Do cell phones affect establishing electronic working length?

INTRODUCTION: Patients often keep their cell phones on and nearby during root canal therapy. Cell phones release electromagnetic interference, which might disturb electronic working length measurements. The purpose of this ex vivo study was to determine the effect of a cell phone (Apple iPhone 5 [Apple, Cupertino, CA] or KP100 [LG, Seoul, Korea]) placed into direct contact with an electronic apex locator (EAL) (Dentaport Root ZX module [J Morita Corp, Tokyo, Japan] or Propex II [Dentsply Maillefer, Ballaigues, Switzerland]) on working length determination. METHODS: Twenty-six human premolars without fractures or carious lesions were used; previously cleaned; and observed under magnification (×15) in order to check for the presence of only 1 apical foramen, the absence of apical resorption, an "open" apex, and accessory canals. The working length measurement was performed with a #15 K-file in the presence of 2.6% sodium hypochlorite under 4 conditions: (1) visually, under the microscope until the file tip reached the canal terminus; (2) electronically, without the cell phone in proximity; (3) electronically, with the cell phone in standby mode placed in physical contact with the EAL; and (4) electronically, with the cell phone activated by a call in the same position. The experimental model for electronic working length determination was a screw top plastic container filled with a saline solution. The measurements were repeated 3 times per canal under each condition. Scores of 1 to 3 categorized the stability of the readings as follows: (1) good stability; (2) unstable reading with minor difficulties determining the working length; and (3) major difficulties or impossible to determine the working length. A 2-way repeated measures analysis of variance (way 1: cell phone type and way 2: EAL model) was performed, and a second repeated measures analysis of variance was performed to seek a difference among the 4 working length determination conditions. RESULTS: Neither the cell phone type nor the EAL affected the measurements (not significant). The electronic working length measurements gave the same results as the visual examination, and this length was not influenced by direct contact with a cell phone (not significant). It was also possible to determine the electronic working length under all the experimental conditions. CONCLUSIONS: Within the limitations of the present study, it can be concluded that patients can keep their cell phones on during root canal therapy without any adverse effect on electronic working length determination.

Influence of acid etching on hydrogen peroxide diffusion through human dentin.

PURPOSE: To evaluate the influence of dentin etching with phosphoric acid on hydrogen peroxide diffusion through human dentin in internal bleaching. METHODS: 46 human premolars were extracted for orthodontic reasons from adolescents. The teeth were endodontically treated and a flat defect was created at the enamel-cementum junction. The teeth were divided into two groups: the access cavity was etched for 30 seconds with 35% H3PO4 in the first group and left intact in the second group. The teeth were filled with 20 microL of 35% hydrogen peroxide gel. The receiving medium on the other side was renewed at Day 1, Day 2 and Day 7 to quantify the diffusing hydrogen peroxide. An analysis of variance was performed to compare the diffusion between the two groups. RESULTS: This work demonstrated a higher hydrogen peroxide diffusion when the access cavity was etched (P < 0.01).

Biological properties of a neutralized 2.5% sodium hypochlorite solution.

OBJECTIVES: The objective of this study was to evaluate the influence of neutralizing a 2.5% NaOCl solution on its cytotoxicity, genotoxicity, and tissue-dissolving potential. STUDY DESIGN: The cytotoxicity and the genotoxicity of Dakin, a 2.5% NaOCl solution, and a neutralized 2.5% NaOCl solution were assessed according to ISO 10993 standards. The weight of palatal mucosa samples placed in neutralized 2.5% NaOCl, 2.5% NaOCl was recorded over time as well as the pH of the solutions. RESULTS: The neutralized 2.5% NaOCl solution was 10-fold more cytotoxic than the 2.5% NaOCl solution. None of the solutions was genotoxic. The 2.5% NaOCl solution had a better tissue-dissolving capacity than the neutralized 2.5% NaOCl solution. The pH of the 2.5% NaOCl solution and neutralized 2.5% NaOCl solution decreased from 12 to 9 and from 7.5 to 5.6, respectively. CONCLUSION: Neutralizing a 2.5% NaOCl solution increased its cytotoxicity, did not induce any genotoxic effect, and reduced its tissue-dissolving ability.

