Comparison of accuracy between digital and conventional implant impressions: two and three dimensional evaluations

PURPOSEThe present study compared the accuracy between digital and conventional implant impressions.MATERIALS AND METHODSThe experimental models were divided into six groups depending on the implant location and the scanning span. Digital impressions were captured using the intraoral optical scanner TRIOS (3Shape, Copenhagen, Denmark). Conventional impressions were taken with the monophase impression material based on addition-cured silicones, Honigum-Mono (DMG, Hamburg, Germany). A high-precision laboratory scanner D900 (3Shape, Copenhagen, Denmark) was used to obtain digital data of resin models and stone casts. Surface tessellation language (STL) datasets from scanner were imported into the analysis software Geomagic Qualify 14 (3D Systems, Rock Hill, SC, USA), and scan body deviations were determined through two-dimensional and three-dimensional analyses. Each scan body was measured five times. The Sidak t test was used to analyze the experimental data.RESULTSImplant position and scanning distance affected the impression accuracy. For a unilateral arch implant and the mandible models with two implants, no significant difference was observed in the accuracy between the digital and conventional implant impressions on scan bodies; however, the corresponding differences for trans-arch implants and mandible with six implants were extremely significant (P<.001).CONCLUSIONFor short-span scanning, the accuracy of digital and conventional implant impressions did not differ significantly. For long-span scanning, the precision of digital impressions was significantly inferior to that of the traditional impressions.     

Effect of impression coping and implant angulation on the accuracy of implant impressions: an in vitro study

PURPOSE

The purpose of this study was to compare the accuracy of the implant master cast according to the type (pick-up, transfer) and the length (long, short) of the impression copings.

MATERIALS AND METHODS

The metal master cast was fabricated with three internal connection type implant analogs (Osstem GS III analog), embedded parallel and with 10° of mesial angulation to the center analog. Four types of impression coping were prepared with different combinations of types (transfer, pick-up) and lengths (long, short) of the coping. The impressions were made using vinyl polysiloxane (one step, heavy + light body) with an individual tray, and 10 impressions were made for each group. Eventually, 40 experimental casts were produced. Then, the difference in the distance between the master cast and the experimental cast were measured, and the error rate was determined. The analysis of variance was performed using the SPSS (v 12.0) program (α = .05), and the statistical significance was set at P < .05.

RESULTS

The ANOVA showed that the pick-up type impression coping exhibited a significantly lower error rate than the transfer type. However, no significant difference was observed with respect to the length of the impression coping. Additionally, no significant difference was observed between the parallel and mesial angulated groups.

CONCLUSION

Within the limitations of this study, the pick-up type impression coping exhibited a more accurate implant master cast than the transfer type in parallel group. The accuracy of the implant master cast did not differ for different lengths of impression coping of at least 11 mm. Additionally, the accuracy of the implant cast was not different for the parallel and 10° mesial angulated groups.     

三种印模材料在根管取模中的比较研究

目的：采用3种印模材料对离体牙根管进行取模,对比观察桩核微渗漏情况。方法：离体前磨牙根管治疗后桩道预备,分别用琼脂、硅橡胶、聚醚橡胶进行根管取模,桩核修复后观测微渗漏情况。结果：硅橡胶组和聚醚橡胶组微渗漏小于琼脂组,组间比较差异有统计学意义（P<0．05）,前两组间差异无统计学意义（P>0．05）。结论：硅橡胶和聚醚橡胶是很好的根管取模印模材。     

摄影测量与传统印模技术制取牙列缺失种植修复印模精度的比较研究

目的:通过体外实验对比摄影测量与传统印模技术制取牙列缺失种植修复印模的精度。方法:选择1例2019年9月就诊于首都医科大学口腔医学院种植中心的74岁男性上颌牙列缺失患者的上颌石膏模型,其上含螺丝固位基台替代体8个。通过开窗夹板式印模复制该石膏模型,将复制模型作为参考模型。由同1名主治医师用两种方法制取参考模型种植体基台...     

