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PurposeThis study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides.Materials and MethodsThree gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer's imaging software. The same measurements were then taken with the CBCT software.ResultsThe anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study.ConclusionThe proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

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Objectives: Modern polyamide 'flexible' denture base materials have increased in popularity for use in removable partial dentures. The introduction of these new products warrants investigation of their relative potential for toxicity. The purpose of this study was to investigate three contemporary denture base materials used in fabricating definitive prosthetic restorations. Materials and methods:Two 'flexible' materials (Valplast™ and Duraflex™) formed by thermoplastic injection molding technique, and one traditional heat processed, methyl methacrylate resin material (Lucitone 199) were evaluated. Cultured gingival epithelial cells and fibroblasts were treated with conditioned media prepared from denture material disks and then assayed for cell toxicity by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) cell viability assay. Cell membrane damage was determined by measuring the release of cytoplasmic lactate dehydrogenase. Further confirmation of toxicity induced by the conditioned media was determined by staining the cells with live/dead stain and observing under a UV microscope.Results: Data were analyzed by means of a linear model ANOVA followed by Tukey's post hoc tests for comparison among groups. The significance level adopted was 5% (p < 0.05). The three denture materials differed in their toxicity to the cells as assessed by MTT assay. Valplast conditioned media in general, especially the media of unpolished disks, was found to be toxic to both gingival fibroblasts and epithelial cells while media obtained from polished Lucitone and Duraflex were found to be less toxic. After 7 days of incubation with Valplast unpolished conditioned media, only 1 to 2% of the cells remained viable, while the polished disk conditioned media caused significantly less (p < 0.05) toxicity, approximately 76 and 92% of fibroblasts and epithelial cells respectively, were viable. After 7 days of incubation with media obtained from the other denture materials, 35 to 92% of fibroblasts and epithelial cells were found to be viable. The data obtained from lactate dehydrogenase (LDH) assay and live/dead mammalian cell viability assay were in agreement with the MTT viability assay. Conclusion:Conditioned media from unpolished Valplast denture material appeared to be significantly more toxic to gingival fibroblasts and epithelial cells when compared to the polished Lucitone disk conditioned media as well as the media obtained from Duraflex.

This study suggests that screw position can be an indicator of fit in dental implant prostheses if the end point of screw rotation is adequately indexed, specific to each assembly and screw.