CLASS II DIVISION 2

Definition

Angle`s classification: based on molar relationship

Class II Division 2: The mesio-buccal cusp of the maxillary first molar occludes anterior to the midbuccal

groove of the mandibular first molar (ie the lower molar is retro-positioned relative to the upper). Hence

the alternative term – postnormal molar relationship with upper central incisors retroclined and the lateral

incisor proclined mesiolabially rotated and OB increased while the The overjet is usually minimal but

may be increased

BSI classification: based on A-P incisor relationship

Class II Division 2: The lower incisor edges occlude or lie posterior to the cingulum plateau of the upper

central incisors with the upper central incisors are retroclined. The overjet is usually minimal but may be

increased.

Other classification also described for epidemiological point of view including

Class II indefinite when one incisor retroclined and the other is proclined (Gravely)

Intermediate when the incisor retroclined or upright and the OJ 5-7 mm (Stephen and William,

1993).

Class II division 1 or division 2 sub-division is occur when MR is class 1 on one side and 2 on the

other side. (IOWA notation system)

Super class 2 when the MR is more than full unit.

Van der Linden classified class2 division 2 into:

Type A: all incisor retroclined

Type B: only centrals retroclined

Type C:all incisors retroclined and overlapped by canines.

Incidences

It has an incidence rate of 1.5% to 7% (Ingervall et al, 1972; Peck et al, 1998),

but has also been reported as high as 17.7% (Foster and Day, 1974).

Elevated male expression of the II/2 deep bite cases may be indicative of a sex-linked genetic

pattern of strong mandibular development. Isaacson et al. (1972).

Highly associated with impacted canine.

AetiologyMainly poly-epigenetic interaction

1. Genetic and familial high heritability of class II division 2 malocclusion, complete penetrance

being reported in familial studies of monozygotic twins (100% occurrence) and dizygotic twin

10% occurrence (Peck, 1998)

2. Environmental factors

A. Soft tissue factors

B. Dental factors

C. Skeletal factors

D. Growth factors

a) Soft tissue factors

A high lip line. Lapatki 2002

Hyperactive or hypertonic lips have been implicated in the aetiology of the class II division 2

incisor relationships (Karlsen, 1994).

Mentalis muscles, (strap-like lower lip). However Rix 1960 showed that there is no basis for this

and even the activity of the muscle are low than normal.

Increased masticatory bite forces due to dominant short acting collagen fiber type II and

hyperatrphic master muscle. this can lead to intrusion of posterior teeth and increased OB.

NB:

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, and the higher the lip line,

the more severe the upper incisor retroclination will be (Houston, 1980).

In some cases the upper lateral incisors, which have a shorter crown length, will escape

the action of the lower lip and therefore lie at an average inclination, whereas the central

incisors are retroclined.

If there is arch length discrepancy, the laterals or canine migt be proclined and rotated to

occupy less space than normal.

b) Dental factors

Upright incisor position,

Long centrals and short lateral that escape from lip effects.

Increased crown root angle of the upper incisor, (McIntyre and Millett, 2003).

Overeruption of the incisors

Thin incisors

small trabecular or cingulum,

c) Skeletal factors

Hopkins 1968 found in class II there is increase cranial base length and angle opposite to that of

class III

Pancherz 1997 conclude that class 2 division 2 has the same features of class 2 division 1 in AP

wise except that upper incisors are retroclined in the former.

Skeletal class II in 50% of cases and reduced AFH in 100%(Pancherz 1997)

d) Growth factors

Overdevelopment of upper anterior alveolar process,

Anterior rotation of the mandible.

