Masseter Muscle Stiffness After Heat Application and Percussion Therapy

Effects of Heat Application and Percussion Therapy on Masseter Muscle Stiffness Measured With Ultrasound Shear Wave Elastography

The purpose of this study is to evaluate the changes in the stiffness of the masseter muscle (a jaw muscle) before and after two types of treatment: applying commercial heat pads or using a commercial massage gun.

We will measure the muscle stiffness on the surface of the muscle using a special ultrasound probe, with a method called shear wave elastography.

When this muscle is too stiff, it's often linked to jaw pain and problems with the jaw joint - a condition known as Temporomandibular Disorder (TMD).

The goal is to find better treatment options for people with TMD and to collect data using this imaging technique.

Study Overview

• Status: Recruiting
• Conditions: Healthy Participants
• Intervention / Treatment: Device: massage gun; Device: heat treatment

Detailed Description

In our study, participants will be randomly assigned to one of two groups. This is important to ensure reliable results and is called randomization.

The two groups are as follows:

Group A:

First, the stiffness of the masseter muscle in the cheek is measured using ultrasound. Then, we will assess the mouth opening, the muscle's sensitivity to pressure, bite force, and chewing efficiency using several short tests. After that, the masseter muscle will be treated with a massage gun with a soft attachment for 2 minutes. All tests will be repeated after the treatment.

Group B:

First, the stiffness of the masseter muscle in the cheek is measured using ultrasound. Then, we will assess the mouth opening, the muscle's sensitivity to pressure, bite force, and chewing efficiency using several short tests. After that, the masseter muscle will be treated with a heat pad for 20 minutes. The heat pad will be held in place with a strap, and participants may sit and read or relax during the treatment. All tests will be repeated after the treatment.

Each participant will receive both treatments (massage gun and heat pad), but in a different order depending on group assignment. There will be a two-week washout phase between the two treatments to ensure that the effects of the first treatment do not influence the second.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Vera Colombo, PD Dr. sc. ETH; Phone Number: +41 (0)44 634 33 11; Email: vera.colombo@zzm.uzh.ch
• Study Contact Backup: Name: Nenad Lukic, Dr. med. Dr. med. dent.; Email: nenad.lukic@zzm.uzh.ch

Study Locations

• Switzerland
  • Canton of Zurich
    • Zurich, Canton of Zurich, Switzerland, 8032
      • Recruiting
      • Zentrum für Zahnmedizin

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Willingness to participate to the study
• Signed written informed consent

Exclusion Criteria:

• Inability to follow procedures or insufficient knowledge of project language, inability to give consent
• a history of drug ingestion within the past week (e.g. pain relievers, muscle relaxants, botox and anti-inflammatory drugs)
• systemic diseases
• Contraindications listed on the massage-gun instruction manual systemic and related to the use on the masseter area.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group A: First massage gun, then heat treatment; The massage gun is the new treatment (experimental). Heat treatment is already commonly used for muscle stiffness and could be considered an active comparator. However, since its specific effects on the masseter muscle are not well established, it may also be classified as experimental.	Device: massage gun; The massage gun used in this study will be equipped with a soft attachment designed for use on the face, ensuring safe and comfortable application to the masseter muscle.; Device: heat treatment; The heat treatment will be applied for 20min.; Other Names: heating pad; heat pad
Experimental: Group B: first heat treatment, then massage gun; The massage gun is the new treatment (experimental). Heat treatment is already commonly used for muscle stiffness and could be considered an active comparator. However, since its specific effects on the masseter muscle are not well established, it may also be classified as experimental.	Device: massage gun; The massage gun used in this study will be equipped with a soft attachment designed for use on the face, ensuring safe and comfortable application to the masseter muscle.; Device: heat treatment; The heat treatment will be applied for 20min.; Other Names: heating pad; heat pad

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Masseter muscle stiffness	Muscle stiffness will be assessed using shear wave elastography (SWE) via ultrasound. Results will be reported in kilopascals (kPa) and/or meters per second (m/s).	The time from the first appointment to the second (final) appointment will be two weeks.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Algometry of the Masseter Muscle	Algometry is the quantitative assessment of pain sensitivity, performed using a pressure algometer to determine pressure pain thresholds (PPTs) at specific anatomical sites.	The time from the first appointment to the second (final) appointment will be two weeks.
mouth opening	The mouth opening will be measured with a ruler.	The time from the first appointment to the second (final) appointment will be two weeks.
maximum bite force	Maximum bite force can be measured with a bite sensor or an occlusal force-meter, that is placed between the patients' teeth. The patient is requested to bite on the bite sensor as hard as possible. Bite force is usually measured in Newton.	The time from the first appointment to the second (final) appointment will be two weeks.
chewing efficiency	Chewing efficiency will be measured with a two-coloured chewing gum. The person tested will take two chewing gums simultaneously, both with different colour. The gums must be chewed 20 times and after that the mass is pressed on a glass plate and is analysed how much the colours have mixed.	The time from the first appointment to the second (final) appointment will be two weeks.

Collaborators and Investigators

• Sponsor: University of Zurich
• Collaborators: University Hospital, Zürich
• Investigators: Study Chair: Mutlu Özcan, Prof. Dr. med. dent., University of Zurich

Study record dates

Study Major Dates

• Study Start (Estimated): November 15, 2025
• Primary Completion (Estimated): March 31, 2026
• Study Completion (Estimated): March 31, 2026

Study Registration Dates

• First Submitted: November 14, 2025
• First Submitted That Met QC Criteria: November 14, 2025
• First Posted (Actual): November 19, 2025

Study Record Updates

• Last Update Posted (Actual): November 19, 2025
• Last Update Submitted That Met QC Criteria: November 14, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: ultrasound; TMD; shear wave elastography; elastography; Elasticity Imaging Techniques; heat treatment; heat pad; massage gun; percussion massage
• Additional Relevant MeSH Terms: Body Temperature Changes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Fever; Therapeutics; Hyperthermia, Induced; Diathermy
• Other Study ID Numbers: 2025-00295

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Upon reasonable request from another research group, the raw IPD will be anonymized and shared.
• IPD Sharing Time Frame: starting 6 months after publication

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No