Cephalometric measurements and facial silhouette profiles: the effect of skeletal pattern on visual perception. Orthodontist vs. lay person [EMBARGOED]

Abstract

Introduction: A lateral cephalometric radiograph (LCR) aids in analysing dentoskeletal and soft tissue relationships objectively. Nevertheless, visual perception of facial profile during clinical assessment is also diagnostically important but may be subjective. Aim: To evaluate the correlation between cephalometric measurements with orthodontists’ visual perception of facial silhouette profile in skeletal Class I, II and III, and to compare the visual perception differences between orthodontists and laypersons. Method: 180 pre-treatment LCRs of Malaysian Malay patients aged 20 to 40 (24.59 ± 3.84) retrieved from two private dental clinics in Kuantan city of Pahang state, were manually traced and measured for 28 skeletal, dental, and soft tissue variables. From the total, 10% of the LCRs were retraced two weeks apart for reliability. Thirty LCRs were converted into facial silhouette profiles and were rated according to the degree of facial convexity or concavity by ten orthodontists and ten laypersons using a validated Visual Analogue Scale, with re-evaluation after two weeks for intra- and inter-reliability. Results: Using intraclass correlation coefficient (ICC), a high degree of intra-reliability was found for all variables (p < 0.001). The Pearson correlation coefficient revealed a very strong positive correlation with high statistical significance between H angle hard tissue and visual perception in skeletal Class I (r = 0.92, p = 0.00). In skeletal Class II, there were strong positive correlation with statistical significance between H angle hard tissue (r = 0.90, p = 0.00), H angle soft tissue (r = 0.85, p = 0.00), facial convexity (r = 0.83, p = 0.00) and lower lip to E-line (r = 0.73, p = 0.02) with visual perception. In skeletal Class III, maxillary depth (r = 0.82, p = 0.00), lower lip to E-line (r = 0.74, p = 0.01) and facial convexity (r = 0.78, p = 0.00) revealed a statistically significant strong positive correlation with visual perception. The facial depth (r = 0.67, p = 0.03) was moderately and positively correlated with visual perception. The lower lip length (r = ?0.72, p = 0.02) and the nose projection to subnasale vertical line showed a strong but negative correlation (r = ?0.81, p = 0.00) whereas the mento-labial sulcus depth showed a moderate negative correlation with visual perception (r = ?0.70, p = 0.03). The ICC score for intra- and inter-reliability among the orthodontists were high (0.92 and 0.99 respectively, with p < 0.001). For laypersons, the intra-reliability was fair (0.58, p < 0.001) whilst the inter-reliability was high (0.93, p < 0.001). Paired T-test showed a significant difference in visual perceptions between orthodontists and laypersons (p < 0.05). Conclusion: Only 32% of the cephalometric measurements had moderate to very strong correlation with visual perception indicating that cephalometric analysis alone should not be interpreted as treatment aim. The significant differences in visual perception of facial profiles found between the orthodontists and laypersons affirm that these differences need to be addressed to avoid miscommunication and patient dissatisfaction of treatment outcome. Certain cephalometric variables in skeletal Class I, II and III show significant differences between male and female suggesting the existence of sexual dimorphism among the genders which need to be taken into account during orthodontic treatment planning to ensure a successful treatment result.