# Morphometric Findings in Adolescents with Robin Sequence: A Photographic and Cephalometric Study of the Face and Mandible

## TL;DR

Adolescents with Robin sequence show proportionate jaw retrusion and a vertical facial pattern, with mandibles growing faster during puberty but remaining harmonious.

## Contribution

The study identifies bi-retrognathic facial patterns in Robin sequence adolescents and challenges the role of neonatal retrognathia as a growth predictor.

## Key findings

- Adolescents with Robin sequence exhibit proportionate jaw retrusion and a vertical facial pattern, mostly with skeletal Class I relationships.
- Mandibles in Robin sequence patients show greater growth velocities during puberty but remain harmoniously downsized.
- Neonatal retrognathia does not predict future mandibular growth, but neonatal functional impairment correlates with increased facial divergence.

## Abstract

What are the main findings?
Adolescents with Robin sequence mainly presented proportionate retrusion of both jaws, which was mostly associated with skeletal Class I and hyperdivergent facial patterns. In subjective profile analysis, approximately 84% of patients had good or acceptable profiles, with no major deficit of chin projection.During the growth spurt, the mandibles of patients with Robin sequence exhibited greater growth velocities than those of controls. Nevertheless, the mandibles remained harmoniously downsized. This finding is consistent with partial catch-up growth.

Adolescents with Robin sequence mainly presented proportionate retrusion of both jaws, which was mostly associated with skeletal Class I and hyperdivergent facial patterns. In subjective profile analysis, approximately 84% of patients had good or acceptable profiles, with no major deficit of chin projection.

During the growth spurt, the mandibles of patients with Robin sequence exhibited greater growth velocities than those of controls. Nevertheless, the mandibles remained harmoniously downsized. This finding is consistent with partial catch-up growth.

What are the implications of the main findings?
The degree of neonatal retrognathia did not impact the sagittal skeletal mandibular parameters of adolescents, as shown by the results of the ANOVA. Therefore, neonatal retrognathia cannot be considered a prognostic factor for further mandibular growth. The facial divergence increased with the degree of neonatal functional impairment. This underscores the importance of functional co-treatment.Robin sequence seems to affect both jaws, and further research is needed to determine the full implications of this finding.The bi-retrognathic facial pattern is a risk factor for sleep-disordered breathing.

The degree of neonatal retrognathia did not impact the sagittal skeletal mandibular parameters of adolescents, as shown by the results of the ANOVA. Therefore, neonatal retrognathia cannot be considered a prognostic factor for further mandibular growth. The facial divergence increased with the degree of neonatal functional impairment. This underscores the importance of functional co-treatment.

Robin sequence seems to affect both jaws, and further research is needed to determine the full implications of this finding.

The bi-retrognathic facial pattern is a risk factor for sleep-disordered breathing.

Background: The aims of the study were to describe facial morphology and analyze facial growth in adolescents with Robin sequence (RS) or Stickler syndrome. Methods: The facial morphology, mandibular size, and facial growth of 69 adolescents (ages 12–18) with RS were analyzed using existing cephalometric radiographs (n = 37) and photographs (n = 69). All participants were followed in our institution since birth. None underwent growth-modifying treatment for micrognathia during infancy, but all had conservative orthodontic treatment during adolescence. Results: Cross-sectional cephalometric analysis according to Tweed revealed differences in RS adolescents as compared with reference values, such as a proportionate retrusion of both jaws, as indicated by decreased SNA and SNB angles (p < 0.05). This finding was mostly associated with skeletal Class I (62.2%) and a vertical facial pattern as indicated by increased FMA and CoGoMe angles (p < 0.05). In Delaire’s analysis, patients showed decreased maxillary, maxillary alveolar (p < 0.05), and mandibular body territories (p > 0.05) but increased ramus (p > 0.05) and nasopremaxillary territories (p < 0.05). According to Ricketts’ analysis, mandibular width was decreased in half of our patients (p > 0.05). The mandibles were harmoniously downsized before and after the growth spurt (p < 0.05); however, they exhibited greater growth velocities than controls. A long-term study during puberty revealed an increase in SNB angles and a decrease in ANB angles (both p < 0.05), which improved the maxillomandibular relationship. Additionally, the vertical facial pattern attenuated (FMA, SNGoGn, and CoGoMe angles decreased; p > 0.05). On cross-sectional photographic analysis, 33.3% of patients had an orthofrontal (straight), 59.4% a cisfrontal (convex), and 7.3% a transfrontal (concave) profile. Their vertical facial proportions were normal. In the subjective profile analysis, most patients (approximately 84%) had good or acceptable profiles, with no major deficit of chin projection. The initial degree of neonatal retrognathia and type of cleft palate surgery did not affect major skeletal parameters (p > 0.05). However, the degree of neonatal functional impairment affected the vertical parameters (SNGoGn, FMA angle; p < 0.05). Conclusions: Overall, RS patients presented a bi-retrognathic profile, a normal jaw relationship, and a tendency toward a vertical growth pattern. Partial mandibular catch-up growth occurred during the pubertal growth spurt. The degree of neonatal retrognathia does not predict further mandibular growth.