Defined
- Irreversible shortening of the root due to tooth movement
When moving a tooth what happens to the root?
- Craters in the cementum – due to over activation of cementoblasts
- Craters resolves on the root services
- But not on the apex, unsure why
Prevalence of RR
- 25% up to 2mm
- 5% up to 4mm, Smemhima 2004
Aetiology Hartsfield 2010
- Genetics 65%
- Mechanics 15%
- Unknown 20%
Predispositions
- No difference in gender
- Slight increase in adults
- Idiopathic root syndrome
- Multiple idiopathic apical external root resorption
Treatment factors 15% of aetiology
- Extended treatment time systematic review Roscoe 2015
- Genetic explanation, allele where there is a threshold to forces, resulting in no repair after a certain time. Al-Qasami
- Apical displacement of the root (overjet and extraction) Iglesias-linares 2017, Nuria 2017
- 5mm – 4.5mm apical displacement = 1-1.7mm resorption
Systematic reviews
- Apical displacement and treatment duration increase RR Segal 2004
- Light forces for intrusion reduces risk of root resorption Weltman 2010
- Increased force levels and treatment time increase RR Roscoe 2015
- Increased continuous force, intrusion and treatment duration increase RR Currell 2019
RR of root canal treated teeth
- No difference in RR Castro 2014
- Slight reduction in RR Kolcuoglu 2020
Immature apex
- Less likely to get RR
Aligners and RR
- No difference – Iglesias-Linares 2017
- Depends on tooth movement, not type of appliance
No difference with micro perforation or photobiomodulation
What to do if RR?
- Stop for 3 months
- When resume less likely RR
Prognosis long term of RR
- Lateral incisors with severe RR (from canines) long term stable , even with 20% increase crown : root ratio Becker 2009
- Increase in mobility with extreme RR
- NO TOOTH LOSS RR Jonsson 2007
- Teeth with severe RR usually stabilise
