Influence of the Smile Line on Smile Attractiveness in Short and Long Face Individuals

Laypersons' Assessment of Smile Esthetics in Young Individuals in Ha'il, Saudi Arabia

INTRODUCTION

When planning esthetic dental treatments, understanding smile preferences is important for dental professionals. This study aimed to evaluate the impact of selected smile characteristics on the attractiveness of young Saudis as assessed by Saudi laypersons and explore gender-preferred changes in smile attractiveness.

METHODOLOGY

This observational study assessed the dynamic smile attractiveness of 168 Saudi individuals (84 males and 84 females), selected through non-probability convenience sampling. Dynamic smiles were elicited by viewing comedic content and captured with a camera standardized for consistent positioning. Videos were edited and adjusted to images, and the frames with the most pronounced smiles were chosen. The intra-rater reliability was assessed using intra-class correlation coefficients (ICCs) and Cohen's kappa tests (κ). The highest and lowest 25th percentiles were categorized as attractive and unattractive smiles, respectively, on the visual analog scale (VAS) by laypersons. Six smile characteristics - anterior smile line, smile arc, upper lip curvature, posterior teeth displayed, smile index, and smile symmetry - were quantitatively evaluated from these images for each participant and classified into attractive and unattractive groups based on laypersons' VAS evaluations. Continuous variables were tested with the Mann-Whitney U test, and for the categorical variables, the Chi-square test was applied. The significance was set at 5%.

RESULTS

 The four randomly selected out of the 22 raters had good VAS reliability; ICCs varied from 0.661 to 0.94, with an average of 0.737, and Cohen's kappa tests for smile characteristics showed values from 0.617 to 0.89. Good agreement was also found with the smile index, with ICCs of 0.775, and dynamic smile symmetry, with ICCs of 0.872. Laypersons rated female smiles as more attractive compared to male smiles (P = 0.004). Low or average anterior smile lines (P = 0.001 for males; P = 0.03 for females), parallel smile arcs (P = 0.001 for males; P = 0.02 for females), and higher smile indexes (P = 0.001 for males; P = 0.004 for females) were significantly attractive, showing no significant gender differences.  Conclusions: Laypersons reliably rated the young Saudis' dynamic smiles as attractive. Of the rated smile characteristics, those with a low or average anterior smile line, parallel smile arcs, and a larger smile index were deemed more attractive. This study's findings show no significant gender differences in the impact of the studied smile characteristics on attractiveness. This study's findings can help dental professionals customize treatment plans that meet patients' expectations.

Comparison of pleasant and unpleasant smile characteristics in the perception of the laypeople in an Iranian population

INTRODUCTION

This study aimed to compare the characteristics of pleasant and unpleasant smiles from the perception of laypeople.

METHODS

Two-hundred posed smile photographs were obtained from adult participants with no anomaly, restoration, or severe crowding and spacing in anterior teeth. Photographs were shown to 26 judges to give each photograph a score for attractiveness. Upper and lower quartiles for the most and least rated smiles were determined, and variables including gingival display, smile arc, midline deviation, buccal corridor, smile width, tooth rotation or malposition, diastema, upper and lower vermilion show, and tooth form were measured. Independent-sample t test and Pearson chi-square analysis were used to determine the differences between the pleasant and unpleasant groups for quantitative and qualitative variables, respectively. The linear regression model revealed variables with the most significant impact on the mean score.

RESULTS

All quantitative and qualitative variables except tooth form significantly differed between pleasant and unpleasant smile groups (P <0.05). The consonant smile arc was associated with an increase of 12.59% in mean scores compared with the inconsonant smile arc. Each tooth reported with malposition was correlated with a decrease of 9.37% in the scores. In the same way, each 1-mm increase in midline diastema and occlusal cant coincided with a drop of 8.73% and 3.59% in scores, respectively.

CONCLUSIONS

The results of this study suggested that smile arc, tooth malposition, midline diastema, and occlusal plane canting had the most impact on smile esthetics and should be given priority by orthodontists in the treatment plan of choice.

Morphological features of smile attractiveness and related factors influence perception and gingival aesthetic parameters

INTRODUCTION

In addition to understanding the basic standards of a smile and patient's opinion, dentists should take into account smile aesthetics, an essential factor for optimal outcomes. This study aimed to evaluate the factors that affect the perception of an aesthetic smile and determine its morphological characteristics and measure the gingival aesthetic parameters.

METHODS

In all, 200 Vietnamese aged 18-35 years were recruited to have their spontaneous smiles captured. These smile images were assessed by 50 laypersons and 50 dentists using a visual analogue scale measurement. The images were analysed to evaluate perceptions of evaluators, determine smile attractiveness, and measure gingival aesthetics.

RESULTS

The difference in the judgements of laypersons and dentists, males and females, and laypersons aged 18-25 and 26-35 years were nonsignificant. High or average anterior smile line, parallel smile arc, upward upper lip curvature, second premolars as the posterior-most teeth displayed, smile index of 5.23-5.63, and dynamic smile symmetry of 1 were scored highly on smile attractiveness. The following maxillary gingival aesthetic parameters were preferred: gingival zenith (GZ) of the canine 0.72-0.75 mm apical to the GZ of the central incisor; GZ of the lateral incisor 0.66 mm coronal to the gingival line; gingival line angle of ∼87°; for the central incisor, lateral incisor, and canines, distance from the GZ to the long axis of 1, 0.4, and 0 mm, respectively; interdental papilla height of 4.25, 3.60, and 3.85 mm, respectively; ratio of the distance from the GZ and the interdental papilla tip to the incisal edge of ∼1.74-1.77 mm.

CONCLUSIONS

Factors including profession, gender, and age of evaluators had almost no impact on their perception of aesthetics. Smile attractiveness characteristics and gingival aesthetic parameters have clinical applicability for patient care.

The Influence of the Smile on the Perceived Facial Type Esthetics

Objective

The objective of this study was to determine if the smile would influence the facial types esthetics perception for dentists, specialists, and laypeople. The null hypotheses for this study were that the smile has no effect on the perceived facial esthetics of different facial types.

Materials and Method

A photograph of an attractive female face with an attractive smile was captured and manipulated using computer software, which was used to produce changes in the smile and facial type of the female face. Two sets of photographs were developed. The first set is composed of three photos showing mesofacial, dolichofacial, and brachyfacial faces; on these photos the smiles were masked intentionally. On the second set, the smile was revealed in the three face types (mesofacial, dolichofacial, and brachyfacial faces); this results in three smiling photos, where each showed a facial type with the same smile. These photos (6 photos in total) were rated by the participants; two hundred participants were recruited, 50 general dentists, 50 specialist dentists, and 100 laypeople.

Results

The three groups (dentists, specialists, and laypeople) rated the mesofacial face as the highest (p value < 0.01) (64.48, 76.12, and 60.68, respectively), the mesofacial face was the only face that showed a significant difference between the three groups ratings (p value<0.01), and this significant difference disappeared when we compared the smiling photos for the mesofacial face (p value>0.01).

Conclusion

Mesofacial face is considered to be the most attractive face in comparison to dolichofacial and brachyfacial faces. Facial type should not be looked at separately from the smile as the smile might influence the esthetics perception of the facial type.