Examining the Impact of Acute Binge Alcohol Consumption on Trabecular Morphometry and Tensile Strength in Adolescent Sprague Dawley Rat Mandibles / Análisis del Impacto del Consumo Excesivo de Alcohol en la Morfometría Trabecular y la Resistencia a la Tracción en Mandíbulas de Ratas Adolescentes Sprague Dawley

SUMMARY: Underage drinking has become a major public concern having a negative impact on the growth and development of the skeleton. Peak bone mass is attained during adolescence hence the aim of the study was to investigate the effect of acute binge alcohol consumption on trabecular morphometry and tensile strength of the adolescent mandible in the Sprague Dawley (SD) rat. The study comprised of 24 SD rats, aged 7 weeks, placed into either the alcohol-exposed [n=12 (6 males and 6 female)] or pair-fed control group [n=12 (6 male and 6 female)]. The treatment of the groups was as follows; the alcohol exposed group and the pair-fed control were administered a single daily dose of 3 g/kg of 20 % alcohol 3 days a week (alternate days) for 7 days and a caloric equivalent dose of maltose dextrin via oral gavage, respectively. The animals were terminated on day 7 via pentobarbital injection. The mandibles were harvested and scanned using a Nikon XTH 255L 3D-microCT scanner (Nikon Metrology, Leuven, Belgium), and biomechanical tests were done using a Shimadzu universal tensile strength testing machine (China). Following scanning and reconstruction, the trabecular morphometry was assessed using Volume Graphics Studio® software. A 3-point bending test was used to evaluate the tensile strength of the bone. Findings from our study showed changes in some trabecular parameters in the female alcohol-exposed group, while the male groups remained unaffected. No changes in tensile strength were seen when comparing male pair-fed control and alcohol-exposed groups and when comparing female pair-fed control and alcohol-exposed groups. Trabecular and tensile strength differences were observed between the sexes when comparing male pair-fed control and alcohol-exposed groups to female pair-fed control and alcohol-exposed groups. These findings do suggest that acute binge alcohol consumption has detrimental effects on the bone micro-architecture in female alcohol-exposed rats and that differences are seen between the sexes.

El consumo de alcohol entre menores de edad se ha convertido en una importante preocupación pública que tiene un impacto negativo en el crecimiento y desarrollo del esqueleto. La masa ósea máxima se alcanza durante la adolescencia, por lo que el objetivo del estudio fue investigar el efecto del consumo excesivo de alcohol en forma aguda sobre la morfometría trabecular y la resistencia a la tracción de la mandíbula en ratas adolescente Sprague Dawley (SD). El estudio estuvo compuesto por 24 ratas, de 7 semanas de edad, colocadas en el grupo control expuesto al alcohol [n=12 (6 machos y 6 hembras)] y alimentado en parejas [n=12 (6 machos y 6 hembras)]. El tratamiento de los grupos fue el siguiente; al grupo expuesto al alcohol y al control alimentado en parejas se les administró una dosis única diaria de 3 g/kg de alcohol al 20 % 3 días a la semana (días alternos) durante 7 días y una dosis equivalente calórica de maltosa dextrina mediante sonda oral, respectivamente. Los animales fueron sacrificados el día 7 mediante inyección de pentobarbital. Las mandíbulas se recolectaron y se escanearon utilizando un escáner 3D-microCT Nikon XTH 255L (Nikon Metrology, Lovaina, Bélgica), y las pruebas biomecánicas se realizaron utilizando una máquina de prueba de resistencia a la tracción universal Shimadzu (China). Después del escaneo y la reconstrucción, la morfometría trabecular se evaluó utilizando el software Volume Graphics Studio®. Se utilizó una prueba de flexión de 3 puntos para evaluar la resistencia a la tracción del hueso. Los hallazgos de nuestro estudio mostraron cambios en algunos parámetros trabeculares en el grupo de hembras expuestas al alcohol, mientras que los grupos de machos no se vieron afectados. No se observaron cambios en la resistencia a la tracción al comparar los grupos control de machos alimentados en parejas y los grupos expuestos al alcohol y al comparar los grupos control de las hembras alimentadas en parejas y los grupos expuestos al alcohol. Se observaron diferencias trabeculares y de resistencia a la tracción entre los sexos al comparar los grupos control de los machos alimentados en parejas y expuestos al alcohol con los grupos de control de hembras alimentadas en parejas y expuestas al alcohol. Estos hallazgos sugieren que el consumo excesivo de alcohol tiene efectos perjudiciales sobre la microarquitectura ósea en ratas hembras expuestas al alcohol y que se observan diferencias entre los sexos.

Effect of a Dose-Dependent Administration of Binge Alcohol on the Mandible in the Adolescent Sprague Dawley Rat / Efecto de una Administración Dosis-Dependiente de Alcohol en Exceso en la Mandíbula de la Rata Sprague Dawley Adolescente

SUMMARY: Binge drinking in adolescents has a negative effect on the developing skeleton and the attainment of peak bone mass. Our study aimed to examine the effect of binge drinking on the growth and functional integrity of the adolescent Sprague Dawley rat mandible and to determine if a dosage of 1.5 g/kg is sufficient to produce a binge-model of consumption. A total of eight 7-week-old adolescent (male) Sprague Dawley rats were randomly placed into 4 groups with two rats each: 1-week alcohol-exposed rats, 1-week pair- fed control rats, 4-week alcohol-exposed rats and 4-week pair-fed control rats. The alcohol exposed groups were administered a single daily dose via oral gavage of 1.5 g/kg of 20 % alcohol 3 days a week (alternate days) for 7 or 28 days. The pair-fed control groups were administered a caloric equivalent dose of maltose dextrin via oral gavage on the same days as the alcohol-exposed rats. The one-week alcohol exposed, and control rats were terminated on day 7 and the four-week alcohol exposed and control rats on day 28. The mandibles were dissected out and osteometric measurements determined using a digital vernier caliper. Bones were scanned using a 3D-microCT scanner (Nikon XTH 255L). Biomechanical tests were done using a Shimadzu universal testing machine. Differences observed were regarding mandibular osteometry, which showed a reduced height in the central portion of the alveolar bone (Al'-Me), and an increase in the height of the condylar head (Cd-Ag) in the 1-week alcohol-exposed rats when compared to the 1-week pair-fed control rats. No other differences were noted. Lack of significant changes seen between the alcohol and pair-fed control groups in both acute binge and chronic binge exposed rats is likely due to the low dose of alcohol administered to the rats in the study thus a higher dose is proposed.

