Journal of Conservative Dentistry最新文献

Background: Decision-making regarding whether cuspal coverage is required or not for the restoration of root canal-treated posterior teeth is still a matter of challenge for the dentist.

Methodology: Four models of endodontically treated mandibular molars with mesio-occlusal (MO) cavity were designed and simulated with direct composite resin restorations. Group 1A - cavity width <½ the intercuspal distance restored without cuspal coverage, Group 1B - same as Group 1A but with cuspal coverage, Group 2A - MO cavity width >½ but <2/3^rd the intercuspal distance restored without cuspal coverage, and Group 2B - same as Group 2A but with cuspal coverage. The models received occlusal load to simulate a mastication load. Static finite element analysis (FEA) was adopted for predicting the stress distribution generated in the restored tooth by the loading condition.

Results: FEA of the models have shown that the variations in stress values were significant in bulk-fill material compared to enamel and other structures. Comparing the maximum and minimum principal stress values in the overall region demonstrated that 2A was safer, whereas 2B was found to be the worst case.

Conclusions: The results indicate that restoration of endodontically treated mandibular molar with loss of one marginal ridge with composite resin without cuspal coverage revealed minimal internal stress values and showed the best performance overall.

Background: Incomplete monomer infiltration into the etched dentin causes postoperative sensitivity (POS) with total-etch adhesives. Increasing the temperature of the air to dry the adhesive has shown to improve its infiltration into the dentin.

Aims: The aim of this research is to evaluate the effectiveness of dry air temperatures of 15°C ± 5°C and 50°C ± 5°C on the POS, depth of penetration, and bond strength of an ethanol/water-based etch-and-rinse (ER) adhesive under in vivo and in vitro conditions.

Methods: Forty-four premolars from 11 patients scheduled for orthodontic extraction were allocated into cold air (Group 1) and warm air (Group 2) groups using a split-mouth design. A 2 mm × 2 mm × 2 mm cavity was prepared on the middle third of the buccal surface of the teeth, acid etched, and two coats of an ethanol/water-based adhesive resin mixed with 0.1% rhodamine B was applied for 10 s. A dental air gun customized to deliver warm and cold air was used to dry the adhesive prior to its light polymerization. The cavities were restored with resin composite incrementally. POS was assessed using visual analog scale at 24 and 72 h using cold test. The teeth were atraumatically extracted and analyzed for depth of adhesive penetration using confocal laser scanning microscope (n = 11) and push-out bond strength (n = 11).

Statistical analysis used: The data were analyzed using sample t-test and Wilcoxon signed-rank test (P < 0.05).

Results: A significantly lower POS and greater adhesive penetration into the dentin was observed in the warm air group compared to cold air (P < 0.05). No significant difference could be elicited between the push-out bond strength of both the groups (P > 0.05).

Conclusions: Warm air alleviated POS and improved the penetration of an ethanol/water-based ER adhesive into the dentin.

Background: This study aimed to evaluate the pH and calcium ions (Ca²⁺) release from two tricalcium silicate-based sealers (Sealer Plus BC and Bio-C Pulpecto) through roots of primary teeth.

Methods: Forty root canals of primary incisors were prepared and distributed into four groups according to the filling material: G_PlusBC (Sealer Plus BC); G_BioC (Bio-C Pulpecto); G_Ultra (Ultracal); and G_C (no filled). pH measurement was performed with a digital pH meter, and the Ca²+ release was measured in an atomic absorption spectrophotometer at baseline, 24 h and 1, 2, 3, and 4 weeks later. The data were analyzed using two-way ANOVA and Tukey's post hoc tests.

Results: The results did not reveal significant differences between the groups in terms of pH in 24 h, 1-, and 2-weeks' periods. After 4 weeks, there was a significant difference, with the highest mean pH values in G_Ultra, followed, respectively, by G_PlusBC and G_BioC. Regarding the Ca²+ release, the G_Ultra showed greatest mean values at all evaluated times, and the other groups showed no difference between them.

Conclusion: Both sealers were able to promote the elevation of the pH and Ca²+ release through roots of primary teeth, which brings favorable properties for their use as a filling material.

Background: Rotary nickel-titanium files have become the most commonly used engine-powered endodontic instruments due to their improvement in fatigue resistance and flexibility. The autoclaving is the most commonly used method for sterilization. However, the risk of instrument fracture, mainly due to cyclic fatigue during rotation within a curved canal, is still a matter of critical concern.

Aims: This study aimed to measure and compares the cyclic fatigue resistance of EdgeFile X7, 2Shape, and F-One files in a single curved simulated canal before and after autoclave sterilization.

Materials and methods: Twenty-four files each of EdgeFile X7, 2Shape, and F-One files were used in this study. They were grouped as group A: EdgeFile X7, group B: 2Shape, and group C: F-One files. Then, each group was subdivided into two, sterilized and nonsterilized, subgroups. The files were tested using a custom-made artificial canal. The number of cycles to fracture (NCF) was calculated.

Statistical analysis used: One-way analysis of variance, post hoc Tukey's test, and independent t-test were used.

Results: In nonsterilized instruments, the NCF of the EdgeFile X7 group was significantly higher than that in the other groups (P < 0.05). In sterilized instruments, there was a nonsignificant difference in NCF between EdgeFile X7 and F-One files (P > 0.05). The NCF of 2Shape was significantly lower than other files (P ≤ 0.05) in sterilized and nonsterilized groups. The autoclaving significantly decreased (P ≤ 0.05) the cyclic fatigue resistance of the tested files.

Conclusions: EdgeFile X7 was the most fatigue resistant. Autoclaving reduced the cyclic fatigue resistance of the tested files.

