OBJECTIVE: To investigate the influence of 135° and 90° cavity design on quality of margin and marginal adaptation and microleakage of all-ceramic computer aided design/computer aided manufacturing (CAD/CAM) inlays. METHODS: One hundred extracted human molars were prepared by criteria of buccal occlusal (BO) inlay. On the buccal, the mesial margin was prepared as 135° bevel while the distal margin was prepared as butt-joint. All-ceramic restorations were made in the Sirona CEREC AC CAD/CAM system with VitaBlocs Mark Ⅱ, Upcera UP.CAD, IPS e.max CAD, Upcera Hyramic and Lava Ultimate. The gaps between each inlay's mesial margin-abutment and distal margin-abutment were recorded under an optical microscope. Each inlay was adhered to the abutment and aged by thermal cycling for 10 000 times. Each specimen was cut into 3 slices after staining. Dye penetration was evaluated under an optical microscope for mesial and distal margins. RESULTS: Mean marginal integrity rate, mean marginal gap value and mean depth of microleakage of 135° margin of Group Upcera Hyramic and Lava Ultimate were significantly better than those of Group VitaBlocs Mark Ⅱ, Upcera UP.CAD and IPS e.max CAD(P < 0.05). Mean marginal gap value, mean depth of microleakage and scale of mean depth of microleakage of 90° margin of Group Upcera Hyramic and Lava Ultimate were significantly better than those of Group Upcera UP.CAD and IPS e.max CAD (P < 0.05) while mean marginal integrity rate was not significantly different (P>0.05). Mean marginal integrity rate of 90° margin was significantly better than that of 135° margin in each group (P < 0.05) while mean depth of microleakage between different margins was not significantly different in each group (P>0.05). Mean marginal gap value of 90° margin of Group VitaBlocs Mark Ⅱ and IPS e.max CAD was significantly better than that of 135° margin (P < 0.05) while there was not significant difference in other 3 groups between 90° and 135° margin (P>0.05). Scale of mean depth of microleakage of 135° margin of Group Upcera Hyramic and Lava Ultimate was significant better than that of 90° margin (P < 0.05) while there was not significantly different in other 3 groups between 90° and 135° margin (P>0.05). CONCLUSION The mesial and distal margins of abutement of all-ceramic inlay should be prepared as butt-joint.
Humans ; Aged ; Molar ; Ceramics ; Computer-Aided Design ; Dental Porcelain ; Materials Testing

Using digital technologies in concurrently performing missing tooth implantation and preparation of remaining teeth is a solution to reduce the number of visits and improve efficiency. This paper proposes a digital process for simultaneously implanting and preparing teeth. It integrates implant surgical guide and 3D-printed tooth preparation guide into a single guide and completes guided implant placement and precise tooth preparation. Based on "repair-oriented" virtual implant planning, the implant surgical guide can improve the efficiency and predictability of implant placement, and its linear accuracy is about 1 mm. The tooth preparation guide precisely guides tooth preparation and restoration space visualization, ensuring the quality of the tooth preparation. The two guides have different design accuracy requirements, and thus their combination improves the overall guiding accuracy requirements. The concurrent application of the two guides minimizes the clinical operation time, number of visits, and economic burden of patients.
Humans ; Surgery, Computer-Assisted ; Dental Implantation, Endosseous ; Printing, Three-Dimensional ; Technology ; Tooth Preparation ; Computer-Aided Design ; Dental Implants ; Imaging, Three-Dimensional ; Cone-Beam Computed Tomography

