Effects of prismatic glasses including optometric correction on head and neck kinematics, perceived exertion and comfort during dental work in the oral cavity--a randomised controlled intervention.

AIM To quantify the effects of using prismatic glasses including optometric correction, on head and neck kinematics, perceived exertion and comfort, during work in the oral cavity. METHODS The study population consisted of forty-five participants. After a basic ergonomic education, baseline measurements of head and neck kinematics were made using inclinometers. Perceived exertion and comfort were rated by the participants. An intervention group (n = 25), selected at random from the participants, received prismatic glasses and optometric correction when needed and were compared with a control group (n = 20). Follow up assessments were made after the intervention. RESULTS At follow up there was a reduction in both the intervention group (8.7°) and in the control group (3.6°) regarding head flexion. Neck flexion was reduced by 8.2° in the intervention group and 3.3° in the control group. The difference between the intervention and the control groups, i.e. the effect of the intervention, was statistically significant for both head (5.1°; p = 0.009) and neck (4.9°; p = 0.045) flexion. No effect of the intervention was seen regarding perceived exertion and comfort. CONCLUSION The reduction in head and neck flexion achieved by the prismatic glasses is likely to reduce the risk of neck pain during dental work. The effect of the prismatic lenses could not be separated from the effect of the optometric correction. The possible effect of the ergonomic education was not evaluated.