Objectives: To evaluate the frequency of apolipoprotein (APOE) alleles and determine whether APOE type 4 allele (epsilon 4) was associated with edentulousness even when certain factors were controlled.
Background: The APOE are important in lipid homeostasis, and APOE epsilon 4 has been found in many diseases and to have a negative impact on longevity. Tooth loss is more common in ill aged subjects with low income and education.
Materials and methods: In a population-based study involving 1860 subjects between 35 and 85 years 1321 dentate (mean age = 54; 54% women, 46% men) and 539 edentulous (mean age = 72; 62% women, 38% men) subjects were studied. Logistic regression was performed with dentate/edentulous as dependent variables and years of education, socio-economic status, social network, stress level, handicap from birth, 23 various diseases and APOE epsilon 4 as covariates. Thereafter, APOE epsilon 4 frequencies were studied in 342 dentate and 336 edentulous subjects 50-85 years of age. The subjects were matched with regard to age, gender, years of education, living condition, stress level, handicap from birth and 23 various diseases.
Results: APOE allele frequency in the total group was epsilon 2 = 7.8%, epsilon 3 = 76.4% and epsilon 4 = 15.8%. Age, living condition, years of education and APOE epsilon 4 were significant covariates in edentulous subjects (p <or= 0.001). APOE epsilon 4 in the matched groups revealed significant differences between the dentate group and the edentulous group (chi2 = 5.68; p = 0.017). There was no group effect (F(29,648) = 0.849; p < 0.696; Wilks' lambda = 0.963). In the dentate group, the frequencies of APOE were: epsilon 2 = 8.8%, epsilon 3 = 77.9% and epsilon 4 = 13.3%. Corresponding frequencies of APOE in the edentulous group were: epsilon 2 = 6.6%, epsilon 3 = 75.4% and epsilon 4 = 18.0%.
Conclusion: Despite matching both groups with regard to different background factors, the edentulous group had a higher frequency of APOE epsilon 4 than the dentate group. Thus, genetic factors might contribute to greater risk in developing complex oral diseases leading to tooth loss or just be an indication that the subjects in our study carrying APOE epsilon 4 are more fragile.