Marco Zaniboni

Clinical outcomes of GBR procedures to correct peri-implant dehiscences and fenestrations: a systematic review

OBJECTIVE To analyze the clinical outcomes of endosseous implants following guided bone regeneration (GBR) procedures to correct dehiscence/fenestration defects associated with implant placement. METHODS/SEARCH STRATEGY: A Medline search was performed for human studies published in English focusing on GBR procedures for the correction of dehiscence/fenestration defects associated with the placement of screw-shaped titanium implants. The selected studies had to include at least 10 consecutively treated patients with a minimum follow-up of 12 months after the start of prosthetic loading. The clinical outcomes in terms of the complication rate of the GBR procedure, implant survival, and stability of marginal soft tissues around implants were evaluated. RESULTS Seven publications were included in this review. A total of 238 patients received 374 implants. Defects were treated with resorbable or non-resorbable membranes, in association with or without graft materials. Patients were followed for 1-10 years after the start of prosthetic loading. In the postoperative period, 20% of the non-resorbable membranes and 5% of the resorbable ones underwent exposure/infection. However, in the majority of cases, a complete or an almost complete coverage of the initial defect was obtained. The overall survival rate of implants, irrespective of the type of membrane and grafting materials, was 95.7% (range: 84.7-100%). No significant modifications of probing depth and/or variation of clinical attachment level around implants were observed during the follow-up period. CONCLUSION Despite the favorable results obtained, it was difficult to draw a significant conclusion as far as the more reliable grafting material and membrane barrier for the correction of dehiscence/fenestration defects are concerned, due to the limited sample of patients and the wide variety of grafting materials and membranes, used alone or in combination. Moreover, due to the lack of randomized clinical trials, it was impossible to demonstrate that such augmentation procedures are actually needed to allow the long-term survival of implants.

Dental implants placed in grafted maxillary sinuses: a retrospective analysis of clinical outcome according to the initial clinical situation and a proposal of defect classification

OBJECTIVE OF THE STUDY To present a classification of maxillary defects necessitating sinus floor elevation procedures (SFEPs) with two objectives: (a) to propose a standardization of surgical procedures according to initial type of atrophy and (b) to allow the evaluation of the success/survival rates of implants placed in the grafted areas according to the initial situation. MATERIALS AND METHODS Nine-hundred and fifty-two consecutive SFEP were performed on 692 patients. Initial defects were classified according to a new classification, which considered not only residual bone height below the sinus but also the width of the alveolar crest and horizontal/vertical intermaxillary relationship. Results were evaluated according to the different classes. The sinuses were grafted with autogenous bone taken from intra-oral or extra-oral sites: 579 SFEP were associated with vertical and/or horizontal onlay grafts to correct concomitant alveolar ridge deficits. A total of 2037 implants were inserted into the grafted sinuses either immediately or 4-6 months later. Three to 6 months afterwards, implants were loaded. The mean follow-up was 59 months (range: 12-144 months). RESULTS The success rate of the reconstructive procedures varied between 93.2% and 100%, according to class of atrophy; the overall survival and success rates of implants were 95.8% and 92.5%, respectively, whereas the survival and success rates according to class of atrophy varied between 90% and 97.6%, and between 85.4% and 95.5%, respectively. Lower success rates were found in classes presenting with more severe atrophy. CONCLUSION The results obtained demonstrated that sinus floor elevation, alone or in association with reconstructive procedures with autogenous bone grafts, is a reliable procedure to allow implant placement in atrophic edentulous maxillae, irrespective of the initial clinical situation. However, it must be underlined that the success rates of reconstructive procedures and implants differ according to class of atrophy, showing lower success rates in classes presenting with more severe atrophy.

