Accuracy of optical scanning methods of the Cerec®3D system in the process of making ceramic inlays

Background/Aim. One of the results of many years of Cerec® 3D CAD/CAM system technological development is implementation of one intraoral and two extraoral optical scanning methods which, depending on the current indications, are applied in making fixed restorations. The aim of this study was to determine the degree of precision of optical scanning methods by the use of the Cerec®3D CAD/CAM system in the process of making ceramic inlays. Methods. The study was conducted in three experimental groups of inlays prepared using the procedure of three methods of scanning Cerec ®3D system. Ceramic inlays made by conventional methodology were the control group. The accuracy of optical scanning methods of the Cerec®3D system computer aided designcomputer aided manufacturing (CAD/CAM) was indirectly examined by measuring a marginal gap size between inlays and demarcation preparation by scanning electron microscope (SEM). Results. The results of the study showed a difference in the accuracy of the existing methods of scanning dental CAD/CAM systems. The highest level of accuracy was achieved by the extraoral optical superficial scanning technique. The value of marginal gap size inlays made with the technique of extraoral optical superficial scanning was 32.97 ± 13.17 μ. Techniques of intraoral optical superficial and extraoral point laser scanning showed a lower level of accuracy (40.29 ± 21.46 μ for inlays of intraoral optical superficial scanning and 99.67 ± 37.25 μ for inlays of extraoral point laser scanning). Conclusion. Optical scanning methods in dental CAM/CAM technologies are precise methods of digitizing the spatial models; application of extraoral optical scanning methods provides the hightest precision

Optička digitalizacija prostornog modela projiciranjem kodiranog svjetla

This paper analyzes deviations of a model developed by milling and a CAD model modeled according to its technical documentation. Deviations of model surfaces, dimensional deviations (length, width and height) and deviations of geometric tolerances are analyzed. It is indicated that on the scanned object specific measured values do not meet the appointment requirements in the technical documentation. Errors occurred during the manufacturing, because the selected object is relatively complex and contains many features such as holes, slots, cones and bores. It is noted that 3D scanners can be used to maintain the quality in the production because it is possible to control the resulting errors in geometry, but also for the purpose of reverse engineering and self-control of the production process.U radu su analizirana odstupanja modela izrađenog na glodalici i CAD modela modeliranog prema tehničkoj dokumentaciji istog. Analizirala su se odstupanja površina modela, dimenzijska odstupanja (duljine, širine i visine) i odstupanja geometrijskih torelancija. Pokazalo se da na skeniranom objektu određene izmjerene vrijednosti ne zadovoljavaju postavljenje zahtjeve u tehničkoj dokumentaciji. Do pogrešaka je došlo prilikom same izrade jer je odabrani predmet relativno kompleksan, sadrži mnogo značajki kao što su provrti, utori, konusi i rupe. Vidljivo je kako se 3D skeneri mogu koristiti za održavanje kvalitete u proizvodnji jer je moguće kontrolirati nastale pogreške u geometriji, ali isto tako i za reverzno inženjerstvo te samokontrolu proizvodnog procesa

Optička digitalizacija prostornog modela projiciranjem kodiranog svjetla

This paper analyzes deviations of a model developed by milling and a CAD model modeled according to its technical documentation. Deviations of model surfaces, dimensional deviations (length, width and height) and deviations of geometric tolerances are analyzed. It is indicated that on the scanned object specific measured values do not meet the appointment requirements in the technical documentation. Errors occurred during the manufacturing, because the selected object is relatively complex and contains many features such as holes, slots, cones and bores. It is noted that 3D scanners can be used to maintain the quality in the production because it is possible to control the resulting errors in geometry, but also for the purpose of reverse engineering and self-control of the production process.U radu su analizirana odstupanja modela izrađenog na glodalici i CAD modela modeliranog prema tehničkoj dokumentaciji istog. Analizirala su se odstupanja površina modela, dimenzijska odstupanja (duljine, širine i visine) i odstupanja geometrijskih torelancija. Pokazalo se da na skeniranom objektu određene izmjerene vrijednosti ne zadovoljavaju postavljenje zahtjeve u tehničkoj dokumentaciji. Do pogrešaka je došlo prilikom same izrade jer je odabrani predmet relativno kompleksan, sadrži mnogo značajki kao što su provrti, utori, konusi i rupe. Vidljivo je kako se 3D skeneri mogu koristiti za održavanje kvalitete u proizvodnji jer je moguće kontrolirati nastale pogreške u geometriji, ali isto tako i za reverzno inženjerstvo te samokontrolu proizvodnog procesa

