Recently the MMP's inhibitory effect of Zinc-ions has been suggested to be performing well and during decades Zinc-based cements proved to be effective in maintaining and even restoring dentine functional properties.
The simple placement of a Zinc-phosphate base over deep affected dentine areas allows to obtain a long-term protection against the MMP's activity, to preserve pulp-health and support collagen remineralisation. Moreover the high radio-opacity of a ZOP-base delivers an optimal contrast and therefore, as a diagnostic tool, enhances precise follow-up. >> = THERANOSTIC ?!
Further, in case of repairing procedures, or in the step-wise approach, the whole base-compound can be easily removed and the exposed dentine condition, if necessary, can be adequately assessed, which is with no doubts a valuable advantage, in order to choose an adequate treatment option, particularly for all kinds of vitality preserving procedures in deep decay situations.
What type of bond is achieved between Dentin and Zn o based material?
Mechanical... retentive shape of dentinal defect is mandatory. This allows to preserve the highest enamel volume, even the unsupported enamel walls. Moreover the real advantage is to bond (Etch& Rinse+ Dry) over the ZOP-based material and enamel without concern about dentin condition, since protected, further without need of anesthesia.
So on histological level there is no chemical bond between ZOP and Dentin and no micro mechanical attachment then there is no adhesion actually and the two surfaces are liable to micro leakage and disintegration as each moves separately under function.
The same applies to etch and bond over ZOP as it is not etchable and no bond is achieved over it.
No adhesion doesn't mean that ..."the two surfaces are liable to micro leakage and disintegration as each moves separately under function."
Amalgam fillings are best performing in a similar way !
No concerns about micro-leakage since ZOP is antibacterial... and if the enamel margins are sealed nothing to be worried.
"The same applies to etch and bond over ZOP as it is not etchable and no bond is achieved over it." ...?? Did you tried ?
Sure ZOP is etchable and bonds better than dentin .... it can even be previously sandblasted! It is not to be confused with ZOE !
Adhesive dentistry is a breakthrough in clinical practice both on biological and mechanical level.
We can't go back to amalgam era and mechanical retention where tooth structure is sacrificed to restore lost tooth structure!
I can't find evidence supporting your claims of etchable ZPO and bonding better than to Dentin, please bring one.
.... " a breakthrough in clinical practice both on biological and mechanical level" maybe in a certain way , although restricted to sound dentin, in the first to second / third of lesion deep. Concerns remains about deep decay management where bonding to affected dentin is more than questionable !
So in order to avoid pulp-exposure ..." where tooth structure is sacrificed to restore lost tooth structure! " an ultra-conservative approach is currently advocated but little evidence is given about how and which material may be most suitable to support the physiological dentin repair potential.
So far my statements are only based on my clinical observation after about 10 years of procedure evaluation... and there is little evidence on the topic, since nobody really cares about cheap & effective alternatives !
I suggest you to try it out and see how good composite resin can be bonded on a medium to coarse grain ZOP base cement .
Best regards
Nicola