Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances

The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG),Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract fromCasearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide paste promoted the highest inflammatory response

Microscopic evaluation of the tissue reaction in subcutaneous of rats to Portland cements containing different arsenic concentrations

O MTA (Agregado Trióxido Mineral) tem sido utilizado na endodontia com diferentes finalidades terapêuticas. Essencialmente ele é constituído pelo cimento Portland acrescido de um radiopacificador. Entre seus componentes, é destacada a presença do arsênico, o qual sofre variação de concentração em função da origem do calcário. A dúvida é que se diferentes concentrações de arsênico representam alguma influência na sua biocompatibilidade. O objetivo deste estudo foi avaliar, microscopicamente, a reação tecidual em subcutâneo de ratos frente a cimentos Portland contendo diferentes concentrações de arsênico. Foram utilizados 36 ratos Wistar albinos, distribuídos em 4 grupos experimentais segundo o material empregado perfazendo um total de 6 implantes por período (15, 30 e 60 dias). A lateral dos tubos serviram como grupo controle. Após 15, 30 e 60 dias, os animais foram mortos e os espécimes foram preparados histotecnicamente para análise microscópica. Os dados da avaliação morfométrica foram submetidos à análise de variância a dois critérios (ANOVA) e teste de Tukey para a comparação (p<0,05). Os resultados mostraram uma maior densidade de volume de células inflamatórias aos 15 dias, com redução dessa densidade com o passar do tempo para todos os materiais. Os resultados da análise descritiva mostraram inflamação crônica induzida pelos materiais, com intensidade de leve a moderada, e organização de uma cápsula fibrosa ao redor de todos os espécimes e em todos os períodos. Os cimentos analisados produziram respostas inflamatórias semelhantes, mesmo apresentando quantidades diferentes de arsênico na composição, apenas com diferença estatisticamente significante entre o cimento Portland cinza Votoran e os demais cimentos nos três períodos estudados.The MTA (Mineral Trioxide Aggregate) has been used in Endodontics for different therapeutic purposes. Essentially, it is composed of Portland cement with addition of a radiopacifier. Its components include arsenic, whose concentration is variable according to the origin of the calcareous. There is doubt whether different arsenic concentrations might influence its biocompatibility. This microscopic study evaluated the reaction of subcutaneous tissue of rats to Portland cements containing different arsenic concentrations. The study was conducted on 36 albinus Wistar rats, divided in 12 animals for each study group. Each animal received two implants of polyethylene tubes, completely filled with the test cements, and the lateral aspect of the tubes was taken as control group. The animals were killed after 15, 30 and 60 days and the specimens were submitted to histotechnical preparation for microscopic analysis. Data of the morphometric analysis were submitted to two-way analysis of variance (ANOVA) and the Tukey test for comparison (p<0.05). The results evidenced greater density of volume of inflammatory cells at 15 days, which was reduced with time for all materials. The results of this descriptive analysis demonstrated chronic inflammation induced by the materials, of mild to moderate intensity, and organization of a fibrous capsule around all specimens and in all periods. The cements induced similar tissue responses, despite the different arsenic concentrations in their composition

Prevalence and morphometric analysis of three-rooted mandibular first molars in a Brazilian subpopulation

The knowledge of the internal anatomy of three-rooted mandibular molars may help clinicians to diagnose and plan the root canal treatment in order to provide adequate therapy when this variation is present. Objectives: To determine the prevalence of three-rooted mandibular molars in a Brazilian population using cone beam computed tomography (CBCT) and to analyze the anatomy of mandibular first molars with three roots through micro-CT. Material and Methods: CBCT images of 116 patients were reviewed to determine the prevalence of three-rooted first mandibular molars in a Brazilian subpopulation. Furthermore, with the use of micro-CT, 55 extracted three-rooted mandibular first molars were scanned and reconstructed to assess root length, distance between canal orifices, apical diameter, Vertucci's classification, presence of apical delta, number of foramina and furcations, lateral and accessory canals. The distance between the orifice on the pulp chamber floor and the beginning of the curvature and the angle of canal curvature were analyzed in the distolingual root. Data were compared using the Kruskal-Wallis test (α=0.05). Results: The prevalence of three-rooted mandibular first molars was of 2.58%. Mesial roots showed complex distribution of the root canal system in comparison to the distal roots. The median of major diameters of mesiobuccal, mesiolingual and single mesial canals were: 0.34, 0.41 and 0.60 mm, respectively. The higher values of major diameters were found in the distobuccal canals (0.56 mm) and the lower diameters in the distolingual canals (0.29 mm). The lowest orifice distance was found between the mesial canals (MB-ML) and the highest distance between the distal root canals (DB-DL). Almost all distal roots had one root canal and one apical foramen with few accessory canals. Conclusions: Distolingual root generally has short length, severe curvature and a single root canal with low apical diameter

