Objectives: This study aimed to assess the effect of three commonly consumed beverages on surface roughness of polished and glazed zirconia-reinforced lithium silicate (ZLS) glass ceramics. Materials and Methods: In this experimental study, 104 rectangular specimens were cut from Vita Suprinity blocks with 2 mm thickness. After ultrasonic cleaning and firing of the specimens, they were finished and polished in two groups. Specimens in the first group were polished using a 2-step polishing kit while the second group specimens were glazed and heated in a porcelain firing oven according to the manufacturer’s instructions. Baseline surface roughness was measured using a profilometer. Specimens in each group were then randomly divided into 4 subgroups (n=13) for immersion in artificial saliva (control group), cola, orange juice and black tea. Surface roughness was measured again and data were analyzed using two-way ANOVA. Results: The highest and the lowest mean Ra were found in orange juice and saliva subgroups, respectively in both glazed and polished groups. The Ra values of both polished and glazed groups significantly increased after immersion in orange juice and cola (P<0.05). The polished surfaces showed insignificantly higher surface roughness compared with glazed surfaces (P>0.05). Conclusion: Orange juice and cola significantly increased the surface roughness of both polished and glazed ZLS ceramics. Type of surface finishing (polishing versus glazing) had no significant effect on the surface roughness of specimens following immersion in different beverages.

Objectives: This study aimed to compare the marginal fit of temporary restorations fabricated by the conventional chairside method, 3D printing, and milling. Materials and Methods: In this in vitro, experimental study, 14 temporary restorations were conventionally fabricated over an implant abutment and analog that had been mounted in a phantom model at the site of canine tooth, using auto-polymerizing acrylic resin and putty index. In digital manufacturing, the original model was scanned, and the final restoration was designed. Fourteen temporary restorations were milled out of polymethyl methacrylate (PMMA) blocks, and 14 others were printed by a 3D printer. Temporary crowns were placed on the abutment, and images were obtained from specific areas under a stereomicroscope at x100 magnification to measure the amount of marginal gap. Data were analyzed using one-way ANOVA and Tukey’s test (α=0.05). Results: The mean marginal gap values for the temporary crowns in the 3D printing, milling, and chairside groups were 91.40, 75.28 and 51.23 µm, respectively. The crowns that were conventionally fabricated chairside exhibited the lowest marginal gap, and the difference in this respect was significant among the three groups (P<0.05). Conclusion: Temporary crowns fabricated by the chairside method showed significantly smaller marginal gap; however, the marginal gap of all three groups was within the clinically acceptable range.

Background: Dental scanners play a critical role in computer-aided design/computer-aided manufacturing technology. This study aimed to compare the accuracy (precision and trueness) of eight dental scanners for dental bridge scanning. Materials and Methods: In this in-vitro experimental study, a typodont model with a missing maxillary right first molar was prepared for a 3-unit fixed partial denture. Each scanner (Sirona inEos inLab, Sirona X5, Dentium, Imes icore 350I I3D, Amann Girrbach map 100, 3Shape D100, 3Shape E3) performed seven scans of the typodont, and the data were analyzed using 3D-Tool software. The abutment length, abutment width, arch length, and interdental distance were measured. To assess the accuracy of each scanner, trueness was evaluated by superimposing the scanned data on true values obtained by the 3shape Triosscanner as the reference. Precision was evaluated by superimposing a pair of data sets obtained from the same scanner. Precision and trueness of the scanners were compared using the one-way ANOVA followed by the post-hoc Tukey's HSD test and one-sample t-test (P<0.05 was considerer significant). Results: The precision of scanners ranged from 14 μm (3Shape Trios) to 45 μm (Imes icore 350i), whereas the trueness ranged from 38 μm (3Shape d700) to 71 μm (Sirona X5). Conclusion: The reported trueness values for 3Shape Trios, Sirona inEos inLab, Sirona x5, Dentium, Imes icore350i, Amann Girrbach, 3Shape d700, and 3Shape e3 were 63, 45, 71, 67, 70, 53, 38, and 42 μm, respectively, whereas the precision values were 14, 29, 44, 34, 45, 44, 30 and 28 μm, respectively.

Background: in oral and maxillofacial fractures, plates and screws routinely fix fragments until the completion of healing process, which has its own complications in some critical fractures. To overcome this drawbacks bone adhesives are developed for the immobilization of fractured bones. Objective: In this in-vitro study we compared the bond strength obtained by immobilization of the bone fragments using plates and screw and new adhesive containing BTDMA monomer. Materials and methods: In this experimental in-vitro trial, bone fractures were simulated in bovine’s mandibular bone using an electrical saw. The bone fragments were randomly allocated in different groups and were immobilized with either plate and screws and adhesive containing 0,10, 15% BTDMA. After 24 hours tensile bond strength was calculated using universal testing machine. One-way ANOVA and Tukey post hoe test were used for statistical analysis. Results: Mean (± standard deviation) of tensile bond strength of bone fixation using adhesive containing 15% (W/W) BTDMA monomer were 176.0 (±18.89) N. These values were 149.1 (±23.88) N for adhesive containing 10% BTDMA; 102(±17.99) N for the base adhesive and 278.9 (±24.12) N for the screw and plate technique. Significant differences were found regarding bond strength of bone fixation in 4 groups using bone adhesives or plate technique (P<0.001). The highest bond strength was recorded for the plate group and the least was related to the base adhesive. Significant differences existed between all bone adhesives as declared by paired comparison (p<0.05). Conclusion: Despite the lower bond strength in adhesive groups in comparison with screw and plate, with regards to possible complications of screw and plate technique, it seems bone adhesives containing BTDMA monomer can be used for bone fragment fixation. However, bond strength is just one of the numerous properties that an adhesive should have and more studies must be done on these kinds of adhesives.