Treatment of class II division 2
Introduction :
These are relatively uncommon malocclusions (between 2 to 3% and 14% of treated malocclusions according to studies) characterized by a distally positioned mandibular arch, palatoverted maxillary incisors and excessive incisal overlap. Class II division 2 is a true clinical entity because this occlusal pattern is most often associated with mandibular hypodivergence and a slight sagittal skeletal shift in a hypertonic muscular context.
In its most common form, facial aesthetics are not disturbed but this malocclusion presents a significant periodontal risk and can be the cause of temporomandibular dysfunction.
Specificities of classes II division 2
Diagnostic and aesthetic specificities
Clinical forms:
Depending on the skeletal context and the axis of the mandibular incisor, two types of class II division 2 are distinguished.
Class II division 2 primitive
It is characterized by a slight sagittal skeletal shift, class I or slight class II, sometimes even class III in a context of mandibular hypodivergence with anterior rotation type growth. The interincisal angle is very open due to biretro-alveolia. It is often of hereditary origin. Heredity intervenes on different factors: the position of the incisal germs, muscle tone and vertical typology.
It can appear very early, even in temporary teeth.
Treatment of class II division 2
Patient presenting with a primitive class II division 2.
Exobuccal photographs showing profile harmony and signs. Profile teleradiography and analysis values: skeletal class I, mandibular hypodivergence and incisor biretro-alveolism.
Class II division 2 secondary or acquired
It is an alveolar compensation of a skeletal class II by vestibuloversion of the mandibular incisor accompanied by a palatoverted or normal maxillary incisor. The vertical skeletal context is more variable.
Treatment of class II division 2
Patient presenting with secondary class II division 2.
Exobuccal photographs showing the convexity of the prof l and the pointed symphysis . Lateral teleradiography and analysis values: skeletal class II, mandibular mesodivergence and normal inclination of the mandibular incisor.
Semiology of classes II division 2
Their clinical picture is characteristic, especially in primitive class II division 2, dominated by signs of mandibular hypodivergence.
Exoral clinical examination :
We observe:
- from the front:
– a rather square face, well developed in the transverse direction, harmonious,
– a reduction in the lower floor,
– lips together,
– a thin, short upper lip,
– a curled lower lip, slightly everted with a marked labiomental furrow,
– a high-positioned stomion,
– a smile that is often gummy due to the egression of the maxillary incisors and the shortness of the upper lip;
- in profile:
– a more or less concave subnasal profile: the nose and chin are marked. The aesthetic harmony depends on the position and shape of the symphysis, often projected in primitive class II division 2,
– a marked labiomental groove,
– a lower level diminished at the anterior level, a slightly inclined basilar edge of the mandible and a closed goniac angle.
Intraoral examination:
He reveals:
_ a deep palatine vault in its anterior part;
_ an equally deep vestibule;
_ a square, wide, rather short maxillary arch, a mandibular arch of variable shape but often in discordance with the maxillary arch, a pronounced or not Spee curve, which may be broken distal to the canine (figure 1.75);
_ class II molar relationships, more or less severe, often asymmetrical;
_ maxillary molars sometimes in mesioposition following canine dystopias;
_ a normal or reduced overjet: the palatoversion can, depending on the forms (Bassigny classification), affect two, three or four incisors or even the entire incisor-canine group
maxilla;
_ a very increased recovery in relation to:
– an incisor overbite due to the maxillary arch, the mandibular arch or most often both,
– and sometimes a molar infra-alveolus;
_ a normal transverse occlusion with linguoversion of the maxillary lateral sectors to compensate for the discordance in the shape of the arches or a vestibuloclusion of the maxillary premolars;
_ teeth that are often small, particularly the maxillary lateral incisors, and relatively frequent dental anomalies in shape and number;
_ and, often, a disharmony in the height of the gingival festoons.
Treatment of class II division 2
Class II division 2 occlusion.
A. Lateral view: Class II molar and canine, and reduction of overjet by palatoversion of the maxillary incisors.
B. Frontal view: overbite, palatoversion of the maxillary central incisors and vestibuloversion of the lateral incisors.
Treatment of class II division 2
Occlusal views of maxillary and mandibular models showing discrepancy of arch forms.
Significant curve of Spee with egression of the mandibular incisors.
Profile teleradiography and cephalometry
These additional examinations show a very variable sagittal skeletal shift depending on the clinical forms:
_ rather weak in primitive class II division 2, where we can even encounter skeletal class III;
_ more marked in secondary forms.
In the vertical dimension, Class II most often presents with mandibular hypodivergence and signs of anterior rotation.