El consumo excesivo de alcohol en adolescentes tiene un efecto negativo en el desarrollo del esqueleto y en la consecución de la masa ósea máxima. Nuestro estudio tuvo como objetivo examinar el efecto del consumo excesivo de alcohol sobre el crecimiento y la integridad funcional de la mandíbula de la rata adolescente Sprague Dawley y determinar si una dosis de 1,5 g/kg es suficiente para producir un modelo de consumo compulsivo. Un total de ocho ratas Sprague Dawley adolescentes (machos) de 7 semanas de edad se colocaron aleatoriamente en 4 grupos con dos ratas cada uno: ratas expuestas al alcohol durante 1 semana, ratas de control alimentadas en parejas durante 1 semana, ratas expuestas al alcohol durante 4 semanas, y ratas de control alimentadas en parejas durante 4 semanas. A los grupos expuestos al alcohol se les administró una dosis única diaria mediante sonda oral de 1,5 g/kg de alcohol al 20 % 3 días a la semana (días alternos) durante 7 o 28 días. A los grupos de control alimentados por parejas se les administró una dosis calórica equivalente de maltosa dextrina mediante sonda oral los mismos días que a las ratas expuestas al alcohol. Las ratas expuestas al alcohol durante una semana, las ratas de control al día 7, las ratas expuestas al alcohol durante cuatro semanas y las ratas de control al día 28. Se diseccionaron las mandíbulas y se determinaron las mediciones osteométricas utilizando un calibre vernier digital. Los huesos se escanearon utilizando un escáner 3D-microCT (Nikon XTH 255L). Las pruebas biomecánicas se realizaron utilizando una máquina de pruebas universal Shimadzu. Las diferencias observadas se relacionaron con la osteometría mandibular, que mostró una altura reducida en la porción central del hueso alveolar (Al'-Me) y un aumento en la altura de la cabeza condilar (Cd-Ag) en las ratas expuestas al alcohol durante una semana, en comparación con las ratas control alimentadas en parejas durante una semana. No se observaron otras diferencias. La falta de diferencias significativas entre los grupos de alcohol y de control alimentados en parejas expuestas a ebriedad aguda y ebriedad crónica, probablemente se deba a la baja dosis de alcohol administrada a las ratas en el estudio, por lo que se propone una dosis más alta.

Monoaxial Mechanical Tests on Porcino Knee Ligaments / Ensaios mecânicos monoaxiais nos ligamentos do joelho porcino

Abstract The failure of ligament reconstruction has different risk factors, among which we can highlight the period before its incorporation, which is a mechanically vulnerable period. Loss of resistance over time is a characteristic of living tissues. Dissection with bone insertions of the cruciate ligaments of animal models is not described; however, it is essential for monoaxial assays to extract information from tests such as relaxation. The present work describes the dissection used for the generation of a test body for the performance of nondestructive tests to evaluate the mechanical behavior. We performed dissection of four porcino knee ligaments, proposing a dissection technique for the cruciate ligaments with bone inserts for comparison with collateral ligaments. The ligaments were submitted to relaxation tests and had strain gauges placed during the tests. The results showed viscoelastic behavior, validated by strain gauges and with a loss over time; with some ligaments presenting with losses of up to 20%, a factor to be considered in future studies. The present work dissected the four main ligaments of the knee demonstrating the posterior approach that allows maintaining their bone insertions and described the fixation for the monotonic uniaxial trials, besides being able to extract the viscoelastic behavior of the four ligaments of the knee, within the physiological limits of the knee.

Resumo A falha da reconstrução ligamentar tem diferentes fatores de risco, dentre os quais podemos destacar o período antes da sua incorporação, o qual configura um período mecânico vulnerável. A perda de resistência ao longo do tempo é uma característica dos tecidos vivos. A dissecção com as inserções ósseas dos ligamentos cruzados de modelos animais não é descrita; todavia, para os ensaios monoaxiais, é fundamental extrair as informações de ensaios como os de relaxação. O presente trabalho realiza a descrição da dissecção utilizada para a geração de corpo de prova para a realização de ensaios não destrutivos para avaliar o comportamento mecânico. Realizamos dissecção de quatro ligamentos de joelho porcino, propondo uma técnica de dissecção para os ligamentos cruzados com as inserções ósseas para comparação com os colaterais. Os ligamentos foram submetidos a testes de relaxação e foram colocadas strain gauges durante os testes. Os resultados mostraram comportamento viscoelástico, validado pelas strain gauges e com uma perda ao longo do tempo, sendo que, em alguns ligamentos, as perdas chegaram a até 20%, fator este a ser considerado em trabalhos futuros. O presente trabalho dissecou os quatro principais ligamentos do joelho, demonstrando a abordagem posterior que permite manter as suas inserções ósseas e descrevendo a fixação para os ensaios uniaxiais monotônicos, além de ter conseguido extrair o comportamento viscoelástico dos quatro ligamentos do joelho dentro dos limites fisiológicos do joelho.

Efecto de diferentes condiciones y modos de aplicación sobre la fuerza de unión de los adhesivos a la dentinaEffect of different conditions and modes of application on bond strength of adhesives to dentine / Effect of different conditions and modes of application on bond strength of adhesives to dentine

Objective: To evaluate the microtensile bond strength in different dentine conditions (etched-E, non-etched-N, dry-D and wet-W) of a multimode adhesive (Scotchbond Universal-SU, 3M/ESPE) and a total etching adhesive (Ambar-AB, FGM) using a sonic device (Smart Sonic Device-SD, FGM). Material and methods: In this in vitro study, ninety six sound extracted human molars were divided into 12 groups (n=8) according to different dentine conditions and adhesive systems. Enamel was removed and the middle dentine surfaces were polished. Each adhesive system was applied according to the different dentine conditions, and composite resin blocks were incrementally built up and stored for 24 hours. Specimens were sectioned into sticks and bond strength data were analyzed with the Kruskal-Wallis test and Mann-Whitney U tests. Results: No effects of sonic application and were observed. In general, AB showed lower results compared to the SU. E and N conditions did not statistically affect the bond strength of SU groups. Dry dentine presented statistically superior bond strength values when compared to wet dentine for SU/E/SD group. Conclusion: Adhesion of dry dentine with multimode adhesive system may be superior to wet dentine with sonic application. The modes of application had no influence in bond strength of studied adhesives.

