Objectives: Intraoral scanners have shown promising results when used as an adjunct or alternative to conventional impression techniques. This study compared the accuracy of digital impression taking using an intraoral scanner versus the conventional technique. Materials and Methods: In this in-vitro experimental study, a typodont molar tooth was prepared as the standard model and scanned by TRIOS intraoral scanner. Ten digital impressions were fabricated as such and intraoral scans were sent to the manufacturers. In the conventional method, using addition silicone impression material, a stone die was fabricated. Using a computer-aided design/computer-aided manufacturing scanner, the die was scanned, and the data were transferred to the software. After the fabrication of frameworks, the replica technique was used. The replicas’ thickness (indicative of the gap between the framework and the model and the accuracy of impression taking) was 12 points. The data were analyzed using student's t-test. Results: The mean thickness of replicas (gap between the internal surface of frameworks and the standard model) at the three points in the buccal, lingual, mesial, and distal sections in the digital impression technique was lower than that in the conventional technique (P<0.0001). In other words, the accuracy of impressions taken by the digital method was significantly higher than those taken by the conventional method. Conclusion: Intraoral digital scanner had significantly higher accuracy than the conventional method in all points. Thus, the digital method can be reliably used as an adjunct or alternative to the conventional method to increase the accuracy of impression taking.

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Background and Aim:The mismatch of the implant-abutment connection can produce instant stress and microleakage which result in mechanical and biological complications. This study aimed to investigate the influence of GapSeal® as a sealing material on the extent of microgap and microleakage at the external hexagon implant platform following cyclic loading. Materials and Methods: Sixteen implants with an external-hexagon connection (BioHorizons External dental implant) were employed in this in-vitro experimental study. All implant-abutment sets were assigned to two groups and were molded in acrylic resins. GapSeal® was injected into the implants in the experimental (test) group. Then, implant assemblies were tightened with the torque of 30 N/cm, and 1200,000 loading cycles with the force of 100 N and the frequency of 1 Hz were applied. Every sample was immersed in a methylene blue dye to evaluate microleakage. Microgap was measured in six regions randomly using a scanning electron microscope (SEM). The data were entered into SPSS 22 and were analyzed using t-test. Results: The mean±SD microgap was 0.87±0.35 µm and 3.43±1.61 µm in the test and control groups, respectively. Methylene blue dye was observed in all of the specimens of the control group, while no liquid was seen in the test group. A significant statistical difference was found between the groups regarding the microgap and microleakage (P<0.0001). Conclusion: Application of GapSeal® reduced the dimension of the microgap and decreased microleakage at the implant-abutment interface.

Background and Aim: Screw loosening is a common problem with both screw-retained and cemented implant restorations. It is assumed that the abutment diameter affects detorque value and screw loosening. We aimed to determine the effect of two different abutment diameters on detorque value using cyclic loading and thermocycling. Materials and Methods: This in-vitro experimental study was conducted on sixteen Morse-taper implants (4×10 mm) with two different diameters (3.9 and 5.2 mm) installed with a 25-Ncm torque (n=8). Eight screws from each group (3.9-and 5.2-mm abutments) were maintained for a month in a stable state while the rest of the screws underwent cyclic loading for 10,000 cycles with the frequency of 1 Hz and force of 75 N/cm. Then, thermocycling was done at 5-55°C. Detorque value was determined using the torque meter used for screw tightening. Removal torque values were recorded. Maximum deformation force and fracture resistance were documented. Data were analyzed according to Student's t-test using SPSS 21.0 software. Result: Detorque values were 18.25±1.91 and 21.13±1.46 Ncm with 3.9-and 5.2-mm abutments, respectively. Detorque loss value was 15.50±5.83% with 5.2-mm abutment and 27±7.63% with 3.9-mm abutment. The mean difference between the two abutment diameters was 2.87±0.85 Ncm. Significant differences were observed on torque loss with 3.9-mm-compared to 5.2-mm-diameter abutments (P=0.004). Conclusion:The results suggested that torque loss was lower with 5.2-mm abutment diameter.

ARTICLE INFO Article HistoryBackground and Aim: Reducing the number of pathogenic microorganisms can contribute to reducing the incidence and epidemiology of periodontal diseases. This study aimed to evaluate the clinical effects of Ardox-X active oxygen-containing toothpaste on periodontal indices in patients with at least 1 to 2 implants. Materials and Methods:In this crossover randomized clinical trial, 30 subjects were randomly divided into two groups (n=15). Oral hygiene instructions were delivered to all subjects before the study. Scaling and root planing (SRP) were performed for all subjects. The subjects were instructed to brush with Oral-B toothpaste and toothbrush twice daily for at least two minutes. All subjects returned 10 days later, and the plaque index (PI) and gingival bleeding index (GBI) were measured. The first group received Ardox-X, and the second group received Oral-B toothpaste. Both groups presented after 7 days, and GBI and PI were measured. SRP was performed again, and the plaque was zeroed. Both groups spent the wash-out period for 10 days. Next, the indices were measured again. The Ardox-X group received Oral-B toothpaste and vice versa. After 7 days, both groups returned, and the indices were measured again. T-test was used for statistical analysis. Results: No significant difference was observed in the PI changes between the control (0.88±0.22%) and case (0.83±0.22%) groups (P<0.6). The changes in the GBI were significantly different between the control (3.9±3.4%) and case (1.5±2%) groups (P<0.01). Conclusion:The results of this study showed that Ardox-X toothpaste performs better than the control group (Oral-B) in terms of the GBI.

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