50 Shades of Teflon – Part 1
Teflon, or polytetrafluoroethylene (PTFE), is a polymer of tetrafluoroethylene; it´s a plastic non-stick material resistant to high temperatures. Teflon is largely used in several fields industry, from aerospace and computer applications, to cooking pans.
An original article by Giuseppe Chiodera and Giulio Pavolucci
– Very low coefficient of friction (the third-lowest of any known solid material) which results in a high surface smoothness.
– Chemically inert.
– Insoluble in water and in organic solvents.
– Resistant to high temperatures.
– Excellent dielectric properties.
– Its excellent dielectric properties and high melting point make teflon the best material for isolating high performance cables, in aerospace and computer engineering.
– One of most exploited property is the very low friction, which carries the PTFE to be used when high fluency is needed (gears, bearings, engines, etc.).
– In the chemical industry is an excellent insulator, because of its resistance to acids.
– Is widely used as non-stick coating of pots and cooking pans.
– Common plumber teflon tape is used to seal tubes.
– Gore-tex is made with teflon.
There are many other fields in which Teflon is used, including dentistry; in addition to non-absorbable PTFE sutures, it is now easy to find the classic plumber´s teflon tape in a dental office.
It´s non-sticky, moldable, it can be stretched and adapted to the surfaces, it´s chemically inert and it´s really cheap. If necessary, it can also easily be autoclaved at 121° C.
Sometimes in dentistry teflon has been improperly used to isolate the operative field instead of the rubber dam; this is not correct. Teflon tape can sometime be helpful to improve the isolation, but it cannot replace the rubber dam. A correct isolation of the operative field is a necessary condition for all adhesive procedures and for endodontics; the rubber dam is the only tool that can guarantee a correct and stable isolation.
We can find several thickness of teflon tape, like 0,076mm-0.1mm-0.2mm. Probably the most versatile for dentistry is 0.2 mm.
Teflon is very useful in adhesive procedures, once rubber dam has been placed. Thanks to the resistance to acids, it can be applied on the adjacent teeth to protect them from the action of the etchant (Img. 1). It is also helpful to prevent bonding and resin excess, making the finishing procedures easier. This is true for both direct and indirect restorations (Img. 2), in anterior and posterior areas (Img. 3).
Efficient and quick application requires to face a steep learning curve, because the tape must be properly adapted and it must be placed between the interproximal spaces. The tape can be stabilized using a common matrix ring in order to avoid it to be accidentally moved during clinical procedures (Img. 4).
Another way to stabilize the tape is to cover it with a thin layer of bonding and then cure it: Teflon is not compatible with the adhesives but the cured resin hardens the surface.
The isolation of the adjacent teeth with Teflon turns out very useful during indirect restoration luting procedures, helping to control and easily remove the excess of resin cement. If we stretch the Teflon tape we can reduce its thickness, making it thinner than any kind of matrix; nevertheless, it´s important to try the restoration before cementing it, to be sure that it properly seats on the cavity after Teflon placement.
Another application in conservative involves direct posterior restorations: the centripetal build-up technique consists in transforming a class II in a class I restoration, building the interproximal wall and the layering the occlusal part of the cavity. To make the first step we can place a sectional matrix and stabilize it with a wedge. It´s important that the wedge properly separate
the elements, to compensate the thickness of the matrix. A ring is then placed to adapt the matrix to the tooth. The ring is not always able to adequately shift the matrix against the tooth, leaving gaps that will bring to an overcontour and to a more difficult finishing procedure. It often happens in the opposite side of the wedge insertion (Img. 5). Teflon in these cases can be easily compacted in the gap between wedge and matrix, pushing it towards the tooth between the wedge and the tooth itself; this will increase matrix fitting and the accuracy of the restoration (Img. 6 and 7), with a regain of time during finishing procedures.
It sometimes happens that the interdental space is very narrow, so the wedge cannot entirely pass between the teeth; in this case we can push some Teflon tape on the opposite side to better adapt the matrix (Img. 8).
When managing a class I restoration of a tooth with an intact occlusal anatomy, we can take a little impression of the occlusal surface with liquid rubber dam: just placing it on the tooth, putting a microbrush on it and curing it. After isolation, cavity preparation and adhesive procedures, the composite can be layered. The final occlusal layer is not cured and covered with Teflon tape (which acts as an insulator), then the little stamp that has been made with liquid dam is applied over the Teflon. With a gentle and continuous pressure, the occlusal anatomy is easily printed on the non-cured resin. The composite can now be cured and the Teflon easily removed (Img. 9).
Img. 1 – Teflon placed on the adjacent tooth to protect it from the etchant.
Img. 2 – Even during veneer cementation teflon is really helpful to protect adjacent teeth.
Img. 3 – Other examples of teflon used to avoid accidental etching of teeth.
Img. 4 – A matrix ring is perfect to stabilize the teflon tape in posteriors.
Img. 5 – Illustration explaining the application of teflon between the wedge and the matrix.
Img. 6 – Pushing teflon helps to adapt the matrix in second class restorations.
Img. 8 – When the wedge can´t completely pass between the teeth, teflon can optimize the matrix adaptation.
Img. 9 – Teflon is perfect to isolate the non-cured composite and easily stamp the occlusal anatomy.
Teflon is a cheap, easy to find product; it has no expiration date and it is very versatile. In this article, some of its many applications have been listed; its various qualities make it useful to simplify clinical procedures, photographic documentation, and the normal daily practice.