Gary G. Goodell

In Vitro Comparison of Three Electronic Apex Locators

INTRODUCTION The purpose of this study was to compare the accuracy of the Root ZX II Apex Locator (RZX), the Elements Apex Locator (ELE), and the Precision Apex Locator (PAL). METHODS Forty single-rooted extracted teeth were decoronated and the root canals coronally flared. Actual canal lengths were determined by inserting a #10 file until the tip was visualized (12.8x magnification) just within the apical foramina. Teeth were mounted in gelatin conducting medium and randomly tested with each electronic apex locator (EAL) to determine the electronic canal length. Differences between the electronic and actual canal lengths were calculated. RESULTS The mean differences were -0.02 mm, 0.13 mm, and 0.15 mm for the RZX, PAL, and ELE, respectively. One-way analysis of variance showed a highly significant difference among EALs (p = 0.003). Student-Newman-Keuls post hoc analysis found significant differences between the RZX and the PAL and between the RZX and the ELE at p < 0.05. No significant difference was noted between the PAL and the ELE. The proportion of electronic canal length measurements falling within +/-0.5 mm of the actual canal lengths for the EALs was as follows: 97.5% for the RZX, 95% for the PAL, and 90% for the ELE. CONCLUSION The RZX was the most accurate at locating the apical foramen compared with the ELE and the PAL.

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.

An agar diffusion comparison of the antimicrobial effect of calcium hydroxide at five different concentrations with three different vehicles.

The purpose of this study was to determine if varying the percent (by weight) of aqueous calcium hydroxide or using different vehicles had an effect on its antibacterial efficacy against common endodontic pathogens in a pour plate/traditional streak agar diffusion model. Mixtures of calcium hydroxide powder and sterile saline in 40, 50 and 60 percent concentrations and the commercial preparations UltraCal XS and Vitapex were tested against six known endodontic pathogens with an agar diffusion method. Each medicament was placed in one of five wells, in each of 10 agar plates (n = 10), for cultures of each bacterial species. Zones of inhibition were measured after 48 hours incubation for aerobes and 96 hours incubation for anaerobes. Multiple one-way analyses of variance and post-hoc Student Neuman Keuls evaluated the data at alpha = 0.05. Larger zones of inhibition were consistently observed for higher concentrations of calcium hydroxide with statistical significance among the bacteria, particularly between 40% and 60%. Vitapex had significantly smaller zones of inhibition than all other medicaments and 35% UltraCal XS with methylcellulose was nearly as effective as 50% Ca(OH)(2) in inhibitory activity. Formulations containing 50-60% Ca(OH)(2) or 35% Ca(OH)(2) with aqueous methylcellulose are recommended as endodontic interappointment medicaments.

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.

In vitro comparison of coronal microleakage between Resilon alone and gutta-percha with a glass-ionomer intraorifice barrier using a fluid filtration model.

The prevention and control of coronal microleakage is critical for successful endodontic outcomes. The purpose of this study was to compare coronal microleakage between Resilon alone and gutta-percha with a glass ionomer intraorifice barrier using a fluid filtration model. Thirty-four extracted human teeth were decoronated, prepared to a standardized length of 16 mm, and instrumented to a .06 taper ISO size 40. After removal of controls, the remaining roots were randomly divided into two equal groups of 15 and obturated with either Resilon alone or gutta-percha with a 2-mm glass-ionomer intraorifice barrier. After set of the sealers, the teeth were evaluated for microleakage using a fluid filtration model. A Student t test found significantly less leakage for the gutta-percha/glass-ionomer intraorifice barrier group than the Resilon alone group (p = 0.008).

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 Hanks 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.

Linear Dye Penetration of a Calcium Phosphate Cement Apical Barrier

Linear dye penetration was evaluated in teeth with open apices in which calcium phosphate cement was used as an apical barrier to facilitate obturation. The apical foramens of 42 extracted single-rooted human teeth were opened to a size 90 file. Half the teeth received apical barriers consisting of calcium phosphate cement (CPC) followed by obturation using a customized gutta-percha cone/ lateral condensation technique. The other half were obturated without benefit of apical barriers. Linear dye penetration was measured after 48 h exposure to India ink. The teeth receiving apical CPC barriers before obturation had significantly less dye penetration than teeth without apical barriers. Based on its proven biocompatibility and osteconductive potential, calcium phosphate cement may serve well as a replacement for calcium hydroxide in a single-visit immediate apical barrier apexification technique.

Effect of Dentin Thickness on Root Surface Temperature of Teeth Undergoing Ultrasonic Removal of Posts

The purpose of this study was to measure root surface temperature changes on thin-rooted and thick-rooted teeth undergoing ultrasonic vibration of cemented posts, with and without irrigation. Twenty-four single canal teeth were decoronated, length standardized, instrumented, obturated, and cemented with prefabricated posts. The teeth were divided into thin-rooted or thick-rooted groups. Thermocouples were cemented to the external proximal root surfaces adjacent the post ends. The roots were then mounted in standardized plaster molds and placed in a temperature-controlled water bath. Posts were ultrasonically vibrated with and without irrigation, and external root temperatures were recorded from an initial 37 degrees C baseline for a period of 4 minutes. The data were analyzed with the Student t test at alpha = .05. No significant differences were found in temperature change between the thin-rooted and thick-rooted groups, with or without irrigation. Linear regression and correlation analysis revealed no relationship between dentin thickness and temperature change.