In a previous article, I went over the steps I take when working with direct composites in the posterior. For this article I’d like to review the steps I use for placing direct composites in Class V lesions. Class V lesions, commonly referred to as cervical erosion, and in the literature as NCCLs (non-carious cervical lesions), can be extremely difficult to restore predictably.
Tay and Pashley described the bonding difficulties well in a review article citing the following challenges:
- Mineral salts occlude the dentinal tubules which prevents resin tag formation
- Many parts of the lesion show a hyper-mineralized surface that resists self etching primers and phosphoric acid
- Significantly lower bond strengths than normal dentin due to the sclerotic nature of the dentin in the occlusal, gingival
- Deeper layers of the lesion
The patient I’ll be using as an example has multiple old Class V restorations and is unhappy with their appearance due to staining and his very high smile line. On top of that, he has lesions that haven’t been treated, yet he would like to have them restored to look better.
While the etiology of Class V lesions is a frequent topic of debate, generally citing occlusal stress (abfraction), abrasion (tooth brush and toothpaste), and finally corrosion (acid) the one thing I can tell you about this patient is that his lesions are not caused by occlusal stresses. He actually has a pre-molar open bite; his anteriors and molars are all in occlusion, but there is no premolar contact no matter how he moves.
Here is how I typically treat patients that present these issues, again noting as in the previous article on posterior composites that there are a multitude of products and techniques that can be used successfully, I will simply present my technique.
Blending the composite
To treat this particular patient and his esthetic desires, I want to make the composite blend well on the occlusal, mesial, distal and gingival margins. As we all know, this can be challenging. In addition, I want to minimize the risk of future marginal staining, which can be a problem for all Class V restorations, particularly on the gingival margin.
For these two reasons, I bevel the enamel. Typically I create a 1 mm tall bevel in the occlusal margin, and a .5 mm bevel on the mesial and distal; doing this allows the composite to become more translucent and less noticeable. Very rarely, there can be some room between the most cervical aspect of the lesion and the gingiva; in this case I will put a small bevel on the cervical as well.
To solve some of the challenges in dentin bonding cited by Tay and Pashley, I air abrade the completed preparation with 50 micron aluminum oxide. Other authors have shown increased retention just from roughening the dentin with a diamond if you don’t have access to air abrasion.
The other choices to be made are whether to use a self etching dentin adhesive or a total etch system, and whether to use a microfilled composite or hybrid. The literature is clear that all the materials just mentioned can be used successfully, although with minor variations in overall retention rates and staining.
For these patients, I always use a total etch two-step system such as 3M single bond plus, since the presence of sclerotic dentin is highly likely. I also etch each tooth for 30 seconds with phosphoric acid rather than 15 seconds, which has been shown to have a better chance of getting a hybrid layer formed in highly sclerotic dentin. The etchant is then rinsed off and Gluma desensitizer is applied for 20 seconds, lightly dried and followed by the dentin adhesive. The adhesive is light cured and then composite placement can begin.
Contraction during composite curing
Class V restorations can be challenging to fill because of the contraction that occurs during composite curing. Typically during the contraction the risk is that the weakest bond will fail as the composite shrinks, leading to premature leakage and staining.
Since the weakest bond will be the cervical margin, assuming the other margins are enamel, I incrementally fill my class Vs. The first increment is to fill up the deepest portion of the preparation.
This increment is then cured. Next the occlusal and cervical increments are placed from mesial to distal, but not touching each other. Finally the middle section is completed. I personally use hybrid composite for my class Vs, but recognize many prefer microfills.
I typically do most of my finishing with rubber polishing abrasive points and discs to achieve the final shape and polish that you see in the final photograph. Note, the photo is from the appointment the composites were placed, so the tissue is somewhat irritated and the teeth have dehydrated slightly.
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