José Antônio Poli de Figueiredo

Influence of Voxel Size in the Diagnostic Ability of Cone Beam Tomography to Evaluate Simulated External Root Resorption

This study assessed in vitro the diagnostic ability of cone beam computed tomography (CBCT) scans with different voxel resolutions in the detection of simulated external root resorption (ERR). For that purpose, 59 teeth were viewed through iCAT tomography (Imaging Sciences International, Inc, Hatfield, PA) following three protocols in which the variation was the voxel resolution (0.4, 0.3, and 0.2mm). A calibrated examiner blinded to the protocol assessed the images through the i-CAT View software (Imaging Sciences International, Inc). The chi-square statistical analysis did not show associations between voxel resolution, section plane, size of cavity, and radicular third. Sensitivity and specificity values were similar. However, likelihood ratio values of 6.4 for a 0.4-mm voxel, 16 for a 0.3-mm voxel, and 12 for a 0.2-mm voxel were found. It was concluded that CBCT is a reliable method for the investigation of simulated ERR, and a 0.3-mm voxel appeared to be the best protocol, associating good diagnostic performance with lower X-ray exposure.

Effect of the Combination of Sodium Hypochlorite and Chlorhexidine on Dentinal Permeability and Scanning Electron Microscopy Precipitate Observation

INTRODUCTION This study compared the combined use of sodium hypochlorite (NaOCl) and chlorhexidine (CXH) with citric acid and CXH on dentinal permeability and precipitate formation. METHODS Thirty-four upper anterior teeth were prepared by rotary instrumentation and NaOCl. The root canal surfaces were conditioned for smear layer removal using 15% citric acid solution under ultrasonic activation and a final wash with distilled water. All teeth were dried, and 30 specimens were randomly divided into three equal groups as follows: positive control group (PC), no irrigation; 15% citric acid + 2% CHX group (CA + CHX); and 1% NaOCl + 2% CHX group (NaOCl + CHX). All roots were immersed in a 0.2% Rhodamine B solution for 24 hours. One-millimeter-thick slices from the cementum-enamel junction were scanned at 400 dpi and analyzed using the software ImageLab (LIDO-USP, Sao Paulo, Brazil) for the assessment of leakage in percentage. For scanning electron microscopy analysis, four teeth, irrigated for NaOCl + CHX samples, were split in half, and each third was evaluated at 1,000x and 5,000x (at the precipitate). RESULTS Using the analysis of variance test followed by the Bonferroni comparison method, no statistical differences between groups were found when analyzed at the cervical and medium thirds. At the apical third, differences between the PC and NaOCl + CHX (p < 0.05) and CA + CHX and NaOCl + CHX could be seen (p < 0.05). CONCLUSION The combination of 1% NaOCl and 2% CHX solutions results in the formation of a flocculate precipitate that acts as a chemical smear layer reducing the dentinal permeability in the apical third.

Antibacterial efficacy of intracanal medicaments on bacterial biofilm: a critical review

The purpose of this paper is to discuss critically the antibacterial efficacy of intracanal medicaments on bacterial biofilm. Longitudinal studies were evaluated by a systematic review of English-language articles retrieved from electronic biomedical journal databases (MEDLINE, EMBASE, CENTRAL) and handsearching records, using different matches of keywords for root canal biofilm, between 1966 and August 1st, 2007. The selected articles were identified from titles, abstracts and full-text articles by two independent reviewers, considering the tabulated inclusion and exclusion criteria. Disagreements were resolved by consensus. The search retrieved 91 related articles, of which 8.8% referred to in vivo studies demonstrating the lack of efficacy of endodontic therapy on bacterial biofilm. Intracanal medicaments were found to have a limited action against bacterial biofilm.

Map-reading strategy to diagnose root perforations near metallic intracanal posts by using cone beam computed tomography.

