Iranian Journal of Orthodontics
Volume:2 Issue: 3, Feb 2007

Apert syndrome is a congenital disorder characterized by craniosynostosis, maxillary hypoplasia, mental retardation, mid-facial malformations, and syndactyly. The developmental disorder is inherited in an autosomal dominant manner, though most cases are sporadic. Approximately 75 percent of Apert's patients suffering from dental anomalies suffer from cleft palate or bifid uvula. Cleft palates are common congenital disorders of the upper mouth, and occur when the palatal plates fails to join together during the second month of fetal development. This research paper focuses on the roles played by the craniofacial team in the management of secondary palates in children with Apert's syndrome.The consequences of Apert's disorders can be severe, long lasting, and sometimes incomprehensible even to the sufferers. But this study has aptly shown that the suffering can be averted, especially if proper corrective strategies are taken as early as possible. However, these strategies must fundamentally revolve around a multidisciplinary approach to sufferers of Apert's syndrome. This study looks into the roles played by the craniofacial team in the management of Apert-related complications such as Cleft lips and palates. The team is made up of the geneticist, speech language pathologist, audiologist, plastic surgeon, dentist, and orthodontist

Light cure composites are routinely used to attach orthodontic brackets, so bond strength and cure time must be considered. Ilowever, the disadvantages of the conventional halogen apparatus include heat and lengthy composite curing. Therefore, the purpose of this study was to compare shear bond strength of orthodontic brackets composite cured by plasma arc (PAC), conventional halogen (QTII), light- emitting diode (LED) and self-cure. In this in vitro study, sixty premolar teeth extracted for orthodontic purposes from patients tinder 18 years of age were collected and divided into four equal groups. In the first group, the brackets were bonded by self-cure composite. In the second, third, and fourth groups, they were bonded by halogen, LED and plasma arc, respectively. The samples were thcrmocycicd and finally the force required for brackt failure was measured. Shear bond strength was obtained by dividing the exerted force by the bracket base surface. AR1 (Adhesive Remnant Index) and EDI(Enamel Detachment index) were also evaluated. Data were analyzed by ANOVA followed by TUKEY test.
Average shear bond strengths were 14.7±5.4 MPa in the self—cure group, 14.6±5.3 MPa in the halogen group, 14.7±4.5 MPa in the LED group, and 14.2±5 MPa in the plasma group. There were no significant differences among the groups. EDI and AR1 did not differ between the light-cure and self-cure groups.
No significant difference was observed in shear bond strength among different methods of composite curing. Therefore, despite the high cost of plasma arc, it is recommended in order to reduce operation time.

Class Ill skeletal deformity may be the result of mandibular prognathism and/or maxillary deficiency. In adult patients , orthognathic surgery is used for treatment. Historically, the surgical correction of class III deformities was achieved just by mandibular setback, but nowadays other methods of surgery are used. Orthosurgery treatments, in addition to improvement in masticatory function, occlusion and esthetics, may lead to changes in upper airway dimensions, position of hyoid, tongue and soft palate. The purpose of this study was to evaluate cephalometric changes in upper airway dimensions of skeletal class III patients following orthodontic treatment and bimaxillary surgery.
In this retrospective study, pre-treatment and post-treatment (6-12 months after surgery) lateral cephalograms of skeletal class III patients were used for analysis. All of the patients of a private office in Hamadan who had the inclusion criteria were selected. Cephalograms were traced manually. All the measurements were done with ruler.Then paired t test was used for analysing the data.
Changes in upper airway linear measurements, position of hyoid, base of tongue, soft palate size and angle. and craniocervical angle, were not statistically significant (p>0.05). But there was a significant increase in nasopharynx and oropharynx surface area (p<0.05).
Orthodontic treatment with bimaxillay surgery in surgical class III cases can increase surface area of oropharynx and nasopharynx, and it seems that there is no risk factor for breathing disorders.

Orthodontic treatment outcomes are combination of advantages and disadvantage. The force implied during treatment could affect dental pulp status. Amount of changes in pulp complex depend on the types of tooth movements and whether the apex is open or not. The aim of this study is to compare the effects of different orthodontic tooth movements in two kinds of open and normal apices by 3D Finite element analysis.
Two three-dimensional Finite element models of an upper central incisor were modeled based on average dimensions. The models contained cortical and spongy bone, uniform thickness PDL of 0.25 mm and an upper central incisor. The differences between the models was the apex development which was complete in the first model and open in the second one in Solid- works 2006 and transferred to ANSYS Workbench Ver. 11.0. Different force systems to produce tipping, bodily and intrusion were applied in the tooth crown. The Von Mises stress was assessed along two defined paths.
Maximum amount of the stress along the long axis of pulp belonged to open apex by tipping movement then intrusion with normal apex and finally bodily movement in open apex samples. In evaluation as regard of stress along apical third of PDL the highest stress created by intrusion in normal apex group.
In open apex, tipping and bodily movement could induce much more stress and in normal apex the concern of root resorption by intrusion was more than other types of tooth movements.

A complete knowledge of bone healing is a prerequisite to many decision makings in dentistry and is considered as a basic event in some research strategies. Any method that can accurately monitor the healing process is important to clinician providing the information required for further treatment planning. Our study shows a simple and reliable method to evaluate the events that occur during socket healing in rats. Thirty five "Sprague - dawly" male rats were selected. All rats were anesthetized with intra peritoneal injection of Ketamin 10% and Xylazine 2% at the dose of 2 mUkg on day I. Mandibular left first molars were extracted with the use of very small excavator and hemostat forceps. At the same day,7,14,21,28,45 and 60 days after extractions, five rats were sacrificd, the left mandibles were removed and placed into 10% Formalinc. Muscles and gingival tissue were dissected away the Following day and the mandible was placed on a radiographic film and the buccul views were taken. The radiographs were scanned and analyzed with Avcnd (program that designed in matlab 6.1). Increased density of the image of apical and crestal areas of the socket was observed on day 7. The maximum density of apical area was reached on day 28 and preceded towards crestal area on day 60. Density increasing in the crestal area is slower than apical area. Densitometrie evaluation of extraction socket healing using Avend program is useful and reliable to objectively assess bone formation and mineralization.

