JOS - European Journal of Oral Surgery

JOS European journal of oral surgery

Official journal of the SocietĂ Italiana Specializzati in Chirurgia Odontostomatologica ed Orale

2 ISSUE 1 VOL.

June 2011

ISSN 2037-7525

CASA EDITRICE ARIESDUE

ITALIA PRESS EDIZIONI

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European journal of oral surgery Official journal of the SocietĂ Italiana Specializzati in Chirurgia Odontostomatologica ed Orale www.ejos.eu

European journal of oral surgery

Editor-in-chief

Publisher

Prof. Franco Santoro (Italy)

ARIESDUE SRL

ITALIA PRESS EDIZIONI

Via Airoldi, 11 22060 Carimate (CO) +39 (0)31.79.21.35 +39 (0)31.79.07.43 www.ariesdue.it info@ariesdue.it

Via Larga, 8 20122 Milano (MI) +39 (0)2 86.46.49.21 +39 (0)2 86.90.372 www.italiapressedizioni.it info@italiapressedizioni.it

Editorial Director Prof. Carlo Maiorana (Italy)

Associate Editors

ISSN: 2037-7525

Prof. Piero Balleri (Italy) Prof. Pascal Valentini (France)

Editorial Board Dr. Giovanni Battista Grossi (Italy) Prof. Alan Herford (USA) Prof. Fouad Khoury (Germany) Prof. Jaime A. Gil (Spain) Prof. Massimo Simion (Italy) Prof. Anton Sculean (Switzerland) Prof. Tiziano Testori (Italy) Prof. Nicholas Toscano (USA) Prof. Leonardo Trombelli (Italy) Dr. Istvan Urban (Hungary)

DIRECTOR Dino Sergio Porro EDITORIAL STAFF Angela Battaglia: a.battaglia@ariesdue.it Cristina Calchera: farma@ariesdue.it Simona Marelli: doctoros@ariesdue.it MARKETING & ADVERTISING Barbara Bono: b.bono@ariesdue.it Paola Cappelletti: p.cappelletti@ariesdue.it Franco De Fazio: f.defazio@ariesdue.it WEB & GRAPHIC DESIGN Michele Moscatelli: grafica@ariesdue.it Simone Porro: simone@ariesdue.it Cover image courtesy of Giampiero Gasperini

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JOS VOL.2 N.1 2011

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LEADING REGENERATION

European journal of oral surgery

Issue 1 Volume 2 June 2011

page 9

Complications in guided bone regeneration

page 19

Simultaneous sinus and horizontal augmentation utilizing a resorbable membrane and particulated bone graft: a technical note and 7-year follow-up of a case

page 25

The removal of a deeply impacted lower third molar by means of the bone lid technique with piezoelectric instruments

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JOS VOL.2 N.1 2011

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European journal of oral surgery Official journal of the SocietĂ Italiana Specializzati in Chirurgia Odontostomatologica ed Orale

European journal of oral surgery

Editor-in-chief

Prof. Franco Santoro SISCOO President

Editorial Dear colleagues, According to the scientific schedule for 2011, SISCOO has been organizing two cultural events with the aim to focus on some of the most burning topics in osseointegration. The first course, which just took place in Milano by Dr Stefano Gracis, covered the success in implant prosthodontics. The lecturer showed all the situations in which, due to a non ideal implant placement, some prosthetic arrangements can overcome an aesthetic problem. The course, fully booked, was highly appreciated by all participants.

The second course will take place on october 29th in Milan, will be held by Dr Jean Pierre Gardella and will cover the soft tissue management around implants.

We think that the continuing education program is a fundamental part of the training for the specialists in oral surgery and the dentists who devote themselves to this fascinating branch of dentistry including periosurgery, oral surgery and implantology and giving such a tool is a duty from a scientific society.

I am proud to announce that the 2nd SISCOO Congress will be held in Milan, September 22nd 2012, and will host seven keynote speakers lecturing on oral surgery, oral pathology, laser and stress control.

I hope that you will save the date and join us.

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JOS VOL.2 N.1 2011

Manuscript Preparation

European journal of oral surgery ISSN: 2037-7525 www.ejos.eu

Guidelines for Authors Manuscript Submission Manuscripts can be uploaded in the “Manuscript Submission” section of the journal’s website http://www.ejos.eu or sent in a CD to the publisher: Ariesdue Srl via Airoldi, 11 - 22060 Carimate (Co) Italy e-mail: farma@ariesdue.it as a PC Word (doc) file with tables and figure legends at the end of the document. Figures should be supplied separately.

• Manuscripts should be typed in a 12-point font and double-spaced; their length should range from 6,000 to 18,000 digits for Case Reports and from 10,000 to 25,000 digits for Monographs. The number of visual components (images and tables) should not exceed 18.

• The first page must include the title of the article (descriptive but as concise as possible); the complete names, titles, addresses, and professional affiliations of all authors, as well as phone, fax, and e-mail address for the corresponding author, who will be assumed to be the first author unless otherwise noted.

• The number of authors should be limited to 7 for Monographs and to 4 for case reports (if more, justification should be provided).

• A 50 to 250-word structured abstract of the article must be included.

• Trade names: When a trade name of a product is used, the name of the manufacturer must appear parenthetically at first mention.

• Tables: Each table should be logically organized, typed on a separate page at the end of the manuscript, and numbered consecutively. Table title and notes should be typed on the same page.

• Legends: There should be an individual legend for each illustration. Figure legends should be typed as a group on a separate page at the end of the manuscript. Detailed captions are encouraged. For micro-photographs, specify original magnification and stain.

• References: References should be limited to those specifically referred to in the text, cited numerically, in order of appearance in the text and listed according to the following style (Vancouver style): Journals: 1. Del Fabbro M, Testori T, Francetti L, Taschieri S, Weinstein R. Systematic review of survival rates for immediately loaded dental implants. Int J Periodontics Restorative Dent 2006;26:249–264.

Submission Letter

Books:

A Submission Letter must be signed by all authors and supplied as a separate pdf file along with the manuscript.

1. Tarnow DP, Cho S-C, Wallace SS, Froum SJ. Effect of surface morphology on implant survival in the grafted maxillary sinus. In: Jensen OT (ed). Bone Graft, ed 2.

Chicago: Quintessence; 2006. p.223–227.

Figures

Publishers ARIESDUE SRL

ITALIA PRESS EDIZIONI

Via Airoldi, 11 22060 Carimate (CO) +39 (0)31.79.21.35 +39 (0)31.79.07.43 www.ariesdue.it info@ariesdue.it

Via Larga, 8 20122 Milano (MI) +39 (0)2 86.46.49.21 +39 (0)2 86.90.372 www.italiapressedizioni.it info@italiapressedizioni.it

Figures should be supplied along with the manuscript but as separate high-resolution digital image files (jpg or tiff), and numbered consistently.

Permissions and Waivers • Permission of author and publisher must be obtained for the direct use of material (text, photos, drawings) under copyright that does not belong to the author.

• Waivers must be obtained for photographs showing persons. When such waivers are not supplied, faces will be masked to prevent identification.

• Permissions and waivers should be supplied along with the manuscript and the Submission Letter as a separate pdf file.

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Monograph

Complications in guided bone regeneration Francesco Briguglio* Massimo Simion**

University of Milan, School of Dentistry Dental Clinic Ospedale Maggiore IRCCS Cs’ Granda Milan (Italy) Director: Prof. Franco Santoro *Department of Implantology **Professor and Chairman, Department of Periodontology

Aim:

Allow to correctly prevent, identify and treat the complications that could occur during GBR treatments requiring resorbable and non-resorbable membranes.

Materials and methods: A correct analysis of the patient’s anatomical characteristics and pathological conditions during a GBR treatment permit a reduction of complications; if these should occur, their immediate identification is fundamental and a correct terapeutic treatment should be implemented in order to not invalidate the regenerative procedure and at the same time to permit the dental implant rehabilitation.

Key words: Guided bone regeneration, pre-surgery analysis, resorbable and non-resorbable membranes, membrane exposure, infection, complications, treatment.

Conclusion: We believe that the knowledge of the guidelines regarding GBR is the only instrument that allows the clinician to solve the complications still connected to the use of synthetic materials: bacterial infections.

