Flanagan Dennis
Private Practice, Willimantic, CT, USA.
Clin Cosmet Investig Dent. 2017 Nov 3;9:93-97. doi: 10.2147/CCIDE.S146544. eCollection 2017.
Implant-supported dental prostheses can be retained by a screw or cement. Implant-supported fixed partial dentures have a passive fit. A passive fit means there is an internal gap between the abutment surface and the intaglio of the retainer to insure that there is no lateral pressure on the supporting implants or friction upon seating of the prosthesis. This gap is filled with cement for retention of the prosthesis. Any lateral pressure may cause marginal bone loss or periimplantitis. Also, there is usually a microscopic gap at the margin of a crown retainer that exposes the cement to oral fluids. The solubility of zinc phosphate (ZOP) cement is a definite liability due to the risk for cement dissolution. In fixed prostheses, the dissolution of the cement of one or more retainers would cause a transfer of the occlusal load to the retained unit(s). The resulting rotation and lifting of the cement-retained implants from occlusal and parafunctional loads could cause loss of osseointegration of the abutment-retained implant(s). ZOP cement may not be indicated for implant-supported fixed partial dentures or splints. Cement dissolution in single unit probably only involves re-cementation, if the patient does not swallow or aspirate the crown.
种植体支持的牙修复体可以通过螺丝或粘结剂固位。种植体支持的固定局部义齿具有被动适合性。被动适合性是指基牙表面与固位体组织面之间存在内部间隙，以确保对支持种植体没有侧向压力或在修复体就位时没有摩擦力。这个间隙用粘结剂填充以固定修复体。任何侧向压力都可能导致边缘骨丧失或种植体周围炎。此外，在冠固位体边缘通常存在微观间隙，使粘结剂暴露于口腔液体中。由于粘结剂溶解的风险，磷酸锌（ZOP）粘结剂的溶解性是一个明显的问题。在固定修复体中，一个或多个固位体的粘结剂溶解会导致咬合负荷转移到被固定的部件上。由此产生的由于咬合和非功能负荷导致的粘结固位种植体的旋转和抬起可能会导致基牙固位种植体的骨结合丧失。ZOP粘结剂可能不适用于种植体支持的固定局部义齿或夹板。如果患者没有吞咽或误吸牙冠，单个部件中的粘结剂溶解可能仅涉及重新粘结。
