Effect of psychological stress on orthodontic tooth movement in rats

Introduction: The purpose of this study was to investigate the effect of psychological stress on orthodontic tooth movement in Wistar rats. Materials and methods: Forty-eight female ten-week old Wistar rats with an average weight of 188 ±12 gr were selected and randomly divided into two experimental and control groups. The experimental group received crowded environment-induced and cat odour stresses 4 weeks before spring insertion. On the 29th day in both groups, maxillary incisors were moved by the insertion of springs and exactly after 7 days, 9 rats from each group and after 14 days the remaining rats were sacrificed. Then the mesioincisal distance between maxillary incisors was measured. Afterwards, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement and the number of osteoclasts were analyzed by independent sample t-test. Results: The results indicated that on the 7th day after spring placement the orthodontic tooth movement was significantly higher in the control group compared to the experimental group (p<0.05). The number of osteoclasts at a significance level of ?=0.1 in the control group was higher compared to the experimental group. On the 14th day after spring placement, the orthodontic tooth movement in the control group was significantly higher compared to the experimental group (p<0.05). However, there were no significant differences in the number of osteoclasts between the two groups. The rats experienced weight loss in the experimental group (p<0.05). Conclusions: Psychological stress led to a decrease in orthodontic tooth movement and in the number of osteoclasts around the root in the movement direction in rats, but a decrease in osteoclast counts was not parallel with time and demonstrated a nonlinear pattern. In addition, psychological stress led to weight loss in rats

Effect of self-etching primer/adhesive and conventional bonding on the shear bond strength in metallic and ceramic brackets

Introduction: Bracket debonding from the tooth surface is a common problem in fixed orthodontics. The aims of the present study were to assess the bond strength and failure sites in two ways of bonding technique, with metallic and ceramic brackets. Materials and Methods: One hundred premolars were assigned to 4 groups of 25each: Group A, metallic brack-Methods: 255 GGroup brackets/ conventional procedure; B, metallic brackets/Transbond XT; C, ceramic brackets/conventional procedure; and D, ceramic brackets/Transbond XT. Transbond XT composite paste was used for bracket bonding and cured by conventional light-cure device. Specimens were subjected to thermocycling. One week after bonding shearing force was applied to the bracket-tooth interface. Bonding failure site optically examined using a stereomicroscope under 10 × magnifications and scoring was done using the adhesive remnant index (ARI). Data were subjected to analysis of One-way variance, Tukey post hoc, Chi-square and Spearman's tests. Results: Mean bond strength (in MPa) were: group A=9.2, group B=8.55, group C=6.2 and group D=55.7. Bond strength differences between groups A and B, and between C and D were not significant, (p<0.0005). Insignificant difference found in ARI in all groups. Conclusion: The bond strengths of metallic brackets were significantly higher than ceramic ones and the self-etching primer produce fewer bonds than the conventional method (clinically acceptable). A positive correlation found between changes in shearing bond strength and ARI. © Medicina Oral S. L

Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: an in-vivo study

Background: Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. Material and Methods: 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups. Results: The mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, ( P =0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded speci mens in different brackets or bonding systems. Conclusions: The SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system

The effect of pregnancy on orthodontic tooth movement in rats

Introduction: The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats. Material and Methods: Forty eight female three-month old Wistar rats with an average weight of 250 ±25 g r were selected and randomly divided into two experimental (pregnant) and control groups (non-pregnant). Maxillary central incisors were tipped distally by insertion of springs exerting 30g force. Two, seven and fourteen days after spring insertion animals were sacrificed. Then the mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement, and the number of osteoclasts were analyzed by independent sample t-test. Results: The results indicated that 2,7 and 14 days after force application there was no significant difference in orthodontic tooth movement between experimental and control groups (p>0.05). The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion (p<0.05). Conclusion: Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant. The number of osteoclasts is significantly decreased during pregnancy

