Iranian Journal of Orthodontics
Volume:8 Issue: 1, Mar 2013

Orthodontic tooth movement requires remodeling of periodontal tissues, especially alveolar bone. A major objective of investigators is to achieve maximum tooth movement with minimal root damage. The aim of this study is to determine if the rate and amount of orthodontic tooth movement in a sample of rats could be enhanced by the injection of a vitamin D metabolite and Prostaglandin E2. Thirty-Two male Wistar rats were randomly divided into 4 groups of eight rats each: 1- 1.5 IU/ml vitamin D was injected into the thigh muscle after installation the orthodontic appliance in first group (Vit D group) 2- 0.1 ml of 1 mg/ml PGE2 was injected submucosally in the second group (PGE2 group). 3- In the third group, 1.5 IU/ml vitamin D and 0.1 ml of 1 mg/ml PGE2 was injected submucosally (Vit D+ PGE2). 4- Distilled water (0.1 ml) was used in control group. In order to calculate the tooth movement; the distance between the upper right first and second molars was measured. All groups have a significant difference with control group (p<0.05). The most mean OTM was observed in the Vit D+PGE2 group (Mean = 0.702± 0.04897mm) that was significantly higher than the Vit D, PGE2 and control groups (P < 0.05).A significant difference (P< 0.05) in root resorption was observed between the PGE2 (0.0192 ±0.000675 mm2) and the other groups. In order to achieve a decrease in root resorption and an increase in OTM, the combination Vit D+PGE2 is useful and there is a synergism effect with Vit D and PGE2.

Today, consideration of soft tissue, esthetic and appropriate facial harmony in patients have been regarded as the base for orthodontic treatments. Therefore, awareness of soft tissue profile changes during growth is essential for orthodontists. The purpose of this study is to determine the changes of soft tissue profile during growth in both sexes. In this descriptive-analytical cross-sectional study, lateral cephalometric images of 60 individuals (30 boys and 30 girls) between 8 and 18 years old were studied. Cephalometric analysis was done and Independent T and Pearson Correlation tests were used for data analysis. Findings in the present study indicated that nose height, nose depth, lips height, upper lip thickness and soft tissue chin thickness increased significantly in the both sexes with increasing age. Increasing lip thickness in point Ls and lower lip thickness in point Li were only significant in boys group, whereas angle of soft tissue facial convexity excluding the nose and lower lip thickness had no significant increase in the both sexes. Angle of soft tissue facial convexity including the nose reduced significantly in both sexes with increasing age. Different measures change variously in males and females between 8 to 18 years old and being aware of these changes will help orthodontist in getting the best decision in preadolescent and adolescent treatment planning.

Accurate identification of dental and skeletal characteristics of different kinds of malocclusions is necessary for educational purposes, proper treatment planning and to reach successful results. The aim of this study was to assess skeletal and dental differences of class II division I patients in Shiraz and Hamadan Dental Schools. In this retrospective study lateral cephalograms of 98 patients from Hamadan (53 girls and 45 boys) and 96 Patients from Shiraz (48 girls and 48 boys) with class II division I malocclusion and age range of 9-14 years old were evaluated. Cephalograms with ANB angle higher than 5 degree were traced with Dolphin program. Statistical analysis was performed using SPSS software. Student t- test was used for between group comparisons. Chi- Square tests used for dichotomous variables. Comparison of mean values of variables between the two groups showed significant differences between SNB, MP-SN, U1-NA0,Y-Axis, Inter incisal angle and PFH/AFH. High percent of patients in both groups had mandibular retrusion, vertical facial growth pattern, protrusion of upper and lower anterior teeth. These characteristics were not statistically significant between boys and girls. This study revealed that there was more mandibular retrusion, vertical facial growth and maxillary protruded incisors in class II division I patients of Hamadan in comparison to Shiraz.

Cleft lip and palate is a common craniofacial congenital malformation. Treatment of this deformity has always been a matter of great concern for physicians and specialists. Data on the incidence and prevalence rate of this condition can help medical authorities plan for the healthcare of these patients. Present study aimed to determine the incidence rate and related risk factors of cleft lip and palate in Hamadan province in 2007 In this study، 29،822 newborns were evaluated in Hamadan Province hospitals، Iran. Variables such as neonatal gender، parents’ occupations، place of residence، family background، parental consanguinity، and neonatal co-occurring disorders، as well as maternal factors such as age at pregnancy، diseases during pregnancy، medications، drug abuse، smoking، alcohol consumption، radiography، and radiotherapy during pregnancy were recorded. Finally، the data were analyzed using SPSS version 13. 25 neonates (14 male and 11 female subjects) were born with various forms of cleft lip and cleft palate. The incidence rate was 0. 83 per 1000 live births. Cleft lip and palate (bi or unilateral) and isolated cleft palate were the most and least frequently reported cases، respectively. In total، 28% of the newborns presented with other co-occurring disorders. Consanguineous marriage was reported in approximately 28% of the neonates’ parents and 12% of the mothers used medications such as phenytoin، imipramine، and trifluoperazine during pregnancy. The incidence rate of cleft lip and palate was close to the average global rate and reports in European and East Asian countries. The incidence rate of clefts was higher in males، compared to females. According to the results، parental consanguinity and mother’s medication، especially at the beginning of pregnancy، are regarded as risk factors for cleft lip and palate،

