1. 1
Dr. Mohammed Alruby
Cross bite
Prepared by Dr.
Mohammed Alruby

2. 2
Dr. Mohammed Alruby
Cross bite
Definition: failure of the two dental arches to occlude normally in bucco-lingual or labiolingual
direction due to:
1- Localized problem of tooth position or alveolar growth
2- Gross disharmony between maxilla and mandible
Anterior cross bite:
= can be present in primary as well as permanent dentition
= it may involve one or more teeth
= it is one of the most common malocclusion present in children
= it should be treated immediately because it is very rarely to self-correcting
= it can be predisposing to the development of class III malocclusion if two or more teeth are
involved
Causes:
= over retained deciduous teeth
= crowding
= cleft palate
Posterior cross bite:
Caused by prolonged retention of deciduous molar
= the most common type of posterior cross bite is usually when the buccal cusps of maxillary
posterior teeth occlude lingual to the buccal cusp of opposing mandibular teeth
= in a majority of posterior cross bite cases, both the opposing teeth are out of position
Therefore, the treatment consists of reciprocal movement of both teeth
The cross bite may involve one or more than one tooth and it may be unilateral or bilateral
The cross bite may originate in: dentition, craniofacial skeleton, and temporomandibular
musculature
Types of cross bite:
1- Dental:
This condition involves only the localized tipping of a tooth or teeth and does not affect the size or
shape of the basal bone
Muscular adjustment is always being made to provide an adequate accommodative occlusion
The midline coincides when the jaws are a part and diverge as the teeth come into occlusion
The most important diagnostic single point will be a symmetry of the dentoalveolar arch
2- Muscular:
This group includes all problems in malfunction of the dentofacial musculature
Any persistent alteration in the normal synchrony of the mandibular movement or muscle
contraction may result in distorted growth of facial bones or abnormal position of the teeth
A simple lip sucking habit may give raise to class II dentition and profile. The sucking habit itself
is a complicated neuromuscular reflex involving many muscles of the face, temporomandibular
articulation and tongue
N: B:
= continued sucking may narrow the maxillary dental arch, this contraction of the maxillary arch
give raise to another complicated neuromuscular habit pattern, mandibular retraction

3. 3
Dr. Mohammed Alruby
= the narrowing of the maxillary arch results in tooth interference, and the mandible is then shifted
posteriorly by the muscles to position of better occlusal function which is called compulsive disto-
occlusion (Hotz)
= there is no clear cut differentiation between the dental and muscular type except for treatment,
that for dental, teeth must be moved but in muscular, the adjustment often be gained by occlusal
equilibration, which permits changes in the muscular reflexes governing mandibular positioning
3- Osseous:
= Aberrations in bony growth may give raise to cross bite in two ways:
1- A symmetric growth of maxilla or mandible
2- Lack of agreement in width of maxilla and mandible
= A symmetric growth of the maxilla or mandible may be due to inherited growth pattern or trauma
pattern or trauma that impedes the normal growth on the affected side
= Cross bite due to asymmetric bony growth are most difficult to treat. Lack of harmony between
the maxillary and mandibular widths usually is due to a bilateral contracted maxilla, in such a
cases, the muscles shift the mandible to one side to acquire sufficient occlusal contact for
mastication
= a more severe condition is that in which the mandibular denture occlude completely within the
maxillary arch
N: B: Sassoni classification:
1- Maxillary buccal
2- Maxillary palatal
3- Mandibular buccal
4- Mandibular palatal
Anterior cross bite
Graber: a condition where one or more teeth may be abnormally malposed bucally or lingually
with references to opposing
Or: malocclusion resulting from lingual position of one or more of maxillary anterior teeth in
relationship with mandibular anterior teeth when the teeth are in centric relation occlusion
Etiology:
1- Dental anterior cross bite:
- Traumatic injury to primary dentition causes lingual displacement of permanent tooth buds
- Palatal deflection of permanent dentition
- Prolonged retention of deciduous teeth may deflect the permanent successors in palatal
direction and may result to single tooth cross bite
- Arch length –tooth material discrepancy
- Supernumerary tooth
- Cleft lip repair cases
2- Skeletal anterior cross bite:
- Usually result from retardation of maxillary growth or excessive mandibular growth or
combination of both or posterior position of maxilla or forward position of mandible
- Retarded development of maxilla
- Genetic factors
- Excessive abnormal mandibular growth
- Combination of maxillary defect and mandibular excess
3- Functional cross bite:
- Habitual forward positioning mandible

