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Table 1 Mean levels and standard errors (se) of TVC at 22° and 36°C (CFU/mL) from water samples, prevalence of samples with microbial levels above the threshold levels established by Italian law (21) (no samples exceeded the CDC 2003 threshold value).

From: Italian multicenter study on infection hazards during dental practice: Control of environmental microbial contamination in public dental surgeries

  Cup fillers
  22°C 36°C
  T0 T1 Statist. anal. T0 T1 Statist. anal.
Logarithmic mean 1.6 (se = 0.15) 1.3 (se = 0.14) t = 1.38 (p = 0.16) 1.7 (se = 0.15) 1.2 (se = 0.13) t = 2.24 (p = 0.02)
Geometric mean 42.7 21.9   47.9 17.4  
% positives (Italian law) 41.2 (42/102) 36.2 (37/102) McN = 1.71 (p = 0.19) 60.8 (62/102) 47.0 (48/102) McN = 10.32 (p = 0.001)
  Air-water syringes
  22°C 36°C
  T0 T1 Statist. anal. T0 T1 Statist. anal.
Logarithmic mean 1.8 (se = 0.15) 1.4 (se = 0.14) t = 2.11 (p = 0.03) 1.7 (se = 0.13) 1.2 (se = 0.13) t = 2.55 (p = 0.01)
Geometric mean 64.6 23.4   49.0 16.6  
% positives (Italian law) 48.9 (47/96) 31.6 (30/95) McN = 13.14 (p = 0.0003) 63.5 (61/96) 46.3 (44/95)) McN = 13.14 (p = 0.0002)
  Tap water     
  22°C 36°C     
  T0 T0     
Logarithmic mean 0.5 (se = 0.07) 0.7 (se = 0.10)     
Geometric mean 3.0 5.4     
% positives (Italian law) 4.4 (4/91) 29.3 (27/91)     
  1. Statistical analysis of differences between T0 and T1 (t-test for paired samples for means and McNemar test for proportions)