Restorative Dentistry & Endodontics最新文献

Objectives: The objective of this study was to evaluate the effects of transformational temperatures on the cyclic fatigue resistance at body temperature of reciprocating file systems: R motion (RM), Procodile Q (PQ), and Reciproc Blue.

Methods: Resistance test was done in a custom-made device at room (20°C ± 1°C) and body (37°C ± 1°C) temperatures within a 60° angle of curvature and 5 mm radius of the artificial canal. The time to fracture (TTF) was recorded. The scanning electron microscope observation and differential scanning calorimetry analyses were performed. Two-way analysis of variance and Tukey post-hoc comparison were applied at a significance level of 0.05.

Results: The results showed a significant influence of temperature on instrumental breakage, regardless of the file systems (p < 0.05). The TTF is significantly decreased at body temperature (p < 0.05). PQ showed the longest TTF in both temperature conditions (p < 0.05). RM demonstrated a significantly higher TTF reduction ratio compared to the other files (p < 0.05).

Conclusions: Within the limitations of this study, the heat-treated files with reciprocating kinetics may have different reduction ratios of the fatigue resistance of the file systems under different temperature conditions. This characteristic is an important point of consideration when clinicians select the file system to reduce potential file fracture.

Objectives: This study aimed to analyze the temperature changes during the light curing of conventional flowable composite resin and bulk-fill composite resin of various thicknesses using an infrared thermographic camera.

Methods: Flowable composite resin (G-aenial Flo, GC Co.) and bulk-fill composite resin (SDR, Dentsply Caulk) were used. Specimens with thicknesses from 0.5 mm to 5.0 mm were prepared. The infrared thermographic camera measured the temperature changes at the maximum temperature rise point during light curing. The data were analyzed for maximum temperature, time to peak temperature, and temperature rise patterns.

Results: For G-aenial Flo, the maximum temperature tended to decrease with increasing thickness, whereas for SDR, the maximum temperature decreased up to 2.0 mm and then remained relatively consistent from 2.0 mm to 5.0 mm. At thicknesses of 1.5 mm or less, both resins showed a rapid temperature increase within the first 5 seconds, followed by a reduced rate of increase up to 80 seconds. At thicknesses of 2.0 mm or greater, the temperature peaked and then gradually decreased. Across all thicknesses, SDR was observed to reach peak temperature more rapidly than G-aenial Flo.

Conclusions: Observable differences in polymerization dynamics were identified between the two resin types, particularly at greater thicknesses. Although no statistical analysis was performed, these descriptive findings suggest that infrared thermographic cameras may be useful for indirectly assessing polymerization dynamics during resin polymerization.

Objectives: This study evaluated the ability of calcium silicate cement (CSC) as a remineralizing agent compared with conventional glass ionomer cement (GIC) and resin-modified GIC (RMGIC) to remineralize artificial caries-affected dentin.

Methods: Twenty-five class V cavities were prepared on extracted human third molars. Twenty teeth underwent artificial caries induction. The remaining five teeth with sound dentin serve as the positive control. The twenty demineralized teeth were subdivided into four groups (n = 5): carious dentin without restoration (negative control [NC]), carious dentin restored with CSC (Biodentine, Septodont), carious dentin restored with GI (Fuji IX, GC Corporation), and carious dentin restored with RMGIC (Fuji II LC, GC Corporation). Following restoration, the specimens were stored in artificial saliva for 7 days. The elastic modulus was evaluated by a nanoindentation test. The mineral composition was analyzed by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and the mineral composition at the dentin-material interface.

Results: CSC had a higher modulus of elasticity compared to GI, RMGI, and NC groups (p < 0.05). Higher calcium and phosphorus content was observed under CSC restorations, as indicated by SEM-EDX examination, which may lead to better remineralization.

Conclusions: Compared to GI and RMGI, CSC showed the best remineralization and mechanical reinforcement in caries-affected dentin, indicating CSC for use in minimally invasive restorative dentistry.

Objectives: The study aimed to investigate how environmental conditions impact the setting time and microhardness of premixed calcium silicate-based sealers.

Methods: The setting time and microhardness of three sealers (Endoseal MTA [MARUCHI], One-Fil [MEDICLUS], and Well-Root ST [VERICOM]) were evaluated under four environmental conditions: unsoaked, distilled water-soaked, phosphate-buffered saline-soaked, and pH 5-soaked gypsum molds (n = 12/group/condition). The setting time was measured with Gilmore needles, and microhardness was assessed using a Vickers tester after 3 days. Welch's analysis of variance and Games-Howell post hoc tests were used for statistical analysis.

