|Year : 2016 | Volume
| Issue : 2 | Page : 16-21
A Review of CAD -CAM in Dentistry
Krishnan Amudhalakshmi1, Arthi Sethalakhsmi2, Krishna Prasad Biswas2
1 Associate Professor MDS, Dept. of Conservative Dentistry & Endodontics, Govt. Dental College, Chennai, Tamil Nadu, India
2 MDS, Dept. of Conservative Dentistry & Endodontics (P.G. Student), Govt. Dental College, Chennai, Tamil Nadu, India
|Date of Web Publication||17-Aug-2016|
Associate Professor MDS, Department of Conservative Dentistry & Endodontics, Govt. Dental College Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Amudhalakshmi K, Sethalakhsmi A, Biswas KP. A Review of CAD -CAM in Dentistry. J Indira Gandhi Inst Med Sci 2016;2:16-21
| Introduction:|| |
In dentistry, we have a long history of contributing to the needs of patients by offering dental restorative and prosthetic devices such as inlays, onlays, crowns, fixed partial dentures (FPDs), and removable dentures, to recover patients’ oral function and maintain their health. In the past two decades, exciting new developments in dental materials and computer technology have led to the success of contemporary dental computer-aided design/ computer-aided manufacture (CAD/CAM) technology. Several highly sophisticated in-office and laboratory CAD/CAM systems have been introduced or are under development. The technologies that have made the use of three-dimensional (3D) digital scanners an integral part of many industries for decades have been improved and refined for application to dentistry.
In dentistry, the major developments of dental CAD/CAM systems occurred in the 1980s. There were three pioneers in particular who contributed to the development of the current dental CAD/CAM systems.
Dr. Duret was the first in the field of dental CAD/CAM development. From 1971 he began to fabricate crowns with the functional shape of the occlusal surface using a series of systems that started with an optical impression of the abutment tooth in the mouth, followed by designing an optimal crown considering functional movement, and milling a crown using a numerically controlled milling machine. Later he developed the Sopha System, which had an impact on the later development of dental CAD/CAM systems in the world. The second is Dr. Moermann, the developer of the CEREC, He attempted to use new technology in a dental office clinically at the chairside of patients. He directly measured the prepared cavity with an intra-oral camera, which was followed by the design and carving of an inlay from a ceramic block using a compact machine set at chair-side. The third is Dr. Andersson, the developer of the Procera. At the beginning of the 1980s, nickel-chromium alloys were used as a substitute for gold alloys because of the drastic increase of gold prices at that time. However, metal allergies became a problem, especially in Northern Europe, and a transition to allergy-free titanium was proposed. Since the precision casting of titanium was still difficult at that time, Dr. Andersson attempted to fabricate titanium copings by spark erosion and introduced CAD/CAM technology into the process of composite veneered restorations.
[TAG:2]Overview of Dental CAD/CAM[/TAG:2]
A revolution has happened in the field of dentistry, with the introduction of laser technology, 3D computer aided designing (3D-CAD) and computer aided manufacturing (CAM) also known as rapid prototyping or free form fabrication (FFF).
After the abutment teeth are prepared, with the aid of computer-assisted technology, abutment teeth are directly digitized inside the oral cavity with the help of intra oral cameras, instead of taking conventional impressions. Restorations are designed on a computer monitor using CAD software based on the digitized data as a virtual wax-up. Finally, restorations are processed by a computer assisted processing machine, usually a milling machine.
Recently, data for the abutment that are digitized at the satellite office are transferred via the internet to a processing center based anywhere in the world. Frameworks fabricated at the center are then delivered to the satellite office to complete the restorations by layering porcelains.
| Components of CAD-CAM:|| |
- A digitalisation tool/scanner that transforms geometry into digital data that can be processed by the computer.
- Software that processes data and, depending on the application, produces a data set for the product to be fabricated
- A production technology that transforms the data set into the desired product.
[TAG:2]Classification of CAD-CAM Systems:[/TAG:2]
CAD-CAM systems may be categorized as either-
A- In office-chair side
B- Laboratory systems
C- Copy milled.
