Morphological Design and Study of a 3D Printed Integrated Fusion Device Based on CT Measurement Data Assisted Anterior Lumbosacral Spine / Diseño Morfológico y Estudio de un Dispositivo de Fusión Integrado Impreso en 3D Basado en Datos de Medición de TC Asistida de Columna Lumbosacra Anterior

SUMMARY: To measure and study the anatomical morphological data of the lumbar 5 to sacral 1 intervertebral space with the aid of CT and design an anatomical anterior lumbosacral 3D printed integrated interbody fusion for the treatment of degenerative lumbosacral spine diseases. 100 adults (50 of each sex) who underwent CT examination of the lumbar spine in our hospital were selected, and their lumbar 5 to sacral 1 intervertebral space anatomical data were measured, including the anterior lumbar convexity angle, different sagittal and coronal heights, and the sagittal and coronal diameters of the superior and inferior endplates. The measured data were also statistically analyzed, and morphological design and study of the 3D printed integrated fusion device in the anterior lumbosacral spine was performed by applying computer software. When comparing the coronal and sagittal diameters of the superior and inferior endplates from lumbar 5 to sacral 1, the differences were statistically greater in men than in women (P0.001). When comparing the height at different positions in the median sagittal plane, both males and females showed an anterior high and posterior low pattern. In the coronal plane, both males and females showed the highest height in the middle position (P0.001). CT can measure the anatomical data of the lumbosacral spinal hiatus more accurately. The 3D-printed anterior integrated fusion device of the lumbosacral spine designed according to the analysis of the data results is more in line with the anatomical structure of the lumbosacral spine, fits well with the superior and inferior endplates, and effectively restores the height and anterior convexity angle of the lumbosacral space.

El objetivo de este trabajo fue medir y estudiar los datos morfológicos anatómicos del espacio intervertebral lumbar 5 a sacro 1 con la ayuda de TC y diseñar una fusión intersomática integrada anatómica lumbosacra anterior impresa en 3D para el tratamiento de enfermedades degenerativas de la columna lumbosacra. Se seleccionaron en nuestro hospital 100 adultos (50 de cada sexo) que se sometieron a un examen de TC de la columna lumbar y se midieron los datos anatómicos del espacio intervertebral lumbar 5 al sacro 1, incluyendo el ángulo de la convexidad lumbar anterior, diferentes alturas sagital y coronal, y los diámetros sagital y coronal de las placas terminales superior e inferior. Los datos medidos también se analizaron estadísticamente y se realizó el diseño morfológico y el estudio del dispositivo de fusión integrado impreso en 3D en la columna lumbosacra anterior mediante la aplicación de software informático. Al comparar los diámetros coronal y sagital de las placas terminales superior e inferior desde lumbar 5 hasta sacro 1, las diferencias fueron estadísticamente mayores en hombres que en mujeres (P 0,001). Al comparar la altura en diferentes posiciones en el plano mediano, tanto hombres como mujeres mostraron un patrón anterior alto y posterior bajo. En el plano coronal, tanto hombres como mujeres mostraron la altura más alta en la posición media (P0,001). La TC puede medir los datos anatómicos del hiato espinal lumbosacro con mayor precisión. El dispositivo de fusión anterior integrado impreso en 3D de la columna lumbosacra diseñado de acuerdo con el análisis de los resultados de los datos está más en línea con la estructura anatómica de la columna lumbosacra, se adapta bien a las placas terminales superior e inferior y restaura eficazmente la altura y la parte anterior del ángulo de convexidad del espacio lumbosacro.

Accuracy of Digital Impression Taking in Partial Dentures: an in Vitro Study on the Degree of Adaptation of Rests / Precisão da Tomada de Impressão Digital em Próteses Parciais: um Estudo in Vitro sobre o Grau de Adaptação de Apoios

The objective of the study is to assess the precision of digital impressions in removable partial dentures through an in vitro study on the degree of abutment adaptation. A Kennedy Class III model with a prosthetic space between elements 43 and 47, featuring niches in the mesio-occlusal and cingulum regions, respectively. Conventional impressions were performed in subgroups CONC and CONM, while digital scanning was conducted in subgroups DIGC and DIGM. Simplified cobalt-chromium alloy frameworks were manufactured using the lost-wax technique on plaster and resin models. The degree of adaptation of the structures was evaluated by impressing the niches with condensation silicone, qualitatively assessing perforations, and quantitatively measuring the mold thickness under a stereomicroscope after cross-sectioning. Regular adaptation was more prevalent among the experimental groups. CONC showed a higher mean degree of abutment adaptation, while CONM had a lower mean. The study factors, impression technique, and type of abutment seat, were not statistically significant, with no interaction among the variables. Occlusal and cingulum abutment measurement points, in both impression techniques, showed no statistically significant difference. Digital scanning yielded better results in terms of abutment adaptation, with smaller average gaps between the abutment seat and the metal structure, making it clinically acceptable. The type of abutment seat and the impression technique did not have a statistically significant impact on abutment adaptation. The impression technique does not represent a factor influencing the adaptation of occlusal and cingulum abutments at different measurement points. (AU)

