J Korean Acad Oral Health.  2015 Jun;39(2):88-94. 10.11149/jkaoh.2015.39.2.88.

Logistic regression analysis of factors affecting the survival of first molars in Korean adults

  • 1Department of Statistics Institute of Applied Statistics, College of Natural Science, Chonbuk National University, Jeonju, Korea.
  • 2Department of Preventive and Community Dentistry, Institute of Oral-bio Science, School of Dentistry, Chonbuk National University, Jeonju, Korea. prevdent@chonbuk.ac.kr
  • 3Department of Dental Hygiene, Daegu Health College, Daegu, Korea.


This study aimed to analyze the variables affecting the survival of the four permanent first molars in an adult Korean population using logistic regression analysis.
The Korean government has been collecting oral health data at the national level at 3-year intervals since 2000. In addition, a national survey was conducted in 2006 among 15,777 persons aged 2-95 years who were stratified by age, gender, and region. The relationship between each of nine objective variables and tooth survival was analyzed by frequency, cross-tabulation, and logistic regression analysis, with age, gender, and economic status as functional variables. The inclusion level was alpha=0.05 and the exclusion level was alpha=0.10. The nine variables were age, occupational status, monthly family income, gender, frequency of brushing the teeth, snack intake per day, presence of diabetes, education level, and smoking (packs per year).
The survival rate of the molars decreased with increased age. In individuals who engaged in farming, stock breeding, and fishing, the rate was 2-5 times lower than that of individuals in higher positions in terms of jobs and society. Furthermore, the survival rate for smokers was 5-10 percent lower, compared with non-smokers.
The most significant predictor of the survival rate of the four permanent molars in Korean adults was age, followed by jobs, smoking, and gender.


first molar; Korean; logistic regression; tooth survival rate
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