Shear bond strength of orthodontic metal brackets to aged composite using three primers

This study aimed to assess the effect of surface preparation with sandblasting and diamond bur along with the use of three primers on shear bond strength (SBS) of metal brackets to aged composite. In this in vitro, experimental study, 60 Filtek Z250 composite discs were fabricated (10×2mm), immersed in distilled water for 24 hours and subjected to 5000 thermal cycles. They were randomly divided into two groups (n=30) of sandblasting with aluminum oxide particles for 10 seconds and surface roughening with bur. Each group was randomly divided into three subgroups (n=10) for use of Transbond XT, Assure Plus and Composite Primer. Metal brackets were bonded and the samples were stored in distilled water for 24 hours followed by 2000 thermal cycles. The SBS of brackets was measured and the adhesive remnant index (ARI) score was calculated. The data were analyzed by one-way ANOVA, t-test and Chi square test. The difference in the mean SBS was not significant among the six subgroups. All combinations of primers and surface preparation methods provided adequately high SBS between brackets and aged composite surfaces. Considering the ARI scores, surface roughening by bur is superior to sandblasting

Dentin bonding agent with improved bond strength to dentin through incorporation of sepiolite nanoparticles

The study aims to investigate the effect of incorporation of sepiolite nanoparticles on the microtensile bond strength of an experimental dentin bonding to the human dentin. The sepiolite nanoparticles were incorporated into an experimental methacrylate-based dentin bonding system in concentrations of 0.0, 0.2, 1.0, 2.0, and 5.0 weight percents. The specimens were then ultrasonicated to finely disperse the nanoparticles in the adhesive matrix. The coronal enamel of 30 intact human premolars was cut to expose dentin. Having etched, rinsed, and blot dried the experimental bonding agents were applied to dentin surface. Adper Single Bond was used as control group according to the manufactor?s instruction. Then all the teeth were built up by composite and sectioned in stick form for microtensile test. The fracture surface was observed using SEM. The data were analyzed by ANOVA and Tukey?s post-Hoc test. The results indicated that the incorporation of the nanofiller, improved the bond strength to dentin with the highest values obtained at 1 w% sepiolite nanoparticle content. Sepiolite nanoparticles can be considered as novel fillers to improve the mechanical properties of dentin bonding agents

Effect of rinsing time and surface contamination on the bond strength of silorane-based and dimethacrylate-based composites to enamel

The aim of this study was to assess whether saliva contamination and rinsing time for 15, 30, and 60 seconds, affects the shear bond strength of silorane and methacrylate-based composites to enamel. Two light cure resin, P60 (3M ESPE) and Filtek LS Silorane were tested. 120 sound premolars were randomly divided into four groups of 30 teeth based on composite type with or without saliva contamination after etching and rinsing. Each group was further divided into three subgroups according to their rinsing time. Then a cylinder of the composite was bonded to the enamel and Shear bond strength was assessed. To determine the failure mode, the bonded surfaces were then observed under SEM. In addition, the DC of each group was measured at pH levels of 4 and 7 using FTIR spectroscopy. The data were analyzed with one-way ANOVA and post hoc analysis followed by Fisher?s least significant difference. The bond strength of the non-contaminated methacrylate group was significantly higher than the other groups (p< 0.0001). In addition, there was no significant deference between the methacrylate subgroups. In the silorane groups, the shear bond strength was higher in the rinsing time of 15 seconds. Failure pattern was mainly adhesive. The DC of the Methacrylates had no significant difference at pH 4 and pH 7, but was significantly higher than that of siloranes (p< 0.0001). While the DC of the siloranes at pH 4 was significantly higher than at pH 7 (p< 0.0001). Saliva contamination in both composites reduces bond strength. Increasing rinsing time in Methacrylates proves ineffective. In non-contaminated siloranes, excessive rinsing time reduced bond strength. The best-recommended rinsing time for both composite is 15 seconds

Factores influyentes en el periodo de erupción del primer diente primario.

