Effects of three nickel titanium instrument systems on root canal geometry assessed by micro-computed tomography.

AIM: To compare and evaluate the shaping ability of several nickel titanium instrument systems with different motions: two reciprocating single-file systems (Reciproc and WaveOne) and one continuous rotation/reciprocation full-sequence system [Twisted File (TF) Adaptive] using micro-computed tomography. METHODOLOGY: A total of forty-eight mesial canals of mandibular molars with two separate root canals and severe angles of curvature were selected. Canals were divided randomly to one of three experimental groups: group 1, reciprocating instrumentation with Reciproc R25, group 2, reciprocating with the Primary WaveOne file and group 3 'Adaptive Rotary Motion' with Twisted Files. Each group consisted of 16 root canals. Canals were scanned before and after root canal preparation, with a resolution of 20 µm using a micro-computed tomography system. The following parameters were assessed: changes in dentine volume, percentage of unshaped canal walls, degree of canal transportation and centring ability. Data were analysed using analysis of variance and Tukey's post hoc tests test to explore a significant difference in mean dentine removal, mean percentage of noninstrumented canals, mean degree of canal transportation and centring ratio between groups in the apical third and along the entire root canal. The level of significance was set at α = 0.05. RESULTS: Preoperatively, there were no differences regarding root canal curvature and volume between experimental groups (P > 0.05). Overall instrumentation led to enlarged canal shapes with no evidence of preparation errors. None of the three groups was able to shape completely the root canal system. Mean dentine removal along the entire canal and in the apical third was significantly higher with Reciproc when compared with TF Adaptive and WaveOne (P = 0.013). Mean degree of canal transportation was significantly lower with TF Adaptive (P < 0.0001) followed by WaveOne and highest with Reciproc in the apical third and along the entire root canal. CONCLUSIONS: None of the NiTi systems was able to instrument completely the entire root canal. Reciprocation and Adaptive Motions were found to cut dentine efficiently to full working length, with no procedural errors. The TF Adaptive system maintained the original canal anatomy with less canal transportation and better centring ability.

Comparative micro-computed tomographic evaluation of two carrier-based obturation systems.

OBJECTIVES: The aim of the study was to measure the percentage of volume of voids and gaps in the apical third of root canals obturated with two techniques using micro-computed tomography. MATERIALS AND METHODS: Fifty-four single-rooted teeth were collected and root canal-prepared. The roots were randomly allocated into two groups; each group was obturated by using thermoplasticized technique with a different material (gutta-percha and Topseal for Thermafil, Resilon and RealSeal for RealSeal 1). Roots were then scanned, and volume measurements for voids and gaps in the obturated roots were carried out using specialized CT software. Percentage of gaps and voids was calculated. RESULTS: The present study showed that none of the root canal-filled teeth was gap free. Student t test was conducted. No significant difference was found between Thermafil and RealSeal 1 concerning percentage of voids in the apical third (P > 0.05). Both materials showed statistically significant difference between the levels where 1 mm showed the highest volume of voids (P < 0.05). CONCLUSIONS: Both carrier-based techniques allowed a good sealing ability in root canals but none of the materials was gap free. Statistically significant difference between the levels was found and 1 mm showed the highest volume of voids. CLINICAL RELEVANCE: This study shows the efficiency of carrier-based obturation systems in filling root canals hermetically. It compares new adhesive endodontic materials with the traditional gold standard gutta-percha. Results show the good sealing ability of both techniques making them appropriate to use in daily endodontic obturations.