Introduction: Beta-thalassemia major is a hemolytic anemia. If these patients are not treated, bone marrow hyperplasia will happen. Hematopoiesis in the jaw results in mandibular and/or maxillary enlargement. To our knowledge, there are few studies about frequency of Malocclusion in these patients. Therefore, this study was designed to investigate the frequency of Malocclusion in beta-thalassemia patients and compare it to healthy control group.Materials and Methods: This research was a cross sectional study. Seventy beta-thalassemia patients and 70 healthy controls (age and sex matched) were examined for Malocclusion using Angle classification, WHO Malocclusion classification, determination of overjet and overbite. If crossbite, spacing, openbite, crowding and mouth breathing were observed in clinical examination they were recorded. Statistical analysis was done using Chi-square and Variants analysis.Results: Beta-thalassemia patients showed class II Malocclusion (angle classification) and grade 2 (WHO classification) more than healthy control group. There were significant differences in angle & WHO Malocclusion classification between two groups (P<0.05). Increased overjet and mouth breathing were seen in patients more than healthy control group. There were significant differences in overjet and mouth breathing between two groups (P<0.05). There was a positive correlation between WHO Malocclusion classification and serum ferritin levels, but not between angle Malocclusion classification, overjet and serum ferritin levels.Conclusion: Beta-thalassemia major is associated with increased Malocclusion and these anomalies will occur if the patients are not treated early. Patients with Malocclusion should be visited and followed up by a dentist for dental problems. Fortunately, as a result of new treatments these patients live longer than before. Therefore, it is important to pay attention to their functional and esthetical problems.

Background and Aim: According to the importance of the harmony of teeth size in establishing a correct occlusion with appropriate overjet, overbite and molar and canine class I relationship, also considering the insufficient and contradictory previous studies in such a field, the goal of the current study was comparing the Bolton ratio between different Malocclusion groups.Material and methods: The Method of this study was descriptive and cross sectional. For this study 120 cast of orthodontic patients with permanent dentition were selected and divided to four equal Malocclusion group (Cl I, Cl II div1, Cl II div2, Cl III). There were 30 patients in each group. The largest mesiodistal width of the teeth of each cast was measured by caliper accurate to 0.1 mm from first left molar of the upper jaw to the first right molar of the lower jaw and Bolton ratio were calculated for each specimen. Then ANOVA statical analysis and chi-square test were done on data.Results: Bolton overall ratio in patients with class III Malocclusion was greater than patients with class I and II Malocclusion and this index in patients with class I Malocclusion was greater than patients with class II Malocclusion. But there were no significant differences between class II div1 and class II div2. Regarding the Bolton anterior ratio this index in patients with class III Malocclusion was greater than class I and II, and in patients with class I Malocclusion was greater than class II div1. But there were no significant differences between class II div1 and 2 and between class I and class II div2. The prevalence of discrepancies about Bolton overall ratio was 44.2% and about Bolton anterior ratio was 60% in sample population.Conclusion: Findings show highly prevalence of Bolton discrepancies in sample population. That means we should pay more attention on teeth size before orthodontic treatment

The role of pharyngeal space has been debated on developing respiratory problems and craniofacial deformities for many years. The purpose of this investigation was to find any differences in oropharyngeal dimensions between skeletal class I and class If Malocclusions.Eighty patients with class I Malocclusion (40 in 9-13 year & 40 in 18-30 year-old age groups) were compared to sixty patients with class Il Malocclusion due to mandibular deficiency (30 in 9-13 year & 30 in 18-30 year old age groups). Patients were selected from those who had no respiratory problems, facial asymmetry, aberrant growth pattern, parafunctional habits, TMJ diseases, vestibule-cochlear, visual & hearing disorders, hypertrophy of adenoids or tonsiles, previous orthodontic treatment or maxillofacial surgery.A lateral cephalogram in Natural Head Position was taken from every patient. Skeletal relationships of craniofacial structures and oropharyngeal dimensions were measured together with the soft palate. Hyoid bone and cervical column position Results indicated that:1- There was no difference in oropharyngeal dimensions, soft palate, hyoid hone and cervical vertehral column position between skeletal class I and class If Malocclusions in the normal respiratory pattern.2- Oropharynx showed some degree of growth in vrtical dimension during the growth period whereas  its sagittal depth remained mostly stable, except in the upper and lower border al class I Malocclusion (PNS-UPW: p<0.01, Spt-PSpt: P<0.03, Va-PVa: P<0.01).The hyoid bone showed down ward move while the posture of cervical column and facial growth had no change. Finally, Soft palate showed a significant increase in length (PNS-U: P<U.OI) at class I Malocclusion.