Hawley and clear overlay retainers have similar survival times

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Having to wear a retainer following orthodontic treatment is almost universal.  The aim of this study was to compare the survival time of the Hawley retainer (HR) and the clear overlay retainer (COR) over one-year follow-up and to analyze risk factors contributing to their breakage.

120 adolescent  patients were randomised to receive either a HR  or COR.  Information on breakage dates , reasons for breakage and the broken parts of the retainers were recorded. A survival analysis was used to describe retainer survival over time.

They found

  • No significant difference in the survival times between the two groups for mandibular or maxillary retainers.
  • While both retainers tended to fracture the locations of the fractures was different.

The authors concluded

…our analysis suggests that the survival times of the HRs and CORs were not statistically significantly different. Therefore, clinicians could advise their patients to wear either of the two retainers without taking breakage into consideration.

Sun J, Yu YC, Liu MY, Chen L, Li HW, Zhang L, Zhou Y, Ao D, Tao R, Lai WL.  Survival time comparison between Hawley and clear overlay retainers: a randomized trial. J Dent Res. 2011 Oct;90(10):1197-201. Epub 2011 Jul 19. PubMed PMID: 21771797.


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Derek Richards

Derek Richards is a specialist in dental public health, Director of the Centre for Evidence-Based Dentistry and Specialist Advisor to the Scottish Dental Clinical Effectiveness Programme (SDCEP) Development Team. He is a former editor of the Evidence-Based Dentistry Journal, the chief blogger for the Dental Elf website and a past president of the British Association for the Study of Community Dentistry. He has been involved with a wide range of evidence-based initiatives both nationally and internationally since 1994. Retired from the NHS he is currently a part-time senior lecturer at Dundee Dental School.

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