The original Twin Block appliance was developed and introduced by Dr. Clark¹ in 1982. Throughout the years there have been many modifications by McNamara and others to treat various malocclusions.

 

One of the problems with the original design was the need to add acrylic for reactivation to achieve an edge-to-edge incisor position, or for overcorrection to compensate for the expected 2-3 mm relapse. Studies have shown that a gradual bite advancement results on better patient compliance and comfort, and theoretically a more orthopedic effect. ² ³ 

 

Geserick and Olsburgh, along with Forestadent, Have developed a bite-jumping screw that allows for a gradual advancement while maintaining a 70º interface between the blocks 4. This Twin Block modification can be used to achieve a 6mm anteroposterior correction in either Class II or Class III cases.

References

1. Clark, W.J.; the Twin Block traction technique, Eur. J. Orthod. 4:129-138, 1982

2. DeVicenzo, J.P. and Winn, M.W.; Orthopedic and Orthodontic effects resulting from the use of a functional appliance with different amounts of protrusive activation, Am. J. Orthod. 96:181-290, 1989

3. Bass, N.M.; Interceptive Orthodontics, European Orthodontic Society of congress, Brighton, England, 1996

4. Geserick, M. and Olsburgh, S.R.; The Bite-Jumping screw for Modified Twin BlockTreatment, Journal of clinical Orthod.,Volume XL Number 7,  432-435, July 2006.