THE EFFECT OF BEAD DIAMETER ON THE ACCURACY OF 2 CURRENT TECHNIQUES USED TO QUANTIFY BONE INGROWTH IN POROUS-COATED IMPLANTS

The effect of the bead diameter on the accuracy of two techniques used in bone ingrowth quantification, microradiography and backscattered e lectron imaging-scanning electron microscopy (BEI-SEM), was assessed u sing porous-coated implants. Two groups of seven titanium porous impla nts (group A: bead size 250-350 mum and group B: 500-700 mum) were imp lanted for 12 weeks in a canine model. After euthanasia, the same hist ological slides were prepared for microradiography and BEI-SEM. The pe rcentage of bone, bone ingrowth, bone ongrowth, porosity and bone inde x were determined by a point counting method using images from both te chniques. ANOVA and Tukey's test were used to compare the results from the different bead sizes and techniques. The results showed significa nt higher bone ingrowth in microradiography groups, and significant lo wer porosity in only the fine-bead microradiography group (group A siz e). Microradiography also obtained significantly higher bone ongrowth, but only for the coarse bead size group (group B). From these results it was concluded that microradiography decreases the porosity of the porous coating compared with BEI-SEM. This effect seems to be dependen t on the bead diameter. The smaller the diameter, the greater the effe ct. Furthermore, microradiography increases bone ingrowth which seems to be affected independently of the bead diameter, becoming the most s ensitive parameter to increase.