08 August 2012

MALOCCLUSION | Orthodontic Dentistry


A malocclusion is a misalignment of teeth and incorrect relation between the teeth of the two dental arches. The term defined by Edward angel, the “Father of modern orthodontics.

Etiology of malocclusion

Graber’s classification
General factors
1. Heredity
2. Congenital
3. Environment
    a) Prenatal (trauma, maternal diet, German measles, maternal metabolism etc.)
    b) Post natal ( birth injury, cerebral palsy, T.M.J. injury )
4. Pre-disposing metabolic climate and disease
    a) Endocrine imbalance
    b) Metabolic disturbance
    c) Infectious disease
5. Dietary problems ( nutritional deficiency )
6. Abnormal pressure habits and functional aberrations
    a) Abnormal sucking
    b) Thumb and finger sucking
    c) Tongue thrust and tongue sucking
    d) Lip and nail biting
    e) Abnormal swallowing habits
     (Improper deglutition)
    f) Speech defects
    g) Respiratory abnormalities
     (Mouth breathing etc,)
    h) Tonsils and adenoids
    i) Psychogenic tics and bruxim
    j) Posture
    k) Trauma and accidents

Local Factors
  1. Anomalies of number : Supernumerary teeth, Missing teeth (congenital absence or loss due to accidents, caries, etc)
  2. Anomalies of tooth size
  3. Anomalies of tooth shape
  4. Abnormal labial frenum : mucosal barriers
  5. Premature loss
  6. Prolonged retention
  7. Delayed eruption of permanent teeth
  8. Abnormal eruptive path
  9. Ankylosis
  10. Dental caries
  11. Improper dental restorations
WHITE AND GARDINER’S CLASSIFICATION
A. Dental base abnormalities
  1. Antero-posterior malrelationship
  2. Vertical malrelationship
  3. Lateral malrelantionship
  4. Disproportion of size between teeth and basal bone
  5. Congenital abnormalities
B. Pre-eruption abnormalities
  1. Abnormalities in position of developing tooth germ
  2. Missing teeth
  3. Supernumerary teeth and teeth abnormal in form
  4. Prolonged retention of deciduous teeth
  5. Large labial frenum
  6. Traumatic injury
C. Post-eruption abnormalities
  1. Muscular
    • Active muscle force
    • Rest position of musculature
    • Sucking habits
    • Abnormalities in path of closure
  2. Premature loss of deciduous teeth
  3. Extraction of permanent teeth
TYPES OF MALOCCLUSION
Malocclusion can be broadly divided into
  1. Individual teeth malposition or intra arch malocclusion
  2. Malrelation of dental arches to one another upon bony bases which may themselves be normally related.
  3. Skeletal malocclusion which involve the underlying bony bases.

INDIVIDUAL TEETH MALPOSITION
A tooth can be abnormally related to its neighboring teeth such abnormally related to its neighboring variations are called individual teeth malposition or intra arch malocclusion. Some commonly seen individual teeth malpositions are
  1. Distal inclination or distal tipping
  2. Mesial inclination or mesial tipping
  3. Lingual inclination or lingual tipping. This condition is also called retroclination
  4. Buccal inclination or Buccal tipping. This refers to labial or buccal tilting of tooth. This condition is also called proclination.
  5. Mesial displacement
  6. Distal displacement
  7. Lingual displacement
  8. Buccal displacement
  9. Infraversion or infraocclusion
  10. Supraversion or supraocclusion
  11. Rotations
  12. Disto-lingual or mesio-buccal rotation
  13. Mesio-lingual or disto-buccal rotation
  14. Transposition
MALRELATION OF DENTAL ARCHES

These malocclusions are characterized by abnormal relationship between two teeth or groups of teeth of one arch to the other arch.
These interarch malooclusion can occur in the saggital vertical or in transverse planes of space.

A) Saggital plane malocclusion
Pre normal occlusion
This term refers to a condition where the lower arch is more forwardally placed when the patient bites in centric occlusion.
Post normal occlusion
This is a condition where the lower arch is more distally placed when the patient bites in centric occlusion.

B) Vertical plane malocclusions
Deep Bite or increased over bite
This refers to a condition where there is an excessive vertical overlap between upper and lower anterior teeth.
Open bite 
This is condition where there is no vertical overlap between the upper and lower teeth.
Thus space exist between the upper and lower teeth when patient bites in centric occlusion. The open bite can be in the anterior or posterior region .

C) Transverse plane malocclusions
The transverse plane interarch malocclusion includes various types of cross bites. The term cross bite refers to abnormal transverse relationship between the upper and lower arches.

Skeletal Malocclusions
They are malooclusions caused due to defects in the maxilla or mandible. The defects can be in size, position or relationship between the jaws.

IMAGES 


ANGEL’S SYSTEM OF CLASSIFICATION
Edward Angel introduced a system of classifying malocclusion in the year 1899.

Basis for Angel’s classification

The Angel’s classification is based on the following criteria :
   a) Angel’s classification was based on the mesio-distal relation of the teeth, dental arches and the jaws.
   b) According to Angel, the maxillary first permanent molar is key to occlusion. He considered these teeth as fixed anatomical points within jaws.
   c) Based on the relation of the lower first permanent molar to the upper permanent molar, he classified malocclusions into three main classes designated by the Roman numerals one, two, and three.

