Class II division 2 Malocclusion in Orthodontics

 

if you are intersted in this article please follow for more readings

https://myorthodonticsblogg.blogspot.com/      👈🏻

Class II Division 2 (definition) :

Acc. To Angle’s Classification

It is when the buccal groove of the 1^st Mandibular molar occludes distal to mesio-buccal cusp of 1^st maxillary molar with retroclination of maxillary central incisors.

Acc. To British Standards classification (Incisor relationship)

The lower incisors edgs occlude posteriorly to the

 cingulum plateau of the upper incisors &

 the lower centrals are retruded (due to lack of stops)

Sub-types

Type A : Maxillary centrals and     laterals are retroclined.

Type B : Maxillary Laterals overlapping the retroclined centrals .

Type C :Maxillary centrals and laterals areretroclined and are overlapped by max. canines.

 

Criteria

Extra Oral features :

- Shape of head : Brachycephalic

- Facial Profile : Convex / Straight

- Chin : prominent

- Lower lip : Everted (lower lip line is high relative to upper incisors ) because of deep bite

- Upper lip : positioned high (Gummy smile )

- Mento-labial sulcus : Deep

- Mentalis Muscle : Hyper active

Intra Oral features  :

-Class II molar relation (Disto occlusion)

- Class II canine relation

- Retroclined maxillary centrals (Extruded)

- Labially tipped maxillary lateral incisors

- Deep bite : Over closure (over bite)

- Accentuated Curve of Spee

-                      - Retroclined Lower incisors (Extruded because of lack of stops)

Etiology

- Class II division 2 malocclusion arise from a number of interrelated dental , skeletal , soft tissue and genetic factors.

- Most of Class II div. 2 malocclusions are caused by an underlying skeletal discrepancy and few have normal skeletal jaw relationship.

                                     Class II div 2

                      Dental                        Skeletal

                                     Both Dental

                                       & skeletal

Dental class II Div.2

-          Normal Maxillo-mandibular skeletal relationship.                                         

-          Mainly occurs due to mesial drift of the maxillary 1^st molar                           

As a result of :

a)      Loss of mesial proximal contact with primary 2^nd molar

-          Premature loss/extraction of primary 2^nd molar

-          Congenitally missing primary 2^nd molar

b)      Inter arch tooth size discrepancy

-          Small /Congenitally missing maxillary permanent  teeth (2^nd premolar) 

c)   Maxillary canine or 2^nd premolar impaction or displacement out of arch (inadequate space in dental arch )

Skeletal class II Div.2

Results from a discrepancy in the maxillary-mandibular skeletal relationship.

Skeletal class II relation is associated with a class II dental malocclusion as result of natural dental compensation to makes the skeletal disharmony less severe.

                                Skeletal class II

            Mandibular deficiency            Maxillary Excess

                                               Combination

                                                    of both

 

Class II/2 Mandibular deficiency

I)            Small

The decreased size is localized more to the mandible body ( mandibular ramus is of normal length).

Cephalometrically

1)      Flat mandibular plane

2)      Increase posterior facial height

3)      Short lower anterior facial height (resulting in both upper and lower lip having more everted position at rest )

4)      Mandibular length measured from (Ar-Gn-Pog) may appear normal because of the excessive chin projection

5)      SNA: Normal ,  SNB: Increase ,  ANB: Decreased

II ) Retruded Mandible relative to normal Maxilla

Result from the retrusion (Distal positioning) of a normal sized mandible.

Cephalometically

SNA: Normal , SNB: Increase ,  ANB: Decreased

Distinguishing characterstics                                                                                 

a)      The cranial base defined by (S-N-Basion).

b)      Glenoid fossa in arelatively posterior in position.

c)       Normal mower facial height.

Class II/2 Maxillary Excess

I) Vertical dimension

-          Vertical maxillary excess may be localized only to the poserior area results in open bite & incompetent lips (normal vertical display of maxillary incisor in repose and during smile).