A new, simple implant-level impression technique for dental implants in limited interproximal space

Making an implant-level impression when implants are placed in limited interproximal space or compromising angulations can be a time-consuming procedure. This article presents a new method for developing a master cast for two implants clinically placed convergent and very close to each other. The technique consists of making an implant-level impression using a transfer jig fabricated on dental abutments.     

三种模型材料在不同印模材料中尺寸变化的实验研究

目的：本实验旨在观察印模材料对工作模型精度的影响以及模型材料与印模材料间的配伍性。方法将普通石膏、硬石膏、超硬石膏３种模型材料分别灌入金属印模,硅橡胶印模,藻酸盐印模和旨印模中,用激光热膨胀仪（日本产１０００型）测量各组试件的凝固时的尺寸变化,将所得数据换算成尺寸变化率并进行统计分析。结果①普通石 在金属印模中呈现为收缩,而在硅橡胶,藻酸盐及琼脂印模中为高度膨胀,其在各种印模材料中的凝固尺寸变化率有显著性差异。②硬石膏在四种印模材料中的凝固尺寸变化率为均小于０．１５％,尤以在金属及藻酸盐印模中尺寸变化较小,性能较稳定。③超硬膏在金属印模中呈现为膨胀,在硅橡胶及藻酸盐印模中尺寸变化稳定,均不超过０．１０％。而在琼脂中表面为明显的收缩。结论各种模型材料同一种印模中的尺寸变化率不同,同一种模型材料在不同的印模中尺寸变     

种植数字化印模精确度分析

目的：测试种植数字化印模的精确度,为种植数字化修复提供参考。方法：随机选取115例种植患者,待骨结合形成后放置种植转移杆,拍摄锥形束CT（CBCT）,同时进行口腔扫描,制作3D打印数字化种植模型,对数字化树脂模型进行模型扫描,得到模型数据,以余留牙为参考依据,在Nobel Clinicion软件中匹配。结果：患者CBCT中种植体转移杆与数字化模型上的种植体转移杆面、冠状面、矢状面均完全匹配重叠,提示口腔内的种植体位置、方向、角度与口腔扫描制取的数字化模型上的替代体完全一致。结论：口腔扫描打印的3D数字化树脂模型完全准确,可在临床上推广运用。     

Factors affecting the accuracy of elastometric impression materials

Objectives. The purpose of this study was to evaluate the effects of (1) various impression materials, (2) different storage times and (3) the proportion of inorganic filler on the accuracy and stability of elastometric impression materials.

Methods. The impression materials studied included three alginate impression materials (Algiace Z, CAVEX and Jeltrate), five commercial silicone impression materials (Aquasil, Exaflex regular type, Express, Coltex fine and Rapid liner) and two experimental silicone impression materials designed for this study (KE106A and KE106B). Impressions were made of 10 metal dies that mimicked prepared crowns. After an impression was taken, dental stone was immediately poured into the alginate impressions, while the silicone impressions was poured 30 min later and waited for 1 h for setting. The second and third stone dies were made 1 and 24 h later, respectively. The diameters of the occlusal surfaces of the metal dies and stone casts were determined using photographs of the surfaces taken with a Kodak DC 290 digital camera. The pictures were then measured using a photomicrograph digitized integration system to calculate any discrepancy. Because each impression was used to make three rounds of stone dies, two-factor mixed factorial ANOVA was used to evaluate the effect of materials and storage time on the accuracy of the stone casts. The simple effects analysis, combined with multiple comparisons considering the per family type I error rate, was performed following confirmation that an interaction between the two factors was significant.

Results. The results showed that: (1) there was a significant interaction effect between materials and storage times on the accuracy of the impressions. (2) Two addition type silicone materials, Aquasil and Exaflex, had the greatest accuracy and stability. (3) The experimental material KE106A had the least accuracy in the first and second rounds and the alginate impression material CAVEX had the least accuracy in the third round. (4) The stabilities of CAVEX and Jeltrate were the least consistent of the 10 materials and decreased significantly with storage time. (5) When the experimental material had a low proportion of filler (KE106A), there was a significantly greater dimensional discrepancy compared to the same material with a higher proportion of filler (KE106B).

