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Purpose: To evaluate the peri-implant parameters of immediately placed and loaded mandibular overdentures over a 5-year follow-up period. Materials and Methods: All subjects who had been advised and planned for two-implant mandibular overdenture treatment were included in this study. The peri-implant parameters –including plaque index (PI), bleeding index (BI) and peri-implant pocket depth (PIPD) as well as marginal bone loss (MBL) – were assessed. In addition, prosthodontic parameters including abutment-, implant- and denture-related complications were assessed. Patients were evaluated at follow-up visits, scheduled at 1, 12, 24, 36, 48, and 60 months. The data distribution was analysed with the Shapiro-Wilk test. Data within follow-up categories were compared using ANOVA and the Tukey-Kramer test. A p-value < 0.05 was considered statistically significant. Results: Among the 32 participants, 19 were males and 13 were females, with a mean age of 60.5 ± 7.33. The mean plaque index (PI), bleeding index (BI) and peri-implant pocket depth (PIPD) varied over time. However, no statistically significant difference was observed in the plaque index, bleeding index and peri-implant pocket depth over time (p > 0.05). The mean value at baseline was found to be -0.9 ± 0.3. The values increased over time, with the highest value observed at 60 months 2.6 ± 0.7, which was statistically significant (p < 0.001). Conclusion: Immediately placed and loaded mandibular implant overdentures using two un-splinted implants with locator attachments showed acceptable PI, BI and PIPD at the 5-year follow-up. Statistically significantly greater marginal bone loss was observed from baseline to follow-up, but it was within acceptable limits. A moderate number of restorative and abutment complications were observed during the follow-up of IODs. [ABSTRACT FROM AUTHOR]

The aim of the study is to assess the impact of mechanical surface treatments on the shear bond strength (SBS) of orthodontic brackets bonded to three-dimensional (3D) printed and milled CAD/CAM provisional materials. Sixty cylindrical samples were fabricated for each provisional material. Samples were treated with one of the following surface treatments: aluminum oxide airborne particle abrasion, diamond bur rotary instrument roughening, and phosphoric acid etching (control). Stainless steel brackets were bonded to the samples, and then SBS was tested using a universal testing machine. SEM and digital microscopy were utilized to examine the bonding interface and the failure modes. Two-way ANOVA, one-way ANOVA, Tukey's HSD, and independent sample t-tests were used for statistical analysis. Results revealed significant differences in SBS between 3D printed and milled samples and significant differences in SBS among most surface treatments, with rotary instrument roughening resulting in the highest values for 3D printed, while airborne particle abrasion leading for milled samples. Digital microscopy indicated that more adhesive remained on 3D-printed samples. SEM analysis revealed varying surface roughness across treatments. Based on the findings of this study, it can be concluded that different surface treatments improve the bonding of orthodontic brackets to provisional crowns. [ABSTRACT FROM AUTHOR]

Background/Objectives: The purpose of this in vitro study was to evaluate and compare the internal adaptation and cement film thickness of cast-gold custom post and core (CPC), three-dimensionally (3D)-printed titanium (Ti) CPC, and milled Ti CPC. Methods: Forty-eight 3D printed resin models, simulating a tooth prepared to receive a CPC, were fabricated. Models were randomly assigned to one of three groups (n = 16 per group): (A) cast-gold CPC (control group), (B) 3D-printed Ti CPC, and (C) milled Ti CPC. Following the manufacturing of CPCs, each CPC was cemented using dual-cure polymerizing resin cement. Then, each model/post-and-core assembly was sectioned at the coronal, middle, and apical thirds of the post at a specific point. Each section was photographed using a microscope in a standardized setting (25×). The pixel count for cement surface area was calculated for each image using Adobe Photoshop software. Descriptive statistics of the mean and standard deviation of the cement film thickness around posts were calculated. Kruskal–Wallis and Dwass–Steel–Critchlow–Fligner tests were used for statistical analysis, with a significance level of α = 0.05. Results: Pairwise comparisons in the coronal section revealed a statistically significant difference (p < 0.05) between groups A and B and groups B and C. In the middle section, there was a statistically significant difference (p < 0.05) between groups A and B only. In the apical section, there was a statistically significant difference (p < 0.05) between all groups. Conclusions: Within the limitation of the present study, neither 3D printed nor milled Ti CPC could achieve comparable cement film thickness to cast-gold CPC in all three sections. Cast-gold CPC cement film thickness was found to be more reduced and consistent, thus having superior internal adaptation to 3D-printed and milled Ti CPCs. [ABSTRACT FROM AUTHOR]

The current study aimed to compare the mechanical properties of CAD/CAM fabricated hybrid ceramic restorative materials. The current study assessed the mechanical properties of additively and subtractively manufactured CAD/CAM fabricated hybrid ceramic by conducting flexure strength test, compressive strength test, and Vickers hardness test. Flexural samples were subjected to a three-point bending test using a universal testing machine until the samples showed fracture. Moreover, samples for the compressive strength test were subjected to compression tests using a universal testing machine until samples were fractured. Samples for the Vickers hardness was tested using the Vickers hardness testing machine to determine the sample's hardness values. There were significant differences (p = 0.0001) were observed among the additive and subtractive groups in terms of flexure strength and compressive strength test. Regarding the Vickers hardness test, significant differences (p = 0.0001) were observed between the polished and unpolished groups in additive manufacturing. However, no significant (p = 0.681) differences were observed in the subtractive manufacturing technique. The subtractive group achieved ISO specifications in terms of flexural strength and was superior to additive groups in hardness while exhibiting lower performance in compressive strength. Moreover, printing orientation had a significant influence on the performance of additive groups. Flexural strength and hardness were improved when the printing orientation was in alignment with the direction of load (90°) while compressive strength was improved when the printing orientation was perpendicular to the direction of load (0°). [ABSTRACT FROM AUTHOR]

Purpose: The effect of a silicone-based sealer on fiber post retention has not been the subject of research and remains unclear. This study aimed to evaluate and compare the impact of a silicone-based sealer and an epoxy resin sealer on fiber post retention., Material and Methods: Forty extracted human mandibular premolars that were caries-free, single-rooted, and possessed straight single canals were the specimens of the present study. Teeth were randomly divided into two groups (n = 20 each). All specimens were prepared using gutta-percha. The sealer used in the first group was Guttaflow 2, while AH26 was used in the second group. Post spaces were prepared immediately after obturation for each specimen. Prefabricated fiber posts were luted in both groups using a self-adhesive resin cement (RelyX-U200). Each specimen was vertically secured using a universal testing machine (Instron Corp.) and a constant pull-out force at a loading rate of 0.5 mm/min was applied until the point of dislodgement. Data were analyzed using t-tests., Results: A significant difference was found between the mean of maximum loads of the silicone-based sealer and epoxy resin sealer groups (p = 0.0001). The mean maximum load for the epoxy resin sealer group was 194.62 N, while that for the silicone-based sealer group was 111.64 N., Conclusion: Fiber post retention in teeth obturated using silicone-based sealer was inferior to that in teeth obturated with epoxy resin sealer. Therefore, the sealer used during obturation can significantly affect fiber post retention., (© 2023 by the American College of Prosthodontists.)