A Clinical Evaluation of Cone-beam Computed Tomography: Implications for Endodontic Microsurgery.

INTRODUCTION: Cone-beam computed tomographic (CBCT) imaging is a valuable diagnostic tool for endodontics. Some studies report that CBCT images have limitations in representing the true clinical presentation. This prospective, in vivo study compared limited field of view (LFOV) CBCT measurements with clinical measurements made during endodontic surgery. METHODS: Eighty-seven subjects requiring endodontic surgery and LFOV CBCT acquisition of the surgical site were enrolled. Data collection involved clinicians answering standardized questions during the radiographic and surgical assessment. Intraoperatively, data were collected and photographically documented. Postoperatively, CBCT scans were evaluated by 3 calibrated, board-certified specialists: 2 endodontists and 1 oral and maxillofacial radiologist. The 2 subsets of data were compared through statistical analysis to quantify their relationship. RESULTS: The subjects included 65 maxillary and 29 mandibular teeth from 87 subjects: 25 women and 62 men with an average age of 42 years old. The CBCT evaluators correctly identified the presence or absence of buccal plate fenestrations with 91.0% accuracy (95% confidence interval, 83.1-96.0) with 89.4% sensitivity and 92.9% specificity. The area of fenestrations measured clinically (mean = 19.6 ± 33.4 mm2) was generally larger than the area measured by CBCT imaging (mean across CBCT evaluators = 12.2 ± 19.1 mm2). Fenestration size in the maxillary arch was more likely to be underestimated than in the mandibular arch (P < .0001). Vertical bone height was also underestimated when measured on CBCT imaging. CONCLUSIONS: Based on the findings of this study, LFOV CBCT imaging accurately identifies the presence or absence of buccal plate fenestrations, yet, when a fenestration is present, underestimates its area.

Effect of EDTA preparations on rotary root canal instrumentation.

INTRODUCTION: The aim of this study was to evaluate whether rotary instrumentation using saline, EDTA 17% solution, or RC-Prep (Premier Dental, Philadelphia, PA) resulted in differences in root canal transportation. The secondary objective was to assess if instrumentation using these agents caused changes in the working length and canal volume. METHODS: Moderately curved mesiobuccal roots of 24 maxillary molars were standardized in length and randomized into 1 control and 2 experimental groups. The canals were instrumented with 0.04 taper rotary files to size #30. All groups were irrigated with saline. Group 1 was also irrigated using EDTA 17% solution (Pulpdent Corp, Watertown, MA), and in group 2, RC-Prep was used. X-ray micro-computed tomographic scans and working length measurements were made before and after instrumentation. Three-dimensional models were created from the pre- and postinstrumentation scan data and compared for volume changes. Centroid points were calculated in cross-sectional slices of the canals, and transportation was determined by measuring the distance between the pre- and postinstrumentation points. The data were analyzed with 1-way analysis of variance (α = 0.05) and the Tukey post hoc test. RESULTS: Less transportation was observed in group 2 than in group 1 (P = .001) and the control group (P = .014). Transportation in group 1 and the control group was not significantly different. Canal volume in group 1 was increased relative to group 2 (P = .004) and the control group (P = .022). No significant differences in the working length were observed. CONCLUSIONS: The use of chelating agents during root canal instrumentation did not significantly increase apical transportation.

Effect of varying water-to-powder ratios on the setting expansion of white and gray mineral trioxide aggregate.

INTRODUCTION: Clinicians commonly mix mineral trioxide aggregate (MTA) to a desired consistency rather than use the recommended amounts of powder and water. The purpose of this in vitro study was to evaluate how varying the water-to-powder (WP) ratio affects the setting expansion of white MTA (WMTA) and gray MTA (GMTA). METHODS: Eight combinations (n = 5) of WMTA and GMTA were mixed using varying WP ratios. Randomized samples were placed in a linear variable displacement transformer and submerged under Hank's balanced salt solution for 25 hours. Expansion was compared using a 2-way analysis of variance (alpha = 0.05). RESULTS: Mean percent expansions ranged from 0.058%-0.093% for WMTA and 2.15%-2.56% for GMTA. GMTA expanded significantly more than WMTA at p = .001. No differences in expansion were found between WP ratios (p = .218). No significant interaction was found between the WP ratio and material type (p = .228). CONCLUSIONS: GMTA expanded significantly more than WMTA; however, varying the WP ratio did not affect the setting expansion.

Effect of shortened irrigation times with 17% ethylene diamine tetra-acetic acid on smear layer removal after rotary canal instrumentation.

The purpose of this study was to evaluate whether irrigation times of 1 minute or less with 1 mL of 17% ethylene diamine tetra-acetic acid (EDTA) effectively removed the smear layer from root canals after rotary instrumentation. Forty single-canal teeth were decoronated, instrumented, and divided into 3 experimental groups (n = 10). Ten teeth served as positive and negative controls. The experimental groups received a final rinse with 1 mL of 17% EDTA for 1 minute, 30 seconds, or 15 seconds followed by a final 3-mL rinse with 6% NaOCl. Teeth were split longitudinally and prepared for scanning electron microscopy imaging. Digital images (350x) of the approximate center of the coronal, middle, and apical sections were graded for quality of smear layer removal by 3 endodontists. Data were analyzed with nonparametric tests, with significance level set at alpha = .05. Significantly greater smear layer removal was found in the 1-minute EDTA irrigation group than the 30-second or 15-second groups.

Fluid flow evaluation of Fuji Triage and gray and white ProRoot mineral trioxide aggregate intraorifice barriers.

The purpose of this study was to compare coronal leakage in teeth with 2-mm intraorifice barriers of Fuji Triage glass ionomer, gray mineral trioxide aggregate (MTA), and white MTA using a fluid flow model. Forty anterior teeth were decoronated, instrumented, and obturated. Teeth were divided into positive and negative controls and 3 experimental groups receiving 2-mm barriers of Fuji Triage glass ionomer, gray MTA, or white MTA. Fluid movement was tested 3 times for each tooth, and means were calculated. Data were analyzed with one-way analysis of variance and Student-Newman-Keuls (alpha = .05). Fluid movement means and standard deviations were as follows: Fuji Triage, 0.47 +/- 0.45 mm; gray MTA, 0.49 +/- 0.44 mm; white MTA, 0.52 +/- 0.23 mm; and positive controls, 3.57 +/- 1.13 mm. No significant differences were found among the experimental groups. However, positive controls leaked significantly more than all experimental groups at P <.001.