Finite element analysis of weakened roots restored with composite resin and posts.

Finite element analysis (FEA) was used to investigate the influence of different post systems on the stress distribution of weakened teeth under oblique-load application. A maxillary central incisor root obtained from a sound tooth was weakened by partial removal of dentin inside the root canal. Seven two-dimensional numerical models, one from the sound tooth and six from the weakened root restored with composite resin and post systems were created as follows - ST: sound tooth; CPC: cast CuAl post and core; SSP: stainless steel post + composite core; GP: fiberglass + composite core; CP: carbon fiber + composite core; ZP: zirconium dioxide post + composite core; TP: titanium post + composite core. The numerical models were considered to be restored with a leucite-reinforced all-ceramic crown and received a 45 masculine occlusal load (10 N) on the lingual surface.All the materials and structures were considered linear elastic, homogeneous, and isotropic, with the exception of fiberglass and carbon fiber posts which assumed orthotropic behavior. The numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using von Mises and Sy stress criteria. When compared with the sound tooth, FEA revealed differences in stress distribution when post systems were used. Among the restored teeth, the use of CPC, SSP, ZP, and TP resulted in higher stress concentration in the post itself when compared to GP and CP. Therefore, results from the FEA images suggested that the use of non-metallic post systems could result in improved mechanical behavior for the weakened restored teeth.

A model of the early mineralization process of mantle dentin.

The aim of this study was to investigate the relationship between proteoglycans (PGs) and collagen fibrils at the early mineralization process of mantle dentin. Ten first molar dental germs of rats were removed and fixed in glutaraldehyde/formaldehyde in cacodylate buffer and post-fixed in osmium tetroxide. The samples were dehydrated and embedded in epoxy resin. Ultrathin sections were contrasted and analyzed in TEM before and after treatment with EDTA, chondroitinases AC and ABC. After EDTA treatment, a electrondense substance associated with collagen fibril was removed, and did not stain again. A high magnification of these areas showed globular structures with 15 nm diameter surrounding collagen fibrils. In advanced mineralization areas, collagen fibrils showed a banded pattern and at high magnification the fibrils presented a light 10 nm ring inside and a dark 10 nm ring outside. After chondroitinase treatment, the electrondense substance associated with collagen fibrils was removed, showing a banded pattern of clear and dark areas along them. From morphological data, the authors proposed a model of interaction between PGs and collagen fibrils, where glicosaminoglycans chains are inside the fibrils, while the protein core remains outside. That stereochemical arrangement would start the crystal nucleation.

Permeability of remaining endodontic obturation after post preparation.

This study assessed the correlation between leakage from the cervix to the apex and from the apex to the cervix for different post preparation techniques. Sixty roots were obturated with gutta-percha lateral condensation and AH Plus sealer and divided into two groups of 30 roots each. Immediate post preparation was used for one group and delayed preparation was used for the other. Two subgroups of 15 roots each were formed to investigate leakage from cervix-to-apex and from apex-to-cervix. The extent of leakage was determined using a dye, India ink, and a clearing technique that rendered the teeth transparent. Linear measurement of the dye penetration was recorded and examined with a stereomicroscope. Eight teeth were used as positive and negative controls. Leakage was observed in all samples. No statistically significant differences were found between the immediate and delayed post preparation techniques regarding apex-to-cervix leakage; however, the values of cervix-to-apex leakage were significantly lower for the immediate technique than for the delayed technique.

Morphometric evaluation and planning of anticurvature filing in roots of maxillary and mandibular molars.

This study aimed to guide the planning of anticurvature filing using pre-determined anatomical points on teeth to establish directions for proper implementation of the technique. Two hundred digital periapical radiographs of human molar teeth were selected and divided into two groups (n = 100): MX (maxillary) and MD (mandibular) molars. Mesiobuccal roots were considered for the MX group and mesial roots for the MD group. Pre-determined anatomical points required for planning the anticurvature filing on the root canal path were located, and the distances between these points obtained. The anticurvature filing was simulated in two different protocols for each group, and the region of dentin removal and the remaining dentin thickness were measured in the safety and danger zones of the root canals. Statistical analysis was carried out at a significance level of 5%. The distances between the anatomical points and the thickness of remaining dentin showed significant differences when the two groups were compared (p < 0.001). No significant differences were found between the two experimental groups regarding the area of dentin removal at the root region, but differences were detected in comparison with dentin removal at the crown (p < 0.001). In terms of wear produced after simulation of both anticurvature filing protocols, significant differences were verified for all regions, except for the dentin remaining at the danger zone. The radiographic location of anatomical points allows for planning and implementation of controlled and efficient anticurvature filing and can be performed in the same manner for maxillary and mandibular molars.

