Study demonstrates safe removal of mini implants after orthodontic treatment

Question: What complications are known to arise with the removal of mini-implants after orthodontic treatment?
Seong-Hun Kim: Usually, complications in mini-implant removal after orthodontic treatment are rare. Infection in the removed area can occur in patients with severe periodontal disease or heavy smokers. Cases with long-term retention of mini implants have demonstrated a prevalence of deformation or fracture, and difficulty in removal particularly in the mandibular area due to osseointegration. 

  Left: Mini-implant fracture after removal.   
  







  Left: Mini screw deformation during removal.
  


Question: What are the most significant outcomes of your research?
 Seong-Hun Kim: The potential for partial osseointegration of the mini-implant was clarified through this study.  The stability and safety of these types of mini-implants were shown as removal torque value. Although this is a known fact, it is nevertheless valid to present successful examples of this type of partially osseointegrated mini-implant (C-implant), as a viable treatment option for the clinician. Another distinction is the C-implant allows rotational moment to be applied to the device, which is not advisable with a conventional self-drilling miniscrew.
The limits of clinical application of the osseointegrated implants (caused by lengthy healing duration, large size, and difficult removal) were overcome using this type of mini implant (1.8mm in diameter and 8.5mm in length).

Question: How do you hope your research will affect future treatment strategies using mini-implants for orthodontic procedures?
Seong-Hun Kim: Mini-implants can be used as independent appliances for orthodontic treatment due to the potential for osseointegration. Partially osseointegrated mini-implants offer different treatment mechanics, high stability and resistance to rotation. The authors developed a new treatment system, called Biocreative therapy, to implement independent en masse retraction of the anterior teeth without unnecessarily extending orthodontic appliances to posterior segments during the retraction period. This concept developed from the fact that partially osseointegrated mini-implants or plates can easily endure multidirectional heavy forces even when they support orthodontic archwires. Orthodontists can now consider the mini-implant with dependent en masse retraction without assistance of posterior bonded or banded appliances in cases of maximum anchorage, periodontal disease or compromised dentition, and systemic disease patients.

A       B       C

Figure A: Biocreative therapy for Class I bidentoalveolar protrusion correction before treatment.
Figure B: During upper and lower mass retraction without bonded or banded posterior appliances.
Figure C: Final stage of treatment - with no complications.
 
Question: Your conclusion states: “A nonloading period of less than 6 months before removal is recommended to prevent complications” – why is this the recommendation?
Seong-Hun Kim: In my clinical experience, C-implants endured over 40Ncm removal torque value without difficulty during removal. However, the larger RTV associated with longer periods of delay after removal of forces suggested that there was increased osseointegration; nevertheless, there was no deformation or fracture of the SLA mini-implant or bone damage on removal. All SLA mini-implants used in this study resisted the removal torque, so they remained securely fastened throughout the test period. From an orthodontic point of view, osseointegration is a double-edged sword. The value of osseointegration must not disturb the removal of the mini-implant, because it has to have the characteristics of a temporary anchorage device for a limited period. Therefore, we recommended a non-loading period of less than 6 months before removal to prevent possible complications.

Question: Will you conduct further research on this topic?
Seong-Hun Kim: The authors have over 8 years’ clinical experience and data on C-implant, and we are also trying to find out the effective treatment philosophy in implant orthodontics for our orthodontic patients. First of all, we are preparing some research articles on the treatment effect of biocreative therapy using partially osseointegrated mini implants using lateral cephalograms and CBCT. Secondly, we are performing continuous research on the effects of different surface characteristics of mini-implants using SEM study, animal experiments and human research simultaneously. Thirdly, we are focusing on the risk factors and solutions in implant orthodontics with clinicians worldwide. I hope to share more information with many enthusiastic researchers in this field.

Lastly, I would like to quote some sentences from the 'letters to the editor section' which were published in AJODO in December 2007.
“Scientific technology has developed at an unprecedented pace. Also, it has affected orthodontic treatment mechanics dramatically. We are proud of our involvement in developing and evaluating a new era of orthodontics— osseointegrationbased mini-implants and related treatment mechanics….”
 

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Full article
'Removal torque values of surface-treated mini-implants after loading'
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 134, Issue 1, July 2008, Pages 36-43