The purpose of this in vitro study was to evaluate the effects of four over-the-counter (OTC) whitening products on the microhardness, surface roughness, color, shear bond strength (SBS) and surface charecteristics of human enamel compared with a product used for dentist-supervised home whitening. Seventy eight enamel specimens allocated into 6 groups (n=13): 1-Opalescence PF 10% (OP) dentist prescribed home whitening product, 2-Opalescence Go prefilled tray (PT), 3-Opalescence Whitening Toothpaste (WT), 4-Listerine Healthy White whitening mouth rinse (WMR), 5-Cavex Bite&White whitening pen (WP) and 6- no treatment (Con). The microhardness (VHN), surface roughness (Ra) and color of the specimens were measured (T₀). The specimens were then subjected to whitening protocols for 14 days (T₁.) followed by artificial saliva storage for 14 days (T₂). The measurements were repeated at T₁ and T₂. The SBS test was done after the application of 35% phosphoric acid (Scotchbond Universal Etchant), followed by a universal adhesive (G-Premio Bond) and a micro hybrid/universal resin composite (Essentia) into a Teflon tube attached to the enamel surface (p<0.05). Surface morphologies of the enamel surfaces were examined by SEM. p value was set at 0.05 Application of OP, PT and WP decrased the microhardness of enamel specimens (p0.05). Ra values of enamel specimens increased with the application of OP, PT and WT (p0.05). OP, PT, WMR, and WP changed the color of the enamel(p<0.05). There were not any significant differences among the SBSs groups, apart from OP applied enamel specimens. OP showed the least SBS values (p=0.001). SEM observations revealed smooth enamel surfaces. The whitening products affected the microhardness, surface roughness, color of enamel differently. Only OP decreased the SBS of the enamel.

Background: Manual dexterity is a critical component of dental education, especially during the early stages of preclinical training. Recent advancements in simulation technology, such as virtual reality (VR) haptic simulators and layered tooth models such as Caviprep (hereafter referred to as the layered model), offer promising tools to enhance psychomotor skills. This study aimed to explore their combined and individual effects on manual skills development in novice dental students. We hypothesized that combined training with VR and layered models would result in greater improvements in manual skills than either modality alone or conventional methods. Methods: Forty-eight second-semester dental students were randomly assigned to four groups: Group 1 (the layered model + VR), Group 2 (the layered model only), Group 3 (VR only), and Group 4 (Control; extracted teeth only). All students received identical theoretical instruction and standardized demonstrations for occlusal amalgam cavity preparation. Manual dexterity was assessed using a standardized evaluation form completed by three blinded evaluators. Statistical analyses were conducted using SPSS 23.0, with significance set at p < 0.05. Results: A significant difference was observed among groups in terms of cavity depth accuracy (p = 0.001), with the control group (Group 4) performing significantly worse. There were no statistically significant differences in other evaluated parameters including cavity outline, floor smoothness, internal line angles, marginal ridge integrity, retention form, or cavity width (p > 0.05). Conclusions: The integration of VR simulators and layered models enhances depth control during cavity preparation exercises in early dental training. These tools may provide valuable benefits in developing the manual skills essential for clinical competence. Trial registration: Not applicable.

This study aimed to evaluate the repair bond strength of composite resin to two 3D-printed permanent resin materials using different universal adhesive systems—light-cure, self-cure, and dual-cure—following a standardized air abrasion. Seventy-two disc-shaped specimens (n = 12 per group) were fabricated using two different commercial 3D-printed materials: Saremco Crowntec and Bego VarseoSmile Crown Plus. After post-processing, all specimens were thermocycled for 5,000 cycles to simulate aging. The bonding surfaces were then subjected to air abrasion, followed by the application of one of three universal adhesive systems: light-cure (G-Premio Bond), self-cure (Tokuyama Universal Bond II), or dual-cure (Futurabond U). A composite resin (Filtek Z250) cylinder was then bonded and light-cured. Shear bond strength (SBS) was measured, and fracture modes were examined under a stereomicroscope. Data were analyzed using two-way analysis of variance (ANOVA) and Tukey HSD tests (p < 0.05). Self-cure universal adhesives exhibited the highest SBS values, especially in the Bego material group (19.20 ± 2.11 MPa), while the lowest bond strength was observed in the Saremco + light-cure group (14.28 ± 1.23 MPa). Both the adhesive system (p < 0.001) and material type (p = 0.002) significantly affected SBS. Failure mode analysis revealed predominantly adhesive failures in the light-cure groups, and more mixed/cohesive failures in the self-cure and dual-cure groups. Bond strength of repaired 3D-printed permanent resins is significantly influenced by the adhesive systems and material type. Self-cure universal adhesives provided the most effective bonding performance, particularly when combined with Bego VarseoSmile Crown Plus.

Objective: This study aimed to evaluate whether radiopacity differs among additively manufactured permanent resins, temporary resins, and conventional resin‐based composites at clinically relevant thicknesses. Materials and Methods: Eight dental materials were evaluated and categorized into four groups: additively manufactured permanent resins (VarseoSmile Crown Plus, Saremco Print CrownTec), additively manufactured temporary resins (Arma Resin TEMP Teeth, Alias Temp C&B), conventional self‐cure resin‐based composites (Stela Automix, Stela Capsule), and conventional light‐cure resin‐based composites (Gradia Posterior, G‐ænial Injectable). Rectangular specimens (5 × 5 mm) were fabricated at two standardized thicknesses (1 and 2 mm) ( n = 10). Extracted human tooth sections and a 21‐step aluminum wedge were used as reference standards. Radiographic images were obtained using a digital intraoral radiography system, and radiopacity values were measured in mmAl using ImageJ software. Statistical analysis was performed using Kruskal–Wallis, Dunn–Bonferroni, and Mann–Whitney U tests ( α = 0.05). Results: Significant differences in radiopacity were observed among the tested materials ( p < 0.05). Additively manufactured temporary resins demonstrated the lowest radiopacity values, whereas conventional resin‐based composites exhibited the highest radiopacity. Permanent additively manufactured resins showed intermediate radiopacity values. Increasing specimen thickness from 1 to 2 mm significantly increased radiopacity values for all materials ( p < 0.001). Several temporary additively manufactured materials presented radiopacity values lower than dentin and enamel. Conclusion: The findings suggest that radiopacity varies significantly among restorative materials and is influenced by specimen thickness. In particular, the relatively low radiopacity of some additively manufactured resins may limit their radiographic detectability, which should be considered during material selection in clinical practice. Clinical Significance: Radiopacity differences among restorative materials may influence the detection of recurrent caries and restoration margins. Lower radiopacity of some additively manufactured resins highlights the importance of careful material selection for accurate radiographic diagnosis.

To evaluate the effects of commonly consumed staining beverages on the color stability and surface roughness of two additively manufactured permanent resin