Journal of Osseointegration by Ariesdue srl

journal of osseointegration issn 2036-412I

june 2012

w w w. j o ur nal of oss e o inte gr ati o n .e u

n. . . . .

vol. . .

journal of osseointegration

Editorial board editors-in-chief

associate editors

Adriano Piattelli

Arthur Belem Novaes Jr.

Biomaterials Ana Pontes Barretos (BRA) Yasumasa Akagawa Hiroshima (JPN) Pâmela L. Santos Araçatuba (BRA) Victor Arana Chavez Sao Paulo (BRA) Sérgio L. Scombatti Carlos Roberto Grandini de Souza Ribeirão Preto (BRA) Ilha Solteira (BRA) Pascal Valentini Paris (FRA) Adalberto Luiz Rosa Ribeirão Paul Weigl Frankfurt am Main (DEU)

novaesjr@forp.usp.br

Lior Shapira Jerusalem (ISR) Paulo Tambasco de Oliveira

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

Dental School of Ribeirão Preto, University of São Paulo (Brazil)

Preto (BRA)

Ribeirão Preto (BRA)

Heverson Tavares Araraquara (BRA) Van P. Thompson New York (USA)

associate editors Biomaterials

Clinical Research

New York (USA)

Rochester (USA)

Biomaterials and Tissue Engineering

Implant Science

Paulo Coelho

Georgios Romanos

Marco Degidi

Jose M. Granjeiro

Bologna (Italy)

Carlo Mangano

Guarulhos (Brazil)

Niterói (Brazil)

Jamil Shibli

Gravedona (Italy)

Clinical Innovations

Basic Research

Devorah Schwartz-Arad

Tel Aviv (Israel)

Pablo Galindo Moreno Granada (ESP)

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

Biomaterials Group “IQ” UNESP Araraquara, SP (Brazil)

n.oliveira@journalofosseointegration.eu

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Biomaterials and Tissue Engineering

Paolo Amerio Chieti (ITA) Timothy G. Broomage New York (USA) Martin Lorenzoni Graz (AUT) Mario Raspanti Varese (ITA) Cristina Teixeira New York (USA) Michael Yost Columbia (USA) Basic Research

Luciano Artese Chieti (ITA) Raquel R. M. Barros Ribeirão Preto (BRA)

Giuseppe Cardaropoli New York (USA) Francesco Carinci Ferrara (ITA) Joni A. Cirelli Araraquara (BRA) Magda Feres Guarulhos (BRA) Giovanna Iezzi Chieti (ITA) Ramon Martinez Corrià Lerida (ESP) Gabriella Mincione Chieti (ITA) Raffaella Muraro Chieti (ITA) Gianpaolo Papaccio Naples (ITA) Rachel Sammons Birmingham (GBR) Clinical Research

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Paola Cappelletti

a.battaglia@ariesdue.it

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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

farma@ariesdue.it

doctoros@ariesdue.it

Joerg Neugebauer Cologne (DEU)

redazione

Barbara Bono

Cristina Calchera

Franco De Fazio Simona Marelli

Preto (BRA)

Implant Science

Carlos R.P. Araujo Bauru (BRA) Bartolomeo Assenza Chieti (ITA) Luigi Califano Naples (ITA) Jose Luis Calvo Guirado Murcia (ESP) 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

David Anson Beverly Hills (USA) 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) Glenn Mascarenhas Mumbai (IDN) Georg H. Nentwig Frankfurt (DEU) Vula Papalexiou Curitiba (BRA) Waldemar Polido Porto Alegre (BRA) Nigel Saynor Woodford (GBR) Ludovico Sbordone Pisa (ITA) David Simmons New Orleans (USA) Aris Tripodakis Athens (GRC)

journal of osseointegration

Arthur B. Novaes Jr 1, Patricia Garani Fernandes 2, Flávia Adelino Suaid 2, Marcio Fernando de Moraes Grisi 3, Sergio Luis Scombatti de Souza 3, Mario Taba Jr. 3, Daniela Bazan Palioto 3, Valdir Antonio Muglia 4 1

DDS, MSc, PhD, Chairman of Periodontology - Ribeirão Preto School of Dentistry, University of São Paulo. DDS, MSc, Graduate Students of Department of Oral Surgery and Periodontology - Ribeirão Preto School of Dentistry, University of São Paulo. 3 DDS, MSc, PhD, Associate Professor of Department of Oral Surgery and Periodontology - Ribeirão Preto School of Dentistry, University of São Paulo. 4 DDS, MSc, PhD, Professor of Department of Dental Materials and Prosthodontics- Ribeirão Preto School of Dentistry, University of São Paulo. 2

Ridge preservation with acellular dermal matrix and anorganic bone matrix cell-binding peptide P-15 after tooth extraction in humans. A histologic and morphometric study to cite this article Novaes AB Jr, Fernandes PG, Suaid FA, de Moraes Grisi MF, Scombatti de Souza SL, Taba M Jr, Palioto DB, Muglia VA. Ridge preservation with acellular dermal matrix and anorganic bone matrix cell-binding peptide P-15 after tooth extraction in humans. A histomorphometric study. J Osseointegr 2012;2(4):23-30.

ABSTRACT Aim The aim of this study was to analyze by histomorphometric parameters the use of acellular dermal matrix (ADM) with or without anorganic bovine bone matrix (ABM) / synthetic cell-binding peptide P-15 in the formation of bone in human alveoli. Materials and methods Eighteen patients in need of extraction of maxillary anterior teeth were selected and randomly assigned to the test group (ADM plus ABM/P-15) or the control group (ADM only). Histomorphometric measurements and histological analysis were recorded about 6 months after ridge preservation procedures in ten patients. The amount of newly formed bone, the most recently formed bone, fibrous tissue plus marrow spaces and remaining graft particles were measured and analyzed. Results At 6 months, the new bone area parameter and the percentage of fibrous tissue plus marrow space areas showed higher values to the control group, and statistically significant differences when compared with the test group (p=0.03). Conclusion The ADM acted as a membrane. The association of ABM/P-15 with ADM resulted in new bone formation within the alveoli, but the results were not considered relevant when used in this indication.

