In the study by van Dijken Activa was placed without a dentin bonding agent which at the time of the start of the experiment was the recommendation. The instructions for use have been update in the mean time and Pulpdent now recommends acid etching and a dentin bonding agent. There are also studies that used a bonding agent and the survival compared to a control is excellent. Not all data has been published but it is safe to say that the updated instructions for use will result in a long lasting restoration. What about the bioactivity with a bonding agent? It appears to be also active with a bonding agent. I trust this answers your question.

How you explain the bioactivity or the ions release after using bonding agent ! What kind of test to approved this

Ask Tore Sauro and he will give you the evidence.

Thank you sir

Yes, we have observed with our results that hen using a bonding agent (simplified universal systems) the bond strength does not reduce compared to the control groups where the same adhesives were applied using a conventional composite. Hence, we hypothesise that some ions may osmotically diffuse into the dentine deactivating the endogenous proteolytic enzymes within the hybrid layer and deposite within the collagen fibrils up to reduce the nanoleakages and nanoporosities within the hybrid layer. This latter outcome was observed using Ca-staining dye-assisted confocal microscopy. We hope to publish such results as soon as possible.

Thanks Tore. You did the work and I did not want to speak on your behalf. All of us appreciate the work you do.

Dear Salvatore,

allow me please to share few questions :

1. The conceptual reason / advantage for using a Bio-active base should be to avoid the "potentially" adverse side effects of a bonding agent... or not ?

2. The "hypothesis that some ions may osmotically diffuse into the dentine" seems to be dependent on the hydrolysis of the bonding agent ... right ?

3. Then, If Activa alone could not improve, as expected (or pretended), the pulp-vitality preservation on the short-term, why would it performs better with a degraded bond ? ... in-vivo on the long-term ??

4. When enough "different" ions are available for a free osmotic-balanced diffusion into the dentine, taking in account the key-role of "water" in restoring homeostasis, only then eventually, a bio-mimetic remineralisation process may

be expected... do you agree ? Which is basically the reasons why MTA showed to performs better !

To conclude I wonder how long will it takes to "translate" dentine physiology knowledge before getting closer to a real bio-mimetic restorative concept ?

And further to make it available for the patients ...

Best regards

Nicola

All good questions!

1. Active base is different from active restorative.......no bonding agent will be used for Activa base liner, but you may need an adhesive when using activa restorative for full restoration.

2. it does not depend necessary from the hydrolytic degradation..........however, it is aspected that if a bonding agent degrades, the interface will be repaired by mineral precipitation; that's we observed with activa using confocal microscopy.

3. this answer is correlated to my previous 1 and 2. By the way, cell studies and in vivo study have showed us that is incredibly biocompatibile and bioactive.

4. Biomimetic remineralisation is feasible in vitro for the moment, but much more complicated to achieve in vivo. So I am afreid you question 4 makes no sense. There is nothing on the market for the moment that can give biomimetic remineralisation of dentine; all we have so far is speculation from companies and SKOL. Take care . Tore

It is such a great subject to discuss. I beg my pardon but I am a PhD. student so my mind confused. can you explain what is microleakage then?? Is there still a risk of microleakage when the bond degrades but the minerals replace it? Is it about the new generation filling material or adhesive material? or both? Is it a new era??

Nicola Minotti should be complemented for raising the question why the stated product performed so poorly in a properly conducted clinical trial. When deconstructing for potential reasons we often discuss operator, patient and material.

I believe it is essential to underscore that this trial was undertaken by an outstanding clinician in a clinical environment that has produced dozens of previous excellent trials. Hence, I do not believe that the poor results are any effect of the operator.

I also do not have any reason (or competence) to distrust the chemistry hypotheses suggested above.

This leaves the third potential factor, i.e., the patient. After reading the paper one may speculate whether some form of carry-over effect may have occurred since the paper state "Reasons for placement of the resin composite restorations were primary and secondary carious lesions, fracture of old amalgam fillings, replacement because of aesthetic or other reasons." (I assume that the "resin composite" in this sentence is just a cut and paste from a former publication and that the statement applied also to the RMGIC restorations). At least for old corroded amalgams, metallic ions can remain in the dentin and I assume that a minimal intervention philosophy was being practiced. I am not a chemist so I cannot judge a potential effect on the very complex chemistry that is being discussed above. Most in vitro studies on hard tissue de- and remineralization, secondary caries and microleakage are conducted on uncontaminated bovine dentine slabs that are "clean".

Article Secondary caries and microleakage

Observations from experiments conducted on such substrates may perhaps not apply directly to "old cavities" impregnated with whatever. Perhaps we should not take for granted that all biomaterials behave similar when placed in a primary cavity versus a cavity formed after an old restoration has been removed?

Very accurate remarks, I agree with the explications and I would like to thanks @ Asbjørn Jokstad for his contribution to the discussion.

Dear Salvatore Sauro ,

in relation to your answers, let me please add few remarks:

1. "Active base is different from active restorative" OK on the vol % of fillers , resulting in different viscosity but the ingredients are basically the same !?

The manufacturer description states: " ACTIVA™ stimulates mineral apatite crystal formation at the material-tooth interface. This natural remineralization process knits the restoration and the tooth together, penetrates and fills micro-gaps and seals margins against microleakage and failure."

2. Let us accept that for a defect with no retention a bonding may be necessary, then you write: " ... if a bonding agent degrades" ?

Thus the manufacturer explain that : "bonding agents will delay the bioactive advantages of ACTIVA, but with few exceptions they will not significantly decrease the bioactivity over time. Most bonding agents are permeable, and the

material-tooth interface begins the process of reaching a bioactive equilibrium after several weeks" ... >> So it's more a question of waiting for the "degradation" to take place ?

3. " incredibly biocompatibile and bioactive " This is what makes me questioning the poor results reported in that article... particularly because even without bonding the bioactive efficacy seems not to be that optimal as espected.

Moreover the manufacturer mentions : " Place appropriate pulp protection, if indicated " .... which, from my perspective, is not the best encouraging advice for an incredibly biocompatible material !

4. Sorry but I do not agree with you : " Biomimetic remineralisation.... complicated to achieve in vivo." Thereafter the sense of my question was directed to what is really necessary for a demineralized dentin interface in order to get the chance of recover .... IONS ! But Which ones ? And in which form ? Inorganic materials seems to offers more advantages than resin based ... or not ?

To conclude when I read :

ACTIVA BioACTIVE-RESTORATIVE is a dentin and enamel replacement material..

I definetively do not believe that this fits with a Biomimetic restorative concept.

Best SKOL

Nicola