The current trend in denture adhesives is shifting toward zinc-free formulations due to the significant health concerns associated with zinc. Studies have focused on the retention of these zinc-free denture adhesives; however, there is a dearth of literature regarding their damping performance. This study analyzes the impact of oral cavity physiological parameters: temperature, pH, and swelling ratio on the mechanical properties of zinc-stabilized and zinc-free denture adhesives and examines the role zinc plays in influencing the adhesive behavior. This study investigates how underlying mechanical properties of adhesive cream change for zinc-stabilized and zinc-free denture adhesives. The relative damping and its variation from exposure to physiological conditions in the oral cavity can significantly assist in the design of dentures to reduce the discomfort experienced by denture wearers. The relative damping of the zinc-stabilized and zinc-free denture adhesives was investigated with the loss modulus values, which were evaluated using rheological frequency sweep tests. The tests were performed by maintaining the denture adhesives at specified values of temperature, pH, and swelling ratio, and over a frequency range of 0.01 Hz to 10 Hz, which included the average frequencies of human chewing / bite forces reported in existing literature. Zinc-stabilized denture adhesive showed a larger fluctuation of loss modulus values compared to the zinc-free formulation with respect to pH, temperature, and swelling ratios. The zinc-free denture adhesive showed higher damping behavior at frequencies below 0.7 Hz, whereas the zinc-stabilized denture adhesive showed higher damping behavior above loading frequencies of 0.7-1 Hz. Both the adhesives showed varying behavior on either side of the bite force spectrum in terms of relative damping of the applied bite. The damping or cushioning effect provided by denture adhesives can reduce pain experienced and assist dental practitioners in better supporting denture wearers.
To investigate the antibacterial effects of Terminalia catappa Linn (TCL) leaf extracts at different concentrations and the effects of these extracts used as primers on the long-term adhesive properties of two universal adhesives. After extract preparation, the antimicrobial and antibacterial activities of TCL against Streptococcus mutans (UA 159) were assessed in microdilution assays to provide the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Additionally, to provide quantitative data on the ability of TCL extract to reduce cell viability, colony forming units (CFU) were counted. To examine adhesive properties, 288 human molars were randomly assigned to 32 experimental conditions (n = 9) according to the following variables: (1) treatment agent: negative control (untreated surface), and primers at concentrations of 1xMIC, 5xMIC, and 10xMIC; (2) adhesives: Scotchbond Universal (SBU) and Futurabond Universal (FBU); (3) adhesive strategy: etch-and-rinse (ER) or self-etch (SE); and (4) storage time: 24 h or after 2 years. Primers were applied for 60 s, upon which the teeth were incrementally restored and sectioned into adhesive-dentin bonded sticks. These were tested for microtensile bond strength (μTBS) and nanoleakage (NL) after 24-h and 2-year water storage, as well as in-situ degree of conversion (DC) at 24 h. The chemical profile of the hybrid layer was determined via micro-Raman spectroscopy. Biofilm assay data were analyzed using the Kruskal-Wallis test; the pH of culture media and the chemical profile were analyzed by one-way ANOVA. The adhesive properties (µTBS, NL, DC) were evaluated using a four-way ANOVA and Tukey's test. Significance was set at 5%. Similar values of MIC and MBC were observed (2 mg/ml), showing bactericidal potential. CFU analysis demonstrated that concentrations of 5xMIC and 10xMIC significantly inhibited biofilm formation (p < 0.001). The application of the TCL primer at all concentrations significantly increased the immediate μTBS and DC, and decreased the immediate NL values when compared to the control group (p < 0.05), regardless of the adhesive and adhesive strategies. Despite an increase in the NL values for all groups after 2 years (p > 0.05), in groups where the TCL primer was applied, the μTBS remained constant after 2 years for both adhesives, while a decrease in the μTBS was observed in the control groups (p < 0.05). Usually, 10xMIC showed better results than 1xMIC and 5xMIC (p < 0.05). The application of TCL promoted cross-linking; cross-linking rates increased proportionally to the concentration of TCL (p < 0.05). Primers containing TCL promoted bactericidal and bacteriostatic action, as well as cross-linking with dentin, while maintaining the adhesive properties of the adhesive-dentin interface after 2 years of water storage.