Objective: To explore the effect of scanning methods on finish line trueness of the full crown preparation. Methods: The standard full crown preparation model of the right maxillary first molars was prepared by using the maxillary standard resin dentition model. The standard preparation was scanned by imetric scanner and data were used as the true value. CEREC Omnicam and 3Shape TRIOS were used to scan the standard preparation. According to the scanning methods, they were divided into parallel scanning group, occlusal wave scanning group and buccolingual wave scanning group. Each group was scanned repeatedly 6 times. The data were imported into Geomagic Studio 2013 software, and the local finish line image data of the mesial, distal, buccal and lingual regions of the full crown preparation were extracted respectively. Three-dimensional deviation analysis was performed with the reference true value, and the root- mean-square error (RMSE) was the evaluation index of scanning trueness. The statistical method was one-way ANOVA. Results: Parallel scanning group: in general, the RMSE value of complete finish lines of scanner B [(35±6) μm] was significantly lower than that of scanner A [(44±7) μm](P<0.05). After scanner A occlusal wave scanning, the RMSE values of the mesial and distal finish lines [(33±5) and (50±12) μm] were significantly lower than those of parallel scanning group (P<0.05). After buccal and lingual wave scanning, the RMSE values of local finish lines in the mesial, distal, buccal and lingual regions [(37±3), (50±6), (28±6) and (29±8) μm] were significantly lower than those in parallel scanning group [(45±9), (63±7), (38±3) and (40±3) μm] (P<0.05). No significant difference was found in the RMSE values of the mesial, distal, buccal and lingual regions of scanner B between parallel scanning group, occlusal wave scanning group and buccolingual scanning group (P>0.05). Conclusions: The scanning trueness of the full crown preparation finish line obtained by the active triangulation scanning equipment can be improved by changing the scanning method to wave scanning.
Humans ; Imaging, Three-Dimensional ; Dental Impression Technique ; Computer-Aided Design ; Dental Care ; Crowns

Spinal bionic therapy is the application of bionics concept, by imitating the natural anatomical structure and physiological function of the spine, to treat spinal diseases using various modern technology, materials and equipment .How to repair or preserve the anatomical structure and function of spine to the maximum extent while treating spinal diseases is an important content of spinal bionic therapy.Firstly, the use of movable spinal implants not only preserves the spinal mobility function to a certain extent, reduces the degeneration of adjacent segments, but also reduces the incidence of internal fixation fracture and improves the long-term efficacy.Secondly, with the help of the development of three dimensional printing technology, personalized artificial prostheses can be made to fill the spinal structure with complex defects, and biological scaffolds and functional prostheses with anti-tumor drugs can not only realize the biomimetic and functional spine anatomy, but also become a multiplier of the efficacy of anti-tumor drugs.Thirdly, in the design and manufacture of spinal orthopaedic braces, computer aided design and manufacturing technology can make spinal orthopaedic braces more comfortable with better orthopaedic effect and ergonomic characteristics.How to apply bionics concepts and relate technologies to spinal surgery have not been determined yet, and no relevant diagnosis and treatment guidelines have been formulated.It is foreseeable that with the continuous development of medical technology, the content of spinal bionic therapy will be gradually enriched and improved, and become a powerful measure to overcome difficulties in the diagnosis and treatment of spinal surgery diseases.
Bionics ; Computer-Aided Design ; Humans ; Printing, Three-Dimensional ; Prostheses and Implants ; Spine/surgery*

