Operative dentistry最新文献

Objective: Because the application of violet light-emitting diode (LED) light may enhance the release of reactive oxygen species, and its combination with a high-concentration bleaching agents may accelerate collagen degradation, this study aimed to evaluate its impact on the mechanical properties of demineralized dentin matrix exposed to high or low concentrations of hydrogen peroxide used in in-office treatments.

Methods: The evaluation included changes in mass, modulus of elasticity, ultimate tensile strength, hydroxyproline release, and total matrix metalloproteinase (MMP) activity. Demineralized collagen matrices were assigned to groups (n = 10): 35% hydrogen peroxide, 7.5% hydrogen peroxide, or simulated body fluid (SBF, control) with or without violet LED light. Treatments were conducted over three 30-minute sessions. During each session, violet LED light was applied in 20 cycles of 60 seconds of light, followed by a 30-second rest interval. Dentin matrix mass variation, modulus of elasticity, ultimate tensile strength after treatments, and hydroxyproline release were evaluated. Additionally, other dentin collagen matrices were evaluated for total MMP activity before and after the bleaching protocols (n = 10).

Results: Violet LED light caused a significant mass loss in the 35% hydrogen peroxide group (p = 0.007; Mann-Whitney test) compared to the other treatments. There were no significant treatment-related differences in modulus of elasticity (p = 0.527; generalized linear models). The 35% hydrogen peroxide group showed lower ultimate tensile strength and higher hydroxyproline release than the 7% hydrogen peroxide and control groups (p < 0.0001; generalized linear models). All experimental groups exhibited lower percentages of MMP inhibition than the control inhibitor group (p < 0.0001; generalized linear models).

Conclusions: Violet LED light and different in-office bleaching agent concentrations did not reduce the modulus of elasticity. Violet LED light combined with 35% hydrogen peroxide reduced dentin mass and ultimate tensile strength, and increased hydroxyproline release and total MMP collagen activity.

Introduction: Resin infiltration is an effective minimally invasive treatment for white spot lesions, but post-treatment discoloration remains a significant clinical challenge with limited evidence-based management protocols.

Objectives: This study evaluated the effectiveness of polishing and bleaching techniques in enhancing the color of resin-infiltrated teeth.

Methods and materials: Fifty caries-free, extracted permanent human teeth were randomly allocated to control and study groups (n = 25). All specimens were cleaned, sectioned mesiodistally, mounted in acrylic resin, and examined for surface imperfections. The study group underwent standardized artificial demineralization to create 50-µm white spot lesions, followed by ICON resin infiltration. Both groups completed a 30-day staining protocol with twice-daily 15-minute immersions in standardized coffee solution and brushing. Interventions included (1) mechanical polishing and (2) 14-day bleaching (9.5% H2O2 gel, 30-minute daily applications). Color changes were quantitatively assessed at baseline, post-polishing, and post-bleaching using spectrophotometry (Vita Easyshade) with CIELAB/CIEDE2000 systems and Vitapan Classical shade scores. Statistical analysis employed paired t-tests, ANOVA, and mixed ANOVA (α = 0.05).

Results: At baseline, resin-infiltrated teeth were significantly darker (lower L*) and redder (higher a*) compared to untreated controls (p < 0.005). Mechanical polishing improved color parameters in both groups and effectively minimized intergroup differences (ΔE00: 6.90 vs 6.84; p = 0.49). Bleaching produced significantly greater color change in resin-infiltrated teeth compared to controls (ΔE00 from baseline: 17.6 vs 11.4, p < 0.001). Vitapan shade scores improved significantly across sequential treatment stages (baseline, post-polishing, post-bleaching; p < 0.001), with no significant intergroup differences in final scores (p = 0.49).

Conclusions: Polishing reduced surface stains and color differences, but bleaching achieved greater whitening, especially in resin-infiltrated teeth. Together, they offer an effective approach for managing post-infiltration discoloration.

Although the effects of in-office and at-home bleaching on the surface properties of CAD/CAM monolithic materials have been extensively explored, their combined effect has not yet been investigated. This study evaluated the effects of different bleaching modalities, including a combination of in-office and at-home beaching in up to three sessions on the roughness, microhardness, and surface topography of five CAD/CAM materials. Disks of a resin nanoceramic (Lava Ultimate, Solventum, St. Paul, MN, USA), a polymer-infiltrated ceramic network (Vita Enamic, Vita Zahnfabrik, Bad Säckingen, Germany), a leucite-reinforced glass-ceramic (IPS Empress CAD, Ivoclar Vivadent, Schaan, Liechtenstein), a lithium disilicate glass-ceramic (IPS e.max CAD, Ivoclar Vivadent), and a zirconia-reinforced lithium silicate glass-ceramic (Vita Suprinity, Vita Zahnfabrik) were subjected to: 1) in-office bleaching with 35% hydrogen peroxide (Whiteness HP Blue, FGM Dental Group, Joinville, Santa Catarina, Brazil) (35% HP), 2) at-home bleaching with 10% carbamide peroxide (Opalescence PF, Ultradent, South Jordan, UT, USA) (10% CP), and 3) a combined protocol of in-office bleaching followed by at-home bleaching. Roughness arithmetical mean height (Sa) (n=12/group), microhardness (n=10/group), and topography (n=2/group) were evaluated before treatment and after the first, second, and third sessions. Data were submitted to mixed repeated measures analysis of variance (ANOVA) (α=0.05). Except for Lava Ultimate and Vita Suprinity, which showed progressive topographic alterations, 35% HP did not affect roughness, microhardness, or topography of any of the materials; 10% CP and the combined protocol caused topographic alterations in all materials. The 10% CP increased roughness of Vita Enamic (from the second session), IPS Empress CAD (from the first session), and IPS e.max CAD and Vita Suprinity (in the third session), and decreased microhardness of IPS Empress CAD (in the third session) and IPS e.max CAD (from the second session). The combined protocol increased roughness (from the second session) and decreased microhardness (in the third session) with IPS Empress CAD. The 35% HP affected the topography of Lava Ultimate and Vita Suprinity and was the safest bleaching protocol for the other materials, regardless of number of sessions. The 10% CP affected both roughness and microhardness of the materials most adversely and, together with the combined protocol, caused topographic changes to all materials.

