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.     

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。     

Clinical application of 3D technology for tooth autotransplantation: A case report

This report presents two cases of tooth autotransplantation using cone‐beam computed tomography (CBCT), the three‐dimensional (3D) simulation dental planning software and a computer‐aided rapid prototyping (CARP) model. Two hopeless teeth of adult patients were replaced as their third molar teeth. Before deciding the autotransplantation, diagnostic CBCT images were acquired and imported to SimPlant software. The SimPlant dental program was used for surgical simulation prior to autotransplantation, which created 3D images of the available donor teeth and recipient site tooth and superimposed the images to display their morphological similarity. Efficient modification of the recipient socket was designed preoperatively. The CARP model of the donor tooth was prepared as a substitute for the donor tooth that would be fit into the new recipient socket during bone preparation. Autotransplantation was favourably performed in 5–6 min. Transplanted teeth healed up without clinical abnormality. The postoperative follow‐up time was up to 6 years.     

Cytotoxicity of 3D printed resin materials for temporary restorations on human periodontal ligament (PDL-hTERT) cells

ObjectivesVarious dental resin materials are available for the fabrication of temporary restorations using modern additive printing methods. Albeit these materials are placed for several months in intimate contact with dental hard and soft tissues, including the gingival crevice, there exists only insufficient evidence on the biocompatibility of these materials. This in vitro study aimed to delineate the biocompatibility of 3D printable materials on periodontal ligament cells (PDL-hTERTs).MethodsSamples of four dental resin materials for additive fabrication of temporary restorations using 3D printing (MFH, Nextdent; GC Temp, GC; Freeprint temp, Detax; 3Delta temp, Deltamed), one material for subtractive fabrication (Grandio disc, Voco) and one conventional temporary material (Luxatemp, DMG) were prepared with a standardized size according to the manufacturer’s instructions. Human PDL-hTERTs were exposed to resin specimens or eluates of the material for 1, 2, 3, 6 and 9 days. For determination of cell viability, XTT assays were performed. In addition, the expression of the proinflammatory cytokines interleukin 6 and 8 (IL-6 and 8) was assessed in the supernatants with ELISA. Cell viability and the expression of IL-6 and 8 in presence of the resin material or their eluates was compared with untreated controls. Immunofluorescence staining for IL-6 and IL-8, as well as scanning electron microscopy of the discs after culturing, were performed. Differences between groups were analyzed with Student´s t-test for unpaired samples.ResultsCompared to untreated control samples, the exposure against the resin specimen induced strong reduction of cell viability in case of the conventional material Luxatemp (p < 0.001) and the additive material 3Delta temp (p < 0.001) irrespective of the observation period. On the contrary, the presence of eluates of the various materials induced only minor changes in cell viability. Considering IL-6 (day 2: p = 0.001; day 6 and 9: p < 0.001) and IL-8 (day 1: p = 0.001; day 2, 3, 6, 9: p < 0.001) their expression was strongly reduced in presence of the eluate of Luxatemp. Except for IL-6 at day 1 and 6 also the material 3Delta temp caused significant reduction of both proinflammatory mediators at any time point.SignificanceThe conventional material Luxatemp and the additive material 3Delta temp appear to severely affect cell viability when in direct contact with PDL-hTERTs. The other tested materials of this new category of additive materials and the subtractive material Grandio seem to induce only minor changes in direct contact with these cells. Therefore, they could serve as a viable alternative in the fabrication of temporary restorations.     

