Purpose Although oral functions have been evaluated by various methods in maxillectomy patients, there exists substantial difficulty in the assessment procedures. The purpose of this study was to evaluate masticatory function, maximum occlusal force (MOF), and maximum tongue pressure (MTP) in maxillectomy patients objectively as per the "oral hypofunction" criteria, and examine the factors that correlate with masticatory function.

Methods This retrospective cross-sectional study included 50 maxillectomy patients with maxillofacial prostheses (23 males and 27 females, median age, 72 years; interquartile range (IQR), 63.75–77). The records of masticatory function, MOF, and MTP as per the "oral hypofunction" criteria and their profiles (age, number of occlusal supports, and maxillary defect configuration) were reviewed. The number of patients who exceeded a threshold value of "oral hypofunction" and the effects of occlusal support and defect configuration on masticatory function and MOF were calculated. Multiple regression analysis was performed to assess the associations between masticatory function and other variables.

Results The median value of masticatory function (114 mg/dL, IQR: 73–167.5) exceeded a threshold value, but not MOF (229.2 N, IQR: 110.2–419.6) and MTP (25.9 kPa, IQR: 21.4–29.0). The number of patients who exceeded each threshold value was 27 (masticatory function), 8 (MOF), and 12 (MTP), respectively. The influence of the number of occlusal supports, but not the defect configuration, was statistically significant. Multiple regression analysis revealed that MOF was independently related to masticatory function (P=0.042).

Conclusions Within the limitations of this study, the median value of masticatory function in maxillectomy patients could exceed a threshold and MOF might be an independent predictor of masticatory function.