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
o Profile
o Mandibular crowding
Bracket selection
· Goal:
o Canine substitution:
§ Reduce canine root prominence
o Premolar substitution:
§ Hide palatal cusp
o 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)
o plasty and step out
· UR3 inverted (+7tq, +8 tip)
o Flipped U3
o Likely require addional torque
· LL5 inverted (+17 tq, +2 tip)
o Suggested by Marco Rosa
o Same torque but no reduction labial face – compound contour
Upper 1st 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
o Mesial IPR – Kailasam 2021 1.2mm enamel mesial
o Incisal reduction
o Palatal reduction
Interproximal reduction for Bolton’s discrepancy
Class 1
· Canine substitution with lower extractions = maxillary excess
o = IPR uppers to correct Bolton’s discrepancy (U 1, 3, 4)
Class 2
· Canine substitution, lower non-ext = Mandibular excess
o = IPR lower anterior to correct Bolton excess (U 1, 3, 4)
Cosmetic bonding
· Step 1: Mesial step out
o Improve marginal ridge with central
o Reduce occlusal interference lower arch
· Step 2: Mesial build up
o Mesial incisal
o 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
o Length of bonded retainer
§ Lower canine mid to distal lateral incisor labial measurement = lingual 3-3 measurement
o 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.
