PURPOSE:The purpose of this study was to evaluate the influence of radiotherapy timing on the dentinal tubule penetration and push-out bond strength of an epoxy resin-based sealer (AH Plus) and a bioceramic sealer (BioRoot RCS). METHODS AND MATERIALS:In total, 180 single-rooted sound human mandibular premolars were used and allocated to three main groups with different radiotherapy timings: Control (no irradiation), Before RT (irradiation prior to root canal obturation), and After RT (irradiation after root canal obturation). Subsequently, each group was subdivided into different sealer types: AH Plus and BioRoot RCS. For the Before RT and After RT groups, a cumulative dose of 60 Gy (6 weeks, 2 Gy per day, 5 days per week) was delivered. The dentinal tubule penetration depth was assessed using confocal laser scanning microscopy (n = 15), and the push-out bond strength was measured using a universal testing machine (n = 15). The data were analyzed using three-way ANOVA and Bonferroni tests (p 0.05). RESULTS:In the coronal thirds, the After RT group showed significantly lower tubule penetration and bond strength compared with the Control group for both sealers. In the apical thirds, BioRoot RCS was predominantly affected. The After RT group also showed significantly lower bond strength and tubule penetration than the Before RT group. These results were confirmed by the higher frequency of adhesive failures in the After RT group compared to the others. Finally, in the coronal thirds, AH Plus exhibited significantly higher bond strength than BioRoot RCS despite having lower dentinal tubule penetration. CONCLUSION:Radiotherapy timing significantly influenced sealer-dentin adhesion, varying by root canal levels and material types. Radiotherapy applied after obturation adversely affected the sealer-dentin interaction, resulting in reduced tubule penetration and bond strength, especially for BioRoot RCS.
PURPOSE:To evaluate the marginal integrity of cervical margin relocation (CMR) or deep margin elevation (DME) restorations using a universal adhesive in etch-and-rinse and self-etch modes, compared to gold-standard systems after 6-month water aging. METHODS AND MATERIALS:Standardized mesial and distal Class II cavities were prepared in 32 human maxillary premolars. Specimens were assigned to four groups according to adhesive systems and modes: OFL (OptiBond FL), CSE (Clearfil SE Bond), UER (Single Bond Universal; etch-and-rinse), and USE (Single Bond Universal; self-etch) (n = 16 per group). After DME/CMR and final restoration, specimens were stored in 37°C distilled water for 6 months. Marginal integrity was assessed qualitatively via micro-CT by two calibrated observers and quantitatively via 0.5% methylene blue dye. Data were analyzed using weighted kappa coefficient, Wilcoxon signed-rank test, two-way repeated measures analysis of variance (ANOVA), and one-way ANOVA with Games-Howell post-hoc tests (α = 0.05). RESULTS:Micro-CT showed high inter-examiner reliability (κ = 0.84) and stable interfacial adaptation across groups post-aging. However, dye penetration revealed that adhesive mode significantly affected microleakage (p 0.05), while proximal box concavity geometry had no significant effect (p > 0.05). The USE group exhibited the lowest mean microleakage (0.94 ± 0.62 mm), showing no significant differences from OFL and CSE. The UER group showed the highest mean microleakage (1.48 ± 0.09 mm), which was significantly higher than the USE group (p 0.05). CONCLUSION:Within the limitations of this study, the self-etch application of universal adhesives provided superior durability of marginal seals for DME compared to the etch-and-rinse mode. Optimizing matrix application also minimized the influence of concavity geometry.
PURPOSE:To determine the influence of different bleaching methods on the shear bond strength (SBS) of orthodontic brackets bonded to resin-infiltrated (Icon, DMG) extracted human enamel. METHODS AND MATERIALS:64 extracted wisdom teeth were randomized into four groups (n = 16): 1. (-)control (no treatment), 2. (+)control (RI), 3. RI followed by 25% H2O2 (IOB) and 4. RI followed by 10% carbamide peroxide bleaching (HB). After a standardized demineralization protocol, RI and bleaching were performed according to the manufacturer's instructions prior to storage for 14 days. Brackets (Mini Diamond Twin, Ormco) were bonded buccally and lingually (Transbond XT, 3M). SBS values (MPa, traverse speed 0.5 mm/min, Zwick Roell) and the Adhesive Remnant Index (ARI) were determined on the buccal side. Following 5000 thermal cycles (5-55°C; RC 20 CS Lauda), SBS and ARI values for the lingual brackets were determined analogously. Data were analyzed with mixed ANOVA and Kruskal-Wallis and Wilcoxon tests at a 0.05 significance level. RESULTS:Differences in SBS were observed among groups (F(3, 64) = 8.01, P 0.001). HB exhibited the lowest SBS values (14.99 ± 6.42 MPa; 10.84 ± 3.61 MPa), differing significantly from the negative control (P = 0.041; P = 0.002 after thermocycling). No significant differences were noted between IOB and HB. Thermocycling reduced SBS values across all groups (F(3, 64) = 25.83, P 0.001). CONCLUSION:RI followed by bleaching negatively impacts bracket bonding strength, with a significant reduction observed after home bleaching, while in-office bleaching showed no such effect.
