Cement Thickness of Inlay Restorations Made of Lithium Disilicate, Polymer-Infiltrated Ceramic and Nano-Ceramic CAD/CAM Materials Evaluated Using 3D X-Ray Micro-Computed Tomography.

PURPOSE: To evaluate the marginal and internal cement thicknesses of inlay restorations made of various CAD/CAM materials using 3D X-ray micro-computed tomography (micro-CT) technique. MATERIALS AND METHODS: Caries-free extracted mandibular molars (N = 30) with similar size were randomly assigned to three groups (N = 10 per group). Mesio-occlusal-distal (MOD) cavities were prepared, and inlay restorations were obtained by milling out CAD/CAM materials namely, (a) IPS: monolithic lithium disilicate (control), (b) VE: polymer-infiltrated ceramic, and (c) CS: nano-ceramic using a CAM unit. Marginal and internal cement thicknesses were measured using 3D micro-CT. Data were analyzed using 1-way ANOVA and Tukey's tests (alpha = 0.05). RESULTS: The mean marginal and internal cement thickness were not significant in all inlay materials (p > 0.05). Mean marginal cement thickness (µm) was the lowest for the IPS group (67.54 ± 10.16) followed by VE (84.09 ± 3.94) and CS (95.18 ± 10.58) (p > 0.05). The internal cement thickness (µm) was the lowest in the CS group (54.85 ± 6.94) followed by IPS (60.58 ± 9.22) and VE (77.53 ± 12.13) (p > 0.05). CONCLUSION: Marginal and internal cement thicknesses of MOD inlays made of monolithic lithium disilicate, polymer-infiltrated ceramic, and nano-ceramic CAD/CAM materials were similar and all less than 100 µm, which could be considered clinically acceptable. CLINICAL SIGNIFICANCE: MOD inlays made of different CAD/CAM materials presented similar cement thickness, less than 100 µm.

A Cross-Sectional Survey on Reasons for Initial Placement and Replacement of Single Crowns.

This cross-sectional survey investigated the reasons for placement and replacement of single crowns, the type of materials selected for initial placement and evaluated their longevity. Information was collected over 19 months period using a questionnaire focusing on the principal reasons for the placement and replacement of crowns, selected material type and the age of the crowns at the time of replacement. A total of 842 single crowns were evaluated in 476 patients. Of the 842 crowns, 472 (56%) were initial placements and 370 (44%) replacements. The main reason for placement of first single crowns was related to endodontic problems (26.5%). Metal-ceramic was indicated significantly more frequent (88.9%; p⟨0.01) than other materials for the placement and replacement of single crowns. The median age of the replaced crowns was 6 years.

Analysis of Endodontic Complications Following Fixed Prosthodontic Rehabilitation.

PURPOSE: The aim of this study was to determine endodontic treatment needs and types of endodontic disease following fixed prosthodontic treatment 24 hours after tooth preparation, 1 week after tooth preparation, 1 month after placement, and 6 months after placement. MATERIALS AND METHODS: Study groups consisted of patients who attended a university dental hospital department of prosthodontics for fixed prosthodontic treatment from January 2011 to December 2013. All teeth were clinically and radiographically evaluated according to American Association of Endodontists evaluation criteria before preparation. Metal-ceramic fixed partial dentures were placed for all patients. A total of 1,633 abutment teeth were prepared with 1,100 pontics in 524 patients (214 female and 310 male). Participant age, sex, and tooth number were recorded. Endodontic treatment follow-up was scheduled for 24 hours after tooth preparation, 1 week after preparation, 1 month after placement, and 6 months after placement, and all teeth were evaluated after placement of FPDs according to a modified criteria. RESULTS: 2,733 retainers were placed with 624 FPDs. Of the FPDs, 332 (53%) were placed in the posterior and 196 (31.5%) in the anterior region. The remaining 96 FPDs (15.5%) were placed anteroposterior. The abutment/pontic ratio was 1.44:1. The number of retainers per FPD was 4.37. Of 1,633 abutment teeth, 103 were endodontically treated after placement of FPDs. Most observed endodontic disease was symptomatic irreversible pulpitis. There were statistically significant differences in terms of teeth regions (P < .001). When follow-up times of 24 hours, 1 week, 1 month, and 6 months were evaluated, there was no statistically significant difference among all teeth groups (P > .05). CONCLUSION: A total of 2,733 retainers on 624 FPDs were evaluated over 6 months, and the mean endodontic treatment need ratio was 6.3%.

The effect of different adhesives and setting times on bond strength between Biodentine and composite.

BACKGROUND: The aim of this study was to evaluate the effects of 3 different adhesives with different functional monomers, on the shear bond strength (SBS) of Biodentine®. METHODS: Acrylic blocks (n = 90) were prepared and a 2-mm height x 4-mm diameter hole was opened in each block. Every hole was completely restored with Biodentine®. Before preparation of composite restorations over the Biodentine® (2-mm height x 2-mm diameter), 3 different adhesives (Etch-37 (37%) w/BAC by Bisco & Prime Bond N&T, Clearfil S3 Bond and Adper Prompt L-Pop) were applied. SBS was evaluated using a universal testing machine, and failure mode for each sample was recorded. The results were statistically analyzed using 2-way ANOVA and post hoc Tukey test. RESULTS: When the megapascal values of all groups were compared, although there was no statistically significant difference in the different setting times (p>0.05), statistically significant differences were observed among all adhesive groups (p<0.05). Moreover, the highest SBS values were observed in the Clearfil S3 Bond group. CONCLUSIONS: Clinical performance of Biodentine® may be affected by adhesive procedures and its setting time.

A Survey on Prevalence, Causes and Prevention of Postcementation Hypersensitivity.

This study evaluated the prevalence and causes of post-cementation sensitivity and possible prevention measures according to the experience of dentists through an internet survey. A questionnaire was prepared with 25 items based on a survey introduced by Rosenstiel and Rashid. An online site was created for the participation to the survey. A total of 322 participants responded the questionnaire. The results of the questionnaire indicated the amount of tooth preparation (42.1%) is the most frequent reason for hypersensitivity followed by water-cooling with pressure (11.2%) and provisionals (10.9%). "Very important" response for tooth reduction, time before cementation, overheating, luting agent, occlusion and provisionals were found to be of statistical significance (p⟨0.001). Comparing respondents' opinions the incidence of post-cementation sensitivity appears to be underestimated. Tooth reduction, preparation under high volume spray and quality of provisional restorations was considered to have a significant impact on the incidence of post-cementation sensitivity according to the dentists surveyed across Turkey. Respondents to the questionnaire considered the use of antimicrobial, desensitizing, resin bonding, hemostatic agents, varnishes, type of liner material, rotary instruments to be less effective for prevention of post-cementation sensitivity.