Bacteriophages in dentistry : State of the art and perspectives

Bacteriophages, viruses capable of killing bacteria, were discovered in 1915, but the interest in their study has been limited since the advent of antibiotics. Their use in dentistry is still very limited. The authors reviewed studies about bacteriophage structure, mode of action, uses in oral health, and possible future uses in dentistry associated with their possible action over biofilm, as well as the advantages and limitations of phage therapy

Influence of calcium hydroxide points on the quality of intracanal dressing filling

OBJETIVO: O objetivo deste estudo foi avaliar, in vitro, a qualidade do preenchimento de canais radiculares curvos com a pasta de hidróxido de cálcio [Ca(OH)2] Ultracal (Ultradent), associada ou não a cones de guta-percha contendo hidróxido de cálcio (Calcium Hydroxide Plus PointsTM, Roeko). MATERIAL E MÉTODOS: Cento e vinte raízes de dentes humanos extraídos, aleatoriamente distribuídas em 3 faixas de curvatura (leve - 0 a 14º; moderada - 15º a 29º; severa >; 30º) foram utilizadas. Após o preparo químico-mecânico, as raízes foram divididas em 4 grupos (n=30) de acordo com o método de aplicação da medicação intracanal: grupo 1 - aplicação da pasta de Ca(OH)2 com espiral de lentulo; grupo 2 - aplicação da pasta de Ca(OH)2 com espiral de lentulo, seguida da introdução de um cone de Ca(OH)2; grupo 3 - aplicação da pasta de Ca(OH)2 com a ponta NavitipTM (fornecida com o Sistema Ultracal); grupo 4 - aplicação da pasta de Ca(OH)2 com a ponta NavitipTM seguida da introdução de um cone de Ca(OH)2. As raízes foram diafanizadas e avaliadas quanto à qualidade do preenchimento do terço apical dos canais por um examinador calibrado. Os espécimes foram examinados em lupa estereoscópica e classificadas por escores de 1 a 4 (desde preenchimento inadequado até preenchimento total dos canais). Os resultados foram comparados através da análise de variância e teste post hoc de Duncan com nível de significância de 5%. RESULTADOS: Não se observaram diferenças estatisticamente significantes (p>;0.05) entre os graus de curvatura dos grupos 1, 3 e 4 quanto ao preenchimento dos canais. A curvatura severa no grupo 2 apresentou significância limítrofe (p=0,05). Os grupos que associaram pasta e cones de Ca(OH)2 (2 e 4) apresentaram melhor preenchimento apical em relação aos demais grupos, porém essa diferença foi estatisticamente significante (pPURPOSE: The aim of this study was to evaluate, in vitro, the quality of calcium hydroxide [Ca(OH)2] paste filling (Ultracal, Ultradent) associated or not with Ca(OH)2-containing gutta-percha points (Calcium Hydroxide Plus PointsTM, Roeko) in curved root canals. MATERIAL AND METHODS: One hundred and twenty roots of extracted human teeth, randomly divided into three curvature ranges (mild - 0 to 14º; moderate - 15º to 29º; severe - >;30º) were used. After chemomechanical preparation, the roots were assigned to 4 groups (n=30), according to the technique of intracanal dressing placement: group 1 - Ca(OH)2 paste was applied with a lentulo spiral; group 2 - Ca(OH)2 paste was applied with a lentulo spiral and a Ca(OH)2 point was inserted into the canal; group 3 - Ca(OH)2 paste was applied with a NavitipTM tip (supplied with Ultracal system); group 4 - Ca(OH)2 paste was applied with a NavitipTM tip and a Ca(OH)2 point was inserted into the canal. The roots were cleared and the quality of apical third filling was assessed by a calibrated experienced examiner. The specimens were examined under stereomicroscopy and scored 1 to 4 (i.e., from inadequate to complete root canal filling). The results were analyzed statistically by ANOVA and Duncan's post hoc test at 5% significance level. RESULTS: There were no statistically significant differences (p>;0.05) among the curvature degrees in groups 1, 3 and 4. Severely curved roots in group 2 presented bordering significance (p=0.05). The groups that associated the use of Ca(OH)2 paste and points (2 and 4) showed better apical filling than the other groups, but this difference was statistically significant (

Assessment of canal walls after biomechanical preparation of root canals instrumented with protaper universalTM rotary system

