A study on FlexMaster : a Ni-Ti rotary engine driven system for root canal preparation.

In the present study, the effectiveness of recently introduced rotary Nickel Titanium FlexMaster engine driven system was evaluated for cleaning and shaping of root canals in extracted human teeth and compared with that done by the Nickel Titanium Flexofile hand instruments. A total of 40 root canals from 36 extracted mandibular and maxillary teeth with curvature ranging between 20 and 30 degree were divided into two groups, consisting 20 canals in each. FlexMaster instrumentation was done in 20 canals, using crown-down technique and manual filing with Flexofile was done in other 20 canals, using conventional and step-back techniques. 5.25% sodium hypochlorite (NaOCl) solution and 17% ethelene di-amine tetra-acetic acid (EDTA) were used alternatively for irrigation after canal preparation by each instrument size. Time needed for canal preparation of individual canal was recorded. A procedural error such as instrument breakage was also noted. After preparation, all the roots were cut longitudinally by using diamond burs in turbine handpiece and examined under scanning electron microscope. Apical region was quantified for debris and smear layer based on a 5-score numerical evaluation scale. The data established for scoring the debris and smear layer and preparation time of individual canal were analyzed statistically using the Mann-Whitney U test. Completely cleaned root canals were not found with any of the two instruments and none of the instruments maintained the original canal uniformity and regular dentine surface. Because significantly less debris was found in the apical region using the manual filing technique (p< 0.05). Thus the flexmaster system was found to produce less cleaner root canal walls than manual technique. Only one FlexMaster finishing file sized 30 was separated in the apical region during preparation of 30 degree curved canal. The time taken by FlexMaster was significantly better (p< 0.01) than that of hand instruments.

An in vitro microleakage study of different filling materials using dye penetration method.

In the present study, the marginal integrity of different filling materials was evaluated in invitro. Furthermore, the effect of manipulation technique on their microleakage was also investigated. A total of sixty standard prepared class V cavities were filled with glass ionomer cement (both auto-cured and light-cured), light cured packable variety composite resin pretreated with echant and bonding agent and dental amalgam (both mechanically and conventional hand mixed) with or without pretreatment by cavity varnish. Cavities were then subjected to microleakage test following thermocycling. Statistical analysis was performed by One way ANOVA and Sheffe's multiple comparison tests. The results showed that mechanically mixed Silver Amalgam pretreated with cavity varnish showed the least microleakage, whereas, autocured glass ionomer showed highest marginal leakage. Light-cured packable composite was superior in resisting microleakage than both types of glass ionomer but was inferior to dental amalgam in the same respect. From this study, it can be concluded that composite resin can be used to fill class V cavities for esthetic reason but their properties should be improved.