KEY WORDS Biocompatible materials; bone regeneration; bone grafting; socket graft; tooth extraction

INTRODUCTION Alveolar bone resorption after tooth extraction is

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an inherent condition of the healing process. It is accelerated at the first 6 months after extraction and followed by a gradual remodeling that includes changes in size and shape, with loss of approximately 40% in height and 60% in width (1-3). The reduction in height and width of the alveolar ridge is progressive and irreversible and it can make implant placement difficult, especially in the anterior maxilla, where bone volume is important for functional and esthetic reasons (4). Early extraction socket healing is expected to decrease the alveolar ridge by 2 to 4 mm horizontally and 1 mm vertically. These changes are time dependent, by the end of the first year post extraction nearly 6 mm of buccal bone loss can be expected (5-7). The general understanding is that bone graft placement in the extraction socket should offset the catabolic processes observed within the crestal ridge. Therefore, several procedures, such as the use of bone autografts, bone replacement materials, and regenerative techniques, have been proposed to prevent and correct alveolar bone resorption. Guided bone regeneration (GBR) is based on the principle of selecting cells using membranes to prevent epithelial proliferation (8). Conventionally, nonresorbable and resorbable membranes are used in GBR techniques. More recently, some studies have shown the possibility of using acellular dermal matrix (ADM) as a biologic membrane in GBR (9-12). ADM is allogeneic human skin obtained from tissue banks. It is processed by removing of the epidermis and all dermal cells; however, the complex basement membrane and the structure of collagen and elastin are preserved (13). In this context, there is a structural biocompatibility as a scaffold for the incorporation and migration of epithelial cells, keratinocytes, and fibroblasts, which will be incorporated into this material (8,13). In addition, ADM has been used in periodontal regenerative procedures, not only because of its biocompatibility but also because of its ability to increase the keratinized tissue for root coverage, be used as membrane in the GBR, and to eliminate gingival

journal of osseointegration Novaes A.B. Jr. et al.

melanin pigmentation (14-16). The use of ADM for the ridge preservation after tooth extraction has been demonstrated by successful clinical reports (10,12,15,17). Moreover, some studies have shown good histologic results in GBR (12,15,17). In general, the amount of newly formed bone is limited by the space below the membrane. ADM can collapse into the bone defects; therefore, the use of bone substitutes has been suggested as space maintainers. Some biomaterials, such as hydroxyapatite, calcium sulfate, bioactive glass, and xenograft bone substitutes, have demonstrated good results when associated with membranes or ADM (16,18-20). A new bone substitute composed of anorganic bovine bone matrix (ABM) and P-15, a synthetic component with a sequence of 15 amino acids of collagen type I, has been used as a new alternative (21). ABM/P-15 has osteoconductive properties because of its ability to promote cell binding, such as fibroblasts and osteoblasts, initiating the cascade of events that allows bone formation including cell migration and differentiation (21). Some studies in dogs have demonstrated the association of ABM/P-15 and biologic membranes. Barboza et al. (22) induced surgical Class III alveolar defects on mandibular second premolars. At 8 weeks, the defects in the test group were filled with ABM associated with a bioabsorbable membrane, and the control group was filled only with ABM/P-15. Clinical results showed significant bone increase and histologic images showed bone formation in the test areas. Beck and Mealey (23) evaluated histologically the bone formation using a single bone allograft material at two different time points after tooth extraction and socket grafting. No statistically significant differences in the amount of new bone formation was found between sites that healed for an average of 14 weeks compared to those that healed for an average of 27 weeks. All sites examined in that study displayed evidence of new bone formation. Moreover, other studies (24-26) suggest that ridge preservation techniques using mineralized human bone allograft may promote new bone formation in the healing extraction socket. The histological analysis of the use of ABM/P-15 with ADM for the treatment of ridge defects after tooth extraction has not been reported in the literature. Therefore, this study aims to analyze through histomorphometric analysis the use of both biomaterials to preserve alveolar bone after tooth extraction.

MATERIALS AND METHODS The present study was performed at the Ribeirão Preto School of Dentistry, University of São Paulo, São Paulo, Brazil, between February 2009 and February 2011. It was approved by the Ethical Committee for Human Research of the same institution, protocol number 2009.1.388.58.0.

This study is a sequence of a recently published study (27), in which the surgical phase of the study is detailed. In summary, 18 patients (five males and 13 females; age range: 33 to 58 years) were selected. They received detailed written information about the treatment and signed an informed consent form. To be included in the study, the patient had to present ≥2 hopeless, single-rooted, and nonadjacent teeth in the maxilla. This was established to avoid the situation where the bone plate of one group could interfere with the healing process of the other group, since the bone plates could be in intimate contact. Therefore, all hopeless teeth were extracted, regardless of whether or not they were included in the study. In this split-mouth study, the test group had 18 sockets treated with ABM/P-15 (PepGen P-15, DENTSPLY Friadent CeraMed, Lakewood, CO) associated with ADM (Alloderm, BioHorizons, Birmingham, Alabama), and the control group (blood clot) had 18 sockets treated only with ADM. Surgical procedures were performed under local anesthesia, and for the extractions a periotome was used to reduce trauma to the bone. Intrasulcular incisions were performed after making releasing incisions on the proximal surfaces of the adjacent teeth, and a mucoperiosteal flap was elevated to expose both the labial and palatal aspects of the alveolar ridge. After tooth removal, the granulation tissue was curetted and removed. The two sockets selected for the study were treated with GBR, using ADM as a barrier membrane, however, only the test socket was filled with the grafting material. After the socket grafting procedure, the full-thickness buccal and lingual flaps were repositioned and sutured with 5.0 non-resorbable sutures. The ADM was intentionally left exposed in its central portion (≤ 2 mm) to induce an increase in the width of the keratinized tissue. Six months after the first surgical procedure, a reentry surgery was performed using the same approach described previously and biopsies measuring 2x5 mm were made in the previously extraction socket area with a 2.75-mm trephine drill (outer diameter) in the central portion of the alveolus for the test (ADM plus ABM/P-15) and control (ADM only) groups. Some patients were not included in this phase of the study, because the remaining bone was not sufficient for implant placement and others did not want to continue participating in this research. So, 10 of 18 patients were selected for the biopsies and implant placement. In most of the sites, implants were placed after the biopsies and preparation of the site. The biopsies were fixed using 4% formalin at pH 7 for 10 days and transferred to a 70% ethanol solution to wait for processing. The samples were dehydrated in increasing alcohol concentrations until 100% concentration was reached. They were embedded in LR White resin (London Resin Company ltd, UK), subsequently two sections from the center of the tissue blocks were made perpendicularly to the long axes using a microtome following the technique for hard tissues, one group of sections were stained with Stevenel’s blue

journal of osseointegration Use of ADM and ABM/P-15 in alveolar ridge preservation

fig. 1A The control group biopsy shows the formation of the new bone (NB) and recently formed bone (RFB) in the center. fig. 1b The test group biopsy shows the residual graft particles (RGP) and fibrous tissue plus marrow spaces (FT+MS) in the center and the formation of the new bone (NB) and recently formed bone (RFB) in the extremity (Mallory trichromic stain; original magnification, x1.6).

complications. No sockets presented exfoliation of the bone graft, indicating that the use of ADM was appropriate for graft retention at the healing phase.

