Causes of Open bite, Deep bite, crowding, Generalized spacing, Midline distema, Scissor bite and Cross bite.

 

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Causes of Medline distema:

1.  Physiological as ugly duckling stage.

2.  Hereditary.

3.  Abnormal labial frenum attachment. (high) confirmed by Graber’s test or “Blanch test”.

4.  Mesiodens.

5.  Proclination of upper incisor.

6.  Peg laterals.

7.  Missing laterals.

8.  Deep bite.

9.  Midline cysts or thick inter-dental bone.

10.                Habits such as thumb sucking/ tongue thrusting.

 

Causes of generalized spacing:

1.  Large sized jaw – macrognathic

2.  Small sized teeth – microdontia, Peg shaped lateral.

3.  Hypodontia – missing teeth especially upper lateral incisors and lower second premolars.

4.  Proclination of anteriors – bigger arch width.

5.  Hereditary.

6.  Macroglossia.

7.  Impacted teeth

 

Causes of crowding:

1.  Small, constricted arches “V” shaped arch.

2.  Large teeth or macrodontia, supernumerary teeth.

3.  Retroclination of the anteriors.

4.  Mesial drift of the posterior.

5.  Mixed dentition crowding due to incisors liability.

6.  Lack of inter-dental spaces in primary dentition.

7.  Early loss of primary canine by ectopic eruption of lateral incisors.

8.  Ectopic eruption of upper first permanent molars.

9.  Supernumerary teeth.

10.                Hereditary.

11.                Retained deciduous teeth.

12.                Premature loss of deciduous teeth.

 

 

 

Causes of deep bite:

1.  Hereditary – genetic pattern or familial occurrence is common.

2.  Skeletal:

a) Over growth or under growth of one or more alveolar segments.

b)            A long vertical ramus with a short body and decreased gonial angle.

c) Convergent upper and lower jaw bases. Horizontal growth pattern or forward and upward rotation (anti clock wise) of lower jaw.

3.  Dental:

a) Loss of posterior teeth with decreased posterior dental height.

b)                        Lingual collapse of the anterior teeth.

c) Over eruption of the incisiors teeth, infra occlusion of the posteriors or both.

d)                        Abnormal tooth shape and size, oligodontia.

e) Periodontal disease.

4.  Mascular: strong and anterior attachment of lower jaw elevator muscles along with a heavy biting force may cause intrusion of the molars and create a deep bite.

5.  Habits: lateral tongue thrusting, thumb sucking.

 

Causes of open bite:

1.  Abnormal habits such as thumb sucking, tongue thrusting, lip biting or mouth breathing.

2.  Abnormal position of the tongue (high tongue posture).

3.  Adenoids with mouth breathing.

4.  TMJ problems.

5.  Abnormal skeletal growth of jaws. (skeletal open bite).

6.  Iatrogenic causes.

7.  Submerged tooth like lower deciduous second molar

8.  Increased anterior facial height with a decreased posterior facial height.

9.  Increased FMA/Mandibular plane angle. (steep angle).

10.       Dolicofacial/ leptoprosopic patient ( long and narrow face) with mandible having a short ramus and small body.

 

 

Causes of scissors bite:

1 Combination of excessive maxillary width and a narrow mandibular alveolar process.

 

Causes of the cross bite:

1.  Anterior cross bite

i. dental causes:

a)    Traumatic injury to primary dentition that cause a lingual displacement of permanent tooth bud.

Persistence of a deciduous tooth à palatal deflection of its erupting successor à single tooth anterior cross bite.

b)                        Supernumerary\ tooth.

c) A habit of biting the upper lip.

d)                        Cleft lip repair cases.

e) Arch length inadequacy à causing lingual deflection of permanent tooth during eruption.

ii. Skeletal causes:

a) Genetic.

b)                        Due to deficient anterior growth of maxilla.

c) Excessive abnormal mandibular growth in anteriorly.

d)                        Combination of both 2 and 3.

iii. Functional causes:

a)  Pseudo class III.

b)                        Habitual forward positioning of the mandible to obtain maximum intercuspation may lead to an anterior cross bite.

 

 

 

2.  Posterior cross bite

i.      Dental causes:

a) Prolonged retention of primary tooth.

b)                     Ectopic eruption of the permanent first molar.

c) Prolonged thumb or finger sucking.

d)                     Cleft palatal cases.

ii.  Skeletal

A)           Genetic.

B)           Due to deficient lateral growth of maxilla.

C)            Excessive abnormal mandibular growth laterally.

D)          Combination of both B and C.

iii.          Functional causes:

a) Unilateral posterior cross bite à due to occlusal interference à deviation of the mandible during jaw closure.