Journal of Dental School
Year:2002 | Volume:20 | Issue:1 (Specail Issue)|Papers Count:17

Aim: This study was designed to evaluate the gingival status of patients receiving orthodontic treatment with fixed appliances at Shahid Beheshti Dental School during the years 2000-2001. Material and Method: This descriptive non-randomized study was performed through an observation process in addition to an interview with a questionnaire filled in by patients who were being treated at the department of orthodontics for the last one year. Gingival plaque, debris and calculus indices were measured. The number of tooth brushing per day, mouth-rinsing free quancy, application of interdental brushes or orthodontic brushes were all recorded.Overall fifty cases were tested including 34 famales (68%) with mean age of 18.2 years and male 16 males (32%) with mean age 17.7 years. Patients were divided into two equal groups of adolescents and adults. Results: Results indicated that 14% of the patients had used mouth-rinses with 80% whom had it for more than twice a day only 4% of the cases had employed an interdental brush while 50% used special orthodontic brushes. A moderate gingivitis was seen in 68% of adolescents and 24% of adults while these figures were at 76% of adolescents and 8% of adults for their moderate to severe plaque accumulation experienced. Over all, 46% of the samples illustrated rated moderate gingivitis and 54% showed a healthy gingival or mild gingivitis, 58% had mild plaque accumulate in and 42% showed moderate to severe plaque accumulation. Conclusions: In total 82% of the patients were judged to have had good Oral hygiene status while 18% were classified as moderate.

Background: A high percent of patients referred to orthodontic clinics have craniofacial asymmetry. P. A. cephalometry is used routinely to diagnosie and provide a more accurae treatment planning.Aim: This research was designed to evaluate the efficacy of P. A. cephalo grams for assessment of craniofacial symmetry in a group of 9-13 years old Tehranian children.Material and Methods: Examination of 60 children was done byemployment of radiographs using NHP technique. As extra cranial true vertical & horizontal lines are not depended on craniofacial land marks the transverse dimension was measured associated with the symmetry in craniofacial complex.Linear & ratio, angular and even trigonometrical measurements of different areas were also used in the measurements of this study.Results: Findings of this research showed that P. A. cephalometry and NHP technique could show the symmetry of the patients skull with 96% confidence.Conclusion: NHP Technique could improve the diagnosis ability.

Aim: With regard to the importance of crowding and the factors effecting on crowding. this study was done to estimate the correlation between vertical facial growth and crowding of lower anterior teeth.Method and Materials: This descriptive study was done on one hundred orthodontic patients over 12 years old, with more than 2 mm crowding of lower anterior teeth. The patients were divided into four groups due to the amount of their crowding. jarabak index was measured by lateral cephalograms. The amount, intensity and direction of correlation was calculated by Pearson test in each group of crowding and totally in all groups.Results: In 100 patients (68 females, 32 males) of 15.6±3.4 years of age, there was no correlation between lower anterior crowding and jarabak index in the four groups.Conclusions: To obtain the better result it is recommended to choose the patients with vertical and horizontal grow patterns (high and low jarabak index) and then measure the amount of crowding and inclination of lower anterior teeth.

Aim: The aim of this investigation was to reveal the biomechanical changes of mandible during chin cup therapy using the finite element method.Material and Method: A three dimensional elemented model of mandible was reconstructed from a young human skull by means of a well developed software. The mandible was supposed to be fixed at the superior surface of glenoid fossa of the computerized model to determine the boundary of forces applied by chin cup. Two forces of 400 and 900 grams were applied to the pogonion of the mandible in relation to the line connecting pogonion to the condyle. Stress distribution was analysed from the loads and direction of displacement of mandible.Results: Compressive stress was clearly present in pogonion and anterior border of ramus, particularly in the junction with the body of mandible. The distribution of stress was also present in the whole body of the mandible, ramus and surface of condyle, although it was greater in anterior portion of the condyle and it's neck. Tensile stress was present in the inferior border of the body of mandible and posterior border of the ramus, specially near the condyle neck.Conclusion: The mandibular displacement was determined to be at upward and backward directions.

