In recent years, laminate veneer restorations should be considered as a minimally invasive treatment option for several aesthetic reasons. This study compared direct composite veneers’ and indirect ceramic laminate veneers’ longevity in multiple diastema closures. A total of 28 patients with a mean age of 26 years received 60 direct resin composite (Estelite Asteria; n = 14) and 60 indirect ceramic veneers (IPS e.max Press; n = 14) on the maxillary anterior teeth with diastema closure. Veneers were evaluated at baseline and thereafter every 6 months for up to 2 years using USPHS criteria. Data were analyzed with Fisher’s exact and chi-squared tests, while Kaplan–Meier curve was used to assess time to event. In total, three failures were observed in the form of debonding (n = 1) and fracture (n = 2) in the indirect ceramic veneers. No significant difference was observed between the survival rates of composite and ceramic veneers (Estelite Asteria: 93.4%, IPS e.max Press: 95%; p > 0.05). The overall survival rate was 94.2% (Kaplan–Meier). Staining (n = 11) and roughness (n = 14) were frequently observed for the resin composite veneers up to the final recall. Thereby, the preliminary results from this clinical trial comparing two veneer materials indicated that their survival rates were statistically similar. However, surface quality changes were more frequent in the composite veneer material.

The oral environment significantly influences the esthetic appearance of CAD/CAM provisional restorative materials. Therefore, a veneering layer is required. Bonding veneering resin composites to these materials presents challenges, particularly under conditions of thermal aging. This study evaluated the impact of various surface treatments and thermal aging on the bond strength between veneering resin and CAD/CAM provisional materials. Fifty disk-shaped specimens of each CAD/CAM material (CAD-Temp, Everest C-Temp, and PEEK), measuring 10 mm in diameter and 3 mm in height, were fabricated. After being ultrasonically cleaned, specimens were embedded in acrylic resin blocks, leaving one surface exposed for surface treatments. Specimens were assigned to five groups at random. Group C: no surface treatments applied; DB: mechanically roughened with a diamond bur; DB + TC: DB group subjected to 5000 cycles of thermocycling; SB: treated with aluminum oxide airborne abrasion; SB + TC: SB group subjected to 5000 cycles of thermocycling. After the surface treatments, the primer and resin veneering composite were applied to the specimens. The shear bond strength (SBS) was calculated using a universal testing machine and the mode of failure was evaluated with an optical stereomicroscope with 40× magnification. Scanning electron microscopy evaluation was conducted to examine the surface topography of the materials’ surfaces after surface treatments. C-Temp in the SB group exhibited the highest SBS values (20.38 ± 1.04 MPa), while CAD-Temp in the C group showed the lowest values (4.60 ± 0.54 MPa). PEEK recorded significantly higher SBS values in DB + TC and SB + TC groups (9.26 ± 1.07 and 12.92 ± 0.97 MPa, respectively) compared to CAD-Temp in DB + TC and SB + TC groups (6.04 ± 0.76 and 8.82 ± 0.86 MPa, respectively). C-Temp exhibited higher SBS without surface treatment (13.11± 0.55 MPa), whereas PEEK showed higher SBS after diamond bur roughening and air particle abrasion (10.87 ± 1.02 MPa, and 14.37 ± 0.98 MPa, respectively). The thermocycling significantly reduced SBS values for C-Temp in the DB + TC and SB + TC groups (11.18 ± 0.92, 15.56 ± 0.87 MPa, respectively) and CAD-Temp in the DB + TC and SB + TC (6.04 ± 0.76 MPa and 8.82 ± 0.86 MPa, respectively). Conversely, the thermocycling had no significant effect on SBS values for PEEK material in the air particle abrasion group (12.92 ± 0.97 MPa).