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Briguglio F. and Simion M. Intraoperative complications

Introduction Guided bone regeneration (GBR) consists of surgical techniques that allow to reconstruct missing bone volume for implant-prosthodontic rehabilitations not otherwise possible. These techniques can be used for bone regeneration in both horizontal and vertical defects by increasing the thickness of the atrophic ridge and extending its height. The performance of these volumetric gains requires operational skill in the management and manipulation of soft and hard tissues as well as competence in the use of grafting materials and covering membranes.

It is clear that these surgical techniques are elective and, despite the indubitable demonstration of their predictability and efficacy in both horizontal and vertical bone regeneration (Esposito, 2006; Rocchietta, 2008) (1, 2), there is no doubt that the ability of the surgeon affects the success of such surgical procedures and significantly influences failure rates.

In order to allow early detection of possible complications and especially to prevent their onset, we will describe below the intra-operative difficulties that may be encountered and how it is possible to prevent and treat them.

Description of GBR complications Complications in bone regeneration are usually divided in intraoperative and post-operative. Although the former almost entirely overlap with common complications in implant surgery, the latter are mostly associated with the use of biomaterials and covering membranes.

Intraoperative complications are the following: • Injuries to vascular structures.

• Injuries to nervous structures.

• Dehiscences and fenestrations of the primary flap.

The surgeon’s knowledge of surgical anatomy is essential to prevent damage to important anatomical structures.

The division of the oral cavity in anatomical areas and the classification of the edentulism can be useful to focus attention on the anatomical structures that may be involved during the operative act; in this respect the most used classification is that of Kennedy (3), which divides the partially edentulous arches on the basis of missing teeth into four classes and simultaneously identifies the area. This classification has been modified by Misch-Judy (4) by adding a morphological description of the bone in the area to be rehabilitated.

Starting from an accurate overview in the light of such classifications, the operator can then focus attention on what could be the anatomical risk in certain areas and thus prevent possible complications (Table 1).

Regarding the dehiscence or the fenestration of the primary flap, these complications can be caused by improper handling of soft tissues. In regenerative surgery, the management of the edges is very important because they have to cover the augmented volumes obtained during surgery and thus require proper flap design and periosteal incisions in order to avoid tensions when suturing. On one hand, these procedures expose the surgeon to the risk of fenestration of the edge in the search for maximum mobilization of the tissues by means of periosteal incisions and, on the other hand, there is a risk of dehiscence of the flap if tension is not sufficiently eliminated.

Post-operative complications Post-operative complications in the performance of regenerative procedures are mainly the following.

• Late dehiscence of the flap.

Areas involved in surgical act

Neural structures

Maxilla: anterior segment

Neurovascular infraorbital bundle Neurovascular bundle Palatin-nose

Maxilla: lateral-posterior segment

Palatin ant. nerve

Alveolar-antral artery Ant. palatine artery

Mandible: anterior segment

Mental’s neurovascular bundle

Submental artery Undertongue artery Deep lingual artery

Mandible: lateral-posterior segment

Inf. alveolar nerve Buccal nerve Lingual nerve

Facial artery Mylohyoid artery

TABLE 1

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Vascular structures

Monograph • Exposure of the membrane.

• Infection without exposure of the membrane.

• Mobilization of support and fixing screws of the membrane.

Inadequate mobilization of the primary flap, though enabling a closure for primary intention of the surgical wound, often leads to delayed dehiscence. The healing of soft tissue is characterized by its gradual contraction, with a minimum volume at about two weeks after surgery, when the highest incidence of exposure of the membrane has been observed.

An inadequate design of the flap may also cause exposure of the membrane.

The use of a provisional removable prosthesis or improperly modelled fixed provisional prosthesis can disturb the healing of the underlying tissues. If the negative action of the temporary prosthesis is extended over time, it can inhibit, due to the micromovements, the vascular anastomoses and block neoangiogenesis, which is essential in the first phase of bone formation.

Closed flap infection represents another less common complication. The causes of bacteria introduction below the gum seal may be sought at different times of treatment. The sterility of the grafted materials and regenerative tools (membrane, tenting and fixing screws) together with the cleaning of the operative field (cleaning the surgical site, root planing of the neighboring teeth, avoiding the recipient site contact with saliva) are necessary conditions to reduce the possibility of infection at this time.

At a second time also suture removal can also generate an infection; in fact, if the sutures are removed without precautions (application of 0.2% chlorhexidine gel on the sutures before their removal) they can become carriers of infection when they pass beneath the tissue.

Finally, the teeth close to the surgical site can become a gateway for bacteria during the healing period of 6-8 months. Both the periodontium, in the case of deep pockets, and the endodontium, in the case of beyond apex or lateral injury, may be preferential channels for bacteria’s access.

Before analyzing in detail the single complications that may occur in the performance of GBR techniques, it is useful to describe how patient selection, by understanding of the difficulties that may occur during the procedure, minimizes the percentage of failures.

Presurgical analysis

mucous membranes can slow down and complicate healing. The presence of macroglossia, of parafunctions or even bad habits, such as the introduction of foreign bodies into the oral cavity, must be carefully controlled by the surgeon prior to performing any bone regeneration, as they are possible factors that can aggravate the healing process.

At the end of a thorough anamnesis it is essential that surgeon assess the teeth in both dental arches and the endodontic health of the teeth near the edentulous area to be rehabilitated. Although periodontitis is not an absolute contra-indication to implant rehabilitation, the reduction of concentration of bacteria in the oral cavity and therefore a previous surgical periodontal therapy reduces the possibility that infectious processes may occur at the level of the surgical site (5).

An analysis should also carefully consider both endodontic and periodontal conditions of the teeth near the area to be rehabilitated; in fact, the presence of endodontic or periodontal lesions at the expense of those teeth may be responsible for bacterial access to the surgery site. For this reason a proper treatment of these dental elements and the certainty that they do not affect the post-operative course is a conditio sine qua non for the implementation of regenerative surgery.

Surgical site analysis After a correct dental anamnesis the surgeon’s attention must turn to a careful analysis of the surgical site in order to reduce intra-operative and post-operative problems.

Since the most common complication in GBR is primary flap dehiscence, resulting in exposure and bacterial colonization of the membrane, special attention must be paid, during the pre-surgical evaluation of the soft tissue, because they must cover and protect during the healing process the graft material and the membrane. Therefore it must first be ensured that the soft tissues are not inflamed. If they are, they are less resistant to mechanical and bacterial injury and require longer periods for complete restitutio ad integrum.

In the case that tooth extractions were performed, it is recommended that the patient wait at least 8-10 weeks before surgery for the complete healing of the soft tissues at the level of post-extraction sites (6).

The surgeon should also ensure that there are no voluminous scars (for example due to repeated endodontic surgery) because the mobilization of the flaps will prove much more complex due to the presence of inelastic fibrous cords. The surgeon should also ensure that there is not a ridge of muscle migration that may oppose a coronal displacement of the flap (Fig. 1).

Dental health status An important step in the prevention of complications in GBR is proper patient selection, by means of a careful dental history aimed at investigating conditions that would prevent a prosthetic implant rehabilitation or complicate the intervention and subsequent recovery.

The presence of malocclusion, such as a cross-bite or even antagonistic elements, can affect the positioning of the implant, or, once the increase in volume of the hard tissue is performed, it can mechanically traumatize tissues during healing. A normal salivary flow rate is also important for soft tissue healing; conditions such as dry

FIG. 1

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Briguglio F. and Simion M. Another important factor is the presence of an adequate band of keratinized gingiva on the ridge that allows a continous sealed suture of the flaps margins through a precise pairing of the edges and that the tearing of the soft tissue during suture is avoided (Fig. 2). In the event that this band of keratinized gingiva is not present, it is necessary to carry out a preventive intervention of epithelium-connective free graft in order to create ideal conditions for the subsequent regenerative surgery.

In addition to a qualitative analysis of the soft tissues, the anatomical features of the area to be regenerated must also be examined and the depth of the vestibular fornix evaluated. If it is not deep enough, it does not allow coronal movement of the flap (Fig. 3), or the presence of frenula with high insertion in frontal areas that can restrict coronal movements and therefore must be removed or repositioned beforehand.

For proper operation planning it is also helpful to consider major operational complications in case it is necessary to obtain a certain volume of bone regeneration in the edentulous interspersed areas or in the upper jaw.

