Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Dentoalveolar compensations /certified fixed orthodontic courses by Indian dental academy


Published on

The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

  • Be the first to comment

Dentoalveolar compensations /certified fixed orthodontic courses by Indian dental academy

  1. 1. DENTOALVEOLAR COMPENSATION INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. CONTENTS uction orm & malocclusion tendencies sional and alignment pattern combinations nathic Surgery ion for orthognathic surgery pensation mination of compensation or dysplastic development
  3. 3. INTRODUCTION In our life time, we have seen the faces of thousands of people , and each face is recognizable to us as distinct individual. No two faces are quite alike, even those of identical twins. The coordination of the development of the upper and the lower jaws are far from perfect. This imperfection can be compensated by skeletal and dentoalveolar changes camouflaging the actual deviation. This mechanism first described by Bjork as the “dentoalveolar compensatory mechanism” and
  4. 4. “ Process or mechanism by which the development of dental and alveolar arches are controlled so as to secure occlusion of the teeth and adaptation to the basal parts of the jaws.”
  5. 5. What is compensation ??? It is a constant ongoing process striving towards ultimate homeostasis during growth . When the growth process is complete a state of compromise equilibrium has been achieved . Compensation can be more aptly called as “ Developmental adjustments for working towards balance ” .
  6. 6. If we have compensatory features , the built in tendencies are offset , to a greater or lesser extent . If it is less then complete malocclusion will be more fully expressed but less severe than the tendencies otherwise could produce.
  8. 8. Shape of the head There are two basic extremes in the shape of the head Dolichocephalic Brachycephalic The cephalic index is the ratio between overall head length & breadth: -Dolichocephalic = Upto 75.9% -Mesocephalic = 76 to 80.9% -Brachycephalic = Over 81%
  9. 9. Dolichocephalic head form Brain is horizontally long and narrow
  10. 10. Cranial base is flat- flexure between the middle cranial floor & anterior cranial floor open . Occlusal plane is rotated downward.
  11. 11. mandibular retrusion, class II molar relation The resultant profile is retrognathic.
  12. 12. BRACHYCEPHALIC HEAD FORM Brain is short, wide.
  13. 13. Basicranial floor is more upright and has a more closed flexure Decreased effective antero-posterior dimension of the middle cranial fossa Posterior placement of the maxilla Horizontal length of the nasomaxillary complex is short. Retrusion of nasomaxillary complex and more forward relative placement of mandible.
  14. 14. The resultant profile is prognathic Class III molar relationship
  15. 15. COUNTERPART PRINCIPLE Growth of any given facial or cranial part relates specifically to other structural & geometric "counter parts" in the face & cranium. e.g maxillary arch is a counterpart of mandibular arch If part and counter part enlarge to same extent , balanced growth is produced.
  16. 16.
  17. 17. COUNTERPART ANALYSIS In this method various facial and cranial parts are compared with each other. The individual is measured against himself,rather than compared with population standards and norms. Size and alignment of the bones are considered. Vertical and or horizontal size of one given part is compared with that of its specific counter parts. If they exactly match, or nearly so , a dimensional balance exist between them.
  18. 18. Three vertical architectural counterparts 1. Cranial floor ramus vertical.. 2. Posterior nasomaxilla.. 3. Anterior nasomaxilla..
  19. 19. If vertical dimensional imbalance occurs Downward occlusal rotation Upward occlusal rotation Open bite
  20. 20. Four horizontal architectural counter parts 4. Middle cranial fossa 5. Ramus 6. Maxilla 7. Mandibular corpus
  21. 21. Horizontal dimensional imbalance Maxillary protrusion Dimensional compensationRamus Dimensional compensationCorpus
  22. 22. Factors responsible for dentoalveolar compensatory mechanism 1. Normal eruptive system 2. Soft tissue envelope 3. Influence on tooth exerted by neighboring teeth during growth
  23. 23. Dentoalveolar compensatory mechanism and malocclusion Two main types of malocclusion: • Inter arch deviation - occlusion anomalies • Intra arch deviation - space anomalies
  24. 24. Three main situations where dentoalveolar compensation is impaired . 1. An optimally functioning dentoalveolar compensatory mechanism 2. In cases where functioning of dentoalveolar mechanism is incomplete 3. In cases where for some reason the compensatory mechanism is inoperative
  26. 26. Horizontal dimension of the mandibular corpus short relative to its counter part Mandibular retrusion, Anterior crowding . Need not be class II
  27. 27. Mandibular corpus is dimensionally longer relative to its counter part Mandibular protrusion Class III molar relation depends on whether mandible is long mesial or distal to the I molar. Horizontally short maxillary arch has the effect
  28. 28. Horizontally long nasomaxillary complex No effect on occlusion Individual can appear retrognathic – protrusive nature of upper part of face.
  29. 29. Horizontal dimension of the ramus is narrow relative to its counterpart-middle cranial fossa Mandibular retrusive effect. This is one of basic skeletal cause that underlie a class II molar relationship
  30. 30. The effective horizontal dimension of the ramus is broad relative to middle cranial fossa Mandibular protrusion. One of the reasons for class III molar relation
  31. 31. Vertically long nasomaxillary complex Downward and backward rotation Mandibular retrusion
