Growth rotations /certified fixed orthodontic courses by Indian dental academy


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Growth rotations /certified fixed orthodontic courses by Indian dental academy

  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. Contents • • • • • • Introduction Terminologies Concepts of Mandibular growth Rotations Concepts of Maxillary growth Rotations Prediction of Mand growth Rotation Interaction b/n jaw Rotation &Tooth eruption • Clinical implications • conclusion
  4. 4. Introduction Since Cephalometrics introduced in 1930, originally used to reveal The Anatomy of head Longitudinal study is possible, soon employed to test various Concepts of mechanisms of postnatal growth of head
  5. 5. Introduction Longitudinal Cephalometrics analysis of profile radiographs shows that facial shape is remarkably constant during growth
  6. 6. • Until the use of metallic implants the extent to which the mand & maxilla rotate during growth was not appreciated • The Rotation tends to be masked by surface remodeling
  7. 7. • Lande in 1952 observed that the lower border of the mand becomes less steeply inclined • The phrase “GROWTH ROTATION” was introduced in 1955 by Bjork • With the use of metallic implants, He could infer the sites & amt of growth & resorption • Superimposing 2 consecutive tracings showed that the older Mand rotated
  8. 8.
  9. 9. Forward Rotation (Bjork) Counterclockwise Rotation (shudy) Posterior growth is greater than Anterior Backward ward Rotation (Bjork) Clockwise Rotation (shudy) Anterior growth is greater than posterior
  10. 10.
  11. 11. TERMINOLOGIES • 1965-Schudy introduced clockwise and counterclockwise rotation. • 1969-Bjork discussed different directions of rotation of the mandibular implant line and the relation of these to mandibular form.
  12. 12. • 1970-Odegard described rotation as the change in the orientation that can occur between implant line and lower border of the mandible. • 1977-Lavergne and Gasson described the terms Positional and Morphogenetic rotations. • 1983-Bjork and Skieller gave the termsTotal rotation. Matrix rotation. Intramatrix rotation
  13. 13. • 1985-Dibbets introduced the term Counterbalancing rotation. • 1988-Solow,Houston True rotation. Apparent rotation. Angular remodeling of the lower border. • Proffit- used the terms Internal rotation. Total rotation . External rotation.
  14. 14.
  15. 15.
  16. 16. TOTAL ROTATION / TRUE ROTATION / INTERNAL ROTATION • Is the rotation of the mandibular corpus and is measured as a change in inclination of the implant line, in the mandibular corpus relative to the anterior cranial base.
  17. 17. If the implant line rotates forwards, the total rotation is designated as Negative The Total Forward Rotation is indicated by converging sella – nasion lines
  18. 18.
  19. 19. MATRIX ROTATION / APPARENT ROTATION / TOTAL ROTATION • Rotation of the soft tissue matrix of the mandible relative to the Anterior cranial base • The soft tissue matrix is defined by the Tangential mandibular line(ML1) • Is designated as Negative,when Tangential mandibular line rotates forwards
  20. 20. The matrix rotates forwards & backwards in same individual during the growth period – PENDULUM MOVEMENT Center of Rotation – Condyles
  21. 21.
  22. 22. INTRAMATRIX ROTATION/ ANGULAR REMODELING/ EXTERNAL ROTATION Defined as the change in inclination of an implant line in the mandibular corpus relative to the tangential mandibular line Intramatrix Rotation is an expression of remodeling at the lower border of the mandible
  23. 23.
  24. 24. • Forward Rotation of the corpus relative to the tangential mand line is recorded as Negative • Center of rotation is somewhere in the corpus • Depends on rotation of corpus of mand & rotation of maxilla & occlusion of teeth
  25. 25. ----- + +++ ++
  26. 26. + ----- +++ ++ -
  27. 27.
