In cephalometrics both angular and linear variables have been proposed in the analysis of sagittal jaw relationship and jaw position. Angular measurements can be erroneous as a result of changes in facial height, jaw inclination, and total jaw prognathism; linear variables can be affected by the inclination of the reference line. In the present article, a method of geometric correction of linear analysis of sagittal jaw relationship and jaw prognathism (based on a standardized occlusal plane) is described. The method is applied to radiographic material (from King's College Hospital, London) of 33 children who, at the age of 19, exhibited Class I occlusal patterns. While uncorrected linear measurement suggested stability of the sagittal jaw relationship from the age of 11 to 19 years, the geometrically corrected value demonstrated a marked reduction in sagittal jaw relationship. The method is developed further to demonstrate the increase in jaw prognathism measured as lined parameters with origin at point sella, the results illustrating again the advisability of correction of geometric errors.
"Of those Downs, Steiner, Tweed, Ricketts and Jacobson probably have gained the widest acceptance. The analyses of Coben, Wylie, Sassouni, Enlow and associates Bimler, Edward Beatty's AXD angle, Rocco J. Di Paolo, Stephen Williams, Sang D Yang are perhaps less widely used, but they are nevertheless well known. "
[Show abstract][Hide abstract] ABSTRACT: In orthodontic diagnosis and treatment planning, assessment of anteroposterior discrepancy is of importance to the orthodontist. Both angular and linear measurements have been incorporated into various cephalometric analyses to help the clinician diagnose anteroposterior discrepancies and establish the most appropriate treatment plan. Hence the present study is designed to establish the norms of Beta angle to assess the sagittal discrepancy for Nellore district population.
The sample was screened from the old records of the Orthodontic department of Narayana Dental College and Hospital. One hundred and fifty pretreatment cephalometric radiographs (50 each of Class I, II, and III) were subdivided based on ANB, Wits appraisal, and Beta angle into skeletal Class I, II, III. The same cephalograms were again classified into skeletal Class I, II, and III based purely on Beta angle. Each group was again divided into 2 subgroups consisting of 25 male and 25 female subjects with a mean age limit between 15 and 45 years old.
The Newman-keuls post hoc test and ANOVA showed that the 3 groups were significantly different (P ≤ 0.001). The Newman-keuls post hoc test also found the groups to be significantly different.
There was statistically significant difference for, the mean values and the standard deviation for Beta angle within the three skeletal patterns (Class I, Class II and Class III skeletal patterns). There was no statistically significant difference among the mean values of beta angle between Nellore district population and Caucasian norms and between male and female sex groups.
[Show abstract][Hide abstract] ABSTRACT: The aim of the present article was to identify morphologic characteristics in the craniofacial skeleton of the 11-year-old child that could indicate potential development of a Class III skeletal pattern. A radiographic material consisting of 24 children (13 girls, 11 boys) at an average age of 11 years 0 months, who in adulthood demonstrated a Class III skeletal pattern, was compared with a control group of 33 children (16 boys, 17 girls, average age 11 years 6 months) chosen retrospectively on the basis of Class I occlusion. The analysis was performed by means of both linear and angular variables and results are reported both as group means and individual analyses. No one morphologic trait indicative of potential Class III development could be isolated because the study clearly demonstrated the existence of different skeletal combinations. The development of the maxilla, both in size and position, was clearly demonstrated by the linear analysis to be an etiologic factor in Class III development. However, maxillary retrognathism was usually masked in the angular analysis because a reduction in length of the anterior base with subsequent effect on the position of point nasion was often seen in these cases. Mandibular prognathism was a frequent observation, although a true macrognathia was uncommon. In the majority of cases, mandibular prognathism was the result of an increase in the ratio between mandibular length and dorsal position of the glenoid fossa (articulare). The relative merits of angular and linear analyses are discussed in relation to the results presented.
American Journal of Orthodontics 05/1986; 89(4):302-11. DOI:10.1016/0002-9416(86)90052-7
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