Effect of Repressing Lithium Disilicate Glass Ceramics on The Shear Bond Strength of Resin Cements.

The aim of this study was to investigate the effect of repeated pressing of lithium disilicate ceramic on the shear bond strength (SBS) of three types of resin cement. METHODOLOGY: A lithium disilicate ceramic (IPS e.max® Press) was first heat-pressed to form rectangular disk specimens. Then, leftovers were used for the second and third presses. A total of 90 specimens were prepared and separated, according to the number of pressing cycles, into three groups: 1st, 2nd, and 3rd presses (n = 30). Each group was further subdivided into three groups (n = 10) according to the type of resin cement used, as follows: Multilink N (MN), Variolink Esthetic DC (VDC), and Variolink Esthetic LC (VLC). All the cement was bonded to the ceramic surface, which was etched with hydrofluoric acid and primed with Monobond Plus. All samples were light-cured and stored for 24 h. Shear bond strength was tested on a universal testing machine. RESULTS: A two-way ANOVA was used to evaluate the influence of repeated pressing cycles and cement type as well as their interaction. The results indicated that cement type has a significant impact (p < 0.001) but not the number of pressing cycles (p = 0.970) or their interaction (p = 0.836). The Bonferroni post-hoc test showed that the SBS of MN was significantly higher than that of VDC and VLC in the first press and second press cycles, respectively. The SBS of MN was significantly higher than that of VDC and VLC cements in the third pressing cycle. There was no significant difference in the SBS between VLC and VDC in all three pressing cycles. CONCLUSION: The results of the current study did not report a detrimental effect of repeated pressing up to three cycles on the shear bond strength of the IPS e.max® Press. Multilink resin cement showed the highest SBS to IPS e.max® Press at the third pressing cycle. For all types of cement and heat pressing cycles, the majority of cement failures were adhesive. No cohesive failures occurred in any of the tested resin cements, regardless of the cement type or the number of heat pressing cycles tested.

Flexural Strength Properties of Five Different Monolithic Computer-Aided Design/Computer-Aided Manufacturing Ceramic Materials: An In Vitro Study.

Objective The purpose of this in vitro study is to compare the flexural strength and Weibull modulus of 5 different monolithic computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics. Methods A total of 50 specimens were fabricated, 10 from each of the following materials: lithium disilicate-based ceramic (IPS e.max CAD), zirconia -reinforced lithium-silicate ceramic (Vita Suprinity), leucite-based glass ceramic (IPS Empress CAD), and two zirconia-based ceramics (Zenostar and CopraSmile). The specimens were 4 mm wide, 2 mm thick, and 16 mm long. Flexural strength test was executed using a universal testing machine (Model 5980, Instron Industrial Products, Norwood, MA, USA). The two-parameter Weibull distribution function was used to analyze the variability of flexural strength values. Statistical analysis was performed on SPSS Version 23 (IBM Corp., Armonk, NY, USA) using one-way analysis of variance (ANOVA) and post-hoc Tukey's test. Results Suprinity had the highest Weibull modulus value, while Empress CAD displayed the lowest value. One-way ANOVA showed significant difference in the flexural strength between the different materials tested (p<0.05). Post-hoc analysis revealed significant differences among all the test groups in terms of flexural strength. Zenostar presented the highest mean flexural strength value (1033.90 MPa), while Empress CAD had the lowest value. Conclusion High-translucency zirconia had superior flexural properties than translucent zirconia, lithium disilicate ceramics, zirconia-reinforced lithium silicate ceramics, and leucite-based glass ceramics.

The Use of a Coded Healing Abutment in the Restoration of a Single, Immediately Placed Implant in the Esthetic Zone: A Clinical Case Report.

For several years, the implant-level impression procedure started by removal of the healing abutment, followed by connection of the impression coping to the implant. Encode Complete (Encode, Biomet 3i, Biomet 3i, Palm Beach Gardens, FL) was introduced to eliminate implant-level impressions by offering a healing abutment-level impression protocol. This report illustrated the treatment of a single tooth in the anterior esthetic zone using Encode Complete. A 23-year-old female patient reported to the prosthodontics clinic complaining of a fractured maxillary anterior tooth that was deemed nonrestorable. After immediate implant placement, soft tissue preservation and temporization of the implant, healing abutment level impression was made. The codes embedded on the occlusal surface communicated the implant depth, hex-orientation, platform diameter, and interface. The definitive Encode gold-plated titanium abutment was anatomically designed virtually with customized margin, contour, taper, and emergence profile. The milling process was initiated, and the virtual design data were sent to the Robocast Center for analog placement in the original Encode master cast. The definitive abutment was placed on the master cast using Robocast technology, followed by the fabrication of the final porcelain fused to zirconia cement-retained all ceramic crown. The abutment was secured to the implant with a Gold-Tite abutment screw, followed by the final cement-retained implant crown placement. Recall visits were obtained at 1 week, 1 month, 3 months, and 1 year after final prosthesis insertion.

Technical Accuracy of Dental Laboratories in the Quality and Shade Matching of Porcelain Fused to Metal Crowns: An In Vitro Study.

Dental laboratories (LABs) are integral to the performance of a dentist in providing successful oral rehabilitation. The aim of this study was to compare the adaptation, contour, contacts, and shade matching of different government and commercial dental LABs in the fabrication of porcelain fused to metal (PFM) crowns. Thirty-two dental LABs were selected to fabricate PFM crowns (one PFM crown each). Marginal adaptation, contour, proximal contacts, and shade matching were evaluated. Evaluation of the crowns' quality was performed following modified USPHS/FDI criteria. Visual and colorimeter assessments were employed to evaluate shade matching. Differences between groups were examined by Pearson's Chi-square and Fisher's exact test. The quality of marginal adaptation of crowns was good in 81.25%, however the quality of contours, contacts, and shade matching was compromised in 43.75%, 59.38%, and 39% of all LABs, respectively. Visual and colorimeter shade matching was acceptable in 62.5% and 80% of LABs in the cervical third and middle third regions of crowns, respectively, however in the incisal third the shade matching was unacceptable in nearly 60% of LABs. Commercial laboratories showed significantly better contours and shade matching, but not marginal adaptation. However, no significant differences were found in comparison of proximal contacts between the groups.