PURPOSE:To determine the influence of operators' experience, dentin moisture condition (DMC), and adhesive type on shear bond strength, and evaluate the consistency of adhesive performance under these conditions to demonstrate clinical reliability. METHODS AND MATERIALS:Six hundred sound dentin surfaces were randomly divided by five dentists with at least 10 years of experience (n = 300/5 dentists) and five first-year dental students without dental experience (n = 300/5 students). Each operator applied universal (UA) (Adhese Universal, Ivoclar) and etch-and-rinse (ERA) (OptiBond FL, Kerr) adhesives (n = 60/adhesive type) before and after receiving demonstration on the manufacturers' recommended application techniques by the principal investigator (PI), on wet, moist, and dry dentin surfaces (n = 5/DMC). DMCs were obtained by the PI before the operators applied the adhesives. The PI applied composite restorations (Tetric EvoCeram Bulk Fill, Ivoclar) and polymerized for 20 s. Shear bond strength (SBS) test was conducted after 24 h storage at 37°C, in 100% humidity. Boxplot, Log Worth, and Tukey HSD were used for statistics. RESULTS:The median SBS of ERA obtained by dentists was 17.79 MPa with an interquartile range (IQR) of 19.61, while students showed a lower median of 13.52 MPa with IQR of 15.81. The UA showed consistency in SBS and reduced variability across operators with median SBS by dentists and students (25.53 MPa and 24.96 MPa, respectively), with narrower IQRs of 10.6 and 7.3, respectively. SBS of UA was significantly higher than ERA (P 0.001). UA obtained 7.38 MPa ± 0.89 greater SBS than ERA. While no difference in SBS by operator was observed for UA, dentists obtained 1.65 MPa ± 0.73 greater SBS than students with ERA. Dry and moist dentin surface conditions yielded higher SBS values compared to wet surfaces (P 0.001 and P 0.002, respectively), with no significant differences observed between moist and dry surfaces. CONCLUSION:The tested UA provided reliable outcomes regardless of operator and DMC.
PURPOSE:Minimal evidence exists on how class II cavity complexity influences direct restoration provision or if complexifying factors influence the use of techniques and materials. This study aimed to explore: (1) experts' willingness to restore a variety of specific presentations of class II cavities with direct composite restorations; (2) the influence of cavity characteristics on this and the provision of cuspal coverage; and (3) how varying cavity presentations affected technique and material use. METHODS AND MATERIALS:An e-questionnaire developed by international experts was distributed to 67 experts on direct composite restoration. The questionnaire section reported here presented vignettes of varying class II cavities, coded by potential complexifying factors. Respondents were asked if they would restore them with a direct composite. If so, it then asked what specific materials and techniques would be used. Regression analyses were performed. RESULTS:Vignette response rate was 78%. There was a large variation in willingness to restore varying class II cavity presentations with direct composite. This was significantly influenced by the presence of large inter-proximal 'bridging' gaps, root fillings, broad boxes, ≥ 3 cavity surfaces involved and deep sub-gingival margins. When present, these complexifying characteristics affected material and technique use. Those willing to restore more complex cavities were more likely to use more curved circumferential bands and less likely to use a rubber dam, among other factors. CONCLUSION:Cavity complexity affects experts' willingness to place direct composite restorations. The willingness to use a variety of techniques was associated with a greater readiness to restore more complex class II cavities with direct composite.
