Dear Eduardo,

I have conducted a series of investigations in that matter, all presented at respective IADR-Meetings in the 90s. As a result, adhesion to aged composites is feasable, was reached by means of a special Adhesive (DMG Ecusite Composite Reapair) and roughening the surface prior to application of the addhesive enhances bonding strength signifiantly. Silance did not. However, the adhesive strength varied extremely dependant on the composite repaired, Tetric was best. Unfortunytely, in clinical practive you freqeunetly do not know the nature of the composite to be reaired. Hence our goal waas to reapir all bis-GMA/TEDMA/TEGMA/UDMA-based composites successfully, this was reached, in fracture testign cohesive fractures occured. Silorane-based composites are a completely different  matter.

Best reagards frm Hambug

Oliver Ahlers

http://www.cmd-centrum.de/team/zahnarzt.shtml

Thanks for your comment Prof. Ahlers!

However, I can say that our experience is as follows: Repairs of our study we perform resin Filtek Supreme (nanoclusters) on a z100  ; a similar monomeric resin, different fill and an adhesive poor results (L-prompt pop ) in cavities classes i and ii, and we had a 80% success at age 10, the repairs were small 3mm. roughly, perhaps the adhesion between a resin and another might be less relevant than we think!

Tha study  : PMID: 24907560

Hallo again,

initially prior to our studies we performed a sereies of test with different formulas of adhesives. the result reddered extremely due to the compositeion of the adhesives used. This supports the view that the adhesive is relevant. In fact, the adhesives tested worked different wiith  different composites. Hence my suggetions was that every manufaturr should be obliged to offer a repair adhesive with his products...

Best regards

Oliver Ahlers

Very interesting,

And what do you think of using universal adhesives for repair?

Concluding from my extensive studies on the materials availlable then it must be a question of luck if the respective universal adhesive is suitable for the task.

The decisive factor was/is the combination of small chain and longer chain molecules where the smaller chain molecules penetrate the surface of the agd coposite for some microns...-> we confirmed that by CLSM.

Best regards

Oliver

According to Sousa et al. (2013), composite repair is more effective when performed after a short period of time. Therefore, clinically, composite repair would not be the most indicated  treatment option when the substrate (composite restoration) has been submitted to the oral conditions for a long period of time. Also, the authors stated that such treatment is more effective when three-step adhesive systems are used.

Please, see the reference:

Sousa AB, Silami FD, da Garcia L, Naves LZ, de Pires-de-Souza F. Effect of various aging protocols and intermediate agents on the bond strength of repaired composites. J Adhes Dent. 2013 Apr;15(2):137-44. doi: 10.3290/j.jad.a29513.

Interesting study would be interesting to know the results with universal adhesives or only with bottle 2  of multipurpose scothbond

In this study you can see the results with a two-step adhesive system.

but, what is the sense of using primer in a repair? I understand that it must respect the protocol - but has no logic

already in the 70ies, Hotz et al. stated that repairs are more liekly to succeed if performaed after short time.

Hi everybody. It is an interesting discussion since I usually repair composite resin restorations when the margins seem to be well bonded and there are no clinical signs of leakage. I also check the roughness and signs of matrix degradation. It is not an easy task to evaluate them visually, but in 16 years of practice, I have got good results. I have always used the adhesives and resins from 3M (Z100 in the beginning, Z250 and now, Z350-XT with silanization + single bond and now, Universal single bond). I agree that when we don´t no the brand of the composite, it is difficult. The restoration age is also an important factor. More than this, when we don´t no the quality of the adhesion, we assume a high risk of failuring. The discussion about the increase in the time life of the restoration may be seen by different point of views. I usually opt for the repair when it will not spend a long period of time, when it will be easier than changing all the restoration, when I consider it will stay at least for more 2 years in good conditions, and when there are no risks of tooth fracture. In this case, I consider, that the life-time of the old resin was increased in, at least, 2 years (or much more, in some cases), with no need of a long session, anesthesia, with low cost, etc. If we consider the life-time of all the restoration as a new restoration, it will certainly be shorter. In summary, if the repair will be as invasive and will spend the same time of changing everything, I change all the restoration.    

I agree with explanation given by Yamaguti 

Perfect explanation given by Dr Yamaguti.

Parts of the old composite restoration may be well bonded with no caries, and may be left in place, provided that this part of the restoration can stay in place due to good mechanical retention and bonding.  The new composite added to this should have mechanical retention and bonding to keep it in place.  A 33 1/2 bur provides good mechanical retention.  The new composite does not necessarily have to bond with the old composite, but the new composite should at least have a good mechanical bond with the old composite.  Use microscope level magnification of 6-8x or greater to precisely determine if the part of the old composite left in place is stable and caries-free.  Why did part of the old composite break down?  Sometimes there is a plunger cusp that cracked part of the old composite.  This cusp would have to be rounded off before putting the new composite.  A dentist can also put amalgam instead of new composite to fill in and repair the old composite.  The amalgam will be held in place with mechanical retention, will expand to seal the interface between the amalgam and the old composite, and provides a localized microscopic toxic environment that prevents caries from growing at the amalgam-composite interface.  In clinical practice I have observed hundreds of examples of repaired composites that show no caries at the interface between the two composites and appear stable.  It is obviously possible for repaired composites to be stable and long-lasting restorations.  It is also not beneficial to remove a well-bonded composite.  A well-bonded composite restoration that is free of marginal caries is a very stable restoration, as stable as amalgam.

I agree with the answers provided.  I teach my residents that if there is a loss of marginal integrity with marginal staining to remove the composite until the stain is gone and there is still good composite to tooth interface integrity, then you can repair it.