Mechanical removal of necrotic periodontal ligament by either Robinson bristle brush with pumice or scalpel blade. Histomorphometric analysis and scanning electron microscopy

One of the important factors accounting for successful delayed replantation of avulsed teeth is seemingly the type of root surface treatment. Removal of necrotic cemental periodontal ligament remnants may prevent the occurrence of external root resorption, which is the major cause of loss of teeth replanted in such conditions. The purpose of this study was to compare the efficacy of two mechanical techniques for removal of root-adhered periodontal ligament. Preservation or removal of the cementum layer concomitantly with these procedures was also assessed. Forty-five roots of healthy premolars extracted for orthodontic purposes were selected. After extraction, the teeth were kept dry at room temperature for 1 h and then immersed in saline for rehydration for an additional 10 min. Thereafter, the roots were assigned to three groups, as follows: group 1 (control) - the cemental periodontal ligament was preserved; group 2 - removal of the periodontal ligament by scraping root surface with a scalpel blade (SBS); group 3 - periodontal ligament remnants were removed using a Robinson bristle brush at low-speed with pumice/water slurry (RBP). The specimens were analysed histomorphometrically and examined by scanning electron microscopy. The quantitative and qualitative analyses of the results showed that the RBP technique was significantly more effective than the SBS technique for removal of the periodontal ligament remnants adhered to root surface. Both techniques preserved the cementum layer.

Primary Tooth Enamel Loss After Manual and Mechanical Microabrasion

Purpose: This study's purpose was to assess the amount of dental enamel loss on primary incisors after manual or mechanical microabrasion with a phosphoric acid/pumice poste. Methods: Ten exfoliated primary maxillary incisors were bisected faciolingually and the resulting 20 halves were randomly assigned to 2 groups: group 1 (N=10) manual technique (plastic spatula); and group 2 (N=10) mechanical technique (rubber cup attached to a low-speed handpiece). Microabrasion was performed on the buccal surface using an abrasive paste prepared with 37% phosphoric acid and pumice. Ten 20-second applications alternated with 20-second risings were performed in each group. Enamel thickness measurements made under stereomi-croscopy before and after microabrasion were analyzed statistically by analysis of variance and pairwise t test. Results: There was a statistically significant difference (P=.003) between the manual and mechanical techniques. The mechanical technique produced a mean enamel loss of 274.16 mu m (66% of total enamel thickness), while the mean enamel loss with the manual technique was 152.59 mu m (39% of total enamel thickness). Conclusion: Manual microabrasion using a plastic spatula removed less enamel, but was sufficient to eliminate most superficial stains and defects, and may be a viable option for the microabrasive technique on primary teeth. (Pediatr Dent 2008;30:420-3) Received March 15, 2007 / Lost Revision September 19, 2007 / Revision Accepted October 19, 2007

Roughness of Human Enamel Surface Submitted to Different Prophylaxis Methods

The purpose of this in vitro study was to evaluate alterations in the surface roughness and micromorphology of human enamel submitted to three prophylaxis methods. Sixty-nine caries-free molars with exposed labial surfaces were divided into three groups. Group I was treated with a rotary instrument set at a low speed, rubber clip and a mixture of water and pumice; group II with a rotary instrument set at a low speed, rubber cup and prophylaxis paste Herjos-F (Vigodent S/A Industria e Comercio, Rio de Janeiro, Brazil); and group III with sodium bicarbonate spray Profi II Ceramic (Dabi A dante Indtistrias Medico Odontologicas Ltda, Ribeirao Preto, Brazil). All procedures were performed by the same operator for 10 s, and samples were rinsed and stored in distilled water. Pre and post-treatment surface evaluation was completed using a surface profilometer (Perthometer S8P Marh, Perthen, Germany) in 54 samples. In addition, the other samples were coated with gold and examined in a scanning electron microscope (SEM). The results of this study were statistically analyzed with the paired t-test (Student), the Kruskal-Wallis test and the Dunn (5%) test. The sodium bicarbonate spray led to significantly rougher surfaces than the pumice paste. The use of prophylaxis paste showed no statistically significant difference when compared with the other methods. Based on SEM analysis, the sodium bicarbonate spray presented an irregular surface with granular material and erosions. Based on this study, it can be concluded that there was an increased enamel stuface roughness when teeth were treated with sodium bicarbonate spray when compared with teeth treated with pumice paste.

Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis

A dispersão da amostra de solo é uma etapa fundamental da análise granulométrica, sendo realizada mediante o uso de dispersantes químicos e agitação mecânica. O objetivo deste trabalho foi avaliar a eficiência de mesa agitadora reciprocante de baixa rotação na dispersão mecânica de amostras de solos de diferentes classes texturais. Foram realizadas análises granulométricas em 61 amostras com quatro repetições, empregando o método da pipeta para determinação da fração argila e tamisagem para determinação das frações areia grossa, areia fina e areia total, sendo o silte determinado por diferença. Na avaliação de desempenho, os resultados obtidos com uso da mesa agitadora reciprocante (MAR) foram comparados com dados disponíveis para as mesmas amostras oriundos de relatórios do Ensaio de Proficiência IAC para Laboratórios de Análises de Solos - Prolab/IAC. Análises de acurácia foram realizadas com base nos valores dos intervalos de confiança definidos para cada fração granulométrica componente de cada amostra ensaiada. Indicadores gráficos também foram utilizados na comparação de dados, por meio de dispersão e ajuste linear. A estatística descritiva indicou preponderância de baixa variabilidade em mais de 90 % dos resultados obtidos para as amostras de texturas arenosa, média e argilosa e em 68 % dos obtidos para as amostras de textura muito argilosa, indicando boa repetibilidade dos resultados obtidos com a MAR. Média variabilidade foi mais frequentemente associada à fração silte, seguida da fração areia fina. Os resultados das análises de sensibilidade indicam acurácia de 100 % nas três frações granulométricas - areia total, silte e argila - para todas as amostras analisadas pertencentes às classes texturais muito argilosa, argilosa e média. Para as nove amostras de textura arenosa, a acurácia média foi de 85,2 %, e os maiores desvios ocorreram em relação à fração silte. Nas aproximações lineares, coeficientes de correlação igual (silte) ou superiores (areia total e argila) a 0,93, bem como diferenças menores do que 0,16 entre os coeficientes angulares das retas e o valor unitário, indicam alta correlação entre os resultados de referência (Prolab/IAC) e os obtidos nos ensaios com a MAR. Conclui-se pelo desempenho satisfatório da mesa agitadora reciprocante de baixa rotação para dispersão mecânica de amostras de solo de diferentes classes texturais para fins de análise granulométrica, permitindo recomendar o uso alternativo do equipamento quando se emprega agitação lenta. As vantagens do uso do equipamento nacional incluem o baixo custo, a possibilidade de análise simultânea de grande número de amostras e o uso de frascos comuns, de vidro ou de plástico, baratos e de fácil reposição.

Effects of a non-rinse conditioner on the enamel of primary teeth

O objetivo deste estudo in vitro foi de avaliar ao microscópio eletrônico de varredura os aspectos morfológicos do esmalte de dentes decíduos após condicionamento com ácido fosfórico a 36% ou com um agente condicionador não lavável. Foram selecionados 10 dentes decíduos anteriores esfoliados naturalmente. As amostras sofreram limpeza coronária com pasta de pedra-pomes e água, em baixa-velocidade. O condicionamento foi realizado no esmalte da face vestibular. Os espécimes foram divididos em dois grupos: G1 (n=10): condicionamento com ácido fosfórico a 36% na forma de gel - Conditioner 36 (Dentsply) durante 20 segundos, seguidos de lavagem com água durante 15 segundos; G2 (n=10): condicionamento com NRC - Non Rinse Conditioner (Dentsply) durante 20 segundos, seguidos de secagem com ar durante 15 segundos. As amostras foram desidratadas, montadas em bases metálicas e cobertas com ouro para análise ao microscópio eletrônico de varredura (Jeol JSM 6.100). A análise da eletromicrografias revelou que ambos os agentes condicionadores foram efetivos para condicionar o esmalte de dentes decíduos, causando microporosidades mas com melhor resultado quando utilizou-se o ácido fosfórico a 36% na forma de gel.

Different methods of finishing and polishing enamel

Statement of problem. Highly polished enamel surfaces arc recommended for axial tooth surfaces that will serve as guiding planes and be contacted by component parts of a removable partial denture. There is little evidence to support the assumption that this tooth modification will provide accurate adaptation of the framework and prevent build-up of plaque.Purpose. The aim of this investigation was to evaluate the surface roughness of the tooth enamel, prepared to serve as guiding planes, with different polishing systems.Material and methods. Four different methods (designated A, B, C, and D) for finishing and polishing the prepared enamel surfaces of 20 freshly extracted third molar teeth were studied. Each method involved 3, 4, or 5 different steps. The roughness of each specimen was measured at the start of each method before recontouring, after recontouring, and after each step of the 4 finishing and polishing procedures. The 4 experimental finishing methods were applied after recontouring the axial surfaces (buccal, lingual, and proxinial) of each tooth. Thus the 20 teeth (60 surfaces) were finished and polished by use of 1 of the experimental methods. Surface roughness was measured with a profilometer (mum); the readings of the unpolished enamel Surfaces were recorded as control measurements. Results were statistically analyzed with one-way analysis of variance followed by Tukey's test at the 95% level of confidence.Results. The highest roughness mean values (14.41 mum to 16.44 mum) were found when the diamond bur was used at a high speed for tooth preparation. A significant decrease in roughness values was observed with the diamond bur at a low speed (P<.05). Analysis of the roughness values revealed that all polishing methods produced surface roughness similar to that of the corresponding control teeth.Conclusion. Within the limitations of this study, all finishing procedures tested effectively promoted an enamel surface similar to the original unpolished enamel.

