Etiology of malocclusion
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Etiology of malocclusion
- 2. ContentsContents Introduction Definition of malocclusion Types of malocclusion Classification of etiologies of malocclusion Brief description on various factors Conclusion
- 3. IntroductionIntroduction Comprehensive orthodontic management involves identification of possible etiological factors and an attempt to eliminate the same. Although it may not be possible, it is nevertheless of value in preventive and interceptive procedures. Rather than having specific “CAUSES” as do some diseases, malocclusions are usually clinically significant variations from normal range of growth and morphology. Etiologic factors contribute to the variance, more often than they simply cause it
- 4. DefinitionDefinition The arrangement of teeth in a dentition or their relation in the jaws to each other, which is not according to the accepted morphologic configuration of human maxillo- dentofacial complex
- 5. Malocclusions may involve four tissue systems Teeth Bones Muscles Nerves Malocclusion GroupsMalocclusion Groups
- 6. Dental dysplasias Skeleto dental dysplasias Skeletal dysplasias Another way to classify malocclusion isAnother way to classify malocclusion is to divide them into three groupsto divide them into three groups
- 7. Classification Of Etiologic FactorsClassification Of Etiologic Factors According to Mc coy Indirect / Pre disposing causes Direct / Determining causes
- 8. Indirect / Pre disposing causes includeIndirect / Pre disposing causes include Hereditary Congenital defects Pre natal abnormalities Acute / chronic infections and deficiency diseases Metabolic disturbances Endocrine imbalance Unknown causes.
- 9. Direct / Determining causes includeDirect / Determining causes include Missing teeth Supernumerary teeth Transposed teeth Malposed teeth Abnormal labial frenum Intrauterine pressure Sleeping habits Posture
- 10. Pressure Abnormal muscular habits Malfunctioning muscles Premature shedding of deciduous teeth Tardy eruption of permanent teeth Prolonged retention of deciduous teeth Loss of permanent teeth Improper dental restorations
- 11. ACCORDING TO MOYERSACCORDING TO MOYERS Heredity Neuro muscular system Bone Teeth Soft parts (other than nerve and muscle) Developmental defects of unknown origin Trauma Prenatal trauma and birth injuries. Post natal trauma.
- 12. Physical agents Pre natal Post natal Habits Thumb and finger sucking, tongue sucking, lip biting etc Disease Systemic diseases Endocrine diseases Local diseases Malnutrition
- 13. According to SalzmannAccording to Salzmann Salzmann’s diagrammatic representation of the etiologic factors in malocclusion embodies prenatal and post natal factors. It clearly shows the genetic, differentiative and congenital factors that make up the prenatal elements of causation, which can influence and one or all of the postnatal components- developmental, functional, environmental.
- 14. According to Graber General Factors Heredity (The inherited pattern) Congenital Defects Cleft palate Torticollis Cleidocranial dysostosis Cerebral palsy Syphilis etc.
- 15. Environment Pre natal Trauma Maternal diet Maternal metabolism German measles etc. Post natal birth injury Cerebral palsy TMJ injury etc.
- 16. Pre disposing metabolic climate and disease endocrine imbalance metabolic disturbances infectious diseases Dietary problems nutritional deficiency
- 17. Abnormal pressure habits and functional aberrations Abnormal suckling Forward mandibular posture Non physiologic nursing Excessive buccal pressures
- 18. Thumb and finger sucking Tongue thrust and tongue sucking Lip and nail biting Abnormal swallowing habits (improper deglutition) Speech defects
- 19. Respiratory abnormalities (mouth breathing) Tonsils and adenoids (compensatory tongue position) Psychogenic tics and Bruxism Posture Trauma and Accidents
- 20. Local factors Anomalies of number Supernumerary teeth Missing teeth Congenital absence or loss due to accidents, caries etc Anomalies of tooth size Anomalies of tooth shape Abnormal labial frenum, mucosal barriers
- 21. Premature loss Prolonged retention Delayed eruption of permanent teeth Abnormal eruptive path Ankylosis Dental caries Improper dental restorations
- 22. ACCORDING TO PROFFITACCORDING TO PROFFIT Specific causes Disturbances in embryologic development (teratogens) Skeletal growth disturbances Intrauterine molding Birth trauma to mandible Childhood fractures or the jaw Muscle dysfunction
- 23. Acromegaly and hemi mandibular hyper trophy Disturbances of dental development Congenitally missing teeth Malformed and supernumerary teeth Interferance with eruption Ectopic eruption Early loss of primary teeth Traumatic displacement of teeth
- 24. Genetic influences Environmental influences Equilibrium theory and development of dental occlusion Functional infuence on dento facial development.