Objetivo: Evaluar la resistencia de la unión microtensil en diferentes condiciones de dentina (grabado-E, sin grabado-N, seco-D y húmedo-W) de un adhesivo multimodo (Scotchbond Universal-SU, 3M/ESPE) y un adhesivo de grabado total (Ambar-AB, FGM) utilizando un dispositivo sónico (Smart Sonic Device-SD, FGM). Material y Métodos: En este estudio in vitro, noventa y seis molares humanos extraídos sanos se dividieron en 12 grupos (n=8) de acuerdo con diferentes condiciones de dentina y sistemas adhesivos. Se eliminó el esmalte y se pulieron las superficies centrales de la dentina. Cada sistema adhesivo se aplicó de acuerdo con las diferentes condiciones de dentina, y los bloques de resina compuesta se acumularon de forma incremental y se almacenaron durante 24h. Las muestras se seccionaron en barras y los datos de resistencia de la unión se analizaron con la prueba de Kruskal-Wallis y la prueba de U de Mann-Whitney. Resultado: No se observaron efectos de la aplicación sónica. En general, AB mostró resultados más bajos en comparación con el SU. Las condiciones E y N no afectaron estadísticamente la fuerza de unión de los grupos SU. La dentina seca presentó valores de fuerza de adhesión estadísticamente superiores en comparación con la dentina húmeda para el grupo SU/E/SD. Conclusión: La adhesión de la dentina seca con un sistema adhesivo multimodo puede ser superior a la dentina húmeda con aplicación sónica. Los modos de aplicación no tuvieron influencia en la resistencia de la unión de los adhesivos estudiados.

Effect of S. mutans biofilm on the hybrid ceramic-resin cement bond strength assessed by different methods

Aim: The purpose of this study was to investigate the biofilm effect on the hybrid ceramic-resin cement bond strength (BS) by comparing two methods. Methods: Teeth were distributed into groups (n=5), according to the resin cement (Maxcem Elite-(MC) or NX3 Nexus-(NX)) and degradation method (24h or 7 days in distilled water; 7 or 30 days incubated with biofilm and 30 days in sterile media). Treated surfaces of Vita Enamic blocks (5x6x7mm) were luted to treated or no treated dentin surfaces and light-cured. After 24h, beams were obtained (1x1x10mm) and stored accordingly. The flexural bond strength (FBS) was assessed by four-point bending test. Additional beams were obtained from new teeth (n=5), stored for 24h or 7 days in distilled water, and submitted to a microtensile bond strength (µTBS) assay. Failure modes were determined by scanning electron microscopy (100X). The flexure strength of the cements (n=10) was assessed by a four-point bending test. Data were analyzed by 1 and 2-ways ANOVA, and Tukey's test (α=0.05). Results: There was no significant difference between the degradation methods for the FBS groups. For the µTBS, the significant difference was as follows: NX 7days > NX 24h > MC 7days = MC 24h. Failure mode was mainly adhesive and mixed, but with an increase of cohesive within cement and pre-failures for the MC groups assessed by µTBS. NX had better performance than MC, regardless of the method. Conclusions: The biofilm had no effect on the materials BS and FBS test was a useful method to evaluate BS of materials with poor performance

Mechanical Properties of Mini-Implants Used in Extra-Radicular Anchorage

ABSTRACT Objective: To evaluate the mechanical properties of mini-implants (MIs) manufactured from stainless steel and compare them with conventional titanium-aluminum-vanadium alloy MIs. Material and Methods: The following groups were formed: G1 (n=24), 8×1.5 mm steel MIs; G2 (n=24), 12×2.0 mm steel MIs; and G3 (n=24), 10×1.5 mm titanium MIs. The 72 MIs were inserted in the infra zygomatic crest region of the maxilla and retromolar trigone in the jaw of 10 pigs. Pull-out, insertion torque, fracture and percussion tests were performed in order to measure the tensile strength, primary stability and fracture strength of MIs. A digital torque gauge was used to measure insertion and fracture torque, a universal mechanical testing machine was used for pull-out testing and a periotest device was used to measure the micromovement of MIs. For morphological and MI component evaluation, scanning electron microscopy (SEM) was performed. D'Agostino & Pearson, Kruskal-Wallis, and Dunn post-hoc and normality tests were used. Results: G2 insertion and fracture torques were significantly higher than G1 and G3 insertion and fracture torques (p<0.05). The pull-out and percussion tests presented similar values among the groups. SEM revealed that the fracture point was predominantly on the fourth thread for steel MIs (G1 and G2) and on the seventh thread for titanium-aluminum-vanadium MIs (G3). Conclusion: The mechanical properties of stainless steel MIs are superior to those of titanium-aluminum-vanadium alloy MIs.

Bond strength of bulk-fill resin composites: the effect of cavity preparation and aging

Aim: Evaluating the resin-dentin bond strength of Class II conventional and bulk-fill composite restorations, using different cavity sizes before and after aging. Methods: Seventy-five human molars were distributed into groups according to the buccolingual width of the cavities, conservative (n=25) and extended (n=50). They were divided according to the restorative material: conventional (Z100/control group) or bulk-fill resin composites (Filtek Bulk Fill/FBF; Tetric N Ceram Bulk Fill/TNCBF; Filtek Bulk Fill Flow/FBFF; Surefill SDR flow/SDR). The restored teeth were sectioned on sticks (n=50 per restorative materials + width cavities group), half were stored in Water/Ethanol 75% for 30 days and the other half were submitted to the immediate microtensile bond strength (µTBS) test. Data were analyzed applying the Three-Way Analysis of Variance (ANOVA), Bonferroni test, test t, and Weibull analyses (p<0.05). Results: SDR and FBF presented lower µTBSvalues for extended preparation when compared to the conservative preparation, before aging. After aging, only for the FBFF, a decrease in the µTBSvalues was observed. Comparing the µTBSvalues, before and after aging, the SDR demonstrated lower µTBSvalues after aging when the conservative cavity was used. A decrease in the µTBSvalues was observed for the Z100, the FBF and, the FBFF, after aging, when the extended cavity was used. Conclusion: The effect of cavity preparation and aging on the resin-dentin of Class II is material dependent. Most of the bulk-fill resin composites evaluated presented a similar performance to the conventional resin composites for all the conditions of this study