According to the fourth national oral health epidemiological survey report (2018), billions of teeth are lost or missing in China, inducing chewing dysfunction, which is necessary to build physiological function using restorations. Digital technology improves the efficiency and accuracy of oral restoration, with the application of three-dimensional scans, computer-aided design (CAD), computer-aided manufacturing (CAM), bionic material design and so on. However, the basic research and product development of digital technology in China lack international competitiveness, with related products basically relying on imports, including denture 3D design software, 3D oral printers, and digitally processed materials. To overcome these difficulties, from 2001, Yuchun Sun's team, from Peking University School and Hospital of Stomatology, developed a series of studies in artificial intelligence design and precision bionics manufacturing of complex oral prostheses. The research included artificial intelligence design technology for complex oral prostheses, 3D printing systems for oral medicine, biomimetic laminated zirconia materials and innovative application of digital prosthetics in clinical practice. The research from 2001 to 2007 was completed under the guidance of Prof. Peijun Lv and Prof. Yong Wang. Under the support of the National Natural Science Foundation of China, the National Science and Technology Support Program, National High-Tech R & D Program (863 Program) and Beijing Training Project for the Leading Talents in S & T, Yuchun Sun's team published over 200 papers in the relevant field, authorized 49 national invention patents and 1 U.S. invention patent and issued 2 national standards. It also developed 8 kinds of core technology products in digital oral prostheses and 3 kinds of clinical diagnosis and treatment programs, which significantly improved the design efficiency of complex oral prostheses, the fabrication accuracy of metal prostheses and the bionic performance of ceramic materials. Compared with similar international technologies, the program doubled the efficiency of bionic design and manufacturing accuracy and reduced the difficulty of diagnosis and cost of treatment and application by 50%, with the key indicators of those products reaching the international leading level. This program not only helped to realize precision, intelligence and efficiency during prostheses but also provided functional and aesthetic matches for patients after prostheses. The program was rewarded with the First Technical Innovation Prize of the Beijing Science and Technology Awards (2020), Gold Medal of Medical Research Group in the First Medical Science and Technology Innovation Competition of National Health Commission of the People's Republic of China (2020) and Best Creative Award in the First Translational Medical Innovation Competition of Capital (2017). This paper is a review of the current situation of artificial intelligence design and precision bionics manufacturing of complex oral prosthesis.
Artificial Intelligence ; Bionics ; Computer-Aided Design ; Dental Prosthesis Design ; Humans ; Printing, Three-Dimensional ; Prostheses and Implants

OBJECTIVE: To analyze the marginal roughness and marginal fitness of chairside computer-aided design and computer-aided manufacturing (CAD/CAM) laminate veneers with different materials and thicknesses, and to provide a reference for the clinical application of laminate veneers. METHODS: The butt-to-butt type laminate veneers were prepared on resin typodonts, the preparations were scanned, and the laminate veneers were manufactured by chairside CAD/CAM equipment. The laminate veneers were divided into four groups (n=9) according to the materials (glass-matrix ceramics and resin-matrix ceramics) and thickness (0.3 mm and 0.5 mm) of the veneers, with a total of 36. The marginal topo-graphies of each laminate veneer were digitally recorded by stereomicroscope, and the marginal rough-nesses of the laminate veneers were determined by ImageJ software. The marginal fitness of the laminate veneers was measured by a fit checker and digital scanning and measuring method. At the same time, the mechanical properties of glass-matrix ceramic and resin-matrix ceramic bars (n=20) were tested by a universal testing device. RESULTS: The marginal roughness of 0.3 mm and 0.5 mm glass-matrix ceramic laminate veneers was (24.48±5.55) μm and (19.06±5.75) μm, respectively, with a statistically significant difference (P < 0.001). The marginal roughness of 0.3 mm and 0.5 mm resin-matrix ceramic laminate veneers was (6.13±1.27) μm and (6.84±2.19) μm, respectively, without a statistically significant difference (P>0.05). The marginal roughness of the glass-matrix ceramic laminate veneers was higher than that of the resin-matrix ceramic laminate veneers with a statistically significant difference (P < 0.001). The marginal fitness of 0.3 mm and 0.5 mm glass-matrix ceramic laminate veneers were (66.30±26.71) μm and (85.48±30.44) μm, respectively. The marginal fitness of 0.3 mm and 0.5 mm resin-matrix ceramic laminate veneers were (56.42±19.27) μm and (58.36±8.33) μm, respectively. There was no statistically significant difference among the 4 groups (P>0.05). For glass-matrix ceramics, the flexural strength was (327.40±54.25) MPa, the flexural modulus was (44.40±4.39) GPa, and the modulus of resilience was (1.24±0.37) MPa. For resin-matrix ceramics, the flexural strength was (173.71±16.61) MPa, the flexural modulus was (11.88±0.51) GPa, and the modulus of resilience was (1.29±0.27) MPa. The flexural strength and modulus of glass-matrix ceramics were significantly higher than those of resin-matrix ceramics (P < 0.001), but there was no statistically significant difference in the modulus of resilience between the two materials (P>0.05). CONCLUSION The marginal roughness of CAD/CAM glass-matrix ceramic laminate veneers is greater than that of resin-matrix ceramic laminate veneers, but there was no statistically significant difference in marginal fitness among them. Increasing the thickness can reduce the marginal roughness of glass-matrix ceramic laminate veneers, but has no effect on the marginal roughness of resin-matrix ceramic laminate veneers.
Ceramics ; Computer-Aided Design ; Dental Porcelain ; Dental Veneers ; Materials Testing ; Surface Properties