Aim: The aim of the present study was to compare the incidence of postoperative pain in single sitting root canal treatment after using two reciprocating and two continuous rotating file systems.

Methodology: One hundred and four permanent mandibular canine and first premolar teeth were selected for the study and were divided into two groups 1 and 2 comprising 52 teeth each. Group 1 was treated using reciprocating file systems and was subdivided into two subgroups A and B using WaveOne Gold (WOG) and Reciproc Blue (RB), respectively. Group 2 was treated using continuous rotating file systems and was divided into two subgroups A and B using One Curve (OC) and Vortex Blue (VB), respectively. Treatments were performed in a single sitting. After the visit, the patients were given a prescription for ibuprofen 400 mg to be taken every 6 h if they experience pain. Participants were asked to rate the intensity of the postoperative pain on a visual analog scale according to four classes (no pain, mild pain, moderate pain, and severe pain) after 24 h, 48 h, 72 h, and 7 days. Patients were also asked to record the number of prescribed analgesic medication tablets taken at these time points.

Results: There was a statistically significant difference (P = 0.00) among the reciprocating file systems and continuous file systems regarding the incidence of postoperative pain after 24, 48, and 72 h which signifies that pain incidence and duration is less with respect to reciprocation instrumentation as compared to continuous instrumentation.

Conclusion: The use of Reciproc instrumentation system (WOG and RB) showed significantly less intensity and duration of posttreatment pain compared to the single-file rotary system (OC and VB) in patients with symptomatic irreversible pulpitis with apical periodontitis.

Aim: This study evaluated the effect of three collagen cross-linking agents - proanthocyanidins (grape seed extract [GSE] and green tea extract [GTE]) and glutaraldehyde [GA] on microshear bond strength (μSBS) of caries-affected dentin (CAD)-resin complex.

Materials and methods: Freshly extracted 96 teeth with caries up to the middle third of dentin were sectioned through the deepest part of the occlusal fissure, perpendicular to the long axis of the crown. Caries was excavated with large round bur until firm dentin was obtained, confirmed by visual inspection and tactile examination. Flat occlusal dentin surfaces were treated as follows: Group-1 - 6.5% GSE (n = 30), Group-2 - 2% GTE (n = 30), Group-3 - 5% Glutaraldehyde (n = 30), Group-4 - control group (no agents) (n = 6). Each group was further divided into Subgroup A - Etch-N-Rinse 15s, Subgroup B - Etch-N-Rinse 45s, and Subgroup C - Self-etch. Two increments of 1.5-mm thick composite (Tetric-N-Ceram - Ivoclar Vivadent) with a 1-mm diameter were built-up. Each sample was subjected to μSBS test in Universal Testing Machine. Student's t-test was done for intragroup comparison and one-way ANOVA for intergroup comparison.

Results: Statistically significant difference was present in mean μSBS, with Group 1B showing the best results and Group 4C, the least.

Conclusions: Thus, the application of these collagen cross-linkers, to CAD, increases μSBS and promises a new approach to improve dentin bond strength.

Aims and objectives: The objective of this study was to compare surface roughness of a nano-spherical resin composite using four different multi-step polishing disc systems at five different speeds.

Materials and methods: In total, 154 discs samples were prepared using a supra-nano spherical resin composite. The samples were divided into negative and positive control groups and the following four finishing and polishing disc systems: Sof-Lex, Bisco Finishing Discs, OptiDisc, and Super-Snap. Each polishing disc system was applied at five different speeds (2000, 5000, 10,000, 15,000, and 20,000 revolutions per minute [RPM]) (n = 7). The surface roughness of samples was measured using a profilometer. One sample from each group was evaluated by scanning electron microscopy and atomic force microscopy. Two-way analysis of variance was used to evaluate the average roughness (Ra) data from the profilometric experiments using statistical software (GraphPad Prism4-GraphPad Software; La Jolla, CA, USA). The mean values were compared using the Bonferroni test (P = 0.05).

Results: The mean roughness ranged from 0.07 μm to 0.41 μm. The smoothest surfaces were obtained with OptiDisc at 20,000 RPM and Super-Snap at 20,000 RPM. The Bisco Finishing Discs group at 2,000 RPM showed the highest surface roughness values. For all polishing systems, the roughness at 20,000 RPM was lower than that at other speeds.

Conclusion: Within the limitations of the present in vitro study, it can be concluded that the polishing performance was in the following order: Super-Snap > OptiDisc > Sof-Lex > Bisco Finishing Discs. In addition, the surface roughness decreased as the polishing speed increased.

Aim: To compare the microleakage of Filtek bulk fill posterior and Beautifil II LS composites in Class II cavities using stereomicroscope.

Materials and methods: A total of 34 extracted teeth were randomly divided into two groups. Teeth were prepared and mounted on a plaster block. In each tooth, Class II cavities were prepared, following which the cavities were etched and bonded. In Group I, 17 teeth were restored with Filtek bulk fill posterior composite in bulk fill technique and in Group II, 17 teeth were restored with Beautifil II LS following manufacture's instructions. The samples were then thermocycled and then the tooth were immersed in 1% methylene blue for 24 h and were divided into two halves mesiodistally using a diamond disc at low speed. Then, all the sections were observed under a stereomicroscope at ×10 magnification.

Results: Mann-Whitney U-test displayed a statistically significant higher mean rank among Filtek bulk fill group (mean rank = 23.09) when compared to Beautifil II LS composite group (mean rank = 11.91).

Conclusion: The study concluded that in Class II restorations, Beautifil II LS showed significantly less microleakage than Filtek bulk fill posterior.