Influence of diameter on mechanical behavior of morse taper narrow implants

Dental implants could give back function, esthetics and quality of life to patients. The correct choice of the implant, especially in borderline cases, is essential for a satisfactory result. Aim: Thus, the objective of this study was to evaluate the mechanical behavior of Morse taper implants with two different prosthetic interfaces. Methods: Twenty self-locking Morse taper implants, 2.9 mm in diameter (FAC), and 20 Morse taper implants, 3.5 mm in diameter (CM) were divided into two groups (n=10), and submitted to strength to failure test, optical microscopic evaluation of fracture, metallographic analysis of the alloy, finite element analysis (FEA) and strain gauge test. A Student's t test (α = 0.05) was made for a statistical analysis. Results: For the strength to failure test, a statistically difference was observed (p <0.001) between FAC (225.0 ± 19.8 N) and CM (397.3 ± 12.5 N). The optical microscopic evaluation demonstrated a fracture pattern that corroborated with FEA ́s results. The metallographic analysis determined that the implants of the FAC group have titanium-aluminum-vanadium alloy in their composition. In the strain gauge test, there was no statistical difference (p = 0.833) between CM (1064.8 ± 575.04 µS) and FAC (1002.2 ± 657.6 µS) groups. Conclusion: Based on the results obtained in this study, ultra-narrow implants (FAC) should ideally be restricted to areas with low masticatory effort

Análisis biomecánico de la continuación prepatelar del cuádriceps / Biomechanical assessment of the prepatellar quadriceps continuation

OBJETIVO Determinar la resistencia máxima a la tracción (RMT) de la continuación prepatelar del cuádriceps (CPC).MATERIALES Y MÉTODOS Se realizó un estudio en cadáveres humanos. Fueron incluidos diez especímenes, en los cuales se utilizaron los tercios proximal y medial de la cortical anterior de la patela para evaluar las propiedades mecánicas de la CPC. En cada espécimen, se estudió un área de sección transversal de 0,2 cm2 (A1) y 1 cm2 (A2). Se aplicó una carga gradual para determinar la RMT.RESULTADOS La mediana de la RMT en el A1 fue de 232,56 N (rango: 141,23 N a 295,33 N) y en el A2 fue de 335,30 N (rango: 216,45 N a 371,40 N). El incremento en la TMR fue significativo entre las 2 áreas (p = 0,006).CONCLUSIÓN El ignificado clínico de este estudio es que la CPC es un tejido fuerte que puede servir de anclaje seguro para reconstrucciones alrededor de la patela. Un área relativamente pequeña tolera al menos 140 N y, a medida que crece el área, también aumenta la RMT.

OBJETIVE To determine the ultimate tensile strength (UTS) of the prepatellar quadriceps continuation (PQC). MATERIALS AND METHODS A human cadaveric study was performed. Ten fresh-frozen specimens were used. The proximal and medial thirds of the anterior cortex of the patella were used to assess the mechanical properties of the PQC. In each specimen, transverse section areas measuring 0.2 cm2 (A1) and 1 cm2 (A2) were studied. A gradual load was applied to determine the UTS. RESULTS The median UTS of A1 was of 232.56 N (range: 141.23 N to 295.33 N), and that of A2 was of 335.30 N (range: 216.45 N to 371.40 N). The increment in UTS was significant between the 2 areas (p » 0.006). CONCLUSION The clinical significance of the present study lies in the fact that it shows that the PQC is a strong tissue that can be a safe anchor for reconstruction around the patella. A relatively small area supports at least 140 N, and, as the area grows, the UTS increases as well.

Comparación de la fuerza de adhesión a dentina de cementos de autograbado vs grabado total / Comparison of bond strength to dentin of self-etching cements vs total etching

Los sistemas cementantes han mejorado notablemente, los objetivos que persiguen los nuevos cementos es que la adhesión sea duradera y conseguir siempre que sea posible una interface cerrada con un sellado perfecto. Se han podido desarrollar nuevas técnicas y nuevos materiales de cementación que han ido perfeccionando la unión del material restaurador al diente. En el presente estudio se compara la fuerza de adhesión a dentina de cementos de autograbado y cementos de grabado total para comprobar los efectos positivos en el grabado de la dentina. Para el estudio se utilizaron dos cementos a base de resina (RelyX U200 Clicker 3M y RelyX Ultimate 3M). Se encapsularon 40 molares en acrílico en dos grupos de 20 muestras para la aplicación de dos sistemas cementantes de autograbado (grupo 1) y de grabado total (grupo 2), respectivamente, se desgastaron hasta descubrir la dentina; siguiendo las especificaciones del fabricante se colocó el cemento en cada grupo, y después se sometieron a pruebas de cizalla en una máquina de ensayo universal Instron. La medida expresada en megapascales (MPa) fue: grupo 1 = 7.5569 y grupo 2 = 12.6444. En este caso fueron analizados dos grupos, tomándose la primera significancia bilateral. Se realiza la prueba en t de Student, con 95% de intervalo de confianza en la diferencia, demostrando así que el cemento RelyX Ultimate 3M tiene mayor fuerza de adhesión que el cemento RelyX U200 Clicker 3M. Nuestra investigación fue factible y llegamos a nuestro propósito, en el cual comprobamos la mayor adhesión de cementos de grabado total, los cuales son sometidos a un previo tratamiento del diente (AU)

Effects of different concentrations of sodium hypochlorite on dentine adhesion and the recovery application of sodium erythorbate / 中南大学学报(医学版)

