3D printed simulation models based on real patient situations for hands‐on practice

During the last few years, the curriculum of many dentistry schools in Germany has been reorganised. Two key aspects of the applied changes are the integration of up‐to‐date teaching methods and the promotion of interdisciplinarity. To support these efforts, an approach to fabricating individualised simulation models for hands‐on courses employing 3D printing is presented. The models are based on real patients, thus providing students a more realistic preparation for real clinical situations. As a wide variety of dental procedures can be implemented, the simulation models can also contribute to a more interdisciplinary dental education. The data used for the construction of the models were acquired by 3D surface scanning. The data were further processed with 3D modelling software. Afterwards, the models were fabricated by 3D printing with the PolyJet technique. Three models serve as examples: a prosthodontic model for training veneer preparation, a conservative model for practicing dental bonding and an interdisciplinary model featuring carious teeth and an insufficient crown. The third model was evaluated in a hands‐on course with 22 fourth‐year dental students. The students answered a questionnaire and gave their personal opinion. Whilst the concept of the model received very positive feedback, some aspects of the implementation were criticised. We discuss these observations and suggest ways for further improvement.     

Use of 3D printed models in student education of craniofacial traumas

A low‐cost 3D printed model has been introduced into the oral and maxillofacial surgery teaching program of undergraduate students to improve education and mechanical comprehension of craniofacial trauma. Steps of the 3D printed haptic model building process are listed. 3D printed models of facial fractures were obtained from Data Imaging and Communications in Medicine (DICOM) data. Computed Aided Design and Manufacturing (CAD‐CAM) freeware was used to create new fractures on the standard tessellation language (STL) file. 3D printed haptic model appears to be an efficient low‐cost support for craniofacial trauma education of undergraduate students.     

Bilateral sagittal split osteotomy training on mandibular 3-dimensional printed models for maxillofacial surgical residents

Complications with bilateral sagittal split osteotomy (BSSO) can sometimes result from surgical inexperience. Our aim was to present a 3-dimensional printed mandibular model for BSSO training in a maxillofacial surgical education programme. A polymethacrylate mandibular model obtained from mandibular cone-beam computed tomographic (CT) images was designed and printed for use in training. Twenty-four residents were each asked to do a BSSO according to the Epker/Dal-Pont technique. The session was conducted as a simulation course with a final debriefing. A questionnaire before and after the test was filled in using a 10-point Likert scale to assess the participants’ knowledge. The mandibular model provided a realistic way of handling the trabecular bone after cortical osteotomy, as well as in the splitting phase. Significant increases in knowledge and surgical skills were noted for all steps of the BSSO, particularly regarding the use of the piezoelectric device for osteotomy, and for management of wisdom teeth in the splitting zone (3.00 ±2.16 to 6.95 ±2.06 and 2.73 ±1.91 to 5.75 ±2.63, respectively; p₁ = 0.0002 and p₂ = 0.0003). We think that this is a valuable printed mandibular model for the development of surgical skills for BSSO in maxillofacial surgical residents.     

Three-body wear of 3D printed temporary materials

ObjectiveThe aim of this study was to investigate the three-body wear of different additively manufactured temporary materials, one temporary PMMA material for CAD/CAM milling and one resin-based composite for direct restorations as a control group by using an ACTA machine.MethodsSpecimens (n = 8) of the 3D printing materials 3Delta temp, NextDent C&B, Freeprint temp were additively manufactured by DLP 3D printer. Postprocessing was carried out according to the manufacturer's specifications. Telio CAD were cut out of blocks, Tetric EvoCeram was applied directly and light cured. Three-body wear was simulated with an ACTA machine. Data were statistically analysed (ANOVA, post hoc test: Tukey, p < 0.05). The worn surfaces of the specimens were examined with a FE-SEM.ResultsThe average mean wear was 50 ± 15 μm for Tetric EvoCeram < 62 ± 4 μm for 3Delta temp < 236 ± 31 μm for Telio CAD < 255 ± 13 μm for NextDent C&B < 257 ± 24 μm for Freeprint temp. After 200,000 cycles, the wear and wear rates for Tetric EvoCeram and 3Delta temp were significantly lower than those for the other materials. SEM revealed that 3Delta temp has a higher filler proportion than the other 3D printing materials but less than Tetric EvoCeram.SignificanceThe filler content influences the wear behaviour of additively manufactured materials as well as dental restorative composite materials. While most 3D printing materials have a low inorganic filler load, which qualifies the materials for temporary use only, one 3D printing material has an optimized composition that would qualify the material for longer clinical service time if wear is considered as the outcome variable.     

