Prevalence of dental anomalies in different facial patterns and malocclusions in an Iranian population

Objective

This study aimed to evaluate the prevalence and association of dental anomalies with different types of malocclusions and facial patterns.

Methods

In this cross-sectional study, the records of patients referred to the Orthodontics Department at 12-20 years of age were collected. The patients were classified into four types of malocclusion: Cl I, Cl II div 1, Cl II div 2, and Cl III, and three types of facial patterns: normal, long, and short. Fifteen dental anomalies were searched within the documents. The statistical analysis of data was performed with chi-squared and Fisher's exact test.

Results

Among 602 patients evaluated in this study, 28.6% were males, and 71.4% were females. The prevalence of Cl I, Cl II div1, Cl II div 2, and Cl III was 58.3%, 28.7%, 5.5%, and 7.5%, respectively. The normal facial pattern was most prevalent (47.2%), followed by the long facial pattern (41.4%) and short facial pattern (11.5%); 60.7% of the study population had at least one dental anomaly. Dilaceration was the most common anomaly (27.7%), followed by impaction (21.8%) and hypodontia (18.9%). Most dental anomalies were found in females, Cl II malocclusion, and long face samples. A statistically significant association was found between transposition and male gender (P = 0.006) and between short roots and Cl II malocclusion (P = 0.047). No significant association was found between dental anomalies and facial patterns.

Conclusion

Significant associations were reported between transposition and male gender and between short roots and Cl II malocclusion. In our population, dilaceration was the most common dental anomaly.

Contrary to an old belief, four corner curing does not provide more bond strength or polymerization in bonding of orthodontic metal brackets

Objectives:

The study aimed to investigate the effect of the direction of light curing on bond strength and adhesive polymerization of orthodontic metal brackets.

Material and Methods:

In this in vitro investigation, 75 extracted human upper premolars were randomly divided into three groups according to the curing direction: Group A (20 s curing from the occlusal side of the bracket), Group B (10 s from occlusal and 10 s from gingival), and Group C (5 s from four corners of the bracket). After bonding, the brackets were subjected to a shear bond strength (SBS) test performed with a universal testing machine. Moreover, Fourier transform infrared spectroscopy (FTIR) analysis was used to find the polymerization ratio of the adhesives in each group. Kruskal–Wallis test was to statistical analysis of SBS and FTIR data, respectively, at the 0.05 level of significance.

Results:

The difference in SBS of metal brackets was not statistically significant between the groups (P > 0.05). However, the difference in polymerization ratio was significant between all groups where the highest and lowest ratio belonged to Groups A and B, respectively (P < 0.05).

Conclusion:

Curing metal brackets from four corners do not increase their bond strength and/or polymerization.

Evaluation of the success rate of pit and fissure sealants on first molars, 12 months follow-up study

INTRODUCTION

Dental caries by far is the most prevalent concern of the preadolescents and adolescents in dental clinics. Despite the provision of local fluoride, the occlusal surfaces of teeth are susceptible to dental caries. Pit and Fissure sealant therapy is a preventive method to decrease dental caries in permanent teeth. The present study aimed to evaluate the success of fissure sealant treatments of first molar teeth, at 3, 6, and 12 months follow-ups.

MATERIALS AND METHODS

Sixty five children were randomly selected. The subjects had already received fissure sealants in the department of public health dentistry. Demographic data, including age and gender, sealant failure and the type of failure were recorded in the relevant checklists. Feigal criteria were used to evaluate the success or failure of fissure sealant treatments.

RESULTS

Overall success rate was 74.3 % for one year. Evaluation of the failure rate showed that at the 3-month interval, 20.6% of the sealants exhibited failure (57.1% due to margin discoloration and 42.9% due to lack of margin adaptation). 28.6% of the sealants failed at the 6-month (75% due to marginal discoloration and 25% due to anatomic form) and 41.2% failed at the 12-month interval (57.1% due to marginal discoloration and 42.9% due to the lack of margin adaptation).

CONCLUSION

The total failure rate of fissure sealant failures after one year was 27.7%. The most frequent reason for the failure of fissure sealants was marginal discoloration.

Inclinometer: A new device for measuring intermolar torque and angle

The torque of posterior teeth is of great importance in esthetics and occlusion. In the present article, we introduce a simple but useful device to measure intermolar torque. The device consists of two movable and adjustable arms that lie on the selected molar teeth bilaterally; the graduated plane at the body of the appliance then shows the intermolar torque. This device can measure intermolar torque easily and rapidly, with high validity and at a low cost.

Effect of different types of acid-etching agents and adhesives on enamel discoloration during orthodontic treatment

Background. Acid etching and bonding is a routine process in orthodontic treatment. The present study aimed to evaluate enamel discoloration after using different types of acid etching and adhesive agents.

Methods. A total of 105 extracted human premolars were divided into six groups regarding the type of acid etching agent: solution and gel of 37% phosphoric acid, and type of self-cured adhesive agent: Unite (3M, fluoride-free), Resilience (Ortho Technology), and Rely-a-Bond (Reliance, fluoride-releasing adhesive), with each group containing 15 specimens. All the selected teeth were subjected to a staining process, and color parameters were determined using a spectrophotometer.

