Manoel Brito-Júnior

Effectiveness of Chemomechanical Preparation with Alternating Use of Sodium Hypochlorite and EDTA in Eliminating Intracanal Enterococcus faecalis Biofilm

INTRODUCTION The elimination of microorganisms from root canals is a critical step in endodontic treatment. We aimed to evaluate the antimicrobial effectiveness of an alternating irrigation regimen during chemomechanical preparation (CMP). METHODS During 21 days, root canals of extracted human teeth were infected with Enterococcus faecalis, and colonization was confirmed by scanning electron microscopy (SEM). Canals were irrigated with saline solution (control group), with 5.25% NaOCl followed by a final rinse with 17% EDTA (conventional irrigation group), or with the alternating use of NaOCl and EDTA (alternating irrigation [AI] group). Samples were taken before treatment (S1), after CMP (S2), and during the following 14 days. Two specimens/group were analyzed by SEM. RESULTS The AI group yielded negative agar and liquid cultures from immediately after CMP and from the 5th day on, respectively. SEM confirmed several bacterium-free sites in the AI group. CONCLUSION The irrigation regimen based on the alternating use of NaOCl and EDTA seems to be a promising endodontic tool because it promoted the elimination of root canal E. faecalis biofilms throughout the experimental period.

INFLUENCE OF LUTING AGENTS ON TIME REQUIRED FOR CAST POST REMOVAL BY ULTRASOUND: AN IN VITRO STUDY

Objective: This in vitro study evaluated the influence of luting agents on ultrasonic vibration time for intraradicular cast post removal. Material and Methods: After endodontic treatment, 30 roots of extracted human canines were embedded in resin cylinders. The post-holes were prepared at 10 mm depth and their impressions were taken using autopolymerizing acrylic resin. After casting procedures using a nickel-chromium alloy, the posts were randomly distributed into 3 groups (n=10) according to the luting material: G1- zinc phosphate (SS White) (control group), G2 - glass ionomer cement (Vidrion C; SS White), and G3- resin cement (C&B; Bisco). In G3, the adhesive procedure was performed before post cementation. After 24 h, the cement line was removed at the post/tooth interface using a fine diamond bur, and the ST-09 tip of an Enac ultrasound unit was applied at maximum power on all surfaces surrounding the posts. The application time was recorded with a chronometer until the post was completely dislodged and data were analyzed by ANOVA and Tukeys test (p<0.05). Results: The roots were removed from the acrylic resin and inspected to detect cracks and/or fractures. The means for G1, G2, and G3 were 168.5, 59.5, and 285 s, respectively, with statistically significant differences among them. Two G3 posts resisted removal, one of which developed a vertical fracture line. Conclusions: Therefore, the cement type had a direct influence on the time required for ultrasonic post removal. Compared to the zinc phosphate and glass ionomer cements, the resin cement required a longer ultrasonic vibration time.

Nonsurgical endodontic management using MTA for perforative defect of internal root resorption: report of a long term follow-up

Internal root resorption is an uncommon lesion following a dental injury. The use of mineral trioxide aggregate (MTA) is a conservative approach to repair lesions with periodontal communication. This case report presents a long-term follow-up of a nonsurgical endodontic management using MTA for perforative defect of internal root resorption. During the endodontic treatment, the granulation tissue was removed and the root canal prepared. Calcium hydroxide was placed as a temporary dressing for 30 days. After this period, the root canal space and the perforation defect were filled with MTA. The clinical findings and periapical radiographs indicated success of treatment until 2 years of follow-up. However, the radiograph after 8 years showed an extensive radiolucent area in the middle third of the root with separation of the apical and coronal root segments. These findings were observed more accurately by using cone-beam computerized tomography.

Detection and quantification of mast cell, vascular endothelial growth factor, and microvessel density in human inflammatory periapical cysts and granulomas

AIM To identify and quantify mast cell (MC), vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) in human periapical cysts and granulomas. METHODOLOGY Archived samples of cysts (n = 40) and granulomas (n = 28) were sectioned and stained with toluidine blue. MCs were identified and counted. Immunohistochemical reactions were employed to evaluate the tissue expression of VEGF and vessels. MVD was estimated by determining the areas of tissue labelled with CD31 antibody. The data were analysed using the Mann-Whitney test (P < 0.05). RESULTS MCs were observed in the peripheral regions of both lesion types, whilst VEGF and MVD were distributed in the stroma. The presence of MCs was higher in cysts than in granulomas (P < 0.05). VEGF and MVD expression were similar in these lesions. CONCLUSIONS The highest number of MCs was observed in cysts. Moreover, the identification of VEGF and MVD was consistent with the immune mechanisms involved in the lesions.