OBJECTIVE: To explore the construction process of the digital reference crown models, and to initially establish the digital reference crown models of the primary teeth to lay the foundation for the establishment of the standardized crown models and the future related applications of computer-aided design/computer-aided manufacture (CAD/CAM) technology to pediatric dentistry. METHODS: This study randomly selected children who were caries free, aged from 4 to 5 years in several kindergartens of Haidian District of Beijing.Plaster dental models were made for the children after taking complete impressions.The digital dental models were reconstructed by using the three-dimensional (3D) dental model scanner.And then, Geomagic Studio, a 3D reverse engineering software, was employed to extract the single dental crown data, the mesiodistal and buccolingual diameters and the height of the crowns were measured.The object was reduced or enlarged by a numerical factor, and then the size of each dental crown was standardized.A total of 3-5 points features on the crown were created, and all the objects were aligned through the functions of feature-based alignment.Finally, through average-based object creation and smoothing, the digital models of reference crowns of the primary teeth were established. RESULTS: A total of 40 plaster dental models from 16 boys and 26 girls were selected out for our further study.The digital dental models were reconstructed, and the mesiodistal and buccolingual diameters and the height of the crowns were measured by using reverse engineering technology.Comparing the results of using mesiodistal diameter, buccolingual diameter and height as the standards, we chose the mesiodistal diameters of crowns to do the standardization, and successfully established the digital reference models of 20 primary teeth crowns with detailed surface characteristics. CONCLUSION In this study, the digital reference crown models of the primary teeth were established by reverse engineering technology, providing reference value for the standardized crown models and application for clinical practice, scientific research and teaching.Furthermore, this study also contributes to the extensive application of CAD/CAM technology in pediatric dentistry and the development of CAD/CAM dental systems with independent intellectual property rights.
Child ; Computer-Aided Design ; Crowns ; Dental Prosthesis Design ; Female ; Humans ; Male ; Software ; Tooth Crown ; Tooth, Deciduous