Results. The type of phosphoric acid (solution or gel) had no significant effect on the color change of enamel (P >0.05). Resilience significantly changed the enamel color compared to the Unite and Rely-a-Bond (P <0.001). There was no significant difference in color change between the Unite and Rely-a-Bond adhesives (P =0.67). The difference in color change between all the three time intervals (T0-T1, T1-T2, and T0-T2) was significant (P <0.001).

Conclusion. In this study, the type of phosphoric acid (solution or gel) did not result in any significant difference in enamel color. Also, considering the lack of the effect of the orthodontic adhesive type in terms of fluoride release or no fluoride release, it can be concluded that this is most affected by the commercial brand of adhesives.

The effect of sandblasting and acid etching on survival rate of orthodontic miniscrews: a split-mouth randomized controlled trial

Background

The aim of this study was to investigate the effect of surface roughening and acid etching on clinical success rate and removal and insertion torque of orthodontic miniscrews.

Materials and methods

Sixty-two orthodontic miniscrews (Jail Medical Corporation, Seoul, Korea) with the same design and dimensions (10-mm length, 2-mm diameter) are divided into two (sandblasted and acid-etched versus control) groups. The sample of the study was 31 patients whose miniscrews were needed for en masse retraction of the upper six anterior teeth. In this split-mouth study, the miniscrews were placed in the attached gingiva between the second premolar and the first molar. The side (left or right) was selected randomly. The miniscrews were loaded 6 weeks after insertion, and the patients were followed up after 3, 6, 10, 14, and 18 weeks and then for 4 weeks interval. Chi-square, correlation, and independent t tests were done using SPSS ver24 to interpret the data.

Results

The survival rate was 90.3% and 83.9% for the sandblasted and acid-etched versus the control group, respectively. The difference in survival rate was not statistically significant (p > 0.05). Removal torque was higher for the sandblasted group (p < 0.05). Younger patients showed less survival rate (p < 0.05) in both groups. Insertion side, namely, left or right, was not statistically significant.

Conclusions

Although sandblasting increased removal torque, it did not influence the survival rate of orthodontic miniscrews significantly.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40510-020-00347-z.

The effect of ZnO nanoparticle coating on the frictional resistance between orthodontic wires and ceramic brackets

Background. Any decrease in friction between orthodontic wire and bracket can accelerate tooth movement in the sliding technique and result in better control of anchorage. This study was carried out to evaluate frictional forces by coating orthodontic wires and porcelain brackets with zinc oxide nanoparticles (ZnO).

Methods. In this in vitro study, we evaluated a combination of 120 samples of 0.019×0.025 stainless steel (SS) orthodonticwires and 22 mil system edgewise porcelain brackets with and without spherical zinc oxide nanoparticles. Spherical ZnOnanoparticles were deposited on wires and brackets by immersing them in ethanol solution and SEM (scanning electronmicroscope) evaluation confirmed the presence of the ZnO coating. The frictional forces were calculated between the wiresand brackets in four groups: group ZZ (coated wire and bracket), group OO (uncoated wire and bracket), group ZO (coatedwire and uncoated bracket) and group OZ (uncoated wire and coated bracket). Kolmogorov-Smirnov, Mann-Whitney andKruskal-Wallis tests were used for data analysis.

Results. The frictional force in ZZ (3.07±0.4 N) was the highest (P <0.05), and OZ (2.18±0.5 N) had the lowest amount of friction (P <0.05) among the groups. There was no significant difference in frictional forces between the ZO and OO groups (2.65±0.2 and 2.70±0.2 N, respectively).

Conclusion. Coating of porcelain bracket surfaces with ZnO nanoparticles can decrease friction in the sliding technique,and wire coating combined with bracket coating is not recommended due to its effect on friction.

Does prenatal restraint stress change the craniofacial growth pattern of rat offspring?

A major and frequently encountered condition underlying the long-term programming effects of the intrauterine environment is exposure to stress. Gestational stress is an environmental factor that induces physical and behavioral alterations in offspring. Seventy female virgin Wistar rats were mated with one male rat for a maximum of four times, after which 52 pregnant rats were divided into two groups. In the experimental group the rats were exposed to restraint stress during pregnancy, whereas the control group did not receive the stress protocol. One male litter was randomly chosen from the offspring of each rat with 8-13 pups. A total of 40 male rat offspring were available for analysis. Thirty-one linear and angular measurements were analyzed in both study groups to investigate whether prenatal restraint stress changes the craniofacial growth pattern of rat offspring. In the prenatally stressed group, anterior cranial base length and viscerocranium measures were significantly increased compared with the control group, whereas cranial width, mandibular dimensions, and posterior cranial height and length remained unchanged. Furthermore, the prenatally stressed group showed backward rotation of the midface and decreased flattening of the cranial vault. It was concluded that prenatal chronic stress can induce alterations in the craniofacial growth pattern by promoting endochondral growth in the cranial base and nasal septum.