Journal of Dental Medicine

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The aim of this study was to evaluate mesiodistal diameter of permanent teeth and evaluating it's distribution in Iran. In current study, 850 plastery impressions or 16590 teeth were precisely measured by a digital coulis with 0.01 mm accuracy.The obtained measures of the permanent teeth are shown in table 1. Table (4) demonstrates the symmetry of left and right maxillary and mandibular teeth. Obtainedmeasurements in Table 1 were compared with Gran's measures (Table 2) which are shown in Table (3).Bolton analysis was done and results were found close to the BolType text or a website address or translate a document.ton measures. It was concluded that it is better to replace measurements of our society instead of Bolton's. Since we found minor difference with the measures of other researchers, especially for teeth anterior to first molar, using our measures in treatment plans would not bring about any problem.

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Normal 0 false false false EN-US X-NONE AR-SA The study's purpose was to estimate the value of symphysis morphology as a standard for anticipating direction of mandibular growth. 160 patients were sampled (80 f/80 m) and formed 8 groups based on gender,age and growth spurt. Mandibular growth direction was evaluated via 6 cephalometric indices: Mandibular Arc angeles, Lower facial Height, Facial Axis , Facial Angle ,Facial Taper and Mandibular Plane. Height, depth and their ratio and angle of symphisis were measured. The highest relation found among 13-16 yrs females as well as +20yrs males. Symphysis angle showed the highest relation in male patients. In 9-12 yrs females and 10-14 male patients in which anticipating the growth is highly needed, the relationship between symphysis morphology and mandibular groth indices was not significant.

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The purpose of this study was to determine the prevalence of dentofacial anomalies in 12 to 14 years old students in Tehran.The sample consisted of 500 students. 250 of them were females and 250 were males. The evaluation of saggital skeletal relationships revealed tha 16% of samples had normal occlusion, 48% of them had CI I malocclusion, 15,6% had CI II Div I malocclusion, 12% of them had CI HI malocclnsion, 5.2% of them had CI. II Div 2 malocclusion and 3.2% of them had pseudo CI III malocclusion. The prevalence of other dentofacial anomalies obtained in this study are, crowding 40.6%, deepbite 27.2%, spacing 20.6%, mandibular deviation 19.4%, unilateral posterior crossbite 9.2%, anterior openbite 6.6%, posterior openbite 5.6%, asymmetry 1.6% and bilateral posterior crossbite 1.6%. The prevalence of dental anomalies in the sample population was as follws: rotated teeth 13.4%, malposed teeth 12.2%, teeth with large size 3.2%, malshaped teeth 2.4% and teeth with smal size 2%. A part from determining the total values mentioned, the prevalence of saggital relationships oral dentofacial anomalies was assessed separately in each of the female and the male samples.

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Facial prognathism, which is a problem in some orthodontic patients, is characterized by a number of cephalometric changes. Most clinicians use SNA angle in lateral cephalometric analysis to evaluate the amount of maxillary prognathism. Since SNA angle is not a reliable measurement for maxillary prognathism, and taking into account that the amount of prognathism changes in relation to cranial anatomy, according to Bjork it's better to measure the facial prognathism by the angle between anterior and posterior cranial base. According, two angles are recommended NSBa and NSAr.In this study 80 lateral cephalograms from three malocclusion groups, were studied and the amount of maxillary prognathism in relation to SNA and NSAr angles and their relationship to each other were measured.

The results were as follows:
1- Studying facial prognathism in relation to SNA and NSAr angles it was found that SNA angle is influenced by cranial base shape
2- The mean value of anterior and posterior cranial bases didn't show significant differences.
3- The mean value of SNA angle didn't show significant statistical difference in various malocclusion groups.
4- The correlation coefficient of ANB angle and wit's measurement is low.