In the first case, the major difficulty is due to the tensions that occur in the coronal displacement of the flap due to the presence of mesial and distal teeth. In the second case, the greatest complications arise from the anatomical features of the palatal mucosa.

When rasing the primary flap in the upper jaw, the surgeon must use the techniques described by Triaca (7), or even those techniques such as the translation of the palatal flap described by Tinti (8), in order to obtain adequate coverage of the site.

After the pre-operative analysis, including the surgeon’s ability to perform the GBR procedure according to its degree of difficulty, it is possible to proceed with the technique by using those measures that may limit the incidence of complications during both the surgical and the post-surgery phase.

FIG. 2

FIG. 3

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Prevention of complications in GBR GBR remains an elective technique both for the use of biomaterials subject to possible infections and for the technical difficulties that may be encountered during the surgical procedure. There are certain steps that the surgeon should implement in order to minimize the complications.

Pre-operative bacterial control The preparation of the room and the patient must have the same requirements as oral surgery, beginning with the preparation of the sterile surgical field.

In order to reduce the intra-oral and extra-oral bacterial charge, the patient should rinse with 0.2% chlorhexidine digluconate for two minutes, while a solution of Betadine (Viatris) is applied to the lips and skin around the mouth.

Antibiotic prophylaxis involves the administration of 875 mg amoxicillin plus 125 mg clavulanate (Augmentin, GlaxoSmithKline) from the day before surgery and continued for a week with a dose of 1 g every 12 hours.

An anti-inflammatory prophylaxis, with NSAIDs, should be administered one hour before surgery and then taken twice a day for a week. The control of intra-oral bacteria is maintained with two rinses of 0.2% chlorhexidine twice daily until suture removal.

Flap design and mobilization It is more in horizontal GBR than in the vertical one that the management of soft tissue is a fundamental step for the success of the intervention. In most cases, this is the moment when it is possible to commit the technical errors that lead to the most common complications in GBR and the exposure of the membrane.

The crestal incision must fall entirely in keratinized gingiva and be extended, in the case of intercalated edentulism, 1-2 mesial and distal teeth from the surgical site (depending on the type of regeneration to be performed). The vestibular incision is closed with two vertical relaxing incisions which must obviously be performed in the foraminal area of the chin nerve. At the lingual or palatal level, the incision proceeds intrasulucular without any release incisions.

The extension of the design of the exceeding flap compared to the surgical site allows a better mobilization of the flap and the release incisions must be distant from the membrane. Only in the case of horizontal regeneration, especially in the esthetic zone and after an assessment of the volume to be regenerated, is it possible to perform a distal vertical incision in order to avoid visible scars.

The manipulation of soft tissues at a later date requires a periosteal relaxing incision line parallel to the ridge that unites the vertical incisions at the base (Fig. 4); the penetration of the scalpel should involve just the periosteal layer, thus avoiding flap fenestrations and permitting, especially in the case of vertical regeneration, the coupling of the margins of the edges at least 10 mm from the underlying membrane. This is to avoid exposure of the membrane during physiological contractions of soft tissue whilst healing. Particular attention should be paid to the execution of the

Monograph periosteal incision in the foraminal area where, to avoid the section of nerve fibres that branch out in the thickness of the mucosa, it is necessary to perform a section of the periosteum with the tip of the blade not following a linear incision but fringing the periosteum, following a parabola that flanks the nervous fibres of the chin without injuring them. At tongue level, the flap is released by the section of the mylohyoid muscle fibres that must be carried out with blunt instruments to avoid injury to the major vascular structures present at the level of the floor of the mouth.

Preparation of the surgical site The surgical site must be accurately prepared in order to avoid soft tissue infiltrating between the graft and the bone. Once the site is skeletonized, it is necessary (curettes, back action), to accurately curette the bony surface with specific instruments, eliminating any possible granulation tissue or connective and periosteal tissue.

In case of intercalated edentulisms, the tooth surfaces near the site to be regenerated have to be adequately cleaned in order to eliminate possible subgingival bacterial deposits that have not been removed with professional prophylaxis. In the case of the presence of a prosthesis, it is a good practice to apply 0.2% chlorhexidine gel for a few minutes at the neck of the crown because here bacteria often find a niche favorable to their adhesion.

Furthermore, bone spicules or bone protusions must be eliminated with dental drill or bone rongeurs as they could produce tensions or even damage the edges when they are moved toward the crown.

Finally, the position of the fixing screws should be assessed during the perforation of the cortical for the blood supply, to avoid difficulties during their stabilization.

it might lead to nerve emerging.

Finally, membranes must be perfectly stable to prevent injury or the uncovering of the graft underneath; for these reasons mini-trans-cortical fixing screws are used: they are applied at the membrane margins both on the vestibular side and the lingual/palatal side to ensure stability. It is advisable to fix the membrane first to the lingual/palatal side and then to the vestibular one in order to easily place the graft with a direct view of the surgical field even with the membrane already present.

The application of the fixing screws is necessary if a non-resorbable membrane is used. The application of collagen membrane, which once wet perfectly adheres to the graft, requires fixing only if there is a risk of its mobilization (if there is horizontal regeneration of a considerable amount).

During the application of the fixing screws and of the tenting screws but also when the cortical bone is perforated for the vascular supply to the graft, it is necessary, in order to avoid iatrogenic injuries, to consider and respect the root anatomy of adjacent teeth and to evaluate the position of the mandibular nerve.

Suture The suture determines the seal of the operated site for the first two weeks of healing, before the complete closure of the wound. For this reason a proper execution is crucial for the success of the regenerative process.

Beside the materials used, also the change of position of the regeneration with respect to the primary incision requires different types of suture in vertical GBR and in horizontal GBR. In vertical GBR, once the flaps are properly mobilized and freed over the membrane surface for at least 10 mm, a passive suture is performed with horizontal mattress stitches alternated

Membrane positioning The correct positioning of the membrane represents a key moment in the prevention of its possible exposure or infection and in general for the success of the regenerative procedure.

Whether you use non-resorbable membranes (e-PTFE) or resorbable collagen membranes, they must have a dimension slightly larger than the graft surface; in this way even if the graft is compressed by the pressure of soft tissues, it remains covered by the membrane during the entire healing period and does not slip out.

Furthermore, the membrane must be carefully shaped to fit the graft and the bone surface passively avoiding avoiding to make some folds (it can often happen with collagen membranes), or it remains in tension, and in order to stay detached 2-3 mm from the root surfaces of adjacent teeth, since the gingival sulcus may be an access to bacterial colonization (Fig. 5).

Particular attention must be paid to the shaping of the e-PTFE membranes, because they may be responsible for lacerations of soft tissues and injuries to the nervous structures due to the consistency of this material.

It is therefore appropriate to smooth the sharp edges that can project onto the periosteal surface and, in case of regeneration in the foraminal area, to cut the membrane in order to avoid that, even under pressure,

FIG. 4

FIG. 5

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Briguglio F. and Simion M. with simple stitches so that the edges do not interface outside the internal surface and do not pucker.

On the teeth at the border of the regenerated area suspended sutures that surround the crown of the teeth are made, pushing the edges over the surface in order to avoid bacterial infiltration through this space.

The relaxing incisions are finally sutured with simple interrupted stitches. The ideal material for this surgical procedure is the e-PTFE suture, both for its physical and chemical features.

In horizontal bone regeneration it is possible to suture with simple interrupted stitches because the membrane and the graft are localized at the incision level and so the contraction of soft tissues in the healing phase would not determine the exposure. If regenerating a dehiscence implant or placing e-PTFE membranes lying over the ridge close to the coupling of the edges, horizontal mattress stitches are sometimes appropriate.

In both procedures it is important anyway not to cause ischemia of the tissues due to an excessive closure of the stitch as tissue ischemia is one of the main causes of necrosis and consequently of tissue contraction.

During the removal of stitches two weeks after surgery, in the case of horizontal mattresses stitches it is useful to cover the external portion of thread with 0.2%, chlorhexidine gel, so that when removing the thread, it does not bring bacterial agglomerates from stitch into the mucous membrane.

Finally, it is fundamental when removing the stitches to check, especially in the case of horizontal mattress stitches, that suture fragments are not left in situ, as they could be an ideal substrate for bacterial infection.