Features1. Skeletal features

2. Soft Tissues features

3. Growth features

4. Dental features

5. Occlusal features

6. IOTN

In details:

A. Skeletal: Hopkins 1968

1. Increased anterior cranial base length and Obtuse cranial base angle, Hopkins 1968

2. Class II or class I and occasionaly Class III skeletal pattern

3. Decrease LAFH

4. Increase PFH

5. Decrease MMPA

6. Seven feature of anterior growth rotation of Bjork 1969

B. Soft Tissues

1. Brackycephalic faces in frontal view

2. Retrusive profile in case of bimaxillary retrognathisim

3. Obtuse NLA

4. Competent lips

5. High lower lip line

6. Thin upper lip

7. Accentuated lower lip curl due to their length relative to a reduced lower face height. This

with the prominence of the chin will lead to acute labiomental angle

8. Prominenat chin.

9. Hyperactive mentalis

10. Masseter muscle hyperactivity

11. High positioned tongue causing scissor bite

12. Traumatized palate or labial gingivae secondary to deep OB

C. Growth features

The presence of seven anticlockwise rotation features described by Bjork 1969 in most of the cases

1. Anterior inclination of the Condylar Head,

2. Increased curvature of the mandibular canal,

3. Thick bone and bowed shape of the lower border of the mandible, and absence of

gonial notch

4. Forward inclination of the symphysis,

5. increased interincisal angle,

6. increased interprcmolar or intermolar angles,

7. Decreased anterior lower face height.

D. Dental:

1. Broad upper arch

2. Retroclined ULS and consequently retrocline LLS particularly if the skeletal base

relationship is class I or mild skeletal class II, as the lower incisors become trapped behind

a retroclined upper labial segment (Mills, 1973). This can result in posterior positioning of

B-point compared to pogonion (Fischer-Brandies, 1985).

3. Crowding variable (crowding occur due to two problems: first LS retroclination and

secondly tooth arch length discrepancy)

4. Proclined laterals or might be retroclined if very high lower lip

5. Short upper laterals which might escape from the lip pressure and being proclined

6. Thin U1 and poor cingulum bulk. Roberston and Hilton 1965

7. Acute angle between crown and root.

8. Dental anomalies, Basdra 2000 found that there is an increased risk of impacted canine,

High risk of diminutive laterals.

E. Occlusal features

1. II angle

2. OB increased

3. Buccal-segment relationship is usually a mild class II, although it can be class I in cases of

bimaxillary retroclination. A full unit class II buccal-segment relationship is not common.

4. The overjet is normal or usually only slightly increased

5. Crossbites but mainly scissor bites.

6. In the upper arch there may be a reduced curve of Spee, while in the lower arch there is

increased and exaggerated curve of Spee

F. Mandibular function: sometime due to restricted mand movement by the deep OB, TMD

problem might arise.

G. IOTN

1. Mainly displacement 1-4D

2. Increased overbite 2-4F

3. Only in intermediate class II there is increased OJ 2-4A

4. Otherwise esthetic componenet play an important role in the IOTN determination

Treatment principles & aimsAccording to Selwan-Barnnet 1991, the aims of the treatment are:

1. Profile improvement where required and correcting the skeletal relationship if indicated

2. Correction of the rotation specially the laterals

3. Relieve crowding (expansion, IPS, distaliation, proclination, extraction)

4. Level and align the arches (intrude anterior, extrude posterior, procline anterior)

5. Correct increased overbite

6. Correct buccal segment relationships (distalization or extraction)

7. Correction of scissor bite

8. Achieve positive occlusal stop (centroid and II) correcting the edge to centroid relationship (lower

incisor should lie anterior to the upper root centroid) and decrease the interincisal angle

9. Correction of OJ if deviated from norms.

Treatment options

Factors to be considered:

1. Patient compliance

2. Clinician philosophy

3. Treatment mechanics

4. Patient age

5. Growth potential

6. Pattern of growth skeletal II deep bite correction is facilitated by favourable facial growth.

Inherent forward mandibular growth rotation tendency (anticlockwise) aids skeletal Class II

correction but tends to increase overbite unless the interincisal angle is altered and a cingulum

stop created. In an adult, overbite reduction by incisor intrusion rather than molar extrusion is

advisable as the latter is unlikely to be stable

7. The patient’s profile little objective difference exists in lip fullness between extraction and non-

extraction treatment, but the latter is favoured, particularly with bimaxillary retroclination. For an

unfavourable profile (marked skeletal Class II and very reduced FMPA) in an adult, a combined

surgical orthodontic approach is required

8. Underlying anteroposterior and vertical skeletal discrepancy. In general, the more Class II the

skeletal pattern and the more reduced the Frankfort-mandibular planes angle (FMPA), the more

difficult to achieve optimal dentofacial correction by orthodontic means alone.

