new method for location of a difficult-to-find root canal orifices: an in-vitro study

In this study, Nd: YAG laser was used as an aid to facilitate the detection of the difficult-to-find orifices of the main and extra root canals. Eighty human extracted teeth were used. The teeth were divided into two groups, forty teeth each. In group I, access cavities according to Black's principles were prepared. In group II, cervical cross-sections were performed. Using Nd: YAG laser at power 15 pps/1.5 w for 1/2-1 minute, applying it to the access cavities and the prepared cervical cross-sections, resulted in black dicoloration and accentuation of the most of the existing main and extra orifices of the root canals. The dark black discoloration might result from carbonization of the organic contents of the canals. This laser effect facilitated the detection of the difficult-to-find orifices and the identification of most of the orifices of the extra canals

Effects of ND: YAG laser on the apical seal of three different retrograde filling materials

Sixty human single rooted m and ibular premolars with single apical foramen were used in this study. The crowns of the selected teeth were capitated. The root canals were obturated with single cone gutta percha technique and the apical cavities were performed to approximately 2 mm deep. The prepared roots were divided into two main groups, the apical cavities of the first group were exposed to Nd: YAG laser [1.06 wave length, 1.6 w, 15 pps] for 1.5 minutes, while the second group left without laser exposure. Each main group was subdivided into three subgroups according to the retrofilling material used. The roots were retrofilled with amalgam in subgroup A [control group], glass ionomer [Ketac Endo] in subgroup B and ultrafil in subgroup C. After coating the root surface with nail polish except the apical cavity, the roots were placed in Indian ink for 7 days. Longitudinal sections were prepared and the amount of dye penetration was measured. When laser was used, amalgam had significant lowest mean leakage [1.88] versus glass ionomer and ultrafil. Also, there was statistically significant reduction of the mean leakage of lased amalgam versus unlased

Comparison of dentinal wall adaptation of Ultrafill versus lateral and vertical condensation techniques after pre-treatment ND-YAG laser A scanning electron microscopic study

Sixty extracted single rooted m and ibular premolars were decapitated and biomechanically instrumented 1 mm shorter to the apex to the size 40 K-file. Step back instrumentation technique was done up to size 70 k-file. The coronal portion of each root canal was further flared with Gate Glidden bur 1 and 2. The prepared roots were divided into two main groups. The root canal walls in the first group were exposed to Nd-YAG laser [1.06 wave length] at energy of 15 pps and 1.5 w for 1.5 minutes; while in the second group, they were left without laser exposure. According to root canal filling technique, each group was subdivided into three subgroups, each contained ten root canals. The root canals were obturated using lateral condensation technique in the first subgroup, vertical condensation technique in the second subgroup, while the low temperature injected thermoplasticized gutta percha was used in the third subgroup. By scanning electron microscope, it was observed that the laterally condensed and injected thermoplasticized gutta percha had poor adaptation to the unlased dentin wall, while insignificant versus vertical condensation technique. In the dentin lased group, although there was no significant difference among the three filling techniques, the laterally condensed and injected thermoplasticized gutta percha were significantly better in adaptation to the lased dentin versus unlased dentin