The effectiveness of endodontic disinfection largely depends on the ability of sodium hypochlorite (NaOCl) to penetrate deeply into dentinal tubules, particularly in the apical third, where the anatomy is more complex and mechanical access is limited. Sonic and ultrasonic activation techniques have been proposed to enhance this penetration by generating dynamic fluid movement. Aim: To evaluate and compare the depth of penetration of 5.25% NaOCl into dentinal tubules using passive ultrasonic irrigation (PUI; NSK Varios 370) and sonic activation (SIM; EQ-S Metabiomed), in comparison to conventional needle irrigation. Materials and Method: thirty-six extracted human single-rooted premolars were instrumented to working length with ProTaper Gold F3. The teeth were randomly assigned to three groups (n = 12): PUI, SIM, and control. A standardized final irrigation protocol was performed, followed by the application of 1% methylene blue, activated or not, according to the group. Three transverse sections were obtained from each tooth (coronal, middle, and apical), and penetration depth was measured using ImageJ image analysis. Data were analyzed with non-parametric tests (Mann–Whitney U; p < 0.05). Results: Both PUI and SIM showed significantly greater penetration depths than the control group in all three thirds of the canal (p < 0.05). No significant difference was found between PUI and SIM (p > 0.05). The greatest penetration was observed in the coronal third, followed by the middle and apical thirds in all groups. Conclusions: Ultrasonic and sonic activation techniques produced greater marker penetration into dentinal tubules compared to conventional irrigation. Furthermore, the EQ-S system yielded similar results to those obtained with ultrasonic activation, with no statistically significant difference between the two systems.
Composite resin has been extensively used as a direct restorative material to restore posterior teeth due to its low cost and more complete preservation of the tooth than conventional resin. Nanohybrid resins are a popular alternative due to their apparently better mechanical strength and aesthetic properties compared to conventional resins. However, their clinical performance is still under evaluation. Adding small amounts of graphene oxide (GO) could improve the physicochemical properties of these resins. Aim: The purpose of the current study was to evaluate the effects on the morphological and physicochemical properties of nanohybrid composite resins when GO is added to them. Materials and Method: Three kinds of composite resin (Universal Nanohybrid Restorer 3M Filtek Z250 XT) were evaluated: G0, without GO; G1, composite resin with 0.01% GO; and G2, composite resin with 0.02% GO. Surface morphology and physicochemical characterization were analyzed for all three groups. Data were submitted to analysis of variance, followed by post hoc Tukey’s tests at a significance level of p < 0.05. Results: The addition of GO did not modify the surface of the composite resin compared to the control. The peak of the GO spectrum obtained by FTIR was very small and almost imperceptible due to the close combination of graphene molecules with the rest of the material. Flexural strength increased significantly in group G1, but decreased in G2 compared to the control group. Both GO concentrations resulted in a significant increase in resistance to wear compared to the control group. Conclusions: The addition of graphene oxide did not modify the surface morphology of the nanohybrid compound resin evaluated. However, it did produce changes in mechanical properties: resistance to wear increased significantly at both concentrations studied, while flexural strength changed in a concentration-dependent manner. These results suggest that low concentrations of GO may contribute to improving certain physicochemical properties of nanohybrid compound resins.
The biomechanical rehabilitation of endodontically treated premolars with extensive mesio-occluso-distal (MOD) cavities is a clinical challenge due to their increased susceptibility to fracture. The aim of this in vitro study was to compare the compressive strength of endodontically treated mandibular premolars restored using different post-endodontic reconstruction protocols, using intact teeth as a reference for maximum mechanical performance. Materials and Method: Forty single-rooted premolars were distributed into four groups: one control group with no interventions, and three experimental groups with standardized mesio-occluso-distal (MOD) preparations. Experimental groups were restored respectively with core buildup, glass fiber posts, and polyethylene fiber reinforcement. After final composite resin restoration, specimens were tested for compressive strength using an INSTRON 1011 universal testing machine. Data were analyzed using the Kruskal–Wallis test (p<0.05). Results: When examining median (95%CI) compressive strength in Newtons (N), the highest value was found in the control group with 557.4 N (100.8-574.8), followed by the polyethylene fiber group with 471.4 N (194.2 to 565.5), the glass fiber posts group with 427.5 N (146.3 to 495.4) and the core buildup group with 345.1 N (216.8 to 574.9), (p = 0.84). Conclusion: Under the experimental conditions of the present study, the compressive strength of endodontically treated mandibular premolars did not differ significantly among the evaluated reconstruction protocols. Although polyethylene fiber reinforcement showed a tendency toward higher resistance values, the results do not enable the establishment of conclusive mechanical advantages among the restorative systems assessed.
Aim: This study analyzes the development of mandibular condyles and its likely impact on the direction of mandibular displacement during maxillofacial development in a ketogenic diet model in growing rats. Materials and Method: Twenty male Wistar rats, weaned at 21 days, were assigned to one of the following groups: control (fed a regular hard diet ad libitum) and experimental (fed a ketogenic hard diet, ad libitum). After 30 days of diet, ketonemia was determined and animals were euthanized. The mandibles were resected, hemisected at the symphysis and fixed in 10% formalin. Remaining soft tissues were removed. Metallic landmarks were placed in the mandibular foramens of one hemimandible of each rat. The hemimandibles were radiographed and cephalometric study was performed on paper tracings of the projected image of the radiographs. Data obtained were analyzed with Student’s “t” Test. Results: Food consumed was lower in the experimental group. Body weight was 179±1 g in controls, and 128±11 g in the experimental group, p<0.05. Ketonemia was 0.29±0.042mmol/l in controls and 1.89±0.7 mmol/l in the experimental group, p<0.05. Condylar process length and angular process convexity were significantly lower in the experimental group. Conclusions: These results suggest that the ketogenic diet alters the development of the condylar process and the angle of the mandible in rats, promoting a dolichofacial growth pattern.
Knowledge of the timing and sequence of permanent tooth eruption is essential for assessing occlusal development and providing population-specific reference standards to support diagnosis, prevention, and treatment planning. AIM:To estimate mean age for eruption of permanent teeth, except third molars, in children in Buenos Aires City (CABA), compare means according to sex, jaw and laterality, and identify the eruption sequence per arch. MATERIALS AND METHOD:An observational, prospective, cross-sectional study was conducted (March-July 2024) on 4- to 15-year-old children who received care at Buenos Aires University's School of Dentistry and at four private offices in Buenos Aires City. A tooth was considered erupted when at least one cusp or incisal edge pierced the gingival epithelium. Mean ages were estimated using the Kärber method with 95 % confidence intervals (CI), and the sequence was established by placing those means in order. RESULTS:We evaluated 1,063 children (532 female), mean age 9.9 ± 2.6 years. The first teeth to erupt were lower central incisors, and the last were upper second molars. No difference was observed between hemiarches. Teeth belonging to the lower incisor-canine group erupted significantly earlier than their homologous upper teeth. Girls presented earlier eruption than boys, with significant differences for all teeth except upper central incisors, and upper and lower first molars. Sequence for the upper jaw was 6-1-2-4-3-5-7 in girls, and 6-1-2-4- 5-3-7 in boys. Sequence in the mandible was 1-6-2-3-4-5-7 in girls, and 1-6-2-4-3-5-7 in boys, with chronological proximity between canine and premolars in some comparisons. CONCLUSION:In this sample, eruption began with lower central incisors, was symmetrical, earlier in girls, and earlier in the lower incisor-canine group, with sequential stability in both sexes during the first transitional period, and variations in the second.
