Fábio Heredia Seixas

In vitro evaluation of external root temperature changes during Er:YAG laser application with five different fiberoptic tip withdrawl techniques

This study evaluated in vitro the external temperature increase at the three root thirds using five different fiberoptic tip withdrawal techniques in 50 human canines. Er:YAG laser was applied with a 50/28 fiberoptic tip with 250 mJ input, 112 mJ output, 10 Hz, 1 mm from the apical foramen: group 1: each third was irradiated starting at the apex for 1 s on each wall, with the irradiation turned off between thirds; group 2: apical third irradiated without movement for 2 s and tip withdrawn with continuous radiation up to the cervical third; group 3: tip activated at the apex and removed to the canal entrance in a straight line; group 4: tip activated at the apex and removed to the canal entrance with circular movements touching all walls; group 5: tip activated at the apex and removed to the canal entrance with clockwise circular movements for 6 s adn then reinserting and removing with counter-clockwise circular movements for another 6 s, touchgin all walls. Group 1 had significantly lower external temperature (p<0.01). The middle third had the greatest temperature increase (p<0.01). We conclude that the withdrawl techniques caused an increase in external root temperature that would not damage adjacent tissues.

In vitro evaluation of external root temperature changes during Er:YAG laser application with five different fiber optic tip withdrawal techniques

This study evaluated in vitro the external temperature increase at the three root thirds using five different fiber optic tip withdrawal techniques in 50 human canines. Er:YAG laser was applied with a 50/28 fiber optic tip with 250 mJ input, 112 mJ output, 10 Hz, 1 mm from the apical foramen: group 1: each third was irradiated starting at the apex for 1 s on each wall, with the irradiation turned off between thirds; group 2: apical third irradiated without movement for 2 s and tip withdrawn with continuous radiation up to the cervical third; group 3: tip activated at the apex and removed to the canal entrance in a straight line; group 4: tip activated at the apex and removed to the canal entrance with circular movements touching all walls; group 5: tip activated at the apex and removed to the canal entrance with clockwise circular movements for 6 s and then reinserting and removing with counterclockwise circular movements for another 6 s, touching all walls. Group 1 had significantly lower external temperature (p<0.01). The middle third had the greatest temperature increase (p<0.01). We conclude that the withdrawal techniques caused an increase in external root temperature that would not damage adjacent tissues.

Er:YAG laser evaluation of smear layer removal from flattened root canals submitted to rotary instrumentation

This study evaluated smear layer removal of 40 mesio-distal flattened root canals after rotary instrumentation. Teeth were divided into 4 goups: Group 1: 2.5% sodium hypochlorite was used as an irrigating solution; Group 2: instrumented as Group 1 followed by Er:YAG laser irradiation (140mJ input/10Hz, withdrawn at 2mm/s from the apical to the cervical region touching the buccal wall; the procedure was then repeated for the lingual wall); Group 3: instrumented as Group 1 and followed by Er:YAG laser irradiation (250mJ input/10Hz, in the same way as described for Group 2) and Group 4: instrumented as Group 1 and alternated with 17% EDTA. Teeth were then split longitudinally and prepared for examination under the scanning electron microscope. Scores from 1 to 4 were given to the fotomicrographs by three independent evaluators, and these data were submitted to statistical analysis. Teeth where alternated 17% EDTA was used (Group 4) showed less amount of smear layer, followed by the group irradiated with 250mJ input/10Hz (Group 3), the group irradiated with 140mJ input/10Hz(Group 2) and the group where only sodium hypochlorite was used (Group 1). The apical third presented more smear layer than the middle third (p<00.1)

In vitro evaluation of smear layer removal of root canals by irradiation with Er:YAG laser after Ni-Ti rotary instrumentation

The smear layer removal of root canal walls irradiated with Er:YAG laser after nickel-titanium rotary instrumentation was evaluated by scanning electron microscopy. Thirty mesial roots of human mandibular molars were selected and randomly distributed in three groups, according to treatment. Group 1 was instrumented with rotary nickel-titanium files 1 mm from the anatomical apex and irrigated with 2.5% sodium hypochlorite. Group 2 received the same treatment as Group 1, but after instrumentation the root canals were irradiated with Er:YAG laser. Group 3 received the same treatment as Group 1, but irrigation was performed with 2.5% sodium hypochlorite alternated wtih 17% EDTA during instrumentation. Photomicrographs were obtained from middle and apical thirds and submitted to qualitative evaluation. Statistical analysis showed that 2.5% sodium hypochlorite associated with 17% EDTA (Group 3) removed smear layer more efficiently than 2.5% sodium hypochlorite al one (Group 1) (p<0.05). Root canals irradiated with Er:YAG laser occupied an intermediary position regarding smear layer removal. There were no statistical differences between the evaluated radicular thirds (p>0.05).

Microbial contamination of the environment after the irradiation of Er:YAG laser in infected root canals

The purpose of this study was to analyze the environment microbial contamination produced by Er:YAG laser irradiation in infected root canals. A total of 20 human anterior teeth were prepared, sterilized and, then, inoculated with a mixture of the following microorganisms: S. Aureus, E. Faecalis, P. Aeruginosa, B. Subtilis and C. Albicans. After the contamination period (28 days), the teeth were irrigated with sterile distilled water or 1% sodium hypochlorite and, then, irradiated with an Er:YAG laser with two different laser parameters: 52 mJ or 110 mJ output at the fiber tip. Eighteen Petri dishes with 20 ml of BHI Agar were used in the study. For each group, 3 plates with BHIA were used for the analysis of the microbial contamination of the environment during the activation of the laser in infected root canals. The plates were positioned in differing distances away from the irradiated tooth (plate 1 - distance of 15 cm, plate 2 - distance of 50 cm and plate 3 - distance of 3 meters). After the analysis of the results, it was observed that the larger microbial contamination occurred in Group 1 (teeth irrigated with sterile distilled water and irradiated with Er:YAG laser with 52 mJ output at the fiber tip), plate 1 (positioned 15 cm away from the irradiated tooth), with values greater than 30 Colony-Forming Units (CFU).