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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| the average-dose method | Active Comparator | With the average-dose method, the dose was individualized according to the severity of anterior gingival exposure pretreatment. For mild gingival smile (3-5 mm), a single-site injection of 2 U botulinum toxin type A [total, 4 U] at both the right and left levator labii superioris alaeque nasi muscles) was administered. For moderate (5-7 mm) and severe (≥7 mm) gingival smile, 3 U and 5 U of botulinum toxin type A, respectively, were injected per side (total, 6 U and 10U, respectively). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point26, with half doses administered at each point. |
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| the higher-dose method | Experimental | With this method, patients were administered botulinum toxin type A after 8 months when the effect of the previous injection had vanished. The injection dose (U) per side was set as the absolute value of the preoperative anterior gingival exposure (mm). For example, if the preoperative anterior gingival exposure was 5mm, then the patient would be injected with 5 U of botulinum toxin per side (total, 10U). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point26, with half doses administered at each point. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| injection of Botulinum type A | Drug | The participates were allocated to two different application methods: Simplified Method for the first injection and Individualized Method 8 months later. All the patients underwent twice injection with each methods with no change of the BTX-A(Botox, Allergan, Irvine, CA) and other injection details: Lyophilized 100 U of Botox was reconstituted in 2.5 mL of 0.9% sodium chloride solution. The injections were made with a 27-gauge insulin syringe. The treatment was an outpatient procedure and all injections were performed by one of the authors (X.G.). No anesthesia was given during the procedure. |
| Measure | Description | Time Frame |
|---|---|---|
| Anterior Gingival Exposure (GE) 4 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | 4 weeks postinjection |
| Measure | Description | Time Frame |
|---|---|---|
| Anterior Gingival Exposure (GE) 12 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | 12 weeks postinjection |
| Anterior Gingival Exposure (GE) 24 Weeks Post-injection |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Xi Gong | Peking University School of Stomatology | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Peking University School and Hospital of Stomatology | Beijing | Beijing Municipality | 100010 | China |
According to the estimated sample size, 33 participants need to be included in the study, and 33 people were actually included, but this study was a prospective, self-controlled clinical study, which is two treatments for the same group of patients, so the total sample size is 33 people.
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| ID | Title | Description |
|---|---|---|
| FG000 | The Treatment Group | In this prospective self-controlled study, healthy participants with gummy smile underwent two treatment methods. First, participants were injected with the average-dose, which the dose was individualized according to the severity of anterior gingival exposure pretreatment. For mild gingival smile (3-5 mm), a single-site injection of 2 U botulinum toxin type A [total, 4 U] at both the right and left levator labii superioris alaeque nasi muscles) was administered. For moderate (5-7 mm) and severe (≥7 mm) gingival smile, 3 U and 5 U of botulinum toxin type A, respectively, were injected per side (total, 6 U and 10U, respectively). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point, with half doses administered at each point. And 8 months later All the patients underwent second injection of the higher-dose method. With this method, patients were administered botulinum toxin type A after 8 months when the effect of the previous injection had vanished. The injection dose (U) per side was set as the absolute value of the preoperative anterior gingival exposure (mm). For example, if the preoperative anterior gingival exposure was 5mm, then the patient would be injected with 5 U of botulinum toxin per side (total, 10U). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point, with half doses administered at each point. |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| the Average-dose Period |
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| the Higher-dose Method Period |
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| ID | Title | Description |
|---|---|---|
| BG000 | The Treatment Group | In this prospective self-controlled study, healthy participants with gummy smile underwent two treatment methods. First, participants were injected with the average-dose, which the dose was individualized according to the severity of anterior gingival exposure pretreatment. For mild gingival smile (3-5 mm), a single-site injection of 2 U botulinum toxin type A [total, 4 U] at both the right and left levator labii superioris alaeque nasi muscles) was administered. For moderate (5-7 mm) and severe (≥7 mm) gingival smile, 3 U and 5 U of botulinum toxin type A, respectively, were injected per side (total, 6 U and 10U, respectively). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point, with half doses administered at each point. And 8 months later All the patients underwent second injection of the higher-dose method. With this method, patients were administered botulinum toxin type A after 8 months when the effect of the previous injection had vanished. The injection dose (U) per side was set as the absolute value of the preoperative anterior gingival exposure (mm). For example, if the preoperative anterior gingival exposure was 5mm, then the patient would be injected with 5 U of botulinum toxin per side (total, 10U). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point, with half doses administered at each point. |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Categorical | Count of Participants |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | Anterior Gingival Exposure (GE) 4 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | Posted | Mean | Standard Deviation | mm | 4 weeks postinjection |
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For follow-up of the first injection, the participants was followed up at 4, 12 weeks and 48 weeks. For the re-injection, the participants was followed up at 4, 12, 48 weeks.
The intervention in this study is low-dose injection of botulinum toxin (6U/person), which is very safe, with no participants at risk for Serious Adverse Events or for All-Cause Mortality.
