Hydrodynamic flow through loading and in vitro secondary caries development

This in vitro study investigated the effect of hydrodynamic flow through mechanical loading on development of secondary caries lesions. forty-eight bovine tooth specimens (enamel and dentin; sizes 3.2 x 3.2 x 2.0 mm) were restored with resin-composite on polystyrene bars; 18 samples were bonded,and 30 were not bonded. specimens were suspended in a lactic acid solution (ph = 5; 14 days) in a modified brushing machine,and artificial caries lesions were formed. during caries development,specimens were mechanically loaded at the surface of the polystyrene bar,bent so that the tooth- composite interfaces were subjected to opening forces (16x/min). loads applied were either none (control bonded,cb,n = 6; and control non-bonded,cnb,n = 6),200 gr (nb200,n = 12),or 350 gr (nb350 and b350,both n = 12). before and after caries development,specimens were imaged with transverse wavelength-independent microradiography (t-wim),and lesion depth (ld) and mineral loss (ml) were calculated at 4 different locations. an independent t test was used to compare the ld and ml at the 4 different locations. a statistically significant effect of the level of loading (comparing groups nb200 and nb350) and of bonding (comparing groups nb350 and b350) could be observed,with a higher load and absence of bonding leading to more advanced lesions. © 2013 international & american associations for dental research.