Influence of flexion angle of files on the decentralization of oval canals during instrumentation.

The aim of this study was to evaluate the influence of the flexion angle of files on the decentralization of root canals during instrumentation. Fifteen lower incisors were instrumented with Protaper Universal files and radiographed in two directions (mesiodistal and buccolingual) before and after instrumentation with a #15 K-file in position for evaluating the flexion angle of files. The specimens were also scanned before and after instrumentation using micro-computed tomography to obtain the canal area and the distance from the center position of the file to the canal walls. Sections located 1.0 mm (end of the canal), 3.0 mm (apical third), 9.0 mm (middle third), and 15.0 mm (cervical third) from the apex were verified. After instrumentation, the flexion angles of files decreased by an average of 0.76º in the buccolingual direction and 1.92º in the mesiodistal direction (p < 0.001); the canal area increased by an average of 0.58, 0.37, 0.23 and 0.13 mm(2) from the cervical to the end of the root canal (p < 0.001). Non-instrumented areas were observed on the buccal and lingual walls, and effective action of files was determined on the mesial and distal walls. The sections from the end of the canal showed canal deviation toward the lingual wall, whereas the other sections showed deviation toward the buccal wall. The flexion angles of files influence the final shape of the root canal, resulting in file decentralization along the pathway of the canal.

Evaluation of intracanal post removal using ultrasound.

The aim of this study was to determine the effect of ultrasonic vibration on the force necessary to remove pre-fabricated and anatomic and cast posts. Two hundred and forty teeth were divided into two groups. In group I, a 0.8-mm metallic pre-fabricated post, Unimetric-Maillefer, was utilized; in group II, cast copper-aluminum alloy posts measuring 0.8, 1.0 and 1.2 mm in diameter were used. The root canals were prepared in three different diameters: 0.8, 1.0 and 1.2 mm, with a length of 10 mm. The posts were cemented with glass ionomer cement resulting in 20 specimens for each subgroup. Half of the sample was submitted to ultrasonic vibration for 3 min, while the other half did not receive any vibration. The specimens were submitted to traction in a universal testing machine. The results were analyzed by non-parametric Mann-Whitney U, Wilcoxon and Kruskal-Wallis tests. The application of ultrasonic vibration significantly reduced the retention provided by the glass ionomer cement in the fixation of intracanal posts. The ultrasonic action was effective in both pre-fabricated and anatomic and cast posts. The effectiveness of the ultrasonic vibration was not related to the cementation line or the diameter of the post.

Critical instrumentation area: influence of root canal anatomy on the endodontic preparation.

The aim of this study was to evaluate the root canal anatomy of mandibular incisors before and after endodontic instrumentation, identifying regions inaccessible to the action of files (Critical instrumentation Area - CA) in a three-dimensional perspective. Thirty human mandibular central incisors were selected, assigned to two groups (n=15) and instrumented using ProTaper Universal rotary files. In the RX group, longitudinal digital radiographic images were obtained in the buccolingual (BL) and mesiodistal (MD) views. In the CT group, cross-sectional micro-computed tomography (µCT) images were obtained at 3, 9 and 15 mm from the apex. The canal area of the specimens was evaluated before and after instrumentation using digital images from each group. Data were analyzed using t-test, one-way ANOVA with subdivided parcels and Tukey's test (α=0.05). The canal area found in the MD radiographs was larger than in the BL radiographs, which was also confirmed in the transversal images (p<0.01). The CA was only detected in the MD radiographs and µCT scans. On the root canal configuration, a continuous reduction in the canal conicity was observed in BL radiographs, while in MD view there was a constriction at the cervical third and subsequent increase at the middle third (p<0.01). The conical shape of the root canal was observed only in the BL view. The canal enlargement in BL radiographs was not indicative of homogeneous instrumentation, since unprepared areas (CA) were also verified on the buccal and lingual walls in different images.