O Objetivo do estudo é valiar precisão da impressão digital em próteses parciais removíveis, por meio de um estudo in vitro sobre o grau de adaptação dos apoios. Um modelo Classe III de Kennedy com espaço protético entre o elemento 43 e 47, nichos na região mésio-oclusal e na do cíngulo. Foram realizadas impressões convencionais nos subgrupos CONC e CONM, e digitalização nos subgrupos DIGC e DIGM, onde estruturas simplificadas de liga de Co-Cr foram fabricadas usando a técnica de fundição perdida nos modelos de gesso e resina. O grau de adaptação das estruturas foi avaliado pela impressão dos nichos com silicone de condensação, qualitativamente as perfurações e quantitativamente a espessura do molde em um estereomicroscópio após seção transversal. A adaptação regular foi mais prevalente entre os grupos experimentais. CONC maior média do grau de adaptação do apoio, enquanto CONM menor média. Os fatores do estudo, técnica de impressão e tipo de assento de apoio, não foram estatisticamente significativos, sem interação entre as variáveis. Pontos de medição de apoio oclusal e de cíngulo, em ambas as técnicas de impressão, sem diferença estatisticamente significativa. A digitalização mostrou melhores resultados em relação ao grau de adaptação dos apoios, com menores lacunas médias entre o assento de apoio e a estrutura metálica, sendo clinicamente aceitável. O tipo de assento de apoio e a técnica de impressão não interferem estatisticamente na adaptação dos apoios. A técnica de impressão não representa um fator que influencie a adaptação de apoios oclusais e de cíngulo em diferentes pontos de medição. (AU)

Evaluación de Protocolos de Autotrasplante Dental Guiado y sus Tasas de Supervivencia y Éxito. Una Revisión Sistemática

Actualmente los factores que influyen en la supervivencia de los dientes trasplantados han podido ser controlados con el uso de la tecnología. El autotrasplante dental guiado ha logrado más predictibilidad y eficiencia, además, h a reducido los tiempos de transferencia desde la extracción hasta el trasplante. El objetivo de esta revisión es describir los protocolos de autotrasplante dental guiado, sus tasas de supervivencia y éxito publicados en la literatura actual. Esta revisió n fue realizada siguiendo la pauta PRISMA. La búsqueda se realizó en MEDLINE, Google Académico, ScienceDirect y SciELO, con los términos "autotransplant", "autotransplantation", "autotransplanting", "dental", "tooth", "teeth", "guided", "guide" con filtro de publicación de 10 años. Se realizó evaluación de riesgo de sesgo mediante pautas Joanna Briggs Institute (JBI) a los estudios, incluyendo en esta revisión sólo con riesgo medio y bajo. Los datos de cada artículo se tabularon en una tabla realizada en el procesador de texto en línea "Google Docs". Diez estudios cumplieron los criterios mencionados y fueron incluidos. Fueron evaluados un total de 37 pacientes entre 9 a 64 años. Los dientes donantes más frecuentes fueron premolares y terceros molares. En la mayoría de los casos los pacientes se encontraban sin antecedentes mórbidos de relevancia. El éxito fue evaluado mediante diversos criterios clínicos y radiográficos. Por otro lado, la supervivencia fue evaluada durante los seguimientos respecto a la permanencia del diente en boca. Este tipo de tratamiento no es muy conocido y los estudios incluidos fueron escasos, por otro lado, estos son de bajo nivel de evidencia (reportes de casos y serie de casos). Los protocolos evaluados difieren en algunas características, sin embargo, todos logran altas tasas de supervivencia y éxito. Igualmente, se presentan algunos fracasos, dónde los dientes debieron ser extraídos por movilidad e inflamación.

Currently, the factors that influence the survival of transplanted teeth have been controlled with the use of technology. Guided dental autotransplantation has achieved greater predictability and efficiency, and has also reduced transfer times from extraction to transplantation. The aim of this review is to describe the protocols of guided dental autotransplantation, their survival and success rates published in the current literature. This review was performed following the PRISMA guideline. The search was carried out in MEDLINE, Google Scholar, ScienceDirect and SciELO, with the terms "autotransplant", "autotransplantation", "autotransplanting", "autotransplanting", "dental", "tooth", "teeth", "guided", "guide" with a 10-year publication filter. Studies were assessed for risk of bias using Joanna Briggs Institute (JBI) guidelines, including only medium and low risk studies in this review. The data for each article were tabulated in a table created in the online word processor "Google Docs". Ten studies met the selection criteria and were included. A total of 37 patients between 9 and 64 years of age were evaluated. The most frequent donor teeth were premolars and third molars. In most cases the patients had no relevant morbid history. Success was evaluated by means of various clinical and radiographic criteria. On the other hand, survival was evaluated during the follow-ups with respect to the permanence of the tooth in the mouth. This type of treatment is not very well known, and the studies included were scarce; on the other hand, they are of a low level of evidence (case reports and case series). The evaluated protocols differ in some characteristics, however, all of them achieve high survival and success rates. There are also some failures, where teeth had to be extracted due to mobility and inflammation.

Improved unilateral puncture PVP based on 3D printing technology for the treatment of osteoporotic vertebral compression fracture / 中国骨伤

OBJECTIVE@#To investigate the clinical effect of unilateral percutaneous vertebroplasty (PVP) combined with 3D printing technology for the treatment of thoracolumbar osteoporotic compression fracture.@*METHODS@#A total of 77 patients with thoracolumbar osteoporotic compression fractures from October 2020 to April 2022 were included in the study, all of which were vertebral body compression fractures caused by trauma. According to different treatment methods, they were divided into experimental group and control group. Thirty-two patients used 3D printing technology to improve unilateral transpedicle puncture vertebroplasty in the experimental group, there were 5 males and 27 females, aged from 63 to 91 years old with an average of (77.59±8.75) years old. Forty-five patients were treated with traditional bilateral pedicle puncture vertebroplasty, including 7 males and 38 females, aged from 60 to 88 years old with an average of(74.89±7.37) years old. Operation time, intraoperative C-arm X-ray times, anesthetic dosage, bone cement injection amount, bone cement diffusion good and good rate, complications, vertebral height, kyphotic angle (Cobb angle), visual analogue scale(VAS), Oswestry disability index (ODI) and other indicators were recorded before and after surgery, and statistically analyzed.@*RESULTS@#All patients were followed up for 6 to 23 months, with preoperative imaging studies, confirmed for thoracolumbar osteoporosis compression fractures, two groups of patients with postoperative complications, no special two groups of patients' age, gender, body mass index (BMI), time were injured, the injured vertebral distribution had no statistical difference(P>0.05), comparable data. Two groups of patients with bone cement injection, bone cement dispersion rate, preoperative and postoperative vertebral body height, protruding after spine angle(Cobb angle), VAS, ODI had no statistical difference(P>0.05). The operative time, intraoperative fluoroscopy times and anesthetic dosage were statistically different between the two groups(P<0.05). Compared with the traditional bilateral puncture group, the modified unilateral puncture group combined with 3D printing technology had shorter operation time, fewer intraoperative fluoroscopy times and less anesthetic dosage. The height of anterior vertebral edge, kyphosis angle (Cobb angle), VAS score and ODI of the affected vertebrae were statistically different between two groups at each time point after surgery(P<0.05).@*CONCLUSION@#In the treatment of thoracolumbar osteoporotic compression fractures, 3D printing technology is used to improve unilateral puncture PVP, which is convenient and simple, less trauma, short operation time, fewer fluoroscopy times, satisfactory distribution of bone cement, vertebral height recovery and kyphotic Angle correction, and good functional improvement.

