Clinical Trial Details
— Status: Completed
Administrative data
NCT number |
NCT05127018 |
Other study ID # |
pkusshighdose |
Secondary ID |
|
Status |
Completed |
Phase |
Phase 1/Phase 2
|
First received |
|
Last updated |
|
Start date |
November 20, 2019 |
Est. completion date |
October 20, 2021 |
Study information
Verified date |
April 2023 |
Source |
Peking University |
Contact |
n/a |
Is FDA regulated |
No |
Health authority |
|
Study type |
Interventional
|
Clinical Trial Summary
Botulinum type A (BTX-A) is an easy and efficacious treatment for gingival smile (GS).
However, the necessary for higher-doses among patients are controversial. The objective was
to compare the reduction of gingival exposure using two methods in patients with different
dosage. In this prospective self-controlled study, healthy GS participates who had an
anterior gingival exposure (GE) of more than 3 mm were enrolled and administered with 2-5 U
BTX-A (total, 4-10 U) injections into 1-2 points according to the severity presented
pretreatment in the Average-dose Method. And after 8 months, the Higher-doses Method was
administered the same point injection of 3-10 U BTX-A (total, 6-20 U). Data were collected at
baseline and 4, 12, 32 and 60 weeks of follow-up.
Description:
The smile is one of the universal facial expressions of humans. Gingival smile is
characterized by gingival exposure of >3 mm upon smiling. The degree of gingival exposure can
vary substantially between patients, with patients presenting gingival exposure of up to more
than 10 mm. The prevalence of gingival smile is 10.57%, and it is more frequently observed in
females. Although gingival smile is merely an anatomical variation, it can be considered
unattractive, causing significant distress and impacting one's quality of life. Moreover,
most orthodontists and dentists regard gingival smile as an important risk factor for dental
treatment.
Gingival smile involves a complex interaction between the facial muscles, bone, and skin;
specifically, it is related to hypermobility of the upper lip with muscle involvement and
alterations in anatomical features, such as a short clinical dental crown, anterior
dentoalveolar extrusion, maxillary excess, and a short upper lip. Therapies for gingival
smile range from botulinum toxin injections to surgical interventions according to its
etiology. Although the outcomes of surgical procedures are long-lasting, botulinum toxin type
A treatment is an easy and fast outpatient procedure that requires no downtime and has high
efficacy rates. Nevertheless, there are controversies around the optimal dose and injection
site of botulinum toxin type A. Moreover, the efficiency of botulinum toxin type A for
gingival smile varies markedly between studies, with the improvement rate of gingival
exposure ranging from 62.06% to 98%. Sucupira and Abramovitz advocate the use of a low amount
of botulinum toxin type A of 1.95 U per side for the treatment of gingival smile. They noted
an average satisfaction level of 9.75 on a 10-point scale with this approach. They claimed
that higher doses does not provide further benefit, and, in fact, could lead to lip ptosis,
asymmetry, and excessive upper lip length. However, Polo disagreed with their argument,
claiming 2-5 U injection of botulinum toxin type A according to the severity of gingival
smile. In this regard, Garcia and Fulton showed that low-dose injection of botulinum toxin
per muscle (2-5 IU) was as effective as higher doses. Though prior studies have demonstrated
a correlation between higher doses of botulinum toxin and intensity and duration of muscle
paralyses, no conclusion can be drawn regarding duration and intensity of doses used in the
recent studies. A safe approach advocated by some authors consists of starting with low toxin
doses initially, with retouching at a later stage if required. In this study, the
investigators compared botulinum toxin type A efficiency using the average-dose method (2-5 U
botulinum toxin type A per side determined according to the severity of anterior gingival
smile) and , the higher-dose method (3-10 U botulinum toxin type A per side determined
according to the severity of anterior gingival smile). The investigators aimed to assess the
efficiency and duration of these approaches, as well as side effects and patients'
satisfaction with treatment.