Comparative analysis of 3d digitization systems in the field of dental prosthetics

Amongst the modern engineering technologies which have found broad application in the field of dentistry, one of the most widely used is the 3D digitization. This paper deals with the application of 3D digitization systems in the field of dental prosthetics, and attempt to contribute in this field through comparative analysis of this kind of systems. Special attention is focused on extra oral 3D digitization systems and among them on non specialized dental 3D digitization systems. Beside the general overview and analysis of nine different systems, this paper presents experimental results of comparative accuracy analysis of two high-end 3D digitization systems - Atos II Triple Scan and Zeiss Metrotom 1500. Investigation was based on CAD inspection technique and included 3D and 2D cross sectional analysis. Results related to 3D analysis show that the majority of deviations are in positive direction, concentrated around 0,025 mm. Results of 2D analysis implicate the conclusion that the accuracy of the analysed systems is dependent on surface shape as well as on the model position during the process of 3D digitization

Relationship between resolution and accuracy of four intraoral scanners in complete-arch impressions

The scanner does not measure the dental surface continually. Instead, it generates a point cloud, and these points are then joined to form the scanned object. This approximation will depend on the number of points generated (resolution), which can lead to low accuracy (trueness and precision) when fewer points are obtained. The purpose of this study is to determine the resolution of four intraoral digital imaging systems and to demonstrate the relationship between accuracy and resolution of the intraoral scanner in impressions of a complete dental arch. A master cast of the complete maxillary arch was prepared with different dental preparations. Using four digital impression systems, the cast was scanned inside of a black methacrylate box, obtaining a total of 40 digital impressions from each scanner. The resolution was obtained by dividing the number of points of each digital impression by the total surface area of the cast. Accuracy was evaluated using a three-dimensional measurement software, using the ?best alignment? method of the casts with a highly faithful reference model obtained from an industrial scanner. Pearson correlation was used for statistical analysis of the data. Of the intraoral scanners, Omnicam is the system with the best resolution, with 79.82 points per mm2, followed by True Definition with 54.68 points per mm2, Trios with 41.21 points per mm2, and iTero with 34.20 points per mm2. However, the study found no relationship between resolution and accuracy of the study digital impression systems (P >0.05), except for Omnicam and its precision. The resolution of the digital impression systems has no relationship with the accuracy they achieve in the impression of a complete dental arch. The study found that the Omnicam scanner is the system that obtains the best resolution, and that as the resolution increases, its precision increases

Comparison of Accuracy Between a Conventional and Two Digital Intraoral Impression Techniques

Aims: The objective of this study was to compare the precision and trueness of full-arch impressions using either a conventional polyvinylsiloxane (PVS) material or 2 intraoral optical scanners. Methods: Full arch impressions were obtained of a reference model using addition silicone impression material (Aquasil Ultra; Dentsply Caulk, Delaware, USA) and two optical scanners (Trios, 3Shape, Copenhagen, Denmark and CEREC Omnicam, Sirona, Wals, Austria). Surface matching software (Geomagic® Control™, 3D Systems©, Rock Hill, SC, USA) was used to superimpose the scans within groups in order to determine the mean deviations (μm) between the scans. The overall mean precision and trueness for each group was calculated and compared statistically using one-way analysis of variance with post-hoc Bonferroni (trueness) and GamesHowell (precision) tests (IBM© SPSS® ver 24, IBM UK Ltd, Portsmouth, England). Qualitative analysis was also carried out from three-dimensional maps of differences between scans. Results: Mean and standard deviations (SD) of precision for conventional, Trios and Omnicam groups were 21.7 (±5.4), 49.9 (±18.3), and 36.5 (±11.12), respectively. Mean and standard deviations (SD) for trueness were 24.3 (±5.7), 87.1 (±7.9), and 80.3 (±12.1) respectively. The conventional impression showed statistically significant improved mean precision (P<.006) and mean trueness (P<.001) compared to both digital impression procedures. There were no statistically significant differences in precision (P=0.153) or trueness (P=0.757) between the digital impressions. The qualitative analysis revealed local deviations along the palatal surfaces of the molars and incisal edges of the anterior teeth in the order of <100μm. Conclusion: Conventional full-arch PVS impressions exhibited improved mean accuracy compared to 2 direct optical scanners. No significant differences were found between the two digital impression methods

Comparison of marginal fit of lithium disilicate crowns fabricated with CAD-CAM technology using conventional impressions and two intra-oral digital scanners.