Shelf life, dissolving action, and antibacterial activity of a neutralized 2.5% sodium hypochlorite solution.

OBJECTIVES: The aim was to evaluate the shelf life and the dissolving and antibacterial properties of a neutralized 2.5% NaOCl solution. STUDY DESIGN: The loss of available chlorine and the pH of the neutralized 2.5% NaOCl solution were recorded to determine its shelf life. The dissolving action on bovine dental pulp was assessed measuring weight loss, pH variation, and decrease in available chlorine content. The antibacterial activity was evaluated on artificially infected human teeth. The roots were endodontically prepared, sterilized, and inoculated with Enterococcus faecalis before irrigation with the neutralized solution. The presence of intracanal bacteria after irrigation was recorded. RESULTS: The neutralized solution presented a shelf life of 2 hours, dissolving capacities equivalent to control for the first 5 minutes, and a better antibacterial efficiency. CONCLUSION: The neutralized 2.5% NaOCl solution must be used within 2 hours after mixing, should be frequently renewed to maintain its dissolving capacities, and presented enhanced antibacterial properties.

Lack of correlation between ex vivo apical dye penetration and presence of apical radiolucencies.

OBJECTIVE: The aim of this study was to determine if there is a significant correlation between the in vivo presence of periapical radiolucency and ex vivo apical dye penetration on the same human teeth. STUDY DESIGN: Eighty-four endodontically filled teeth that were scheduled for extraction were classified into 2 groups according to the presence or absence of a periapical radiolucency and further divided into 2 subgroups according to the quality of the root canal filling. After extraction, the apical filling was evaluated by a dye penetration method. RESULTS: The dye extraction evaluation showed no correlation between apical dye penetration and the presence of a periapical radiolucency (not significant), but a statistically significant correlation with the quality of the root canal filling (P = .03). CONCLUSION: The results of the dye penetration study were correlated to the quality of the root canal filling but had no predictive value for the development of periapical radiolucency.

Evaluation of periapical lesion healing by correction of gray values.

The purpose of this study was to compare two methods for evaluating periapical healing in humans: the periapical index (PAI) and a gray value correction method. Fifty human teeth with a periapical lesion were endodontically treated. Radiographs, with a special aluminum device, were taken postoperatively, after 3 months and after 6 months. The PAI was recorded at each period of time, and a Kruskall and Wallis test was performed to compare the three groups. After scanning, the size of the lesion and its gray value were recorded. The aluminum device allowed the gray values to be equalized. An analysis of variance followed by a Duncan test was performed to compare the three groups. The teeth that showed no sign of healing according to the PAI were separately analyzed by an analysis of variance and a Duncan test. The PAI (n = 50) showed signs of periapical healing over time (p < 0.01). The analysis of variance, based on gray value evaluation (n = 50), also showed signs of periapical healing over time (p < 0.002). The analysis of variance of teeth with the same PAI over time (n = 15 at 3 months, and n = 5 at 6 months), based on gray value evaluation showed statistically significant differences among the 3 groups (p < 0.02). These results show that the gray level correction method is powerful and may reduce the risks of false negative responses during assessment of treatment results or epidemiological studies.

Apical leakage of four endodontic sealers.

The purpose of this study was to evaluate the sealing properties of four root canal sealers. Forty-eight maxillary central incisors were instrumented with Profile rotary instruments. They were randomly divided into four groups (n = 12) and filled using lateral condensation with one of the four sealers: Sealapex, Pulp Canal Sealer, AH 26, and Ketac-Endo. The apical leakage was measured with a fluid filtration method and expressed as L s(-1) KPa(-1). The teeth filled with Sealapex displayed a higher apical leakage (8.42 +/- 4.2 10(-11) L s(-1) KPa(-1)) than those filled with AH 26 (2.10 +/- 1.39 10(-11) L s(-1) KPa(-1)), Pulp Canal Sealer (0.17 +/- 0.09 10(-11) L s(-1) KPa(-1)) or Ketac-Endo (0.32 +/- 0.24 10(-1) L s(-1) KPa(-1)) (p < 0.01). No statistically significant difference was found among AH 26, Pulp Canal Sealer, and Ketac-Endo. No correlation was found between the sealing efficiency of the four sealers and their adhesive properties recorded in a previous study.