Journal of Osseointegration by Ariesdue srl

jo j o u r n a l o f osseointegration

issn 2036-4121 june 2014 n. 2 vol. 6 www.journalofosseointegration.eu

Editorial board editors-in-chief

board of reviewers

Adriano Piattelli

Professor of Oral Pathology and Medicine Dental School, University of Chieti Pescara (Italy) apiattelli@unich.it

Arthur Belem Novaes Jr.

Dental School of Ribeirão Preto, University of São Paulo (Brazil) novaesjr@forp.usp.br

Biomaterials

Yasumasa Akagawa Hiroshima (JPN) Victor Arana Chavez Sao Paulo (BRA) Carlos Roberto Grandini Ilha Solteira (BRA)

Adalberto Luiz Rosa Ribeirão Preto (BRA)

Lior Shapira Jerusalem (ISR) Paulo Tambasco de Oliveira Ribeirão Preto (BRA)

associate editors Biomaterials

Clinical Research

New York (USA)

Rochester (USA)

Biomaterials and Tissue Engineering

Implant Science

Georgios Romanos

Paulo Coelho

Marco Degidi

Jose M. Granjeiro

Bologna (Italy)

Niterói (Brazil)

JosE Luis Calvo Guirado

Murcia (Spain)

Carlo Mangano

Jamil Shibli

Guarulhos (Brazil) Clinical Innovations

Gravedona (Italy) Basic Research

Devorah Schwartz-Arad

Tel Aviv (Israel)

Pablo Galindo Moreno

Granada (Spain)

assistant editors Vittoria Perrotti

Department of Dentistry and Oral Science, Dental School, University of Chieti-Pescara (Italy) v.perrotti@unich.it

Nilson T. C. Oliveira

Departamento de Engenharia de Materiais DEMa / CCDM - Universidade Federal de São Carlos UFSCAR, SP (Brazil) n.oliveira@journalofosseointegration.eu

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Simona Marelli

Sergio Caputi Chieti (ITA) Massimo Del Fabbro Milan (ITA) Carlo Ercoli Rochester (USA) German Gomez-Roman Tübingen (DEU) Ole Jensen Denver (USA) Gregorio Laino Naples (ITA) Voja Lekovic Belgrade (SRB) Eloà R. Luvizuto Araçatuba (BRA) Elcio Marcantonio Jr Araraquara (BRA)

Ziv Mazor Ra'anana (ISR) Valdir Antonio Muglia Ribeirão Preto (BRA)

Joerg Neugebauer Cologne (DEU) Ana Pontes Barretos (BRA) Pâmela L. Santos Araçatuba (BRA) Sérgio L. Scombatti de Souza Ribeirão Preto (BRA) Pascal Valentini Paris (FRA) Paul Weigl Frankfurt am Main (DEU) Implant Science

Carlos R.P. Araujo Bauru (BRA) Bartolomeo Assenza Chieti (ITA) Luigi Califano Naples (ITA) James Doundoulakis New York (USA) Massimo Frosecchi Florence (ITA) Enrico Gherlone Milan (ITA) Ana Becil Giglio New York (USA) Graziano Giglio New York (USA) Luigi Guida Naples (ITA) Giulio Leghissa Milan (ITA) Giuseppe Luongo Naples (ITA) Rogério Margonar Araraquara (BRA) Emeka Nkenke Erlangen (DEU) Marco E. Pasqualini Milan (ITA) Thallita Pereira Queiroz Araraquara (BRA) Lorenzo Ravera Chieti (ITA) Gilberto Sammartino Naples (ITA) Antonio Scarano Chieti (ITA) Tiziano Testori Milan (ITA) Stefano Tetè Chieti (ITA) Clinical Innovations

Zvi Artzi Tel Aviv (ISR) Giuseppe Corrente Turin (ITA) Nilton De Bortoli Jr São Paulo (BRA) Paolo Della Casa Genoa (ITA) Stefano Fanali Chieti (ITA) Carlos Ademar Ferreira Tucuruvi (BRA) Luis Fujimoto New York (USA) Heracles Goussias Athens (GRC) Robert Horovitz New York (USA) Fouad Khoury Münster (DEU) Georg H. Nentwig Frankfurt (DEU) Vula Papalexiou Curitiba (BRA) Waldemar Polido Porto Alegre (BRA) Ludovico Sbordone Pisa (ITA) Aris Tripodakis Athens (GRC)

Francisley Ávila Souza1, Ana Paula Farnezi Bassi1, Alessandra Marcondes Aranega1, Daniela Ponzoni1, Gabriela Bufulin Leonardi2, Fernanda Brasil Daura Jorge Boos3, Eloá Rodrigues Luvizuto4, Heloísa Helena Nímia5, Idelmo Rangel Garcia Júnior1 1

DDS, MS, PhD. Professors of the Surgery and Integrated Clinic Department at the Araçatuba of Dental School – Univ Est Paulista Júlio de Mesquita Filho - UNESP, Brazil 2 Undergraduate Student of the Araçatuba of Dental School – Univ Est Paulista Júlio de Mesquita Filho - UNESP 3 DDS, MS. Student of the Post-Graduation Course in Dentistry, Area of Concentration in Oral and Maxillofacial Surgery and Traumatology of the Araçatuba of Dental School – Univ Est Paulista Júlio de Mesquita Filho - UNESP 4 DDS, MS, PhD. Substitute Professor of the Surgery and Integrated Clinic Department at the Araçatuba of Dental School – Univ Est Paulista Júlio de Mesquita Filho - UNESP 5 Nurse, MS. Professor of Pontifical Catholic University. Puc-Minas, Poços de Caldas, Brasil. Student of the Post-Graduation Course in Nurse of the Guarulhos University – UNG., Brazil

Reconstruction of maxillary ridge atrophy caused by dentoalveolar trauma, using autogenous block bone graft harvested from chin: a case report to cite this article Souza FÁ, Bassi APF, Aranega AM, Ponzoni D, Leonardi GB, Boos FBDJ, Luvizuto ER, Nímia HH, Garcia IR Júnior. Reconstruction of maxillary ridge atrophy caused by dentoalveolar trauma, using autogenous block bone graft harvested from chin: a case report. J Osseointegr 2014;6(2):21-27.

ABSTRACT Background Dentoalveolar trauma, especially when involving front teeth, negatively affect the patient’s life; in particular, tooth avulsion is a complex injury that affects multiple tissues, and no treatment option offers stable long-term outcomes. The aim of this study was to report a case of reconstruction of atrophic anterior alveolar ridge after tooth loss, performed with autograft harvested from the chin, and subsequent prosthetic rehabilitation with the use of an osseointegrated implant. Case report A 23-years-old Caucasian girl, presented an atrophic alveolar bone in the area of tooth 11, as a result of tooth resorption 10 years after a tooth reimplantation procedure. Reconstruction was performed with autogenous bone harvested from the chin. After 6-months healing period to allow autograft incorporation, a dental implant was inserted. After further 6months, a screw-retained implant supported metal-ceramic prosthesis was fabricated. Results The prosthetic rehabilitation was successful, and after a follow-up period of 5 years, the achieved result was stable. Conclusion It can be concluded that the autogenous bone graft harvested from the chin, is a safe and effective option for alveolar ridge defects reconstruction, allowing a subsequent placement of a dental implant supporting a prosthetic restoration.

Keywords Autogenous bone graft; Dentoalveolar traumatism; Osseointegrated implants; Prosthetic rehabilitation; Tooth avulsion.

June 2014; 6(2) © ariesdue

INTRODUCTION Dentoalveolar traumas are very common, and mainly affect children and adolescents. The main causes are car accidents, sporting activities and aggressions. There are some predisposing factors for this condition, such as accentuated overjet, childhood obesity (1), upper lip incapable of covering the anterior teeth, and protrusion of the maxillary central incisor (2). The most common dento-alveolar traumas include fractures, luxations and tooth avulsion; the latter occurs when the tooth is completely forced out of its alveolar socket. The most conservative treatment for avulsion is tooth reimplantation; however, frequently this is not possible, leading to sequelae that include psychological effects on the patient, compromising oral function, esthetics and self-esteem (3), and biological damage to the hard and soft tissues of the affected region (4). Nevertheless, even when reimplantation is performed, the main and most likely complication is tooth resorption, which may trigger extensive bone resorption and severe atrophy of the maxilla (5). This condition makes implants insertion and prosthetic rehabilitations impossible or difficult. In these cases, bone regeneration procedures are mandatory to allow the implant placement in a correct tridimensional situation (6). The goal of bone reconstructions by means of grafts is to re-establish adequate bone dimension, allowing correct rehabilitation with osseointegrated implants (7). Autogenic bone grafts are considered the gold standard among grafting materials in dentistry (8). This is due to their relative resistance to infection, incorporation by the host, without the occurrence of a foreign body reaction (9), in addition to osteogenic, osteoinductive and osteoconductive capacity (8). The

Souza F.A. et al.

autogenous bone graft may be of trabecular, cortical or mixed (osseous coagulum and particulate bone) bone from an intra or extra-oral donor area (10). The main extra-oral donor sites are the iliac crest and calvarium, and the intra-oral sites are the chin, retromolar areas and maxillary tuberosity (11). The use of extra-oral areas involves extensive surgeries, greater morbidity and costs, requiring hospitalization of the patient (12), whereas grafts from intra-oral sources are obtained more easily due to the proximity between the donor and receptor sites, when possible under local anesthesia, and with less discomfort to the patient, in addition to a low resorption potential (8). On the other hand, the main disadvantage of using intra-oral donor areas is the limited quantity of bone tissue available (13). One of the factors to be considered in the choice of donor area is the quantity of bone graft required. Among the intra-oral bone sites, the chin region is one of the most used, particularly in case of receptor areas that need a small quantity of bone volume and small augmentation of the alveolar ridge. The chin presents both cortical and medullary bone types, which ensure good incorporation, rapid revascularization and extremely little loss of grafted bone volume (8, 14). Moreover, it offers a thick block, larger bone volume, and moderate post-operative pain and edema, when compared with other intraoral donor areas (15). The limits of harvesting grafts from the mental symphysis are connected to the presence of the roots of teeth, mental foramen, inferior cortical and lingual cortical borders (16). One of the main limitations of this technique is the proximity to the mental nerve, that could be damaged and cause an alteration of sensitivity (8). At present, there is great concern about the adequate placement of implants, allowing a more functional prosthetic rehabilitation from the biomechanical point of view, and enhanced esthetics, with benefits to the patient’s self-esteem, and a high level of satisfaction. Therefore, the aim of this study was to report a case of reconstruction of atrophic anterior alveolar ridge, performed with autograft harvested from the chin, and rehabilitated with an implant-supported prosthesis.