PURPOSE:This study evaluated the influence of different specimen preparation methods on the shear bond strength (SBS) of a universal adhesive to dentin, with the aim of identifying a more standardized and reliable protocol for SBS testing. METHODS AND MATERIALS:Thirty-three extracted molars were used to obtain 66 dentin surfaces. After surface preparation with 600-grit silicon carbide paper, specimens were randomly assigned to three groups (n = 22) according to the specimen preparation technique: tube-removed (polyethylene tubes removed before testing), tube-retained (tubes left in place during testing), and jig-based (Ultradent jig system, South Jordan, UT, USA). SBS testing was performed using a universal testing machine at 1 mm/min. Failure modes were analyzed under a stereomicroscope and representative specimens were examined by scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA and Tamhane's T2 post-hoc test (α = 0.05). RESULTS:Significant differences were found among the groups (P 0.001). The highest mean SBS values were obtained in the jig-based group, followed by the tube-removed and tube-retained groups. Adhesive failure was predominant across all groups, with 100% adhesive failures observed in the jig-based group. SEM analysis revealed a more clearly delineated bonding interface in the jig-based group, while tube-based groups exhibited minor polyethylene residues. CONCLUSION:These findings indicate that the specimen preparation method plays a critical role in the reliability and interpretation of SBS testing outcomes. The jig-based approach may provide more consistent and reproducible SBS results compared to tube-based methods, highlighting the importance of standardized specimen fabrication in adhesive dentistry research.
PURPOSE:The increasing use of monolithic translucent zirconia for fixed dental restora-tions in orthodontic patients has created new challenges for reliable bracket bonding. This in vitro study evaluated the influence of different surface pretreatment protocols on the shear bond strength (SBS) of metal brackets bonded to 3-mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) and 5-mol% yttria-stabilized partially stabilized zirconia (5Y-PSZ) ceramics using an adhesive resin cement. METHODS AND MATERIALS:Ninety-six specimens were prepared (n = 48 per zirconia type), each providing two bonding interfaces (n = 192). Three surface pretreatment protocols were tested: pumice slurry (PS), silicon carbide burr roughening (SiB), and alumina air-particle abrasion (AP). Metal brackets were bonded using an MDP-containing self-adhesive resin cement and a custom 3D-printed bonding device, applying a standardized load of 7.4 N. Half of the specimens were tested for SBS after 3 days of water storage at 37°C; the remaining half after artificial aging (37,500 thermocycles between 5°C and 55°C) for 150 days. SBS was measured using a universal testing machine. Data were analyzed using non-parametric tests (Kruskal-Wallis; Mann-Whitney U with Bonferroni-Holm correction; α = 0.05). RESULTS:Artificial aging significantly affected SBS, whereas zirconia type had no significant influence. After 3 days, no significant differences were observed among surface pretreatment methods. Following artificial aging, AP and SiB pretreatments achieved significantly higher SBS values than PS for both zirconia types. AP yielded the highest bond strengths overall (up to 51.3 MPa for 5Y-PSZ after 150 days). Spontaneous debonding occurred only in the PS groups. CONCLUSION:Although AP pretreatment achieved the highest bond strength values, its clinical application is limited by the risk of surface damage and uncontrollable intraoral pressures. SiB pretreatment provided clinically sufficient bond strength while preserving zirconia surfaces, representing a safer and more practical alternative. Pumice slurry alone was inadequate for reliable bonding. Thus, SiB can be recommended as a minimally invasive and effective clinical protocol for orthodontic bonding to zirconia restorations.
Purpose: To evaluate and compare the presence and distribution of residual fibers from two different brands of adhesive applicators within the adhesive interface after active application of a universal adhesive. Methods and Materials: Eighteen sound human molars were prepared with standardized Class II cavities and randomly assigned to two groups (n = 9) according to the applicator used: group P (Proclinic SAU, Spain) or group K (Kerr, USA). A one-step self-etch universal adhesive (Scotchbond Universal Plus; Solventum, USA) was actively applied following the manufacturer's instructions. After polymerization, specimens were examined under ultraviolet (UV) light using an optical microscope. Residual fibers were identified, quantified, and categorized according to their location (external cavity surfaces, cavosurface margins, internal line angles, axial walls, and cavity floors). Data were analyzed using the Fisher-Freeman-Halton exact test (P < 0.05). Results: Residual fibers were detected in all specimens, predominantly on external cavity surfaces, cavosurface margins, and axial walls. Statistically significant differences were observed between the two applicator brands (P < 0.05), with group P showing a higher number and greater length of fibers than group K. Conclusion: Both applicator brands released microscopic fibers that became incorporated into the adhesive interface, revealing an unrecognized source of contamination and leading to rejection of the null hypothesis. Fiber distribution was not homogeneous across cavity surfaces. The proposed methodology proved effective for detecting and localizing applicator-derived residues, highlighting an overlooked source of contamination that may influence adhesive performance and restoration durability.