OBJECTIVES@#Root canal therapy is the most effective and common method for pulpitis and periapical periodontitis. During the root canal preparation, chemical irrigation plays a key role. However, sodium hypochlorite (NaOCl), the widely used irrigation fluid, may impact the bonding strength between dentin and restorative material meanwhile sterilization and dissolving. Therefore, it's important to explore the influence of NaOCl on the adhesion between dentin and restoration materials to ensure clinical efficacy. This study aims to explore the effect of NaOCl on dentine adhesion and evaluate the effect of dentine adhesion induced by sodium erythorbate (ERY), and to provide clinical guidance on dentin bonding after root canal therapy.@*METHODS@#Seventy freshly complete extracted human third molars aged 18-33 years old, without caries and restorations were selected. A diamond saw was used under running water to achieve dentine fragments which were divided into 10 groups with 14 fragments in each group: 2 control [deionized water (DW)±10% ERY] and 8 experimental groups (0.5%, 1%, 2.5%, and 5.25% NaOCl±10% ERY). The dentine specimens in the control group (treated with DW) and the experimental groups (treated with 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl) were immersed for 20 min using corresponding solutions which were renewed every 5 min. The other 5 groups were immersed in 10% ERY for 5 min after an initial washing with DW for 1 min. Then, we selected 4 dentine fragments from all 14 fragments in each group and the numbers and diameters of opening dentinal tubules were observed under scanning electron microscope (SEM). The other 10 dentine fragments from each group were used to make adhesive samples by using self-etch adhesive wand composite resin. All the above adhesive samples were sectioned perpendicular to the bonded interface into 20 slabs with a cross-sectional area of 1 mm×1 mm using a diamond saw under the cooling water, and then the morphology of 10 slabs in each group's bonding interface was observed from aspects of formation of resin tags, depth of tags in dentin, and formation of hybrid layer under SEM. The other 10 slabs of each group's microtensile bond strength and failure modes were also analyzed.@*RESULTS@#Among the 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules gradually increased with the rise of concentration of NaOCl solution (all P<0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules increased after using ERY, but without significant difference (all P>0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, the scores of formation of resin tags under SEM gradually increased with the increase of concentration of NaOCl solution, while the score in the 5.25% NaOCl group decreased significantly compared with the score of the 2.5% NaOCl group (P<0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (all P>0.05). The scores of length of the tags under SEM in the 5.25% NaOCl group was significantly higher than the scores of DW, 0.5% NaOCl, and 1% NaOCl groups (all P<0.05), and it was also higher than the score of the 2.5% NaOCl group, but without significant difference (P>0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (P>0.05). The scores of formation of hybrid layer under SEM in the 2.5% NaOCl and 5.25% NaOCl groups significantly decreased compared with the score of the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). Microtensile bond strength was greater in the 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, but lower in the 5.25% NaOCl group than that in the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). The incidence of type "Adhesive" of failure modes in the 5.25% NaOCl group was significantly higher than that in other groups (all P<0.05), while the incidence of type "Adhesive" in the 5.25% NaOCl+10% ERY group was lower than that in the 5.25% NaOCl group (P<0.05).@*CONCLUSIONS@#The bonding strength to dentine increases with the increase of NaOCl concentration when the concentration lower than 2.5%; whereas it is decreased at a higher concentration (such as 5.25%). 10% ERY has a definite recovery effect on attenuated bonding strength to 5.25% NaOCl-treated dentine.

Effect of hydroxyapatite based agents on the bonding properties of universal adhesives / 中华口腔医学杂志

Objective: To study the effect of hydroxyapatite (HA) based agents on the bonding properties of universal adhesive with different application modes, and to provide evidence for the use of adhesives after desensitization treatment. Methods: Sixty impacted third molars were extracted and selected (acquired from Department of Oral and Maxillofacial Surgery, College of Stomatology, Xi'an Jiaotong University). Four third molars were used to prepare 1 mm thick dentin disks and treated with 1% citric acid to simulate sensitive tooth models. The dentin surfaces were observed by scanning electron microscope (SEM) after treating with no desensitization (control group), desensitized by HA based toothpaste Biorepair and Dontodent Sensitive respectively (desensitizing toothpaste A group and B group), or HA paste treatment (desensitizing paste group ) (n=2 per group). The remaining teeth were selected to expose the mid-coronal dentin and establish dentin sensitivity models. Then, the specimens were divided into 4 former groups and received corresponding treatment. Each group was randomly divided into 2 subgroups, and intermediately strong universal adhesive (G-Premio Bond) was applied on the desensitized dentin by either etch-and-rinse mode or self-etch mode. Resin-dentin slice specimens (n=4 per subgroup), microtensile specimens (n=20 per subgroup) and slice specimens (n=6 per subgroup) were prepared. The microstructure and nanoleakage of the adhesive interfaces were observed by scanning electron microscopy (SEM). The microtensile strength (bond strength) and fracture mode were tested and recorded. The water permeability of the adhesive interface was observed by laser scanning confocal microscopy (LSCM). Results: SEM showed that desensitizing toothpaste and desensitizing paste could partially or entirely occlude most of the dentin tubules. For the etch-and-rinse mode, the bond strength of specimens treated with toothpaste A [(40.98±4.60) MPa], toothpaste B [(40.89±4.64) MPa] and HA paste [(41.48±3.65) MPa] was significantly higher than that of the control group [(38.58±4.28) MPa] (F=3.89,P<0.05). There was no statistically significant difference in bond strength among the 4 subgroups for self-etch modes (F=0.48,P>0.05). After desensitization, the bond strength of the control group and desensitizing groups in the self-etch mode was significantly higher than that in the etch-and-rinse mode (P<0.05). The overall fracture modes were mixed failure and interfacial failure in the control group and desensitizing groups. SEM showed speckled silver-stained particles deposited along the bottom of the hybrid layer on the bond interface of etch-and-rinse mode, and there were few silver-stained particles deposited on the bond interface of self-etch mode. LSCM showed continuous linear penetration in the hybrid layer of etch-and-rinse mode subgroups and discontinuous linear penetration in the hybrid layer of self-etch mode subgroups. Conclusions: HA based desensitizers have no adverse effect on the bond strength of intermediately strong universal adhesive and show good bonding performance accompanied with the self-etch mode.

