Whitening May be Harmful to Biofilm Build-up on Restored Teeth
A new study has revealed that whitening may prevent biofilm build-up on restored teeth. Restorations bleached with 35% hydrogen peroxide and 15% carbamide peroxide had significantly lower biofilm levels than those left untreated. Researchers from Iran studied whether whitening affects biofilm formation and surface roughness of these materials.
What They Found…
The lead author on the study, Mahmoud Bahari, DDS, MSD, from Tabriz Medical Science University in Tabriz, Iran, had this to share:
“Knowledge about the effect of bleaching on the behavior of composite resins is important to find a suitable composite resin for the restoration of teeth undergoing bleaching,”
Mahmoud further went on to say:
“This study aimed to assess the effect of different bleaching protocols on surface roughness and biofilm formation on a silorane-based composite resin.”
The Effects of Bleaching on Biofilm
According to Mahmoud Bahari, DDS, MSD, and his colleagues:
“One major cause of the reduction in biofilm formation in the bleached groups may be the antibacterial effects of the bleaching agents.” Researchers of the current study investigated whether three common tooth bleaching regimens increased surface roughness or biofilm formation on 60 restoration models. Previous studies have suggested that bleaching may increase surface roughness, which is a risk factor for biofilm formation.
These composite models were divided into four groups:
- Control: Unbleached composite samples stored in distilled water for two weeks.
- CP: Samples bleached with 15% carbamide peroxide for two hours per day for two weeks.
- HP: Samples bleached with 35% hydrogen peroxide for 30 minutes every three to five days for two weeks.
- Light-activated HP: Samples bleached with 35% hydrogen peroxide activated by an LED light for 40 minutes; bleaching occurred one time, as specified by manufacturer recommendation.
They also found that all three restoration groups exposed to bleaching had significantly less biofilm formation than the control group. The two groups, in particular with hydrogen peroxide, fared better than the carbamide peroxide group, and the light-cured hydrogen peroxide restorations performed above the rest overall.
Moreover, the study did not indicate any significant differences in surface roughness among the groups. On that note, the following was said by one of the researchers:
“Some previous studies have shown that [hydrogen-peroxide]-based bleaching agents have bactericidal properties.”
Additional Research About Biofilm Build-up Indicates
One key limitation of the research is that it was conducted as an in vitro study and is not necessarily representative of clinical scenarios. More studies are needed to verify the findings, the authors noted.
Nevertheless, the results were significant and indicate that tooth bleaching may reduce biofilm formation for at least some types of restorations.
“Bleaching decreased biofilm formation,” the authors concluded. “The lowest biofilm formation was noted in the group subjected to light-activated 35% peroxide.”
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