Provisional prosthesis The application of a provisional prosthesis that would not traumatize the surgical site, is essential for the success of regenerative procedures. In this case it is possible to create a fixed provisional prosthesis (Maryland bridge), which is preferred to a mobile prosthesis that could compress the healing soft tissues If there are no distal teeth, a mobile prosthesis to be modeled in order not to press onto the grafted site may be used, though not before 15-20 days after surgery and only in the case of horizontal bone regeneration.

Monitoring is also recommended with periodical checks on the stability of the mobile prosthesis because a variation in its position could determine tissue ischemia and necrosis and consequently an exposure of the operated site even in an advanced phase of the healing process. In case of vertical crest increase, no mobile prosthesis can be applied on the regenerated site, both for the possibility of dehiscence of the edge and for microtrauma that can occur over the graft that inhibit neoangiogenesis and thus the regenerative process.

Classification and treatment of complications in GBR In addition to the common complications in oral surgery, in regenerative surgery it is possible to face with

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specific issues related to the use of grafting materials and covering membranes. A separate beforehand analysis of the different complications in GBR is necessary, as these are closely linked to the materials used. Below, they are listed according to the type of membrane used.

Complications in the use of resorbable membranes Although in the literature there are no works that classify and describe in detail the complications of this type of membrane, clinical practice proves that even using very malleable materials one can run into postoperative problems.

Non-resorbable membranes, owing to their physical characteristics and space-making properties, are used almost exclusively to increase ridges requiring a horizontal vector. It is therefore important that a morphological evaluation of the site to be regenerated is made so as to overcome the physical non-resorbable membrane characteristics through the presence of bone walls that protect the graft from damage and stabilize it.

It sometimes happens that if this is not done carefully, the pressure on the graft from soft tissues, tongue, muscles, or even from the lips, compresses and reduces the volume of bone increased at the moment of the second surgical stage, preventing or complicating (if it changes the morphology of the graft) implant rehabilitation. In order to prevent this, in such cases it is sometimes advisable to place grafts larger than the bone volume to be regenerated. In case of mechanical trauma, this provides a sufficient volume of the regenerated bone at the moment of a second intervention.

Another technique described by Bornstein et al. (9) involves the use of two resorbable membranes stacked at the site to be regenerated. The histologic results showed that a double layer of membranes protects the underlying graft better and extends the filter effect against soft tissue, giving a greater guarantee for the amount of regenerated bone especially in significant regeneration.

Another complication in guided bone regeneration using resorbable membranes is their exposure during healing.

Although this is a lesser frequent occurrence and of a less concern when using resorbable membranes instead of non-resorbable ones, if this should arise, the success of the regenerative process is still at risk. It is therefore necessary to confront this complication correctly and with a full understanding of its characteristics.

Therefore frequent controls in the postoperative period are important for the early detection of membrane exposure, in order to start as soon as possible antibiotic and antiinflammatory therapy, both locally and systemically to allow the membrane to be firmly maintained for as long as possible. The collagen is degraded by salivary enzymes once it is exposed and it can be a vehicle for infection of the still sub-emerged membrane and the graft material below.

If it is difficult to keep the membrane in place for a period of 60 days, it is better to remove both the membrane and the graft in order to avoid poor regeneration. Should the resorbable membranes be exposed, a prompt pharmacological therapy and a careful removal of the infected parts are necessary to

Monograph allow even a partial regeneration of the site in order to enable the insertion of implants.

Complications in the use of non-resorbable membranes For both physical and chemical characteristics of the materials, the exposure of non-resorbable membranes is a much more frequent and more serious complication than the exposure of resorbable ones.

The e-PTFE is in fact a more rigid material than collagen and therefore with higher risks of dehiscence.

GORE membranes are also an excellent substrate for bacterial adhesion and therefore in case of exposure are rapidly colonized and infected (Simion, 1994) (10-11).

The treatment of premature membrane exposure depends on its location, extent and the presence or absence of infection.

Verardi and Simion article (12) divided the different types of treatment as follows. â&#x20AC;˘ Class I It is defined as a small (<3mm) dehiscence of the soft tissues without the presence of purulent exudate (Fig. 6), in which case the exposed membrane can often be maintained through specific oral hygiene by applying 0.2% chlorhexidine gel twice a day to reduce plaque formation and inflammation of the surrounding tissues (13). If exposure has occurred in a marginal portion of the membrane, it can be cut and closure of the fenestration can be attempted. At other times it is necessary to perform a connective tissue graft covering the portion of tissue during regeneration (Fig. 7 a-f).

In cases where the membrane remains exposed, it cannot be kept for more than 3-4 weeks, because the inflammation present on the surface could damage the deeper tissues in the process of regeneration, that often present a reasonable degree of regenerated tissue, even in case of early exposure of the membrane.

FIG. 6

FIG. 7a

FIG. 7b

â&#x20AC;˘ Class II This class regards exposures larger than 3 mm without the presence of purulent exudate (Fig. 8) Treatment in this case requires the immediate FIG. 7c

FIG. 7d

FIG. 7e

FIG. 7f

15

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Briguglio F. and Simion M. removal of the membrane with a consequent failure of the regenerative procedure (Fig. 9, 10).

However, sometimes, in cases where exposure has occurred after 8-10 weeks following surgery and has not affected the grafted material, it is possible to remove the membrane, close the fenestrated area, and wait for a 4-5 months healing before re-opening it. During this time there must be an antibiotic coverage with amoxicillin and clavulanic acid. It is still possible at the re-entry, to make up the deficit with a second regeneration certainly smaller than the first.

â&#x20AC;˘ Class III When the exposure of the membrane is associated with purulent exudate it is defined as exposure of Class III (Fig. 11). The treatment of this complication requires immediate membrane removal to limit the infiltration of bacteria in the graft. In addition, once the graft is exposed, it is advisable to carefully curette the particles already infected and remove any inflamed tissue present (Fig. 12 a-d). Early intervention would help to limit the infection to the graft surface, thus allowing a progression of the regenerative process in the deeper layers (14). In

FIG. 8

FIG. 9

FIG. 11

FIG. 11a

FIG. 11b

FIG. 11c

FIG. 11d

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16

FIG. 10

Monograph addition, an antibiotic therapy with amoxicillin (875 mg) and clavulanic acid (125 mg) is prescribed twice a day for 5 days. â&#x20AC;˘ Class IV The final category of complications related to the use of non resorbable membranes is represented by the formation of a submucosal abscess without exposure of the membrane (Fig. 13); this event originates from the contamination of the materials used during the surgical procedure. Therefore, special attention must be paid during surgery to the removal of any residual bacteria or tissue inflammation at the surgical site (curettage and bone surfaces of adjacent teeth), and it would seem appropriate to avoid contact with the membrane and grafting material, along with the tongue, saliva and all potentially contaminated surfaces.

It is still a good habit, during the manipulation of materials, to regularly change the sterile gloves, because these may have come into contact with liquids or surfaces with bacteria in the first surgical phase.

Once the infection has occurred, the surgical site will appear swollen, inflamed, and become filled with purulent material which can sometimes burrow through the mucosa. Pain is reported by the patient as well as a a feeling of tightness at the level of the soft tissues.

Although the incidence of this complication is less frequent than the exposure of the membrane, the surgeon must carefully consider, especially during the third and fourth weeks post-surgery, the condition of the soft tissue overlying the graft in order to promptly intervene in case of suspected infection.

Treatment involves the immediate removal of the membrane and the infected tissue, combined with washing the area with rifamycin (90 mg Rifocin, Sanofi Aventis) or tetracycline (250 mg Ambramicina, Scharper). Finally, the patient should be given antibiotic treatment with amoxicillin (875 mg) and clavulanic acid (125 mg) for at least 5 days (Fig. 14 a-d).

FIG. 13

FIG. 14a

FIG. 14b

Mobilization of the graft Beside the exposure of the membrane, a much rarer complication in the performance of regenerative techniques with non resorbable membranes, is the mobilization of the instruments for securing and supporting these membranes during the healing phase.

During surgery, it is essential that the proper screw is chosen to fix the membrane to prevent it from moving during the following 6-8 months of healing.

At the mandibular level, due to a usually denser bone quality, it is often possible to use inserting screws with a hammer. In the upper jaw, more porous bone requires longer screws to be inserted into the bone structure.

The supporting rods of the membrane, which help to prevent a decline in case of large regeneration, must be a certain length to ensure stability during the healing process even under the pressure of soft tissues.

