RESUMO
Objective: Lack of a dental material with optimal adhesion and sealability is an important challenge in modern dentistry leading to marginal leakage. There are controversies on the necessity of enamel preparation in pit and fissure sealant therapy and its effect on decreasing the microleakage; therefore, the present in vitro study aimed to assess the amount of microleakage with and without enamel preparation
Methods: In this experimental study, 30 sound premolars assigned suitable for sealant application, were chosen and randomly divided into two groups. Sealant was applied to all teeth with the same conventional technique. In group A, fissure sealant was applied without enamel preparation while in group B, sealant was applied after fissurotomy with bur. The teeth were thermocycled and microleakage was measured using silver nitrate as leakage tracer. The teeth were then cut into three bucco-lingual sections and examined under a stereomicroscope with 32× magnification. The amount of dye penetration into the sealant was recorded in microns and the degree of microleakage was classified into four degrees of 0, 1, 2 and 3. T-test was applied for the comparison of data between the two groups
Results: In total,20% of specimens in group B [fissurotomy] had degree 1 and 80% had degree 0microleakage and no specimen had degrees 2 and 3 microleakage, while in group A [no preparation], 20% had degree 1, 33.3% had degree 2 and 46.7% had degree 3microleakage. No specimen had degree 0 microleakage. Therefore, placement of sealant with enamel preparation significantly decreased microleakage [p<0.001]
Conclusion: In view of the findings of this investigation, it seems that enamel preparation reduces marginal leakage in pit and fissure sealant therapy
RESUMO
This study compared the cleaning efficiency of Mtwo, Race and Medin Nickel-Titanium [NiTi] rotary instruments. Sixty mandibular molar mesial roots were selected with angle curvatures between 25-35 degrees and divided into three groups; each containing 20 teeth. Canals were prepared with the rotary files and irrigated with 2.5% NaOCl solution after each instrument. Total of 5mL of normal saline was used as the final rinse; subsequently the canals were dried with paper points. The amount of debris and smear layer in three parts of the root canal walls was evaluated using SEM and the data were analyzed by using the Kruskal-Wallis test and the Mann-Whitney U test. The results for remnant debris in the coronal part of root canals were similar, whereas in the middle third, Mtwo instruments achieved significantly better results compared to Race and Medin instruments. In the apical third of the root canals more debris was created by Race instruments. Overall, Mtwo instruments had greater success in producing clean canals