支撑角度对选择性激光熔覆制作下颌双侧游离端牙列缺损可摘局部义齿支架适合性的影响

目的评价选择性激光熔覆(selective laser melting,SLM)技术制作下颌双侧游离端牙列缺损可摘局部义齿支架过程中支撑角度对支架适合性的影响。方法以下颌双侧游离端牙列缺损石膏模型为原始模型,设置对照组排除系统误差后,使用钛合金粉末,SLM制作支撑角度分别为0°(水平组)、45°(45°组)和90°(垂直组)的可摘局部义齿支架(每组6个)。将支架戴入原始模型,通过复模法获得具备支架组织面形态的石膏模型。用三维扫描仪分别扫描原始模型和复模得到的石膏模型,数据导入Geomagic Qualify软件,通过目测法以及分析支架组织面与模型的间隙评价支架的适合性。结果3组可摘局部义齿支架与石膏模型紧密贴合,无明显翘动。水平组支架与模型间的总体偏差(0.146±0.017)mm]显著小于45°组和垂直组分别为(0.182±0.015)和(0.185±0.022)mm](P<0.05),45°组与垂直组间差异无统计学意义(P>0.05)。水平组支托处偏差显著小于45°组(P<0.05),垂直组支托处偏差与水平组、45°组间差异均无统计学意义(P>0.05);水平组卡环处偏差显著小于45°组和垂直组(P<0.05),45°组与垂直组卡环处偏差差异无统计学意义(P>0.05);3组支架舌杆处偏差差异均无统计学意义(P>0.05)。结论通过3种支撑角度SLM制作的下颌双侧游离端牙列缺损可摘局部义齿支架的适合性均可满足临床要求,推荐优先选择水平向支撑角度制作义齿支架。

Effect of different support angles on the fitness of removable partial denture framework fabricated using selective laser melting technique

Objective To evaluate the fitness of bilateral free-end dentition defect removable partial denture framework fabricated by selective laser melting(SLM)technique with different support angles.Methods After the control group has been set to eliminate the system error,and according to the standard model of bilateral mandibular posterior teeth loss,eighteen titanium alloy removable partial denture frameworks fabricated by SLM technology were divided into 3 groups with support angles of 0°(horizontal group),45°(45°group)and 90°(vertical group).Plaster cast with duplicated structure of tissue surface of the removable partial denture(RPD)framework was obtained.A three-dimensional scanner was used to scan original and duplicated plaster casts.The gaps between framework and the model in different parts were analyzed using Geomagic Qualify software to evaluate the fitness of the framework with visual method.Results The framework fits on the plaster model completely,and its tissue surface fitted on the plaster model well.The deviation between frameworks and plaster casts was calculated as follow:the total deviations of the horizontal,45°,and vertical group were(0.146±0.017),(0.182±0.015)and(0.185±0.022)mm respectively.The mean deviation of the horizontal group was significantly less than those of the 45°group and the vertical group(P<0.05).Moreover,there was no significant difference in the total deviation between the 45°group and the vertical group.The total deviation of occlusal rest of the horizontal group was significantly less than that of the 45°group(P<0.05).However,no significant difference was detected in the deviation of occlusal rest among the vertical group,the horizontal group,and the 45°group(P>0.05).There was no significant difference in the deviation of occlusal rest among the vertical group,the horizontal group,and the 45°group.The deviation of clasp of the horizontal group was significantly smaller than those of the 45°group and the vertical group(P<0.05).Whereas,there was no significant difference in the deviation of clasp between the 45°group and the 90°group(P>0.05).No significant difference was found in the deviation of lingual bar among the three groups(P>0.05).Conclusions Among the three kinds of bilateral free-end dentition defect RPD framework fabricated by SLM in different support angles,horizontal printing was proved to reach the minimal deviation,even though the fitness of all three kinds of frameworks can fullfil clinical requirements according to previous studies.