Abstract
Many clinicians hypothesize that retroclination of the maxillary central incisors in Class II, Division 2 malocclusion is caused by increased resting lip pressure against these teeth. The purpose of this study was (1) to verify this assumption by means of simultaneous lip-pressure measurements at two different levels on the maxillary central incisor crowns, and (2) to examine factors that could possibly contribute to the increased resting lip pressure. This is the first study to prove that individuals with Class II, Division 2 malocclusion (n = 21) have the upper central incisors exposed to significantly higher lip pressure than those with Class I malocclusion (n = 21). Our statistical evaluation revealed that this is primarily attributed to a high lip line and not to a hypertonic peri-oral musculature. We concluded that orthodontic treatment of Class II, Division 2 cases should include intrusion of the maxillary incisors, to eliminate the non-physiologically high pressure exerted by the lower lip on these teeth and, consequently, to reduce the high risk of a post-orthodontic relapse.
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
