Title There Is No Difference in the Failure Risk of Fixed Mandibular Retainers When Bonded via Direct or Indirect Methods
Clinical Question In orthodontic patients, will direct bonding compared to indirect bonding of fixed lingual retainers result in lower failure rates?
Clinical Bottom Line In orthodontic patients, there is no difference in the failure risk of fixed lingual retainers when using the direct method compared to the indirect method. This is based on a single-center randomized controlled trial of 64 patients.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
25432250Bovali/201464 post-orthodontically treated patients Randomized Controlled Trial
Key resultsAt the 6-month post-placement interval, the failure rate was 32% using the indirect bonding method and 24% using the direct technique (Log rank test, P=0.35; test of proportions: risk difference = 0.08; 95% CI, -0.15 to 0.31; P=0.49).
28024770Egli/201764 post-orthodontically treated patientsRandomized Controlled Trial
Key resultsAfter two years post-placement, the failure rate was 43% using the indirect bonding method and 37% using the direct technique (Log rank test, P=0.64; Hazard ratio = 1.26; 95% CI, 0.56 to 2.81; P=0.58)
Evidence Search (((((direct bonding) AND indirect bonding) AND orthodontic retainers) AND failure))
Comments on
The Evidence
Validity: Both studies were randomized controlled studies and thus provide weaker evidence than a systematic review or a meta-analysis. The strengths of the studies include all retainers being bonded by the same operator and fabricated by the same lab technician. Additionally, the studies were completed in a single center, which allowed control of baseline characteristics. Although there was blinding of the investigator during clinical assessment, one major limitation of the studies was that there was no blinding of the operator or patients. Furthermore, other factors that may influence failure rates of retainers, such as diet, chewing, and parafunctional habits, were not investigated. Perspective: Based on these studies, providers should feel confident using either bonding method when placing fixed lingual retainers due to their similar failure risk. However, these studies did not address or compare the time and cost associated between the direct versus indirect bonding methods. This is an important consideration that needs to be explored, especially since a large majority of orthodontists are trying to run an efficient and economically viable private practice.
Applicability Long-term retention is critical for maintaining teeth in optimal esthetic and functional position in every orthodontic patient after treatment. Fixed lingual retainers can provide the necessary retention and are the most commonly used due to their numerous advantages, including better esthetics, no need for patient compliance, and effectiveness. Based on the results of these studies, there is no significant difference in failure risk after two years whether the provider uses an indirect or direct method when bonding these appliances. However, further studies will be needed to evaluate the risk of failure when providers use various bonding materials, wire types and sizes over a longer period of time.
Specialty (General Dentistry) (Orthodontics)
Keywords Direct bonding, Indirect bonding, Orthodontics, Retainers, Failure
ID# 3440
Date of submission 11/23/2020
E-mail Walkera2@livemail.uthscsa.edu
Author Addison Walker, DMD
Co-author(s) Simi Mathur, DDS
Co-author(s) e-mail mathurs1@livemail.uthscsa.edu
Faculty mentor Dr. Ravikumar Anthony, BDS, MDS, MS
Faculty mentor e-mail anthonyr@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
Comments and Evidence-Based Updates on the CAT
None available