Table 1. The result of Cox proportional hazards single regression analysis for identifying the risk of primary and secondary caries in adult patients.

Variables	Primary caries		Secondary caries
	Hazard ratio (95% CI)	p-value	Hazard ratio (95% CI)	p-value
Age	0.99 (0.97–1.01)	0.2902	1.01 (1.00–1.03)	0.1397
DMFT	1.02 (0.98–1.06)	0.3203	1.09 (1.05–1.03)	<0.0001*
Saliva flow	0.98 (0.92–1.04)	0.5762	0.98 (0.92–1.03)	0.4261
Buffer capacity	0.84 (0.56–1.53)	0.3584	1.07 (0.78–1.44)	0.6565
SM level#	2.31 (1.41–3.99)	0.0010*	2.62 (1.70–3.98)	<0.0001*
LB level##	2.03 (1.23–3.26)	0.0027*	3.91 (2.17–7.78)	<0.0001*
Poor compliance	2.36 (1.46–3.77)	0.0006*	1.44 (0.90–2.25)	0.1229

^*Statistically significant at a level of p < 0.05.

^#Level of mutans streptococci. The thresholds were 1 × 10⁶ CFU/ml for primary and secondary caries.

^##Level of Lactobacilli. The thresholds were 1 × 10⁵ CFU/ml and 1 × 10⁵ CFU/ml for primary and secondary caries, respectively.