Analiza metroloških karakteristika uređaja za optičku digitalizaciju stomatoloških CAD/CAM sistema

Development and improvement of 3D digitization methods in the last forty years, have enabled that virtual impression in dentistry becomes a reality. Unlike conventional impressions, which represent negative copies of prepared teeth and surrounding tissue, 3D digitization collects data on the coordinates of surface points and transfers them into digital form. Various working principles of 3D digitization methods were the reason, that in the framework of this reasearch to invstigate and compare the basic metrological characteristics of selected optical digitization devices. Based on the hypothesis, following goal of investigation were formulated: to establish whether there is a difference in the accuracy and precision between the optical digitization devices where the process of digitization based on various working principles and determine the degree of measurment uncertainty. The basis of this experiment is CAD inspection. CAD inspection was used to measure and analyze deviations between the CAD reference model and experimental CAD models. In this way is possibile to determine the precision and accuracy of the observed optical digital device. The experimental CAD models were generated by 3D digitization of the stone replica using Cerec® AC (Sirona, Germany), Cerec® In Eos Blue (Sirona, Germany), Trios (3 shape AS, Denmark), KaVo Everest (KaVo, Germany) and Sinergia Scan (Nobil - Metal, S.p.A. Italy) surface digitization devices. The CAD master model was generated by 3D digitization of the stone replica, using Atos III Triple Scan surface digitization device. Processing of the measured results included 2D and 3D analysis. The results of 3D analysis showed thet the highest level of precision in the proceeding of digitizing the right half of upper dental arch are present in Sinergia Scan, then follow KaVo Everest, Trios, Cerec®InEos Blue i Cerec®AC devices. The highest level of accuracy in the same procedure have Cerec®InEos Blue, follow the Sinergia Scan, Cerec®AC i KaVo Everest...Razvoj i unapređenje metoda 3D digitalizacije u proteklih četrdeset godina, omogućio je da se ideja o primeni digitalnog otiska u stomatologiji pretvori u stvarnost. Za razliku od konvencionalnog otiska koji predstavlja kopiju zuba i okolnih tkiva u negativu, 3D digitalizacija je postupak u okviru koga se vrši prikupljanje podataka u vidu koordinata – tačaka i obavla njihovo prevođenje u digitalnu formu. Razlike u radnim principima postupaka 3D digitalizacije predstavljale su povod da se u okviru istraživanja ispitaju i uporede osnovne metrološke karakteristike odabranih uređaja za optičku digitalizaciju, koji se primenjuju u stomatološkoj praksi. Na osnovu postavljene hipoteze definisan je osnovni cilj istraživanja: utvrditi da li postoji razlika u preciznosti i tačnosti između uređaja za optičku digitalizaciju kod kojih je postupak digitalizacije zasnovan na različitim radnim principima i na osnovu toga proceniti stepen njihove merne nesigurnosti. Osnovu eksperimenta čini metoda CAD inspekcije, čijom primenom je moguće izvršiti kvantitativnu i kvalitativnu analizu izmerenih odstupanja uzoraka CAD eksperimentalnih modela u odnosu na CAD master model i na taj način utvrdi stepen preciznosti i tačnosti posmatranih uređaja. CAD eksperimentalni uzorci su nastali u postupku digitalizacije osnovnog modela od gipsa pomoću sledećih uređaja: Cerec®AC (Sirona, Germany), Cerec® InEos Blue (Sirona, Germany), Trios (3 shape AS, Denmark), KaVo Everest (KaVo, Germany) i Sinergia Scan (Nobil - Metal, S.p.A. Italy). Digitalizacijom osnovnog modela pomoću industrijskog optičkog uređaja Atos III Triple Scan dobijen je CAD master model. Obrada izmerenih rezultata obuhvatala je 3D i 2D analizu. Rezultati 3D analize prikazuju da je najviši stepen preciznosti uređaja u postupku digitalizacije desne polovine zubnog luka gornje vilice prisutan kod Sinergia Scan, slede KaVo Everest, Trios, Cerec®InEos Blue i Cerec®AC uređaji. Najviši stepen tačnosti u istom postupku ima Cerec®InEos Blue, slede Sinergia Scan, Cerec®AC i KaVo Everest uređaji. Dobijeni rezultati potvrđuju da uređaji za ekstraoralnu digitalizaciju imaju viši stepen tačnosti i preciznosti u odnosu na uređaje za intraoralnu digitalizaciju..

