Table 3 Negative binomial regression analysis with cumulative (dmfs+DMFS) caries experience as the outcome variable and demographic, salivary and behavioural characteristics as explanatory variables

 Males (n = 104)

−0.06 (0.13)

0.95 (0.73–1.22)

−0.06 (0.15)

0.95 (0.71–1.27)

 Females (n = 135)

Ref

Ref

Ref

Ref

Age

0.01 (0.02)

1.01 (0.98–1.05)

0.005 (0.02)

1.01 (0.96–1.05)

  ≥ 10^5 CFU/ml saliva (n = 176)

0.71 (0.15)

2.03 (1.52–2.72)

0.41(0.20)

1.51 (1.01–2.25)

  < 10^5 CFU/ml saliva (n = 63)

Ref

Ref

  ≥ 10^5 CFU/ml saliva (n = 96)

0.47 (0.13)

1.59 (1.24–2.06)

0.42 (0.16)

1.52 (1.12–2.07)

  < 10^5 CFU/ml saliva (n = 143)

Ref

Ref

 Moderate or Heavy (n = 37)

0.17 (0.18)

1.19 (0.84–1.68)

0.38 (0.21)

1.46 (0.97–2.18)

 None or light (n = 202)

Ref

Ref

pH

0.01 (0.14)

1.01 (0.77–1.32)

−0.08 (0.16)

0.92 (0.68–1.26)

Saliva flow

0.01 (0.02)

0.99 (0.95–1.04)

−0.05 (0.29)

0.96 (0.90–1.01)

Total buffering capacity

−0.06 (0.03)

0.94 (0.88–1.00)

−0.006 (0.04)

0.99 (0.92–1.07)

  ≤ once/day (n = 58)

0.34 (0.16)

1.41 (1.04–1.91)

0.39 (0.18)

1.47 (1.04–2.08)

  ≥ twice/day (n = 181)

Ref

Ref

Ref

Ref

 No (n = 54)

−0.62 (0.17)

0.54 (0.39–0.74)

− 0.24 (0.21)

0.79 (0.52–1.20)

 Yes (n = 185)

Ref

Ref

Ref

Ref