CASE REPORT Case history

A 23-year-old Caucasian girl, showed attendance at the clinic of Oral and Maxillofacial Surgery of the Araçatuba of Dental School – UNESP, in order to replace a partial fixed adhesive denture on teeth 12, 11, and 21 with an osseointegrated implant. There was absence of tooth 11, lost as a consequence of tooth resorption: the patient had suffered a tooth avulsion at the age of 10 years. On the day of the avulsion the tooth was reimplanted by a dental surgeon specialized in Pediatric Dentistry, in the city where the patient

fig. 1a Adhesive partial denture.

fig. 1b Bone thickness defect.

fig. 2 Initial panoramic radiograph.

was born. She reported that, at that time, the protocol for late reimplantation was performed, with surface treatment of the tooth, endodontic treatment and definitive restoration at the site of the coronal opening. Nine years after, tooth 11 was lost as related by the patient, because it had become mobile, with presence of a purulent exudate. The surgical procedure for extraction was performed by the same clinician and an adhesive fixed partial denture was fabricated on tooth 11, with adhesive abutments on teeth 12 and 21 (Fig. 1a). The patient reported to have used the denture up to the moment of referral, but she complained about the difficulty of cleaning it, and exacerbation of the nasal filter sinking due to the alveolar bone resorption in correspondence of tooth 11. During the clinical intra-oral examination, bone resorption of the vestibular wall was observed, in correspondence of the missing tooth (Fig. 1b). A panoramic radiograph was requested (Fig. 2), in which

Reconstruction of traumatized atrophic ridge with bone block graft. A case report

fig. 3a Mucoperiosteal Incision.

fig. 3b Vestibular wall thickness.

it was possible to observe bone tissue without signs of bone rarefaction, with preserved bone height between the alveolar crest and floor of the nasal fossa. Complementary exams were requested in order to evaluate the patient’s general state of health, which included hemogram, complete coagulogram, fasting glycemia, urea, creatinine and electrolyte dosages (Sodium, Potassium and Calcium); thus, the patient was graded into surgical risk ASA I, in accordance with the American Society of Anesthesiologists (1963). Reconstruction of the alveolar ridge corresponding to tooth 11 was planned, by means of an autogenous bone graft harvested from the chin, with an implant supported prosthetic rehabilitation to be performed at a later date. After the pre-operative review, on the day of surgery, the patient received preventive antibiotic therapy of 2g of Amoxicillin (Amoxicilina, Eurofarma, São Paulo, Brazil) and 5 mg of Diazepam (Valium, Products Roche Chemistry and Pharmaceutics, Rio de Janeiro, Brazil) to control anxiety, in addition to verbal tranquilization throughout the surgical procedure.

Surgical technique

The surgical procedure began with intra-oral antisepsis with 0.12% chlorhexidine digluconate (Periogard, P&G, São Paulo, Brazil), and extra-orally with topical application of 10% PVPI (Riodeine, Rioquímica, São José do Rio Preto), and apposition of sterile fields. Anesthesia was performed with bilateral regional block of the anterior middle superior alveolar nerve, and of the nasopalatine nerve in the maxilla. Similarly, bilateral pterygo-mandibular anesthesia was performed by means of the Smith technique

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of 3 positions (17), in the mandible. In addition, subperiosteal infiltrative terminal anesthesia was also performed in the vestibule of the anterior regions of the maxilla and mandible with the intention of curbing possible hemorrhages. Surgical access began in the receptor area with a Newman mucoperiosteal incision using a scalpel blade (15s, Feather, Feather Safety, Japan) mounted in a scalpel handle (Hu-Friedy, Berlin, Germany), for detachment and exposure of the receptor site (Fig 3a). Extensive bone resorption was observed in the vestibular-palatine direction, proved by the thinness of the receptor site (Fig. 3b). Decortication of the vestibular bone plate was performed by means of a Maxicut spherical bur (Edenta, Zahn-Labor, Labordental, São Paulo, Brazil) and perforations with Bur 702 (Maillefer Instruments, Ballaigues, Switzerland), mounted in a straight multiplicator handpiece (Kavo do Brasil, Joinvile, Brazil) with electric motor (Kavo do Brasil, Joinvile, Brazil), under constant irrigation with 0.9% physiological solution (Darrow, Rio de Janeiro, Brazil). An incision was made in the mucosa at the depth of the anterior vestibular fornix, then a perpendicular mucoperiosteal incision to detach and expose the chin donor area was performed (Fig. 4a). The size of the graft necessary for the reconstruction was delimited in the donor area (Fig 4b), followed by monocortical osteotomy (Fig. 4c), performed with Bur 702. The monocortical block bone graft was removed with the aid of Wagner chisels and hammer (Quinelato, São Carlos, Brazil), as shown in Figure 4d. The recipient site was shaped for passive graft accommodation insertion (Fig. 5a) and fixation by means of 2 bicortical screws measuring 1.3x11.0 mm (SIN, Sistema de Implante Nacional, São Paulo, Brazil) (Fig. 5b). The desired thickness achieved after performing the graft can be noted (Fig. 5c). Then, the sharp angles were rounded off in order to avoid possible exposure and/or fenestrations and the area was sutured with simple “U”-shaped stiches, using 5.0 nylon thread (Mononylon, Ethicon, Johnson, São José dos Campos, Brazil). Moreover, the acute edges of the donor area were rounded off; the muscle plane was sutured with Polyglactin thread 910 (Vicryl 5.0, Ethicon, Johnson, São José dos Campos, Brazil) and the mucosal plane with 5.0 nylon thread (Fig. 5d). After suturing, a compressive micropore dressing was placed (Johnson & Johnson, São José dos Campos, Brazil) on the chin and upper lip, and kept in place for 24 hours. A maintenance therapy prescription was prescribed, with 500 mg Amoxicillin (Amoxicilina, Eurofarma, São Paulo, Brazil) every 8h for 7 days, 100mg Nimesulide (Nimessulida, Medley, Campinas, Brazil) every 12h for 3 days, in addition to pain control with 500 mg Sodium Dipyrone (Dipirona Sódica, Eurofarma, São Paulo, Brazil) every 6h in case of pain. Furthermore, the patient was instructed to perform a careful oral hygiene with moderate topical

Souza F.A. et al.

fig. 4a Access to donor site.

fig. 4b Delimitation of bone graft.

fig. 4c Osteotomy of bone graft.

fig. 4d Removal of bone graft by means of chisels.

fig. 5a Passive accommodation of bone graft in receptor area.

fig. 5b Fixation of bone graft in receptor area.

fig. 5c Desired thickness achieved.

fig. 5d Suturing of receptor and donor areas.

mouth washes with 0.12% Chlorhexidine Digluconate (Periogard, P&G, São Paulo, Brazil) starting on the day after surgery. On the same day, the adhesive prosthesis was bonded with resin cement. After 14 days, the sutures were removed and the wound was inspected to detect any infections and dehiscences. The patient was visited at least once per month until implant surgery.

Implant placement

After 6 months the patient was submitted to the same pre-operative and surgical procedures, as previously

described. After exposure of the reconstructed area, the 2 bicortical stabilization screws of the graft were removed and remodeling of the bone graft in the reconstructed area was observed (Fig. 6). The bone graft was fixed to the residual bone with absence of mobility, indicating that incorporation had occurred. Therefore, in this area, a cylindrical dental implant with a hexagon connection (SIN, Sistema de Implante Nacional, São Paulo, Brazil) measuring 4.0x13.0 mm was placed (Fig. 7). Thus, the patient’s adhesive denture was bonded with resin cement, in order to avoid any interference in the peri-implant mucosa.

Reconstruction of traumatized atrophic ridge with bone block graft. A case report

fig. 6 Remodeling of bone graft after 6 months.

fig. 7 Implant placement.

• Absence of bone resorption of the graft.

Implant osseointegration

There was successful implant osseointegration into the area reconstructed with the autogenous block bone graft harvested from chin, as the clinical and radiographical results satisfied the criteria for evaluation of implant survival suggested by Chiapasco et al. (18): • Absence of persistent pain or dysesthesia; • Absence of peri-implant infection with suppuration; • Absence of vertical or horizontal implant mobility after masticatory force; • Absence of continuous peri-implant radiolucency.

Prosthetic results

After a follow-up period of 5 years, stability of the result achieved was assessed by means of clinical (Fig. 9) and radiographical (Fig. 10) evaluation.

fig. 8 Provisional resin composite denture on implant.

DISCUSSION The most conservative treatment for tooth avulsion is tooth reimplantation (5), with success rate ranging from 4% to 50% (19). When failure occurs, it is almost always associated with tooth and bone resorption (4); these bone defects are not only due to dento-alveolar traumas, but also could be a consequence of diseases, surgeries, tooth extractions or physiological resorption that may affect bone quantity, height and volume (7). The most common surgical procedure for reconstruction

Suture removal was performed 7 days after implant placement.

fig. 9 Screwretained definitive crown after five years follow-up.

Prosthetic rehabilitation

After further 6 months, a new panoramic radiograph was taken to evaluate the implant osseointegration, and the absence of bone resorption. Re-opening of the implant site was performed, and transfer molding with square transfer coping (SIN, Sistema de Implante Nacional, São Paulo, Brasil) was placed. A provisional screw-retained resin denture (Fig. 8) was screwed with a torque of 10 N/cm. Then, a definitive metal ceramic screw-retained denture was delivered.

Surgical reconstruction

There was incorporation of the block bone graft harvested from chin in the receptor site (maxilla), as the clinical and radiographical results showed: • Absence of persistent pain, dysesthesia or infection with suppuration in the donor site or reconstructed area. • Absence of bone graft mobility during implant placement.

June 2014; 6(2) © ariesdue

fig. 10 Five years follow-up panoramic radiograph.

Souza F.A. et al.

of such areas is bone grafting, for which materials of autogenous, allogeneic, xenogenic and synthetic origin are used. In this case report, autologous bone was chosen due to its osteogenicity. In the literature, autogenous bone grafting has been established as the best material for reconstructions, because it has live immunocompatible bone cells that are essential in the early stages of osteogenesis (20) and allows a better incorporation into the receptor site (8). Among the donor areas for autografts, intraoral sites are preferred to extraoral ones due to their convenient access, proximity between the donor and receptor sites, lower degree of morbidity after graft harvesting and minimum discomfort to the patient (21). However, in some cases it is not possible to use intraoral donor areas, particularly when a large quantity of bone is required. In case of single tooth area replacement, partial anterior reconstructions, or sinus membrane elevation in a single maxillary sinus (14, 22), the intraoral donor site provides a sufficient quantity of bone to reconstruct the alveolar defect. Some authors (23, 24) reported that bone harvested from the mandible offers benefits inherent to its embryological origin, such as small loss of grafted bone volume and good incorporation into the host. Moreover, others authors (25, 26) showed that a low level of grafted bone resorption occurs due to the microarchitecture of the mandibular cortical and trabecular bone plates. In the present case report, there was a considerable bone graft remodeling due the receptor site condition, where a high level of bone resorption occurred as a result of dento-alveolar trauma. A previous study (27) reported that bone resorption level after alveolar ridge (maxillary sites) augmentation with mandibular block bone graft represents 20% of initial volume for lateral augmentation and up to 41.5% in case of vertical augmentation. The chin region as a donor site in bone grafting procedures offers a low degree of morbidity (28), relatively good bone quantity and quality due to the presence of cortical and medullary bone (21), in addition to a small loss of bone volume when grafted. In this case report, the chin was used as donor site due to the cortical-medullary anatomic characteristics of the graft, thus providing a reconstruction with greater bone volume in the reconstructed area, where there was extensive bone resorption. For a good integration of the grafted bone tissue into the receptor bed and its good vascularization (29), the surgical site should be immobilized, avoiding obstacles during its healing phase. The placement of a temporary prosthetic (adhesive fixed denture), both during graft incorporation and implant osseointegration, allowed healing of the treated site without interferences or loading. Implant placement soon after incorporation of the graft has a stimulating effect on bone, maintaining its

volume and preventing subsequent bone loss (12, 30). For this reason, in the case here reported, the implant was placed six months after the bone graft, which corresponded to the final stage of autogenous bone grafts incorporation (8). In relation to the success of bone grafting procedures, many studies report that surgical techniques performed, donor site, recovery time, and time of implant placement are also crucial.

CONCLUSION It can be concluded that the autogenous bone graft harvested from the chin is a safe and effective option for alveolar ridge defects reconstruction, allowing a further placement of dental implant supporting a prosthetic restoration.

