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Title Continuous Force Application Leads to More Root Resorption Than Intermittent Force Application in Adolescent Orthodontic Patients
Clinical Question In adolescent patients undergoing orthodontic treatment, do continuous orthodontic forces compared to intermittent forces cause an increased incidence of root resorption?
Clinical Bottom Line In adolescent patients undergoing orthodontic treatment, continuous orthodontic forces lead to an increased amount of root resorption when compared to intermittent forces. This is supported by three clinical trials that all came to the same conclusion using similar experimental methods.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 19577132Ballard/200916 maxillary premolars from 8 patients (13.4-18.6 years)Randomized Controlled Trial
Key resultsThe use of intermittent orthodontic forces led to a decreased volume of root resorption compared to continuous forces (0.815 mm3 vs. 0.985 mm3, respectively) (p<0.05).
#2) 10227557Acar/1999 22 premolars from 8 patients (15-23 years)Clinical Trial
Key results40% of roots showed moderate resorption in premolars subjected to intermittent orthodontic forces, compared to 60% for premolars subjected to continuous forces.
#3) 12938838Wieland/200390 premolars from 27 patients (10.2-14.5 years)Clinical Trial
Key resultsTeeth moved continuously with a superelastic wire had 6 more sites of resorption on average than teeth moved intermittently with a stainless steel wire (P< 0.001). Additionally, the perimeter, area, and volume of resorption of the roots were 140% greater with the teeth moved by superelastic wire compared to the steel wire (P<0.001).
Evidence Search continuous[All Fields] AND discontinuous[All Fields] OR dissipating[All Fields] OR Intermittent[All Fields] AND force[All Fields] AND ("orthodontics"[MeSH Terms] OR "orthodontics"[All Fields]) AND ("root resorption"[MeSH Terms] OR ("root"[All Fields] AND "resorption"[All Fields]) OR "root resorption"[All Fields])
Comments on
The Evidence
These clinical trials together encompassed a total of 43 patients between the ages of 10 and 23 years, and each trial reached the same conclusion. All of these studies were split-mouth designs in which patients served as their own controls. The amount of root resorption was calculated topographically after the teeth were extracted.
Applicability In patients where significant root resorption has occurred due to orthodontic treatment, superelastic wires should be avoided and alternatives such as steel wires or Invisalign, which utilize intermittent orthodontic forces, should be selected.
Specialty/Discipline (General Dentistry) (Orthodontics) (Pediatric Dentistry)
Keywords Root resorption; continuous forces; intermittent forces
ID# 2984
Date of submission: 02/29/2016spacer
E-mail oldhamm@livemail.uthscsa.edu
Author Maxwell Oldham
Co-author(s) Kristen Self
Co-author(s) e-mail SELFK@livemail.uthscsa.edu
Faculty mentor/Co-author Clarence C. Bryk, DDS, MS
Faculty mentor/Co-author e-mail brykc@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
post a rationale
by Kristen Self (San Antonio, TX) on 09/19/2017
When a force is applied to a tooth, the periodontal ligament (PDL) is compressed resulting in a reduction of blood flow in the PDL. If the force applied is sustained at a magnitude where the blood vessels are not completely occluded, chemical messengers are released that stimulate both osteoclastic and osteoblastic activity. These bone-resorbing and bone-forming cells are responsible for tooth movement through the alveolar bone (Proffit, p. 283). Acar suggests that intermittent forces can provide “rest periods” to help repair sites of resorbed alveolar bone when compared to continuous forces applied to teeth (publication PMID: 10227557). Providing orthodontic treatment with intermittent forces could help decrease root resorption in comparison to continuous forces. Proffit, William R., Henry W. Fields, and David M. Sarver. Contemporary Orthodontics. St. Louis, MO: Elsevier/Mosby, 2013.
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