INTRODUCTION To determine the diagnostic hypothesis on the basis of periapical radiography (PR) is a great challenge for radiologists and endodontists. Visualization of three-dimensional structures, available with cone beam computed tomography (CBCT), favors precise definition of the problem and treatment planning. However, metallic artifact effect of intracanal posts might also induce untrue images. The aim of this article is to suggest a map-reading strategy to diagnose root perforations near metallic intracanal posts (ICPs) by using CBCT. METHODS AND RESULTS The incapacity to locate correctly the position of root perforation might lead to clinical failures. One strategy to minimize metallic artifact in root perforation associated with ICP is to obtain sequential axial slices of each root, with an image navigation protocol from coronal to apical (or from apical to coronal), with axial slices of 0.2 mm/0.2 mm. This map reading provides valuable information showing dynamic visualization toward the point of communication between the root canals and the periodontal space, associated with radiolucent areas, suggesting root perforation. CONCLUSIONS The accurate management of CBCT images might reveal abnormality that is unable to be detected in conventional PR. A map-reading approach reduces problems related to detection of root perforations near metallic artifacts. The final diagnosis should always be made in conjunction with the clinical findings.

Evaluation of chlorhexidine substantivity on human dentin: a chemical analysis.

INTRODUCTION The aim of this study was to investigate the substantivity of chlorhexidine (CHX) solution and gel within a root canal system for 24 hours, 30 days, and 90 days. METHODS Forty-five extracted human anterior teeth were used for this study. The samples were divided into 3 groups according to the chemical auxiliary substance used to perform the root canal preparation: group 1, 2% liquid CHX; group 2, 2% gel CHX; and group 3, distilled water (the control group). The working length was determined by inserting a #10 K-file into the canal up to the moment its tip was seen in the apex foramen and then withdrawing it 1 mm. The roots were prepared up to the instrument #45. Longitudinal grooves were carved on the free surfaces of the roots, providing 2 halves of each root and resulting in 30 samples per group. Each group was randomly divided into 3 subgroups (n = 10), and substantivity was evaluated after 24 hours, 30 days, and 90 days of incubation. The amount of CHX (in micrometers) was measured through reverse-phase high-performance liquid chromatography. Statistical analysis was performed by analysis of variance and the Tukey test for post hoc comparisons (α = 0.05). RESULTS The control group showed no substantivity. Significant amounts of CHX solution and gel remained retained in dentin substrates independent of the time of incubation (P < .05). CHX solution showed a higher substantivity than CHX gel, with the exception of groups incubated for 90 days. The decreasing amounts of retained CHX inside the canal were for 24 hours >30 days >90 days for CHX solution and 24 hours >30 days ≥ 90 days for CHX gel. CONCLUSIONS The results of this study indicate that CHX solution and gel are retained in root canal dentin for up to 90 days.

A MODEL SYSTEM TO STUDY ANTIMICROBIAL STRATEGIES IN ENDODONTIC BIOFILMS

The purpose of this work was to develop a model system to study antimicrobial strategies in endodontic biofilms. Enterococcus faecalis suspension was colonized in 10 human root canals. Five milliliters of Brain Heart Infusion (BHI) were mixed with 5 mL of the bacterial inoculums (E. faecalis) and inoculated with sufficient volume to fill the root canal during 60 days. This procedure was repeated every 72 h, always using 24-h pure culture prepared and adjusted to No. 1 MacFarland turbidity standard. Biofilm formation was analyzed by scanning electron microscopy (SEM). E. faecalis consistently adhered to collagen structure, colonized dentin surface, progressed towards the dentinal tubules and formed a biofilm. The proposed biofilm model seems to be viable for studies on antimicrobial strategies, and allows for a satisfactory colonization time of selected bacterial species with virulence and adherence properties.

Evaluation of the antimicrobial effect of super-oxidized water (Sterilox®) and sodium hypochlorite against Enterococcus faecalis in a bovine root canal model

Ideally root canal irrigants should have, amongst other properties, antimicrobial action associated with a lack of toxicity against periapical tissues. Sodium hypochlorite (NaOCl) is a widely used root canal irrigant, however it has been shown to have a cytotoxic effect on vital tissue and therefore it is prudent to investigate alternative irrigants. Steriloxs Aquatine Alpha Electrolyte® belongs to the group of the super-oxidized waters; it consists of a mixture of oxidizing substances, and has been suggested to be used as root canal irrigant. Super-oxidized waters have been shown to provide efficient cleaning of root canal walls, and have been proposed to be used for the disinfection of medical equipment. Objective To compare the antimicrobial action against Enterococcus faecalis of NaOCl, Optident Sterilox Electrolyte Solution® and Steriloxs Aquatine Alpha Electrolyte® when used as irrigating solutions in a bovine root canal model. Methodology Root sections were prepared and inoculated with E. faecalis JH2-2. After 10 days of incubation the root canals were irrigated using one of three solutions (NaOCl, Optident Sterilox Electrolyte Solution® and Steriloxs Aquatine Alpha Electrolyte®) and subsequently sampled by grinding dentin using drills. The debris was placed in BHI broth and dilutions were plated onto fresh agar plates to quantify growth. Results Sodium hypochlorite was the only irrigant to eliminate all bacteria. When the dilutions were made, although NaOCl was still statistically superior, Steriloxs Aquatine Alpha Electrolyte® solution was superior to Optident Sterilox Electrolyte Solution®. Conclusion Under the conditions of this study Steriloxs Aquatine Alpha Electrolyte® appeared to have significantly more antimicrobial action compared to the Optident Sterilox Electrolyte Solution® alone, however NaOCl was the only solution able to consistently eradicate E. faecalis in the model.