基于锥形术CT数字化建模的3D打印牙颌模型制作及精确度研究

目的 基于锥形术CT（CBCT）数据构建患者数字化模型,应用3D打印技术制作牙颌实体模型并评估其精确度。方法 通过Mimics 10.01软件处理正畸临床患者CBCT数据,并结合Geomagic studio三维软件制作牙颌数字化模型,导入MakerBot Replicator2X型3D打印机中,采用熔融沉积技术（FDM）制作聚乳酸材料的上下颌实体模型。比较3D打印模型与传统石膏模型的牙冠近远中径、牙弓长度和宽度及后牙牙尖三角嵴长度测量值。结果 3D打印牙颌模型和传统石膏模型的测量数据经配对样本t检验,无统计学差异（P>0.05）。结论 采用CBCT构建数字化模型具有可行性,能够简化正畸检查流程、实现患者牙颌状况的数字化存储。采用3D打印制作牙颌模型精确度良好,可用于正畸临床。     

The influence of printing angle on color and translucency of 3D printed resins for dental restorations

ObjectivesTo evaluate the influence of printing orientation on color and translucency of 3D printing restorative resins.MethodsFour 3D printing resin systems in the available shades (DFT-Detax Freeprint Temp- A1, A2,A3; FP-Formlabs Permanent Crown- A2,A3,B1,C2; FT- Formlabs Temporary CB- A2,A3,B1,C2; GCT-GC Temporary- Light, Medium) were evaluated. Three samples (10×10×1.2 mm) from each material were printed at two different printing orientations (0° and 90°) and polished to 1.00 ± 0,01 mm of thickness. Spectral reflectance was measured against black background using a calibrated spectroradiometer, CIE D65 standard illuminant and the 45°/0°geometry. Color and translucency differences were evaluated using CIEDE2000 metric (ΔE₀₀) and 50:50% perceptibility (PT₀₀ and TPT₀₀) and acceptability (AT₀₀ and TAT₀₀) thresholds.ResultsIn general, color changes due to printing orientation at (0° and 90°) were mainly produced by ΔL* or ΔC* . ΔE₀₀ were above PT₀₀ for all DFT shades, FP-B1, FP-C2, FT-A2 and FT-B1. Only for DFT-1, ΔE₀₀ was above AT₀₀. ΔRTP₀₀ values were above TPT₀₀ for DFT-A1, DFT-A3, FP-B1 and FT-B1, but lower than TAT₀₀. The direction of the changes in translucency (ΔRTP₀₀) depends on the material and shade.SignificanceThe selection of building orientation (0° and 90°) for the 3D printed resins influence the visual color and translucency and therefore their esthetic appearance. These aspects should be considered when printing dental restorations using the evaluated materials.     

Description and evaluation of a new approach on pre‐clinical implant dentistry education based on an innovative simulation model

Introduction: Predominantly theoretical courses are employed to teach German dental students in implant dentistry at pre‐clinical stage. As implant dentistry is an important part of the clinical treatment spectra, practical implementation of this field at an early stage of education seems to be appropriate. By a newly developed interdisciplinary implant dentistry course, students should assess an improved competence level as well as first practical experiences in the field of implant dentistry at the pre‐clinical stage of their education. Materials and methods: Interdisciplinary implant dentistry education was integrated in the final pre‐clinical course Phantom II at the Department of Prosthodontics, LMU, Munich. In total 120 pre‐clinical students participated at the implant dentistry education course. After theoretical introduction into implant surgery and implant prosthetics, 30 simulation units were employed for the practical training of the participants. All important treatment steps were carried out by the students under instruction by the supervisors, including interdisciplinary planning, the use of the drilling template, the template guided insertion of two implants, as well as the integration of two ball attachments into a pre‐existing full denture. After the course participants were asked by questionnaire about the quality of the course and their personal opinion. Results: The course received an extraordinary positive feedback. In total 108 students evaluated the course with the overall grade of 1.68 according to the German school‐mark system (1 = excellent, 6 = unsatisfactory). Also the single parts of the course were voted constantly positively. Conclusion: The aim of this first interdisciplinary course for pre‐clinical students was to enhance competence level and practical implementation of implant dentistry at an early stage of education. Participants’ comments and suggestions on the questionnaires demonstrated the positive response and the general interest in this form of dental education, as well as the demand for further development of training in this field.