Effect of a novel radio-frequency atmospheric-pressure glow discharge plasma jet treatment on crosslinking of dentin collagen / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of a noval radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma jet on crosslinking of dentin collagen.@*METHODS@#(1) Twenty intact third molars were collected. The middle dentin discs were prepared for each tooth by low-speed water-cooled Isomet saw, and then immersed in 10% (mass fraction) H3PO4 solution for 16 h to obtain fully demine-ralized dentin collagen. The twenty dentin discs were then randomly divided into five groups. The control group was untreated while the four experimental groups were treated by plasma jet with gas temperature of 4 ℃ for different times (20 s, 30 s, 40 s, and 50 s). The structure and crosslinking degree of dentin collagen were characterized by attenuated total reflection-Fourier transform infrared spectroscopy. The surface morphology of demineralized dentin was observed by scanning electron microscope, and the microstructure was observed by transmission electron microscope. (2) Fourty non-caries third molars were collected to prepare 5 g fine dentin powder, then completely demineralized with 10% H3PO4 solution. The control group was untreated, while the four experimental groups were treated by plasma jet for 20 s, 30 s, 40 s and 50 s. The crosslinking degree of each group was determined by ninhydrin colorimetric method. (3) Forty intact third molars were collected to obtain dentin strips. Only two central symmetrical dentin strips (nasty 80) were taken from each tooth and immersed in 10% H3PO4 solution for 16 h to obtain fully demineralized dentin collagen. Eighty dentine collagen fiber strips were randomly divided into five groups. The control group was untreated and the axial surfaces of dentin collagen fiber strips in the expe-rimental groups were treated with the plasma jet for 20 s, 30 s, 40 s and 50 s. The ultimate tensile strength of dentin was measured by universal mechanical machine.@*RESULTS@#(1) The surface morphology of demineralized dentin observed by scanning electron microscope showed that the network structure of collagen fibers on the surface of demineralized dentin treated with the plasma jet for 20 s, 30 s and 40 s could maintain the uncollapsed three-dimensional structure, and part of the microstructure was destroyed after plasma jet treated for 50 s. After being treated by plasma jet for 20 s, 30 s and 40 s, the three-dimensional structure was uncollapsed, and the typical periodic transverse pattern of natural type Ⅰ collagen fiber could be seen. The results of infrared spectra showed that the secondary conformation of dentin collagen fibers was the same as that of the control group after being treated with the plasma jet, and the intensity of amide band was significantly increased after being treated for 30 s and 40 s. (2) The results of ninhydrin crosslinking test showed that the crosslinking ratio of dentin collagen treated by plasma jet for 30 s and 40 s was the highest, and the difference was statistically significant (P < 0.05). (3) The results of dentin ultimate tensile strength showed that the control group was (1.67±0.24) MPa, and the plasma jet treated 20 s, 30 s, 40 s and 50 s groups were (4.21±0.15) MPa, (7.06±0.30) MPa, (7.32±0.27) MPa, and (6.87±0.17) MPa, which were significantly different from that of the control group (P < 0.05).@*CONCLUSION@#The novel RF-APGD plasma jet treatment can promote the crosslinking degree of demineralized dentin collagen and improve their ultimate tensile strength.

The influence of prophylaxis with amino acid glycine powder and sodium bicarbonate jet on the bond strength of dental enamel / A influência da profilaxia com aminoácido glicina em pó e jato de bicarbonato de sódio na resistência de união do esmalte dentário

Aim: To compare the influence of prophylaxis with sodium bicarbonate and amino acid glycine powder on the bond strength of bovine teeth enamel and on the properties of two adhesive systems. Methods:Thirty-six extracted bovine incisors were randomly divided into six groups (n = 6) according to the prophylactic treatment received: no prophylactic treatment (NT), sodium bicarbonate powder (SB), and glycine powder (GL). Each group was subdivided into 2 groups based on what adhesive systems were used: conventional system (A) and universal system (B). Composite resin was applied on the buccal surface of the teeth in a block measurement 8x8x6 mm. The specimens were cut to obtain beams measuring 1.0 x 1.0 mm and were subjected to microtensile bond strength tests. Results were compared using two-way ANOVA (p ≤ 0.05). Results: The GLA group obtained the highest bond strength value for the conventional adhesive (18.97 MPa), but the GLB group obtained a lower strength value than the SBB group (GLB: 21.05 MPa and SBB: 22.29 MPa) (p < 0.05). Conclusions: Cleaning of the enamel surface increases the adhesive properties of restorative materials, and the bond strength was more effective in the group that received glycine prophylaxis and the conventional adhesive system.

Objetivo:Comparar a influência da profilaxia com bicarbonato de sódio e ClinproProphy ™ na resistência de união do esmalte de dentes bovinos e nas propriedades de dois sistemas adesivos.Métodos: Trinta e seis incisivos bovinos extraídos foram divididos aleatoriamente em 6 grupos (n = 6), cada um de acordo com o tratamento profilático recebido: nenhum tratamento profilático (NT), bicarbonato de sódio em pó (SB), glicina em pó (GL). Cada grupo foi subdividido em 2 grupos com base nos sistemas adesivos utilizados: sistema convencional (A) e sistema universal (B). A resina composta foi aplicada na superfície bucal dos dentes em um bloco de 8x8x6 mm. As amostras foram cortadas para obter blocos medindo 1,0 x 1,0 mm e submetidas a testes de resistência de união por microtração. Os resultados foram comparados usando o teste two-way ANOVA (p ≤ 0,05). Resultados: O grupo GLA obteve o maior valor de resistência de união para o adesivo convencional (18,97 MPa), mas o grupo GLB obteve um valor de resistência menor que o grupo SBB (GLB: 21,05 MPa e SBB: 22,29 MPa) (p < 0,05). Conclusão: A limpeza da superfície do esmalte aumenta as propriedades adesivas dos materiais restauradores, e a resistência adesiva foi mais eficaz no grupo que recebeu profilaxia com glicina e sistema adesivo convencional.

Effect of Chelating Agents on Push-Out Bond Strength of NeoMTA Plus to Root Canal Dentin

ABSTRACT Objective To evaluate and compare the effect of 17% Ethylenediaminetetraacetic Acid (EDTA), 9% Etidronic acid (HEDP), and 7% Maleic acid (MA) on the push-out bond strength of NeoMTA Plus sealer to the coronal, middle, and apical thirds of root canal dentin. Material and Methods Forty single-rooted human maxillary central incisors were selected and decoronated to 12 mm long root fragments. Working length was established and root canals were then enlarged up to rotary Protaper F3. After each instrumentation, the root canal was irrigated with 2.5% NaOCl. For the final irrigation regimen, the specimens were divided into 4 groups (n=10) and treated with EDTA, HEDP, MA or Saline. Root canals were coated with NeoMTA Plus sealer, and obturation was done with single cone obturation technique. Subsequently, three horizontal sections were taken from the coronal, middle and apical thirds of each specimen, and POBS was measured using a universal testing machine. The type of bond failures was assessed under a stereomicroscope. Statistical analysis was done with One-way ANOVA with Tukey's Post hoc analysis. Results MA and EDTA showed the highest POBS. There was no significant difference in bond strength between MA and EDTA (p>0.05). HEDP and Saline showed lower POBS. Among all the four groups, the coronal third showed the highest values, followed by middle and apical thirds. Conclusion The type of chelating agent used during the root canal treatment significantly affects the bond strength of NeoMTA Plus to the root canal dentin.

