How the Luco Hybrid Device Treats Sleep-Related Bruxism

The Luco Hybrid OSA Appliance is the only FDA cleared treatment of sleep related bruxism (K160477). To date, it is the only FDA cleared treatment of this common and serious condition.

The design of the Luco Hybrid was refined over 7 years to incorporate a number of features that not only protect the teeth from the forces of sleep related bruxism, but also address the activation of the trigeminal cardiac reflex.

The Patented Forward Bite:

There patented forward bite of the Luco Hybrid precisely places the bite over the upper 1st and second bicuspids. There are a number of reasons for this innovation that make the Luco Hybrid unique in mandibular advancement appliances. This is, by far, the most significant feature of the Luco Hybrid device.

Figure 1: the Forward Bite of the Luco Hybrid OSA Appliance The Luco Hybrid uses two pads on the upper appliance that only allow it to contact in the region of the 1st bicuspids and cuspids of the upper teeth. There is no contact in the molar region.

 

1. Stress Distribution:

When we bite together, this places stress and strain on the skull. There are three types of stress: compression, torsion and shear (figure 2).

Figure 2: Types of Stress: Compression stress occurs in sleep-related bruxism during tonic or clenching type events while shear stress occurs when the teeth are ground side to side during phasic events. 

When chewing hard foods, compression stress occurs on the teeth and jaws. When chewing side-to-side, there is shear stress on the cusps or points of the teeth and when eating something sticky or chewy, there is tension stress. In sleep-related bruxism, compression and shear strength (figure 2) are the most significant. With compression (clenching of the teeth), filings and ceramic crowns may crack under the pressure or vertical cracks in the teeth can occur.  With shear(grinding of the teeth), the cusps of the teeth can fracture, the teeth can loosen or the PDL can be damaged resulting in pain. Shear(clenching) is much more common than compression (clenching) during sleep-related bruxism at all levels of severity.

Stress Distribution on the Skull When Biting in the Molar Region:

When biting or contacting in the molar region, there are a number of regions that are placed under excessive stress\force. The following is a stereolythic model of forces when biting in the molar region. Dark blue indicates low stress, green moderate, and red severe.

Figure 3: Stress Distribution with a Molar Bite: There are a number of high stress areas including the body, the ramus and the condyle of the mandible as well as the TMJ, under the eyes and down the nasal septum. 

When biting in the molar region, there are high concentrations of force (red in animation)  in the regions of:

  • the body of the mandible
  • the angle of the mandible
  • the coronoid process of the mandible
  • the TMJ
  • under the eyes
  • down the nasal septum

As can be seen in Figure 3, there are very unfavorable stresses associated with a molar bite. Unfortunately, all other mandibular advancement appliances are designed with this type of bite. The FDA, on their guidance for OSA appliances actually list Temporomandibular Joint (TMJ) Dysfunction Syndrome as a an identified risk for OSA appliances, in section 5. This is most likely due to the molar bite on all other mandibular advancement appliances.

Stress Distribution on the Skull when Biting in the Cuspid Region:

When biting in the cuspid region, the bite force is much more favorable.

Figure 4: The Cuspid Bite: When biting in the cuspid region, the only high stress area is the tip of the cuspid, the strongest tooth in the mouth. The rest of the force is evenly distributed through the facial bones. The forward bite of the Luco Hybrid distributes the bite force in this way.

As can be seen in figure 4 above, when biting in the cuspid region, there is an even distribution of the bite force through the facial bones. The forward bite of the Luco Hybrid places the bite precisely in this place. The only high stress area (marked in red) is the tip of the cuspid (eyetooth), which is one of the strongest teeth we have.

This is why the Luco Hybrid device does not cause Temporomandibular Joint (TMJ) Dysfunction Syndrome and was originally designed to treat this condition. All other mandibular advancement appliances run the risk of TMJ and muscle pain after a few weeks to a month of use. This is why the FDA list it as an identified risk.

 

2. Activation of the Periodontal Masseter Reflex

There is another cranial reflex that is utilized by this device called the periodontal masseter reflex. It is not affected by the HTR2a polymorphism and functions normally in patients suffering from sleep-related bruxism.

Figure 5: The Periodontal Masseter Reflex:  When the periodontal lament receptors are activated by excessive compression forces, this reflex is activated. Suppression of masseter contraction and activation of the digastric muscle to open the mouth occurs

The periodontal-masseter reflex is similar to the masseter inhibitory reflex except it does not involve the same pathways. When the periodontal or ligaments surrounding the roots of the 1st bicuspids and cuspids are stimulated, this reflex is activated. To a lesser extent, pressure on the incisors can elicit this response however it is stronger in the cuspid region. It is unique in that it affects both closing and opening muscles (figure 5) in the reflex loop.

The Luco Hybrid device treats the muscle hyperactivity and limits the bite force by activating this reflex through the forward bite.

3. Prevention of Activation of the Trigeminal Cardiac Reflex

An endodontic study demonstrated that root canal therapy on the 1st bicuspids or cuspids resulting in a rapid drop in heart rate and blood pressure, suggesting a novel form of the TCR.

The Luco Hybrid, with its forward bite, stimulates the conventional parasympathetic stimulation of the TCR that negates the Gasserion ganglion sympathetic stimulation of the TCR known to occur  (One is sympathetic, the other parasympathetic. Each has the opposite effect on the cardiovascular system and activation of both simultaneously simply cancels both out).

Figure 6: Sleep study of sleep related bruxism demonstrating the SRB events, the hyperpnea and tachycardia associated with activation of the TCR.

It should be noted that it is medically accepted that there must be a change in heart rate of greater than 20% from the mean heart rate before a diagnosis of TCR activation may be made. In the above animation, the heart rate increases from 65 bpm to 94 bpm during the SRB events, a 44% increase. SRB is a significant simulator of the TCR and often increases heart rate by 90 to 100%.

In figure 7, the tracing is from the same patient as in Figure 6 while wearing a Luco Hybrid Device. Note the dramatic improvement in muscle activity, respiration and heart rate.

For more detailed  information on the trigeminal cardiac reflex, click here.

The Luco Hybrid’s Effect:

Figure 7: Sleep tracing of the same patient wearing the Luco Hybrid device. Note the stabilization of the muscles, respiration, and heart rate.

The tracing in Figure 7 is the same patient as in figure 6, while wearing the Luco Hybrid device. The positive effects of PMR activation are clearly demonstrated. This is typical for patients suffering from sleep-related bruxism. When wearing the Luco Hybrid device, respiration normalizes, heart rate returns to normal, blood pressure stabilizes and the sleep bruxism is well controlled.

Please note that sleep-related bruxism is no considered a risk factor for the development of heart disease.

In Summary…

In the development of the Luco Hybrid, it was found to be essential to incorporate the forward bite into the design for the reasons given above. This patented feature and its profound effects are unique to the Luco Hybrid. No other device, including OSA, mandibular advancement, conventional upper or lower night guards can make this claim or demonstrates the above effects.