Diseases of the Teeth

Adults have 32 permanent teeth, including the incisors, canines, premolars, and molars. As shown in Figure 1, the crown of a tooth rises above the gingiva, and the root is the portion embedded in alveolar bone. The periodontal ligament suspends a tooth and its roots in the bone and is made up of collagen fibers. The major component of teeth is a bone-like substance called dentin. Inside the tooth lies the pulp, containing blood vessels and nerves. The crown is covered by enamel and the roots are covered by cementum.

Fig.1 Tooth Anatomy

Diseases of the teeth are frequently identified by clinical inspection of the oral cavity and by x-ray examination. Common radiographs include periapical views to identify the crown and root, bite-wing radiographs to examine the interproximal spaces, occlusal views to image large segments of the dental arch, and panoramic views to identify both dental arches and their supporting structures. Periapical, bite-wing, and occlusal radiographs are intraoral films made by placing film inside the patient's mouth and directing the x-ray beam through the area to be imaged. Panoramic radiographs, which are extraoral films requiring special equipment to obtain, are frequently used since they can display the entire maxillomandibular region on a single film.

Dental caries, or injury and destruction of the calcified structures of the teeth by Streptococcus species and other bacteria, continue to be extremely prevalent in the United States. Although less than 15% of US adults are free of caries, the absolute number of caries per individual during the past 50 years has declined. This is due in part to preventive measures such as water fluoridation and the use of toothpaste, supplements, and mouth rinses that contain fluoride.

Caries may occur on smooth tooth surfaces, chewing surfaces, and most commonly in pits and fissures (Fig 2). To prevent caries in the pits and grooves of occlusal surfaces of posterior teeth, dental sealants have been developed. These materials modify the resistance of teeth to caries by coating the occlusal grooves with an adherent material such as a plastic resin. Dental sealants are currently indicated for newly erupted teeth with significant pits and fissures or for patients with significant previous occlusal caries. Once dental caries occur, they are treated by removal of the affected tissue and replacement with a restorative material such as silver amalgam, gold, or composite. The primary goal, however, is prevention of caries through dietary modification, limitation of sucrose-containing food, use of fluoride supplements, and antibacterial measures such as daily personal oral hygiene and regular professional cleanings.

Fig 2. Pit and Fissure

taken from : http://www.medscape.com/viewarticle/410839