Different ultrasonic vibration protocols and their effects on retention of post-and-core to root canal.

This study evaluated the effect of different ultrasonic vibration protocols on custom cast post-and-cores' retention to the root canal. Post holes were placed in the root canals of human maxillary canines, and post-and-core sets were luted, using zinc phosphate cement. The samples were divided into 5 groups (n = 8). Group 1 (control) received no ultrasonic vibration. For the other samples, the tip of the ultrasonic device was positioned either over the incisal face of the core (Group 2), over the lateral core surfaces and close to the incisal edge (Group 3), over the lateral face of the core but close to the line of cementation (Group 4), or over the lateral face of the core but with the end of the mouth mirror handle positioned on the opposite surface of the core (Group 5). After a tensile test, data were submitted to 2-way ANOVA and Tukey's tests (P < 0.05). The control group showed higher values than all of the groups that were submitted to ultrasonic vibration. Bond strength was similar for Groups 2 and 3. Bond strength was lower in Groups 4 and 5; no statistical difference was observed between these 2 groups. Based on these results, both positioning the tip of the ultrasonic device near the cement line and placing a mouth mirror handle on the opposite surface of the core, are effective ways to reduce the retention of a cast post-and-core within a root canal.

Efficacy of Low-Level Laser Therapy in Reducing Pain in the Initial Stages of Orthodontic Treatment.

Purpose: There is no consensus about the mechanism and efficacy in alleviating pain of the lower-level laser therapy (LLLT) during orthodontic treatment. This study aimed to evaluate the LLLT effectiveness clinically in reducing pain caused by orthodontic movement that occurs in the early stages of treatment. Methods: The sample consisted of 54 patients in need of orthodontic treatment divided into two groups. A 28 experimental patients group (initial mean age: 26.84 years old) was undergone gallium-aluminum-arsenide infrared laser application on 12 points for each tooth immediately after the installation of the first alignment archwire, and a 26 patients control group (initial mean age: 29.13 years old) was undergone to no pain control intervention at all. Pain intensity was measured by using a visual analog scale, which was marked pain level (mm) reported in 06, 24, 48, and 72 hours. The perception of pain (beginning, peak, decline, and absence) was evaluated by filling up a questionnaire. To compare the intensity and perception of pain between groups, a nonparametric Mann-Whitney has been performed. Results: The experimental group showed levels (mm) at 6 (p < 0.001), 24 (p=0.004), and 48 hours (p=0.007) and perception of pain (hours) in the peak (p=0.026), decline (p=0.025), and absence (p=0.008) significantly lower compared to the group control. Conclusion: Low-level laser therapy is effective in reducing pain severity caused by orthodontic forces activation, and it promotes the analgesic action lasting effect during the most painful feeling time.

Midbuccal canals of maxillary molars evaluated by cone-beam computed tomography: endodontic management of two cases.

Maxillary molars present variable root canal and root morphologies. This report describes the endodontic management of two cases of midbuccal canals found in maxillary molars. Midbuccal canals were present in a maxillary first molar with a single buccal root (Case 1), and in a maxillary second molar with three buccal roots (Case 2). An assessment of the internal configuration of these teeth was performed using cone-beam computed tomography (CBCT). Magnification with a dental operating microscope, surgical loupes, and the use of an endodontic explorer enabled the identification of the midbuccal canal orifices. The root canals in both cases were chemomechanically prepared and filled. Postobturation radiographic images revealed four (one midbuccal, two mesiobuccal and one palatal) and five (one midbuccal, two mesiobuccal, one distobuccal and one palatal) root canals, which were filled in Cases 1 and 2, respectively. Complex canal configurations of maxillary molars including the presence of midbuccal canals were presented. CBCT was a valuable tool in this diagnosis, as it provided a precise description of these unusual anatomical variations.

Comparison of the time required for removal of intraradicular cast posts using two Brazilian ultrasound devices.

The aim of this in vitro study was to compare the time required for removal of intraradicular cast posts cemented with zinc phosphate (ZF) or glass ionomer cement (GIC), using two Brazilian ultrasound devices (BUD). Seventy two human inferior premolars with single root canals were sectioned transversally at the cementoenamel junction. In each specimen, the root canal was endodontically treated, the post space was prepared to a depth of 9 mm and the canal was molded to obtain a post impression. After the casting procedures, the posts were randomly distributed into 2 groups (n = 36) according to the luting material used: G1 - ZF and G2 - GIC. The tooth and luted post set was then embedded in an acrylic resin block. The groups were then divided into 3 subgroups (n = 12) according to the ultrasound device used: A - Enac (Osada Electric, Japan), used as a control group; B - Profi II Ceramic (Dabi Atlante, Brazil) and C - Jet Sonic Satelec (Gnatus, Brazil). The posts were submitted to the vibration process with maximum power set on all surrounding surfaces. Time of application was recorded with a chronometer until complete post dislodgment, and the data were analyzed by the ANOVA test (p < 0.05). The averages required for post removal in G1 and G2 were respectively 41.42 and 92.03 seconds, with significant statistical difference (p = 0.001). No statistical difference was observed among the three ultrasound devices (p = 0.088), and the BUD presented a performance similar to that of the international gold standard device (Enac). Moreover, the type of luting agent had a greater influence on the time required for post removal than the origin of the ultrasonic unit.