PURPOSE:This study evaluated the effects of different surface treatment methods and thermocycling on the shear bond strength (SBS) of repaired composite resin restorations across three composite types (nanohybrid, bulk-fill, and microhybrid). METHODS AND MATERIALS:A total of 252 disk-shaped specimens (Ø20 × 5 mm, n = 7 per group) were fabricated from three composite resins: a nanohybrid composite (Filtek Z550; 3M ESPE), a bulk-fill composite (Opus Bulk Fill; FGM), and a microhybrid composite (Gradia Direct Anterior; GC). The specimens were divided into four subgroups according to surface treatment: no surface treatment (ST-C), airborne-particle abrasion (ST-AO), bur roughening with a medium-grit diamond bur under water cooling (ST-B), and phosphoric acid etching followed by application of a universal adhesive (ST-PH). For all groups, the repair procedure was performed using a nanohybrid composite (Filtek Z550; Ø2.38 × 3 mm). Aging protocols included water storage at 37°C for 24 h (Immediate), thermocycling for 10,000 cycles, and 30,000 cycles between 5°C and 55°C. Shear bond strength (SBS) was measured using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed using the Shapiro-Wilk and Levene tests, followed by three-way ANOVA (with stratified one-way ANOVAs where interactions were significant) and Tukey post hoc tests (α = 0.05). RESULTS:A three-way ANOVA revealed that composite type, surface treatment, and aging condition significantly affected SBS (P 0.001). SBS differed significantly among composites and surface treatments (P 0.001). For RC-BF, ST-PH provided the highest bond strength after 10,000 and 30,000 cycles. In RC-MH, bur roughening (ST-B) yielded the highest bond strength at 10,000 cycles. For RC-NH, ST-PH initially showed the highest SBS values; however, at 30,000 cycles, ST-B provided the best repair stability for the RC-NH group (12.96 MPa). However, the highest overall SBS value across all tested materials at this final aging stage was achieved by the RC-BF group treated with ST-PH (13.91 MPa).. Thermocycling significantly reduced SBS (P 0.001). Nanohybrid composites exhibited relatively stable SBS values across aging conditions. CONCLUSION:Appropriate surface treatment, particularly phosphoric acid etching combined with universal adhesive application, significantly increased shear bond strength following thermocycling. Nanohybrid composites demonstrated stable SBS trends across aging conditions compared with the other materials.
PURPOSE:Self-adhesive flowable giomer (SAG) has been used in dental practice recently to simplify clinical procedures and shorten chair times. However, there are only few studies evaluating its bond strength to enamel and dentin, resulting in a lack of evidence. The purpose of this study was to compare the micro-shear bond strength with and without adhesive in enamel and dentin to evaluate the self-adhesive ability of SAG. METHODS AND MATERIALS:Sound bovine teeth were used as the tooth substrates. For μ-SBS tests, enamel and dentin specimens were prepared for SAG (Beautifil Kids SA - BK), a self-adhesive flowable composite (Vertise Flow - VF), and a nanohybrid flowable giomer (Beautifil Flow Plus F03 - BF). Two adhesive modes were tested for BK and VF (with self-etching adhesive and no adhesive), and one for BF (with self-etching adhesive). The μ-SBS test was conducted after 24 h and after thermocycling for 10,000 cycles using a universal testing machine. RESULTS:For all materials, when self-etching adhesive was used, the μ-SBS was significantly higher than that of the no-adhesive group (P 0.05). No statistically significant difference was found between the restorative materials under any condition. Thermocycling had no significant effect on the μ-SBS of BK. In the self-etching adhesive group, mixed failure was predominant for all materials. However, in no-adhesive group, adhesive failure and mixed failure were observed at similar levels for all materials. CONCLUSION:The self-adhesive resin without adhesive showed lower bonding strength in both enamel and dentin compared to the one with adhesive. CLINICAL RELEVANCE:Although there were no significant differences in bond strength stability between materials, SAG still offers a simplified bonding process without compromising bond strength, making it a viable option for clinical use.
