Comparison of smile esthetics among celebrities, dentists, and dental students in a Han Chinese population

Comparison of the width-to-height ratio in maxillary anterior teeth in different populations: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The width-to-height (W/H) ratio values of maxillary anterior teeth are parameters used in esthetic dentistry. However, a meta-analysis of studies evaluating these parameters in individuals from different countries, taking sex into account, is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to determine and compare the W/H ratio values seen in the maxillary anterior teeth of different populations.

MATERIAL AND METHODS

A systematic search was performed using the PubMed/Medline, Google Scholar, and Web of Science databases to identify English and non-English language articles reporting the golden ratio, golden percentage, tooth ratio, tooth size, W/H ratio, maxillary tooth width, maxillary tooth height, maxillary anterior tooth size, and dental esthetics. The titles, full text, and abstracts were scanned by 2 investigators independently to identify articles that fulfilled the inclusion criteria. Using a meta-analysis software program, data extracted from each selected study were statistically combined using the random-effects model, and the weighted mean differences were calculated.

RESULTS

The search protocol resulted in a total of 987 articles, but only 15 articles fulfilling the inclusion criteria were included in the meta-analysis. While the sample size varied between 50 and 412 in the 15 analyzed studies, a total of 2304 individuals from 12 countries were evaluated. As a result of the evaluation of the general W/H means of the maxillary anterior teeth, the largest teeth were seen in Korea and Pakistan, and the general mean W/H ratios of the central, lateral, and canine teeth showed no statistically significant difference between sexes (P>.05).

CONCLUSIONS

As a result of the meta-analyses of the W/H ratios of the maxillary central, lateral, and canine teeth, the differences between populations were found not to be statistically significant.

Comparison of maxillary anterior mathematical proportions among 3 dental arch forms

STATEMENT OF PROBLEM

Race and sex differences in the mathematical proportions of maxillary anterior teeth have been evaluated. However, studies exploring the relationship between the mathematical proportion of maxillary anterior teeth and maxillary dental arch form are lacking.

PURPOSE

The purpose of this clinical study was to determine if a correlation exists between the mathematical proportions of maxillary anterior teeth and 3 dental arch forms.

MATERIAL AND METHODS

Three hundred young participants were recruited according to predefined criteria, and images and maxillary casts were obtained. The perceived width and length of the maxillary anterior teeth were measured on the images by using a software program, and mathematical proportions, including width ratios and width-to-length ratios, were calculated for each. The casts were used to categorize each specimen into tapered, ovoid, or square groups by using a specific classification method, and the width ratios and width-to-height ratios of the 3 dental arch forms were compared. Statistical analysis was performed by using analysis of variance (ANOVA) or the Kruskal-Wallis H test to compare the mathematical proportions of maxillary anterior teeth among the 3 dental arch forms (α=.05). The intraclass correlation coefficient (ICC) was used to test the reliability of the investigators.

RESULTS

Except for the width-to-length ratios of the central incisor, mathematical proportions were affected by the dental arch form. The perceived width ratios of the maxillary lateral incisor-to-central incisor gradually increased from the tapered arch to the ovoid arch and from the ovoid arch to the square arch, with mean ±standard deviation values of 0.71 ±0.04, 0.73 ±0.05, and 0.79 ±0.06, respectively. For the maxillary perceived width ratios of canine-to-lateral incisor, the ovoid arch had the maximum perceived width ratios (0.86 ±0.10), followed by the tapered (0.82 ±0.10) and square arches (0.77 ±0.11). The width-to-length ratios of the central incisor were not affected by the arch form (P=.075), and the width-to-length ratios of the lateral incisor increased as the arch form became flat, with respective values of 0.70 ±0.10, 0.74 ±0.10, and 0.76 ±0.10. For the width-to-length ratios of the canine, the ovoid arch had the maximum perceived width ratios (0.58 ±0.10), followed by the tapered (0.53 ±0.10) and square arches (0.52 ±0.10).

CONCLUSIONS

The mathematical proportions varied among the 3 dental arch forms, and the dental arch form should be considered during the prosthodontic design of maxillary anterior teeth.

Effect of smile esthetics on the quality of life in a Han Chinese population

OBJECTIVE

This study aimed to explore the influence of smile esthetics on the quality of life in a Han Chinese population.

