Abrol Surbhi, Nagpal Archana, Kaur Rupandeep, Verma Ramit, Katna Vishal, Gupt Parikshit
Private Practitioner, Dharamshala, Himachal Pradesh, India.
Head, Department of Prosthodontics, Himachal Dental College, Sundernagar, Himachal Pradesh, India.
J Clin Diagn Res. 2017 Aug;11(8):ZC102-ZC105. doi: 10.7860/JCDR/2017/28372.10501. Epub 2017 Aug 1.
Minor rotation of impression coping secured in the impression is an avoidable error that needs to be minimized to ensure precise positioning of implant analog in master cast.
The aim of the study was to compare the precision in obtaining master casts by improving the stability of impression copings in the impression with the use of tray adhesive along various surface treatments to increase surface area and by mechanical locking.
A total of 60 samples were made (15 samples for each group). A total of 15 samples for Group I were prepared with untreated impression copings, 15 samples for Group II with impression copings treated and modified by application of tray adhesive only. Group III includes 15 samples which were fabricated with impression copings modified by making four vertical grooves on surface of impression coping and coated with adhesive. Group IV had 15 samples which were fabricated with impression copings sandblasted with 50 μm aluminum oxide powder and coated with adhesive. Profile projector was used to evaluate the rotational accuracy of the implant analogs by comparing Molar Implant Angle (MIA) and Premolar Implant Angle (PIA) of test samples with reference model. One-way ANOVA and Student t-test were used to analyze the data.
One-way ANOVA didn't show any significant differences for both MIA and PIA between the Groups I, II, III and IV. Student's unpaired t-test revealed no significant difference in the mean MIA and mean PIA. Though results were statistically non-significant, all types of surface treatments of the impression copings showed more accurate transfer than those with no treatment. Sandblasted and adhesive coated impression copings showed minimum amount of rotation followed by those with vertical slots and adhesive coated impression copings.
印模帽在印模中轻微旋转是一个可避免的错误，需要尽量减少以确保种植体代型在工作模型中的精确就位。
本研究的目的是通过使用托盘黏合剂沿不同表面处理增加表面积并通过机械锁定来提高印模帽在印模中的稳定性，比较获得工作模型的精度。
共制作60个样本（每组15个样本）。第一组15个样本采用未经处理的印模帽制备，第二组15个样本采用仅应用托盘黏合剂处理和改良的印模帽。第三组包括15个样本，其印模帽通过在印模帽表面制作四条垂直凹槽并涂覆黏合剂进行改良。第四组有15个样本，其印模帽用50μm氧化铝粉末喷砂并涂覆黏合剂。通过将测试样本的磨牙种植体角度（MIA）和前磨牙种植体角度（PIA）与参考模型进行比较，使用轮廓投影仪评估种植体代型的旋转精度。采用单因素方差分析和学生t检验分析数据。
单因素方差分析显示，第一组、第二组、第三组和第四组之间的MIA和PIA均无显著差异。学生非配对t检验显示，平均MIA和平均PIA无显著差异。尽管结果在统计学上无显著意义，但印模帽的所有表面处理类型均显示出比未处理的更精确的转移。喷砂并涂覆黏合剂的印模帽旋转量最小，其次是有垂直槽并涂覆黏合剂的印模帽。
