Comparison of the transfer accuracy of two digital indirect bonding trays for labial bracket bonding

ObjectivesTo compare the transfer accuracy of two digital transfer trays, the three-dimensional printed (3D printed) tray and the vacuum-formed tray, in the indirect bonding of labial brackets.Materials and MethodsTen digital dental models were constructed by oral scans using an optical scanning system. 3D printed trays and vacuum-formed trays were obtained through the 3Shape indirect bonding system and rapid prototyping technology (10 in each group). Then labial brackets were transferred to 3D printed models, and the models with final bracket positioning were scanned. Linear (mesiodistal, vertical, buccolingual) and angular (angulation, torque, rotation) transfer errors were measured using GOM Inspect software. The mean transfer errors and prevalence of clinically acceptable errors (linear errors of ≤0.5 mm and angular errors of ≤2°) of two digital trays were compared using the Mann-Whitney U-test and the Chi-square test, respectively.ResultsThe 3D printed tray had a lower mean mesiodistal transfer error (P < .01) and a higher prevalence of rotation error within the limit of 2° (P = .03) than did the vacuum-formed tray. Linear errors within 0.5 mm were higher than 90% for both groups, while torque errors within 2° were lowest at 50.9% and 52.9% for the 3D printed tray and vacuum-formed tray, respectively. Both groups had a directional bias toward the occlusal, mesial, and buccal.ConclusionsThe 3D printed tray generally scored better in terms of transfer accuracy than did the vacuum-formed tray. Both types of trays had better linear control than angular control of brackets.     

Transfer accuracy of vinyl polysiloxane trays for indirect bonding

Objective:To elicit the magnitude, directional bias, and frequency of bracket positioning errors caused by the transfer of brackets from a dental cast to the patient’s dentition in a clinical setting.Materials and Methods:A total of 136 brackets were evaluated. The brackets were placed on dental casts and scanned using cone beam computed tomography (CBCT) to capture 3-D positioning data. The brackets were then transferred to the patient’s dentition with an indirect bonding method using vinyl polysiloxane (VPS) trays and later scanned using CBCT to capture the final bracket positioning on the teeth. Virtual models were constructed from the two sets of scan data and digitally superimposed utilizing best-fit, surface-based registration. Individual bracket positioning differences were quantified using customized software. One-tailed t tests were used to determine whether bracket positioning was within limits of 0.5 mm in the mesiodistal, buccolingual, and vertical dimensions, and 2° for torque, tip, and rotation.Results:Individual bracket positioning differences were not statistically significant, indicating, in general, final bracket positions within the selected limits. Transfer accuracy was lowest for torque (80.15%) and highest for mesiodistal and buccolingual bracket placement (both 98.53%). There was a modest directional bias toward the buccal and gingival.Conclusion:Indirect bonding using VPS trays transfers the planned bracket position from the dental cast to the patient’s dentition with generally high positional accuracy.     

Transfer accuracy of 3D-printed trays for indirect bonding of orthodontic brackets:: A clinical study

ObjectivesTo evaluate the transfer accuracy of 3D-printed indirect bonding trays constructed using a fully digital workflow in vivo.Materials and MethodsTwenty-three consecutive patients had their incisors, canines, and premolars bonded using fully digitally designed and 3D-printed transfer trays. Intraoral scans were taken to capture final bracket positioning on teeth after bonding. Digital models of postbonding scans were superimposed on those of corresponding virtual bracket setups, and bracket positioning differences were quantified. A total of 363 brackets were evaluated. One-tailed t-tests were used to determine whether bracket positioning differences were within the limit of 0.5 mm in mesiodistal, buccolingual, and occlusogingival dimensions, and within 2° for torque, tip, and rotation.ResultsMean bracket positioning differences were 0.10 mm, 0.10 mm, and 0.18 mm for mesiodistal, buccolingual, and occlusogingival measurements, respectively, with frequencies of bracket positioning within the 0.5-mm limit ranging from 96.4% to 100%. Mean differences were significantly within the acceptable limit for all linear dimensions. Mean differences were 2.55°, 2.01°, and 2.47° for torque, tip, and rotation, respectively, with frequencies within the 2°-limit ranging from 46.0% to 57.0%. Mean differences for all angular dimensions were outside the acceptable limit; however, this may have been due to limitations of scan data.ConclusionsIndirect bonding using 3D-printed trays transfers planned bracket position from the digital setup to the patient''s dentition with a high positional accuracy in mesiodistal, buccolingual, and occlusogingival dimensions. Questions remain regarding the transfer accuracy for torque, tip, and rotation.     