In spite of the continuous interest of orthodontists in the effects of soft tissues on dental and skeletal structures, this influence is not well clear. The purpose of this investigation was to clarify the effect of open lip posture on selected dentoskeletal features of growing children. In this cross sectional study, 193 pupils (99 girls, 94 boys) with age range of 9 to 13 years were participated. All patients were examined by a trained investigator and those having incompetent lip seal were selected and their dentoskeletal features were compared with a control group consisting of 36 subjects with normal occlusion. The data were analyzed by independent sample t-tests. Among the 193 students examined in this study, 19 cases (10%) were diagnosed as having lip incompetence. A more open lip posture was associated with an increase in overjet, lower incisor inclination and Palatal plane to Mandibular plane angle (p<0.05); while Interincisal angle was significantly decreased in this group compared to control subjects (p<0.05). The amount of overbite and upper incisor inclination were not statistically different between the two groups (p>0.05). The data from this study suggest that lip incompetence may have a significant environmental effect on dentofacial structures. Since lip seal assessment can be achieved simply by practitioners, parents or teachers, it is suggested that adults observe and provoke children to maintain appropriate lip posture.

There are significant differences in morphological features of various racial and ethnic groups. The purpose of the present study was to identify cephalometric norms of Tweed diagnostic facial triangle in North East adolescents of Iran and to evaluate the effect of sexual dimorphism on cephalometric criteria of this population. The sample comprised lateral cephalograms taken in natural head position of 40 pupils with normal occlusion (20 girls, 20 boys). Tweed diagnostic triangle was traced on each cephalogram and its angles were measured to the nearest 0.5°. The data were analyzed by SPSS software using independent samples t-tests and liotelling's test . The lower incisors were significantly more proclined and mandibular plane was significantly steeper in north eastern Iranians compared to Caucasians (p<0.00 ). The average FMIA angle was significantly smaller than 65° as proposed by Tweed (p<0.001). There was no statistical difference in mean values of the three angles between boys and girls (p>0.05). There are significant differences in cephalometric norms of Tweed triangle between Iranians and Caucasians, showing important implications in orthodontic treatment planning. With respect to the significant differences in cephalometric norms of Iranians and Caucasians, it seems necessary to use standards of each racial group for orthodontic diagnosis and treatment of malocclusions in that population.

There are few studies on the electrochemical corrosion behavior of Nitinol at various pH and temperature. Considering the pH of mouth can alter at a wide range, the present study investigated the effects of various pH and temperature of artificial saliva on the electrochemical stability of commercial equiatomic Ni-Ti orthodontic wire. In this manner, cyclic polarization tests were performed at different temperatures and pH. Surface conditions of wires were evaluated with Scanning-Electron Microscopy. Decreasing of pH to the acidic pHs and increasing of temperature in these pHs cause to increasing of Igor, and C.R. and decreasing of E, and Epit. The SEM micrographs indicate that the surface of sample become smoother after cyclic potentiodynamic tests. In fact, cyclic potentiodynamic tests cause to a general corrosion on the surface of sample. Corrosion behaviour of NiTi completely relies on the characteristics of its passive layer. Decreasing of pH causes to partly dissolution of the passive layer of NiTi in the acidic pHs. Influence of temperature on the corrosion behaviour of NiTi, related to the pH of solution. It appears that pitting critical temperature of NiTi in the artificial saliva is higher than 42 ̊C.

Despite a substantial body of literature refuting an association between third molar eruption and crowding of the lower anterior dentition, the issue continues to be controversial. This study sought to assess the correlation between angulations of impact mandibular third molars and anterior crowding of the lower arch. 127 patients were examined in this analytical-descriptive study. Clinical and paraclinical records were obtained to assess different impaction angulations and the rate of crowding. Patients with history of previous extractions, orthodontic treatment, Bolton discrepancy and skeletal orthodontic malformations were excluded. Kruskal —Wallis test was used for statistical analysis. Of the 127 patients studied, mcsioangular impaction was observed in 61 patients (48%). This study showed no significant correlation between different angulations of mandibular third molar impaction and crowding (P>0.05). This study seems to confirm that the role of the lower third molars is not a significant factor in causing late anterior crowding.

To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of Iranian (Yazd) population with that of the study of Tanaka and Johnston. Teeth on study casts of an unselected sample from a 11 to 25 years old (n 120; 60 males and 60 females) were measured in the mesiodistal dimension. An Iranian mixed dentition analysis based on the Tanaka and Johnston method was constructed with new linear regression equations for prediction of the mesiodistal widths of unerupted canines and premolars. Digital calipers were used to measure the mesiodistal widths of all teeth on study models fabricated from alginate impressions. The predicted widths of the canines and the premolars in both arches were compared with the actual measured widths. Sexual dimorphism was evident between Iranian (Yazd) males and females in incisors, canines, and premolars in the mesiodistal dimension. To predict the space (in mm) required for alignment of unerupted canine and premolars in Iranian(Yazd) children, divide the sum of the mesiodistal dimensions of the four mandibular incisors by two and add the respective constants for males (upper, 12.91; lower, 10.51) or females (upper, 9.09; lower, 8.22).