Comparison of the Accuracy of CBCT Images and Apex Locator in Detection of External Root Resorption with Perforation.

Statement of the Problem: Perforation within external root resorption (ERR) lesions dra-matically affects the prognosis of the involved roots. Failure to diagnose perforation under-mines treatment; therefore, early detection of these lesions is of great importance. The cone-beam computed tomography (CBCT) images and electronic apex locators (EAL) are reliably used to detect root perforations. Purpose: In this in vitro study, we compared the EAL findings with the results obtained by the CBCT images for the detection of perforations within ERR lesions. Materials and Method: This cross sectional study included 160 extracted anterior human teeth. The teeth were categorized into four groups including teeth with intact root, teeth with ERR, teeth with ERR and 0.5 mm perforation, and teeth with ERR with 1 mm perforation. The presence of perforations was compared by CBCT images and root EAL. Results: The sensitivity of CBCT scans in detecting 0.5 mm and 1 mm root perforations was 100% and 97.5%, respectively, while the sensitivity of the EAL was 10% and 27.5% in de-tecting 0.5 mm and 1 mm root perforations, respectively( with the ±0.5mm range of error). For detecting intact and teeth with ERR, the specificity of CBCT scans was 100% and 95%, respectively, and for EAL, it was 100% for both. Poor agreement was found between the two techniques (kappa=-0.025). Conclusion: CBCT scans were more sensitive and specific than EAL scans for detecting perforations in non-obturated root canals in this study.

Assessment of sodium thiosulfate neutralizing effect on micro-hardness of dentin treated with sodium hypochlorite.

BACKGROUND: This study aims to evaluate the ability of sodium thiosulfate (STS) to neutralize the adverse effect of sodium hypochlorite (NaOCl) on dentin micro-hardness. METHODS: Fifty single-rooted teeth were longitudinally sectioned. The samples divided into a control and four sample groups (n = 20). All the samples were immersed in different solutions as follows, Control: Normal saline for 15 min, G1and G2: 2.5% NaOCl for 15 min, G3: 2.5% NaOCl for 15 min, followed by 5% STS for 10 min, G4: Normal saline for 15 min followed by 5% STS for 10 min. All groups except G1 incubated for one week before the test. The micro-hardness of samples was measured. Data were analyzed using the Kruskal-Wallis test for pairwise comparisons. A p value < 0.05 was considered significant. RESULTS: All groups showed a significant decrease in the micro-hardness value compared with the control group. NaOCl for one week (G2) reduced the micro-hardness of dentine compared with samples, tested immediately after immersion in NaOCl (G1) (p < 0.05). NaOCl alone (G2) or treated with STS (G3) resulted in a significant decrease in micro-hardness compared with the STS group (G4) (p < 0.05). CONCLUSIONS: STS as a neutralizing agent could not prevent the dentin micro-hardness downturn caused by NaOCl.

Influence of calcium hydroxide residues after using different irrigants on the accuracy of two electronic apex locators: An in vitro study.

BACKGROUND: The purpose of this study was to evaluate the effect of calcium hydroxide (Ca[OH] 2) residues on the accuracy of two electronic apex locators (EALs) (Root ZX and Raypex 6) in the presence of different irrigants. MATERIALS AND METHODS: In this an in vitro study Eighty single-rooted human mandibular premolars were selected. The crowns of the teeth were removed to standardize the working lengths (WLs). Actual WLs (AWLs) were recorded, and the root canals were shaped using protaper rotary instruments up to size F3. Then, the root canals were dried and filled with injectable Ca (OH) 2 paste and the access cavities were temporarily sealed. Teeth were put into four alginate boxes, including two experimental groups (n = 30) and two control groups (n = 10). The pools of alginate were wrapped in wet gazes and stored at 37°C and 100% humidity for 7 days. Then, the root canals were exposed and Ca (OH) 2 paste was removed by normal saline or 5.25% sodium hypochlorite irrigation followed by 17% ethylenediaminetetraacetic acid (EDTA), and the electronic WL (EWL) was measured by Root ZX and Raypex 6. Differences of EWL from AWL were calculated. Furthermore, the percentage of acceptable measurements (tolerance limit of ± 0.5 and ± 1 mm) was calculated for each apex locator. One-way ANOVA test with post hoc paired t-test and Chi-square test was used to analyze the data (P < 0.05). RESULTS: The results showed that there was no significant difference between the accuracy of two EALs and irrigants (P > 0.05). CONCLUSION: The present study revealed that no statistically significant differences were observed between the two apex locators after Ca(OH)2 paste removal with different irrigants.

Effect of Different Water-to-powder Ratios on the Solubility and Microhardness of Calcium-Enriched Mixture Cement.

Introduction: The aim of this study was to evaluate the effect of different water-to-powder (WP) proportions on the microhardness and water solubility of calcium-enriched mixture (CEM) cement. Methods and Materials: One gram of CEM cement powder was mixed with 0.33 mL, 0.4 mL or 0.5 mL CEM liquid. For water solubility, a total of 60 specimens were prepared (n=20 per each ratio) in the disk-shaped stainless-steel molds with a height of 1.5±0.1 mm and internal diameter of 10.0±0.1 mm. The specimens of each WP ratio were randomly divided into two subgroups: half (n=10) were immersed for one day and the other half (n=10), were kept for 21 days in distilled water. The solubility was calculated as a percentage of the weight loss. To measure microhardness, a total of 30 samples were prepared (10 per each ratio, n=10). The mixtures were transferred to metallic cylindrical molds with internal dimensions of 6±0.1 mm height and 4±0.1 mm diameters. After 4 days the specimens were subjected to Vicker's test. The data were analyzed using two-way ANOVA and post-hoc Tukey's tests at a significance level of 0.05. Results: The 0.33 WP ratio showed significantly greater microhardness value (25.98±2.77) compared to 0.4 and 0.5 proportions (P=0.004 and P<0.001 respectively). Significant differences were observed between water solubility values of different WP ratios at both time intervals (P<0.001). At both time intervals, 0.33 and 0.5 WP ratios exhibited the lowest and highest solubility, respectively. Conclusion: According to the results of this in vitro study, higher WP ratios result in lower microhardness and higher water solubility of the CEM cement. Therefore, the 0.33 WP ratio would be the ideal proportion.

Clinical and Histopathologic Investigation of Periapical Actinomycosis with Cutaneous Lesion: a Case Report.

Management of an extra-radicular infection is a challenging procedure that requires surgical intervention. This report describes a patient with discharging cutaneous lesion that required apical surgery. A 40-year-old woman was referred to the Department of Endodontics, Shiraz Dental School with chief complaint of a cutaneous sinus tract. She had been treated by a dermatologist and an otolaryngologist. The patient had also received orthograde root canal treatment of tooth #16. Yet, the lesion was still discharging and the patient was scheduled for surgery. Histopathologic analysis of the lesion showed actinomycosis infection. A 36-month follow-up revealed clinical and radiographic healing.