Assessment of influence of flexion angles of files in apical stop preparation by using manual and rotary instrumentation techniques.

INTRODUCTION: This study aimed to evaluate the influence of flexion angles produced by files during root canal instrumentation on the final form of the apical stop. METHODS: Sixty human lower incisors were divided into 3 groups (n = 20). After access preparation and working length determination, radiographs were taken from a mesiodistal and buccolingual direction with #15 K-file inserted to working length. Teeth from FlexM group were instrumented with stainless steel Flexofiles up to #40 file. For ProM and ProR groups, hand ProTaper Universal and ProTaper Universal rotary files were used, respectively, up to file F4. New radiographs were taken as previously described. After gutta-percha insertion, the apex of each specimen was ground, allowing gutta-percha visualization, and an image of the apex was captured to identify root canal deformation with computer software. The flexion of files was evaluated from both initial and final radiographs as the angle formed between the divergence of the file path and its virtual image represented by the direction taken by the file in the absence of curvature. RESULTS: FlexM group presented the highest variation in flexion angles compared with ProM (P = .112) and ProR (P = .024) groups. Nickel-titanium rotary system (ProR) reduced apical stop deformation compared with the manual techniques that used nickel-titanium (P = .011) or stainless steel (P = .025) files. CONCLUSIONS: Force vectors caused by the flexion angles of the files during the instrumentation of curved canals promoted apical stop deformation. ProTaper Universal rotary files showed less apical deformation than hand ProTaper Universal and stainless steel files.

Micro-computed tomographic evaluation of removal and extrusion of root filling material during canal retreatment / Avaliação por meio de microtomografia computadorizada da remoção e extrusão de material obturador durante retratamento endodôntico

This study aimed to assess the efficiency of manual and rotary techniques for removing root filling material in endodontic treated canals and to evaluate the extrusion of debris via apical foramen. After access preparation, thirty human lower central incisors were instrumented, filled and divided into two groups (n=15): MNmanual retreatment technique; RT- rotary retreatment technique. The teeth were submitted to micro-computed tomographic scanning before and after the retreatment procedure, for quantifying the remaining filling material by relating the initial and final conditions. The analysis was conducted separately in all root thirds. The volume of material extruded through the apical foramen was also quantified. The data were statistically analyzed using t-test and two-way analysis of variance (ANOVA) at 5% of significance. No significant differences were detected between remaining filling material for the techniques evaluated (p=0.74), even considering the apical third only (p>0.75). Significant differences were found for the remaining filling material verified between the cervical third and middle/apical thirds, with lower values being observed at the cervical third for both groups (p<0.05). Apical extrusion of filling material was verified in seven specimens (2 from MN group and 5 from RT group). Both techniques showed similar performance for removing filling material from the root canal, considering the whole tooth or the root thirds independently. The apical extrusion of filling material observed was not sufficient to indicate which technique has increased tendency to induce more events during retreatments.

Este estudo objetivou avaliar a eficiência das técnicas manual e rotatória na remoção de material obturador de dentes tratados endodonticamente, além de verificar a extrusão de resíduos via forame apical. Após acesso endodôntico, trinta incisivos centrais inferiores humanos foram instrumentados, obturados e divididos em dois grupos (n=15): MN- técnica de retratamento manual; RT- técnica de retratamento rotatória. Os dentes foram submetidos à escaneamento micro-tomográfico previamente e após os procedimentos de retratamento para quantificação do remanescente de material obturador relacionando as condições inicial e final. Esta análise foi conduzida separadamente em todos os terços radiculares. O volume de material extruído via forame apical também foi quantificado. Os dados foram analisados estatisticamente por meio dos Testes T e de Análise de Variância em dois níveis com significância em 5%. Diferenças significantes não foram detectadas entre a quantidade de material remanescente para as duas técnicas avaliadas (p=0,74), mesmo considerando o terço apical separadamente (p>0.75). Diferenças significantes foram encontradas na quantidade de material remanescente verificado entre os terços cervical e médio/apical, com menores valores detectados no terço cervical para ambos os grupos (p<0.05). Extrusão apical de material obturador foi identificada em sete espécimes (2 do grupo MN e 5 do grupo RT). As duas técnicas avaliadas apresentaram desempenho similar na remoção do material obturador do canal radicular, considerando o dente como um todo ou os terços radiculares separadamente. A extrusão apical de material obturador verificada não foi suficiente para indicar qual técnica possui maior tendência de promover eventos durante o retratamento.

