Efficacy of Two Rotary NiTi Instruments in Removal of Resilon/Epiphany Obturants

Introduction: The success of endodontic retreatment is related to the complete removal of the obturation material from the root canal system. The aim of this study was to evaluate the efficacy of Mtwo R and ProTaper retreatment files in removing the Resilon/Epiphany system with or without chloroform during retreatment.Materials and Methods: Sixty distal roots of first mandibular molars were prepared and laterally condensed with Resilon/Epiphany, then divided into four groups (15 each for retreatment): 1) Mtwo R/solvent; 2) Mtwo R; 3) ProTaper D/solvent; and 4) ProTaper D. The cleanliness of the canal walls was evaluated using radiography; a stereomicroscope and SEM. Data were subjected to ANOVA and Student’s t-test.Results: Neither rotary system performed better than the other when considering the whole root canal, with or without solvent. In the apical portion, ProTaper/solvent showed the best result (P<0.05).Conclusion: In Resilon/Epiphany retreatment cases, ProTaper/solvent was better in the apical portion; however when considering the whole canal, Mtwo R and the ProTaper D series had the same performance

X-ray Diffraction Analysis of ProRoot Mineral Trioxide Aggregate Hydrated at Different pH Values

Introduction: The aim of this study was to compare the chemical compounds of white ProRoot mineral trioxide aggregate (WMTA) hydrated at different pH environments. Methods and Materials: Mixed samples of WMTA were kept in acidic (pH=5.4), neutral (pH=7.4) and alkaline (pH=9.4) environments for 48 h. Then, X-ray diffraction (XRD) analysis was performed for both hydrated and powder forms of WMTA. Portlandite crystalline structures of environments were compared from three aspects: intensity (height of the peak, corresponding to the concentration), crystallinity (peak area/total area) and crystal size (full-width at half-maximum of the peak). Results: After matching the peaks of each sample with those of the International Center for Diffraction Data (ICDD) database, the main constituent of all set cements and powder form was found to be bismuth oxide. Acidic environment exhibited lower intensity and crystallinity of portlandite in comparison with neutral environment. Conclusion: The highest concentration and crystallinity of portlandite were observed in WMTA samples hydrated at neutral pH and the highest crystal size was detected after hydration in alkaline pH.Keywords: Mineral Trioxide Aggregate; pH; X-ray Diffractio

Incidence of Dentinal Crack Formation Using ProTaper Universal and WaveOne Systems in Straight and Curved Root Canals

Introduction: This study aimed to compare dentinal micro crack formation following root canal instrumentation with ProTaper Universal (PTU) and WaveOne (WO) rotary systems in straight and curved root canals. Methods and Materials: One hundred mesiobuccal (MB) straight and curved canals of mandibular molars meeting inclusion criteria were divided into two control (n=10) and four experimental groups (n=20). After mounting the teeth and simulating the periodontal ligament, all the MB canals were coronally flared using Gates-Glidden drills #3 and 2 respectively. Then, in the experimental groups, the canals were instrumented with either PTU files (Sx, S1, S2, F1, F2), or Primary WO (25/0.08). Afterwards, roots were horizontally sectioned at 2, 4, and 6 mm from the apices, and evaluated under a microscope under 20× magnification. Data were analyzed with the Chi-Square and Kruskal-Wallis tests. The significance level was set at 0.05. Results: The control groups showed no cracks. There was no significant difference between the two systems in the straight root canals (P>0.05). But in the curved root canals, PTU produced significantly more cracks (P<0.05) with the complete crack type which was dominant (P=0.013) compared to WO. Conclusions: This in vitro study showed that in curved root canals, instrumentation with reciprocal WO system may be safer than full rotational PTU instruments regarding crack formation.Keywords: Crack; Dentin; Instrumentation; Reciprocating; Root Canal Preparation

Knowledge and clinical judgment of Iranian general dentists on vertical root fracture

BACKGROUND AND AIM: This study was conducted with the aim to investigate the knowledge and clinical judgment of Iranian general dentists and related factors on the diagnosis and treatment plan of vertical root fracture (VRF). METHODS: A questionnaire was distributed among 300 general dentists who attended in Iranian General Dentists Association (IGDA) congress in 2015. The questionnaire comprised of demographic information and nine closed-end questions on the knowledge on VRFs and different treatment options and seven photographs for clinical judgment evaluation. The answers to all questions were assessed and data were analyzed by chi-square test. RESULTS: 271 individuals (50.7% men and 49.3% women) participated in the study and responded the questions of the questionnaire correctively. Of the subjects, 88.3% and 76.3% had low to moderate clinical judgment and knowledge about vertically fractured teeth, respectively. The correlation between knowledge of participants attending in short endodontic courses was higher than that of those not attended in these courses; the difference between these two groups was statistically significant (P = 0.0005). The correlation between clinical judgment, gender, past clinical activity, attendance in short endodontic courses, and field of clinical interest among participants was not significantly different (P = 0.1900). CONCLUSION: It seems that knowledge and clinical judgment are weak among general dentists requiring serious improvement. Fortunately, short endodontic courses may improve their knowledge of diagnosis and interventions related to teeth undergoing VRF. KEYWORDS: Surveys and Questionnaires; Judgment; Dentists; Tooth Fractures; Tooth Roo

Incidence, location, and type of isthmus in mandibular second molars among individuals of an Iranian population

BACKGROUND AND AIM: Isthmuses are narrow and strip shaped connections between two canals containing pulpal tissue that may encompass bacteria as well. They are hardly accessible for cleaning; therefore, success and failure of root canal treatments could be affected by their presence. The present study was carried out aiming to evaluate the incidence, location, and type of isthmus in mandibular second molars (MSMs) among individuals of an Iranian population. METHODS: 80 MSMs with inclusion criteria, belonging to individuals of an Iranian population were collected and disinfected. After embedding the samples’ roots in the acrylic resin, teeth were sectioned horizontally at 2, 4, and 6 mm distances from the apices. Then they were viewed and recorded by a stereomicroscope under × 30 magnification. According to Kim classification, two endodontists recorded the number of canals, incidence, and type of the isthmuses. In cases of disagreement, a third endodontist was involved to judge on the right opinion between the two. The acquired data were analysed using chi-square test. RESULTS: The results showed that 96.3% and 3.75% of MSMs had two and three roots, respectively. Type V (described in the following) was the most frequent type of isthmus at mesial and distal roots. C-shaped canals composed 3.7% of the samples and showed isthmus at all the three sections. There was a significant difference in the distribution of isthmuses (P < 0.001). CONCLUSION: According to this study, different types of isthmuses prevail in high rate of mesial and about half of the distal roots of MSMs, which are important for root canal cleaning and shaping. KEYWORDS: Anatomy; Molar; Tooth; Root Cana