A-CHAIR SIDE CAD-CAM SYSTEM
Design-when creating a chair side CAD-CAM filling, the dentist makes a digital picture of the prepared tooth with a small intraoral camera. This digital image contains three-dimensional informations about the size of the tooth and defect being restored, as well as the adjacent teeth. Then designing the desired filling directly on a computer screen using CAD-CAM software. Once all of the pertinent information has been entered (like type of filling, contours) a tooth colored block of ceramic or composite material is machnined by fine diamond drills to produce the designed filling.
The CAD-CAM filling is then tried in mouth, adjusted, polished and bonded in place with a composite resin bonding cement.
| Laboratory CAD-CAM Systems:|| |
CAD-CAM technology is the only way to create zirconia copings because the design program is able to adjust precisely for the shrinkage caused by sintering.
A common way for laboratories to use CAD-CAM is for the laboratory to scan the stone model with a digital scanner, after the waxing up the model, a second scan is done. The design program combines the 2 images digitally to determine the form of the restoration.
| Copy Milling:|| |
It is the mechanical shaping of an industrially prefabricated ceramic material, which is consistent in quality and its mechanical properties (an improvement over conventional ceramics). Copy milling includes fabrication of a prototype (pro-inlay or crown) usually via impression making and model preparation. Based on the model, a replica of inlay/ crown is made and fixed in the copying device and transferred 1:1 into the chosen material such as ceramic.
[TAG:2]Review of Various CAD-CAM Systems 4, 5, 6, 7, 8 CEREC System:[/TAG:2]
CEREC (Ceramic Reconstruction) is a dental restorations product that allows a dental practitioner to produce an indirect ceramic dental restoration using a veriety of computer assisted technologies, including 3D photography and CAD-CAM. With CEREC, teeth can be restored in single sitting with the patient, ratherthan the multiple sitting.
| Initial Design of preliminary CERAC : (Werner Moremann & Dr. Macro Brandestini Dec 1980)|| |
To achieve the needs of an expeditious chair side fabrication of ceramic restorations, the initial technical CEREC concept comprised a small mobile CAD-CAM unit integrating a computer with a monitor and keyboard, track-ball ,foot-pedal, and optoelectronic 3D-scanning mouth camera as input devices.
| CEREC 2 System:|| |
The CEREC 2 unit (Siemen/ Sirotra), based on the process developed by Moreman & Brandestini was introduced in September 1994 and is the result of constant further development via different generations of CEREC units lo eliminate the previous limitations.
| CEREC 3:|| |
It is a modular CAD/CAM system for creating all ceramic restoration the course of a single treatment session and is the hardware basis for the new 3D software The system consists of 2 separate components
Esthetics and strength are improved compared to CERAC 2-an imaging unit and a milling unit.
| CEREC AC:|| |
The new CEREC AC gives dentists the choice of implementing in-office fabrication or sending the digital images with CEREC CONNECT directly to the laboratory, where the restoration can either be milled directly or a model can be created for traditional fabrication of the restoration. Transfer to the laboratory is only possible if the laboratory has CEREC CONNECT. The scanner operates using visible blue light emanating from light emitting diodes (LEDs) with shorter wavelengths of light than previous CEREC models, increasing the accuracy of the scan. The CEREC MC XL milling center can be used to create full contour crowns in six minutes. Alternatively, the MCL Compact Milling Unit can be used. All types of indirect restorations can be created.
| E4D (D4D Technologies):|| |
The E4D [Figure 1] can be used for all fixed restorations except bridges and implants, and will scan up to 16 restorations. The E4D Dentist chairside CAD/CAM system uses laser dentistry to design tooth restoration. The E4D has separate scanning and milling units within a cart, with automated interunit communication. The scanner reflects light from directly above the tooth, using a red light laser oscillating at 20,000 cycles per second to capture the series of images and create a 3-D model. The E4D does not offer the opportunity to scan and digitally transfer the images to a laboratory. It allows dentist to see many aspects of tooth not available on other imaging systems, including enamel, dentin and even stains.
