Iranian Journal of Orthodontics
Volume:5 Issue: 3, Sep 2010

Aim: Sliding a tooth along an archwire involves a frictional force, causing a number of adverse effects like anchorage loss, excessive orthodontic forces, prolonged treatment time and damage to the roots. This is especially true in ceramic brackets where the friction is notoriously higher.Recently, wire coating with the different nanoparticles has been proposed to decrease the frictional forces. This study evaluated the friction force created between stainless steel archwires coated with ZnO nanoparticles and ceramic brackets in vitro.
Friction tests simulating archwire functioning of the coated and uncoated wires and ceramic brackets were carried out by an Instron machine.Control and case groups included uncoated and coated 0.019×0.025 stainless steel wires respectively. Coating was preformed by inserting stainless steel (SS) wires into solutions of ethanol zinc oxide. The adhesion properties of the coated wires after friction were analyzed by SEM (scanning electron microscope).The frictional forces were compared usingMann-Whitney test.
In the control group (porcelain brackets uncoated stainless steel wires) the mean friction force was 2.59 ± 0.37N whereas in case group (porcelain brackets coated stainless steel wires) the mean friction force was 2.54 ±0.32 N. Although the friction force in coated wires was lower than uncoated wires; the difference between two groups was not statistically significant. (p=0.62).
coating of stainless steel archwires with ZnO nanoparticles did notcause significant reduction in frictional forces between stainless steel arch wires and ceramic brackets.

Aim: Hearing impairment is one of the associated problems to cleft palate; although it affects language development, it has rarely been noticed in literature. The aim of this study is evaluating cleft palate patients’ hearing condition and the relationship of different incorporated elements with their hearing.
Forty-two patients with cleft palate (23 males and 19 females) were selected among patients referring to orthodontic department of Shahid Beheshti university and Nime Sha’ban dental clinic of Kerman, their files were surveyed according to audiometric and tympanometric tests (A,B and C). Likewise the relationship of other factors including age, gender, type of cleft (unilateral, bilateral), history of previous reconstructive surgery and presence of oronasal fistula were studied on hearing. Chi-square and t-tests were used to analyze the data.
Twenty-three patients (54.7%) had one ear or both ears mild conductive hearing loss; and tympanogram-B was observed in 38 ears from 84 ears. These disorders were mostly observed in younger patients. Gender and type of cleft had no relationship with hearing condition. The average of hearing threshold in patients who had cleft palate surgery and patients without oronasal fistula was lower than other groups.
Hearing problem was observed in more than %50 of the studied patients; which determines the need for proper examination and diagnosis following by predetermined treatment protocols.

Aim: The main goal of thisstudywas to evaluate orthodontic treatment needs (IOTN) ofschoolboys population of Isfahan in 2009-2010based on Index of Orthodontic Treatment Need (IOTN).
In this study an examiner used the Dental Health Component (DHC) and Aesthetic components (AC) of IOTN to assess Orthodontic treatment needs for 400 Isfahan schoolboys. Multistage randomized cluster sampling method was used to choose the participants. All the participants were schoolboys aged 11 to 14 years. Using the IOTN, Malocclusion was determined. To evaluate the data a chi-square test was carried out.
Taking into account DHC, 3.5% of Isfahan schoolboys were in ''Extreme need'', 14% in ''Severe need'', 25% in ''Moderate need'', 38.5% in ''Little need'' and 19% had ''No need'' to orthodontic treatment.In evaluating AC, 77.5% had no need or little need, 16.5% had moderate need and 6% had great need to treatment group.
It was concluded that 17.5% of 11-14 year-old male students in Isfahan need orthodontic treatment (IOTN grades 4 and 5) and common deviations in this group were impaction, hypodontia and contact displacement.

Aim: Infectious complication which is reduced by chlorhexidine application may contribute to immediate orthodontic miniscrew failure. This study was determined to assess the influence of this agent on miniscrew immediate failure rate.
The study sample consisted of 62 miniscrews inserted in 31 patients that their treatment plan consisted of placing one miniscrew on each side of their maxillary arch between first molar and second molar (2 screws for each patient). Fifteen patients were given a chlorhexidine regimen.
In the first six weeks after miniscrew insertion and before their loading 13.33 % of miniscrews in chlorhexidine group failed but the failure rate in non-chlorhexidine group was 6.25 %. According to Fisher''s exact test the difference in failure rate was not statistically significant. Also there was no significant relation of failure rate to any category of the measured insertion torques or placement side (left or right) of miniscrews.
Using chlorhexidine does not affect the miniscrew immediate failure rate. Also, insertion torque value and placement side (left or right side of the jaw) in the maxilla do not seem to have influence in miniscrew failure rate.