Histological observations

It was possible to observe the presence of newly formed bone (NB), most recently formed bone (RFB) and fibrous tissue plus marrow spaces (FT+MS) in the sections from both groups (Fig. 1A, 1B). Besides, in the test group, residual graft particles (RGP) of ADM/ P-15 were present in the center and in the border of the biopsy (Fig. 1B). The control and test groups showed an osteoid matrix (OM) that was also identified in some areas on the external surfaces of the newly formed bone (Fig. 2A, 2B), and it was paved with osteoblasts (OB) both in

and Alizarin red S, and the other with Toluidine blue for optical microscopy. With this last stain it was possible to identify the bone tissue that was in formation during the healing process and the bone that was being deposited at the time of the biopsy.

Histomorphometric analysis

Histological sections from each biopsy were captured through a video camera (Leica DC300F; Leica Microsystems, Heerburgg, Switzerland) joined to a stereomicroscope (Leica MZFL III). The images were analyzed using the Image J Program to determine the following area measurements (mm2): total area (TA), new bone area (NBA), recently formed bone (RFB) and fibrous tissue and marrow spaces (MS). In the test groups (ADM plus ABM/P-15) the amount of residual graft particles (RGP) was measured in the total area.

Statistical analysis

To compare the results obtained in the control and test groups after treatment, Wilcoxon signed-rank test was applied. For all statistical analyses, a significance level of 5% (P<0.05) was used.

RESULTS Clinical findings

The surgical procedures were well tolerated by all 18 patients (5 males and 13 females, mean age 44 â&#x20AC;&#x201C; 8.10 years; age range 33 to 58 years) with no postoperative

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fig. 2a The presence of the fibrous tissue and marrow spaces (FT+MS), osteoid matrix (OM), osteoblast (OB) and newly formed bone (NB) in the control and test groups (Mallory trichromic stain; original magnification, x40). fig. 2b The evidence of these structures and cells with another image (Mallory trichromic stain; original magnification, x40).

journal of osseointegration Novaes A.B. Jr. et al.

the interior and exterior of the lamellae depositing unmineralized osteoid matrix (Fig. 2A, 2B). Interrupted/ partially resorbed lamellae and incremental lines were observed in the newly formed bone, indicating regions of new bone formation (Fig. 3, 4). Besides, in some areas, lamellae circumscribed by concentric bone matrix were present representing new bone formation (Fig. 4). The most recently formed bone (RFB) was partly fibrous and partly cellular and immature (Fig. 3, 4, 5B). The bone with this characteristic was present on the surface of the newly formed bone overlapping this structure. This RFB was depositing at the moment of the biopsy, representing the remodeling process of the newly formed bone, which was deposited during the healing period (figures 3, 4 and 5B). A layer of osteoblasts on the external surfaces of the most recently formed bone

was present depositing osteoid matrix (Fig. 4). Amongst the newly formed bone, it was possible to observe the presence of ABM/P-15 residual graft particles (RGP), in the test group (Fig. 5A, 5B). These particles were dispersed in the region corresponding to the area of new bone formation, in some areas, it was present with immature bone formation around and circumscribing the residual particles (Fig. 5A, 5B). Sometimes, these particles were lined by the newly formed bone representing the direct contact between the structures (Fig. 5B).

fig. 3 In the control group: the fibrous tissue and marrow spaces (FT+MS), newly formed bone (NB) and the recently formed bone (RFB) overlapping the new bone in the extremity of the structure (Toluidine blue stain; original magnification, x20).

fig. 4 In the test group: the fibrous tissue and marrow spaces (FT+MS), new bone formed (NB) and the recently formed bone (RFB) formation overlapping the new bone in the extremity of the structure. The osteoid matrix (OM) and osteoblasts (OB) in the external surface of the newly bone formed and the presence of the concentric lamellae (CL) in the center (Toluidine Blue stain; original magnification, x20).

Histomorphometric findings

At 6 months, the histomorphometric analysis showed 38.66% of new bone tissue, 6.84% of recently formed bone (total amount of 45.5% of mineralized tissue) and

fig. 5a In the test group the residual particles (RGP) of ABM/P-15 were observed as well as fibrous tissue and marrow spaces (FT+MS) in the center of the biopsy. The new bone formation (NB) and recently formed bone (RFB) was observed on the border of the biopsy (Toluidine blue stain; original magnification, x10). fig. 5b The recently formed bone (RFB) is present in the extremity of the new bone (NB). The new bone was formed around and is circumscribing the residual graft particles (RGP) (Mallory trichromic stain; original magnification, x10).

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journal of osseointegration Use of ADM and ABM/P-15 in alveolar ridge preservation

54.5% of fibrous tissue and marrow spaces in the control group. The test group presented 29.13% of new bone area, 7.8% of recently formed bone area (total amount of 36.93% of mineralized tissue), 42.4% of fibrous tissue plus marrow space and 20.67% of residual graft particles. The results showed no statistically significant differences (p>0.05) between the test and control groups (TG and CG) for the recently formed bone (RFB) area (p>0.05). However, the new bone area parameter (NBA) showed higher values to the control group, and statistically significant differences when compared with the test group (p=0.03). Additionally, the percentage of fibrous tissue plus marrow space areas was higher in the control group, and showed statistically significant differences in comparison with the test group (p=0.03). Additionally, in the test group, we found particles of ABM/P-15 (bone graft) corresponding to 20.67% of the total area (Table 1).

