A METHOD FOR QUANTITATIVE HISTOMORPHOMETRIC EVALUATION OF SOFT-TISSUEREACTIONS TO IMPLANTS

The spatial distribution and concentration of distinct cellular elemen ts, and the width of the reaction zone are of particular interest in t he evaluation of the compatibility of implant materials. There is a di lemma in the use of interactive histomorphometric evaluation system, A t low magnifications cell differentiation is difficult and at high mag nification (x 400) correct cell differentiation is possible but the ev aluated area adjacent to the implant border is small and therefore not necessarily representative. The solution could be the evaluation of r andom samples at precise localization under high magnification. A ligh t microscope with a software-controlled motorized stage is connected t o a personal computer. The software allows definition of one or more p olygonal areas at low magnification. A random generator determines the coordinates of the microscopic fields to be analysed and the motorize d stage moves automatically to these coordinates. The number of micros copic fields which it is necessary to evaluate in each sample is calcu lated by the statistical methods described by Stein which take the het erogeneity of the histological structures into account. A software pac kage ranks the various cells at selectable class intervals off the mat erial-tissue interface (distance histogram). Data are stored in ASCII format, which allows importation into any evaluation software. The use of statistical methods seems to be justified for quantitative biocomp atibility testing when the tissue encapsulating the implant is heterog eneous and larger than the suitable optical field of the microscope.