The Effect of CuO Nanoparticles on Antimicrobial Effects and Shear Bond Strength of Orthodontic Adhesives

Statement of the Problem: Orthodontic appliances facilitate microbial plaque accumulation and increase the chance of white spot lesions. There is a need for new plaque control methods independent of patient's cooperation. Purpose: The aim of this study was to determine the effects of incorporating copper oxide (CuO) nanoparticles on antimicrobial properties and bond strength of orthodontic adhesive. Materials and Method: CuO nanoparticles were added to the composite transbond XT at concentrations of 0.01, 0.5 and 1 wt.%. To evaluate the antimicrobial properties of composites containing nanoparticles, the disk agar diffusion test was used. For this purpose, 10 discs from each concentration of nano-composites (totally 30 discs) and 10 discs from conventional composite (as the control group) were prepared. Then the diameter of streptococcus mutans growth inhibition around each disc was determined in blood agar medium. To evaluate the shear bond strength, with each concentration of nano-composites as well as the control group (conventional composite), 10 metal brackets were bonded to the human premolars and shear bond strength was determined using a universal testing machine. Results: Nano-composites in all three concentrations showed significant antimicrobial effect compared to the control group (p< 0.001). With increasing concentration of nanoparticles, antimicrobial effect showed an upward trend, although statistically was not significant. There was no significant difference between the shear bond strength of nano-composites compared to control group (p= 0.695). Conclusion: Incorporating CuO nanoparticles into adhesive in all three studied concentrations added antimicrobial effects to the adhesive with no adverse effects on shear bond strength

Association between mandibular second molars calcification stages in the panoramic images and cervical vertebral maturity in the lateral cephalometric images

Determination of maturation and evaluation of growth potential is extremely important in clinical orthodontics. The purpose of this study was to evaluate the diagnostic performance of the mandibular second molar calcification stages for identification of growth phases. In this cross-sectional descriptive study, samples were derived from panoramic radiographs and lateral cephalograms of 125 subjects (61 males and 64 females) with age ranging from 8 to 17 years and estimates of dental maturity (Demirjian Index [DI]) and skeletal maturity (Cervical vertebral maturation indicators CVMI]) were made. Correlations between DI and CVMI were shown by Spearman?s correlation. The diagnostic performance of the DI for the identification of the growth phase were evaluated using positive likelihood ratios (LHRs), with a threshold of ?10 for satisfactory performance. Correlations between second molar calcification and growth phase were 0.819 for females and 0.805 for males (P-value< 0.0001). LHR ?10 was only observed for the identification of the post-pubertal growth phase for the H stage of the second molar. In spite of the high correlation coefficients between mandibular second molar calcification stages and skeletal maturity, these stages are reliable only for the identification of the post pubertal growth phase

Effect of Saliva Contamination on Microleakage Beneath Bonded Brackets: A Comparison between Two Moisture-Tolerant Bonding Systems

Objectives: This study aimed to evaluate the effects of saliva contamination on the metallic bracket microleakage bonded with two moisture-tolerant bonding systems. Materials and Methods:  Ninety freshly extracted premolar teeth were randomly divided into six groups of 15 with the following treatments: G1 (control): After acid etching, Assure primer and Assure adhesive were applied to non-contaminated enamel surfaces. G2 (contaminated after etching): The etched enamel surface was exposed to saliva, then Assure primer and Assure adhesive were applied. G3 (contaminated after priming): Saliva contamination was done after application of Assure primer. The exact same procedures were applied to groups G4 to G6 except that TIMP primer and Transbond Plus adhesive system were used.   To measure the microleakage score, the teeth were stained with 2% methylene blue for 24 hours, sectioned and examined under a stereomicroscope at ×16 magnification. Data analysis was performed using Fisher’s exact test. Results: In dry conditions, Assure and TMIP were not significantly different in terms of microleakage scores.  All contaminated groups exhibited higher microleakage score at the enamel/adhesive interface compared to the bracket/adhesive interface (P< 0.01). In wet conditions, Assure groups showed higher microleakage at the enamel-adhesive interface compared to the TMIP groups (P<0.05). At the bracket-adhesive interface, the microleakage scores were not significantly different in saliva contaminated groups compared to the controls. Conclusion: Saliva contamination caused greater microleakage at the enamel-adhesive interface compared to the adhesive-bracket interface. Keywords: Orthodontic Brackets; Adhesives; Saliv