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。     

Application of silicon hybrid transfer trays to an indirect bonding system through bracket positions referred by 3D digital software

Recently many indirect bonding systems have been developed. However, the necessary laboratory work can be quite complicated. Therefore we developed a method of systematic positioning, and a simple and easy method using a silicone tray.We measured accurate bracket positioning height (BPH-line) and referred to Kalange's method using virtual setup models. We used two characteristically different chemical bonded silicon materials as the tray as part of our indirect bonding method.We found this system to be very useful, simple to apply, and accurate.     

Measurement and comparison of bracket transfer accuracy of five indirect bonding techniques

Objective:To measure and compare bracket transfer accuracy of five indirect bonding (IDB) techniques.Materials and Methods:Five IDB techniques were studied: double polyvinyl siloxane (double-PVS), double vacuum-form (double-VF), polyvinyl siloxane vacuum-form (PVS-VF), polyvinyl siloxane putty (PVS-putty), and single vacuum-form (single-VF). Brackets were bonded on 25 identical stone working models. IDB trays were fabricated over working models (n  =  5 per technique) to transfer brackets to another 25 identical stone patient models. The mesiodistal (M-D), occlusogingival (O-G), and faciolingual (F-L) positions of each bracket were measured on the working and patient models using digital photography (M-D, O-G) and calipers (F-L). Paired t-tests were used to compare bracket positions between working and patient models, and analysis of variance was used to compare bracket transfer accuracy among the five techniques.Results:Between the working and patient models, double-VF had the most teeth with significant differences (n  =  6) and PVS-VF the fewest (n  =  1; P < .05). With one exception, all significant differences were ≤0.26 mm and most (65%) were ≤0.13 mm. When the techniques were compared, bracket transfer accuracy was similar for double-PVS, PVS-putty, and PVS-VF, whereas double-VF and single-VF showed significantly less accuracy in the O-G direction.Conclusions:Although overall differences in bracket position were relatively small, silicone-based trays had consistently high accuracy in transferring brackets, whereas methods that exclusively used vacuum-formed trays were less consistent.     

A three-dimensional printed assembled sleeveless guide system for fiber-post removal

This report describes a technique to develop a three-dimensional printed assembled sleeveless guide system to aid the fiber-post removal in a safe and efficient way. The surface and volume data of the dentition containing the targeted tooth were acquired with optical scanners and cone-beam computed tomography. The virtual path of the fiber-post removal was determined and integrated with a guide prototype with a cylindrical passage. The prototype data was split into two separate parts, combined with the matched pin and jack structures to facilitate the assembly. A guide tube was generated based on the axis of the cylindrical passage, split into three units, and combined with the previously processed data with connectors to form the finalized guide system. The adaptor for the head of handpiece was designed to facilitate the guidance. All the finalized data were printed with titanium alloy. The fiber-post of the upper right central incisor was successfully removed with the aid of this assembled sleeveless guide system that guides the handpiece rather than the rotary instrument.     

不同数字印模技术对3D 打印模型精度的影响

目的：结合3D 打印树脂模型评价2种椅旁扫描系统的扫描精度。方法：仿照上颌牙弓形态及大小制作一金属底座主模型,底座上设计4个柱形金属预备体,分别模拟上颌尖牙和第一磨牙的预备体,右侧尖牙和第一磨牙分别以 A、B 表示,左侧分别以 C、D 表示。分别利用 Cerec 蓝光照相系统和 Cerec 真彩摄像系统扫描主模型各10次,每次扫描生成一个数字化模型。用3D 打印机打印出树脂模型（n ＝10）,在三坐标测量机上分别测量主模型和树脂模型相应柱形金属预备体间的距离 AB、AC、BD 以及 A 的直径 d。采用 SPSS 13．0软件对测量结果进行统计分析。结果：蓝光组 AB、AC、BD 的距离,真彩组 AC、BD的距离分别与主模型差异有显著性（P ＜0．05）;蓝光组与真彩组各距离差异均有显著性（P ＜0．05）。2组的 d 值与主模型差异无显著性（P ＞0．05）。结论：对单个预备体的扫描,Cerec 蓝光照相系统精度高于 Cerec 真彩摄像系统;当扫描区域扩大,Cerec真彩摄像系统精度高于 Cerec 蓝光照相系统。     

Portable fluid circuit device containing printed silicone microvessels as a training aid for arterial microanastomosis

