Knobloch Lisa, Larsen Peter A, Rashid Bob, Carr Alan B
Ohio State University College of Dentistry, Department of Restorative Dentistry, Prosthodontics, and Endodontics, Columbus, Ohio, USA.
Int J Oral Maxillofac Implants. 2004 May-Jun;19(3):350-6.
The purpose of this study was to compare machined-surface implants (control) and oxidized-surface titanium screw-type implants (test) loaded with fixed partial dentures at 2, 4, and 6 weeks postplacement in terms of implant survival and stability.
The beagle model was chosen for the study. Four mandibular premolars were extracted bilaterally from each dog. After 2 months of healing, 4 implants were placed in each dog. Half of the dogs (n = 6), the test group, received oxidized-surface implants; the other half (n = 6), the control group, received machined-surface implants. In each group, 2 dogs were randomly assigned to a 2-week preloading healing period, 2 to a 4-week period, and 2 to a 6-week period. Three implants were loaded in each dog; 1 was left unloaded as a control. Clinical stability and survival were monitored every 2 weeks for 6 months.
Failures were noted only among the implants assigned to the 2- and 4-week groups. Failures accounted for 9.4% (9/96) of the implants--12.5% (6/48) of the control implants and 6.3% (3/48) of the test implants. One hundred percent prosthesis stability was noted for the test-surface implant group. Stability of the test implants was significantly better than stability of the control implants (-2.6 vs -1.7, P < .05). Mean Periotest values at loading were 3.7 for the group loaded at 2 weeks, 1.6 for the group loaded at 4 weeks, and 0.6 for the group loaded at 6 weeks. Fifty percent of the 6-week group, 25% of the 4-week group, and 12.5% of the 2-week group had a Periotest value < 0 at loading.
The results reveal a qualitative difference in performance between the implant groups. Twice as many failures occurred in the control group, few failures occurred following loading, and no failures occurred after 4 weeks postplacement. The survival curves for both implants were flat after 4 weeks; however, the duration of follow-up may hide effects of time-dependent factors on survival and poses a concern for clinical inference.
Early loading of both implant types was well tolerated, as only 2 failures occurred following loading. A subsequent report will review these outcomes along with histomorphometric data collected at 6 months to better understand the significance of tissue-level implant-surface interaction for survival and stability.
本研究的目的是比较植入后2周、4周和6周时，加载固定局部义齿的机械加工表面种植体（对照组）和氧化表面钛螺丝型种植体（试验组）在种植体存活率和稳定性方面的差异。
选用比格犬模型进行研究。每只犬双侧拔除4颗下颌前磨牙。愈合2个月后，每只犬植入4颗种植体。一半的犬（n = 6），即试验组，接受氧化表面种植体；另一半（n = 6），即对照组，接受机械加工表面种植体。在每组中，2只犬被随机分配到2周的预加载愈合期，2只到4周的预加载愈合期，2只到6周的预加载愈合期。每只犬植入3颗种植体；1颗不加载作为对照。每2周监测6个月的临床稳定性和存活率。
仅在分配到2周和4周组的种植体中出现失败情况。失败的种植体占所有种植体的9.4%（9/96）——对照组种植体的12.5%（6/48）和试验组种植体的6.3%（3/48）。试验表面种植体组的义齿稳定性为100%。试验组种植体的稳定性显著优于对照组种植体（-2.6对-1.7，P < .05）。加载时，2周加载组的平均Periotest值为3.7，4周加载组为1.6，6周加载组为0.6。6周组的50%、4周组的25%和2周组的12.5%在加载时Periotest值< 0。
结果显示种植体组之间在性能上存在质的差异。对照组的失败率是试验组的两倍，加载后很少出现失败情况，植入后4周后未出现失败情况。两种种植体的存活曲线在4周后趋于平稳；然而，随访时间可能掩盖了时间依赖性因素对存活率的影响，并对临床推断构成了担忧。
两种类型的种植体早期加载耐受性良好，因为加载后仅出现2例失败情况。后续报告将结合6个月时收集的组织形态计量学数据回顾这些结果，以更好地理解组织水平的种植体-表面相互作用对存活率和稳定性的意义。
