# Tribological characterization of contacts in the temporomandibular joint

Nawal Ouakka, Christophe Maréchal, Philippe Moreau, Romain Vayron, Mathilde Savignat

► To cite this version:

Nawal Ouakka, Christophe Maréchal, Philippe Moreau, Romain Vayron, Mathilde Savignat. Tribo-logical characterization of contacts in the temporomandibular joint. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the.., 10.46298/mbj.16238 . hal-05191793v2

HAL Id: hal-05191793

https://hal.science/hal-05191793v2

Submitted on 23 Oct 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

# Tribological characterization of contacts in the temporomandibular joint

Nawal Ouakkaª, Christophe Marechalª, Philippe Moreauª, Romain Vayronª, Mathilde Savignatᵇ

ª Univ. Polytechnique Hauts de France, LAMIH, CNRS UMR 8201, Valenciennes

ᵇ Department of Dentistry, Centre Abel Caumartin, Chru Lille, Place de Verdun, Lille, France

* Corresponding author: christophe.marechal@uphf.fr

Received date: 04/04/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** temporomandibular joint (TMJ), articular disc, tribological analysis, condyle-disc contact, coefficient of friction

© 2025 The Authors

Licence CC-BY 4.0

Published by Société de Biomécanique

## 1. Introduction

Temporomandibular joint (TMJ) is the junction between the mandible and the skull. It is a bicondylar diarthrosis with an interposed disc, allowing for large-amplitude rotational and translational movements.

Numerical modelling is a relevant tool for studying mechanical behaviour of the TMJ under various loading conditions. It is possible to reproduce mechanical behaviour of the disc and predict the impact of variations in loading, movement speeds and contact conditions. It is essential to prevent TMJ disorders. However, such models require accurate experimental data, particularly the coefficients of friction between the condyle and the disc.

Several studies (Zimmerman et al., 2015) used low-speed, moderate-load tests that do not fully represent the joint's clinical loading conditions. Mandibular forces and speeds vary with function, yet their tribological impact is not well studied.

This study aims to analyze the tribological characteristics of the condyle-disc contact under dynamic friction conditions, with varying loading and velocity conditions.

## 2. Materials and Methods

Two condyles and discs were harvested from porcine heads, an anatomically model close to the human TMJ. After harvesting, samples were stored in a freezer to preserve their characteristics. Before testing, discs and condyles were placed in water for thawing. Discs were

immersed for one hour to ensure optimal surface lubrication. During the tests, water was regularly added to the disc surface to maintain lubrication.

Specific fixtures were designed using CATIA V5 to securely mount the disc and condyle onto the tribometer plates, and fabricated by 3D printing in polylactic acid. To ensure stability and measurement accuracy, condyle and articular disc were encapsulated in a resin cylinder prior to testing.

Condyle and disks were respectively fixed on the upper plate and lower plate of the tribometer (TriboLab Bruker). A normal force was applied while translation was performed along the perpendicular axis.

Mechanical interactions were analysed under varying load conditions (5 N, 10 N, and 30 N) and speeds (low: 2 mm/s, medium: 5 mm/s, and high: 10 mm/s). These values were selected due to their consistency with those measured in previous TMJ studies (Nickel et al., 2004; Zhu et al., 2024).

Loads of 5 N, 10 N, and 30 N were chosen to cover a range of representative forces: a minimal, a nominal and a high load, which allows simulation of physiological conditions. Movement speed was determined by considering velocities and amplitudes of natural movements observed in clinical studies.

Before each test, a static load was applied and maintained for 3 seconds to allow contact stabilization.

Nine experimental configurations were implemented for each sample (Table 1).
Each test was conducted over a 10 mm distance at a 50 Hz frequency. Normal forces $F_z$ and tangential forces $F_x$ were recorded and the coefficient of friction $\mu$ was calculated using the formula:

$$ \mu = \frac{F_x}{F_z} $$

### 3. Results and discussion

For tests at 5 N, a high speed results in an average coefficient of friction of $\mu = 0.33$, whereas a low speed increases the coefficient to $\mu = 0.35$. This trend is also observed in tests conducted at 20 N and 30 N forces. These results are consistent with tribological principles, where higher speed reduces the contact time of surface roughness, thereby decreasing friction forces (Bhushan, 2013).