DISCUSSION The presence of tooth and the functional supporting tissues (cementum, periodontal ligament, and bone) play a crucial role in maintaining the dimensions of the alveolar process. Alveolar deformities resulting from tooth loss can cause esthetic and functional problems, especially in the anterior maxilla. During alveolar wound healing, most changes occur during the first 4 months (7, 28). Therefore, preservation of the ridge is important to avoid alveolar bone and soft tissue collapse, which could impair and compromise the prosthetic rehabilitation with implants or conventional prostheses (6,20,29,30). GBR has been used successfully to prevent alveolar ridge deformities (7,31-34). A number of materials, nonabsorbable and absorbable, have been used as membranes, with similar results in terms of bone formation (27,3539). The ideal barrier should be made of material less susceptible to membrane exposure or that cannot be significantly colonized by periodontopathogenic bacteria when exposed to the oral cavity.

NBA

RFB

FT+MS

RGP

100

38.66 ± 6.9*

6.84 ± 2.4

54.5 ± 6.5†

100

29.13 ± 6.6*

7.8 ± 1.9

42.4 ± 4.2†

20.67%

0.03*

0.62

0.03*

Legend: TA: total area; NB: new bone area; RFB: recently formed bone; FT+MS: fibrous tissue and marrow spaces; RGP: residual graft particles. Wilcoxon signed-rank test; *†Statistically significant difference between the groups (P <0.05)

table 1 .

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The present study shows that the GBR technique using ADM was able to reduce initial bone resorption. ADM has been used for numerous purposes and clinical studies have also used the ADM as a membrane for GBR in edentulous ridges and in association with immediate implants, suggesting that this material may be able to act as a barrier (11,34,40-42). Different studies showed that ADM can be used as a membrane for ridge preservation procedures in GBR, minimizing bone remodeling after tooth extraction (11,12,14,17). This study evaluated the use of ADM in post-extraction alveoli (control group – CG) to reduce ridge deformities and to induce bone formation within the alveoli. The histomorphometric analysis showed 38.66% of new bone tissue, 6.84% of recently formed bone and 54.5% of fibrous tissue and marrow spaces. These results are similar to those obtained by Borges et al. (12) that observed in dogs 58.99% of bone fill into the defect area and to those obtained by Schenk et al. (43), who reported that the newly formed bone occupied 55% of the defect volume. In our study, we found a total of 40.9% of mineralized tissuethat corroborated with the results of Schenk et al. (43) and Borges et al. (12) who observed approximately 38% and 42.47% of mineralized tissue. Jovanovic et al. (44), on the other hand, reported a bone density that varied from 50% to 57% in control sites or in sites treated with GBR. The basic principle of GBR is the isolation of epithelium and connective tissue cells from the bone defects (8). However, it is necessary that the available space for bone regeneration be maintained under the membranes or ADM, which have a tendency to collapse into larger bone defects. To maintain space and to act as a scaffold for cell migration, proliferation and differentiation, an association of bone grafts and GBR is suggested. As a result some bone substitutes have emerged with a promising outcome. In the present study, ABM/P-15 was used as bone graft in association with ADM. ABM/P-15 emerged in studies that focused on cell adhesion, which can influence the function and metabolism of various cell types during biologic processes. Qian and Bhatnagar (21) developed a synthetic peptide composed of a defined sequence of 15 amino acids, identical to a potent domain of cell alfa-1 chain receptor of type I collagen. They used particles of hydroxyapatite of bovine origin as carriers for this peptide. This combination allows the stimulation of fibroblast adhesion and the formation of three-dimensional colonies of extracellular collagen matrix, with mineralization foci, forming a structure similar to bone; in this way, it improves the efficacy of conventional replacement grafts in the treatment of intrabony defects. Krauser et al. (45) observed histologically that the sites treated with ABM/P-15 showed new bone around the graft particles, whereas sites treated with ABM remained encapsulated by a fibrous tissue. Smiler et al.

journal of osseointegration Novaes A.B. Jr. et al.

(46) compared two groups, ABM/ P-15 and ABM plus demineralized freeze-dried bone allograft, in sinus-lifting procedures. They observed after 4 months that there was 45% vital bone when ABM/P-15 was used, compared to 13% of the association to the allograft alone. To our knowledge, the present study is the first to evaluate the influence of ABM/P-15 associated with ADM in the prevention of ridge deformities after tooth extraction. The data show that the graft (ABM/P-15) efficiently promoted the maintenance of the buccalpalatal dimension (27). In the experimental group, the histomorphometric analysis showed 29.13% of new bone area, 7.8% of recently formed bone area, 42.4% of fibrous tissue plus marrow space and 20.67% of residual graft particles. The histological examination revealed that the central portions of the specimens were mainly occupied by regenerated bone and bone marrow. The biopsy showed mature bone with lamellar configuration throughout the specimens. The percentage of bone tissue was 37% and this value was comparable with the 6- to 8-month results from Froum et al. (47) (41.7%), who used nonabsorbable anorganic bovine bone mineral and ADM. Neiva et al. (48) found similar results to this study using Putty P15 and bioabsorbable collagen in post-extraction alveoli and 29.92% of new bone was observed. In accordance, Fotek et al. (32) reported a range of 27% to 32% of new bone formation 16 weeks after ridge preservation. In comparison with other bone grafts, the ABM/P-15 shows slightly increased bone formation into the socket. Norton et al. (49) used xenograft and porcine collagen membrane and reported that the mean percentage area of new bone formation was 25.6% after a mean of 26 weeks. Carmagnola et al. (50) filled the extraction sockets only with deproteinized bovine bone mineral and made undecalcified specimens after 7 months. The sections were comprised of 26.0 ± 23.7% lamellar bone and 8.4 ± 8.0% woven bone. Comparing with the present study, Carmagnola et al. (50) and Norton et al. (49) showed lower percentage of bone formation (about 10%). In this study, 20.67% of graft residual particles remained after 24 weeks of healing. This result was similar to numerous studies showing that full graft resorption was never observed. In fact, these data were superior to those of Artzi et al. (51) who reported 30% of graft residual particles. Two major differences were noted between this study and the one by Artzi et al. (51); they used a xenograft and allowed a longer healing period (9 months). Yet, even with the longer healing periods, a major component of the particulate xenograft remained. Similarly, Carmagnola et al. (50) found a significant proportion of xenograft particles (21.1%) remaining. This slower resorption rate could hinder new bone formation as shown by Vance et al. (25), in which bone was found in 61% of the sites grafted with an allograft versus 26% of sites grafted with a bovine

hydroxyapatite. Fotek et al. (32) reported an average of 14% to 15% of residual bone graft particles with a range of 27% to 32% of new bone formation 16 weeks after ridge preservation.

