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.     

Advanced platelet‐rich fibrin and freeze‐dried bone allograft for ridge preservation: A randomized controlled clinical trial

1 Background

Advanced platelet‐rich fibrin (A‐PRF) is an autogenous blood product with applications in dento‐alveolar surgery. However, there is minimal information regarding its optimal clinical application or efficacy. The aim of this multi‐arm parallel randomized controlled clinical trial was to evaluate the efficacy of A‐PRF alone or with freeze‐dried bone allograft (FDBA) in improving vital bone formation and alveolar dimensional stability during ridge preservation.

2 Methods

Forty patients requiring extraction of non‐molar teeth and replacement with dental implants were randomized into one of four ridge preservation approaches: A‐PRF, A‐PRF+FDBA, FDBA, or blood clot. A‐PRF was prepared at 1,300 rpm for 8 minutes. Non‐traumatic extractions and ridge preservation was performed. After an average of 15 weeks healing, bone core samples were harvested at the time of implant placement for micro‐CT and histomorphometric analysis. Ridge dimensions were measured immediately after extraction and before implant placement.

3 Results

Significantly greater loss of ridge height was noted in the blood clot group (3.8 ± 2.0 mm) compared to A‐PRF (1.8 ± 2.1 mm) and A‐PRF+FDBA (1.0 ± 2.3 mm) groups (P < 0.05). No significant differences in ridge width reduction were noted between groups. Significantly more vital bone was present in the A‐PRF group (46% ± 18%) compared to the FDBA group (29% ± 14%) (P < 0.05). Bone mineral density was significantly greater in the FDBA group (551 ± 58 mg/cm³) compared to blood clot (487 ± 64 mg/cm³) (P < 0.05).

4 Conclusions

This study demonstrates A‐PRF alone or augmented with FDBA is a suitable biomaterial for ridge preservation. This study represents the first randomized controlled clinical trial comparing A‐PRF with and without FDBA to FDBA alone for ridge preservation.     

Lateral ridge augmentation using equine‐ and bovine‐derived cancellous bone blocks: a feasibility study in dogs

Objectives: The aim of the present study was to histologically evaluate and compare a new prototype collagen type I/III‐containing equine‐ (EB) and a bovine‐ (BB) derived cancellous bone block in a dog model. Materials and methods: Four standardized box‐shaped defects were bilaterally created at the buccal aspect of the alveolar ridge in the lower jaws of five beagle dogs and randomly allocated to either EB or BB. Each experimental site was covered by a native (non‐crosslinked) collagen membrane and left to heal in a submerged position for 12 weeks. Dissected blocks were processed for semi‐/and quantitative analyses. Results: Both groups had no adverse clinical or histopathological events (i.e. inflammatory/foreign body reactions). BB specimens revealed no signs of biodegradation and were commonly embedded in a fibrous connective tissue. New bone formation and bony graft integration were minimal. In contrast, EB specimens were characterized by a significantly increased cell (i.e. osteoclasts and multinucleated giant cells)‐mediated degradation of the graft material (P<0.001). The amount and extent of bone ingrowth was consistently higher in all EB specimens, but failed to reach statistical significance in comparison with the BB group (P>0.05). Conclusions: It was concluded that the application of EB may not be associated with an improved bone formation than BB. To cite this article:
Schwarz F, Ferrari D, Balic E, Buser D, Becker J, Sager M. Lateral ridge augmentation using equine‐ and bovine‐derived cancellous bone blocks: a feasibility study in dogs.
Clin. Oral Impl. Res. 21 , 2010; 904–912.
doi: 10.1111/j.1600‐0501.2010.01951.x     

Biodegradation Property of Beta‐Tricalcium Phosphate‐Collagen Composite in Accordance with Bone Formation: A Comparative Study with Bio‐Oss Collagen® in a Rat Critical‐Size Defect Model

Purpose: The objective of this study was to compare osteoconductivity and biodegradation properties of an in‐house fabricated beta‐tricalcium phosphate (b‐TCP)‐collagen composite with those of Bio‐Oss Collagen® (Osteohealth, Shirley, NY, USA) using a rat calvarial critical‐size defect model. Materials and Methods: b‐TCP–collagen composite material was fabricated by mixing b‐TCP granules having a particle size of 0.15 to 0.8 mm and 75% porosity, with bovine dermis‐derived soluble collagen sponge. The dry weight ratio of b‐TCP granules‐to‐collagen ratios was 4:1. Bio‐Oss Collagen or the b‐TCP–collagen composite was used to fill a 5.0 mm–diameter calvarial defect in rats. The defects were evaluated by histological and histomorphological analyses of decalcified histological sections with hematoxylin and eosin staining 6 and 10 weeks, respectively, after surgery. Results: The defect implanted with the b‐TCP composite contained immature bone structures with dense connective tissue in contrast to the abundant fibrous tissue, but no trabecular structure was observed within the defect implanted with Bio‐Oss Collagen at 6 weeks postoperatively. Eventually, the defect filled with the b‐TCP composite was covered with dense, continuous, mature bone tissue with complete replacement of the graft material. However, in defects filled with Bio‐Oss Collagen, only dense connective tissue, containing limited amounts of immature trabecular bone and abundant remnant Bio‐Oss particles, was observed. Histomorphological analysis revealed that the b‐TCP composite caused greater tissue augmentation with a larger volume of bone tissue observed in the defect and greater bioabsorption of remnant material than Bio‐Oss Collagen. Conclusion: These results indicated that the b‐TCP composite has greater osteoconductivity and better biodegradation properties than Bio‐Oss Collagen; these properties of the b‐TCP–collagen composite complimented bone formation and remodeling.