Background: Results of using distraction osteogenesis has shown the importance of appliance orientation. Although successful results of mandibular lengthening using osteodistraction have been reported, optimal orientation of the distractors has not been determined accurately for mandible.Aim: The purpose of this study was to evaluate the biomechanical effects of unilateral distraction osteogenesis in mandible, using a finite element model.Materials & Methods: Three different osteotomy lines (ie: oblique, vertical, transverse) with three different pin angulation (30, - 60, -90) degrees were compared which were related to the osteotomy lines. Displacement of proximal, distal bony segments and Pog onion were precisely evaluated on this model.Results: Vertical osteotomy line (90 degree) caused the most displacement in all the osteotomy lines, except transverse line (90 degree), pogonion displaced upward. In vertical osteotomy lines angles changing from 90 to 60 and them 30 degreees displacement of pogonion reduced in all planes, but with ablique and transverseosteotomy lines, displacement of pogonion increased in all planes.Conclusions: Biomechanical principles must be applied in treatment planning for distraction osteogenesis of mandible. Determination of distractors, orientation and osteotomy lines must be included in preoperative planning for mandibular osteodistraction.

Aim: This study was designed to determine any profile changes and indentify the role of the most significant factors responsible for these changes.Materials and Methods: Cephalograms of 56 class II Division I patients (36 female and 18 male with mean age of 10 years) were used to analysis any changes in the perioral soft tissue profile before and after the treatment. A correlation analysis and multiple regression analysis (forward) revealed complex interaction between dentition, bony structures and soft tissues of the perioral area.Results: Retraction at the upper lip and increase in lower lip length in boys were more predictable than that of others. Significant soft tissue changes occured in response to orthodontic treatment, Upper lip retraction was shown to be related to the following factors: a- Retraction of upper incisal edges during treatment, b-Retraction of Point A, c- Pretreatment upper sulcus thickness and d- Retraction of sulcus superior.Conclusion: A greater increase in lower lip length takes place with greater amount of maxillary incisa1 edge retraction during treatment and a greater amount of sulcus superior retraction.

Background: The craniofacial musculature has been cited as a possible etiologic factor in the development of malocclusions and relapse after orthodontic therapy.Aim: This investigation was designed to assess electromiographic activate of the muscles in aground of Cl II Div1 patients.Materials and Methods: In order to evaluate the relationship between craniofacial morphology and orofacialmuscle activity, integrated electromyography activity of the master, anteriortemporal, mentalis, and orbicularisoris muscles at rest, maximum intercuspation, during clenching and swallowing was recorded into a computer based system using surface bipolar electrodes in a sample of 10 Class II, Div.2 malocclusion in 10 normal occlusion adults.Results: Data analysis revealed no significant differences between the two groups.With respect to the differences reported in the literature between EMG activity of the orofacial muscles in children with cm, DiV.2 malocclusion and normal occlusion.Conclusion: it could be suggested there is an adaptation between form and function in the dentofacial neuromuscular system in the growing child.Precise evaluation of this adaptation maybe of clinical significance.

Aim: This study was conducted to evaluate a modified frankel appliance with application of jack-screw for gradual advancement of deficient mandible in treatment of C1 II div I malocclusion.Materials and Methods: 10 boys and girls 8-12 years old with skeletal C1 Il due to underdeveloped mandeble were selected from orthodontic department, school of dentistry, Shahid Beheshti University of Medical Sciences.After obtaining study models, xrays photographs and clinical examination, jack screws were incorporated in buccal shields of modified franke1 function appliance, in such a form which opening of screw moved mandible gradually in a forward position.Results: After 6-9 months of treatment, C1 I molar relationship was achieved and the overjet was eliminated. The profile improved and nodual-bite was present. Lateral cephalograms showed the significant forward movement of B-point and increase of mandibular length. Cooperation of patients was very good.Conclusion: Gradual Gradual movement of mandible to the normal position, might clecrease the resistance of orofacial musculature, motivates the cooperation of patients, increnses the mandibular length and leads to neuromuscular adaptation.

The aetiology of crowding which frequently develops in untreated lower arch in the period of erupting second and third molars remain enigmatci. It is apparently multifactorial, there may be more than one cause operating in an inividual and the cause may vary from one person to another. Diffculties have been encontered in establishing a cause and effect relationship between increased crowding and any of these factors.These causes are reviewed in the following article.

