As primary care physicians and consultants, internists are often asked to evaluate patients with disease of the oral soft tissues, teeth, and pharynx. Knowledge of the oral milieu and its unique structures is necessary to guide preventive services and recognize oral manifestations of local or systemic disease (Chap. e12). Furthermore, internists frequently collaborate with dentists in the care of patients who have a variety of medical conditions that affect oral health or who undergo dental procedures that increase their risk of medical complications.
Tooth and Periodontal Structure
Tooth formation begins during the sixth week of embryonic life and continues through the first 17 years of age. Tooth development begins in utero and continues until after the tooth erupts. Normally, all 20 deciduous teeth have erupted by age 3 and have been shed by age 13. Permanent teeth, eventually totaling 32, begin to erupt by age 6 and have completely erupted by age 14, though third molars (wisdom teeth) may erupt later.
The erupted tooth consists of the visible crown covered with enamel and the root submerged below the gum line and covered with bonelike cementum. Dentin, a material that is denser than bone and exquisitely sensitive to pain, forms the majority of the tooth substance. Dentin surrounds a core of myxomatous pulp containing the vascular and nerve supply. The tooth is held firmly in the alveolar socket by the periodontium, supporting structures that consist of the gingivae, alveolar bone, cementum, and periodontal ligament. The periodontal ligament tenaciously binds the tooth's cementum to the alveolar bone. Above this ligament is a collar of attached gingiva just below the crown. A few millimeters of unattached or free gingiva (1–3 mm) overlap the base of the crown, forming a shallow sulcus along the gum-tooth margin.
Dental Caries, Pulpal and Periapical Disease, and Complications
Dental caries begin asymptomatically as a destructive process of the hard surface of the tooth. Streptococcus mutans, principally, along with other bacteria colonize the organic buffering film on the tooth surface to produce plaque. If not removed by brushing or the natural cleaning action of saliva and oral soft tissues, bacterial acids demineralize the enamel. Fissures and pits on the occlusion surfaces are the most frequent sites of decay. Surfaces adjacent to tooth restorations and exposed roots are also vulnerable, particularly as teeth are retained in an aging population. Over time, dental caries extend to the underlying dentin, leading to cavitation of the enamel and, ultimately, penetration to the tooth pulp, producing acute pulpitis. At this early stage, when the pulp infection is limited, the tooth becomes sensitive to percussion and hot or cold, and pain resolves immediately when the irritating stimulus is removed. Should the infection spread throughout the pulp, irreversible pulpitis occurs, leading to pulp necrosis. At this late stage, pain is severe and has a sharp or throbbing visceral quality that may be worse when the patient lies down. Once pulp necrosis is complete, pain may be constant or intermittent, but cold sensitivity is lost.
Treatment of caries involves removal of the softened and infected hard tissue; sealing the exposed dentin; and restoration of the tooth structure with silver amalgam, composite resin, gold, or porcelain. Once irreversible pulpitis occurs, root canal therapy is necessary, and the contents of the pulp chamber and root canals are removed, followed by thorough cleaning, antisepsis, and filling with an inert material. Alternatively, the tooth may be extracted.
Pulpal infection, if it does not egress through the decayed enamel, leads to periapical abscess formation, which produces pain on chewing. If the infection is mild and chronic, a periapical granuloma or eventually a periapical cyst forms, either of which produces radiolucency at the root apex. When unchecked, a periapical abscess can erode into the alveolar bone producing osteomyelitis, penetrate and drain through the gingivae (parulis or gumboil), or track along deep fascial planes, producing a virulent cellulitis (Ludwig's angina) involving the submandibular space and floor of the mouth (Chap. 164). Elderly patients, those with diabetes mellitus, and patients taking glucocorticoids may experience little or no pain and fever as these complications develop.
Periodontal disease accounts for more tooth loss than caries, particularly in the elderly. Like dental caries, chronic infection of the gingiva and anchoring structures of the tooth begins with formation of bacterial plaque. The process begins invisibly above the gum line and in the gingival sulcus. Plaque, including mineralized plaque (calculus), is preventable by appropriate dental hygiene, including periodic professional cleaning. Left undisturbed, chronic inflammation ensues and produces a painless hyperemia of the free and attached gingivae (gingivitis) that typically bleeds with brushing. If ignored, severe periodontitis occurs, leading to deepening of the physiologic sulcus and destruction of the periodontal ligament. Pockets develop around the teeth and become filled with pus and debris. As the periodontium is destroyed, teeth loosen and exfoliate. Eventually, there is resorption of the alveolar bone. A role for the chronic inflammation resulting from chronic periodontal disease in promoting coronary heart disease and stroke has been proposed. Epidemiologic studies demonstrate a moderate but significant association between chronic periodontal inflammation and atherogenesis, though a causal role remains unproven.
Acute and aggressive forms of periodontal disease are less common than the chronic forms described above. However, if the host is stressed or exposed to a new pathogen, rapidly progressive and destructive disease of the periodontal tissue can occur. A virulent example is acute necrotizing ulcerative gingivitis (ANUG) or Vincent's infection. Stress, poor oral hygiene, and tobacco and alcohol use are risk factors. The presentation includes sudden gingival inflammation, ulceration, bleeding, interdental gingival necrosis, and fetid halitosis. Localized juvenile periodontitis, seen in adolescents, is particularly destructive and appears to be associated with impaired neutrophil chemotaxis. AIDS-related periodontitis resembles ANUG ...