Evidence based materials selection III

Question 1

Aims of manufacturing in healthcare?

Answer 1

Improve pt care

• Reducing costs
• Enabling delivery
• Increasing access

Question 2

What is CAD/CAM?

Answer 2

CAD - computer aided design

CAM - computer aided manufacturing

Question 3

Process of CAD/CAM?

Answer 3

1. Date adquisition
   - A scanner that transforms geometry into digital data that can be processed by a computer
2. Data processing
   - Software that processes date and produces a date set for the product to be fabricated
3. Manufacturing
   - A production technology that transforms the data set into the desired production

Question 4

How does data adquisition occur?

Answer 4

CT
MRI
Laser digitalising (intraoral scanners)
Ultrasound
Mammography
Conventional X-ray

Question 5

Pros and cons of intraoral scanners?

Answer 5

Pros

• Pt comfort
• Dentist auto evaluation
• Reduced model time
• Favours clinic lab communication

Cons

• Cost investment
• Training
• Just surface registration

Question 6

What is required for intraoral scanners?

Answer 6

Further studies to assess reliability, accuracy, reproducibility and scanning times of IOS

Question 7

Data processing steps?

Answer 7

1. Segmentation
   = Allows you to select regions of interest (often different organs)
2. Interpolation
   = Allows you to increase the resolution of the contour
3. CAD package
   = Allows further manipulation of the files obtained

Question 8

Types of CAD packages?

Answer 8

Specialised
- Materialised = expensive

General
- Solidworks/autoCAD/blender = lots of learning resources, varying prices

Question 9

What is subtractive manufacturing?

Answer 9

Controlled material removal process

Question 10

What is additive manufacturing?

Answer 10

Builds objects by adding parts together in layers

Question 11

What are the types of rapid prototyping techniques? (layer by layer manufacturing)

Answer 11

Stereolithography
Fused deposition modeling
Laser powder forming technique

Question 12

What is stereolithography?

Answer 12

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

Question 13

What is fused deposition modelling?

Answer 13

Non laser-based process that builds physical models by depositing layers of thermoplastic material
No post-polymerisation needed
Support material dissolved after model completion

Question 14

What is the laser powder forming technique?

Answer 14

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 wide range of commercially available powders
Self supporting method that allows the parts to be nested together

Question 15

How can we use CAD/CAM technology?

Answer 15

Medical modelling

• Study model
• Pre-plan surgery
• Practice surgery

Drilling and cutting guides

Partial denture frameworks

• Mill or print crown or bridge structures
• Wax burnout or straight to metal
• Post processing required (printing)

Digital orthodontics
Dental/craniofacial implants
- Specific to pt

Question 16

Additive manufacturing techniques?

Answer 16

Selective laser melting

Milling

Question 17

Rapid prototyping limitations?

Answer 17

End manufactured product

• Control/improvement of layer thickness
• Model shrinkage
• Inferior mechanical properties
• Surface finishing

Speed problems
Limitations of materials availability