Iranian Journal of Orthodontics
Volume:6 Issue: 1, Mar 2011

Aim: Friction accompanies all sliding techniques. Sliding is in the manner of tipping and uprighting with increasing angle between bracket and wire. Recently, wire coating with the different nanoparticles has been proposed to decrease the frictional forces. The present study was done to coat the stainless steel wires with the ZnO nanoparticles and determine the effect of this coating on friction reduction during different angle between the wires and brackets.
Eighty pieces of 0.016 stainless steel wires with and without zinc oxide nanoparticles were used in 80 pieces of orthodontic brackets (0.018). The coated wires analyzed by the SEM and XRD observations. Friction between the wires and orthodontic brackets at 0,5,10 degree angle were calculated using universal testing machine. Two and three group comparisons were done by means of Student t and one-way ANOVA respectively and Tukey post hoc test was used to assess the paired comparisons.
Frictional values were significantly increased with the increased angles between the wire and bracket. the increased friction force from 0 to 10 degree in uncoated wires were Statistically more significant than increased friction force from 0 to 10 degree in coated wires (p considering the positive effects of zinc oxide nanoparticles coating in decreasing frictional forces, they might offer a novel opportunity to significantly reduce friction during sliding and consequent better anchorage control, reduced risk of root resorption.

Obstructive sleep apnea (OSA) is a physical disorder that leads to repetitive obstruction of upper air way, causing in 30 or more apneic (the pause of airflow at the mouth and nose for more than 10 seconds) episodes during sleep. It is caused by the repeated collapse or narrowing of the pharyngeal walls due to partial or complete obstruction of the upper airway. Treatment for sleep apnea include weight loss, keeping off alcohol, positional therapy, oral appliances, continuous positive airway pressure (CPAP). Oral appliances have proven to be useful, noninvasive and easy to use. Patients prefer oral appliances and mandibular advancement appliances to CPAP. Our study concluded that oral appliances may assist in the management of OSA.

Aim: the prevalence of maxillary missing lateral incisor (MMLI) is 1-2% which is responsible for 20% of all missing teeth. Increased knowledge of causes and clinical manifestations of cases with this situation can be helpful in their diagnosis and treatment planning. The aim of the present study was to determine dental and skeletal features of patients with missing of maxillary lateral incisors.
The material consisted of pre-treatment dental casts and cephalograms of 26 patients (14 females and 12 males with average age of 17.5) with unilateral or bilateral MMLI. The following parameters were measured on the dental casts: the maxillary and mandibular intercanine width (ICW) and intermolar width (IMW), overjet, overbite, missing or anomalous of other teeth. Parameters that were measured on cephalogram including: SNA, SNB and ANB angle and Wits. The parameters were finally compared to a control group with normal occlusion by means of paired t-test.
Eight subjects out of 26 patients with MMLI had bilateral missing and from 18 subjects with unilateral missing, 66.67% (12 subjects) had lateral missing on the right side. MMLI was associated with other anomalous or congenital tooth absence in 12 subjects. In comparison with control group, the overjet was significantly lesser (p Missing of maxillary lateral incisor was highly correlated with other tooth anomalies. Most of patient with this situation had skeletal and dental Class III tendency.

Aim: The main objective of this preliminary study was to introduce a new approach for the estimation of nasal cavity volume using two dimensional measurements in serial sections, as an alternative to planimetry volume measurements.
Ten CBCT images were studied in the coronal plane and the 4-mm thick sections were selected between Anterior and Posterior Nasal Spine. Real estimation of nasal cavity volume was computed using Cavalieri principle in conjunction with planimetry method. The outline of each slice was digitized and the resulted surface area was computed by AutoCAD software. In alternative method, a surface area estimate was measured by multiplying maximum width and maximum height in each slice. The sum of slices area in each method was named as Total Nasal Cavity Area (TNCA). Nasal cavity volume = TNCA × thickness of tomography slice. TNCA1 based on planimetry method, was compared with TNCA2 using to coordinates with linear regression analysis.
Regression analysis showed a powerful correlation between two methods measurements (r = 0.951). The following formula was proposed for volume estimation using the coordinate TNCA1 = 85.6±1.53 TNCA2.
In this pilot study, we substituted successfully two linear measurements instead of planimetry to estimate nasal cavity volume. This may help investigators to overcome inherent problems appearing in measurements of nasal cavity volume.

Aim: Anchorage management is a challenging problem while retracting anterior segment in orthodontic treatments. The purpose of this study is to evaluate the effect of anterior teeth labiolingual inclination on the amount of anchorage loss and distance of anterior retraction.
Methods and Materials: Six 3D computer models of an upper anterior segment were designed in SolidWorks 2006 (SolidWorks, Concord, Massachusetts, USA).The models contained supporting structure, upper central and lateral incisors, their PDLs, the brackets and an anterior retraction arch wire with two vertical open loops. The models were the same except for the torque of anterior teeth which were 0, 5, 10, 15, 22, and 35 degrees consequently. ANSYS Workbench Version 12.1 (ANSYS Inc., Southpointe, Canonsburg, PA, USA) was selected for the analysis. At each analysis, the end points of the arch wire were displaced distally simulating the anterior retraction arch wire activation. The displacement produced in the labio-mesio-incisal point angle and the mesializing force applied to the terminal molar was assessed.
Torque degree of 0 to 22 exerting almost equal force on anchorage unit during retraction while 35 degrees of torque causing more reciprocal force. Ten degrees of anterior torque resulted in maximum displacement of anterior segment.
To have maximum anchorage and faster anterior teeth movement during retraction degree of torque suggested to be about average and neither too protruded nor uprighted.

