Alveolar Bone Architecture: A Systematic Review and Meta‐Analysis

Background: There is a need for studying bone characteristics systematically for a better understanding of planning (i.e., timing of placement and loading) and outcomes of implant therapy. Therefore, the aim of the present review is to evaluate alveolar bone microarchitecture and its modifiers. Methods: Two independent reviewers conducted electronic and manual literature searches in several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register, for articles published up to February 2015 reporting alveolar bone microstructure. The random‐effect model was applied to calculate the weighted mean (WM) of total bone volume (TBV), which has a range from 0 to 1. TBV was stratified by anatomic locations, atrophic status, and types of specimens. Correlations between TBV and other bone‐related parameters were also analyzed. Results: A total of 800 articles were initially identified. After abstract/full‐text review, 24 articles were included in the systematic review, of which 23 were also included in the quantitative analysis. The WM TBV was 0.365 (95% confidence interval = 0.278 to 0.452), higher in the maxillary/mandibular anterior sites than the maxillary/mandibular posterior sites. However, great variations existed within each anatomic location. Additionally, WM TBV was lower in atrophic sites than non‐atrophic sites. TBV was correlated negatively with trabecular spacing (R² = 0.11). Conclusions: The present systematic review suggests that the TBV might not be different between the defined anatomic locations. However, the atrophy status might influence TBV.     

An Alveolar Bone Augmentation Technique to Improve Esthetics in Anterior Ceramic FPDs: A Clinical Report

This clinical report describes guided bone augmentation for treatment of a facial maxillary alveolar bone defect to enhance the esthetic result for an all-ceramic fixed partial denture (FPD). A combination of decalcified freeze dried bone allograft and resorbable human pericardium, in conjunction with cortical channel expansion, was used for the augmentation process to eliminate a secondary surgical procedure. Post-operative examinations showed improvement in the alveolar bone contour. The regeneration of the missing osseous structure was accomplished to support the future esthetic soft tissue contours. This osseous regenerative technique significantly increased the functional and esthetic outcome of the final FPD by restoring the alveolar ridge defect to its original dimension.     

The Need for Lateral Piriform Rim Augmentation in Patients with Unilateral Cleft Lip/Palate During Alveolar Cleft Bone Grafting

Background

Alveolar bone grafting in unilateral cleft lip/palate (CLP) patients can improve nasal symmetry and facial esthetic. In some cases lateral piriform hypoplasia cannot be compensated by soft tissue thickness of the face, necessitating onlay bone grafting. This study was designed to estimate the proportion of patients among unilateral CLP patients requiring this procedure.

Materials and Methods

In a retrospective study, unilateral CLP patients with severe paranasal deficiency, who were managed by paranasal augmentation with cortico-cancellous bone graft during the alveolar cleft bone grafting, were included.

Results

From 85 unilateral CLP patients treated from 2005 to 2011 in the Oral and Maxillofacial Surgery Department, Mashhad University of Medical Sciences, fourteen patients were treated with lateral piriform augmentation technique. Mean age of the patients at the time of operation was 16 ± 4.8 years. Follow-up period was 2–6 years.

Conclusion

Concomitant alveolar bone grafting and lateral piriform augmentation is needed at least in 16.5 % of unilateral CLP patients.     

Timing of Implant Placement and Augmentation with Bone Replacement Material: Clinical Assessment at 8 and 16 Months