- 25. General factors Heredity A child may have facial features that markedly resemble those of his father or mother, or the net result may be a combination of features from each parent. It is also to be noted that, a single gene is not responsible for a particular malocclusion and it may be due to the combined action of different types of Genes Heredity could be considered significant in determining the following characteristics
- 26. Tooth size Width and length of arch Height of palate Crowding and spacing of teeth Overjet Position and conformation of perioral musculature to tongue size and shape Soft tissue peculiarities Facial asymmetries Macorgnathia and micrognathia Macrodontia an microdontia
- 27. Oligodontia and anodontia Tooth shape variations (peg laterals, Carabellis cusps, mamelons etc) Cleft palate and hare lip Diastemas Deep bite Rotation of teeth Mandibular retrusion Mandibular prognathism
- 28. Congenital defects Cleft lip and palate Congenital defects life cleft lip and palate separately or in combination are among the most frequent congenital deformities of mankind. It is not often possible for the dentist to compensate for residual post surgical abnormalities. In a unilateral cleft, the teeth or one side are usually in lingual cross bite with the opposing lower teeth. Many times the premaxilla is displaced anteriorly, or, because of the tightly repaired lip, the whole pre maxillary structure is forced lingually. The maxillary incisors in this type are badly malposed with bizarre axial inclinations. In the area of cleft, teeth are often jumbled. Maxillary lateral incisors may be missing, atypical in shape or ‘twinned’
- 29. Cerebral palsy Paralysis or lack of muscular co-ordination due to an intra cranial lesion Complete lack of motor control resulting in abnormal muscular function in masticaction, deglutition, speech and respiration. Abnormal pressure habits lead to malocclusion
- 30. Torticollis Shortening of the sternocleido mastoid muscle causing profound changes in the bony morphology of the cranium and the face Characterised by “wry neck” Bizarre facial asymmetries and uncorrectable malocclusions if not treated early
- 31. Cleidocranial dysostosis Maxillary retrusion and possible mandibular protrusion Retained deciduous teeth Retarded eruption of permanent teeth Short and thin permanent teeth roots Super numerary teeth
- 32. Congenital Syphilis Abnormally shaped teeth
- 34. Pre natal Teratogens: Chemical and other agents capable of producing embryologic defects if given at critical time are called teratogens Aminopterin Aspirin Cigarette smoke (hypoxia) Cytomegalovirus Anencephaly Cleft lip and palate Cleft lip and palate Microcephaly, hydrocephaly, microphthalmia Dilantin Ethyl alcohol 6-Mercaptopurine 13-cis Rentinoic acid (Accutane) Cleft lip and palate Central mid-face deficiency Cleft Palate Retinoic acid syndrome: malformations virtually same as hemifacial microsomia, Treacher Collins syndrome Rubella virus Thalidomide Microphthalmia, cataracts, deafness Malformations similar to hemifacial microsomia, Treacher Collins syndrome Toxoplasma Microcephaly, hydrocephaly, microphthalmia X-radiation Valium Vitamin D excess Microcephaly Cleft and palate Premature suture closure
- 35. Intrauterine moldingIntrauterine molding Pressure against the developing face prenatally can lead to distortion of rapidly growing areas. Eg: an arm is pressed across the face in utero resulting in severe maxillary deficiency. Other factors that may affect are trauma, maternal diet, maternal metabolism and German measles
- 36. Birth trauma In some difficult births use of forceps to the head to assist in delivary might damage either or both TMJ. Heavy pressure in the area of TMJ could cause internal haemorrhage, loss of tissue and a subsequent under development of the mandible Childhood fractures: Falls that produce condylar fractures may cause marked facial asymmetries Extensive scar tissue, from a burn may also produce malocclusions Post natal
- 37. Some specific endocrinologic diseases may be potent makers of malocclusion. Diseases with a paralytic effect, such as poleomyelitis are capable of producing malocclusions. Disease with muscle malfunction, such as muscular dystrophy and cerebral palsy also have deforming effects on dental arch Pre disposing metabolic climate and diseases
- 38. HypothyroidismHypothyroidism Abnormal resorption patterns Delayed eruption pattern Gingival disturbances Retained deciduous teeth
- 39. AcromegalyAcromegaly Which is caused by an anterior pituitary tumor that secrete excess amounts of GH, excessive growth of mandible may occur, creating a skeletal class III malocclusion in adult life. Also multiple root resorption may be found.
- 40. Nutritional deficiencyNutritional deficiency Disturbances such as rickets, scurvy and berry-berry can produce severe malocclusions. Main problem is upsetting of the dental developmental time tables. The resultant premature loss, prolonged retention, poor tissue health and abnormal eruptive paths lead to malocclusion
- 41. Non nutritive sucking habits, Includes all sucking habits Thumb sucking Finger sucking Pacifiers etc. Abnormal pressure habits andAbnormal pressure habits and functional aberrationsfunctional aberrations
- 42. Dento facial changes associated with prolonged non nutritive sucking habits are Increased proclination of upper incisors Increased maxillary arch length Increased clinical crown length of max incisiors Increased atypical root resorption in primary central incisors
- 43. Increased retroclination of mandibular incisors Increased overjet Decreased over bite Increased unilateral and bilateral class II occlusion Increased lip incompetence Tongue thrust Speech defects, especially lisping
- 44. Lip biting Involves the lower lip which is turned inwards and pressure is exerted on the lingual surfaces of maxillary anteriors Proclined upper anteriors and retroclined lower anteriors Hyper trophic and redundant lower lip Cracking of lips Lip habitsLip habits
- 45. Nail bitingNail biting Does not produce gross malocclusion. But minor local tooth irregularities like Rotation Wear of incisal edge Minor crowding.