Analysis of metrological characteristics of the optical digitization devices in dental CAD/CAM technology

Razvoj i unapređenje metoda 3D digitalizacije u proteklih četrdeset godina, omogućio je da se ideja o primeni digitalnog otiska u stomatologiji pretvori u stvarnost. Za razliku od konvencionalnog otiska koji predstavlja kopiju zuba i okolnih tkiva u negativu, 3D digitalizacija je postupak u okviru koga se vrši prikupljanje podataka u vidu koordinata – tačaka i obavla njihovo prevođenje u digitalnu formu. Razlike u radnim principima postupaka 3D digitalizacije predstavljale su povod da se u okviru istraživanja ispitaju i uporede osnovne metrološke karakteristike odabranih uređaja za optičku digitalizaciju, koji se primenjuju u stomatološkoj praksi. Na osnovu postavljene hipoteze definisan je osnovni cilj istraživanja: utvrditi da li postoji razlika u preciznosti i tačnosti između uređaja za optičku digitalizaciju kod kojih je postupak digitalizacije zasnovan na različitim radnim principima i na osnovu toga proceniti stepen njihove merne nesigurnosti. Osnovu eksperimenta čini metoda CAD inspekcije, čijom primenom je moguće izvršiti kvantitativnu i kvalitativnu analizu izmerenih odstupanja uzoraka CAD eksperimentalnih modela u odnosu na CAD master model i na taj način utvrdi stepen preciznosti i tačnosti posmatranih uređaja. CAD eksperimentalni uzorci su nastali u postupku digitalizacije osnovnog modela od gipsa pomoću sledećih uređaja: Cerec®AC (Sirona, Germany), Cerec® InEos Blue (Sirona, Germany), Trios (3 shape AS, Denmark), KaVo Everest (KaVo, Germany) i Sinergia Scan (Nobil - Metal, S.p.A. Italy). Digitalizacijom osnovnog modela pomoću industrijskog optičkog uređaja Atos III Triple Scan dobijen je CAD master model. Obrada izmerenih rezultata obuhvatala je 3D i 2D analizu. Rezultati 3D analize prikazuju da je najviši stepen preciznosti uređaja u postupku digitalizacije desne polovine zubnog luka gornje vilice prisutan kod Sinergia Scan, slede KaVo Everest, Trios, Cerec®InEos Blue i Cerec®AC uređaji. Najviši stepen tačnosti u istom postupku ima Cerec®InEos Blue, slede Sinergia Scan, Cerec®AC i KaVo Everest uređaji. Dobijeni rezultati potvrđuju da uređaji za ekstraoralnu digitalizaciju imaju viši stepen tačnosti i preciznosti u odnosu na uređaje za intraoralnu digitalizaciju...Development and improvement of 3D digitization methods in the last forty years, have enabled that virtual impression in dentistry becomes a reality. Unlike conventional impressions, which represent negative copies of prepared teeth and surrounding tissue, 3D digitization collects data on the coordinates of surface points and transfers them into digital form. Various working principles of 3D digitization methods were the reason, that in the framework of this reasearch to invstigate and compare the basic metrological characteristics of selected optical digitization devices. Based on the hypothesis, following goal of investigation were formulated: to establish whether there is a difference in the accuracy and precision between the optical digitization devices where the process of digitization based on various working principles and determine the degree of measurment uncertainty. The basis of this experiment is CAD inspection. CAD inspection was used to measure and analyze deviations between the CAD reference model and experimental CAD models. In this way is possibile to determine the precision and accuracy of the observed optical digital device. The experimental CAD models were generated by 3D digitization of the stone replica using Cerec® AC (Sirona, Germany), Cerec® In Eos Blue (Sirona, Germany), Trios (3 shape AS, Denmark), KaVo Everest (KaVo, Germany) and Sinergia Scan (Nobil - Metal, S.p.A. Italy) surface digitization devices. The CAD master model was generated by 3D digitization of the stone replica, using Atos III Triple Scan surface digitization device. Processing of the measured results included 2D and 3D analysis. The results of 3D analysis showed thet the highest level of precision in the proceeding of digitizing the right half of upper dental arch are present in Sinergia Scan, then follow KaVo Everest, Trios, Cerec®InEos Blue i Cerec®AC devices. The highest level of accuracy in the same procedure have Cerec®InEos Blue, follow the Sinergia Scan, Cerec®AC i KaVo Everest..

Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60) ceramic crowns were made on non-carious extracted human premolars. Thirty (30) crowns were made on the basis of feather-edge preparation (experimental group I). The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system “Zirkonzahn” (Zirkonzahn GMBH, Gais, Germany). The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and gingival inflammatory response

Primena CAD/CAM tehnologije u projektovanju i izradi mostova pune anatomske forme na bazi cirkonijum-dioksida

Daily progress of dentistry, especially in the field of prosthodontics is introducing new materials and technologies. With the increasing need for aesthetically acceptable and non-metal materials, it came to development and improvement of ceramic materials and computer based systems (CA). The patient came in order to compensate the missing left lateral incisor. Since the adjacent teeth are brushed and the print was taken, casted model has been scanned using 3Shape D800 laboratory scanner. Dental restoration has been designed using 3Shape DentalSystem Premium software and the available tools. After completing the virtual design, the data are sent to the program responsible for CAM Zenotec® mini CAD/CAM device. As a result, the compensation with the full morphology was obtained without the need for finishing works.Stomatologija, posebno stomatološka protetika svakodnevno napreduje uvođenjem novih materijala i tehnologija. Kako se javlja sve veća potreba za estetski prihvatljivim i bezmetalnim materijalima, došlo je do razvoja i unapređenja keramičkih materijala i računarima podržanih sistema (CA). Pacijent se javio radi nadoknade nedostajućeg levog bočnog sekutića. Pošto su susedni zubi zbrušeni i uzet otisak, izliven je model koji je skeniran pomoću 3Shape D 800 laboratorijskog skenera. Zubna nadoknada je dizajnirana pomo ću 3Shape DentalSystem Premium softvera korišćenjem raspoloživih alata. Nakon završenog dizajna virtuelni podaci su poslati u program odgovoran za CAM Zenotec® mini CAD/CAM uređaja. Kao rezultat, dobijena je nadoknada pune morfologije bez potrebe za dorađivanjem

Preciznost keramičkih kruna izrađenih primenom optičkih metoda skeniranja Cerec3D sistema

Introduction: The results of many years technological development of Cerec® 3D CAD/CAM system, is implementation one intraoral and two extraoral optical scanning methods. Aim: The aim of this study was to determine the precision of ceramic crowns made by optical scanning methods of Cerec®3D system. Methods: The study was conducted in three experimental groups of ceramic crowns in whose manufacturing was applied three optical scanning methods of Cerec®3D system. Control group consisted of metalceramic crowns made by conventional methodology. The accuracy of ceramic crowns was examined by measuring of the marginal gap size between edge of crowns and demarcation by scanning electron microscope (SEM). Results: The research found, that there is a difference in the accuracy of ceramic crowns made by Cerec®3D system. The highest level of accuracy was recorded in the group of crowns made by technique extraoral optical superficial scanning (31,64±9,45μ). Marginal gap size crowns made with technique intraoral optical superficial scanning showed a lower level of accuracy (50,27±31,50μ). Value of marginal gap size crowns made by technique extraoral laser point scanning was 102,58+31,23μ. Conclusion: Ceramic crowns made by Cerec®3D optical scanners show a high and clinically acceptable precision level.Uvod: Dugogodišnji razvoj Cerec®3D CAD/CAM sistema implementirao je u praktičnu upotrebu jednu intraoralnu i dve ekstraoralne metode optičkog skeniranja. Cilj: Cilj rada je bio da se utvrdi stepen preciznosti keramičkih kruna izrađenih primenom različitih tehnika optičkog skeniranja Cerec®3D sistema. Materijal i metod: Ispitivanje je sprovedeno u okviru tri eksperimentalne grupe kruna u čijoj izradi su primenjeni različiti postupci skeniranja Cerec®3D sistema. Metalokeramičke krune izrađene konvencionalnom metodologijom predstavljale su kontrolnu grupu. Preciznost kruna ispitivana je merenjem veličine marginalnog zjapa između ruba krune i demarkacije preparacije pomoću skenirajućeg elektronskog mikroskopa (SEM). Rezultati: Rezultati istraživanja pokazuju da postoji razlika u preciznosti kruna izrađenih primenom različitih metoda skeniranja Cerec®3D sistema. Najviši stepen preciznosti (31,64±9,45μ) zabeležen je kod kruna u čijoj izradi je primenjena tehnika optičkog ekstraoralnog površinskog skeniranja, nešto niži stepen preciznosti (50,27±31,50μ) imale su krune izrađene tehnikom intraoralnog optičkog površinskog skeniranja. Krune izrađene primenom tehnike ekstraoralnog tačkastog skeniranja imale su stepen preciznosti od 102,58±31,23μ. Zaključak: Krune izrađene primenom optičkih metoda skeniranja Cerec 3D sistema pokazuju visok i klinički prihvatljiv stepen preciznosti

