Apical extrusion of debris after canal shaping with three single-file systems.

OBJECTIVES: The aim of this study was to evaluate the quantity of apically extruded debris after canal shaping with three single-file systems. MATERIALS AND METHODS: Sixty mesiobuccal canals of mandibular molars were divided into three experimental groups according to the used file systems-WaveOne Gold, RECIPROC Blue, and HyFlex EDM One file. Debris extruded during canal shaping were collected in preweighed vials. Each canal was irrigated with 5 mL of distilled water via a 30 G side-vented needle. The amount of the debris extruded from each canal was calculated by subtracting the preinstrumentation from postinstrumentation measurement. The preparation times were recorded. Data were analyzed using analysis of variance (ANOVA) and posthoc Tukey tests with α = 0.05. RESULTS: WaveOne Gold extruded the least amount of debris. Results between WaveOne Gold and HyFlex EDM were significantly different. No significant differences in canal shaping time were detected among the three groups (P > 0.05). CONCLUSION: WaveOne Gold showed the best results regarding apical debris extrusion. Difference between WaveOne Gold and HyFlex EDM suggests that file design and motion kinematics affect the quantity of debris extrusion.

Root and canal morphology of maxillary premolar teeth in an Egyptian subpopulation using two classification systems: a cone beam computed tomography study.

AIM: To investigate the number of roots and root canal configurations using two coding systems and the root canal diverging and merging levels in extracted maxillary premolars in an Egyptian subpopulation using cone beam computed tomography (CBCT). METHODOLOGY: A total of 700 maxillary premolars were examined using CBCT in an Egyptian subpopulation. The number of roots was identified, and root canal configurations were classified according to Vertucci's classification and a new system for classifying root and canal morphology. In addition, the position where roots bifurcated and the levels where canals merged or diverged were identified. Fisher's exact test and independent t-test were used for statistical analysis, and the level of significance was set at 0.05 (P = 0.05). RESULTS: More than half of maxillary first premolars were double-rooted, and the majority of maxillary second premolars were single-rooted (P < 0.001). Most of the double-rooted samples had bifurcations in the middle of the root. According to the Vertucci classification, canal configuration type IV was the most common in both first and second maxillary premolars. According to the new system, the code 2 FP B1 P1 was the most common for maxillary first premolars, whilst 2 SP B1 P1 , 1 SP2 and 1 SP2-1 codes were the most common for maxillary second premolars. The three-canalled morphology in double- and three-rooted maxillary premolars had considerable variations. Root canal merging and diverging levels were comparable in both tooth types. CONCLUSION: Maxillary premolars in this Egyptian subpopulation had a wide range of root and canal anatomical variations. Clinicians should be aware of where canals merge and diverge to facilitate the treatment of all canals. The new system for classifying canal morphology describes the root and canal configurations in a more accurate and practical manner compared to the Vertucci classification.

Incidence of dentinal defects after preparation of severely curved root canals using the Reciproc single-file system with and without prior creation of a glide path.

AIM: To investigate the incidence of dentinal defects after preparation of severely curved root canals using the Reciproc single-file system with and without prior creation of a glide path. METHODOLOGY: Mesial roots from extracted mandibular first molars were collected and scanned with CBCT to assess the morphology of the root canal systems. Three groups of 20 anatomically comparable specimens were generated. The control group was left unprepared, whilst the experimental groups were prepared with Reciproc R25 with and without a glide path (groups RG and R, respectively). Roots were then sectioned perpendicular to the long axis at 2, 4, 6, 8 and 10 mm from the apex, and coloured photographs of the sections at 40× were obtained. Two blinded examiners registered the presence of dentinal defects twice at 2-week interval. Data were statistically analysed using the Fisher exact and Cochran's Q tests. RESULTS: No defects were observed in the control group. The overall incidence of dentinal defects was 26% in group R and 24% in group RG, with no significant differences between them (P > 0.05). Dentinal defects occurred significantly more often in the middle and coronal thirds compared to the apical third of the canals (P < 0.05). CONCLUSIONS: Prior preparation of a glide path had no impact on the incidence of dentinal defects when using Reciproc files.

Comparative evaluation of the shaping ability of WaveOne, Reciproc and OneShape single-file systems in severely curved root canals of extracted teeth.

AIM: To compare the shaping ability of WaveOne, Reciproc and OneShape single-file systems in severely curved root canals in extracted human molar teeth. METHODOLOGY: Sixty mandibular molars with mesio-buccal canals with curvatures ranging between 25° and 35° and radii of curvature ranging between 4 and 9 mm were divided into three groups of 20 teeth each: group W (WaveOne), group R (Reciproc) and group O (OneShape). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvatures was determined using the NIH Image J software. A double-digital standardized radiographic technique was used to determine apical transportation at 0.5 mm from the working length (1.5 mm coronal to the major foramen). Preparation time and instrument failures were also recorded. Data were analysed using one-way analysis of variance (anova) and post-hoc Tukey-test. RESULTS: During root canal preparation, no instruments fractured but all OneShape instruments were deformed after preparation of four canals. The use of OneShape resulted in significantly greater canal straightening and apical transportation than WaveOne and Reciproc (P < 0.05), with no significant differences between WaveOne and Reciproc (P > 0.05). Instrumentation with OneShape was significantly faster than with WaveOne and Reciproc (P < 0.05), whilst Reciproc was significantly faster than WaveOne (P < 0.05). CONCLUSIONS: All instruments were safe to use. Reciproc and WaveOne instruments respected the original canal curvature better than OneShape files. The use of OneShape instruments required less time to prepare the curved canals compared with Reciproc and WaveOne.

Comparative evaluation of the shaping ability of ProTaper Next, iRaCe and Hyflex CM rotary NiTi files in severely curved root canals.

AIM: To compare the shaping ability of ProTaper Next, iRaCe and Hyflex CM rotary NiTi files during the preparation of severely curved root canals in extracted human molar teeth. METHODOLOGY: Sixty mandibular molars with mesio-buccal canals having angles of curvature ranging from 25° to 35° were divided according to the instrument used into three groups of 20 teeth each: group PTN (ProTaper Next), group IR (iRaCe) and group HF (Hyflex CM). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvature was determined using image analysis software. A double-digital standardized radiographic technique was used to determine apical transportation 0.5 mm from the working length (1.5-mm coronal of the major foramen). Preparation time and instrument failures were also recorded. Data were analysed using one-way analysis of variance (anova) and post hoc Tukey's test, and significance was set at P < 0.05. RESULTS: During root canal preparation, no instruments fractured. The use of PTN resulted in significantly greater canal straightening than IR and HF (P < 0.05), with no significant differences between IR and HF (P > 0.05). There were no significant differences between the three groups with respect to apical transportation (P > 0.05). IR and HF were significantly faster than PTN (P < 0.05), with no significant differences between IR and HF (P > 0.05). CONCLUSIONS: Under the conditions of this study, PTN, IR and HF respected original canal curvature well and were safe to use.