Linear evaluation of the development of sagittal jaw relationship.
ABSTRACT 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.
- [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.Journal of natural science, biology, and medicine. 01/2013; 4(2):409-413.
- [Show abstract] [Hide abstract]
ABSTRACT: There may be significant variation amongst oral and maxillofacial surgeons (OMFS) in the identification and placement of cephalometric landmarks for orthognathic surgery, and this could impact upon the surgical plan and final treatment outcome. In an effort to assess this variability, 10 lateral cephalometric radiographs were selected for evaluation by 16 OMFS with different levels of surgical knowledge and experience, and the position of 21 commonly used cephalometric landmarks were identified on radiographs displayed on a computer screen using a computer mouse on a pen tablet. The database consisted of real position measurements (x, y) to determine the consistency of landmark identification between surgeons and within individual surgeons. Inter-examiner analysis demonstrated that most landmark points had excellent reliability (intra-class correlation coefficient >0.90). Regardless of the level of surgeon experience, certain landmarks presented consistently poor reliability, and intra-examiner reliability analysis demonstrated that some locations had a higher average difference for both x and y axes. In particular, porion, condylion, and gonion showed poor agreement and reliability between examiners. The identification of most landmarks showed some inconsistencies within different parameters of evaluation. Such variability among surgeons may be addressed by the consistent use of high-quality images, and also by periodic surgeon education of the definition of the specific landmarks.International Journal of Oral and Maxillofacial Surgery 09/2013; · 1.52 Impact Factor