9. The presence and degree of crowding. Avoid lower arch extractions as may encourage overbite

increase by retroclination of the labial segment. Because it is often trapped lingually by the upper

incisors, proclination of the lower incisors and mild intercanine expansion is possible to relieve

crowding and may be reasonably stable

10. Local factors Impacted maxillary canines/absent or small upper lateral incisors will require

orthodontic-oral surgical, orthodontic-restorative planning as appropriate

The treatment modalities for class II division 2 1. Accept

2. Interceptive orthodontic treatment

3. Growth modification

4. Fixed appliance therapy

5. Orthognathic surgery

6. Combination of the above

NB: high angle class II D2 would be treated similar to class II D1

1. Accept

In mild cases, the occlusion may be aesthetically and functionally satisfactory and so treatment is

not indicated.

Where the overbite is not very deep, it may be accepted and treatment directed towards alignment

of the lateral incisors if they are proclined.

2. Interceptive orthodontic treatment including the early use of HG+URA with ABP or HG and

lower lip pumper with social six fixed appliance (Nielsen, 1984)

3. Growth modification (orthopaedic/functional appliances) either:

A. It is mainly indicated in growing individuals, class II division 2 malocclusions with mild-to-

moderate skeletal class II base relationships and a class II buccal segment relationship.

B. One of the main problems of functional appliance is the lateral open bite at the end of the

functional stage. To address this, the appliance can either

Cribbing the lower first molars can be avoided to allow buccal segment eruption,

Cribbing the anterior teeth with clasps or acrylic coverage is recommended

The blocks selectively trimmed

Be worn on a part-time basis after the ap correction

Alternative functional appliances allowing differential eruption of the posterior dentition, such as

a median opening activator can be used.

C. Conversion to class II division 1 by

Bonding sectional FA on the ULS

Using ELASSA which is beneficial if using a monobloc-type functional appliance that does not

incorporate a midline expansion screw. Further, the ELSAA appliance can also incorporate an

anterior bite plane to start the process of overbite reduction.

Modification of the functional appliance for class II division 2 problem by incorporating a

cantilever spring or sectional screw added to the TB. This is a modification of Dyer and Sandler

2001.

Transition from functional to FA stage better with Steep and deep. Fleming 2007

4. Fixed appliance therapy with apical control techniques. Space can be provided:

A. Non-extraction basis by proclining LS if there is mild LLS crowding (Selwan-Barrnet) and

the OJ as well as the skeletal problem are very mild

B. Preserving Lee way space

C. IPS (BOS recommendation not more than 0.25 per side per tooth)

D. Molar distalization by

TAD for distalzation

lip pumper,

IO distalizer appliance

HG with URA as En mass appliance retraction with or without exraction of second molar or

usually before eruption of second molars.

Hg to molar bands

HG with URA as Nudger appliance

URA+anterior bite plane with low pull HG this is called Acrylic Cervical-Occipital (ACOA)

appliance popularized by Cetlin and Ten Hoeve (1983).

E. Class II bite corrector mechanics

F. Extraction of premolars or molars in the UA or both arches. However extraction might:

Makes OB worse.

However, Al-Mangoly 1993 found that extraction has no effects on the OB and

space closure if the correct mechanics is used.

If only upper arch extractions are prescribed, a tooth size discrepancy will result

due to the mesiodistal dimension of the upper premolar being greater than half the

mesiodistal dimension of the lower first molar. The excess space in the upper arch should

be taken up by a slight over-rotation of the upper first molar and over-torquing the upper

labial segment or using the MBT philosophy using the contralateral second molar tube on

the first molar

However, some authors have suggested that in borderline cases it would be a more

sound clinical approach to complete levelling, aligning and overbite reduction before a

final decision is made to extract teeth (Selwyn-Barnett, 1996).

Stelzig 1999, compare the result of extraction of the 5 and 7s and they found

the profile flatten more in 5s extraction however it flatten in both cases. The lower 8s

erupt in a better position in the 7 cases.