Morphometric evaluation and planning of anticurvature filing in roots of maxillary and mandibular molars

This study aimed to guide the planning of anticurvature filing using pre-determined anatomical points on teeth to establish directions for proper implementation of the technique. Two hundred digital periapical radiographs of human molar teeth were selected and divided into two groups (n = 100): MX (maxillary) and MD (mandibular) molars. Mesiobuccal roots were considered for the MX group and mesial roots for the MD group. Pre-determined anatomical points required for planning the anticurvature filing on the root canal path were located, and the distances between these points obtained. The anticurvature filing was simulated in two different protocols for each group, and the region of dentin removal and the remaining dentin thickness were measured in the safety and danger zones of the root canals. Statistical analysis was carried out at a significance level of 5%. The distances between the anatomical points and the thickness of remaining dentin showed significant differences when the two groups were compared (p < 0.001). No significant differences were found between the two experimental groups regarding the area of dentin removal at the root region, but differences were detected in comparison with dentin removal at the crown (p < 0.001). In terms of wear produced after simulation of both anticurvature filing protocols, significant differences were verified for all regions, except for the dentin remaining at the danger zone. The radiographic location of anatomical points allows for planning and implementation of controlled and efficient anticurvature filing and can be performed in the same manner for maxillary and mandibular molars.

Influence of flexion angle of files on the decentralization of oval canals during instrumentation

The aim of this study was to evaluate the influence of the flexion angle of files on the decentralization of root canals during instrumentation. Fifteen lower incisors were instrumented with Protaper Universal files and radiographed in two directions (mesiodistal and buccolingual) before and after instrumentation with a #15 K-file in position for evaluating the flexion angle of files. The specimens were also scanned before and after instrumentation using micro-computed tomography to obtain the canal area and the distance from the center position of the file to the canal walls. Sections located 1.0 mm (end of the canal), 3.0 mm (apical third), 9.0 mm (middle third), and 15.0 mm (cervical third) from the apex were verified. After instrumentation, the flexion angles of files decreased by an average of 0.76º in the buccolingual direction and 1.92º in the mesiodistal direction (p < 0.001); the canal area increased by an average of 0.58, 0.37, 0.23 and 0.13 mm2 from the cervical to the end of the root canal (p < 0.001). Non-instrumented areas were observed on the buccal and lingual walls, and effective action of files was determined on the mesial and distal walls. The sections from the end of the canal showed canal deviation toward the lingual wall, whereas the other sections showed deviation toward the buccal wall. The flexion angles of files influence the final shape of the root canal, resulting in file decentralization along the pathway of the canal.

Ex vivo comparison of the accuracy of Root ZX II in detecting apical constriction using different meter's reading.

The purpose of this study was to compare the accuracy of Root ZX II to locate the apical constriction with the display meter set at "0.5" and "1'"reading. Seventy single-rooted teeth were soaked in an alginate model and randomly distributed in 2 groups (n = 35). Measurements were taken following canal irrigation with 1% NaOCl. The length was established using a #20 K-file attached to the holder when the display indicator reached the marks "0.5" (group I) or "1" (group II), after the meter read "Apex." Then, the file was fixed in position and the teeth removed from the alginate. The apical portion of the root was shaved until the tip of the file could be seen, the distance to the apical constriction verified by means of a stereomicroscope and the measurements compared. Statistical analysis was performed by using Student t test with the null hypothesis set as 5%. The mean positions of the file tip relative to the apical constriction were -0.23 +/- 0.39 mm and -0.42 +/- 0.45 for groups I and II, respectively, with no statistical difference (P > .05). The accuracy was 90.5% and 83.78% for the Root ZX II "0.5" and "1" readings, respectively. It was concluded that the meter reading "1" of Root ZX II reduced the risk of working length overestimation.