The iTero chairside digital impression scanner utilizes parallel confocal imaging to capture a 3D digital impression of the tooth surface, contours and gingival structure. It captures 100,000 points of laser light and has perfect focus images of more than 300 focal depths. The system captures 3.5 million data points for each arch. The scanner has the ability to capture preparations for crowns, bridges, inlays, and onlays. Parallel light emission from the scanner, which does not need to be held a set distance from the tooth and will also scan when touching the teeth, enables the detection of angled contours. For each preparation, a facial, lingual, mesio-proximal and disto-proximal view is recorded in around 15 to 20 seconds, after which the adjacent teeth are scanned from the facial and lingual aspect. After the images have been captured, the digital impression is transmitted to the manufacturer’s facility and to the selected dental laboratory. The manufacturer mills the models on a 5- axis milling machine, using a proprietary resin material. Simultaneously, the dental laboratory technician can export the digital impression file to his or her CAD/CAM system and begin fabrication of copings and/or full coverage restorations.
| CICERO System:|| |
Computer Integrated Ceramic Reconstruction (Elephant industries). The CICERO method of crown fabrication was developed at the Academic Center of Dentistry Amsterdam (ACTA) and consists of optically digitizing a gypsum die, designing the crown layer build-up, and subsequently pressing, sintering, and milling consecutive layers of a shaded high-strength alumina-based core material, a layer of dentine porcelain, and a final layer of incisal porcelain. Final finishing is done in the dental laboratory. The CICERO method allows efficient production of all-ceramic restorations without compromising esthetics and function. The unique feature of the Cicero system is that it produces Crowns, FPD’s and inlays with different layers such as metal and dentin and incisal porcelains, for maximum strength and esthetics.
COMET System (Coordinate Measuring Technique, Steinbichler Optotechnik, Neubeurn, Germany).
It is a laboratory CAD/CAM system. It uses stone cast to take impression. This system allows the generation of a 3-dimensional data record for each superstructure with or without the use of a wax- pattern. For imaging, 2-dimensional line grids are projected onto an object, which allows mathematical reproduction of the tooth surfaces. It uses a pattern digitization and surface feedback technique, which accelerates and simplifies the 3-dimensional representation of tooth shapes while allowing, individual customization and correction in the visualized monitor image.
| CELAY System:|| |
The Celay System (Mikrona AG, Spreintenbach, Switzerland) became first commercially available in 1992. It is a high precision, manually operated copy milling machine and the fabrication principle is the same as for ‘Key’ duplication. This system was originally designed and intended for use in the dental laboratory, however it may also be used at the chairside. A prototype resin coping of the restoration (prototype) called ‘pro-inlay’ (a provisional inlay) is fabricated on the die using a blue light-cured resin (Celay-Tech, Mikrona Technologies, AG, Switzerland). The cured resin prototype is removed from the die and fixed on the left side of the relay unit using a special retaining device (rod shaped). A prefabricated ceramic blank (eg. - aluminous core ceramic ‘In- Ceram’) is fixed in the carving chamber on the right side of the relay unit. Milling is done by duplicating the movements of the reference disk, the rough milling disk (a coarse diamond instrument with a grit size of 126 ?m) and a high speed turbine driven by air pressure.
| Sopha System:|| |
This sophisticated French system, invented by Duret, Allows for the production of inlays, anterior and posterior crowns and bridges. It also permits consideration of both static and dynamic occlusal factors. An impression of the tooth is taken using a laser imaging system and holography. Information from the light source is then digitized by the camera, presented on a video display and transferred to a CAD/CAM program that creates a model of the preparation. The complex software allows the dentist to access a library of theoretical teeth, which may be adapted and modified according to the requirements of the oral situation.
| Dux System:|| |
The Dux system, also known as the Titan system (DCS, Dental Allschwill, Switzerland) consists of a miniature contact digitizer, a central computer and a milling unit. The manually operated tracing unit, which is said to have an average accuracy of 3μm, consists of a table that shifts a die or model beneath a contact stylus.
