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

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 1^st premolar bracket selection

• U3 or U4 slightly distal – palatal cusp hidden
• See orthoinsummary blog on Premolar substitution

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 Orthodontics, 35(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 dentistry, 17(1), pp.5-10.

Kravitz, N.D. and Shirck, J.M., 2017. Measuring Bonded Lingual Retainers. Journal of clinical orthodontics: JCO, 51(5), pp.294-294.

Kravitz, N.D., Miller, S., Prakash, A. and Eapen, J.C., 2017. Canine bracket guide for substitution cases. J Clin Orthod, 51, pp.450-453.