The anatomy of the root canal system of three-rooted maxillary premolars analysed using high-resolution computed tomography

AIM To analyse the anatomy of the root canal system of maxillary premolars with three distinct roots using high-resolution computed tomography (μCT). METHODOLOGY Ten three-rooted human maxillary premolars were scanned transversally from crown to apex at 42μm intervals using a high-resolution desktop μTC system (Skyscan 1072). The images were processed and analysed for the following features: cross section of the roots and canals in the apical, middle and coronal thirds; location of the apical foramen; distance from the pulp chamber roof to the bifurcation and trifurcation of the canals and anatomic variations of the root canal system. The results were expressed descriptively. RESULTS The cross-sectional shape of canals was heterogeneous along the length of the roots. The location of the apical foramen varied, tending to lie palatally or distally. The buccal pulp horn was larger than the palatal. The mean distance from the most cervical region of the pulp chamber roof to the bifurcation and trifurcation of the canals was 3.13 and 5.08mm, respectively. CONCLUSIONS Features of the internal anatomy of the pulp cavity of three-rooted maxillary premolars were identified with the use of μCT. The results revealed the heterogeneity of three-rooted maxillary premolars.

Evaluation of the centreing ability of the ProTaper Universal™ rotary system in curved roots in comparison to Nitiflex™ files

The aim of the present study was to assess the centreing ability of the ProTaper Universal rotary system in curved roots in comparison to Nitiflex files, by means of preoperative and postoperative imaging of a cross-section of the apical third. Twenty mesiobuccal canals of human first mandibular molars with a degree of curvature ranging from 35 degrees to 60 degrees were divided into two groups of 10 specimens each: group 1, ProTaper Universal rotary system; group 2 (control), Nitiflex files. All instruments produced morphological alterations. The Students t-test and Kruskal-Wallis test showed that the differences were not statistically significant, except for the specimens instrumented by Nitiflex file #30. The ProTaper Universal showed the capacity for producing centered preparations in curved and thin root canals with low proportions of apical deviation.

Accuracy of Cone-beam Computed Tomography and Periapical Radiography in Apical Periodontitis Diagnosis

INTRODUCTION This study aimed to investigate the correlation and the agreement between periapical radiography (PR) and cone-beam computed tomography (CBCT) correlating to histologic findings in the diagnosis of apical periodontitis (AP). METHODS One hundred thirty-four premolar root canals from 10 dogs were treated after AP induction. Four months later, the animals were killed, and standard digital PRs were obtained. The area of AP was measured by using ImageJ software. CBCT (i-CAT) images from each arch were obtained, and AP area and volume were measured by using Osiri-X software. The apical inflammatory infiltrate was evaluated under light microscopy. The correlation between imaging methods was evaluated by using the Pearson coefficient. The Bland-Altman method was used to assess the agreement between PR and CBCT data. The Spearman coefficient was used to correlate the imaging data and histologic findings. RESULTS Despite a strong correlation between PR and CBCT areas, the agreement limits were very broad (95% limits of agreement, 0.19-1.08). PR only measured, on average, 63% of CBCT values. Although there was a strong correlation between PR area and CBCT volume, the Bland-Altman method suggests that the larger the CBCT volume, the more underestimated the PR value. When APs had a volume smaller than 6 mm(3), the PR estimation of CBCT data was unpredictable. A positive correlation was found for PR area, CBCT area, CBCT volume, and histology data. CONCLUSIONS The diagnosis of AP based on PR data is clinically limited, and it should not be used for scientific investigations.