Waiting time for coronal preparation and the influence of different cements on tensile strength of metal posts.

This study aimed to assess the effect of post-cementation waiting time for core preparation of cemented cast posts and cores had on retention in the root canal, using two different luting materials. Sixty extracted human canines were sectioned 16 mm from the root apex. After cast nickel-chromium metal posts and cores were fabricated and luted with zinc phosphate (ZP) cement or resin cement (RC), the specimens were divided into 3 groups (n = 10) according to the waiting time for core preparation: no preparation (control), 15 minutes, or 1 week after the core cementation. At the appropriate time, the specimens were subjected to a tensile load test (0.5 mm/min) until failure. Two-way ANOVA (time versus cement) and the Tukey tests (P < 0.05) showed significantly higher (P < 0.05) tensile strength values for the ZP cement groups than for the RC groups. Core preparation and post-cementation waiting time for core recontouring did not influence the retention strength. ZP was the best material for intraradicular metal post cementation.

Diagnosis and esthetic functional rehabilitation of a patient with amelogenesis imperfecta.

Amelogenesis imperfecta is a hereditary disease that causes structural anomalies in dental enamel of both the primary and permanent dentition. The anomaly may present a variety of clinical forms and appearances, with its main characteristics being the loss of tooth structure, compromised esthetic appearance, and dental sensitivity. The aim of this study was to present the clinical report of a 16-year-old patient with severely compromised esthetics as a result of amelogenesis imperfecta of the hypocalcified type who was rehabilitated with composite resin and ceramic crowns.

Alkali soluble fluoride deposits on bovine dental enamel after treatment with a mouthwash containing fluoride and chlorhexidine / Deposição de fluoreto solúvel em álcali no esmalte dental bovino após tratamento com um enxaguatóriocontendo fluoreto e clorexidina

Aim: The aim of this in vitro study was to determine whether the addition of chlorhexidine (CHX)to a mouthwash containing fluoride (F) diminishes the concentration of soluble F and its reactivity withbovine dental enamel. Materials and Methods: First, the concentration of F found in mouthwashs wasdetermined by an ion-specific electrode. To test their reactivity, 30 slabs of bovine dental enamel (5 x 5mm)were distributed into three groups (n = 10), according to the treatment applied, for 30 seconds: controlgroup (distilled deionized water); NaF group (0.05% sodium fluoride); NaF + CHX group (Noplak Max®:0.05% sodium fluoride + 0.12% chlorhexidine digluconate). After, the slabs were washed with distilleddeionized water and individually immersed in artificial saliva for 30 minutes. They were dried and thenindividually immersed in 0.5 mL of 1M KOH for 24 hours, under agitation. After buffering the samples withHCI containing TISAB II, the concentration of F present in the KOH solutions was determined be means ofan ion-specific electrode. Results: No significant difference in the concentration of soluble F in the studiedmouthwashs (NaF and NaF+CHX; Student’s t-test, p > 0.05) could be observed. Furthermore, no differencecould be identified among the alkali soluble fluoride deposits from the NaF and NaF+CHX groups, andboth groups presented higher deposit levels than did the control group (Kruskal-Wallis and Dunn´s method,p < 0.05). Conclusion: The addition of CHX to a mouthwash containing F did not decrease its soluble Fconcentration, nor its reactivity to bovine dental enamel.