Cephalometric analyses highlight the palatoversion of the maxillary incisor and the lingual or vestibular version of the mandibular incisor and quantify the opening of the interincisal angle.
Teleradiography allows visualization of any coronoradicular bends of the incisors.
Class II division 2 malocclusions are characterized mainly by their hypodivergent facial pattern, prominent chin, palatoversion of the maxillary incisors and increased overlap.
Dental specificities:
Class II division 2 is often accompanied by small teeth; palatoversion of the maxillary incisors would result in the primitive form of the initial position of the germ against the vestibular cortex.
This situation could contribute, during root construction, to the formation of the coronoradicular bend frequent in these cases and which participates in the anterior locking.
In addition, the cingulum of the maxillary incisors, sometimes absent or abraded, then ensures less vertical alignment of the incisors.
A significant frequency of congenital dental anomalies is observed in class II division 2 (small or agenetic maxillary lateral incisors, canine inclusions, etc.).
Evolutionary specificities of classes II division 2
Marked anterior rotation growth:
Class II division 2 presents strong condylar growth oriented upwards and forwards which is accompanied by marked anterior rotation.
In class II division 2, the locking of the mandible, imposed in particular by the hypertonic labial strap, hinders the lengthening of the mandible which tends to curl up on itself during growth.
Anterior rotation worsens the incisor overbite and reinforces the anterior blockage.
This type of growth, in the absence of therapy, worsens class II division 2.
The mandibular symphysis is projected forward, making the subnasal profile more concave and accentuating the hypodivergence. On the other hand, when the sagittal shift is significant, it tends to reduce it.
Risks associated with class II division 2
Class II division 2 is accompanied by significant periodontal, dental and joint risks related to the incisor overbite and the muscular environment.
Periodontal risks
Excess coverage sometimes results in contact between:
_ the maxillary incisors and the vestibular gingiva of the mandibular incisors;
_ the mandibular incisors and the palatine mucosa.
This contact is responsible for destruction of the periodontium in these regions.
In addition, the excessive pressure exerted by the labiomental strap contributes to weakening the periodontium of the mandibular incisor sector.
Dental risks
The high activity of the elevators and the forced contact between the maxillary and mandibular incisors promote premature wear of the palatal surfaces in the maxilla and the vestibular surfaces in the mandible.
Joint risks
The risks of ATM dysfunction are significant in class II division 2, both on the muscular and articular level.
The anterior guide causes a rapid vertical disocclusion. The functional opening angle of Slavicek (angle between the palatal surface of the maxillary incisors and the vestibular surface of the mandibular incisors) is reduced and the mandible is often in a forced retrusive position, favored by the contraction of the posterior temporal and the hyperactivity of the anterior strap.
Anterior occlusal interferences require adaptation of mandibular dynamics and cause avoidance movements that are incompatible with harmonious muscle functioning. This results in fatigue and then muscle spasms that disorganize the musculocondylodiscal system, leading to displacement or deformation of the disc.
Therapeutic approach to class II division 2
Therapeutic objectives
They arise from the previous clinical picture.
Intercept or remove the previous lock and restore the previous guide
This is the first objective of any treatment of a class II division 2. It allows:
_ an anterior repositioning of the mandible and its possible recentering;
_ a release of mandibular growth. It is obtained by reduction of the incisal overbite and by correction of the axis of the maxillary incisors.
Reduction of incisor overbite
Excessive incisal overlap may be due to:
_ an infra-alveolar molar;
_ an incisive, maxillary and/or mandibular supraalveolar;
_ a combination of both.
Molar infra-alveolism , associated with an increase in free space, can be corrected by egression of the molars either by promoting natural egression in mixed dentition, or by egressing the premolars and molars with intermaxillary traction after removing the interposition
lingual by screens. This movement causes an opening of the vertical direction, most often favorable in the case of hypodivergence, but often subject to recurrence due to the strong activity of the elevators in this type of patient.
The correction is generally more stable in mixed dentition because it accompanies alveolar growth.
Incisal supra-alveolism is due to excessive vertical development of the maxillary and/or mandibular incisive alveolar processes and excessive egression of the incisors.
The involvement of the maxillary incisors is assessed during the smile.
Indeed, excessive egression of the maxillary incisors is accompanied by exposure of the gum when smiling (gummy smile). In this case, intrusion of the maxillary incisors is recommended to reestablish harmonious lip-tooth relationships.
