Full mouth rehabilitation/ Labial orthodontics

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Full mouth rehabilitation/ Labial orthodontics

  1. 1. Part V INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Contents  Factors that determine disclusion  Disocclusion  Classification of occlusal rehabilitation  Hobo’s twin table technique  Hobo’s twin stage technique  Conclusion www.indiandentalacademy.com
  3. 3. Factors that determine disclusion I. Anterior guidance II. Condylar guidance III. Cusp angulation www.indiandentalacademy.com
  4. 4.  Takayama and Hobo derived kinematic formulae to calculate anterior guidance from the condylar path. Anterior guidance computed from these formulae confirmed a statistical correlation to the data of anterior guidance on the same patients at p < 0.01 level of significance. www.indiandentalacademy.com
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  6. 6. Angle of hinge rotation  The mandible rotates around the intercondylar axis during eccentric movements when anterior guidance is steeper than the condylar path. The factor that compensates for the difference in steepness is the angle of hinge rotation. www.indiandentalacademy.com
  7. 7.  Takayama and Hobo analyzed disclusion relative to the angle of hinge rotation by using kinematic formulae. The results indicated that the angle of hinge rotation contributed to posterior disclusion by approximately 0.2 mm for protrusive movement 0.5 mm on average for lateral movement on both working and nonworking sides. www.indiandentalacademy.com
  8. 8.  The amounts of disclusion were 1.1 +- 0.6 mm during protrusive movement 0.5 +- 0.3 mm on the working side 1.0 +- 0.6mm on the nonworking  Measured at the mesiobuccal cusp tip of the mandibular first molar . www.indiandentalacademy.com
  9. 9. Degree of disclusion Measured value Angle of hinge axis Cusp shape factor Protrusive 1.1 0.2 0.9 Working 0.5 0.5 0 Non working 1.0 0.5 0.5 www.indiandentalacademy.com
  10. 10. Cusp shape factor www.indiandentalacademy.com
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  12. 12.  If the shapes of the posterior cusps are less steep than the condylar path, the posterior teeth disclude even if anterior guidance is parallel to the condylar path.  The semicircular shape of the cusps affects the posterior disclusion.  This is called Cusp shape face . www.indiandentalacademy.com
  13. 13. Disocclusion www.indiandentalacademy.com
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  18. 18. Deviation of condylar path  When repetitive lateral movements were compared with the respective condylar paths, no movement traced the same line. The deviation in the condylar path during eccentric movements was attributed to the shock-absorbing nature of the articular disk. This deviation in condylar path is referred as a "buffer space." www.indiandentalacademy.com
  19. 19. Buffer space (mm) Disclusion (mm) Protrusive 0.8 1.1 Working 0.3 0.5 Non working 0.8 1.0 www.indiandentalacademy.com
  20. 20. The width between the eccentric and the returning condylar path measured at 2mm from the condylar position in maximum intercuspation. www.indiandentalacademy.com
  21. 21. Width between eccentric and returning condylar path Unit (mm) Mean SD Protrusive movement 0.44 0.26 Lateral movement 0.79 0.37 www.indiandentalacademy.com
  22. 22. Comparison between sagittal condylar path inclinations of eccentric and returning path Unit (mm) Eccentric path Returning path Differen ce Mean SD Mean SD Mean Protrusive movement 40.1 13.8 27.4 7.6 12.7 Lateral movement 40.5 11.8 17.5 10.9 23.0 www.indiandentalacademy.com
  23. 23.  Standard amount of disocclusion at second molars was 1.0 mm at protrusive movement of 3 mm.  When the sagittal condylar path inclination decreased, it displaced the position of the cusp of the mandibular second molar in a superior direction by 0.020mm per degree. Influence of condylar path on amount of disocclusion www.indiandentalacademy.com
  24. 24.  Rate of influence of sagittal lateral condylar path inclination is 0.015 mm on the non working side – 0.002 mm on the working side per degree.  The influence of deviation in the condylar path on the amount of disclusion was calculated :  Protrusive : 0.26 mm  Non working side : 0.35 mm  Working side : - 0.05 mm www.indiandentalacademy.com
  25. 25.  When sagittal inclination decreases by one degree, amount of disclusion decreases by Protrusive : 0.038 mm  When frontal inclination decreases by one degree, amount of disclusion decreases by Non working : 0.042 mm Working : 0.038 mm Influence of incisal path on amount of disocclusion www.indiandentalacademy.com
  26. 26. Variation in incisal path is approximately 10 degrees  Protrusive : 0.38 mm  Non working : 0.42 mm  Working : 0.38 mm www.indiandentalacademy.com
  27. 27. Cusp angle www.indiandentalacademy.com
  28. 28.  When the cusp angle increases by one degree the amount of disclusion decreases by 0.046 mm during protrusive movement 0.046 mm on the non working side 0.041 on the working side.  The influence of cusp angle is 40% - 44% of the total influence far greater than condylar path but comparable to incisal path. www.indiandentalacademy.com
  29. 29. Classification of occlusal rehabilitation www.indiandentalacademy.com
  30. 30. There are four types of occlusal rehabilitation situations: A. The curve of Spee and the incisal guidance are acceptable and the posterior teeth need rehabilitation. The treatment plan includes the restoration of the lower posterior teeth to the patient's curve of Spee.  Then the upper posterior teeth are restored by the functionally generated path technique. www.indiandentalacademy.com
