Functional appliances

1. Functional appliances

2. Background • Functional appliances are conceptually based on Moss’ functional matrix theory • Functional matrix theory proposes that functional matrices, tissues like muscles and glands influence skeletal units such as jaw bones and ultimately control their growth

3. Form follows function

6. Functional appliance types • Orthodontic functional appliances may be active or passive: • Active appliances reposition the mandible so that the condyle is forced out of the glenoid fossa and this in turn is thought to stimulate the posterior/superior growth of the condyle • Passive appliances act by repositioning the musculature associated with the mandible so that the jaw bone itself responds by growing to the new equilibrium position

7. Passive functional appliances • Frankel

8. Active functional appliances • Fixed active functional appliances • Herbst

9. Active functional appliances • Removable active functional appliances • Bionator

10. Active functional appliances • Removable active functional appliances • Woodside activator

11. Active functional appliances • Removable active functional appliances • Twin-block appliance

12. Duration and timing of wear • Functional appliance treatment should be started before the pubertal growth spurt • This is the time when the mandible may exhibit increased growth which may be influenced • Functional appliances should be worn for at least 10-12 hours a day • These appliances should be worn at nighttime as this is when growth takes place

13. Evidence of clinical effectiveness • A Cochrane review, published in 2008, studied orthodontic treatment for prominent upper teeth in children • The study concentrated on primary outcomes including the prominence of upper front teeth and the relationship between upper and lower jaws • The secondary outcomes compared included self-esteem, injury to teeth, joint problems, patient satisfaction and the number of appointments during active treatment

14. Evidence of clinical effectiveness • It has been shown that when front teeth stick out by more than 3mm, they are twice as likely to be injured • The Cochrane review included eight clinical trials, based on data from 592 patients with Class II Division 1 • Three trials, evaluating 432 patients, compared early treatment (before the age of 10) with a functional appliance compared to no treatment • It was found that functional appliance treatment resulted in significant decreases in overjet and the ANB angle

15. Evidence of clinical effectiveness • When the same patients received the second phase of treatment (full fixed treatment) and when they were compared to patients who only received one phase of treatment in adolescence, it was found that there were no significant differences • Other reviews have also found that although the overall effect of early treatment was not significant, the patients did have a milder malocclusion at the start of full fixed treatment

16. Evidence of clinical effectiveness • A systematic review by Cozza et.al. included 18 retrospective longitudinal controlled clinical trials • It was found that functional appliances did result in a significant elongation of mandibular length (>2mm) • It was concluded that the effect of growth modification is the greatest during the pubertal growth peak

17. What does this mean? • According to the evidence one should not use functional appliances as they are not necessarily more efficient than one phase treatment • Should we rely only on evidence in guiding our clinical decisions? • I would argue that although sound scientific evidence is the most important aspect of clinical practice, it is not the only factor to consider

18. What does all this mean? • Indeed, care for our patients extends beyond all the evidence available • True care also includes: • Honesty • Empathy • Being genuine • Patient centered approach

19. Refernces • http://cache.virtualtourist.com/3709891-Long_neck_Karen_in_Shan_state_of_Burma-Burma.jpg • http://farm1.static.flickr.com/47/154578698_6011a485ce.jpg • http://www.sleepingtiger.org/blog/wp-content/uploads/2007/08/maxyawns.jpg • http://imagecache2.allposters.com/images/146/PP0195.jpg • http://www.nimrodental.co.uk/appliances/media/functional5.jpg • http://coloradospringsortho.com/Web%20site/About%20braces_files/herbst_appliance.jpg • http://www.weisskircher.de/bilder/bionator.jpg • http://www.tanos.co.uk/braces/bkb/images/activatorwoodside.jpg • http://www.orthodentlab.com/products/images/photos/TwinBlock1.jpg

20. References • Harrison JE, O’Brien KD, Worthington HV. Orthodontic treatment for prominent upper front teeth in children (review). The Cochrane Collaboration. John Wiley & Sons, 2008. • Nguyen QV, Bezemer PD, Habets L, Prahl-Andersen B. A systematic review of the relationship between overjet size and traumatic dental injuries. European Journal of Orthodontics 1999;21(5):503-515. • Pavlow SS, McGorray SP, Taylor MG, Dolce C, King GJ, Wheeler TT. Effect of early treatment on stability of occlusion in patients with Class II malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics 2008;133:235-244. • Dolce C, McGorray SP, Brazeau L, King GJ, Wheeler TT. American Journal of Orthodontics and Dentofacial Orthopedics 2007;132:481-489. • Cozza P, Baccetti T, Franchi L, De Toffol L, McNamara JA. Mandibular changes produced by functional appliances in Class II malocclusion: a systematic review. American Journal of Orthodontics and Dentofacial Orthopedics 2006;129:599.e1-599.e12.