Influence of different working lengths on the shaping ability of Reciproc Blue in the apical third and apical foramen: a micro-computed tomographic study

Aim: This study aimed to assess the shaping ability of Reciproc Blue in the apical third and apical foramen of moderately curved canals at different working lengths (WLs), by micro-computed tomography. Methods: Thirty-six mesial roots (mesiobuccal and mesiolingual canals) were included, each with 2 separate root canals and independent apical foramina, according to type IV of Vertucci's classification of first and second mandibular molars. The canals were instrumented at three different WLs: G-1, 1mm short of the major apical foramen; G0, at the major apical foramen; G+1, 1mm beyond the major apical foramen. The groups were assessed for changes in root canal volume and untouched wall area in the apical third. Groups G0 and G+1 were also compared for percentage of untouched walls at the apical foramen. One-way ANOVA (post hoc Tukey test) and Student's t-test adopted a 5% level of significance. Results: Root canal volumes (mm3) in the apical third were 22.86±10.46, 44.48±24.91, and 55.71±21.32 in G-1, G0 and G+1, respectively. G-1 volume following instrumentation increased significantly less than that of G0 or G+1 (P>.05); G0 did not differ from G+1. The percentage of untouched wall area in the apical third did not differ among the three groups (P>.05). G0 and G+1 did not differ regarding untouched walls in the major apical foramem walls. Conclusion: Extending the WL from 1mm short of the apical foramen to a point at and beyond the WL increases the apical third volume without increasing the prepared area. Untouched surface areas of the apical foramen were not modified by instrumentation at or beyond the foramen

Development of castor polyurethane scaffold (Ricinus communisL.) and its effect with stem cells for bone repair in an osteoporosis model.

The development of 'smart' scaffolds has achieved notoriety among current prospects for bone repair, especially for chronic osteopathy, such as osteoporosis. Millions of individuals in the world suffer from poor bone healing due to osteoporosis. The objective of this work was to produce and characterize castor polyurethane (PU) scaffolds (Ricinus communisL.)andevaluate itsin vitrobiocompatibility with stem cells and osteoinductive effectin vivoon bone failures in a leporid model of osteoporosis. The material was characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, SEM, and porosity analysis. Then, the biocompatibility was assessed by adhesion using SEM and cytotoxicity in a 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium assay. The osteoinductive effectin vivowas determined in bone defects in rabbit tibias (Oryctolagus cuniculus) submitted to castor PU scaffold, castor PU scaffold associated with stem cells, and negative control, after four and eight weeks, evaluated by computed microtomography and histopathology. The scaffolds were porous, with an average pore size of 209.5 ± 98.2 µm, absence of cytotoxicity, and positive cell adhesivenessin vitro.All the animals presented osteoporosis, characterized by multifocal osteoblastic inactivity and areas of mild fibrosis. There were no statistical differences between these treatments in the fourth week of treatment. In the eighth week, the treatment with castor PU scaffold alone induced more significant bone formation when compared to the other groups, followed by treatment with an association between castor PU scaffold and stem cells. The castor PU scaffold was harmless to cell culture, favoring cell adhesiveness and proliferation, in addition to inducing bone neoformation in osteoporotic rabbits.

The effect of high concentration of zoledronic acid on tooth induced movement and its repercussion on root, periodontal ligament and alveolar bone tissues in rats.

Zoledronic acid (ZA) is often prescribed for osteoporosis or resorptive metabolic bone disease. This study aims to evaluate the effect of ZA on orthodontic tooth movement (OTM) and root and bone resorption and its repercussion on root, periodontal ligament and alveolar bone tissues. The experimental group consisted of 72 Wistar rats divided in four subgroups: Naive, Saline and Zoledronic Acid groups at the concentration of 0.2 mg/kg [ZA (0.2)] or 1.0 mg/kg [ZA (1.0)]. The animals were subjected to i.v (dorsal penile vein) administrations of ZA or saline solution, on days 0, 7, 14 and 42. Under anesthesia, NiTi springs were installed in the first left maxillary molar with 50gf allowing the OTM, except for the negative control group (N) for mesial movement of the left first maxillary teeth. The animals were sacrificed and maxillae were removed for macroscopic and histopathological analyzes, scanning electron microscopy, computerized microtomography and confocal microscopy. Treatment with ZA decreased the OTM and the number of osteoclasts and loss of alveolar bone when compared to the naive and saline groups. Reduction of radicular resorption, increased necrotic areas and reduced vascularization in the periodontal ligament were observed in the ZA groups. ZA interferes with OTM and presents anti-resorptive effects on bone and dental tissues associated with a decreased vascularization, without osteonecrosis.

Microtomographic analysis of the effect of sodium alendronate on orthodontic movement in rats.

OBJECTIVE: To evaluate the effect of sodium alendronate on orthodontic tooth movement in rats using microtomographic analysis. SETTINGS AND SAMPLE POPULATION: Thirty male Wistar rats (Rattus norvegicus) were divided into three groups of 10 rats and administered saline (control), 1 mg/kg sodium alendronate or 6 mg/kg sodium alendronate, respectively. MATERIALS AND METHODS: The drug was administered once per week for 5 weeks by gavage. Orthodontic movement was induced during the last 2 weeks of medication administration by inserting a closed nickel-titanium spring between the left upper first molar and central incisors. The opposite side served as the control. Tooth movement and bone trabeculation in the furcation region were evaluated by microtomographic analysis in the first (moved) and third (static) molars. The data were subjected to one-way or two-way ANOVA and Bonferroni test (P < .05). RESULTS: The microtomographic images of the group that received 6 mg/kg sodium alendronate demonstrated significantly less tooth movement (P = .048), less space between the trabeculae (P = .031) and greater number of bone trabeculae (P = .033) compared to the other groups. There were no statistically significant differences in bone volume and mean trabecular thickness between the three groups. The static teeth did not show the same alterations (P > .05). CONCLUSION: Sodium alendronate treatment reduced tooth movement in rats.