CONCLUSION In conclusion, ADM acted as a membrane and led to new bone formation within the alveoli. Also, the addition of ABM/P-15 resulted in the new bone formation within the alveoli. Although the ABM/P-15 showed satisfactory results at the 6-month observation period, the results were not considered relevant when used in this indication.

ACKNOWLEDGMENTS The authors want to thank BioHorizons, Inc. Birmingham, Alabama for donating the acellular dermal matrix used in this study. The authors report no conflicts of interest related to this study.

REFERENCES 1. Amler MH. The time sequence of tissue regeneration in human extraction wounds. Oral Surg Oral Med Oral Pathol 1969;27(3):309318. 2. Atwood DA, Coy WA. Clinical, cephalometric, and densitometric study of reduction of residual ridges. J Prosthet Dent 1971;26(3):280-95. 3. Araújo MG, Lindhe J. Ridge alterations following tooth extraction with and without flap elevation: an experimental study in the dog. Clin Oral Implants Res 2009;20(6):545-9. 4. Seibert JS. Treatment of moderate localized alveolar ridge defects. Preventive and reconstructive concepts in therapy. Dent Clin North Am 1993;37(2):265-80. 5. Lekovic V, Camargo PM, Klokkevold PR et al. Preservation of alveolar bone in extraction sockets using bioabsorbable membranes. J Periodontol 1998;69(9):1044-9. 6. Lekovic V, Kenney EB, Weinlaender M et al. A bone regenerative approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases. J Periodontol 1997;68(6):563-70. 7. Iasella JM, Greenwell H, Miller RL et al. Ridge preservation with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: A clinical and histologic study in humans. J Periodontol 2003;74(7):990-9. 8. Dahlin C, Linde A, Gottlow J, Nyman S. Healing of bone defects by guided tissue regeneration. Plast Reconstr Surg 1988;81(5):672-6. 9. de Andrade PF, de Souza SL, de Oliveira Macedo G, Novaes AB Jr, de Moraes Grisi MF, Taba M Jr, Palioto DB. Acellular dermal matrix as a membrane for guided tissue regeneration in the treatment of Class II furcation lesions: A histometric and clinical study in dogs. J Periodontol 2007;78(7):1288-99. 10. Novaes AB Jr., Souza SLS. Acellular dermal matrix graft as a membrane for guided bone regeneration: A case report. Implant Dent 2001; 10(3):192-6. 11. Novaes AB Jr, Papalexiou V, Luczyszyn SM, Muglia VA, Souza SLS,

journal of osseointegration Use of ADM and ABM/P-15 in alveolar ridge preservation

Taba M Jr. Immediate implant in extraction socket with acellular dermal matrix graft and bioactive glass: A case report. Implant Dent 2002;11(4):343-8. 12. Borges GJ, Novaes AB Jr, Grisi MFM, Palioto DB, Taba M Jr, de Souza SL. Acellular dermal matrix as a barrier in guided bone regeneration: a clinical, radiographic and histomorphometric study in dogs. Clin Oral Implants Res 2009;20(10):1105-15. 13. Wainwright DJ. Use of an acellular allograft dermal matrix (AlloDerm) in the management of full-thickness burns. Burns 1995;21(4):243-8. 14. Batista EL Jr, Batista FC, Novaes AB Jr. Management of soft tissue ridge deformities with acellular dermal matrix. Clinical approach and outcome after 6 months of treatment. J Periodontol 2001;72(2):26573. 15. Novaes AB Jr, Marchesan JT, Macedo GO, Palioto DB. Effect of in vitro gingival fibroblast seeding on the in vivo incorporation of acellular dermal matrix allografts in dogs. J Periodontol 2007;78(2):296-303. 16. Gapski R, Parks CA, Wang HL. Acellular dermal matrix for mucogingival surgery: a meta-analysis. J Periodontol 2005;76(11):1814-22. 17. Luczyszyn SM, Papalexiou V, Novaes AB Jr, Grisi MFM, Souza SLS, Taba M Jr. Acellular dermal matrix and hydroxyapatite in prevention of ridge deformities after tooth extraction. Implant Dent 2005;14(2):176-84. 18. Sottosanti JS. Aesthetic extractions with calcium sulfate and the principles of guided tissue regeneration. Pract Periodontics Aesthet Dent 1993;5(5):61-9,quiz 69. 19. Buser D, Brägger U, Lang NP, Nyman S. Regeneration and enlargement of jaw bone using guided tissue regeneration. Clin Oral Implants Res 1990;1(1):22-32. 20. McAllister BS, Haghighat K. Bone augmentation techniques. J Periodontol 2007;78(3):377-96. 21. Qian JJ, Bhatnagar RS. Enhanced cell attachment to anorganic bone mineral in the presence of a synthetic peptide related to collagen. J Biomed Mater Res 1996;31(4):545-54. 22. Barboza EP, de Souza RO, Caúla AL, Neto LG, Caúla FdeO, Duarte ME. Bone regeneration of localized chronic alveolar defects utilizing cell binding peptide associated with anorganic bovine-derived bone mineral: A clinical and histological study. J Periodontol 2002;73(10):1153-9. 23. Beck TM, Mealey BL. Histologic analysis of healing after tooth extraction with ridge preservation using mineralized human bone allograft. J Periodontol 2010;81(12):1765-72. Epub 2010 Jul 27. 24. Wang HL, Tsao YP. Mineralized bone allograft-plug socket augmentation: rationale and technique. Implant Dent 2007;16(1):3341. 25. Vance GS, Greenwell H, Miller RL, Hill M, Johnston H, Scheetz JP. Comparison of an allograft in an experimental putty carrier and a bovine-derived xenograft used in ridge preservation: a clinical and histologic study in humans. Int J Oral Maxillofac Implants 2004;19(4):491-7. 26. Fowler EB, Breault LG, Rebitski G. Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part I. A report of 2 cases. J Periodontol 2000;71(8):1353-9. 27. Fernandes PG, Novaes AB Jr, Queiroz AC, Souza SLS, Taba M Jr, Palioto DB, Grisi MFM. Ridge preservation with Acellular Dermal Matrix and anorganic bone matrix cell-binding peptide P-15 after tooth extraction in humans. J Periodontol 2011;82(1):72-9. 28. Johnson K. A study of the dimensional changes occuring in the maxilla following tooth extraction. Aust Dent J 1969;14(4):241-4. 29. Zubillaga G, Von Hagen S, Simon BI, Deasy MJ. Changes in alveolar bone height and width following post-extraction ridge augmentation using a fixed bioabsorbable membrane and demineralized freezedried bone osteoinductive graft. J Periodontol 2003;74(7):965-75. 30. Simon BI, Von Hagen S, Deasy MJ, Faldu M, Resnansky D. Changes in

