The purpose of this in vitro study is to compare the roughness and gloss of four resin-modified CAD/CAM ceramics after different surface treatments. Forty-eight specimens (1.20 × 12 mm²) were prepared from Lava Ultimate (LU), Vita Enamic (VE), Cerasmart (CS), and Crystal Ultra (CU) CAD/CAM ceramics. The prepared specimens were polished with silicon carbide paper before being roughened with a 30 µm grit diamond bur. Each material was allocated into four groups: control (no treatment), Luster Meisinger polishing (MP), Optiglaze (OG), or Meisinger polishing, followed by a final polishing with Shofu Direct Dia Paste (MP+PP). The roughness and gloss were measured after the surface treatment using a profilometer and gloss meter, respectively. Scanning electron microscopy micrographs were obtained to analyze the surface characteristics. Statistical analysis was performed using a multivariate analysis of variance (MANOVA), one-way ANOVA, and Dunnett’s post hoc test (α = 0.05). The surface treatments significantly affected the surface roughness and gloss of the tested materials (p < 0.05). All the tested resin-modified CAD/CAM ceramics demonstrated a lower surface roughness and higher gloss after glazing using OG, followed by MP+PP and MP. The highest and lowest Ra were presented by the control VE (0.63 ± 0.23 µm) and glazed LU specimens (0.04 ± 0.01 µm), respectively. The highest and lowest GU were presented by the glazed LU (90.48 ± 4.69 GU) and the control VE specimens (23.32 ± 2.41 GU), respectively. After clinical adjustment, finishing, and polishing, the restoration is essential to obtain a restorative surface with lower roughness and the highest gloss. Surface glazing using Optiglaze exhibited the smoothest and glossiest surface of all the tested resin-modified ceramics.

The aim of this study was to compare the surface roughness and gloss of polymer-infiltrated ceramics after simulated in vitro toothbrushing in different storage mediums. Four polymer- infiltrated ceramics were evaluated, Lava ultimate (LU), Vita enamic (EN), Shofu (SH), and Crystal ultra (CU). The control group was a feldspathic ceramic, Vita Mark II (VM). One hundred and twenty specimens (12 × 14 × 2.5 mm) were prepared using a precision saw. For each material (n = 24), the specimens were allocated into two groups, polished and stained. The specimens of each group were stored (for 7 days) in either citric acid (0.2N) or distilled water. Data for surface gloss (ΔE*_SCE-SCI) and roughness (Ra) were evaluated before (baseline) and after simulated toothbrushing. For toothbrushing simulation, a toothpaste slurry containing a toothpaste of 100 relative dentin abrasion (RDA) and 0.3 ml distilled water was used for 3650 cycles (7300 strokes) for each specimen. Data were analyzed using t-test and ANOVA. A p-value of ≤ to 0.05 was considered significant. The highest mean value of surface gloss was identified in CU (stained—water) (4.3 (0.47)) (ΔE*) and EN (stained—acid) (4.3 (1.00)) (ΔE*) specimens, whereas the lowest mean value was shown by SH (stained—acid) (2.04 (0.42)) (ΔE*) samples. The highest mean value of surface roughness was observed in SH (0.40 (0.99)) Ra (stained—acid) whereas the lowest in VM (0.13 (0.039)) Ra (polished— water). A significant difference (p < 0.05) was observed in surface roughness and gloss between the materials with simulated toothbrushing, except in VM and LU, respectively. Therefore, it can be concluded that simulated toothbrushing impacts on surface roughness and gloss, irrespective of the storage medium.