The use of digital impression techniques in dental crown fabrication is increasing. It is important these techniques yield prosthesis of equal or better accuracy compared to conventional techniques. This study compared marginal gap size in crowns fabricated by conventional and digital impression methods. One typodont maxillary right central incisor was prepared for an all-ceramic crown. Ten impressions were made with each method: conventional using polyvinyl siloxane impression material, digital impressions using the Lava C.O.S. (3M ESPE), and iTero (Cadent) intraoral scanning devices. Lithium disilicate crowns were fabricated and marginal gap measured for each using an optical microscope. There was no significant difference between average gap size in all groups. However, though not statistically significant, the conventional group average gap size was about 23µm larger compared to the digital groups. Within the limitations of this study, the digital and conventional impressions were found to produce crown crowns with similar marginal accuracy

Accuracy of computer-aided design/computer-assisted manufacture (CAD/CAM) fabricated dental restorations: a comparative study

Introduction: Computer-Aided-Design (CAD) and Computer-Aided-Manufacture (CAM) has been developed to fabricate fixed dental restorations accurately, faster and improve cost effectiveness of manufacture when compared to the conventional method. Two main methods exist in dental CAD/CAM technology: the subtractive and additive methods. While fitting accuracy of both methods has been explored, no study yet has compared the fabricated restoration (CAM output) to its CAD in terms of accuracy. The aim of this present study was to compare the output of various dental CAM routes to a sole initial CAD and establish the accuracy of fabrication. The internal fit of the various CAM routes were also investigated. The null hypotheses tested were: 1) no significant differences observed between the CAM output to the CAD and 2) no significant differences observed between the various CAM routes. Methods: An aluminium master model of a standard premolar preparation was scanned with a contact dental scanner (Incise, Renishaw, UK). A single CAD was created on the scanned master model (InciseCAD software, V2.5.0.140, UK). Twenty copings were then fabricated by sending the single CAD to a multitude of CAM routes. The copings were grouped (n=5) as: Laser sintered CoCrMo (LS), 5-axis milled CoCrMo (MCoCrMo), 3-axis milled zirconia (ZAx3) and 4-axis milled zirconia (ZAx4). All copings were micro-CT scanned (Phoenix X-Ray, Nanotom-S, Germany, power: 155kV, current: 60µA, 3600 projections) to produce 3-Dimensional (3D) models. A novel methodology was created to superimpose the micro-CT scans with the CAD (GOM Inspect software, V7.5SR2, Germany) to indicate inaccuracies in manufacturing. The accuracy in terms of coping volume was explored. The distances from the surfaces of the micro-CT 3D models to the surfaces of the CAD model (CAD Deviation) were investigated after creating surface colour deviation maps. Localised digital sections of the deviations (Occlusal, Axial and Cervical) and selected focussed areas were then quantitatively measured using software (GOM Inspect software, Germany). A novel methodology was also explored to digitally align (Rhino software, V5, USA) the micro-CT scans with the master model to investigate internal fit. Fifty digital cross sections of the aligned scans were created. Point-to-point distances were measured at 5 levels at each cross section. The five levels were: Vertical Marginal Fit (VF), Absolute Marginal Fit (AM), Axio-margin Fit (AMF), Axial Fit (AF) and Occlusal Fit (OF). Results: The results of the volume measurement were summarised as: VM-CoCrMo (62.8mm3 ) > VZax3 (59.4mm3 ) > VCAD (57mm3 ) > VZax4 (56.1mm3 ) > VLS (52.5mm3 ) and were all significantly different (p presented as areas with different colour. No significant differences were observed at the internal aspect of the cervical aspect between all groups of copings. Significant differences (p ZAx4 External Occlusal, External Cervical 3 ZAx3 ZAx4 Internal Occlusal and Internal Axial The mean values of AMF and AF were significantly (p M-CoCrMo and CAD > ZAx4. Only VF of M-CoCrMo was comparable with the CAD Internal Fit. All VF and AM values were within the clinically acceptable fit (120µm). Conclusion: The investigated CAM methods reproduced the CAD accurately at the internal cervical aspect of the copings. However, localised deviations at axial and occlusal aspects of the copings may suggest the need for modifications in these areas prior to fitting and veneering with porcelain. The CAM groups evaluated also showed different levels of Internal Fit thus rejecting the null hypotheses. The novel non-destructive methodologies for CAD/CAM accuracy and internal fit testing presented in this thesis may be a useful evaluation tool for similar applications

