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Periodontal Diseases

The periodontium includes the gingiva, alveolar bone, cementum, and periodontal ligament (see Fig. 338.5 ). Gingivitis Poor oral hygiene results in the accumulation of dental plaque at the tooth-gingival interface that activates an inflammatory response, expressed as localized or generalized reddening and swelling of the gingiva. More than half of American school children experience gingivitis. In severe cases, the gingiva spontaneously bleeds and there is oral…

Dental Caries

Etiology The development of dental caries depends on interrelationships among the tooth surface, dietary carbohydrates, and specific oral bacteria. Organic acids produced by bacterial fermentation of dietary carbohydrates reduce the pH of dental plaque adjacent to the tooth to a point where demineralization occurs. The initial demineralization appears as an opaque white spot lesion on the enamel, and with progressive loss of tooth mineral, cavitation of…

Cleft Lip and Palate

Clefts of the lip and palate are distinct entities which are closely related embryologically, functionally, and genetically. It is thought that cleft of the lip appears because of hypoplasia of the mesenchymal layer, resulting in a failure of the medial nasal and maxillary processes to join. Cleft of the palate results from failure of palatal shelves to approximate or fuse. Incidence and Epidemiology The incidence of…

Malocclusion

The oral cavity is essentially a masticatory instrument. The purpose of the anterior teeth is to bite off large portions of food. The posterior teeth reduce foodstuff to a soft, moist bolus. The cheeks and tongue force the food onto the areas of tooth contact. Establishing a proper relationship between the mandibular and maxillary teeth is important for both physiologic and cosmetic reasons. Variations in Growth…

Development and Developmental Anomalies of the Teeth

Newborn infants do not have teeth for about first 6 mo after birth (predentate period). At this stage, the upper and lower alveolar ridges in the mouth, also known as gum pads, house the primary (deciduous) and some permanent tooth buds. The primary dentition period starts with eruption of the first primary tooth; all 20 primary teeth erupt by 3 yr of age. The permanent teeth start erupting…

Major Symptoms and Signs of Digestive Tract Disorders

Disorders of organs outside the gastrointestinal (GI) tract can produce symptoms and signs that mimic digestive tract disorders and should be considered in the differential diagnosis ( Table 332.1 ). In children with normal growth and development, treatment may be initiated without a formal evaluation based on a presumptive diagnosis after taking a history and performing a physical examination. Poor weight gain or weight loss is…

Echinococcosis ( Echinococcus granulosus and Echinococcus multilocularis )

Etiology Echinococcosis ( hydatid disease or hydatidosis ) is a widespread, serious human cestode infection ( Fig. 330.1 ). Two major Echinococcus groups of species are responsible for distinct clinical presentations. Echinococcus granulosus and related species cause cystic hydatid disease, and Echinococcus multilocularis causes alveolar hydatid disease . The adult parasites are small (2-7 mm) tapeworms with only 2-6 segments that inhabit the intestines of canines such…

Cysticercosis

Etiology Taenia solium, also known as the pork tapeworm , causes 2 different infections in children. In its normal life cycle, children can acquire the tapeworm form by ingestion of undercooked pork containing the larval cysts (see Chapter 328 ). In the intestines, the cyst converts into the tapeworm form. Children are also susceptible to infection by the eggs shed by tapeworm carriers. After the eggs…

Adult Tapeworm Infections

Tapeworms are adult forms of cestodes , multicellular helminth parasites, that live in human intestines and cause non–life-threatening illness. Invasive larval forms of cestodes are associated with cysts that lead to severe human disease such as neurocysticercosis ( Taenia solium ; see Chapter 329 ) and echinococcosis (mostly Echinococcus granulosa and E. multilocularis ; Chapter 330 ). The adult worms themselves are flat and multisegmented, varying…

Flukes (Liver, Lung, and Intestinal)

Several different trematodes , or flukes, can parasitize humans and cause disease. Flukes are endemic worldwide but are more prevalent in the less developed parts of the world. They include Schistosoma, or the blood flukes (see Chapter 326 ), as well as fluke species that cause infection in the human biliary tree, lung tissue, and intestinal tract. These latter trematodes are characterized by complex life cycles…

Schistosomiasis (Schistosoma)

The term schistosomiasis (bilharzia) encompasses the acute and chronic inflammatory disorders caused by human infection with Schistosoma spp. parasites. Disease is related to both the systemic and the focal effects of schistosome infection and its consequent host immune responses triggered by parasite eggs deposited in the tissues. For the affected individuals, this frequently manifests as disabling chronic morbidity. Etiology Schistosoma organisms are the trematodes, or flukes…

Trichinellosis (Trichinella spiralis)

Etiology Human trichinellosis (also called trichinosis ) is caused by consumption of meat containing encysted larvae of Trichinella spiralis, a tissue-dwelling nematode with a worldwide distribution. After ingestion of raw or inadequately cooked meat from pigs (or other commercial meat sources such as horses) containing viable Trichinella larvae, the organisms are released from the cyst by acid-pepsin digestion of the cyst walls in the stomach and…

Toxocariasis (Visceral and Ocular Larva Migrans)

Etiology Most cases of human toxocariasis are caused by the dog roundworm , Toxocara canis. Adult female T. canis worms live in the intestinal tracts of young puppies and their lactating mothers. Large numbers of eggs are passed in the feces of dogs and embryonate under optimal soil conditions. Toxocara eggs can survive relatively harsh environmental conditions and are resistant to freezing and extremes of moisture…

Other Tissue Nematodes

Onchocerciasis (Onchocerca Volvulus) Infection with Onchocerca volvulus leads to onchocerciasis or river blindness . Onchocerciasis occurs primarily in West Africa but also in Central and East Africa and is the world's 2nd leading infectious cause of blindness. There have been scattered foci in Central and South America, but the infection is now thought to be eliminated in the Americas. O. volvulus larvae are transmitted to humans…

Lymphatic Filariasis ( Brugia malayi, Brugia timori, and Wuchereria bancrofti )

Etiology The filarial worms Brugia malayi ( Malayan filariasis ), Brugia timori, and Wuchereria bancrofti ( bancroftian filariasis ) are threadlike nematodes that cause similar infections. Infective larvae are introduced into humans during blood feeding by the mosquito vector. Over 4-6 mo, the larval forms develop into sexually mature adult worms. Once an adequate number of male and female worms accumulate in the afferent lymphatic vessels, adult…

Strongyloidiasis (Strongyloides stercoralis)

Etiology Strongyloidiasis is caused by the nematode, or roundworm, Strongyloides stercoralis. Only adult female worms inhabit the small intestine. The nematode reproduces in the human host by parthenogenesis and releases eggs containing mature larvae into the intestinal lumen. Rhabditiform larvae immediately emerge from the ova and are passed in feces, where they can be visualized by stool examination. Rhabditiform larvae either differentiate into free-living adult male…

Enterobiasis (Enterobius vermicularis)

Etiology The cause of enterobiasis, or pinworm infection, is Enterobius vermicularis, which is a small (1 cm in length), white, threadlike nematode, or roundworm, that typically inhabits the cecum, appendix, and adjacent areas of the ileum and ascending colon. Gravid females migrate at night to the perianal and perineal regions, where they deposit up to 15,000 eggs. Ova are convex on one side and flattened on the…