Artificial teeth used to make dentures can be made of porcelain, acrylic resin, or composite resin. Here we will be looking at the most commonly used ones-porcelain teeth and acrylic resin.
Let’s first look at the requirements of good artificial teeth:
- Good appearance. They should resemble the natural tooth as far as possible in shape, colour, translucency and dimension.
- Good attachment of the teeth to the base of the denture,as it is reported that 33% of all denture repairs are required due to debonding of teeth
- Should not adversely affect the base material, i.e. the teeth and base should be compatible.
- Of low density so that they do not increase the weight of the denture which will be inserted in the mouth.
- Strong and tough to resist fracture.
- Hard enough to resist abrasive forces in the mouth and during cleaning, but allows trimming with a dental bur to allow adjustments to be made by the dentist at the chairside.
The first porcelain dentures were made around 1770 by Alexis Duchateau. In the past, artificial porcelain teeth were generally preferred over plastic teeth due to their greater durability and esthetics.
Advantages of porcelain teeth
- Although both acrylic and porcelain teeth can be made to give a natural appearance, the slightly greater translucency and depth of color achieved with porcelain possible gives this material a slight advantage.
- Harder than acrylic-more durable.
- Resist wear– this preserves the normal jaw movements and alignment for a longer period.
- Resist staining
- Occasionally, due to resorption of the edentulous ridges, the denture becomes loose and does not fit the mouth at all. Instead of remaking a new denture, the base of the denture can be replaced (called “rebasing”) while retaining the artificial teeth so that the way the teeth come together (occlusion) will not be altered. Because porcelain teeth do not bond chemically to the base, they are easily removed from the base for this purpose.
Disadvantages of porcelain teeth
- Dentures made with porcelain can be noisy: clicking sounds are made when porcelain teeth comes into occlusion with another porcelain tooth
- Brittle – more likely to fracture than acrylic teeth
- Do not bond chemically to denture base – attachment is achieved my means of mechanical bonding. Small holes or metal pins are incorporated in the base of porcelain teeth during their production to enable mechanical bonding to the denture base.
- Not as compatible as acrylic teeth with the base of the denture – There is a serious mismatch in coefficient of thermal expansion(how much a substance expands under a given temperature) and modulus of elasticity between porcelain and acrylic resin. This may lead to crazing and cracking of the denture base in the region around the base of the porcelain teeth.
- Its density value is about twice that of acrylic teeth; dentures constructed with porcelain teeth are much heavier.
- Difficult to fabricate
- Difficult to trim, due to the hardness of this material
- Porcelain teeth exert more force to the underlying supporting soft tissues, causing more trauma to these tissues. This is a function of the greater modulus of elasticity of porcelain. This trauma is capable of accelerating the rate by which the underlying bone resorbs.
- If a denture is going to be worn against opposing natural teeth than plastic teeth should be selected because porcelain teeth, being harder, could excessively wear natural teeth away.
This is the same material used in fabricating the base of an acrylic denture. It is primarily made of polymethylmethacrylate polymer.
Advantages of acrylic teeth
- Easy to adjust and trim
- Chemical bonding to denture base, as they are made of the same material
- Acrylic teeth are more compatible with the denture base than porcelain teethNo clicking sound
- Easy to fabricate
- Less trauma to denture-bearing area. This is particularly crucial for people with implants supporting the fake tooth. If they have lost bone or gum tissues around the implant, acrylic teeth are more forgiving when you grind your teeth, and will hold their position longer than porcelain teeth.
- Dentures made with acrylic teeth are lighter.
Disadvantages of acrylic teeth
- Acrylic teeth are susceptible to abrasion, e.g. if the patient has a habit of teeth-grinding (bruxism) or eats abrasive diets, the teeth will wear down with time, causing changes in the length of the teeth.
- Easily stained, as they contain microscopic pits that can hold bacteria
- In rebasing, difficult to remove acrylic teeth from the denture base
Nowadays most dentures are made using acrylic teeth, but regardless of which type of tooth is chosen, the success of the denture is dependent upon proper care and regular checking of your denture.