Abstract
Abstract Objectives The study aimed to assess the longitudinal changes in the ANB angle before and after adolescence, and determine Class I normative values for childhood and adolescent Caucasian patients based on cervical vertebral maturation stages (CVMS) and gender. Setting and sample population The sample included 71 (41 females and 30 males) untreated Caucasian subjects who took part in a growth study between 1959 and 1976. Materials and methods Lateral cephalometric radiographs were analysed at CVMS1 (childhood) and again at CVMS4-5 (adulthood). A paired sample t-test was used to analyse ANB angle differences between the two time points. Subjects who were skeletally and dentally Class I at adulthood (51 subjects) had their radiographs at CVMS1 (childhood) and CVMS2-3 (adolescence) used to establish Caucasian normative values for those stages. Data were also analysed for gender and skeletal classification differences. Results There was a statistically significant decrease in ANB value (2.3°) from CVMS1 to CVMS4-5 in the combined sample as well as the skeletal Class I and Class III groups (2.5° and 3.3° for Class I and Class III subjects, respectively). The reduction was smaller and not statistically significant in Class II individuals (1.5°). In Class I individuals, ANB values were 4.68° (SD:1.76°) at CVMS1, 2.86° (SD:1.18°) at CVMS2-3, and 2.13° (SD:0.99°) at CVMS4-5. No significant gender differences were found. Conclusions Statistically significant decreases in the ANB angle can be expected between childhood and adulthood in Class I and Class III patients but not Class II untreated subjects. Adult normative values should not be used for children.
Highlights
Orthodontists use lateral cephalometric radiographs to assist in diagnosis and treatment planning by gathering information regarding a patient’s skeletal and dental relationships
The purpose of the present study was to longitudinally assess changes in the ANB angle before and after adolescence, and determine Class I normative values for childhood and adolescent Caucasian patients based on cervical vertebral maturation stages (CVMS) and gender
This was done for the entire sample as well as for each adult skeletal classification (Class I, Class II, and Class III based on the ANB angles at the age of 18)
Summary
Orthodontists use lateral cephalometric radiographs to assist in diagnosis and treatment planning by gathering information regarding a patient’s skeletal and dental relationships. Most of the cephalometric normative values/ standards in current use were developed between 1945–1955, when cephalometrics gained popularity for longitudinal growth studies and as an orthodontic diagnostic aid.[6] Many of the standards developed were based on subjective concepts of what was considered ‘normal’. In 1954, Tweed developed norms from 95 cases that he considered had a “face that I thought was pleasing”.3. Despite their imprecise origin, many of these norms have proven reliable over time, including the Caucasian adult normative value for the angle between A point, B point and Nasion (ANB) of 2°.7 In 1952, Riedel developed normative values for children and adults based on a small sample of individuals with “excellent occlusion”.4 In 1953, Steiner developed his analysis to express the concept of “an average American child of average age”.2 In 1954, Tweed developed norms from 95 cases that he considered had a “face that I thought was pleasing”.3 Despite their imprecise origin, many of these norms have proven reliable over time, including the Caucasian adult normative value for the angle between A point, B point and Nasion (ANB) of 2°.7
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