Results: The sealer type and environmental conditions significantly influenced setting time and microhardness (p < 0.001). The initial and final setting times were the shortest in the unsoaked samples. For Endoseal MTA and One-Fil, the unsoaked condition exhibited significantly shorter setting times than the soaked conditions. Well-Root ST exhibited significantly longer setting times in acidic conditions. Surface microhardness was highest in the unsoaked group (p < 0.001). Among the soaked groups, the phosphate-buffered saline-soaked group had the lowest hardness for Endoseal MTA, whereas the pH 5-soaked group exhibited the lowest hardness for One-Fil and Well-Root ST. Endoseal MTA consistently demonstrated a lower microhardness than the other sealers (p < 0.001).

Conclusions: Moisture, pH, and solution chemistry influenced the setting time and microhardness of premixed calcium silicate sealers. Although acidic conditions generally prolong the setting time and reduce hardness, the effects vary based on the sealers used and the setting environment.

Objectives: This study fabricated and characterized a resolvin E1 (RvE1)-loaded carboxymethyl chitosan (CMC) scaffold and determined its cytotoxicity and mineralization potential on inflamed human dental pulp stem cells (hDPSCs).

Methods: CMC scaffold incorporated with two concentrations of RvE1 (100 and 200 nM) was fabricated and characterized. The scaffolds' porosity, drug release kinetics, and degradation were assessed. The impact of RvE1 on inflamed hDPSCs proliferation, proinflammatory gene expression (tumor necrosis factor alpha [TNF-α]), alkaline phosphatase activity, and alizarin red S staining was evaluated.

Results: Scanning electron microscopy analysis demonstrated a highly porous interconnected microstructure. Release kinetics showed gradual RvE1 release peaking at day 14. Cumulative degradation of the CMC scaffold at 28 days was 57.35%. Inflamed hDPSCs exposed to 200 nM RvE1-CMC scaffold exhibited significantly improved viability compared to 100 nM. Both RvE1-CMC scaffolds significantly suppressed the expression of TNF-α at 7 days. Alkaline phosphatase activity was enhanced by both RvE1 concentrations on days 7 and 14. Alizarin red staining revealed superior mineralization potential of 200 nM RvE1 on days 14 and 21.

Conclusions: This study concludes 200 nM RvE1-CMC scaffold is a promising therapy for inflamed pulp conditions, enhancing cell proliferation and biomineralization potential in inflamed hDPSCs.

Objectives: This study aimed to evaluate whether continuous irrigation with larger volumes or allowing sodium hypochlorite (NaOCl) resting time is more critical for pulp tissue dissolution using a controlled artificial root canal system.

Methods: A three-dimensional printed artificial root canal with a lateral canal in the apical third was fabricated. Standardized bovine pulp tissue specimens were inserted, and three irrigation protocols were tested: group A (continuous NaOCl irrigation at 1 mL/min via syringe pump), group B (intermittent NaOCl irrigation with 0.1 mL and a 3-minute resting period), and group C (control, saline irrigation). The time for complete dissolution and the total NaOCl volume were recorded.

Results: Complete dissolution occurred in groups A and B, with significant differences in NaOCl volume and time (p < 0.05). In group A, complete dissolution was consistently observed after the 6th irrigation cycle, corresponding to a total NaOCl volume of 6.0 ± 0.66 mL per test. The average time required for complete dissolution in this group was 6 ± 0.66 minutes. In group B, complete dissolution occurred after the 4th cycle, with a total NaOCl volume of 0.4 ± 0.06 mL per test and a mean dissolution time of 12.6 ± 1.8 minutes.

Conclusions: NaOCl volume and exposure time significantly influence pulp tissue dissolution.

Objectives: The aim of this study was to compare the remineralizing capacity of bioactive glass (BGS-7, CGBIO) with other agents.

Methods: Twenty caries-free third molars were sectioned and demineralized. Specimens were divided into four groups: (1) control, (2) Clinpro XT varnish (Solventum), (3) 1.23% acidulated phosphate fluoride gel, and (4) a new type of CaO-SiO2-P2O5-B2O3 system of bioactive glass ceramics (BGS-7). Agents were applied and stored in simulated body fluid at 37℃ for 2 weeks. Microhardness was measured using the Vickers hardness testing method. Five specimens per group were analyzed using quantitative light-induced fluorescence (QLF) to assess mineral loss. Field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to examine the surface morphology and elemental composition. Data were analyzed using paired t-test and one-way analysis of variance (p < 0.05).

