Sir, we wish to highlight a trend noticed in patients after improved facial aesthetics. Jawzrsize is advertised as a 'face and neck toning' device but in our opinion it could potentially cause negative effects for patients looking for a more square, prominent jaw. The device is effectively a rubber ball with or without upper and lower occlusal rests for the incisal teeth; these can be 'custom fit' akin to 'boil and bite' mouth guards. The consumer then bites up and down on the device for numerous repetitions and sets as they see fit throughout the day. The resistance of the devices ranges from 20 to 40 lbs (89 to 178 N). The average range of force exerted when eating carrots or meat is 70 to 150 N.1

The website for the device has numerous claims without any medical backing including improved collagen stimulation, improved jaw function and relief of TMJD symptoms. It seems likely that the repeated use of this device will result in far more stresses on the TMJ and cause significant wear on the articular disc potentially triggering various TMJD symptoms from crepitus to complete dislocation. The effort exerted by use of this device could be compared to those of bruxists and could lead patients down the path of requiring neuromodulators to reduce the muscle activity of the masseter.

Healthy jaw rehabilitation emphasises gentle conditioning not inducing extreme stresses. Following a routine of simple resistance exercises with your own hands is regarded as a useful tool in conservative management of TMJD.2