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24. Zins JE, Whitaker LA. Membranous vs. endochondral bone autografts: implications for craniofacial reconstruction. Surg Forum 1979;30:521-523. 25. Misch CM, Misch CE, Resnik RR, Ismail YH. Reconstruction of maxillary alveolar defects with mandibular symphysis grafts for dental implants: a preliminary procedural report. Int J Oral Maxillofac Implants 1992;7:360366. 26. Ozaki W, Buchman G. Investigation of the influence of biomechanical force on the ultrastructure of human sagittal craniosynostosis. Plast Reconstr Surg 1998;102:1385-1394. 27. Cordaro L, Amadé DS, Cordaro M. Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement. Clin Oral Implants Res 2002;13:103-11. 28. Schliephake H, Kroly C, Wustenfeld H. Experimental study by fluorescence microscopy and microangiograph of remodeling and regeneration of bone inside alloplastic contour augmentation. Int J Oral Maxillofac Implants 1994;23:300-305. 29. Branemark PI, Adell R, Albrektsson T, Lekholm U, Lundkvist S, Rockler B. Osseointegrated titanium fixtures in the treatment of edentulousness. Biomaterials 1983;4:25-28. 30. Lidstrom RD, Symington JM. Osseointegrated dental implants in conjunction with bone grafts. Int J Oral Maxillofac Surg 1988;17:116-118.

C. Mangano1, F. Luongo2, F. G. Mangano3, A. Macchi4, V. Perrotti5, A. Piattelli6 1

MD, DDS, Assistant Professor and Head of Oral Surgery, Department of Surgical and Morphological Sciences, Dental School, University of Varese, Italy 2 DDS, Private Practice, Rome, Italy 3 DDS, Research Fellow, Department of Surgical and Morphological Sciences, Dental School, University of Varese, Italy 4 DDS, Full Professor, Department of Surgical and Morphological Sciences, Dental School, University of Varese, Italy 5 DDS, PhD, Research Fellow, Department of Medical, Oral and Biotechnological Sciences, Dental School, University of Chieti-Pescara, Italy 6 MD, DDS, Full Professor, Department of Medical, Oral and Biotechnological Sciences, Dental School, University of Chieti-Pescara, Italy

Wide-diameter locking-taper implants: a prospective clinical study with 1 to 10-year follow-up to cite this article Mangano C, Luongo F, Mangano FG, Macchi A, Perrotti V, Piattelli A. Wide-diameter lockingtaper implants: a prospective clinical study with 1 to 10-year follow-up. J Osseointegr 2014;6(2):28-36.

Keywords Complications; Locking-taper implants; Long-term prospective clinical study; Survival; Wide-body implants.

ABSTRACT

INTRODUCTION

Aim Wide-diameter implants (WDIs, diameter ≥4.5 mm) are increasingly being used in patients with poor bone quality and reduced bone height. The aim of this study was to evaluate the survival rate, peri-implant bone loss, biological and prosthetic complications of wide-diameter (4.8 mm) lockingtaper implants used in the restoration of partially and fully edentulous patients. Materials and methods Between January 2002 and December 2011, all patients referred to a private clinic for treatment with WDIs were considered for inclusion in the study. At each annual follow-up session, clinical and radiographic parameters were assessed: the outcome measurements were implant failure, peri-implant bone loss (distance between the implant shoulder and the first visible bone-to-implant contact: DIB), biological and prosthetic complications. The cumulative survival rate (CSR) was assessed using the KaplanMeier estimator; Log-rank was applied to evaluate correlations between the study variables. The statistical analysis was performed at the patient and at the implant level. Results A total of 438 WDIs were placed in 411 patients. Four implants failed, for a CSR of 99% (patient-based) and 99.1% (implant-based) at 10-year follow-up. The CSR did not differ significantly with respect to patients’ gender, age, smoking or parafunctional habit, implant location, position, length, bone type or prosthetic restoration. A mean DIB of 0.34 mm (± 0.23), 0.45 mm (± 0.27) and 0.75 mm (± 0.33) was shown at the 1-, 5- and 10-year follow-up examination. Conclusions Wide-diameter, locking-taper implants can be a good treatment option for the rehabilitation of partially and fully edentulous patients over the long term.

Wide-diameter implants (WDIs) are defined as implants with 4.5 mm diameter or more (1,2). They were originally introduced in 1993 as rescue implants, used for immediate replacement of non-osseointegrated or fractured fixtures to allow adequate anchorage in cases of over-enlarged sites, and to expand implant placement in posterior areas with poor bone quality and limited height (3-5). Nowadays, WDIs are the first choice in situations such as fresh extraction sockets, and are increasingly being used for implantation in patients with poor bone quality, reduced bone height and habit of bruxism (6-10). The use of WDIs may enhance bicortical stability, and increase the surface available for osseointegration (6-11). In fact, WDIs are often used to be placed immediately in extraction sockets because they increase stability by reaching the socket wall (2,10); in addition, they may improve bone-to-implant contact (BIC) due to the increased implant surface area (6-11), which could enhance the osseointegration of implant to bone and establish implant stability (10), compensating for the lack of bone height or density (11). Moreover, their larger surface area enhances connectivity with the surrounding bone and shows an anchorage strength 3- to 6-fold of that of standard diameter implants (1215). Several experimental studies indicated that WDIs are associated with increased removal torque values and that the load on cortical bone decreases with increasing the implant diameter (12-15). A WDI may better bear the occlusal loading, as compared to a standard (3.75- 4 mm) diameter implant, being biomechanically

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Wide diameter implants: a prospective clinical study at 10 years

more effective in counteracting occlusal forces of the magnitude that may be exerted in the posterior region, particularly in molar areas (12-14). A better distribution of occlusal forces and the possibility to use wider prosthetic components may reduce the risk for mechanical complications, such as abutment screw loosening or fracture (12-15). Despite encouraging data obtained from finite element analysis and animal studies (11-15), early publications on WDIs reported an increased failure rate compared to standard diameter implants (3,5,16-19). More recently, several short-term studies on WDIs have been published, showing favorable survival rates (2,7,8,10). However, there is no abundance of studies evaluating the long-term (≥10 years) clinical outcome of WDIs (6,20,21). More than 20 years ago, locking taper implants have been introduced as an alternative to screw-retained abutment systems (22,23). Locking-taper implants are composed of a fixture and an abutment joined together by a Morse taper connection; this tapered fit implantabutment connection is able to induce a self-locking mating between the components (22-25). Several studies demonstrated that locking-taper implants can represent a successful treatment modality for the rehabilitation of partially and completely edentulous patients (22-25). The aim of the present prospective study was to evaluate the survival rate, peri-implant bone loss, biological and prosthetic complications of wide-diameter (4.8 mm) locking-taper implants used in the rehabilitation of partially and fully edentulous patients over the long term.

MATERIALS AND METHODS Patient selection

Over a 10-year period (January 2002-December 2011) all patients referred to a private clinical center for treatment with dental implants were considered for inclusion in this study. Inclusion criteria were: age >18 years, fully or partially edentulous patients, >6 weeks of healing after tooth extraction, placement of widediameter (4.8 mm) dental implants, good systemic and oral health, dentition in the opposing jaw to have occlusal contacts. Exclusion criteria were: unsatisfactory oral hygiene, active periodontal infections or other oral disorders, insufficient bone volume to place widediameter (4.8 mm) implants, with at least 8 mm in length, bone augmentation procedures with autogenous bone or bone substitutes, uncontrolled diabetes mellitus, severe systemic pathologies that would contraindicate implant placement, coagulation disorders, irradiated bone, psychologic disorders, alcohol or drug abuse. Smoking and bruxism were recorded but were not an exclusion criteria for this study. All patients who smoked were defined as smokers, without considering

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the amount of cigarettes; these patients were told that smoking is associated with an increased implant failure rate. Bruxers were patients with a repetitive jawmuscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Patients' questionnaires, clinical examination and electromyography were used for the diagnosis of bruxism (26). The study protocol was explained to each participant, and each patient was required to sign an informed consent. The patients agreed to participate in a post-operative control program. The study was carried out in accordance with the principles outlined in the Declaration of Helsinki on experimentation involving human subjects, as revised in 2000, and approved by the Ethical Committee of the University of Insubria, Varese, Italy.

Implant design and surface characterization

Screw-shaped, wide-diameter (4.8 mm) implants made of grade-5 titanium alloy (Leone Implant System, Florence, Italy) were used. The surface of these implants is blasted with 50 micro-meters Al3O2 particles and acidetched with HNO3, after which the average of roughness (i.e., the mean of the peak-valley distance on surface irregularities) is 0.5 micrometers. This implant system uses a Morse taper implant-abutment connection combined with an internal hexagon; the Morse taper has an angle of 1.5°.

Preoperative study

Before implant placement, an accurate examination of the hard and soft tissues was carried for all patients; the presence of periodontal disease, caries, soft tissue disorders was investigated, and patients received appropriate treatments and oral hygiene instructions. Panoramic radiographs were the basis for the initial investigation; in a few selected cases, cone beam computed tomography (CBCT) scans were used. CBCT datasets were acquired and then transferred to specific implant navigation softwares (Mimics®; Materialise, Leuven, Belgium), where a three-dimensional (3D) reconstruction of the jaws was performed. With these softwares, it was possible to correctly plan the implant position, depth and angulation, by assessing the width of each implant site, the thickness and the density of the cortical plates and the cancellous bone, as well as the ridge morphology. Pre-operative study also included an assessment of the edentulous ridges using casts and diagnostic wax-up.

Implant placement

After local anesthesia, obtained by infiltration of articaine (4%) containing 1:100.000 adrenaline, a midcrestal incision was made at the site of implant installation. The mesial and distal aspects of the crestal incision were connected to two releasing incisions. A full thickness flap was reflected exposing the alveolar ridge, and

Mangano C. et al.

preparation of implant sites was carried out with spiral drills of increasing diameter, under constant irrigation, as previously reported (23,24). The implants were placed in the prepared sites, achieving good primary stability, with the neck located at the bone crest level. Finally, sutures were performed. All patients were prescribed antibiotics, amoxicillin + clavulanic acid 2 g each day for 6 days. Postoperative pain was controlled with 100 mg nimesulide every 12 hours for 2 days. Patients received detailed instructions on oral hygiene, with mouth rinses containing 0,12% chlorhexidine administered for 7 days. Sutures were removed after 8-10 days.

Prosthetic procedures

A two stage technique was used and the implants were left submerged during the healing period, ranging from 3 months in the mandible to 4 months in the maxilla. The prosthetic rehabilitations were single crowns (SCs), fixed partial prostheses (FPPs), fixed full-arches (FFAs) and overdentures (ODs). Second-stage surgery was conducted to be able to access the submerged implants and healing abutments were placed. The flap was adjusted to the healing abutment and sutured in position. Two weeks after the second surgery, in all fixed restoration protocols (SCs, FPPs, and FFAs), the abutments were connected and provisional acrylic restorations were provided. These restorations remained in situ for 3 months, in order to monitor the implants’ stability under load and to obtain good softtissue healing around the implants; after this period, definitive ceramo-metallic restorations were provided, cemented with temporary cement. All the restorations were carefully evaluated for proper occlusion, and protrusion and laterotrusion were assessed on the articulator and intraorally. Finally, in patients with implant-supported overdentures (ODs), the prosthodontic procedure was achieved as previously described (27). Patients wore provisional complete dentures, relined with a tissue conditioner, for a 3-month period; after that, second-stage surgery was then conducted to gain access to the underlying implants, and the healing abutments were inserted. Two weeks later, the healing abutments were removed, pick-up impression posts were placed at the implant level and an impression was taken; a master cast was poured, and a rigid gold bar was fabricated. The fixtures were elongated with pre-fabricated abutments to the top of which gold copings were screwed. The splinting superstructures for the implants consisted of an eggshaped Dolder gold bar, with or without extensions. All these bars were supported by 3-4 fixtures. All ODs had a horseshoe design and were fabricated with acrylic resin with a metal framework. Retention of the superstructure was ensured by several pre-fabricated gold clips. The ODs were carefully evaluated for proper occlusion and protrusion and laterotrusion were assessed on the articulator and intraorally.

