02 Oct The Dark Side of Rubber Dam. Part I
I’m going to present a series of articles about the dark sides of the rubber dam, that has never been considered and analyzed.
One of the most frustrating experiences in restorative dentistry is the lack of contact area – or an insufficient contact area – at the end of the restorative procedure.
When we do a proximal filling in composite, we need to address the following problems in order to get a tight contact area:
- the thickness of the matrix (on average 50 microns)
- the linear shrinkage of the composite (in average 50 microns)
- the thickness of adhesive on the matrix (on average 10 microns)
- the rubber dam traction (among 20-80 micron)
An overlooked issue in dentistry is the negative effect or rubber dam upon the contact areas. It is common experience among dentists to get good contact areas under rubber dam at the end of the restorative procedure, and the same contact area eventually disappears or become weak after the removal of rubber dam.
I have analyzed this anecdotal issue in a numerical way, thanks to the intra-oral scanner (I-Medit 500). I have been scanning quadrants before and after having placed rubber dam, quantifying the reciprocal movement of the teeth onto the quadrant. What I have found consistently is the reciprocal approaching among the teeth of the quadrant, ranging about 20-80 micron, in non-perio-patients.
This new data – that should be quantified in a more rigorous way and with wider sample – implies the necessity to rethink to the separation in some clinical scenarios, as I have shown earlier (re-introducing the Elliot Separator alternatively to the classic rings).
These data cast an “alarm” also on indirect posterior adhesive restorations, cemented under rubber dam, like onlays. This pulling action of rubber dam may impede the correct seating of the onlay and/or may outcome in weak or no contact area at the end of the procedure.