Conclusions. The accuracies varied among the 10 impression materials over three rounds. Of all the materials, the addition type silicone materials, Aquasil and Exaflex, had relatively greater accuracy and stability. The discrepancy of the alginate impression materials increased with storage time. The large loading of filler showed less discrepancy.     

The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study

Aim of the Study:

To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique.

Methodology:

A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint^™ II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector.

Statistical Analysis:

The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student''s Newman–Keul''s test.

Results:

When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint^™ II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint^™ II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint^™ II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively.

Conclusion:

Among the impression materials Imprint^™ II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results.Key Words: Dimensional accuracy, double mix impression technique, impression materials, polyvinyl siloxane, single mix impression technique     

2种CAD/CAM口腔数字化导板精度的比较

目的： 比较2种CAD/CAM口腔数字化导板的精度。方法： 选择上海市静安区牙病防治所就诊的36例口腔种植患者,均行CBCT检查和口内激光扫描,所获数据导入3Shape软件,进行术前设计。每个病例生成2个导板,A导板数据来自CBCT,B导板数据为CBCT和口内激光扫描数据的拟合,随机选择导板类型并使用。术后拍摄CBCT并将数据导入设计软件,与种植前设计的位置进行比较。采用R语言4.1.0对数据进行统计学分析。结果： B导板组种植体顶部中心点距离偏差、种植体底部中心点距离偏差和两中心点连线的角度偏差显著小于A导板组（P<0.05）。结论： CBCT和口内激光扫描数据拟合生成的CAD/CAM口腔数字化导板精度更高,有利于提高种植体植入的三维位置精确度。     

几种常用印模材制取固定义齿模型伯三维精度比较

目的：评价硅橡胶类、琼脂类、藻酸盐类（水粉剂与糊剂）等4各临床常用印模材料的取模精度。方法：分别用4种模型材料制取10个同一金属实验模具的石膏模型,用测量显微镜测量金属模型和石膏模型上各标志点的距离,精度为0．001mm,所得数据进行统计分析。结果：藻酸盐糊剂印模材料制取的石膏模型在长径方向上与其他组有显著差异,且超出了临床允许的精度范围;硅橡胶印模材料制取的石膏模型线性变化率最小且比金属模型略大;琼脂印模材料与藻酸盐印模材料（水粉剂）制取的印模在三维尺寸变化率方面无显著差异。结论：藻酸盐糊剂印模材料取模精度差;硅橡胶印模材料的取模精度最高,且可以起到补偿义齿后续操作中的收缩及提供冠桥粘结剂间隙的作用;琼脂印模材料具有印模精度高,操作比较简单,且价格易于接受等优点,值得在临床应用中进一步普及和推广。     

Wear particle release at the interface of dental implant components: Effects of different material combinations. An in vitro study

ObjectivesParticle generation from implant components caused by frictional wear affect the surrounding peri-implant tissues. The objective of this study was to evaluate the effect of combining implant and abutment materials on wear and particle release in a dynamical loading setup.MethodsA customized dynamical loading machine was used to subject two implant materials (Titanium and Titanium- Zirconium alloy) paired with two different abutment materials (Titanium and Zirconia) to a cyclic loading set of 240.000 cycles (simulating 1 year of clinical use). The implant and abutment complex was immersed in corrosive liquid to collect particle debris and measure the release of corroded ions. Scanning electron microscopy was used to analyze signs of wear on the components after testing and evaluate the size and composition of particle debris.ResultsWear signs were evident in all material couplings. Particle debris was found on top, inside the implants, and on the abutment heads. The particle size ranged between 0.6 and 16.9 µm, with larger particles composed of Ti. Smaller-sized particles were found in the container liquid ranging from 0.253 to 1.7 µm compared to inside the implants ranging from 3.25 to 95.3 µm. Larger particles were found inside Tizr implants compared to Ti implants. Low levels of ions released due to corrosion were found when measuring content in surrounding liquid.SignificanceParticle generation is evident when subjecting dental implant and abutment couplings in a dynamic loading setup. Internally connected implants hinder the release of larger particles to surrounding container liquid.     

