Perceptions of Dentists and Non-Professionals on Some Dental Factors Affecting Smile Aesthetics: A Study from Vietnam

The knowledge regarding the impacts and management of black triangles among dental professionals and laypeople

This study aimed to assess the knowledge regarding impacts, causes and management of black triangles (BT) among participants from different educational backgrounds including dental students, dentists and laypeople. This descriptive cross-sectional observational research included 435 participants who comprised 4 groups: pre-clinical (3rd year) dental students, clinical (4th and 5th year) dental students, dentists, and laypeople. A constructed self-reported questionnaire was utilized to assess participants' demographic data and their knowledge of the impacts, causes and management of BT. The VAS scale was used to assess participants' ratings for the impacts of BT on esthetics, with 0 meaning no impact and 10 meaning very severe negative impacts. The most reported treatments for BT were "cannot be treated" 99.3% and "non-surgical periodontal treatment" 67.1%. Meanwhile, the least reported was "modify the porcelain" 41.8%. The most reported cause of BT was "periodontal disease" 85.1%. However, the least reported were "parafunction" and "deep implants" 33.1% each. Dental professionals had better knowledge of the causes (t = 8.189, P < 0.001) and management (t = 8.289, P < 0.001) of BT than the non-dental participants. The dentists had the best knowledge, while the laypeople had the least knowledge of the causes (F = 62.056, P < 0.001) and treatment (F = 46.120, P < 0.001) of BT. The knowledge of the causes (t = 0.616, P = 0.538) and treatment (t = 1.113, P = 0.266) for BT was not significantly different between males and females. Age was not significantly related to the total knowledge about the causes (r = -0.034, P = 0.475) or treatment (r = -0.034, P = 0.482) for BT. Dental professionals had better knowledge of the impacts, causes and management of BT than the non-dental participants. The dentists were the best, while the laypeople were the worst in this regard. Age and gender had no relationships with the knowledge of causes or management of BT.

Layperson assessment of smile lines and upper lip combined images in smile esthetics

STATEMENT OF PROBLEM

The esthetic assessment of smile lines by laypersons is a subject of ongoing debate. However, smile lines often appear with different types of upper lip curvature, which further complicates the esthetic assessment process, and studies on this combination are lacking.

PURPOSE

The purpose of this clinical study was to investigate a layperson's esthetic perception of smile lines and upper lip combined images.

MATERIAL AND METHODS

Twenty-six smile images resulting from combinations of 3 upper lip types, 4 anterior smile line types, and 3 posterior smile line types were generated by an image editing software program. Eighty-three laypersons (39 men and 44 women; 18 to 35 years of age) completed rating images using a visual analog scale. Unattractive smiles were designated to be those with scores <50 and attractive ones with scores ≥50. Data were analyzed using 1-way analysis of variance and Bonferroni post hoc tests (α=.05).

RESULTS

High anterior smile line with gingival display >4 mm obtained significantly lower scores of <50 when combined with all upper lip curvatures (upward: 28.29 ±22.79, straight: 38.74 ±23.00, downward: 30.67 ±22.25, P<.01). High anterior smile lines with gingival display ≤4 mm combined with upward and straight upper lip curvature images obtained significantly higher scores, and all were ≥50 (upward: 63.24 ±22.22, straight: 61.40 ±21.58, P<.01).

CONCLUSIONS

From a layperson's perspective, high anterior smile lines with gingival display >4 mm combined with any lip type were determined to be unattractive. If gingival display was ≤4 mm combined with both upward and straight lip types, the smile was assessed as attractive.

Relationships between perception of black triangles appearance, personality factors and level of education

This analytical cross-sectional study evaluated the perception of black triangles (BT) and examined the relationships between the perception of BT, personality factors, different educational backgrounds and demographic factors. 435 participants were included and divided into four groups: dentists, clinical (4th and 5th year) dental students, pre-clinical (3rd year) dental students, and laypeople. Participants' perception of the attractiveness of smile profiles of maxillary and mandibular anterior dentition with BT was rated using a ten-point VAS scale with 0 being the least, and 10 being the most attractive smile profile. The personality was assessed using the NEO-FFI personality questionnaire. The smile profile with multiple large BT was rated the least attractive for the maxillary (mean = 3.6) and mandibular (mean = 3.9) tested profiles. The smile profile without BT was rated the most attractive for the maxillary (mean = 9.1) and mandibular (mean = 8.8) tested profiles. The dental professionals perceived the maxillary smile profile with multiple large BT as less attractive than the non-dental participants (t = - 2.715, P = 0.007). Being a male, having dental education, having lower Neuroticism scores, as well as having higher Openness, Agreeableness, Conscientiousness, and Extraversion scores predicted and contributed more towards perceiving various tested smile profiles as more attractive. These findings show that black triangles negatively impacts the perception of smile attractiveness, and that personality traits and having dental education impact the perception of smile attractiveness for smiles with black triangles.

