Iranian Journal of Orthodontics
Volume:2 Issue: 1, Jun 2007

corrosion of NiTi wires in the oral cavity has been a matter of discussion in some in-vitro studies but in-vivo tests about corrosion of NiTi wires have been rarely investigated. We designed an in-vivo study to evaluate corrosion behavior of retrieved NiTi wires compared with as-received wires.  Considering our criteria, 15 participants demanding orthodontic treatment entered the study, two NiTi SE(G&H) wires were inserted in bracket slots and band tubes and two passively in auxiliary tubes of molars. After 2 months wires were retrieved and were evaluated regarding clinical conditions (tarnish, deformation). Then potentiodynamic test performed on distal segment of 60 retrieved wires and Rp test (polarization resistance test) for all specimens including retrieved and as-received wires. Non parametric tests were used to compare retrieved and as-received wire groups. Retrieved wires showed clinically and electrochemically significant corrosion compared with as-received wires (p<0.05). All retrieved wires showed signs of tarnish which was more in lower arch. Among all retrieved wires, 5 wires showed deformation, 3 from lower arch and 2 from upper arches. One of recent two wires belonged to not-engaged group. Despite of adequate corrosion resistance, NiTi wires, engaged or not engaged will corrode electrochemicallyin oral enviroment and should be noticed in clinical use.

 Assessment of skeletal and dentoalveolar changes in class II division 1 patients after treatment with Seifi's functional appliance in dental school of Shahid Beheshti. University in 2007-2008.  In this before- after clinical trial study, Seifi's functional appliance was used for 15 patients (mean age: 9.84±1.24 year) with class II division I deep bite maloccIusion. All of them had mandibular deficiency and ANB>4 degrees, OJ and OB>4mm. Lateral cephalometric and panoramic radiographs, primary impression via alginate, intraoral and facial photographs were taken at the beginning of the study and after 10.2±2.01 months. The results were compared to each other. The device was two pieces and consisted of an acrylic cap on mandibular incisors and a mid palatal screw and a vertical plate on the upper jaw. In sagittal dimension ANB, 1-SN and OJ decreased and SNB increased (P<0.05). Changes of SNA and IMPA were not significant(P>0.05). In vertical dimension OB decreased and L6-MP increased(P<0.05). Due to simultaneous three dimensional correction in transverse, sagittal and vertical dimensions, the patient benefits of the short period of treatment in the golden growth period. Also correction in skeletal and dentoalveolar relations and improvement in profile happens.

Enamel decalcification during orthodontics treatment is a serious clinical problem. Glass Ionomer is a hydrophilic compound that is able to release fluoride. Hence we assessed the amount of fluoride release from Glass lonorner type I (use in orthodontics banding) following refluoridisation in acidic and nutraI solution of NaF 0.2%.Materials arid In this experimental research, we chose Type I Glass Ionomer Cement which was built in Ariadent Factory, 30 disc shape compound in stainless steel casts with 6 mm diameter and 2 mm height according to manufacturer structure was prepared. Each sample floated in 5cc acidic and nutral 0.2% NaF solution and distillated water. We assessed the amount of fluoride in solutions by potentiometer method in 1st, 8th, 15th, 22nd and 29th and reported in ppm scale.
Maximum Fluoride releasing from the samples existing in the distillated water was in 8th day that descended during the first month, but maximum fluoride absorption in samples in acidic NaF solution was in first day that descended during the first month and maximum fluoride absorption in samples in nutral NaF solution was in 8th day that descended during the first month. Glass Ionomer cement can act as a chargeable fluoride releasing and absorption system also daily using acidic compound consisted of fluoride decrease surface hardness of glass ionomer. The amount of fluoride releasing and absorption of glass ionomer decrease rapidly in acidic solution that is not proper for long orthodontics treatments.

One of the important subjects in dentistry is oral habits which is a matter of concern for parents. Some scientists believe that the reason for starting and continuing oral habits can be due to psychological factors. Because the children's temper is related to the parents, it is possible that parents' personality characteristics would be related to creation of habits. The aim of this study was the evaluation of the role of mothers' personality characteristics on children's nutritive and non nutritive sucking habits. This cross-sectional study was done on seven year old girl students between 2006 and 2007 in Mashhad primary schools. A questionnaire was used including social history, questions about baby's oral habits and world standard psychological test (Eysenck). Overall 436 students were recruited. The data were analyzed through descriptive and Chi-square tests. There was a significant relationship between the history of pacifier sucking habit and mother's personality characteristics, Children with anxious and depressed mothers used pacifier more than mothers with normal personality, however thumb sucking and other oral habits (nail chewing pencil chewing ... ) were not related to mother's personality characteristics. Only the pacifier sucking habit was related to mother's personality characteristics.

This article is aimed at geometrical evaluation of antero-posterior displacement of incisor inferioris (Ii) and pogonion (Pog) following mandibular rotation and introducing a simple method to predict post surgical Holdaway ratio to evaluate the need for genioplasty. First the geometrical factors affecting the displacement of a landmark following the mandibular rotation are discussed; namely α (the amount of mandibular rotation), r (the distance of the landmark from the center of rotation), and θ (the angle of the radius of the landmark from true horizontal line), Then the amount of displacement is calculated as d=2r[sirt(α/2)sin(α/2+θ)]. Finally prediction method of post surgical Holdaway ratio is described as adding the amount of "d " for Pog and Ii to pre surgical Holdaway ratio. This ratio in addition to position of Pog relative to facial skelton was used to predict the need for genioplasty. The application of this method is also demonstrated on an open bite patient as an example and the outcome is compared with manual prediction method. The described method predicted the need for genioplasty the same way as manual prediction method. The geometrical prediction method can be of great value in determining the need of genioplasty following surgical mandibular rotation.

