Local Factors_Etiology of Malocclusion - Dr. Nabil Al-Zubair


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Local Factors_Etiology of Malocclusion - Dr. Nabil Al-Zubair

  2. 2. ETIOLOGY OF MALOCCLUSION Heredity Malocclusion Heredity FACTORSAcquired Malocclusion Environment Effects
  3. 3. Malocclusion is associated with one or more of the followingMalposition Malrelationship of Malocclusion of teeth dental arches Single teeth Antero-posterior Rotation Class II Tipping Class III Displacement Vertical infra-occlusion Openbite Supra-occlusion Deepbite Transposition T Transverse Space discrepancy Crossbite Crowding Scissorbite Spacing
  4. 4. Etiology of malocclusion.Malocclusion can occur as a result of different factorswhich are inherited or acquired1) Skeletal factors. Etiology of malocclusion.2) Soft tissue factors.3) Dental and local factors. Skeletal factors4) Combinations. Soft tissue factors Malocclusion Dental and local factors
  5. 5. Etiology of malocclusion• Skeletal Factors;1) Anteroposterior. Skeletal Factors2) Vertical. Skeletal factors3) Transverse.4) Combinations Anteroposterior Class II Class III Vertical Low angle Malocclusion High angle Transverse Crossbite Scissor bite
  6. 6. Etiology of malocclusionSoft tissue factor.1) Lips.2) Tongue. Soft tissue factor3) Combinations. Lips Morphology Function Malocclusion Tongue Position Size
  7. 7. Etiology of malocclusion – soft tissue factors
  8. 8. Dental & local factors
  9. 9. Etiology of malocclusionDental & local factors
  10. 10. Dental and local factors
  11. 11. Dental and local factors
  12. 12. LOCAL FACTORS IN THE AETIOLOGY OF MALOCCLUSIONI-Anomalies in Number of Teeth:- Developmental Missing teeth III- Anomalies in Position of Teeth:- Supernumerary (Extra-teeth) - Ectopic- The early loss of deciduous teeth - Impaction- Retained deciduous teeth - Transposition- Loss of permanent teeth IV-_ Habits: - Finger suckingII- Anomalies in Size & Form of - Tongue thrustingTeeth:Size:- Microdontia- Macrodontia V- Others :Form - fraenum- Peg lateral incisors - Trauma- Dilaceration - Pathology- Twin teeth (gemination/fusion) - Bad restorations- Dens evagenatus
  13. 13. I-Anomalies in Number of Teeth: - Developmental Missing teeth - Supernumerary (Extra-teeth)- The early loss of deciduous teeth - Retained deciduous teeth - Loss of permanent teeth
  14. 14. - Variations in tooth number• absence of one or more • Supernumerary teeth of teethHypodontia Hyperdontia
  15. 15. Hypodontia A common condition characterized bydevelopmental absence of one or more primary orsecondary teeth excluding the third molars Aetilogy: Multifactorial with both It results from disturbance during initial inherited & environmental factors stages of tooth formation ,initiation and contributing to the condition proliferation
  16. 16. Classified according to its severity as:The most commonlymissing teeth are: • 1-2 missing teeth Mild • 3-5missing teeth moderate • ≥ 6missing teeth Severe
  17. 17. Congenitally missing teethMissing of teeth can be:-a. Complete (Anodontia).b. Many teeth (oligodontia). Both are rare & are associated with ectodermal dysplasia (systemic abnormality).C. Few teeth (hypodontia) is more common.
  18. 18. - Oral anomalies associated with hypodontia Over-eruptionDelayed dental Severely rotated of opposing development premolars teethTransposition Taurodontism Alveolar atrophy
  19. 19. Medical conditions associated with hypodontiaEctodermal dysplasia: • Hypodontia, Hypohidrosis (failure to sweat leading heat intolerance & dry erythematous skin, Hypotrichosis (sparse hair), nail defects & XerostomiaDown syndromeCleft lip & palateHemifacial microsommia
  20. 20. Missing of primary teeth lead to missing of its permanent successor • Bilateral congenital absence is more frequent than unilateral. • More frequent in permanent dentition than in deciduous dentition.• The missing tooth always the most distal tooth of each segment* Incisor segment >>> lateral incisor.* Premolar segment >>> secondpremolar.* Molars segment >>> third molar.
