Reliability of a novel method for measuring maximal voluntary mouth opening in patients with oral carcinoma

Background/Aims Mouth opening is a routine and vital activity of daily life that facilitates ingestion and speech. It is often found to be limited in patients with oral carcinoma. Measuring mouth opening is essential to detect the therapeutic effect of an intervention aiming to improve it. During measurement, the procedure needs to be reliable, simple, inexpensive and safe. This study aimed to determine the intrarater and interrater reliability of a novel method of measuring maximal voluntary mouth opening in patients with oral carcinoma. Methods Patients aged between 40 and 60 years of either gender with a diagnosis of oral carcinoma and presenting with difficulty in mouth opening were recruited. The distance between incisors was marked on standard sized paper slips as the participants performed maximal voluntary mouth opening. Distance between the markings was measured with a ruler in millimeters. The measurement procedures were carried out by two independent investigators. Results A total of 15 patients (12 male and 3 female) with a mean age of 52.53 ± 8.28 years participated in the study. Mean maximal voluntary mouth opening measure was <35mm, indicating restricted mouth opening in these patients. Intrarater reliability of 0.95 (0.87-0.98) and interrater reliability of 0.96 (0.89-0.98) were found for the measurements. Conclusions The reliability of maximal voluntary mouth opening measurement using this novel technique was found to be excellent. This technique can be used in the routine clinical evaluation of patients with oral carcinoma.