Cross Bite

1. 1 Cross bite Cross bite Prepared by Dr. Prepared by Dr. Mohammed Alruby Mohammed Alruby يقشي لاو لضي لاف الله يده عبتا نم يقشي لاو لضي لاف الله يده عبتا نم C Cross ross bite in bite in O Orthodontics rthodontics Dr. Dr. Mohammed Alruby Mohammed Alruby

2. 2 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 C Cross ross bite in bite in O Orthodontics rthodontics Dr. Dr. Mohammed Alruby Mohammed Alruby

3. 3 = 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 C Cross ross bite in bite in O Orthodontics rthodontics Dr. Dr. Mohammed Alruby Mohammed Alruby

4. 4 -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: C Cross ross bite in bite in O Orthodontics rthodontics Dr. Dr. Mohammed Alruby Mohammed Alruby

5. 5 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 C Cross ross bite in bite in O Orthodontics rthodontics Dr. Dr. Mohammed Alruby Mohammed Alruby