To evaluate the colour stability and surface roughness of 3 different CAD/CAM materials (IPS e.max, Vita Enamic, and PEEK) after immersion in two beverage solutions (Coffee, Coca-Cola). Methodology: Samples from a lithium disilicate glass-ceramic (IPS e.max CAD), a hybrid ceramic (Vita Enamic), and PEEK (BioHPP) were evaluated for colour change and surface roughness under immersion in two beverage solutions (Coffee, Coca-Cola). A total of 30 samples were prepared n=10 each. Spectrophotometer analysis was used to measure colour parameters (a*, b*, c*) before and after the immersion cycles and the average colour difference (Delta E*) was calculated after immersion in different beverages. Surface roughness was measured with a non-contact profilometer. Statistical analysis was performed using the Kruskal Wallis test with the Mann Whitney test as posthoc. The significance level was set at P ≤ 0.05. Results: There was a significant colour change between the materials. Vita Enamic and PEEK samples showed the highest colour change value with coffee immersion (ΔE) (7.96± 3.86), (6.07± 3.12) respectively. While IPS e.max. CAD revealed the lowest colour change value (2.62 ±1.54) following coffee immersion with a statistically significant difference in between (P< 0.011). After immersion in different media, there was a significant difference in surface roughness between the materials (p< 0.05). Conclusion: Vita Enamic and PEEK showed colour change beyond the clinically acceptable level, while IPS e.max CAD was the most stable material in colour and surface roughness.

No abstract

No abstract

Aim: The aim of this in-vitro study was to evaluate the effect of abutment tooth geometry on the accuracy of two intraoral scanners. Methodology: The study was conducted using maxillary typodont. Six full coverage crown preparations were performed on central incisors, 1st premolars and 1st molars with known axial wall taper (6o and 12o) using dental parallelometer. Highly accurate table-top scanner (Identica T500) was used to obtain reference scan to the typodont. Two intraoral scanners (3shape Trios 3 and Medit i500) scanned the typodont 13 times to obtain total samples of prepared teeth (n=39) for each group. All scans were exported in standard tessellation language (STL) format. Measurements of trueness and precision for respective tooth preparation were evaluated using reverse engineering software for superimposition and deviation analysis.  Comparison between groups was performed by using One-Way ANOVA test followed by Tukey`s Post Hoc test and Independent t- test. Results: Statistical analysis showed no significant difference in trueness between the two intraoral scanners. Trueness values were 39.9 µm and 41 µm for Trios 3 and Medit i500. Trios 3 was significantly more precise (23.6 µm) compared to Medit i500 (34.7 µm).

Statement of the problem: Preservation of the cingulum in anterior teeth have been recommended however with recent ceramic restorations its contribution to internal adaptation and fatigue resistance needs further study. Objective: The purpose of this in-vitro study was to evaluate the internal fit, marginal integrity and the fatigue resistance of E-max CAD crowns on two preparation designs for maxillary anterior teeth. Material and methods: Twenty defect free human maxillary central incisors were prepared to receive E-max CAD ceramic crowns. 10 samples were prepared with parallel labiolingual wall (anatomic) group A and 10 samples were prepared with elimination of the cingulum (non-anatomic) group B. Scanning was done using powder free Identica hybrid scanner (Medit 02855] 23, Inchonro 22-gil, Seongbuk-gu, Seoul, Korea), designing was made by Exocad software version 2016 (Exocad Gmbh Julius-Reiber-Strabe 37, 64293 Darmstadt, Germany) then the restoration was milled by Roland DWX-510 milling machine (15363 barranca Parkway Irvine, California 92618) from E-max CAD blocks (LT) (Ivoclar Vivadent AG, 9494 Schaan, Princiability of Liechtenstein). Internal fit, marginal adaptation was measured before cementation using replica technique on prepared tooth using stereomicroscope. Duplication of the preparation was made in order to get epoxy resin dies for crown cementation, then restorations were cemented on the corresponding epoxy resin die and marginal adaptation was reevaluated under stereomicroscope. Specimens were then subjected to thermomechanical aging using four stations multimodal ROBOTA chewing simulator (Model ACH-09075DC-T, AD-TECH TECHNOLOGY CO., LTD., GERMANY) followed by fatigue resistance measurement using universal testing machine (Model 3345; Instron Industrial Products, Norwood, MA, USA). Results: It was found that group B recorded statistically significant (P<0.05) higher marginal gap mean value (29.7±3.97 µm) than group A (25.39±3.24 µm) as indicated by unpaired t-test (3020)