Clinical outcomes of 3D-printing stand-alone artificial vertebral body in anterior cer-vical surgeries / 北京大学学报(医学版)

Objective:To explore the short-term outcomes of 3D-printing stand-alone artificial vertebral body(AVB)in the surgical procedure of anterior cervical corpectomy and fusion(ACCF).Methods:Following the proposal of IDEAL(idea,development,exploration,assessment,and long-term follow-up)framework,we designed and conducted this single-armed,retrospective cohort study.The patients with cervical spondylotic myelopathy were recruited,and these patients exclusively received the surgical procedure of single-level ACCF in our single center.After the process of corpectomy,the size was tailored using different trials and the most suitable stand-alone AVB was then implanted.This AVB was manufactured by the fashion of 3D-printing.Two pairs of screws were inserted in an inclined way into the adjacent vertebral bodies,to stabilize the AVB.The participants were regularly followed-up after the operation.Their clinical data were thoroughly reviewed.We assessed the neurological status according to Japanese Orthopedic Association(JOA)scale.We determined the fusion based on imaging examination six months after the operation.The recorded clinical data were analyzed using specific software and they presented in suitable styles.Paired t test was employed in comparison analysis.Results:In total,there were eleven patients being recruited eventually.The patients were all followed up over six months after the operation.The mean age of the cohort was(57.2±10.2)years.The mean operation time was(76.1±23.1)min and the median bleeding volume was 150(100,200)mL.The postoperative course was uneventful for all the cases.Dysphagia,emergent hematoma,and deterioration of neurological func-tion did not occur.Mean JOA scores were 13.2±2.2 before the operation and 16.3±0.8 at the final follow-up,which were significantly different(P＜0.001).The mean recovery rate of neurological func-tion was 85.9％.By comparing the imaging examinations postoperatively and six months after the opera-tion,we found that the average subsidence length was(1.2±1.1)mm,and that there was only one ca-ses(9.1％)of the severe subsidence(＞3 mm).We observed significant improvement of cervical lor-dosis after the operation(P=0.013).All the cases obtained solid fusion.Conclusion:3D-printing stand-alone AVB presented favorable short-term outcome in one-level ACCF in this study.The fusion rate of this zero-profile prosthesis was satisfactory and the complication rate was relatively low.

Effect of printing orientation on physical and mechanical properties of 3D printing prosthodontic base resin materials / 北京大学学报(医学版)

Objective:To analyze the influence of forming direction on the surface characteristics,elastic modulus,bending strength and fracture toughness of printed parts and the relationship between forming direction and force direction,and to provide scientific basis and guidance for the clinical applica-tion of oral denture base resin materials.Methods:The 3D printing technology was used to print denture base resin samples.The shape and size of the samples referred to the current standard for testing conven-tional denture base materials.The samples used for physical performance testing were cylindrical(with a diameter of 15 mm and a thickness of 1 mm)and printed at different angles along the Z axis(0°,45°,90°).Scanning electron microscope was used to observe the microscopic topography of the different sam-ples.The color stability of different samples was observed by color stabilizer.The surface roughness of the samples was analyzed by using surface roughness tester.The Vickers hardness was measured to ana-lyze the hardness of the samples.The samples used for mechanical performance testing were rectangular(elastic modulus and bending strength:A length of 64 mm,a width of 10 mm,and a height of 3.3 mm;fracture toughness:A length of 39 mm,a width of 8 mm,and a height of 4 mm),divided into two groups:W group and H group.The W group was printed from the bottom up along the Z axis with the length × width as the bottom surface parallel to the X,Y axis plane,while the H group printed from the bottom up along the Z axis with the length × height as the bottom surface parallel to the X,Y axis plane.The forming angles of both groups were equally divided into 0°,45°,and 90°.The elastic modulus,bending strength and fracture toughness of different samples were studied through universal mechanical testing machine.SPSS 22.0 software was used for statistical analysis.Results:The microscopic topogra-phy and roughness of different samples were closely related to the printing direction,with significant differences between the 0°,45°,and 90° specimens.The 0° specimens had the smoothest surface(roughness＜1 μm).The surface of the 45 ° specimen was the roughest(roughness＞3 μm).The microhardness of the 0° sample was the best[(196.13±0.20)MPa],with a significant difference com-pared with the 90° sample[(186.62±4.81)MPa,P＜0.05].The mechanical properties of different samples were also closely related to the printing direction.The elastic modulus,bending strength,and fracture toughness of the 45° samples in the W group were the highest compared with the other groups.The results of elastic modulus showed that in the H group,the 45° specimens had the highest elastic mo-dulus,which was significantly different from the 0° and 90° specimens(P＜0.05).The elastic modulus of 0° and 45° specimens in the W group were higher than those in 90° specimens(P＜0.05).The bending strength results showed that there was no significant difference between the specimens from dif-ferent angles in the H group.The bending strength of the 90° specimens in the W group was the smallest,and there was a significant difference between 90° and the 0° and 45° specimens(P＜0.05);And the bendind strength of the 0° and 45° specimens in the W group was significantly higher than that of the 0° and 45° specimens in the H group(P＜0.05).The fracture toughness results showed that the fracture toughness of the H group specimens was lower than 1.9 MPa m1/2,which was specified in the denture base standard.The 45° samples in the W group were the highest,with significant differences compared with the 0° and 90° samples(P＜0.05).And the 90° samples of the W group specimens were lower than 1.9 MPa m1/2.And the fracture toughness of the 45° specimen in the W group was significantly higher than that of all the specimens in the H group(P＜0.05).Conclusion:The 0° samples had rela-tively better physical properties.The 45° samples had the best mechanical properties.But the fracture toughness of specimens(H group and 90° samples of W group)did not yet meet clinical requirements.That indicated that the characteristics of the 3D printing denture base resin were affected by the printing direction.Only when the performance of the printed samples in all directions met the minimum require-ments of the standard,they could be used in clinical practice.

