Basic Dental Materials John J Manappallil
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Dentistry and Dental MaterialsCHAPTER 1

Dental treatment may be divided into 3 phases:
  • Prevention,
  • Restoration, and
  • Rehabilitation.
 
PREVENTION
The preventive phase is probably the most important. This includes educating the patient on how to maintain his oral hygiene through regular brushing, flossing and periodic checkup at the dental office. Regular brushing with a suitable brush and paste has been shown to be very effective at controlling caries as well as gum (periodontal) problems. The role of fluorides and fluoride therapy in the control of dental caries has been known to us for a long time. Fluoridation of drinking water and fluoride therapy at the dental office has played a significant role in reducing dental caries especially in children. Caries often begins in deep fissures in teeth. Fissure sealants is another preventive measure especially in children to prevent caries.
 
RESTORATION
The next stage is the actual development of dental caries and periodontal problems. Caries involves the actual demineralization and destruction of tooth structure. Our next focus is to arrest the caries process. This involves removing the carious enamel and restoring the cavity with a suitable filling material. The famous silver filling has been in use for more than a century and is currently the most widely used filling material. The silver restoration would certainly look unpleasant if used for the front (anterior) teeth. Therefore, we would like to restore anterior teeth with an esthetic (tooth colored) material. Other ways to restore teeth involve the use of gold inlays and ceramic inlays.
As caries progresses, it gets closer to the pulp, which can lead to pain (pulpitis) and infection of the pulp. If the pulp is only mildly affected, pulp therapy is started using special materials which have a beneficial effect on the pulp. These materials 2can be soothing and promote healing by forming a new layer of dentin (secondary dentin).
Once the pulp is infected, we have no choice but to remove the pulp (pulpectomy). This is the next step. This is known as root canal treatment popularly known as RCT. After removing the pulp, the canal is made sterile and sealed using root canal filling materials. The root canal treated tooth is fragile and can fracture if not protected with a crown or onlay.
Sometimes the tooth structure is so destructed and weakened that a simple restoration would not be sufficient. In such a case the tooth is covered with a crown or an onlay. Before the discovery of tooth colored crown materials, metallic crowns were given (the famous gold tooth). Today dentists are able to provide crowns that are natural looking and pleasing. Many of these structures are processed outside the mouth, in the laboratory. The dental technician uses an accurate model of the teeth to fabricate these restorations. How are these models made? The dentist makes a negative record of the mouth called an impression. This is sent to the laboratory where the technician pours a mix of plaster or stone into the impression. When the mix hardens we obtain a model.
If the coronal tooth structure is entirely gone or destructed, even a crown would not stay. In this case the dentist has to place a post and core. The part placed into the root canal is known as post and the rest of it is known as the core. The crown is then constructed and cemented on to the core.
 
REHABILITATION
Unfortunately, the reality is that often patients come too late for any kind of conservative treatment. Hopeless teeth have to be extracted. After extraction the patient often desires that it be replaced with an artificial tooth. There are many ways of replacing the tooth. Today implants have become very popular. A titanium screw can be implanted into the jaw surgically followed by an artificial crown. The implant is quite an expensive proposition and involves surgery.
The next choice is the fixed partial denture (bridge). Usually the teeth by the side of the missing tooth is reduced in size (prepared) in order to receive the bridge. The bridge is then cemented on to these teeth.
If too many teeth are missing, we might have to consider the removable partial denture which replaces the missing teeth but is not fixed in the mouth. It can be removed by the patient for cleaning and hygiene. The ideal removable partial denture is usually made of a combination of metal and plastic (cast partial denture). It can be made entirely of plastic also and is referred to as a treatment partial denture.
The final stage is of course when all the teeth have to be replaced. One is of course familiar with the complete denture which is often seen in elderly individuals. These artificial teeth replace the entire dentition and is usually of the removable type (fixed complete dentures are also available which are supported and retained by implants). 3The complete denture is usually made of a type of plastic called acrylic. The teeth used in the denture can be made of acrylic or porcelain.
Besides all the materials mentioned above, different specialties in dentistry have their special materials. Some of these are not covered in this book. For example, endodontists use special medicaments to clean and debride the root canal. A variety of root canal sealing pastes and medicaments are also available. The periodontist uses different types of graft material to restore lost periodontal bone. Unfortunately, not all the materials used in dentistry are within the scope of this book.