Insertion torque recordings for the diagnosis of contact between orthodontic mini-implants and dental roots: a systematic review

Abstract

BackgroundMost orthodontic mini-implants (OMIs) are inserted between dental roots. The prevalence of contacting these structures is high. Such contacts can cause permanent root damage and implant instability. Increased torque levels during implant insertion (the index test) could be a more accurate and immediate measure for diagnosing implant-root contact (the target condition) than radiographs (the reference standard) and could ultimately lead to a reduction or elimination of X-ray exposure. To address this issue, we asked three questions: (1) whether OMIs with root contact had higher insertion torque values than those without, (2) what is the accuracy of the index test compared with the reference standard to diagnose the target condition and what are the adverse effects of the index test, and (3) whether intermediate torque values have clinical diagnostic utility.MethodsMethods were conducted according to our published protocol, which was based on the PRISMA-P 2015 statement. We applied broad spectrum eligibility criteria that included randomized and non-randomized studies on clinical, animal, and cadaver models. Not including such models would be unethical because it could slow down knowledge creation on the adverse effects of implant insertion. We conducted searches in more than 40 electronic databases including MEDLINE and 10 journals were hand-searched. Grey literature and reference lists were also searched. All research procedures were conducted independently by three reviewers. Authors of selected studies were contacted to obtain additional information. Outcomes on the three different research models were analysed separately. Systematic error was assessed with the Cochrane ‘Risk of bias tool’ for non-randomized studies.ResultsOne clinical, two animal, and two cadaver studies fulfilled the eligibility criteria of the first research question. All studies and subgroups demonstrated higher insertion torque values for OMIs with the target condition than those without. Mean differences (MD) between these effect estimates were statistically significant in one beagle model (MD, 4.64; 95 % CI, 3.50 to 5.79) and three subgroups of cadaver studies (MD, 2.70; 95 % CI, 1.42 to 3.98) (MD, 3.97; 95 % CI, 2.17 to 5.78) (MD, 0.93; 95 % CI, 0.67 to 1.20). Highest mean differences were identified in most self-drilling compared with pre-drilling groups. Clinical heterogeneity between studies was high, and many items were underreported. All studies except one cadaver study scored at least one domain as ‘serious risk’ of bias. No studies addressed the second research question. One cadaver study addressed the third question which showed the importance of recording torque levels during the entire implant insertion process. Responses of contacted authors were helpful, but often difficult to obtain. Implants fractured in one animal and in one cadaver model.ConclusionsAll eligible studies scored higher insertion torque values for implants with root contact than those without, but none of these studies assessed the diagnostic accura...

Revisiting the Complications of Orthodontic Miniscrew

“…Insertion torque with root contact was proved to be higher than those without and in agreement with many studies [ 22 ]. One study showed that the average placement torques in contact cases were twice higher than those in noncontact cases [ 20 ].…”

Comparative Evaluation of Primary Stability of Two Different Types of Orthodontic Mini-Implants

“…Therefore, torque levels should be recorded during the entire process of mini-implant insertion. [ 17 ]…”

Maximum insertion torque loss after miniscrew placement in orthodontic patients: A randomized controlled trial

“…It is known that insertion torque values do not result in predictions for long‐term stability, 17 and the present study found no association between baseline torque values and success. However, reference values may help to assess as a diagnostic test for root contact (a previously published study showed that miniscrews with root contact have different insertion torque values compared with those without) 33 and have less adverse effects than radiographic images 34 …”