Advances in the complications related to transcatheter closure of patent ductus arteriosus in children / 国际儿科学杂志

Patent ductus arteriosus（PDA）is one of the most common congenital heart diseases in childhood.The prevalence of PDA is about 0.5% and PDA accounts for 5%-10% of congenital heart diseases. Continuous opening of the ductus arteriosus can affect children's growth and development. Meanwhile，PDA increases the possibility of pneumonia，infective endocarditis，neonatal necrotizing enterocolitis，and other diseases.Compared with traditional surgery，percutaneous interventional closure of PDA in children has a higher surgical success rate and shorter hospital stay. Clinical practice has proved that percutaneous interventional closure is the preferred method for children with PDA. However，transcatheter closure also has complications，including displacement，valvular regurgitation，hemolysis and thrombocytopenia. The review aims to illustrate the mechanism and treatment of the complications after PDA interventional closure，in order to increase the physician's awareness of those complications，reduce the incidence of the complications and improve the prognosis of the patients.

Application of multiplanar reconstruction and 3D printing in anterior cruciate ligament revision / 中南大学学报(医学版)

Objective:Anterior cruciate ligament injury is the most common type of knee joint ligament injury.Anterior cruciate ligament reconstruction has a high failure rate,with bone tunnel abnormalities as the most significant factor in these failures.Digital orthopedic technology can effectively develop implementation plans for the revision,thus increasing the success rate.This study aims to develop a surgical plan for anterior cruciate ligament revision by employing multiplanar reconstruction(MPR)for measuring bone tunnel position and diameter,and simulating bone tunnel creation via 3D printing preoperatively. Methods:A total of 12 patients who underwent anterior cruciate ligament revision at the Third Xiangya Hospital of Central South University between 2014 and 2021 were retrospectively studied.The data included patient demographics,preoperative formulated knee joint 3D printing models,and preoperative knee CT scans.The study measured the bone tunnel's diameter and position to guide the establishment of revision bone tunnels during surgery,reassessed the postoperative bone tunnels,and evaluated knee joint functional scores[including International Knee Documentation Committee Knee Evaluation Form(IKDC)score,Lysholm score,and Tegner exercise level score]. Results:Preoperative measurements revealed suboptimal femoral tunnels positions in 4 patients and tibial tunnels positions in 2 patients.MPR and 3D printing technology were used to guide the establishment of a new bone canal during surgery,and postoperative measurements were satisfactory for all patients.Preoperative measurements demonstrated the interclass correlation coefficient for femoral tunnels and tibial tunnels diameters were 0.843(P<0.05)and 0.889(P<0.001),respectively.Meanwhile,the intraclass correlation coefficient were 0.811(P<0.05)and 0.784(P<0.05),respectively.The intraoperative diameter of femoral and tibial tunnels showed excellent correlation with postoperative CT measurements,with intraclass correlation coefficient values of 0.995(P<0.001)and 0.987(P<0.001),respectively.All bone tunnel positions were within the normal range.At the final follow-up,knee joint function scores in all 12 patients improved significantly compared to pre-surgery(P<0.001),and the reoperation rate was zero. Conclusion:MPR and 3D printing technology can accurately measure the parameters of reconstructed anterior cruciate ligament bone tunnels.Personalized revision plans for patients with reconstruction failure enhances the success rate of revision surgery and improves patient prognosis.

Application Effect of A New Modified 3D PSI in Total Knee Arthroplasty for Knee Osteoarthritis / 昆明医科大学学报

Objective To explore the application effect of new improved 3D printing individualized guidance(3D psi)in total knee arthroplasty(TKA)for knee osteoarthritis(KOA).Methods A total of 100 patients with KOA in 920th Hospital of Joint Logistics Support Force,PLA from January 2021 to January 2022 were selected,and were divided into 2 groups of 50 patients each using the randomized numerical table method.The control group was treated with conventional TKA,and the study group was treated with new improved 3D psi assisted TKA.The operation conditions,postoperative rehabilitation,complications,prosthesis component position deviation,knee range of motion(ROM),lower limb force line parameters[coronal distal femoral mechanical axis lateral angle(mldfa),lower limb mechanical axis angle(HKA)],gait parameters(percentage of support time,stride,pace),knee function(HSS score),quality of life(AIMS2 score)were observed.Results Com-pared with control group,the amount of intraoperative and postoperative blood loss and drainage volume 2 days after operation were less in the study group,and the operation time and hospital stay were shorter(P<0.05).The deviations of LTC Angle,FFC Angle,HKA Angle,LFC Angle and FTC Angle in the study group were smaller than those in the control group(P<0.05).At 3 months,6 months and 12 months after surgery,the percentage of knee ROM,supporting time,stride length and walking speed of the research group were higher than those of the control group,while the coronal-position mLDFA and HKA were lower than those of the control group(P<0.05).The proportion of WBC and PMN in joint fluid at 3 months,6 months and 12 months after surgery was lower than that in control group(P<0.05).The HSS score of the study group was higher than that of the control group at 3 months,6 months and 12 months after operation,and the AIMS2 score was lower than that of the control group(P<0.05).There was no statistically significant difference in the incidence of complications between the study group and the control group(P>0.05).Conclusion The new improved 3D PSI-assisted TKA treatment of KOA can optimize the surgical situation,improve operating accuracy,improve the patient's lower limb alignment,promote limb function recovery,help improve the quality of life,and has high safety.

