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Types of malocclusion
Prepared by
Dr. Mohammed Alruby
‫تصن‬ ‫التي‬ ‫القرارات‬
‫اوجعتك‬ ‫وان‬ ‫حتي‬ ‫صائبه‬ ‫الكرامه‬ ‫عها‬

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Types of malocclusion
Malocclusion can occur singly or in combination as follows:
1- Dental mal-relationship.
2- Dento-alveolar, involving the teeth and alveolar process.
3- Dental arch mal- relationship
4- Basal arch discrepancy
5- Cranio-facial abnormalities.
1- Dental mal relationship
Including crowding, spacing, ectopism and other local malposition of the teeth that not affect the
arch size, relationship and growth.
Causes of dental malposition:
1- genetic factors.
2- Prolonged retention or early loss of primary teeth.
3- Delayed eruption of permanent teeth.
4- Supernumerary teeth, missing teeth, either congenital or due to extractions.
5- Ectopic eruption and abnormal tooth morphology.
6- Abnormal development of the teeth.
Frequency:
=The most frequently malposed teeth in permanent dentition are the 3rd
molars, maxillary lateral
incisors, mandibular incisors, 2nd
premolars and 2nd
molars, the less frequently malposed teeth are the 1st
molars and 1st
premolars.
= spacing is predominating in deciduous dentition while crowding is common in permanent dentition.
= Irregularities due to local pot natal causes will manifest themselves clinically and will requires
corrective treatment.
= rotation of the teeth in most cases is a sequlea of crowding but sometimes occurs with spacing due to
loss of proximal contact between the erupting and adjacent teeth.
= crowding and spacing of the same arch may be expected in deciduous dentition but if occurs in
permanent dentition, it will represent a symptoms of tooth shifting and detective eruption due to local
interfere.
Spacing of permanent teeth:
In the permanent dentition, spacing in the maxillary arch is usually localized from canine to canine.
The median diastema in maxillary arch may be caused by:
1- Abnormal labial Frenum or presence of mesiodense
2- Dwarfed or congenitally absent lateral incisors.
3- Or as a part of generalized spacing.
Spacing in the mandibular arch is less common but may occurs due to:
1- Abnormal large tongue and bi dental protrusion.
2- Abnormal lingual Frenum ----- median diastema.
3- As a part of generalized spacing.
Loss of space or space closure:
a- In mixed dentition:
= In children with well-developed arches, there is little or no space loss after extraction of primary
molars, this may be due to the cuspal interlocking of U and L 6
= There will be more space loss after extraction of E then after extraction of D
= loss of UE before the eruption of UB causes the U6 to erupt far mesially toward UD occupying the
space required for eruption of U5------ impaction of U5.
= in the mandibular arch the forward shifting of L6 is less great and space loss is less marked.

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= the order of eruption of permanent teeth has some effect on determining the space closure. For
example: the maxillary canine may block out labially because it erupts after U4, the mandibular 2nd
bicuspids may block out lingually because it is the last tooth erupt in the front of L6.
b- In permanent dentition:
= space loss following extraction of permanent teeth is faster and more pronounced in the maxillary than
mandibular arch due to the mesial migration of the teeth posterior the extraction site, while in
mandibular arch the space loss occurs mainly by distal shifting of the teeth anterior to the extraction site.
This is accompanied by lack of forward growth of anterior teeth and shifting of midline toward the
extraction site.
Treatment of space problems in permanent dentition:
a- Treatment of mutilated or incomplete dentition:
In cases of extraction of permanent teeth or missing permanent teeth the decision must be made whether
the space could be closed or opened, this depend on:
1- The presence or absence of natural teeth in opposing dental arch.
2- The usefulness of the teeth for prosthetic restoration.
3- The general characters of dentition.
4- Size and shape of the dental arches.
b- Missing lateral incisors:
When upper laterals are missing the plane of treatment is influenced by:
1- The age of pt.
2- Shape and size of upper canines.
3- The axial inclination and shifting of upper canines and premolars.
4- The type of occlusion.
5- Size of the basal arch.
6- Function of the lips and tongue.
7- The developmental tendency of the jaws.
It is preferable to extract the UB 2 or 3 years before eruption of U canines when crowding is expected,
the permanent canines will erupt distal to the U1, then reshape to the form of lateral incisors.
c- Missing premolars:
The most commonly missing premolars are L 5.
If crowding is expected, extraction of L E it indicated to place L4 in proper alignment. In well-developed
arch the L E is left if the jaws growth will favor retention of the teeth in good occlusion, serial
examination is necessary.
d- Blocked out premolars:
If the teeth are well aligned, space opening is contraindicated, and the blocked out premolars should
be extracted.
e- Malformed teeth:
Congenitally or traumatically malformed teeth in the anterior region where jacket crown cannot
construct should be removed.
2- Dento- alveolar Malocclusion
Dento-alveolar malocclusion may be caused by:
1- Disproportion between the size of teeth and size of dental arch which may result in crowding or
spacing.
2- Abnormal vertical growth of alveolar process:
= over development of anterior alveolar process with excessive over bite and over jet of anterior
teeth.

