Dear members of the Jordan Orthodontic Society,

 This is my first blog and in the spirit of making it both interesting and informative, I will be using a format similar to that used by Professor Kevin O’Brien.

For the next few months I will be scanning papers in The Angle Orthodontist and selecting the ones I find of clinical and practical significance.

This month I will be featuring a study conducted at the University of Malay in Malaysia. The paper is entitled “Mini-implant supported canine retraction with micro-osteoperforation: A split-mouth randomized clinical trial” Angle Orthodontist, Vol 89, No 2, 2019

What did the researchers do?

They wanted to test whether using micro-osteoperforations  (MPO) by inserting and removing TAD’s in the extraction site of the first premolar had an effect on the speed of canine retraction. The control was the contralateral side on the same patient. Canine retraction was measured at 4 week intervals to the nearest 0.01mm over a 16 week interval.

 Postoperative pain and the impact of this pain on daily function was also evaluated for each subject using a self-administered questionnaire.

A proper sample size calculation was carried out based on a clinically relevant difference of 0.84 mm per month.

How did they do it?

 The sample consisted of 30 patients with maximum anchorage requirements. Canines were retracted using 1.6-mm diameter mini-implants placed in a buccal position between the first permanent molar and second premolar and ligated directly to the first molar for anchorage. Similar bracket prescriptions, arch wire sequences and methods of retraction of the canines was used in all cases.

Three MPO’s were placed by inserting and removing TAD’s at 3 locations adjacent to the extraction site in a vertical direction 2 mm apart and 3 mm in depth. The sample was further subdivided into 3 groups and MPO’s were repeated at 4, 8, and 12 wks.

What were their main findings?

MOP was associated with statistically significantly increased overall canine retraction of 1.1 mm over the 16-week period of observation.

There were only small differences in tooth movement when intervals of 4, 8, and 12 week MOP were used.

Moderate pain was associated with MOP at 4-week intervals while only mild pain was perceived for intervals of 8 and 12 weeks.

What did I think?

This was a well-designed clinical study of clinical relevance to daily practice. The sample size calculation gave power to the study and all variable were controlled. However, the subdivision of the sample into 3 MOP groups weakened the study since there were only 10 subjects in each subgroup. This is a common mistake many researchers make when they are trying to investigate to many variables in a single study.

The statistically significant difference of 1.1 mm in unlikely to be of clinical significance and, in my opinion, is out weighed by the pain and extra surgical procedures that patients were subjected to.

In conclusion, I will not be placing MOP’s to aid canine retraction in my patients.

مقال الشهر