Objective: To provide a reference for using intraoral scanners for making clinical diagnostic dentures of edentulous jaws by comparing the accuracy of three intraoral scanners for primary impression and jaw relation record of edentulous jaws.
Methods: This study contained 6 primary impressions of the edentulous patients. Each of the impressions consisted of the maxillary primary impression, the mandibular primary impression and the jaw relation record. For each of them, a dental cast scanner (Dentscan Y500) was used to obtain stereolithography (STL) data as reference scan, and then three intraoral scanners including i500, Trios 3 and CEREC Primescan were used for three times to obtain STL data as experiment groups. In Geomagic Studio 2013 software, trueness was obtained by comparing experiment groups with the reference scan, and the precision was obtained from intragroup comparisons. Registered maxillary data of the intraoral scan with reference scan, the morphological error of jaw relation record was obtained by comparing jaw relation record of the intraoral scan with the reference scan. Registered mandibular data with jaw relation record of intraoral scan and the displacement of the jaw position were evaluated. Independent samples t test and Mann-Whitney U test in the SPSS 20.0 statistical software were used to statistically analyze the trueness, precision and morphological error of jaw relation record of three intraoral scanners. The Bland-Altman diagram was used to evaluate the consistency of the jaw relationship measured by the three intraoral scanners.
Results: The trueness of i500, Trios 3 and CEREC Primescan scanners was (182.34±101.21) μm, (145.21±71.73) μm, and (78.34±34.79) μm for maxilla; (106.42±21.63) μm, and 95.08 (63.08) μm, (78.45±42.77) μm for mandible. There was no significant difference in trueness of the three scanners when scanning the maxilla and mandible(P>0.05). The precision of the three scanners was 147.65 (156.30) μm, (147.54±83.33) μm, and 40.30 (32.80) μm for maxilla; (90.96±30.77) μm, (53.73±23.56) μm, and 37.60 (93.93) μm for mandible. The precision of CEREC Primescan scanner was significantly better than that of the other two scanners for maxilla (P<0.05). Trios 3 and CEREC Primescan scanners were significantly better than i500 scanner for mandible (P<0.05). The precision of the i500 and Trios 3 scanners for mandible was superior to maxilla (P<0.05). The upper limit of 95% confidence intervals of trueness and precision of three scanners for both maxilla and mandible were within ±300 μm which was clinically accepted. The morphological error of jaw relation record of the three scanners was (337.68±128.54) μm, (342.89±195.41) μm, and (168.62±88.35) μm. The 95% confidence intervals of i500 and Trios 3 scanners were over 300 μm. CEREC Primescan scanner was significantly superior to i500 scanner(P<0.05).The displacement of the jaw position of the three scanners was (0.83±0.56) mm, (0.80±0.45) mm, and (0.91±0.75) mm for vertical dimension; (0.79±0.58) mm, (0.62±0.18) mm, and (0.53±0.53) mm for anterior and posterior directions; (0.95±0.59) mm, (0.69±0.45) mm, and (0.60±0.22) mm for left and right directions. The displacement of the jaw position of the three scanners in vertical dimension, anterior and posterior directions and the left and right directions were within the 95% consistency limit.
Conclusion: Three intraoral scanners showed good trueness and precision. The i500 and Trios 3 scanners had more errors in jaw relation record, but they were used as primary jaw relation record. It is suggested that three intraoral scanners can be used for obtaining digital data to make diagnostic dentures and individual trays, reducing possible deforming or crack when sending impressions from clinic to laboratory.
方法: 共纳入无牙颌患者红膏初印模6副,每副印模包含上颌初印模、下颌初印模和上颌背面的颌位记录。使用Dentscan Y500牙颌模型三维扫描仪扫描红膏初印模获取三角网格数据(stereolithography,STL)格式数据作为参考模型。分别使用i500,Trios 3和CEREC Primescan三款口内三维扫描仪扫描红膏初印模获取STL数据,重复3次作为实验组。在Geomagic Studio 2013软件中,将口内三维扫描仪扫描获得的数据与参考模型比较评价正确度,同一扫描仪三次扫描的数据互相比较评价精密度。将口内三维扫描仪扫描的上颌数据与参考模型上颌数据配准,评价颌位记录扫描的形态误差。将口内三维扫描仪扫描的下颌与颌位记录配准,评价下颌颌位的偏差。采用SPSS 20.0统计软件,对三款口内三维扫描仪的正确度、精密度和颌位记录的形态误差分别进行独立样本t检验和Mann-Whitney U非参数检验。采用Bland-Altman图示法对三款口内三维扫描仪测量的下颌颌位的一致性进行两两评价,判断其在垂直方向、前后方向和左右方向偏移量的差异。
结果: i500、Trios 3和CEREC Primescan三款扫描仪的正确度分别为:上颌(182.34±101.21) μm,(145.21±71.73) μm,(78.34±34.79) μm;下颌(106.42±21.63) μm,95.08(63.08) μm,(78.45±42.77) μm。扫描上、下颌时三款扫描仪的正确度差异无统计学意义(P>0.05)。三款扫描仪的精密度分别为:上颌147.65(156.30) μm,(147.54±83.33) μm,40.30(32.80) μm;下颌(90.96±30.77) μm,(53.73±23.56) μm,37.60(93.93) μm。扫描上颌时CEREC Primescan扫描仪精密度显著优于另两款扫描仪(P<0.05),扫描下颌时Trios 3和CEREC Primescan 扫描仪的精密度显著优于i500扫描仪(P<0.05),i500和Trios 3扫描仪扫描下颌的精密度优于上颌(P<0.05)。三款扫描仪扫描上、下颌初印模的正确度和精密度的95%置信区间的上、下限均在±300 μm范围内。扫描颌位记录的形态误差,i500扫描仪(337.68±128.54) μm,Trios 3扫描仪(342.89±195.41) μm,CEREC Primescan扫描仪(168.62±88.35) μm,i500扫描仪和Trios 3扫描仪的95%置信区间上限大于300 μm,CEREC Primescan扫描仪显著优于i500扫描仪(P<0.05)。扫描测量的下颌颌位,垂直差异:i500扫描仪(0.83±0.56) mm,Trios 3扫描仪(0.80±0.45) mm,CEREC Primescan扫描仪(0.91±0.75) mm;水平前后差异:i500扫描仪(0.79±0.58) mm,Trios 3扫描仪(0.62±0.18) mm,CEREC Primescan扫描仪(0.53±0.53) mm;水平左右差异:i500扫描仪(0.95±0.59) mm,Trios 3扫描仪(0.69±0.45) mm,CEREC Primescan扫描仪(0.60±0.22) mm。Bland-Altman图示法三款扫描仪扫描获得的下颌颌位在垂直方向、前后方向和左右方向的偏移量两两之间比较均位于95%一致性界限内。
结论: 三款口内三维扫描仪扫描上、下颌红膏初印模表现出较好的正确度和精密度, i500和Trios 3扫描仪记录的颌位记录的误差较大,但仅作为初始颌位记录使用,提示临床医生可以使用这三种口内三维扫描仪应用于数字化全口义齿前期数据获取来制作诊断义齿和个别托盘,减少将红膏初印模长途寄运至技工室导致的红膏碰撞破损及高温变形。