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In this investigation, the position of hyoid bone was compared in three skeletal groups of class I, II and III. The study was based on evaluating 77 lateral cephalometric radiographs, 40 girls and 37 boys, which were divided into 3 groups. Group 1, 2, and 3 consist of 26, 25, and 26 radiographs. 19 cephalometric landmarks and 10 planes were used in order to tracing the radiographs. In all patients, 9 skeletal and 4 cervical vertebrae parameters were measured to determine the hyoid bone. These parameters were compared between three skeletal groups regardless of sex and then, in another statistical analysis, parameters were compared based on patients sex. Statistical analysis showed that in class III patients, the hyoid bone was positioned more anteriorly than two other groups. Also in this group, the hyoid bone had less inclination and it was more horizontal in relation to mandibular plane. In skeletal class II patients this bone was positioned more superiorly than two other groups. Due to these findings it can be concluded that perimandibular muscles and bones could affect the growth of mandible. In addition, comparison of the parameters between two sexes revealed that the hyoid bone was positioned more anteriorly and inferiorly in boys. Also it was shown that in the girls, the position of hyoid bone was closer to the position of this bone in skeletal class I patients.

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Statement of Problem: The significance of adenoid tissue in Orthodontia appeared in 1954. At that time,even as today, orthodontists had an enduring interest in the relationship between excessive amounts of adenoid tissue, the developing occlusion, and facial morphology.
Purpose: The aim of this study was to evaluate effect of mouth breathing with adenoid enlargement on dentofacia! cephalometric measurements.
Material and Methods: A sample of 92 subjects between the ages of 6 and 15 years old were studied in two study and control groups. In study group, 46 mouth breathers (32 girls and 14 boys) with mean of 1 1.26 years old were examined by orthodontist and ENT specialist in order to confirmation of nasopharyngeal obstruction.Control group contained 46 nasal breathers (35 girls and 11 boys) with mean of 11.33 years old. For each patient in centric occlusion, a lateral cephalogram was taken and traced. 12 dentofacial variables were measured and statistical t-test was conducted by calculating the mean, standard deviation and p-value of parameters. Statistical t-test for mean oi~ dentofacial variables for the two groups revealed that some of variables were significantly different.
Results: In study group Z Go.Me-SN, Z Y-A.xis, Z Go, Z SN-PL variables were significantly higher than control group and Z HoFIl, Z SNB were significantly lower. The other dentofacial variables (ZS, IMPA,Z SNA, Z ANB. Z Ar and LH) didn't show any significant difference.
Conclusion: Adenoid enlargement and nasopharyngeal obstruction can affect dentofacial morphology and cause facial vertical growth pattern and upper centrals retrusion.

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Background and Aim: External apical root resorption is a common iatrogenic consequence of orthodontic treatment. Much controversy exists in the literature about changes in root lengths at post treatment periods. Although many practitioners believe that resorption becomes stable after active treatment, quantitative data are scarce. The purpose of this study was to determine quantitative changes in root lengths of maxillary incisors during fixed orthodontic post treatment period, and to assess if it is influenced by gender and factors related to active treatment.

Materials and Methods: This was a case cross over study, performed on 80 patients (52 females and 28 males) aged between 13 and 22 years. At debonding stage and beginning of retention phase of fixed orthodontic treatment, Hawley type retainer was fabricated for maxillary arch. Periapical radiographs of maxillary incisors using standard parallel technique were obtained immediately after debonding, and 3 and 7 months later. Crown and root lengths of maxillary incisors were measured using computer program. Changes in root lengths were calculated considering correction factors. Also associations between some factors and the change in root lengths during post treatment periods were assessed. These included gender, type of treatment plan (non extraction/extraction), technique (standard edgewise/straight-wire edgewise) and duration of active treatment (less than 2 years/2 years and more). T-test and 4-way ANOVA were used for statistical analysis with P0.05 as the limit of significance.

Results: No significant relation was found between apical root resorption of maxillary central incisors and time elapsed after treatment. Significant relation was observed between apical root resorption of maxillary lateral incisors and the length of post treatment period. No significant relation was found between root length changes of maxillary incisors during post treatment period and gender, type of treatment plan, technique, and the length of active treatment period (P 0.05).

Conclusion: Considering the general process of root length reduction in maxillary lateral incisors during post treatment period, establishment of preventive measures is emphasized.