Follow-up examinations

The patients were enrolled in an annual recall program. During each annual follow-up visit, the clinical assessment of implants, peri-implant tissues and prostheses were performed by a surgeon and a prosthodontist, who were not directly involved in the study. The outcome measurements were as follows. › Implant failure. Failure to osseointegrate with implant mobility, persistent peri-implant infections with pain/ suppuration, progressive marginal bone loss due to mechanical overload and implant body fracture were the conditions for which implant removal was indicated (28). The implant failures were divided into early (before the abutment connection) and late (after the abutment connection) failures. › Peri-implant bone loss. Intraoral periapical radiographs were taken for each implant, using a Rinn alignment system with a rigid film-object x-ray source coupled to a beam-aiming device to achieve reproducible exposure geometry (29). Customized positioners, made of polyvinyl-siloxane, were used for precise repositioning of the radiographic template. Radiographs were taken immediately after implant placement and at each annual follow-up session, with the aim to: evaluate the presence/ absence of continuous peri-implant radiolucencies; measure the distance between the implant shoulder and the first visible bone-to-implant contact (DIB) in mm, at the mesial and distal site of each implant (29). For the latter, measurements were made by means of an ocular grid; the following equation: “rx implant length : true implant length = rx DIB : true DIB” was used to correct potential distortions in the radiograph, and to establish with precision the amount of vertical bone loss at the mesial and distal site of the implant (29). A mean DIB value was obtained from the mesial and distal measurement at each radiograph. In the present study, modifications in the distance from the implant shoulder to the first visible bone-to-implant contact (DIB) were measured on periapical radiographs which were taken immediately after installation and at the 1-, 5- and 10-year follow-up examination. › Complications, which were divided into two types: a) biological complications, including the disturbances in the function of the implant characterized by a biological process affecting the supporting tissues and structures (pain or swelling after surgery, soft tissue inflammation and peri-implant infection with fistula formation, pain, suppuration or exudation, discomfort on occlusion). The threshold to define a peri-implantitis was set at a probing pocket depth ≥6 mm and bleeding on probing or pus secretion; b) prosthetic complications, related to implant components (mechanical complications, such as loosening or fracture of abutment) or prostheses (technical complications, such as loss of retention

Wide diameter implants: a prospective clinical study at 10 years

or porcelain fracture) for fixed restorations, and anchorage structure (broken bars, or loose, lost, or broken bar retainers) or prostheses (repairs of fractured prostheses or overdenture teeth) for removable restorations. Static and dynamic occlusion were evaluated, using standard occluding papers; all prosthetic complications were carefully registered, and if possible, managed during the follow-up visit; additional appointments were arranged if needed.

intermediate between those described for types II and IV, the bone was categorized as type III. Log-rank test was used to evaluate the correlations between the study variables. Data analysis was performed with a statistical software package (SPSS 17.0, SPSS Inc, Chicago, IL, USA). The level of significance was set at 0.05.

Statistical analysis

In total, 411 patients (235 males and 176 females; aged between 24-73 years, mean 47.6 ± 9.0) were enrolled in the present study. Among these patients, 58 (14.1%) were smokers and 29 (7.0%) were bruxists. The average follow-up time was 6.1 ± 2.7 years. Twenty-one patients had multiple indications for implant therapy. A total of 438 WDIs were placed. One-hundred and ninety-one implants (43.6%) were inserted in the maxilla, while 247 implants (56,4%) were inserted in the mandible. With regard to the position of the installed implants, 12 (2.8%) were incisors, 18 (4.1%) were cuspids, 134 (30.5%) were premolars and 274 (62.6%) were molars. The detailed distribution of the implants according to the position is reported in figure 1. Regarding bone quality, most of the implants were inserted in posterior areas of lower density, with 232 implants (53.0%) placed in bone type III, and 121 implants (27.7%) placed in bone type IV; only 80 implants (18.2%) and 5 implants (1.1%) were placed in bone type II and I, respectively. The most frequently used implant length was 12 mm, with 195 implants (44.5%), followed by 10 mm, with 135 implants (30.9%); 54 implants (12.3%) were 8 mm and 14 mm long. Finally, the most frequent indication was the restoration of single-tooth

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Patient population and implant-supported restorations

133 maxilla mandible Numbers of implants

Data collection and analyses were performed by two independent examiners (a surgeon and a prosthodontist) who were not directly involved in the treatment of patients. Data were tabulated and analysed by means of Microsoft Excel Software 2003. A descriptive analysis was performed for patient demographics, distribution of implants, radiographic bone loss, biologic and prosthetic complications. Absolute and relative frequency distributions were calculated for qualitative variables, and means, standard deviations (SD), median, range and confidence intervals (CI: 95%) were calculated for quantitative variables. Implant failure was the principal variable of the study, and implant survival rates were calculated using Kaplan-Meier survival curves (30). Each implant was followed from the date of placement to either the date of failure or the date of last followup. The cumulative survival rate (CSR) was estimated both by a patient-based and an implant-based analysis. In the implant-based analysis each inserted implant was considered as the analysis unit. In the patientbased analysis, each patient was considered as the analysis unit: in case of multiple indications for implant therapy (with the same patient receiving more than one implant), the patient was classified as a failure even in the event of a single implant loss. Variables including gender, age at surgery, smoking habit (smokers or non-smokers); parafunctional habits (bruxists or nonbruxists) were analyzed at the patient-level. Variables including implant location (mandible or maxilla), implant position (incisors, cuspids, premolars or molars), implant length (8.0, 10.0, 12.0 or 14.0 mm), type of prosthetic restoration (SCs, FPPs, FFAs or ODs) and bone type (type I, II, III or IV) were analysed at the implantlevel. Bone quality was ascertained clinically by tactile evaluation at the time of implant placement, during drilling, according to the clinician’s judgment and by radiographic assessment according to the criteria of Lekholm and Zarb index (31). In particular, following the withdrawal of an osteotomy reamer, an assessment of the bone in the reamer flutes was conducted in terms of quality and appearance. Bone quality was classified as type I if the bone was compact, cortical and nearly bloodless. Type II bone was red and filled the flutes of the reamer. If no bone remained in the flutes, the bone quality was classified as type IV. If the findings were

RESULTS

73 54

51 33

4 central incisor

lateral incisor

10 8 cuspids

first second premolars premolars

12 first molars

second molars

fig. 1 Implant distribution by location.

Mangano C. et al.

gaps (235 implants, 53.7%), whereas the least frequent indication was the treatment of fully edentulous patients with ODs (21 implants, 4.8%); a total of 132 implants (30.1%) were installed to support FPPs, while 50 implants (11.4%) were used to support FFAs.

Cumulative survival rate (maxilla vs mandible)

Survival rate (implant-based)

1.000

Implant survival

0.995

0.990

0.985

0.980 0.00

20.00

40.00 60.00 80.00 Follow-up (months)

100.00

120.00

maxilla maxilla-t mandible mandible-t

fig. 2 Survival rate with Kaplan Meier estimates.

Failures 1 Patient details Female Gender 54 Age No Smoking No Bruxism Implant details Mandible Location Premolar Position Type III Bone type 14.0 mm Length Restoration FPP Failure details 3 months Time of failure Implant Failure mobilityreason

lack of osseointegration

Male

Yes

Maxilla

Premolar

Molar

Type IV

10.0 mm

12.0 mm

8.0 mm

FPP

4 months

Implant mobilitylack of osseointegration

tabLE 1 Details of the failed implants.

Four implants failed and were removed, in 4 different patients. Eleven of the 411 patients were classified as drop-outs, since they did not participate in the postoperative control program in full. At the end of the study, an overall CSR of 99.0% (patient-based) and 99.1% (implant-based) were achieved at 10-year followup, with 434 implants still in function. In the maxilla, the CSR was 98.4%, with 3 implants failed and removed. In the mandible, the CSR was 99.6%, with one implant failure (Fig. 2). With regard to the position of the failed implants, 2 were premolars (1 maxilla, 1 mandible) and 2 were molars (2 maxilla). All implants were lost within the healing period (3-4 months after surgery), before the abutment connection. For this reason, they were classified as “early failures”, showing implant mobility due to lack of osseointegration, before functional loading, with no signs of peri-implant infection. No implants failed after the abutment connection, or after prosthetic loading, so that no “late failures” were found. The details of the failed implants are recorded in table 1. The survival rate did not differ significantly with respect to patients’ gender, age, smoking or parafunctional habit, implant location, position, length, bone type or prosthetic restoration. The

N° of Failures Kaplan- Logpatients Meier (%) rank Patients gender Males 235 3 98.7 0.473 Females 176 1 99.4 Patients age 24-34

100

35-44

108

100

45-54

175

98.3

55-64

100

99.0

65-

100

98.3

99.2

100

99.0

0.675

Smoking Smokers

Non-smokers 353

0.532

Bruxism Bruxists

Non- bruxists 382

0.581

tabLE 2 Patient-based analysis.

Wide diameter implants: a prospective clinical study at 10 years

evaluation of the influence of different patient-related and implant-related variables on implant survival is reported in table 2 and table 3, respectively.

0.34 mm (± 0.23), 0.45 mm (± 0.27) and 0.75 mm (± 0.33) at the 1-, 5- and 10-year follow-up examination, respectively (Tab. 4; Fig. 3, 4).

Peri-implant bone loss

Complications

The mean distance between the implant shoulder and the first visible bone-to-implant contact (DIB) was

N° of Failures Kaplan- Logimplants Meier (%) rank Implant position Maxilla 191 3 98.4 0.206 Mandible 247 1 99.6 Implant location Incisors

100.0

Cuspids

100.0

Premolars

134

98.5

Molars

274

99.3

0.931

After surgery, 4 patients treated with a single implant experienced severe swelling and pain; three months after, one of these patients experienced implant failure. Two implants were diagnosed with peri-implantitis, showing suppuration/exudation, bleeding on probing and a probing pocket depth ≥6 mm, 6 years after placement; however, these implants were successfully treated and no further biological complications were reported. In total, the overall incidence of biological complications was 1.3%. With regard to prosthetic complications with fixed restorations (SCs, FPPS and FFAs: 417 surviving implants), all complications were technical in nature (loss of retention, porcelain fracture). In fact, the most frequent complication was loss of retention, which occurred in 16

Implant length 8.0 mm

98.1

10.0 mm

135

99.3

12.0 mm

195

99.5

14.0 mm

98.1

0.877

Bone quality Type I

100.0

Type II

100.0

Type III

232

99.6

Type IV

121

97.5

Fig. 3A

Fig. 4A

Fig. 3B

Fig. 4B

Fig. 3C

Fig. 4C

Fig. 3 A Periapical radiographs of a WDI placed in the maxilla: 1-year follow-up. b. Periapical radiographs of a WDI placed in the maxilla: 5-year follow-up. c. Periapical radiographs of a WDI placed in the maxilla: 10-year follow-up.

Fig. 4 A Periapical radiographs of a WDI placed in the mandible: 1-year follow-up. b. Periapical radiographs of a WDI placed in the mandible: 5-year follow-up. c. Periapical radiographs of a WDI placed in the mandible: 10-year follow-up.

