Gray/white border appearance during restorations margins?

[Faux]

Every now and then I'll see a white/gray border between my restorations and tooth structure. Almost like chalkiness really. Usually most of the walls are fine, but such as yesterday, this particular appearance was evident on the gingival floor.

Even when I passed it with the explorer, it was completely flushed. I noticed this more with resin modified glass ionomers than with composite.


Any idea? ways to avoid?

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[THS]

Before or after polishing? If after polishing it's debris getting trapped in a microgap between restoration and tooth. You may consider using a sealant like G-coat or fortify prior to polishing, then polish from the restoration out towards tooth.

If before polishing, maybe it's a rim of etched enamel past your restoration margin? Try etching far beyond the prep margin and see if that band gets wider or not.
I don't use RMGIs often, but for composite I'll do a "snow plow" technique where I line the floor of my prep with flowable, then without curing it pack some "packable" composite on top. The flowable gets washed up around the margins to prevent any marginal voids. I also use wide, shallow bevels and spread my composite past my prep margins to maximize adhesion and blending.

 

[NC dent]

If you are consistently getting white lines, maybe step back and think of what is going on. White lines are microgaps created by intense light activation especially in the presence of bulk filling and not accounting for c-factor forces created. I still get white lines on occasion. I have never been a bulk filler and I have always minded c-factor forces and try to keep composite to 2 walls when possible. Especially if you are using a high powered light like the Velo by Ultradent, start curing from 2-3cm away and over a couple seconds get closer to the composite until the light is touching the tooth. This allows you light to be as close as possible, but reduce the initial intensity so you get slower polymerization shrinkage = less composite pull on the wall. I also try to layer where I stop initial layers below the occlusal surface margin.

 

[Inkdot]

Do you see a white line or halo adjacent to the enamel margin, so between the enamel and the restoration (i.e. the cavosurface margin)? Apparently this is a common problem associated with composite restorations (and by extension RMGICs I would think).
The white halo you see may be due to microfracture of the marginal enamel. This may have occurred due to:

* traumatic contouring or finishing techniques
* inadequate etching or bonding of that area
* high intensity light curing, resulting in excessive polymerisation stresses

Potential solutions include:

* re-etching, priming and bonding in that area
* conservative repair, so remove the defect and re-restore
* use atraumatic finishing techniques (e.g. light intermittent pressure)
* use soft-start polymerisation techniques
* leaving as is and monitoring for leakage

[Heymann 2012]