Correlation of cone beam CT-derived bone density parameters with primary implant stability assessed by peak insertion torque and periotest in the maxilla.

PURPOSE: Primary implant stability is crucial to osseointegration. The aim of this study was to assess correlation of preoperative radiologic parameters with intraoperatively obtained biomechanical tests in the maxilla. MATERIALS AND METHODS: A total of 259 implants were inserted in the maxilla of 99 patients. Cone-beam computed tomography (CBCT)-derived Hounsfield units (HU), voxel grey values and computed tomography mental index (CTMI) performed preoperatively were correlated with insertion torque and Periotest (obtained intraoperatively and 12 weeks later) to assess their prognostic value for primary implant stability. RESULTS: Voxel grey values and insertion torque showed a low correlation (r = 0.329, p = 1.055×10-7 ). Likewise, a low correlation was found between HU measured preoperatively and insertion torque as well as intraoperative Periotest values (r = 0.297, p = 4×10-6 and r = - 0.234, p = 4.35×10-4, respectively). A moderate correlation could, however, be assessed between insertion torque and intraoperative as well as Periotest values 12 weeks later. (r = -0.555, p = 1.022×10-20 and -0.465. p = 1.150×10-13). On contrast, a high correlation was observed between the voxel grey values of CBCT and related HU (r = 0.710, p = 6.486×10-37 ) so that a conversion from grey values into HU could be suggested. According to regression analysis, an intraoperative negative Periotest value could be expected at an insertion torque of 40 N/cm upwards. CONCLUSION: CBCT-based bone density parameters correlate with each other and allow conversion of grey scales into HU preoperatively. Both insertion torque and Periotest showed a significant correlation which enables regression analysis to predict implant stability for related insertion torque. On contrast, for HU the distribution curves do not allow a reliable assignment into certain Periotest values.

Sinus augmentation with bovine hydroxyapatite/synthetic peptide in a sodium hyaluronate carrier (PepGen P-15 Putty): a clinical investigation of different healing times.

PURPOSE: Augmentation of the sinus floor with autogenous bone often requires an extra donor site, which is associated with a risk of morbidity, and current grafting protocols involve healing times of up to 9 months. In this prospective in vivo study, the time-dependent efficacy of PepGen P-15 Putty, a combination of bovine hydroxyapatite and synthetic peptide in a sodium hyaluronate carrier, was evaluated in sinus grafting. MATERIALS AND METHODS: Twenty-four edentulous patients received bilateral sinus augmentations with PepGen P-15 Putty, which mimics the cell-binding domain of type I collagen responsible for cell migration, differentiation, and proliferation. The patients were randomly divided into four groups of six patients each, corresponding to 2, 4, 6, and 9 months of healing postaugmentation. After these time intervals, bone biopsy specimens were retrieved through the alveolar bone crest into the augmented sinus, and subsequently oral implants were placed. The specimens were immersed in buffered formalin, scanned with a desktop microcomputed tomography machine, and processed for histologic and histomorphometric evaluation. A mixed model was used for statistical analysis. RESULTS: Three-dimensional microcomputed tomography depicted the distinct structure of trabecular bone encompassing remnants of PepGen, and histologic evaluation revealed osteoblasts and osteoid with osteocytes in the vicinity of the PepGen particles at all healing stages. Histomorphometric results indicated an increase in the newly formed bone fraction in the specimens as follows: 21.3% (± 2.33) at 2 months, 21.9% (± 8.9) at 4 months, 28.5% (± 6.9) at 6 months, and 29.8% (± 11.8) at 9 months. The differences were statistically insignificant. All implants placed in the augmented sites integrated and were restored prosthetically. CONCLUSIONS: PepGen can be used successfully for maxillary sinus augmentation. These data provide evidence that implant placement, even after only 2 months of healing, may be possible.