0.054

Type of restoration SCs

235

99.1

FPPs

132

98.5

FFAs

100.0

ODs

100.0

0.686

tabLE 3 Implant-based analysis.

Year 1

Mean

Median

CI (95%)

0.34

0.23

0.4

0.32-0.36

0.45

0.27

0.4

0.43-0.47

0.75

0.33

0.7

0.66-0.84

tabLE 4 Peri-implant bone loss (in mm).

Mangano C. et al.

implants during the observation period (3.8%); moreover, 7 (1.6%) porcelain fractures occurred. No mechanical complications (loosening or fracture of abutment) were reported. In total, the overall incidence of prosthetic complications for fixed restorations was 5.5%. With removable prostheses (ODs: 21 surviving implants), all the complications were related to the weakness of the anchorage components used for connecting the bar to the denture. In fact, no complications related to implant components (loosening or fracture of abutment) were reported. In total, 9 clip loosenings and 4 clip fractures were recorded; in addition, in 3 patients, acrylic resin or tooth fractures were encountered. All these prosthetic complications were managed during the follow-up visit where possible; additional appointments were arranged when major repairs were needed.

DISCUSSION The initial experience with machined-surface WDIs showed lower success rates than those reported for standard-sized implants (3,5,16). In 1993, Langer and co-workers introduced a new 5 mm diameter implant and recommended its use as rescue implant for immediate replacement of non-osseointegrated or fractured regular implants (3). Due to the larger surface area, this WDI was also recommended for use in areas of compromised bone quality and quantity. Unfortunately, a high overall implant failure rate of 13% to 25% was described for WDIs in this 3-year follow-up study (3). In 1998, Aparicio and Orozco reported a cumulative success rate of 97.2% for WDIs in the maxilla and 83.4% in the mandible, with a mean post-loading follow-up of 33 months (5). Extremely low survival rate (82%) of WDIs have also been described by Ivanoff and associates: reporting on the influence of variations in Brånemark implant diameter in a 3- to 5- year retrospective clinical study, the authors found the highest implant failure rate (18%) for 5 mm diameter implants, compared with 3% for 4 mm wide implants and 5% for the 3.75 mm diameter implants (13,16). However, only 10% of the WDIs used in this study had a length >10 mm, as the implants studied were predominantly short widebody implants (6 to 8 mm long) (6, 16). Eckert and colleagues also found statistically higher failure rates for WDIs in both maxilla (29%) and mandible (19%); according to the authors, a critical bone volume was needed for osseointegration, which was sometimes hampered by WDIs (17). Similar results were reported in a retrospective study by Shin and colleagues, with survival rates of 80.41% and 96.8% for wide- and regular-body implants, respectively (18); in 2004, Hultin-Mordenfeld and co-workers reported a higher implant failure rate with WDIs, with better results in the mandible (94.5%) than the maxilla (78.3%) (19). Although initially higher failure rates for WDIs were

reported, recently improved surgical procedures, new implant design and surface configurations have demonstrated that wide implant body and lower survival rates are not related (6-10,20,21,29,32). In a retrospective study on 131 WDIs with a mean loading time of 17 months, Khayat and colleagues found an overall survival rate of 95% (7). Similar results were reported by Friberg and colleagues, with a loss rate of 4.5% for WDIs (5 mm) and no differences in survival rates between 5 mm, 4 mm and 3.75 mm implants (32). In a retrospective study on 168 hydroxyapatite (HA)coated WDIs placed in posterior areas with reduced bone height, Griffin and Cheung reported a survival rate of 100% after 35 months of loading (33). More recently, several studies have reported failure rates of less than 5% up to 5 years of function (20,21). However, the longterm (≥10 years) observation on WDIs is still missing, and details of survival, success and complications of this treatment modality in the long-term are still unknown. In our present prospective study on 438 WDIs placed in 411 patients, an overall CSR of 99% (patient-based) and 99.1% (implant-based) was achieved at 10-year followup. Four implants failed; all these implants were lost within the healing period (before functional loading) and were classified as “early failures”, showing implant mobility due to lack of osseointegration, with no signs of peri-implant infection. These results are in accordance with those of previous studies, in which a prevalence of early failures was reported (7,20,21,32,33). The CSR of WDIs was compared in terms of different subgroups, and it did not differ significantly with respect to patients’ gender, age, smoking or parafunctional habit, implant location, position, length, bone type or prosthetic restoration. With respect to the patientbased analysis, one implant failure due to lack of osseointegration was found among smoking patients in our study, giving a CSR of 98.3% for smokers. Smoking is a well-documented risk factor for implant failure (34), however no statistically significant difference in survival rate was found between smokers and non-smokers in this study (p=0.532). Bruxists had a very high 10-year CSR (100%). This result could suggest that the use of WDIs may be helpful in case of parafunctional habits; it should be noted, however, that the number of bruxists in the present study was low (29). With regard to the implant-based analysis, in the present study, the CSR of WDIs in the mandible (99.6%) was shown to be slightly higher than in the maxilla (98.4%). The higher bone density of the mandible was probably the reason for the better outcomes, as previously reported (19). In the present study, a lower CSR (97.5%) was found in regions with poor bone quality (type IV; p=0.054), with 3 implants failed in the posterior maxilla. Bone in the posterior jaw region is more commonly type III or type IV, especially in the maxilla: according to the literature, implants in poorer quality bone have a higher failure rate (2,35).

Wide diameter implants: a prospective clinical study at 10 years

The locking-taper implant system used in the present study is composed of a fixture and an abutment joined together by a self-locking connection by means of a Morse taper guided by an internal hexagon. The Morse taper has a angle of 1.5°, and is able to induce a self-locking mating between the parts, thus giving a higher implant-abutment mechanical stability (2225,36). Recent researches have shown that the use of locking taper implants can effectively reduce the incidence of prosthetic complications at the implantabutment interface, by resisting eccentric loading complexes and bending moments, ensuring excellent mechanical stability (22-25,36,37). In our present study, no technical complications related to implant components (loosening or fracture of abutment) were reported, both for fixed and for removable restorations. This seems to confirm previous results obtained with locking-taper implants (22-25). In addition, WDIs create a wider base, giving the opportunity to use wider and stronger prosthetic components: this may help to reduce the risk of technical complications and increase the ability of implants to tolerate occlusal forces of the magnitude that are present in posterior areas (9,20,21). The distribution of stress toward surrounding bone and the control of biomechanical loads are thought to be critical for long-term maintenance of implant-bone interface (15): a dental implant serves as a load-bearing device that not only sustains masticatory forces, but also transfers loads to peri-implant bone (15). It has been postulated that among the factors that affect the load transfer at the bone-implant interface is implant geometry, diameter and the surface area of implant integrated into the bone (11,12,15). From this point of view, it could be helpful to design the implant with a geometry that will minimize the peak bone stress caused by loading (11). In our present study on wide-diameter, locking-taper implants, a minimal marginal bone loss between implant installation and the 10 years’ follow-up visit was reported, with a mean DIB of 0.34 mm (± 0.23), 0.45 mm (± 0.27) and 0.75 mm (± 0.33) at the 1-, 5- and 10-year follow-up session, respectively. Finally, the locking-taper implant-abutment connection may provide an excellent seal against bacterial penetration (38). It is noteworthy that all implants with screw-type connections show a microgap of variable dimensions (40-100 micrometers) at the implant-abutment interface (39,40). As this microgap is colonized by micro-organisms, capable of penetrating into the inner portion of the implant, the bacterial leakage and persistent colonization may lead to chemotactic stimuli which initiate and sustain recruitment of inflammatory cells (39,40). Eventually this could result in inflammation of the peri-implant tissues and bone loss (39,40). The Morse taper connection reduces microgap dimensions (1-3 micrometers) at the implant-abutment interface, providing an excellent biological seal, preventing microbial infiltration (38). This

may reduce the level of soft tissue inflammation, ensuring long-term bone crest stability (38, 41, 42).

CONCLUSION Initially introduced as rescue implants, WDIs have increasingly been used for implantation in fresh extraction sites or in patients with insufficient bone height, poor bone quality or habit of bruxism. Early studies on WDIs have reported an increased failure rate; however, those unsatisfactory results were probably related to older implant design, machined surfaces, the learning curve for the surgical technique required and the traumatic effect on the bone from the wide drills used during the osteotomy preparation. Nowadays, new implant designs and surface configurations, modified drilling techniques and adapted surgical protocols have contributed to the enhanced performance of WDIs. Our present study suggests that the use of locking-taper WDIs can be a predictable treatment modality and may provide benefits for long-term maintenance of various implant-supported prosthetic restorations. Lockingtaper WDIs can yield reliable long-term outcomes, with high 10-year survival (patient-based: 99%; implantbased: 99.1%) rates and few biological and prosthetic complications. However, further long-term researches should be performed on locking-taper WDIs, such as randomized controlled trials, in order to obtain definitive evidence.

Acknowledgements The authors declare that they have no financial relationship with any commercial firm that may pose a conflict of interest for this study. No grants, equipment, or other sources of support were provided. The authors gratefully acknowledge the Lab 3 dental laboratory (Curno, Bergamo, Italy) and particularly the dental technician Roberto Cavagna for assistance in providing our dental clinic functional and esthetic restorations along these years.

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clinical evaluation of 307 single tooth Morse taper connection implants: a multicenter study. Int J Oral Maxillofac Implants 2010; 25: 394–400. 25. Urdaneta RA, Leary J, Lubelski W, Emanuel KM, Chuang SK. The effect of implant size 5 × 8 mm on crestal bone levels around single-tooth implants. J Periodontol 2012; 83: 1235–1244. 26. Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ, de Leeuw R, Manfredini D, Svensson P, Winocur E. Bruxism defined and graded: an international Consensus. J Oral Rehab 2013; 40: 2–4. 27. Mangano C, Mangano F, Shibli JA, Ricci M, Sammons R, Figliuzzi M. Morse taper connection implants supporting “planned” maxillary and mandibular bar-retained overdentures. A 5-year prospective multicenter study. Clin Oral Implants Res 2011; 22: 1117–1124. 28. Filippi A, Higginbottom FL, Lambrecht T, Levin BP, Meier JL, Rosen PS, Wallkamm B, Will C, Roccuzzo M. A prospective non-interventional study to document implant success and survival of the Straumann bone level SLA active dental implant in daily dental practice. Quintessence Int 2013; 44: 499-512 29. Weber HP, Crohin CC, Fiorellini JP. A 5-year prospective clinical and radiographic study of non-submerged dental implants. Clin Oral Implants Res 2000; 11: 144–153. 30. Kaplan EL, Meier P. Non parametric estimation from incomplete observation. J Am Stat Assoc 1958; 53: 467–481. 31. Lekholm U, Zarb GA. Patient selection and preparation. In: Branemark PI, Zarb GA, Albrektsson T. (eds). Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence, 1985: 199– 208. 32. Friberg B, Ekestubbe A, Sennerby L. Clinical outcome of Branemark System implants of various diameters: A retrospective study. Int J Oral Maxillofac Implants 2002; 17: 671–677. 33. Griffin TJ, Cheung WS. The use of short, wide implants in posterior areas with reduced bone height: A retrospective investigation. J Prosthet Dent 2004; 92: 139–144. 34. de Souza JG, Neto AR, Filho GS, Dalago HR, de Souza Jr JM, Bianchini MA. Impact of local and systemic factors on additional peri-implant bone loss. Quintessence Int 2013; 44: 415-424 35. Pennarocha-Diago M, Carillo-Garcia C, Boronat-Lopez A, Garcia-Mira B. Comparative study of wide-diameter implants placed after dental extraction and implants positioned in mature bone for molar replacement. Int J Oral Maxillofac Implants 2008; 23: 497–501. 36. Bozkaya D, Muftu S. Mechanics of the tapered interference fit in dental implants. J Biomech 2003; 36: 1649–1658. 37. Sannino G, Barlattani A. Mechanical evaluation of an implant-abutment self-locking taper connection: finite element analysis and experimental tests. Int J Oral Maxillofac Implants 2013; 28: e17–e26. 38. Dibart S, Warbington M, Su MF, Skobe Z. In vitro evaluation of the implantabutment bacterial seal: The locking taper system. Int J Oral Maxillofac Implants 2005; 20: 732–737. 39. Fujiwara CA, Magro Filho O, Oliveira NTC, Queiroz TP, Abla MS, Pardini LC. Assessment of the interface between implant and abutments of five systems by scanning electron microscopy. J Osseointegration 2009; 2: 60–66. 40. Piattelli A, Vrespa G, Petrone G, Iezzi G, Annibali S, Scarano A. Role of the microgap between implant and abutment: A retrospective histologic evaluation in monkeys. J Periodontol 2003; 74: 346–352. 41. Mangano FG, Shibli JA, Sammons RL, Iaculli F, Piattelli A, Mangano C. Short (8-mm) locking-taper implants supporting single crowns in posterior region: a prospective clinical study with 1-to 10-years of follow-up. Clin Oral Implants Res 2014; 25: 933-940 42. Mangano F, Shibli JA, Sammons RL, Veronesi G, Piattelli A, Mangano C. Clinical outcome of narrow-diameter (3.3-mm) locking-taper implants: a prospective study with 1 to 10 years of follow-up. Int J Oral Maxillofac Implants 2014 Mar-Apr;29(2):448-55.