It would be a good idea, then, once having included both types of screw, to check their stability using pressure as mentioned above and check if they are

FIG. 14c

FIG. 14d

17

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Briguglio F. and Simion M. subject to injury, due toan inappropriate provisional prosthesis.

It is possible that during the healing process, the tools used to fix the membrane and consequently the graft, move. In this case the micromovements do not allow the vascular supply and lead to the failure of the procedure. Should this complication arise, treatment requires the removal of the membrane and the graft material, disinfection of the surgical site and repeated operation.

6. Boyne PJ. Osseous repair of the postextraction alveolus in man.

Oral Surg Oral Med Oral Pathol 1966 Jun;21(6):805-13

Conclusion

10. Simion M, Baldoni M, Rossi P, Zaffe D. A comparative study of the effectiveness of e-PTFE membranes with and without early exposure during the healing period. Int J Periodontics Restorative Dent 1994 Apr;14(2):166-80.

In the light of what is reported above, and according to the current literature, there is no doubt that those techniques that involve the use of non-resorbable membranes compared to resorbable membranes can be considered less predictable.

Nonetheless, in cases such as vertical peak increase, non-resorbable membranes remain the gold standard of these procedures which any way are strongly influenced by the ability of the surgeon.

So what is crucial in order to reduce the incidence of such complications, is a deep knowledge of technique and a perfect execution of the various operational steps, having previously properly selected and planned the intervention of the case.

The surgeon should also be able to promptly identify and take appropriate measures when these complications occur, in an effort to minimize the consequences and prevent a complete failure of the regenerative procedure.

Thanks to tissue engineering, the research is focusing on the possibility of simplifying the surgical technique by increasing the regenerative potential of the grafted material and reducing the use of synthetic materials which are most frequently associated with complications.

11. Simion M, Trisi P, Maglione M, Piattelli A. A preliminary report on a method for studying the permeability of expanded polytetrafluoroethylene membrane to bacteria in vitro: a scanning electron microscopic and histological study. J Periodontol 1994 Aug;65(8):755-61.

References 1. Esposito M, Grusovin MG, Coulthard P, Worthington HV. The efficacy of various bone augmentation procedures for dental implants: a Cochrane systematic review of randomized controlled clinical trials. Int J Oral Maxillofac Implants 2006 Sep-Oct;21(5):696-710.

2. Rocchietta I, Fontana F, Simion M. Clinical outcomes of vertical bone augmentation to enable dental implant placement: a systematic review. J Clin Periodontol 2008 Sep;35(8 Suppl):203-15.

3.

Kennedy E. Partial denture construction, Brooklyn, NY, 1928; Dental Items of Interest.

4. Misch CE, Judy KW. Classification of partially edentulous arches for implant dentistry. Int J Oral Implantol 1987;4(2):7-13.

5. Cochran DL, Schou S, Heitz-Mayfield LJ, Bornstein MM, Salvi GE, Martin WC. Consensus statements and recommended clinical procedures regarding risk factors in implant therapy.

Int J Oral Maxillofac Implants 2009;24 Suppl:86-9

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18

7. Triaca A, Minoretti R, Merli M, Merz B. Periosteoplasty for soft tissue closure and augmentation in preprosthetic surgery: a surgical report. Int J Oral Maxillofac Implants 2001 NovDec;16(6):851-6.

8. Tinti C, Parma-Benfenati S. Coronally positioned palatal sliding flap. Int J Periodontics Restorative Dent 1995 Jun;15(3):298-310.

9. Bornstein MM, Bosshardt D, Buser D. Effect of two different bioabsorbable collagen membranes on guided bone regeneration: a comparative histomorphometric study in the dog mandible. J Periodontol 2007 Oct;78(10):1943-53.

12. Verardi S, Simion M. Management of the exposure of e-PTFE membranes in guided bone regeneration. Pract Proced Aesthet Dent 2007 Mar;19(2):111-7.

13. Simion M, Trisi P, Maglione M, Piattelli A. Bacterial penetration in vitro through GTAM membrane with and without topical chlorhexidine application. A light and scanning electron microscopic study. J Clin Periodontol 1995 Apr;22(4):321-31.

14. Rossa ML, Lima LA, Pustiglioni FE, Hespanhol AM, Kon S, Grigolli Filho J, Novo NF. SEM analyses of bacterial contamination of e-PTFE membranes and GTR clinical results. J Int Acad Periodontol 2006 Oct;8(4):115-24.

Case report

Simultaneous sinus and horizontal augmentation utilizing a resorbable membrane and particulated bone graft: a technical note and 7-year follow-up of a case Istvan A. Urban Loma Linda University, Loma Linda, California (USA) Private Practice in Periodontics and Implant Dentistry, Budapest (Hungary)

Aim:

This clinical case report describes and demonstrates successful use of autogenous particulated bone and a resorbable barrier membrane to reconstruct a severe alveolar bone defect.

Key words: bone defects, sinus augmentation, horizontal augmentation.

Case report: A combined sinus graft and horizontal alveolar ridge augmentation was successfully performed. Detailed clinical steps were described. In addition the patient was followed-up for 7 years and the regenerated bone has demonstrated stability throughout this period.

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Urban I.

Introduction Augmentation utilizing guided bone regeneration (GBR) has become a major treatment option to provide optimal bone support for osseointegrated dental implants.

Simple defects were initially treated with GBR, including dehiscence and fenestration defects (1-9).

In addition, GBR has been utilized for horizontal and vertical ridge augmentations (4-13) and has demonstrated reproducible outcomes with high implant survival rates and low complication rates (14).

The so called “knife-edge” ridges, or Cawood and Howell Class IV edentulous jaw (15), present a unique problem for horizontal augmentation. The necessary height of the ridge is adequate on the lingual/palatal side, but the width is insufficient making implant placement often impossible without prior treatment (16). However, there is a good prognosis for this treatment as the residual ridge can be used to stabilize the bone graft, making it less subject to movement, one of the factors that may lead to a failure. To avoid movement of the bone graft, autogenous bone blocks are often screwed onto the ridge to ensure stability and subsequent new bone formation (17-20). Bone blocks (also referred to as “onlay bone graft”) can be fixated onto the residual ridge, providing a limited number of additional bone forming cells into the augmentation site.

However, block bone grafts are associated with varying morbidity depending on the harvest site (2123) and early resorption that could compromise clinical outcome (17, 24). Thus, for partially edentulous patients it has been suggested the utilization of GBR as an alternative grafting procedure for patients presenting with advanced ridge atrophies (25). Recent reports in the literature indicate that the standard treatment of knife-edge ridges has changed in recent years (26, 27).

The use of bone grafting materials and resorbable membranes to treat knife-edge defects with horizontal augmentation may lead to less morbidity in the treatment of patients with these defects. The posterior maxilla presents a unique problem since patients frequently

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presents with defects with both severe horizontal crestal bone atrophy and enlarged maxillary sinus. This type of defect requires a combined procedure of horizontal GBR and a simultaneous maxillary sinus graft.

This clinical case report describes and demonstrates the successful use of autogenous particulated bone, anorganic bone mineral and barrier membranes to reconstruct severe alveolar bone defects.

Case presentation A healthy, 50 year old male patient presented for an evaluation of his posterior right maxilla, which had a history of dentoalveolar infections and tooth loss at the premolar region.

Several years postextraction, the patient wanted implant therapy. As expected, a severe horizontal ridge defect was noted in close proximity to the floor of the sinus and significantly compromised the site with regards to an implant reconstruction. Since the patient desired a fixed reconstruction, the clinical plan was

to regenerate the alveolar defect in order to ideally reconstruct form and esthetics and subsequently place implants to support a fixed prosthetic restoration.

Surgical procedure The patient was premedicated with amoxicillin 2 g one hour before surgery and then 500 mg penicillin was administered three times a day for one week following the surgery.

The patient rinsed with 0.12% chlorhexidine solution (e.g. Peridex) for one minute, then the skin surrounding the surgical site was disinfected and a sterile surgical drape was applied to minimize the potential contamination from extraoral sources.

A full thickness, mid-crestal incision was made in the keratinized gingiva on the alveolar crest. For adequate surgical access, a divergent vertical incision was made at the mesial line angle of tooth #13 and an oblique vertical incision was made on the area of the tuberosity of the maxilla.

