Applications of artificial intelligence in dentistry: A comprehensive review

This work was funded by the Spanish Ministry of Sciences, Innovation and Universities under Projects RTI2018-101674-B-I00 and PGC2018-101904-A-100, University of Granada project A.TEP. 280.UGR18, I+D+I Junta de Andalucia 2020 project P20-00200, and Fapergs/Capes do Brasil grant 19/25510000928-3. Funding for open-access charge: Universidad de Granada/CBUAObjective: To perform a comprehensive review of the use of artificial intelligence (AI) and machine learning (ML) in dentistry, providing the community with a broad insight on the different advances that these technologies and tools have produced, paying special attention to the area of esthetic dentistry and color research. Materials and methods: The comprehensive review was conducted in MEDLINE/ PubMed, Web of Science, and Scopus databases, for papers published in English language in the last 20 years. Results: Out of 3871 eligible papers, 120 were included for final appraisal. Study methodologies included deep learning (DL; n = 76), fuzzy logic (FL; n = 12), and other ML techniques (n = 32), which were mainly applied to disease identification, image segmentation, image correction, and biomimetic color analysis and modeling. Conclusions: The insight provided by the present work has reported outstanding results in the design of high-performance decision support systems for the aforementioned areas. The future of digital dentistry goes through the design of integrated approaches providing personalized treatments to patients. In addition, esthetic dentistry can benefit from those advances by developing models allowing a complete characterization of tooth color, enhancing the accuracy of dental restorations. Clinical significance: The use of AI and ML has an increasing impact on the dental profession and is complementing the development of digital technologies and tools, with a wide application in treatment planning and esthetic dentistry procedures.Spanish Ministry of Sciences, Innovation and Universities RTI2018-101674-B-I00 PGC2018-101904-A-100University of Granada project A.TEP. 280.UGR18Junta de Andalucia P20-00200Fapergs/Capes do Brasil grant 19/25510000928-3Universidad de Granada/CBU

Effect of Aging and Thermocycling on Flexural Strength of Poly Ether Ether Ketone (PEEK) as a Provisional Restoration for Full Mouth Rehabilitation: An Invitro Comparative Study

PURPOSE OF THE STUDY: The present in-vitro study was conducted to compare and evaluate the flexural strength of Autopolymerizing PMMA resin, CAD/CAM milled PMMA and CAD/CAM milled PEEK after being subjected to aging and thermocycling. MATERIALS AND METHODS: Sixty identical samples measuring 25mm * 2mm * 2mm , according to ADA/ANSI specification no. 27 were fabricated using Auto polymerizing PMMA resin – GROUP I ; CAD /CAM milled PMMA – GROUP II and PEEK – GROUP III ( 20 samples in each group). The Group I (A), Group II (A) and Group III (A) test samples (10 samples in each group) were subjected to 7 days of aging/conditioning and 500 cycles of thermocycling and Group I (B), Group II (B) and Group III (B) test samples (10 samples in each group) were subjected to 14 days of aging/conditioning and 1000 cycles of thermocycling. Aging/ conditioning was done in incubator and thermocycling was done in Thermocycling unit. The flexural strength was evaluated using Universal testing machine. The data’s were analyzed with Student t test and pair–wise comparison of mean values was done by ANOVA (Analysis of Variance) test. Statistical significance was considered at 5% significance level. RESULTS: The Flexural strength of PEEK was higher than the Autopolymerizing PMMA resin and CAD/CAM milled PMMA. The Flexural strength of PEEK subjected to 7 days of aging/conditioning and 500 cycles of thermocycling (Group III (A)) (6628.70 Mpa) was the highest followed by the flexural strength of PEEK subjected to 14 days of aging and 1000 cycles of thermocycling (Group III (B)) (3760.50 Mpa). CONCLUSION: The mean flexural strength of PEEK was highly significant than the Autopolymerizing PMMA resin and CAD/ CAM milled PMMA. But, the mean flexural strength of PEEK reduced approximately by 44% while increasing the days of aging and number of thermocycling

Comparative evaluation of the marginal gap and internal gap of Co-Cr copings fabricated by different techniques: An In Vitro study