In fixed appliance treatment of class II division 2 the anchorage demand is high for many reasons? Presence of crowding

Canine angulation

Incisor inclination

Other intra and interarch problems like ML or OJ

What Are the Stages of Treatment Using the Tip Edge Appliance for this Patient?

i. Stage 1 of treatment involves overbite and overjet correction and correction of the molar

relationship. Initially, an appliance is placed on the upper labial segment only and a nickel–

titanium archwire placed to align the teeth, increasing the overjet as a result. Following this,

appliances are placed on the lower labial segment and upper and lower 016-inch stainless steel

by-pass arches are placed with tip-back bends mesial to the upper second and lower first molar

bands. Light class II elastics are worn on a full-time basis, which in combination with the tip-back

bends, facilitates overbite and overjet reduction.

ii. Stage 2 involves space closure. Once the overbite and overjet are fully reduced, the premolar

attachments and upper and lower 020-inch stainless steel wires are placed. Space is closed in the

maxillary arch using intra-arch elastics running from the upper second molars to circle loops on

the archwire, again supported by light class II traction.

iii. Stage 3 involves second- (angulation) and third- (torque) order correction. Once space is closed,

upper and lower 21   ×   25-inch stainless steel archwires are placed with auxiliary springs

inserted into the vertical bracket slots to express the correct angulation and torque for each

bracket prescription. (Parkhouse, 1998). More recently, a horizontal slot has been introduced in

the Tip Edge-PLUS ® bracket, which is situated deep to the main bracket slot. By placing a

flexible superelastic nickel– titanium archwire in this slot, the brackets can be uprighted without

the need for an auxiliary spring or sidewinder; a rigid rectangular archwire is present in the main

bracket slot, permitting torque expression (Parkhouse, 2007). Overall, this innovation has made

stage 3 a little less complicated for the orthodontist.

iv. Finally the lower second molars were bonded and settling elastics were run to a lower braided

rectangular steel archwire.

5. Orthognathic surgery

It mainly depend on the lower anterior facial height and the prominence of the chin as well as the

presence of maxillary retrognathia. Surgical option involves:

1. Mandibular advancement with 3 point landing.

2. Bimaxillary osteotomy with clockwise rotation.

3. Total subapical osteotomy of lower jaw.

4. Adjunctive procedure include:

On occasion a reduction genioplasty may also be required to optimise the profile.

Where the lower facial height is average or mildly increased, the overbite may be reduced by a

lower labial segment set-down at the time of surgery.

6. Combination of the above

Correcting the Overbite in class II division 2

This can be achieved by

a) Labial segment intrusion

maxillary incisor intrusion,

mandibular incisor intrusion,

b) Labial segment proclination

Lower incisor proclination,

Upper incisor proclination

This effect has been analysed by Eberhart et al (1990) who, for example, stated that 5 degrees of incisor

proclination would reduce the overbite by 1 mm on average.

c) posterior tooth extrusion

maxillary posterior tooth extrusion,

mandibular posterior tooth extrusion

d) surgery

Please refer to deep OB correction note

STABILITY

Kim 1999 found that the starting OB is the most important predictors, 50% maintained OB less than

4mm.

Canuat 1999 found II angle not related to stability and overcorrection because more relapse.

Criteria of good stability

1. Over-correction of the deep overbite to prevent vertical relapse. Leave it edge to edge.

2. Relative decrease of the lower lip cover

3. Torque of the lower incisors by positioning the lower incisal edge 0-2mm to upper centroid and

interincisal angle of 135 degree

4. Positive occlusal stop

5. Overcorrectin of rotation

6. favourable growth

7. good buccal interdigitation

8. minimal change in the LLS position

9. the use of permanent fixed retainer

Method of retentions

Fixed retainer

VFR

Active URA with anterior bite plane

CSF (reduced relapse by 20% Edward) (specially lateral incisors)

Build up the cingulum plateau

Cochrane review by Millet 2007, There is no scientific evidence to establish whether orthodontic

treatment, carried out without the removal of permanent teeth, in children with Class II division 2

malocclusion is better or worse than orthodontic treatment involving extraction of permanent

teeth or no orthodontic treatment. The same is revised in 2012 with same result.