PURPOSE:The aim of this in vitro study was to measure the microtensile bond strength (μTBS) and the contact angle of a universal adhesive (Prime & Bond Active) to overdried and water-contaminated human dentin. MATERIALS AND METHODS:After exposing flat dentin surfaces (5×5 mm2) of 60 caries- and restoration-free molars, test groups were either overdried or water-contaminated before adhesive application (self-etch) or after phosphoric acid etching (etch&rinse). In control groups, the adhesive was applied according to the manufacturer's instructions. μTBS (n = 45 samples) was analyzed (24 h/thermocycling: 15,000 cycles, 5/55°C). Fracture patterns were assessed microscopically. Contact angles were measured using the sessile drop method. Statistical analysis was performed using Tobit regression and Scheffé correction for bond strength data and Kruskal-Wallis test for contact angle measurements (α = 0.05). RESULTS:Overall, µTBS was significantly higher after etch&rinse application compared to the self-etch mode before (P 0.001, Δ 11.04 MPa) and after aging (P 0.001, Δ 6.73 MPa). The highest μTBS (29.9 ± 10.4 MPa) was achieved by the etch&rinse control before aging. For etch&rinse application, water contamination and overdrying initially led to significantly lower µTBS compared to the control (P = 0.014/P = 0.007). Aging significantly decreased μTBS in both etch&rinse control and overdry groups (P 0.001/P = 0.036). Fracture modes were predominantly adhesive (90%). Contact angle on water-contaminated dentin was significantly lower for self-etch than for etch&rinse mode (P = 0.008). CONCLUSION:The adhesive application mode significantly influenced bond strength. Dentin surface condition initially affected the µTBS solely in etch&rinse mode. Only on water-contaminated dentin, the contact angle was influenced by the adhesive application mode.
PURPOSE:To measure the tip diameter (mm) and the ability to cover the anterior and posterior large restorations, radiant power (mW), radiant exitance (mW/cm2), emission spectrum (mW/cm2/nm), radiant exposure (J/cm2), the effect of the design on the access to the mouth posterior region, the temperature rise inside the pulp of three light-curing units (LCUs) and a new LCU available in the Brazil. METHODS AND MATERIALS:Four LCUs that cost over US$900, three well-established (Bluephase G2, Ivoclar Vivadent; VALO Grand, Ultradent; and VALO Cordless, Ultradent), and a new LCU (Quazar, FGM) were tested in standard mode (20 s for all LCUs), high mode (3 s for VALO Cordless, 5 s for Quazar, and 20 s for Bluephase G2), and Xtra power mode (3 s for VALO Grand). The radiant power (mW) and emission spectrum (mW/nm) were measured using an integrating sphere connected to a fiberoptic spectroradiometer. The internal tip diameter (mm) of each LCU was measured using a digital caliper and was used to calculate the radiant exitance (mW/cm2). Radiant exitance profiles at the light tip were measured using a laser beam profiler. The radiant exposure (J/cm2) was calculated. The in vitro temperature rise produced by LCUs inside the pulp cavity of molar teeth was measured using a thermocouple. The mouth access of the LCU tip on the occlusal surface of the first mandibular molar tooth with two mouth openings of 25 mm and 45 mm at the incisors was evaluated. The cost of each LCU in Brazil was correlated with internal tip diameter, radiant power, and radiant exitance. RESULTS:All the LCUs were multiple-peak LCUs, and a uniform output. Quazar, VALO Cordless, and VALO Grand could maintain a perpendicular position regardless of mouth interincisal opening, while the Bluephase G2 required a tip angulation of 31.6 degrees at the 25 mm interincisal opening. The VALO Grand and VALO Cordless produced the highest temperature rise in standard mode ( 2.5°C), while in high mode, all LCUs produced lower temperature increases that use 5 s for Quazar and 3 s for VALO Grand and VALO Cordless, except for Bluephase G2, which produced a higher temperature rise ( 2.0°C) when activated for 20 s. There was a positive correlation between the cost of these LCUs and their averaged radiant power, diameter and the radiant exitance. CONCLUSIONS:The LCUs tested emit light in the blue and violet spectra, characterizing them as multiple peaks. The temperature increases in the produced pulp remained within safe thermal limits ( 2.5°C), although standard-mode exposures produced higher pulp temperature rises. Bluephase G2 created higher angulation at 25 mm of interincisal mouth opening. The Quazar LCU produced a light output that was comparable to that from leading LCUs.