Resistencia a la fuerza de tracción de espigos de fibra de vidrio y anatomizados / Tensile bond strength of fiberglass and anatomized posts

Introducción: Es frecuente el desprendimiento de los espigos de fibra de vidrio por pérdida de adhesión cuando son sometidos a las fuerzas masticatorias. Objetivo: Comparar in vitro la resistencia a las fuerzas de tracción de espigos de fibra de vidrio y anatomizado con un mismo cemento. Métodos: Estudio in vitro, de tipo experimental. Se seleccionaron 20 premolares extraídos por motivos ortodónticos que fueron distribuidos aleatoriamente en dos grupos. Se les realizó el tratamiento de conductos por un especialista, la preparación fue manual y la técnica de obturación por condensación lateral. Los dientes fueron preparados para, en forma estándar, recibir el espigo de fibra de vidrio y anatomizados con resina. Para ambos grupos la cementación siguió el protocolo sugerido por el fabricante de Allcem Core® (cemento dual). Los especímenes fueron troquelados en acrílico de autocurado. Para luego ser sometido a fuerza de tracción vertical en la máquina de pruebas de materiales (Instrom©). Resultados: En el grupo de dientes con espigos anatomizados se obtuvo una media de 31 Kg/F, postes de fibra de vidrio 12,47 Kg/F. Según las pruebas de Shapiro-Wilk, las muestras presentaron distribución normal (p > 0,05). Se contrastó la hipótesis con la prueba de t de Student y se encontró diferencia estadística altamente significativas entre los grupos (p = 0,001) Conclusiones: Existe una mayor resistencia a la tracción vertical en los espigos anatomizados(AU)

Introduction: Fiberglass posts often fall off their position due to loss of adhesive capacity when they are subjected to masticatory force. Objective: Compare in vitro the tensile bond strength of fiberglass and anatomized posts cemented with the same adhesive material. Methods: An in vitro experimental study was conducted. A selection was made of 20 premolars extracted by orthodontic indication which were then randomly distributed into two groups. The premolars underwent root canal treatment by a specialist. The preparation was manual and sealing was performed by lateral condensation. The teeth were prepared in the standard manner to receive the fiberglass and resin-anatomized posts. In both groups' cementation followed the protocol suggested by the manufacturer of Allcem Core® (dual cement). The specimens were stamped in self-curing acrylic. Next, they were subjected to vertical tensile strength in an materials testing machine (Instrom©). Results: The mean values obtained were 31 kg/F for teeth with anatomized posts and 12.47 kg/F for fiberglass posts. According to Shapiro-Wilk tests, the samples exhibited a normal distribution (p > 0.05). The hypothesis was contrasted with Student's t test, obtaining a highly significant statistical difference between the groups (p = 0.001). Conclusions: Vertical tensile bond strength is greater in anatomized posts(AU)

Resistencia de diferentes implantes y componentes sometidos a sobre torque. Estudio in-vitro / Resistance of different implants and components subjected to high torque. An in vitro study

Objetivo: Describir las fallas en diferentes sistemas de implantes al ser sometidos a fuerzas de torsión creciente, de- terminar el torque en el cual aparece un daño medible en el implante o alguno de sus componentes y especificar la falla más frecuente. Materiales y métodos: Se realizó un estudio experi- mental in vitro. Se utilizaron 88 implantes agrupados según diseño y marca comercial (Federa, Rosterdent, Biomet 3i, Tree-Oss, B&W, ML) en 11 grupos de 8 implantes cada uno. Éstos fueron inmovilizados en acrílico y fijados en una pren- sa. Se aplicó una fuerza de torsión creciente con torquímetro de precisión digital hasta la aparición de alguna falla en el implante o sus componentes. Se registró el torque en el que se produjo la falla. Se realizó estadística descriptiva para el análisis de datos. Resultados: El 100% de los implantes o alguno de sus componentes mostraron una falla detectable al ser sometidos a fuerzas de torsión creciente (rango de torque: 83,5 Ncm ­im- plante con conexión cono morse 8 grados­ a 384 Ncm ­implan- te de conexión interna sin montar­). El torque promedio más bajo en el que aparecieron los daños fue 103,75 (±8,08) Ncm para implantes de conexión interna tipo cono morse, mientras que el más alto fue 279,87 (±89,73) Ncm para implantes de conexión interna sin montar. La falla más frecuente (28,4%) fue la fractura del tornillo del portaimplante y falseo del hexá- gono externo simultáneamente. Conclusión: Las fallas detectables a fuerzas de torsión creciente ocurrieron entre 83,5 Ncm y 384 Ncm. La falla rei-terada fue la fractura del tornillo del portaimplante y falseo del hexágono simultáneamente (AU)

Aim: To describe the failures in different implant sys- tems when subjected to increasing torsional forces, deter- mine the torque at which measurable damage occurs to the implant or one of its components, and determine the most frequent failure. Materials and methods: This was an experimental in vitro study. A total 88 implants were used, grouped accord- ing to design and trademark (Federa, Rosterdent, Biomet 3i, Tree-Oss, B&W, ML) into 11 groups of 8 implants each. The implants were immobilized in Duralay acrylic and fixed in a vice. Increasing torsional force was applied with a digital pre- cision torque wrench until the occurrence of any failure in the implants or their components. The torque at which the failure occurred was recorded. Descriptive statistics were performed for data analysis. Results: 100% of the implants or any of their compo- nents showed a detectable failure when subjected to increas- ing torsional forces (force range: 83.5 Ncm in an implant with 8-degree Morse taper connection to 384 Ncm in an implant with unmounted internal connection). The lowest average torque at which damage occurred was 103.75 (±8.08) Ncm for conical implants with Morse internal connection, while the highest was 279.87 (±89.73) Ncm for implant with unmounted internal connection. The most frequent failure (28.4%) was fracture of the implant retaining screw and distortion of the external hexagon simultaneously (AU)

Effect of different concentrations of green tea extract solutions on bonding durability of etchand- rinse adhesive system to caries affected dentin