E. Gheno1, A. Palermo2, L.F. Rodella3, B. Buffoli3 1

Private practitioner in Somma Lombardo (Va), Italy; Private practitioner in Lecce, Italy; 3 Section of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Italy 2

The effectiveness of the use of xenogeneic bone blocks mixed with autologous Concentrated Growth Factors (CGF) in bone regeneration techniques: a case series to cite this article Gheno E, Palermo A, Buffoli B, Rodella LF. The effectiveness of the use of xenogeneic bone blocks mixed with autologous Concentrated Growth Factors (CGF) in bone regeneration techniques: a case series. J Osseointegr 2014;6(2):37-42.

ABSTRACT Aim Different types of biomaterials and surgical techniques are currently used for the augmentation of atrophic ridges in view of implant supported restorations. The aim of this study was to clinically and histologically evaluate the combination of Concentrated Growth Factors (CGF) and xenogeneic bone in vertical and/or horizontal ridge augmentation. Materials and methods Seven patients (3 males and 4 females), who required oral implant and ridge augmentation surgery, were selected: 3 implants were placed during the surgery and 4 implants were inserted 4 months later, in order to allow complete graft integration. All implants were loaded after a 4-month healing time. The following parameters were assessed: a) the capability of CGF to permeate the bone scaffold; b) the degree of bone regeneration; c) the clinical success rate. Results The results obtained showed that: a) with the used medical device porous bone scaffolds can be effectively permeated by the CGF; b) the permeated grafting material resulted in effective bone regeneration, as confirmed by histomorphometric analysis; c) all implants were successfully in function at the 12 months follow-up. Conclusion This technique can be safely performed in the dental office under local anesthesia, so it can be considered a viable option in bone regeneration surgery.

Keywords Bone regeneration; CGF; Horizontal ridge augmentation; Scaffold blocks; Vertical ridge augmentation.

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INTRODUCTION The rehabilitation of partially and totally edentulous arches with osseointegrated implants is now a common practice supported by reliable long-term results (1-11). In some cases the anatomy of the edentulous ridges may be unfavourable to implant placement: large bone defects, in fact, may make the insertion of implants difficult or impossible due to insufficient bone volume. Currently, major bone defects can be filled using different surgical techniques (12, 13) in combination with the use of autografts, allografts and xenografts, as well as different types of natural and synthetic biomaterials (6,14-17). The grafting procedure using autologous bone is considered the gold standard, owing to the osteogenic capacity and the absence of antigenic response. However, it has some disadvantages, namely increased morbidity and limited availability of donor site. Therefore, biomaterials of different origin have been proposed as bone substitutes to overcome these limitations. In literature, there are several studies comparing the use of autologous bone with other bone substitutes; in particular, xenogeneic biomaterials are reported to be as clinically efficient as autologous bone, even if their biological behaviour can significantly vary according to their origin (porcine, bovine, equine) and their macro- and micro-structure, thus affecting the bone regeneration process (17-23). In the last years the use of platelet preparations, alone or in combination with other biomaterials, has proven to be a good regenerative option (24-25). Concentrated Growth Factors (CGF) are platelet concentrates containing autologous growth factors together with blood cells (26) that are reported to promote bone regeneration (27). As other platelet concentrates, CGF are isolated from whole blood samples with a simple and standardized protocol by means of a specific centrifuge, without the addition of exogenous substances. The main characteristic of CGF is

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its consistency: it is an organic matrix rich in fibrin and, therefore denser than other platelet concentrates; this characteristic makes it suitable for different uses, alone or in combination with other materials, as filler or as a scaffold for synthetic and biological membranes. CGF can be mechanically mixed with different biomaterials, in the form of granules or blocks, using a special medical device. The purpose of the present study was to standardize a surgical technique, that can be performed in any dental practice under local anaesthesia, through the assessment of the following parameters: a) ability of xenogeneic bone blocks to be permeated by CGF; b) amount of bone regeneration; c) clinical success rate.

MATERIALS AND METHODS Patient selection and surgical planning

In this study, 7 patients (3 males and 4 females aged between 45 and 63 years old) who needed oral surgery rehabilitation (4 in the maxilla and 3 in the mandible) were enrolled. Patients were selected according to the following inclusion criteria: patients in good general health and not heavy smokers (<10 cigarettes/day), who gave written informed consent for implant surgery. Subjects who had absolute contraindications to surgery were excluded. Two operators (EG and AP) performed surgeries: the treatments described were performed in their private practices, after a written informed consent was signed by each patient, following the Declaration of Helsinki principles. The materials and equipment used have been marketed for a long time, and there is no conflict of interest on the part of the authors. One month before surgery each patient underwent scaling and root planing, combined with motivational sessions and oral hygiene education. Radiographic evaluation was performed before surgery, 1 month after surgery and every 6 months after prosthetic loading. Patients were divided into two groups: in Group 1 (3 subjects) implants (SPI; Alpha-Bio Tec, Israel - Ankylos; Dentsply, Bologna, Italy) were placed during oral surgery

session (simultaneous implants); in Group 2 (4 subjects) implants (SPI; Alpha-Bio Tec, Israel - Ankylos; Dentsply, Bologna, Italy) were placed 4 months after surgery (delayed implants), when full graft integration was achieved. Two implants diameters were selected (3.3 and 3.5 mm), in order to be easily contained in the graft, and their length was proportionate to the anatomical site. In addition, a pre-surgical 3D measurement was performed to evaluate bone volume and quality.

Preparation of CGF and permeation process of biomaterial

Venous blood samples (4 samples of 9 ml) were obtained from each patient. Each blood sample was centrifuged by means of a specific device (Medifuge MF200; Silfradent srl, Italy) in order to obtain the CGF (Fig. 1), according to the manufacturer’s instruction. For the permeation process, the whole CGF obtained was mechanically mixed with the blocks of collagenated xenogeneic biomaterial (Sp-Block OsteoBiol® and C-Block; Tecnoss, Italy) using the Round Up device (Silfradent srl, Italy). The permeated blocks (Fig. 2) were then placed: Sp-square blocks were used for horizontal ridge augmentation, whereas C-cylinder blocks were used for vertical bone augmentation.

Surgical procedure

Local anaesthesia (plexus block) was administered (articaine 4% with epinephrine 1:100,000). A full thickness flap was raised to allow site evaluation and selection of bone block size. Bone decortication in the recipient site was performed to help graft integration. After preparing the surgical site, the Sp-Block or C-Block combined with CGF was placed and fixed with osteosynthesis screws (Fig. 3A, 4A) or by means of the implant itself, depending on the simultaneous or delayed protocol used. Flap mobilization was achieved with periosteal incisions; marginal gaps were filled with slow resorbable material, mixed with CGF. Finally, a resorbable membrane (OsteoBiol ® Evolution; Tecnoss, Coazze, Italy) was placed (Fig. 3B) and the site was sutured without tension. The patient was instructed to apply ice during

fig. 1 CGF preparation using the centrifuge device. A. Centrifuge device; B. Tube loading and balancing; C. Tubes after centrifugation; D. CGF isolation.

Xenogeneic bone blocks mixed with CGF in bone regeneration

fig. 2 Permeation of C-Block using Round Up device. A. Round Up; B. Scaffold; C. Placement of CGF in the holder of Round Up; D. Placement of the scaffold in the holder of Round Up; E-F. C-Block permeated with CGF. A

fig. 3 A. Placement and stabilization of SP-Block; B. Protection of the graft with the membrane; C. Radiographic examination of the bone block.

the first 12 hours and to follow a soft diet throughout the first month; antibiotics and nonsteroidal antiinflammatory drugs (NSAIDs) were administered. Loading of simultaneous implants with temporary prostheses, and subsequently with permanent ceramic prostheses, was achieved about 4 months after implant placement. Delayed implants were inserted after complete graft integration (about 4 months after surgery); during preparation of the implant site a bone core was harvested for histomorphometric analysis, using a 2 mm trephine bur before the final drill to insert the implant (Fig. 5); loading was achieved 4 months after implant placement.

Clinical and histomorphometric analysis

Treatment success was evaluated through both clinical examination (lack of mobility and pain, no bleeding on probing) and radiographic examination to assess bone structure (Fig. 3C, 4B, 4C). Histomorphometric analysis of the bone cores obtained during implant site preparation was performed by the Department of Anatomy and Physiopathology, University of Brescia, Italy. All bone samples were fixed in 10%

neutral buffered formalin, decalcified with Osteodec (Bio-Optica, Italy) and paraffin-embedded according to standard procedures; 7 μm thick sections were cut by microtome and stained with haematoxylin and eosin (BioOptica, Italy) (Fig. 6). The histomorphometric analysis was performed using an optical light microscope (Olympus, Germany) by operators blinded to the assigned group. Digital images of slices (five fields for each sample) were analyzed by means of a specific software (Image Pro-Plus 4.5.1, Immagini e Computer, Italy), able to quantify the ratio of newly formed bone (NB), non-mineralized tissue (n-MT) and residual graft (RG). Histomorphometric data were reported as mean ± standard error of the mean (SEM).

RESULTS The histological findings showed that porous bone blocks could effectively be permeated by CGF, using the Round Up medical device (Fig. 7). Histomorphometric analysis of bone sample (Fig. 8) showed the presence of trabeculae of newly formed

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fig. 4 A. Placement and stabilization of C-Block; B. Radiographic examination of the bone block; C. Radiographic examination of the implant. A

fig. 5 A. Implant site preparation using a core drill; B. Implant site; C. Bone core; D. SPI implant (Alpha Bio) placement; E. Radiographic examination of the implant.

bone (NB), together with non-mineralized tissue (n-MT), and residual bone graft (RBG). Quantitative data of NB, n-MT and RBG are shown in Table 1. Concerning clinical success rate, all implants were successfully in function after a 12-month follow-up. No implant mobility, no pain nor bleeding on probing were detected. Radiographic examinations also showed good implant integration in both types of graft. In addition, the specific shape of the used implants ensured significant implant stability, although only the apical third of them was used as anchorage during the healing phase.

