Medial mandibular flexure and maximum occlusal force in dentate adults

Medial mandibular flexure (MMF) is the functional narrowing of the mandible during opening and protrusion movements, which may affect conventional or implant-supported prostheses. This study evaluated the association among MMF, maximum occlusal force (MOF), gender, weight, height, body mass index (BMI), and age in 80 dentate adult subjects (40 women, 40 men; age range 20 to 38 years).

Bilateral MOF was measured using a cross-arch force transducer placed in the first molar region. For MMF calculation, impressions of the mandibular occlusal surface were made with vinyl polysiloxane putty material in rest (R), maximum opening (O), and maximum protrusion (P). The impressions were scanned, and the images were processed using Adobe Photoshop software. Reference points were selected on the occlusal surface of the contralateral first molars, and the linear intermolar distance was measured using Image Tool software. MMF was calculated by subtracting the intermolar distance during opening or protrusion from the intermolar distance during rest.

Mean values of MOF were 698.14 N for women and 1,009.48 N for men; MMF-O was 0.146 mm and MMF-Pwas 0.15 mm for the total sample. No correlation was found between MOF and MMF (r = 0.02 for MMF-O; r = 0.11 for MMF-P; P > .05) or between MMF and weight, height, BMI, or age. MOF was significantly associated (P <.001) with weight (r = 0.509), height (r = 0.459), and BMI (r = 0.423), but not with age (r = 0.009).

These results suggest that MMF is not associated with MOF in this sample of dentate adults.