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Tips and tricks for bonding in minimally invasive repair procedures

According to Dr Michał Jaczewski, the modification of composite restorations can be easy, provided that appropriate materials and techniques are used. (All images: Michał Jaczewski/Kuraray Noritake Dental)

Fri. 20. December 2024

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Resin composites are wonderful restorative materials. Besides allowing for minimally invasive, defect-oriented tooth preparation, they can be modelled as desired and modified and repaired whenever necessary. These qualities require a strong and long-lasting bond established either between enamel and dentine and the resin composite or between the existing and the newly applied composite material.

Universal adhesive

Being committed to keeping clinical procedures as simple as possible, I use an eighth-generation bonding agent in my dental office: CLEARFIL Universal Bond Quick (Kuraray Noritake Dental). Featuring rapid bond technology, it allows for straightforward use without the need for extensive rubbing or long waiting times, and the inclusion of the original MDP monomer in the formula enables it to bond well to various substrates, including enamel, dentine and resin composite.

Fig. 1: CLEARFIL Universal Bond Quick establishes a strong bond to dentine, enamel and old composite.

Fig. 1: CLEARFIL Universal Bond Quick establishes a strong bond to dentine, enamel and old composite.

Its composition and resulting versatility make CLEARFIL Universal Bond Quick the first choice for many indications, including non-invasive and minimally invasive repair procedures. Given that it works well in situations where a bond to dentine, enamel or old composite is required (Fig. 1), it is usually not necessary to remove the entire existing restoration that needs to be repaired or modified. Instead, preparation may be limited to the composite part, meaning that no additional tooth structure needs to be removed.

Clinical protocol

Depending on the condition of the existing restoration surface, the repair protocol may differ slightly. The basic steps are as follows.

Protocol when the oxygen inhibition layer is still on the surface:

  • No surface treatment is required, but rinse with water in case of contamination with blood or saliva, followed by air-drying and (optional) adhesive application.
  • Apply a new layer of composite immediately.

Protocol when the oxygen inhibition layer has already been removed from the composite surface:

  • Remove the composite around the defect and create a bevel at the cavity margin with rotating instruments.
  • Sandblast the surface with aluminium oxide particles.
  • Clean the composite surface with KATANA Cleaner (Kuraray Noritake Dental) or etch with phosphoric acid etchant.
  • If the composite surface is older than two weeks, etch with phosphoric acid etchant.
  • Apply the universal adhesive (which contains silane).
    – Apply a new layer of composite.

Clinical recommendations

Stay in the composite during preparation:

When an old composite restoration needs to be replaced—for example because the existing restoration shows discoloration or the patient has asked for a brighter shade—it is possible to remove only a part of the composite and leave the rest in place to save the underlying healthy tooth structure. Using ultraviolet (UV) light helps to accurately control the amount of material removed and the amount of material left in place. Under UV light, the composite is perfectly visible (Fig. 2), supporting highly conservative removal (Fig. 3).

Increase adhesion by sandblasting:

Sandblasting the affected composite area with aluminium oxide particles aims to create a clean, micro-retentive composite surface that is ideal for bonding (Fig. 4). The particle size I prefer is 27 μm. Residual particles may be removed with 37% phosphoric acid, which needs to be rinsed off thoroughly before air-drying the surface (Figs. 5 & 6).

Use a universal adhesive that contains silane:

When bonding to old composite, silanisation of the surface is recommended to increase the bond strength. On dentine, a separate silane shows no positive effect. Therefore, it is recommended to apply a separate silane to the composite surface only, a challenging task in situations with a surface consisting of tooth structure and composite. As CLEARFIL Universal Bond Quick contains silane, the separate silane application step may be skipped, simplifying the procedure (Figs. 7 & 8).

If in doubt, use a universal adhesive during repair procedures:

When detected during restoration, defects in the composite layer or air bubbles can be repaired or eliminated right away. If the oxygen inhibition layer is still present, another layer of composite may be applied immediately without any prior steps. However, if the surface has been contaminated by saliva or blood (Figs. 9 & 10), or if it is unclear whether the clinician is bonding to dentine, enamel or composite, CLEARFIL Universal Bond Quick may be applied (Fig. 11). A new layer of composite is placed on top to restore the defect (Fig. 12).

If available, employ a silicone index to simplify anatomical shaping:

If the defect is small, it is possible to apply the flowable composite directly and remove the excess material (Fig. 13). Achieving a natural shape and smooth transition between old and new composite is simplified using a silicone index, which may still be available from the original restoration procedure (Figs. 14 & 15).

Conclusion

Provided that appropriate materials and techniques are used, the modification of composite restorations can be easy and may address issues such as bubbles or defects in a freshly created restoration, changes in the colour of an existing restoration or shape loss due to wear processes. Choosing a suitable adhesive system is a key consideration, and clinicians are advised to opt for one that supports streamlined procedures and excellent outcomes, such as a single-bottle adhesive like CLEARFIL Universal Bond Quick. By following the tips provided in this article, clinicians can realise the desired outcomes in a minimally invasive, straightforward way, laying the foundation for long-lasting and optimal aesthetics and function.

Fig. 13: Flowable composite spreading and excess removal.

Fig. 13: Flowable composite spreading and excess removal.

Fig. 14: Silicone index placed over the teeth, including the tooth with the defect.

Fig. 14: Silicone index placed over the teeth, including the tooth with the defect.

Fig. 15: Outcome of the flowable injection procedure prior to finishing and polishing.

Fig. 15: Outcome of the flowable injection procedure prior to finishing and polishing.

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