A comparative analysis of the accuracy of different direct impression techniques for multiple implants

Background: The aim of this study was to compare the accuracy of different direct implant impression techniques for edentulous arches with multiple implants. Methods:  Five experimental groups (n = 5) were assembled. Experimental models were created by a direct splinted technique (EG2 to EG5) and a non‐splinted technique (EG1). In EG2 and EG3 synOcta impression copings were splinted with an acrylic resin bar, and in EG4 and EG5 with a light‐curing composite resin bar. In EG3 and EG5 the resin bars were sectioned, while the other experimental groups were not. Three‐dimensional discrepancies were measured by a computerized coordinate measuring machine. Distortion values among the groups were analysed using one‐way repeated measures ANOVA. The post hoc Tukey’s test was then performed for multiple comparisons. Results:  The highest accuracy was obtained in EG2 (mean deviation: 12.70 μm). The acrylic bars demonstrated less deviation (12.70 μm and 22.71 μm) from the master model than the light‐curing composite resin groups and the non‐splinted group (41.09 μm). The post hoc Tukey’s test showed no significant difference among the groups when the effect of splint design on accuracy was investigated. Conclusions:  For situations where impressions of multiple implants are to be made, splinting impression copings with acrylic resin demonstrate superior results than the non‐splinted technique and splinting with light‐curing composite.     

1144颗种植牙修复临床效果分析

目的评价北京口腔医院种植中心2000年1月至2005年4月所完成种植修复病例的临床效果。方法2000年1月至2005年4月共植人种植体2158颗,随访观察时间3-8年。依照珠海种植会议标准,采用寿命表法进行统计分析。结果2000年1月至2005年4月种植病例1125人,随访到577人,1144颗种植体。累计5年存留率91．37％。结论累计种植5年存留率达到91．37％。     

三种间接粘接方法转移托槽的准确性比较

目的:比较间接粘接技术中使用不同转移托盘转移托槽的准确性。方法:选择2019年7月至2021年1月空军军医大学口腔医院正畸科就诊的患者28例,分为A、B、C三组,分别使用3D打印托盘、双层压膜塑料托盘、双层硅橡胶托盘粘接托槽。A组口内扫描获取工作模型,使用软件定位托槽,再导出数字化模型,作为该组托槽转移前的数字化模型。B组和C组在工作石膏模型上定位托槽,使用口内扫描仪扫描,获取B组和C组托槽转移前的数字化模型。A、B、C组制作相应的转移托盘,将托槽粘接至患者口内后对患者口内扫描,获取三组托槽实际粘接的数字化模型。使用Geomagic软件测量转移前后的数字化模型,获取使用不同托盘时,托槽粘接的实际位置距离预设在近远中方向、龈 方向、颊舌方向上的线距误差,超过0.5 mm的托槽转移线距误差定义为严重误差。 结果:近远中向上B组与A组间、C组与A组间严重误差发生率的差异存在统计学意义( P<0.05)。龈 向上3组组间的严重误差发生率差异均存在统计学意义( P<0.05)。颊舌向上3组组间的严重误差发生率差异无统计学意义。 结论:(1)3D打印托盘转移托槽时严重误差的发生率显著高于双层硅橡胶托盘与双层压膜塑料托盘。(2)双层硅橡胶托盘粘接托槽时严重误差的发生率最低。     

