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. 2023 Jun;9(3):455-463.
doi: 10.1002/cre2.735. Epub 2023 Apr 18.

Establishing standards for Yonsei point in a White South African population for the treatment of gummy smile

Brandon Booysen  1 , René H Baron  1 , André Uys  1
Affiliations

Establishing standards for Yonsei point in a White South African population for the treatment of gummy smile

Brandon Booysen et al. Clin Exp Dent Res. 2023 Jun.

Abstract

Introduction: The purpose of this study is to establish the efficacy of Yonsei point in the treatment of a gummy smile in a White South African population. The accurate surface anatomy criteria in relation to the underlying musculature for the administration of Botulinum toxin injections in the treatment of gummy smile was determined.

Materials and methods: Nineteen (10 males and 9 females) cadavers were selected for facial dissection. Facial profile photographs were taken before and after dissection. The before and after photographs were overlayed to determine where the pin positions should be on the dissected cadaver to determine the Yonsei point. The levator labii superioris (LLS), LLS alaeque nasi (LLSAN), zygomaticus minor, and zygomaticus major muscles were measured using a protractor and ruler, which accounted for the manual measurements. Digital measurements were measured by importing dissected images into ImageJ. Circles with a 2 cm diameter (1 cm radius) were constructed to determine whether the Yonsei point could successfully influence muscles fibers.

Results: Digital and manual measurements show comparable results with high correlation and reliability. Results showed that the White South African population had narrower facial musculature angles as compared with the Korean population.

Conclusion: Based on the selected sample, the Yonsei point is an ineffective injection site for the successful treatment of gummy smile in a White South African population.

Keywords: Yonsei point; botox injections; hyperactive lip elevator muscles; injection landmark radii.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Pin positions 1– 6, (b) constructed triangle, (c) frontal photograph of cadaver with pin positions, (d) perpendicular photograph (to the surface of the pins) of the cadaver showing pin positions.
Figure 2
Figure 2
(a) Frontal and (b) perpendicular photograph of a dissected cadaver.
Figure 3
Figure 3
(a) Muscle vector directions in relation to the midline of the face, (b) muscle vector directions and Botox spread (2 cm) on dissected cadaver, (c) overlaid photograph showing Botox spread at Yonsei point and the individual injection landmarks.
Figure 4
Figure 4
(a) Injection landmark zones and (b) overlap of Yonsei point radius with the injection landmark radii.
Figure 5
Figure 5
(a) The differences between the muscle angles in the male Korean and male South African population. (b) The differences between the muscle angles in the female Korean and female South African population.
Figure 6
Figure 6
(a, c, e) Yonsei point (yellow) with overlap of individual injection sites and (b, d, f) corresponding cadaver with new proposed injection landmarks (red) located at the center of the planes running between the specific injection landmarks.
See this image and copyright information in PMC

References

    1. Agur, A. M. R. , Dalley II, A. F. , & Moore, K. L. (2019). Moore's essential clinical anatomy (6th ed.). Wolters Kluwer.
    1. Al Wayli, H. (2019). Versatility of botulinum toxin at the Yonsei point for the treatment of gummy smile. The International Journal of Esthetic Dentistry, 14(1), 86–95. - PubMed
    1. Bobak, C. A. , Barr, P. J. , & O'Malley, A. J. (2018). Estimation of an inter‐rater intra‐class correlation coefficient that overcomes common assumption violations in the assessment of health measurement scales. BMC Medical Research Methodology, 18(1), 93. 10.1186/s12874-018-0550-6 - DOI - PMC - PubMed
    1. Davenport, T. R. H. , & Saunders, C. C. (2000). South Africa: A modern history (5th ed.). Macmillan Press, St. Martin's Press.
    1. Dong, J. K. , Jin, T. H. , Cho, H. W. , & Oh, S. C. (1999). The esthetics of the smile: a review of some recent studies. The International Journal of Prosthodontics, 12(1), 9–19. - PubMed