Purpose: The purpose of this study is to evaluate implants placed at different times of bone augmentation. Materials and Methods: Four implants were placed in seven dogs: one at a 6‐month bovine mineral grafted site (6‐month Bio‐Oss® grafted site [6mBio]), one at a grafted membrane‐protected simultaneously augmented (Fresh Bio‐Oss® grafted site [FrBio]) site, one at a clotted (nongrafted clotted membrane‐protected site [Clot]) membrane‐protected site, and one at a pristine (nongrafted uncovered site [Cont]) site. Implants were exposed after 6 months. The same protocol was repeated on the contralateral side, at a delay of 8 months. Peri‐implant care was performed throughout the hygienic phase (2 and 10 months, respectively) every 48 to 72 hours. Probing depth and bleeding on probing were recorded. Implant stability was determined by a Periotest® (Medizintechnik Gulden, Modautal, Germany). Statistical analysis was conducted using analysis of variance with repeated measures. Results: Average probing depth at the simultaneously grafted sites was 2.21 mm and 2.03 mm at 8 and 16 months, respectively. At the 6‐month grafted sites, it was 1.96 mm and 1.57 mm. At the Clot sites, it was 2.68 mm and 2.07 mm, and 2.21 mm and 1.82 mm at the Cont sites, respectively. The average bleeding on probing was 0.50 and 0.42 at the FrBio sites, and 0.35 and 0.07 at the 6mBio sites during the respective periods. At the Clot sites, it was 0.50 and 0.28, and at the Cont sites, 0.43 and 0.21, respectively. Probing depth significantly reduced over the time at 6mBio, Clot, and Cont sites (p < .03). Average implant stability score at the FrBio sites was ?0.24 and ?0.27, and ?0.50 and ?0.46 at the 6mBio sites, at 8 and 16 months, respectively. At the Clot sites, it was ?0.35 and ?0.46. Cont sites averaged ?0.37 at both periods. Implant stability was significantly higher (p < .005) comparing 6mBio over FrBio, 6mBio over Cont, and Clot over FrBio sites. Conclusions: Immediate and delayed augmentations are safe modes. Probing depth and bleeding indices gradually improved along time. Implant stability was higher at the delayed mode.     

Fresh‐Frozen Bone Allografts in Maxillary Alveolar Augmentation: Analysis of Complications,Adverse Outcomes,and Implant Survival

Background: Success of any bone augmentation procedure is dependent on several factors. Because complications occur in some cases, the aims of this study are to analyze adverse events associated with placement of fresh‐frozen bone allografts (FFBAs) during alveolar ridge augmentation and to assess 1‐year survival of dental implants placed in reconstructed sites. Methods: Fifty‐eight consecutive patients (15 males and 43 females, aged 38 to 76 years; mean age: 58 ± 9.2 years) requiring maxillary bone reconstruction prior to implant placement were enrolled in this study. A total of 268 implants was subsequently placed in sites reconstructed with FFBAs. There were 22 posterior grafted sites, 19 anterior, and 17 full‐arch sites. After a 4‐ to 6‐month integration period, all patients received an implant‐supported fixed prostheses. Complications occurring during treatment and the 12‐month follow‐up period were recorded and evaluated. Results: Thirteen of 58 (22.41%) patients experienced some kind of complication in the receptor site. Infection occurred in six (10.34%) individuals, dehiscence in five (8.62%), and mucosal perforation in seven (12.07%). Adverse outcomes categorized as partial and total graft loss occurred in four (6.90%) and three (5.17%) patients, respectively. Implant failure rate was 16 (5.97%) of the 268 fixtures placed in 12 (20.70%) of 58 patients. Conclusions: Infection and suture dehiscence are significantly correlated with graft loss in a maxillary FFBA augmentation. Patients with full‐arch grafting reconstructions lost significantly more implants. Early diagnosis and prompt management of adverse events seem to be of great importance in prevention of total graft loss.     

