Clinical Oral Investigations

, Volume 23, Issue 4, pp 1595–1604 | Cite as

Guided bone regeneration to reduce root migration after coronectomy of lower third molar: a randomized clinical trial

  • Yiu Yan LEUNGEmail author
Original Article



Root migration occurs after most third molar coronectomy and a portion may be exposed in the oral cavity. This study compared the root migration rate, surgical morbidities after third molar coronectomy with or without adjunctive guided bone regeneration (GBR).


A split-mouth randomized clinical trial was conducted on patients with bilateral lower third molars close to the inferior alveolar nerve. One side of the lower third molars was randomized to receive coronectomy with adjunctive GBR (study group) and the other side received coronectomy alone (control group). The cases were followed up for 2 years. Root migration, root exposure rate, surgical morbidities, and adjacent second molar periodontal regeneration were analyzed.


Forty-eight subjects (19 males, 29 females) with a mean age of 2.6 years (SD 5.8 years) were recruited. There was no root exposure in the review period. There were no statistical differences in pain and infection rate between the two groups at all time-points. The root migration was significantly less in the study group than the control group from 3 months onwards, and migrated only 1 mm (SD 1.3 mm) in 2 years (versus 3.5 mm (S.D.1.9 mm) in the control group). There were no differences in the periodontal attachment regeneration between the two groups.


Root migration in coronectomy with adjunctive GBR was less when compared with coronectomy alone, and with similar surgical morbidities and periodontal regeneration of adjacent second molars.

Clinical relevance

Minimal root migration occurred in coronectomy with adjunctive GBR. The chance of long-term (3 years or more) root exposure and the need of subsequent second operation to remove the exposed root would be reduced.


Coronectomy Guided bone regeneration Third molar surgery Randomized clinical trial 



The author would like to thank Ms. Natalie Wong and Dr. Karen Cheung for their help in this research.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Funding information

This project was funded by the Early Career Scheme of the Research Grnats Council, The Government of the Hong Kong Special Administrative Region (Grant code: HKU 788913M).

Ethical approval

Ethical approval was granted by the local Institutional Review Board of the University of Hong Kong and Hospital Authority Hong Kong West Cluster (IRB No. UW12-451).

Informed consent

Informed consent of the study was obtained from the recruited patients.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Oral and Maxillofacial Surgery, Faculty of DentistryThe University of Hong KongPok Fu LamHong Kong

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