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= arrested development of anterior alveolar process ---- anterior open bite.
= arrested development of posterior alveolar process ---- posterior open bite.
3- Abnormal transverse growth of alveolar process ----- posterior cross bite.
4- Malposition of individual teeth caused by arch length – tooth size discrepancies or teeth
migration due to periodontal disease, extraction, infection or pressure habits.
5- Mal-alignments deficiency of the dental arches as whole.
Arch length deficiency:
May result in crowding or bi-maxillary protrusion.
Crowding:
Is more common in the lower arch than the maxillary arch and tend to increase with age especially
during eruption of L 8.
Bi-maxillary protrusion:
Bi-maxillary protrusion shows genetic distribution and may be considered as a normal finding in some
ethnic group as negro, bi- maxillary protrusion should differentiate from mand. Or max. prognathism
Over bite:
Factors considered in over bite:
1- The angulation of occlusal plane.
2- The inter-incisal angle
3- The length of mandible and maxilla.
4- The anterior and posterior position of the jaws.
5- The sequence of eruption of the teeth: stage of the dental development.
6- Local interference in the occlusion as: mesial shift and over eruption of molars.
7- Abnormal morphology and location of TMJ.
8- The length of the ramus, MPA, and the size of the body of the mandible.
9- The clivus angle.
10- The degree of mandibular growth and the size of the teeth.
11- Height of incisors teeth.
NB; normal over bite: it is better expressed in ratio than in mm, normal over bite is about 25% of
mandibular incisors crown height (about one third) also 25% to 40% may considered normal if no
functional disturbances.
Molar eruption is not determining factor in the severity of over bite, but with complete eruption of canine
and premolars, the over bite in permanent dentition is established.
According to Baume, normal sequence of eruption in lower arch is 3,4,5 and 4,5,3 in upper arch will
result in normal over bite.
NB: abnormal over bite, may be excessive over bite or open bite.
= excessive over bite is more prevalent in mixed dentition and tend to be corrected in late mixed
dentition
= it is also prevalent in early deciduous dentition and reduced with eruption of primary molars. (stage of
dental development)
= when the inter-incisal angle is larger than 150 degrees, the maxillary incisors may guide the mandible
into over closure in which the lateral movement of the mandible cannot be obtained without opening of
the jaw to appreciable degree.
= when the amount of overjet in increase, there is lack of incisal stop, the incisor still erupts until:
1- Their vertical growth ceased
2- Balanced masticatory forces.
3- Reach the soft tissues.
= grinding of incisors to relief the soft tissue traumatization is contraindicated, since they will elongate
again.

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= open bite: it is failure of the teeth to meet its antagonist when the mandible is brought into centric
occlusal position.
= open bite can occur in all types of malocclusion, but it is a characteristic of long face syndrome, and
should be treated as early as possible.
Etiology of open bite:
1- Dental: may occur due to:
= the presence of mechanical interference between the maxillary and mandibular segment as;
thumb sucking, tongue thrust.
= disturbance in eruption and alveolar growth as; lack of eruptive force or ankyloses of the teeth.
= dental open bite may or may not associated with skeletal discrepancies.
2- Skeletal: occurs as a result of sever osseous dysplasia, or mandibular prognathism (sever Class
III) or vertical dysplasia as: increase the vertical mandibular growth component.
3- Muscular: week mandibular elevators acting against strong mandibular depressor evidenced by
the deep anti-gonial notch
= abnormal over jet: may be due to skeletal factors, maxillary prognathism, or mandibular retro-
gnathism.
1- Dental factors: abnormal inclination of maxillary and /or mandibular incisors.
= protrusion of maxillary teeth: may be due to: hypotonic upper lip, thumb sucking, tongue thrust.
=retrusion of mandibular teeth for any reason: hyper active mentalis, lip sucking, lip biting.
2- Dento alveolar factors: the difference in the amount of dentoalveolar protrusion in the respective
jaws.
= the exact cause of abnormal over jet, must be determined before treatment is undertaken.
= reversed over jet seen in sever Class III cases.
=Anterior cross bite: may be due to
1- Dental factors:
= abnormal inclination of one or more of maxillary and /or mandibular teeth.
= premature contact and translocated or forward mandibular over closure, (pseudo Class III),
usually the area of interference is located at primary canine regions.
2- Skeletal factors:
= skeletal Class III may be due to maxillary deficiency or mandibular prognathism.
= posterior cross bite: may be due to
1- Dental factors:
= abnormal axial inclination or malposition of one or more maxillary and /or mandibular teeth.
= premature contact and shifting of mandibular laterally
2- Dentoalveolar:
= unilateral or bilateral collapse of maxilla------ buccal cross bite
= unilateral or bilateral collapse of mandible------ lingual cross bite.
3- Skeletal:
= a symmetry of the basal bones of maxillary and /or mandibular arch in transverse direction.
= types: maxillary buccal cross bite, maxillary lingual cross bite,
mandibular buccal cross bite, mandibular lingual cross bite.
Cross bite in deciduous teeth:
==Tend to appear when deciduous canines appear between 18 months and 2 years. The canines show
cusp to cusp relationship while the mandibular shift to the right or to left anteriorly, in deciduous teeth
cross bite not cause facial a symmetry and may unnoticed and untreated, but of persist in mixed
dentition, it is more likely to cause facial a symmetry. The midline of the teeth is shifted, the maxillary
canines and the mandibular lateral incisors may be blocked out of the dental arch.
== cross bite should be treated as early as possible, since anterior cross bite may interfere with normal
forward growth of maxilla and posterior cross bite may interfere with transverse growth of the jaws in
addition----- causing gross facial a symmetry and TMJ dysfunction.