Introduction: Deciduous teeth play an important role in proper growth. Tooth eruption is a complicated process in which different mechanisms are involved. Early or delayed tooth eruption depends on different factors, with the impact of some already established. There are apparent controversy regarding the effect of some factors on time of the first deciduous tooth eruption among the conducted studies. The current study aimed to evaluate factors affecting the time of the first deciduous tooth eruption. Materials and Methods: One hundred and sixty eligible infants referring to the healthcare centers of Tabriz, Iran, were randomly selected; the demographic data including weight and height at birth, head circumference, mother’s age and level of education, birth rank in the family and type of feeding were recorded, in addition to the time of the first deciduous tooth eruption. Data were analyzed using SPSS version 21 by ANOVA and t test.Results: Out of 54.1% female and 45.9% male participating infants, 78.3% had normal weight at birth. Results showed a significant relationship between weight at birth and timing of the first deciduous tooth eruption, among the evaluated factors. Conclusions: Although no significant relationship was observed between gender, type of feeding, mother’s level of education and birth rank in the family, and time of the first deciduous tooth eruption, there was a significant relationship between the weight at birth and the timing of the first deciduous tooth eruption. Infants with higher or lower abnormal weight at birth had delayed deciduous tooth eruption.Introducción: los dientes primarios juegan un papel importante en el crecimiento adecuado. La erupción dental es un proceso complexo en el que intervienen diferentes mecanismos. La erupción temprana o tardía de los dientes depende de diferentes factores, con el impacto de algunos ya establecido. Existe controversia entre los estudios realizados con respecto al efecto de algunos factores que afectan la erupción del primero diente primario. El presente estudio tuvo como objetivo evaluar los factores que afectan el periodo de erupción del primero diente primario o temporal. Materiales y métodos: Ciento sesenta bebés referidos a los centros de salud de Tabriz, Irán, fueron seleccionados al azar; Se registraron los datos demográficos, incluidos el peso y la estatura al nacer, la circunferencia de la cabeza, la edad y el nivel de educación de la madre, el rango de nacimiento en la familia y el tipo de alimentación, además del momento de la primera erupción del diente primario. Los datos fueron analizados por ANOVA y t-test utilizando SPSS versión 21. Resultados: de los lactantes participantes (54,1% femeninos, 45,9% masculinos) el 78,3% tenía peso normal al nacer. Entre los factores evaluados, los resultados mostraron una relación significativa entre el peso al nacer y el momento de la erupción del primero diente primario. Conclusiones: aunque no se observó una relación significativa entre sexo, tipo de alimentación, nivel de educación de la madre y rango de nacimiento en la familia, y el period de erupción del primero diente primario, hubo una relación significativa entre el peso al nacer y el momento de la primera erupción dental decidua. En los lactantes con peso anormal al nacer se había retrasado la primera erupción de los dientes primarios

Casein phosphopeptide-amorphous calcium phosphate effects on brackets shear bond strength and enamel damage

The aim of study was to evaluate the application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride regarding their effect on the shear bond strength (SBS), bond failure pattern of brackets using the adhesive remnant index (ARI) and assessing the quality of enamel surface using the enamel damage index (EDI). Sixty extracted premolar teeth were randomly divided into four groups regarding pretreatment application of CPP-ACP and fluoride. Brackets were bonded using the conventional method. Specimens were thermocycled for 1000 cycles and were subsequently tested for the SBS in a universal testing machine. After debonding, the teeth were examined under a stereomicroscope to evaluate the ARI. Then, The EDI was assessed using a scanning electron microscope (SEM). Data were analyzed using ANOVA and the Chi-square test. Evaluation of SBS, ARI and EDI scores showed no significant difference among the study groups. However, a correlation was found between the ARI and EDI scores, indicating that with more adhesive remnants on enamel surface, enamel damage was lower. The use of CPP-ACP and fluoride can be considered a prophylactic application since these agents did not compromise bracket bond strength although they did not reduce iatrogenic damage to the enamel

Efficacy of a Novel Bioactive Glass-Polymer Composite for Enamel Remineralization following Erosive Challenge