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | the First Injection（the Average-dose Method） | With the average-dose method, the dose was individualized according to the severity of anterior gingival exposure pretreatment. For mild gingival smile (3-5 mm), a single-site injection of 2 U botulinum toxin type A [total, 4 U] at both the right and left levator labii superioris alaeque nasi muscles) was administered. For moderate (5-7 mm) and severe (≥7 mm) gingival smile, 3 U and 5 U of botulinum toxin type A, respectively, were injected per side (total, 6 U and 10U, respectively). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point26, with half doses administered at each point. injection of Botulinum type A: The participates were allocated to two different application methods: Simplified Method for the first injection and Individualized Method 8 months later. All the patients underwent twice injection with each methods with no change of the BTX-A(Botox, Allergan, Irvine, CA) and other injection details: Lyophilized 100 U of Botox was reconstituted in 2.5 mL of 0.9% sodium chloride solution. The injections were made with a 27-gauge insulin syringe. The treatment was an outpatient procedure and all injections were performed by one of the authors (X.G.). No anesthesia was given during the procedure. |
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| Term | Organ System | Source Vocabulary | Assessment Type | Notes | Statistical Information |
|---|---|---|---|---|---|
| Slight lip ptosis | Skin and subcutaneous tissue disorders | Systematic Assessment | patients felt slight lip ptosis at 1-2 weeks after injection, which disappeared within 4 weeks without further intervention. |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Xi Gong | Peking University School of Stomatology | 15201304426 | gongx31480528@163.com |
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot_SAP | Yes | Yes | No | Study Protocol and Statistical Analysis Plan | Nov 20, 2019 | Oct 26, 2022 | Prot_SAP_000.pdf |
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| ID | Term |
|---|---|
| D012904 | Smiling |
| ID | Term |
|---|---|
| D005149 | Facial Expression |
| D009633 | Nonverbal Communication |
| D003142 | Communication |
| D001519 | Behavior |
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The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. |
| 24 weeks postinjection |
| Anterior Gingival Exposure (GE) 48 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | 48 weeks postinjection |
| Participants |
|
| Age, Continuous | Mean | Standard Deviation | years |
|
| Sex: Female, Male | Count of Participants | Participants |
|
| Race and Ethnicity Not Collected | Race and Ethnicity were not collected from any participant. | Count of Participants | Participants |
|
| Region of Enrollment | Number | participants |
|
| anterior gingival exposure | Mean | Standard Deviation | mm |
|
| OG001 | the Second Injection(the Higher-dose Method) | With this method, patients were administered botulinum toxin type A after 8 months when the effect of the previous injection had vanished. The injection dose (U) per side was set as the absolute value of the preoperative anterior gingival exposure (mm). For example, if the preoperative anterior gingival exposure was 5mm, then the patient would be injected with 5 U of botulinum toxin per side (total, 10U). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point26, with half doses administered at each point. injection of Botulinum type A: The participates were allocated to two different application methods: Simplified Method for the first injection and Individualized Method 8 months later. All the patients underwent twice injection with each methods with no change of the BTX-A(Botox, Allergan, Irvine, CA) and other injection details: Lyophilized 100 U of Botox was reconstituted in 2.5 mL of 0.9% sodium chloride solution. The injections were made with a 27-gauge insulin syringe. The treatment was an outpatient procedure and all injections were performed by one of the authors (X.G.). No anesthesia was given during the procedure. |
|
|
| Secondary | Anterior Gingival Exposure (GE) 12 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | Posted | Mean | Standard Deviation | mm | 12 weeks postinjection |
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| Secondary | Anterior Gingival Exposure (GE) 24 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | Posted | Mean | Standard Deviation | mm | 24 weeks postinjection |
|
|
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| Secondary | Anterior Gingival Exposure (GE) 48 Weeks Post-injection | The distance from the superior margin point of the right incisor to the lower margin of the upper lip upon maximum smile. | Posted | Mean | Standard Deviation | mm | 48 weeks postinjection |
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| 0 |
| 33 |
| 0 |
| 33 |
| 5 |
| 33 |
| EG001 | the Second Injection（the Higher-dose Method） | With this method, patients were administered botulinum toxin type A after 8 months when the effect of the previous injection had vanished. The injection dose (U) per side was set as the absolute value of the preoperative anterior gingival exposure (mm). For example, if the preoperative anterior gingival exposure was 5mm, then the patient would be injected with 5 U of botulinum toxin per side (total, 10U). The injection points were located at bilateral levator labii superioris alaeque nasi muscles and at the Yonsei point26, with half doses administered at each point. injection of Botulinum type A: The participates were allocated to two different application methods: Simplified Method for the first injection and Individualized Method 8 months later. All the patients underwent twice injection with each methods with no change of the BTX-A(Botox, Allergan, Irvine, CA) and other injection details: Lyophilized 100 U of Botox was reconstituted in 2.5 mL of 0.9% sodium chloride solution. The injections were made with a 27-gauge insulin syringe. The treatment was an outpatient procedure and all injections were performed by one of the authors (X.G.). No anesthesia was given during the procedure. | 0 | 33 | 0 | 33 | 4 | 33 |
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