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. 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. 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. 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.
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. 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. 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. The self-adhesive resin without adhesive showed lower bonding strength in both enamel and dentin compared to the one with adhesive. 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.
To systematically review in-vitro studies that evaluated the influence of erbium laser pretreatment on dentin shear bond strength (SBS) and bond failure modes. Electronic databases (PubMed, Cochrane Central, Embase, and Web of Science) were searched. Only in-vitro studies involving erbium laser irradiation of the dentin surface and SBS testing of the bonded resin block were included. The three common modes of bond failure (1. adhesive, 2. cohesive, and 3. mixed) were observed and analyzed. The network meta-analysis (NMA) was performed by Stata 15.0 software, the risk of bias was evaluated, and the certainty of the evidence was assessed by the Confidence in Network Meta-analysis (CINeMA). Forty studies with nine pretreatments (1. blank group: BL; 2. phosphoric acid etch-and-rinse: ER; 3. self-etch adhesive: SE; 4. Er:YAG laser: EL; 5. Er,Cr:YSGG laser: ECL; 6. ER+EL; 7. ER+ECL; 8. SE+EL; 9. SE+ECL) were included in this analysis. The NMA of SBS showed that ER+EL [SMD = 0.32, 95% CI (0.11, 0.98)] had the highest SBS next to ER, especially when using one of the 3M ESPE adhesives, followed by EL, ECL, SE and SE+EL. The Ivoclar Vivadent adhesives significantly increased the SBS of the ECL [SMD = 0.37, 95% CI (0.16,0.90)] and was higher than ER+EL [SMD = 0.25,95% CI (0.07,0.85)]. Finally, the surface under the cumulative ranking curve (SUCRA) value indicated that ER+EL (SUCRA = 71.0%) and EL (SUCRA = 62.9%) were the best treatments for enhancing dentin SBS besides ER. ER+EL (SUCRA = 85.3%), ER (SUCRA = 83.7%) and ER (SUCRA = 84.3%) had the highest probability of occurring in adhesive, cohesive and mixed failure modes, respectively. Er:YAG and Er,Cr:YSGG lasers improved dentin SBS compared to the blank group, especially when the acid etch-and-rinse pretreatment was combined with Er:YAG laser. Shear bond strength and failure mode do not appear to be directly related.
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. 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. 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. The tested UA provided reliable outcomes regardless of operator and DMC.
To investigate the effect of adhesive type and long-term aging on the shear bond strength (SBS) between silica-based ceramics and composite cement (CC). Lithium-silicate (LS), feldspathic (FD) and polymer-infiltrated ceramic (PIC) blocks were sectioned (10 x 12 x 2 mm) and divided into 24 groups considering the factors: "ceramics" (LS, FD, and PIC), "adhesive" (Ctrl: without adhesive; 2SC: 2-step conventional; 3SC: 3-step conventional; 1SU: 1-step universal), and "aging" (non-aged or aged [A]). After the surface treatments, CC cylinders (n = 15, Ø = 2 mm; height = 2 mm) were made and half of the samples were subjected to thermocycling (10,000) and stored in water at 37°C for 18 months. The samples were submitted to SBS testing (100 kgf, 1 mm/min) and failure analysis. Extra samples were prepared for microscopic analysis of the adhesive interface. SBS (MPa) data was analyzed by 3-way ANOVA and Tukey's test (5%). Weibull analysis was performed on the SBS data. All factors and interactions were significant for SBS (p<0.05). Before aging, there was no significant difference between the tested groups and the respective control groups. After aging, the LS_1SU (22.18 ± 7.74) and LS_2SC (17.32 ± 5.86) groups exhibited significantly lower SBS than did the LS_Ctrl (30.30 ± 6.11). Only the LS_1SU group showed a significant decrease in SBS after aging vs without aging. The LS_1SU (12.20) group showed the highest Weibull modulus, which was significantly higher than LS_2SC_A (2.82) and LS_1SU_A (3.15) groups. No type of adhesive applied after silane benefitted the long-term adhesion of silica-based ceramics to CC in comparison to the groups without adhesive.
