IADR Abstract Archives
Beta-Angle and W-Angle Cephalometric Values in a Caucasian Ohio Valley USA Sample
Objectives: To determine Caucasian cephalometric norms for Beta- and W-angles and test the hypothesis that these angles have similar sensitivity and specificity to assess ANB-angle and Wits defined sagittal jaw relationships.
Methods: This retrospective study was conducted under UK-IRB approval #14-1025-P6J. Pretreatment cephalometric radiographs of Caucasian orthodontic patients were screened in Dolphin Imaging software for ANB-angle and Wits parameters used to define skeletal Class I, II or III according to the Iowa Growth Study. Two hundred and fifty-two subject radiographs qualified were coded to remove patient identifiers and divided into three skeletal classification groups (Class: 70, class II: 86 and class III: 96). All lateral cephalograms were re-traced by one orthodontist using Dolphin to measure ANB-angle, Wits, Beta-angle, and W-angle. Receiver operating characteristic (ROC) curves and tables were produced to assess sensitivity and specificity of the Beta- and W-angle measurements to delineate skeletal classification based on ANB-angle and Wits (JMP 13.2.1, SAS institute 2017).
Results: The Beta-angle means for Class-I, Class-II and Class III were 29.9°±3.9°, 23.3°±4.3°, and 40.1°±4.7°, respectively. The mean W-angles for skeletal Class-I, II and III were 53.3°±3.0°, 49.5°±3.4°, and 60.6±3.2°, respectively. Beta-angles<27° discriminated Class-II from Class-I (sensitivity 77%, specificity 82%), while Beta-angles>34° discriminated Class-III from Class-I (sensitivity 91%, specificity 93%). Similarly, W-angles<52° discriminated Class-II from Class-I (sensitivity 70%, specificity 76%), while W-angles>56.2° discriminated Class-III from Class-I (sensitivity 86%, specificity 90%).
Conclusions: The Beta angle had greater sensitivity and specificity than the W-angle to delineate Class II and Class III from Class I subjects according to classification based on both ANB-angle and Wits criteria.
Methods: This retrospective study was conducted under UK-IRB approval #14-1025-P6J. Pretreatment cephalometric radiographs of Caucasian orthodontic patients were screened in Dolphin Imaging software for ANB-angle and Wits parameters used to define skeletal Class I, II or III according to the Iowa Growth Study. Two hundred and fifty-two subject radiographs qualified were coded to remove patient identifiers and divided into three skeletal classification groups (Class: 70, class II: 86 and class III: 96). All lateral cephalograms were re-traced by one orthodontist using Dolphin to measure ANB-angle, Wits, Beta-angle, and W-angle. Receiver operating characteristic (ROC) curves and tables were produced to assess sensitivity and specificity of the Beta- and W-angle measurements to delineate skeletal classification based on ANB-angle and Wits (JMP 13.2.1, SAS institute 2017).
Results: The Beta-angle means for Class-I, Class-II and Class III were 29.9°±3.9°, 23.3°±4.3°, and 40.1°±4.7°, respectively. The mean W-angles for skeletal Class-I, II and III were 53.3°±3.0°, 49.5°±3.4°, and 60.6±3.2°, respectively. Beta-angles<27° discriminated Class-II from Class-I (sensitivity 77%, specificity 82%), while Beta-angles>34° discriminated Class-III from Class-I (sensitivity 91%, specificity 93%). Similarly, W-angles<52° discriminated Class-II from Class-I (sensitivity 70%, specificity 76%), while W-angles>56.2° discriminated Class-III from Class-I (sensitivity 86%, specificity 90%).
Conclusions: The Beta angle had greater sensitivity and specificity than the W-angle to delineate Class II and Class III from Class I subjects according to classification based on both ANB-angle and Wits criteria.