Allahyar Geramy; Maryam Moghaddas Bayat
Abstract
Background: During mixed dentition period, one can make accurate estimation of future dental development and can assess whether there will be enough space in the dental arch. In orthodontics treatment planning, it is vital to predict space required for unerupted canine and premolars in the arch.
Objectives: ...
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Background: During mixed dentition period, one can make accurate estimation of future dental development and can assess whether there will be enough space in the dental arch. In orthodontics treatment planning, it is vital to predict space required for unerupted canine and premolars in the arch.
Objectives: The main goal of this study is to compare different teeth combinations in predicting needed space for unerupted canine and premolars on Bayesian approach and introduce the most reliable one.
Patients and Methods: The sample for this study consists of 47 dental casts (19 males, 28 females) with complete erupted dental arches. The meisodistal width of all teeth was measured using a dental caliper. We consider different combinations of teeth size and compare them to find the best predictor. In order to do that, quantile regression and Bayesian approach are applied using “R software”. Results: Combination of first maxillary molars with sum of central and lateral mandibular incisors has the smallest standard deviation. This is true for male and female samples. The regression formula based on this teeth combination has been introduced.
Conclusions: In our sample, combination of Mandibular incisors and maxillary first molar is found to be better than the other predictors for female and female model in both arches.
Jean Marc Retrouvey; Allahyar Geramy
Abstract
Background: Occlusal loads are always present though not widely considered in orthodontic treatments. Applied force systems are analyzed in detail and taught but their interaction with occlusal force is oftentimes ignored. Numeric evaluation of this combination by finite element method is the main goal ...
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Background: Occlusal loads are always present though not widely considered in orthodontic treatments. Applied force systems are analyzed in detail and taught but their interaction with occlusal force is oftentimes ignored. Numeric evaluation of this combination by finite element method is the main goal of this research.
Objectives: The present study has implemented FEA to investigate the effect of orthodontic force application on the tooth-periodontium-alveolar bone system. Materials and Methods: A 3D model of a lower premolar was designed. The model contained cortical and spongy bone, PDL, and tooth. A 1.73 N force decomposed to 1 N in each plane axis was applied as a random levelling and aligning force to assess the von Mises stress produced at the mesial aspect of the PDL from cervical down to the apical area. At the second phase a 200-Newton intruding force vector was applied simulating the occlusal force. The effects of the combination force system were evaluated in the same area of the PDL. Results: The maximum finding of von Mises for both stages were in found in the cervical area. This was almost 0.267 MPa for the first stage and 2.27 MPa for the second stage.
Conclusions: Our findings show that the co-existence of heavy occlusal forces due to clenching or bruxism in our tooth-periodontium-orthodontic force system has a significant influence on the magnitude and location of the high stress areas.
Mehdi Hassanpour; Amirhossein Mirhashemi; Atefe Saffarshahroudi; Allahyar Geramy
Abstract
Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in ...
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Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. It has therefore been recommended that CBCT be used in selected cases in which conventional radiography cannot supply satisfactory diagnostic information; which include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and planning orthognathic surgery. The need to use in other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations.
Amir Reza Rokn; Allahyar Geramy; Hadi Zare
Abstract
Hyperdontia is more common in the permanent dentition than primary teeth. The rampancy of hyperdontia in the permanent dentition is reported to vary between 0.1 and 3.8 % and its rampancy in the primary dentition is found to be 0.3-0.8 %. A 20-year-old woman contacted the Faculty Practice Clinic at the ...
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Hyperdontia is more common in the permanent dentition than primary teeth. The rampancy of hyperdontia in the permanent dentition is reported to vary between 0.1 and 3.8 % and its rampancy in the primary dentition is found to be 0.3-0.8 %. A 20-year-old woman contacted the Faculty Practice Clinic at the Tehran University with concern regarding tooth caries. The panoramic radiography showed seven retained supernumerary teeth. Several clinical exams were then performed to rule out the presence of systemic pathology, and they all showed normal results. It is reported that the premolar region in the lower arch is the most common place for supernumerary teeth. Worldwide; many studies have reported the prevalence of supernumerary canines, which has been estimated from 0 to 1.5%. In our case occlusion was normal and no discrepancies observed.
Allahyar Geramy; Hannane Ghadirian; Mohammad Javad Kharazifard; TajGaldi Katooki
Abstract
Aim: anterio-posterior discrepancies and differentiating the involved problems make a major part of our diagnosis and treatment. The main goal of this study was to compare the Materials and methods: In this cross sectional study, 105 pre-treatment lateral cephalograms (42 males and 63 females; 12±3 ...
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Aim: anterio-posterior discrepancies and differentiating the involved problems make a major part of our diagnosis and treatment. The main goal of this study was to compare the Materials and methods: In this cross sectional study, 105 pre-treatment lateral cephalograms (42 males and 63 females; 12±3 years old) The cephalograms were classified according to Angle classification. In all cephalograms, the ANB angel, Wits analysis, β angel, µ angel, Jaraback index and Bjork angels were measured.Results: The highest accordance between clinical observation and Wits appraisal was seen in class III group. The most accordance of the ANB angel was in the class II group.The best correlation was found between µ angel and β angel (r=0.912). The correlation of ANB angel with µ angel was the weakest (r=0.769).The results showed that when angle is smaller than 12.7 degrees, the patient is skeletal class II and the patients whose angle is larger than 19.1 degrees are classified in class III group.Conclusion: All of four sagittal parameters (ANB angle, Wits, β angle and µ angle) were well-correlated. The best correlation was found between µ angel and β angel. The correlation of ANB angel with µ angel was the weakest. angle and angle are proper tools to show skeletal class II and class III, but these angles cannot differentiate prognatic or retrognatic jaw.
