RESUMEN
PURPOSE: To evaluate the effects of 1 versus 2 glaze firings on the color and mechanical properties of an extrinsically characterized lithium disilicate ceramic after thermal cycling, brushing, or both. MATERIALS AND METHODS: Eighty specimens were divided into 2 groups: 1 glaze firing (GL1) and 2 glaze firings (GL2). Each group was subdivided into 4 groups (n = 10), according to the experimental conditions: thermal-cycling, brushing, thermal-cycling + brushing, and immersion in distilled water (control). Color variation, surface roughness, and Vickers microhardness were analyzed before each designated experiment and after the simulated periods of 2.5, 5, and 10 years. Three-way mixed ANOVA was used for all outcomes, followed by 1-way ANOVA, repeated measures 1-way ANOVA, Bonferroni post hoc test, and t-test to check for statistical differences (α = 0.05). RESULTS: Thermal cycling generated greater color changes in the GL1 group at 2.5 and 5 years (p < 0.001; p = 0.013). Brushing generated color changes in GL1 at 5 years (p = 0.003) and in GL2 at 10 years (p = 0.017). Regarding surface roughness, the GL1 group suffered alterations in thermal cycling + brushing at 5 years. In the control group, the GL1 group exhibited higher roughness values than GL2 (p < 0.05). Most of the groups experienced an increase in microhardness at 2.5 years (p < 0.05). In the GL1 group, thermal-cycling increased the microhardness at 5 years (p = 0.006); at 5 and 10 years, the GL1 group had a higher microhardness than the GL2 in thermal-cycling + brushing (p < 0.05). CONCLUSION: Ceramics with 1 glaze firing showed greater color, roughness, and microhardness changes compared to those submitted to 2 firings.
RESUMEN
ABSTRACT: Dento-alveolar traumas are one of the most frequent injuries to teeth, mainly affecting the upper incisors due to their exposed position in the dental arch. In such cases, esthetics, function and phonetics of anterior teeth may be compromised. Furthermore, when there is involvement of the biological width, there is often a poor prognosis. This case report describes the multidisciplinary approach to tooth fragment re-attachment in a fracture with biological width violation. The patient presented with an oblique crown fracture in the maxillary right lateral incisor, extending from the buccal to palatal side, as well as a biological width invasion. The re-establishment of the biological width was obtained by periodontal surgery to achieve clinical-crown lengthening and tooth fragment re-attachment with a glass fiber post to increase retention. After 3 years of follow-up, the rehabilitated lateral incisor remains in good condition, with satisfactory esthetic and periodontal health.