Bone tissue response to experimental zirconia implants.

Abstract

This study seeks to assess the bone tissue response at experimental zirconia implants in comparison with titanium implants by means of descriptive histology and histomorphometry in a dog model. Experimental zirconia implants with three different surface roughnesses (Z1<Z2<Z3) and conventional sandblasted large grit and acid-etched titanium implants were inserted bilaterally in the lower jaws of nine beagle dogs. Tissue biopsies were obtained after 3 and 14days and 10weeks of transmucosal healing. The tissue response was investigated by assessing new, old, and total bone-to-implant contact (nBIC, oBIC, and tBIC). After 3days, histological specimens of all groups showed an intimate contact between the implant threads and pristine bone (tBIC: Ti 42.3%>Z2 30.1%>Z3 28.9%>Z1 25.1%, p>0.05, unpaired t test, respectively). A provisional matrix was evident at all implant surfaces. At 14days, percentages of BIC increased in all groups (tBIC: Ti 62.1%>Z3 69.2%<Z2 44.4%>Z1 42.3%; nBIC: Z3 58.9%>Ti 52.2%>Z2 35.1%>Z1 32.5%). Two implants, one of group Z1 and one of group Z2, were lost. At 10weeks, 13 of 18 zirconia implants were lost, equally distributed between all three surface modifications. The remaining implants revealed increased BIC values (tBIC: Z3 69.5%>Ti 58.5%>Z1 49.7%>Z2 37.1%; nBIC: Z3 57.2%>Ti 46.5%>Z1 32.3%>Z2 29.3%). Histomorphometrical analysis showed comparable mean BIC values in all groups at all healing periods without showing statistical differences (p>0.05, unpaired t test, respectively). The bone tissue response throughout the healing periods was characterized by a constant bone remodeling accompanied by resorption of old bone in favor of new bone formation at both titanium and zirconia implants. Surface roughness had a positive effect on BIC, although not showing statistical significance. Due to the poor survival rate, the experimental zirconia implants investigated may not be suitable for clinical use. Zirconia has been introduced as an alternative biomaterial for dental implants. A profound knowledge about the bone tissue response at zirconia implant surfaces is necessary as it plays an important role for proper osseointegration and long-term stability.