-          Overall maxillary excess includes both the anterior and posterior area which result in an excessive vertical display of the maxillary incisors in repos and during smile (high smile line) (gummy smile and incompetent lips)

Cephalometrically

SNA: Normal , SNB: decreased ,  ANB: Increased

a)      Increase lower anterior facial height

b)      Steeper mandibular plane

c)       More inferior position of maxillary molars  relative to  palatal plane.

d)      Clock wise rotation of the mandible.

II) Antero-Posterior dimension

Characterized by :Protrusion of the mid face including

1)      Nose

2)      Infra orbital area

3)  Upper lip

Cephalometrically  : SNA: Increased, SNB: Normal ,  ANB: Decreased

-          Increased face convexity

-          Overjet : excessive

-          Over eruption of mandibular incisors

-        Excessive overbite

-          If the midface protrusion is severe then lower lip will be positioned lingual to the maxillary incisors encouraging there protrusion.

Diagnosis

-Decision making in orthodontics requires establishment of a problem list before considering the ttt options (3D: soft tissue ,dento-alveolar ,skeletal).

-Therefore to establish a proper diagnosis , we should create an adequate data base (Data collection).

1)Questionnaire interview

2)Clinical examination                Data base       Problem        Diagnosis

3)Diagnostic records                                             listing

 

 

1)      Patient interview

- chief complain : to find what is important to the patient.

- Medical and dental history.

- Physical growth status (Age and sex) = Growing or Non-growing.

-Motivation and expectation.

        2) Clinical examination

-          To evaluate facial , occlusal and functional characterstics (extra/Intra Oral)

-          Proper evaluation of the face , smile and profile to define esthetic problem list.

 3) Evaluation of diagnostic records

  Diagnostic casts.

Radiographic records : lateral ceph./ panoramic x.ray.

Photographs : -  frontal /frontal dynamic :posed smile.

                 -   close up image of posed smile

                -   ¾ view

                -  Profile

 

Treatment planning :Problem Potential approach  

-           After eval. of the collected data base & establishment of prioritized problem list , we should start thinking about the potential solutions of these problems ( Ttt planning)

-          The ttt plan describes the procedures meant to correct each problem on the list.

Treatment options for class II div.2

Any characteristics of malocclusions (3 ranges of correction exists)

A range of correction that can be accomplished by orthodontic tooth movement alone .

A larger amount that can be accomplished by orthodontic tooth movement  aided by absolute anchorage .

Additional amount that can be achieved by functional & orthopedic ttt ( Growth modification )

A large range of correction that requires surgery as apart of ttt plan.

The range of tooth movement for a patient is determined by :

1) Severity of malocclusions.

2) Age of the patient  (Growing /Non growing ).

3) Facial esthetics.

Timing of the treatment

Is an important factor in the amount of change that can be produced .

Optimum time for growth modification at pre-pubertal  growth spurt .

Therefore, proper diagnosis of the patient at early age & the use of correct functional appliances will cause the patient to avoid surgery.

Limitaions

I)Limitation of orthodontic treatment

Epker envelope of discrepancy : represents the maximum amount of tooth movement possible by 3 different means of ttt : ( Orthodontic/ Orthopedic /Orthognathic )

It has 3 envelops : the perimeter of each envelope gives the maximum range of movements possible by different methods of ttt.

Inner envelop : orthodontic ttt

Middle envelope : Orthodontic & Growth modification

Outer most envelope : Orthognathic surgery

II)Soft Tissue Limitations

Functional Stability

Facial Esthetic

Limitations in orthodontic ttt related to the oft tissue :-

Pressure exerted from teeth from lips , cheeks & tongue.

Periodontal attachment.

Neuro-muscular influence on mandibular position.

Lip-tooth relationship ( anterior tooth display during facial animation).

 

Treatment of class II/2

I)Dental

Orthodontic ttt (Extraction/Non extraction)

Depending on

-          The severity of mesial drift of maxillary 1^st molar.

-          Slight mesial drift (mesial crown tipping) & minimal crowding managed by by non extraction and distalization of maxillary 1^st molar.