Background: There are very few studies in literature concerning the bonding between 3D-printed resin posts and the core build-up material. This study aimed to evaluate and compare the adhesion of 3D-printed and milled resin posts to composite resin core build-up material following different surface treatments. Methods: Three types of resin posts were utilized in this study: ready-made glass-reinforced fiber post (3M ESPE, Germany), milled PEEK POST (Bredent, Germany), and 3D-printed resin post (CROWNTEC, Saremco Dental AG, Switzerland). Each type of post was categorized into three groups based on surface treatments: C: untreated surfaces; SB: Air abrasion with 50 μm aluminum oxide particles was applied to the posts’ surfaces.; HO: the posts’ surfaces were immersed in 30% H₂O₂ for 5 min. A dual-cured composite resin (Grandio DC; VOCO) was utilized for core build-up in each group to evaluate adhesion through the push-out bond strength test. The modes of failure were analyzed, and the surface morphology of the post was characterized using SEM. Data were analyzed using a two-way analysis of variance (ANOVA) along with Tukey’s test. Results: The two-way ANOVA indicated a significant effect for surface treatment (F = 583.54, p < 001), post type (F = 79.96, p < 0.001), and their interactions (F = 265.74, p < 0.001). Regarding 3D-printed resin post, 30% H₂O₂ for 5 min recorded the highest statistically significant bond strength value (13.11 ± 1.61) compared to other groups. Regarding the milled PEEK post, the air particle abrasion recorded the highest statistically significant value (23.88 ± 1.66) compared to other groups. Adhesive failure was the predominant failure type, with an occurrence rate of 70.35%. Mixed failure was noted in 24.07% of the cases, with a significant prevalence in the PEEK post within the air particle abrasion group (58.3%). Cohesive failure was noted in 5.54% of cases, with a significant prevalence in the air particle abrasion group, occurring at rates of 16.6% in the resin fiber post group and 33.3% in PEEK posts. Conclusions: Air particle abrasion significantly improved the push-out bond strength of milled PEEK posts, but it did not have a similar effect on the 3D-printed resin posts. The application of 30% H₂O₂ for 5 min to 3D-printed resin post enhanced the adhesion to core build-up material. The manufacturing method of posts, the surface treatments utilized, and their interactions affect the interfacial bond strength between posts and the composite resin core build-up material.

Novel dentin bonding pretreatment using copper sulfate (CuSO₄) and dipotassium hydrogen phosphate (K₂HPO₄) may create a more hydrophobic environment for dentin bonding. Thus, this study aims to investigate the impact of a CuSO₄ + K₂HPO₄ pretreatment on dentin μTBS when bonded with a universal adhesive to conventional and CAD/CAM resin composites. Eighty recently extracted human molars (n = 80) were chosen and placed in transparent acrylic blocks to expose the crowns entirely. Nano-filled resin composite and CAD/CAM resin blocks were selected. Based on the dentin pretreatment, type of resin composite, and adhesion strategy, the teeth were randomly allocated into eight equal groups (n = 10). The microtensile bond strength (μTBS) and fracture mode were determined. A three-way analysis of variance (ANOVA) was used to analyze the μTBS data, followed by Tukey’s post hoc test. The μTBS values were not significantly affected by either the resin composite type (p > 0.05) or the adhesive strategy (p > 0.05) according to the three-way ANOVA results. Conversely, significant differences were detected between no dentin pretreatment (24.20 ± 4.54 MPa) and CuSO₄ + K₂HPO₄ pretreatment (33.66 ± 5.22 MPa) using an etch-and-rinse adhesive strategy for nano-filled composites (p < 0.001). Additionally, significant differences were detected between no dentin pretreatment (24.71 ± 4.33 MPa) and CuSO₄ + K₂HPO₄ pretreatment (32.49 ± 4.92 MPa) using an etch-and-rinse adhesive strategy for CAD/CAM resin blocks (p < 0.001). Moreover, significant differences were detected between no dentin pretreatment (21.20 ± 3.40 MPa) and CuSO₄ + K₂HPO₄ pretreatment (30.31 ± 3.87 MPa) using a self-etching adhesive strategy for nano-filled composites (p < 0.001). Also, significant differences were detected between no dentin pretreatment (23.89 ± 3.89 MPa) and CuSO₄ + K₂HPO₄ pretreatment (31.22 ± 4.71 MPa) using a self-etching adhesive strategy for CAD/CAM resin blocks (p < 0.001). In conclusion, dentin μTBS was enhanced by a copper-based treatment when used with nano-filled and CAD/CAM resin blocks.