DISCUSSION Different techniques and biomaterials are now available for the augmentation of atrophic ridges before implant surgery (1-25); however, an ideal procedure does not exist. The oral surgeon has to choose the best

fig. 6 A. Bone core; B. Histological analysis: haematoxylin-eosin staining. 2X magnification.

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Xenogeneic bone blocks mixed with CGF in bone regeneration

fig. 7 A Histological aspect of C-Block permeated with CGF, 1.25 magnification; B-c Enlargement - 10X magnification (arrows indicate CGF). Haematoxylin-eosin staining. A

fig. 8 Histomorphometric analysis. Haematoxylineosin staining. A. Vertical ridge augmentation using C-Block. 10X magnification. B. Horizontal ridge augmentation using SP-Block. 10X magnification.

NB (%+SEM) n-MT (%+SEM) RG (%+SEM) Vertical 30.40 +/- 0.57 34.52 +/- 1.42 augmentation Horizontal 46.59 +/- 3.28 48.61 +/- 2.49 augmentation

35.08 +/- 1.42 2.73 +/- 0.87

tabLE 1 Histomorphometric analysis of the percentage of New Bone (NB); non-Mineralized Tissue (n-MT), Residual Graft (RG) expressed as mean Âą standard error of the mean (SEM).

technique for the specific case and, in particular, the one that allows to limit surgical risks, costs and time (28-31). Several types of biomaterials are used in combination with different surgical techniques and many data support the efficacy of bone substitutes, such as xenogeneic bone derived biomaterials (of bovine, equine, porcine origin) (15-20,32-34). Beside these biomaterials, the use of different preparations of platelet concentrates has also been evaluated with promising results (24,25,27,35). The results of the present study showed that the Round Up device could effectively permeate bone blocks with CGF. This procedure allowed to add to the mechanical properties of the scaffold the biological activity of the CGF; therefore, it represents an effective method for

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bone regeneration, where CGF contributes to a better and more rapid healing of both soft and hard tissues, confirming the bone regenerative effect of platelet concentrates. The bone regeneration efficacy of this scaffold was also proved by histomorphometric analysis of the bone cores obtained during implant site preparation, which, clearly demonstrated that an adequate amount of regenerated bone, necessary for the correct integration of the implant, was present in the grafted sites 4 months after surgery; moreover, these data were supported by radiological examination and by the absence of significant clinical alterations. However, further controlled studies, with greater numbers of patients, are necessary to validate the present results.

CONCLUSION The technique proposed in the present study can be safely performed in the dental office under local anesthesia, and can be considered a viable option in bone regeneration surgery. Future scientific researches should be focused on the study of heterologous materials, which can completely replace the use of autogenous bone, and their combination with platelet concentrates that promote bone regeneration.

Gheno E. et al.

REFERENCES 1. Arvidson K, Bystedt H, Frykholm A, von Konow L, Lothigius E. Five-year prospective follow-up report of Astra tech implant system in the treatment of edentulous mandibles. Clin Oral Implants Res 1998;9:225-34. 2. Carlsson GE, Omar R. The future of complete dentures in oral rehabilitation. A critical review. J Oral Rehabil 2010;37:143-56. 3. Esposito M, Murray-Curtis L, Grusovin MG, Coulthard P, Worthington HV. Interventions for replacing missing teeth: different types of dental implants. Cochrane Database Syst Rev 2007;(4):CD003815. 4. Javed F, Ahmed HB, Crespi R, Romanos GE. Role of primary stability for successful osseointegration of dental implants: Factors of influence and evaluation. Interv Med Appl Sci 2013;5:162-7. 5. Leonhardt A, Grondahl K, Bergstrom C, Lekholm U. Long-term follow-up of osseointegrated titanium implants using clinical, radiographic and microbiological parameters. Clin Oral Implants Res 2002;13:127-32. 6. Mamalis A, Markopoulou K, Kaloumenos K, Analitis A. Splinting osseointegrated implants and natural teeth in partially edentulous patients: a systematic review of the literature. J Oral Implantol 2012;38:42434. 7. Margonar R, dos Santos PL, Queiroz TP, Marcantonio E. Rehabilitation of atrophic maxilla using the combination of autogenous and allogeneic bone grafts followed by protocol-type prosthesis. J Craniofac Surg 2010;21:18946. 8. Meyle J, Gersok G, Boedeker RH, Gonzales JR. Long term analysis of osseointegrated implants in non-smoker patients with a previous history of periodontitis. J Clin Periodontol 2014 doi: 10.1111/jcpe.12237 (In Press). 9. Parithimarkalaignan S, Padmanabhan TV. Osseointegration: An Update. J Indian Prosthodont Soc. 2013;13:2-6. 10. Warreth A, McAleese E, McDonnell P, Slami R, Guray SM. Dental implants and single implant-supported restorations. J Ir Dent Assoc 2013;59:32-43. 11. Weber HP, Crohin CC, Fiorellini JP. A five-year clinical and radiographic study of non submerged dental impalnts. Clin Oral Impl Res 2000;11:144-53. 12. Kan JY, Lozada JL, Goodacre CJ et al. Mandibular fracture after endosseous implant placement in conjunction with inferior nerve transposition: a patient treatment report. Int. J Oral Maxillofac Implants 2006;21:86-93. 13. Felice P, Checchi V, Pistilli R, Scarano A, Pellegrino G, Esposito M Bone augmentation versus 5 mm dental implants in posterior atrophic jaws. Four month post loading results from a randomized controlled clinical trial. Eur J Oral Implantol 2009;2:267-81. 14. Acocella A, Sacco R, Niardi P, Agostini T. Early implant placement in bilateral sinus floor augmentation using iliac bone block grafts in severe maxillary atrophy: a clinical, histological, and radiographic case report. J Oral Implantol 2009;35:37-44. 15. Artese L, Piattelli A, Di Stefano DA, Piccirilli M, Pagnutti S, D’Alimonte E, Perrotti V. Sinus lift with autologous bone alone or in addition to equine bone: an immunohistochemical study in man. Implant Dent 2011;20:383-8. 16. Buffoli B, Boninsegna R, Rezzani R, Poli PP, Santoro F, Rodella LF. Histomorphometrical evaluation of fresh frozen bone allografts for alveolar bone reconstruction: preliminary cases comparing femoral head with iliac crest grafts. Clin Implant Dent Relat Res 2013;15:791-8 17. Di Stefano DA, Artese L, Iezzi G, Piattelli A, Pagnutti S, Piccirilli M, Perrotti V. Alveolar ridge regeneration with equine spongy bone: a clinical, histological, and immunohistochemical case series. Clin Implant Dent Relat Res 2009;11:90-100. 18. Di Stefano DA, Cazzaniga A, Andreasi Bassi M, Ludovichetti M, Ammirabile G, Celletti R. The use of cortical heterologous sheets for sinus lift bone grafting: a modification of Tulasne’s technique with 7-year follow-up. Int J Immunopathol Pharmacol 2013;26:549-56. 19. Felice P, Marchetti C, Piattelli A, Pellegrino G, Checchi V, Worthington H, et al. Vertical ridge augmentation of the atrophic posterior mandible with interpositional block graft: bone from the iliac crest versus bovine anorganic bone. Eur J Oral Implantol 2008; 1:183-98.

20. Felice P, Marchetti C, Iezzi G, Piattelli A, Worthington H, Pellegrino G, et al. Vertical ridge augmentation of the atrophic posterior mandible with interpositional block graft: bone from the iliac crest vs bovine anorganic bone. Clinical and histological result up to one year after loading from a randomized-controlled clinical trial. Clin Oral Implants Res 2009;20:138693. 21. Felice P, Piattelli A, Iezzi G, Degidi M, Marchetti C. Reconstruction of an atrophied posterior mandible with the inlay technique and inorganic bovine bone block: a case report. Int J Periodontics Restorative Dent 2010;30:583-91. 22. Merli M, Migani M, Esposito M. Vertical ridge augmentation with autogenous bone graft: resorbable barriers supported by ostheosynthesis plates versus titanium-reinforced barriers. A preliminary report of a blinded, randomized controlled clinical trial. Int J oral Maxilofac Implants 2007;22:373-82. 23. Tetè S, Vinci R, Zizzari VL, Zara S, La Scala V, Cataldi A, Gherlone E, Piattelli A. Maxillary sinus augmentation procedures through equine-derived biomaterial or calvaria autologous bone: immunohistochemical evaluation of OPG/RANKL in humans. Eur J Histochem 2013;57:e10. 24. Del Corso M, Vervelle A, Simonpieri A, Jimbo R, Inchingolo F, Sammartino G, Dohan Ehrenfest DM. Current knowledge and perspectives for the use of platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) in oral and maxillofacial surgery part 1: Periodontal and dentoalveolar surgery. Curr Pharm Biotechnol 2012;13:1207-30. 25. Simonpieri A, Del Corso M, Vervelle A, Jimbo R, Inchingolo F, Sammartino G, Dohan Ehrenfest DM. Current knowledge and perspectives for the use of platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) in oral and maxillofacial surgery part 2: Bone graft, implant and reconstructive surgery. Curr Pharm Biotechnol 2012;13:1231-56. 26. Rodella LF, Favero G, Boninsegna R, Buffoli B, Labanca M, Scarì G, Sacco L, Batani T, Rezzani R. Growth factors, CD34 positive cells, and fibrin network analysis in concentrated growth factors fraction. Microsc Res Tech 2011;74:772-7. 27. Sohn DS, Heo JU, Kwak DH, Kim DE, Kim JM, Moon JW, Lee JH, Park IS. Bone regeneration in the maxillary sinus using an autologous fibrin-rich block with concentrated growth factors alone. Implant Dent 2011;20:389-95. 28. Felice P, Pistilli R, Lizio G, Pellegrino G, Nisii A, Marchetti C. Inlay versus onlay iliac bone grafting in atrophic posterior mandible: a prospective controlled clinical trial for the comparison of the two techniques. Clin Implant Dent Relat Res 2009;11:69-82. 29. Chiapasco M, Romeo E, Casentini P, Rimondini L. Alveolar distraction osteogenesis vs. vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: a 1-3 years prospective study on humans. Clin Oral Implants Res 2004;15:82-95. 30. Chiapasco M, Zaniboni M, Rimondini L. Autogenous onlay bone graft vs. alveolar distraction osteogenesis for the correction of vertically deficient edentulous ridges: a 2-4 years prospective study on humans. Clin Oral Implants Res 2007;18:432-40. 31. Bianchi A, Felice P, Lizio G, Marchetti C. Alveolar distraction osteogenesis versus inlay bone grafting in posterior mandibular atrophy: a prospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 105:282-92. 32. Perrotti V, Nicholls BM. Resorption pattern of a porcine-derived bone substitute. J Osseointegr 2009; 1: 22-8. 33. Scarano A, Piattelli A, Assenza B, Quaranta A, Perrotti V, Piattelli M, Iezzi G. Porcine bone used in sinus augmentation procedures: a 5-year retrospective clinical evaluation. J Oral Maxillofac Surg 2010;68:1869-73. 34. Scarano A, Piattelli A, Perrotti V, Manzon L, Iezzi G. Maxillary sinus augmentation in humans using cortical porcine bone: a histological and histomorphometrical evaluation after 4 and 6 months. Clin Implant Dent Relat Res 2011; 13:13-8. 35. Honda H, Tamai N, Naka N, Yoshikawa H, Myoui A. Bone tissue engineering with bone marrow-derived stromal cells integrated with concentrated growth factor in Rattus norvegicus calvaria defect model. J Artif Organs 2013; 16:305-15.

