Quantitative 3D profilometry and SEM analysis of the adaptation of root-end filling materials placed under an optical microscope.

AIM: To evaluate by 3D profilometry and scanning electron microscopy (SEM), the marginal adaptation of mineral trioxide aggregate (MTA) and Sealer 26 placed in root-end cavities with direct vision or under an optical microscope. METHODOLOGY: The root ends of 52 root filled canine teeth were filled with MTA or Sealer 26 under direct vision or optical microscope (n=13). In each group, eight specimens were analysed by profilometry for measurement of the area and depth of gaps. In the other five specimens, gap area was measured using SEM to verify marginal adaptation and surface characteristic. Data were analysed by parametric (anova and Tukey) and non-parametric (Kruskal-Wallis and Dunn) tests. RESULTS: The assessment of the adaptation of both materials to dentine was not influenced by the mode of visualization, which was confirmed by both profilometry and SEM observations. The voids measured with profilometry for Sealer 26 under direct vision were significantly wider and deeper than those for MTA under direct vision (P<0.05). In SEM, significantly larger gap areas were observed with Sealer 26 (P<0.05). CONCLUSION: Root-end cavities filled with MTA had smaller gaps and better marginal adaptation than Sealer 26.

Ultrastructural analysis of radicular dentine surface submitted to CO2 laser at different parameters.

BACKGROUND: There are no reported studies comparing different parameter settings of the CO(2) laser and irradiation direction considering their effect on the morphology of radicular dentine surface. PURPOSE: To evaluate the alterations of radicular dentine (cervical, middle, and apical thirds) irradiated with CO(2) laser at different potencies and irradiation directions. STUDY DESIGN: Roots of 35 canines were prepared and randomly distributed according to the laser potency: GI: no laser treatment (control) (n = 5); GII, 2 W (n = 10); GIII: 4 W (n = 10); GIV: 6 W (n = 10). Each group (excepting GI) was divided in two subgroups according to the irradiation distance (n = 5): (A) parallel and (B) perpendicular to the root canal walls. The roots were splited longitudinally and analyzed by scanning electron microscopy in a qualiquatitative way. The scores were submitted to Kruskal-Wallis and Dunn's tests. RESULTS: No significant statistical differences were observed among root canal thirds (P > 0.05). The specimens irradiated with 2 W were statistically different (P < 0.05) from those irradiated with 4 and 6 W, which were statistically similar between themselves (P > 0.05). With 2, 4, and 6 W at in parallel irradiation and 2 W in perpendicular direction, the surface showed a fissured aspect. With 4 W in perpendicular direction and 6 W in parallel and perpendicular direction, surface was modified by laser action and exhibited fused areas. CONCLUSIONS: The intensity of the effects is dependent on the laser-irradiation dosimetries. Alterations were more intense when higher parameters were used.

Temperature variation at the external root surface during 980-nm diode laser irradiation in the root canal.

OBJECTIVE: To assess the temperature variation in the cervical, middle and apical thirds of root external wall, caused by 980-nm diode laser irradiation with different parameters. METHODS: The roots of 90 canines, had their canals instrumented and were randomly distributed into 3 groups (n=30) according to the laser potency (1.5 W, 3.0 W and 5.0 W). Each group was subdivided into 3 (n=10) according to the frequency (CM, 100 Hz and 1000 Hz), and each subgroup divided into 2 (n=5): dried canal or filled with distilled water. The maximum temperature values were collected by 3 thermocouples located at each third of the root external wall and recorded by digital thermometers. RESULTS: The groups irradiated in the continuous mode (CM) presented the highest values (11.82+/-5.78), regardless of the canals were dry or not, which were statistically different (p<0.01) from those obtained with 100 Hz (6.22+/-3.64) and 1000 Hz (6.00+/-3.36), which presented no statistical difference between them (p>0.01). The groups irradiated with 5.0 W presented the greatest temperature variation (12.15+/-5.14), followed by 3.0 W (7.88+/-3.92) and 1.5 W (4.02+/-2.16), differing between them (p<0.01). The cervical third of the root presented the highest temperature rises (9.68+/-5.80), followed by the middle (7.66+/-4.87) and apical (6.70+/-4.23), with statistical difference among them (p<0.01). After 30s from the end of irradiation, all the specimens presented temperature variation lower than 10 degrees C. CONCLUSIONS: Application of 980-nm diode laser in the root, at 1.5 W in all operating modes, and 3.0 W, in the pulsed mode, for 20s, can safely be used in endodontic treatment, irrespective of the presence of humidity.

Ex vivo study of the adhesion of an epoxy-based sealer to human dentine submitted to irradiation with Er : YAG and Nd : YAG lasers.

