Rickett’s E-line as Antero-Posterior Lip Posture Indicator

Method: Thirty participants (15 male, 15 female) with normal class I occlusion and no history of malocclusion, orthodontic or surgical treatment were enrolled. Various indices and analyses including Ricketts, Holdway, Burston, Steiner, Sushner, Z angle, upper and lower lip height,  mentolabial angle (MLA) and nasolabial angle (NLA) were measured on standard negative profile photographs. Statistical analysis was performed utilizing t-test and Pearson correlation.

Result: A direct and moderate correlation was found between upper lip height and upper lip to E-line distance (p=0.026). Correlations between upper lip height and upper lip distance to either one of B, S1 or S2 lines (p< 0.5), between lower lip height and lower lip to S2-line distance, and between upper and lower lips height, were direct but weak. MLA and NLA correlated inversely; however, no significant correlation was found among other studied indices. The inter-gender difference in mean height of upper and lower lips was not statistically significant, but the Z angle was smaller in women. MLA and NLA were significantly larger among women based on Ricketts, Holdway, Burston, Steiner and Sushner lines.

Conclusion: Based on our findings, only upper lip height and upper lip to Rickett’s line correlated significantly. (r = 0.402, p=0.028) Further studies are suggested to determine the diagnostic value of this finding.