Journal of implantology and applied sciences ISSN:2765-7833(Print) 2765-7841(Online) 대한구강악안면임플란트학회지

The purpose of this study was to compare hard tissue reactions of two kinds of implant surfaces by surface roughness analysis, implant stability analysis, removal torque measurements, histologic and histomorphometric analysis. Screw-shaped titanium implants with two different surfaces used ; whole smooth machined surface(Branemark^®, Nobel Biocare, Sweden) and hybrid type which had smooth surfaces at upper 3㎜ area and acid-etched rough surface below machined surfaces(Osseotite^®, 3i, USA). Commercially pure titanium implants, with the length of 8.5㎜, the diameter of 3.75㎜ and a pitch height of 0.6㎜ were used in both systems. Twenty machined and hybrid screw implants implanted in the tibae and femurs of 10 New Zealand rabbits. The purpose of this study was to compare hard tissue reactions of two kinds of implant surfaces by surface roughness analysis, implant stability analysis, removal torque measurements, histologic and histomorphometric analysis. Screw-shaped titanium implants with two different surfaces used ; whole smooth machined surface(Branemark^®, Nobel Biocare, Sweden) and hybrid type which had smooth surfaces at upper 3㎜ area and acid-etched rough surface below machined surfaces(Osseotite^®, 3i, USA). Commercially pure titanium implants, with the length of 8.5㎜, the diameter of 3.75㎜ and a pitch height of 0.6㎜ were used in both systems. Twenty machined and hybrid screw implants implanted in the tibae and femurs of 10 New Zealand rabbits. The results were as follows : 1. Surface roughness analysis The rough part of hybrid implant(Sa:1.59㎛) was twice as rough as that of machined implant(Sa:0.73㎛). 2. Implant stability analysis (1) In the stability test at implantation and sacrifice, the resonance frequency value(RFV) at sacrifice was significantly higher than RFV at implantation irrespective of the place and the kinds of implant(p<0.05). (2) In the case of stability test, the RFV of hybrid implant in tibia at implantation was significantly higher than that of machined implant (p<0.05), but no significant difference was found in the other case. (3) In the stability test according to measuring direction, though the value of the resonance frequency was V1(8569.6㎐), H1(8470.3㎐), V2(8434.7㎐), H2(8423.6㎐) in a sequence, no significant difference was shown among all the groups. 3. Removal torque analysis The removal torque measured in the tibia after sacrifice was significantly higher in hybrid implant than that of the machined implant(p<0.05). 4. Histologic analysis Most of the cortical bone layers contacted with the smooth machined threads of tybrid and machined implants. The rough part of hybrid implant was surrounded by the cancellous bone active bone remodeling was observed around that area. 5. Histomorphometric analysis (1) In the bone to metal contact, the observation of all threads around the implant fixture and the best three consecutive screws showed no statistically significant differences between the machined and hybrid implants. (2) The bone area had no statistical difference in all threads around the implant fixture, but in the best three consecutive threads the machined implant was of significant higher value than that of hybrid implant(p<0.05). Therefore, when the surface roughness of the implant was increased, the mechanical stability was enhanced, but the contact degree between the implant and bone decreased. In the future, however, it is though that it is necessary to research more thoroughly the implant surface in order to achieve the proper roughness and the reactions of the implant-tissue interface when the functional forces are applied to the implant.