Anastomosis of the microvessels requires high-level skills and extensive basic training. This study was performed to introduce and evaluate an inexpensive laboratory device as a training aid. Micro-tubes of 0.8 mm inner diameter and 0.5/0.8 mm wall thickness mimicking human vein/artery were printed from a silicon-containing hydrogel using three-dimensional printing technology. The hydrogel components are optimized to render the printed tubes biomechanical features resembling the blood vessels of a living organism. These artificial vessels were connected to a pump for fluid flow, simulating the blood circulation. Forty medical interns were assigned to two equal groups. The 20 interns in group A practiced anastomosis using the training aid for a total of 10 hours over 5 days. The 20 interns in group B practiced anastomosis using the traditional gum pieces and silicone tubes. Then, all interns performed anastomosis on rat carotid arteries, and their performance was scored by a team of five experienced maxillofacial surgeons. The average success score and time required for anastomosis were compared between the two groups. The mean success score of group A was significantly higher than that of group B (0.83 ± 0.12 vs 0.64 ± 0.10, P < 0.001). The mean anastomosis time of group A was significantly shorter than that of group B (10.2 ± 1.1 vs 17.2 ± 1.4 minutes, P < 0.001). This training device for vessel microanastomosis is an inexpensive, practical, and effective tool for use in laboratories and also reduces the use of animals.     

3D打印聚乙烯醇/纳米羟基磷灰石支架与丝素蛋白/聚乙烯醇/纳米羟基磷灰石支架的性能比较

目的　采用3D打印技术制备3D打印聚乙烯醇 /纳米羟基磷灰石支架与丝素蛋白/聚乙烯醇/纳米羟基磷灰石支架,并对其进行表征。方法　采用3D打印技术制作聚乙烯醇/纳米羟基磷灰石支架以及丝素蛋白/聚乙烯醇/纳米羟基磷灰石复合支架。进行孔隙率、扫描电镜、压缩力学性能及细胞毒性检测。 结果　①扫描电镜观察：丝素蛋白/聚乙烯醇/纳米羟基磷灰石支架结构规则,网状结构清晰,交通支连续,层层之间搭接良好,支架空隙均一。相同倍数下,聚乙烯醇/纳米羟基磷灰石支架网状结构连续性较差。②压缩力学性能：相同应力情况下（10 MPa）,3D打印丝素蛋白/聚乙烯醇/纳米羟基磷灰石支架的应变大于3D打印聚乙烯醇/纳米羟基磷灰石支架。③孔隙率：3D打印丝素蛋白/聚乙烯醇/纳米羟基磷灰石支架的孔隙率大于3D打印聚乙烯醇/纳米羟基磷灰石支架。④细胞毒性检测：不同时间点两组支架的细胞增殖率无明显差别。结论　结果表明：3D打印聚乙烯醇 /纳米羟基磷灰石支架与丝素蛋白/聚乙烯醇/纳米羟基磷灰石支架具有良好的理化性能和细胞相容性。     

Transfer accuracy of four different lingual retainer transfer methods using digital orthodontic models:: An in vivo comparative study

ObjectivesTo compare the transfer accuracy of four different lingual retainer (LR) transfer methods using three-dimensional digital models.Materials and MethodsFour groups of 17 patients each were created: finger transfer (FT), silicone key transfer (SKT), acrylic resin transfer (ART), and indirect bonding (IDB). At the end of orthodontic treatment, the mandibular dental casts of patients were scanned with the LR wire. Then, intraoral scanning of the mandibular arches was performed after bonding the retainer wires. Linear and angular measurements were made using software on superimposed digital models.ResultsHorizontal and vertical errors among the teeth were not significantly different among the FT, SKT, and ART groups. However, in the IDB group, linear transfer errors showed significant differences among the different teeth. The tip and rotation errors in the FT group were not significantly different among the teeth. The angular errors were lower in canines than in the incisors. In all measured parameters, the SKT group showed the lowest errors, whereas the FT group had the highest transfer errors in all parameters except vertical.ConclusionsAmong the transfer methods tested, SKT was determined to have the highest clinical accuracy.     