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. 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). 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). 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.
To evaluate the effect of pre-procedural antiseptic mouthwashes on dentin bond strength of different adhesive systems. Flat occlusal dentin surfaces from 120 extracted human molars were randomly divided into four groups according to mouthwashes (0.12% chlorhexidine = CHX, 1% hydrogen peroxide = HP, 0.2% povidone-iodine = PI, and no mouthwash/control) and three subgroups of adhesives used (Clearfil SE Bond; CSE, Single Bond Universal = SBU in etch-and-rinse (ER) or self-etch (SE) modes) (n = 8). Composite resin was built up, and all bonded teeth were stored in 37°C distilled water for 24 h. Stick-shaped specimens were prepared and subjected to microtensile bond strength (µTBS) test. Failure mode analysis was determined using a light microscope. A resin-dentin interface was observed using scanning electron microscopy (SEM, n = 2). Elemental analysis in the PI group was further examined by SEM with energy-dispersive X-ray spectroscopy. The µTBS data were statistically analyzed by two-way analysis of variance (ANOVA) and Duncan's multiple comparison (P < 0.05). Rinsing with PI followed by SBU-SE demonstrated significantly higher µTBS than the control group (P < 0.05). Rinsing with HP showed significantly lower bond strength for CSE (P < 0.05). However, the effect of adhesive systems was not observed for all mouthwashes used (P > 0.05). SEM/EDX revealed the iodine deposition in the underlying dentin, where the highest amount of iodine was found for SBU-SE. CHX and PI can be recommended as pre-procedural antiseptic mouthwashes since they show no negative impact on µTBS for all tested adhesives. The dentin bond strength of CSE is hampered in the HP mouthwash group, and this should be a concern for the use of self-etching adhesive afterward.
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. 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). 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. 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.
This study aims to develop and characterize copper-doped bioactive glass nanoparticles (BG/CuNp), and to evaluate the effects of their addition into a resin composite on antimicrobial activity (AMA), cytotoxicity (CTX), ultimate tensile strength (UTS), Knoop microhardness (KHN), as well as immediate resin-dentin microtensile bond strength (μTBS), nanoleakage (NL) and in-situ degree of conversion (DC). BG/CuNp were added to a resin composite at different concentrations (0% [control]; 5, 10 and 20 wt%). The AMA was evaluated against Streptococcus mutans. For CTX, the Gingival mesenchymal stem cells (GMSC) cell line was used. For UTS and KHN, specimens were tested after 24 h and 28 days. For bonding evaluation, a universal adhesive was applied on flat dentin surfaces, experimental resin composite build-ups were prepared, and specimens were sectioned to obtain resin-dentin sticks. These were evaluated for μTBS, NL and DC after water storage. Data were submitted to statistical analyses (α = 0.05). The addition of 5% and 10% of BG/CuNp increases AMA (P 0.05), while the CTX remained unchanged with resin-containing BG/CuNp (P > 0.05). UTS and KHN remained stable with the addition of 5% and 10% of BG/CuNp at 24 h, but showed significantly higher values compared to the control after 28 d (P 0.05). μTBS and in-situ DC remained unchanged with BG/CuNp addition, regardless of the concentration added. However, significantly lower NL was observed for BG/CuNp groups (P 0.05). The addition of BG/CuNp in the tested concentrations into a resin composite may be an alternative to provide antimicrobial activity and improve the integrity of the hybrid layer, without compromising biological, adhesives and mechanical properties.
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. 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). 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. 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.
