Histological and scanning electron microscope examination of root canal after preparation with Er:YAG laser microprobe: a preliminary in vitro study.

Abstract

Until now, there has been no study that demonstrates the effectiveness of Er:YAG laser microprobes to clean and shape the root canal without using any mechanical instrumentation. The study was conducted on 28 single-rooted extracted central incisors teeth with straight roots. Fourteen were mechanically prepared and served as the control group, and 14 were treated by Er:YAG laser only. From every group, half of the teeth were examined histiolgically and half by SEM. The instrument tested was an Er:YAG laser with microprobes 200-400 micro in diameter and 20 mm in length, coupled onto special handpieces, attached to the delivery fiber of an OPUS 20 Er:YAG laser. The Er:YAG laser was applied with the following parameters: wavelength 2.94 microm; pulse duration 400 msec; repetition rate 10 Hz; energy per pulse 140 mJ for the 400 micro microprobe and 90 mJ for the 200-micro microprobe. For the control group, histologically, large amounts of residual pulp tissue were found in the root canal cavity, and open tubules were seen in all the specimens; SEM examination showed very uniform root canal, from apical to cervical portion, high number of open tubules, and different levels of canal debridment. For the study group, histologically, no residual pulp tissue was found in the root canal cavity and open tubules were seen in all the specimens; SEM examination showed the root canal free of debris, removed smear layer, open dentinal tubules, and different levels of enlargement. Our results show that the Er:YAG laser special microprobes are effective in shaping, cleaning, and enlarging straight root canals faster and more efficiently then traditional methods.