Critical Instrumentation Area: Influence of Root Canal Anatomy on the Endodontic Preparation

The aim of this study was to evaluate the root canal anatomy of mandibular incisors before and after endodontic instrumentation, identifying regions inaccessible to the action of files (Critical instrumentation Area - CA) in a three-dimensional perspective. Thirty human mandibular central incisors were selected, assigned to two groups (n=15) and instrumented using ProTaper Universal rotary files. In the RX group, longitudinal digital radiographic images were obtained in the buccolingual (BL) and mesiodistal (MD) views. In the CT group, cross-sectional micro-computed tomography (µCT) images were obtained at 3, 9 and 15 mm from the apex. The canal area of the specimens was evaluated before and after instrumentation using digital images from each group. Data were analyzed using t-test, one-way ANOVA with subdivided parcels and Tukey's test (α=0.05). The canal area found in the MD radiographs was larger than in the BL radiographs, which was also confirmed in the transversal images (p<0.01). The CA was only detected in the MD radiographs and µCT scans. On the root canal configuration, a continuous reduction in the canal conicity was observed in BL radiographs, while in MD view there was a constriction at the cervical third and subsequent increase at the middle third (p<0.01). The conical shape of the root canal was observed only in the BL view. The canal enlargement in BL radiographs was not indicative of homogeneous instrumentation, since unprepared areas (CA) were also verified on the buccal and lingual walls in different images.

Este estudo avaliou a anatomia do canal radicular de incisivos inferiores, antes e após a instrumentação endodôntica, identificando regiões inacessíveis à ação das limas (Área Crítica de instrumentação - AC), em uma perspectiva tridimensional. Trinta incisivos centrais inferiores humanos foram selecionados, divididos em dois grupos (n=15), e instrumentados usando limas rotatórias ProTaper Universal. No grupo RX, imagens longitudinais foram obtidas em duas incidências, vestíbulo-lingual (VL) e mésio-distal (MD), por meio de radiografias digitais. No grupo CT, imagens transversais foram obtidas por meio de microtomografia computadorizada (μTC), em secções localizadas a 3 mm, 9 mm, e 15 mm do ápice. A área do canal das amostras foi avaliada antes e após a instrumentação usando as imagens digitais de cada grupo. Os dados foram analisados por meio do teste t, ANOVA a um critério com parcela subdividida e ao teste de Tukey (α=0,05). A área de canal encontrada nas radiografias MD foi maior do que nas radiografias VL, o que também foi confirmado nas imagens transversais (p<0,01). A Área Crítica de instrumentação só foi detectada nas radiografias MD e nas seções de μTC. Na configuração de canal, a redução contínua na conicidade do canal foi observada nas radiografias VL, enquanto na incidência MD, houve uma constrição no terço cervical e um subsequente aumento no terço médio (p<0,01). A forma cônica do canal radicular foi observada somente na visão VL. O alargamento do canal verificado nas radiografias VL não foi indicativo de instrumentação homogênea, uma vez que áreas não instrumentadas (AC) foram observadas nas paredes vestibular e lingual em visões distintas.

Avaliação da eficácia de métodos de limpeza de limas endodônticas / Evaluation of the effectiveness of cleaning endodontic files methods

A reutilização de limas no tratamento endodôntico é uma realidade na rotina de grande parte dos profissionais. Alguns cuidados devem ser tomados para que a limpeza inadequada das mesmas não prejudique o processo de esterilização, aumentando o risco de infecção cruzada entre pacientes. Muitas dúvidas recaem na maneira como as limas devem ser limpas após o uso clínico e antes da esterilização. O presente trabalho avaliou a efetividade de três métodos de limpeza das limas endodônticas, foram utilizadas 18 caixas de limas da primeira série tipo Kerr, divididas em três grupos (n=6) de acordo com o tratamento endodôntico: G1- dentes com vitalidade; G2- dentes com necrose e G3- dentes com necessidade de retratamento. Terminada a instrumentação as limas foram avaliadas com microscópio óptico em um aumento de 40x, atribuindo-se valores para a presença ou ausência de detritos aderidos na superfície da parte ativa da lima. Em seguida foram submetidas a um dos processos de limpeza: torsão da lima contra gaze embebida em álcool 70%, limpeza com escova e detergente e limpeza em cuba ultrasônica e detergente e novamente avaliadas. Os resultados apresentaram diferença estatística significante entre os métodos, sendo a limpeza com a gaze o menos eficaz (p<0,05). Todos os processos de limpeza testados promoveram redução significativa nos valores de detritos, no entanto não houve nenhum método 100% efetivo em todas as situações analisadas.