Impact of different pretreatments and attachment materials on shear bond strength of indirectly bonded brackets using CAD/CAM transfer trays to monolithic zirconia

ObjectiveInvestigating the impact of different pretreatment methods, attachment materials and aging regimens on shear bond strength (SBS) between zirconia and indirectly bonded brackets using CAD/CAM transfer trays.MethodsZirconia substrates were conditioned with silica coated alumina (CoJet) and a) Clearfil Ceramic Primer Plus (CF), b) RelyX Ceramic Primer (RXP), c) Futurabond U (FU). Brackets were virtually placed, transfer tray designed (OnyxCeph) and 3D-printed for indirect bonding with a) Transbond LV (TBL), b) Nexus NX3 (NX3), c) Maximum Cure (MC). SBS testing was performed with a universal testing machine after 24 h, 500 thermal cycles, 90 d. Directly bonded brackets to human enamel using Transbond XT Adhesive served as control. The adhesive remnant index (ARI) was evaluated. Data was analyzed with Shapiro–Wilk, Kruskal–Wallis and Dunn’s post-hoc test with Bonferroni correction, Chi² test (p < 0.05), and the Weibull modulus was calculated.ResultsSBS ranged from 0.1 to 15.5 MPa and were influenced mostly by the attachment material. NX3 generally showed the highest values (9.5–15.8 MPa). Initially RXP/TBL and FU/TBL presented the lowest values (4.3/4.8 MPa). Aging regimens reduced SBS of MC irrespective of pretreatment, after 90 d values ranged from 0.1 to 0.9 MPa. ARI 1 was predominant in all MC groups and FU/NX3, 2 and 3 in the other groups. Weibull moduli ranged between 0.15 (MC/RXP/500 TC) and 6.24 (NX3/RXP/500 TC).SignificanceMC seems not to be suitable for indirect bonding using CAD/CAM transfer trays to zirconia. NX3 showed similar SBS values compared to the control, TBL lower.     

The accuracy of matching three-dimensional photographs with skin surfaces derived from cone-beam computed tomography

The state-of-the-art diagnostic tools in oral and maxillofacial surgery and preoperative orthodontic treatment are mainly two-dimensional, and consequently reveal limitations in describing the three-dimensional (3D) structures of a patient's face. New 3D imaging techniques, such as 3D stereophotogrammetry (3D photograph) and cone-beam computed tomography (CBCT), have been introduced. Image fusion, i.e. registration of a 3D photograph upon a CBCT, results in an accurate and photorealistic digital 3D data set of a patient's face. The purpose of this study was to determine the accuracy of three different matching procedures. For 15 individuals the textured skin surface (3D photograph) and untextured skin surface (CBCT) were matched by two observers using three different methods to determine the accuracy of registration. The registration error was computed as the difference (mm) between all points of both surfaces. The registration errors were relatively large at the lateral neck, mouth and around the eyes. After exclusion of artefact regions from the matching process, 90% of the error was within+/-1.5 mm. The remaining error was probably caused by differences in head positioning, different facial expressions and artefacts during image acquisition. In conclusion, the 3D data set provides an accurate and photorealistic digital 3D representation of a patient's face.     

Objects build orientation,positioning, and curing influence dimensional accuracy and flexural properties of stereolithographically printed resin

Objective

To evaluate the influence of printing parameters on flexural properties and accuracy of SLA-printed standard objects.

The accuracy of maxillary positioning using digital model planning and 3D printed wafers in bimaxillary orthognathic surgery

Objective: Orthognathic wafers may be made using digital model movements and CAD-CAM technology. This paper analysed the accuracy of maxillary movements using this new process.

Design: Retrospective study of pre and post-operative cephalograms.

Participants: Thirty consecutive orthognathic patients undergoing bimaxillary osteotomies in a UK hospital.

Methods: Jaw movements were planned using cephalometric and Orthoanalyzer? software. The resultant intermediate and final wafer occlusal relationships were used for wafer fabrication by 3D printing of the inter-occlusal space. Pre- and post-operative lateral cephalograms were compared in terms of maxillary antero-posterior and vertical movements. Statistical analyses including the paired t-test, two-sample t-test and Fisher’s exact test.

Results: Wide individual variation was observed between the planned and actual movements. Thirteen cases (43%) had a 2 mm discrepancy in at least one variable. Statistically significant differences between the planned and actual maxillary vertical movements were observed for the molar (U6y: p < 0.0001) and anterior maxillary (Ay: p < 0.01) differences. Analysis of a subgroup with primarily impaction movements demonstrated a statistically significant bias towards excessive maxillary advancement (U1x: p < 0.01) and incisor impaction (U1y: p < 0.01) in this group.

Conclusions: This new digital surgical wafer technique achieves a similar level of accuracy to the conventional facebow and model surgery process.