Composite resin veneers can be of two types

1. The type that are directly formed in the mouth (ie they are not sent to a laboratory for construction.) The material is a soft putty like consistency which is placed onto a tooth which has been primed and bonded. The putty is shaped to look like the front of the tooth and forms a thin coating approximately the thickness of a fingernail over the front of the tooth to change the colour, shape or texture. It is then light cured so it hardens to a rock like consistency. The primary advantage to composite veneers is the fact that they are less expensive. They are also a one appointment procedure and this can be an advantage for patients that are in a hurry or find getting to the dentist a challenge.
2. Laboratory fabricated composite veneers made of a stronger composite, cured under compressed nitrogen and heat for a better cure.

Porcelain veneers

These are formed by a laboratory technician made by melting porcelain powders in a high temperature furnace. In order for the technician to have a tooth shape to work on, moulds have to be made of your teeth and sent to the laboratory where the technician fabricates a replica model of your teeth. The veneers are thin, translucent and tooth like, and approximately fingernail thickness. These veneers are etched internally with a special acid which creates microscopic pores into which the bonding resin engages and locks the veneer securely to the primed and bonded tooth. Porcelain veneers have significant advantages to composite veneers despite their increased cost.

Firstly they are fired in a vacuum furnace, this means that there are no air bubbles in the porcelain after it cools and hardens. This is in distinct contrast to composite veneers which often contain microscopic voids and air bubbles which are not immediately apparent but which fill up with stains (from coffee, tea, red wine and some foods ) and eventually end up as small black dots or fine lines.

Secondly, porcelain veneers have a high glaze which cannot be removed. Composite resin (depending on what type of material is used) does not polish to such a high degree. The highly polishable resins are called microfills and these are more prone to breaking. If they break, it is beyond our control, and it will cost you to have them repaired. The stronger resins which are more suitable for covering incisal edges (which are high stress areas) assume a satin finish rather than a high gloss finish. This can make them more prone to pick up stains from food and drinks. Porcelain on the other hand has strength and high gloss.

The other advantage of porcelain is that the surface texture can be made to mimic that of enamel with very slight ridges, lumps and bumps. The polishing procedure for composite resin generally causes a fairly flat surface texture and the surface does not look as much like tooth as glazed porcelain does.

Composite resin also tends to feather off at the edges next to the gum and in between the teeth, and at those feathered edges it can gradually lose its bond strength to the tooth. This can become evident in the years to come and appear as a brown stain, especially in between the gaps in the teeth. When the trimming and polishing procedures are carried out on composite resin there is only so far we can go into the gaps between the teeth with our polishing apparatus. Porcelain, because of its its' glazed surface, does not need polishing in the gap in between the teeth. It is easily glued in, and because of this there are generally no stains visible on any part of the porcelain veneer, so that it looks beautiful much longer than the composite resin alternative.

Porcelain resin veneers have been used widely around the world since the early eighties. We have a lot more experience with them and their bond strength (although not perfect) is very good and very predictable.

You have to be aware that a small percentage or porcelain veneers will come unstuck and some will break. If you are contemplating having resin or porcelain veneers you should be aware that if something breaks or comes unstuck this is not due to the incompetence or negligence of the dentist, but is merely a fact of life for a small percentage of these restorations.

The biocompatability of porcelain is pretty much undoubted, whereas composite resins have a complex mixture of chemicals which generally do not cause problems, but on occasions there have been reports of sensitivity to the acrylates in certain individuals. There can also be gum irritations caused by some materials in some individuals.Ê Porcelain tends to be more inert and more biocompatible. Porcelain veneers, by virtue of their nature, are very brittle and very stiff, where as composite tends to flex somewhat more. Porcelain in this regard tends to mimic the original, natural tooth enamel which is also brittle, stiff and glass-like. It has been postulated that this stiffness can account for a reduction in sensitivity when biting on veneers. There has been reports of post-operative biting sensitivity with some composite resins and veneers and this is possibly due to the flexibility putting localised pressure on the tooth structure. The porcelain, being stiffer, tends to spread the biting point load pressures over a wider area, and the pressure on the tooth structure remains below the critical level to cause pain. This area is not yet definitively understood, but it is of some interest, especially if you have to have your veneers replaced because of biting sensitivity.

Care of your veneers

1. Flossing is mandatory. It cleans the crevices and keeps the plaque out of the minute dents, voids and ledges that may be around your veneers. If the gum gets red, swells, bleeds and/or feels sore, floss more and use a sonicare toothbrush (see your dentist for more information on the sonicare). If the problem does not go away, come in for an examination. There may be a residual of plastic cement that needs to be filed down or polished.
2. Surface stains can be removed with a more abrasive cleaner - use one or more of the following; a) smokers toothpaste, b) tooth paste rubbed into the stain with a cotton bud, c) dry powdered baking soda used as a tooth paste, d) an ink rubber (from stationary suppliers) rubbed onto the stain (sounds crazy, but it works.) Sharpen rubber to a thin edge to get between the teeth if necessary.
3. Avoid sudden impact stress - absolutely no biting nails, or cutting string with your front teeth. Take extreme care gnawing meat off bones (gently does it)! Cut stone fruit up - sudden impact with a stone can break a veneer.
4. If you grind your teeth, you don't have to have a night guard, but be prepared to pay if you keep loosing or chipping veneers. Some patients seem to get away without night guards, despite grinding, so it's not compulsory, but advised as a safety measure.

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