OBJECTIVE: To investigate the effect of polishing on surface roughness, gloss and optimum polishing time of various computer aided design/computer aided manufacturing (CAD/CAM) restorative materials and to provide a proper polishing procedure for dental clinicians. METHODS: Five CAD/CAM restorative materials including vita mark Ⅱ (VM), vita enamic (VE), lava ultimate (LU), shofu block HC (SB) and brilliant crios (BC) were selected. Six specimens were prepared for each material. The specimen was fixed on a custom-made polishing apparatus and sequentially polished with Sof-Lex poli-shing disk system including medium disk (with abrasive particle sizes of 10-40 μm), fine disk (with abrasive particle sizes of 3-9 μm) and superfine disk (with abrasive particle sizes of 1-7 μm). Surface roughness (Ra value) and gloss value were measured every 10 seconds until the numerical values were no longer changed. Then the surface roughness, gloss value and polishing time were recorded and the specimen was moved to the next sequence of polishing. Finally, statistical analysis was performed using SPSS 24.0. RESULTS: For all the restorative materials, the Ra values were significantly reduced (P < 0.05) and the gloss values were significantly increased (P < 0.05) after sequentially polishing with Sof-Lex disks. No significant difference was detected among Ra values of all the tested materials (P>0.05) after sequential polishing. The gloss values of LU [(68.1±4.5) GU] and BC [(68.2±5.8) GU] were significantly higher than those of VE [(48.1±8.1) GU] and BC [(53.2±5.8) GU], P < 0.05. To obtain optimal surface smoothness, VM cost the shortest polishing time [40 (30, 55) s] among all the restorative materials (P < 0.05). No significant differences in the total polishing time were observed among VE [140 (135, 145) s], LU [130 (120, 140) s], SB [140 (130, 150) s] and BC [130 (120, 140) s], P>0.05. CONCLUSION The surface roughness of all CAD/CAM restorative materials were decreased after sequentially polishing with Sof-Lex disk system. To obtain the smoothest surface, different types of restorative materials might need different polishing times using Sof-Lex polishing disk system. For ceramic restorative material VM, we recommend polishing only with medium disk for 40 s. For hybrid restorative material VE and composite restorative material LU, SB and BC, we recommend polishing with medium disk, fine disk and superfine disk in sequence for 130-140 s in total.
Ceramics ; Composite Resins ; Computer-Aided Design ; Materials Testing ; Surface Properties

With the development of computer and digital technology, the application of computer-aided technology has become a new trend in the field of oral implant. Computer-guided oral implant surgery has the advantages of being safer and more accurate than traditional implant surgery, and it can truly realize the concept of restoration-oriented implant. However, computer-guided oral implant surgery has various steps which cause deviations accumulation, so that some clinicians remain sceptical about the accuracy of the technology. Currently, due to the lack of a quantitative system for evaluating the accuracy of computer-guided oral implantation, the implant deviation in each step is still inconclusively in the stage of research and debate. The purpose of this paper is to summarize the advantages and disadvantages, research progress, accuracy and influencing factors of computer-guided oral implantation, aiming to provide a reference for improving implant accuracy and guiding clinical design and surgery.
Computer-Aided Design ; Computers ; Cone-Beam Computed Tomography ; Dental Implants ; Imaging, Three-Dimensional ; Patient Care Planning ; Surgery, Computer-Assisted

Cranial defects may result from clinical brain tumor surgery or accidental trauma. The defect skulls require hand-designed skull implants to repair. The edge of the skull implant needs to be accurately matched to the boundary of the skull wound with various defects. For the manual design of cranial implants, it is time-consuming and technically demanding, and the accuracy is low. Therefore, an informer residual attention U-Net (IRA-Unet) for the automatic design of three-dimensional (3D) skull implants was proposed in this paper. Informer was applied from the field of natural language processing to the field of computer vision for attention extraction. Informer attention can extract attention and make the model focus more on the location of the skull defect. Informer attention can also reduce the computation and parameter count from N ² to log( N). Furthermore,the informer residual attention is constructed. The informer attention and the residual are combined and placed in the position of the model close to the output layer. Thus, the model can select and synthesize the global receptive field and local information to improve the model accuracy and speed up the model convergence. In this paper, the open data set of the AutoImplant 2020 was used for training and testing, and the effects of direct and indirect acquisition of skull implants on the results were compared and analyzed in the experimental part. The experimental results show that the performance of the model is robust on the test set of 110 cases fromAutoImplant 2020. The Dice coefficient and Hausdorff distance are 0.940 4 and 3.686 6, respectively. The proposed model reduces the resources required to run the model while maintaining the accuracy of the cranial implant shape, and effectively assists the surgeon in automating the design of efficient cranial repair, thereby improving the quality of the patient's postoperative recovery.
Humans ; Computer-Aided Design ; Skull/surgery* ; Prostheses and Implants ; Head