For tests at 2 mm/s, increasing the normal force from 5 N to 30 N generated a lower coefficient of friction value, $\mu = 0.35$ vs. $\mu = 0.25$, indicating that increased load flattens surface roughness, thus reducing adhesion and consequently friction forces.

The determination of forces $F_x$ and $F_z$ allowed for the calculation of a friction indicator, defined as the ratio $\frac{F_x}{F_z}$. Analysis of this ratio showed that at constant sliding speed, increasing the normal force tends to reduce the ratio, indicating a relative decrease in friction with higher loads. Additionally, tests conducted at higher speeds led to a further decrease in the ratio, suggesting that relative friction diminishes as sliding speed increases, a trend consistent with fundamental tribological behavior.

It is important to note that at a normal force of 30 N, disturbances appeared in the results due to folds present on the surfaces of discs. These folds caused instability in the measurements. These data were excluded from the final analysis.

During sample harvesting, synovial fluid was not preserved, which may have influenced the results by affecting natural lubrication of the joint, potentially explaining some differences with previous studies (Tanaka, Detamore, & Peak, 2004).

Table 1 shows the effect of speed and load on the tribological properties of condyle-disc joint contacts.

<figure><img src="image_3.png" /><figcaption>Figure 1. Experimental setup to determine the coefficient of friction of the disc/condyle pair.</figcaption></figure>

<table><caption>Table 1. Average coefficients of friction according to test conditions.</caption><thead><tr><th>Loads (N)</th><th>Speeds (mm/s)</th><th>Coefficient of friction sample 1 (μ)</th><th>Coefficient of friction sample 2 (μ)</th><th>Average Coefficient of friction</th></tr></thead><tbody><tr><td rowspan="3">5</td><td>2</td><td>0,36</td><td>0,34</td><td>0,35</td></tr><tr><td>5</td><td>0,34</td><td>0,33</td><td>0,34</td></tr><tr><td>10</td><td>0,33</td><td>0,33</td><td>0,33</td></tr><tr><td rowspan="3">10</td><td>2</td><td>0,35</td><td>0,27</td><td>0,31</td></tr><tr><td>5</td><td>0,33</td><td>0,26</td><td>0,3</td></tr><tr><td>10</td><td>0,32</td><td>0,25</td><td>0,29</td></tr><tr><td rowspan="3">30</td><td>2</td><td>0,29</td><td>0,2</td><td>0,25</td></tr><tr><td>5</td><td>0,28</td><td>0,18</td><td>0,23</td></tr><tr><td>10</td><td>0,3</td><td>0,75</td><td>0,53</td></tr></tbody></table>
## 4. Conclusions

This study highlights the influence of tribological parameters on TMJ function. The higher the sliding speed, the lower the friction, while increased load also reduces adhesion between surfaces. These results enhance our understanding of TMJ response to mechanical stresses, which could be useful for improving insights into the mechanisms causing TMJ disorders, with the aim of developing appropriate treatments.

## Acknowledgments

This work is supported by the French Ministry of Higher Education and Research, the National Centre for Scientific Research (CNRS), and the Hauts-de-France region. The authors sincerely thank these institutions for their support.

## References

- Bhushan, B. (2013). *Introduction to Tribology*. John Wiley & Sons.

- Nickel, J. C., Iwasaki, L. R., Beatty, M. W., Marx, D. B. (2004). Laboratory stresses and tractional forces on the TMJ disc surface. *J Dent Res*, *83*(8), 650-654. https://doi.org/10.1177/154405910408300813

- Tanaka, E., Detamore, M. S., & Peak, C. (2004). Tribology in the temporomandibular joint: a review. *Current Opinion in Otolaryngology & Head and Neck Surgery*.

- Zhu, Y., Zheng, F., Gong, Y., Zhu, J., Yin, D., & Liu, Y. (2024). Effect of occlusal contact on TMJ loading during occlusion: An *in silico* study. *Computers in Biology and Medicine*, *178*, 108725. https://doi.org/10.1016/j.compbiomed.2024.108725

- Zimmerman, B.K., Bonnevie, E.D., Park, M., Zhou, Y., Wang, L., Burris, D. L., & Lu, X. L. (2015). Role of 3nterstitial fluid pressurization in TMJ lubrication. *Journal of Dental Research*, *94*(1), 85-92. https://doi.org/10.1177/0022034514553626