Dental development and the pharyngeal lymphoid tissue.

Because the teeth are housed and develop within the jaws, skeletal development of the maxilla and mandible is a primary factor in the consideration of any problems pertaining to the developing dentition. Growth of the posterior nasal choanae, the maxilla, and the nasopharynx should be evaluated as a unit in assessing the favorable or unfavorable character of the nasopharyngeal region. Both large and small adenoidal tissues should be examined in light of the morphologic character of the nasopharynx (be it small, large, narrow, or wide) and related to the developing maxilla. Variables in size and location of the maxilla and the pharynx will play an important role in the impact that lymphoid tissue will have on the patency of the nasopharyngeal isthmus. Synchronized growth between the normally developing adenoids and the migration of the maxilla away from the cranial base will produce a balanced environment that precludes nasal obstruction by the presence of adenoids. With time, the changes in spatial relationships between the posterior border of the maxilla and the posterior pharyngeal wall plus atrophy of the adenoidal tissue will generally minimize or eliminate the problems of nasal obstruction and mouth breathing. Growth data may be used to evaluate the status, assess progress, measure comparability, determine inheritance patterns, and confer individuality. Unit-trait inheritance of the teeth, alveolar processes, maxilla, mandible, soft-tissue profile, tongue, pharynx, and lymphoid tissues may well produce more definitive answers to the question of the developing dentition and the pharyngeal lymphoid tissue. Finally, at present, no clinician can categorically state that enlarged tonsils or adenoids per se are responsible for abnormal dentition in the absence of other factors.