Comparative study of MTA and other materials in retrofilling of pulpless dogs' teeth

This in vivo study compared the effect of mineral trioxide aggregate (MTA), IRM, Super EBA and ZOE in a puttylike consistency, used as retrofilling materials, in the healing process of periapical tissue of pulpless dogs' teeth submitted to a conventional retrofilling technique. Twenty-four premolars obtained from three dogs were used. At the first intervention, the animals were anesthetized, coronal access was obtained and pulpectomy was done. Root canals were kept open to the oral environment for 180 days to induce the formation of apical lesions. After surgical removal of the lesions with curettes, 2 mm of the apical root was cut out perpendicular to the long axis of the teeth, and root-end cavities were shaped with a low-speed round bur. The bone cavities were irrigated and dried, and the root-end cavities were filled with MTA, IRM, Super EBA and ZOE in a puttylike consistency. The bone cavities were passively filled with blood and flaps were sutured. The coronal access openings were cleaned and double-sealed with ZOE and amalgam. After 180 days, the animals were killed by anesthetic overdose, maxilla and mandible were removed and the pieces were processed for histomorphologic analysis. Data were evaluated blindly on the basis of several histopathologic events and the scores obtained were analyzed statistically using the Kruskal Wallis test. No significant differences were observed among MTA, Super EBA and IRM (p>0.05). However, ZOE had a significantly more negative influence on the apical healing (p<0.05). In conclusion, MTA, Super EBA and IRM had similar histopathologic effects among each other and better performance than ZOE used in a puttylike consistency. Furthermore, only MTA stimulated hard tissue deposition in direct contact with the retrofilling material, even when it was inserted under critical conditions.

Effect of dentinal surface preparation on bond strength of self-etching adhesive systems

The aim of this study was to evaluate the effects of dentin surface treatments on the tensile bond strength (TBS) of the self-etching primer Clearfil SE Bond (CSE) and the one-step self-etching One-Up Bond F (OUB). The exposed flat dentin surfaces of twenty-four sound third molars were prepared with diamond bur at high-speed, carbide bur at low-speed or wet ground with #600 grit SiC paper. The adhesive systems were applied to the dentin surfaces and light-cured according to the manufacturers' instructions. A 6-mm high composite crown was incrementally built-up and each increment was light-cured for 40 seconds. After being stored in water (37°C/24 h), the samples were serially sectioned parallel to the long axis, forming beams (n = 20) with a cross-sectional area of approximately 0.8 mm 2. The specimens were tested in a Universal Testing Machine at 0.5 mm/min. The cross-sectional area was measured and the results (MPa) were analyzed by two-way ANOVA and Tukey Test (p < 0.05). Overall, the groups treated with CSE exhibited the highest TBS for all surface treatments. Dentin surfaces prepared with carbide bur at low speed reduced TBS in the CSE group; however, OUB was not affected by surface treatments. The effect of surface abrasive methods on TBS was material-dependent.

Analysis of the distances covered by first division Brazilian soccer players obtained with an automatic tracking method

Methods based on visual estimation still is the most widely used analysis of the distances that is covered by soccer players during matches, and most description available in the literature were obtained using such an approach. Recently, systems based on computer vision techniques have appeared and the very first results are available for comparisons. The aim of the present study was to analyse the distances covered by Brazilian soccer players and compare the results to the European players', both data measured by automatic tracking system. Four regular Brazilian First Division Championship matches between different teams were filmed. Applying a previously developed automatic tracking system (DVideo, Campinas, Brazil), the results of 55 outline players participated in the whole game (n = 55) are presented. The results of mean distances covered, standard deviations (s) and coefficient of variation (cv) after 90 minutes were 10,012 m, s = 1,024 m and cv = 10.2%, respectively. The results of three-way ANOVA according to playing positions, showed that the distances covered by external defender (10642 ± 663 m), central midfielders (10476 ± 702 m) and external midfielders (10598 ± 890 m) were greater than forwards (9612 ± 772 m) and forwards covered greater distances than central defenders (9029 ± 860 m). The greater distances were covered in standing, walking, or jogging, 5537 ± 263 m, followed by moderate-speed running, 1731 ± 399 m; low speed running, 1615 ± 351 m; high-speed running, 691 ± 190 m and sprinting, 437 ± 171 m. Mean distance covered in the first half was 5,173 m (s = 394 m, cv = 7.6%) highly significant greater (p < 0.001) than the mean value 4,808 m (s = 375 m, cv = 7.8%) in the second half. A minute-by-minute analysis revealed that after eight minutes of the second half, player performance has already decreased and this reduction is maintained throughout the second half. ©Journal of Sports Science and Medicine (2007).