  28. 28. • The diff b/n Total Rotation & Matrix Rotation is intramatrix Rotation
  29. 29. • According to Bjork & Skieller’ “Intramatrix” concept First,the mandible “wiggles” with in the matrix Second,this “wiggling” is associated predominantly with the corpus, but is caused by the growing condyle Third, Rotation results from or compensates for, a genetically determined program
  30. 30. BJORK SOLOW, HOUSTON PROFFIT Rotation of Mandibular core relative to cranial base implants Total Rotation True Rotation Internal Rotation Rotation of Mandibular plane relative to cranial base Matrix Rotation Apparent Rotation Total Rotation External Rotation of Mandibular Intramatrix Angular Remodeling Rotation plane relative to core of Rotation of lower Mandible border
  31. 31. • The Total Rotation = Matrix Rotation + IntraMatrix Rotation
  32. 32. • The center of Total Rotation depends on other two centers of Rotation • The pattern of vertical facial development is strongly related to the Rotation of both the jaws • For an average individual with normal vertical facial height • Total Rotation = – 15 Matrix Rotation = –4 IntraMatrix Rotation = –11
  33. 33. “Positional” & “Morphogenetic” Rotation Given by Lavergne & Gasson Positional Rotation deals with the position of the mandible with in the head
  34. 34. Morphogenetic Rotation • concerns the shape of the mandible itself • super imposing the two tracings on a line through condylion & pogonion •The angle b/n two implant lines is determined & this corresponds to the degree of morphogenetic Rotation • similer to Bjork’s Intramatrix Rotation but not identical
  35. 35. Bjork & Skieller consider the key factor of Intramatrix rotation to be found in a rotation of the mandibular corpus inside its matrix Lavergne & GassonFound the effective mechanism in Ramus, its forward or backward growth,therby shortening or elongating the effective length of the mandible
  36. 36. • Maxillary – Mandibular sagittal discrepancy is minimized by opening or closing the gonial angle
  37. 37. “It is a compensating mechanism which is capable of enlarging or reducing mandibular length as measured along the condylion-pogonion diagonal”
  38. 38. J.M.H.Dibbets • Re-examination of the concept of “Intramatrix Rotation" as defined by Bjork & Skieller & also explored by Lavergne & Gasson • Three diff interpretations of Intramatrix concept are
  39. 39. • First option - Bjork & Skieller define the “Intramatrix Rotation” as The Rotation of the mandibular corpus relative to the lower border is a result of genetically determined condylar growth both in magnitude & in direction
  40. 40. Bjork approach Superimposing two tracings of the same mandible registered upon natural reference structures shows Rotation
  41. 41. Divergence of implant lines indicates Intramatrix rotation Superimposed on implant markers Indicates extensive remodeling
  42. 42. • The condyle grows on a circular arc with radius from center at chin to the condyle. • When two tracings are superimposed on their contours, they are identical in size & shape. • The external configuration of mandible need not change in order to allow ‘Intramatrix rotation’ • Any Depositional or Resorptive activity maintains original contours
  43. 43. Painting rotated with in frame but external configuration & dimensions do not change
  44. 44. • The bony element can rotate with in its periosteal frame • Every deflection of condylar growth creates the possibility of compensatory remodeling, mostly resorption of the lower border resulting in Intramatrix rotation • Intramatrix Rotation neutralizes the condylar growth.
  45. 45. Second option-Hunterian concept or Morphogenetic rotation Posterior ramal deposition & Ant resorption The direction of condylar growth follows pattern that enlarges the Mandible maximally
  46. 46. Third option - Dibbets • Two divergent patterns of mandibular growth • 1)Circular growth pattern of condyle, resulting in Intramatrix Rotation without any enlargement of mandible • 2)linear growth pattern of the condyle, characterized by the absence of intramatrix rotation but evidencing mandibular enlargement. suggested mechanism Counterbalancing Rotation
  47. 47. Counterbalancing Rotation “Counterbalancing Rotation pertains to circular condylar growth, accompanied by selective coordinated remodeling, which does not contribute to the incremental growth of the mandible” *The actual path of the mand condyle is accompanied by selective remodeling & thus neutralizes the growth * Results in selective enlargement of the mandible, apart & distinct from mechanisms that have been described in the literature
  48. 48. Counterbalancing proportion Defined as the percentage of condylar incremental growth, detected by implants that has contributed to the enlargement of the condylion- pogonion dimension • The quantification & comparison of condylar growth & mandibular enlargement
  49. 49. Mandibular growth =pg-Ar2 – Pg-Ar1 Condylar growth – Ar1 – Ar2 Growth of articulare to pogonion Counterbalancing = Condylar incremental growth proportion ×100
  50. 50. • According to the concept of congruous mandibular growth, the proportion expected is 100%. • But the proportion ranges from 50% to 97%. • Average counterbalancing proportion for Angle classes Class III – 85% Class I – 76% Class II Div 2 – 59% Class II Div 1– 65.5% Effective contribution vary among individuals because of varying condylar directions & mand remodeling
  51. 51. Concepts of mandibular Rotations
  52. 52. Enlow’s concept Two categories of Rotations - Remodeling Rotations - Displacement Rotations
  53. 53. Remodeling
  54. 54. Ramus • Ramus undergoes remodeling to carryout following functions • Place the corpus in constant functional relationship with maxillary arch • To bridge the pharyngeal compartment • To accommodate the vertical dimension of nasomaxillary complex • Give attachment to the growing masticatory musculature.