Most often, the intrusion of the maxillary incisors is accompanied by their vestibuloversion. However, when the initial palatoversion is very marked, the line of action of the intrusion force passes behind the center of rotation of the tooth and induces a palatoversion movement
In these cases, reduction of the palatoversion of the incisor must be carried out before the intrusion to avoid the risk of aggravating it.
Ingression of the mandibular incisors is desirable when the mandibular curve of Spee contributes to the overbite. It is accompanied, here again, most often by incisor vestibuloversion.
Correction of maxillary incisal axes
It is obtained by vestibuloversion or by applying a radiculopalatine torque on these teeth. These two actions are often associated.
Vestibuloversion of the incisors opens a functional space (OJ) between the maxillary and mandibular incisors that promotes anterior repositioning of the mandible. A closed interincisal angle and the reestablishment of normal mandibular dynamics with sufficient lateral excursions and propulsion contribute to the vertical stability of the maxillary incisor-canine group.
In class II division 2, hypercorrection of the incisal axes is the rule.
Preserving facial aesthetics
The retrusive position of the dental arches on their bony bases is often accompanied, especially in primitive class II division 2, by a retrusive bilabial profile. In addition, the concavity of the subnasal profile tends to increase regardless of the therapy performed, by growth of the nose and chin, mainly in marked anterior rotations of the mandible.
In these cases, it is therefore advisable to preserve or improve the support of the lips by the teeth. Extractions are avoided as often as possible so as not to move the mandibular incisors back or aggravate the tendency towards anterior rotation.
In cases of absolute necessity due to the size and severity of the curve of Spee, they are rather performed posterior to the mandibular arch.
In these patients, in the event of dento-dental disharmony or agenesis, the therapeutic choices will favor coronoplasties by addition or the placement of implants to increase the dental material and, consequently, the labial support.
Ensure the stability of the results obtained
The growth typology and the muscular context of this dysmorphosis are often causes of recurrence. Treatment should attempt to reduce this risk by hypercorrection of the incisal axes and improvement of the position of the stomion associated with neuromuscular rehabilitation. The latter aims in particular to strengthen the superior orbicularis and relax the inferior orbicularis.
Processing time
Treatment of class II division 2 depends on the age of the patient. Interceptive treatment can be implemented from the mixed dentition. Action on mandibular growth and attempts to open the vertical direction are particularly indicated during this period.
In addition, the preservation of spaces facilitates the treatment of moderate congestion, often avoiding subsequent extractions.
Orthodontic treatments in permanent dentition restore the anterior guide, most often by incisal intrusion, free mandibular growth and ensure meshing.
The presence of significant congestion or residual sagittal shift sometimes leads to extractions.
Finally, when the sagittal skeletal shift or vertical dysmorphosis are too severe and cause aesthetic damage, surgery may be considered at the end of growth in addition to orthodontic treatment. In adolescents, these cases are relatively rare.
Class II Division 2 Prevention
Prevention of these malocclusions is limited due to their hereditary nature and the hyperactive muscular context which is not always apparent and possible to re-educate in a young child.
It is therefore advisable to recommend orthostatic feeding which promotes mandibular propulsion and consequently the reduction of class II as well as non-mixed feeding to establish unilateral chewing alternating with large lateral movements which better control the vertical evolution of the incisors and limit the locking of the mandibular arch.
Similarly, atypical swallowing with lateral interposition of the tongue must be re-educated.
Treatment of class II division 2 in mixed dentition :
This treatment phase is most often initiated in the stable mixed dentition or at the end of the mixed dentition and is followed by a finishing phase in the permanent dentition. This early intervention helps reduce the periodontal and articular risks that accompany this malocclusion.
It allows us to best meet the previous objectives.
Lift anterior locks and intercept or correct incisor overbite
At this age, the removal of the anterior blockage is achieved by vestibuloversion of the incisors and correction of the overbite.
When the incisor overbite exists in the temporary dentition, its installation in the permanent dentition can be intercepted early, from the beginning of the evolution of the maxillary incisors. Philippe recommends the use of an interincisor palatal plate as soon as the temporary incisors fall out, which covers the eruption site of the permanent teeth, opposing the egression of the maxillary incisors.
. The plate is worn for approximately 6 months until the incisor crowns are fully exposed. The position obtained is stable if the mandibular dynamics are normal with sufficient propulsion and lateral movements.
Several devices can be used to correct incisor overbite depending on the desired objectives, ingression or stabilization of the incisors or molar egression:
- incisor intrusion arc bypass on the lateral sectors (Ricketts base arch
- high extraoral forces applied to the incisal sector, on a splint or on an arch;
- retro-incisive plan;
- palatine plate with lateral awnings;
- intrusion by mini anchor screw
Ricketts Ingression Base Arc
Extraoral force on splint
Treatment of class II division 2
Incisive ingressive mechanics under the control of a non-buried screw anchor.