Substantial tooth bonding is the defining characteristic of effective minimally invasive all-ceramic restorations. Natural and synthetic cross-linkers that could strengthen the bonding quality are currently drawing enormous interest. Thus, this study aimed to assess the microtensile bond strength and nanoleakage of computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated ceramics to pretreated dentin with chlorhexidine or Salvadora persica extract, compared to no pretreatment, after thermomechanical cyclic loading. Consequently, forty-five extracted third-molar teeth (n = 45) were utilized to obtain mid-coronal dentin and assigned into three groups (n = 15) in accordance with dentin pretreatment; (group I: no dentin pretreatment (control), group II: 2% chlorhexidine, and group III: Salvadora persica extract pretreatments). Ceramic onlays were milled from lithium disilicate IPS e.max CAD/CAM blocks and cemented to prepared teeth with etch-and-rinse resin cement (Variolink Esthetic DC system kit). Microtensile bond strength and interfacial nanoleakage were accessed after thermomechanical cyclic loading. Statistical analysis was performed using one-way ANOVA, followed by Tukey’s post hoc test. Additionally, p-values < 0.05 were considered statistically significant. The chlorhexidine pretreated group showed the most favorable outcome compared to the control group. Conversely, using Salvadora persica pretreatment did not affect the bond strength and nanoleakage compared to the control group (p > 0.05). Consequently, unlike Salvadora persica extract, chlorhexidine–dentin pretreatment maintained superior bonding strength to ceramics after thermomechanical cyclic loading, facilitating minimally invasive, yet lasting, aesthetic restoration.

The long-term success of zirconia restorations depends on the durability of the resin–zirconia bond. This study evaluated the microshear bond strength (μSBS) of an MDP-containing universal adhesive, Scotchbond Universal Plus Adhesive, compared with its predecessor, Scotchbond Universal Adhesive, when bonded to three generations of CAD/CAM-fabricated zirconia ceramics. Sixty zirconia specimens were fabricated from 3Y-TZP (IPS e.max ZirCAD), 4Y-PSZ (IPS e.max ZirCAD MT), and gradient zirconia (IPS e.max ZirCAD Prime; 3Y-TZP/5Y-PSZ). Following polishing, sintering, and airborne-particle abrasion with 50 μm Al₂O₃ particles, specimens received either Scotchbond Universal Plus Adhesive or Scotchbond Universal Adhesive. Resin cement cylinders were bonded with a dual-cure resin cement and subjected to thermal cycling (20,000 cycles; 5–55 °C) prior to μSBS testing. Data were analyzed using one-way ANOVA, independent-samples t-tests, and Fisher’s exact test (α = 0.05). Significant differences in μSBS were observed among zirconia generations for both adhesive systems (p < 0.05). The highest bond strengths were recorded for 4Y-PSZ bonded with Scotchbond Universal Adhesive (15.36 ± 3.00 MPa) and Scotchbond Universal Plus Adhesive (14.67 ± 4.52 MPa), whereas the lowest values were obtained for 3Y-TZP (8.91 ± 3.53 MPa and 9.20 ± 3.52 MPa, respectively). No significant differences were detected between the two adhesive systems within any zirconia generation (p > 0.05). Failure mode analysis revealed predominantly adhesive and mixed failures, with no significant differences in the distribution of failure modes among groups (p > 0.05). In conclusion, zirconia generation significantly influenced bond strength, whereas Scotchbond Universal Plus Adhesive demonstrated bonding performance comparable to that of Scotchbond Universal Adhesive after thermocycling. Among the tested substrates, 4Y-PSZ exhibited the most favorable bonding performance.