METHODS

A total of 110 Han Chinese volunteers (52 males and 58 females, mean age 26.7 years) were recruited, and frontal images of their smiles were collected. A photoediting program was used to evaluate the following components of smile esthetics: the buccal corridor ratios, the angle between the interpupillary and commissural lines, the number of visible teeth, and width-to-length ratios of the maxillary central incisors. Oral health-related quality of life (OHRQoL) in these volunteers was evaluated using the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) and Oral Health Impact Profile-14 (OHIP-14). Statistical analyses were performed by using Pearson's correlations and multiple linear regression (α = 0.05).

RESULTS

Compared to males, females scored higher on psychological impact (p = 0.017). Moreover, the number of visible teeth had a significant effect on social impact, psychological impact and esthetic concern (all p < 0.05). However, the buccal corridor ratios, the angle between the interpupillary and commissural lines, and the width-to-length ratios of the maxillary central incisor did not correlate with the OHRQoL (all p > 0.05).

CONCLUSIONS

The number of visible teeth significantly influenced the quality of life in a Han Chinese population. Smile esthetics had a significantly greater psychological impact on females than males.

CLINICAL SIGNIFICANCE

This study highlights the effects of smile esthetics on the quality of life in a Han Chinese population. Female patients may raise more esthetic concerns in clinical practice.

The Influence of the Maxillary Posterior Region on Smile Aesthetics in a Chinese Cohort

OBJECTIVES

The aim of this research was to establish standard norms for posterior smile-related characteristics including posterior smile line (PSL), the most posterior teeth displayed, buccal corridor ratio (BCR), and buccal corridor symmetry (BCS) and investigate its aesthetic contributions to smile attractiveness in a Chinese population.

MATERIALS AND METHODS

From digitally recorded dynamic smile videos of young Chinese participants, 188 standardised full-smile images were captured and then 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.

RESULTS

The VAS scores of participants with high PSL were significantly lower than those with average or low PSL (P < .01), especially when they display average or low anterior smile line (P < .05). Smiles with the second premolar displayed obtained the highest VAS amongst the 3 subgroups (P < .05). No significant differences were found between the VAS scores of BCR and BCS (P > .05).

CONCLUSIONS

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.

Patterns of Facial Profile Preference in a Large Sample of Dental Students: A Cross-Sectional Study

The objective of this study was to explore dental students’ facial profile preferences in a large sample of students. Nine hundred and nineteen dental students of four dental schools were involved. As part of a larger study on dentofacial esthetics, six photo series consisting of one unaltered and four altered variants of the same female profile were distributed among the students. The altered features were ones that are esthetically significant according to the literature. The students had to indicate the photo in each series that they preferred. The data were analyzed in a regression model in which preference in the given photo series was the dependent variable and gender, grade of studies, and dental school were the factors. Eight hundred and sixty-one students (93.7%) responded. Gender and dental school were not associated with the observed preferences, but the grade of studies was associated for three of the modified parameters: chin prominence, the sagittal position of the maxillary dental arch, and the simultaneous modification of the prominence of the chin and the nose. This study has confirmed several earlier observations, and new observations have also been made. We have demonstrated that the anteroposterior position of the maxillary incisors may be an important determinant of profile esthetics, even if this position does not influence the situation of the soft tissues and if the forehead cannot be used as a reference. We have also shown that the harmony between the nose and the chin overrides the importance of their individual dimensions.

Analysis of dental esthetic proportions in a Spanish population sample

PURPOSE

The present study aimed to analyze in a Spanish population sample the compliance of the anterior maxillary teeth to the dental esthetic proportions described in the literature.

METHODS

Photographs of the smiles of 78 individuals were calibrated and digitally analyzed considering the following proportions: golden proportion (GP), recurring esthetic dental (RED), golden percentage (GPG), Preston's proportion and Modified golden percentage (MGPG). For statistical analysis, the t-test of an independent sample was applied, and compliance percentages for each standard were recorded.

RESULTS

The existence of RED 70% or 80% has not been registered. The percentages of compliance with GP were within a range between 0% and 16%. The mean tooth width ratios were adjusted to the values described by Preston (P > 0.05), but the compliance percentages were low (3.33-25%). GPG only presented high percentages of compliance in the lateral incisors (53.33-62.5%). MGPG showed the highest percentages of compliance (50-68%).

CONCLUSION

After analyzing a Spanish population sample using smile photographs for the first time, GP, RED, GPG and Preston's proportion standards are not fulfilled and therefore, not suitable for treatments that seek a smile that reproduces natural principles. However, the values designated by MGPG with a deviation of ±1% are largely applicable for treatments that aim for a natural smile.