Bimaxillary protrusion in Malay population: a systematic classification of skeletal, dental and its soft tissue features / Siti Maisarah Ahmad Razin

The aim of this study is to analyze, classify and calibrate its cephalometric classification of skeletal and dental components and to describe its related soft tissue features of bi maxillary protrusion in Malay patients attending Orthodontic Clinic at UiTM. This cross-sectional study involved tracings and analysis of 116 lateral cephalometric radiographs using Dolphin Imaging software. This study was conducted in four phases which are first: preliminary, second: sample selection, third: quantitative and fourth qualitative analysis. Thirty radiography were randomly selected, traced, digitized, calibrated and repeated within 2 weeks interval to assess measurement error. Eight angular and eight linear parameters were measured. Skeletal and dental values were analyzed and classified into mild, moderate and severe to grade the severity of protrusion. Tracings were matched to the profile photos and numerically arranged for further grading by four assessors on two occasions of 2 weeks interval. Calibration were tested among 18 assessors including subjective scoring without cephalometric values. Descriptive statistics were used to assess the dentoskeletal characteristics and Kappa coefficient to measure the assessors’ agreement. Inter-rater and intra-rater reliability were analyzed for 30 radiographs and showed excellent correlation coefficient (ICC: 0.831). Agreement on classification between 4 assessors were found to be good in skeletal (0.8007) and very good in dental components (0.853). Further calibration similarly showed good agreement in skeletal (0.8490) and dental (0.7693), whereas subjective scoring displayed poor agreement in both variables (0.2506, 0.2079). With regards its severity, 61% of the subjects exhibited moderate, 24% of mild and 15% of severe protrusion. Significant bidental proclination of incisors were also observed (UIA: 125.48°; LIA: 102.56°) with acute interincisal angle (102.73°). Majority of subjects had moderate (71%) and 26% with severe proclination. Soft tissue assessments showed that the average lip thickness of the subjects was 11 ± 2mm. Bimaxillary protrusion mainly presented in wide range of protrusion from mild, moderate to severe protrusion and in occurrence of soft tissue procumbence. Subjective perception was shown to be inaccurate and unreliable. Thus, this systematic categorization aids easy identification, guided evaluation and proper treatment delivery.