An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical equation to bring about a relationship between the L-loop height, width, activation and the produced force.
Six 3D finite element models were designed for L-loop without preactivation bends. Loops were designed with different widths (w) and heights (h). The cross section of wire was 0.016”× 0.022”. The distal end of each model was activated 1 mm in 0.1 mm intervals. The force produced by activation in a 0.1 millimeter increment was recorded.
Force findings were different according to the loop parameters defined. The produced force varies from 0.106 to 0.228 N for a 0.1 millimeter of activation and increased from 1.07 to 2.27 N in 1.0 mm of activation.
The magnitude of force by L-loop can be estimated through adjustment of vertical part and activation as Increments of activation increased the delivered force while Increasing Lloop height decreased the generated force.

Aim: The goal of this research was examination of agreement between analysis of Hand wrist bones and cervical vertebrae to determine the skeletal age and patient’s growth value in 8-18 years of Iranian children referred to the department of orthodontics, faculty of Dentristy, Tehran University of Medical Sciences.
A group of 123 subjects, in accordance with specific treatment design for these patients, performed right hand wrist and lateral cephalograms. Bones evolutionary stages of hand wrist examined based on Grave & Browns and Bjork methods in 9 phase and in 7 regions of hand and wrist. Evolutionary stages of cervical vertebrae determined based on Baccetti method by using from sight or aspect trunk of 2,3,4 vertabrae in 5 phase. These analyses repeated 6 month later. . Kappa Correlation index used for comparison of two used method in order to determine stage of skeletal maturity in general sample.
Results and correlation value in these two methods was weak to determine the skeletal age by analysis of Hand wrist radiography and cervical vertebrae. These cannot be considered as the alternate to determine skeletal age and growth peak with each other.

Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. It has therefore been recommended that CBCT be used in selected cases in which conventional radiography cannot supply satisfactory diagnostic information; which include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and planning orthognathic surgery. The need to use in other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations.

Aim: Tooth size in panoramic view has both magnification and distortion. It is supposed that panoramic view generated from Cone Beam computed tomography (CBCT) has more accurate tooth size compared with conventional panoramic view. The purpose of this study was to compare magnification of mandibular tooth size in digital panoramic radiographs andCBCT reconstructed panoramic images.
Amongpatients referred to Hamadan dental school, having both digital panoramic radiograph and CBCT, 28 patients were selected. Maximum width and length of mandibular teeth No. 36,34,33,31,41,43,44, 46 were measured in digital panoramic views and in CBCT reconstructed panoramic views. The CBCT images in multiple planes were used to give the dimensions referred to as gold standard. MANOVA test, Post Hoc and Tukey were used for statistical analysis.
There was a significant difference in width and length of teeth between digital panoramic view and both reconstructed panoramic view and gold standard (P value 0.05).
CBCT reconstructed panoramic views show significantly less magnification regarding tooth size compared with digital panoramic views.

Aim: Occlusal indices used to determine orthodontic treatment needs cannot include the patients’ perception about their need for orthodontic treatment. That is why in some cases, these indices show that a particular patient needs orthodontic treatment while the patient feels no such need. This study was carried out to compare normative and self-perceived orthodontic treatment needs of 11-14 year-old school children.
In a descriptive cross-sectional study 250 children of 11 to 14 years old were selected randomly. The scores of the Aesthetic Component (AC) of IOTN, were determined by specialist and the children themselves. The Dental Health Component (DHC) of IOTN was also assessed. Statistical analysis used: correlations between the AC of the patient, AC of the specialist and DHC of the specialist were assessed using Spearman’s rho correlation coefficient.
The mean of patient’s AC and specialist’s AC were 2.556 and 4.308, respectively, while the mean of specialist’s DHC was 2.60. The correlation coefficient between patient’s AC and specialist’s AC was 0.281, between specialist’s AC and DHC was0.549 and between patient’s AC and DHC was 0.210. The highest correlation was seen between specialist’s AC and DHC and the lowest correlation was seen between patient’s AC and DHC.
The significant positive relation between the AC indices and the DHC indicates their ability to determine the need for orthodontic treatment. The highest need for orthodontic treatment was determined by specialist’s AC and the lowest was patient’s AC.

as regards to prevalence of mouth breathing and its complications, The panoramic view of children with mouth breathing as a routine initial accessible radiographic examination, was assessed in the present study; considering Confounding factors such as the magnification, dimensional changes, type of the x-ray machine and head position during imaging. We tried to innovate new standardization of nasal cavity analysis in panoramic radiography, in addition to creating specified and reliable new parameters, and investigate if there are significant differences between these parameters in mouth breathing patients than in those with nasal breathing.
This wasa control and analytical study which assessed 30 patients with Mouth breathing and 30 patients with nasal breathing, in the range of 9-12 years old with equal numbers of both sexes, in both groups. After tracing panoramic radiographs, five angular and proportional variables was created and measured, T-test was performed and the level of significance was evaluated. For investigation of nasal septum deviation, we used Chi-square test.
«NL» and «NL/B» parameters and unclear irregular view ofnasal cavity ininternal structures, showed significant differences in mouth breathing group (P. Value Due to availability and benefits of panoramic radiography, the proportional and angular parameters used, were reliable for assessment of nasal cavity in mouth breathing children and could be developed in future studies for diagnosis of mouth breathing children.