Ispitivanje preciznosti radnih modela pomoću koordinatne merne mašine u stomatologiji

Background/Aim. Dental impressions present a negative imprint of intraoral tissues of a patient which is, by pouring in gypsum, transferred extraorally on the working cast. Casting an accurate and precise working cast presents the first and very important step, since each of the following stages contributes to the overall error of the production process, which can lead to inadequately fitting dental restorations. The aim of this study was to promote and test a new model and technique for in vitro evaluation of the dental impression accuracy, as well as to asses the dimensional stability of impression material depending on the material bulk, and its effect on the accuracy of working casts. Methods. Impressions were made by the monophasic technique using the experimental master model. Custom trays with spacing of 1, 2 and 3 mm were constructed by rapid prototyping. The overall of 10 impressions were made with each custom tray. Working casts were made with gypsum type IV. Measurement of working casts was done 24 h later using a coordinate measuring machine. Results. The obtained results show that the working casts of all the three custom trays were in most cases significantly different in the transversal and sagittal planes in relation to the master model. The height of abutments was mainly unaffected. The degree of convergence showed certain significance in all the three custom trays, most pronounced in the tray with 3 mm spacing. Conclusion. The impression material bulk of 1-3 mm could provide accurate working casts when using the monophasic impression technique. The increase of the distance between abutment teeth influences the accuracy of working casts depending on the material bulk.Uvod/Cilj. Otisak predstavlja negativ intraoralnih tkiva, čijim se izlivanjem u gipsu njihova morfologija prenosi ekstraoralno na budući radni model. Sa laboratorijskog aspekta izrade zubnih nadoknada, izlivanje tačnog i preciznog radnog modela predstavlja prvi i veoma bitan korak, pošto svaka sledeća faza doprinosi daljem povećanju greške tokom izrade, što za krajnji ishod može imati neodgovarajuću zubnu nadoknadu. Cilj istraživanja bio je da se ispitaju novi model i tehnika za in vitro procenu preciznosti zubnih otisaka, kao i da se odredi uticaj količine otisnog materijala na dimenzionu stabilnost otisaka i preciznost izrade radnih modela. Metode. Za uzimanje otisaka korišćena je monofazna tehnika otiskivanja. Individualne kašike sa međuprostorom od 1, 2 i 3 mm napravljene su aditivnom tehnologijom za brzu izradu prototipova. Sa svakom kašikom napravljeno je po 10 otisaka. Radni modeli izlivani su u gipsu tipa IV. Merenje radnih modela vršeno je nakon 24 sata na koordinatnoj mernoj mašini. Rezultati. Rezultati pokazuju da radni modeli napravljeni pomoću sve tri individulane kašike u transverzalnoj i sagitalnoj ravni značajno odstupaju od glavnog dela modela. Visina patrljaka je u većini slučajeva bila kao na glavnom modelu. Stepen konvergencije pokazao je određena odstupanja samo kod kašike sa međuprostorom od 3 mm. Zaključak. Monofazna tehnika otiskivanja i otisni materijal debljine od 1 do 3 mm obezbeđuju izradu preciznih radnih modela. Rastojanje između zubnih patrljaka utiče na preciznost izrade radnih modela u zavisnosti od količine otisnog materijala

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

Analiza distribucije opterećenja kod mešovito nošenih mostova primenom rezilijentnih abatmenata

