Does Mandibular Bone Resorption Affect Masticatory Function for Complete Denture Wearers?

Objectives: This transversal clinical study measures the degree and severity of mandibular bone atrophy in edentulous patients and analyzes how bone resorption affects the masticatory function.
Methods: Thirty patients wearing complete dentures for at least 3 months were divided in two groups with different degrees of bone atrophy. The subdivision was based on radiographic measurements taking into account the bone height (Cawood & Howell, 1988) and the severity of bone resorption (Wicall & Swoope, 1974). Subsequently, several (semi)-quantitative and qualitative parameters related to the masticatory function were evaluated, namely the retention and stability of the mandibular complete denture, the masticatory performance (MP, indexes: X_50 and PM_B) and the masticatory efficiency (ME, sieves 4 and 2.8). In addition, the and the Geriatric Oral Health Assessment Index (GOHAI) and Dental Impact on Daily Living (DIDL) questionnaires were completed by the target group.

Results: Atrophic edentulous patients showed prolonged mandibular edentulism compared to the non-atrophic ones in both groups (P<0.05). Furthermore, atrophic patients presented lower bone height in the superior mentual foramen, pre-molar and molar regions (P<0.05). Positive associations between bone atrophy and poor retention (clinical score 3) were found irrespective of bone height (P=0.005) or bone resorption severity (P=0.007). The mandibular length was the only radiographic parameter correlated with MP X_50 (r=0.420) and ME 2.8 (r=-0.359). The results from the GOHAI questionnaire reveal a correlation between MP X_50 and the psychosocial domain (r=-0.305, p=0.049), while ME 2.8 correlates positively with the physical domain (r=0.412, p=0.05). The DIDL questionnaire showed that from ME 4, there is a positive correlation with eating and chewing domain (r=0.362, p=0.048). Moreover, there is a negative correlation between the perceived oral comfort (r= -0.405, p=0.026) and general performance domains(r= -0.405, p=0.026).
Conclusions: The analyzed bone atrophy criteria indicate that neither the bone height nor the severity of mandibular ridge directly affected the masticatory function, while being inversely correlated with the perceived masticatory ability.