An in vitro study was conducted to comparatively evaluate the marginal gap and internal gap of Co-Cr copings fabricated by conventional casting procedures and with Direct Metal Laser Sintering (DMLS) technique. In the conventional casting procedures, two different pattern forming techniques namely conventional inlay casting wax pattern fabrication and 3D printed resin pattern fabrication were employed. A total of 30 test samples (G1, G2 and G3) were fabricated using Co-Cr alloy in three different fabricating techniques. All the samples were made from single master die which was a replica of the stainless steel master model. 10 cast copings were made from patterns obtained from inlay casting wax. 10 cast copings were made from 3D printed resin pattern. 10 copings were obtained from DMLS technique. Patterns made from inlay casting wax and 3D printed pattern resin were invested, burn out procedure was carried out and casting procedure was done with Co-Cr alloy to obtain cast copings. Cast copings were divested, sandblasted, steam cleaned and finishing procedures were done. Copings obtained from DMLS technique were also sandblasted and steam cleaned. The test samples were then cemented sequentially on stainless steel model using pressure indicating paste to simulate a coping cemented in the oral condition and the copings were evaluated for vertical marginal gap in microns. The vertical marginal gap was measured in 8 predetermined reference areas using Video Measuring Systems (VMS2010F). The test samples were removed from the master model, and pressure indicating paste was separated from the inner surface of test samples. They were then partially sectioned and reseated on the master model with pressure indicating paste and were evaluated for internal gap. The internal gaps were measured with Video Measuring System (VMS2010F) at 4 predetermined reference areas. The results obtained for both marginal and internal gap were tabulated and statistically analyzed. The results obtained in this study indicate the presence of vertical marginal gap and internal gap for all the test samples .The vertical marginal gap of the copings obtained by three different fabrication techniques methods were statistically significant to each other. The copings obtained from DMLS technique showed statistically significant minimum value followed by cast copings obtained using 3D printed resin pattern. The cast copings obtained from inlay casting wax pattern showed maximum vertical marginal gap. The results of the internal gap present between the coping and the master model showed statistically significant difference between cast copings obtained using inlay casting wax and cast copings obtained using 3D printed resin pattern. Cast copings obtained from 3D printed resin pattern and copings obtained from DMLS technique also showed statistical significance. But there was no statistical difference between cast copings obtained from inlay casting wax and copings obtained using DMLS technique. The manufacturing process influences marginal and internal accuracy of the dental restorations. An increase in vertical marginal gap exposes the cement to the oral environment thereby affects the health of the remaining supporting structure and increase in internal gap affects the retention of the restoration, hence both are important parameters to be considered for longevity of a restorations. Results of this study showed the vertical marginal gap of Co-Cr copings obtained by three different fabrication techniques were within the clinically acceptable range of (10-160μm). The internal gap of Co-Cr copings obtained from three different techniques were also within the clinically acceptable range (81-136μm). In this study a new fabricating procedure (DMLS) was used for the fabrication of Co-Cr copings. The vertical marginal gap of the Co-Cr coping obtained by this technique was (10.52μm) least compared to other two techniques. However the internal gap of Co-Cr copings by DMLS procedure (41.27μm) was maximum among the three groups. Though results obtained in this in vitro study fall within the clinically acceptable range, the DMLS technique had an edge over the other two techniques used, as it exhibited minimal gap in the marginal region which is an area of chief concern. In terms of marginal fit and internal fit, both conventional casting technique and DMLS have yielded results within clinically acceptable range but the difficulties encountered during conventional casting procedures are being completely eliminated in DMLS technique which seems to yield promising results. Future studies regarding the mechanical properties and biocompatibility of laser sintered Co-Cr would be of great use before their acceptance into dental laboratory and practice

Three-dimensional modeling of the human jaw/teeth using optics and statistics.

