Masticatory function of conventional complete denture wearers changing to 2-implant retained mandibular overdentures: clinical factor influences after 1year of function.

Purpose: Evaluate how clinical factors related to conventional complete denture (CCD) wearers, can influence masticatory function (MF) of totally edentulous patients before and after one-year transitioning to implant-retained mandibular overdentures (IMO).

Methods: Forty patients using CCD were rehabilitated with IMO and their MF was evaluated by: (i) ST_X50: theoretical aperture through which 50% of the weight of the particles would pass; (ii) STB: distribution homogeneity of the crushed particles. The clinical parameters analyzed were: atrophy, retention, stability, facial type, anteroposterior skeletal discrepancy, and type of loading. The statistical association was tested through crude and adjusted logistic regression.

Results: IMO promoted improvements in the MF, irrespective of the clinical parameters. CCD wearers with poor retention had 86% less chance of achieving a good ST_X50. STB was associated with stability, facial type, and anteroposterior discrepancy. Subjects with poor mandibular CCD stability had a 76% lower chance of achieving a good test food homogenization, whereas brachyfacial individuals were 1.3 times more likely to have a good STB. Class II patients had an 89% lower chance of having a good homogenization of the particles as CCD users and after transition to IMO.

Conclusions: CCD users with poor retention achieved an inferior ST_X50. The STB performance can be compromised by poor stability or Class II characteristics, while brachyfacial individuals achieve better homogenezation of the food bolus. Although the transition to IMO improved the masticatory function, the anteroposterior discrepancy still maintained an association with STB, as Class II individuals still presented difficulties homogenizing food.