3D printed versus conventionally cured provisional crown and bridge dental materials

Objectives

To optimize the 3D printing of a dental material for provisional crown and bridge restorations using a low-cost stereolithography 3D printer; and compare its mechanical properties against conventionally cured provisional dental materials.

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.     

3D打印多孔钽种植体对骨整合影响的实验研究

目的 研究多孔钽及多孔钛种植体对骨整合的影响。方法 通过计算机辅助设计方法建模,采用3D打印技术制备两种微孔参数相同的多孔材料种植体：多孔钽及多孔钛。在24只新西兰大白兔双侧股骨外踝处建立骨缺损模型,每只动物左右侧缺损随机分组,分别用多孔钽（实验组）和多孔钛（对照组）种植体进行修复。种植体植入后2、4、8周取材,进行大体观察和亚甲基蓝-酸性品红染色,观测种植体和骨界面的骨整合情况,采用推出实验测试种植体-骨界面结合强度。 结果 术后2、4、8周,两组材料界面的新生骨组织逐渐增加,出现新生骨小梁并向材料孔隙内生长;两组的成骨情况及种植体-骨组织界面结合强度的差异无统计学意义（P>0.05）。结论 3D打印的多孔钽能与骨组织形成早期的生物结合,具有与多孔钛相当的骨整合能力。     

基于3D打印水凝胶技术的显微外科仿真训练教具的研制与应用效果评价

目的 采用3D打印水凝胶技术制作微小仿真血管,以此为基础,研发一种显微外科训练教具,并评估其教学效果和适用性。方法 利用3D打印水凝胶技术制作微小血管,设计管路连接系统、血液循环泵等部件,研制出显微外科仿真训练教具。从空军军医大学口腔医院口腔颌面外科选择10名具有丰富显微外科经验的教师,试用新教具,通过问卷打分形式评价其与传统显微外科训练教具之间的差别。选择24名口腔医学专业第五年实习学生,随机分为对照组和实验组,每组12人,对照组学员用传统的橡皮片、软质胶管为教具进行训练,实验组学员用新教具进行训练,共训练10 d,2 h/d;训练结束后,2组学员均以吻合小鼠颈动脉进行考核打分。通过问卷调查、考核成绩评估教具使用的实用性与教学效果。采用SPSS 19.0软件包对数据进行统计学处理。结果 成功研发出一套以3D打印水凝胶血管为核心,带有液体循环系统的新型显微外科训练教具。对10名教师的问卷结果显示,新教具在实用性、科学性方面优于传统教具,实验组学员的考核成绩显著高于对照组（P<0.05）。结论 基于3D打印水凝胶血管技术研发的仿真显微外科训练教具实用性强、成本低,教学效果优于传统教学模式,值得推广应用。     

Comparison of additive manufactured models of the mandible in accuracy and quality using six different 3D printing systems

The aim of this study was to analyze and compare the accuracy and quality of six 3D printing systems available on the market.Data acquisition was performed with 12 scans of human mandibles using an industrial 3D scanner and saved in STL format. These STL files were printed using six different printing systems. Previously defined distances were measured with a sliding caliper on the 72 printed mandibles. The printed models were then scanned once again. Measurements of volumes and surfaces for the STL files and the printed models were compared. Accuracy and quality were evaluated using industrial software. An analysis of the punctual aberration between the template and the printed model, based on a heat map, was also carried out. Secondary factors, such as costs, production times and expendable materials, were also examined.All printing systems performed well in terms of accuracy and quality for clinical usage. The Formiga P110 and the Form 2 showed the best results for volume, with average aberrations of 0.13 ± 0.23 cm³ and 0.12 ± 0.17 cm³, respectively. Similar results were achieved for the heat map aberration, with values of 0.008 ± 0.11 mm (Formiga P110) and 0.004 ± 0.16 mm (Form 2). Both printers showed no significant difference from the optimal neutral line (Formiga P110, p = 0.15; Form 2, p = 0.60). The cheapest models were produced by the Ultimaker 2+, with an average of 5€ per model, making such desktop printers affordable for rapid prototyping. Meanwhile, advanced printing systems with sterilizable and biocompatible printing materials, such as the Formiga P110 and the Form 2, fulfill the high expectations for maxillofacial surgery.     

