Pre-clinical animal models are commonly used to evaluate the osteogenic potential of bone grafting materials in-vivo. Based on the histology analysis, the currently commercially available bone grafting materials show comparable results with respect to biocompatibility, incorporation and remodeling. In the present pilot study we introduce a methodology to compare calcium phosphate-based bone grafting materials from world-leading companies in clinical trials and analyze them by means of established histology and synchrotron radiation-based micro computed tomography (SRμCT). The results indicate that the morphology of the bony structures depends on the selected bone grafting material and that an arbitrarily selected histological slice can lead to misleading conclusions. Complementary μCT data can become the basis for the identification of a representative slice. The registration of the selected histological slice with its counterpart in the three-dimensional μCT dataset was performed both visually and automatically with well comparable results. This registration allows for the compilation of a joint histogram to identify anatomical features, which can neither be extracted from histology nor from μCT data on their own. Accordingly, μCT will become an integral part of studies on the efficacy of bone augmentation materials and beyond.

Objectives This retrospective clinical study investigates the frequency of biological and technical complications in patients rehabilitated by natural root-retained overdentures (RODs) with cast post-and-cores (root caps) wearing precision attachments and analyses factors influencing complication rates (e.g. oral hygiene routines). Materials and methods Patients formerly treated with RODs were invited for a cost-free clinical visit to evaluate their intraoral status. Furthermore, they were interviewed and patient records were screened for complications occurring since denture delivery. Statistical models include descriptive analyses, Fisher’s exact test, odds ratios, and a multivariate regression model. Results A total of 114 patients wearing 128 RODs with a total of 280 abutment teeth were evaluated (mean service time: 7.9 years). Technical complications occurred in 68.8% of the RODs, with matrix loosening being the most frequent complication (50.1%). Biological complications occurred in 53.9% of all RODs, with the presence of denture stomatitis being the most common biological complication (38.3%). The presence of denture stomatitis was significantly higher in the maxilla relative to the mandible (p = 0.0029), in subjects cleaning their dentures less than twice a day (p < 0.001), in subjects regularly using CHX-containing products (p = 0.036) and in subjects with a plaque index > 40% (p < 0.001). Conclusions Root cap-retained overdentures with precision attachments are a viable treatment option in partially dentate subjects, even over long-term periods. However, high complication rates should be expected. Clinical relevance Establishing good oral hygiene is a decisive factor in preventing complications in RODs. Furthermore, CHX-containing products may not be recommended for routine domestic use.

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Summary Background Root‐retained overdentures (OD) are one treatment option for partially edentulous patients. However, the available evidence regarding factors influencing abutment survival in root‐retained ODs is limited. Purpose This retrospective study included clinical examinations and evaluated the survival rate of roots restored with precision attachments soldered to post‐and‐core (gold cap) retained ODs, analysed with respect to various patient‐ and prosthesis‐related factors. Methods Patients receiving at least one OD with gold caps in the past were invited for comprehensive clinical examinations. The primary outcome parameter was the abutment survival rate over the observation period (2002‐2016). Possible contributing factors (eg closed vs open OD design) were analysed. Analyses included Kaplan‐Meier estimators, Cox regressions and hazard ratios (HR). Results 114 patients with 128 ODs originally retained by 280 abutments, with a cumulative total exposure time of 2035.4 years, were examined. Twenty‐seven abutment teeth (9.6%) were lost after a mean observation period of 7.9 ± 3.4 years. Significant factors associated with abutment loss were a closed, compared to an open OD design (HR 8.38 (95% CI 1.11‐63.59), P = .040), which was independent of the number of abutments per OD. Furthermore, the loss rate was higher when the denture was not worn day‐and‐night (HR 3.52 (95% CI 1.32‐9.40), P = .012). Oral hygiene behaviour was associated with higher HRs. Conclusions ODs remain a viable treatment option for patients with few teeth remaining in the dental arch. It is advisable to choose an open design for the OD, irrespective of the number of abutment teeth. Furthermore, gold cap‐retained ODs should not be removed overnight.

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