Analysis of the influence of residual alveolar bone height on sinus augmentation outcomes

Introduction Maxillary sinus augmentation is a predictable implant site development technique for posterior atrophic maxillary ridges. However, graft consolidation requires adequate angiogenesis and migration of osteogenic cells from native bone. Therefore, the amount of residual bone height ( RBH ) may play a role in the rate of graft maturation. The purpose of this study was to analyze the influence of RBH in the histomorphometric outcomes of maxillary sinus augmentation procedures. Material and methods Patients in need of sinus augmentation were recruited for the study. Customized radiographic guides were fabricated and a cone‐beam computerized tomography scan was obtained at baseline. Two examiners measured RBH on the scans at the locations marked by the radiographic guide. Sinus grafting was performed by a lateral window approach using a particulated mineralized allograft. Patients were followed up for 6 months. At the time of implant placement, bone core biopsies were harvested using the radiographic guide, which was converted into a surgical guide. Samples were histomorphometrically analyzed. Proportion of vital bone (% VB ), remaining allograft particles (% RA ), and non‐mineralized tissue (% NMT ) were quantified. Categorical analysis of correlation of RBH (<4 or ≥4 mm) with% VB and% RA was performed using a statistical model. Results Twenty‐one patients underwent sinus augmentation for a total of 21 sinuses. One patient developed an infection after grafting and was excluded. Histomorphometric analysis revealed that mean% VB was 20.47 ± 18.25, mean % RA was 29.04 ± 24.94, and average % NMT was 50.47 ± 12.76. No significant correlation between RBH and % VB ( r  = 0.016; P  =   0.951), and RBH and % ( r  = 0.009; P  =   0.971) was found. Similarly, categorical analysis of correlation showed no statistical significance. Conclusion These findings suggest that the remaining alveolar bone height does not appear to influence the maturation and consolidation of an allograft in the maxillary sinus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93580/1/clr2270.pd

The effect of collagenated space filling materials in sinus bone augmentation: a study in rabbits

Aim: The inclusion of biomaterial particles used for alveolar bone regeneration in a carrier or in binding agents such as collagen gel or fibers is of interest as a means to help with surgical handling. However, the possible influence of collagen on bone tissue response to biomaterials is poorly studied. The objective of the present study was to investigate, in a sub-sinus bone augmentation model in rabbits, the effect of collagen at different stages of the osteogenesis process. Histologic, histomorphometric and volumetric analyses were performed. Materials and methods: Rabbits underwent a double sinus lift procedure using bovine hydroxyapatite (BHA), collagenated bovine hydroxyapatite (BHAColl), and prehydrated and collagenated porcine hydroxyapatite (PHAColl). Animals were sacrificed at 1 week, 5 weeks or 6 months. Samples were subjected to X-ray micro-tomography and histology. Qualitative analysis was performed on the non-decalcified sections and quantitative histomorphometric analyses were conducted using scanning electron microscopy (SEM). Volume variations of bone augmentations were calculated at different time points. Results: The three biomaterials allowed an optimal bone formation and were able to equally withstand sinusal reexpansion. A comparable percentage of new bone, as well as 3D volume stability, was found between the groups at each time point. However, the PHAColl resorption rate was significantly higher than the rates in other groups (P = 0.0003), with only 3.6% of the particles remaining at 6 months. At 1 week, both collagenated groups displayed the presence of inflammatory cells although BHA did not show any sign of inflammation. At 5 weeks and 6 months, the inflammatory process had disappeared completely in the BHAColl groups, whereas some inflammatory-like cells could still be observed around the remaining particles of PHAColl. Conclusions and clinical implications: Within the limitations of this study in rabbits, the findings showed the presence of inflammatory-like cells at the early stage of bone regeneration when collagenated xenogenic biomaterials were used compared to xenogenic granules alone. Nevertheless, similar bone formation occurred and comparable 3D volumes were found at 6 months in the different groups

Single tooth implants in the esthetic zone following a two-stage all flapless approach: A retrospective Analysis

