OxyFile #248

Effect of bleaching agents on dentin permeability to Streptococcus 

Author: Heling I; Parson A; Rotstein I

Source: J Endod 1995 Nov; 21(11):540-2


Bacterial contamination of dentin may be a contributing 
factor in the development of bleaching-associated root 
resorption. In this study, the effect of commonly used 
bleaching agents on the permeability of dentin tubules 
to Streptococcus faecalis was evaluated. Sixty extracted 
bovine incisors were horizontally sectioned apically to 
the cementoenamel junction. In each tooth, a standard cavity 
was prepared, the pulp tissue extirpated, and remnants 
of soft tissue and smear layer were removed. Following 
rinsing and repeated autoclave sterilization, the teeth 
were divided into four groups, each treated with one of 
the following materials: 30% hydrogen peroxide, sodium 
perborate mixed with 30% hydrogen peroxide, sodium perborate 
mixed with distilled water, and distilled water alone that 
served as control. The bleaching agents were sealed in 
the teeth and incubated at 37 degrees C for 7, 14, and 
21 days. At each time interval the bleaching agents were 
removed and the teeth incubated at 37 degrees C in brain 
heart infusion infected with S. faecalis. Histological 
sections were prepared, and the maximal bacterial penetration 
for each group was measured using a computerized morphometric 
system. Statistical analysis of the results revealed that 
teeth treated with either 30% hydrogen peroxide alone or 
in combination with sodium perborate were significantly 
more permeable to S. faecalis than those treated with sodium 
perborate mixed with water (p < 0.0001). Sodium perborate 
mixed with water did not cause an increase in dentin permeability 
to S. faecalis and was similar to the water control. In 
conclusion, it seems that bleaching agents containing hydrogen 
peroxide in high concentrations may increase bacterial 
penetration through dentinal tubules.