Skeletal factors in anterior open-bite and deep overbite

Abstract

I t is not surprising that most orthodontists are mainly interest,ed in anteroposterior malrelationships of the teeth, since Edward Angle,l in his traditional classification, laid great emphasis on these common and esthetically displeasing abnormalities. By comparison, little work has been done on the less disfiguring vertical aspects of malocclusion. Sir Norman Bennett’s” classification, t,hough tleficient in other respects, drew attention to the vertical dimension, and clinicians have come to realize that vertical malrelationships may impose limitations on the treatment of antcropostcrior irregularities. In general, the vertical malocclusions are more difficult to correct than the anteroposterior ones. In anterior open-bite, the prognosis is either very good 01 very poor. Those eases seen at an early age tend to improve with growth and ccbssation of a habit; those seen later carry a poor prognosis if the condition is associated with a grossly abnormal facial shape or a persistent abnormality of tongue behavior in swallowing and speech. Mechanical treatment of open-bites is frequently related more to correction of a habit or tongue-thrust than to rearrangement of the teeth themselves. Attempts to elongate the incisors or depress the posterior teeth face the ever-present difficulties of pulp damage and instability after treatment. At the opposite extreme, deep overbites tend to improve with the passing 01 time,7j I3 but. most orthodontists make a more positive attempt at treat.ment oT deep overbite than of open-bite. In Britain, the conventional form of mechanotherapy is an anterior bite plane, usually of the Sved type, which brings about overbite reduction by permitting overeruption of posterior teeth or additional development of alveolar bone in this region. Unfortunately, the results tend to bc unstable in about one third of the cases.“’ With fixed appliances, the prospects of stable overbite reduction seem to be improved+ Q, l5 but ultimate stability in overbite reduction with any appliance seems to depend upon a good anteroposterior incisor relationship at the end of treatment. In reviewing the literature I? noted that both dental and skelet,al factors