A histochemical assessment of teeth stained in vitro by blood : evaluation of the efficacy of various bleaching agents

Abstract

There is little information in the literature regarding the causes of discotoration of traumatized teeth or the breakdown of blood products in the pulp chamber. The most commonly quoted causes of the various types of tooth discoloration are based on empirical observations made almost fifty years ago. lt is generally considered that the main aetiological factor of tooth discoloration is pulpal haemorrhage following trauma or pulp extirpation. The aims of the study were to determine which component of blood is the primary cause of discoloration in non-infected, traumatized teeth and to determine the degree of catabolism of haemoglobin in the pulp chamber. Initially, sterile saline, platelet concentrate, whole blood and packed red blood cells were placed in the pulp chambers of each of five teeth and centrifuged twice daily for twenty-five minutes over a period of three consecutive days in order to experimentally induce staining following trauma and haemorrhage into the pulp chamber. When this confirmed that the blood pigment responsible for the staining of the teeth was found in the erythrocytes, a further group of five teeth was stained, as above, using packed red blood cells. These teeth were subjected to benzidine, zinc leuco, Perl's and Turnbull Blue histochemical tests to evaluate the degree of haemoglobin breakdown. A positive response to benzidine and zinc leuco was demonstrated whereas Perl's and Turnbull Blue gave a negative response. lt was concluded that, following haemolysis of the red blood cells, haemoglobin was found either intact or in the form of one of the haematin molecules with no further breakdown of the haem structure and no evidence of any free ferric ions or haemosiderin. ln view of the above findings, non-traditional bleaching agents and enzymes which may be involved in the removal of blood pigments within the body were evaluated, and compared to hydrogen peroxide and sodium perborate in their efficacy in removing blood stains from teeth. Results obtained to date suggest that there may be an alternative to the traditional bleaching agents and further investigation into the use of biological enzymes to remove blood stains from traumatized teeth rn vivois required.