Dental Clinical Articles

Posted: 14 February 2011

Partial Dentures : How to get it right

Author: Joe Law

Partial dentures should be strong, flexible, comfortable and easy to work with. Joe Law advises on how to get the best results with them.

Dentists worldwide who prescribe partial dentures have certain key requirements. When it comes to partial denture treatment, Sunflex’s partial dentures provide dentists with a dense, stain-resistant product, that won’t warp, discolour or become brittle, when good oral hygiene is maintained. (Heavy smoking, spiced foods and some medications could cause staining.)

They are made using a specialised form of nylon from the family of Superpolymides, a pure nylon resistant to chemical deterioration that is virtually unbreakable, and because of their compressive, impact and bending strength, the raw material comes with a lifetime guarantee. They are also formulated to be as flexible as possible for maximum comfort.

They can be used as short (2-3 teeth extensions) bilateral (Figure 1) or unilateral dentures, an implant healing partial, and can also be prescribed in combination with cast metal frameworks to provide better stability for free end-saddle cases (Figure 2).

Fitting partial dentures

No tooth preparation is required to make the impressions. Instead, a master cast is poured immediately from an alginate impression that is then sent to the laboratory, along with opposing model and bite registration.

They stay translucent after processing, and adapt to a variety of natural tissue shades as the resin is available in four different tones, for which complimentary shade guides are available.

To guarantee their smooth placement and that they adapt well to the natural tissues in the patient’s mouth, the Sunflex partial must be immersed in hot tap water for about two minutes prior to insertion. Once cooled to a tolerable temperature, it is then inserted gently in the patient’s mouth. If a clasp is too tight, it can be loosened slightly by immersing it again in hot water for 30 seconds and bent outward under cold water. If a clasp is loose, the same procedure can be used, while bending it inward, while the resin will retain its position once cooled. Each adjustment should be taken off the model and done by hand.

Chairside adjustments

Sunflex Partials’ properties mean chairside adjustments can be easily made without the material gumming or flaking. For best results, this can be done with the Sunflex Tool Kit, a set of burs especially designed to be used with the Sunflex thermoplastic resin (Figure 3).

The green silicone-carbide abrasive bur provides fine adjustments with little roughness on the surface, and is used to relieve tissue-contacting areas, reduce periphery edges and diminish insertion and removal difficulty. The green and brown rubber point provides even smoother reduction, and the brown rubber point rubberises, smoothes and pre-polishes the surface.

Too much pressure could burn or distort the partial, so it’s crucial to vary the contact point repeatedly and use the lowest speed on the hand piece for all burs. With continuous trimming in one direction, moving the handpiece towards you, apply only slight pressure to avoid surface burn.

Although this is unlikely to happen when the green point is used properly, polishing can be done with a coarse pumice and brown tripoli on a soft rag wheel, followed by the use of an acrylic-polishing mix for high lustre.

Additions / rebase

Sunflex resin teeth and clasps can be added without demarcation lines and, although it easily adapts to subtle changes in the mouth, if necessary, it can be rebased in the lab.

If a tooth, clasp or saddle need to be added, an alginate impression with the partial in place should be taken, poured immediately and sent to the laboratory with instructions. For a rebase, the tissue side of the partial must be clean and all adhesives must be removed. A rubber-base impression in a closed-mouth position is taken, followed by an alginate pickup impression that is poured immediately, and it’s crucial that the partial is not separated from the model when sent to the laboratory.