The reuse of files in root canal treatment is a reality in routine of most professionals. Many questions fall on how the files should be cleaned after clinical use and before sterilization. Some care should be taken that inadequate cleaning of the files does not harm the sterilization process, increasing the risk of cross infection between patients. This study evaluated the effectiveness of three methods for cleaning of endodontic files were used 18 boxes of files from the first series Kerr, divided into 3 groups (n = 6) according to the treatment endodontic: G1-teeth with vitality; G2- teeth with necrosis and G3- teeth requiring retreatment. After instrumentation the files were evaluated with an optical microscope at a 40X magnification, assigning values to the presence or absence of debris adhered to the surface of the active part of the file. They were then subjected to one of the cleaning processes: torsion file against gauze soaked in 70% alcohol, cleaning brush with detergent and ultrasonic cleaning tank and detergent and re-evaluated. The results showed statistically significant difference between the methods, and cleaning with gauze less effective (p <0.05). All cleaning processes tested caused significant reduction in the amounts of debris; however there was no 100% effective method in the analyzed situations.

Avaliação histoquímica da permeabilidade dentinária após a utilização do edta como auxiliar na irrigação do canal radicular / Histochemical evaluation of dentin permeability after using edta as auxiliar irrigation of the root canal

O presente estudo avaliou a permeabilidade dentinária em toda a extensão do canal radicular após o uso do EDTA associado a diferentes concentrações de NaOCl. Foram utilizados cinquenta incisivos bovinos divididos em cinco grupos experimentais (n=10) de acordo com as soluções irrigantes empregadas: G1- NaOCl 1%; G2- NaOCl 5,25%; G3- NaOCl 1% + EDTA; G4- NaOCl 5,25% + EDTA; G5- Água destilada (grupo controle). Após o preparo biomecânico, as raízes foram submetidas ao método de coloração histoquímico com sulfato de cobre a 10% e ácido rubeânico a 1% para identificação da permeabilidade dentinária. Para a análise morfométrica as amostras foram seccionadas transversalmente, obtidas três secções de cada terço, desidratadas e clarificadas. Analisadas em microscopia óptica para quantificar a penetração dos íons cobre na dentina radicular. Após a análise estatística dos dados, os resultados indicaram que, houve diferença significativa entre os terços analisados seguindo uma ordem de efetividade do terço cervical maior que o médio e este maior que o apical. Entretanto, nenhuma diferença significante em relação à permeabilidade foi encontrada quando se comparou as diferentes soluções estudadas. Concluiu-se que o uso do EDTA associado com diferentes concentrações de hipoclorito de sódio, como irrigante final, não promoveu alteração na permeabilidade dentinária no canal radicular em relação as soluções usadas isoladamente.

This study evaluated the dentine permeability on the length of the root canal after the use of EDTA associated with different concentrations of NaOCl. Fifty bovine incisors were used divided into five experimental groups (n = 10) according to the irrigating solutions used: G1- 1% NaOCl; G2- 5.25% NaOCl; G3- 1% NaOCl + EDTA; G4- 5.25% NaOCl + EDTA; G5- distilled water (control group). After biomechanical preparation, the roots were subjected to histochemical staining method with 10% copper sulfate and then in 1% rubeanic acid alcohol solution for identification of dentin permeability. For the morphometric analysis the samples were cross sectioned, obtained three sections of each third, dehydrated and clarified. Analyzed with light microscopy to quantify the penetration of copper ions in the root dentin. After statistical analysis, the results indicated that there were significant differences among thirds analyzed by an order of effectiveness of the cervical third larger than the middle and this larger than the apical. However, no significant difference in relation to the permeability was found when comparing the different solutions studied. In conclusion, the use of EDTA associated with different concentrations of sodium hypochlorite, as final rinse, did not cause changes in dentin permeability in relation solutions used alone.

