Effect of Different Agitation Techniques on the Penetration of Irrigant and Sealer into Dentinal Tubules.

OBJECTIVE: The aim of this study was to compare the effectiveness of five intracanal agitation techniques on the penetration of irrigant and sealer into dentinal tubules. BACKGROUND DATA: Intracanal agitation techniques could promote chemomechanical debridement and the sealing of root canals during endodontic treatment. However, there is limited evidence for the agitation effect of Nd:YAP laser. MATERIALS AND METHODS: Human maxillary premolars with single straight canals (N = 60) were prepared with ProTaper Next® NiTi rotary files (Dentsply Maillefer) up to X4 (ISO 40 size). Rhodamine B-labeled sodium hypochlorite was used for final irrigation together with the conventional syringe (control), sonic, ultrasonic, Nd:YAP laser, or V-Clean™ endodontic agitation system. All canals were obturated with gutta-percha and fluorescein isothiocyanate-labeled AH Plus sealer. Transverse sections were obtained at 2, 5, and 8 mm from the apex and observed under confocal laser scanning microscopy. Maximum penetration depth and penetration percentage of both irrigant and sealer were recorded. Kruskal-Wallis and Mann-Whitney tests were performed for multiple comparisons. The Spearman coefficient was calculated to confirm correlations between irrigant and sealer penetration. RESULTS: Laser agitation attained the most irrigant and sealer penetration depth and penetration percentage (p < 0.05). Sonic and ultrasonic agitation attained significantly more penetration percentage than the control group at 2 mm from the apex (p < 0.05). Patterns of irrigant and sealer penetration correlated significantly for all agitation techniques (p < 0.001). CONCLUSIONS: Nd:YAP laser was superior to other agitation techniques in dentinal tubule penetration of irrigant and sealer at one or more sectioned levels from the apex.

Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment.

OBJECTIVE: To evaluate the change in mandibular second-molar (M2) angulation in orthodontic treatment with premolar extraction and lower third molar (M3). STUDY DESIGN: Panoramic radiographs were evaluated in 3 groups of 129 participants: (1) control, no orthodontic treatment (n = 65); (2) extraction, orthodontic treatment with premolar extraction (n = 30); and (3) nonextraction, orthodontic treatment without premolar extraction (n = 34). The angular difference and ratio of M2 to the first molar (M1), the change in the angulation of M2 between pre- and postorthodontic treatment, and the distal bone level of M2 were assessed. RESULTS: The angular difference and ratio of M2 to M1, the angulation change of M2 between pre- and postorthodontic treatment, and the distal bone level of M2 were higher in the nonextraction group than in the control and extraction groups. CONCLUSIONS: The successful orthodontic alignment of the M2 may not be achieved in nonextraction cases when the M3s are present.

Mesiobuccal root canal anatomy of Korean maxillary first and second molars by cone-beam computed tomography.

OBJECTIVE: The aim of this study was to investigate the types of canal configurations and the incidence of a second mesiobuccal (MB2) canal in Korean maxillary molar mesiobuccal (MB) roots by analyzing cone-beam computed tomographic (CBCT) images. STUDY DESIGN: Three-dimensional CBCT images of 458 maxillary first molars and 467 second molars from 276 Korean patients were analyzed to determine the incidence of an MB2 canal, the types of canal configurations, and the correlations between the incidence of an MB2 canal and age, gender, and tooth position. RESULTS: The incidence of 2-canaled MB roots was 71.8% in first molars and 42.2% in second molars, with the most common configurations being Weine types III and II. The frequency of an MB2 canal decreased with age in both molars (P < .05). CONCLUSIONS: Types III and II canal configurations were the most prevalent in the 2-canaled MB roots of Korean maxillary molars.