  55. 55.
  56. 56. Vertical lengthening ramus continues after horizontal growth ceases
  57. 57. Opening and closing of the gonial angle compensates for extreme forward or backward rotation
  58. 58. • Vertical growth changes of the mandibular dento-alveolar arch, the ramus & middle cranialfossae must match nasomaxillary growth to achieve facial balance • Any diff will lead to Displacement mand Rotations
  59. 59. Displacement rotations • Changes in the junctional contact with the cranial floor and maxilla. • Cranial base angleOpen-downward and backward rotation of mandible. Closed-forward rotation.
  60. 60.
  61. 61. Closed Angle Open Angle
  62. 62. Vertically short midface causes forward rotation & upward inclination of mandible
  63. 63. Long nasomaxillary region causes downward & backward alignment of mandible
  64. 64. Schudy’s concept • The Rotation of the mandible resulting from an inhormony b/n vertical growth & horizontal growth • Counter clockwise Rotation deficiency of vertical growth compared to horizontal growth & tends to cause closed bite • Clockwise Rotation – excessive vertical growth compared to horizontal growth & tends to cause open bite
  65. 65.
  66. 66.
  67. 67. Vertical elements of growth • Growth at nasion • Growth of maxillary corpus • Growth of max post alveolar processes • Growth of mand post alveolar processes
  68. 68. Posterior growth analysis The ratio b/n horizontal growth & Vertical growth A= I+ II + III
  69. 69. Bjork concept
  70. 70. Forward Rotation – 3 Types Type – I Center- TMJ Deep bite ↓ Ant facial height Lower dental arch compressed in to upper Cause-occlusal imbalance due to loss of teeth/powerful musculature
  71. 71. • Type II • Center- incisal edges of lower ant teeth • Marked development of post facial height & normal ↑ ant facial height • ↑ Post facial height Lowering of middle cranial fossae increase in height of ramus
  72. 72. Vertical direction of the condylar growth lowered the mandible more than it is carried forward Muscular & ligamentus attachments Carries the lowered mandible forward Lower border undergoes characteristic remodeling
  73. 73. Type III Center of rotation - premolars The dental arches compressed in to each other & basal deep bite develops Cause – Anomalous occlusion of ant teeth
  74. 74. • The inclination of teeth is greatly influenced by rotation of jaws • Displaces the path of eruption of teeth in mesial direction • Ant crowding referred as packing
  75. 75. Backward Rotation –two Types Type I Center - TMJ underdevelopment of post facial height leads to Backward Rotation Causes- the middle Cranial fossae is rised -Incomplete development in height of middle cranial fossae as in oxycephaly
  76. 76. Type II • Center – Most distal occluding molars • Cause - Sagittal growth direction of condyle • The symphysis is swung backwards & chin drawn back • Double chin
  77. 77. Basal open bite develops Lower ant teeth retroclined & alveolar prognathism is reduced Rotation did not lie in the over eruption of lower teeth This type of rotation is characteristic in condylar hypoplasia & In condylar aplasia
  78. 78. Mandibular growth Rotation is closely associated with both the direction & the amount of growth at the condyles
  79. 79.
