目的探讨线性(牙合)用于2枚种植体支持的即刻负荷下颌种植覆盖全口义齿的临床可行性、技术特点并评估其临床效果。方法在6例下颌牙槽骨严重吸收的无牙颌患者的颏孔前区植入2枚种植体,术后即刻印模转移,24 h 内完成杆卡式附着体固位的覆盖线性(牙合)全口义齿修复。于术后1周,负荷后1、3、6、12个月复诊,之后每6个月复诊1次,检查种植体的稳定性、种植体周牙龈组织的健康状况,拍摄曲面断层 X 线片观察种植体周骨高度变化,检查修复体戴用情况,评估患者满意度。结果 6例患者共植入12枚种植体,追踪观察9～30个月,种植体均无松动或脱落。种植体周牙龈出血指数为0～1、龈沟深度均小于2 mm,牙龈组织健康。曲面断层 X 线片显示,即刻负荷后第1年种植体周骨吸收量均在1 mm 以内,未见明显骨吸收。患者对修复效果满意。结论在下颌牙槽骨严重吸收的无牙颌患者的颏孔前区植入2枚种植体,即刻采用杆卡式附着体固位的种植覆盖线性(牙合)全口义齿修复是可行的,近期临床效果满意,长期效果需进一步观察。
Background The rocking and instability of a loaded complete denture （CD） during lateral excursion reduce the bearing area under the denture base, causing localized high stress concentrations. This can lead to mucosal tenderness, ulceration, and alveolar bone resorption, and the linear occlusion design was to decrease the lateral force exerted on the denture and to ensure denture stability. But it is not known how the bearing areas of linear occlusal CDs （LOCDs） and anatomic occlusal CDs （AOCDs） differ. The purpose of this study was to analyze and compare the distributions of the high and low vertical stress-bearing areas in the mandibular alveolar mucosa under LOCDs and AOCDs at lateral excursion.Methods Computerized tomography （CT） and finite element analysis were used to establish three-dimensional models of an edentulous maxilla and mandible with severe residual ridge resorption. These models were composed of maxillary and mandibular bone structure, mucosa, and the LOCD or AOCD. Lateral excursion movements of the mandible were simulated and the vertical stress-bearing areas in the mucosa under both mandibular CDs were analyzed using ANSYS 7.0.Results On the working side, the high stress-bearing （-0.07 to -0.1 Mpa） area under the LOCD during lateral excursion was smaller than that under the AOCD, while the medium stress-bearing （-0.03 to -0.07 Mpa） area under the LOCD was 1.33-fold that under the AOCD. The medium stress-bearing area on the non-working side under the LOCD was 2.4-fold that under the AOCD. Therefore, the overall medium vertical stress-bearing area under the LOCD was 20% larger than that under the AOCD.Conclusions During lateral excursion, the medium vertical stress-bearing area under a mandibular LOCD was larger and the high vertical stress-bearing area was smaller than that under an AOCD. Thus, the vertical stress under the LOCD was distributed more evenly and over a wider area than that under the AOCD, thereby improving denture stability.
