Title High Orthodontic Force Levels May Increase Root Resorption in Young Patients with Open Apexes But More Studies Specific For This Population Are Needed
Clinical Question In young patients with open apex undergoing orthodontic treatment, does the application of low orthodontic forces reduce the severity of root resorption compared to application of high orthodontic forces?
Clinical Bottom Line Multiple studies showed that higher orthodontic forces significantly increased root resorption, particularly in patients with fixed appliances. The impact of lower forces was mixed. Villaman-Santacruz, et al., did not show any difference, while some studies reported reduced resorption, and others, like the Hansson study, showed increased resorption and buccal bone loss, depending on the appliance type used. The intensity of the force applied and type of appliance all play critical roles in the extent of root resorption. More studies specific to young patients with open apexes are needed to support strong recommendations.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
36206494Villaman-Santacruz (2022)Patients undergoing orthodontic treatmentMeta-Analysis
Key resultsThere was no significant difference in external root resorption in self-ligating (lower forces) or the use of conventional appliances (higher forces). This review did not specifically focus on low forces in young patients with apexes, limiting its direct applicability to this PICO question. Additionally, the lack of significant difference could be explained by moderate to high risk of bias present in the studies reviewed, including variability in study designs, assessment methods and sample sizes.
33215186Yassir (2021)8-18-year old patients undergoing orthodontic treatmentSystematic review
Key resultsThis systematic review found that 30% of patients treated with high force fixed appliances experienced root resorption, with an average resorption of 2-3mm. The review also found that lower force treatments were underexplored, and as a result, there was insufficient evidence to determine whether the difference between high and low force was statistically or clinically significant. The broad age range of included patients (8-18 years) further complicates its relevance for this PICO question.
39230018Hansson (2024)42 children with unilateral posterior crossbite, with a mean age of 9.5 years.Randomized Controlled Trial
Key resultsRapid maxillary expansion (RME), which applied higher forces, successfully opened the mid palatal suture, while quad helix (QH), which applied lower forces, did not. The QH group also showed significantly more buccal bone loss and root resorption immediately after treatment (P < 0.001 for bone loss and P = 0.013 for root resorption). However, these differences were no longer statistically significant at the 1 year follow up (P = 0.11 for bone fenestrations and P = 0.22 for root resorption). Clinically, the immediate adverse effects were more pronounced in the QH group, but long-term effects were similar between both groups.
36206494Bhatia (2024)50 patients with class l malocclusion and moderate to severe anterior crowding.Randomized Controlled Trial
Key resultsHigh force treatments caused significantly more root resorption than low force treatments (resorption depth averaging 2.18 ± 0.30 mm vs. 1.47 ± 0.24 mm for low forces (p < 0.001). Both NiTi and CuNiTi archwires caused slight but clinically significant root resorption in lower anterior incisors, with more pronounced resorption in the mandibular right central incisor in the NiTi group (P < 0.01).
Evidence Search Root resorption factors, Open palatal suture with appliances, heavy orthodontics forces.
Comments on
The Evidence		 The evidence provided by systematic reviews and RCTs presents a broad but somewhat conflicting perspective on the relationship between orthodontic forces and root resorption. While Bhatia (2024) shows that even low forces can cause slight root resorption (1-2mm), Yassir (2021) only highlights the increased incidence of severe root resorption in high force treatments (30% of patients). The difference between these findings is likely due to study design differences (fixed vs removable appliances, patients age, treatment duration) and sample sizes. Additionally, the Hansson study (2024) presents a unique discrepancy, as it shows that low forces (quad helix) resulted in increased root resorption and buccal bone loss. This is due to the type of appliance used, as the quad helix distributes forces differently than other appliances like archwires. The Villaman-Santacruz (2022) systematic review further underscores the variability in patient response to treatment, reflecting the need for more focused studies on younger patients with open apexes. More research is needed with larger sample sizes targeting this population to establish clear guidelines.
Applicability The findings are generally applicable to young patients with open apexes, although the variability in patients ages and appliances across the studies limits the strength of the recommendations. The evidence suggests that lower forces may reduce the likelihood of root resorption in this population, but more high-quality trials focused specifically on young patients with open apexes are needed to confirm these findings.
Specialty (General Dentistry) (Orthodontics)
Keywords Heavy orthodontics forces, types of appliances
ID# 3568
Date of submission 10/21/2024
E-mail alsabee@livemail.uthscsa.edu
Author ABDULAZIZ A H S H ALSABEE
Co-author(s) Gloria Verde Gaffaro
Co-author(s) e-mail Verdegaffaro@uthscs.edu
Faculty mentor Kyumin Whang
Faculty mentor e-mail whang@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?)
None available
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Comments and Evidence-Based Updates on the CAT
(FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs)
None available