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alveolar bone height and width following ridge augmentation using bone graft and membranes. J Periodontol 2000;71(11):1774-91. 31. Kirkland G, Greenwell H, Drisko C, Wittwer JW, Yancey J, Rebitski G. Hard tissue ridge augmentation using a resorbable membrane and a particulate graft without complete flap closure. Int J Periodontics Restorative Dent 2000;20(4):382-9. 32. Fotek PD, Neiva RF, Wang HL. Comparison of dermal matrix and polytetrafluoroethylene membrane for socket bone augmentation: a clinical and histologic study. J Periodontol 2009;80(5):776-85. 33. Pinho MN, Roriz VL, Novaes AB Jr et al. Titanium membranes in prevention of alveolar collapse after tooth extraction. Implant Dent 2006;15(1):53-61. 34. Fowler EB, Breault LG, Rebitski G. Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part II. Immediate endosseous implant placement. J Periodontol 2000;71(8):1360-4. 35. Hockers T, Abensur D, Valentini P, Legrand R, Hammerle CH. The combined use of bioresorbable membranes and xenografts or autografts in the treatment of bone defects around implants. A study in beagle dogs. Clin Oral Implants Res 1999; 10(6):487-98. 36. Polimeni G, Koo KT, Pringle GA, Agelan A, Safadi FF, Wikesjo UM. Histopathological observations of a polylactic acid-based device intended for guided bone/tissue regeneration. Clin Implant Dent Relat Res 2008;10(2):99-105. 37. Thomaidis V, Kazakos K, Lyras DN, Dimitrakopoulos I, Lazaridis N, Karakasis D, Botaitis S, Agrogiannis G. Comparative study of 5 different membranes for guided bone regeneration of rabbit mandibular defects beyond critical size. Med Sci Monit 2008;14(4):BR67-73. 38. Trombelli L, Farina R, Marzola A, Itro A, Calura G. GBR and autogenous cortical bone particulate by bone scraper for alveolar ridge augmentation: a 2-case report. Int J Oral Maxillofac Implants 2008;23(1):111-6. 39. Schwarz F, Rothamel D, Herten M, Wüstefeld M, Sager M, Ferrari D, Becker J. Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs. Clin Oral Implants Res 2008;19(4):402-15. 40. Griffin TJ, Cheung WS, Hirayama H. Hard and soft tissue augmentation in implant therapy using acellular dermal matrix. Int J Periodontics Restorative Dent 2004;24(4):352-61. 41. Novaes AB Jr, Pontes CC, Souza SL, Grisi MF, Taba M Jr. The use of acellular dermal matrix allograft for the elimination of gingival melanin pigmentation: case presentation with 2 years of follow-up. Pract Proced Aesthet Dent 2002;14(8):619-23; quiz 624. 42. Novaes AB Jr, Grisi DC, Molina GO, Souza SL, Taba M. Jr, Grisi MF. Comparative 6-month clinical study of a subepithelial connective tissue graft and acellular dermal matrix graft for the treatment of gingival recession. J Periodontol 2001;72(11):1477-84. 43. Schenk RK, Buser D, Hardwick WR, Dahlin C. Healing pattern of bone regeneration in membrane-protected defects: a histologic study in the canine mandible.Int J Oral Maxillofac Implants 1994;9(1):13-29. 44. Jovanovic SA, Hunt DR, Bernard GW, Spiekermann H, Wozney JM, Wikesjo UM. Bone reconstruction following implantation of rhbmp-2 and guided bone regeneration in canine alveolar ridge defects. Clin Oral Implants Res 2007;18(2):224-30. 45. Krauser JT, Rohrer MD, Wallace SS. Human histologic and histomorphometric analysis comparing OsteoGraf/N with PepGen P-15 in the maxillary sinus elevation procedure: a case report. Implant Dent 2000;9(4):298-302. 46. Smiler DG, Johnson PW, Lozada JL, et al. Sinus lift grafts and endosseous implants. Treatment of the atrophic posterior maxilla. Dent Clin North Am 1992;36(1):151-86; discussion 187-8.

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49. Norton MR, Odell EW, Thompson ID, Cook RJ. Efficacy of bovine bone mineral for alveolar augmentation: A human histologic study. Clin Oral Implants Res 2003;14(6):775-83. 50. Carmagnola D, Adriaens P, Berglundh T. Healing of human extraction sockets filled with Bio-OssÂŽ. Clin Oral Implants Res 2003;14(2):137-43. 51. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets. Part 1: Histomorphometric evaluations at 9 months. J Periodontol 2000;71(6):1015-23.

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journal of osseointegration

Aris Petros Tripodakis1, Hercules Goussias2, Panagiotis Andritsakis 3 1

Associate Professor, National and Kapodistrian University of Athens, Department of Prosthodontics Lecturer, National and Kapodistrian University of Athens, Department of Prosthodontics 3 Instructor, National and Kapodistrian University of Athens, Department of Prosthodontics 2

Immediate prostheses on one-piece trans-mucosal implants in flapless surgical procedures Case Series Report. Part I: full arch rehabilitations to cite this article Tripodakis AP, Goussias H, Andritsakis P. Immediate prostheses on one-piece trans-mucosal implants in flapless surgical procedures – Case Series Report. Part I: full arch rehabilitations J Osseointegr 2012;2(4):31-36.

KEY WORDS Flapless surgery; Full arch prosthesis; One piece implants.