Background and Dental impressions often carry microorganisms that may cause cross infection from patients to dental staff. The purpose of this study was to evaluate the disinfecting efficacy of three commercially available disinfectants on Staphylococcus aureus.
Methods and subjects: Impressions were made of a sterile metal model of the maxillary arch that had been contaminated with Staphylococcus aureus. The Impressions were cultured before and after immersion in one of the following disinfectants: 15 minutes in Micro 10⁺ (5%), 5 minutes in Deconex (2%) and 10 minutes Glutaraldehyde (2%).
Kruskal-Wallis test was used to evaluate the colony forming units (CFUs) of Staphylococcus Aureus.in each of the three groups. The same test showed that the colony forming units (CFUs) were reduced to Zero by all disinfectants.
This study showed that all disinfectants were fully successful in complete removal of Staphylococcus Aureus.

Aim: culture of human preiodontal mesenchymal stem cells to production osteoblast. This might be used for repair of human periodontal defects in future.
periodontal tissues were obtained from periodontium of patients who were candidate for periodontal surgery. They were 25-45 years old and had no systemic diseases, no smoking, and no drug treatment. Tissues were cultured in DMEM medium. Cells were by subsequently expanded by passages. 3 passages were done. Then cells were evaluated by inverted microscope and flowcytometry. We stained PDLstem cells with these markers: CD44, CD90 CD166,CD13, CD34,CD45 .
Finding: PDL stem cells expressed MCSCs markers as shown in flowcytometry. The cells were negative by CD34 and CD45 markers and were positive by CD90, CD166, CD13, and CD44 markers .We saw a monolayer attached cells on the floor of flask macroscopically and we saw spindle cells by inverted microscope. In the microscopic finding we saw nuclear red calcified view with Alizarine staining in day 14th of culture.
Our findings show that human PDL contains a population of multypotent postnatal stem cells can be isolated and expanded in vitro. It provides a reservoir of stem cells from an accessible tissue resource. These cells have capacity of proliferation ex vivo. Therefore tissue regeneration mediated by human PDL stem cells might have potency of practical cellular- based treatment of periodontal defects.

Supernumerary tooth is a rare event, which is usually found coincidentally in radiographic examination. The prevalence of this event is 1-3% with different prevalence for primary and permanent dentition. Supernumerary teeth may cause various clinical problems including: delayed or failure of eruption, displacement or rotation of permanent teeth and cyst formation. The purpose of this study was to present the case of a 9-year-old boy who had a large dentigerous cyst around his primary mandibular left premolar that was enucleated with the tooth. A year after this enucleation, we have observed a supernumerary tooth in mesial of canine. It is a reasonable question that “can the supernumerary tooth formation relate to the dentigerous cyst around impacted tooth?” Therefore, it is necessary to perform more pathological investigation in this aspect to answer this question.

One of the most important characteristic of dentition is dental arch form. In orthodontic treatment, it is crucial to understand each individual dental arch for diagnosis and treatment planning and try to preserve it throughout the treatment to achieve a higher stability. Additionally, it is important to maintain a wellestablished coordination between maxillary and mandibular dental arch to have a perfect functional occlusion. In orthodontics up to now, different definitions have been proposed for human dental arch form and methods for coordinating dental arches. The aim of this study was to gather and compare these concepts. The available data were categorized and discussed in five different domains: Arch Form (history and recent concepts), Factors affecting dental arch form, Characterization of arch form, Coordination of upper and lower arches and arch wire selection and arch form.

Aim:Assessment of patient''s motivations requesting orthodontic treatment can help clinicians in meeting the needs and expectations of patients and attain a successful treatment result. The present study was carried out in 2008 to provide data regarding motives of patients coming to specialized orthodontic clinics of Qazvin for treatment.
In this descriptive study, 300 patients aged 12 years old and more (27.3% males, 72.7% females, the mean age: 19.61 years) were studied. Age, gender, parents’ level of education, and father’s occupation, motives for improving teeth and face components; and the location of pain and discomfort were evaluated. The correlation between motives and different socioeconomic factors were assessed using Spearman and Pearson correlation coefficients.
Alignment of the anterior teeth was the most frequent motive regarding the teeth (89.3%). However, for face components ,it was improving teeth and gingival view during smiling (18.7%). Significant correlations were noted between patients'' gender and motivation to align anterior teeth (p Alignment of anterior teeth and improving the teeth or gingival appearance during smiling were found to be major motives for requesting orthodontic treatments.

Patients with midline or generalized diastema can be managed successfully by multidisciplinary approach. Our patient was managed by orthodontic, prosthodontic and restorative procedures. After orthodontic treatment, maxillayr labial frenectomy was done for this patient to reduce the possibility of relapse. Restorative treatments were also performed to close the remaining spaces. After all, a fixed prosthodontic bridge was constructed to close the remaining posterior space.