Correcting skeletal class II
When occlusal blockages are released, the mandible spontaneously recenters and often repositions itself forward by correction of its forced retracted position, thereby reducing occlusal and skeletal Class II.
In addition, the released mandibular growth can then express itself and continue this correction on its own.
Thus, orthopedic therapy with a device is often not necessary, especially in primitive class II division 2 cases where the initial skeletal shift is small.
However, when the sagittal skeletal shift is more severe, mandibular retrognathia can be treated with a class II activator, preferably with a high-traction anterior extraoral force, to avoid the risk of relapse of the incisor overbite linked to the clockwise rotation of the maxilla under the effect of the activator. Molar egression can be promoted by grinding the interocclusal surfaces of the activator.
Treatment in permanent dentition
Treatment in permanent dentition respects the same objectives. At this stage, the possibility of treatment without extractions depends on:
_ the severity of the congestion and the Spee curve;
_ the concavity of the nasolabial profile;
_ the amount of occlusal Class II shift;
_ the amount and type of residual growth.
Treatment without extraction of premolars
It is recommended in primitive class II division 2 whose biretrusive labial profile, marked mandibular symphysis and strong growth potential in anterior rotation raise fears of worsening of the concavity of the profile. This therapeutic choice is indicated when:
_ the footprint is small or non-existent;
_ the initial linguoversion of the mandibular incisors allows their therapeutic vestibuloversion;
_ class II is moderate;
_ residual growth can help reduce sagittal shift.
The first phase of treatment consists, as in mixed dentition, in lifting the occlusal locks, particularly the anterior ones, by vestibuloversion and intrusion of the maxillary incisors. It allows the anterior repositioning of the mandible and the release of mandibular growth.
Depending on the severity of the occlusal and skeletal misalignment, various devices may be used:
_ class II intermaxillary tractions ,
_ of the forsus ;
_ a Herbst device .
HERBST device
FORCUS
Treatment with extraction of premolars
In some cases, the size and depth of the Spee curve may require extractions.
To preserve labial support and avoid excessive retraction of the mandibular incisors in these risk profiles, extractions most often concern the mandibular second premolars and the maxillary first premolars.
Extraction of the four second premolars may sometimes be preferred, but here again, this choice increases the difficulties of managing maxillary posterior anchorage.
The choice of extractions 14-24-35 and 45 is therefore mainly indicated in the absence of too significant a reduction in the skeletal vertical dimension compared to a complete class II.
Extraction of 14-24 allows correction of canine class II and that of 35-45 allows correction of molar class II.
Extractions are often delayed until after the anterior unlocking phase to better assess the residual Class II.
Surgical-orthodontic treatment of class II division 2
At the end of growth, when skeletal dysmorphosis is severe, the aesthetic damage may lead to the establishment of surgical-orthodontic treatment.
This is essentially the case when:
- the very marked mandibular hypodivergence induces an unsightly vertical insufficiency of the lower level;
- Skeletal class II due to mandibular retrognathism is responsible for a highly retrusive profile.
The most common surgery in class II division 2 is mandibular advancement surgery often supplemented by harmonization genioplasty.
Contention and stability
Class II division 2 is a very recurrent malocclusion due to the associated muscular context. The hyperactivity of the labial strap tends to lingualize the incisors, thus promoting the recurrence of the incisor overbite.
.
Rehabilitation must most often be associated in order to normalize functions and relax the labiomental strap.
It contributes significantly to the stability of the results.
This risk of recurrence must be anticipated during treatment by:
- overcorrection of the incisal axes and overlap, and correct positioning of the maxillary incisors in relation to the stomion;
- the restoration of normal mandibular dynamics, with sufficient excursions in propulsion and laterality, controlling the vertical position of the incisorcanine group.
The retention is most often glued to the mandibular arch in order to stabilize the position of the incisor-canine group.
In the maxillary arch, the retention of the axial and vertical correction of the incisors can be ensured by:
- a return of the palatal resin of the plate to the incisal edge;
- a very gingival position of the vestibular bar;
- composite stops at the cingulate level.
Treatment of class II division 2
Wisdom teeth can be painful if they are misplaced.
Composite fillings are aesthetic and durable.
Bleeding gums can be a sign of gingivitis.
Orthodontic treatments correct misaligned teeth.
Dental implants provide a permanent solution for missing teeth.
Scaling removes tartar and prevents gum disease.
Good dental hygiene starts with brushing twice a day.