Effect of Saliva Contamination on Shear Bond Strength of Transbond XT and Assure Universal Bonding Resin to Enamel

Background and Aim : Assure universal bonding resin is a modified cement with fluoride releasing property. It is claimed to provide adequate bond strength between the bracket and enamel in wet conditions although more studies are required in this regard. This study compared the shear bond strength of Transbond XT and Assure universal bonding resin to dry and saliva-contaminated enamel in vitro .   Materials and Methods : In this in vitro study, 60 extracted human premolars were selected and stainless steel brackets were bonded to enamel surfaces. Bonding of brackets to enamel surfaces was done using Assure universal bonding resin (dry condition), Transbond XT (dry condition) and Assure (saliva-contaminated condition). The shear bond strength of brackets to the enamel was determined by Zwick/Roell machine in three groups. Data were analyzed using one-way analysis of variance (ANOVA), and the Kruskal Wallis test .   Results : The mean shear bond strength of brackets to enamel surfaces bonded with Assure (dry condition), Transbond XT and Assure (saliva-contaminated condition) was 14.18±4.78 MPa, 16.13±5.49 MPa and 13.32±4.74 MPa, respectively (with no significant differences). Non-parametric Kruskal-Wallis test found no significant differences regarding the adhesive remnant index (ARI).(p=0.053). .   Conclusion : Bonding of stainless steel brackets to enamel surfaces with Assure universal bonding resin provided adequate bond strength in dry and saliva-contaminated conditions. Thus, it may be used for bonding of orthodontic brackets to the enamel surfaces in the clinical setting

Microshear Bond Strength of Transbond XT and Assure Universal Bonding Resin to Stainless Steel Brackets, Amalgam and Porcelain

Background and Aim: Assure Universal Bonding Resin is marketed with fluoride releas-ing potential. The manufacturer claims that it provides adequate bond strength between the bracket and amalgam and porcelain. This study compared the shear bond strength of Transbond XT and Assure Universal Bonding Resin to stainless steel brackets, amalgam and porcelain in vitro. Materials and Methods: In this in vitro study, 20 standard brackets of the maxillary cen-tral incisors, 20 feldspathic porcelain specimens and 20 self-cure acrylic cavities filled with amalgam were divided into 2 groups bonded with Transbond XT and Assure. After surface preparation in each group, Transbond XT composite was applied to the surfaces using silicon tubes and light-cured for 20 seconds. Then, the microshear bond strength was measured using a universal testing machine. The data were subjected to two-way ANOVA, Tukey’s post hoc test, Student’s t-test and the Kruskal Wallis test. Results: Different microshear bond strength values were obtained for the bond to stain-less steel brackets, amalgam and porcelain by Transbond XT and Assure (p<0.000). Using Assure for bonding to amalgam (7.2±1.46 vs. 10.12±4.97) and brackets (16.14±3.2 vs. 20.16±5.12 p<0.05) decreased the microshear bond strength compared to Transbond XT. However, Assure significantly increased the bond strength to porcelain compared to Transbond XT (28.84±6.42 vs. 22.48±3.6 p<0.01). Non-parametric Kruskal-Wallis test showed significant differences in adhesive remnant index (ARI) between the two bonding agents only in the amalgam group (p=0.029). Conclusion: Although the bond strength values of Assure were less than those of Transbond XT, Assure was capable of providing sufficient bond strength especially to porcelain

Effects of two soft drinks on shear bond strength and adhesive remnant index of orthodontic metal brackets.

Bond failure of brackets during orthodontic treatment is a common problem; which results in treatment interference, increased treatment time and prolonged clinical time for rebonding of failed brackets. The purpose of this study was to evaluate the effects of Coca-Cola and a non-alcoholic beer on the shear bond strength and adhesive remnant index (ARI) of orthodontic metal brackets in vitro.Eighty intact human premolars were divided into two experimental groups of Coca-Cola and non-alcoholic beer (Istak), and a control group of artificial saliva. Over a period of thirty days, the test groups were immersed in the respective soft drinks for 5 minutes, twice a day. For the remainder of the time, they were kept in artificial saliva at 37°C. The control group was stored in artificial saliva during the experiment. All samples were subjected to shearing forces using Universal Testing Machine. ARI was determined with a stereomicroscope at ×12 magnification. The data of shear bond strength were statistically analyzed by one-way ANOVA and Tukey's Post-Hoc test and the data of ARI scores were analyzed by Kruskal-Wallis test.No significant difference was observed in ARIs of the three groups (P≤ 0.552). The shear bond strength of Coke group was significantly lower than that of the two other groups (P≤ 0.035); but there was no significant difference between the shear bond strength of Istak and the control group (P≤ 0.999).Coca-Cola decreased the shear bond strength of orthodontic brackets

Cephalometric evaluation of soft tissue changes after extraction of upper first premolars in class II div 1 patients

Introduction: Tooth extraction to provide sufficient space, or camouflage of underlying skeletal problems is quite common in orthodontics. The present study evaluated soft tissue changes after upper first premolars extraction in class II div 1 patients. Material and Methods: 20 cases (15 females, 5 males), with a mean age of 17.8±2.9 years with class II div1 malocclusion and normal vertical height, who needed upper first premolars extraction were selected. Pre- and post- treatment lateral cephalometric radiographs were digitized. Image analysis was conducted by View Box 3.1.1 software. Paired t-test was used for comparison of pre- and post-treatment results. Results: The relationship of upper and lower lip to E-line and B-line had significant reduction. Dental variables of U1-NA(mm), U1-NA(°), overjet and overbite showed statistically significant reduction. Interincisal angle had significant increase. There were no significant difference in lower incisor variables and skeletal variables like SN- GoGn and FMA. Conclusions: Extraction of upper first premolars in patients with class II div 1 malocclusion resulted in normal position of lips as presented by Holdaway, Legan and Ricketts which play a role in aesthetic profile. However, the amount of lip retraction was different from patient to patient

