Quality assessment of systematic reviews on vertical bone regeneration.

The aim of this study was to evaluate and compare the quality of systematic reviews of vertical bone regeneration techniques, using two quality-assessment tools (AMSTAR and ROBIS). An electronic literature search was conducted to identify systematic reviews or meta-analyses that would evaluate at least one of the following outcomes: implant survival, success rates, complications or bone gain after vertical ridge augmentation. Methodological quality assessment was performed by two independent evaluators. Results were compared between reviewers, and reliability measures were calculated using the Holsti's method® and Cohen's kappa. Seventeen systematic reviews were included, of which seven presented meta-analysis. Mean ±95% confidence interval AMSTAR score was 6.35 [4.74;7.97], with higher scores being correlated with a smaller risk of bias (Pearson's correlation coefficient=-0.84; P<0.01). Cohen's inter-examiner kappa showed substantial agreement for both checklists. From the available evidence, we ascertained that, regardless of the technique used, it is possible to obtain vertical bone gains. Implant success in regenerated areas was similar to implants placed in pristine bone with results equating between 61.5% and 100% with guided bone regeneration being considered the most predictable technique regarding bone stability, while distraction osteogenesis achieved the biggest bone gains with the highest risk of possible complications.

Assessment of the distraction regenerate using three-dimensional quantitative computer tomography.

This study presents a new method for objective assessment of the distraction regenerate using three-dimensional quantitative computer tomography (3D-QCT). The distraction specimens of 16 sheep that underwent bifocal cranial distraction osteogenesis to reconstruct a critical size defect were used to evaluate this method. To analyse the validity of this method the results were compared to conventional quantitative computer tomography (QCT). Squared correlation coefficients (r(2)) according to Sackett showed a high reliability (r(2) > 70% for the total DO regenerate, DO Regions 2-4). Method comparison according to Bland-Altman (< or =6.25% of measurements out of 95% limits of agreement) showed that three-dimensional computer tomography based bone densitometry is valid for future DO research.

Assessment of the incorporation of revascularized fibula grafts used for mandibular reconstruction with F-18-PET.

AIM: Determination of the range of regional blood flow and fluoride influx during normal incorporation of revascularized fibula grafts used for mandibular reconstruction. Evaluation, if healing complications are preceded by typical deviations of these parameters from the normal range. Assessment of the potential influence of using "scaled population-derived" instead of "individually measured" input functions in quantitative analysis. METHODS: Dynamic F-18-PET images and arterialized venous blood samples were obtained in 11 patients early and late after surgery. Based on kinetic modeling regional blood flow (K1) and fluoride influx (Kmlf) were determined. RESULTS: In uncomplicated cases, early postoperative graft K1--but not Kmlf--exceeded that of vertebrae as reference region. Kmlf values obtained in graft necrosis (n = 2) were below the ranges of values observed in uncomplicated healing (0.0113-0.0745 ml/min/ml) as well as that of the reference region (0.0154-0.0748). Kmlf values in mobile non-union were in the lower range--and those in rigid non-union in the upper range of values obtained in stable union (0.0211-0.0694). If scaled population-derived instead of measured input functions were used for quantification, mean deviations of 23 +/- 17% in K1 and 12 +/- 16% in Kmlf were observed. CONCLUSIONS: Normal healing of predominantly cortical bone transplants is characterized by relatively low osteoblastic activity together with increased perfusion. It may be anticipated that transplant necrosis can be identified by showing markedly reduced F- influx. In case that measured input functions are not available, quantification with scaled population-derived input functions is appropriate if expected differences in quantitative parameters exceed 70%.