Estudio digital radiográfico y densitométrico en mandíbulas de cerdos sometidos a osteotomía con alta y baja velocidad, con refrigeración líquida

The influence of the type of rotary cutting instrument on bone repair after osteotomy in swine jaw, was evaluated using digital and densitometric radiographic examinations, at controlled times. Two cross-sectional dissections were made through the base of the right jaw, one using a high speed rotary instrument and the other using low speed, both with liquid cooling. After established periods the animals were sacrificed and their jaws removed for direct and indirect digital radiographic and densitometric studies using the CROMOX, DIGORA and ODR systems. In the initial periods (7 and 28 days) the bone density was higher in osteotomy areas performed with high rotation speeds, and in the final periods (60 and 90 days) the bone density was higher in the osteotomies performed with low rotation, indicating a better final bone repair with the use of low rotation. The qualitative analysis of the repair process was made by the ODR system which obtained three-dimensional and coloured digital images, which enable the bone thickness to be measured using an aluminium wedge. This showed that by twenty-eight days the bone repair was already apparently complete. © 2010 SECOM.

Effects evaluation of remaining resin removal (three modes) on enamel surface after bracket debonding

Introduction: An appropriate selection of instruments is essential to perform a correct debonding technique, by properly removing orthodontic brackets and the remaining resin. Objective: The aim of this study was to evaluate three methods of remaining resin removal on enamel surface after bracket debonding, by means of Scanning Electron Microscopy (SEM). Methods: Eighteen bovine incisors were selected and divided into three groups (A, B and C) of six teeth each. Before bracket bonding, epoxy resin casts were obtained by impression of the teeth with addition silicon, in order to register baseline enamel characteristics and representing the control group. The methods for remaining resin removal were: Group A - gross and medium granulation Soflex discs; Group B - carbide bur in low-speed; Group C - carbide bur in high-speed. Soflex polishing system fine and ultrafine granulation discs were used for Group A, rubber tips for Groups B and C, and polishing paste for all groups. After polishing, impression of teeth were taken and casts were analyzed by means of SEM. The baseline enamel characteristics (Control Group) were compared to the final aspect of enamel to determine the method that generated less enamel abrasion. Results and Conclusion: The remaining resin removal by carbide bur in low-rotation, and enamel polished with rubber tips followed by polishing paste produced the smaller damage to the enamel.

Estudio histológico comparativo de la reparación ósea entre hueso alveolar y extra-alveolar en los cerdos sometidos a osteotomía con alta y baja velocidad, con refrigeración líquida

Taking into account the bone repair process in pigs has shown a greater similarity among the histological variables studied compared to other biological models, the present study has as its aim to evaluate the histological bone repair process of osteotomy performed on alveolar and extra-alveolar bones, using drilling tools with liquid refrigeration. Material and method: Eighteen Large White pigs weighing between 20 and 25 Kg were divided into three groups of six animals in order to evaluate the osteotomy repairs with low and high speed in the alveolar bone and threes in the extra-alveolar area, study periods of 7, 14 and 28 days. Results: It was observed that in the alveolar bone at the postoperative times of 14 and 28 days, the best repair results were in the osteotomy performed with low speed, while in the 7 day postoperative period, the results with high speed were slightly better, in alveolar areas as well as extra-alveolar areas. There no statistically significant differences between the alveolar and extra-alveolar bone repair process. Conclusions: The repair process, by means of microscopic analysis in the alveolar and extra-alveolar areas, are similar with better results observed in osteotomies performed with low speed drills in the 14 and 28 day study periods, and at 7 days postoperative the results with high speed drills and refrigeration were slightly better. Research works using pigs as an animal model are perfectly viable. © 2011 SECOM.

Estratégias adaptativas da locomoção na ultrapassagem de obstáculo móvel

Pós-graduação em Ciências da Motricidade - IBRC

Remoção mecânica do ligamento periodontal cementário necrosado com escova de Robinson e pedra pomes e com lâmina de bisturi. Análise histomorfométrica e MEV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência in vitro da clorexidina e do chá verde na longevidade de união adesiva resina composta – dentina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)