Class II Division 2
1. Introduction
Class II division 2 is certainly not the most frequent or most described anomaly but it is the most resounding anomaly.
The statement of a class II division 2 constitutes a diagnosis in itself. It is a real clinical entity although not stereotypical.
Most authors agree on the definition of the occlusal point of view but diverge on the typological characteristics.
2. Definitions
2.1. Definition of skeletal class II division 2
Class II division 2 is a dento-skeletal anomaly characterized by:
A basic shift between the upper and lower jaw in the sagittal direction with the maxilla advanced relative to the mandible.
Distal occlusion of the two lateral sectors of the lower arch evidenced by the mesio-distal relationship of the first molars and the permanent canines as well as by a lingual version of the upper incisors (two, three or four) with or without overbite.
DARQUE distinguishes two types of class II division 2:
Class II 2 primary: called hereditary
Class II 2 secondary: called functional or acquired.
2.2. Definition of Class II Division 2 malocclusion
It is a malocclusion of the ANGLE classification, characterized by lingoversion of the two upper central incisors or all three incisors or all four upper incisors with a decreased overjet and Class II molar and canine relationships.
5- Etiopathogenic diagnosis
5.1 . Role of heredity
The role of heredity in primary Class II division 2 malocclusion is essential because it occurs at three levels:
- On the skeletal diagram
- On the muscular system
- On the dental system
- On the skeletal diagram
According to SCHWARTZ, the study of the relationships of the arches in the newborn specifies that from birth, the shift of the upper and lower bony bases and the anterior relationships of the alveolar ridges “like a box lid” are established.
- On the muscular system
The study of genetics determines the characteristics of muscle tone specific to each individual, it seems that in addition to muscle tone, heredity determines to a certain extent the characteristics of muscle insertions at the skeletal level.
- On the dental system
More than in muscular behavior, it appears that “the hereditary factor” determines:
- The mesial position of the upper canine germ
- The vertical position of the axes of the upper central incisors.
In fact, the examination of the oral cavity of a child with temporary teeth already presents the morphological characteristics of class II division 2.
5.2 . The role of acquired factors
5.2.1. Muscle imbalance and functional disorders
Muscular imbalance and functional disorders are often called upon to explain the pathogenesis of these malocclusions. However, it is very difficult in a muscular disorder to distinguish what is determined by heredity from what is due to dysfunction.
This imbalance in class II division 2 can be described as “concentric” if we refer to the neuromuscular classification of (Ms. MULLER), that is to say an imbalance of the neuromuscular behavior between the facial muscles and the tongue in favor of the facial muscles.
5.2.2. Skeletal Base Shift
The development of the mandible is held back because of incisor occlusal interferences which maintain the growth delay of the latter, but the current trend is more in favor of a hereditary morphological data than of an acquired skeletal dysmorphosis.
5.2.3. Mesialization of the upper lateral sectors.
This mesialization is due to the more anterior position of the pterygomaxillary ligament, the tone of this ligament is associated with labial tone and thereby causes anteroposterior compression of the upper arch with anterior dental crowding.
For others, it is a time lag between the anteroposterior growth at the level of the tuberosity and the development of the germs of the 2nd and 3rd molars. This development being earlier, the evolution of the 2nd and 3rd molars causes the mesialization of the 1st molar and of all the lateral sectors.
This mesialization will cause that of the canine, hence anterior crowding with dystopia: vestibuloposition of the canine with lingual version of the crown at the incisal level without there being lingual pressure.
5.2.4. In the pathogenesis of overbite
Overbite is caused by the disruption of the vertical occlusal balance due to the increase in the inter-incisal angle because the incisors do not find antagonists and therefore lengthen until contact with the opposite jaw. Add to this the lower lip which does not oppose incisal egression in the case where the stomion is too high.
5.2.5. In the pathogenesis of palatoversion of the upper incisors.
The palatoversion of the upper central incisors is explained by the low position of its free edge supported by the lower lip while the lateral incisors escape this control and are most often in normal or vestibuloposition.
Class II division 2 Class II division 2
6- Clinical forms:
Form 1: Deck Bis
This is the most common form. It is characterized by a lingual version of the upper central incisors and apparent vestibuloversion of the upper lateral incisors associated with an overbite.
Form 2: It is characterized by lingoversion of the 3 or 4 upper incisors, ectopic canines in the vestibular position, or palatal inclusions, associated with an overbite.
Form 3: This is the most severe case, characterized by a box-lid occlusion: a lingoversion of the incisor-canine group and supra position of the canines. The maxillary SPEE curve is inverted. An exaggerated vestibuloclusion or vestibular inocclusion of the premolars is observed.
The bimaxillary overbite is very pronounced. It is not uncommon to observe, in this form, lesions of the retrocingulate palatine mucosa and recessions at the level of the vestibular gingiva of the lower incisors.
The vertical dimension is very significantly reduced. This particularly pathogenic occlusion can be aggravated by a disharmony of arch shape between the maxillae (U-shaped in the maxilla, V-shaped in the mandible), by microdontia localized to the premolars (Dental Disharmony between anterior and lateral sectors) by a linguoversion of the lower premolars and an exaggerated vestibuloversion of the upper premolars.