PURPOSE:Surface treatment of zirconia before cementation can be performed using different methods, e.g. airborne particle abrasion (APA) or various etching protocols. This study evaluated the effect of storage time between surface treatment and cementation on the surface free energy (SFE) of zirconia, the bond strength of composite cement, and failure mode. MATERIALS AND METHODS:Rod-shaped zirconia specimens were fabricated and assigned to two surface treatment groups: APA (n = 80) and hot etching with potassium hydrogen difluoride (KHF2, n = 80). Each group was divided into four storage time subgroups: immediate, 24 h, 1 week, and 1 month. After storage, specimens were either analyzed for SFE (n = 10) or cemented for shear bond strength (SBS) testing and failure mode evaluation (n = 10). RESULTS:Two-way analysis of variance (ANOVA) showed a significant effect of both surface treatment and storage time on SFE (P 0.05), with KHF2-etched zirconia exhibiting the highest values across all time points. In both groups, SFE gradually decreased with increased storage. Surface treatment did not significantly affect SBS (P > 0.05). Storage time significantly influenced SBS (P 0.05), specifically for KHF2-etched zirconia; post-hoc comparisons showed higher SBS after 1 week than at immediate testing (P 0.05). Although adhesive failures to cement increased with longer storage time for KHF2-etched specimens, this trend was not significant (P > 0.05). For APA specimens, the highest incidence of adhesive failures (n = 9) to cement occurred after 24 h of storage. CONCLUSION:Given the significant decrease in SFE with prolonged storage and adhesive failures to zirconia tended to increase over time, minimizing the interval between surface treatment and cementation is recommended.
PURPOSE:This in vitro study was designed to assess the influence of KATANA™ Cleaner (KC) on the microshear bond strength (μSBS) of composite resin restorations to saliva-contaminated dentin surfaces at various stages of the bonding process using a two-step self-etch adhesive system. MATERIALS AND METHODS:A total of 140 sound human molars were randomly assigned into 14 groups according to the timing of saliva contamination and the decontamination approach. Saliva contamination was introduced at critical phases of adhesive application (before primer, after primer, after bond application, and after bond polymerization). KC was used for surface decontamination where applicable. Clearfil SE Bond adhesive and Filtek Z250 composite resin were applied using standardized procedures. μSBS test was performed after 24-h water storage, and failure modes were analyzed using stereomicroscopy. Additionally, dentin surfaces were evaluated under SEM. EDS was employed to evaluate the structure of the adhesive surface. Data were statistically analyzed using one-way ANOVA and LSD post hoc tests (α = 0.05). RESULTS:A significant difference in μSBS was observed among the groups (P = 0.029). The highest μSBS (29.5 ± 9.25 MPa) was recorded in the group that was contaminated after primer application and subsequently decontaminated with KC prior to bonding, surpassing even the uncontaminated control group. Decontamination following contamination after polymerization also led to significantly improved μSBS (26.5 ± 10.78 MPa). Groups without any decontamination exhibited significantly lower μSBS. Predominantly cohesive (in composite resin) and mixed failure modes were observed in high-strength groups, while adhesive failures were more common in low-strength groups. CONCLUSION:KC significantly improved the μSBS of composite resin in saliva-contaminated dentin, particularly when applied after primer or post-polymerization contamination. These findings support the clinical use of KC as an effective decontamination protocol to maintain bonding performance under compromised isolation.
PURPOSE:This study evaluated the effects of etching mode, pH, and composition on the shear bond strength of three universal adhesives (UAs), in comparison with conventional adhesives. MATERIALS AND METHODS:Crowns from 110 extracted third molars were sectioned to obtain 220 dentin surfaces and allocated into 11 groups (n = 20) based on adhesive system (OptiBondFL, ClearfilSE Bond, All-Bond Universal, OptiBond Universal, G2-Bond Universal) and etching mode (etch-and-rinse [ER], self-etch [SE], selective dentin etching [SDE]). Each group was divided into pre- and post-aging sub-groups. Shear bond strength was tested at 24h and after 5,000 thermal cycles. The resin-dentin interface was examined using scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA, LSD post-hoc and paired-sample t-tests (α = 0.05). RESULTS:All-Bond Universal exhibited the highest bond strength across all modes, while OptiBond Universal showed the lowest. No significant difference was observed between ER and SE modes for most UAs, except G2-Bond Universal. SDE did not result in significantly higher bond strength compared to SE or ER in any group. After aging, G2-Bond Universal in SE mode exhibited the highest bond strength. CONCLUSION:Bond strength was influenced by etching mode, pH, and composition of the adhesive. UAs performed comparably to the gold-standard SE adhesive in SE mode; however, their performance in ER mode varied depending on their composition and pH. CLINICAL RELEVANCE:To ensure predictable clinical outcomes, clinicians should recognize that UAs do not perform uniformly. Selecting both the adhesive and etching mode according to the adhesive's composition may enhance long-term bonding success.