INTRODUCTION: Dental caries is the most common cause of tooth loss. However, it can be stopped by enhancing remineralization. Fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) are among the most important remineralizing agents. Recent studies have used bioactive glass as a remineralizing agent in different forms. This study aimed to assess the efficacy of a composite paste (prepared by mixing urethane polypropylene glycol oligomer with bioactive glass powder for easier application). MATERIALS AND METHODS: Enamel disks were cut out of the buccal surface of extracted sound third molars. The samples were randomly divided into 3 groups of 15 and underwent Vickers microhardness test. X-ray diffraction (XRD) and field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FESEM/EDS) were performed. All samples were immersed in a demineralizing solution for 14 days. The tests were then repeated. Next, bioactive glass paste, fluoride, and CPP-ACP were applied on the surface of the samples and they were then stored in an artificial saliva for 14 days. The tests were repeated again. The microhardness values were analyzed using repeated measures ANOVA followed by one-way ANOVA and Tukey's post hoc test (P < 0.05). RESULTS: The microhardness of the bioactive glass group was significantly higher than that of other groups (P < 0.05). XRD revealed an enamel structure more similar to sound enamel in the bioactive glass and CPP-ACP groups compared with the fluoride group. FESEM/EDS revealed higher hydroxyapatite deposition in the bioactive glass group than in the other two groups. CONCLUSIONS: All three remineralizing agents caused remineralization, but bioactive glass paste had a greater efficacy

Comparing the Effect of Assure Plus and Transbond XT Bonding on Shear Bond Strength and Adhesive Remnant Index in Metal Brackets Bonded to Enamel

Background and purpose: Bracket debonding is a major problem during orthodontic treatment. This research aimed at studying shear bond strength (SBS) and adhesive remnant index (ARI) in two bonding systems (Assure Plus (adhesion booster) and control). Materials and methods: In this vitro trial, premolars (n=90) were divided into two groups. The brackets were bonded either with Transbond XT or Assure Plus. After aging and thermocycling, SBS was measured by universal testing machine. ARI scores were recorded using stereomicroscope. Data were analyzed in SPSS V20 applying One-way and two-way analysis of variance, Tukey test, and KruskalWallis test. Spearman correlation coefficient was calculated to determine any correlation between bond strength and ARI scores. Results: Aging had no significant effect on SBS in Assure Plus samples (P=0.252) but in Transbond XT, samples with 6 months of aging had significantly lower bond strength compared to 24 hours (P=0.001) and 3 months (P=0.000) of aging. There were no significant differences between Transbond XT and Assure Plus when aged for 24 hours (P=0.280) or 3 months (P=0.114) but when aged for 6 months, Assur Plus had significantly higher bond strength (P=0.000). Spearman correlation test showed significant and direct relation between ARI score and SBS (r=0.834, P<0.001). Conclusion: Shear bond strength of Assure Plus was not affected by aging, so it could be useful when higher bond strength is needed for longer period of time

Evaluation of flexural strength, degree of conversion, and demineralization-prevention properties in adjacent tooth structures of an experimental fissure sealant containing nano-calcium-phosphate compounds

Abstract Background The present study aimed to evaluate the flexural strength, degree of conversion, and demineralization-prevention ability of an experimental fissure sealant containing nano-calcium-phosphate compounds. Methods An experimental sealant was formulated using silica and nano hydroxyapatite filler particles. The control group consisted of the DENU Seal (n = 10, each group). The flexural bond strength was evaluated by UTM. DC was evaluated by FTIR. To evaluate the demineralization-prevention ability, Cl V cavities in 10 third molar teeth restored with two sealant products, followed by an acid challenge then the Vickers microhardness test was carried out. Results The mean flexural strength in the commercial group was higher than the experimental group. However, the mean flexural modulus was not significantly different between the two groups. In the experimental group, DC was significantly higher than the commercial group. Adjacent to the interface, the decrease in microhardness in the experimental group was significantly less than the commercial group. However, on the tooth surface, there were no significant differences between the two groups. In the experimental group, the decrease in microhardness at the interface was less than at the tooth surface, however the situation was opposite in the commercial group. Conclusions Incorporating hydroxyapatite into the sealant structure might prevent demineralization, without adverse effects on flexural modulus and degree of conversion