J.L. Calvo-Guirado1, M. Mallaun2, M. Dard3, J.A. López Torres4 1

University of Murcia, Murcia, Spain Institut Straumann, Basel, Switzerland 3 New York University, New York, USA 4 University of Murcia, Murcia, Spain 2

short communication

Evaluation of 4 mm implants in mandibular edentulous patients with reduced bone height. Surgical preliminary results to cite this article Calvo-Guirado JL, Mallaun M, Dard M, López Torres JA. Evaluation of 4 mm implants in mandibular edentulous patients with reduced bone height. Surgical preliminary results. J Osseointegr 2014;6(2):43-45.

ABSTRACT Aim Growing evidence has suggested the utility of short dental implants for oral reconstructive procedures in clinical situations of limited vertical bone height. The aim of this short comunication was to evaluate the clinical use of implants < 10 mm in length and to determine short implant-supported prosthesis success in the atrophic jaw. Materials and methods Six women and three men were recruited for the treatment of edentulous mandibles. A total of 6 implants were inserted in each patient: two anterior implants of conventional lenght and four posterior 4 mm Titanium Zirconium (TiZr) implants. The insertion torque and bone denisty were evaluated. Results The mean insertion torque for the 4 mm implants was lower than for conventional ones, without any statistical difference. Moreover, most of the patients (88%) showed a D2 bone type. Conclusion The provision of short implant-supported prostheses in patients with atrophic alveolar ridges appears to be a successful treatment option in the short term; however, more scientific evidence is needed for the long term.

Keywords bone density, insertion torque, short implants, success rate.

Introduction Rehabilitation of totally edentulous patients with conventional removable dentures could be unsatisfactory for patients due to instability, discomfort, nerve punching and affection of the ability to eat and speak. A complete

screw-retained implant-supported prosthesis may be a viable alternative in such cases. However, the lack of sufficient bone volume and close proximity to the inferior alveolar nerve may represent a difficult clinical situation for the placement of endosseous implants (1). By using short implants to circumvent these difficulties, the primary stability may be compromised due to the reduced contact area for osseointegration. Moreover, successful placement of short implants in dense bone may furthermore depend on an accurate surgical technique to prevent a loose fit and overheating of the bone site (2-3). Traditionally, clinicians have avoided the use of short-length implants in areas of compromised bone (e.g., posterior locations, low bone density, and thin ridges). With the introduction of new surfaces, the surgical and clinical performance of short-length implants may become very similar to that of standard length ones. The main purpose of this short communication was to evaluate and report the surgical performance of novel short 4 mm implants made of Titanium Zirconium (TiZr) alloy with a hydrophilic surface.

Material and Methods Six women and three men with a mean age of 64 (range 44–86) years were recruited for treatment of edentulous mandibles. Each individual was thoroughly informed of the overall requirements/procedures of the study after explaining the purposes of the study, the nature of the planned treatment and alternative procedures. Potential risks, possible complications, and benefits of the proposed treatment were explained to the study subjects and they all signed an informed consent. The inclusion and exclusion criteria were selected as follows. › Inclusion criteria: age >18 years; committed to participate up to 3 years follow-up; complete edentulism in the mandible to allow placement of 6 implants (two in the canines zone of 10 mm in lenght and four 4 mm implants placed in the resorbed sites behind the mental

Calvo Guirado J.L. et al.

nerve); full or partial dentition opposing the implants. The implant site had to be edentulous for >2 months and healed, with evidence of bone resorption and atrophy; the minimal residual bone height should be adeqaute in the canine zone, and at least 8 mm in the posterior zone. â&#x20AC;ş Exclusion criteria: presence of blood, metabolic, endocrine, renal, or neoplastic disease; human immunodeficiency virus infection; smoking >10 cigarettes per day; alcoholism; any conditions that may prevent study participation or interfere with analysis of results; mucosal diseases; history of irradiation therapy; previous reconstruction, bone grafting, or failed GBR at

the site of intended implant surgery; severe bruxism/ clenching; inadequate oral hygiene or unmotivated for home care; lack of primary stability; insufficient bone or any abnormality that would contraindicate implant placement.

Pretreatment procedures

A clinical and radiological examination was carried out including panoramic x-rays (Fig. 1) (8000C Digital Panoramic and Cephalometric System, Carestream, Rochester, NY, USA) and Cone beam scan (CS 9300 System, Carestream, Rochester, NY, USA). Bone and non-bone voxels were segmented using a heuristic segmentation algorithm that was developed specially for bone tissue with highly nonhomogeneous CT attenuation density distributions (4).

Study design

Each patient received 6 implants: two anterior implants of 10 mm length and four posterior implants of 4 mm lenght with a hydrophilic surface (Tissue Level Standard Plus, RN, Roxolid, SLActive, diameter 4.1 mm, Institut Straumann AG, Basel, Switzerland) for a screw-retained fixed complete denture. fig. 1 Preoperative panoramic radiograph. fig. 2 Mucoperiosteal flap elevated before implant placement.

fig. 3 Drilling sequence for 4 mm Standard Plus Implants: Lance-shaped drill (pointed drill designed to break the cortical bone); 2,2 mm drill (initial step for dental implant); Implant Depth Gauge; 2,8 mm drill; Implant Depth Gauge; 3,5 mm drill; Implant Depth Gauge. fig. 4 Six implants placed in edentulous mandible, two long implants of 10 mm length and 4 mm implants behind mental nerve in both sides.

Surgical procedure

Implant placement was performed using single-stage surgery. Local anesthesia was achieved by inferior alveolar nerve block and administration of an appropriate dose of Articaine dentalÂŽ 4% with epinefrine 1:100.000 (Inibsa, Barcelona, Spain). A midline incision was done at the alveolar crest from the distal surface of the missing first molar. Full thickness mucoperiosteal flaps were raised and the path of the mental foramen identified with two realease incisions at the back (Fig. 2). The preparation of the implant sites was performed according to a precise sequence (Fig. 3). Immediately postoperatively, the initial implant stability was assessed by recording the insertion torque value of the 4 mm implants. Cover screws were placed on the implants and the flaps were repositioned and sutured (Fig. 4). Antibiotics were prescribed at the discretion of the surgeon. Analgesics were given as required for pain control. The patients were instructed to rinse with a 0.12% chlorhexidine solution (Dentaid, Barcelona, Spain) twice a day for 1 or 2 weeks until suture removal. After suture removal, the patients were instructed in proper mechanical brushing of the implants using 1% chlorhexidine gel until placement of the final restoration. A removable temporary prosthesis was installed in the mandible by using provisional implants loaded with Structur (Voco Gmbh, Cuxhaven, Germany), in order to avoid stress/load on the definitive implants during the healing phase. Panoramic radiographs were obtained before and after surgery (Fig. 5).

Statistical analysis

The statistical software used was StatXact (Cytel, Cambridge, MA, USA) and descriptive statistics by means of Excel (Microsoft, Redman, WA, USA). The patient was used as

ÂŠ ariesdue June 2014; 6(2)

Short Communication. Preliminary data on 4 mm implants in reduced bone height

fig. 5 Postoperative radiograph after implant placement. Ncm 60 50 40 30 20 10 0 1

fig. 6 Mean insertion torque values per patient, recorded during the insertion of the 4 mm implants.

Patient

P1 P2 P3 P4 P5 P6 P7 P8 P9

Ncm SD

5.6

6.4

7.2

1.5

7.5

tabLE 1 Mean insertion torque values (Ncm)+/- standard deviation (SD) per patient (P1 to P9), recorded during the insertion of the 4 mm implants.

the unit of analysis in all tests. For continuous data, a mean value was calculated per patient. The paired two-sample t-test was used and the level of significance was set at 0.05.

Results All implants survived until one month after insertion. The mean insertion torque for the 4 mm implants was 38.1 ± 1.2 Ncm, while for the 10 mm implants was 42.4 ± 2.1 Ncm (table 1). Using a paired two-sample t-test, no significant difference between the average insertion torques was found (p=0.005) (Fig. 6). Most of the patients had D2 bone (88%), while fewer patients had class D1 (8 %) or D3 (4 %) bone.

Discussion and conlcusion Short implants should be used by experts with skillfull hands to avoid implant failures. The preliminary results of this study demonstrate that 4 mm long TiZr implants with an hydrophilic surface can be safely inserted in

resorbed mandibles with insertion torques comparable to longer implants, thereby avoiding vertical augmentation procedures. Unlike the mandible (McGill Consensus meeting, Montreal, 2003), there is no consensus today regarding the number of implants for a maxillary overdenture. However, a recent systematic review revealed that a maxillary overdenture, supported by six implants, connected with a bar, is the most successful treatment regarding the survival of both the implants and the overdenture (6). Four additional extrashort implants, as proposed by the present study, implicate an additional cost, altought they may help the long implants, by increasing the stability of fixed resin prostheses, due to the wider spread of the implants within the arch. A second advantage might be that posterior bone resorption could be prevented, implicating less relinings of the prosthesis and avoiding mental nerve damage. Pieri et al. suggested that even in quality IV bone, a successful treatment can be expected with two additional short implants, early loaded, supporting an overdenture (7). The lower bone quality/density in the posterior areas may be compensated by splinting of all implants with a cadcam bar. The loading, in the present study, was avoided in the early stages and after the final restoration; moreover, unfrequent relining during the first weeks was performed to reduce crestal bone loss. Van Assche et al., studied the lack of information on the forces applied by different opposite arch conditions. Since the patient population of the study was limited, it was not possible to evaluate the influence of the applied forces of the opposing arch. They also showed that short implants can be a successful alternative to bone augmentation techniques for this treatment concept, also in type III or IV bone (8). The provision of short implant-supported prostheses in patients with atrophic alveolar ridges appears to be a successful treatment option in the short term; however, more scientific evidence is needed for the long term.

References 1. Annibali S, Cristalli MP, Dell’Aquila D, Bignozzi I, La Monaca G, Pilloni A. Short dental implants: a systematic review. J Dent Res 2012;91(1):25-32. 2. Anitua E, Alkhraist MH, Piñas L, Begoña L, Orive G. Implant survival and crestal bone loss around extra-short implants supporting a fixed denture: the effect of crown height space, crown-to-implant ratio, and offset placement of the prosthesis. Int J Oral Maxillofac Implants 2014;29(3):682-689. 3. Grandin M, Berner S, Dard M. A review of titanium zirconium (TiZr) alloys for use in endosseous dental implants. Materials, 2012, 5: 1348-1360. 4. Kim DG, Christopherson GT, Dong XN, Fyhrie DP, Yeni YN. The effect of microcomputed tomography scanning and reconstruction voxel size on the accuracy of stereological measurements in human cancellous bone. Bone 2004;35(6):1375-82. 5. Slotte C, Gronningsaeter A, Halmoy AM, Ohrnell LO, Stroh G, Isaksson S, Johansson LA, Mordenfeld A, Eklund J, Embring J. Four-millimeter implants supporting fixed partial dental prostheses in the severely resorbed posterior mandible: two-year results. Clin Implant Dent Rel Res 2011;14:46-58. 6. Slot W, Raghoebar GM, Vissink A, Huddleston Slater JJ, Meijer HJA. A systematic review of implant-supported maxillary overdentures after a mean observation period of at least 1 year. J Clin Periodontol 2010;37:98-110. 7. Pieri F, Aldini NN, Fini M, Marchetti C, Corinaldesi G. Immediate functional loading of dental implants supporting a bar-retainedmaxillary overdenture: preliminary 12-month results. J Periodontol 2009;80:1883-1893. 8. Van Assche N, Michels S, Quirynen M, Naert I. Extra short dental implants supporting an overdenture in the edentulous maxilla: a proof of concept. Clin Oral Impl Res 2012;23:567-576.

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