Brunski J B
Department of Biomedical Engineering, Room 7040, Jonsson Engineering Center, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590, USA.
Adv Dent Res. 1999 Jun;13:99-119. doi: 10.1177/08959374990130012301.
Since dental implants must withstand relatively large forces and moments in function, a better understanding of in vivo bone response to loading would aid implant design. The following topics are essential in this problem. (1) Theoretical models and experimental data are available for understanding implant loading as an aid to case planning. (2) At least for several months after surgery, bone healing in gaps between implant and bone as well as in pre-existing damaged bone will determine interface structure and properties. The ongoing healing creates a complicated environment. (3) Recent studies reveal that an interfacial cement line exists between the implant surface and bone for titanium and hydroxyapatite (HA). Since cement lines in normal bone have been identified as weak interfaces, a cement line at a bone-biomaterial interface may also be a weak point. Indeed, data on interfacial shear and tensile "bond" strengths are consistent with this idea. (4) Excessive interfacial micromotion early after implantation interferes with local bone healing and predisposes to a fibrous tissue interface instead of osseointegration. (5) Large strains can damage bone. For implants that have healed in situ for several months before being loaded, data support the hypothesis that interfacial overload occurs if the strains are excessive in interfacial bone. While bone "adaptation" to loading is a long-standing concept in bone physiology, researchers may sometimes be too willing to accept this paradigm as an exclusive explanation of in vivo tissue responses during experiments, while overlooking confounding variables, alternative (non-mechanical) explanations, and the possibility that different types of bone (e.g., woven bone, Haversian bone, plexiform bone) may have different sensitivities to loading under healing vs. quiescent conditions.
由于牙种植体在功能上必须承受相对较大的力和力矩，因此更好地了解体内骨对加载的反应将有助于种植体设计。以下几个方面对于这个问题至关重要。（1）理论模型和实验数据可用于理解种植体加载情况，以辅助病例规划。（2）至少在手术后的几个月内，种植体与骨之间间隙以及先前受损骨中的骨愈合情况将决定界面结构和特性。持续的愈合过程会创造一个复杂的环境。（3）最近的研究表明，对于钛和羟基磷灰石（HA）种植体，在种植体表面与骨之间存在界面水泥线。由于正常骨中的水泥线已被确定为薄弱界面，骨 - 生物材料界面处的水泥线也可能是一个薄弱点。实际上，关于界面剪切和拉伸“结合”强度的数据与这一观点一致。（4）植入后早期过度的界面微动会干扰局部骨愈合，并易导致形成纤维组织界面而非骨结合。（5）大应变会损伤骨。对于在加载前已原位愈合数月的种植体，数据支持这样的假设，即如果界面骨中的应变过大，就会发生界面过载。虽然骨对加载的“适应性”是骨生理学中一个长期存在的概念，但研究人员有时可能过于愿意接受这一范式作为实验中体内组织反应的唯一解释，而忽略了混杂变量、其他（非机械）解释以及不同类型的骨（如编织骨、哈弗斯骨、丛状骨）在愈合与静止条件下对加载可能具有不同敏感性的可能性。