Location of the Supraclusion:
- Upper central incisors only
- In the upper and lower incisors. The SPEE curve is subnormal.
- In the upper and lower incisors with accentuation of the mandibular SPEE curve
Under these conditions, the incisal coverage is greatly increased.
Associated lower incisor crowding
- No incisal crowding most often
- More or less marked incisal crowding giving the appearance of Dento-Maxillary Disharmony and related to lingoversion of the lower incisors (bi retroalveolism)
- DDM associated with class II division 2 which poses particular treatment difficulties.
7- Positive diagnosis:
7.1. Facial signs:
No facial aesthetic impact in general, except in certain severe cases which present a significant reduction in the lower part of the face and an accentuated concavity of the profile.
a/ facial examination: the face is usually of the “short face” type. The face is sometimes square with pronounced features (nose and chin)
b/ profile examination: the profile is frequently concave, depending on a mental symphysis and a nose of larger than average dimensions:
The goniac angle appears closed
The lips have on average a reduced thickness. In marked cases, there is a relative procheilia of the upper lip in relation to the lower lip due to retromandibulia.
Eversion of the lower lip with a marked labiomental groove.
Class II Division 2
7.2. The muscular environment
- Tongue: normal size; high and posterior posture; sometimes lateral spread on the grinding surfaces: no dental support
- Lips : significant labial tone, sometimes a strap effect on the lower lip causing lingoversion of the upper incisors, the orbicularis oris is very toned and also the mentalis muscle in severe cases, constant labial occlusion, at rest a rather unsightly gummy smile if the upper lip is short.
- Masticatory muscles : predominance of posterior fibers of the temporal and masseter muscles
7.3. Occlusal signs:
The most common clinical form is lingoversion of the two central incisors. Its intra-oral aesthetic impact leads to consultation:
7.2.1. Intra-arcade layout:
a/ maxilla :
Deep palatine vault at the anterior level.
Linguoversion of the two central incisors and apparent vestibuloversion of the lateral incisors.
The free edge of the upper central incisors is located lower than the occlusal plane.
B/mandible
Little or no incisal crowding.
Incisor supraclusion associated or not with an accentuated SPEE curve.
Abrasion facet sometimes visible at the free edges of the incisors.
7.2.2. Inter-arch relationships
static
- anteroposterior sense molar class II ratio, canine class II ratio, reduced incisal overjet
- vertical direction; excessive incisal overlap depending on the overbite located in the upper central incisors or the overbite in the lower incisors
- transverse direction; normoclusion from the canines or exaggerated vestibuloclusion of the upper premolars.
7.4. Functional examination:
- Swallowing:
When a swallowing disorder exists, it manifests itself by atypical swallowing with:
- Lateral lingual interposition
- Untimely contraction of the lower lip, the square and the tuft of the chin.
But generally, in class II division 2 swallowing is normal and with constant lip contraction.
- Breathing : normal
- Chewing
The masticatory effort and occlusal forces are very important in these subjects, this anomaly of mastication encountered in cases of primary Class II division 2 gives the impression that these patients chew with the orbicularis.
7.5. Teleradiographic signs
- Increased ANB (> 2.5° +/- 2°).
- The height of the lower floor is reduced:
- according to W .W ENA-ME<55%.
- According to Ricketts ht of the lower floor ENA-XI-PM < 47° +/- 4°.
- The height of the Ramus according to Château is increased:
CO-GO > 47%+/-3%.
- Reduced tweed FMA (< 22°+/- 6°)
- Parallelism of horizontal planes: Frankfurt plane // bispinal plane // Occlusal plane // mandibular plane.
- Quite marked mental symphysis
- The glenoid cavity is deep in relation to the overbite (incisal slope) and the condylar slope.
- Lingoversion of the upper central incisors and overbite:
- I/F decreased (< 107° +/- 2°).
- I to Na linear and angular decreased
I to Na < 22°
I to Na < 4 mm.
- i/m normal or decreased (90° +/- 3°)
- Increased angle of attack I / i > 125° +/- 6°.
- The apices of the upper central incisors are located very close to the external alveolar cortex.
- Concave skin profile according to Ricketts.
8- Differential diagnosis:
Superior retroalveolus.
8- Long term consequences:
- First possibility : no particular consequences: the periodontium of these patients is usually very resistant to aggression. Therefore, the long-term consequences of a class II division 2 will be zero if there are stable incisal contacts and if hygiene is correct.
- Second possibility
- Progressive abrasion of the lower incisors in the case of advanced and non-centered position of the condyles at rest
- In some severe cases, overbite causes retro-incisor palatal lesions and vestibular denudation at the level of the incisors, jeopardizing the future of these teeth in the more or less long term.
- DAM in predisposed subjects.
9- Conclusion
It is clear that class II division 2 is “typical” but that its treatment will not be considered in the same way for different forms, typologies.
Before starting any therapeutic approach and developing a treatment plan, it is necessary to ensure the advanced diagnosis. This is why here again we will insist on the gathering of clinical and radiographic signs that support a positive diagnosis supported by its etiology.
Class II Division 2
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Preventative dental care avoids costly treatments.
Baby teeth serve as a guide for permanent teeth.
Fluoride mouthwash strengthens tooth enamel.
An annual checkup helps monitor oral health.