[Temperature variation at the external root surface during Nd: YAG laser irradiation in the root canal in vitro].

Objective: To assess the temperature variation of the root surface using Nd: YAG laser irradiation in the root canal with different power and to evaluate the safety of laser application on the periodontal region.

Methods: Thirty extracted human teeth with single-roots were collected. The teeth were cross-sectioned in the cervical portion, standardizing the roots at a 12-mm length.

[Clinical evaluation of large periapical lesions following apical surgery].

Objective: To evaluate the therapeutic effect of teeth with large periapical lesions followed apical surgery.

Methods: 59 patients (59 periapical lesions, 91 teeth) with large periapical lesions ranging in size from 6 mm to 21 mm in diameter were included in this study. All teeth were treated by root canal therapy and apical surgery, and the surgical procedure was completed with microsurgical technology and ultrasonic root-end preparation.

[Clinical evaluation on the root canal therapy bypassing intracanal separated instruments].

Objective: To study and evaluate the clinical effect of root canal therapy bypassing intracanal separated instruments.

Methods: 32 teeth were selected as the test group, from which the intracanal separated instruments couldn't be taken out, adopted the method of root canal preparation and obturation bypassing broken instruments. Meanwhile, 13 teeth were selected as the control group, in which the fractured instruments couldn't be taken out from root canal, and not be cured bypassing broken instruments.