Compared to the removal kit, removal of the fiber posts with an ultrasonic tip decreases the fracture resistance of the roots, although significantly more time is required.

The aim of this in vitro study was to compare the efficacies of two different fiber post‐removal systems. Thirty extracted single‐rooted mandibular premolar teeth were used. After RelyX fiber posts were cemented, the teeth were divided into two groups with regard to the post removal techniques: ultrasonic vibration and D.T. Light‐Post removal kit. Residual material, tooth volume changes, working time and micro‐crack formation were assessed using micro‐computed tomography. All data were analyzed using Wilcoxon signed‐rank and Mann–Whitney U tests. There was significantly more tooth root volume change in the ultrasonic group than removal kit group (p < .05). Fiber post removal time for the ultrasonic group was significantly longer than the removal kit group (p < .01).

The purpose of this study was to evaluate the presence of dentinal defects after root canal preparation with hand instruments and two different reciprocating instruments. Sixty freshly extracted mandibular incisor teeth were selected for this in vitro study. On the basis of root length, mesiodistal and buccolingual dimensions, the teeth were allocated into three identical experimental groups (n = 15) and one control group (n = 15). The teeth in the control group were left unprepared. The other groups were: stainless steel hand instruments, WaveOne® Primary instruments and RECIPROC® R25 instruments. The reciprocating instruments were used with a reciprocating gentle in-and-out motion in a torque-limited electric motor at the appropriate preset mode. Horizontal sections were made 3, 6 and 9 mm from the apex. Samples were stained with methylene blue and viewed through a stereomicroscope. The presence of dentinal defects (fractures, incomplete cracks and craze lines) and their locations were investigated by two endodontists. These data were analysed statistically by Fisher's exact and chi-square tests. No defects were observed in the unprepared group. All instruments caused dentinal defects, with no significant differences between the instrument systems. All experimental groups demonstrated significantly more defects at the 3-mm level in comparison with the unprepared group (p = 0.032). At the other levels, there was no significant difference between the experimental groups and the control group. The use of hand or reciprocating instruments could induce the formation of dentinal defects during root canal preparation.

Dens invaginatus is a developmental anomaly that results in an enamel-lined cavity intruding into the crown or root before the mineralization phase. This report presents regenerative endodontic treatment of a necrotic immature tooth with Oehler's type III dens invaginatus of a nine-year-old female patient. A diagnosis of dens invaginatus (Oehler's type III) and a large periapical lesion was established with the aid of cone-beam computed tomography (CBCT). In the presented case contrary to the classic revascularization protocol, mechanical instrumentation was performed which apparently did not interfere with the regeneration process. After mechanical instrumentation of the invaginated canal by manual K-files, the invaginated canal space was disinfected by triple antibiotic paste followed by blood clot induction from the periapical tissues and the placement of mineral trioxide aggregate. At one-year follow-up, the tooth remained clinically asymptomatic. Radiographic examination revealed complete healing of the periapical lesion. At the 20-month follow-up, the radiographic examination also showed that the open apex was closed and the walls of the root canal were thickened.

Dens invaginatus is a developmental anomaly that results in an enamel-lined cavity intruding into the crown or root before the mineralization phase. It typically affects permanent maxillary lateral incisors, central incisors, and premolars. This paper describes the root canal treatment of Oehlers' type II dens invaginatus in maxillary left lateral incisors. A 16-year-old boy presented to the Faculty of Dentistry, University of Kocaeli, to receive his dental treatments. During the caries removal, the pulp was exposed then anendodontic treatment was initiated. Two canals, one of which represented the invagination, were instrumented, irrigated, and then obturated with a lateral condensation technique.