AIM: To evaluate the adhesion of an epoxy-based sealer to human dentine submitted to irradiation with Er : YAG or Nd : YAG laser at various parameters. METHODOLOGY: Ninety maxillary canine teeth were sectioned transversely at the cemento-enamel junction and at the root tip to leave an 8-mm-long cylinder. The tooth specimen was centred in a metallic ring (16 mm diameter and 8 mm height) and embedded in acrylic resin. The root canals were prepared using a low-speed handpiece and a conical diamond bur, which was attached to a paralleling device. This bur was lowered to a depth previously determined by a silicone stop. Specimens were divided into nine groups: group I, dentine was treated with 2 mL of 17% EDTAC for 5 min. Groups II-V were irradiated with Er : YAG laser at the following parameters: group II - 8 Hz and 200 mJ input (120 mJ output); group III - 8 Hz and 400 mJ input (240 mJ output); group IV - 16 Hz and 200 mJ input (120 mJ output); group V - 16 Hz and 400 mJ input (240 mJ output). Groups VI-IX were irradiated with Nd : YAG laser at the following parameters: group VI - 10 Hz and 1 W input (0.4 W output); group VII - 10 Hz and 2 W input (0.8 W output); group VIII - 15 Hz and 1 W input (0.4 W output); group IX - 15 Hz and 2 W input (0.8 W output). The root canals were filled with an epoxy-based root canal sealer and submitted to a push-out test. RESULTS: Statistical analysis showed significant differences (P < 0.01) between Er : YAG and Nd : YAG laser treatments at the higher frequencies compared with 17% EDTAC. Greater adhesion values were obtained for groups IV and V (Er : YAG laser) and groups VIII and IX (Nd : YAG laser), which were statistically different from groups II and III (Er : YAG laser) and groups VI and VII (Nd : YAG laser). Treatment with only 17% EDTAC had the lowest adhesion values. CONCLUSIONS: An increase in frequency, independent of power settings, of the lasers used in this study increased adhesion of an epoxy-based root canal sealer.

Evaluation of smear layer removal by EDTAC and sodium hypochlorite with ultrasonic agitation.

AIM: To evaluate smear layer removal by different irrigating solutions under ultrasonic agitation. METHODOLOGY: Twenty recently extracted mandibular incisors with a single root canal were divided into four equal groups. Three groups were instrumented using the modified double-flared technique, the fourth remained unprepared. Each group was irrigated with either distilled water, 1.0% sodium hypochlorite alone or associated with 15% EDTAC between each file size. The final group was not instrumented but irrigated with 1.0% sodium hypochlorite and 15% EDTAC. A size 15 file energised by ultrasound was used with small amplitude filing movements against the canal walls in all groups. The teeth were split longitudinally and the roots measured to provide three sections of the same size (cervical, middle and apical). Samples were examined under the scanning electron microscope and assessed for the amount of smear layer by three independent and calibrated examiners. The scoring system ranged from 1 (no smear layer) to 4 (all areas covered by smear layer). Due to the non-parametric nature of the data, Friedman's test was used for statistical analysis. RESULTS: Canal walls were covered with smear layer in the group irrigated with 1% sodium hypochlorite alone and the group irrigated with distilled water. Canals irrigated with 1.0% sodium hypochlorite associated with 15% EDTAC had less smear layer throughout the canal (P < 0.001). There were no statistical differences for the amount of smear layer found on the cervical, middle and apical thirds when each group was analysed separately. CONCLUSIONS: Under ultrasonic agitation, sodium hypochlorite associated with EDTAC removed the smear layer from root canal walls, whereas irrigation with distilled water or 1.0% sodium hypochlorite alone did not remove smear layer.

Evaluation of Er:YAG laser and EDTAC on dentin adhesion of six endodontic sealers.

The effect of Er:YAG laser application and EDTAC on the adhesion of epoxy resin-based endodontic sealers to human dentin was evaluated in vitro. A total of 99 extracted human maxillary molars with their crowns worn flat were used. The teeth were divided into 3 groups: group 1, the dentin surface received no treatment; group 2, EDTAC was applied to the dentin surface for 5 min; group 3, the dentin surface received Er:YAG laser application (2.25 W potency; 11 mm focal distance; 4 Hz frequency; 200 mJ energy; 62 J total energy; 313 mean impulse). Three teeth from each group were analyzed by scanning electron microscopy for changes in dentin surface. The epoxy resin root canal sealers used were: AH Plus, Topseal, Sealer 26, AH 26, and Sealer Plus. The zinc oxide eugenol-based sealer Fillcanal was used as control. Adhesion was measured with a Universal testing machine. The results showed a statistically significant difference at the level of 1% among the dentin treatments. The dentin treated with Er:YAG laser showed greater adhesion with the sealers than dentin treated with EDTAC which was greater than dentin that received no treatment. The Tukey test showed the formation of 5 groups in decreasing order of adhesion: AH Plus, Topseal and Sealer 26, AH 26, Sealer Plus, and Fillcanal (Grossman cement).