- 46. Tongue thrustTongue thrust Defined as a condition in which the tongue makes contact with any teeth anterior to the molars during swallowing It has to be remembered at this time that there is a controversy regarding Tongue thrust as an etiologic factor of anterior open bite. According to Graber and Moyers, Tongue thrust definitely leads to anterior open bite. Proffit contradicts this fully and according to him, it is an already existing anterior open bite that leads to Tongue thrusting habit Proclination of anterior teeth Anterior open bite Bimaxillary protrusion Posterior open bite in case of lateral Tongue thrust Posterior cross bite
- 47. Mouth breathingMouth breathing Mouth breathing can result in altered jaw and tongue posture which could alter the oro-facial equilibrium there by leading to malocclusion Long and narrow face Short and flaccid upper lip. Contracted upper arch with possibility of posterior cross bite Increased overjet as a result of flaring of the incisors. Dryness of the mouth predisposes to caries. Anterior open bite
- 48. BruxismBruxism Grinding of teeth for non functional purposes Occlusal wear facets Fractures of teeth and restorations Mobility of teeth. Tenderness and hypertrophy of masticatory muscles TMJ pain
- 49. Tongue size as well as function is an important consideration. Aglossia can result in narrowing of the upper dental arch with severely malpositioned teeth and crowding. Where as Macroglossia can lead to widening of dental arches, spacing and open bite.
- 50. Anomalies in number of teeth Super numerary teeth Missing teeth Local factorsLocal factors
- 51. Super numerary teethSuper numerary teeth The presence of extra tooth obviously has great potential to disrupt normal occlusal development. Early intervention and to remove it is usually required to obtain reasonable alignment and occlusal relationships. Most common-mesiodens. Also lateral incisors, extra premolars, fourth molars multiple super numerary teeth are found in cleidocranial dysplasia and other congenital deformities like cleft lip and cleft palate
- 53. Quite frequently it has been noted that, one maxillary lateral incisor will be of normal size and configuration while the other is small. Anomalies of size are relatively frequent in the mandibular pre molar area Anomalies of tooth sizeAnomalies of tooth size
- 55. Abnormal labial FrenumAbnormal labial Frenum If the frenum is thick, it prevents the closure of diastema (which is normal during mixed dentition prior to the eruption of canines) In these cases a frenectomy is indicated
- 56. Premature loss of deciduous teethPremature loss of deciduous teeth The early loss of permanent teeth should be considered as a “Malocclusion Maker” Deciduous teeth not only serve as organs of mastication, but as space savers for permanent teeth. Loss of a deciduous 2nd molar will lead to mesial drift of the 1st permanent molar and blocking of erupting 2nd premolars. In this cases appropriate space maintainers should be given
- 59. This is usually a secondary manifestation of a primary disturbance Severe crowding Super numerary tooth Retained deciduous tooth / root fragment Bony barrier Dentigerous cysts Another form of abnormal eruption is referred as ectopic eruption. Most common form is a permanent tooth erupting through the alveolar process causing resorption on a contiguous deciduous tooth or permanent teeth , rather than its predecessor. Eg; maxillary first molar, causing resorption of maxillary deciduous second molar. Abnormal eruptive pathAbnormal eruptive path
- 61. Dental cariesDental caries Dental caries should be considered as one of the local factors causing mal occlusion. Caries which leads to premature loss of a deciduous or permanent tooth may cause drifting, axial inclination, over eruption, bone loss etc.
- 62. Improper dental restorationsImproper dental restorations Silver mercury alloy restorations have a tendency to “flow” under pressure. Large proximal restorations change gradually under the assault of occlusal forces, and arch length is increased. This may result in the creation of broken contacts, rotations, crossbite conditions and functional prematurities. Lack of anatomic detail in restoration of cuspal areas of a tooth can permit elongation of opposing tooth. Loose contacts also leads to food packing, teeth tend to move apart and also leads to bone loss
- 63. Knowledge about the various etiological factors of malocclusion will help us to plan the various interceptive and preventive orthodontic procedures. It also helps in eliminating the etiological factor if it is of a environmental type. The recognition and reporting of a malocclusion or a condition that could lead to a malocclusion is the most important service that a dentist can provide to his patients. Malocclusion has an important impact on the function and esthetics of the entire dentition. In fact, malocclusion has a detrimental effect on the self esteem of many children, adolescent and adult. If a malocclusion is not recognized by either the dentist or the patient, it cannot be assessed and treated A sound knowledge about the various factors that lead to malocclusion, will definitely help is to render excellent treatment for our patients with good retention and stability Conclusion