Failures in Jaw Reconstructive Surgery with Autogenous Onlay Bone Grafts for Pre-implant Purposes: Incidence, Prevention and Management of Complications

Dental rehabilitation with oral implants has become a routine treatment modality in the last decades, with reliable long-term results. However, insufficient bone volume or unfavorable intermaxillary relationships may render implant placement impossible or incorrect from a functional and esthetic viewpoint. Among the different methods for the reconstruction of deficient alveolar ridges, the use of autogenous bone blocks represents the most frequently used treatment modality both for limited and extended bone defects. Prerequisites for a successful outcome are represented by accurate preoperative planning, proper reconstructive procedure, and adequate prosthetic rehabilitation. Even if all these principles are followed, complications involving the grafts may occur, such as dehiscence, infection, or relevant resorption of the graft. The aim of this article is to present an updated overview on the incidence, prevention and treatment of these complications.

Methods to treat the edentulous posterior maxilla: implants with sinus grafting.

Prosthetic rehabilitation of the edentulous posterior maxilla with implant-supported prostheses frequently presents a challenge for the oral surgeon because of the lack of bone due to alveolar ridge resorption or maxillary sinus pneumatization. To overcome these problems, different solutions were proposed over the years, such as the use of short implants or tilted implants (including zygoma implants), with the aim of avoiding maxillary sinus floor elevation. Both of these techniques have advantages and disadvantages that should be evaluated carefully to choose the most appropriate treatment. Zygoma implants or short/tilted implants are not a panacea for the treatment of patients with inadequate posterior maxillary bone stock. Instead, treatment should be based on the characterization of resorption patterns of the posterior maxilla, and may include the need for sinus grafting or other grafting procedures to reestablish not only adequate bone volume for implant placement, but also a favorable intermaxillary relationship, to optimize the functional and esthetic outcome of the final prosthetic rehabilitation. The authors discuss the indications, advantages, and disadvantages of sinus-grafting procedures in association with or without other reconstructive procedures.

Sinonasal complications resulting from dental treatment: outcome-oriented proposal of classification and surgical protocol.

Background Odontogenic sinusitis is a relevant infectious condition of the paranasal sinuses. The widespread use of dental implants and reconstructive procedures for dental implant placement has led to new types of complication. To the authors’ knowledge, no publication has extensively examined sinonasal complications resulting from dental treatment, and no classification system allowing standardization and comparison of results is currently available. This study was designed to (a) analyze the results obtained from surgical treatment of complications resulting from dental procedures combining functional endoscopic sinus surgery (FESS) and an intraoral approach and (b) propose a new classification system and standardized treatment protocols for sinonasal complications resulting from dental procedures. Methods A total of 257 patients consecutively treated with FESS (136 in conjunction with oral surgery) were included in the study. Different clinical situations were integrated into a new classification system based on the pathogenesis and clinical aspects of each case, with the aim of identifying homogenous treatment groups. Results were evaluated for each class. Results Of the 257 patients, 254 were successfully treated with surgery performed according to the proposed protocols. Three of 257 patients required a second surgery, after which they completely recovered. Complications of implant and preimplant surgery (maxillary sinus floor elevation) showed longer recovery times. Conclusion The results obtained are very encouraging. The majority of patients (254/257; 98.8%) were successfully treated with the proposed protocols. These results seem to indicate that the rationalization of surgical treatment protocols according to the initial clinical situation may significantly improve the clinical outcome.

Evaluation of peri-implant bone resorption around Straumann Bone Level implants placed in areas reconstructed with autogenous vertical onlay bone grafts.

AIM OF THE STUDY To evaluate the survival and success rate of Straumann Bone Level implants placed in vertically atrophied edentulous jaws previously reconstructed with autogenous onlay bone grafts taken from the calvarium or the mandibular ramus. MATERIALS AND METHODS From 2007 to 2009, 18 patients presenting with vertical deficits of the edentulous ridges were treated with autogenous cortical bone grafts harvested from the mandibular ramus or the calvarium. Four to seven months afterward, 60 Straumann Bone Level implants were placed in the reconstructed areas. After a further waiting period of 2-3 months, patients were rehabilitated with implant-supported fixed prostheses. Follow-up ranged from 12 to 36 months (mean: 19 months) after the start of prosthetic loading. Graft resorption before implant placement, as well as survival and success rates of implants, were recorded. RESULTS The mean bone resorption prior to implant placement was 0.18 mm for calvarial grafts and 0.42 mm for ramus grafts. Survival rate was 100% either for implants placed in calvarial grafts or implants placed in ramus grafts, while success rate was 90.3% for implants placed in calvarial grafts, and 93.1% for implants placed in ramus grafts. CONCLUSION Results from this study seem to demonstrate that implants with a platform-switching design may predictably integrate in edentulous areas reconstructed with autogenous bone grafts, with survival rates consistent with those reported in recent literature reviews on the same topic, and also with implants placed in native bone. Conversely, this study was not able to demonstrate that implants with platform-switching design may reduce bone resorption around implants placed in reconstructed areas.

