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Acute pericoronitis is a painful, debilitating infection that is most commonly found among young adults with erupting mandibular third molars. Prophylactic removal of third molars to prevent this disease has been advocated, but this procedure requires an accurate description of the third molar at highest risk for this infection. Clinical and radiographic measurements were compared in 25 diseased subjects and 109 normal subjects. Of 10 variables significantly related to the presence of acute pericoronitis, stepwise discriminant analysis selected 4 variables that produced a canonical correlation coefficient of 0.71. In clinical terms, these variables described the tooth at highest risk for acute pericoronitis as a fully erupted, vertical mandibular third molar that is in contact with the adjacent second molar, at or above the occlusal plane, and partially encapsulated by soft or hard tissues. Prophylactic treatment of these third molars is highly recommended.

Thirty-one healthy patients whose third molars needed to be removed were randomly placed into two groups. Before sedation the control group (n = 16) received normal saline solution and the experimental group (n = 15) received 125 mg of methylprednisolone intravenously. Swelling was measured by photographic and face-bow techniques, trismus was determined by measuring maximal interincisal opening, and pain was evaluated by asking the patients to report the number of pain pills they used and assess th severity of their pain daily. The swelling and pain, but not the trismus, that developed after third molar removal were significantly reduced by a single dose of methylprednisolone.

The effect of age on dental tissues was studied on histologic sections of totally impacted teeth obtained from patients between 11 and 76 years of age. Impacted teeth were used in order to obviate the influence of the environmental effects prevalent in the oral cavity. The presence of concentric denticles and diffuse calcifications was determined, and the width of secondary dentin, predentin, and cementum was measured. The width of predentin and cementum increased linearly with age, whereas the aging process of secondary dentin formation and diffuse calcifications followed a different pattern. The incidence of concentric denticles was identical for all age groups.

Surgical exposure may be an integral part of orthodontic treatment of impacted teeth. In some cases the surgical procedure alone results in eruption and alignment of such teeth. The nature of the mechanism that starts concomitantly with the removal of covering tissues is not known. The aim of this investigation was to study factors associated with eruption as well as the eruption route of impacted and unerupted teeth following surgical exposure. The material consisted of 542 impacted teeth in 389 patients. The findings given strong support to the hypothesis that forces within surrounding tissues act upon the exposed crown in such a way as to direct it toward the area where the tissues were removed.