After the primary incisions, periosteal elevators were used to FIG. 1

Occlusal view of posterior maxillary area showing thin bone crest.

FIG. 2

Buccal view of the defect area with the elevated maxillary sinus.

20

Case report reflect a full thickness flap beyond the mucogingival junction and at least 5 mm beyond the bone defect.

A rectangular shaped antrostomy with rounded corners was created with a round diamond bur at the lateral wall of the maxillary sinus.

The sinus window was then infractured and the sinus membrane was carefully reflected with sinus curettes and elevated with care to prevent perforations. The recipient bony bed was prepared with multiple decortical holes to expose the medullary space using a small round bur. Autogenous bone was then harvested from the right ascending ramus and particulated in a bone mill. (R. Quétin Bone-Mill, Roswitha Quétin Dental Products, Leimen, Germany). An appropriate size, synthetic barrier membrane composed of a microporous structure of synthetic bioabsorbable glycolide and trimethylene carbonate copolymer fiber (Gore Resolut® Adapt® LT Regenerative Membrane, W.L. Gore & Associates, Inc., Flagstaff, AZ) was selected and trimmed considering graft volume.

The membrane was fixated first on the palatal side using multiple titanium pins. A sagittal sandwich layer bone graft was created with anorganic bovine-derived bone mineral (ABBM) (Bio-Oss®, Geistlich Pharma AG, Wolhusen, Switzerland) (BO) and the harvested, particulated autogenous bone. BO was applied and packed to the

medial wall of the sinus. The autogenous bone was then applied and packed exactly superior to the planned implant sites on the ridge.

Then, the autogenous bone layer was covered laterally with a final layer of BO. This sandwich technique has been previously described in a prospective study (28). The final layer of bone graft was then placed within the subantral space and

autogenous bone was placed appositionally on the horizontal alveolar defect. Once the membrane was completely secured with additional titanium pins, the flap was mobilized to permit tension free, primary closure. A periosteal releasing incision connecting the two vertical incisions was performed to achieve elasticity of the flap.

The flap was than sutured in two

FIG. 3

The recipient bone bed is prepared with multiple decorticalization holes. BO was applied and packed to the medial wall of the sinus.

FIG. 4

Autogenous bone was then applied and packed exactly superior to the planned implant sites on the ridge.

FIG. 5

After palatal membrane fixation, autogenous particulated bone was placed on the external portion of the ridge.

FIG. 6

Occlusal and buccal views of the fixated membrane.

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Urban I. FIG. 7

Occlusal and buccal views of the fixated membrane.

FIG. 8

After 6 months of uneventful healing, occlusal view of the augmented bone crest. Two implants are in position.

FIG. 9

After 6 months of uneventful healing, occlusal view of the augmented bone crest. Two implants are in position.

FIG. 10

Final prosthetic reconstruction.

layers: first horizontal mattress sutures (Gore-Tex® CV-5 Suture, W.L. Gore & Associates, Inc.,

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Flagstaff, AZ) were placed 4 mm from the incision line; then, single interrupted sutures with the same e-

22

PTFE suture were placed to close the edges of the flap, leaving at least a 4 mm thick connective tissue layer between the membrane and the oral epithelium. This intimate connective tissue-toconnective tissue contact provides a barrier preventing exposure of the membrane. Vertical incisions were closed with single interrupting sutures.

The single interrupted sutures were removed between 10 to 14 days post surgery, and mattress sutures were removed after two to three weeks. Medications were followed as described above. In addition an anti-inflammatory medication, 50 mg diclofenac (Voltaren XR, Novartis Pharmaceuticals) was prescribed three times a day for one week following the surgery.

Chemical plaque control using 0.12% chlorhexidine solution was used daily from 24 hours postsurgery until the time of suture removal. Postoperative swelling was remarkable with its maximum at 48 hours postoperatively. Swelling gradually subsided but was still visible at one week and disappeared completely after ten days.

Postoperative discomfort was mostly associated with tension from the swelling. Pain was negligible however. No other symptoms occurred in the postsurgical period.

To avoid postsurgical trauma, a removable appliance was not utilized. After a previously described, 6 months of uneventful healing, the area was explored employing the same full thickness flap design (27).

Upon reopening of the surgical site the tissue beneath appeared healthy, with a healthy periosteal layer between the soft tissue and the bone, and no remains of the membrane was observed. A complete, 6 mm horizontal augmentation was observed. Two, standard diameter, Branemark TiUnite™implants were placed (Nobel Biocare, Yorba Linda, CA) following the manufacturer’s protocol.

The implants were submerged in a two stage technique for 6 months, and then uncovered and restored with single implant supported porcelain fused to metal crowns.

The patient was entered into a scheduled maintenance program that included a clinical examination

Case report FIG. 11

Peri-apical radiograph after 7 years of function.

every six months and annual radiographic examination.

Periapical radiographs were taken at the abutment connection and then every 12 months thereafter with a long cone parallelling technique.

Peri-implant mucosal conditions were assessed for redness, hyperplasia, suppuration, swelling, and presence of plaque.

The implants remained in function, and the patient did not report any complaints for foreign body sensation, pain or dyesthesia.

Intraoral examinations revealed healthy peri-implant mucosa without suppuration, swelling or redness at any implant site. Upon radiological examination the first bone-implant contact was located near the first implant thread.

Discussion The case presented herein demonstrates a detailed protocol and long-term follow-up for a patient treated with simultaneous sinus and horizontal ridge augmentation utilizing GBR. Autogenous bone and ABBM was used for sinus augmentation and particulated autogenous bone alone and a resorbable membrane was used for horizontal augmentation simultaneously and implants were placed at a second surgery after 6months of uneventful healing. Even though the healing time between grafting and implant placement can be regarded as a compromise between the time to form sufficient amount of new bone and the need

of a timely prosthetic solution for a patient, the benefit of this twostaged procedure is that it provides the amount of horizontal ridge width and vertical height necessary to successfully place an implant.

The grafting technique utilized to augment the sinus floor in this case report has been evaluated successfully in a recent prospective study reporting on 100 sinus grafts for up to 5-years of implant loading (28). The study concluded that clinical success and survival of implants placed after sinus augmentation appear similar to success and survival of implants placed in native bone. Another recent prospective case series of 25 cases reported on implants loaded successfully between 2 to 5 years and demonstrated that the horizontal augmentation technique described herein can be safely and effectively used for lateral augmentation of knife-edge ridges (27). Sixteen (16) of the 25 cases received a combination treatment of horizontal augmentation and a sinus graft. However, the publication did not provide a detailed clinical protocol that described these combination procedures.

The case reported herein has been followed for 8 years, and is the first patient treated with this technique within the previously reported prospective case series. The clinical and radiological examinations demonstrated that both implants are successful according to the established success criteria (28, 29).

This finding is also in agreement with reports on enhanced surface implants placed into augmented

23

ridges by simultaneous vertical and sinus bone grafting (30, 31). In another publication, significantly lower implant success rates were reported on simultaneous sinus and vertical augmentation utilizing machined surface implants (32).

GBR is a well-documented option in bone augmentation procedures (1), but there is limited information in the literature on combined procedures such as simultaneous sinus and horizontal augmentation.

Multicenter, randomized clinical trials are necessary to investigate and compare the procedure described herein with other potential clinical solutions, and these trials could also evaluate complication rates of bone graft healing, donor site morbidity as well as the longterm success of the loaded implants.

These trials could determine which clinical procedure is the most appropriate to treat this type of defect in the posterior maxilla.

Conclusion This limited report demonstrates long-term follow-up of a case after remarkable horizontal bone regeneration in conjunction with autogenous bone and a resorbable barrier membrane. Multicenter, randomized clinical trials are necessary to further investigate and compare this procedure with other potential clinical solutions.

References 1. Aghaloo TL, Moy PK. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant pPlacement. Int J Oral Maxillofac Implants 2007;22:49-70.

2. Esposito M, Grusovin MG, Coulthard P, Worthington HV. The efficacy of various bone augmentation procedures for dental implants: a Cochrane systematic review of randomized controlled clinical trials. Int J Oral Maxillofac Implants 2006;21:696-710.

3. H채mmerle CH, Jung RE, Feloutzis A. A systematic review of the survival of implants in bone sites augmented with barrier membranes (guided bone regeneration) in partially edentulous patients. J Clin Periodontol 2002;29 Suppl 3:226-231; discussion 232223.

