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Background. The widespread use of dental implants as a predictable treatment choice has drawn attention to their complications as a major challenge despite their high clinical success rates. In this context, loosening of the abutment screw in posterior single crowns is the most common problem; the use of adequate preload and proper anti-rotational features at implant?abutment interface appear to be two main solutions to such a problem. The present study evaluated the effect of implant?abutment connections in four different implant systems before and after cyclic loading. Methods. Intra-Lock, Dentis, Xive, and Dio implant systems were used in this study. Each system underwent one million cycles of dynamic forces eight times with a magnitude of 110 N. For each specimen after tightening the screw with a torque of 32 Ncm, the detorque values were measured and recorded by a digital torquemeter after and before cyclic loading. Data were analyzed by Kolmogorov-Smirnov, Levene's, one-way ANOVA, and post hoc Tukey tests. Results. Initial detorque values between the study groups showed significant differences (P < 0.0001). Pairwise comparisons showed significantly lower primary detorque values in the Dentis system compared to the three other systems (P < 0.0001). After cyclic loading, significant differences were observed between the study groups (P < 0.0001). Pairwise comparisons of the groups showed significant differences between all the systems after loading. Conclusion. The type of implant?abutment connection is an essential factor influencing the amount of abutment screw loosening. [ABSTRACT FROM AUTHOR]

Background: One of the most important fundamental issues in mental health is patients' satisfaction with the beauty of their teeth and their compatibility with complete dentures. Therefore, this study investigated the role of early maladaptive schemas and body image in the level of satisfaction with complete dentures among patients referred to the dental clinic of Islamic Azad University of Tabriz, Iran, in 2021-2022. Methods: The research was a descriptive correlational study. This study's statistical population included all candidates for complete dentures referring to the dental clinic of Islamic Azad University of Tabriz in 2021-22, from among which, 168 people were selected through convenience sampling method. The research tools included the Young Schema Questionnaire-Short Form (YSQ-SF) (1988), Body Image Concern Inventory (BICI) Littleton et al. (2005), and Dental Satisfaction Questionnaire (DSQ) by Davies and Ware (1982). The collected data were analyzed using multiple regression tests in SPSS software. Results: The results showed a relationship between the components of early maladaptive schemas [failure (B = -0.225), defectiveness/shame (B = -0.279), social isolation/alienation (B = 0.278), abandonment/instability (B = 0.331), subjugation (B = -0.264), and dependence/incompetence (B = 0.246)] and the level of satisfaction with complete dentures among the patients (P < 0.05). The results also showed a significant relationship between the components of body image and the level of satisfaction with complete dentures (P < 0.05). Conclusion: It can be concluded that early maladaptive schemas and body image playa role in the satisfaction level of patients referred to the dental clinic of Islamic Azad University of Tabriz. [ABSTRACT FROM AUTHOR]

Background.: Using antibacterial agents to remove the foul odor of the implant cavity and prevent peri-implantitis can affect the detorque values and lead to the loosening of the abutment screw. This study investigated the effects of tetracycline and chlorhexidine gel on detorque values. Methods.: This in vitro study was carried out on three groups of five implants. Group G1 was the control group, and no material was applied to the implant cavity. In group G2, the implant cavity was first filled with artificial saliva and then with chlorhexidine gel. In group G3, the implant cavity was first filled with artificial saliva and then with tetracycline. The abutments were tightened with 25 N/cm2 and then loosened. Finally, the detorque values were calculated. Results.: The highest detorque values were recorded in group G1. Group G3 showed the lowest detorque values. ANOVA showed significant differences in mean detorque values (P <0.05)> Conclusion.: According to this study, applying antibacterial agents decreased the detorque values and increased the risk of screw loosening. The reduction of detorque values was more pronounced with the oil-based antibacterial agent (tetracycline). [ABSTRACT FROM AUTHOR]

Background and Aims: The root fracture resistance of endodontically treated teeth depended on the types of posts. Despite the contradictions in studies on the fracture resistance of roots implied on the use of various non metallic posts. The aim of this study was to compare the effects of two types of bonded non metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads. Materials and Methods: In this in vitro experimental study 20 recently extracted mandibular premolars were selected that they were sectioned adjacent to the CEJ and endodontically treated. The specimens were randomly divided to 2 groups (n=10). After post spaces preparation the fiber D.T Light posts (R.T.D France) and Zirconia coated fiber posts (ICE light, Danvill) were cemented in teeth canals. Composite resin (Lumiglass R.T.D, France) cores were built up. After fabricating PDL the specimens were embedded in acrylic resin and then secured in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture, at a crosshead speed of 1mm/min. Data were analyzed usinf one-way ANOVA and T test. Results: The resistance fracture mean of R.T.D group was (1083.11±156.74 (N)) and the mean of ICE light group was (865.18±106.24 (N)). The highest resistance fracture mean was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0.001). Conclusion: FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution so using fiber posts is preferred. [ABSTRACT FROM AUTHOR]