Effects of multiple root canal usage on the surface topography and fracture of two different Ni-Ti rotary file systems.

Aim: The purpose of this study was to evaluate the effect of multiple root canal usage on the surface topography and fracture of Twisted File (TF) and ProTaper (PT) rotary Ni-Ti file systems, using scanning electron microscope (SEM). Materials and Methods: Ten sets of PT and TF instruments were used to prepare the mesial canals of mandibular first molars. TF 25, 0.06 taper and PT F1 instruments were analyzed by SEM when new and thereafter every three root canal usages. This sequence was repeated for both the TF and PT groups until 12 uses. Two images of the instrument were recorded, one of the instrument tip and the other 5 mm from the tip, both at ×100 magnification. The sequential use was continued till the instrument fractured and the number of root canal usages for the file to fracture was noted. All fracture surfaces were examined under the SEM. Results: Fresh TF instruments showed no surface wear when compared to PT instruments (P < 0.05). Spiral distortion scores remained the same for both the groups till the 6 th usage (P > 0.05), while at the 9 th usage TF showed a steep increase in the spiral distortion score when compared to PT (P < 0.05). PT instruments fractured at a mean root canal usage of 17.4, while TF instruments showed a mean root canal usage of 11.8. Fractographically, all the TF instruments failed due to torsion, while all the PT instruments failed because of cyclic fatigue. Conclusion: PT instruments showed more resistance to fracture than TF instruments.

Efficacy of passive ultrasonic irrigation with natural irrigants (Morinda citrifolia juice, Aloe Vera and Propolis) in comparison with 1% sodium hypochlorite for removal of E. faecalis biofilm: An in vitro study.

Aim: Present study evaluated the efficacy of natural derivative irrigants, Morinda citrifolia juice (MCJ), Aloe Vera and Propolis in comparison to 1% sodium hypochlorite with passive ultrasonic irrigation for removal of the intraradicular E. faecalis biofilms in extracted single rooted human permanent teeth. Materials and Methods: Biofilms of E. faecalis were grown on the prepared root canal walls of 60 standardized root halves which were longitudinally sectioned. These root halves were re-approximated and the samples were divided into five groups of twelve each. The groups were, Group A (1% NaOCl), Group B (MCJ), Group C (Aloe vera), Group D (Propolis) and Group E (Saline). These groups were treated with passive ultrasonic irrigation (PUI) along with the respective irrigants. The root halves were processed for scanning electron microscopy. Three images (X2.5), coronal, middle and apical, were taken for the twelve root halves in each of the five groups. The images were randomized and biofilm coverage assessed independently by three calibrated examiners, using a four-point scoring system. Results: 1% NaOCl with passive ultrasonic irrigation (PUI) was effective in completely removing E. faecalis biofilm and was superior to the natural irrigants like MCJ, Aloe vera and Propolis tested in this study. Conclusion: 1% NaOCl used along with passive ultrasonic irrigation was effective in completely removing E. faecalis biofilm when compared to natural irrigants (MCJ, Aloe Vera and Propolis).

Assessment of root canal morphology of mandibular first premolars in the Indian population using spiral computed tomography: An in vitro study.

Aim: The aim of the study is to determine the root canal morphology of the mandibular first premolar teeth in an Indian population using spiral computed tomography (SCT). Materials and Methods: One hundred extracted mandibular first premolars were observed using Spiral Computed Tomography for the (i) Pattern of root canal (ii) Tooth length (iii) Position of the bifurcation of the canal (iv) Invagination of the root (v) Root thickness. The root canal morphology was classified based on Vertucci's classification. Results: Eighty percent of the teeth had a single canal, 11% of the teeth had two canals, and C-shaped canals were found in 2% of the teeth, in this study. The average length of the teeth was 21.6 mm. Fourteen percent of the teeth had mesial invagination of the root. Conclusion: The Type I root canal morphology was the most common type of root canal system in the mandibular first premolars among the Indian population in this study.

Evaluation of the pulp chamber size of human maxillary first molars: an institution based in vitro study.

The aim of this in vitro study was to determine the morphological measurements of the pulp chamber and also to establish the relationship of the cemento-enamel junction (CEJ) to the roof of the pulp chamber of the maxillary first molars in an Indian population. One hundred extracted human maxillary first molars were used. Each molar tooth was radiographed by radio visiography (RVG). Measurements were made by using the grid option in RVG. The results (mean +/- SD; in mm) were as follows: distance from floor of the pulp chamber to the furcation = 2.7 +/- 0.63; distance from roof of the pulp chamber to the furcation = 5.34 +/- 0.9; distance from tip of the palatal cusp to the furcation = 11.58 +/- 1.01; distance from the tip of the palatal cusp to the floor of the pulp chamber = 8.86 +/- 0.68; distance from the tip of the palatal cusp to the roof of the pulp chamber = 6.2 +/- 0.66; height of the pulp chamber = 2.62 +/- 0.61. The results of these measurements revealed that the morphological measurements of the maxillary first molars in the Indian population were similar to that reported by previous studies; the roof of the pulp chamber was found at the CEJ in 96% of the specimens.