PURPOSE:This study evaluated the effects of incorporating urethane tetramethacrylate (UTMA) monomers and inorganic nano-fillers on the bonding performance and mechanical properties of a next-generation one-step universal adhesive, Clearfil Universal Bond Quick 2 (UBQ2), with a focus on clarifying its improvements over the previous formulation. MATERIALS AND METHODS:Five adhesive systems were investigated: UBQ2, two experimental variants lacking either UTMA (UBQ2-U) or nano-fillers (UBQ2-F), the predecessor adhesive (Clearfil Universal Bond Quick, UBQ), and a gold-standard two-step self-etch adhesive (Clearfil SE Bond 2, SE2). Microtensile bond strength (μTBS), bond layer thickness (L), ultimate tensile strength (UTS), and water sorption (Wsp) were evaluated. RESULTS:UBQ2 demonstrated significantly higher UTS and lower Wsp than UBQ2-U (P 0.001 and P = 0.03, respectively), indicating enhanced mechanical resilience and hydrolytic stability due to the presence of UTMA. Compared to UBQ, UBQ2 showed improved mechanical properties while maintaining comparable μTBS. The absence of nano-fillers (UBQ2-F) significantly reduced μTBS (P 0.05), confirming their critical role in bonding performance. Despite forming a thinner adhesive layer, UBQ2 achieved dentin bond strength comparable to SE2. CONCLUSION:By combining UTMA and nano-fillers, UBQ2 has improved wettability compared to conventional products, while also providing high bonding performance and mechanical properties with a one-step application. These findings support the development of universal adhesives through simplified clinical protocols and improved material properties. CLINICAL RELEVANCE:This study demonstrates that incorporating nano-fillers and UTMA into a one-step universal adhesive (UBQ2) enhances mechanical strength, reduces water sorption, and maintains high dentin bond strength. Clinically, UBQ2 offers a simplified yet reliable bonding performance comparable to SE2.
PURPOSE:To evaluate whether single-day, gamified training (called 'Battle of the Bonds') improves operators' immediate macro dentin shear bond strength (SBS) values and perceived learning in undergraduate and continuing dental education about dental adhesives, composite resin, and light-curing units. MATERIALS AND METHODS:In July 2025, 14 dentists and 21 final-year students performed four macro-SBS tests before and eleven after lectures on adhesive systems, composite selection, and light-curing. SBS was measured on human dentin for each participant's routine adhesive and representatives of all actual adhesive/generation families (from three-step etch-and-rinse to universal adhesives). Post-course satisfaction was measured using a 13-item Likert questionnaire (ranging from 1 to 5). Paired and independent t-tests were used to compare the SBS (α = 0.05). RESULTS:The baseline SBS with the participants' own adhesive was similar between the dentists and the students (12.5 ± 6.4 MPa vs 13.1 ± 6.6 MPa, P = 0.68). After training, the mean SBS with the participants' own adhesive significantly increased to 18.5 ± 6.3 MPa for the dentists (+67%) and to 17.3 ± 6.0 MPa for the students (+27%) (both P 0.05). Satisfaction with training and perceived knowledge gains were very high (4.9 ± 0.5 for dentists and 4.9 ± 0.3 for students). CONCLUSIONS:A single-day, competition-based curriculum that couples concise lectures with hands-on SBS testing yields rapid, clinically meaningful improvements and strong engagement across predoctoral and practitioner audiences. This experiential format may help standardize technique-sensitive restorative skills in dental education.