Cytotoxic response of two cell lines exposed in vitro to four endodontic sealers

Aim: To investigate the cytotoxicity of four endodontic sealers with different bases – Epiphany(EPH), AH Plus (AHP), Sealer 26 (S26) and Endofill (ENF) – on human foreskin fibroblasts(HFF) and mouse macrophages (J774/G8). Methods: Cells were placed in direct contact withfreshly prepared endodontic sealers in polypropylene tubes. The cells were incubated for 24, 48and 72 h. Cytotoxicity was assessed using the MTT assay (cell viability) and Griess reagent (NOrelease). Results: On the HFF cultures, EPH showed the lowest viability levels of all four sealersat 24 h (p<0.05), but over time (72h), EPH lessened its toxic levels in a similar pattern as the otherthree materials (p>0.05). The viability of all four sealers on the macrophage cultures showed nostatistically significant difference over time, except between EPH and AHP at 72 h (p<0.05).Although uniformity was not detected in macrophage and fibroblast release of NO in response tosealers over time, a trend of increased NO levels for EPH (p<0.05) was observed. Conclusions:The response pattern varied depending on time and type of cell line used for analysis, althoughthe results indicate a higher cytotoxicity for EPH in short-term tests.

Influence of calcium hydroxide on marginal leakage of endodontically treated teeth

Aim: To evaluate the influence of residual calcium hydroxide (CH) intracanal medication consideringtwo dye leakage locations (apical foramen and middle root canal third) by quantifying the diffusionof India ink in length and depth. Methods: After biomechanical preparation, 72 single-rootedbovine teeth were divided into two groups in which half was filled with a CH and saline paste. After7 days, the medication was removed and the canals in both groups were filled. Half of thesamples had the apical third and part of middle third removed for infiltration of India ink at themiddle third (MTI), while the rest were infiltrated at the apical foramen (AI). The followingexperimental groups were formed (n = 18 each): A1 – CH-medicated + AI, A2 – CH-medicated+ MTI, B1 – non-medicated + AI, B2 – non-medicated + MTI. For evaluation of dye leakage, theexperimental specimens were cross-sectioned, photographed and had the infiltration perimetermeasured using the Image Tool 3.00 software. The Mann-Whitney U-test was used for statisticalanalysis (p<0.05). Results: The lowest values of dye penetration in length and depth werefound in the groups receiving intracanal medication (A1 and A2). Conclusions: Lower dyepenetration in length and depth at the two different locations was observed in the canals withresidual CH intracanal medication.

Avaliação do fluxo e direcionamento do jato de água do sistema de refrigeração de turbinas de alta rotação / Evaluation of the flow and direction way of the water spray high-speed handpieces

O desgaste da dentina por turbinas de alta rotação pode produzir calor excessivo e comprometer o tecido pulpar. O objetivo da pesquisa foi avaliar o fluxo e o direcionamento da água das turbinas de alta rotação antes do uso clínico pelos alunos do Curso de Odontologia da Universidade Federal de Uberlândia. Sessenta turbinas de alta rotação tiveram fluxo e direção da água expirada avaliados. A avaliação do direcionamento do jato de spray ar/água foi feita através de uma documentação fotográfica com a turbina de alta rotação acionada, considerando-se direcionamento adequado quando o mesmo atingia diretamente a parte ativa da broca. O fluxo e o volume de água expirado por cada aparelho examinado foi verificado por meio do acionamento da turbina de alta rotação sobre um frasco graduado tipo Becker durante um minuto. Para avaliação do volume de água liberado, foi considerado fluxo adequado um volume de água maior ou igual a 30 ml por minuto. Os resultados da análise estatística demonstraram que 88,33% das turbinas apresentaram fluxo adequado e apenas 23,33% direcionamento adequado. Maior atenção deve ser dada ao direcionamento do fluxo de água das turbinas de alta rotação.