Effect of Saliva pH on Shear Bond Strength of Orthodontic Brackets

Objectives: The purpose of this study was to evaluate the effect of salivary pH on the shear bond strength (SBS) of orthodontic brackets to tooth surface. Materials and Methods: Eighty intact premolars were randomly divided into four groups of 20.  After bonding a bracket on each tooth, the groups one to four were stored in artificial saliva at a pH of 3.8, 4.8, 5.8, and 6.8, respectively for two months. The artificial saliva solutions were refreshed weekly. Each tooth was then embedded in an acrylic block so that the crown was exposed and its buccal surface was parallel to the direction of the force during SBS testing. All brackets were debonded using Dartec universal testing machine, and the mean values of SBS in different groups were compared using one-way analysis of variance (ANOVA).  Results: The mean SBS value in group 1 (pH 3.8) was significantly lower than that in other groups (P value0.05). Conclusion: Decreased salivary pH, due to poor oral hygiene, and/or frequent con- sumption of acidic beverages, may be responsible for orthodontic bracket bond fail- ure

Computerized Analysis of Digital Photographs for Evaluation of Tooth Movement

Objectives: Various methods have been introduced for evaluation of tooth movement in orthodontics. The challenge is to adopt the most accurate and most beneficial method for patients. This study was designed to introduce analysis of digital photographs with Auto- CAD software as a method to evaluate tooth movement and assess the reliability of this method. Materials and Methods: Eighteen patients were evaluated in this study. Three intraoral digital images from the buccal view were captured from each patient in half an hour inter- val. All the photos were sent to AutoCAD software 2011, calibrated and the distance be- tween canine and molar hooks were measured. The data was analyzed using intraclass cor- relation coefficient. Results: Photographs were found to have high reliability coefficient (P > 0.05). Conclusion: The introduced method is an accurate, efficient and reliable method for eval- uation of tooth movement

Prediction of Mesiodistal Width of Unerupted Lateral Incisors, Canines and Premolars in Orthodontic Patients in Early Mixed Dentition Period

Objectives: Proper diagnosis and prevention of malocclusion are superior to treatment. Discrepancy between arch length and tooth size in mixed dentition period is a condition requiring timely diagnosis. Estimating the mesiodistal width of unerupted teeth according to the size of erupted ones can lead to earlier diagnosis of malocclusion. On the other hand, the best timing for serial extractions is before the eruption of lateral incisors. The aim of this study was to present prediction formulas for mesiodistal width of unerupted lateral incisors, canines and premolars in an Iranian population based on the width of erupted permanent mandibular central incisors and maxillary first molars. Materials and Methods: A total of 120 dental models (60 males, 60 females) of orthodontic patients between 11-25 years were evaluated in Yazd city. The measurements were made by a digital caliper on the widest mesiodistal width of teeth at the interproximal contacts. Data were analyzed to calculate the prediction equation. Results: The prediction equation in the upper jaw was y=0.57x+10.82 for males, y=0.7x+6.37 for females and y=0.64x+8.46 for both sexes. The equation for the lower jaw was y=0.76x+2.86 for males, y=0.74x+3.53 for females and y=0.77x+2.7 for both sexes. Conclusions: The prediction equations suggested in this study can predict the mesiodistal width of unerupted lateral incisors, canines and premolars in an Iranian population in early mixed dentition period without taking radiographs.