PURPOSE:This study aimed to evaluate the effects of bioactive, inorganic, and organic fillers on the curing time, mechanical properties, mineralization ability, and shear bond strength to dentin of 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butylborane (4-META/MMA-TBB) resin-based restorative materials. MATERIALS AND METHODS:Experimental resins were prepared by incorporating 3 wt% organic composite filler, bioactive glass, or aluminosilicate glass into 4-META/MMA-TBB resin. A commercial organic-filler-containing 4-META/MMA-TBB resin (Bondfill SB Plus (BSP)) was also tested for comparison. The curing time, three-point flexural strength, and shear bond strength to root dentin were measured and statistically analyzed with a significance level of α = 0.05. The mineralization ability of groups containing bioactive glass was evaluated based on the formation of hydroxyapatite in simulated body fluid. RESULTS:The bioactive glass group exhibited prolonged curing times and reduced flexural strengths compared to BSP. Bioactive glass induced slight mineralization. Organic composite filler reduced the curing time and significantly increased the shear bond strength to dentin. After thermal cycling, the organic composite filler groups retained higher bond strengths than the other groups. CONCLUSION:Incorporating organic composite fillers into 4-META/MMA-TBB resin may improve clinical handling by reducing the curing time while maintaining or enhancing the bond strength to dentin, suggesting their suitability for restorative applications, particularly in moisture-compromised environments.
PURPOSE:This prospective crossover clinical study evaluated the effectiveness of different moisture control methods on intraoral humidity and examined the influence of external environmental humidity. MATERIALS AND METHODS:Forty adult participants (31 females, 9 males; mean age 36.6 ± 11.3 years) were enrolled. Intraoral relative humidity was measured above anterior and posterior teeth under four randomized conditions: control (mouth breathing), rubber dam isolation, vacuum-assisted isolation (ZOO), and saliva ejector. External humidity was recorded simultaneously and categorized as high (≥60%) or low (60%). RESULTS:Both rubber dam isolation and vacuum-assisted isolation significantly reduced intraoral humidity compared with the saliva ejector and control. Under low external humidity, rubber dam and vacuum-assisted isolation achieved the lowest intraoral humidity (all P 0.001). Under high external humidity, all methods reduced humidity compared with control, but vacuum-assisted isolation remained significantly more effective than the rubber dam and saliva ejector. External humidity showed a strong correlation with intraoral humidity in the rubber dam group (ρ up to 0.77, P 0.001). CONCLUSION:Moisture control methods differ in their ability to reduce intraoral humidity, with rubber dam and vacuum-assisted isolation providing the most effective reduction. However, high external humidity significantly increases intraoral humidity regardless of the isolation method, indicating that clinicians should consider both the isolation strategy and environmental conditions when aiming to minimize intraoral humidity.
PURPOSE:To evaluate the influence of functional monomer type and powder-to-liquid ratio on the interfacial properties and degree of conversion of experimental self-adhesive flowable resin composites (SAFRCs) bonded to dentin. MATERIALS AND METHODS:Nine experimental SAFRC formulations were developed by varying the powder-to-liquid ratio (1.9, 2.2, 2.5) and the functional monomers included (10-MDP, GPDM, HEMA). Human molars (n = 27) were restored using each formulation and analyzed using a rheometer to assess viscosity, Raman micro-spectroscopy for inter-diffusion zone (IDZ) width, and degree of conversion at the interface (DC%). Two-way ANOVA and post-hoc tests were performed for statistical analysis (α = 0.05). RESULTS:Rheological testing revealed, as expected, non-Newtonian flow behavior in all composites, with significant effects of both powder-to-liquid ratio (P 0.001) and monomer type (P 0.001) on viscosity. 10-MDP composites exhibited optimal viscosity (1.12-2.86 mPa·s) across all ratios, significantly lower than GPDM and HEMA. Raman mapping showed a distinct IDZ with hybrid characteristics for 10-MDP formulations, contrasting with abrupt transitions or gaps in GPDM and HEMA groups. IDZ width was significantly greater in 10-MDP formulations (P 0.0001). The DC% at the interface was highest for 10-MDP and HEMA formulations, exceeding 68%, while GPDM composites showed lower values (P 0.001). CONCLUSION:Functional monomer type critically affects the interfacial bonding performance and conversion rate of SAFRCs, with 10-MDP outperforming GPDM and HEMA in interdiffusion and adhesive quality. Variations in powder-to-liquid ratio influenced viscosity but had a limited impact on interfacial performance. Optimized formulations with 10-MDP may enhance the clinical efficacy of SAFRCs. CLINICAL RELEVANCE STATEMENT:Refining acidic-monomer chemistry and viscosity in SAFRCs could improve their bonding predictability.
