Effect of occlusal vertical dimension on lip positions at smile

Abstract

Purpose:In full mouth reconstructive dentistry, the occlusal vertical dimension(OVD) is often increased to provide adequate restorative space or for esthetic reasons. The purpose of this study was to analyze the effect of occlusal vertical dimension on dimensional measurements of the smile. Materials and Methods:30 dental students, 12 male and 18 female between the ages of 21 -30 participated in this study. Polyvinyl Siloxane bite splints of 2mm, 4mm, 6mm, 8mm thicknesses were fabricated on stone casts mounted on semi-adjustable articulators. A wall-mounted head positioning device, modified from a cephalometric unit was used to stabilize head positions. Three photographs each at OVD of +0mm, +2mm, +4mm, +6mm, +8mm were taken using a DSLR camera mounted on a tripod. Measurements were made in Adobe Photoshop CS5, using the width of the maxillary central incisors to convert pixel measurements to millimeter measurements. Results:One way repeated measures ANOVA found statistically significant differences in interlabial gap height, incisal edge -lower lip length, and display zone area with increasing OVD. No statistically significant differences were found for intercommisural width and incisal edge -upper lip length. Conclusions:This study demonstrates that excessive increase of OVD may lead to excessive interlabial gap height, incisal edge -lower lip length, and display zone area. A lengthening of the upper lip at smile should not be expected with increasing OVD. In addition, a change in the width of the smile should not be expected with increasing OVD. i ACKNOWLEDGEMENTS

Effect of smile index and incisal edge position on perception of attractiveness in different age groups

“…Recently, OVD was found to affect the positions of the lips during smile . With an increase in OVD, the position of the upper lip and the intercommissural width stay the same while the lower lip moves downwards, leading to a lower SI .…”

“…In a recent study, occlusal vertical dimension (OVD) was found to affect lip positions at smile . Specifically, increasing the OVD shifts the lower lip downwards, increases the interlabial gap height, increases the display zone area and lowers the smile index (SI, intercommissural width/interlabial gap height) . The width of the smile and position of the upper lip were not found to be affected by changes in OVD .…”

“…SI had been correlated with facial growth pattern (vertical versus horizontal) variations . As discussed, SI has been found to decrease as OVD is increased . However, little information is available on the influence of SI on aesthetic perception.…”

“…The dimensions of the smile have been extensively studied in the literature . It has been found to change with age .…”

“…This leads to a decrease in maxillary incisor display . In a recent study, occlusal vertical dimension (OVD) was found to affect lip positions at smile . Specifically, increasing the OVD shifts the lower lip downwards, increases the interlabial gap height, increases the display zone area and lowers the smile index (SI, intercommissural width/interlabial gap height) .…”