Comparison of clinical and electromyographic rest vertical dimensions in dolichofacial and brachyfacial young adults: A cross-sectional study.

STATEMENT OF PROBLEM: Therapeutic procedures that increase occlusal vertical dimension (OVD) may have different responses in patients with different craniofacial vertical patterns. The effect on these patients of increasing their OVD is not well understood.

PURPOSE: The purpose of this clinical study was to compare measurements of vertical jaw separation (VJS) in patients with brachyfacial and dolichofacial craniofacial patterns in 2 vertical dimensions: the clinical rest/postural vertical dimension (CR/PVD) and electromyographic rest vertical dimension (EMGRVD).

MATERIAL AND METHODS: Sixty healthy dental students were selected at random after a lateral skull radiograph was made. The Ricketts (VERT index) analysis was used to determine 30 brachyfacial (G1) and 30 dolichofacial (G2) types. The VJS was measured for G1 and G2 types in the 2 rest vertical dimensions specified. CR/PVD was recorded using 2 methods: swallowing (CR/PVD-P1) and the phonetic breathing method (CR/PVD-P2). The Shapiro-Wilk test was used for data distribution, and the Mann-Whitney U test was used to accept or reject the null hypothesis (α=.05).

RESULTS: Mean VJS in CR/PVD-P1 was 1.92 ±1.14 mm for the brachyfacial and 1.36 ±0.58 mm for the dolichofacial facial group (P=.05). The mean VJS in CR/PVD-P2 was 1.89 ±1.17 mm for the brachyfacial and 1.31 ±0.58 mm for the dolichofacial group (P=.03). The mean VJS in EMGRVD was 8.23 ±2.21 mm for the brachyfacial and 16.55 ±4.29 mm the dolichofacial group (P<.001).

CONCLUSIONS: CR/PVD measurements in dolichofacial individuals were lower than those in brachyfacial individuals. EMGRVD measurements were higher in dolichofacial individuals than those in brachyfacial individuals. Biomechanical, physiological, and behavioral reasons might explain such diversity.