OBJECTIVE: The aim of this study was to examine the instrumented walls of root canals prepared with the ProTaper UniversalTM rotary system. MATERIAL AND METHODS: Twenty mesiobuccal canals of human first mandibular molars were divided into 2 groups of 10 specimens each and embedded in a muffle system. The root canals were transversely sectioned 3 mm short of the apex before preparation and remounted in their molds. All root canals were prepared with ProTaper UniversalTM rotary system or with NitiflexTM files. The pre and postoperative images of the apical thirds viewed with a stereoscopic magnifier (X45) were captured digitally for further analysis. Data were analyzed statistically by Fisher's exact test and Chi-square test at 5% significance level. RESULTS: The differences observed between the instrumented and the noninstrumented walls were not statistically significant (

Biocompatibility of different intracanal medications in rat bucal submucosa tissue

The aim of this study was to analyze the buccal tissue responses of Wistar rats to 2% chlorhexidine solution, calcium hydroxide and the association of both products. For this purpose, 30 specimens were randomly implanted in the filtrum of the four upper and lower hemiarches with a polyethylene tube containing one of the following substances: 2% chlorhexidine solution, calcium hydroxide and 2% chlorhexidine solution (test groups); calcium hydroxide and distilled water and distilled water (control groups). Ten rats each were distributed according to time interval of evaluation at 7, 15 and 30 days. The histological sections were stained with Harris hematoxylin and eosin. Analysis was performed with an optical microscope at x100, x200 and x400 magnifications by an expert examiner blinded to the materials. The sections were classified by scores attributed to inflammatory events and by a ranking determined according to the severity of the inflammation. The results of the inflammatory events and severity ranking were submitted to the Kruskal-Wallis test at a 0.05 level of significance. No statistically significant difference occurred among the tested materials; however, all materials showed a decreased of severity with respect to longer time intervals

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

Biological tissue response to a new formulation of a silicone based endodontic sealer

Satisfactory biological behavior is a necessary requirement for clinical application of endodontic materials. In this study, the connective tissue responses to silicone (GuttaFlow 2), epoxy resin (AH Plus) and zinc oxide and eugenol (Endofill) based sealers were compared. Twelve Wistar rats had polyethylene tubes (four per animal) containing one of the tested sealers and empty tubes (negative control) implanted in their subcutaneous tissue. The tubes were randomly placed 2 cm from the spine and at least 2 cm apart from one another. Tissue samples with implants were processed for histological analysis after 7 or 60 days (n=6 animals per period). Inflammatory cells, fibrous condensation and abscess were scored according to their intensity. Friedman, followed by Dunn’s post hoc, was used to compare sealers. Differences between the two experimental periods were verified using Mann-Witney U test (p<0.05). At 7 days, most of the histological parameters showed no significant differences amongst groups. Endofill group scored higher than the others for giant cells (o<0.05) and promoted a greater number of samples presenting abscess formation. GuttaFlow 2 tended to show a less intense inflammatory infiltrate compared to the other materials. At 60 days, there were no significant differences between groups in most of the histological parameters evaluated. However, it was observed that Endofill scored higher for macrophages (p<0.05) compared to the control group, and GuttaFlow 2 tended to present lower scores than the others for neutrophils and abscess. GuttaFlow 2 showed proper biological behavior and should be considered adequate for clinical practice

Pulp capping with mineral trioxide aggregate or Biodentine : a comparison of mineralized barrier formation and inflammatory and degenerative events

Biodentine in endodontic practice has been widely investigated, but comprehensive histological descriptions of degenerative and inflammatory responses are not covered in most of the studies that compare pulp capping materials. This study aimed to evaluate pulpal responses to mineral trioxide aggregate (MTA Angelus) and Biodentine, focusing on mineralized barrier formation and on inflammatory and degenerative events. 80 male Wistar rats were assigned to 5 groups, according to the materials used for pulp capping and coronal sealing (n=8 per group/period). The lower first molars were mechanically exposed, capped with either MTA or Biodentine, and restored with silver amalgam. In an additional test group, the teeth were capped and sealed with Biodentine. The teeth capped with gutta-percha and restored with silver amalgam served as positive control, whereas untreated teeth served as negative control. Pulpal responses and coronal sealing were evaluated after 14 or 21 days. Data was statistically analyzed by the Kruskal-Wallis and Dunn's post hoc tests (p<0.05). Biodentine and MTA presented satisfactory results, showing a milder inflammatory response (p<0.0001) and more pronounced formation of mineralized barrier (p<0.0001) compared to the teeth capped with gutta-percha. As a restorative material, Biodentine kept coronal sealing in only 37.5% of the samples. Biodentine showed favorable properties in vital pulp therapy, being similar to MTA. However, it was not effective in protecting dental pulp from microleakage during the experimental period

