Bonding and composite veneers

What are bonding and composite veneers?

Bonding is an aesthetic procedure in which composite resin, a tooth-coloured filling material, is bonded to the tooth, then shaped by hand and hardened directly in the mouth. When done for small corrections it is called "bonding"; when the entire front surface of the tooth is covered, it is called a "composite veneer" or "direct composite veneer".

Composite resin can be applied directly in the mouth without being sent to a laboratory. Because of this, it is often completed in a single session, and the dentist can adjust the shape, colour and length step by step together with the patient.

Its most important feature is that it is tissue-preserving. A laboratory comparison reported that preparations for porcelain veneers removed more tooth structure than preparations for direct composite veneers (Source 4). In many cases, bonding can be applied without any tooth preparation at all.

Who is it suitable for, and who is it not suitable for?

Bonding is suitable for small chips, gaps, mild shape irregularities, length differences and limited colour issues in front teeth. It is often preferred by patients who want a reversible solution, by younger patients whose teeth are still developing, or by those who want to try out a change before moving to a permanent treatment.

Bonding may have limitations in cases of severe teeth clenching, in very dark teeth where full colour masking is expected, and in fractures where a large part of the tooth has been lost. The risk is also higher in root-filled teeth: one clinical study found an annual failure rate of 4.9% for direct composite veneers on vital teeth, compared with 9.8% on root-filled teeth (Source 2).

Direct composite or laboratory-made composite?

Composite veneers can be made directly in the mouth or prepared indirectly in a laboratory from an impression. Direct application is completed in a single session, requires the least preparation, and allows the dentist to adjust the shape in the mouth. Laboratory-made composite can provide a more controlled shape and surface, but requires an additional session and usually somewhat more preparation. The choice between the two depends on the number of teeth, the complexity of the correction and the bite. In both cases, the composite's discolouration and wear characteristics are similar, and regular polishing is needed.

Treatment steps

1. Examination and planning: The teeth, gums, bite and any teeth clenching are assessed. For multiple teeth, the target shape can be designed in advance.
2. Shade selection: The colour and layers of the composite are chosen in natural tooth light. If whitening is planned, it is usually done first, and time is allowed for the shade to settle.
3. Surface preparation: The tooth surface is cleaned; very limited preparation is done if needed. The surface is made ready for bonding.
4. Layered application: The composite is placed in layers, shaped and hardened with light.
5. Finishing and polishing: The final shape is refined and the surface is polished.
6. Bite check: It is checked that the restoration is not overloaded during biting and jaw movements.

How long does it take?

Bonding is usually completed in a single session; when several teeth are covered with composite veneers, 1-2 sessions may be needed. The duration depends on the number of teeth and the scope of the correction.

If preliminary steps such as whitening, gum treatment or orthodontics are needed, the total time is longer. Finishing and polishing can also be planned as part of a follow-up check-up.

Risks and limitations

The main issues with composite resin are fracture, discolouration at the margins, loss of surface gloss and wear. A systematic review of composite restorations in front teeth found annual failure rates between 0% and 4.1%, with tooth or restoration fracture as the most common cause of failure (Source 1). The same review noted that aesthetic-related failures were more common in restorations done for aesthetic reasons.

A retrospective study found an overall survival rate of approximately 80% for direct composite veneers over an average of 3.5 years of use, with fracture as the most common cause of failure (Source 2). Teeth clenching and biting hard objects increase this risk.

The colour of composite resin does not lighten with whitening. For this reason, if whitening is done in the future, the composite restorations may need to be renewed.

The success of the composite also depends on keeping the bonding area free from moisture and saliva during the procedure. Correct hardening of the layers and careful final polishing affect the surface's resistance to discolouration and plaque accumulation. Fine colour lines that may develop at the margins over time can often be corrected with polishing; if they become deeper, that section needs to be renewed.

Alternatives

A randomised study found ten-year results in favour of porcelain veneers: the survival rate was 75% for indirect composite veneers and 100% for porcelain veneers; however, the study included only 48 restorations (Source 3). For the porcelain option, you can see the porcelain laminate veneer page.

Care and longevity

Composite restorations are brushed and flossed like natural teeth. Tea, coffee and smoking can increase discolouration. Avoiding biting hard objects and using an occlusal splint (night guard) if there is teeth clenching reduces the risk of fracture.

At check-ups, the surface can be polished, and small chips and marginal discolouration can be repaired. This is an important advantage of composite resin: it is often possible to maintain the restoration without renewing it entirely. If you are planning to lighten the shade, you can see the teeth whitening page.

Clinical data on longevity show a wide range, and no personal duration can be promised. In general, it is accepted that composite resin requires more frequent care and renewal than porcelain.

If there is teeth clenching, the cutting edges and corners of the composite are more prone to wear and fracture. In this case, adjusting the bite and using an occlusal splint (night guard) should be considered as part of the care plan.

From a prosthodontist's perspective

From a prosthodontist's point of view, bonding is both a treatment in itself and a decision-making tool. Because it is reversible, it can allow the patient to try out the new tooth length and shape in daily life before moving to a permanent restoration.

The main criteria assessed include: the size of the correction, teeth clenching and bite, the vitality of the tooth, the need for colour masking, and how much time the patient can devote to regular care and polishing. For small to moderate corrections, especially in younger patients, discussing bonding first as the least invasive option is a tissue-preserving approach.

To evaluate the options together, you can see the who is a veneer suitable for article. A definite decision on the option suitable for you is made after an examination and, if needed, radiographic assessment.