Effect of ultrasound streaming on the disinfection of flattened root canals prepared by rotary and reciprocating systems

New technical and scientific developments have been advocated to promote the success of the endodontic treatment. In addition to rotary and reciprocating systems, irrigating solution agitation has been suggested and passive ultrasonic irrigation (PUI) is the most used. Objective: To evaluate, in vitro, the effect of ultrasound streaming (US) in the disinfection of flattened root canal systems prepared by the ProTaper, BioRaCe and Reciproc systems, utilizing the microbiological culture. Methodology: Extracted human mandibular incisors (n=84) were used. Suspensions of Enterococcus faecalis (ATCC 29212) were standardized and inserted along with the teeth immersed in brain-heart infusion (BHI) broth. The contamination was made following a protocol during 5 days. The teeth were randomly divided into six groups: G1, ProTaper Universal; G2, ProTaper Universal with US; G3, BioRaCe; G4, BioRaCe with US; G5, Reciproc; and G6, Reciproc with US. Irrigation was performed with saline solution. After biomechanical preparation, microbiological samples were performed with sterilized paper points, which were diluted and spread on BHI agar; after 48 h, the colony forming units (CFU/mL) were counted for each sample. Results: Groups using ultrasonic agitation presented a greater antibacterial effect than the other ones, even using saline solution as irrigant. The ProTaper Universal system showed the best antibacterial activity of the tested systems (median of 0 CFU/mL with and without surfactant or ultrasonic activation [PUI]). Even with PUI, Reciproc (median of 2.5 CFU/mL with PUI and 5 without it) could not reduce as many colonies as ProTaper Universal without US. The BioRaCe system had greater bacterial reduction when using US (median of 0 CFU/mL with PUI and 30 without it). Conclusions: US promoted greater reduction in the number of bacteria in the flattened root canals prepared with nickel-titanium mechanized systems. Regarding the instruments used, the ProTaper Universal system was the most effective in reducing the bacterial number

Antimicrobial activity of triantibiotic paste, 2% chlorhexidine gel, and calcium hydroxide on an intraoral-infected dentin biofilm model

Introduction: The purpose of this study was to evaluate the antimicrobial activity of calcium hydroxide, 2% chlorhexidine gel, and triantibiotic paste (ie, metronidazole, minocycline, and ciprofloxacin) by using an intraorally infected dentin biofilm model. Methods: Forty bovine dentin specimens were infected intraorally using a removable orthodontic device in order to induce the biofilm colonization of the dentin. Then, the samples were treated with the medications for 7 days. Saline solution was used as the control. Two evaluations were performed: immediately after the elimination of the medication and after incubation in brain-heart infusion medium for 24 hours. The Live/Dead technique (Invitrogen, Eugene, OR) and a confocal microscope were used to obtain the percentage of live cells. Nonparametric statistical tests were performed to show differences in the percentage of live cells among the groups (P < .05). Results: Calcium hydroxide and 2% chlorhexidine gel did not show statistical differences in the immediate evaluation. However, after application of the brain-heart infusion medium for 24 hours, 2% gel chlorhexidine showed a statistically lesser percentage of live cells in comparison with calcium hydroxide. The triantibiotic paste significantly showed a lower percentage of live cells in comparison with the 2% chlorhexidine gel and calcium hydroxide groups in the immediate and secondary (after 24 hours) evaluations. Conclusions: The triantibiotic paste was most effective at killing the bacteria in the biofilms on the intraorally infected dentin model in comparison with 2% chlorhexidine gel and calcium hydroxideFAPESP #2010/16002-