种植义齿的咬合——会有问题吗?

Occlusion on implants——Is there a problem?

义齿修复不仅可恢复牙形态和功能,并且可影响全身健康。牙齿为特殊触感及咬合运动方向感提供了结构基础,使咀嚼和吞咽活动能够有效地进行,同时可感知食物的质地和硬度。颌骨肌外周反馈调节信号主要来自牙釉质-牙本质-牙髓复合体和牙周组织中的机械感受器,来自牙周以及其他口腔部位的机械感受器的信息与来自中枢系统的信息对口腔修复的功能和适应性同等重要。种植体缺乏牙周组织和牙周机械感受器的反馈作用,因而明显降低了对精细咀嚼运动的调节能力,虽然患者依旧可以完成正常的功能活动。种植义齿与全口固定修复治疗相比,在功能恢复程度方面并没有显著差异。种植义齿的预后取决于骨支持情况,理想修复设计的咬合负荷,对种植体周围骨组织改建和骨组织张力有决定性意义。有限元分析结果证实,在种植体上部结构周围(冠状面范围)临床上常见骨吸收的部位,有明显应力集中的情况。牙尖越陡、咬合接触面越宽,应力越集中;面中央窝区域以及咬合接触面越窄的部位,应力集中越不明显。因此建议在设计咬合时应减径,将牙尖交错位作成中央窝承载形式,减小牙尖斜度,以降低功能活动及副功能活动中的侧向力。了解种植修复的这些特点对认识种植修复治疗中的咬合相关问题有重要意义。

Oral rehabilitation restores form and function and impacts on general health. Teeth provide a discriminating sense of touch and directional specificity for occlusal perception, management of food with mastication and swallowing, and awareness of its texture and hard- ness. Peripheral feedback for control of jaw muscles includes the enamel-dentine-pulp complex and mechanoreceptors in the periodontal tis- sues. The implications of feedback from periodontal and other intra-oral mechanoreceptors as well as changes in central representation are significant for function and adaptation to oral rehabilitation. With implants, in the absence of the periodontium and periodontal mechanore- ceptor feedback, fine motor control of mastication is reduced, but patients are still able to function adequately. Further, there is no signifi- cant difference in function with full-arch fixed prostheses on teeth in comparison with implants. Predictable implant outcomes depend on bone support. Optimum restoration design appears to be significant for bone remodelling and bone strains around implants with occlusal loading. Finite element analysis data confirmed load concentrations at the coronal bone around the upper section of the implant where bone loss is com- monly observed clinically. Load concentration increased with steeper cusp inchnation and broader occlusal table and decreased with central fossa loading and narrower occlusal table size. It is recommended that occlusal design should follow a narrow occlusal table, with central fossa loading in intercuspal contact and low cusp inclination to minimise lateral loading in function and parafunction. Acknowledging these features should address potential problems associated with the occlusion in implant therapy.