AIM: This study aimed to identify the factors influencing the changes in the number of teeth present, and the number of healthy or filled surfaces between two time-points.

MATERIALS AND METHODS: Repeated cross-sectional data from population-based studies, i.e., the German Oral Health Studies (DMS-III vs DMS-V), the Studies of Health in Pomerania (SHIP-START-0 vs. SHIP-TREND-0), and the Jönköping study (2003 vs. 2013), were analysed. Oaxaca decomposition models were constructed for the outcomes (number of teeth, number of healthy surfaces and number of filled surfaces).

RESULTS: The number of teeth increased between examinations [DMS: +2.26 (adults), +4.92 (seniors), SHIP: +1.67, Jönköping: +0.96]. Improvements in education and dental awareness brought a positive change in all outcomes. An increase in powered toothbrushing and interdental cleaning showed a great impact in DMS (adults: +0.25 tooth, +0.78 healthy surface, +0.38 filled surface; seniors: +1.19 teeth, 5.79 healthy surfaces, +0.48 filled surface). Interdental cleaning decreased by 4% between SHIP-START-0 and SHIP-TREND-0, which negatively affected the outcomes.

CONCLUSION: From this study, it can be concluded that education may be the most important factor having a direct and indirect effect on the outcomes. However, for better oral health, powered toothbrushing and interdental cleaning should not be neglected.