  31. 31. B. The curve of Spee is irregular, but the incisal guidance is acceptable. The treatment plan involves the restoration of the lower posterior teeth to a more desirable curvature. Then the upper posterior teeth are restored with the functionally generated path technique and the existing incisal guidance. www.indiandentalacademy.com
  32. 32. C. The curve of Spee and the incisal guidance are both unacceptable.  The treatment plan involves:  The correction of the incisal guidance by restoring the upper anterior teeth by means of jackets or pinlays  The restoration of the lower posterior teeth to a more desirable occlusal curvature  The restoration of the upper posterior teeth with the use of the functionally generated path technique. www.indiandentalacademy.com
  33. 33. D. The curve of Spee and the incisal guidance are not acceptable, and the upper and lower anterior teeth need rehabilitation.  The treatment plan involves:  The restoration of all the lower anterior teeth  The restoration of the upper anterior teeth and the incisal guidance  The restoration of the lower posterior teeth to a more acceptable occlusal curvature, and  The restoration of upper posterior teeth with the use of the functionally generated path technique www.indiandentalacademy.com
  34. 34. Hobo’s twin table technique www.indiandentalacademy.com
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  41. 41. It is critical to form the resin cones toward the outer edge of the path. www.indiandentalacademy.com
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  47. 47. Hobo’s twin stage technique www.indiandentalacademy.com
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  50. 50. STANDARD VALUE OF THE CUSP ANGLE  Since there are minimal variations in cusp morphology of permanent teeth immediately after eruption, and if the value of the cusp angle at the time of eruption is used as a reference for occlusion, making a restoration following this guide should be ideal for the patient. www.indiandentalacademy.com
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  52. 52. Cusp angle Cusp angle on molars (deg) Sagittal protrusive effective 25 Frontal lateral effective (working side) 15 Frontal lateral effective (non working side) 20 Standard values of effective cusp angles on molars www.indiandentalacademy.com
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  55. 55.  Adjust the condylar path to 40 degrees and the anterior guide table to 45 degrees when fabricating anterior guidance with the anterior segment attached to the cast. In this manner, (1) The standard amount of disocclusion will be obtained on molars (2) A physiological anterior guidance will be fabricated. www.indiandentalacademy.com
  56. 56. Physiological discrepancy If the sagittal condylar path of the patient is steeper than the articulator adjustment value (40 degrees), the amount of disocclusion increases. If the condylar path in the patient is shallower than 40 degrees, the amount of disocclusion decreases to some extent.  The sagittal condylar path distributes +/- 14 degrees (SD) from the mean value (40 degrees). www.indiandentalacademy.com
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  58. 58.  Presently, the twin-stage procedure is contraindicated in the following cases : A. Abnormal curve of Spee B. Abnormal curve of Wilson C. Abnormally rotated tooth D. Abnormally inclined tooth www.indiandentalacademy.com
  59. 59. Stage I: Fabrication of the cusp angle  Adjust an articulator to the following values:  Sagittal condylar path inclination =25 degrees  Bennett angle=15 degrees  Sagittal inclination of the anterior guide table=25 degrees  Lateral wing angle=10 degrees. www.indiandentalacademy.com
  60. 60.  Make the anterior segment of the maxillary or mandibular cast removable using dowel pins.  Remove the anterior segment.  Make the maxillary and mandibular casts on the articulator so that they do not disocclude during eccentric movement.  Balanced articulation is obtained and every cusp will have a standard cusp angle www.indiandentalacademy.com
  61. 61. Stage II: Fabrication of anterior teeth  Adjust an articulator to the following values:  Sagittal condylar path inclination=40 degrees  Bennett angle=15 degrees  Sagittal inclination of the anterior guide table=45 degrees  Lateral wing angle=20 degrees www.indiandentalacademy.com
  62. 62.  Reassemble the anterior segment of the cast.  The maxillary and mandibular casts on the articulator produce the standard amount of disocclusion.  Wax the palatal contours of the maxillary anterior teeth so incisors contact during protrusive movement, and the canines on the working side contact during lateral movement.  Anterior guidance is established and the standard amount of disocclusion will be produced. www.indiandentalacademy.com
  63. 63. Articulator adjustments for twin stage Stage Condylar path Anterior guide table Sagittal path inclination Bennett angle Sagittal inclination Lateral wing angle Stage I: without anterior teeth 25 15 25 10 Stage II: with anterior teeth 40 15 45 20 www.indiandentalacademy.com
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  90. 90. Conclusion  Modern dental treatment is designed to focus on one predominant goal: optimally maintainable oral health.  Any factor that lessens the maintainability of any oral tissue is a factor that must be isolated and corrected. To do less is to fail the task entrusted to us. www.indiandentalacademy.com
  91. 91.  The broad aim of our work and the restoration of function must always be kept in mind. Then only can we estimate the value of the techniques involved, espousing some methods and materials and rejecting others. www.indiandentalacademy.com
  92. 92. For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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