# Influence of Hyaluronic Acid Lip Filler Augmentation on Smile Design Parameters in Young Female Population: An Observational Study

## TL;DR

This study shows that hyaluronic acid lip fillers slightly reduce tooth visibility in smiles, affecting dental aesthetics.

## Contribution

The study introduces 3D scanning to quantify how lip fillers alter smile design parameters in young women.

## Key findings

- HA lip augmentation reduced maxillary incisor and canine exposure by 0.1 mm at follow-up.
- Upper lip volume increased by 0.79 mm³ after treatment.
- Lip volume inversely correlated with central incisor exposure but not with canine exposure.

## Abstract

To evaluate the effect of hyaluronic acid (HA) lip augmentation on anterior tooth exposure and smile‐line characteristics using three‐dimensional (3D) facial scanning technology.

Twenty‐five female participants were enrolled. All injections were performed by a single experienced clinician following a standardized protocol, with a total of 1.0 mL of HA filler administered to the lips. 3D facial scans were obtained before treatment, immediately after injection, and at a 4‐week follow‐up. Maxillary left central incisor and canine exposure during smiling, as well as upper lip volume, were measured at each timepoint using dedicated software.

The mean participant age was 26.2 years, and the mean follow‐up period was 28.8 days. At follow‐up, maxillary central incisor and canine exposure decreased by 0.1 mm compared to pre‐treatment values (p  < 0.001). Upper lip volume increased by 0.79 mm3 at follow‐up (p  < 0.001). An inverse correlation was observed between lip volume and central incisor exposure, indicating reduced tooth display with increased lip volume. No significant correlation was found between lip volume and canine exposure or between central incisor and canine exposure.

HA lip augmentation was associated with small but statistically significant changes in anterior tooth exposure during smiling. These findings highlight the influence of perioral soft tissue on smile‐related dental parameters and underscore the importance of considering lip volume when planning esthetic dental and restorative treatments.