The revolutionary role of CAD and CAM in Rehabilitation 

The massive/immense growing technology brings a lot of innovation in each and every field and this is not exceptional for the medical field where new innovations and methods are being proposed to make comfort and ensure better treatment for the people. Rehabilitation is a vast field that restores the condition of good health and help people lead a better life after a trauma/injury.

IMPORTANT FACTORS TO BE CONSIDERED:

There are some important factors to be considered for the rehabilitation devices:

1. The consideration of hygiene
2. The user should be able to clean the orthosis or prosthesis adequately.
3. The cosmesis is the third factor.
   • The third one is much important since appearance is a major factor and has a great psychological importance to the user.
   • Also it provides realistic cosmetic covers for hand or foot prosthesis.

Here comes the role of CAD and CAM which is the advanced technology that brings out the solution for the rehabilitation devices. This technology has changed the physical design of the orthotic and prosthetic devices over the past decade. This provides customized component design to match to the body shape.

In our context, CAD refers to Computer Aided Design and CAM is Computer Aided Manufacturing. CAD is the use of computers to help in the creation, modification and analysis of the design/ model. CAM is nothing but the use of software programs to automate the manufacturing process.

TRADITIONAL METHOD

1. The first step is casting the residual limb in plaster of paris
2. Pouring the mold.
3. Manual rectification and socket fabrication

ADVANCED TECHNOLOGY using CAD/CAM

1. The design of product is done with CAD.
2. Once when the design is completed it can be loaded into CAM.
3. The software in the CAM starts preparing the model for machining.
   • Machining is nothing but the transformation of raw materials into defined shape through cutting, drilling or boring.
4. Once the model is prepared, the information is sent to the machine to produce the part physically.
5. The machine does the process to produce a finished product.

CNC (Computer Numerical Control) machines are widely used to produce the engineered parts. The only human intervention required for running a CNC machine is during the time of

• Loading a program
• Inserting raw material, and then
• Unloading a finished product.

APPLICATIONS OF CAD/CAM IN REHAB

CAD/CAM IN ORTHOTIC AND PROSTHETIC DEVICES:

The problems faced in prosthetic and orthotic devices is the fitting procedure. CAD/CAM brings a solution to this as it can be modified and evaluated until a proper structure is provided.

The procedure involved in creating a prosthesis/orthosis includes 3 steps:

1. Shape capture
2. Rectification
3. Fabrication

SHAPE CAPTURE:

To capture the impression of the patient’s limb, several types of scanners are used. They are structured light scanners and laser based 3D scanners.

RECTIFICATION

The captured image is modified using CAD software. Before printing the modified scan, the file must be prepared for the specific manufacturing technology.

FABRICATION

There are many 3D printing technologies but these three are used in prosthetics and orthotics.

1. Fused deposition modelling (FDM)
2. Selective laser sintering (SLS)
3. Powder bed and inkjet head 3D printing (3DP)

In a survey, 97% reports that adopting CAD/CAM positively impacts on patient’s care.

A prosthetic lower limb should be significantly lighter than the normal since the muscles do not control them. Two technological advances have helped in intelligent prosthetic knee.

1. First, carbon fiber construction has reduced the mass of the lower limb.
2. Second, pneumatic or hydraulically controlled damping mechanisms for the knee joint have enabled adjustment of the swing phase to suit an individual’s pattern of walking.

DENTAL APPLICATION

CAD/CAM is the fastest growing technology in the field of modern restorative dentistry. The prosthetic management of the patients is taken by CAD/CAM by providing a minimally invasive approach. The virtual environment along with onscreen designing and computer assisted production with rapid prototyping allows for fabrication without help of any physical models.

Let us consider a case study where a 25 year old man was dissatisfied with his smile and visited prosthodontics department. He complained about the shape of the teeth, missing of some teeth and also about his unaesthetic smile. He was suffered from agenesis(absence of seven teeth). So, he was carefully observed by his orthodontist for 3 years and has been provided with orthodontic treatment to close the spaces created by the agenesis. His score of oral quality of life was very poor (38/60).

It was necessary to restore the aesthetic and function to improve the quality of his life. But the implant treatment was not possible due to the lack of space, since he had undergone 3 years treatment to close the space. The patient does not want to proceed with the orthodontic treatment. So, a decision was made to place a full-mouth prosthodontic rehabilitation (monolithic lithium disilicate glass-ceramic, IPS E-max CAD).

A software was used for modelling. A complete resin mock up was created and tried for the patient to check whether it works out. After 2 weeks a dental scan was taken for the patient along with that mockup for creating the mold. It was possible to maintain the enamel necessary for bonding. Now a digital cast(mold) is obtained by intraoral scanning according to the patient’s need and the quality was evaluated. After validation, rubber dam was installed to allow optimal bonding. Finally once the teeth has been fixed properly, the rubber dam was removed and the adjustments of prosthetic components was made.

The choice of material for full-mouth restoration in this case was lithium disilicate glass-ceramic (e-MAX, Ivoclar Vivadent). The treatment lasted for 7 weeks. After a month, the score of the oral quality of life was improved (54/60). The use of CAD/CAM systems has allowed time saving, tissue saving, better communication and aesthetic management with the patient during a complex prosthetic treatment. This proves that CAD/CAM is a promising technology.

Modification of the 3-D shape using the CAD/CAM system is done with the click of a mouse versus the manual procedure of mixing and applying of plaster and waiting for a long time for the plaster to set. Thus CAD/CAM technology allows the clinicians to address patients needs with a greater degree of precision. The rehabilitation equipment industry needs flexible design and manufacturing techniques and this is enormously supported by CAD/CAM system.

BENEFITS OF CAD:

• Higher quality designs
• Saves time
• Increase productivity
• Can easily change the designs

BENEFITS OF CAM:

• Greater speed in producing components
• Greater accuracy and consistency
• Greater efficiency

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