  21. 21. Supernumerary teeth
  22. 22. Most commonly Occur 10 times found in the Males are twiceDefined as teeth more frequently anterior as commonlyin excess of the in the maxilla maxillary region affected than normal series than the followed by the females mandible mandibular premolar region Supernumerary teeth
  23. 23. Prevalence: • 0.3 – 0.8% (primary dentition) • 0.1 – 3.8% (permanent dentition)• A Supernumerary tooth in the primary dentition is likely to be followed by a Supernumerary in the permanent dentition
  24. 24. Medical conditions associated with SupernumeraryCleidocranial dysplasia: • Aplasia or agenesis of the clavicles, Class III malocclusion, multiple supernummerariesCleft lip ±palateGardner’s syndrome
  25. 25. • Multiple numeraries can be seen in cleidocranial Dysplasia.
  26. 26. Types of supernumerary teeth
  27. 27. Types: Conical, tuberculate, supplemental & odontomesAn erupted mesiodens causing separation ofthe upper central incisors
  28. 28. An upper anterior occlusal radiograph also showing the presence of a supplemental B supernumeraryA complex odontome preventingeruption of 3.
  29. 29. Diagnosis:1) Clinical examination: displacementof erupted incisors or midline diastema.2) A "vertex occlusal" RADIOGRAPH takenthrough the long axis of the incisors gives anindication as to whether supernumeraries arepalatally or labially placed.
  30. 30. Supernumerary Complications Failure of Midline Crowding eruption diastemaDisplacement or Root resorption Prevention ofrotation of of neighboring tooth movementadjacent teeth teeth
  31. 31. supernumerary preventing eruption of 1.
  32. 32. The early loss of DECIDUOUS teeth
  33. 33. • Causes of Premature Lossi. Extensive carious lesion.ii. Accidents "trauma" lead to loss of thetooth vitality and abscess formation wherebytheir removal becomes a necessity.iii. Child has much fever that decrease bodyresistance with multiple abscess formationand increase the possibility of premature loss.iv. Accelerate root resorption of tooth.v. Premature extraction in serial extractiontherapy.vi. Diseases such as Rickets.
  34. 34. The effect on the developing dentitiondepends on: - the amount of the crowding , - the age of the patient & - the tooth lost
  35. 35. The effects of early loss of deciduous teeth on the developing dentition - the tooth lostDeciduous - Minimal effect – some space loss ifincisors crowdingDeciduous canines - Centerline shift if unilateral loss with some relief of incisor crowding - Space loss for permanent canines Premature lost of primary canine 1.5 years later of the same patient
  36. 36. Deciduous first - Small Centerline shift if crowdingmolars with minimal relief of labial segment crowding - Mesial molar movement with space loss
  37. 37. Deciduous second - Often no effect on centerline ormolars incisor crowding - Mesial drift of molars with space loss for second premolars
  38. 38. The effects of early loss of deciduous teeth on the developing dentitionTooth lost Effect on permanent dentition Action requiredDeciduous incisors - Minimal effect – some space loss - None if crowdingDeciduous canines - Centerline shift if unilateral loss - If crowding, consider with some relief of incisor balancing extraction to crowding protect the centerline - Space loss for permanent caninesDeciduous first - Small Centerline shift if crowding - Consider balancingmolars with minimal relief of labial extraction or space segment crowding maintenance - Mesial molar movement with space lossDeciduous second - Often no effect on centerline or - Space maintenance except inmolars incisor crowding spaced arches - Mesial drift of molars with space loss for second premolars
  39. 39. Retained deciduous teeth
  40. 40. Loss of permanent teethThe most common permanent tooth to beextracted early is:- the first permanent molar- A permanent maxillary central incisors
  41. 41. The early loss of first permanent molar: Extraction before the age of 8 years results in: Significant distal migration of the second premolar which may then become impacted distal migration
  42. 42. A permanent maxillary central incisors:Occasionally lost due to traumaIf there is crowding, space loss can occur (complicate later tooth replacement)
  43. 43. Early loss of primary teeth Early loss of teeth will lead to dental arch collapse, but it’s not the only cause for crowding & Malalignment. Collapse will be due to :1. Mesial drifting of posterior teeth.2. Distal drifting of incisors a/f canine & 1st decidious molar loss.
  44. 44. II- Anomalies in Size & Form of Teeth: Size: - Microdontia - Macrodontia Form - Peg lateral incisors - Dilaceration - Twin teeth (gemination/fusion) - Dens evagenatus
  45. 45. Anomalies in Size of teeth Microdontia Macrodontia - genetically determined - generalised or localisedTeeth smaller than normal Teeth larger than normalAssociated with hypodontia Associated supernumerary teethPredispose to spacing Predispose to crowdingThe microdontia of maxillary lateralincisor is associated with impaction ofthe permanent maxillary canine
  46. 46. Anomalies of tooth form
  47. 47. Abnormalities in tooth size and shape will be dueto disturbances during morpho & histodifferentiation stages of its development.Most common abnormality is seen in lateralincisors & 2nd premolars .