Aim: The in vitro study evaluated the effect of different concentrations of green tea extract solution (GT) on the bonding durability of etch-and-rinse adhesive system to caries dentin affected (CAD). Methods: Dentinal surfaces of human third molars were polished and submitted to a microbiological caries induction protocol for 14 days. After removal of the infected dentin layer, the samples were randomly divided into 4 groups (n= 10), according to the concentration of GT solution applied in CAD, after acid etching: 0.05%; 0.2%; 2% and NT (no treatment ­ control). After application of a etch-and-rinse adhesive system (Adper Single Bond 2, 3M ESPE), composite resin restorations were performed on the dentin. After 24 hours, the resin-dentin blocks were sectioned 1mm2 specimens, which were subjected to the microtensile test immediately or after 6 months of storage in water. Data were submitted to two-way ANOVA for randomized blocks and Tukey test (α= 5%). Results: There was no effect of double interaction (p= 0.934). The application of 0.2% GT promoted a statistically significant increase in dentin bond strength values in comparison to the condition where GT was not used (p=0.012). There was a significant decrease of bond strength after 6 months of storage, regardless of dentin pretreatment (p = 0.007). The G test identified that there was no statistical difference regarding failure mode (p= 0.326). Conclusion: The concentration of 0.2% improved the bond strength of an etch-and-rinse adhesive system to caries affected dentin, however, none of dentin pretreatments could prevent the decrease in bond strength over time

CHX stabilizes the resin/demineralized dentin interface

Abstract The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) on microtensile bond strength (µTBS) between an adhesive system and under 3 dentin conditions. For that, this study evaluated the adhesive interface at initial, after 6 months and 1 year of storage. Forty-eight human third molars were prepared and randomly divided into 3 groups, according to dentin substrates: sound dentin (Sd), caries-infected dentin (Ci) and caries-affected dentin (Ca). The groups were subdivided into two according to the dentin pre-treatment: application of 2% CHX or without pre-treatment (control). The dentin surfaces were etched with 35% phosphoric acid gel and bonded with Adper Single Bond 2 (3M ESPE) adhesive system according to manufacturer's instructions. Subsequently, the specimens were stored in deionized water at 37°C for 24h, 6 months and 1 year. Two additional teeth were used to analyze the bonding interfaces by SEM. Data was submitted to three-way ANOVA in a split plot design and Tukey's test (α = 0.05). The results showed that Ci decreased µTBS values when compared to Ca and Sd, regardless storages time or treatment. Stored samples for 6 months and 1 year decreased the µTBS for the control group, but no difference was found between storages time for the CHX group. As a conclusion, the 2% CHX application after etching showed improved dentin bond strength in the storage time, regardless of the substrates evaluated.

Resumo O objetivo deste estudo foi avaliar o efeito do digluconato de clorexidina 2% (CHX) na resistência de união à microtração (µTBS) entre um sistema adesivo e sob 3 condições de dentina. Para tanto, este estudo avaliou a interface adesiva no início, após 6 meses e 1 ano de armazenamento. Quarenta e oito terceiros molares humanos foram preparados e divididos aleatoriamente em 3 grupos, de acordo com os substratos dentinários: dentina hígida (Dh), dentina infectada por cárie (Di) e dentina afetada por cárie (Da). Os grupos foram subdivididos em dois de acordo com o pré-tratamento: aplicação de CHX 2% ou sem pré-tratamento (controle). As superfícies da dentina foram condicionadas com gel de ácido fosfórico a 35%, em seguida, utilizou-se o sistema adesivo Adper Single Bond 2 (3M ESPE) de acordo com as instruções do fabricante. Posteriormente, os corpos-de-prova foram armazenados em água deionizada a 37°C por 24h, 6 meses e 1 ano. Dois dentes adicionais foram usados ​​para analisar as interfaces de união no MEV. Os dados foram submetidos a ANOVA três fatores em esquema de parcela subdividida e ao teste de Tukey (α = 0,05). Os resultados mostram que a Di diminuiu os valores de µTBS quando comparado as Da e Dh, independente do tempo de armazenamento ou tratamento. Amostras armazenadas por 6 meses e 1 ano diminuíram a µTBS para o grupo de controle, mas nenhuma diferença foi encontrada entre o tempo de armazenamento para o grupo CHX. A aplicação de CHX 2% após o condicionamento apresentou melhora na resistência de união à dentina no tempo de armazenamento, independente dos substratos avaliados.

Evaluation of tensile strength after insertions andremovals of abutments on frictional Morse taper implants / Evaluación de la Resistencia a la Tracción Después de la Inserción y Extracción de Pilares en Implantes de Cono de Fricción Morse

This study aimed to evaluate possible changes in final retention after nine sequences of insertion and removal (SIR) of a frictional Morse taper implant/abutment system, evaluating the force required for dissociating this set between sequences, and verifying possible deformations in the implant heads. Ten implants, 13 mm long and 3.3 mm in diameter, were coupled to a universal mechanical testing machine. Ten anti-rotational abutments, 13 mm long and 3.5 mm in diameter, were connected to the implants parallel to the long axis, using an instrument called beat-connection, and subjected to tensile tests and SEM analysis. The results were analyzed using the Kruskal-Wallis test with Dunn's post-test, and the significance level was set at 5 %. There was no statistically significant difference in final retention among the nine SIRs evaluated. The force needed to uncouple the abutment from the implant increased as SIRs were performed on all ten implants, and an increase of 29.03 % was observed in the ninth SIR compared to the first SIR. After SEM analysis, no significant deformations, fractures, or cracks were observed in the implant heads.

Este estudio tuvo como objetivo evaluar los posibles cambios en la retención final después de nueve secuencias de inserción y extracción (SIR) de un sistema de implante / pilar de cono de fricción Morse, evaluando la fuerza necesaria para disociar este conjunto entre secuencias y verificando posibles deformaciones en las cabezas de los implantes. Se acoplaron diez implantes, de 13 mm de largo y 3,3 mm de diámetro, a una máquina universal de ensayos mecánicos. Se conectaron a los implantes en paralelo al eje largo diez pilares antirrotacionales, de 13 mm de largo y 3,5 mm de diámetro, mediante un instrumento llamado beat-connection, y se sometieron a pruebas de tracción y análisis SEM. Los resultados se analizaron mediante la prueba de Kruskal-Wallis con la prueba posterior de Dunn, y el nivel de significancia se estableció en 5 %. No hubo diferencias estadísticamente significativas en la retención final entre los nueve SIR evaluados. La fuerza necesaria para desacoplar el pilar del implante aumentó a medida que se realizaban SIR en los diez implantes, y se observó un aumento del 29,03 % en el noveno SIR en comparación con el primer SIR. Después del análisis SEM, no se observaron deformaciones, fracturas o grietas significativas en las cabezas de los implantes.