Dr Nicola Parkin BOSF Grant 2004

Surgical exposure of palatally displaced canines (PDC). A randomised clinical trial.

Primary investigator

Nicola Parkin (Thumbnail)
Dr Nicola Parkin (Sheffield)

Secondary investigators

Philip Benson (Sheffield), Ann Marie Smith (Derby), David Tinsley (Chesterfield), Richard Milner (Sheffield)

Principle Research Question

Is there any difference in the periodontal health of orthodontically aligned ectopic canines that have been exposed with an open (left) versus a closed technique (right)?

Parkin open exposureParkin closed exposure

Other outcomes

Economic: Is one technique more expensive?
Patient response: Which technique causes the least discomfort to the patient?


We began this research project in the summer of 2003. Owing to a number of ‘teething’ problems, for example surgical colleagues confusing open with closed techniques, our original sample size target has had to increase substantially! By December 2006 we recruited 81 patients, this allowed compensation for incorrect surgery, failure to diagnose PDC and drop outs. Forty-one participants were allocated to open exposure and forty to closed exposure. Some patients are taking much longer than others to treat (one patient took 50 months!) and we still have 7 patients in active treatment.


We are assessing periodontal outcome clinically, with photographs, study models and radiographs.

My periodontal colleagues assure me that all the patients are especially impressed with the Williams pressure sensitive periodontal probes that we are using. (It is a problem getting patients back in to carry out these measurements, the Williams pressure sensitive probe could be one reason, especially for those participants with gingival inflammation!)

We are taking study model records at 3 months post debond and 1 year post debond. Records appointments generally take approximately 90 minutes (30 minutes in the dental chair and 60 minutes in ‘our very busy’ xray department). Financial remuneration has helped ensure attendance at these appointments.

I am just beginning to measure the study models. I am looking at gingival recession, width of attached gingivae and position of canines. One of the things I am finding out is that retention of PDC is extremely important, particularly for the 1 year post debond visit.


PARKIN N, DEERY C, SMITH AM, TINSLEY D, SANDLER J, BENSON PE. No difference in surgical outcomes between open and closed exposure of palatally displaced maxillary canines. J Oral Maxillofac Surg. 2012 Sep; 70(9): 2026-34

PARKIN N & BENSON P. Current ideas on the management of palatally displaced canines: Faculty Dental Journal January 2011, Volume 2, Issue 1

PARKIN, N. (2009) Clarifying points. Br Dent J, 207, 567-8.

PARKIN, N., BENSON, P. E., SHAH, A., THIND, B., MARSHMAN, Z., GLENROY, G. & DYER, F. (2009a) Extraction of primary (baby) teeth for unerupted palatally displaced permanent canine teeth in children. Cochrane Database Syst Rev, CD004621.

PARKIN, N., BENSON, P. E., THIND, B. & SHAH, A. (2008) Open versus closed surgical exposure of canine teeth that are displaced in the roof of the mouth. Cochrane Database Syst Rev, CD006966.

PARKIN et al: Periodontal health between palatally displaced canines treated with either an Open or Closed surgical technique in young peope undergoing fixed orthodontic treatment: A multi-centre randomized controlled trial. In press: American Journal of Orthodontics & Dentofacial Orthopedics

PARKIN N, FURNESS S, SHAH A, THIND B, MARSHMAN Z, GLENROY G, DYER F, BENSON PE. Extraction of primary (baby) teeth for unerupted palatally displaced permanent canine teeth in children. Update, Cochrane Database Syst Rev. 2012 Dec

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