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Dr. Mohammed Alruby
- Pseudo class III: Sunday bite, this patient able to close the upper and lower incisors edge
to edge together
Delayed treatment of anterior cross bite can lead to serious of complications such as:
1- Loss of arch length
2- Gingival recession of lower incisors
3- Prolonged pocket formation
4- Wear facets on labial surface of maxillary incisors
5- Deleterious effect on masticatory system
Treatment of anterior cross bite:
Cross bite with or without functional shift must be corrected as soon as possible
Treatment of dental cross bite:
Dental cross bite should be treated to prevent change of the skeletal cross bite due to loss of natural
safety valve mechanism provided by the maxillary dentition over mandibular dentition
At primary dentition:
- Removing the occlusal prematurity
- Elimination of causative factors
- Habit breaking appliance
At mixed dentition:
- Is sufficient space is available, maxillary removable appliance is usually the best method to
correct anterior cross bite
At permanent dentition:
Fixed appliance is used to correct anterior cross bite
Appliance used for correction of anterior cross bite:
1- Tongue blade:
= used when cross bite is seen at the time of permanent teeth are appeared in oral cavity
= placed inside the mouth to contact the palatal surface of upper incisors and labial surface of
lower
= is continued for 1-2 hours for about 2 weeks
Draw backs of tongue blade:
- Only effective till the clinical crown not completely erupted in the oral cavity
- Used only if sufficient space is available for the correction
- Required patient cooperation
2- Catalan’ appliance: lower anterior inclined plane:
Introduced by Catalan used in cases where there is fully developed cross bite of single tooth
Constructed at 45-degree angulation on the lower anterior by acrylic or cast metal
When the maxillary teeth in cross bite touches the inclined plane, a forward directed force moves
the tooth to a more labial position, more steep angle and more force generated
Disadvantages of appliance:
1- Difficulty in speech and chewing
2- Required patient cooperation
3- Acts as anterior bite plane so it can lead to supra-eruption of posterior teeth ----- anterior
open bite
4- Cannot used in cases of mal-aligned lower incisors
5- The appliance may become lose, there is chances of accidental swallowing
3- Double Cantilever spring: Z spring:

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Dr. Mohammed Alruby
Used in anterior cross bite either one or two teeth are should an adequate space for correction
This method effective only where there is enough space for aligning the teeth
4- Screws appliances:
Micro: used to correct individual tooth
Mini: capable for moving two teeth
Medium: used to correct segment cross bite
3D: used to correct posterior as well as anterior cross bite
5- Face mask:
Used to correct skeletal anterior cross bite, some cases need some transverse expansion
6- Chin cup appliance:
Used in cases of mandibular excess, the appliance rotates the mandible backward and downward
7- FR III appliance:
Used for correction of skeletal class III malocclusion
N: B:
Limitation of removable appliances:
1- Bodily movement if speed need to created
2- Torqueing the incisor root: if incisors root is positioned palatally, simple tipping of the
tooth will procline the tooth excessively, that lead to poor esthetic and poor gingival contour
3- Rotation of the teeth: due to single point of contact and result tipping movement
N: B:
Factors should be considered before selection of treatment approach of anterior cross bite
1- Adequate space for correction in arch
2- Class I malocclusion
3- Sufficient over bite to hold the tooth in position following correction
4- An apical position of the tooth in cross bite that is the same as it should be in normal
occlusion
N: B:
Before and after treatment casts were photocopied side by side with a coin, used as dimensional
standard for image size adjustment of the copy machine: the coin is measured for accuracy
The selected points references are measured as:
1- Inner lingual points on the gingival margin of the 1st
upper molar wear taken for inter-
molar width
2- Inner lingual points on the gingival margin of canine were taken for inter-canine width
3- Points on mesial aspect of permanent 1st
molar on the distal aspect of canine and central
incisors taken for arch parameter
4- Points on mesial aspect of 1st
molar and mesial aspect of central incisors were taken for
arch length; measurement are carried out with digital caliper
N: B:
Rickets et al1982, each increase of 0.25mm in the perimeter by 1mm of inter-molar distance
Adkin et al 1990, each 1mm increase in inter-premolar distance added 0.7mm arch perimeter