Treatment Planning for Class II/2 Anomalies
Many of the matters discussed earlier with reference to Class I anomalies and abnormalities of teeth are also involved in Class II/2 anomalies; they usually make the situation more complicated.
The correspondence between Class II/2 and Class II/1 anomalies is limited to the disto-occlusion in the posterior segments and the deep overbite. So many of the points discussed in the previous chapters also apply to Class II/2 and are not repeated here.
Individuals with a Class II/2 anomaly exhibit normal lip closure and can have a harmonious profile and a good external facial form. In a number of cases a large nose, a shallow lower facial third and a “dished-in” profile betray a Class II/2 anomaly, but it can also be impossible to detect the existence of a Class II/2 from the external appearance. In speaking and laughing, the teeth are relatively inconspicuous.
The three distinguished types of Class II/2 anomalies (2.4.5, Fig. 2-10) differ markedly from an esthetic point of view. When all four maxillary incisors are retroclined and the canines are not prominent (Type A), the anomaly does not have to be objectionable This is not the case when one or two lateral incisors are severely tipped labially (Type B) and is often also not so when the maxillary canines are prominent and positioned labially to the dental arch (Type C).
Class II/2 anomalies are difficult to correct; the treatment lasts a long time and often fixed appliances are required. When treatment results of a Class II/2 case are not optimal the anomaly has, more than in any other anomaly, a great tendency to return.
If a Class II/2 anomaly is not esthetically objectionable, or gives the patient no trouble and involves no extreme situations the incisor regions that provide a risk of periodontal degeneration, it is advisable not to indulge in treatment.
Many points that come up here also apply to Class I anomalies with symptoms of Class II/2, so mention will not be made every time.
Class II/2 anomalies are not manifested exclusively in association with a particular skeletal pattern.74 350 Certainly, the lower face height is often on the shallow side, the inferior border of the mandible runs more horizontally, and there is a more pronounced chin than in Class I and Class II/1 situations; but a Class II/2 anomaly can also—as an exception—occur with a higher lower facial height.
If the lower lip excessively covers the maxillary incisors, then there will usually be a Class II/2 anomaly, or a Class I anomaly with symptoms of Class II/2. These anomalies do not appear without the excessive covering of the maxillary incisors by the lower lip as this is a specific characteristic.
As indicated earlier, the variety of dispositions of the maxillary front teeth (Types A, B and C) is chiefly dictated by the circumstances regarding space in the maxillary arch and the relationship of the lip line to the maxillary lateral incisors. The extent to which the mandibular incisors are tipped lingually due to the retroclination of the maxillary incisors with which they make contact, and the extent to which more secondary crowding develops, are related to the sagittal occlusion in the posterior segments (see Figs. 2-9 and 2-12).
The size of the jaws, and also that of the original conditions regarding space in the dental arches, can vary greatly in Class II/2 anomalies. When the retroclination takes place, any possible excess of space disappears and spaces in the posterior segments close. In the second transitional period mandibular premolars can become crowded. Often there is insufficient room for third molars. In cases in which the dental arch is relatively far dorsally placed, the posterior section of the apical area in the mandible can be so small that even the second permanent molar cannot emerge properly. Crowding in the posterior section of the apical area in the mandible occurs sooner in cases with a small gonial angle than in those where the angle is greater. Where the inferior border of the mandible runs more steeply, a greater increase in the tooth-bearing part of the mandible occurs than when this is inclined more horizontally, something which is related to the rotation of the mandible during growth.36
In assessing the alveolar process in the maxilla, the impression is readily obtained of an anterior section of the apical area that is positioned far ventrally, though often this is only an illusion. In tipping lingually, the maxillary incisors move their apices ventrally. The labial aspect of the roots is consequently often outside the true region of the apical area; they can be clearly palpated in this condition. In extreme cases they can lose their labial covering of alveolar bone.
The nose and chin point increase in their domination of the face according to the degree to which the maxillary incisors are tipped lingually. This picture is emphasized more by the anterior growth of the nose and chin, something that is a normal developmental phenomenon following puberty, and which is more active in boys than in girls. Altogether, it is seen that Class II/2 anomalies are frequently associated with a mouth that has fallen-in, a “dished-in” profile.
Class II/2 anomalies are not only often associated with a short upper lip, a shallow lower face height, a pronounced bony chin and a certain excess of soft tissue (Fig. 2-11), but they also usually exhibit a large freeway space and a more or less horizontal occlusal plane. Further, the mandible in closing moves cranially and dorsally, whereas normally the movement would be cranially and ventrally.74
Probably the development of the mandible ventrally is inhibited by the so-called “lid effect” of the cover bite, which is the overlapping of the mandibular teeth by the overerupted maxillary incisors (and posterior teeth as sometimes occurs). The mandibular incisors are imprisoned, as it were, by the retroclined maxillary incisors and the deep overbite. The slightly more dorsal than normal position of the mandible in Class II/2 anomalies90 can be explained by the “lid-effect”, as can the more dorsally directed path of closure.
A Class II/2 cannot be prevented. Interceptive measures have little to offer. Only occasionally is it possible, by particular interventions, to guide the unfavorable development and reduce the seriousness of the abnormality.
An apparently normal situation that later develops into a Class II/2 anomaly can usually be recognized early by watching the relation between stomion and the maxillary incisors. The lip line can already be too high in the deciduous dentition. If there are other features present that predispose to the development of a Class II/2 anomaly (see Fig. 2-11) then particular attention should be given to the development of the dentition and the growth of the face.
Premature loss of deciduous teeth due to early resorption cannot be avoided, but loss due to caries certainly can and must be prevented. A reduction in tooth material, especially in the mandible, leads to an exaggeration of the inversion of the incisors in both jaws. Extraction of deciduous teeth in the mandible has serious drawbacks in that respect. The prevention of, and prompt restoration of cavities in, deciduous molars is therefore most important.
It also must be seen that emerging mandibular premolars do not end up in endo-occlusion. This would lead to increase in crowding and further collapse of the mandibular arch.
The development of the maxillary arch also needs to be followed closely. The retroclination is more severe if the situation in the dental arch, as it affects space, will permit it. This can happen for example after premature loss of lateral deciduous incisors or deciduous canines.