三种间接粘接方法转移托槽的准确性比较

目的:比较间接粘接技术中使用不同转移托盘转移托槽的准确性。方法:选择2019年7月至2021年1月空军军医大学口腔医院正畸科就诊的患者28例,分为A、B、C三组,分别使用3D打印托盘、双层压膜塑料托盘、双层硅橡胶托盘粘接托槽。A组口内扫描获取工作模型,使用软件定位托槽,再导出数字化模型,作为该组托槽转移前的数字化模型。B组和C组在工作石膏模型上定位托槽,使用口内扫描仪扫描,获取B组和C组托槽转移前的数字化模型。A、B、C组制作相应的转移托盘,将托槽粘接至患者口内后对患者口内扫描,获取三组托槽实际粘接的数字化模型。使用Geomagic软件测量转移前后的数字化模型,获取使用不同托盘时,托槽粘接的实际位置距离预设在近远中方向、龈 方向、颊舌方向上的线距误差,超过0.5 mm的托槽转移线距误差定义为严重误差。 结果:近远中向上B组与A组间、C组与A组间严重误差发生率的差异存在统计学意义( P<0.05)。龈 向上3组组间的严重误差发生率差异均存在统计学意义( P<0.05)。颊舌向上3组组间的严重误差发生率差异无统计学意义。 结论:(1)3D打印托盘转移托槽时严重误差的发生率显著高于双层硅橡胶托盘与双层压膜塑料托盘。(2)双层硅橡胶托盘粘接托槽时严重误差的发生率最低。     

即刻种植与即刻修复的临床应用

目的 探讨即刻种植与即刻修复的临床运用原则，并初步评价临床疗效。方法 14例患者共37个牙位在拔牙同时植入了种植体，其中6例共14个牙位即刻种植后又行即刻修复。平均4个月后进行Ⅱ期手术和最终修复。修复后平均追踪观察时间为22个月。结果 除1例2枚种植体于即刻种植并即刻修复后3周松脱外，其余病例自修复完成至最后一次复查，临床效果良好，4年累积存活率达到94．6％。结论在适当选择病例的情况下，即刻种植与即刻修复可成功应用于临床，并获得较高的存活率。     

The use of a 3D laser scanner using superimpositional software to assess the accuracy of impression techniques

Objective. Several studies have made comparisons in the dimensional accuracy of different elastomeric impression materials. Most have used two-dimensional measuring devices, which neglect to account for the dimensional changes that exist along a three-dimensional surface.

Purpose. The aim of this study was to compare the dimensional accuracy of an impression technique using a polyether material (Impregum) and a vinyl poly siloxane material (President) using a laser scanner with three-dimensional superimpositional software.

Materials and methods. Twenty impressions, 10 with a polyether and 10 with addition silicone, of a stone master model that resembled a dental arch containing three acrylic posterior teeth were cast in orthodontic stone. One plastic tooth was prepared for a metal crown. The master model and the casts were digitised with the non-contacting laser scanner to produce a 3D image. 3D surface viewer software superimposed the master model to the stone replica and the difference between the images analysed.

Results. The mean difference between the model and the stone replica made from Impregum was 0.072 mm (SD 0.006) and that for the silicone 0.097 mm (SD 0.005) and this difference was statistically significantly, p=0.001.

Conclusions. Both impression materials provided an accurate replica of the prepared teeth supporting the view that these materials are highly accurate.     

A laboratory study of dimensional changes for three elastomeric impression materials using custom and stock trays

Clinical success of fixed prosthodontic procedures is dependent in part upon the dimensional accuracy of elastomeric impression materials and impression procedures. Three elastomeric impression materials were used in custom and stock trays to determine the accuracy of impressions taken from an experimental stainless steel model representing premolar and molar bridge abutment preparations. Horizontal and vertical individual abutment and interabutment dimensions were measured on die stone replicas, and the measurements compared with those obtained from stainless steel master models. The results of this study demonstrate polysulphide is the least accurate impression material for both vertical and horizontal individual abutment dimensions. However, for interabutment horizontal dimensions, no statistical differences were noted between impression material types when using a custom tray. Stock trays produced unreliable results for all the materials tested.