Accelerated tooth movement in orthodontic is a challenging task to shorten the treatment time
Research in this area confined into the following categories;
1- Biomechanical approach: as self-ligating system
2- Physiological approach: such as direct electric stimuli, or low level Laser therapies (LLLTs)
3- Pharmacological approach: local injection of cytokines or hormones
4- Surgical assisted approach: periodontal ligament distraction, dento-alveolar distraction, selective decortication,
5- Surgery simulated approach: as submucosal injection of platelets rich plasma (PRP)
1- Biomechanical approach: self-ligating bracket system
= 1st self-ligating -------- Russell attachment 1935
= edge lock (oramco) ----- 1972
= mobile lock (Forstadent) ------1980
= speed ---------------- 1980
= active --------------- 1986
Self-ligating brackets has 2 categories, active and passive
Active: bracket have a spring clip that store energy to pass against the arch wire
Passive: bracket have slide that can be closed and does not encroach on slot lumen
Self-ligating bracket enable tooth to slide along an arch wire with lower and more predictable net forces with complete control
Mechanism:
The primary advantage of self-ligating over conventional that occurs because the usual steel or elastomeric ligature not necessary
Passive design generates less friction than active one. Under conventional, the friction / bracket with Niti wire was 41gm in Dentaurum bracket, and 15gm with Damon bracket with stainless steel wire
With reduced friction may become 3.6gm so less force needed to produce movement
Self-ligating bracket produce more physiologically harmonies tooth movement by interrupting periodontal vascular supply so:
- More alveolar bone generation
- Greater amount of expansion
- Less Proclination of anterior segment
- Less need for extraction
** several systematic reviews and studies revealed that self-ligating bracket do not accelerate alignment or space closure in clinical setting, this approach paradox in likely due to the effect of binding because when the teeth tip, rotate or torque, the edges of slot engage the arch wire creating binding so that resistance to sliding increase.
** because the bracket design of self-ligating is narrower than conventional type so the effect of binding is greater resulting in increased resistance to sliding compared with conventional. Less incisor Proclination appear the more advantage of self-ligating bracket
** tooth movement is a metabolic process of alveolar bone resorption and deposition of bone, so acceleration of movement may affect by biological and surgical procedure
2- Physiological approach: direct electric current stimulation:
Beason et al, the 1st that proposed use of electric current for orthodontic tooth movement near to tooth that moved but failed to demonstrate the effect on movement
DavidoVitch et al reported successful results in accelerating orthodontic tooth movement through direct current on gingival tissue as