How are the color parameters of a CAD/CAM feldspathic ceramic of the material affected by its thickness, shade, and color of the substructure?

OBJECTIVES: The purpose of this study was to evaluate the effect of the tooth color, ceramic color, and ceramic thickness on the final color parameters of a feldspathic computer-aided design (CAD)/computer-aided manufacturing (CAM) ceramic material. MATERIALS AND METHODS: Resin specimens (12 × 14 × 4 mm) were prepared from six shades, namely, 0M1S, 1M1S, 2M3S, 3M2S, 4M3S, and 5M3S, to simulate tooth color. Ceramic slices with thicknesses of 0.3, 0.5, 0.7, and 1 mm were sectioned from Vitablocs Mark II (12 × 14 × 18 mm) in 10 shades-OM1C, 1M1C, 1M2C, 2M1C, 2M2C, 2M3C, 3M1C, 3M2C, 3M3C, and 4M2C. An intraoral spectrophotometer was used and three axes of Commission Internationale de l'Eclairage (CIE) LAB color space (CIE L* a* b*) and chroma (C) and hue (H) values were obtained. RESULTS: The a* and b* values showed a decrease with increasing thickness. Generally, C decreased with the increasing ceramic thickness. The effect of ceramic thickness on H changed depending on the block and substructure color. The change of ceramic thickness resulted in changes in the lightness parameter (L*) of the ceramics. Generally, with an increase in the thickness, the L* value increased. The univariate analysis of variance (ANOVA) indicated a significant interaction between ceramic thickness and substructure color (P <. 005) and ceramic thickness and ceramic color (P <. 005). CONCLUSION: The final color parameters of a feldspathic CAD/CAM block were significantly affected by the changes in the ceramic thickness and substructure color.

InLab and Cerec Connect: virtual contacts in maximum intercuspation compared with original contacts--an in vitro study.

PURPOSE: The aim of this in-vitro study was to evaluate the accuracy of inLab and Cerec Connect software in simulating the maximum intercuspal contacts in comparison to the real situation on the respective gypsum casts. MATERIALS AND METHODS: Ten pairs of maxillary and mandibular casts were mounted in articulators in maximum intercuspal position. The contacts of the gypsum casts were marked and digital photographs of the mandibular casts were taken. Digital impressions of arches were made using two different software packages; inLab (Version 3.83) and Cerec Connect (Version 3.83) using the Cerec Acquisition Center. The intercuspal position of the teeth was captured by buccal images. Screenshots of the virtual casts showing the occlusal contacts were saved. The digital photographs of the contacts of the cast and the screenshots of the occlusal contacts were superimposed using an image processing program. The number of contacts of the virtual mandibular models that were identical with the contacts of the gypsum casts were determined and calculated as percentages in relation to the gypsum cast contacts, which were set as 100%. The null hypothesis tested was that the Cerec connect software delivers contacts that are closer to the real situation than contacts created with the inLab software. RESULTS: Cerec Connect showed a median percentage of 41.6% and Inlab a median percentage of 31.9%. The Wilcoxon test revealed statistically significant differences between the inLab software and Cerec Connect. Especially at the contra-lateral side of that side where the virtual buccal registration was done, the contacts showed the greatest deviations from the original. CONCLUSION: Cerec Connect more precisely virtually simulated the real contacts than did inLab when scanning full-arch dentitions.

Clinical evaluation of submerged and non-submerged implants for posterior single-tooth replacements: a randomized split-mouth clinical trial.

The aim of this study was to evaluate clinical and radiographic results of submerged and non-submerged implants for posterior single-tooth replacements and to assess patient-based outcomes. Twenty patients were included in the study. A split-mouth design was used; implants inserted using a submerged technique were compared to those inserted with a non-submerged technique. Implants were restored with metal-ceramic crowns after 3 months. Reconstructions were examined at baseline, 6, 12, and 24 months. Standardized radiographs were made. Radiographic crestal bone level changes were calculated, as well as soft tissue parameters, including pocket probing depth, bleeding on probing, plaque index, and gingival index. Results were analyzed by two-way repeated measures of variance (ANOVA). To evaluate patient-based outcomes, patients were asked to complete a questionnaire at the 6-month follow-up; the Wilcoxon paired signed rank test was used to compare scores. The data of 18 patients were reviewed. During 24 months, non-submerged implants (0.57 ± 0.21 mm) showed significantly lower bone loss than submerged implants (0.68 ± 0.22 mm) (P<0.01). Patient satisfaction with non-submerged implants (median 87.5) was significantly higher than with submerged implants (median 81.5) (P<0.01). Non-submerged implants showed comparable clinical results to submerged implants and resulted in higher patient satisfaction due to decreased surgical intervention.