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Urban I. 4. Dahlin C, Andersson L, Linde A. Bone augmentation at fenestrated implants by an osteopromotive membrane technique. A controlled clinical study.

Clin Oral Impl Res 1991;2:159-165.

5. H채mmerle CH, Chiantella GC, Karring T, Lang NP. The effect of a deproteinized bovine bone mineral on bone regeneration around titanium dental implants. Clin Oral Impl Res 1998;9:151-162.

6. Jovanovic SA, Spiekermann H, Richter EJ. Bone regeneration around titanium dental implants in dehisced defect sites: a clinical study. Int J Oral Maxillofac Implants 1992;7:233-245.

7. Lorenzoni M, Pertl C, Keil C, Wegscheider WA. Treatment of periimplant defects with guided bone regeneration: a comparative clinical study with various membranes and bone grafts. Int J Oral Maxillofac Implants 1998;13:639-646.

8. Zitzmann NU, Sch채rer P, Marinello CP. Long-term results of implants treated with guided bone regeneration: a 5year prospective study. Int J Oral Maxillofac Implants 2001;16:355366.

9. Moses O, Pitaru S, Artzi Z, Nemcovsky CE. Healing of dehiscence-type defects in implants placed together with different barrier membranes: a comparative clinical study. Clin Oral Impl Res2005;16:210-219.

10. Simion M, Jovanovic SA, Tinti C, Benfenati SP. Long-term evaluation of osseointegrated implants inserted at the time or after vertical ridge augmentation. A retrospective study on 123 implants with 1-5 year follow-up.

Clin Oral Impl Res 2001;12:35-45.

11. Buser D, Ingimarsson S, Dula K, Lussi A, Hirt HP, Belser UC. Long-term stabilit of osseointegrated implants in augmented bone: A 5-year prospective study in partially edentulous patients.

Int J Periodontics Restorative Dent 2002; 22:109-117.

12. Urban IA, Jovanovic S, Lozada JL. Vertical Ridge Augmentation Using Guided Bone Regeneration (GBR) in Three Clinical Scenarios Prior to Implant Placement: A Retrospective Study of 35 Patients 12 to 72 Months After Loading. Int J Oral Maxillofac Implants 2009;24:502-510.

13. Urban IA, Caplanis N, Lozada JL. Simultaneous Vertical Guided Bone Regeneration (GBR)and Guided Tissue Regeneration (GTR) in the posterior maxilla using recombinant human platelet-derived growth factor (rhPDGF). A case report.

J Oral Implantol. 2009;35:251-256.

14. Esposito M, Grusovin M, Worthington H, Coulthard P. Interventions for replacing missing teeth: bone augmentation techniques for dental implant treatment. The Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD003607.pub2.

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DOI:10.1002/14651858 CD003607.pub2.

15. Cawood JI, Howell RA. A classification of the edentulous jaws. Int J Oral Maxillofac Implants 1988;17:232236.

16. Proussaefs P, Lozada J. The use of resorbable collagen membrane in conjunction with autogenous bone graft and inorganic bovine mineral for buccal/labial alveolar ridge augmentation: a pilot study. J Prosthetic Dent 2003;90:530-538.

17. von Arx T, Buser D. Horizontal ridge augmentation using autogenous block grafts and the guided bone regeneration technique with collagen membranes: a clinical study with 42 patients. Clin Oral Impl Res 2006;17:359-366.

18. Cordaro L, Amade DS, Cordaro M. Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement.

Clin Oral Impl Res 2002;13:103-111.

19. 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;9:13-29.

20. Buser D, Dula K, Hirt HP, Schenk RK. Lateral ridge augmentation using autografts and barrier membranes: a clinical study with 40 partially edentulous patients. J Oral Maxillofac Surg 1996;54:420-432; discussion 432-423.

21. Nkenke E, Schultze-Mosgau S, Radespiel-Troger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Impl Res2001;12:495-502.

22. Nkenke E, Weisbach V, Winckler E, Kessler P, Schultze-Mosgau S, Wiltfang J, et al. Morbidity of harvesting of bone grafts from the iliac crest for preprosthetic augmentation procedures: a prospective study. Int J Oral Maxillofac Implants 2004;33:157-163.

23. Raghoebar GM, Louwerse C, Kalk WW, Vissink A. Morbidity of chin bone harvesting.

Clin Oral Impl Res2001;12:503-507.

24. Maiorana C, Beretta M, Salina S, Santoro F. Reduction of autogenous bone graft resorption by means of biooss coverage: a prospective study. Int J Periodontics Restorative Dent 2005;25:19-25.

25. Chiapasco M, Zaniboni M, Boisco M. Augmentation procedures for the rehabilitation of deficient edentulous ridges with oral implants. Clin Oral Impl Res 2006; 17:136-159.

26. H채mmerle CHF, Jung RE, Yaman D, Lang NP. Ridge augmentation by applying bioresorbable membranes and deproteinized bovine bone

24

mineral: a report of twelve consecutive cases. Clin Oral Impl Res2008;19:1925.

27. Urban IA, Nagursky H, Lozada JL. Horizontal ridge augmentation with a resorbable membrane and particulated autogenous bone with or without anorganic bovine bone-derived mineral: A prospective case series in 22 patients. Int J Oral Maxillofac Implants 2011;26:404-414.

28. Urban IA, Lozada JL. A prospective study of two-staged sinus augmentation in minimal and moderate residual crestal bone: Results after 1 to 5 Years. Int J Oral Maxillofac Implants 2010;25:12031212.

29. Albrektsson T, Zarb G, Worthington P, Eriksson B. The long-term efficacy of currently used dental implants: A review and proposed criteria of success.

Int J Oral Maxillofac Implants 1986;1:11-25.

30. Urban IA, Jovanovic S, Lozada JL. Vertical ridge augmentation using guided bone regeneration (GBR) in three clinical scenarios prior to implant placement: A retrospective study of 35 patients 12 to 72 months after loading. Int J Oral Maxillofac Implants 2009;24:502-510.

31. Urban IA, Caplanis N, Lozada JL. Simultaneous vertical guided bone regeneration (GBR) and guided tissue regeneration (GTR) in the posterior maxilla using recombinant human platelet-derived growth factor (rhPDGF): A case report. J Oral Implantol. 2009;35:251-256.

32. Simion M, Fontana F, Rasperini G, Maiorana C. Long-term evaluation of osseointegrated implants placed in sites augmented with sinus floor elevation associated with vertical ridge augmentation: A retrospective study of 38 consecutive implants with 1 to 7-year follow-up. Int J Periodontics Restorative Dent. 2004;24:208-221.

Case report

The removal of a deeply impacted lower third molar by means of the bone lid technique with piezoelectric instruments Matteo Chiapasco Andrea Flora Laura Serioli Marco Zaniboni

Oral Surgery Unit (Head: Prof. Matteo Chiapasco) Dental Clinic - Department of Medicine, Surgery, and Dentistry A.O. San Paolo, University of Milan Milan, Italy

Background: The removal of impacted lower third molars is one of the most frequent procedures in oral surgery. In case of deep impaction and close relationship between the impacted tooth and the inferior alveolar nerve, the risk of neural damage may be relevant, in particular when a standard approach for tooth removal is used due to the limited visibility and narrowness of surgical field.

Case report: In this case report the authors present the surgical treatment of a deeply impacted lower third molar in continuity with the inferior alveolar nerve by means of a lateral approach consisting of the so called â&#x20AC;&#x153;bone lidâ&#x20AC;? technique. This approach allows direct control of the surgical field with reduction of damage to the inferior alveolar nerve as compared to the standard approach.

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25

Key words: impacted third molars, surgical procedure, piezosurgery, inferior alveolar nerve, complications.

Chiapasco M. et al.

Introduction The removal of impacted lower third molars is a very common surgical procedure, due to the high prevalence of impaction of these teeth (20% in developed countries) (1), and due to the relevant incidence of diseases related to lower third molar impaction such as pericoronitis, endosseous cysts, periodontal damages and/or decay of adjancent teeth, neurologic symptoms (such as neuralgia and/or pain) and, finally, the occurence of odontogenic tumours, such as the ameloblastoma (1, 2, 4, 6, 7, 9).

