Comparison of Effectiveness, Duration, and Patient’s Satisfaction of Botulinum Toxin A and Hyaluronic Filler in the Treatment of Gummy Smile: An in Vivo Study

ABSTRACT

Aim:

This study aimed to compare the effectiveness, duration, and patient satisfaction of botulinum toxin A (BTX-A) and hyaluronic fillers in treating gummy smiles.

Materials and Method:

A prospective clinical study was conducted at D.Y. Patil University, involving 14 patients aged 18–40 years with a gummy smile of ≥3 mm. Participants were divided into two groups: Group A (BTX-A injections) and Group B (hyaluronic fillers). Gingival display was measured using standardized photographic methods at baseline and follow-up visits (14, 30, 60, and 90 days). Patient satisfaction was evaluated using the Global Aesthetic Improvement Scale (GAIS).

Result:

The results indicated that while BTX-A provided immediate improvements, hyaluronic fillers demonstrated more consistent and prolonged results. Patient satisfaction was higher in the hyaluronic filler group, with most patients reporting exceptional improvement (GAIS score of 1) across all follow-ups. No severe adverse effects were observed in either group.

Conclusion:

Hyaluronic fillers demonstrate superior effectiveness and patient satisfaction compared to BTX-A in the treatment of gummy smiles.

INTRODUCTION

Smile is the main facial emotion of joy, pleasure, and hope, and it is crucial for socialization.[1] It has been shown that when the gingival exposure is more than 2 mm above the dental line, a gummy smile or excessive gingival display results.[2]

Due to increasing desire for the best possible dental aesthetics, (nonsurgical) face aesthetics received attention from the dental community. Dental manufacturers started to make these materials more widely available and highlighted them in their catalogues and ads as a result of patient demands for specific compounds, such as hyaluronic acid fillers and botulinum toxin.

MATERIALS AND METHOD

For this study, 14 patients who were unwilling to undergo any surgical treatment for their gummy smile and had finished their fixed orthodontic treatments were chosen. A thorough case history was acquired.

Procedure

Post-orthodontic patients were equally divided into two groups (seven each):

GROUP A: received BTX-A in the treatment of gummy smile.

GROUP B: received hyaluronic acid (Restylane) filler in the treatment of gummy smile.

Group A: Botulinum toxin A injection site

Method of injection

With prior application of a topical lidocaine, the levator labii superioris alaeque nasi [Figure 1], levator labii superioris muscles, and the zygomaticus minor on either side of the face were the landmarks where 2.5-U injection of type-A botulinum toxin at YONSEI POINT was injected with the 31-gauge/8-mm needle.

Figure 1.

Injection site for botulinum toxin A

Group 2: Hyaluronic acid injection site

Method of injection

Lidocaine lotion was applied to prepare the area. The required needle size was 31 gauge/8 mm. Administration of 23 mg/mL hyaluronic acid was done using a blunt microcannula (25 G and 50 mm) into the deep layer of the canine fossa (0.2 to 0.3 mL) and 0.2 to 0.4 mL was injected at the bone level over the anterior nasal spine and/or in a multilayer approach [Figure 2].

Figure 2.

Injection site for hyaluronic acid

A scale and a Vernier caliper were used to measure the gingival display in BTX-A group and hyaluronic acid group. The values were computed on the day that hyaluronic acid and BTX-A group administered as well as after two weeks, at 30, 60, and 90 days.

Statistical test

Paired samples t-test, repeated measures ANOVA, and descriptive statistical analysis were used.

RESULTS

A P value of 0.372 indicated that there was no statistically significant difference in the age distribution between the Botox group and the hyaluronic acid filler group.

The distribution of sexes in the two groups did not differ significantly.

GINGIVAL SHOW at different time points

A significant difference in the gingival show was observed between the two groups on the 60^th day and 90^th day, with the Botox group showing a larger gingival show compared to the hyaluronic acid filler group.

• Between group comparisons for gingival show, the P > 0.077 on injection day (baseline), P > 0.190 on day 14, P > 0.132 on day 30, which was not significant, P < 0.0001 on day 60, which was significant, and P < 0.0001 on day 90, which was significant [Table 1].

Table 1.