The effect of oral contraceptives on orthodontic tooth movement in rat

Introduction: The purpose of this study was to investigate the effect of ethinyl estradiol/norgestrel ? used in some oral contraceptives- on orthodontic tooth movement in Wistar rats. Material and Methods: Forty eight female three-month old Wistar rats with an average weight of 250?25gr were divided into two experimental and control groups. One week prior to appliance insertion and during the appliance therapy period, 100 mcg/kg/day of ethinyl estradiol and 1mg/kg/days of norgestrel were administered to the experimental group by gavage; meanwhile the control group received an equivalent volume of Sodium Chloride 0.9 % (Saline). Maxillary central incisors were tipped distally by insertion of springs exerting 30g force. Two, seven and fourteen days after spring insertion animals were sacrificed. The mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared for histomorphometric studies. Results: 14 days after force application the orthodontic tooth movement was significantly lower in the experimental group (p<0.05). The number of osteoclasts were significantly lower in the experimental group 2, 7 and 14 days after spring insertion (p<0.05). Conclusion: Ethinyl estradiol/norgestrel (oral contraceptives) can significantly decrease the amount of tooth movement in the linear phase

Comparison of the Effects of Traditional with Combined (Traditional and Electronic) Educational Methods on Promoting the Practical Skill of Fabricating the Removable Orthodontic Appliance

Introduction: Computer aided education can compensate for some deficiencies and limitations of traditional education. The aim of this study was to evaluate the effect of e-learning, as an adjunctive method of traditional education, in the form of video clips and PowerPoint presentations on the skills of fabricating the wire components of removable orthodontic appliance in the preclinical course of dental students. Methods: This prospective quasi-experimental study was performed on 40 eighth semester dental students who were taking the course practical orthodontics 1 in Tabriz School of Dentistry in 2012-13 academic year. Participants were selected through convenience sampling and randomly divided into two groups. The control group received traditional trainings including practical training of fabricating the wire components of removable orthodontic appliance, and the experimental group received the same plus e-learning. The skills in fabricating three major components of removable orthodontic appliance namely Z spring, Adams clasp and labial bow were evaluated using a 21-item checklist. Data were analyzed by means of independent and paired t-tests. Results: The mean scores of the control and the experimental groups were 14.2±1.4 and 15.5±1.8 (out of 20) respectively and their difference was statistically significant (P=0.026, t=2.31). The mean score of labial bow fabrication was higher in the experimental group than that of the control group (p=0.01, t=2.72). However, the mean scores of Z spring and Adams clasp fabrication were not significantly different in the two groups. Conclusion: Using E-learning as an adjunctive method of traditional education can improve the practical skills of fabricating the wire components of removable orthodontic appliances

Assessment of Factors Affecting Adolescent Patients’ Compliance with Hawley and Vacuum Formed Retainers

INTRODUCTION: Success of orthodontic retention with removable retainers almost entirely depends on patients’ compliance. AIM: This study was carried out to investigate the relationship between adolescent orthodontic patients’ compliance and various clinical and social factors. MATERIALS AND METHODS: The data were collected from 77 orthodontic patients aged 7-11 years old who had finished the full fixed appliance therapy. Hawley’s retainers were used in 34 patients and 43 patients used Vacuum Formed Retainers (VFRs). The subjects completed a questionnaire including several identifiers allowing the respondents to be classified into subgroups. They were also asked to indicate how long they wore their retainers during the day, by writing the number of hours in the report-card for the next three months. Comparison of the results was performed by one-way ANOVA and independent sample-t tests. RESULTS: No significant differences were found between males and females. Type of the retainer, patients’ grade of study, mothers’ occupation, clinicians’ and parents’ attitudes and filling the report cards had significant effect on mean wear hours per day. When compliance of the patients was assessed according to treatment location, Living place, parents’ educational degrees and ethnicity, no significant differences could be found. CONCLUSION: The adolescent patients’ compliance was greater with VFRs than with Hawley’s retainers. Parental attitude and doctor-patient relationship had a great impact on adolescent patients’ compliance