The short answer to whether composite bonding can be whitened is generally no. Composite dental bonding uses a tooth-colored material, consisting of a plastic resin matrix mixed with glass filler particles, to repair chips, close gaps, or cover stains. This synthetic material is color-matched to the patient’s teeth during placement, providing an aesthetic repair. Unlike natural tooth structure, however, composite resin does not react to the chemical agents used in traditional teeth whitening treatments.
Why Composite Material Resists Whitening
The reason composite material resists whitening is the fundamental difference between its composition and natural tooth enamel. Natural enamel is a porous, crystalline structure that allows whitening agents, typically hydrogen or carbamide peroxide, to penetrate its microscopic channels. These agents work by releasing highly reactive oxygen molecules that penetrate the enamel and dentin to break down the molecular bonds causing deep-set stains, effectively bleaching the tooth structure.
Composite resin, conversely, is a dense, non-porous polymer matrix. This material is chemically stable and lacks the fine network of pores necessary for peroxide molecules to enter and initiate the oxidation reaction. Since the whitening gel cannot penetrate the material’s solid structure, the pigments within the synthetic resin remain unaffected by the chemical process. The color of the bonding material is permanently set once cured, and traditional bleaching treatments have no effect on its shade.
The resin matrix is reinforced with inorganic fillers such as silica or glass particles, designed for durability and a smooth surface finish. This structure prevents the absorption and chemical interaction required for whitening. While professional polishing can remove extrinsic surface staining on the composite, this physical process only addresses discoloration on the surface, not the internal color of the material.
The Aesthetic Problem: Color Mismatch
When a person with existing composite bonding undergoes a whitening procedure, the inevitable outcome is an aesthetic color mismatch. The natural tooth structure surrounding the restoration will lighten noticeably due to the peroxide’s oxidative action. However, the composite bonding material retains its original color, which was matched to the tooth’s pre-whitening shade.
This difference often makes the bonding appear darker or more yellow compared to the newly brightened natural teeth. Even if the bonding covers only a small chip, the contrast can make the restoration highly visible. This issue is compounded because composite resin can absorb surface stains over time from pigmented foods and beverages. An older, stained bonding material will look even more out of place once the adjacent enamel has been whitened, creating a non-uniform result.
Achieving a Whiter Smile When You Have Bonding
Achieving a uniformly whiter smile when composite bonding is present requires a specific two-step professional protocol. The only effective way to integrate a color change is to whiten the natural teeth first, and then replace the existing composite material. The initial step involves undergoing the full teeth whitening treatment until the desired shade is achieved. It is important to note that the current bonding will appear darker during this phase.
After the final whitening session, the dentist must wait approximately two weeks before placing the new bonding material. This waiting period is necessary for two scientific reasons. First, it allows the freshly whitened tooth color to stabilize and reach its final, settled shade. Second, it ensures the dissipation of residual oxygen from the peroxide within the tooth structure. Peroxide can temporarily compromise the strength of the bond between the new resin and the tooth enamel, so allowing it to fully dissipate ensures a durable and strong restoration.
Once the two-week period has passed, the dentist removes the old composite bonding and places a new layer of resin precisely matched to the new, lighter color of the natural teeth.
Professional Repolishing
For minor surface discoloration on existing bonding that is structurally sound, a dentist may use professional re-polishing techniques. This procedure removes only extrinsic stains accumulated on the resin surface, which can restore the restoration to its original shade. It cannot, however, make the material lighter than it was when first placed. Maintaining the color of the new bonding requires diligent oral hygiene and minimizing consumption of highly staining agents.