The central computer converts the three-dimensional model data into a CNC milling programme. Titanium crown and bridge substructures may be produced using this technique.
| DentiCAD:|| |
The DentiCAD system (BEGO, Bremen, Germany and DentiCAD, Waltham Mass, USA) consists of a miniature robot arm digitizer, CAD/CAM software with a facility for fully automated design and a milling machine. The robot arm can be used either intra- orally or indirectly on conventional dies or models. The milling process is directly controlled by computer.
| Lava System:|| |
The Lava all-ceramic system (3M ESPE Dental Products, Seefeld, Germany) also uses a CAD/CAM procedure, to produce a framework consisting of a Y-TZP-based ceramic supplemented by a specially designed veneer ceramic.
It is a laboratory system of fabrication of restorations. The frameworks are fabricated using contemporary CAD/ CAM procedures (scanning, computer-aided framework design and milling) from presintered Y-TZP blanks. The shade of the core material may also be stained to correspond with 1 to 7 shades of the Vita Classic shade system resulting in the ability to develop shading of the restoration., the Y-TZP core utilized for the Lava system has been considered to exhibit increased translucency in comparison with other zinconia-based ceramic core materials. The manufacturers have suggested that an ideal translucency may be achieved as a result of inherent material properties and a low wall thickness.
| Procera System:|| |
Procera system is unique CAD/CAM technology system for fabrication of esthetics and functional dental restorations in laboratory. There’s a seamless solution for every indication, whether it’s crown, bridges or implant abutments. The versatility of procera system allows to incorporate it into practise.
| Turbodent:|| |
The TurboDent System (TDS) milling center, with its headquarters in Taiwan, began full production in 2005. With this system, the operator scans the stone model and wax-up with the TDS Scanner, and the dental prosthesis is designed by the operator using the TDS Designer. The TDS Designer is a design software package that includes a digital wax-up tool and a comprehensive library of wax-up designs, enabling various prostheses designs to be input and modified by the operator. The five-axis TDS Cutter is capable of milling a wide range of restorations, such as inlays, onlays, veneers, copings, bridge frameworks, custom implant abutments, and implant bars, from titanium or ceramic material. Like the Procera system, casts and dies may be scanned from anywhere in the world using the TDS Scanner and electronically transmitted to the milling center for design, fabrication and finishing.
| DCS Precident:|| |
The DCS Precident system is comprised of a Preciscan laser scanner and Precimill CAM multitool milling center. The DCS Dentform software automatically suggests connector sizes and pontic forms for bridges. It can scan 14 dies simultaneously and mill up to 30 framework units in a single, fully automated operation. Materials used with DCS include porcelain, glass ceramic, Vita In-Ceram, dense zirconia, metals, and fiber-reinforced composites. This system is one of the few CAD/CAM systems that can mill titanium and fully dense sintered zirconia.
| Everest:|| |
Introduced in 2002, the Everest system consists of scan, engine, and therm components. The operator fixes a reflection-free gypsum cast into the scanning unit where it is scanned by a CCD camera in a 1:1 ratio, with an accuracy of measurement of 20 µm. The system automatically generates a digital 3D model by computing 15-point photographs. The operator then designs the restoration on the virtual 3D model with Windows-based software. The machining unit has five-axis movement that is capable of producing detailed morphology and precise margins from a variety of materials including leucite-reinforced glass ceramics, partially and fully sintered zirconia, and titanium. Partially sintered zirconia frameworks require additional heat processing in its furnace. The marginal adaptation for Everest crowns was reported as 32.79 (± 6.82) μm and 33.72 (± 6.69) μm.
| Cercon:|| |
Also launched in 2002, the Cercon system initially was referred to as a CAM system because it did not have a CAD component. At that time, the operator needed to make a wax pattern (coping) with a minimum thickness of 0.4 mm. Subsequently, the system scanned the wax pattern and the Cercon Brain milling unit milled a zirconia coping from proprietary presintered zirconia blanks. The coping then was sintered in the Cercon Heat furnace (1,350oC) for 6 to 8 hours. A low-fusing, leucite-free Cercon Ceram S veneering porcelain was used to provide the esthetic contour. In 2005, DENTSPLY Ceramco introduced the Cercon Eye 3D laser optical scanner and Cercon Art CAD design software.