  80. 80. Maxillary Rotations
  81. 81. Bjork & Skieller Implant studies of Bjork & Skieller have shown that, The downward & forward displacement of maxillae are associated with varying degrees of vertical Rotation Internal Rotation produced with in the core of maxilla tends to be masked by surface changes & alterations in the rate of teeth eruption
  82. 82. • The maxilla is less easy to delude in to core of bone & functional processes • Alveolar process is functional process but no areas of muscle attachment
  83. 83. • Lateral implants – 4yrs of age, inserted in the zygomatic process two on each side, antly on the lower margin away from the crest •Indicates increase in width of median suture at the level of first molars
  84. 84. • Anterior implants – 10yrs of age, inserted below the anterior nasal spine on each side of median suture at the level of apices of central incisors
  85. 85. • Maxillary Rotations studied in 2 planes Transverse plane Vertical plane
  86. 86. Transverse / Mutual Rotation of two Maxillae Triangle is constructed with the sides of constant length by joining ant & lateral implants
  87. 87. • Lateral implants separate more than ant implants • Two maxillae rotate in relation to each other in transverse plane • Length of the maxilla is reduced in mid sagittal plane • Length of dental arch becomes reduced
  88. 88.
  89. 89. Vertical Rotation A line from tip of ant implant to Lateral implant is drawn on profile radiograph Tracings shows change in inclination of implant line to the SN plane at diff ages
  90. 90. The inclination of nasal floor to ant cranial base is maintained by differential remodeling In forward rotation – the resorption at nasal floor is greater antly than postly Facial growth is greater postly
  91. 91. In backward Rotation Rotates downwards & backwards Resorption at nasal floor is greater postly Facial growth is greater antly than postly
  92. 92.
  93. 93. Enlow’s Maxillary Rotations Displacement Remodeling
  94. 94. Displacement Rotations Primary displacement The whole nasomaxillary complex is displaced in conjunction with its own growth
  95. 95. Secondary Displacement - Results from growth of other bones & their soft tissues
  96. 96. • Displacement in clockwise/counterclockwise direction would result in canting & misfit of the palate & maxillary arch in to either open / closed bite positions • Remodeling fields along nasal & oral sides of the palate offset & compensate
  97. 97. Remodeling
  98. 98. 2-3 – primary displacement 1-2 - Remodeling movement
  99. 99. Prediction of mandibular growth Rotation Bjork method • Longitudinal method • Metric method • Structural method
  100. 100. Longitudinal method • The course of development in annual x-ray Cephalometric films • Superimposed on natural reference strs
  101. 101. Rotation – angle b/n SN lines
  102. 102. Limitations Pattern of growth is not constant • permits observation of changes only in sagittal direction • Changes in vertical direction are masked to larger extent
  103. 103. Metric method • Prediction of facial development on basis of facial morphology ,determined from a single x-ray • Statistical studies – predicting the intensity & direction of development from shape & size at childhood is not feasible • The changes in shape of face during adolescence weakly correlated with shape of face at 12yrs
  104. 104. Structural method • Based on information gained from implant studies of mandibular remodeling process • Recognizes specific structural signs develop as a result of remodeling • Various types of rotations can be recognized with implant method
  105. 105. Structural signs • Seven structural signs of extreme growth rotation • Considered in relation to condylar growth direction • Greater the number, more reliable the prediction will be. • Signs are not clearly developed before puberty
  106. 106. • Inclination of condylar head • Curvature of the mandibular canal • The shape of the lower border of the mandible • Inclination of the symphysis • Interincisal angle • Interpremolar and molar angles • Lower anterior face height
  107. 107.
  108. 108.
  109. 109. Condylar Inclination
  110. 110. Mandibular Canal
  111. 111. Lower Border & Inclination of Symphysis
  112. 112. Inter Incisal Inclination
  113. 113. Inter Molar Relation
  114. 114. Condylar Inclination
  115. 115. Mandibular Canal
  116. 116. Lower Border & Inclination of Symphysis
  117. 117. Inter Incisal Inclination
  118. 118. Inter Molar Relation
  119. 119. • But Baumrind & Rodney lee contradicted findings of Bjork et al very strongly
  120. 120. • The study conducted in our Department by violet barbosa, • Lower gonial angle • Inclination of condylar head • Inclination of symphysis are reliable signs to predict the type of rotation • Limited extent
  121. 121. Interaction b/n Rotation & Tooth eruption • Rotational pattern greatly influences the magnitude & direction of eruption • Superimposition on mand lower borderno change in incisor eruption
  122. 122. Forward Rotation • Superimposition on implants – forward directed path of eruption • Forward migration of whole dentition • Anterior crowding • Lower post teeth- more upright • Increase in interpremolar & intermolar angles
  123. 123. Average values: Mandibular arch Mean forward migration of mandibular molars 5.2mm. Lower central incisors-3.2mm. Shortening of the dental arch-2.0mm.