Severe Rotational Drift of an Impacted Mandibular Third Molar: A Case Report

hird molar eruption is an unpredictable event. Occasionally, mandibular third molars undergo angular changes in young adults. This rotational drift is of unknown etiology, is not predictable and may facilitate the eruption or may make the impaction worse. A rare case is presented with severe rotational drift of a mesioangularly impacted mandibular third molar

Palatal dimensions at different stages of dentition in 5 to 18-year-old Iranian children and adolescent with normal occlusion

Abstract Background This study was purposed to evaluate palatal width, height, and height index at various stages of dentition in Iranian children and adolescent with normal occlusion. Methods This cross-sectional study was conducted on a random sample of 237 children (45% male and 55% female, aged 5–18 years) with normal occlusion selected from kindergartens and elementary and high schools in Hamadan, Iran. The subjects were clinically examined and classified based on dentition to primary (21.5%), mixed (21.9%), and permanent (56.5%) stages. Dental casts were obtained from all subjects. Palatal width (inter-molar and -canine distances), and height (at molar and canine areas) were measured on the casts by Korkhaus’ compass and digital caliper. Palatal height index was calculated for each dentition stage. Data were analyzed by SPSS 15 using one-way ANOVA followed by Tukey’s post hoc test and t- test (p <  0.05). Results Palatal inter-molar and -canine width values were increased from primary to permanent dentition. Palatal height and palatal height index in mixed dentition were significantly lower than those in primary and permanent dentition. Palatal width at inter-molar and -canine distances was significantly higher in males than females. There was no significant difference in palatal height and palatal height index at molar area between males and females. However, palatal height and palatal height index at canine area were significantly higher in males compared to females. Conclusion These findings showed that palatal width increased from primary to permanent stage. Palatal height and palatal height index decrease from primary to mixed dentation, then increase from mixed to permanent dentition

Effect of Incorporation of Nano-Hydroxyapatite and Nano-Zinc Oxide in Resin Modified Glass Ionomer Cement on Metal Bracket Debonding

Background and Aim: Use of fluoride releasing materials to decrease the risk of demine-ralization around orthodontic brackets would be reasonable as an adhesive for bracket bonding only if they provide acceptable shear bond strength (SBS). The aim of this study was to evaluate the SBS of resin-modified glass ionomer cements (RMGICs) modified by nano-zinc oxide (NZnO) and nano- hydroxyapatite (NHA) in comparison with composite resins. Materials and Methods: In this experimental study, 80 extracted human premolars were used. The teeth were randomly divided into 4 groups as follows: Group 1: Trans bond XT as a control group, Group 2: RMGIC (Fuji II LC), Group 3: RMGIC with5% NHA and Group 4: RMGIC with2% NZnO. After etching the enamel, brackets were bonded. The SBS was measured for each group. The percentage of adhesive remnants on the enamel surface was quantified using the adhesive remnant index (ARI).The data were analyzed using one-way ANOVA and the Kruskal Wallis test. Results: According to the results of ANOVA, no significant difference was found in theSBS of groups (p=0.075). The mean shear bond strength in groups 1 to 4 was 15.43 ± 4.61, 14.95 ± 4.34, 17.97 ± 3.65 and 17.08 ± 3.59, respectively. According to the Kruskal-Wallis test, there was no significant difference in ARI score among the groups (p=0.413). Conclusion: The amount of SBS was similar among all groups and addition of NZnO and NHA particles had no negative effect on SBS of RMGIC. Less than half the adhesive re-mained on the enamel surface after bond failure in all groups

Effect of Nano-Hydroxyapatite Incorporation into Resin Modified Glass Ionomer Cement on Ceramic Bracket Debonding

Background and Aim : Preventing enamel demineralization around brackets is a concern for orthodontists. Fluoride releasing materials have been recommended to overcome this problem. The aim of this study was to evaluate the effect of incorporating nano-hydroxyapatite (NHA) into resin modified glass ionomer cements (RMGIC) on ceramic bracket debonding .   Materials and Methods : In this experimental study, 80 human premolars were divided into 4 bonding groups as follows: group 1: Transbond XT (control group), group 2: Fuji II LC (RMGIC), group 3: 5% NHA added to RMGIC and group 4 10% NHA added to RMGIC. After enamel etching, ceramic brackets were bonded. The shear bond strength (SBS) and the adhesive remnant index (ARI) were calculated for each group. The data were analyzed using one-way ANOVA, Tukey’s post hoc HSD test and the Kruskal Wallis test .   Results : According to ANOVA, 10% NHA added to RMGIC had a significantly lower SBS compared to other groups (11.93±2.11) but no significant difference was found among the remaining groups. The mean SBS was 17.33±4.07 in group 1, 17.22±3.55 in group 2 and 16.56±2.59 in group 3. According to ARI, the predominant failure mode in RMGIC groups was cohesive .   Conclusion: Resin modified glass ionomer cements containing 5% NHA can be as effective as composite resins for bonding ceramic brackets