ABSTRACT

Introduction

Aim The aim of the present case series report is to illustrate a clinical technique and present the application of onepiece transmucosal implants in flapless surgical procedures, supporting full arch immediate prostheses. Materials and methods A total of 294 implants (Xive TG, Friadent, Germany) have been used to support full arch immediate prostheses, over the last six years and have been in function for at least one year. The surgical placement of five or more implants per case involved immediate extraction and intrasocket flapless placement, combined with minimal flap elevation in the areas of healed extraction sites (43 mandibular and 7 maxillary arches). In all cases immediate provisionalization followed. Detailed three-dimensional cone-beam localized volumetric tomography preceeded the surgical procedures. The delivery of the final ceramo-metal prostheses was accomplished within a 20 day period. Results Six implants failed to osseointegrate. All other implants are still successfully bearing the final prosthesis for the time that they have been followed. Soft tissue reaction was favorable from both the biologic and esthetic point of view. Conclusion The flapless placement of one piece implants into edentulous healed sites is a predictable procedure in the presence of abundance of supporting bone as confirmed by 3-D imaging. On the other hand, immediate extraction placement of one piece implants allows the engagement of sound bone located deeper into the socket and provides adequate mechanical support of the soft tissue architecture that is preserved predictably. In all cases the prosthetic procedures are accomplished without disturbing the hardsoft tissue interface as the abutment-prosthesis interface is coronally elevated by the virtual design of the implant.

Osseointegrated implants were originally successfully applied by the two stage surgical approach. The implant insertion at first stage was followed by the abutment connection during a second stage surgical procedure. In this approach the two piece implant–transmucosal abutment complex was absolutely necessary and therefore implemented. The connection of the two separate pieces in intimate vicinity with the vulnerable hard and soft tissue interface of the supporting structures, inevitably was followed by biological flaws (1,2). The implant-abutment junction’s micro gap could act as a bacterial trap (3). The retrieval or interchange of the transmucosal element, on the other hand, could generate an adverse biological consequence of the disruption of the intimate soft tissue adaptation. Nowadays, one stage immediate transmucosal provisionalisation and function have been widely documented and broadly clinically applied both in single and multiple implant restorations (5, 6, 7). Such an approach totally eliminates the requirement of the two-piece implant/abutment complex, allowing the application of one-piece transmucosal implants. Thus the implant-restorative interface is elevated on a higher level, closer to the marginal area of the peri-implant soft tissue. In that way the previously described biological drawbacks are fully eliminated. Clinical procedures are facilitated and oral hygiene is more controllable. Minimal or no flap elevation combined with one stage surgery has also been suggested (8, 9). Thus, the surgical trauma is reduced minimizing post-surgical discomfort. By applying one-piece implants in flapless surgical procedures, mechanical support is immediately provided to the soft periimplant tissue collar. Also the

journal of osseointegration Tripodakis A.P., Goussias H. and Andritsakis P.

fig. 1A 3D tomographic evaluation of upper right quadrant.

fig. 1B Preoperative clinical situation of edentulous maxilla.

mm in height and 5 mm in width were included. Therefore the danger of an unsuccessful implant placement due to the limited visual access caused by the flapless surgical approach was minimized.

Presurgical preparation

Conservative periodontal treatment preceding the surgery involved full mouth sub-gingival scaling when natural teeth where preoperatively present. The patients were repeatedly instructed to perform thorough plaque control. Antibiotics were prescribed one day preoperatively. fig. 1C Flapless implant surgical insertion by levelling the threadedsmooth interface with the soft-hard tissue interface.

intimate soft tissue adaptation on the coronal part of the implant remains undisturbed. Therefore the maintenance and the preservation of the pre-existing soft tissue architecture are fairly accomplished. The aim of the present case series is to illustrate a clinical technique and present the application of one-piece transmucosal implants in flapless surgical procedures, supporting multiple implant immediate full arch prostheses.

Materials and Methods Patient population

A total of 50 patients in general good health (20 men and 30 women) have received full arch immediate prostheses (7 maxillary and 43 mandibular), supported by 294 implants in total, that have been in function over the last six years. Fifteen smokers were not excluded while only 4 patients were fully edentulus.

Radiographic evaluation

The presence of sufficient residual bone volume was confirmed radiographically. In all cases orthopantomographic imaging was followed by detailed three-dimensional cone-beam localized volumetric tomography (Morita Accuitomo, Japan) (Fig. 1a). Only patients that presented supporting bone of at least 13

Surgical procedure

In edentulous sites (Fig. 1b) the surgical approach was accomplished without flap elevation, through a minor slit of the tissue (Fig. 1c), guided by the related tomogram, leveling the threaded-smooth interface with the softhard tissue interface. No surgical guide was used while no attempt was made to attain absolute parallelism of the implants. The common path of insertion for the future screw-retained superstructure on the short external retentive square features on the implant heads was granted by their tapered design and therefore was independent of the axial divergence of the implants. In posterior mandible sites, above the mandibular canal, 9,5 or 11 mm long implants were used. Generally, minimal amount of suturing was applied. In dentate sites (Fig. 2a) after atraumatic extraction of the teeth, the sockets were rinsed thoroughly with clorexidine solution. Thorough rinsing with saline solution followed. The flapless preparation of the implant bed was started inside the extraction socket, on the apical third of the palatal or lingual bone wall guided by the specific tomogram, in order to avoid contact with the labial osseous plate and was directed towards the basal bone. At least 13 mm long and 3.4 mm wide implants excluding the collar (Xive TG, DentsplyFriadent, Manheim Germany) were self-tapped with a torque of 42 N/cm (Fig. 2b).

Prosthetic procedures

Impression copings (Standard XiVE TG transfer impression copings, Dentsply-Friadent, Germany)

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journal of osseointegration Full arch rehabilitations on one-piece transmucosal implants. Case series

were mounted on the implants immediately after insertion (Fig. 2c). Although an open tray impression procedure would have been preferable for precision, a closed tray was used. The reason was that the existing open tray impression coping, originally designed for single implant restorations, is firmly engaging the external anti-rotational mechanism located on the head of the implant. In that way upon removal some of the impression copings would not eventually freely disengage. Occasionally however, on specific implants in fig. 2a Preoperative clinical situation of terminal mandibular dentition.

fig. 2b Immediate intrasocket implant placement providing adequate soft tissue support and preservation.

fig. 2C Closed tray impression copings were mounted on the implants immediately after insertion.

fig. 2D Initial occlusal registration procedures were immediately performed on the impression copings by using polyether registration material.

fig. 2e Improvement of the passivity of the fit of the metal framework was followed by corrective occlusal registration during try-in.

fig. 2f One year postoperative appearance extraorally.

which the heads were found to be below the soft tissue crest, open tray impression copings were used by simply snapping them on the implant head, without fastening them by the stabilizing screw. By doing so, the retentive impression coping head was engaged and lifted by the closed tray impression material and therefore a more

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fig. 2G One year postoperative appearance intraorally.