The dentin wear by high-speed handpieces can produce excessive heat and compromise the pulp tissue. The research aimed to evaluate the flow and direction of the water spray high-speed handpieces before clinical use by students of Dentistry, Federal University of Uberlandia. Sixty high-speed handpieces had flow and direction of water expired evaluated. The assessment of the direction of the jet of air / water spray was made by a photographic documentation with high-speed handpiece driven, considering the appropriate direction when it hit directly on the active part of the bur. The flow and volume of water exhaled by each turbine examined was assessed through the drive highspeed handpiece on a Becker type flask for one minute. To evaluate the volume of water released was considered an adequate flow volume of water greater than or equal to 30 ml per minute. The statistical analysis results showed that 88.33% of the turbines had adequate flow and only 23.33% adequate direction. Greater attention should be given to the direction of flow of water from high-speed handpieces

CVD (Chemical Vapor Deposition) - solução para controle de temperatura durante preparo cavitário? / CVD (Chemical Vapor Deposition) - solution for control of temperature during cavity preparation?

Os procedimentos restauradores em Odontologia utilizam brocas, turbinas de alta rotação, laser e novas tecnologias, como as pontas diamantadas obtidas pelo processo de deposição química a vapor (CVD). O uso incorreto desses métodos pode gerar aquecimento excessivo e agredir o complexo dentinopulpar, provocando lesões que variam de leve à grave e até mesmo a necrose da polpa. O objetivo deste trabalho foi revisar e discutir o aumento de temperatura no complexo dentinopulpar durante o preparo cavitário, causado pelas brocas diamantadas convencionais usadas em turbina de alta rotação, pelo laser e pelas pontas diamantadas CVD acopladas ao ultrassom. Treze estudos foram encontrados após busca na base de dados PubMed no período de 1998 a 2009, sendo quatro relacionados a brocas diamantadas em turbinas de alta rotação, sete acerca de sistemas a laser e dois sobre as pontas CVD. De acordo com a literatura científca pesquisada, pode-se concluir que nenhum dos métodos aumenta a temperatura a ponto de causar injúria pulpar irreversível. Porém, não há estudos suficientes publicados para se afirmar que as pontas diamantadas CVD apresentam-se como a solução para controle do aumento de temperatura durante o preparo cavitário.

The restorative procedures in dentistry use burs, high-speed handpieces, laser and new technologies such as diamond burs obtained by the process of chemical vapor deposition (CVD). The misuse of these methods can generate excessive heat, and harm the pulpodentin complex, causing injuries ranging from mild to severe and even necrosis of the pulp. The objective was to review and discuss the temperature increase in pulpodentin complex during cavity preparation, caused by conventional diamond burs used in high-speed handpieces, laser and the CVD ultrasound diamond burs. Thirteen studies were found after a search on PubMed database from 1998 to 2009, and 4 were related to diamond burs at high-speed handpieces, 7 about laser systems and 2 about the CVD burs. According to the researched literature, we can conclude that none of the methods increases the temperature to the point of causing irreversible injury on the pulp. However, there are not enough published studies that confrm CVD diamond burs as the solution to controlling the temperature increase during cavity preparation.

Avaliação da reação tecidual a cimentosendodônticos recém-manipulados e suarelação com o subtipo de macrófago M1 / Evaluation of tissue reaction to freshly mixed endodontic sealers and their relationship with the M1 macrophage phenotype

Esse estudo avaliou a resposta tecidualpara cimentos recém-manipulados (Sealer 26, ou SE26;e Epiphany, ou EPH) e a relação entre macrófagos M1e reparação tecidual. Material: foram utilizados 21 ratospara avaliar a resposta tecidual aos 7, 14 e 21 diaspós-implantação. Metade das seções histopatológicasfoi marcada com anticorpos anti-iNOS (M1 macrófagossubconjunto), e metade foi classificada de acordo coma intensidade inflamatória. Resultados: no dia 7, nãofoi encontrada diferença significativa na intensidade dareação inflamatória entre os cimentos. Nos dias 14 e21, SE26 mostrou uma reação inflamatória mais intensado que o EPH (p < 0,05). Nos dias 7 e 14, o númerode células iNOS+ foi significativamente maior do queem EPH SE26 (p < 0,05). Conclusões: SE26 foi maistóxico do que o EPH. O grau de inflamação observadaem EPH teve relação inversa com a quantidade de macrófagosM1 observados.