N-acetylcysteine (NAC) Protects Against Acute Kidney Injury (AKI) Following Prolonged Pneumoperitoneum in the Rat

Background. Acute kidney injury (AKI) following prolonged laparoscopy is a documented phenomenon. Carbon dioxide pneumoperitoneum induces oxidative stress. Previous experimental studies have shown that the antioxidant, N-acetylcysteine, protects the rat from AKI following ischemia-reperfusion. The aim of this study was to evaluate the effects of N-acetylcysteine (NAC) on rat renal function after prolonged pneumoperitoneum. Methods. Normal rats treated or not with NAC were submitted to abdominal CO2 insufflation of 10 mmHg, at short and long periods of time of 1 and 3 h, respectively, and evaluated at 24, 72 h, and 1 wk after deinsufflation. Glomerular filtration rate (GFR) was measured by inulin clearance and oxidative stress was evaluated by serum thiobarbituric acid reactive substances (TBARS) Results. No significant alterations in GFR were observed in normal animals submitted to the pneumoperitoneum of 1 h and evaluated after 24 h desufflation. With 3 h of pneumoperitoneum, a significant and progressive decrease in GFR occurred 24 and 72 h after desufflation with an increase in serum TBARS. GFR returned to normal levels a week later. In the NAC-treated rats, a complete protection against GFR drops was observed 24 and 72 h following 3 h of pneumoperitoneum associated with a decrease in TBARS. Conclusion. These results suggest that NAC protects against acute kidney injury following prolonged pneumoperitoneum. These findings have significant clinical implications. (C) 2012 Elsevier Inc. All rights reserved

Análise comparativa da formação do "zip" apical em canais curvos e atresiados produzido "in vitro" por duas técnicas de instrumentação

O objetivo do presente estudo foi avaliar a formação do "zip" apical em canais curvos e atresiados produzido por duas técnicas de instrumentação. Para tanto, 50 canais simulados em resina "epoxi" foram confeccionados a uma curvatura de 40° e divididos em dois grupos de 25 canais cada um. O primeiro grupo foi preparado pela Técnica Convencional e o segundo pela Técnica Escalonada. Depois de feitos os reparos, os canais foram avaliados por dois observadores. Diante dos resultados obtidos, chegou-se às seguintes conclusões: a) a Técnica Convencional produziu zip apical em maior número do que a Técnica Escalonada; b) a Técnica Escalonada proporcionou maior segurança no preparo, tendo obtido, na maioria dos casos, uma forma cônica afunilada contínua, com o desgaste sendo menor no ápice e maior no orifício de entrada do canal

Decision-making for dental pulp exposure : a survey in graduate programs at Brazilian universities

Clinical decision-making tends to be based on what clinicians have been taught during undergraduate and graduate programs. The aim of the present study was to assess the clinical approach and to identify the factors that influence the decision-making for dental pulp exposure among graduate students and coordinating professors in endodontics programs offered at Brazilian universities. The study used a mail-out survey developed in the Qualtrics platform, based on seven clinical reports in which dental pulp exposure was evidenced. Descriptive statistics showing vital pulp therapy (VPT) and root canal treatment (RCT) were calculated for each clinical report. Data on the participants’ (n = 113) profile and variables related to clinical and radiographic characteristics of the cases were evaluated as to their potential to affect decision-making and analyzed by logistic regression (p < 0.05). VPT was likely to be indicated in cases of patients with immature teeth (OR = 0.017; 95%CI = 0.004 -0.073). RCT indications were related to the presence of symptoms (OR = 5.326; 95%CI = 1.429–19.852) and old age (OR = 21.057; 95%CI=6.809–65.120). In pulp exposure secondary to trauma, time of pulp exposure was significantly associated with RCT indication (OR=3.267; 95%CI=1.332–8.012). The present study demonstrated that patient age, root development, and symptom features were the main factors affecting participants’ decision-making