Showing 5 results for Yassaei
A. Khavari , S. Yassaei ,
Volume 14, Issue 4 (10 2002)
Abstract
The purpose of this study was to investigate the soft tissue profile changes of the lower face following premolars extraction and incisor retraction. In order to do that, pre-and post treatment lateral cephalometric radiographs of 40 female orthodontic patients, with cl. II div. I malocclusion (22 patients) and bialveolar protrusion (11 patients) were analyzed. At beginning of orthodontic treatment, their mean age was 18.10 years, ranging from 15-24. All cephalometric radiographs were analyzed by a conventional and confirmed method called "combination analysis". The findings revealed that "lip tension" is a significant factor in soft tissue response to orthodontic treatment, so that in patients with lip strain, nasolabial angle increase was significantly more that those without lip strain. Moreover, regarding the increase of vermilion thickness of the upper lip, a significant difference was observed between two groups. In patients with lip strain, following premolars extraction and incisors retraction, lip strain was reduced or eliminated and upper lip vermilion thickness increased, following incisors retraction, the slope of nasal inferior border, in the group with lip strain, was reduced, while in the group without lip strain, this slope increased.
S. Yassaei , Mm. Soroush ,
Volume 19, Issue 4 (6 2007)
Abstract
Background and Aim: Unlike other bones of the head and neck, hyoid bone has no bony articulations. It is connected to mandible, cranium and pharynx through muscles and ligaments. During treatment with functional appliance in patients with class II div1 malocclusion, mandible is positioned in inferior and anterior direction. Regarding the relation between hyoid and mandibular bone, alterations of hyoid bone position can be a result of functional appliance therapy. The aim of this study was to evaluate the changes of hyoid bone position following treatment with Farmand functional appliance in patients with class II div 1 malocclusion.
Materials and Methods: In this before-after clinical trial, 28 patients with class II div 1 malocclusion which were under treatment with Farmand functional appliance for 11 months were selected. Facial growth in vertical, normal or horizontal direction was determined by cephalometric measurement. Data were analyzed with Paired-t test to compare the differences of mean values pre and post treatment. Variance analysis was used to compare the three growth patterns. P<0.05 was considered as the limit of significance.
Results: Hyoid bone shifted significantly forward in horizontal dimension (P<0.01) and non-significantly upward in vertical dimension. There was no significant difference among the three studied groups with respect to hyoid bone position alterations in horizontal dimension but significant difference was observed between horizontal and vertical growth pattern in vertical dimension (P<0.05). There was significant correlation between decrease of ANB angle and forward movement of hyoid bone.
Conclusion: Based on the results of this study, treatment with Farmand functional appliance (Fa II) leads to significant alterations in the position and anterior displacement of the hyoid bone.
Ar. Davari , S. Yassaei, Ar. Danesh Kazemi , Mh. Yousefi ,
Volume 19, Issue 4 (6 2007)
Abstract
Background and Aim: With the introduction of different bondable restorative materials in dentistry, various methods have been suggested to enhance the polymerization and shear bond strength of these materials. The aim of this study was to determine the effects of different methods of enamel conditioning on bond strength of orthodontic brackets and on the bracket/ adhesive failure mode.
Materials and Methods: In this experimental in vitro study, brackets were bonded to thirty-six bovine incisor teeth with different protocols according to the manufacturer's instructions as follows: Group 1: conventional multistep adhesive (n=12) Group 2: self-etching primer system (n=12) Group 3: acid+self-etching primer system (n=12). Specimens were loaded in a universal testing machine (Instron, Canton and Mass) and the mode of failure was recorded. Data were analyzed by ANOVA and Kruskall-Wallis tests with p<0.05 as the limit of significance.
Results: The mean shear bond strength was 11.7 ± 4.2, 10.5 ± 4.4, and 10.9 ± 4.8 MPa for group 1, 2, and 3 respectively. There was no significant difference in bond strength among the three groups (P=0.800). No significant difference was observed among the three groups with respect to residual adhesive on the enamel surfaces (P=0.554).
Conclusion: Based on the results of the present study, the use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in orthodontic bonding.
S. Yassaei , H. Aghili , D. Razeghi ,
Volume 20, Issue 3 (4 2007)
Abstract
Background and Aim: Functional appliances refer to a variety of removable or fixed appliances designed to alter the mandibular position both sagitally and vertically, resulting in orthodontic and orthopedic changes. Despite the long history of functional appliances, there is still much controversy related to their effectiveness and mode of action. The aim of this study was to evaluate dental and skeletal effects of Fa II in patients with class II malocclusion due to mandibular deficiency.
Materials and Methods: In this before-after clinical trial, 35 patients with class II div I malocclusion were selected. These samples were under treatment with Fa II appliance for 11 months. The range of age of females was 10-13 years and males 11-14 years. Combination analysis was used to determine skeletal and dental effects. Paired t-test was used to compare the differences of mean value pre and post treatment. P<0.05 was considered as the level of significance.
Results: There was significant difference between pre and post treatment in respect to posterior and anterior facial height, eruption of upper and lower posterior teeth, eruption of upper anterior teeth, mandibular body length, ANB angle, IMPA and 1 to SN. No significant difference was observed between pre and post treatment regarding facial growth.
Conclusion: Treatment with Fa II functional appliance leads to significant alterations in dental and skeletal elements of craniofacial complex and improvement of dental and jaws relationship.
Abdolrahim Davari, Soghra Yassaei, Alireza Daneshkazemi, Mohadeseh Khosravanian,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: Orthodontic bracket failure during treatment is a common problem. With the introduction of low shrinkage composites the question is that whether: this sufficient has coefficient bond strength for bonding bracket during orthodontic treatment. The aim of this study was to compare the shear bond strength (SBS) of silorane-based and metacrylate-based composites to metal brackets.
Materials and Methods: 30 human premolar teeth were collected and divided into 2 groups. In group 1, 15 orthodontic brackets were bonded using silorane-based composite, in group 2, 15 orthodontic brackets were bonded using metacrylate-based composite. The shear bond strength of each specimen was determined in an Instron machine. Amount of residual adhesive remaining on each tooth was evaluated using a stereomicroscope. Data were analyzed using T-test to compare the shear bond strength between groups and LSD method to compare the Adhesive Remnant Index (ARI) scores.
Results: There was significant difference in the SBS between the test groups (P<0.001). The mean bond strength of bonding brackets to silorane-based composite was (42.42 ± 7.03) MPa, and the mean bond strength of bonding brackets metacrylate-based composite was (21.08±2.97 ) MPa. No significant difference in the ART was found between groups (P=0.66).
Conclusion: Silorane-based composite provided higher bond strength to orthodontic metal brackets.
