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Table 2 Proportion benefiting from the intervention and number needed to treat in the two included studies

From: Non-surgical treatment of dentin caries in preschool children – systematic review

Study Intervention (test group) Caries arrest rate in test group Caries arrest rate in control group Proportion benefiting from intervention Number needed to treat
   P (A) P (B) P(C) = P(A) - P(B) NNT = 1/P(C)
Chu et al. 2002 [13] 38% SDF + excavation 0.65 0.34 0.31 3.2
  38% SDF 0.65 0.34 0.31 3.2
  5% NaF + excavation 0.38 0.34 0.04 25
  5% NaF 0.44 0.34 0.10 10
Lo et al. 1998 [9] Brushing with fluoridated toothpaste 0.28 0.12 0.16 6.3