Application and accuracy assessment of a novel 3D-printed osteotomy guide in anterior maxillary segmental distraction osteogenesis / 上海交通大学学报（医学版）

Objective·To evaluate the effects of anterior maxillary segmental distraction osteogenesis(AMSDO)in treating sagittal maxillary hypoplasia in cleft lip and palate(CLP)patients and to report a 3D-printed surgical guide to facilitate the osteotomy.Methods·Twelve patients with CLP who underwent AMSDO were included in this study.Virtual osteotomy was performed in a 3-dimensional model and the osteotomy line were fabricated into a tooth-borne surgical guide by using 3D-printing technique.Lateral cephalograms taken before surgery(T0),at the end of consolidation(T1)and six months after consolidation(T2)were used to evaluate the effects of AMSDO.The accuracy of the osteotomy guide was measured by superimposing the postoperative CT data to virtual planning.Results·All the patients went through surgery without serious complications.SNA and overjet changed significantly both from T0 to T1 and from T0 to T2.ANB,facial convexity,and palatal length changed without significance from T0 to T1 and from T0 to T2.SNB remained stable.All the variables remained relatively stable from T1 to T2.The anteroposterior linear root-mean-square deviation(RMSD)between planning and actual results was 0.90 mm,while the angular RMSD in the sagittal plane was 5.07°.Conclusion·AMSDO is an effective treatment for maxillary hypoplasia secondary to CLP.The accuracy of this 3D-printed osteotomy guide is clinically acceptable,and this can simplify the surgery with fewer complications.

Advances of the application of 3D printing technology in dental teaching models / 实用口腔医学杂志

With the development of digital technology,computer-aided design and manufacturing(CAD/CAM)combined with 3D printing technology is increasingly used in clinical and teaching applications in dentistry.In clinical dentistry,3D printing technology has been widely used in oral and maxillofacial surgery,orthodontics and implantation.Traditional oral laboratory teaching usually uses extracted teeth,resin teeth or various dental models,while 3D printing of oral models can achieve standardized,mass-produced and close-to-real clinical application,which better meets the needs of clinical pre-practice teaching.This article reviews the latest educa-tional applications of 3D printing of dental models in teaching of oral restoration,dental pulp-cavity,oral and maxillofacial surgery,and summarizes the selection of different printing processes and printing materials,aiming to apply the research strategy of 3D printing technology in pre-clinical teaching in dentistry.Finally,the article explores the trends and urgent problems that need to be solved in the development of 3D printed dental models.

Research advances in the accuracy of 3D printing prosthesis / 实用医学杂志

Prosthodontic dentures are used to treat tooth defects,dentition defects and dentition loss,which can restore the appearance and function of the patient's oral cavity.With the advent of the digital age,3D printing technologies have slowly gained widespread popularity.In the field of prosthodontics,3D printing can manufacture materials including resins,waxes,metals,and ceramics.Besides,it can produce fixed,movable,implant dentures and dental models required for dentures.3D printing can produce complicated things with a high material consump-tion rate,simplifying denture manufacture.In addition,the accuracy of 3D printed prosthesis is directly related to the comfort and durability.This article summarizes the process of accuracy of 3D printed dental prosthesis at home and abroad in recent years and provides clues for better 3D printing application.

Construction methods and application of assembloids / 中国组织工程研究

BACKGROUND:In recent years,many studies have confirmed that assembloids can make up for the shortcomings of organoids,which cannot fully reproduce the interaction between cell and cell and between cell and matrix.Since the assembloids construction methods are in the early stage of development,there is no unified standard. OBJECTIVE:To review the current construction methods,applications,advantages,and disadvantages of assembloids,guide the development and improvement of vitro cell models. METHODS:PubMed,CNKI,and WanFang databases were searched with English search terms"assembloids,organoids,tumor microenvironment,organoids AND assemble,organoids AND microenvironment"and Chinese search terms"assembloids,organoids,tumor microenvironment,organoid reorganization,multicellular model".Totally 94 articles were screened out for review after excluding irrelevant articles and deduplication. RESULTS AND CONCLUSION:(1)According to the different sources of cells,the construction of assembloids can be divided into three methods:self-assembly,direct-assembly,and mixed-assembly.According to the differences of cell culture methods,it can be divided into suspension culture method,matrix culture method,organ chip culture method,and 3D bio-printing.(2)The process of self-assembly covers early stages of cell and tissue development,so it has broad prospects in the fields of organ development and developmental disorders.The function of differentiated mature cells is relatively perfect,and the assembloids directly assembled by them have more potential in the study of functional disorders and cell-damaging diseases.Self-assembly may be better in organ transplantation,and direct-assembly will be more suitable for the repair of tissue damage.Mixed-assembly combines the advantages of the former two and is mostly used to explore the physiological and pathological mechanisms of cells in the microenvironment,as well as drug screening.(3)Although different assembloids have their own advantages,they all face the problem of imperfect vasculature system,then,each method has its own limitations,for example,the degree of cell differentiation in self-assembly assembloids may still be different from that in vivo,and the fixed cell types in direct-assembly models cannot simulate complex microenvironments in vivo.These are urgent problems to be solved.(4)In the future,with the continuous improvement of assembloids culture technology,scientists can assemble biomimetic organoids with more complex tissues in vitro,providing infinitely realistic models for the study of physiological and pathological processes of human tissue and organ.