-          Severe mesial drift ( root and crown are mesially positioned) managed by extraction to obtain space. 

II)Skeletal

1)      Growth modification (growing patient)

-          The goal of orthopedic treatment is to enhance the unacceptable skeletal relationship by modifying remaining facial growth pattern of the jaws.

-          Optimum timing : pre-pubertal growth spurt ( active growth period)

Two types of appliances is used in skeletal class II/2:

1- Headgear (Extra oral force)

2- Functional appliances (Removable/Fixed)

1) Headgear (facebow: Max. excess/J-hooks: Max. Ant. retraction & Intrusion)

It delivers an extra oral orthopedic force to compress the maxillary sutures & modify the pattern of bone apposition at the these sites.

Headgear extra-oral part (support)

I)Cervical

-          Distal & exrusive force on maxillary molars

-          Posterior & inferior extra-oral forces

-          Increase vertical dimension

Used in antero-posterior maxillary excess with flat mandibular plane

II) Occipital

-          Distal & intrusion forces on maxillary molars

-          Extra oral forces are directed superiorly

-          Antero-posterior maxillary excess poseterior (decreased vertical dimension).

2) Functional appliances

Are designed to position the mandible in a downward and forward  to enhance it’s mandibular growth pattern.

Indication: Mandibular  deficiency

Removable                                            Fixed

1)      Activator                                                  Herbst

 1)      Bionator                                                   Jasper Jumper

2)      Twin block

4)   Frankyl II

2) Dental Camouflage

It is a treatment that seeks to create a dental compensation to hide the skeletal discrepancy hat lead to maxillary retroclination and mandibular protraction.

Indications

1- adults

2- Mild to moderate skeletal class II cases

3- Acceptable facial esthetics

4- usually requires extraction.

Dental camouflage without extraction is rare in skeletal class II

a)      Mild skeletal class II

b)      Mild excessive overjet

c)       Adequate space available

d)      Maxillary molar distalization

 3)Orthognathic Surgery

Combination of orthodontic therapy & orthognathic surgery for the correction of moderate to severe class II malocclusions ( adults –No growth potentials )

Indications

1- Moderate to severe skeletal  discrepancy.

2- Facial imblalnce of asymmetries : long lowe face ,gummy smile.

3- Limitations of tooth movements : Upright on basal bone.

4- Relapse potential of orthodontic treatment.

5- Severe crowding and protrusion in dental arches with skeletal class II malocclusion ( extraction space is not sufficient to correct buccal occlusion).

 Surgical correction includes

I) Mandibular advancement:

Indicated: skeletal class II with mandibular deficiency .

The intra-oral sagittal split osteotomy is the most popular technique for surgical mandibular advancement.

II) Maxillary impaction (Le Fort I maxillary osteotomy) :

Indicated : vertical maxillary excess

Maxillary impaction may include

1- Total maxillary osteotomy ( Maxillary excess Ant. & Post.)

2- bilateral posterior segmental maxillary osteotomy (excess localized poserior)

Vertical Maxillary excess in the anterior and posterior region of maxilla

It requires maxillary impaction by total maxillary osteotomy.

To correct:

1- Gummy smile

2- Excessive lower facial height

3- Incompetent lips

4- Mandible will rotate anti-clock wise

Anterior Maxillary sub-apical setback

Indicated : Maxillary excess is in A-P dimensional mid-face protrusion(No vertical excess).

Combined Surgical appraoches

Indicated : maxillary excess (Vertical or A-P)combined with mandibular deficiency.

 

Strong Consideration of surgical correction of a class II div 2 with skeletal discrepancy should be based on the following questions:

1- Do the patient’s goal for treatment place a high priority on improvement in facial esthetics

2- Are the orthodontic movements required in excess of the envelope of discrepancy so that adequate orthodontic correction may not be achieved ?

3- Are the risks of surgery within acceptable levels ?

4- Are the benefits of surgical treatment as previously described, obvious ?