The use of lateral cephalometric radiography for evaluating cervical vertebral bone age is a method that can substitute for the hand-wrist radiography method. The aim of this study was to determine the correlation between the cervical vertebral bone age, chronological age and hand-wrist bone age. Lateral cephalometric and hand-wrist radiographs of 125 girls (8-13 wars) who needed orthodontic treatments were chosen. The dimensions of the 3rd and 4th cervical vertebral bodies were measured by a digital micrometer caliper with 0.02-mm accuracy and determined a regression formula to obtain cervical vertebral bone age. The data were collected and analyzed by a stepwise multiple regression analysis, and the results were compared with those obtained using the hand-wrist radiography method. Our investigation shows that the correlation coefficient between cervical vertebral bone age and hand-wrist bone age (0.734) is significantly (p<0.01) higher than that obtained for the relationship between cervical vertebral bone age and chronological age (0.367). The correlation between hand-wrist bone age and chronological age was 0.701. In addition, we show that the average difference (absolute value) between cervical vertebral bone age and hand-wrist bone age (0.71±0.59 years) is significantly (p<0.05) lower than that between cervical vertebral bone age and chronological age (1.27± 0.92 years).
By using lateral cephalometric radiography, it is possible to carry out a proper evaluation of skeletal maturity without any need for exposing the patient to extra radiation.

The premature loss of primary molars and the failure to protect this site during normal growth and developmental events may put the normal occurrence of occlusion at risk in the permanent dentition. Protection of dental arch relations in the premature loss of teeth can only be ensured with placement of space maintainers. The purpose of this study was to evaluate the clinical performance of Fiber Reinforced Composite resin(FRC) as a space maintainer. This study was conducted on 24 children applying 34 space maintainers. Old restorations in buccal surface were removed and grooves in mesiodistal direction were prepared on the decalcified or carious buccal surface of the abutment teeth. Teeth surfaces were etched, rinsed and dried. The required length of fiber was cut and then saturated with a few drops of bonding agent. The fiber was placed and a flowable composite was applied on the prepared grooves and fiber. The patients were followed up for 12 months. Our results showed that median survival time was 11.65 months and the success rate of FRC as a space maintainer was 88.24%. At the end of the study, there was no significant statistical difference between linear and angular measurements in initial and final casts (P>0.05). This study revealed that FRC can be an appropriate substitute appliance in preserving the space of the premature loss of primary teeth to prevent space loss.

Bent root forms are always a challenging point in an orthodontic treatment. The main aim of this study has been to assess the stress effects of a dilaceration in apical third of an upper central incisor in orthodontic movement. Three FEM models of an upper central incisor were designed with cortical and spongy bone, PDL, and teeth. The only difference between 3D models was the anatomy of the apical fourth of their root. A 30-deg (the first model) and a 60-degree (the second model) dilaceration in the apical fourth of the root were designed in a labial direction. The calculation was in ANSYS Workbench Ver. 11.0. A 1.0 N labio-palatal force was applied in 45 degrees to the horizontal plane in the labial side of the crown. Von mises stress was evaluated along a path of nodes starting at the mid root area at labial moving towards the apex and continuing to reach the mid root lingual region on root surface.
The apical stress did not show a dramatic increase in dilacerated form models starting from 0.11 MPa in normal model to 0.17 MPa in a 60-degree dilacerations model. Moving away from the apex, the stress findings increased which was noticeable between the normal model (0.48 MPa) and the 60-degree model (2.11 MPa). Based on the findings of this FEN! study, It was shown that the increase in the stress in areas away from the apex can be interpreted as the reason to the start of the external root resorption. There may be other models of the pointed apex root forms to show an increase in the apical area stress which was not the case in this model.

Supernumerary teeth occur in both the deciduous and the permanent dentition. Reported prevalence in permanent and primary dentition is between 1% and 3.5% and between 0.3% and 0.6%, respectively. Supernumerary teeth occur more frequently in the maxilla. The present case is extremely unusual in that a supernumerary premolar in the right maxilla distal to first molar is functionally erupted but caused impaction of second and third molars.

There is little information about the diagnostic ability of SNB and Facial angles in class II malocclusion. The aim of this study was to evaluate sensitivity and specificity of SNB and Facial angle in diagnosing anteroposterior position of mandible in patients with skeletal class II malocclusion. Pretreatment cephalograms of 76 patients with skeletal class II malocclusion were assessed in this study. Sensitivity and specificity of SNB and Facial angles were determined using SPSS and ROC (Receiver Operative Characteristics) curves. Sensitivity and specificity of Facial angle were 61 and 70 percent, respectively. The corresponding values for SNB angle were 40 and 86 percent. The highest sensitivity and specificity for SNB and Facial angles related to 75.5 and 79.5 degrees, respectively. The findings showed that in diagnosing mandibular anteroposterior position of class II patients, Facial angle is more sensitive and SNB angle is more specific. Moreover, it is suggested that in cephalometric analysis, patients with Facial and SNB angles less than 79.5 and 75.5 degree respectively, be assumed to have skeletal class II malocclusion.