3D printing process of gelatin/oxidized nanocellulose skin scaffold with high elastic modulus and high porosity / 中国组织工程研究

BACKGROUND:In the treatment of skin trauma with active repair,tissue engineering techniques are needed to generate new tissue to replace necrotic tissue.Skin scaffolds have a good application prospect in the field of wound repair.Skin scaffolds need to present three-dimensional porous structures with certain mechanical strength to meet the needs of cell proliferation and division.However,the mechanical strength of the currently used gelatin-based biomaterials is weak and cannot meet the requirements of the use of skin scaffolds. OBJECTIVE:To study the 3D printing process used in the preparation of tissue engineering skin scaffolds by gelatin/oxidized nanocellulose composites,and focus on the relationship between the porosity and mechanical strength of the scaffolds prepared under different process parameters. METHODS:Oxidized nanocellulose whiskers at 10%concentration were extracted from Humulus scandens and then compounded with 5%gelatin to obtain gelatin/oxidized nanocellulose composites.The elastic modulus of gelatin and gelatin/oxidized nanocellulose composite was determined.Skin scaffolds were prepared by 3D printing extrusion molding using gelatin/oxidized nanocellulose composite as the base material.Mechanical and rheological properties of the composite were tested to determine extrusion molding parameters(filling gap 1.5-2.5 mm,uniform distribution of 0.1 mm;air pressure of 160-200 kPa),and the skin scaffold with a three-dimensional porous structure was prepared.The compressive performance of the skin scaffold was tested and compared with the finite element analysis results.The relationship between the filling gap and the porosity and mechanical strength of the scaffold was demonstrated. RESULTS AND CONCLUSION:(1)The elastic modulus of 5%gelatin was increased by 8.84 times by adding 10%oxidized nanocellulose whisker.A gel filament with a diameter of 1 mm was obtained by extrusion at the air pressure of 160 kPa.When the filling gap increased from 1.5 mm to 2.5 mm,the theoretical porosity of the scaffold increased from 33%to 60%,but the compressive strength decreased from 230 000 Pa to 95 000 Pa.(2)These findings showed that the skin scaffold with theoretical porosity of 50%and elastic modulus of 160 000 Pa was prepared by using 2 mm filling gap.The scaffold had a clear three-dimensional porous structure.

Application of bio-inks for 3D printing in tissue repair and regenerative medicine / 中国组织工程研究

BACKGROUND:With the right bio-inks,3D printing can be used to create replacements for human tissues and organs that work inside the body.In recent years,3D printing technology has developed rapidly and has great application potential in regenerative medicine. OBJECTIVE:To introduce the types of bio-inks for 3D printing,and review the classification,application,advantages and disadvantages of bio-inks,as well as the future vision. METHODS:With"3D printing,biological ink,tissue engineering,hydrogel,synthetic material,cytoactive factor"as search terms,relevant articles published on PubMed and CNKI databases from 2000 to 2022 were searched by computer and finally 83 articles were included for review. RESULTS AND CONCLUSION:3D bioprinting technology has developed rapidly over the past few decades and has received great attention in various fields,including tissue engineering and biomedicine.Compared with the limitations of traditional biological scaffold manufacturing methods in terms of function and structure,3D printing can better simulate the complex structure of biological tissues and has appropriate mechanical,rheological and biological characteristics.Bio-ink is an essential part of 3D printing.Bioscaffolds produced by printing bio-ink prepared by biological materials have great scientific potential and clinical significance in tissue repair and regenerative medicine.The research of the materials itself is also getting more and more attention from experts.Bio-inks for 3D printing come in a variety of materials,from natural to synthetic,to aggregations of cells that do not require any additional biomaterials,and their usefulness in practical use varies.In the future,more and more bio-inks will be developed for tissue engineering.It is necessary to analyze the printability of bio-inks through sufficient experimental simulation and equipment testing to meet the actual medical needs.

Biological scaffold materials and printing technology for repairing bone defects / 中国组织工程研究

BACKGROUND:In recent years,with the development of biological scaffold materials and bioprinting technology,tissue-engineered bone has become a research hotspot in bone defect repair. OBJECTIVE:To summarize the current treatment methods for bone defects,summarize the biomaterials and bioprinting technology for preparing tissue-engineered bone scaffolds,and explore the application of biomaterials and printing technology in tissue engineering and the current challenges. METHODS:Search terms were"bone defect,tissue engineering,biomaterials,3D printing technology,4D printing technology,bioprinting,biological scaffold,bone repair"in Chinese and English.Relevant documents published from January 1,2009 to December 1,2022 were retrieved on CNKI,PubMed and Web of Science databases.After being screened by the first author,high-quality references were added.A total of 93 articles were included for review. RESULTS AND CONCLUSION:The main treatment methods for bone defects include bone transplantation,membrane-guided regeneration,gene therapy,bone tissue engineering,etc.The best treatment method is still uncertain.Bone tissue engineering technology is a new technology for the treatment of bone defects.It has become the focus of current research by constructing three-dimensional structures that can promote the proliferation and differentiation of osteoblasts and enhance the ability of bone formation.Biological scaffold materials are diverse,with their characteristics,advantages and disadvantages.A single biological material cannot meet the demand for tissue-engineered bone for the scaffold.Usually,multiple materials are combined to complement each other,which is to meet the demand for mechanical properties while taking into account the biological properties of the scaffold.Bioprinting technology can adjust the pore of the scaffold,build a complex spatial structure,and is more conducive to cell adhesion,proliferation and differentiation.The emerging 4D printing technology introduces"time"as the fourth dimension to make the prepared scaffold dynamic.With the synchronous development of smart materials,4D printing technology provides the possibility of efficient repair of bone defects in the future.