Fresh Frozen versus Autogenous Iliac Bone for the Rehabilitation of the Extremely Atrophic Maxilla with Onlay Grafts and Endosseous Implants: Preliminary Results of a Prospective Comparative Study

PURPOSE The purpose of this study was to compare (1) the clinical outcome of the reconstruction of extremely atrophic edentulous maxillae with fresh frozen allogeneic bone (FFB) (group A) and autogenous bone (AB) (group B) iliac blocks; and (2) the peri-implant bone resorption and the survival rate of implants in the two groups. MATERIALS AND METHODS In a 1-year period, eight patients were treated with FFB and seven with AB iliac grafts. Five to seven months afterward, 108 implants were inserted (59 in group A and 49 in group B). Four to five months afterward, patients were rehabilitated with implant-supported prostheses. The mean follow-up was 24 months. RESULTS Prior to implant placement, graft exposure occurred in two patients in group A and in one patient in group B. The mean graft resorption prior to implant placement was 0.78 mm and 0.54 mm in group A and B, respectively. After implant placement, bone graft exposures with partial loss of the graft occurred in six out of eight patients in group A and in none of the group B patients. The survival rate of implants was 90.1% and 100% in group A and B, respectively. The mean values of peri-implant bone resorption at the end of the follow-up period were 1.64 mm and 0.92 mm in group A and B, respectively. CONCLUSION Results of this study seem to demonstrate that FFB does not represent a reliable alternative to AB blocks because of the higher rate of bone exposure and partial loss of the grafts, the lower implant survival, and the higher peri-implant bone resorption in FFB patients.

Implants in Reconstructed Bone: A Comparative Study on the Outcome of Straumann® Tissue Level and Bone Level Implants Placed in Vertically Deficient Alveolar Ridges Treated by Means of Autogenous Onlay Bone Grafts

PURPOSE To evaluate: (1) the survival rate of Straumann® Tissue Level and Bone Level implants placed in atrophic edentulous jaws previously reconstructed by means of autogenous onlay bone grafts; (2) to compare peri-implant bone resorption values over time. MATERIALS AND METHODS From 2005 to 2010, 50 patients presenting with vertical or tridimensional defects of the edentulous ridges were treated with autogenous bone grafts. Three to 7 months afterward, 192 implants were placed (Group A: 97 Tissue Level implants; Group B: 95 Bone Level implants) in the reconstructed areas. After a further waiting period of 2 to 3 months, patients were rehabilitated with implant-supported fixed prostheses. The follow-up ranged from 12 to 68 months after the start of prosthetic loading (mean: 33 months). RESULTS No implants were removed (survival rate: 100%), but in Group B 13 implants (8 placed in iliac grafts, 2 placed in ramus grafts, and 3 placed in calvarial grafts) presented peri-implant bone resorption values higher than those proposed by Albrektsson and colleagues. for successful implants: the overall implant success rate was then 100% for Group A and 86.8% for Group B. No prosthetic failures were recorded, thus leading to a 100% prostheses success rate. CONCLUSION No significant differences were found between the two types of implants as far as implant survival rate is concerned, but results from this study seem to demonstrate that Tissue Level implants may present better long-term results in terms of peri-implant bone maintenance, as compared with Bone Level implants, when placed in reconstructed areas.