Are Noffel's danger signs pathognomonic of class II division 2? A retrospective comparative study.

Introduction: The 3 Noffel signs, "Ramal height", "Smiling chin", and "B-line space", often present in class II division 2, are called "danger signs" for aesthetics, when they are strongly marked and absolutely need to be taken into account in the therapeutic strategy. The main objective was to assess whether the three measurements associated with Noffel signs (Gonion/Articulare distance, Cutaneous Pogonion/Na-B, and B-line space) were pathognomonic of class II division 2. The secondary objective was to determine whether there was a correlation between the severity of Noffel signs and the sagittal and/or vertical skeletal severity of class II division 2.

Materials And Methods: In this comparative, mono-centric study based on a retrospective cohort, lateral cephalograms of all the growing patients who were treated at the CSERD between 2012 and 2018 and had normodivergent and hypodivergent profiles, were analysed.

Results: The logistic regression analysis showed that only "Total chin" and "B-line space" were significantly related to class II division 2 (P=0.00199; P=0.00778, respectively). The three signs were related to the severity of the hypodivergence, but not to the severity of skeletal class II.

Conclusion: Only "Total chin" and "B-line space" are pathognomonic of class II division 2. The correlation between the severity of Noffel's three signs and skeletal severity exists only in the vertical dimension.