RESUMO
BACKGROUND: Teeth with severe crown destruction and endodontically treated may or may not present a circular strip of dental tissue located in the cervical region called ferrule. AIMS: The aims of this study were to evaluate ferrule thickness influence on endodontically treated teeth (ETT) resistance to fracture. MATERIALS AND METHODS: A total of 30 bovine incisor teeth were selected, endodontically treated and randomly distributed, according to the ferrule thickness: G1- no ferrule, G2 - 1 mm, and G3 - 2 mm. All the teeth were restored with prefabricated posts and composite resin. Resistance to fracture was established as the compression strength at 45° tilt at the lingual surface of the crown. STATISTICAL ANALYSIS USED: Data were analyzed using ANOVA and Tukey's test. RESULTS: Resistance to fracture of G1 and G2 were significantly higher than that of G3 (P < 0.001). The pattern of fracture, common to all groups, occurred at the composite resin on the coronary portions. CONCLUSION: Ferrule thickness can influence the resistance to fracture of ETT.
RESUMO
OBJECTIVE: This investigation assessed the susceptibility of Streptococcus mutans and Lactobacillus acidophilus to Photodynamic Therapy (PDT) when grown simultaneously in dentine carious lesions. BACKGROUND DATA: PDT is a technique that utilizes light to activate photosensitizers in the presence of oxygen to produce reactive radicals. MATERIALS AND METHODS: A culture medium of 1% glucose, 2% sucrose, 1% young primary culture of L. acidophilus 108 CFU/mL, and S. mutans 108 CFU/mL was utilized to inoculate the bacterial induced caries on human dentine slabs. Different concentrations of the photosensitizer (0.75, 1.5, 3.0, 4.0, and 5.0 g/L) were activated through exposure to the light-emitting diode source with a central wavelength of 450 nm and a fluency of 5.7 J/cm2. Two light intensities (19 and 47.5 mW/cm2) were tested. Four different groups were analyzed: L-D- (control group), L-D+ (drug group), L+D+1 (PDT group 1, light intensity of 19 mW/cm2), and L+D+2 (PDT group 2, light intensity of 47.5 mW/cm2). ANOVA/Tukey tests were utilized to compare groups (α = 5%). RESULTS: Both light intensities required 5.0 g/L of curcumin for significant bacterial reduction (p < 0.05). No significant effect was found for L-D+, thus proving the absence of a potential inherent toxicity. CONCLUSIONS: Curcumin has a toxic effect on microorganisms at appreciable concentrations upon photoactivation. However, it was required to use the maximum concentration of the drug for a successful procedure.