Vascularized tracheal substitutes constructed by exosome-load hydrogel-modified 3D printed scaffolds / 中国组织工程研究

BACKGROUND:For the replacement treatment of long-segment tracheal defects,although tissue engineering research has made some progress in recent years,it is still not perfect,and one of the biggest difficulties is that the hemodynamic reconstruction of the tracheal replacement cannot be achieved rapidly. OBJECTIVE:To preliminarily explore the potential of polycaprolactone scaffolds modified with exosome-loaded hydrogels to construct a rapidly vascularized tracheal substitute. METHODS:Exosomes were extracted from bone marrow mesenchymal stem cells of SD rats.After preparation of hyaluronic acid methacrylate solution,the exosome solution was mixed with hyaluronic acid methacrylate solution at a volume ratio of 1:1.Hyaluronic acid methacrylate hydrogels loaded with exosomes were prepared under ultraviolet irradiation for 5 minutes.The degradation of exosome-unloaded hydrogels and the controlled release of exosome-loaded hydrogels were detected.Polycaprolactone scaffolds were prepared by 3D printing.The pure hyaluronic acid methacrylate solution and the exosome-loaded hyaluronic acid methacrylate solution were respectively added to the surface of the scaffold.Hydrogel-modified scaffolds and exosome-modified scaffolds were obtained after ultraviolet irradiation.Thirty SD rats were randomly divided into three groups with 10 rats in each group and subcutaneously implanted with simple scaffolds,hydrogel-modified scaffolds and exosome-modified scaffolds,respectively.At 30 days after surgery,the scaffolds and surrounding tissues of each group were removed.Neovascularization was observed by hematoxylin-eosin staining and Masson staining and the expression of CD31 was detected by immunofluorescence. RESULTS AND CONCLUSION:(1)As time went by,the hydrogel degraded gradually,and the exosomes enclosed in the hydrogel were gradually released,which could be sustained for more than 30 days.The exosome release rate was faster than the degradation rate of the hydrogel itself,and nearly 20%of the exosomes were still not released after 30 days of soaking.(2)Under a scanning electron microscope,the surface of the simple polycaprolactone scaffold was rough.After hydrogel modification,a layer of gel was covered between the pores of the scaffold,and the scaffold surface became smooth and dense.(3)After 30 days of subcutaneous embedding,hematoxylin-eosin staining and Masson staining showed that more neovascularization was observed inside the scaffolds of the exosome-modified scaffold group compared with the hydrogel-modified scaffold group.The hydrogels on the scaffolds of the two groups were not completely degraded.Immunofluorescence staining showed that CD31 expression in the exosome-modified scaffold group was higher than that in the hydrogel-modified scaffold group(P<0.000 1).(4)These results indicate that hyaluronic acid methacrylate hydrogels can be used as controlled-release carriers for exosomes.The 3D-printed polycaprolactone scaffold modified by hyaluronic acid methacrylate hydrogel loaded with exosomes has good biocompatibility and has the potential to promote the formation of neovascularization.

Finite element analysis on correction effect of varus foot orthosis based on the three-point force principle / 中国组织工程研究

BACKGROUND:Three-point mechanics is an effective method for ankle foot orthosis correction and prevention of various foot diseases.At present,the clinical application research on 3D printing ankle foot orthosis has been widespread;however,there are relatively few reports on numerical simulation and finite element analysis involving three-point mechanical correction.There is a lack of relevant biomechanical experimental verification. OBJECTIVE:Three-point force was loaded to analyze the composite model of ankle foot orthosis and foot by finite element method,observing the effect of foot correction with ankle foot orthosis under three-point force intervention,verifying the effectiveness of three-point force and the reliability of ankle foot orthosis. METHODS:A three-dimensional foot and ankle model of a healthy volunteer was constructed based on the medical image processing software Mimics.Rodin 4D and Geomagic reverse engineering software were used to optimize the models and design personalized ankle foot orthosis models.Solidworks software was utilized to turn the ankle model inside for 10° to simulate the foot varus disease.Static loading was carried out on the foot force application area by ANSYS software combined with the three-point mechanics principle.The deformation and stress changes of the foot and ankle tissues were analyzed when the human foot pain threshold was met.The display dynamics was used to further verify the effectiveness of the three-point force applied by the ankle foot orthosis. RESULTS AND CONCLUSION:(1)The personalized ankle foot orthosis designed in this paper had the effect of preventing and fixing foot and ankle varus.The ankle varus was 1.81 mm after being loaded with 1 N·m of varus when not wearing ankle foot orthosis,while it was only 0.44 mm after wearing ankle foot orthosis,the deformation rate was reduced by 75.7%,and the effect of preventing varus was significantly enhanced.(2)When only coronal correction was performed,the low calcaneal force would aggravate the varus angle of the front foot.After adjusting the correction force on the inside of the heel and above the medial malleolus,the varus angle of the front foot and the calcaneus position were improved;however,the medial phalangeal region of the foot still had different degrees of adduction and displacement,which would aggravate the adduction deformity of the patient's front foot.(3)The correction effect of the coronal plane and horizontal plane was better than that of the single coronal plane.There was no adduction and displacement of the medial phalanges of the front foot and the varus angle of the front foot decreased under the force(25,10,10,20 N)of the medial heel,the medial shaft of the first metatarsal,below the lateral malleolus and above the medial malleolus,and the valgus along the X-axis was corrected by 1.395 mm,the calcaneus valgus was corrected by 1.227 mm.The calcaneus varus angle was corrected from 10.21° to 7.25°,and the varus angle was improved by 28.9%.(4)The lateral plantar metatarsal load decreased,the medial plantar metatarsal load increased under the action of a two-plane three-point force,and the plantar bone stress was significantly improved after correction.Thus,the reliability of the three-point force principle was further verified.This study provides an important theoretical support for the implementation of ankle foot orthosis in the treatment of varus in clinical practice.