An Evaluation of Dentin’s Effect on the Antifungal Activity of MTA Cements

INTRODUCTION: The aim of this study was to evaluate the effect of dentin on the antifungal activity of gray and white-colored MTA (GMTA, WMTA) using a tube-dilution test. MATERIALS AND METHODS: MTA preparations were tested freshly mixed and after 24h on Candida Albicans (CA). The experiment was performed in 24-well culture plates. Fifty wells were used and divided into four experimental groups (freshly-mixed WMTA, freshly-mixed WMTA plus dentin powder, freshly-mixed GMTA, and freshly-mixed GMTA plus dentin powder) of 10 wells each and control groups of five wells each. Plates of Sabouraud dextrose agar mixed with CA served as positive control and Sabouraud dextrose agar without CA served as negative control. Fresh inoculate of CA was prepared by growing an overnight culture from a stock culture. Aliquots of CA were then taken from the stock culture and plated on the agar compound of the experimental and positive control group. All plates were incubated at 37°C for1h, 24h, and 72h. Growth of fungi was monitored daily by the presence of turbidity. Kruskal-Wallis test was used for statistical analysis. RESULTS: Results showed the inhibitory effect of dentin powder on the antifungal effect of MTA cements during 24h and 72h incubation periods, whereas, there was no significant difference between 1h incubation groups. CONCLUSION: The antifungal effect of freshly mixed MTA cements was decreased in the presence of dentin

In vitro evaluation of microleakage around orthodontic brackets using laser etching and Acid etching methods.

path of microleakage between the enamel and adhesive potentially allows microbial ingress that may consequently cause enamel decalcification. The aim of this study was to compare microleakage of brackets bonded either by laser or acid etching techniques.The specimens were 33 extracted premolars that were divided into three groups as the acid etching group (group 1), laser etching with Er:YAG at 100 mJ and 15 Hz for 15s (group 2), and laser etching with Er:YAG at 140 mJ and 15 Hz for 15s (group 3). After photo polymerization, the teeth were subjected to 500 thermal cycles. Then the specimens were sealed with nail varnish, stained with 2% methylen blue for 24hs, sectioned, and examined under a stereomicroscope. They were scored for marginal microleakage that occurred between the adhesive-enamel and bracket-adhesive interfaces from the occlusal and gingival margins. Data were analyzed with the Kruskal- Wallis test.For the adhesive-enamel and bracket-adhesive surfaces, significant differences were not observed between the three groups.According to this study, the Er:YAG laser with 1.5 and 2.1 watt settings may be used as an adjunctive for preparing the surface for orthodontic bracket bonding

The effect of ovalbumin on orthodontic induced root resorption

Background: This randomized trial was undertaken to investigate the effect of experimentally induced allergy on orthodontic induced root resorption. Materials and Methods: A total of 30 Wistar rats were divided randomly into test and control groups. Starting from the first 3 days, the rats in the test group were injected intra-peritoneally by 2 mg ovalbumin as allergen and 0.5 mg Alume as adjuvant. Afterward only allergen was injected once a week. The control group was injected by normal saline. After 21 days, Wistar immunoglobulin E was measured and peripheral matured eosinophil was counted. A total of 50 g nickel-titanium closed coil spring was ligated between right incisor and first molar. All animals were sacrificed after 14 days. The mesial root of the right and left first molar was dissected in a horizontal plane. The specimens were divided into four groups considering whether force and/or ovalbumin was applied or not. Root resorption was measured and compared among these groups. Repeated measures analysis of variance (ANOVA), and Bonferoni tests were used to analyze the data. The level of significance was determined at 0.05. Results: In general, the differences were insignificant (P > 0.05). As the only exception, the group in which both ovalbumin and force were applied had significantly more root resorption than the group in which neither force nor ovalbumin was applied (P < 0.001). Conclusion: Allergy may increase the susceptibility to root resorption. Application of light force, periodical monitoring of root resorption and control of allergy are advisable