This study aimed to measure the effect of storage environment on the hardness, surface roughness and wear ability of CAD/CAM resin-matrix ceramics. A total of 200 rectangular-shaped specimens were obtained by sectioning 5 CAD/CAM blocks; Crystal Ultra (CU), Vita Enamic (VE), Lava Ultimate (LU), Cerasmart (CS) and Vita blocks Mark II (MII). Microhardness and surface roughness were measured at baseline and after 7 days of immersion either in saliva or cola (n = 10). The wear ability of the CAD/CAM materials against steatite-ceramics antagonist was determined using a chewing simulator. The data were statistically analyzed using factorial ANOVA followed by post hoc Bonferroni multiple comparison tests (p < 0.05). The independent factors significantly influenced the microhardness and surface roughness (p < 0.05). The highest VHN was observed in MII at baseline (586.97 ± 13.95), while CU showed the lowest VHN after 7 days of immersion in cola (68.3 ± 1.89). On the contrary, the highest Ra was observed after 120,000 chewing cycles for the VE specimens (1.09 ± 0.43 µm) immersed in cola, while LU showed the lowest Ra at baseline (0.07 ± 0.01 µm). The highest % mass loss of the antagonist was observed with MII immersed in cola (1.801%), while CS demonstrated the lowest % mass loss of 0.004% and 0.007% in AS and cola, respectively. This study confirms that the surface properties of tested CAD/CAM materials are susceptible to degradation in an acidic environment except for hardness and wear of CS material.

Labban N, et al. J Adv Prosthodont. 2021 Feb;13(1):1-11. https://doi.org/10.4047/jap.2021.13.1.1

The cyclic fatigue resistance of ProTaper Universal (PTU), ProTaper Gold (PTG), and ProTaper Next (PTN) nickel titanium (NiTi) rotary files was evaluated. Fifteen instruments of each type were selected, totaling 195 files. The instruments were rotated until fracture in an artificial canal with dimensions corresponding to the dimensions of each instrument tested: +0.1 mm in width and 0.2 mm in depth, an angle of curvature of 45°, a radius of curvature of 5 mm, and a center of curvature 5 mm from the instrument tip. The fracture surfaces of three representative samples of each subgroup were examined using scanning electron microscopy (SEM). Time to fracture was analyzed via analysis of variance and Tukey’s tests (P < 0.05). PTG F1 and F2 had significantly higher resistance than PTU F1 and PTN X2, and PTU F2 and PTN X3, respectively. PTN X2 showed a significantly higher resistance than PTU F1. The PTG series demonstrated superior cyclic fatigue (CF) behavior compared with that of the PTU and PTN series.

To assess the current status of digital technology (DT) implementation in prosthodontics post-graduate (PG) programs in Saudi Arabian dental institutions. A 19-item survey was created using Google forms and the link was emailed to the 29 prosthodontics PG program directors (advanced clinical training and joint program) in Saudi Arabia. The questionnaire contained five Sect. 1) didactic training and DT usage in PG preclinical, clinical and laboratory training, 2) incorporation of DT in PG program, 3) utilization of DT and the types of cases treated by PG students during their course, 4) information on the faculties involved in prosthodontics PG education, and 5) potential challenges encountered and program directors’ satisfaction of the PG program. Descriptive statistics was used to present the frequencies and proportions, and Chi square inferential test was used to compare the participants’ response based on the type of PG programs (α = 0.05). Only 28 program directors responded to the survey, yielding a 95.5% response rate. Among the program directors, 24 (85.7%) and 4 (14.3%) directors supervised the advanced clinical training and joint programs, respectively. Among the DT, CAD/CAM was the most used technology (50–80%), followed by intra-oral scanning (28–96%). Digital technology implementation was largely limited by lack of resources or equipment (67%), cost (53%) and scarcity of PG teaching staff (46%). A significant difference was observed between the programs regarding the mandatory use of DT for their cases (p = 0.03). This multi-institutional survey of program directors revealed that DT is continuously implemented in the last few years. Saudi dental institutions must prioritize implementing and utilizing DT in PG training to graduate competent prosthodontists in this fast-paced digital era. While DT is pivotal in dental education, its implementation is limited in many institutions due to resources or equipment, cost, and lack of trained faculty.