Three kinds of 3D printed models assisted in treatment of Robinson type Ⅱ B2 clavicle fracture / 中国组织工程研究

BACKGROUND:With the application and development of 3D printing technology in medicine,orthopedic internal fixation surgery has become precise and individualized.The equal-scale fracture model obtained by 3D printing technology was simulated and planned before surgery,realizing the leap from traditional 2D images to more vivid and detailed three-dimensional objects.It allows the surgeon to understand the fracture type in advance and rehearse the reduction sequence,so as to realize the individualized implementation of fracture surgery,optimize the surgical process,bring better postoperative recovery and less surgical complications. OBJECTIVE:To compare clinical efficacy of three 3D printed models combined with computerized virtual repositioning technology to assist incision reduction bone plate internal fixation and traditional incision reduction bone plate internal fixation in the treatment of Robinson II B2 clavicle fracture. METHODS:Eighty patients with Robinson II B2 clavicle fracture were randomly divided into trial group(n=40)and control group(n=40).In the trial group,three kinds of 3D printing models(affected clavicle fracture model,computer simulation clavicle fracture reduction model,clavicle mirror model of healthy side)combined with computer virtual reduction technology were used for preoperative in vitro surgery rehearsal.Finally,3D printing was used for clavicle mirror model of healthy side to advance bending and select bone plates for internal fixation.In the control group,open reduction plate internal fixation was applied.The time from admission to surgery,intraoperative blood loss,operation time,frequency of fluoroscopy,number of bends of the bone plate,fracture healing time,complications,and visual analog scale score and Constant score before and after surgery were compared between the two groups. RESULTS AND CONCLUSION:The time from admission to operation in the trial group was greater than that in the control group(P<0.05).Operation time,intraoperative fluoroscopy frequency and bending times of the bone plate in the trial group were lower than those in the control group(P<0.05).The trial group had faster fracture healing and fewer complications(P<0.05).There was no significant difference in intraoperative blood loss between the two groups(P>0.05).Constant score of the two groups had an increasing trend with time(F=613.50,P<0.001),but the difference between the groups was not statistically significant(F=0.08,P=0.78),and there was no interaction between the measurement times and the group assignment(F=0.27,P=0.66).The visual analog scale score decreased with time(F=1 149.55,P<0.001),but there was no significant difference between groups(F=0.02,P=0.88),and there was no interaction between the number of measurements and the group assignment(F=1.02,P=0.36).The results show that the use of 3D printed model combined with computer virtual reduction technology for preoperative rehearsal can shorten the operation time,reduce the number of intraoperative fluoroscopy frequency and the times of bone plate bending,and have the advantages of faster fracture healing,fewer complications,and similar functional recovery to the traditional incision reduction bone plate internal fixation.

Evaluation of antibacterial properties of uniaxial and coaxial minocycline hydrochloride-loaded bone scaffolds / 中国组织工程研究

BACKGROUND:Due to the unstable drug release rate of uniaxial bone scaffolds,multi-structure composite printing methods have been sought in and outside China in recent years.Currently,coaxial drug-loaded bone scaffolds,which combine drug-loaded sustained release system with bone transplantation and repair technology,not only replace the defective bone after implantation,but also release drugs slowly,providing a microenvironment conducive to bone formation at the implant site. OBJECTIVE:To explore and assess the in vitro antibacterial properties of uniaxial and coaxial minocycline hydrochloride bone scaffolds. METHODS:Rapid prototyping technology was used to prepare uniaxial hydroxyapatite/silk fibroin-polyvinyl alcohol scaffold,uniaxial hydroxyapatite/silk fibroin-polyvinyl alcohol scaffold,coaxial hydroxyapatite/silk fibroin-polyvinyl alcohol scaffold,and coaxial hydroxyapatite/silk fibroin-polyvinyl alcohol scaffold,respectively,which were named S1,S2,T1 and T2.The morphology,porosity,degradation performance,in vitro sustained-release performance and cytotoxicity of scaffolds were characterized.Four kinds of bone scaffolds were immersed in PBS to prepare the extracts at different time points(1,3,5,7,14,21,and 28 days).The qualitative filter paper was placed into the extract for 24 hours.The filter paper was co-cultured with Porphyromonas gingivalis and Fusobacterium nucleatum for 72 hours.The bacteriostatic effect of four groups of scaffolds was detected by the agar diffusion method. RESULTS AND CONCLUSION:(1)Scaffold characterization:Four groups of scaffolds were well formed.The surface of micro-wires in the S1 and S2 groups was dense and smooth,and the surface of micro-wires in the T1 and T2 groups was rough.Porosity was between 40%-47%and met the requirements of bone scaffolds.Compared with the S2 group,sustained release time was longer in the T2 group.The sustained release concentration of the drug was between 1-10 μg/mL for a long time,which was more conducive to bacteriostasis and osteogenesis.After 10 weeks of immersion in PBS in vitro,the degradation rate of the coaxial printed bone scaffold was faster than that of the corresponding uniaxial printed bone scaffold,and the degradation rate of the coaxial loaded bone scaffold was lower than that of the coaxial non-loaded bone scaffold.The four groups of scaffold extracts were co-cultured with osteoblasts respectively.CCK-8 assay displayed that the cell proliferation rate was greater than 75%,which met the requirements of biocompatibility.(2)In vitro antibacterial effect:S1 and T1 did not have antibacterial activity.S2 and T2 had an obvious antibacterial effect.Under the extraction solution on day 28,the diameter of Porphyromonas gingivalis and Fusobacterium nucleatum inhibition zone in the S2 group was smaller than that in the T2 group(P<0.05).(3)These findings exhibit that hydroxyapatite/silk fibroin-polyvinyl alcohol scaffolds with coaxial minocycline have good physical properties and bacteriostatic properties.