Tahereh Hosseinzadeh Nik; Toktam Jalayer; Amine Beymouri; Atefe Saffar Shahroudi; Armin Eftekhari
Abstract
Background: Third molar impaction is a major problem facing the dental profession and its impacts on the dentition has long been a major concern. Third molar is the most frequently impacted tooth. The prevalence of mandibular third molar impaction has been reported from 18 to 32 percent which varies ...
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Background: Third molar impaction is a major problem facing the dental profession and its impacts on the dentition has long been a major concern. Third molar is the most frequently impacted tooth. The prevalence of mandibular third molar impaction has been reported from 18 to 32 percent which varies between populations and races.
Objectives: This study was designed to determine the best retromolar space analysis from available methods with the highest correlation with mesio-distal width of mandibular third molar (MTM) in order to predict its eruption or impaction.
Patients and Methods: Measurements were carried out on digital panoramic radiographs of 98 Iranian patients. One hundred and seventy mandibular third molars were divided into 4 groups: impacted females, impacted males, erupted females and erupted males. Twenty eight points and 24 planes were marked on the radiographs: 11 points in relation to retromolar space analysis and the mesio-distal width of MTM; and 17 points in relation to some anatomic variables assumed to be related to MTM eruption or impaction. Using these landmarks, different methods were tested for analyzing the retromolar space and its relation to the width of the MTM. Student’s t-test was applied for comparison between erupted and impacted groups and ROC curve was drawn to determine the method with the highest specificity and sensitivity.
Results: Among the performed retromolar space analysis, the method that measured the distance between distal surface of second molar and the anterior border of ramus parallel to functional occlusal plane had the highest correlation with the MTM width. Also, the impact of some anatomic factors including posterior ramus height, upper body length, etc. on MTM eruption or impaction was observed.
Conclusions: Retromolar space analysis on panoramic radiographs can be a relatively precise predictor for mandibular third molar eruption or impaction. This study also supports the multifactorial concept about third molar impaction.
Ahmad Sodagar; Tahura Etezadi; K. Manshaie
Abstract
Background and aim: The aim of present study was to predict post treatment space available of mandibular arch and compare this method of measurement with the previous methods. Materials and methods: Pretreatment lower dental arch models of 33 patients attending to the department of orthodontics ...
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Background and aim: The aim of present study was to predict post treatment space available of mandibular arch and compare this method of measurement with the previous methods. Materials and methods: Pretreatment lower dental arch models of 33 patients attending to the department of orthodontics of Tehran University of medical sciences were randomly selected. Two conventional methods of brass wire and sectional way were done for estimating space available in traditional method. In predictive method two mathematical arch forms, β-function and the sixth degree polynomial function were selected as the based arches. Post treatment arch perimeter predicted according to these arch forms separately and finally the results were compared with traditional method of brass wire.Results: According to this study, two traditional methods are so closed to each other and also two predictive methods, but differences between traditional method and predictive methods measurements were considerable. Conclusions: Using of post treatment arch parameters would be useful to predict post treatment space available in arches, and also detecting arch form, the position of the teeth, the retention requirements and so on.
Mohammad Hossein Toodehzaeim; Hossein Aghili; Hoori Mirmohammadsadeghi; Elham Shariatifar
Abstract
Aim: To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of Iranian (Yazd) population with that of the study of Tanaka and Johnston.Materials and Methods: Teeth on study casts of an unselected sample from a 11 to 25 years old (n 120; 60 males and 60 females) ...
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Aim: To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of Iranian (Yazd) population with that of the study of Tanaka and Johnston.Materials and Methods: Teeth on study casts of an unselected sample from a 11 to 25 years old (n 120; 60 males and 60 females) were measured in the mesiodistal dimension. An Iranian mixed dentition analysis based on the Tanaka and Johnston method was constructed with new linear regression equations for prediction of the mesiodistal widths of unerupted canines and premolars. Digital calipers were used to measure the mesiodistal widths of all teeth on study models fabricated from alginate impressions. The predicted widths of the canines and the premolars in both arches were compared with the actual measured widths.Results: Sexual dimorphism was evident between Iranian (Yazd) males and females in incisors, canines, and premolars in the mesiodistal dimension.Conclusions: To predict the space (in mm) required for alignment of unerupted canine and premolars in Iranian(Yazd) children, divide the sum of the mesiodistal dimensions of the four mandibular incisors by two and add the respective constants for males (upper, 12.91; lower, 10.51) or females (upper, 9.09; lower, 8.22).