The popularity of Biodentine (Septodont) use for vital pulp therapies requires verifying its bonding ability to other restorative materials. The null hypotheses were that different restorative materials and adhesive strategies did not influence shear bond strength (SBS) to Biodentine, nor its setting time. 204 plastic molds were filled with Biodentine, half set for 12 min, and the rest for 7 days. Specimens were divided into six groups according to the strategy and material used to restore over Biodentine (n = 17): (1) SE: Universal adhesive application in self-etch mode; (2) ER: Universal adhesive in etch-and-rinse mode; (3) Bur: Roughening with a bur followed by SE; (4) AO: Airborne-particle abrading with Al2O3 particles before SE; (5) RMGIC: Restoration with a resin-modified glass-ionomer; (6) SARC: Restoration with a self-adhesive resin cement. Groups 1 to 4 were restored with a flowable bulk-fill composite. Specimens were subjected to SBS, and the mode of failure was determined. Five additional specimens were evaluated under SEM-EDX. Data were analyzed with Kruskal-Wallis and U-Mann-Whitney tests (P 0.05). AO and SARC groups showed 100% pretest failures. At 12 min setting, the RMGIC group and Bonferroni correction achieved the lowest SBS values. At a 7-day setting, the Bur group registered the lowest SBS, and the groups restored with universal adhesive achieved the highest values. SBS results for the Bur and RMGIC groups were influenced by the setting time. Bur roughening or alumina airborne-particle abrading did not improve Biodentine adhesion to composite resin restorations, whereas the application of a universal adhesive achieved the highest SBS results regardless of the evaluated setting time.
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. 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). 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. 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. 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.
The goal of this study was to determine the survival rate, success rate, and periodontal health quality (PHQ) of glass fiber-reinforced composite (FRC) resin-bonded fixed dental prostheses (RBFDPs) over an observation period of up to 22 years. RBFDPs reinforced with unidirectional glass fiber strands were fabricated directly (n = 16) or indirectly (n = 31; *n = 1 missing data) for 48 adult patients (24 female, 24 male) and used to replace 39 anterior teeth and 9 posterior teeth in the maxilla (n = 33) or mandible (n = 15) using different framework designs: single-retainer (n = 8), double-retainer (n = 33), or multi-retainer (n = 7). Their fate was classified as a success, functional survival, or failure based on observed complications. PHQ was evaluated by measuring PPD, CAL, SBI, and PI around the abutment teeth and unrestored reference teeth (controls). The clinical quality of the restorations was evaluated according to the Fédération Dentaire Internationale (FDI) criteria. Statistical analysis included Kaplan-Meier survival analysis, Wilcoxon tests, Mann-Whitney U tests, and Chi-squared tests. The significance level was set at P 0.05 for all statistical tests. The outcome was 'failure' in 37 cases (52.9%), 'functional survival' (at a mean follow-up of 9 years) in 15 cases (25.7%), and 'success' in 18 cases (25.7%). The median time to first complication was 32.0 months. The most common complications were debonding and fracture. Multi-retainer FRC-RBFDPs had the highest complication rates. Most FRC-RBFDPs were of good clinical quality according to FDI criteria. PHQ scores showed significantly higher clinical attachment level (CAL) (pw = 0.027) around abutments (3.40 ± 1.42/controls: 3.09 ± 1.11) and significantly greater plaque accumulation around abutments (pw = 0.008, 3.28 ± 1.03/controls: 2.83 ± 1.02) and pontics (pw = 0.001, 3.50 ± 0.99/controls: 2.83 ± 1.02) than around control teeth. Pocket probing depth (PPD) values were lower for abutments (2.43 ± 0.49) than for control teeth (2.52 ± 0.55). The opposite was true for sulcus bleeding index (SBI) scores (abutments: 0.64 ± 0.76/controls: 0.42 ± 0.71). There were no significant differences in periodontal health variables between younger and older restorations. In group comparisons, mean and median PPD, CAL, and plaque index (PI) scores for abutment and control teeth were higher in older patients than in younger patients. Based on our survival and complication data, FRC-RBFDPs can be considered short- to medium-term restorations. A 5-year survival rate of approximately 80% can be expected. The most common complications were reparable defects. Thus, repairs can prolong the survival time in many cases. Patient age had a greater effect on PHQ than restoration age. For example, FRC-RBFDPs in older patients were associated with higher levels of plaque accumulation and gingival inflammation around abutments, suggesting that older patients have greater difficulty cleaning the resin-bonded bridge area.