Suitability of 3D printed pieces of nanocrystalline zirconia for dental applications

ObjectivesThe main goal of this work is to evaluate the suitability of nanostructured zirconia pieces obtained by robocasting additive manufacturing (AM), for dental applications.MethodsThe density, crystalline structure, morphology/porosity, surface roughness, hardness, toughness, wettability and biocompatibility of the produced samples were compared with those of samples obtained by conventional subtractive manufacturing (SM) of a similar commercial zirconia material. Chewing simulation studies were carried out against dental human cusps in artificial saliva. The wear of the material was quantified and the wear mechanisms investigated, as well as the influence of glaze coating.ResultsAM samples, that revealed to be biocompatible, are slightly less dense and more porous than SM samples, showing lower hardness, toughness and wettability than SM samples. After chewing tests, no wear was found both on AM and SM samples. However, the dental wear was significantly lower when AM samples were used as counterbody. Concerning the glazed samples, both coated surfaces and dental cusps suffered wear, being the cusps’ wear higher than that found for unglazed samples. More, cusps tested against AM coated samples suffered less wear comparatively to those opposed to SM coated samples.SignificanceOverall, the results presented in this paper show that AM processed nanostructured zirconia can be used in dental restorations, with important advantages from the point of view of processing and tribological performance. Moreover, the option for glaze finishing should be carefully considered both in SM and AM processed specimens.     

三维打印血管的研究进展

血管化作为骨、牙髓、皮肤等口腔颌面组织再生的关键,一直是组织工程研究的重点。随着三维(three-dimensional, 3D)打印在组织工程领域的发展,构建血管结构的方式逐渐增加。但要达到在形态及功能上高度模拟血管结构的目的,构建精度较高且具备生物功能的高仿真血管结构以促进组织修复仍是3D生物打印需要克服的一大难点。该文总结了三维打印血管结构的新进展,阐述了几种前沿生物制造技术即悬浮打印、同轴打印、4D打印等在构建血管及血管化结构中的应用,并分析和探讨其优缺点与应用前景,为三维打印血管在口腔颌面组织再生修复方面的应用提供参考。     

Fracture toughness of conventional,milled and 3D printed denture bases

ObjectivesThe aim of this study was to determine and compare fracture toughness (K_IC) and work of fracture (WOF) of a conventional (C) denture base, using the notchless triangular prism (NTP) specimen K_IC test, with CAD/CAM (milled, M) and 3D-printed (P) materials at 7 d and 90 d.MethodsLucitone 199 (C), Lucitone 199 CAD (M) and Lucitone Digital Print (P) (Dentsply, USA) were used to fabricate NTP specimens. Samples were stored in 37 °C water for 7 d (20/group) and 90 d (20/group) and conditioned in 23 °C water for 1 h prior to testing. For testing, samples were secured in custom-made jigs and loaded in tension until crack arrest/failure. The maximum-recorded load was used to calculate KIC. The results were analyzed by two-way ANOVA, Scheffé multiple mean comparisons (α = 0.05), independent t-tests and Weibull. WOF (in KJ/m²) was calculated by dividing the area under the load-displacement graphs by twice the corresponding crack-arrested cross sectional area of the fractured surfaces.ResultsThe results have shown that: 1) the tested materials had significantly different K_IC (P > C > M; p < 0.005) and WOF at both 7d and 90d; 2) ageing in 37 ºC water for 90 d resulted in a significant decrease of K_IC in the C and M groups (p < 0.001) and of WOF in all groups.SignificanceThe tested P denture base exhibited significantly higher K_IC and WOF, suggesting that it could be more resistant to crack propagation than the C and M materials tested. Water storage for 90 d significantly decreased K_IC of C and M materials and WOF of all.     

3D打印钴铬合金和铸造钴铬合金的理化性能和生物相容性的比较

目的 比较3D打印和传统铸造钴铬合金的理化性能及生物学影响.方法 实验组和对照组分别用3D打印技术中的选择性激光熔融(SLM)和传统铸造技术,制作钴铬合金试件各10个,采用洛氏硬度计HR-150A和金相显微镜对两组分别进行洛氏硬度测定和金相观察,并在自腐蚀电位下对金属试件进行极化曲线测定.在无菌环境下制备试件的浸提液,...     