Introduction Differences between the tooth and implant response to load can lead to many biological and technical implications in the conditions of occlusal forces. Objective The objective of this study was to analyze load distribution in tooth/implant-supported fixed partial dentures with the use of resilient TSA (Titan Shock Absorber, BoneCare GmbH, Augsburg, Germany) abutment and conventional non-resilient abutment using finite element method. Methods This study presents two basic 3D models. For one model a standard non-resilient abutment is used, and on the implant of the second model a resilient TSA abutment is applied. The virtual model contains drawn contours of tooth, mucous membranes, implant, cortical bones and spongiosa, abutment and suprastructure. The experiment used 500 N of vertical force, applied in three different cases of axial load. Calculations of von Mises equivalent stresses of the tooth root and periodontium, implants and peri-implant tissue were made. Results For the model to which a non-resilient abutment is applied, maximum stress values in all three cases are observed in the cortical part of the bone (maximum stress value of 49.7 MPa). Measurements of stress and deformation in the bone tissue in the model with application of the resilient TSA abutment demonstrated similar distribution; however, these values are many times lower than in the model with non-resilient TSA abutment (maximum stress value of 28.9 MPa). Conclusion Application of the resilient TSA abutment results in more equal distribution of stress and deformations in the bone tissue under vertical forces. These values are many times lower than in the model with the non-resilient abutment.Uvod Razlike u odgovoru zuba i implantata na opterećenje mogu imati za posledicu niz bioloških i tehničkih komplikacija u uslovima delovanja okluzalnih sila. Cilj rada Cilj ovog rada je da se analizira distribucija opterećenja kod mešovito nošenih mostova sa primenom rezilijentnog TSA abatmenta (Titan Shock Absorber, BoneCare GmbH Germany), kao i konvencionalnog nerezilijentnog abatmenta primenom metode konačnih elemenata (MKE). Metode rada U ovom radu napravljena su dva osnovna 3D modela. Na jednom implantatu i modelu korišćen je standardni nerezilijentni abatment, a na implantatu drugog modela korišćen je rezilijentni TSA abatment. Na virtuelnom modelu su modelirane konture zuba, PDL-a, sluzokože, implantata, kortikalne i spongiozne kosti, abatmenta i suprastrukture. U eksperimentu je korišćena vertikalna sila od 500 N, koja je primenjena u tri različita slučaja aksijalnog opterećenja. Metodom konačnih elemenata izračunavani su potom Fon Mizesovi ekvivalentni naponi u korenu zuba i parodoncijumu, implantatu i periimplantatnom tkivu. Rezultati Na modelu kod koga je primenjen nerezilijentni abatment, maksimalne vrednosti napona i deformacije u sva tri slučaja su registrovane u kortikalnom delu kosti oko zuba i implantata u zavisnosti od napadne tačke sile (maksimalan napon 49,7 MPa). Vrednosti napona i deformacija na modelu sa primenom rezilijentnog TSA abatmenta pokazale su sličnu raspodelu u kosti, međutim ove vrednosti su višestruko manje nego kod modela sa nerezilijentnim abatmentom (maksimalan napon 28,9 MPa). Zaključak Primena rezilijentnog TSA abatmenta dovodi do ravnomernije raspodele napona i deformacije u koštanom tkivu oko zuba i implantata pod dejstvom vertikalnih sila. Izmerene vrednosti su višestruko manje nego na modelu sa nerezilijentnim abatmentom

Optical stereometric analysis of an experimental partially-edentulous mandible

Stereooptics method have been successfully used in biomechanical studies of dental models. The aim of this study was to investigate, on the basis of functional deformities, the distribution of occlusal loads on the casts of a partially-edentulous mandible without and with dedicated copings. Precise measurement of strain and displacement of partially-edentulous mandibular control and experimental casts were provided by the digital image correlation method and ARAMIS software. Simulated loads ranged from 0 to 1000 N. Displacements and deformations of abutment teeth within the control cast of a partially-edentulous mandible were 0.48% for incisor without coping, 10.29% for canine without coping, and 6.64% for premolar without coping, and within the experimental cast of a partially-edentulous mandible they were 0.29% for incisor with coping, 7.007% for canine with coping, and 4.98% for premolar with coping. Wilcoxon matched pairs signed ranks sum test was not statistically significant for the majority of the examined parameters, except for the differences between deformations of teeth and copings under pressure p lt = 0.05. When loading the abutment teeth, the distribution of strain through the remaining tooth substance is specific and various. Abutment teeth covered by protective copings are more resistant to loads

Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation