Face
Conditions
Keywords
Hard Gum Chewing, Facial Morphology, 3dMD, Stereophotogrammetry, Facial Soft Tissue, Heatmap Analysis, Chewing Gum, Masticatory Muscles, Three-Dimensional Imaging, Surface Distance Mapping
Brief summary
This pilot clinical trial will evaluate whether intentional chewing of a standardized hard chewing gum for 4 weeks produces measurable changes in facial morphology in healthy adults. Twenty participants aged 20-40 years will undergo three-dimensional facial imaging (3dMD) at baseline (T0), after the 4-week chewing intervention (T1), and following a 4-5-week washout period (T2). Changes in facial soft-tissue morphology will be assessed using three-dimensional surface analysis, including heatmaps, regional surface displacement, and morphometric measurements. Secondary outcomes include self-reported muscle fatigue, soreness, adherence, and temporomandibular disorder (TMD) symptoms.
Detailed description
Facial morphology is influenced by multiple functional factors, including masticatory muscle activity. Although hard gum chewing has been promoted as a method to improve facial definition and jawline appearance, there is limited scientific evidence demonstrating whether intentional chewing can produce measurable changes in facial soft tissues. The purpose of this prospective pilot clinical trial is to evaluate the effect of intentional hard gum chewing on facial morphology using three-dimensional stereophotogrammetry (3dMD). Twenty healthy adults aged 20-40 years will be enrolled. Participants will complete a standardized hard-gum chewing protocol every other day for 4 weeks. Each chewing session will last approximately 16 minutes and will follow a predefined protocol designed to provide a consistent masticatory stimulus. Three-dimensional facial images will be obtained at baseline (T0), immediately after the intervention period (T1), and after a 4-5-week washout period (T2). Facial changes will be assessed through surface registration techniques, heatmap analysis, regional displacement measurements, and linear and angular soft-tissue measurements. Participants will also complete questionnaires regarding muscle fatigue, soreness, oral behaviors, and temporomandibular symptoms. The primary objective is to determine whether intentional hard gum chewing produces measurable changes in facial morphology. Secondary objectives include evaluating participant-reported outcomes and monitoring for adverse events or symptoms suggestive of temporomandibular disorders. Because this is a pilot study, the results will be used to estimate effect sizes and feasibility for future larger clinical trials investigating the relationship between masticatory activity and facial soft-tissue adaptation.
Interventions
BEHAVIORALHard Gum Chewing
Participants will chew a standardized hard chewing gum (Jawliner®, hard hardness level) every other day for 4 weeks. Each session will consist of two 8-minute chewing blocks following a standardized protocol with controlled chewing pace, progressive force application, and alternating chewing sides. Total chewing time per session will be approximately 16 minutes.
Sponsors
UConn Health
Charles Burstone Foundation
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
20 Years to 40 Years
Healthy volunteers
No
Inclusion criteria
* Healthy, non-smoking adults. * Age 20 to 40 years. * Presence of a full dentition from central incisor to first molar in all four quadrants, excluding second molars. * Stable occlusion with no ongoing orthodontic treatment or myofunctional therapy. * Ability and willingness to comply with the prescribed hard-gum chewing regimen for 4 weeks and attend all study visits. * Ability to provide written informed consent.