Comparison of the time required for removal of intraradicular cast posts using two Brazilian ultrasound devices

The aim of this in vitro study was to compare the time required for removal of intraradicular cast posts cemented with zinc phosphate (ZF) or glass ionomer cement (GIC), using two Brazilian ultrasound devices (BUD). Seventy two human inferior premolars with single root canals were sectioned transversally at the cementoenamel junction. In each specimen, the root canal was endodontically treated, the post space was prepared to a depth of 9 mm and the canal was molded to obtain a post impression. After the casting procedures, the posts were randomly distributed into 2 groups (n = 36) according to the luting material used: G1 - ZF and G2 - GIC. The tooth and luted post set was then embedded in an acrylic resin block. The groups were then divided into 3 subgroups (n = 12) according to the ultrasound device used: A - Enac (Osada Electric, Japan), used as a control group; B - Profi II Ceramic (Dabi Atlante, Brazil) and C - Jet Sonic Satelec (Gnatus, Brazil). The posts were submitted to the vibration process with maximum power set on all surrounding surfaces. Time of application was recorded with a chronometer until complete post dislodgment, and the data were analyzed by the ANOVA test (p < 0.05). The averages required for post removal in G1 and G2 were respectively 41.42 and 92.03 seconds, with significant statistical difference (p = 0.001). No statistical difference was observed among the three ultrasound devices (p = 0.088), and the BUD presented a performance similar to that of the international gold standard device (Enac). Moreover, the type of luting agent had a greater influence on the time required for post removal than the origin of the ultrasonic unit.

Fracture resistance and stress distribution of simulated immature teeth after apexification with mineral trioxide aggregate.

AIM To evaluate the effect of adhesive restorations on fracture resistance and stress distribution in teeth with simulated immature apices and apical plugs of mineral trioxide aggregate (MTA). METHODOLOGY Sixty bovine incisors were sectioned 8 mm above and 12 mm below the cemento-enamel junction (CEJ). The root canal was enlarged using a diamond bur, resulting in remaining root canal walls with 0.1-0.2 mm of thickness. A 5-mm apical plug of MTA was placed and the teeth were restored according to the following groups: GP--the root canal was filled with gutta-percha and endodontic sealer; CR--the root canal was filled with light-cured composite resin inserted incrementally; FP--a fibre post was cemented into the root canal; and RFP--the fibre post was relined with composite resin prior to the cementation into the root canal. A load was applied on the crown of all teeth at 135° to their long axis until fracture. Data was analysed by one-way anova and SNK tests (α = 0.05), whilst the fracture pattern was evaluated according to the position of the fracture. Stress distributions in the restored teeth were verified by finite element analysis. RESULTS Teeth restored with fibre posts and relined fibre posts were associated with the highest fracture resistance, whilst the GP group had the lowest values. GP and RC groups had similar fracture resistance values (P = 0.109). All fractures types involved the cervical and middle thirds of roots. The GP model had high levels of stress concentration in the cervical and middle thirds of roots. No difference was found amongst the stress concentration in the RC, FP and RFP models. CONCLUSION Restorative protocols alter the fracture resistance and stress distribution of immature teeth after placement of MTA apical plugs.

Radiographic quality of root canal fillings performed in a postgraduate program in endodontics

The aim of this study was to evaluate the standard quality of 1,347 root fillings performed by postgraduate students in Endodontics according to 3 radiographic quality parameters. The analyzed quality parameters included apical extension (AE), taper (TA) and homogeneity (HO), which received scores S2 (ideal standard), S1 (slight deviation) or S0 (accentuated deviation). A perfect filling (PF) received S2 for all parameters. In the absence of one or two S2 score, the fillings were deemed as satisfactory (SF) or deficient (DF), respectively. The results showed 51.7%, 41.5% and 6.8% of PF, SF, and DF, respectively. AE, TA, and HO presented equivalent quality parameters in root-filled canals of mandibular incisors and mandibular premolars (p>0.05). Conversely, in maxillary incisors, canines and distal root of mandibular molars, significant differences (p<0.05) were found between 2 parameters. Besides, there were significant differences (p<0.05) among the measured parameters in root-filled canals of maxillary premolars, all root canals of the maxillary molars and mesial root of the mandibular molars. AE showed the lowest frequency of S2 score for all groups. In conclusion the prevalence of perfect, satisfactory and deficient fillings varied significantly according to the root canal group. The quality parameters categorized fillings in 3 complexity degrees. AE was the most critical parameter of quality in root canal fillings.

