Advanced manufacturing and related technologies in dentistry Flashcards
Manufacturing techniques (3_
Conventional methods: Impression techniques -cheap -easy to use -high skills -subjective Subtractive - milling -'low' investment -simple shapes New methods: Additive - rapid prototyping -complex shapes -translucent -materials -training
What i CAD/ CAM? (3)
- Data acquisition
- Data processing
- Manfacturing
Data acquisition (6)
Data acquisition for the existing structure of interest. • Computerised tomography (CT) • Magnetic resonance imaging (MRI) • Laser digitalising • Ultrasound • Mammography • Conventional X-ray
Computerised tomography (2)
Radiographic technique for producing cross-sectional images by scanning a
slice of tissue form multiple directions using an arrow fan-X-ray
Magnetic resonance imagine (2)
Images obtained based on different tissue characteristics by varying the
number and sequence of pulsed radio frequency fields in order to take
advantage of magnetic relaxation properties of the tissues
Laser surface digitalising (LSD) (3)
A diode–based laser beam is split into a plane of laser light that comes out of the probe and shines below on the surface of the object being scanned. Thus a profile on the surface of the part is formed.
=intra-oral scanners!
Intra-oral scanners - pros and cons (7)
Pros: -pt comfort -dentist auto evaluation -reduced model time -favours clinic-lab communication Cons: -cost investment (coating) -training -just surface registration
Current literature lacks of sufficient evidence to
provide solid information regarding the use of
intraoral scanners under clinical conditions (3)
For example, in 2017 only 4 published studies reported on
validity, repeatability and reproducibility of digital
measurements.
Current reviews highlight the scientific evidence collected
on intraoral scanning is neither exhaustive, nor updated.
Not all the commercially available scanners have been
tested in the clinical setting
Data processing (3)
Segmentation: selection of the regions of interest
Interpolation: to increase the resolution of the contour
CAD package: further manipulation of the files obtained
Segmentation (2)
Identifying and dividing the images into areas of interest • Often different organs • Or sections of organs Automated processes exist • Not always accurate
Specialised CAD packages (2)
Materialise
Specifically designed/ highly
specialised
Expensive
General CAD packages (3)
Solidworks/ AutoCAD/ Blend er Lots of learning resources Multiple applications Varying prices
Subtractive vs additive manufacturing (2)
Subtractive Manufacturing: controlled material-removal process (Machining)
Additive Manufacturing: builds objects by adding parts together in layers
Rapid prototyping techniques (layer-by-layer techniques (3)
- Stereolithography
- Fused deposition modeling
- Laser powder forming technique
Stereolithography (2)
• Additive fabrication process based on the spatially
controlled solidification of a liquid resin by
photopolymerisation.
• Cure depth given by the energy of the light to which the resin is exposed
Stereolithography: available materials (6)
WATERSHED Medical prototyping USP grade VI approved XTREM Very tough Functional testing Si25 Snap fits, concept models and functional assembly components Si60 Production of prototype models requiring some level of transparency BLUESTONE Water handling components High temperature applications CERAMAX Ceramic based material Aesthetic and functional components
Fused deposition (3)
- Non laser-based process that builds physical models by depositing layers of thermoplastic material
- No post-polymerisation needed
- Support material dissolved after model completion
Fused deposition steps (4)
Material feeding –> model fabrication –> support material removal –> final model
Fused deposition - available materials (5)
ABS Strong, functional, smooth parts with good feature detail NYLON Higher elongation at break Good impact strength PC Accurate, durable, strong, stable Functional testing; imaging & RF transparent ABS-M30i Bio-compatible (ISO 10993; USP Class VI) Gamma & EtO sterilizable PC-ISO Bio-compatible (ISO 10993; USP Class VI) Gamma & EtO sterilizable Imaging & RF transparent Strong and rigid
Laser powder forming technique (3)
• A high power laser is directed to a fine layer of powder
substrate using mirrors. The beam creates a melt pool
and the powder particles melt together
• Can produce parts from a relatively wide range of
commercially available powders
• Self-supporting method that allows the parts to be
nested together
Laser powder forming steps (4)
Material feeding –> model fabrication –> removal from the base –> final product
Laser powder based technique: available materials (5)
POLYMERS Polyamide Nylon Polyethilene COMPOSITES Mixtures of polymers Polymers and hydroxyapatite CASTING WAX METALS Steel Ti and Ti-alloys Co/Cr alloys CERAMICS
Medical modelling (4)
• Study model • Pre-plan surgery • Practice surgery • Especially useful is unusual anatomy
Drilling and cutting guides (3)
• Allow for highly accurate surgery • Increases speed and confidence of placement • Based on CT scan
Partial denture frameworks (3)
• Mill or print crown or bridge copings/structures • Wax burnout or straight to metal • Post-processing required (printing)
Digital orthodontics (4)
• Based of CT data • Software predicts/plans route • Print out models • Design/ plan metal work
Dental/ craniofacial implants (3)
• Produce complex geometry • Porous/rough surface • Specific to patient
Additive manufacturing: current applications in dentistry (3)
SLM
- 3D printed cobalt chrome
- crowns’ bridges
- partial dentures
BUT……ARE ALL THE INNOVATIVE
APPROACHES AND COMPANIES
GOING FOR ADDITIVE? (2)
Not really
Some new companies are still milling e.g. Juvora
-cheaper
Additive manufacturing and the dental community (4)
• “Competition” with traditional manufacturing in creating end-use materials
• Transformation of the highly skilled labour// INVESTMENT
• High number of complex products made simultaneously
• Complex shapes at “affordable prices” with little waste
material
Rapid prototyping limitations (3)
End-Manufactured Product
Control/improvement of layer thickness
Model shrinkage
Inferior mechanical properties (in some cases)
Surface finishing /Post-processing
Speed problems (although multi-product manufacture can be achieved)
Limitation of materials AVAILABILITY