Purpose: There is limited information in the literature regarding when overhanging restorations should be replaced, and the topic remains underexplored. Therefore, the aims of this study were to investigate, using fractal analysis, whether overhanging restorations cause microtrabecular alterations in the adjacent alveolar bone even in the absence of radiographically visible changes, and to evaluate whether the size of the overhang contributes to the extent of these bone changes.

Methods: In periapical radiographic images of 85 individuals with overhanging restorations, regions of interest (ROIs) were selected from the interdental trabecular bone adjacent to the overhanging edge and the normal side of the same tooth. Fractal dimension (FD) values were obtained using the box-counting method developed by White and Rudolph, implemented with ImageJ software version 1.52 (National Institutes of Health, Bethesda, MD, USA). Compliance with the normal distribution was analyzed using the Kolmogorov-Smirnov test. The relationship between FD values was assessed using the paired two-sample t-test and expressed using the Pearson correlation coefficient. The angle between the lines drawn from the cementoenamel junction of the tooth to the mesio-distal extreme point of the overhanging restoration and the contact point with the adjacent tooth was determined. The effect the of overhanging restoration angle on FD value was analyzed using linear regression analysis.

Results: The overhanging restorations were most commonly found in the maxillary molar regions and in disto-oclusal cavity types. The FD obtained on the overhang side was 0.99 ± 0.06, and the FD obtained on the control side was 1.04 ± 0.06. When FD on the overhang side and FD on the control side were compared using the dependent t-test, the difference between them was statistically significant (p < 0.001). The effect of angle on the FD ratio was evaluated using linear regression analysis, and no significant result was found (F = 0.072, p = 0.789).

Conclusion: According to the results of this study, overhanging restorations can cause radiographically undetectable alveolar bone loss, and this effect can be demonstrated using fractal analysis.

Objectives: Although the repair of partially defective resin composite restorations is promoted as a minimally invasive alternative to full replacement, existing evidence remains fragmented across systematic reviews with differing scopes and conclusions. This umbrella review synthesized current systematic reviews on the topic, focusing on clinical longevity, adhesive protocols, professional attitudes, and patient acceptance.

Methods and materials: A comprehensive search was conducted in five databases up to April 2025. Eligible systematic reviews assessed clinical or in vitro outcomes, patient or professional perspectives, or decision-making protocols related to resin composite repair. Methodological quality was assessed using AMSTAR 2, and study overlap was evaluated with corrected covered area (CCA). Findings were interpreted across five thematic domains using the PROPS framework (Patient-centeredness, Risk of bias, Outcomes, Protocols, Significance).

Results: Seven systematic reviews were included. A meta-analysis found no significant difference in failure rates between repaired and replaced restorations (RR= 1.21; 95% CI: 0.51-2.83), though evidence certainty was low. A network meta-analysis of laboratory studies identified that diamond bur + silane + adhesive yielded the highest bond strength (mean: 24.5 MPa). Surveys reported high patient acceptance (> 86%) and professional endorsement of repair, yet only 31.3% of defective restorations were repaired. Standardized decision-making tools were lacking.

Conclusions: Repair is a clinically sound, conservative option that can offer outcomes comparable to full replacement when appropriately indicated and proper protocols are used. Broader implementation requires guideline standardization, clinical training, and studies incorporating patient-reported outcomes and cost-effectiveness.

Purpose: Low-temperature plasma (LTP) has been used as an option for dentin surface treatment prior to adhesion due to its antibacterial effect without causing substantial changes to the dentin surface. However, few studies have reported the influence of argon combined with oxygen on the degree of conversion of resin cements or the adhesive luting procedure. Thus, this study aimed to evaluate the effect of LTP pretreatment of dentin on the degree of conversion of resin cements, as well as the effect on bond strength to dentin of different adhesion luting protocols.