Influence of Lip Appearances and Tooth Shade on Smile Attractiveness Perception

This study determined the effect of lip thickness, lipstick color, and tooth shade on the smile attractiveness perceptions of dentists, laypersons, dental students, and other faculty students. A set of 27 smile photographs was prepared with different lip thicknesses (Tk, thick; M, medium; and Tn, thin), lipstick shade (R, red; P, pink; and O, orange), and tooth shades (0M1, 0M3, and A1). A total of 212 Thai participants in four rater groups (dentists, laypersons, dental students, and other faculty students) rated smile attractiveness using a visual analog scale (VAS). Statistical analyses were performed using the Kruskal-Wallis test and pairwise analysis at a 0.05% level of significance. Tk or M lip thickness was associated with more smile attractiveness than Th lip thickness. The R lipstick is more attractive than the P and O lipsticks. The 0M1 tooth shade appeared to be the most attractive for laypersons and other faculty students, whereas tooth shades (0M1, 0M3, or A1) did not influence the smile attractiveness perception of dentists and dental students. The smile attractiveness perception was influenced by the lip appearance and tooth shade for each rater group, which are essential for an attractive smile design.

Accuracy of three-dimensional optical devices for facial soft-tissue measurement in clinical practice of stomatology: A PRISMA systematic review

BACKGROUND

The accuracy of 3-dimensional (3D) optical devices for facial soft-tissue measurement is essential to the success of clinical treatment in stomatology. The aim of the present systematic review was to summarize the accuracy of 3D optical devices used for facial soft-tissue assessment in stomatology.

METHODS

An extensive systematic literature search was performed in the PubMed/MEDLINE, Embase, Scopus and Cochrane Library databases for studies published in the English language up to May 2022 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Peer-reviewed journal articles evaluating the facial soft-tissue morphology by 3D optical devices were included. The risk of bias was performed using the Quality Assessment Tool for Diagnostic Accuracy Studies-2 guidelines by the 2 reviewers. The potential publication bias was analyzed using the Review Manager software.

RESULTS

The query returned 1853 results. A total of 38 studies were included in this review. Articles were categorized based on the principle of devices: laser-based scanning, structured-light scanning, stereophotogrammetry and red, green, blue-depth camera.

CONCLUSION

Overall, the 3D optical devices demonstrated excellent accuracy and reliability for facial soft-tissue measurement in stomatology. red, green, blue-depth camera can collect accurate static and dynamic 3D facial scans with low cost and high measurement accuracy. Practical needs and availability of resources should be considered when these devices are used in clinical settings.

The Effect of Perioral Scan and Artificial Skin Markers on the Accuracy of Virtual Dentofacial Integration: Stereophotogrammetry Versus Smartphone Three-Dimensional Face-Scanning

This study evaluated the effects of different matching methods on the accuracy of dentofacial integration in stereophotogrammetry and smartphone face-scanning systems. The integration was done (N = 30) with different matching areas (n = 10), including teeth image only (TO), perioral area without markers (PN) and with markers (PM). The positional accuracy of the integrated models was assessed by measuring the midline linear deviations and incisal line canting between the experimental groups and laser scanner-based reference standards. Kruskal–Wallis and Mann–Whitney U tests were used for statistical analyses (α = 0.05). The PM method exhibited the smallest linear deviations in both systems; while the highest deviations were found in the TO in stereophotogrammetry; and in PN in smartphone. For the incisal line canting; the canting degree was the lowest in the PM method; followed by that in the TO and the PN in both systems. Although stereophotogrammetry generally exhibited higher accuracy than the smartphone; the two systems demonstrated no significant difference when the perioral areas were used for matching. The use of perioral scans with markers enables accurate dentofacial image integration; however; cautions should be given on the accuracy of the perioral image obtained without the use of markers.

Accuracy of Portable Face-Scanning Devices for Obtaining Three-Dimensional Face Models: A Systematic Review and Meta-Analysis

The use of three-dimensional face-scanning systems to obtain facial models is of increasing interest, however, systematic assessments of the reliability of portable face-scan devices have not been widely conducted. Therefore, a systematic review and meta-analysis were performed considering the accuracy of facial models obtained by portable face-scanners in comparison with that of those obtained by stationary face-scanning systems. A systematic literature search was conducted in electronic databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for articles published from 1 January 2009 to 18 March 2020. A total of 2806 articles were identified, with 21 articles available for the narrative review and nine studies available for meta-analysis. The meta-analysis revealed that the accuracy of the digital face models generated by the portable scanners was not significantly different from that of the stationary face-scanning systems (standard mean difference (95% confidence interval) = -0.325 mm (-1.186 to 0.536); z = -0.74; p = 0.459). Within the comparison of the portable systems, no statistically significant difference was found concerning the accuracy of the facial models among scanning methods (p = 0.063). Overall, portable face-scan devices can be considered reliable for obtaining facial models. However, caution is needed when applying face-scanners with respect to scanning device settings, control of involuntary facial movements, landmark and facial region identifications, and scanning protocols.