3D打印定位导板在辅助制备股前外侧穿支皮瓣中的临床应用

目的:探讨采用3D打印固定式定位导板制取股前外侧穿支皮瓣中定位穿支血管的准确性和可行性。方法:收集2019年1月—2020年12月就诊于新疆医科大学第一附属医院/附属口腔医院口腔颌面肿瘤外科,因口腔颌面部软组织缺损需行股前外侧穿支皮瓣修复重建的患者20例。其中,实验组术前3D打印定位导板,术中定位穿支血管并辅助制取股前外侧穿支皮瓣(n=8);对照组采用常规多普勒超声定位穿支血管并辅助制取股前外侧穿支皮瓣(n=12)。比较2组在皮瓣制取时间、出血量、术后供区外形满意度、下肢功能评定量表(LEFS)评分、穿支血管定位、有无术后皮瓣并发症的差异。采用SPSS 24.0软件包对数据进行统计学分析。结果:皮瓣制取时间、出血量、术后供区外形满意度、定位穿支血管的差异有统计学意义(P<0.01);术后皮瓣并发症、LEFS评分差异无统计学意义(P>0.05)。结论:3D打印固定式定位导板为股前外侧穿支皮瓣穿支血管的定位提供了一种新方法,术中定位血管更准确,提高了手术效率以及患者对术后供区外形恢复的满意度。     

Initial biocompatibility of novel resins for 3D printed fixed dental prostheses

ObjectivesSeveral materials for 3D printing of fixed dental prostheses (FDP) have been recently introduced. This study aims to evaluate the initial biocompatibility of novel printable resins for manufacturing temporary and permanent FDP.MethodsSpecimens of five printable resins (VarseoSmile Crown plus, NextDent C&B MFH, VarseoSmile Temp, Temp PRINT, P Pro Crown & Bridge), two types of resins for subtractive manufacturing (Tetric CAD, Telio CAD) and two types of resins with conventional curing processes (Tetric EvoCeram, Protemp 4) were produced and finished. Post-processing was strictly performed according to the manufacturer’s protocol. Biocompatibility was evaluated by eluting specimens with cell culture medium and treating human gingival fibroblast cells with the eluates. A 72-hour continuous read cell viability assay measuring the reducing potential of the cells was performed. The cellular inflammatory response in terms of IL-6 and PGE₂ levels was determined with specific ELISAs. Oxidative stress was determined by measuring oxidized glutathione concentrations after exposure to the resin eluates. A luminescence-based apoptosis assay was used to detect apoptosis.ResultsTetric CAD and Telio CAD were slightly toxic. All other resins were moderately to severely cytotoxic. VarseoSmile Crown plus and P Pro Crown & Bridge significantly enhanced PGE₂ levels. Higher concentrations of oxidized gluthatione were determined in the presence of Telio CAD, VarseoSmile Temp and P Pro Crown & Bridge. Tetric EvoCeram and Protemp 4 reduced intracellular gluthatione levels. All printable resins slightly induced apoptosis.SignificanceFurther post-processing steps such as additional curing and washing may improve the biocompatibility of printable materials.     

Comparison of various 3D printed and milled PAEK materials: Effect of printing direction and artificial aging on Martens parameters

ObjectivesThe aim of this study was to investigate the effect of artificial aging on the Martens parameters of different 3D printed and milled polyaryletherketon (PAEK) materials.MethodsIn total 120 specimens of 4 different polyetheretherketon (PEEK) materials (Essentium PEEK, KetaSpire PEEK MS-NT1, VICTREX PEEK 450 G and VESTAKEEP i4 G) were additively manufactured via fused layer manufacturing (FLM) in either horizontal or vertical directions (n = 15 per group). 75 specimens were milled out of prefabricated PAEK blanks from the materials breCAM.BioHPP, Dentokeep, JUVORA Dental Disc 2 and Ultaire AKP ( = 15 per group). Martens hardness (HM), indentation hardness (H_IT) and indentation modulus (E_IT) were determined initially and longitudinally after thermocycling (5−55 °C, 10,000x) and autoclaving (134 °C, 2 bar). In each case, the surface topography of the specimens was examined for modifications using a light microscope.Data were analysed with Kolmogorov-Smirnov test, univariate ANOVA followed by post-hoc Scheffé test with partial eta squared (η_p²), Kruskal–Wallis-, Mann–Whitney-U-, Friedman- and Wilcoxon-Test. A value of p < 0.05 was considered as significant.ResultsMilled specimens showed higher Martens parameters than printed ones (p < 0.001). Artificial aging had a negative effect on the measured parameters (p < 0.001). Horizontally printed specimens presented higher Martens parameters than vertically printed ones, regardless of material and aging process (p < 0.001). Essentium PEEK and breCAM.BioHPP showed the highest and VICTREX PEEK 450G as well as Ultaire AKP the lowest values of all investigated PAEK materials initially, after thermocycling and after autoclaving (p < 0.001). Microscopic examinations showed that artificial aging did not cause any major modifications of the materials.SignificanceAdditively manufactured PEEK materials showed lower Martens parameters than milled ones, whereas horizontally printed specimens presented higher values than vertically printed ones. Artificial aging had a negative effect on the Martens parameters, but not on the surface topography.