No abstract

The purpose of this study was to investigate and to compare the physical-mechanical properties of a resin-modified calcium silicate material (TheraCal LC), used for pulp-capping, to MTA (Angelus) and a calcium hydroxide cement (Dycal). Specimens of each material (n=12) were prepared in Teflon molds (3.58 mm x 3 mm) and measured before and after immersion in distilled water for 24 h and 30 days to evaluate the dimensional change. The same specimens were submitted to compressive strength test on a Universal Testing Machine (Instron) (1 mm/min). Root canals were filled with the cements (n=8), and after 24 h, the bond strength (push-out test) to dentin was also assessed on a Universal Testing Machine (1 mm/min). Eight additional specimens of TheraCal LC were prepared to evaluate the bond strength immediately after light curing. Data were analyzed using One-Way ANOVA, and Tukey or Bonferroni post hoc tests (p<0.05). Percentage expansion of TheraCal LC was above the Specification No. 57 of ANSI/ADA, in both periods. The dimensional change for TheraCal LC was higher than MTA in 24 h and 30 days; and Dycal in 30 days (p<0.05). TheraCal LC had higher compressive and bond strength to dentin in comparison with MTA and Dycal (p<0.05). Although TheraCal LC expanded more than the ANSI/ADA recommendation, its compressive and push-out bond strength to dentin were satisfactory and superior to MTA and Dycal.

Context: Knowledge about dentin microstructure is essential for execution of clinical procedures which require adhesion of materials to dentin. Aims: To evaluate by scanning electron microscopy (SEM) the dentin ultrastructure after demineralization with 6 M and 12 M hydrochloric acid (HCl). Subjects and Methods: Twenty dentin segments were immersed in fixative solution and dehydrated in ethanol. After 24 h, segments were randomly divided into 2 groups ( n = 10), demineralized with 6 M HCl (G6M) and 12 M HCl (G12M), and prepared for SEM analysis. Statistical Analysis Used: Based on photomicrographs and chemical composition (energy dispersive X-ray spectroscopy) of dentin, a descriptive analysis was conducted. Results: G6M samples revealed a demineralized surface with peritubular dentin exposure and small magnification of the dentinal tubules openings. The intertubular dentin was partially demineralized. Demineralization of G12M samples was more aggressive and at different depths, promoting erosion and “detachment” of dentin layers. Peritubular dentin was observed on the dentin surface. There was a large magnification of the dentinal tubules openings. In both groups, tubular structures showed a similar chemical composition to the intertubular dentin. Lamina limitans was not observed. Conclusions: Dentin demineralization is dependent on the HCl molarity and promotes exposure of peritubular dentin.

The use of PUI during final irrigation phase does not improve the action of CH when it is used as temporary filling material.