The Forces Behind Mandibular Advancement Devices (MAD): A Brief Explanation

by Diane Robichaud, Dental technician and member of the R&D team, Panthera Sleep Division    

Mandibular advancement devices function by moving the lower jaw (mandible) forward. Accordingly, moving any object implies that a force is applied (Newton’s Law). This law applies to any mechanical systems.

Sparse literature has investigated the forces developed by a MAD. This paper correlates the force magnitude experimentally measured by Cohen-Levy et al. (2013) using a pressure transducer applied to a MAD with the various device designs. For a mandibular advancement of around 9.5mm (the actual MAD settings measured according to the methodology developed by Bruno et al. (2020), a force of 11.18 N per splint has been considered.’ Manila Caragiuli, 2021.

Whether the MAD is pushing or pulling the lower jaw, the minimum force needed will be of the same intensity. To control this intensity, the force’s application points, orientation, and direction can be carefully selected. Controlling force intensity reduces undesired side effects such as tooth movement and muscle and TMJ pain.

Central connector systems apply strong pressure on the incisors (A) especially if there is only a single application point (D).

Bilateral connectors apply less pressure (B-C-D) then central connectors.

Bilateral connectors in the occlusal plane apply the least pressure (C).

An oblique bilateral connector with four application points (B) applies more pressure than a bilateral connector in the occlusal plane with two application points (C). Why?

The Pythagorean Theorem explains why titration systems connected by a diagonal applies more force than necessary on the masticatory system and increases the risk of undesired side effects.

If the only force being considered was gravity, at 9.81 newton (Figures 1 and 2):

The laws of mechanics provide four conclusions regarding titration system:

• Bilateral connectors with no central application point spreads the force on both sides
• Multiple application points divide the forces
• Titration systems in the occlusal plane minimizes the force required to maintain the lower jaw’s protrusion
• Central connecting systems which are located on the incisors creates maximum force on fragile teeth

According to Caragiuli et al., ‘A central connector mechanism discharges the force mainly on the anterior teeth. In contrast, a lateral connector system better distributes the force and affects molars and premolars primarily, and more uniformly’.³

Taking this into account, Panthera Dental selected the following titration system for the D-SAD Classic MAD (Figure 3).

• Bilateral with no central application point
• In the occlusal plane
• Four application points divide the force on strong teeth

This system reduces risk of short term tooth movement (B. Navailles, Ch.Valence, 2016).

This brief overview discusses a single mechanical concept. It does not discuss other parameters such as leverage effects on the TMJ, material selection and its impact on forces distribution. These and many other factors must be considered by the dental sleep specialist when selecting an appliance.

To find out more about or D-SAD Classic, visit www.pantherasleep.com.