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== in deciduous dentition between 3 and 5 years, fixed appliance may be used. In mixed dentition,
removable appliances that will not interfere with normal eruption of permanent teeth are indicated.
Cross bite in permanent dentition:
== cross elastics may be used but it is not helpful in correction of skeletal lateral deviations.
== expansion screw is effective in correction of maxillary constriction and even splitting mid palatal
suture in young children. The exact cause of cross bite should be detected before treatment planning by
careful cast analysis to determine the site of a symmetry.
3-Dental arch Malrelatioship
1- Positional deviation:
= antero-posteriorly: Class II, Class III.
= transverse: Bucco-lingually: posterior cross bite.
= vertical: openbite, deep bite.
2- Dimensional deviation:
Abnormality of the size of jaws in relation to each other:
Maxillary micrognathia ------ normal mandible
Maxillary macrognathia -----normal mandible
Mandibular micrognathia ----- normal maxilla.
Mandibular macrognathia ---- normal maxilla.
Combination of both.
Dimensional deviations:
Basal arch deficiency:
=basal arches defined as the areas which extends around the jaws at the most constricted part in the
body of maxilla and mandible, subjacent to the maxillary alveolar process and subjacent to the
mandibular alveolar process.
= basal arches are parallel to the alveolar process, they include the A point in maxilla and B point in
mandible and axel- landstrom apical bases.
= basal arch deficiency may be uni-maxillary or bi- maxillary.
= basal arch deficiency may be result in crowding, impaction or procumbancy of incisors.
= vertical deficiency of basal arches --- decrease in ANS-Me dimensions (decrease LAFH)
Tooth size – basal arch length discrepancies:
= small teeth and large basal arch will result in spacing.
=large teeth and small basal arch will result in crowding.
Treatment of large basal arch:
= in this case spacing will occur and teeth arrangement will depend primarily on muscular pressure
including tongue, lips, cheeks musculatures. When the teeth are inclined lingually or moved behind the
area of functional tolerance in the presence of large basal arch, they will return to their original position
dictated by the forces on occlusion produced during function and spacing will recur.
constricted basal arch:
= in these cases, crowding will occur crowding of mandibular incisors and other teeth will occur, but if
normal arrangement is maintained, the teeth will show procumbent relationship to the mandibular plane.
= basal arch deficiency may be due to lack of posterior growth at the maxillary tuberosity in maxilla or
at the inner border of ramus of mandible.

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Expansion of dental arches:
Derichs weiler(1953), described splitting of the palatal suture for treatment of constricted maxilla, two
bands are placed on the permanent molars, primary molars or premolars, attached to a highly polished
acrylic split plate with expansion screw. This appliance should remain in place at least 3 months which
the screw is open daily, followed by retention period at least 3 months. This method is believed to relief
certain type of nasal obstruction.
= expansion can also have achieved by uprighting of the teeth, if the size of basal arch permit such
expansion (how analysis is helpful in these cases.
= stability of the dental arches after expansion depends on:
1- Adequate functional activity and proper muscle function.
2- Sufficient basal bone.
3- Correction of malocclusion.
4- Growth potential.
5- Elimination of pressure habits.
= expansion in inter-canine region usually followed by relapse, inter-canine width cannot be increased
by orthodontic treatment after growth is completed.
= the maxillary arch will tolerate more expansion than the mandibular arch.
= narrow dental arch may be normal in certain facial types.
Clinical manifestation of malocclusion:
Malocclusion among population occurs in decreasing frequency as:
1- Intra-maxillary crowding mainly due to local interfering factors
2- Inter-maxillary dental occlusal relationship with or without jaws mal-relationship.
3- Disproportion in the overall jaw development and growth.
4- Combination of dental irregularities and mal-development and mal-relationship of the jaws
4-craniofacial abnormalities
=Small clavius angle (cranial base angle) (Nasion, sella, basion) is associated with less deep
maxilla------- mandibular prognathism even when the mandible is of normal size.
= obtuse clavius angle require changed maxilla and may cause mandibular retrusion even when the
mandible is of normal length and position.
= relatively horizontal anterior cranial base (parallel to FH plane) make the posterior part of the
face occupy higher position of the skull, and maxilla tipped downward anteriorly----- abnormal steep
mandibular plane and mandibular retrusion. But if maxilla not tipped downward anteriorly---- the
palatal plane remains parallel to FH and SN and Mandibular plane too------- skeletal deep bite case
with reduced MPA.
= steep inclination of anterior cranial base causes the posterior part of the face to occupies a low
level in the skull with horizontal mandibular plane in most cases.
With my best wishes;;;;;;;
Dr. Alruby