Effectiveness of Newer Tip Design of Laser in Removing the Smear Layer at the Apical Third of Curved Root Canals: An Ex Vivo study

The purpose of this ex vivo study was to investigate the effectiveness of newer tip design of Er,Cr:YSGG laser in removing the smear layer at the apical third of curved root canals. A total of 81 freshly extracted single rooted intact human mandibular premolars teeth with 15-30º canal curvature were selected for the study and were decoronated at the level of cemento enamel junction. The roots were divided in to three main groups with 27 samples each. GROUP I - Irrigants not activated by laser (non lased group). GROUP II - Irrigants activated by Er,Cr:YSGG laser with plain tip and GROUP III-Irrigants activated by Er,Cr:YSGG laser with conical tip and each group were further divided in to three sub groups of 9 samples each with EDTA, CHX, NaOCl respectively. In all the three groups, Canals were prepared with rotary nickel-titanium (Ni-Ti) instruments to a working length 1 mm short of the apex to size F3 by using Protaper instruments. In Group I the canal was irrigated with 17% EDTA, 2% Chlorhexidine and 3% NaOCl without laser irradiation, where as in Group II and Group III the canal was irrigated with 17% EDTA, 2% Chlorhexidine and 3% NaOCl respectively with Plain and conical fiber tips was placed 5mm from the apex in the root canal and the appropriate irrigant solution was then activated for 20 second. The teeth were then grooved longitudinally with a diamond disc on their buccal and lingual surfaces and were split into two halves with a chisel and mallet. The split half of the tooth in which apex was most visible used for SEM evaluation at 1000 X magnification and smear layer scoring was done using Torabinejad’s scoring system. The result of the present study were subjected to statistical analysis to interpret the smear layer removal in each group and also between the groups. ONE-WAY ANOVA followed by POST HOC TUKEY HSD test was used for statistical analysis in the present study. CONCLUSION: Within the limitations of this ex vivo study it can be concluded that: 1. Er,Cr:YSGG laser with conical fiber tip performed better removal of smear layer in the apical third of the curved root canal system. 2. Conical fiber tip performed better than plain fiber tip for removing smear layer in the apical third of the curved root canal system. 3. Among the irrigants used EDTA showed better effectiveness in smear layer removal followed by CHX and NaOCl in the apical third of the curved root canal system. This suggests that to ensure complete removal of smear layer from the root canal system it may be prudent to activate EDTA with conical tip design of Er,Cr:YSGG laser during irrigation protocol in the curved root canals