Morphologic Changes of Apical Foramen and Microcrack Formation after Foraminal Enlargement: A Scanning Electron Microscopic and Micro-computed Tomographic Analysis.

INTRODUCTION: The aim of the present study was to evaluate the morphologic changes on the apical foramen and the formation of dentinal microcracks after foraminal enlargement in straight and curved root canals using scanning electron microscopic (SEM) and micro-computed tomographic (micro-CT) analyses. METHODS: Sixty teeth were selected and divided into 2 experimental groups: GI (incisors/straight group, n = 30) and GM (molars/curved group, n = 30). Each group was divided into 2 subgroups (n = 15) according to the analysis performed: SEM or micro-CT analysis. The incisors and mesiobuccal canal of molars were instrumented with Reciproc Blue R25 instruments (VDW, Munich, Germany) using standardized shaping procedures in the apical foramen and 1 mm beyond. The occurrence of foraminal deformation was analyzed by scanning electron microscopy. The z test was used for statistical analysis (P < .05). Micro-CT imaging was used to observe the presence of microcracks in the root apical third. Afterward, pre- and postoperative cross-sectional images were screened to identify the presence of dentinal defects. RESULTS: The curvature of the canal did not influence the occurrence of foraminal deformation either for instrumentation in the foramen or for instrumentation beyond the foramen (P > .05). It was also observed that the increase in the working length did not influence the appearance of new deformations in the GI/SEM and GM-SEM groups (P > .05). Qualitative micro-CT analysis showed the presence of dentinal defects in 0.8% (112) and 1.5% (208) of the cross sections of incisors and molars, respectively, from a total of 13,987 slices. All dentinal defects identified in the analysis of any postoperative scans were already present in the corresponding preoperative images. Therefore, no new microcracks were observed after root canal preparation. CONCLUSIONS: The preparation of straight and moderately curved root canals with Reciproc Blue, regardless of the working length, did not influence the occurrence of apical foramen deformations and did not cause the formation of dentinal microcracks.

Os pricipais efeitos colaterais do clareamento dentário: como amenizá-los / Tooth whitening: main T collateral effects and how to smooth them

Introdução: em busca de uma perfeita harmonia na forma e nas cores dos dentes, a dentística desenvolveu diversas alternativas para a melhoria da estética dentária, sendo que para o tratamento das alterações cromáticas, o procedimento mais utilizado atualmente é o clareamento dental. Objetivo: realizar uma revisão de literatura a cerca dos possíveis efeitos colaterais advindos das técnicas de clareamento dental e como minimizá-los. Material e Métodos: revisão de literatura por meio de busca bibliográfica nas bases de pesquisa online: PubMED, Medline, Lilacs, Scielo e Scopus, através do rastreio de artigos relevantes publicados entre o período de 2010 a 2016. Resultados: dentre os efeitos colaterais apresentados pelo clareamento dental, a sensibilidade durante e após o clareamento tem sido um dos efeitos adversos mais apontados na literatura, fato que pode ser resultado do aumento da permeabilidade do esmalte, com uma possível difusão do peróxido até a polpa, os tratamentos mais eficazes no controle da sensibilidade são: nitrato de potássio a 5%, fluoreto de sódio neutro a 2%, a terapia a laser e o uso de analgésicos e anti-inflamatórios. O gel clareador deve ser removido totalmente ao final do clareamento, porém se alguma quantidade do mesmo é deixada para trás, o paciente pode eventual deglutir, o que pode levar a irritação na mucosa gastrointestinal, dessa forma é importante que seja evitado o excesso de produto e de aplicações, atentando com a remoção cuidadosa dos excessos, para evitar sua ingestão e contato com tecidos moles. Conclusão: independentemente da técnica de clareamento a ser utilizada é necessária a supervisão e acompanhamento de um cirurgião-dentista, pois com o seu criterioso diagnóstico e adequado tratamento é que os resultados satisfatórios serão alcançados e os efeitos colaterais evitados e/ou minimizados. (AU)

Introduction: in order to achieve a perfect harmony in the shape and colors of the teeth, the dentistry has developed several alternatives for the improvement of dental aesthetics, and for the treatment of chromatic alterations, the most commonly used procedure is tooth whitening. Objective: to carry out a literature review about the possible side effects of dental bleaching techniques and how to minimize them. Material and Methods: a review of the literature was carried out through a bibliographic search in the following online databases: PubMED, Medline, Lilacs, Scielo and Scopus, through the screening of relevant articles published between 2010 and 2016. Results: among the side effects of tooth whitening, sensitivity during and after bleaching has been one of the most commonly reported adverse effects in the literature, a fact that may be a result of increased permeability of the enamel, with a possible diffusion of the peroxide to the pulp. The most effective treatments for sensitivity control are: 5% potassium nitrate, 2% neutral sodium fluoride, laser therapy and the use of analgesics and anti-inflammatories. The bleaching gel should be removed completely at the end of bleaching, but if any amount is left behind, the patient may eventually swallow, which may lead to irritation in the gastrointestinal mucosa, so it is important to avoid excess product And applications, with the careful removal of excess, to avoid its ingestion and contact with soft tissues. Conclusion: regardless of the technique of whitening to be used, it is necessary the supervision and follow-up of a dental surgeon, because with his careful diagnosis and appropriate treatment, satisfactory results will be achieved and the side effects avoided and/or minimized. (AU)