摘要
目的定量测量CEREC CAD/CAM系统中生物仿造咬合面与天然牙咬合面的变化。方法通过Infinite Focus扫描系统获取20个完整的上颌第一磨牙的超硬石膏模型的三维模型。在模型的三维坐标系统中测量近中舌尖最高点(lMPC)及中央窝最低点(lCP)相对近中颊尖最高点的高度以及过近中舌尖最高点和中央窝最低点直线与水平面之最小夹角(∠MPC)。随后在石膏模型上进行近中舌尖的嵌体窝洞预备。于CEREC椅旁系统之中利用生物仿造模式(biogeneric tooth model)自动生成嵌体设计并在瓷块中切割出修复体。瓷嵌体就位于石膏模型后置于Infinite Focus中扫描并测量相同的3个指标。通过t检验检测3组指标的差值是否具有统计学意义。通过Pearson相关性分析探索各指标的变异与牙尖斜度之间的关系。结果各指标间的变异分别为ΔlMPC=(101.87±33.21)μm,ΔlCP=(-201.72±55.28)μm以及Δ∠MPC=(4.66°±0.31°)。3组指标之差值均具有统计学意义(P<0.05)。三组指标的变异中只有Δ∠MPC与牙尖斜度存在明显相关性(P<0.01)。结论生物仿造模式自动生成之修复体咬合面与原天然牙咬合面仍存在明显差异。
Objective To metrically assess the vertical changes of the occlusal landmarks for biogenerically reconstructed inlays in CEREC CAD/CAM system. Methods Stone replicas of 20 untreated maxillary first molars were scanned and measured with Infinite Focus system. Relative heights of the tip of mesiopalatal cusp （MPC） and the central pit （CP） to the tip of mesiobuccal cusp were calculated and the inclination of the line passing through MPC and CP was measured as a representation of the mesiopalatal cuspal inclination （MPCINC）. The casts were prepared for mesiopalatal inlay restoration and restored with CEREC chair-side system using biogeneric tooth model. Inlays seated on the corresponding casts were scanned again. The same items were measured and calculated. Differences between the restorations and natural teeth （△MPC, △CP and △MPCINC） were tested by paired Student’s t test （P=0.05）. Bland-Altman plots were used to assess agreements between the two occlusal surfaces. Relationships between the differences and MPCINC of natural tooth were evaluated using Pearson’s correlation coefficient. Results The vertical differences of occlusal landmarks between natural teeth and biogeneric reconstructions were （101.87±33.21） μm for MPC, （-201.72±55.28） μm for CP and （4.66°±0.31°） for MPCINC. All three differences were statistically significant （P〈0.05）. There was a significant correlation between △MPCINC and MPCINC of natural tooth （P〈0.01） while △MPC and △CP were independent from MPCINC. Conclusions Significant differences associated with three occlusal landmarks exist between the automatic occlusal reproduction by biogeneric tooth model and the natural occlusal morphology.
出处
《口腔医学》
CAS
2017年第10期885-888,共4页
Stomatology
基金
上海市科委医学引导项目(15411969400)
