Study finds influence of Maxillary Posterior Region on smile aesthetics

China: University-based researchers found that maxillary posterior gingiva and teeth displayed influence smile attractiveness as perceived by laypersons.

The research team from the Department of Periodontology at Peking University School and Hospital of Stomatology investigated the aesthetic contributions of posterior smile-related characteristics to smile attractiveness in a Chinese population.

Establishing norms for posterior smile-related characteristics

Led by co-first authors Ning Wei and Cui Wang, the study results were published in the International Dental Journal titled “The Influence of the Maxillary Posterior Region on Smile Aesthetics in a Chinese Cohort”.

According to the study authors, the purpose of this research was to establish norms for posterior smile-related characteristics including posterior smile line (PSL), most posterior teeth displayed (MPTD), buccal corridor ratio (BCR), buccal corridor symmetry (BCS) and aesthetic contributions of these components to smile attractiveness as evaluated by laypersons.

The relationships amongst these 4 characteristics, along with anterior smile line (ASL), smile pattern (SP), and upper lip curvature (ULC) were also explored.

Laypersons evaluate dynamic smile videos

After capturing 188 standardised full-smile images from digitally recorded dynamic smile videos of young Chinese participants, the images were aesthetically evaluated by 22 laypersons using a visual analog scale (VAS).

Four smile-related variables in the posterior region were analysed. VAS data were compared between subgroups to test the influence of these variables on smile aesthetics with significance level of P < .05.

“It is worth pointing out that most people display maxillary premolars when smiling, partially showing the continuous gingival band during smiling, according to Maulik and Nanda,” said the authors.

“Therefore, great attention should be paid to aesthetically demanding cases, in which posterior teeth and gingiva are displayed when smiling.”

Emphasis on display of gingiva and teeth in maxillary posterior region

The researchers hypothesised that PSL, MPTD, BCR, and BCS would have no influence on the perception of smile aesthetics and that there would be no correlation between ASL and PSL.

The null hypothesis that none of the above-mentioned 4 posterior smile-related elements influence the perception of smile aesthetics was rejected based on the findings of the present study.

“The posterior smile variables including PSL and MPTD can impact the perception of smile attractiveness. And the discrepancies between ASL and PSL cannot be neglected,” they wrote.

“When the ASL is average/low, the display of gingiva and teeth in the maxillary posterior region should be taken into consideration.”

Impact of posterior teeth on smile aesthetics

Concluding that smile variables, including PSL and the MPTD, have an impact on smile aesthetics, the researchers added:

“The maxillary first premolars are almost always displayed during smiling, sometimes even more posterior teeth, which should be taken into consideration when smile aesthetics are involved.

“Maxillary posterior gingiva and teeth displayed influence smile attractiveness evaluated by laypersons, which should be given attention when treating patients with compromised aesthetics, especially those displaying average or low anterior smile lines.”

This study was funded by the National Natural Science Foundations of China, Beijing, China.

Read the article: The Influence of the Maxillary Posterior Region on Smile Aesthetics in a Chinese Cohort.