Enamel colour changes following whitening with 10 per cent carbamide peroxide: a comparison of orthodontically-bonded/debonded and untreated teeth

The purpose of this study was to determine if a colour difference exists be tween teeth that had orthodontic appliances bonded to and debonded from the m and untreated controls subjected to whitening with 10 per cent carbamide peroxide. The sample consisted of 20 pairs of first and second premolars ex tracted for orthodontic reasons. The contralateral surfaces were divided in to an experimental and control group. The experimental group underwent orth odontic bonding/debonding procedures. Both groups were subjected to 4 hour whitening and 20 hour hydration sessions for 30 days. The L*a*b* colour sys tem was chosen to evaluate any colour change and these changes were calcula ted by determining the AE from the L*a*b* values using a colorimeter. Colou r change readings were taken before and after each 4 hour whitening. Additi onal readings were taken at 48 hour intervals for 30 days following the ces sation of active whitening. The results were analysed using statistical (AN OVA) and graphical analyses (alpha = 0.05). A colour change difference of 2 CIELAB units was set as being clinically significant. A mean clinical colour difference was found for enamel surfaces subjected t o orthodontic bonding/debonding of attachments relative to control sites af ter whitening. Bonding and debonding procedures resulted in a significant c olour difference between orthodontic bonded and control sites at the end of the active period, which became insignificant at the end of the 30 day per iod of monitoring. Both the control and debonded sites responded to whiteni ng; however, the control sites responded initially to a greater extent; the orthodontic debonded sites did not respond until after 2 weeks of continuo us whitening. After the 2 week period the improved response of the debonded sites decreased the colour difference between the two groups.