  48. 48. - Peg lateral incisors
  49. 49. - Twin teeth (gemination/fusion)Fusion:-is teeth with separate pulp chambersjoined at dentin .Gemination:-is teeth with common pulp chamber.They are almost similar ,so you shouldcount no of teeth.
  50. 50. Dilaceration Formation of tooth at an angle manifested as a bent root due to displacement of tooth germClinical Applications Delayed Eruptions Difficult Tooth Movements Interference with Adjacent Tooth Roots
  51. 51. - Dens evagenatus
  52. 52. III- Anomalies in Position of Teeth: - Ectopic - Impaction - Transposition
  53. 53. INFRAOCCLUSION - Variations in tooth position- TOOTH IMPACTION - TRANSPOSITION:
  54. 54. Ectopic eruption It occurs as a result of a permanent tooth bud malposition. Ex:-1. Mesial drifting of maxillary first molar.2. Mandibular 2nd premolar erupt distally.3. Impacted Maxillary canines
  55. 55. INFRAOCCLUSION- occurs as a consequence of failure of eruption of a tooth due to ankylosis (the anatomical fusion of cementum & alveolar bone)- Ankylosed tooth become submerges relative to its nieghbours- The first & second deciduous molars most commonly affected- Complications: Tipping, inhibition of vertical development of adjacent teeth Deviation of the dental centerline to the affected side(the results of stretching of the transseptal periodontal fibersthat interconnect the teeth
  56. 56. Consequences of infraocclusion of a deciduous molar Tooth ConsequencesInfra-occluded deciduous Delay exfoliationmolar Progressive submergence with failure of alveolar development Difficult extraction often requiring surgery !!!!!Permanent successor Delayed & abnormal eruption Disturbed root development Centreline shiftDeveloping occlusion Tipping of adjacent teeth Localised posterior open bite Higher frequency of canine impaction, hypodontia & ectopic first permanent molar eruption
  57. 57. - Abnormalities in the position of teeth can also arise as a result of - TOOTH IMPACTION- Excluding third molars, commonly impacted teeth include:  Maxillary canines  Maxillary central incisors  First permanent molars
  58. 58. - TRANSPOSITION:- An abnormality where the position of teeth is interchanged- The most transposed teeth: The maxillary canines & first premolars
  59. 59. - Primary failure of eruption:- The most affected teeth: The first & second permanent molar
  60. 60. Traumatic displacement of teeth Dental trauma can lead to development of malocclusion in 3 ways:1. Damage to permanent tooth buds from injury to primary teeth.2. Drift of permanent teeth a/f premature loss of primary teeth.3. Direct injury to permanent teeth.
  61. 61. Trauma to primary tooth lead to 2 results:- Trauma to the permanent tooth crown &disturbances in enamel formation &defect ontooth .The crown may be displaced relative to theroot causing less root formation & short root ordilacerations
  62. 62. Abnormal frenum attatchment
  63. 63. Labial FrenumIts ORIGIN in the inner surface of the upper lip.However, its insertion changed by age as follow • In infancy: Inserted in the region of the incisive papillae. • In early childhood: Inserted at the gingival crest at the midline. • Increasing age: The teeth erupt and the alveolar process grows downwards and the frenum is found to be further away apically from the gingival crest
  64. 64. Normal Labial Frenum thin knife like edge formed of double layer of fibrous tissue covered with mucous membrane. Abnormal Labial Frenumthickened fibrous, fan shape in appearanceand taping downward to the alveolar cresteven after eruption of the permanent canines.
  65. 65. Normal Labial Frenum Abnormal Labial FrenumHistologically the frenum fibers do not the fibers penetrating the V- penetrate the shaped inter-maxillary suture premaxillary suture attaching at different depth to the connective tissues and periosteum.
  66. 66. Abnormal Labial Frenum
  67. 67. Diagnosis1. By clinical observation alone.2. By "Blanching Test": pull of upperlip upward and outwardlead to blanching of the interdentalpapillae obviously observedwith the abnormal heavy fibrousfrenum.3. Periapical radiograph:V-notch of the interdental bone betweencentral incisors
  68. 68. Abnormal frenal attatchmentLingual frenum Lower labial frenum
  69. 69. Abnormal Habits . Thumb and Finger Sucking :Nasal Breathing Mouth BreathingNormal Swallow Abnormal Tongue Thrust Swallow DISTURBANCE OF NORMAL FUNCTION