Part 1 explores key themes around the effectiveness of class 2 correction, how they work, different times, the role of headgear and fixed functional appliances.
Q1 & 2 Do we have the evidence, and is it effective?
Phase 1
o Phase 1 there is no advantage, no difference in clinical outcomes: Cochrane review Harrison 2007.
o 9-10% of patients benefit from phase 1 through a reduction in trauma, Gianelly 1995.
o “Just because we can doesn’t mean we should” Jay Bowman
Trauma
· Increased OJ greater than 3mm = 2 x risk of trauma Nguyen 1999
Questions 3 Growth can we predict it?
· No restraining effect on Maxilla, slight growth of the mandible and increase vertical growth Mills 1991
o 3mm growth Pg-Go
o SNB improvement of 4o
o NO we cannot - Unpredictable
Question 4 When to treat and which on?
· When: CVM 3-4 is where peak growth occure, (PHV): however only 25% of patients have 1 single peak, most have ‘multiple peaks’
· Which one: Efficiency- Herbst 0.28mm, TB 0.23mm, Herbst more efficient - fixed more efficient
Question 5 What changes take place?
Functional appliances don’t all work the same:
· Removable:
o Upper molar distalisation / upright
o Upper incisor uprighting
· Fixed
o Upper molar distalisation / upright
o Increase mandibular length (Po-Go)
Question 6 Do they grow mandibles?
· AAO Council statement 2005 – “No scientific evidence of increase in mandible”
o Lengthening of condyle and ramus does occur.
o Glenoid fossa remodelling does occur.
o No evidence shows:
§ Insignificant overall increase in length .
§ Condyle growth cannot be permanently increased.
Question 7 Does HG still have a role?
· Vertical and AP changes do occur with HG after 6/12 Burke 1992, Nanda 2006,
· Compliance however is 56% Brandao
Question 8 Effectiveness of fixed functional appliances?
· Compliance nearly 100%
· Phase 1 shorter 4.5 months
· Forsus Vs Powerscope:
o More AP change with Forsus Arora 2018
· New ideas of fixed functional and TAD / miniplates
References
Harrison, J.E., D O'Brien, K. and Worthington, H.V., 2007. Orthodontic treatment for prominent upper front teeth in children. Cochrane Database of Systematic Reviews, (3)
Nguyen, Q.V., Bezemer, P.D., Habets, L.L.M.H. and Prahl-Andersen, B., 1999. A systematic review of the relationship between overjet size and traumatic dental injuries. European Journal of Orthodontics, 21(5), pp.503-515.
Mills, J.R.E., 1991. The effect of functional appliances on the skeletal pattern. British Journal of Orthodontics, 18(4), pp.267-275.
Vaid, N.R., Doshi, V.M. and Vandekar, M.J., 2014, December. Class II treatment with functional appliances: A meta-analysis of short-term treatment effects. In Seminars in Orthodontics (Vol. 20, No. 4, pp. 324-338). WB Saunders.