A study of mineral density surrounding resorption sites in teeth

Abstract

An investigation of mineral density surrounding lacunar resorption sites in cases of both internal and external root resorption, was carried out on 37 human primary and permanent teeth. In addition, equivalent areas of the roots of 14 normal appearing teeth were studied for comparison. Thirty-two of the teeth were analyzed using microradiographic and microhardness techniques and the remainder were studied microscopically after histologic preparation. The teeth used for microradiographic analysis were embedded in plastic, bisected and half of each tooth was sectioned at 70–100 Μ. Microadiographs were taken at 9.5 kv and exposed to 30 milliamperes for 25 to 40 minutes. The other halves of the teeth were used for microhardness tests using a Tukon Microhardness Tester. One series of microhardness measurements was made 10 to 40 Μ from sites of active resorption in root dentin and a second series was made 250 to 500 Μ from these sites. The hardness measurements of the first series were found to be significantly lower than those of the second in cases of both external and internal resorption. Hardness values of the surface of normal appearing roots were also less than areas 250 to 500 Μ deeper in the dentin. Microradiographs did not reveal any definite zone of subsurface demineralization although some resorption sites were bordered by irregular areas of decreased radiodensity which may be due to superimposition of several resorption sites within the thickness of the tooth section. Histologic observations did not reveal a definite subsurface demineralization gradient. The lacunar resorption front was found to be a multilocular and completely interconnected system.