The objective of this study is determining the correlation among the dental crowding and mesiodistal tooth width and dental arch dimensions. In this case-control study dental casts of two groups of 40 subjects was investigated. Each group included 20 male and 20 female subjects with the age range of 17 to 25 years old. The first group had class I malocclusion with nominal or no crowding. (space deficiency ≤ 4). The second group had class I malocclusion with significant crowding. (space deficiency ≥ 4). The following parameters were measured and compared in both groups: The sum of mesiodistal tooth width, arch length in canine and molar spaces and arch perimeter. In order to compare the two group independent t-test with 95% confidence was applied. In lower arch a significant difference was detected in both tooth size (P=0/02) and arch dimensions. The group with the significant crowding has smaller arch dimension and larger tooth size in comparison to the group with no crowding. In the upper arch a significant difference in intercanine width (P=0/01), arch perimeter (P=0/023), arch length (P=0/012), and intermolar width (P=0/03) was detected. The results of this study indicated that in upper arch the arch dimensions plays a significant role in crowding, and in the lower one both tooth size and arch dimensions have important role in crowding.

The frequency of exposure of dental personnel to infection and of patient to cross contaminated instruments has prompted concern about adequate sterilization of dental instruments. Aim of the present study was to evaluate the changes in the frictional properties of Ni-Ti orthodontic wires after sterilization with chemical agents. In the present study the friction between Ni-Ti wires measuring 16 mm in diameter and 18-slot stainless steel brackets were measured and compared in two groups as follows: 1) without sterilization (as received); 2) after chemical sterilization. Each group consisted of 30 specimens and friction was measured in a Universal testing machine. Comparison of unsterilized samples with the group sterilized with chemical agents showed a significant difference (P=0.000) in shear stress Based on the results of the present study, this sterilization techniques result in an increase in the friction of NiTi orthodontic wires.

The objective of this study was to investigate the relationship between the gonial angle changes and occlusal plan steepness in patients underwent Bilateral Sagittal Split Osteotomy (BSSO) surgery. In this analytical retrospective clinical trial, 18 males and 12 females were studied who had been underwent BSSO surgery for mandibular advancement in. Cephalometric landmarks were calculated on the patients'' lateral radiographs taken before and 1-6 months postsurgery using Dolphin software. The patients assigned into 3 groups according to different occlusal plan steepness. Landmarks'' changes before and after surgery were analyzed by Paired t-test. The changes occurred regarding the normal and flat facial types assessed by Student t-test while the relationship between the presurgical occlusal plan and the landmark changes was evaluated using the Pearson Coefficient. After BSSO, the gonial angle had increased in all patients with the mean value of 6.83ᴼ (P˂0.0001) but occlusal plan steepness increased to an insignificant value (mean 2.82ᴼ). Increased values of the gonial angle were similarly reported in the patients with normal occlusal plan steepness and flat occlusal plan while no significant relationship was found between occlusal plan steepness before the surgery and the gonial angle changes after surgery. However, fair more increase occurred in patients with normal steepness than lower ones. The results showed that there is no significant relationship between the gonial angle changes after surgery and the occlusal plan steepness prior the surgery of BSSO for mandibular advancement.

Number of studies evaluating the changes in head position following mandibular setback surgery (MSS) is scarce. This study sought to assess the craniofacial morphology, head and neck posture following mandibular setback surgery. This retrospective, longitudinal, semi-experimental study was performed on 35 patients with Class III malocclusion. Radiographs taken at baseline and one year after surgery were retrieved from the medical records of patients. Lateral cephalograms were scanned and landmarks were marked on the first (baseline) radiograph. The second radiograph was superimposed on the first radiograph, true vertical lines or a ruler were considered as parallel images and a line was drawn along the SN from the point S. After superimposition, cephalometric variables were measured using Orthosurger X software (Iran). The mean, standard deviation (SD) and range of changes in each group were calculated. The significance of differences caused by surgery was analyzed using paired t-test. The total mandibular length, mandibular body length, ramus length, SNB, SN-Pog, A-N-Pog, the angle between the body and ramus and the mandibular plane inclination significantly decreased; while, ANB angle, overjet and overbite significantly increased. No significant change occurred in the head position or cervical vertebra following MSS. Since changes in the positions of cervical hard tissue were not significant, decreased airway volume following MSS seems to be related to the soft tissue structures namely the tongue, the soft palate and the suprahyoid and cervical muscles.