Object modeling is a fundamental problem in engineering, involving talents from computer-aided design, computational geometry, computer vision and advanced manufacturing. The process of object modeling takes three stages: sensing, representation, and analysis. Various sensors may be used to capture information about objects; optical cameras and laser scanners are common with rigid objects, while X-ray, CT and MRI are common with biological organs. These sensors may provide a direct or an indirect inference about the object, requiring a geometric representation in the computer that is suitable for subsequent usage. Geometric representations that are compact, i.e., capture the main features of the objects with a minimal number of data points or vertices, fall into the domain of computational geometry. Once a compact object representation is in the computer, various analysis steps can be conducted, including recognition, coding, transmission, etc. The subject matter of this dissertation is object reconstruction from a sequence of optical images using shape from shading (SFS) and SFS with shape priors. The application domain is dentistry. Most of the SFS approaches focus on the computational part of the SFS problem, i.e. the numerical solution. As a result, the imaging model in most conventional SFS algorithms has been simplified under three simple, but restrictive assumptions: (1) the camera performs an orthographic projection of the scene, (2) the surface has a Lambertian reflectance and (3) the light source is a single point source at infinity. Unfortunately, such assumptions are no longer held in the case of reconstruction of real objects as intra-oral imaging environment for human teeth. In this work, we introduce a more realistic formulation of the SFS problem by considering the image formation components: the camera, the light source, and the surface reflectance. This dissertation proposes a non-Lambertian SFS algorithm under perspective projection which benefits from camera calibration parameters. The attenuation of illumination is taken account due to near-field imaging. The surface reflectance is modeled using the Oren-Nayar-Wolff model which accounts for the retro-reflection case. In this context, a new variational formulation is proposed that relates an evolving surface model with image information, taking into consideration that the image is taken by a perspective camera with known parameters. A new energy functional is formulated to incorporate brightness, smoothness and integrability constraints. In addition, to further improve the accuracy and practicality of the results, 3D shape priors are incorporated in the proposed SFS formulation. This strategy is motivated by the fact that humans rely on strong prior information about the 3D world around us in order to perceive 3D shape information. Such information is statistically extracted from training 3D models of the human teeth. The proposed SFS algorithms have been used in two different frameworks in this dissertation: a) holistic, which stitches a sequence of images in order to cover the entire jaw, and then apply the SFS, and b) piece-wise, which focuses on a specific tooth or a segment of the human jaw, and applies SFS using physical teeth illumination characteristics. To augment the visible portion, and in order to have the entire jaw reconstructed without the use of CT or MRI or even X-rays, prior information were added which gathered from a database of human jaws. This database has been constructed from an adult population with variations in teeth size, degradation and alignments. The database contains both shape and albedo information for the population. Using this database, a novel statistical shape from shading (SSFS) approach has been created. Extending the work on human teeth analysis, Finite Element Analysis (FEA) is adapted for analyzing and calculating stresses and strains of dental structures. Previous Finite Element (FE) studies used approximate 2D models. In this dissertation, an accurate three-dimensional CAD model is proposed. 3D stress and displacements of different teeth type are successfully carried out. A newly developed open-source finite element solver, Finite Elements for Biomechanics (FEBio), has been used. The limitations of the experimental and analytical approaches used for stress and displacement analysis are overcome by using FEA tool benefits such as dealing with complex geometry and complex loading conditions

Comparison of internal fit of metal copings fabricated with laser sintering technique and lostwax technique, pre and post firing: An In Vitro study

An in vitro study was conducted to compare the marginal and internal gap of Co-Cr copings fabricated by two methods, (conventional lost wax technique and Direct laser sintering). A total of 30 test samples were fabricated using Co-Cr alloys in two different techniques. All the samples were made by making an impression from a stainless steel master model.15 cast copings were fabricated from patterns obtained by inlay-casting wax for conventional lost wax technique. 15 copings were obtained from 3D printing for fabricating DMLS copings. Patterns made from inlay wax were invested, burnout and casting was done by traditional method with Co-Cr alloy to obtain cast copings. Cast copings were divested, sandblasted, steam cleaned and finished. Copings prepared from DLMS technique were also sandblasted and steam cleaned. The entire copings were then cemented on the stainless steel master model using silicone pressure indicating paste to simulate a coping cemented in the oral condition. The test samples were removed from the master model, and the silicon coping was separated from the inner surface of test samples. The silicon copings thus obtained were evaluated for internal gap using an electronic analytical weighing machine (Schimadzu, Japan). All the measurements were determined in micro grams (μg). Later the test samples were cemented onto their respective dies with GIC type I luting cement (GC, FUJI Japan). These cemented specimens were sectioned mesio-distally. The marginal gap was measured in 2 predetermined reference points using a Scanning electron microscope (Sigma V, Carl Zeiss, Munich, Germany), All the measurements were determined in micrometers (μm). The manufacturing process influences marginal and internal accuracy of the dental restorations. An increase in marginal gap exposes the cement to the oral environment thereby affecting the health of the remaining supporting structures and increase in internal gap can affect the restoration. Hence both are important parameters to be considered for longevity of a restoration. Results of this study showed the marginal gap of Co-Cr copings obtained by two different fabrication techniques were within the clinically acceptable range (10-160μm). The internal gap of Co-Cr copings were obtained from two different techniques were also within the clinically acceptable range (81-136μm) In this study a new fabricating procedure (DMLS) was used for the fabrication of Co-Cr copings. The marginal gap of the Co-Cr coping obtained by this technique was (32μm) least compared to the lost wax technique (112μm). Though results obtained in this in vitro study fell within the clinically acceptable range, the DMLS technique had an advantage over the lost wax technique, as it exhibited minimal gap in the marginal region, an area of chief concern. In terms of marginal fit and internal fit, both the conventional casting technique and DMLS technique have yielded results within clinically acceptable range but the difficulties encountered during conventional casting procedures are being completely eliminated in DMLS technique which seems to yield promising results. The scope of further studies regarding the mechanical properties and biocompatibility of laser sintered Co-Cr would be of great use for their acceptance in dental laboratory and practice. CONCLUSION: This in-vitro study was conducted to compare pre and post-firing of the internal fit of Co-Cr coping fabricated by conventional lost wax technique (LW) and direct metal laser sintering (DMLS) technique. 1. The internal gap of 15 pre-firing Co-Cr copings of the lost wax (G1-LW) showed a mean value of 34μg. 2. The internal gap of 15 post-firing Co-Cr copings of lost wax (G1-LW) showed a mean value of 37μg. 3. The internal gap of 15 pre-firing Co-Cr copings of the DMLS (G2-DMLS) showed a mean value of 23μg. 4. The internal gap of 15 post-firing Co-Cr copings of DMLS (G2-DMLS) showed a mean value of 26μg. 5. The marginal gap of the 15 Co-Cr copings obtained from Lost-wax (G1-LW) technique showed a mean value of 109μm. 6. The marginal gap of the 15 Co-Cr copings obtained from DMLS (G2-DMLS) technique showed a mean value of 46μm. From the above data the study concluded that the mean internal gap between (G1-LW) and (G2-DMLS) for pre and post firing metal ceramic copings show statistically significant difference. Also it was found that the mean marginal gap between (G1-LW) and (G2-DMLS) for post firing metal ceramic copings show very high statistically significant difference. Conventional casting technique and DMLS have yielded results within clinically acceptable range, but compared to conventional casting methods, the technique sensitive procedures are being completely eliminated in the DMLS technique