  32. 32. Vertically short nasomaxillary complex Upward and forward rotation Mandibular protrusion
  33. 33. The Posterior Maxillary Plane The PM plane is a developmental interface between the vertical series of counterparts in front of, and behind it. This key plane retains these basic relationships throughout the growth process.
  34. 34. Neutral Occlusal Axis (N.O.A.):- In a well balanced face both functional occlusal plane and N.O.A. will be coinciding.
  35. 35. The alignment of parts are in neutral position. Occlusal plane is perpendicular to PM plane and parallel to neutral orbital axis
  36. 36. COMPENSATORY MECHANISM During the development and establishment of the occlusion, ongoing and intensive adjustment occurs involving dentoalveolar remodeling . The effect of dentoalveolar compensatory mechanism on dimension of the dental arches ,the inclination of the teeth and occlusal relationships has been well documented
  37. 37. Compensation by ramus in dolicocephalic pattern
  38. 38. Nasomaxillary complex lengthened vertically Mid facial growth has exceeded the growth of ramus and middle cranial fossa complex Downward backward alignment of the whole mandible to accommodate the longer nasomaxillary complex..
  39. 39. Upper teeth drift inferiorly till they contact the antagonist. Occlusal plane is a straight line , inclined downward.
  40. 40. Dentoalveolar curve (Curve of spee) Upper teeth drift down . The upper anterior drift only to the level of the premolar. Anterior mandibular teeth drift superiorly till they contact the upper. Occlusal plane is curved.
  41. 41. ANTERIOR CROWDING Teeth have very little capacity to remodel after they are formed fully. Only a limited extent of root resorption, deposition of cementum , crown wear are possible in this regard. This means that adaptive adjustment for a tooth must be carried out by the displacement process .
  42. 42. While extensive resorptive & depository remodeling is a basic growth function for the housing alveolar bone, it is not a factor for the tooth itself . Thus anterior crowding is , in effect, a compensatory means by which the teeth are housed beyond the limit provideded by the alveolar bone .
  43. 43. Compensation for variation in the sagittal jaw relationship. • In cases of skeletal class II. To compensate for the large sagittal discrepancy in jaw relationship the upper incisor are retroclined and lower incisor are proclined to maintain normal overjet. • In cases of skeletal class III. The upper incisors are proclined and the lower incisors are retroclined to maintain normal overjet. (Hiroyaki ishikava
  44. 44. Compensation for variation in vertical jaw relationship. • In cases of skeletal open bite, To maintain the normal overbite, the posterior dentoalveolar segment intrudes. The anterior dentoalveolar segment extrudes or both can happen. • In a case of skeletal deep bite The posteriors can extrude or the anteriors can intrude to maintain a normal overbite.
  45. 45. Compensation for variations in transverse jaw relationship. • A discrepancy between a narrow maxillary base and a wide mandibular base is compensated by buccal tilting of upper teeth and lingual tilting of lower teeth. • Discrepancy between wide maxillary base and narrow mandibular base is compensated by lingual tilting of upper teeth and by buccal tilting of lower teeth.
  46. 46. In ideal situations, this compensation masks discrepancies in all three planes of space. The dentoalveolar changes may however also be unfavourable or dysplastic and contribute to an occlusal problem more severe than that caused by actual skeletal discrepancy .
  47. 47. Orthognathic Surgery:- Every patient who goes for a surgical line of treatment should be put on an orthodontic appliance to carry out the presurgical decompensation. Here upper and lower arches are separately aligned but no attempt is made to correct the bite by orthodontic means as bite will be corrected by surgical repositioning of the jaw to get a near occlusal fit as possible.
  48. 48. INDICATION FOR PRE-SURGICAL ORTHODONTICS ( BELL AND PROFIT ) 1 ) When segments in the skeletal cannot be & dento osseous placed a satisfactory relationship because of gross occlusa1 interferences or gross malrelation of teeth to their supporting bone . 2 ) When postsurgical orthodontic work would necessitate tooth
  49. 49. What is decompensation? In many cases of severe jaw imbalances and the resulting malocclusion, the teeth are inclined in such a manner as to partially offset the discrepancies. Pre surgical orthodontics should be aimed at removing this natural compensation or to decompensate.
  50. 50. NEED FOR PRESURGICAL DECOMPENSATION 1. To position the teeth in an ideal axial inclination with respect to the jaws. 2. To optimize the magnitude of surgical advancement or repositioning. 3. For better esthetics , stability and function. 4. If malpositioned anterior teeth are not corrected , they may hinder the repositioning of jaws at the time of surgery.
  51. 51. Determination of compensation or dysplastic development IN THE MAXILLA, the "maxillary zone" measured as the angle between the palatal plane (ANS-PNS) and the maxillary occlusal plane ( mean 10 +- 3 ), describes the extent of compensatory or dysplastic development.
  52. 52. IN THE MANDIBLE, the "mandibular zone" measured between the mandibular plane (Go-Gh) and the mandibular occlusal plane (mean 20 +- 4) similarly describes possible compensation. If one or both of these measurement are increased in a patient with increased vertical jaw relations; favourable dentoalveolar compensation is indicated. On
  53. 53. Dentoalveolar compensation in negative over jet cases were statistically confirmed for both incisor inclination and occlusal plane angulation. However the compensatory effects were weaker than with positive overjet cases. Hiroyaki ishikava
  54. 54. Leader in continuing dental education