precise orientation was maintained. The final impression was made using polyether material (Permadyne heavy body 3M ESPE, Seefeld, Germany) and occlusal registration procedures followed using polyether registration material (Ramitec, 3M ESPE, Seefeld, Germany) (Fig. 2d). The impression copings

journal of osseointegration Tripodakis A.P., Goussias H. and Andritsakis P.

were then replaced by healing cups on which transitional pressure cured shell acrylic restorations were intraorally relined. Unfortunately no other available components could offer a more viable transitional approach. The clinical possibility of using additional natural tooth retention for the provisional restoration by strategically postponing the extraction of certain teeth, has also been applied. Standard prosthetic procedures were used to fabricate the final screw-retained ceramo-metal prostheses that were inserted within the next three postoperative weeks. In most cases during the framework try-in, cut and laser welding procedures secured the passivity of fit (Fig. 2e). The cross-arch rigid stabilization of the implants, achieved by the splinting action of the superstructure, neutralized the effect of the initial reduction of mechanical stability of the implants, while their biologic osseous integration was not fully matured. Moreover upon the final delivery of the prosthesis the soft tissue healing was still in process.

Thus an occasional partial visual exposure of the Titanium transmucosal collar zone was to be expected following the healing completion (Fig.2f, 2g).

Results In total 294 implants were inserted supporting 7 maxillary and the 43 mandibular full-arch reconstructions. The overall outcome after one to six years of function was shown to be favorable from a functional, biologic and esthetic point of view. Osseointegration was successfully achieved with the exception of 5 implants (4 implants in two mandibular reconstructions and 1 maxillary) that failed after a period of approximately 6-18 months of function. In these 3 cases, the insertion of additional implants was mandatory and the reconstruction of a new prosthesis followed. All other implants are still successfully supporting the final prosthesis.

fig. 3a Preoperative clinical situation of a maxillo-mandibular terminal dentition. fig. 3b Preoperative orthopantomogram.

fig. 3C Soft tissue healing 15 days postoperatively in the maxilla.

fig. 3d Soft tissue healing 15 days postoperatively in the jaw.

fig. 3e Clinical appearance 25 days postoperatively.

fig. 3f Orthopantomogram 5 years postoperatively.

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journal of osseointegration Full arch rehabilitations on one-piece transmucosal implants. Case series

Soft tissue reaction was also biologically favorable. Moreover the prosthetic procedures are accomplished without disturbing the hard-soft tissue junction as the implant/restorative interface is established away from it, due to the virtual one-piece design of the implant (Fig. 3a-3f). In general in the treated cases cervical esthetics was not a priority and therefore the occasional esthetic compromise due to the partial visual exposure of the Titanium transmucosal collar zone, was considered esthetically insignificant.

Discussion The placement of one-piece trans-mucosal implant by a flapless surgical approach is a clinical procedure providing simultaneously hard and soft tissue integration. It combines the necessary foundation by the anchorage to the supporting bone with the provided adequate mechanical support and undisturbed biologic response of the soft tissue. The machine-polished transginval implant extension Ti collar (TG), acts as the ideal support for the soft tissue intimate adaptation, while the oral hygiene procedures are facilitated. The flapless approach in all cases (both dentate and edentulous) is mainly a rather atraumatic surgical procedure. Denuding the bone from the periosteum subsequent to an elevated flap, momentarily jeopardizes the normal blood supply of the surgical site, and inevitably leads to further bone loss. In a flapless surgical intervention the host defense mechanism and the regenerative potential are kept in full action by the uninterrupted blood supply during wound healing (10, 11). In addition to that, the reduced trauma is favorably accepted by patients. Nevertheless the visual access of the surgical site is inevitably limited. Surgical guidance in the presently described clinical approach was assisted by the detailed cone-beam three-dimensional tomographic evaluation. Computer navigation systems could even better secure an accurate implant orientation. In all cases however, the absolute prerequisite for flapless surgical procedures is the presence of adequate bone volume both in height and width. If the bone volume is limited, flap elevation is mandatory. In dentulous patients immediate implant placement into the extraction socket provides adequate support of the soft tissue architecture that is predictably preserved (12-14). The implant in such cases tends to attain a deeper location that is compensated by the presence of its transmucosal extension. Thus the implant restorative interface is elevated in a more coronal level, away from the supporting bone. Immediate loading of the implants provided by the function established by the immediate provisionalization is a very well documented modality both experimentally and clinically.

Favorable load distribution, that results from splinting the implants by the immediate provisional restoration, assures the elimination of micro movements. Nkenke et all concluded in their research: immediate loading does not affect the bone mineral apposition rate when compared with unloaded implants. Rigid splinting seems to be the crucial factor for implant success. Uncontrolled masticatory forces can cause failure after partial loss of the provisional restoration (4). In the 50 clinical cases that were restored by full arch immediate prostheses on one-piece trans-mucosal implants inserted by the flapless surgical approach, the failures that occurred can be interpreted as follows. › The reported mandibular failures of four implants 15 mm in length, inserted in immediate extraction compromised sites between two mental foramina developed a painful reaction and subsequent radiographic radiolucency. Possible explanations could be the unfavorable biologic and anatomic condition of the defect or even the overheating of the dense mandibular bone. › The maxillary implant failed due to overloading that followed the fracture of a soldered joint. › The 3 reconstructions had to be repeated after additional implant placement. The social advantages and quality of life enhancement of the presented clinical modality are also important. The reduced trauma and the immediate restoration are the important features for treatment acceptance and patient satisfaction. The decrease of the number of both the necessary clinical procedures and the components required creates a cost effective treatment, financially beneficial for the patient and the dentist.

Conclusions 1. The flapless placement of one piece implants into edentulous healed sites is a predictable procedure in the presence of abundance of supporting bone as confirmed by 3-D imaging. 2. The placement of such implants in immediate extraction sockets allows the engagement of sound bone located deeper into the socket and provides adequate mechanical support of the soft tissue architecture that is predictably preserved. 3. The limited visual access has to be compensated by the 3-D tomographic evaluation. 4. The prosthodontic procedures are accomplished without disturbing the hard-soft tissue interface as the abutment-prosthesis interface is coronally elevated by the virtual design of the implant. One-piece trans-mucosal immediate implants, 5. combined with flapless surgical procedures can be used predictably for immediate prostheses with functional, biologic and esthetic advantages.

journal of osseointegration Tripodakis A.P., Goussias H. and Andritsakis P.

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