Exclusion criteria
* Age younger than 20 years or older than 40 years. * Evident facial asymmetry from a frontal view. * Signs or symptoms of temporomandibular disorders (TMD) according to the Diagnostic Criteria for TMD (DC/TMD). * Less than the normal range of condylar motion during maximum opening and closing. * Parafunctional habits such as bruxism with pain, clenching, or habitual gum chewing for more than 1 hour per day. * History of major craniofacial trauma, orthognathic surgery, or congenital craniofacial anomalies. * Ongoing orthodontic treatment or recent removal of fixed appliances (\<6 months). * Significant malocclusion or missing teeth in the anterior or premolar-first molar region that may affect mastication. * Systemic diseases or medications affecting muscle or bone metabolism. * Previous use of botulinum toxin (Botox) within the last 6 months or anticipated use during the study period. * Pregnancy or lactation. * Allergy or intolerance to the chewing gum ingredients.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Changes in Facial Morphology Assessed by 3dMD Stereophotogrammetry | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Quantification of facial morphology changes using three-dimensional stereophotogrammetry, including regional surface distance maps (heatmaps), linear and angular measurements, and global and regional RMS deviation values. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Soft-Tissue Surface Topography Changes | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Evaluation of localized hypertonia and volumetric shifts using three-dimensional heatmap analysis and regional surface displacement measurements. |
| Change in Body Weight | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Body weight will be measured in kilograms using a calibrated digital scale to monitor changes in body weight that could influence facial soft-tissue morphology. |
| Body Height | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Standing height will be measured in centimeters using a Scale. Height will be used together with body weight to characterize participants' body size and, when applicable, to calculate body mass index. |
| Participant-Reported Muscle Fatigue, Soreness, and Facial Definition Perception | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Self-reported outcomes related to muscle fatigue, soreness, chewing effort, and perceived facial definition collected through study questionnaires. |
| Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Symptom Questionnaire | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of temporomandibular disorder symptoms using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I Symptom Questionnaire. This questionnaire is part of the standardized DC/TMD diagnostic protocol and evaluates jaw pain, headache attributed to TMD, joint noises, jaw locking, and functional symptoms. Responses are recorded as presence or absence of symptoms and do not generate a total score. Presence/absence of symptoms (Yes/No). This questionnaire does not generate a total score. |
| Oral Behaviors | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of oral parafunctional behaviors using the Oral Behaviors Checklist (OBC), one of the DC/TMD Axis II instruments. The questionnaire consists of 21 items assessing awake and sleep-related oral behaviors. A total score ranging from 0 to 84 will be calculated, with higher scores indicating more frequent oral parafunctional behaviors. |
| Patient Health Questionnaire-4 (PHQ-4) | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of psychological distress using the Patient Health Questionnaire-4 (PHQ-4), included as part of the DC/TMD Axis II psychosocial assessment. Total scores range from 0 to 12, with higher scores indicating greater psychological distress. |
| Jaw Functional Limitation Scale-8 (JFLS-8) | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of jaw functional limitation using the Jaw Functional Limitation Scale-8 (JFLS-8), a DC/TMD Axis II instrument. The questionnaire evaluates limitations in mastication, jaw mobility, and verbal and emotional expression. Scores range from 0 to 10, with higher scores indicating greater functional limitation. |
| Patient Health Questionnaire-9 (PHQ-9) | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of depressive symptoms using the Patient Health Questionnaire-9 (PHQ-9), administered as part of the DC/TMD Axis II psychosocial evaluation. Total scores range from 0 to 27, with higher scores indicating greater depression severity. |
| Jaw Functional Limitation Scale-20 (JFLS-20) | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of jaw functional limitation using the Jaw Functional Limitation Scale-20 (JFLS-20), a DC/TMD Axis II instrument. Scores range from 0 to 10, with higher scores indicating greater functional limitation. |
| Generalized Anxiety Disorder-7 (GAD-7) | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of anxiety symptoms using the Generalized Anxiety Disorder-7 (GAD-7), administered as part of the DC/TMD Axis II psychosocial evaluation. Total scores range from 0 to 21, with higher scores indicating greater anxiety severity. |
| Patient Health Questionnaire-15 (PHQ-15) | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Assessment of somatic symptom burden using the Patient Health Questionnaire-15 (PHQ-15), administered as part of the DC/TMD Axis II psychosocial evaluation. Total scores range from 0 to 30, with higher scores indicating greater somatic symptom severity. |
| Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Clinical Examination | Baseline (T0), Post-Intervention (T1, 4-5 weeks), and Washout (T2, 8-9 weeks) | Clinical examination performed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I Examination Protocol, including mandibular range of motion (mm), pain on palpation of the temporomandibular joints and masticatory muscles, pain during mandibular movements, joint sounds, and diagnostic clinical findings. Continuous variables will be reported in millimeters, and categorical findings will be reported as present or absent. |
Countries
United States
Contacts
CONTACTFlavio Uribe (Chair, Depto Orthodontics; UConn School of dental medic
CONTACTGeorgiana Defilio
PRINCIPAL_INVESTIGATORFlavio Uribe
UConn School of dental medicine
PRINCIPAL_INVESTIGATORThais Fernandes Poleti, PhD
UConn School of dental medicine
Outcome results
None listed