  124. 124. Average values: • Maxillary arch -Mesial migration I molars-5mm -central incisors-2.5mm Shortening of arch-1mm+1.5mm
  125. 125. Backward Rotation • Incisors become retroclined • Alv prognathism is reduced • Eruption of lower molars – hindered • Interpremolar& intermolar angles are small
  126. 126. • Proffit -The lower mandibular teeth erupt in upward and forward direction. -Forward rotation –alters the path of eruptiondirected posteriorly.
  127. 127. Clinical implications Forward Rotation • • • • • • • Short face type “Square jaw” type Low mandibular plane angle Skeletal anterior deep bite Crowding of anterior teeth Palatal plane is nearly horizontal. smile - lower incisors are visible with the upper incisors hidden behind the upper lip.
  128. 128. Backward Rotation • • • • • • Long face type “Round jaw” type Steep mandibular plane angle Skeletal anterior open bite Dental protrusion Negative inclination of palatal plane
  129. 129. • Various combinations of rotations can cause malocclusions
  130. 130.
  131. 131. Growth Rotation can also affect sagittally • Hypodivergent - can compensate for class II - worsen class III Hyperdivergent - worsen class II - compensate for class III
  132. 132. Treatment in preadolescent children Growth modificationVertical, sagittal, transverse Before adolescent growth spurt ends
  133. 133. • Both forward & Backward rotation greatly influences paths of eruption • Serious risk of extreme migration after extractions • Extractions should be avoided until the beginning of pubertal growth spurt
  134. 134. • Forward Rotation • Major risk of deep bite developing- prevented stabilizing appliance introduced before puberty • After treatment, stabilization is necessary until the growth of the jaws is completed
  135. 135. • Mandibular deficiency • Functional appliances • Removable appliances Activator, Bionator, Frankel 1&2 Bimler’s appliance, Twin block appliance • Fixed Herbst appliance, Jasper jumper, Churro jumper,Forsus
  136. 136. Mandibular excess Functional appliances Frankel 3 Reverse Activator
  137. 137. MANDIBULAR EXCESS • extra oral force • orthopedic chin cup • occipital pull chin cup vertical pull chin cup Steep mandibular plane angle & excessive lower facial height.
  139. 139. Maxillary deficiency • Growth modulation in sagittal plane can be done : 1.face mask Delaire facemask 2.reverse functional appliances. Petite facemask
  140. 140. Maxillary excess • To restrict the maxillary growth Headgear
  141. 141. Cervical head gear: used in patients with horizontal growth pattern with reduced lower facial height.
  142. 142. Occipital pull Head gear:Used in long face patients with high mandibular plane angle.
  143. 143. References • Contemporary orthodontics - William.R.Proffit(2nd &3rd ed.) • Essentials of of facial growth - Donald.H.Enlow. • Dentofacial orthopaedics with functional appliances -Thomas M.Graber, Thomas Rakosi, Alexandrer G.Petrovic.
  144. 144. • Facial growth and facial orthopedics. -van der Linden. • Determinants of mandibular form & growth (CFGS) Monograph-4 • Factors effecting growth of the midface (CFGS) Monogrph-6. • The rotation of mandible resulting from growth;Its implications in orthodontic treament -F.F.Schudy-AO,36-50.
  145. 145. • Prediction of growth rotation - A.Bjork-AJO-DO1969,jun 39-53. • Facial development and tooth eruption :an implant study at the age of pubertyA.Bjork,V.Skieller AJO-DO 1972,62,4;339-383. • Normal and abnormal growth of mandible.a synthesis of longitudinal cephalometric implant studies over a period of 25 years.A.Bjork,V.Skieller.EJO-1983,5;1-46.
  146. 146. • The puzzle of growth rotation. J.M.H.Dibbets –AJODO June 1985 ,87,6;473-480. • Mandibular rotations – concepts & terminology Beni Solow & William Houston J B-EJO1988,10;177-179. • Mandibular rotation and enlargement. J.M.H.Dibbets.AJO-DO July 1990,29-32. • Mandibular morphologic characteristics in relation to various facial types and jaw rotations.- Dr. Violet Barbosa Aug 1996.
  147. 147. Thank you Leader in continuing dental education