Dental Tribune India

3D Printing: the latest vogue in Dentistry

By Dr.Ruchi Gupta
March 28, 2018

From defense, aerospace technology, art, jewellery, cloth designing to firearms, 3D printing, an exciting technology is gaining attention of innovative minds. It has been hailed as “revolutionary” in field of medicine and surgery by changing the face of manufacturing products for applied human sciences.

In recent times, 3D printing has gained particular resonance in dentistry. 3D printing is rapid prototyping concept of creating three dimensional objects by additive method. It is the precise printing of a three-dimensional object from a digital file designed in a customized fashion or scanned by 3D scanner.

3D printing is process of depositing fine layers of material and depends on adhesion of each consecutive layer to the previously deposited layer. The material for 3D printing may be available as fluid or powder or as filament. The fluid or powder type of material is contained in a tank provided in the machine and each layer is activated to fuse with previous layer by selective laser sintering. When provided as filament, temperature rise in nozzle is used to melt the filament which is then deposited over previous layers which act as scaffold to support and fuse with consecutive layers.

Since 3D printing is a technology which depends on curing or solidification of existing layer of material before it can support each consecutive layer, lot of time is consumed in making any particular design into a model by this method. Factors which affect this processing time include size of the model and thickness of layers. If thickness of layers is reduced to give a better finish and resolution, it increases number of layers and in turn takes multiple hours to make the model sometimes even days.

Previously, the choices of material were limited and the technology was closed only to select machines and their softwares. Hence, 3d printing was considered  costly and lower to milled objects in strength and quality. Recent advances in material, user-friendly machines and availability of open-ended softwares are bringing 3d printed products closer to daily dental practice. Present materials are not only long-lasting but also have good bonding between layers to provide the strength we need. Also present materials being biocompatible are available for manufacture of end-product rather than just for temporary purpose.

For instance, 3D scanning and printing technology was successfully used by us at V-Invent in the making of D-cleft, a patented innovative device for feeding of cleft palate babies till the time of surgical correction.

The template design of the device was made using modelling wax adapted over the rim of a normal feeding bottle, having an attachment shaped like an inverted spoon with concavity facing towards and parallel to the nipple of feeding bottle. This template of modelling wax was placed over a rotating table and scanned by HP sprout super-computer.

The digital design thus obtained was then modified using Autodesk Alias software. The digital design was modified numerous times to effect optimum functionality. The design was made in variable diameters to easily adapt to different sizes of bottles’ rims and also spoon like attachment was made in different sizes for possible sizes of palatal defect.

The prototypes were 3D printed using fused-filament type of 3D printer with PLA {Poly Lactic Acid} material, which is a strong, bio-degradable, eco-friendly material derived from corn starch, compatible for intra-oral use in infants. D-cleft prototypes were used in subsequent trials for feeding cleft palate babies, with positive feedback from parents and doctors. Only issue faced was rigidity of PLA material, hence another set of prototypes were made using Flexible PLA, which resolved the rigidity issue and rendered more ease in feeding cleft baby.

This example of D-cleft serves to explain the ease of using this new technology for end-product manufacture. In comparison to the above stated example, conventional manufacture of same design by using injection molding technique would not only increase the initial cost of making heavy-duty molds but also reduce any possibilities of altering the size or any other aspects of design which is locked before making the mold.

But, by use of 3D technology the digital design can itself be modified as and when required based on size of cleft  of patient. This provides stronger attachment compared to use of soft-liner which may be used to reline a marginally deficient device.

3D scanning and printing technology is not only helpful in making such innovative devices but also in regular dental work-flow including diagnostic and patient education models, models for treatment planning and mock surgery, precise pattern printed in burn-out material for cast metal prostheses, Surgical stents for implantology and even making custom tools or spares for lab work. When indicated, they are also being used as temporary or permanent prostheses for patients. In most recent advances, anti-bacterial teeth and prostheses are being researched.

3D printed objects are made by using additive technology, hence material wastage is very minimal. The main advantage is that the products can be made with hollow interior which reduces the load of plastic on earth compared to injection molding or milling techniques where the products have solid interior composition. When employed in digital dental workflow, right tools of 3D scanning and printing mean lower cost, fewer mishaps and better results.

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