IDENTIFICATION OF CONDYLAR ANATOMY AFFECTS THE EVALUATION OF MANDIBULAR GROWTH - GUIDELINES FOR ACCURATE REPORTING AND RESEARCH

Mandibular length is measured on cephalographs to depict changes durin g growth and after orthodontic treatment, and is often defined between condylion (Co, most posterior superior point on the condylar outline) and pogonion (Fog, most anterior point on the chin). The aim of this study was to assess the accuracy of identifying condylar anatomy, thus the validity of using Co-Pog to evaluate mandibular growth. The sampl e included 34 children from a prospective study on the early treatment of distoclusions. Two lateral head films were taken of each child, th e first with the mouth closed (MC), the second with the mouth open (MO ). Three examiners, two orthodontists (U.H. and K.H.) and a dental rad iologist (R.B.), rated the condyle as identifiable, nonidentifiable, a nd interpreted. The rating was applied to the left (L) and right (R) c ondyles, or to only one outline (O) when the R and L structures appear ed superimposed and were not distinguished separately. Besides Co-Pog, the orthodontists traced sella-nasion (SN) and incisor tip-menton (I- Me) to evaluate variability in measurements that do not include Co. On e operator (J.G.) measured all distances. Agreement among the three ex aminers was best in rating the MO radiographs (50%): 4.1% identifiable , 5.9% nonidentifiable or interpreted; in the MC films, they agreed in 32.3% of the cases, but only one of the ratings was identifiable (2.9 %). The highest agreement was in identifying the left condyle on the M O film (35.3%). Intraclass correlation coefficients for CO-Pog ranged from r = 0.73 (L side) to r = 0.92 (O) for one orthodontist, and for t he other from r = 0.76 (O) to r = 0.85 (L). Both orthodontists had hig h correlations for SN and I-Me between MC and MO (0.94 < r < 0.98). Th e variability between examiners in recognizing condylar anatomy, parti cularly on radiographs taken with the mouth dosed, suggests that the i dentification of condylar anatomy must be rated in studies of mandibul ar growth. Researchers measuring mandibular length in investigations o f mandibular growth after orthodontic therapy should differentiate bet ween cases where the condyle is readily identified, and those where co ndylar anatomy is interpreted.