Smile analysis: what to measure

Effect of the ethnic, profession, gender, and social background on the perception of upper dental midline deviations in smile esthetics by Chinese and Black raters

BACKGROUND

The purpose of this study was to compare the perception of upper dental midline deviation on the attractiveness of a smile among raters from different ethnicities, professions, genders, and ages and measure to what extent the presence or absence of the associated smiling structures influence the raters' evaluations.

METHODS

A male subject (26 years of age) with adequate smile characteristics was selected by 3 experienced orthodontists, and 561 raters from 2 different ethnic groups (281 Chinese raters and 280 Black raters) rated the subject's smile after the subject's upper dental midline was digitally altered from 0 to 5 mm using a 5-point Likert scale on 12 smile photographs divided into two groups: group 1, in the presence of smile related structures, two-thirds of the nose, lips, and chin (NLC), and group 2, in the absence of smile related structures, the lips only (L).

RESULTS

There were statistically significant differences (p < 0.05) between the two ethnicities, in 2 mm and 4 mm in-group NLC and 5 mm in-group L, as well as the raters' profession to each midline shift of both groups (NLC) and (L) for both ethnicities except for 0 mm. Regarding the role of associated smile structures, the smile photos were observed in the presence of smile-associated structures, and in its absence (NLC × L), statistically significant differences (p < 0.05) were found when the deviation was 5 mm among the Chinese raters; in 1 mm, and 4 mm among the Black raters. Among different genders, statistical differences were only reported (p < 0.05) for Chinese raters for 5 mm in NLC, while statistical differences were observed for 2 mm and 3 mm in NLC for Black raters. For age categories, differences were observed (p < 0.05) for 4 mm, 5 mm in NLC and 4 mm, and 5 mm in L for Chinese raters, while 5 mm in NLC and 1 mm in L for Black raters.

CONCLUSION

Perception of the upper dental midline deviations was influenced by the factors of ethnicity, profession, presence or absence of smile-associated structures, as well as the gender and age of the raters.

Impact of assessing smile parameters as part of orthodontic treatment planning - a survey based analysis

BACKGROUND

Smile forms an imporatnt aspect of facial analysis, as it contributes to overall facial esthetics. Many orthodontists pay more attention to cephalometric radiograph; and profile assessment to improve their patients' esthetics; however, the facial attractiveness of the individuals is obviously improved through enhancing their smiles. This study was aimed at evaluating the impact of analyzing certain smile esthetic parameters on diagnosis and treatment plan for individuals seeking orthodontic treatment.

MATERIALS AND METHODS

An electronic questionnaire with 24 questions arranged on five main axes was designed. These axes included smile arc, smile line, buccal corridors, smile symmetry, and photographic analysis of the smile, with several questions in each axis. The electronic link of the questionnaire was sent to all members of the Iraqi Orthodontic Society in April 2019. The answers were collected after 4 weeks of questionnaire link distribution date.

RESULTS

Among the surveyed orthodontists, there was a consistent agreement to assess the smile arc, smile line, buccal corridors, and smile symmetry, with main axes scores (4.14 ± 0.81, 4.1 ± 0.79, 3.86 ± 0.82, and 4.16 ± 0.86 respectively). Moreover, the participants prefer, with 3.89 ± 0.86 main axis score, to use the facial photograph for a less time-consuming and detailed evaluation of smile features.

CONCLUSIONS

Smile parameters, for example, smile arc, smile line, buccal corridors, and smile symmetry are better to be analyzed using photographs during orthodontic diagnosis and treatment planning.

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.

Distribution of smile line, gingival angle and tooth shape among the Saudi Arabian subpopulation and their association with gingival biotype

Objectives:

To determine the occurrence of smile line and maxillary tooth shape in the Saudi Arabian subpopulation, and to estimate the association between these parameters with gingival biotype.

Materials and Methods:

On the fulfillment of selection criteria, total 315 patients belong to Saudi Arabian ethnic group were randomly selected. Two frontal photographs of the patients were acquired. The tooth morphology, gingival angle, and smile line classification were determined with ImageJ image analyzing software. The gingival biotype was assessed by probe transparency method. The obtained data were analyzed with SPSS 19 (IBM Corporation, New York, USA) software to determine the frequency and association between other parameters and gingival biotype.

Results:

Among the clinical parameters evaluated, the tapering tooth morphology (56.8%), thick gingival biotype (53%), and average smile line (57.5%) was more prevalent. The statistically significant association was found between thick gingival biotype and the square tooth, high smile line. The high gingival angle was associated with thin gingival biotype.

Conclusions:

The study results indicate the existence of an association between tooth shape, smile line, and gingival angle with gingival biotype.

The role of personality traits in self-rated oral health and preferences for different types of flawed smiles

Symmetric, aligned and luminous smiles are usually classified as 'beautiful' and aesthetic. However, smile perception is not strictly governed by standardised rules. Personal traits may influence the perception of non-ideal smiles. We aimed to determine the influence of personality traits in self-rated oral health and satisfaction and in the aesthetic preference for different strategically flawed smiles shown in photographs. Smiles with dark teeth, with uneven teeth, with lip asymmetry and dental asymmetry were ordered from 1 to 4 as a function of the degree of beauty by 548 participants, of which 50·7% were females with a mean age of 41·5 ± 17·6 years (range: 16-89 years). Self-assessment and oral satisfaction were recorded on a Likert scale. Personality was measured by means of the Big Five Inventory (extraversion, agreeableness, conscientiousness, neuroticism and openness), and the Life Orientation Test was used to measure optimism and pessimism. Of the four photographs with imperfect smiles, dental asymmetry was the most highly assessed in 63% of the sample, and the worst was lip asymmetry, in 43·7% of the sample. Some personality traits (above all conscientiousness and openness) were significantly correlated with the position assigned to the photographs with dental and lip asymmetry or with misaligned teeth. The extraversion, agreeableness and openness traits were correlated with the self-perceptions of oral health and aesthetics of the participants. Dental asymmetry seems to be better tolerated than lip asymmetry. Personality traits are weakly but significantly correlated with the aesthetic preference and oral health values, conscientiousness and openness being the most relevant domains in this sense.