BACKGROUND Due to chronic inflammation or trauma facial bone is frequently missing after tooth loss in the esthetic zone. As a consequence, procedures to augment or at least to preserve bone are frequently necessary prior to implant placement. PURPOSE The aim of this retrospective case series is to demonstrate the applicability of a staged all-flapless concept to establish satisfactory implant restorations following situations of partial missing facial bone in the esthetic zone. MATERIALS AND METHODS Radiological/clinical data of 25 patients were analyzed and an esthetic evaluation of 24 patients was performed. The staged concept included ridge preservation at time of tooth extraction and delayed guided implant placement. Marginal bone loss was measured radiologically and esthetic evaluation was performed based on standardized photographs using the Pink Esthetic Score as well as the Papilla Index. RESULTS Implant success rate revealed 100%. The mean radiological peri-implant marginal bone loss measured 1.16 mm (SD: 0.16). Regarding the esthetic outcome 71% of patients were evaluated with a Pink Esthetic Score higher or equal to 10 constituting satisfactory esthetics (median pink esthetic score: 10). The mean follow-up time for clinical and radiographic analysis was 1.3 years (SD: 0.6 years) and 1.2 years (SD: 0.6) for esthetic evaluation. CONCLUSION Although marginal bone loss cannot be avoided, the staged concept of flapless ridge preservation and subsequent delayed flapless guided implant placement carries the potential to improve esthetics of single-tooth implants in the anterior maxilla

Osteocyte lacunar density and area in newly formed bone of the augmented sinus

OBJECTIVES Osteocytes, the most common cells of the bone, are buried in lacunae. Density and area of the osteocyte lacunae change with increasing maturation of the newly formed bone. Evaluation of osteocyte lacunae can therefore provide insights into the process of graft consolidation. MATERIALS AND METHODS Here, we determined the osteocyte lacunar density (number of osteocyte lacunae per bone area; N.Ot/BAr) and the osteocyte lacunar area in μm(2) (Lac.Ar) in histological specimens 6 and 12 weeks after the sinuses of 10 minipigs were augmented with Bio-Oss(®) , a deproteinized bovine bone mineral, and Ostim(®) , an aqueous paste of synthetic nanoparticular hydroxyapatite. The region of interest was defined by the following criteria: (i) >1 mm from the host bone, (ii) >0.5 mm from the sinus mucosa, (iii) minimum area of 0.2 mm(2) , and (iv) bone tissue spanning at least two bone substitute particles. RESULTS The overall osteocyte lacunar density was significantly higher in the Bio-Oss(®) group than in the Ostim(®) group and decreased during the observation period at a similar range in both groups. The osteocyte lacunar area was smaller in the Bio-Oss(®) group than the Ostim(®) group but there was no significant change within the groups over time. CONCLUSIONS These results suggest that bone substitutes affect the osteocyte lacunar density and the osteocyte lacunar area in the newly formed bone within the augmented sinus in this particular model situation. These measures can provide insights into the maturation of newly formed bone in the augmented sinus

Graft Remodeling following Transcrestal Sinus Floor Elevation via the Gel-Pressure Technique (GPT) and Pasteous Nano-Crystalline Hydroxyapatite Bone Substitute

Bone grafting of the maxillary sinus is attempted to compensate for sinus pneumatization and permit reliable insertion of endosseous dental implants for prosthetic rehabilitation. The aim of the present clinical investigation was to study bone regeneration four months after transcrestal sinus floor elevation via the Gel-Pressure Technique (GPT) and application of pasteous nano-crystalline hydroxyapatite bone substitute. A total of 25 patients with deficient alveolar ridges in the posterior maxilla (mean residual bone height: 4.7 ± 1.8 mm) were subjected to 32 flapless transcrestal sinus floor augmentations and simultaneous insertion of 40 implants. Sinus membrane elevation height averaged 11.2 ± 2.7 mm and minimal vertical graft resorption of 0.1 mm was observed after four months. Radiographic bone density averaged 460 Hounsfield units in regions adjacent to the native jawbone (1 to 7 mm distance), while reduction of bone density by −7.2%, −11.3%, −14.8%, −19.6% and −22.7% was recorded in more apical regions of 8, 9, 10, 11, and ≥12 mm distance to the original sinus floor, respectively. The results suggest that graft remodeling is completed up to a distance of 7 mm within a healing period of four months after sinus augmentation using nano-crystalline hydroxyapatite bone substitute material