Lip-to-incisor relationship and postorthodontic long-term stability of cover-bite treatment.
OBJECTIVE
To investigate the impact of a persisting high lip line and other potential relapse-inducing factors on long-term stability of orthodontic correction of retroinclined maxillary central incisors.


METHODS
Thirty-one cover-bite ("Deckbiss") patients with retroinclined maxillary central incisors and a deep frontal overbite were evaluated. The maxillary central incisor inclination was determined odontometrically with study models made pretreatment, posttreatment, and at a follow-up examination (mean posttherapeutic interval: 9.0 years). The lip-to-incisor relationship, the interincisal angle, and the anteroposterior maxillary central incisor position were measured on lateral cephalograms taken after active treatment.


RESULTS
The relapse tendency of the orthodontic correction of the retroinclined maxillary central incisors displayed great interindividual variability with a range of posttherapeutic inclination change of -6.75 degrees to +8.00 degrees. Multiple regression analysis revealed an increased tendency for relapse in patients with (1) a high posttherapeutic (dorsal) lip line level combined with the maxillary central incisor and lower lip contact only in the incisal crown area (P < .01) and (2) a marked therapeutically induced inclination change of the maxillary central incisors (P < .05). Interrelations between the relapse of the corrected maxillary central incisors and other evaluated parameters were not statistically significant.


CONCLUSIONS
For maximum treatment stability, the elimination of an excessive overlap of the upper incisors by the lower lip should be regarded as one of the most important therapeutic objectives when treating this malocclusion.
Lapatki
Bernd G
BG
Department of Orthodontics, School of Dental Medicine, University of Freiburg, Freiburg i Br., Germany. bernd.lapatki@uniklinik-freiburg.de
Baustert
Dirk
D
Schulte-Mönting
Jürgen
J
Frucht
Sibylle
S
Jonas
Irmtrud E
IE
D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D002648:Child; D005260:Female; D006801:Humans; D007180:Incisor / Q000503:physiopathology*; D008046:Lip / Q000033:anatomy & histology*; D008297:Male; D008312:Malocclusion, Angle Class II / Q000473:pathology / Q000628:therapy*; D009811:Odontometry; D012008:Recurrence; D012044:Regression Analysis; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric