Figure 3. Survival CART for the incidence of primary and secondary caries within three years.

For primary caries (a) three nodes were identified according to compliance with the preventive program and the SM level. Patients with good compliance were categorized as low-risk (Node 1) with a hazard ratio of 0.42; while patients with poor compliance and an SM level of ≥1 × 10⁶ CFU/ml were categorized as high-risk (Node 3) with a hazard ratio of 3.66. For secondary caries (b) three nodes were also identified according to the LB level and DMFT. Patients with an LB level of < 1 × 10⁵ CFU/ml were categorized as low-risk (Node 1) with a hazard ratio of 0.35. Patients with an LB level of ≥1 × 10⁵ CFU/ml and DMFT >15 were categorized as high-risk (Node 3) with a hazard ratio of 3.50. *Statistically significant at a level of p < 0.05.