Bioinformatics, Interaction Network Analysis, and Neural Networks to Characterize Gene Expression of Radicular Cyst and Periapical Granuloma

INTRODUCTION Bioinformatics has emerged as an important tool to analyze the large amount of data generated by research in different diseases. In this study, gene expression for radicular cysts (RCs) and periapical granulomas (PGs) was characterized based on a leader gene approach. METHODS A validated bioinformatics algorithm was applied to identify leader genes for RCs and PGs. Genes related to RCs and PGs were first identified in PubMed, GenBank, GeneAtlas, and GeneCards databases. The Web-available STRING software (The European Molecular Biology Laboratory [EMBL], Heidelberg, Baden-Württemberg, Germany) was used in order to build the interaction map among the identified genes by a significance score named weighted number of links. Based on the weighted number of links, genes were clustered using k-means. The genes in the highest cluster were considered leader genes. Multilayer perceptron neural network analysis was used as a complementary supplement for gene classification. RESULTS For RCs, the suggested leader genes were TP53 and EP300, whereas PGs were associated with IL2RG, CCL2, CCL4, CCL5, CCR1, CCR3, and CCR5 genes. CONCLUSIONS Our data revealed different gene expression for RCs and PGs, suggesting that not only the inflammatory nature but also other biological processes might differentiate RCs and PGs.

Comparison of different ultrasonic vibration modes for post removal

This in vitro study compared different ultrasonic vibration modes for intraradicular cast post removal. The crowns of 24 maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the canals were treated endodontically. The post holes were prepared and root canal impressions were taken with self-cured resin acrylic. After casting, the posts were cemented with zinc phosphate cement. The samples were randomly distributed into 3 groups (n=8): G1: no ultrasonic vibration (control); G2: tip of the ultrasonic device positioned perpendicularly to core surface and close to the incisal edge; and G3: tip of the ultrasonic device positioned perpendicularly to core surface at cervical region, close to the line of cementation. An Enac OE-5 ultrasound unit with an ST-09 tip was used. All samples were submitted to the tensile test using an universal testing machine at a crosshead speed of 1 mm/min. Data were subjected to one-way ANOVA and Tukeys post-hoc tests (α=0.05). Mean values of the load to dislodge the posts (MPa) were: G1 = 4.6 (± 1.4) A; G2 = 2.8 (± 0.9) B, and G3= 0.9 (± 0.3) C. Therefore, the ultrasonic vibration applied with the tip of device close to the cores cervical area showed higher ability to reduce the retention of cast post to root canal.

A Novel Dentin Push-out Bond Strength Model That Uses Micro-Computed Tomography.

INTRODUCTION Current push-out experimental methods used in endodontic research should be improved. This study introduced a novel dentin push-out bond strength model that uses micro-computed tomography (μCT). METHODS Roots filled with gutta-percha cones and different resin-based sealers (n = 10) were sectioned transversely to obtain two 2-mm-thick slices per root third. The first slice was subjected to a push-out test by using a material testing stage fitted inside a μCT scanner. The apparatus was scanned before and after the test to evaluate areas of filling material ruptures. The images provided by μCT were also used to generate models for a 3-dimensional finite element analysis. Confocal laser scanning microscopy was used to assess failure modes after the test and to measure interfacial gaps in slices not subjected to push-out. Bond-strength and gap data were statistically analyzed (P < .05). RESULTS Proper coefficients of variation (average less than 30%) were observed for all the experimental conditions. The finite element analysis helped explain the results of bond strength and root-filling ruptures. A significant, moderate, indirect correlation was observed between the bond strength and gaps. CONCLUSIONS The micromechanical model with the μCT images resulted in a consistent root-filling bond strength evaluation.