Immunohistochemical Localization of Substance P in Pulp Tissue After In-Office Bleaching Technique in Rats

Abstract

Currently in-office bleaching procedure is the most frequently used in dentistry which represents the most traditional way to modify the color of teeth. The objective of the study is to investigate the pulp response to in-office bleaching procedure with two different concentration of bleaching products by immunohistochemical assessment for Substance P which represent main neuropeptide located in the sensory nerves of the pulp. Twenty four male albino rats were randomly divided equally into two groups. The right maxillary molars were subjected to a single in-office bleaching session with 40% of hydrogen peroxide (Opalescence Boost, UT, USA) (group A) and with 30% of hydrogen peroxide (Philips Dash, USA) (group B). The left maxillary molars in both groups received no treatment used as (negative control). the pulp response were evaluated in 1st day (n=6) and 7th day (n=6) after bleaching procedure. The upper jaws were processed for H&E stain and immunohistochemical localization of substance P. At 1st day there was high mean value of dental pulp cells that positively expressed for substance P antibody in both bleached groups and mostly in 40% bleached group (group A 30.133, group B 27.267) than control group (10.358) with significant p value (0.013) while at 7th day this expression was reduced in both groups(mean value of group A was 15.300 while the group B was 11.400). In conclusion the higher the concentration of hydrogen peroxide in bleaching products the further damage to the pulp represents in neurogenic inflammation which explain the increasing in substance P expression.