Results: BGS-7 showed the highest microhardness values and the greatest recovery in QLF analysis (p < 0.05). FE-SEM revealed granular precipitates on demineralized enamel in the BGS-7 group. EDS confirmed the presence of newly formed silicon and fluoride layers.

Conclusions: BGS-7 demonstrated superior remineralization capacity compared to other agents, suggesting its potential as an effective remineralizing material.

Objectives: This in vitro study aimed to evaluate temperature variation on the external surface of mandibular molars and within ultrasonic inserts when using adapter-coupled versus one-piece inserts.

Methods: Twenty-four extracted human mandibular molars were divided into two groups based on the type of ultrasonic insert used: adapter-coupled and one-piece inserts. Temperature on the external surface of each tooth was measured with a thermocouple probe positioned in the furcation area, capturing data continuously. The temperature of the ultrasonic inserts was monitored in real-time using a thermal imaging camera. Measurements were taken in a controlled environment without cooling for over 120 seconds. Statistical analysis was conducted using analysis of variance (ANOVA) and two-way ANOVA with repeated measures to evaluate temperature variations between groups and over time, with significance set at 5%.

Results: In the external tooth surface temperature measurements, no significant differences were observed between the groups during the initial 15 seconds (p = 0.185) and 30 seconds (p = 0.067). However, significant differences emerged at 60 seconds (p = 0.025), 90 seconds (p = 0.024), and 120 seconds (p = 0.020), with the one-piece insert group demonstrating higher temperatures in the furcation region. Thermal imaging of the inserts revealed a significant difference at all time points (p < 0.001), with adapter-coupled inserts showing greater heating.

Conclusions: The use of ultrasonic inserts leads to a gradual rise in temperature on the external tooth surface. One-piece inserts generated higher temperatures on the tooth, while adapter-coupled inserts exhibited greater heating within the insert.

Objectives: This study evaluated the efficacy of three distinct bleaching agents over time on blood-stained, devitalized teeth. Furthermore, the recoloring subsequent to bleaching will be monitored.

Methods: The study was conducted on 60 caries-free, unfilled, upper human incisors. The Freccia and Peters blood staining technique was employed, and four groups (n = 15) were identified: control, 35% hydrogen peroxide-treated, 37% carbamide peroxide-treated, and sodium perborate-treated groups. Color differences were measured using ΔE00, ΔWID, L*, a*, and b* values. To investigate tooth discoloration after bleaching, 10 unbleached teeth with three groups of 10 bleached teeth were compared by vine staining. The group of bleached teeth was restored immediately, another group waited one week, and the third group had sodium ascorbate applied and analyzed using one-way analysis of variance tests (p < 0.05).

Results: Among the groups, carbamide peroxide exhibited the most significant whitening during the 6-day bleaching process, followed by hydrogen peroxide and sodium perborate. Subsequent examination of the wine recoloring of post-bleaching samples demonstrated that bleached teeth exhibited a heightened propensity for recoloration in contrast to unbleached teeth. Notably, sodium ascorbate treatments for hydrogen peroxide neutralization and the wait-and-restore approach were not statistically significant in terms of preventing recoloration.

Conclusions: Sodium perborate is less effective and more time-consuming than hydrogen peroxide or carbamide peroxide for bleaching purposes. Carbamide peroxide is the most effective bleaching agent. The sodium ascorbate treatment and the wait-and-restore approach are ineffective in preventing recoloring. Bleached teeth have more discoloration than unbleached teeth.

Objectives: This study aimed to assess the effect of cross-section geometry on the mechanical properties of nickel-titanium (NiTi) instruments by comparing two instruments with identical tip size, taper, and thermal treatment but differing in cross-section design.

Methods: One hundred four NiTi rotary instruments, being S-shaped and triangular cross-section, manufactured with Blueish thermal treatment, were tested (n = 52 per group). Differential scanning calorimetry was employed, and the metal mass volume and cross-section area were assessed. The cyclic fatigue, torsional, and bending resistance tests were assessed. Data were analyzed using the Kolmogorov-Smirnov and Student t tests, and the level of significance was set at 5%.

Results: The instruments exhibited similar start and finish temperatures of phase transformation. The S-shaped instruments had significantly lower metal mass volume and cross-sectional area (p < 0.05). S-shaped instruments demonstrated superior cyclic fatigue resistance, greater angular deflection, and lower bending stiffness (p < 0.05).

Conclusions: Cross-section geometry significantly influences the mechanical properties of NiTi rotary instruments.