[TAG:2]Recent Advances in CAD/CAM9,,,,: Haptic Technology:[/TAG:2]
An adjunct technology recently added to the available systems is Haptic technology (Sensable Technologies). This is a virtual wax up system whereby the technician can sit in front of a computer screen looking at a 3D model, holding a computerized wax spatula (actually an elaborate computer mouse) place wax on dies, and even create partial frameworks, retention bars and other devices with a tactile feedback that feels like the operator is touching a model. These wax ups can then be created by a CAD/CAM system. Haptic technology is also being applied for virtual cavity preparation for endodontic procedures.
| 3 Shape Dental System:|| |
3 Shape’s Dental System 2009 is the most versatile CAD/CAM system3Shape’s Dental System.
Includes the high-performance D700 laser 3D scanner, the intuitive Dental Designer CAD modelling program and the Dental Manage.
| D700 Scanner:|| |
Building on the functionality of 3Shape’s previous scanners, the D700 represents the culmination of 3Shape’s scanning expertise. This revolutionary scanner is optimized for impression scanning, and is capable of scanning full dental gypsum models up to 40% faster and with greater details than 3Shape’s previous D640 scanner. The D700 also offers reduced temperature sensitivity. Easy and quick object fixation followed by click-on one button in the scanning software makes the scanner easy to use and requires a minimal amount of training. The D700 scanner scans all colours, meaning that laser and camera parameters are automatically adjusted to the material of the scanned object.
| Intrascan 3D:|| |
The entire camera technology is integrated in the hand-piece that weighs only 720 grams. The intrascan 3D is connected simply by USB cable plug and play to PC/ laptop. The digital acquisition the oral situation happens in real time and is displayed digitally in exoScan software as 3D model. The scanning process can be interrupted at any time and can be continued after drainage.
| Spectro Shade:|| |
SpectroShade is a technological achievement in the range of colorimetric analysis and the global communication. The patented SpectroShade system consists of a digital camera and is connected to a LED spectrophoto- meter, a device for identifying colors which has proved to be more effective than the human eye. SpectroShade recognizes the color shades of the teeth or dental prosthesis with high precision. Hence, the color shades can be adjusted perfectly according to the shades of the teeth themselves or the color scale in order to reconstruct the teeth with the necessary materials. This advanced communication device has been developed in order to avoid arising incongruities of color shades while conveying photos between dentists and dental technicians.
| CERAC Omnicam:|| |
The latest development is the CEREC Omnicam intraoral camera, which was launched on the market in 2012 and facilitates powder-free digital impressions in natural colors. CEREC technology from Sirona Dental is recognized as the pioneer of the “direct/indirect” digital impression capture category. Has a 3D stereo lithography printed resin model option for the execution of multiple-unit complex- treatment protocols.
| E4D Planscan (D4D technology):|| |
Scanner has advanced settings that facilitate longer and more accurate scans such as heated mirror tips, heat dissipiating fans and blue laser. Video rate scanning and tuned- bolt connectivity to Plan CAD laptop Scanner captures and processes data almost as quickly as dentist moves hand. Iris adjustable field of view allows adjustment of capture window to avoid lips, tongue and cheeks. The auto-focus feature eliminates the depth-of-field issue, allowing the operator to rest the camera on the unpowdered teeth
| Conclusion:|| |
Dental CAD/CAM technology is successful today because of the vision of many great pioneers. CAD/CAM systems offer automation of fabrication procedures with standardized quality in a shorter period of time. They have the potential to minimize inaccuracies in technique and reduce hazards of infectious cross contamination. It allows application of newer high strength materials with outstanding biocompatibility combined with adequate mechanical strength, provisions for esthetic designs, excellent precision of fit and longetivity. However, these advantages must be balanced against the high initial cost of CAD/CAM systems and the need for additional training.
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