Investigation of adhesion status of Candida species to the surface of resin materials produced at different angles with additive manufacturing.

BACKGROUND: The aim of this study was to evaluate the adhesion of Candida glabrata, Candida albicans, Candida krusei, Candida parapsilosis and Candida tropicalis yeasts to disk-shaped resin materials produced from resin which used in the production of surgical guide with 0, 45 and 90-degrees printing orientations by Liquid Crystal Display additive manufacturing technology. METHODS: Disk-shaped specimens were printed with surgical guide resin using the Liquid Crystal Display production technique in 3 printing orientations (0, 45 and 90-degrees). Surface roughness and contact angle values were evaluated. Real-Time PCR analysis was performed to evaluate Candida adhesion (C. glabrata, C. albicans, C. krusei, C. parapsilosis and C. tropicalis) Field emission scanning electron microscope (FESEM) images of the materials were obtained. RESULTS: Specimens oriented at 45-degrees demonstrated higher surface roughness (P < .05) and lower contact angle values than other groups. No significant difference was found in the adhesion of C. glabrata, C. albicans, and C. parapsilosis among specimens printed at 0, 45, and 90-degrees orientations (P > .05). A higher proportion of C. krusei and C. tropicalis was found in the specimens printed at orientation degrees of 45 = 90 < 0 with statistical significance. Analyzing the adhesion of all Candida species reveals no statistical disparity among the printing orientations. CONCLUSIONS: The surface roughness, contact angle, and adhesion of certain Candida species are affected by printing orientations. Hence, careful consideration of the printing orientation is crucial for fabricating products with desirable properties. In 45-degree production, roughness increases due to the layered production forming steps, whereas in 0-degree production, certain Candida species exhibit high adhesion due to the formation of porous structures. Consequently, considering these factors, it is advisable to opt for production at 90-degrees, while also considering other anticipated characteristics.

Effect of cement type on vertical marginal discrepancy and residual excess cement in screwmentable and cementable implant-supported monolithic zirconia crowns.

The purpose of this study was to investigate the vertical marginal discrepancy (VMD) and residual excess cement (REC) of cementable and screwmentable monolithic zirconia crowns cemented with different types of cement. Abutments were attached to 40 implant analogues. Crowns were created using computer-aided design/computer-aided manufacturing technology from monolithic zirconia blocks, either with or without a screw access hole (SAC). Crowns created both ways were split into two groups and cemented with resin and zinc polycarboxylate cement under a 5-kg weight. VMD and REC values were evaluated using an X20 zoom stereomicroscope. Data were analysed using two-way ANOVA and the Bonferroni test. According to the two-way ANOVA results, REC measurements differed significantly in the crown design and cement groups. However, whilst VMD values were significantly different in both crown design groups, there was no significant difference in the cement groups. According to the Bonferroni test results, the highest REC (157.241 ± 44.29 µm) and VMD (68.052 ± 16.19 µm) values were found in the crowns without SAC and cemented with zinc polycarboxylate. Screwmentable crowns are more effective than cementable crowns in reducing REC and VMD. Whilst polycarboxylate cement reduces VMD in screwmentable crowns, resin cement is more suitable for cementable crowns.

Fracture strength of implant-supported monolithic crowns after aging in a mastication simulator.

The fracture strength of implant-supported monolithic CAD/CAM crowns under approximate clinical conditions and how their fracture strength is affected by cement type remain unclear. The present study investigated the fracture resistance of implant-supported polymer-infiltrated ceramic and zirconia-reinforced lithium silicate glass-ceramic crowns cemented with two different cement types after aging in a mastication simulator. RelyX Ultimate Clicker (3M ESPE) as adhesive resin cement, Panavia SA Cement Plus (Kuraray Noritake) as self-adhesive resin cement, and two monolithic materials (A1-T for Enamic and M1-HT for Suprinity; both Vita Zahnfabrik) were tested. Forty CAD/CAM-produced monolithic implant-supported crowns for a maxillary right second premolar were prepared, and crowns were cemented to the straight implant abutments with each cement, then subjected to dynamic load cycling (480,000 cycles) and thermocycling (about 4,000 cycles) in a mastication simulator. Crown fracture resistance was analyzed by the load-to-failure test. Crown-abutment samples were loaded until fracture. No significant difference was observed in the fracture load of the crowns among the groups. The results suggest that both monolithic restoration materials could be an alternative for implant-supported cement-retained restorations, regardless of cement type.

Effect of Vent Hole and Cement Type on Fracture Resistance of CAD-CAM Monolithic Zirconia Crowns.

PURPOSE: To assess the fracture resistance of monolithic zirconia crowns cemented with different types of cement on cement-retained implant abutments. MATERIALS AND METHODS: Forty implant analogs were positioned in acrylic resin blocks, and cement-retained straight implant abutments were fastened to the analogs. Crowns were designed with/without occlusal vent holes and produced from monolithic zirconia blocks by the CAD-CAM technique. The two crown types were divided into two groups and cemented with resin and zinc-polycarboxylate cement under 5 kg weight. A universal testing machine applied compressive forces to the crowns until fracture. Fracture resistance values were analyzed using two-way ANOVA and the independent samples t-test with statistical significance set at p < 0.05. RESULTS: According to the two-way ANOVA results, although the crown design did not have a significant effect on fracture resistance (1417.65 ± 337.39 N, 1565.16 ± 517.12 N; crowns with and without vent holes, respectively), the main effect of the cement variable on the fracture resistance was significant. Zinc-polycarboxylate cement (1680.1 ± 375.23 N) showed higher fracture resistance than resin cement (1302.71 ± 420.64 N) in the crowns designed with vent holes (p < 0.005). CONCLUSION: The use of cement-retained implant-supported monolithic zirconia crowns with an occlusal vent hole is safe, and zinc-polycarboxylate cement use may be an appropriate choice for cementation of these crowns.

Removal of lithium disilicate veneers with Er,Cr:YSGGL laser: now? Or after ageing?

This study was purposed to assess the impact of ageing and resin cements polymerized with different modes on the removal time of lithium disilicate (LiSi) ceramics using Er,Cr:YSGG laser. Ninety LiSi slabs (6 × 6 × 1 mm) were cemented to freshly extracted bovine teeth using cements polymerized with different modes (light-curing (LC), dual-curing (DC), self-curing (SC)). The specimens were divided into subgroups according to ageing conditions (no thermal cycling, 5000 or 30,000 thermal cycling). After that, Er,Cr:YSGG laser was applied until LiSi slabs were debonded; the removal time was recorded. Vickers microhardness test, SEM and EDS analyses were performed for specimens with the longest exposure time to laser application in the groups. One uncemented sample was also used as a control. Data were analyzed with two-way ANOVA and Tukey post hoc test. Ageing and cement polymerization mode significantly affected the removal time of LiSi specimens. The removal time for the self-curing resin cement group (22.67 ± 12.68 s) was significantly longer than for cements polymerized with other methods (LC = 10.833 ± 7.28 s, DC = 12.0 ± 7.96 s). Removal time was significantly reduced after ageing in all polymerization modes; however, there were no significant differences between 5000 (11.83 ± 7.52 s) and 30,000 (11.83 ± 7.26 s) thermal cycling groups. Self-curing resin cements had prolonged the laser-aided removal time for LiSi ceramics. It can be concluded that Er,Cr:YSGG laser-aided removal of LiSi veneers after clinical use can be done more faster than its immediate removal.