A long term evaluation of permanent bonded retention after treatment with fixed orthodontic appliances

Research Doctorate - Doctor of Philosophy (PhD)In 2004 and again in 2009, the Cochrane collaboration reviewed orthodontic clinical practice on retention. The review found; “there are insufficient data on which to base our clinical practice on retention at present”. The Aims of this study were two; the first was to review the effectiveness, durability and dental health impacts of bonded retainers (BRs) that have been in place for more than 15 years. The second was to discover the opinions of dentists and patients on comparing BRs to removable retainers (RRs). Method This was a 15 year retrospective study which reviewed 61 patients who had undergone conventional fixed appliance treatment with the chief researcher (CR) prior to 1993. Study sample size calculations required 44 BR study group and 44 RR control group patients for a valid analysis. Overall, 46 patients had experience with 55 BRs and 43 had experience with 55 RRs; 28 patients had worn both a BR and a RR at the same time and were thereby included as paired observations in both groups. All 61 participants completed a specifically designed questionnaire relative to their orthodontic treatment experience. They also underwent a clinical examination, had a series of intra-oral and extra-oral digital images and an OPG radiograph taken. Seventy one dentists who had referred patients to the CR over the previous 25 years were sent a confidential questionnaire; to be completed anonymously for their opinions on RRs and BRs. Statistical analyses were carried out using SPSS V16 (2008) and statistical significance was set at the 0.05 level. A Newcastle University statistician worked with the CR in analysing the results and compared them with those of four independent specialist examiners using Bland- Altman plots and Spearman’s rank correlation coefficient (SCC) analyses. Results The CR’s measures were found to be reliable and valid. After 15 years, the BRs were 100% effective at maintaining acceptable alignment while 53% of the control group had unacceptable alignment. The BRs had a unit composite bond/wire fracture rate of 0.58% per annum. The BRs did not produce any clinically significant negative dental health impacts. The majority of patients and dentists rated BRs as superior to RRs. Conclusions After 15 years, BRs were found to be adequately durable, effective at stabilising the anterior dentition and they did not produce adverse dental health effects. The majority of patients felt BRs improved their quality of life