Aim: Two functional appliances; namely Harvold and two piece function corrector (TPFC) were used to test the hypothesis on modus operandi of functional appliances. This hypothesis states that postural and functional activity of masticatory muscles will increase after insertion of functional appliances.Material and Method: The pre and post treatment electromyographic (EMG) activity of the masseter and temporal is muscles were recorded in a population of thirty Class 11 Div. 1 children. Refered to Shahid Beheshti Dental School, Orthodontics Dept. EMG activity of masseter and temporal is muscles were recorded for each subject, at rest, swallowing 10 CC water and during maximum clenching using surface electrodes.Results: EMG activity of the masseter muscle was increased during maximum clenching, However, insertion of these two appliances was associated with a decrease in EMG activity of the two muscles.Conclusion: Results did not support the hypothesis of this study.

Background: The most important reason pushing people to seek orthodontic treatment is the lack of spacing or crowding for both the upper and lower anterior teeth.In most cases, the lower incisors" position determines the type of treatment required.Aim: This pilot-study, was designed to assess the power of a suggested mathematical formula to illustrate the lower incisor's relationship with the two sagittal and transverse plans.Material and Methods: The amount of developing space can be calculated with the amount of space needed for retrusion after protrusion based on the length of the root, IMPA, mesiodistal width of the lower incisor and the location of the center of rotation, using this formula. Eight dental casts were selected with protrusion or retrusion of the lower incisors. Sassouni trimming was performed by cutting the dental casts in sagittal plan, the long axis of incisor, mandibular plan and the angle between them. The lower incisors were set up in a new position. This newly set up model was duplicated and a final cast was prepared from it. Occlusal view of the initial and final cast was copied by Xerox-Copy to facilitate two dimensional evaluation in the occlusal plan. Radius of the anterior arch was determined. The space after protrusion or retrusion of the lower incisors was also measured both clinically and by aalication of the formula. These two measurements were then compared using a Paired t-test.Results: Results revealed that the use of such calculation could lead to an acceptable, reliable and easy achiering analysis Conclusion: This formula has an exact and aceurate meansurement capability using the dental casts.

Background: The prevalence of C1 III malocclusion has been reported to be different among different races, something between 1 to 13% this prevalence has been reported higher in Iran (7.88% to 19.5%). Early treatment of this malocclusion has a great importance and is highly recommended.Aim: The aim of this study was to introduce a simple appliance for treatment of C1 HI cases and to evaluate its dentoskeletal effect in association of a chin cap, particularly an maxilla.Material and Methods: Ninetee Individuals from a group of patients with C1 III malocclusion who were divided into two groups of 30 and 60 cases and controls.Treatment was carried out by means of at ongue appliance and a chin cap in case group while the control group were only reviewed without treatment. The mean age of the patients was 8.6 years. Cephalograms were taken from patients prior to and following the treatment course.Results: Analyzing the cephalogrophic measurments showed the following changes:Maxillary measurements: SNA=1.06±52; A(x)=2.9±3.4mm; A(y)=4.3±3.9 mm;Mandibular measurements: SNB=0.6±2.17mm; SnPog: 0.07±2.34; yaxis 1.56±2.29;Occlusal condition: ANB= 1.6± 1.88; overjet=2.95± 1.1 mm;Uprighting both incisors: IMPA=0.07±7.14; 1.1 to SN = 0±4.70Conclusion: Anteroposterior growth rate of the maxilla was found to be less incontrol compare to the experimental group. This was however more in the case of mandible.

Aim: This investigation was designed to evaluate the height spurt rate using radiographic indices of the wrist and hand.Materials and Methods: A group of 578 patients aged 8-17 years were selected from schools in shiraz. Radiographs were take from their hands and wrists. Five developmental indices of skeleton were assessed in addition to the patients's height measurements.Results: Findigns of, this investigation, showed that the age range in which the height spurt occurs is 11-13 years in girls and 13-15 years in boys. The mean age for the presence of sesamoid index is 1.6±0.9 in girls and 14.3±0.9 in boys.Conclusion: Developmental indices play an important role in decision making for treatment planning in orthodontics.

Background: There has been several reports on the relationship between the width and heigh of the skull in Caucasians. Initial assessment of a group of Iranian population has indicated some difference to these norms.Aim: This investigation was designed to find this norm for the male Iranian population. A group of 12 year old school boys (400 individuals) were selected from Several Mashhad's secondary schools.Results: Finding of this study indicated that there are obvious differences between the measurements of the population of this study and previous reports. Over all face layout of these boys were judged as narrower with wider skull compare to the Caucasians reported earlier. Mean cephalic index was found to be at 80% with facial index being at 100%.Conclusion: There was clear difference from previously reported norms with the newly found norms being intredaced.