Methods and materials: The dentin surfaces of 72 sound human molars were exposed. Specimens were divided into three groups according to LTP pretreatment (argon-based LTP, argon/oxygen-based LTP, and no LTP application). These groups were then divided into three subgroups (n = 8) and resin composite blocks (Te-Econom Plus, Ivoclar Vivident) were cemented to the dentin according to one of three adhesive luting protocols (Single Bond 2 [Solventum] + RelyX ARC [Solventum], Single Bond Universal [Solventum] + RelyX Ultimate [Solventum], and RelyX U200 [Solventum]). Microtensile bond strengths were measured before and after thermocycling (10,000 cycles between 55°C and 5°C). Degree of conversion was measured using a Raman spectrometer (Senterra, Bruker Optik GmbH). All data were submitted to ANOVA and Tukey post hoc tests (α = 0.05).

Results: RelyX ARC exhibited higher dentin bond strength than RelyX U200 regardless of LTP treatment. RelyX Ultimate showed intermediate bond strength and higher degree of conversion than the other materials. The application of argon-based LTP resulted in bond strength and degree of conversion similar to those of the control group for all cements used. The addition of oxygen to argon to generate LTP resulted in lower bond strength, especially when RelyX U200 was used.

Conclusion: The application of Argon plasma did not cause any damage to the adhesive interface. However, neither Argon alone nor the addition of oxygen to argon to generate LTP was beneficial for the properties evaluated.

Background: Immediate dentin sealing (IDS) has been widely used to enhance adhesive bonding in indirect restorations. However, the influence of different bonding agents, temporary materials, and surface cleansing protocols on shear bond strength (SBS) remains unclear. Previous studies have reported conflicting results, and no consensus exists on the optimal combination of these factors for maximizing adhesive performance. This study aimed to evaluate how these variables affect SBS in IDS-based restorations.

Methods: Occlusal dentin surfaces of 80 human third molars were prepared and treated with either an etch-and-rinse adhesive (OptiBond FL, Kerr, Orange CA, USA) or a universal adhesive (G2 Bond, GC Corporation, Tokyo, Japan) to create an IDS layer. Specimens were then divided based on the type of temporary material used: eugenol-free cement (TempBond NE, Kerr) or resin-based material (Structur 2 SC, Voco GmbH, Cuxhafen, Germany). After 24-hour water storage, temporary materials were removed using either airborne aluminum oxide (Al2O3) particle abrasion or waterborne Al2O3 particle abrasion (AquaCare, Velopex, London, UK). Ceramic discs were cemented with resin cement, and SBS was measured using a universal testing machine. Failure modes were analyzed under a stereomicroscope, and structural changes on dentin surfaces were examined using scanning electron microscopy (SEM). Data were analyzed using three-way ANOVA with Bonferroni post hoc tests (α = 0.05).

Results: Three-way ANOVA revealed a significant interaction among adhesive system, temporary material, and cleansing method (p < 0.001). Due to this interaction, only select pairwise comparisons were interpreted. The highest SBS was observed in the OptiBond FL-Structur 2 SC-AquaCare group, significantly higher than all other combinations (p < 0.05). AquaCare-treated groups consistently outperformed air-abraded groups in bond strength (p < 0.001). Within the air-abraded subgroup, G2 Bond Universal-Structur 2 SC yielded significantly higher SBS than G2-TempBond NE and OptiBond FL-Structur 2 SC (p < 0.05). Failure mode analysis showed a predominance of mixed failures across groups, with no significant differences among failure types (p = 0.729).

Conclusion: Cleansing method, adhesive system, and temporary material significantly and interactively influenced SBS in IDS-based restorations. AquaCare waterborne Al2O3 abrasion consistently yielded higher bond strengths than conventional Al2O3 air abrasion. The highest SBS was achieved with the combination of OptiBond FL-Structur 2 SC-AquaCare. These findings highlight the importance of optimizing all procedural steps to enhance bonding effectiveness.

Bond strength tests are used as predictors of the clinical longevity of dental restorations. However, the aging of bond strength specimens is often simulated with static water storage, even though the saliva flows over teeth and restorations in the mouth. This study investigated the effect of water under static and flow conditions on the bond strength between zirconia and tooth structure using different test designs. Ninety human molars with prepared flat dentin surfaces were randomly divided into three groups according to the test design: Tensile, Shear, and Crown pull-off. The Crown pull-off group received additional standard full crown preparations. Zirconia specimens milled according to the shape of each test design (n=30) were bonded to the tooth structure using resin cement. There were three subgroups (n=10) according to the artificial aging procedure: NA - no aging (24 hours); SW - static water (30 days); FW - water flow (30 days). Bond strength was assessed using a universal testing machine, and the load at failure was recorded. Data were analyzed using two-way ANOVA and Tukey post hoc tests (α=0.05), and the mode of failure was also classified. Two-way ANOVA revealed a significant effect of the test design (p<0.001). However, no effect was observed for the aging procedure (p=0.166). The interaction aging*test design was significant (p=0.019). FW significantly decreased the retention of zirconia crowns to tooth structure (p<0.05) but did not affect the other test design specimens. The mode of failure was adhesive (100%) at the zirconia/cement interface for all specimens and aging conditions, except for Crown pull-off / FW, which were predominantly mixed (60%). FW negatively affected the retention of Y-PSZ crowns to the tooth structure.