Platelet‐Rich Plasma–Assisted Guided Bone Regeneration for Ridge Augmentation: A Randomized,Controlled Clinical Trial

Background: Platelet‐rich plasma (PRP) contains a number of biologically active growth factors, and previous studies have reported conflicting ridge augmentation results. The primary aim of this randomized, controlled, masked, clinical trial was to determine if PRP combined with a rapidly resorbing cancellous allograft would enhance the regenerative result compared with an allograft without PRP. Methods: Thirty‐two patients with an edentulous ridge defect were sequentially entered into the study; four were excluded from data analysis. Fourteen patients received a cancellous allograft (CAN group) and the other 14 received a cancellous allograft mixed with PRP (PRP group). All 28 grafted sites were covered with a resorbable polylactide membrane. After elevation of a full‐thickness flap, horizontal ridge dimensions were measured with a digital caliper at the crest and 5 mm apical to the crest. Vertical ridge dimensions were measured from a tooth‐supported stent. All sites were reentered at 4 months, and a trephine core was obtained for histologic analysis before implant placement. Results: The crestal ridge width for the CAN group had a mean gain of 2.0 ± 1.2 mm, whereas the PRP group gained 2.9 ± 1.0, and the difference was statistically significant between groups (P <0.05). The percent vital bone was 36% ± 14% for the CAN group compared with 51% ± 15% for the PRP group and was statistically significant between groups (P <0.05). Loss of augmented ridge width was 34% ± 17% for the CAN group and 28% ± 17% for the PRP group (P >0.05). Conclusion: These clinical and histologic findings suggest that PRP enhanced bone regeneration and resulted in increased horizontal bone gain and percentage vital bone.     

Long‐Term Stability of Contour Augmentation With Early Implant Placement Following Single Tooth Extraction in the Esthetic Zone: A Prospective,Cross‐Sectional Study in 41 Patients With a 5‐ to 9‐Year Follow‐Up

Background: Early implant placement with simultaneous contour augmentation is documented with short‐ and medium‐term studies. The long‐term stability of contour augmentation is uncertain. Methods: In this prospective, cross‐sectional study, 41 patients with an implant‐borne single crown were examined twice, in 2006 and 2010. Clinical, radiologic, and esthetic parameters were assessed at both examinations. In addition, a cone beam computed tomographic (CBCT) image was obtained during the second examination to assess the dimensions of the facial bone wall. Results: All 41 implants demonstrated ankylotic stability without signs of peri‐implant infection at both examinations. The clinical parameters remained stable over time. Satisfactory esthetic outcomes were noted, as assessed by the pink and white esthetic score (PES/WES) indices. Overall, the PES scores were slightly higher than the WES scores. None of the implants developed mucosal recession over time, as confirmed by values of the distance between implant shoulder and mucosal margin and cast measurements. The periapical radiographs yielded stable peri‐implant bone levels, with a mean distance between implant shoulder and first visible bone‐implant contact value of 2.18 mm. The CBCT analysis demonstrated a mean thickness of the facial bone wall ≈2.2 mm. In two implants (4.9%) no facial bone wall was detectable radiographically. Conclusions: This prospective cross‐sectional study demonstrates stable peri‐implant hard and soft tissues for all 41 implants examined and satisfactory esthetic outcomes overall. The follow‐up of 5 to 9 years confirmed again that the risk for mucosal recession is low with early implant placement. In addition, contour augmentation with guided bone regeneration was able to establish and maintain a facial bone wall in 95% of patients.     

Bone Augmentation in Dental Implantology Using Press‐Fit Bone Cylinders and Twin‐Principle Diamond Hollow Drills: A Case Series

Background: Bone transplants are mostly prepared with cutting drills, chisels, and rasps. These techniques are difficult for unexperienced surgeons, and the implant interface is less precise due to unstandardized preparation. Cylindrical bone transplants are a known alternative. Current techniques include fixation methods with osteosynthesis screws or the dental implant. Purpose: A new bone cylinder transplant technique is presented using a twin‐drill principle resulting in a customized pressfit of the transplant without fixation devices and combining this with the superior grinding properties of a diamond coating. Materials and Methods: New cylindrical diamond hollow drills are used for customized press fit bone transplants in a case series of five patients for socket reconstruction in the front and molar region of maxilla and mandibula with and without simultaneous implant placement. Results: The technical approach was successful without intra or postoperative complications during the acute healing phase. Conclusion: The customized press fit completes a technological trias of bone cylinder transplant techniques adding to the assisted press fit with either osteosynthesis screws or the dental implant itself.     