Digital impressions in fixed prosthodontics

Otisak u fiksnoprotetskoj terapiji najvažnije je sredstvo komunikacije između kliničara i laboratorijskog tehničara. Budući da se otisak nalazi na početku "proizvodnog lanca", eventualne greške odrazit će se na sve naredne korake u izradi protetskog rada i na njegovu konačnu preciznost. Zbog toga se nastavlja potraga za boljim materijalima i tehnologijama koji će pogreške svesti na najmanju moguću mjeru. Suvremene digitalne metode razvijene su kako bi ubrzale i pojednostavile postupak, omogućujući njegovu standardizaciju i učinkovito upravljanje kvalitetom. Trodimenzionalna (3D) digitalizacija osnova je digitalnog otiska. Postupak digitalizacije u dentalnoj medicini može biti intraoralni ili ekstraoralni, koji je zbog praktičnosti zastupljeniji. Suvremeni sustavi temelje se na optičkim metodama digitalizacije. Pritom kao izvor svjetlosti danas uglavnom služi laser zbog manje osjetljivosti na okolne čimbenike. Kao prednosti digitalnog otiska među ostalim se navode brzina, učinkovitost, ugodniji postupak za pacijenta, veća preciznost zbog smanjenja utjecaja ljudskog faktora, mogućnost pohranjivanja prikupljenih podataka na neodređeno vrijeme bez potrebe za fizičkim prostorom te jednostavniji prijenos digitalne slike između ordinacije i laboratorija. Kvaliteta otiska ovisi o tehničkoj razini opreme koja se koristi, te educiranosti i stručnosti terapeuta. Svaka novija generacija uređaja za digitalizaciju nudi nove mogućnosti s novim senzorima, eletronikom i programskom podrškom te postupak čini jednostavnijim, bržim i preciznijim.An impression in fixed prosthetic therapy is the most important communication tool between dentists and dental technicians. Since the impression is the first step in the "production chain", possible errors will be reflected in all subsequent processing steps during the fabrication of a restoration and influence its final precision. Therefore, there is a continuing quest for better materials and technologies to reduce errors to a minimum. Modern digital methods have been developed to speed up and simplify the fabrication procedure, enabling standardization and effective quality management. Three-dimensional (3D) digitalization is the basis of a digital impression. The digitalization process in dentistry can be conducted intraorally or extraorally, which is more common because of the convenience. Modern systems are based on optical methods of digitalization. Today, the mainly used light source is laser due to less sensitivity to surrounding factors. The benefits of digital impressions are speed, efficiency, more comfortable procedure for the patient, greater accuracy due to reduced influence of the human factor, the ability to store data for an indefinite period without occupying physical space, and easier transfer of digital images between the clinic and the laboratory. The quality of the impression depends on the technical level of equipment used, as well as the education and expertise of the therapist. Each new generation of devices offers new possibilities with new sensors, electronics and softwares, which make the process easier, faster and more accurate

Sistema CAD/CAM como facilitador na confecção de próteses fixas odontológicas: uma revisão integrativa

Trabalho de Conclusão de Curso, apresentado para obtenção do grau de Cirurgião Dentista no curso de Odontologia da Universidade do Extremo Sul Catarinense - UNESCA evolução da tecnologia trouxe grandes avanços para odontologia, como é o caso do sistema CAD ∕ CAM (Computer Aided Desing / Computer Aided manufactoring) definido como Desenho Auxiliado por Computação e Fresagem Auxiliada por Computação, respectivamente. Dentre todas as áreas clinicas, a prótese fixa foi a que teve maiores benefícios com essa modernização. O objetivo dessa revisão integrativa foi descrever o sistema, avaliar suas vantagens, limitações e indicações. Conclui-se que entre as maiores vantagens ao utilizar o novo sistema estão a velocidade no fluxo de trabalho, facilidade de uso, qualidade, estabilidade de cor e precisão, embora seu uso seja ainda um pouco limitado devido ao custo inicial de todo o equipamento e software