Between-group comparisons for Gingival show (GS)

Group		Injection day	Day 14	Day 30	Day 60	Day 90
BTX	n	7	7	7	7	7
	Mean	4.74	2.59	3.24	4.11	4.74
	SD	0.53	0.50	0.62	0.50	0.53
	Median	4.90	2.70	3.50	4.20	4.90
	Minimum	3.9	1.5	2.0	3.5	3.9
	Maximum	5.4	2.9	3.8	4.7	5.4
	Range	1.5	1.4	1.8	1.2	1.5
HA	N	7	7	7	7	7
	Mean	5.30	2.86	2.86	2.86	2.86
	SD	0.55	0.13	0.13	0.13	0.13
	Median	5.50	2.90	2.90	2.90	2.90
	Minimum	4.5	2.7	2.7	2.7	2.7
	Maximum	6.0	3.0	3.0	3.0	3.0
	Range	1.5	0.3	0.3	0.3	0.3
Between	Mean Diff.	-0.56	-0.27	0.39	1.26	1.89
group
differences
	95% C.I.	-1.19	-0.70	-0.13	0.83	1.44
	(L)
	95% C.I.	0.07	0.15	0.91	1.69	2.34
	(U)
	t	-1.931	-1.388	1.615	6.390	9.123
	df	12	12	12	12	12
	P	0.077	0.190	0.132	<0.0001	<0.0001

Interpretation

Global Aesthetic Improvement Scale (GAIS) in two groups in Mann–Whitney “U” test on injection day the P > 1.000, on 14^th day P > 1.000, on 30^th day P > 1.000, on 60^th day P < 0.001, and on 90^th day P < 0.001 [Table 2].

Table 2.

(GAIS) in two groups

		BTX (n=07)		HA (n=07)		Mann-Whitney ’U’ test
		No.	%	No.	%	Z	P
Injection	Exceptional	0	0.0%	0	0.0%	0.000	1.000
day	improvement
	Very improved	0	0.0%	0	0.0%
	patient
	Improved patient	0	0.0%	0	0.0%
	Unaltered patient	7	100.0%	7	100.0%
	Worsened patient	0	0.0%	0	0.0%
Day 14	Exceptional	7	100.0%	7	100.0%	0.000	1.000
	improvement
	Very improved	0	0.0%	0	0.0%
	patient
	Improved patient	0	0.0%	0	0.0%
	Unaltered patient	0	0.0%	0	0.0%
	Worsened patient	0	0.0%	0	0.0%
Day 30	Exceptional	7	100.0%	7	100.0%	0.000	1.000
	improvement
	Very improved	0	0.0%	0	0.0%
	patient
	Improved patient	0	0.0%	0	0.0%
	Unaltered patient	0	0.0%	0	0.0%
	Worsened patient	0	0.0%	0	0.0%
Day 60	Exceptional	0	0.0%	7	100.0%	3.606	<0.001
	improvement
	Very improved	0	0.0%	0	0.0%
	patient
	Improved patient	0	0.0%	0	0.0%
	Unaltered patient	7	100.0%	0	0.0%
	Worsened patient	0	0.0%	0	0.0%
Day 90	Exceptional	0	0.0%	7	100.0%	3.606	<0.001
	improvement
	Very improved	0	0.0%	0	0.0%
	patient
	Improved patient	0	0.0%	0	0.0%
	Unaltered patient	0	0.0%	0	0.0%
	Worsened patient	7	100.0%	0	0.0%

Side effects: None of the patients underwent major side effects, mild redness, and swelling, but no adverse effects were seen.

DISCUSSION

Gummy smile is an unhealthy smile in which the gums on the palate protrude too much.[3] In our study, since age and gender were evenly distributed, the observed differences were due to the treatment effects rather than demographic factors. While both treatments showed similar effects in the initial weeks, Botox led to a significantly greater gingival show by the 60^th and 90^th days.

In our study, both Botox and HA filler initially provided comparable aesthetic improvements. However, from day 60 onward, HA filler showed significantly better long-term aesthetic outcomes, while Botox’s effects diminished.

Cengiz et al., in 2020,[4] found that patients with higher gingival exposure may benefit from Botox injections. Kandhari et al.[5] showed that hyaluronic acid has been reported to be effective in cases where lip asymmetry is significant and is an easy nonsurgical alternative.

Hsien-Li Peng and Peng[6] reported that a less invasive therapeutic method for GS has been suggested in the form of HA fillers.

CONCLUSION

According to the study’s findings, hyaluronic fillers had a longer duration of effectiveness and higher patient satisfaction while BTX-A had a speedier commencement of action.

Ethical clearance

The D.Y. Patil School of Dentistry’s Institutional Review Board in Nerul, Navi Mumbai, granted the study ethical permission.

Informed consent

Every participant provided written informed permission.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.