Graft‐Free Maxillary Sinus Floor Elevation: A Systematic Review and Meta‐Analysis

Background: This systematic review and meta‐analysis aims to investigate survival rates of dental implants placed simultaneously with graft‐free maxillary sinus floor elevation (GFSFE). Factors influencing amount of vertical bone gain (VBG), protruded implant length (PIL) in sinus at follow‐up (PILf), and peri‐implant marginal bone loss (MBL) are also evaluated. Methods: Electronic and manual searches for human clinical studies on simultaneous implant placement and GFSFE using the lateral window or transcrestal approach, published in the English language from January 1976 to March 2016, were conducted. The random‐effects model and mixed‐effect meta‐regression were used to analyze weighted mean values of clinical parameters and evaluate factors that influenced amount of VBG. Results: Of 740 studies, 22 clinical studies were included in this systematic review. A total of 864 implants were placed simultaneously with GFSFE at edentulous sites having mean residual bone height of 5.7 ± 1.7 mm. Mean implant survival rate (ISR) was 97.9% ± 0.02% (range: 93.5% to 100%). Weighted mean MBL was 0.91 ± 0.11 mm, and it was significantly associated with the postoperative follow‐up period (r = 0.02; R² = 43.75%). Weighted mean VBG was 3.8 ± 0.34 mm, and this parameter was affected significantly by surgical approach, implant length, and PIL immediately after surgery (PILi) (r = 2.82, 0.57, 0.80; R² = 19.10%, 39.27%, 83.92%, respectively). Weighted mean PILf was 1.26 ± 0.33 mm (range: 0.3 to 2.1 mm). Conclusion: Within limitations of the present systematic review, GFSFE with simultaneous implant placement can achieve satisfactory mean ISR of 97.9% ± 0.02%.     

Effects of Recombinant Human Bone Morphogenetic Protein‐2 on Vertical Bone Augmentation in a Canine Model

Background: Vertical bone augmentation (VBA) remains unpredictable and challenging for most clinicians. This study aims to compare hard tissue outcomes of VBA, with and without recombinant human bone morphogenetic protein (rhBMP)‐2, under space‐making titanium mesh in a canine model. Methods: Eleven male beagle dogs were used in the study. Experimental ridge defects were created to form atrophic ridges. VBA was performed via guided bone regeneration using titanium mesh and allografts. In experimental hemimandibles, rhBMP‐2/absorbable collagen sponge was well mixed with allografts prior to procedures, whereas a control buffer was applied within controls. Dogs were euthanized after a 4‐month healing period. Clinical and radiographic examinations were performed to assess ridge dimensional changes. In addition, specimens were used for microcomputed tomography (micro‐CT) assessment and histologic analysis. Results: Membrane exposure was found on five of 11 (45.5%) rhBMP‐2–treated sites, whereas it was found on nine of 11 (81.8%) non–rhBMP‐2–treated sites. Within 4 months of healing, rhBMP‐2–treated sites showed better radiographic bone density, greater defect fill, and significantly more bone gain in ridge height (P <0.05) than controls. Experimental hemimandibles exhibited lower rates of membrane exposure and a noteworthy, ectopic bone formation above the mesh in 72% of sites. Results from micro‐CT also suggested a trend of less vertical bone gain and bone mineral density in controls (P >0.05). Under light microscope, predominant lamellar patterns were found in the specimen obtained from rhBMP‐2 sites. Conclusion: With inherent limitations of the canine model and the concern of such a demanding surgical technique, current findings suggest that the presence of rhBMP‐2 in a composite graft allows an increase of vertical gain, with formation of ectopic bone over the titanium mesh in comparison with non–rhBMP‐2 sites.