Evaluation of cephalometric changes in patients with class III malocclusion in mixed dentition period following face mask therapy and slow maxillary expansion

"nBackground and Aim: Among different treatments of patients with Class III malocclusion , orthopedic protraction of maxilla has been known as an effective method in mixed dentition period. The aim of this study was to evaluate the cephalometric changes of Cl III patients in mixed dentition period following face mask therapy and slow maxillary expansion. "nMaterials and Methods: This was a before-after study which was conducted on 10 children in mixed dentition period, who had class III malocclusion and maxillary deficiency according to the Stiener and Mc Namara's analysis. The patients were all treated by protraction face mask and slow maxillary expansion. The cephalometric changes of maxilla , mandible and dental relations during the treatment were analyzed by Paired sample T Test. P<0.05 was considered as the level of significant. "nResults: The overjet increasement was 1.7mm. Co. ANS distance improvement was 5.6mm, Ptm.ANS distance increasing was 3mm, and ultimately improvement of Gf.s distance was 1.5mm which were all statistically significant (p<0.05). "nConclusion: Based on the results of this study, face mask therapy with slow maxillary expansion is able to improve the horizotal position of maxilla, in patients with Cl III malocclusion , in mixed dentition period

Examination of third molar Missing in skeletal Cl I , Cl II in Tehran dental school patients during

"nBackground and Aims: One of the common human evolutionary anomalies is dental Missing. Evolution of dental system is toward deduction of teeth number. The Missing of third molar is interesting subject for dentists and genetic researches because of its variety in different races. Consideration of bilateral effect of third molar Missing with jaw relation is an important subject. The aim of this study was to evaluate the third molar missing in Cl I and Cl II skeletal (without rotation) and comparison of them together. "nMaterials and Methods: The patients of the orthodontic department of school of Dentistry (Tehran University of Medical Sciences) were analyzed. About 121 patients had Cl I and 60 patients had ClI jaw relation. This relation identified based on cephalometric lateral radiographic ANB corner angle. Patient who had rotation in maxilla or mandible based on SN-Go Gn angle were excluded. The incidence of third molars agenesis in individual dentition quadrants, upper and lower jaw and right and left side of dentition was examined from panoramic radiography. AChi-square test was used for statistical analysis of data. "nResults: Missing of one or more third molar in skeletal Cl I and Cl II was 43% and 33.3%, respectively. Missing of one or more third molar in Cl II was fewer than Cl I, but no statistically significant differences were seen between them. "nConclusion: There was not a direct relationship between jaw relation and third molar Missing

Effect of Fast Curing Lights, Argon Laser, and Plasma Arc on Bond Strengths of Orthodontic Brackets: An In Vitro Study

Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek) were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland), the argon laser unit (Bo-5, Iran ), and the plasma arc unit (Remecure 15, Belgium). The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek). After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany).Results: The mean bond strengths was 17.344 MPa (SD=4.567) for halogen 19.172 MPa(SD=6.328) for laser and 19.322 MPa (SD=4.036) for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light