Impact of Lightness Differences in Digitally Simulated Composite Resin Restorations on Perceived Smile Attractiveness

To investigate the effect of lightness differences between digitally simulated composite restorations and anterior maxillary teeth, in combination with restoration type, and clinical experience on perceived smile attractiveness.

An imaging software program (Adobe Photoshop CC 2023) was used to digitally manipulate a frontal full-face portrait of a smiling female model, to create five types of moderate-sized composite resin restorations of moderate size. For each restoration 14 lightness differences were simulated. The image was digitally modified to simulate five different types of composite resin restorations (Class III, Class IV, Class V, diastema closure (bilateral and unilateral approach)). Each restoration was adjusted through 7 incremental increases and 7 incremental decreases of 1 unit in lightness (L* value), yielding a total of 70 images. The smile attractiveness of each picture was rated by 80 dentists and 80 laypersons, ranged from 21 to 77 years using a visual analog scale. The Wilcoxon signed-rank test was employed to assess whether the mean of a sample significantly differed from the control (p < 0.05).

Among the different restoration types, crown fracture repairs (Class IV) had the greatest negative impact, followed by proximal restorations (Class III), diastema closures (Bilateral approach), diastema closures (Unilateral approach), and, lastly, cervical restorations (Class V), which had the least impact on perceived smile attractiveness (p ≤ 0.05). The influence of lightness differences, whether toward a darker or lighter restoration, was dependent on both the type of restoration and the observer's experience.

The effect of lightness difference on perceived smile attractiveness was significantly influenced by both the type of composite resin restoration and the observer's experience. Dental professionals perceived lightness discrepancies as less attractive compared to laypersons, suggesting that experience plays a key role in the perception of esthetic outcomes.

The repositioning of an esthetic direct dental restoration is highly influenced by the dentist's chromatic perception which is more sensitive than that of a layperson who evaluates its matching with the natural tooth. The findings of the present study can support evidence-based clinical decision-making.