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Canine substitution Neal Kravitz. Episode 143. December 16th 2021

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Hosted by
Farooq Ahmed

 

Join me for Neal Kravitz’s lecture on canine substitution and the clinical management of it. Focusing on bracket selection and canine recontouring

 

 

Case selection

  • 2 key factors
    • Profile
    • Mandibular crowding

Bracket selection

  • Goal:
    • Canine substitution:
      • Reduce canine root prominence
    • Premolar substitution:
      • Hide palatal cusp
    • Molar interdigitation:
      • class 2 cases

4 bracket choices for canine

  • UR1 (+17 tq, + 4 tip)
  • Achieves ideal torque
  • Requires flattening of canine labial face = plasty
  • UR2 (+10 tq, + 8 tip)
    • plasty and step out
  • UR3 inverted (+7tq, +8 tip)
    • Flipped U3
    • Likely require addional torque
  • LL5 inverted (+17 tq, +2 tip)
    • Suggested by Marco Rosa
    • Same torque but no reduction labial face – compound contour

Upper 1st premolar bracket selection

Upper molar tube selection for class 2 finish

  • Achieve good interdigitation, the U6s tubes have 10 degree rotation labially, which does not interdigitate with the lower 5/6 embrasure space well, the 0 degree offset on lower 6s / 7s (-20 / -10 torque)
  • No change in tip and torque

Tooth reshaping

 

  • Canine morphology frequently triangular, more so mesial then distal
  • Reduction – frequently underdone
    • Mesial IPR – Kailasam 2021 1.2mm enamel mesial
    • Incisal reduction
    • Palatal reduction

Interproximal reduction for Bolton’s discrepancy

Class 1

  • Canine substitution with lower extractions = maxillary excess
    • = IPR uppers to correct Bolton’s discrepancy (U 1, 3, 4)

Class 2

  • Canine substitution, lower non-ext = Mandibular excess
    • = IPR lower anterior to correct Bolton excess (U 1, 3, 4)

Cosmetic bonding

  • Step 1: Mesial step out
    • Improve marginal ridge with central
    • Reduce occlusal interference lower arch
  • Step 2: Mesial build up
    • Mesial incisal
    • Line angle not that I practice it but they are essentially
      • Transition between proximal and labial face
      • Can make canine look narrower through altering this transition, ie the shallower gradient narrower the tooth

Retention and review

  • Group function and lateral clearance
  • Long term fixed retention 4-4
    • Length of bonded retainer
      • Lower canine mid to distal lateral incisor labial measurement = lingual 3-3 measurement
    • Material – memotain Custom NiTi

References

 

Rosa, M.A.R.C.O. and Zachrisson, B.U., 2001. Integrating esthetic dentistry and space closure in patients with missing maxillary lateral incisors. Journal of Clinical Orthodontics35(4), pp.221-238

 

Kokich Jr, V.O. and Kinzer, G.A., 2005. Managing congenitally missing lateral incisors. Part I: Canine substitution. Journal of esthetic and restorative dentistry17(1), pp.5-10.

 

Kravitz, N.D. and Shirck, J.M., 2017. Measuring Bonded Lingual Retainers. Journal of clinical orthodontics: JCO51(5), pp.294-294.

 

Kravitz, N.D., Miller, S., Prakash, A. and Eapen, J.C., 2017. Canine bracket guide for substitution cases. J Clin Orthod51, pp.450-453.

 

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