The complexity of the surgical procedure depends on the position and depth of the impacted molar, in particular when the tooth is in direct contact with the inferior alveolar nerve (3). For this reason, whenever intraoral or panoramic radiographs show an apparent relationship between the impacted tooth and the nerve, it is mandatory to perform a computed tomography of the mandible in order to precisely evaluate the position and morphology of the tooth and the course of the nerve (8, 10, 15).

Notwithstanding the data given by CT scans, the surgical removal of deeply impacted lower third molars may prove difficult to be performed if a standard approach is used. This latter generally consists of the elevation of a full-thickness flap in the retromolar area, an ostectomy to expose the crown of the impacted tooth, the odontotomy (whenever indicated) and, finally, the removal of the tooth (1, 3). In case of deeply impacted third molars, these manoeuvres may be very complex due to the limited access to the surgical field, the few angles allowed for the management of surgical instruments, and the poor visibility.

Due to the aforementioned aspects, this approach may require a relevant share of bone removal which may cause periodontal damages to the second molar and may leave a residual bone defect that exposes to the risk of incomplete bone regeneration (8).

The limited visibility, in particular, may cause a lengthening of the operating time and a higher risk of damaging the inferior alveolar

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nerve, with increased postoperative morbidity in terms of pain, swelling and neural disturbances (1, 8).

Therefore, in case of deeply impacted lower third molars, a different surgical approach which can provide better access and visibility of the area on intervention and limit the need for extended ostectomy, is advisable (11).

In 1993, Alling and Alling documented a surgical approach based on the removal of a â&#x20AC;&#x153;bone lidâ&#x20AC;? to expose the impacted tooth from the buccal side (11; 13). The proposed technique was similar to the one used to perform the harvesting of bone blocks from the mandibular ramus: four osteotomic paths are designed to isolate the bone block, which is then detached with the aid of surgical chisels.

The aim of this work is to present a case report using a similar procedure with the aid of piezoelectric intrumentation.

Case report FB, a female patient aged 47 presented with chronic pain and suppuration from a deep periodontal pocket distal to 47. The panoramic radiograph and CT scans (Fig. 1, 2) showed a deeply impacted right mandibular third molar with the apex of the roots very close to the lower border of the mandibular angle, and a tight contiguity with the inferior alveolar nerve located on the buccal side of the tooth.

Obvious difficulties were immediately identified due to the depth of impaction, the need for odontotomy, the proximity of the alveolar nerve, and the very limited surgical access in the case a standard approach had been chosen.

For these reasons, the bone lid technique was adopted.

The patient was operated under general anesthesia with naso-

FIG. 1

The preoperative panoramic radiograph shows a deeply impacted lower third molar which must be removed because of chronic infection with a fistula from the molar crown toward the alveolar crest.

FIG. 2

The CT scan shows a close relationship between the impacted molar and the alveolar nerve which runs in direct contact with the third molar root on the buccal side of the mandible very close to the outer cortex. The scan also confirms the presence of bone loss connecting the third molar crown and the alveolar ridge, through which pus drains.

26

Case report

FIG. 5

The three fragments of the impacted tooth.

FIG. 3

FIG. 4

After flap elevation a bone lid created with piezoelectric instruments is detached with surgical chisel in order to obtain access to the impacted molar.

After the removal of the bone lid the alveolar nerve has been isolated and protected during odontotomy of the lower third molar necessary for a safe removal of the impacted tooth.

tracheal intubation. Antibiotic prophylaxis (amoxicilline + clavulanate, 2 g) was administered via endovenous injection during anesthesia induction.

Piezoelectric instrumentation (Mectron Piezosurgery速) was used for the preparation of the bone lid and for inferior alveolar nerve isolation, while traditional rotary instruments (low-speed straight handpiece and fissure bur) were used for odontotomy.

of adequate dimensions in the area of impaction. As the course of the inferior alveolar nerve was markedly buccal, special care was taken, despite the use of piezoelectric instruments, to avoid any possible trauma to the nerve. The bone lid was then removed by dislocation with the aid of surgical chisels (Fig. 3).

After the removal of the bone lid, the nerve was isolated and protected, and the crown and root furcation of the tooth were exposed by ostectomy (Fig. 4). To avoid root fractures and

lesions to the nerve, the impacted tooth was sectioned in three parts and all fragments (Fig. 5) were removed with surgical elevators.

The detached bone lid was not repositioned, due to the risk of compression determined by the markedly buccal course of the inferior alveolar nerve, and to the concomitant presence of a wide cavity following both the tooth removal and the bone erosion determined by chronic infection that would have made the fixation of the bone lid difficult and its vascularization inadequate.

After careful inspection of the residual cavity (Fig. 6) and irrigation of the surgical field with sterile saline, the surgical flap was sutured (Fig. 7), and compression with a sterile gauze was applied for a few minutes.

To reduce post-operative swelling,

FIG. 6

FIG. 7

The surgical field at the end of the procedure showing preservation of the alveolar nerve.

The surgical field after the suture of the flap.

Surgical procedure The surgical intervention began with the elevation of a triangular mucoperiosteal flap similar to the one used in the conventional crestal approach, but incisions were extended further towards the coronoid process (the distal one) and towards the vestibular sulcus (the mesial one) to design a wider flap, according to clinical needs.

The buccal aspect of the flap was then retracted with the aid of a malleable spatula, to improve the access and visibility of the surgical field, and the protection of the soft tissues and important anatomical structures such as the facial artery.

By means of piezoelectric instruments, four osteotomic paths were designed to isolate a bone block

27

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Chiapasco M. et al. dexamethasone (8 mg) was administered perioperatively via intravenous injection.

Antibiotic therapy with amoxicillin and clavulanate (1 g) was prescribed (1 tablet every 12 hours for 6 days), in association with non-steroidal anti-inflammatory drugs. The patient followed a liquid and cold diet for 24 hours after the end of the surgical intervention and a soft diet until suture removal (7 days afterwards). Chlorhexidine mouthwashes (1 rinse 3 times a day) were associated to the usual oral hygiene manoeuvres for 10 days.

Post-operative recovery was uneventful. Transient paresthesia disappeared spontaneously two weeks after surgery.

Discussion and conclusion

FIG. 8

Postoperative panoramic radiograph.

access (11). Therefore, a significant reduction of intraoperative neural damages can be obtained.

Osteotomies for bone lid isolation can be performed with traditional rotary instruments, or with piezoelectric intrumentation. The first method is widely used and very well documented, and allows for a fast and effective osteotomic path design. However, it must be considered that the creation of the osteotomies with fissure burs determines higher bone loss, and can expose to higher risks in cases where the course of the nerve is markedly buccal. Piezoelectric instruments have been recently introduced, and use microvibration of the surgical inserts at ultrasonic (27 to 29 kHz) frequencies to perform cutting of the hard tissues (11, 16, 17). These instruments demonstrated good cutting properties on cortical bone, allowing at the same time the preservation of soft tissues from damage in case of accidental contact (16, 17, 18).

This aspect has important implications when anatomical structures such as vessels and nerves are contained in bone tissue, as it occurs for the inferior alveolar nerve.

The removal of deeply impacted mandibular third molars with a buccal approach by means of a bone lid creation demonstrated to be a safe and reliable technique, that can significantly simplify the surgical intervention and reduce the risk of neural damages (Fig. 8).

Surgical removal of impacted mandibular third molars is one of the most frequent oral surgery interventions (1, 5). Though precise tridimensional radiographic imaging, such as CT, allow a precise preoperative assessment of the clinical situations, in the case of deep impaction and proximity of the impacted tooth with the inferior alveolar nerve, the risk of nerve damage is not negligible (10, 12), as demonstrated by several studies reporting neural complications rates ranging from 0.4% to 25% (11, 14, 15).

Studies published in the literature present large patients’ populations, but all of them report data for patients treated with the “classical”, crestal approach (14). This access may, in the majority of cases, permit the removal of the impacted tooth, but in case of deep impaction it may render the surgical manoeuvres more difficult due to the reduced visibility, and can therefore expose to a higher risk of inferior alveolar nerve damage. The approach proposed in this study, although more invasive and, for this reason, limited to the most complex cases, allows a superior control of the surgical field, permits to identify and protect the inferior alveolar 1. Chiapasco M, De Cicco L, Marrone G. nerve, and allows to perform Side effects and complications associated with third molar surgery. odontotomy with a more comfortable

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