Based on the above mentioned principles, Angel classified malocclusion into the following broad categories.
Class I
Class II
       Division 1
       Division 2
Class III

Angle’s Class I classification of malocclusion
Angle’s Class I classification of malocclusion is characterized by the presence of a normal inter-arch molar relation. The mesio-buccal cusp of the maxillary first permanent molar occludes in the buccal groove of mandibular first permanent molar. The patient may exhibit dental irregularities such as crowding, spacing, rotations, missing tooth, etc.

These patients exhibit normal skeletal relation and also show normal muscle function. Another malocclusion that is most often categorized under Class I is bi-maxillary protrusion where the patient exhibits a normal Class I molar relationship but the dentition of both the upper and lower arches are forwardly placed in relation to the facial profile.

Angle’s Class II classification of malocclusion
This group is characterized by a Class II molar relation where the disto-buccal cusp of the upper first permanent molar occludes in the buccal groove of the lower first permanent molar. Angle has sub-classified 

Class II malocclusion into two divisions:
Class II, Division 1 classification of malocclusion
The Class II, Division 1 classification of malocclusion is characterized by proclined upper incisors with a resultant increase in over jet. A deep incisor overbite can occur in the anterior region. A characteristic feature of this malocclusion is the presence of abnormal muscle activity. The upper lip is usually hypotonic, short and fails to form a lip seal.

The lower lip cushions the palatal aspect of the upper teeth, a feature typical of a Class II classification of malocclusion, Division 1 referred to as ‘lip trap’. The tongue occupies a lower posture thereby failing to counteract the buccinator activity. The unrestrained buccinator activity results in narrowing of the upper arch at the premolar and canine regions thereby producing a V-shaped upper arch.

Another muscle aberration is a hyper-active mentalis activity. The muscle imbalance is produced by a hyper-active buccinator and mentalis and an altered tongue position that accentuates the narrowing of the upper dental arch.

Class II, Division 2 classification of malocclusion
As in Class II, Division 1 classification of malocclusion, the Division 2 also exhibits a Class II molar relationship. The classic feature of this malocclusion is the presence of lingually inclined upper central incisors and labially tipped upper lateral incisors overlapping the central incisors. Variations of these forms are lingually inclined central incisor and lateral incisors with canine labiallytipped. The patients exhibit a deep anterior overbite.

The lingually inclined upper centrals give the arch a squarish appearance, unlike the narrow V-shaped arch seen in Division 1 classification of malocclusion. The mandibular labial gingival tissue is often traumatized by the excessively tipped upper central incisors. The patients exhibit normal perioral muscle activity. An abnormal backward path of closure may also be present due to the excessively tipped central incisors.

Class II, Subdivision classification of malocclusion
When a ClassII molar relation exists on one side and a Class I relation on the other, it is referred to as Class II, Subdivision. Based on whether it is a Division 1 or Division 2 it can be called Class II, Division 1, Subdivision or Class II, Division  2, Subdivision.

Class III malocclusion classification of malocclusion
This malocclusion exhibits a Class III molar relation with the mesio-buccal cusp of the maxillary first permanent molar occluding in the interdental space between the mandibular first and second molars. Class III classification of malocclusion can be classified into true Class III and pseudo Class III.

True Class III classification of malocclusion

This is a skeletal Class III classification of malocclusion of genetic origin that can occur due to the following causes:
    a. Excessively large mandible.
    b. Forwardly placed mandible
    c. Smaller than normal maxilla.
    d. Retro positioned maxilla.
    e. Combination of the above causes

The lower incisors tend to be lingually inclined. The patient can present with a normal overjet, an edge to edge incisor relation or an anterior cross bite. The space available for the tongue is usually more. Thus the tongue occupies a lower position, resulting in a narrow upper arch.

Pseudo Class III classification of malocclusion
This type of malocclusion is produced by a forward movement of the mandible during jaw closure thus it is also called ‘postural’ or ‘habitual’ Class III classification of malocclusion. The following are some of the causes of pseudo Class III malocclusion:
a. Presenc
e of occlusal prematurity may deflect the mandible forward.
b. In case of premature loss of deciduous posteriors, the child tends to move the mandible forwardtoestablishcontactinanteriorregion.
c. A child with enlarged adenoids tends to move the mandible forward in an attempt to prevent the tongue from contacting the adenoids.


Class III Subdivision classification of malocclusion
This is a condition characterized by a Class III molar relation on one side and a Class I relation on the other side.



A. class I crowding  |  B. class II bimaxillary protrusion | c. spacing
d. spacing | e. classII division I | f. class II division II | g. Anterior cross bite
h. Anterior cross bite


(I) Anterior cross bite | (J) Posterior cross bite | (k) Rotation | (L) Midline diastema |
 (M) & (N) Anterior open bite | (O) & (P) Deep bite




Drawbacks of Angle’s classification
Angel’s classification has been used for almost a hundred years now; it still has a number of drawbacks that include:
  1. Angel considered malocclusion only in the antero-posterior plane. He did not consider malocclusions in the transverse and vertical planes.
  2. Angel considered the first permanent molars as fixed points in the skull. But this is not found to be so.
  3. The classification cannot be applied if the first permanent molars are extracted or missing.
  4. The classification cannot be applied to deciduous dentition.
  5. The classification does not differentiate between skeletal and dental malocclusion.
  6. The classification does not highlight the etiology of the malocclusion.
  7. Individual tooth malpositions have not been considered by Angle.

0 Responses to “MALOCCLUSION | Orthodontic Dentistry”

Post a Comment