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). 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). 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. 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.
To evaluate the effect of a self-etching primer on the long-term bond strength stability between a leucite-based glass-ceramic and resin cement, compared to the conventional treatment involving hydrofluoric acid (HF) etching followed by silane application. Blocks of a leucite-based glass-ceramic (IPS Empress CAD) were cut into plates and embedded in acrylic resin. Half of the specimens were treated with 5% HF for 60 s and silane application, and the other half was treated with a self-etching primer (Monobond Etch and Prime, MEP). Resin cement cylinders (n = 24) were built onto their surfaces, and the specimens of each group were divided into three subgroups according to the microshear bond strength (µSBS) testing time: baseline, after 10,000 thermocycles, or after 10,000 thermocycles followed by 180 days of immersion in water. Statistical analysis was performed with two-way analysis of variance and Tukey's tests. Complementary failure mode, contact angle, and scanning electron microscopy analyses were carried out. MEP groups showed higher bond strength results than HF. HF-treated specimens exhibited a decrease in bond strength after thermocycling and water storage, while MEP-treated specimens maintained similar bond strength values across all aging conditions. Only cohesive failures within the ceramic were observed at baseline. After aging, most HF specimens exhibited adhesive failures. HF etching created more irregularities with apparent deeper defects on the ceramic surface compared to MEP. HF etching produced a lower contact angle between the ceramic surface and the water drop compared to the self-etching primer. Applying the self-etching primer resulted in higher bond strength stability between leucite-based glass-ceramic and resin cement compared to conventional treatment.
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. 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). 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). 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.
To evaluate the survival and clinical quality of individually layered indirect composite restorations (ICRs) in the mixed and permanent dentition at two study centers. A total of 155 adhesively cemented ICRs in 34 participants (aged 6 to 50 years and treated between 2008 and 2018) were evaluated for survival and clinical quality. All were individually layered restorations fabricated from laboratory sculptable composites by a specialized dental technician. Two calibrated independent investigators examined and graded each restoration as success, survival with repair, or failure based on the FDI criteria. The marginal quality and gap width of the restorations were analyzed by scanning electron microscopy. The periodontal health of treated teeth (TT) was evaluated in comparison with that of unrestored control teeth (CT) by measuring the pocket depth (PD), clinical attachment level (CAL), sulcus bleeding index (SBI), and the modified Turesky Plaque Index (TPI). A serial t-test (p 0.05) was used for statistical analysis of periodontal parameters. Success and functional survival rates were calculated using the Kaplan-Meier method. Molar incisor hypomineralization (MIH) was the most common indication for treatment (41%). The median age at treatment was 14.9 years (68%-CI: 7.7-29.5). The median service time of the restorations was 5.7 ± 3.4 years. 132 restorations were classified as a success, 21 as survival with repair, and 1 as a failure. The success rates at 1, 5, and 10 years were 95.4%, 87.4%, and 78.8%, respectively, and the corresponding functional survival rates were 100.0%, 98.9%, and 98.9%. The clinical quality, encompassing esthetic, functional, and biological criteria, was rated as excellent or good in over 90%. Periodontal response, however, was the only criterion showing worse results since restored teeth (TPI = 1.9) had significantly more plaque than CT (TPI = 1.7; p = 0.0001). No significant differences were observed in PD, CAL, or SBI. The mean marginal gap width was 135.7 µm and 63.8% of the restorations had perfect margins. ICRs are suitable for minimally invasive restoration of large tooth structure defects in the developing dentition of children and adolescents and for long-term temporary restoration of the adult dentition.
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. 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). 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). 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. Refining acidic-monomer chemistry and viscosity in SAFRCs could improve their bonding predictability.