Lec: Treatment of class II div2 malocclusion
A Class II incisor relationship is defined by the British Standards classification as being present when the lower incisor edges occlude posterior to the cingulum plateau of the upper incisors. Class II division 2 includes those malocclusions where the upper central incisors are retroclined. The overjet is usually minimal, but may be increased. The prevalence of this malocclusion in a Caucasian population is approximately 10 percent...
Etiological factors of class II div2
The majority of Class II division 2 malocclusions arise as a result of a
number of inter-related skeletal and soft tissue factors.
a. Skeletal factor. (mostly cl II)
b. Soft tissue factor. (unfavourable)
c. Dental factor.
• Class II division 2 malocclusion is commonly associated with a mClass II skeletal pattern, but may also occur in association with a Class I or even a Class III dental base relationship. The vertical dimension is also important in the aetiology of Class II division 2 malocclusions, and typically is reduced. There is a low gonial angle giving rather square facial profile due to forward rotational pattern of the mandible which will help in reducing the severity of the skeletal patterns but give a deep bite.
• The influence of the soft tissues in Class II division 2 malocclusions is usually mediated by the skeletal pattern. If the lower facial height is reduced, the lower lip line will effectively be higher relative to the crown of the upper incisors (more than the normal one-third coverage). A high lower lip line will tend to retrocline the upper incisors. There is commonly pronounced labio-mental groove beneath the lower lip.
• As with other malocclusions, crowding is commonly seen in conjunction with a Class II division 2 incisor relationship. In addition, any pre-existing crowding is exacerbated because retroclination of the upper central incisors. If there is crowding of the upper dental arch, the upper laterals or canines may be proclined in front of the lower lip function.
Lack of an effective occlusal stop to eruption of the lower incisors may result in their continued development, giving rise to an increased overbite.This may be due to a Class II skeletal pattern or retroclination of the incisors as a result of the action of the lips, leading to an increased inter-incisal angle.
The incisors position in class II div2
The retroclination of the incisors and deep incisal overbite are the main features which warrant in class II2, this will lead to:
• Trauma in both upper and lower gingiva.
• Excessive vertical development of anterior dento-alveolar segments.
• Reduced lower facial height.
Treatment objectives and limitations:
o Relief of crowding and local irregularities.
o Relief of gingival trauma and correction of incisal inclinations.
o Correction of buccal segment relation.
The relief of anterior gingival trauma necessitates movement of the incisor teeth to a position where the lower incisor edges contact the palatal surface of the upper incisor in occlusion. This can only brought about by reduction of the inter-incisal angle.
The limiting factors to this treatment are the musculature of the lower lip and the degree of class II skeletal discrepancy. If the lower lip line is high, proclination of the upper anterior segment by simple tipping movement is not possible. Furthermore, if there is a sever skeletal discrepancy then the lower incisors cannot be proclined sufficiently to meet the upper segment.
Management
Stable correction of a Class II division 2 incisor relationship is difficult as it requires not only reduction of the increased overbite, but also reduction of the inter-incisal angle which classically is increased. If re-eruption of the incisors and therefore an increase in overbite is to be resisted, the inter-incisal angle needs to be reduced, preferably close to 135°.
The inter-incisal angle in a Class II division 2 malocclusion can be
reduced in a number of ways:
• Torquing the incisor roots palatally/lingually with a fixed appliance.
• Proclination of the lower labial segment. This approach should only be employed by the experienced practitioner as, although it provides additional space for alignment of the lower incisor teeth, any excessive movement of the lower arch would increase the risk of relapse.
• Proclination of the upper labial segment followed by use of a functional appliance to reduce the resultant overjet and achieve intermaxillary correction (the patient should be .....).
We can start with upper removable appliance then followed by myofunctional or fixed appliance, this depend on the etiology of class II2 at the presence of crowding or spacing, the patients, profile and age. A sever class II skeletal discrepancy with class II2 may prevent the attainment of incisal contact and if there is gingival trauma a permanent retainer may be necessary after reduction of overbite.
Approaches to the reduction of overbite:
• Intrusion of the incisors
• Eruption of the molars
• Proclination of the lower incisors
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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