Production Engineering and Management

The annual International Conference on Production Engineering and Management takes place for the sixth time his year, and can therefore be considered a well - established event that is the result of the joint effort of the OWL University of Applied Sciences and the University of Trieste. The conference has been established as an annual meeting under the Double Degree Master Program ‘Production Engineering and Management’ by the two partner universities. The main goal of the conference is to provide an opportunity for students, researchers and professionals from Germany, Italy and abroad, to meet and exchange information, discuss experiences, specific practices and technical solutions used in planning, design and management of production and service systems. In addition, the conference is a platform aimed at presenting research projects, introducing young academics to the tradition of Symposiums and promoting the exchange of ideas between the industry and the academy. Especially the contributions of successful graduates of the Double Degree Master Program ‘Production Engineering and Management’ and those of other postgraduate researchers from several European countries have been enforced. This year’s special focus is on Direct Digital Manufacturing in the context of Industry 4.0, a topic of great interest for the global industry. The concept is spreading, but the actual solutions must be presented in order to highlight the practical benefits to industry and customers. Indeed, as Henning Banthien, Secretary General of the German ‘Plattform Industrie 4.0’ project office, has recently remarked, “Industry 4.0 requires a close alliance amongst the private sector, academia, politics and trade unions” in order to be “translated into practice and be implemented now”. PEM 2016 takes place between September 29 and 30, 2016 at the OWL University of Applied Sciences in Lemgo. The program is defined by the Organizing and Scientific Committees and clustered into scientific sessions covering topics of main interest and importance to the participants of the conference. The scientific sessions deal with technical and engineering issues, as well as management topics, and include contributions by researchers from academia and industry. The extended abstracts and full papers of the contributions underwent a double - blind review process. The 24 accepted presentations are assigned, according to their subject, to one of the following sessions: ‘Direct Digital Manufacturing in the Context of Industry 4.0’, ‘Industrial Engineering and Lean Management’, ‘Management Techniques and Methodologies’, ‘Wood Processing Technologies and Furniture Production’ and ‘Innovation Techniques and Methodologies

Surface Reconstruction by Triangular Mesh of Models with Uneven Density and with Hole

With the fast development of computer software, 3D computer aided design (CAD) and computer aided manufacturing (CAM) are being improved rapidly and have been commonly used in industry, especially in medical area and moulding field. 3D CAD/ CAM has greatly shortened the mould development time, thus it plays an important role in product development and automatic production. It has been a serious topic about how to get the product design and also being manufactured in a short time to grasp the market opportunities in the competition of the developing manufacturing techniques, diversification and complexification of product demand. But not all the products have the design draft, for example, some of them were made by the mould of clay which came from craftsman by their hands. In order to conquer those problems, reverse engineering came into being. Reverse engineering could achieve a faster product design and manufacture, it also could be used in the field of vehicle components, home appliances, medical supplies (like human body measurement such as for artificial leg bones, tooth, etc.,), and rapid prototyping (such as precision casting products, industrial design, etc.). The so-called reverse engineering now targets to the existing mould (samples or manual model). It starts with the existing model, sampling surface data by data acquisition equipment (DAE) then acquire an ordered or unordered could of points. After that by the use of discrete geometry processing technology to get the CAD model of solid entity which computer could recognize. The following procedures of the CAD model could be redesigned or improved as required