Preservation of a very small enamel ridge can be determining to the longevity of a restoration. Choosing the right time to be conservative – and when not to be – is of primary importance as we tend to see extremely conservative procedures that, paradoxically, can do more harm than good.
This trick that I’m about to share is actually an old procedure that has been performed for more than 3 decades: it consists in preserving the thin remaining sound enamel below the gingival margin of the cavity after removing big decay. Thanks to adhesive procedures, it is easy to overcome this problem and respect the most delicate tissues remaining in our clean cavities.
Img. 1 – Initial situation, a 28 year old patient came to our attention with two big-sized proximal caries on the mesial side of tooth 2.6 and on distal of 2.5.
Img. 2 – The rubber dam just placed must be washed before carrying out any other procedure.
Img. 3 – The field is then ready to work on.
Img. 4 – Before intervening in any proximal lesion, we must place a wedge interproximally in order to separate teeth, compress soft tissues, protect the rubber dam and determine the position of the gingival margin. As a rule, never start a proximal cavity opening without having positioned a wedge.
Img. 5 – Cavity opening starts from the occlusal surface, near the ridge, in order to find the carious spot. This strategy is useful to determine the width of the cavity, as well as to position the axial margins and, most of all, as a training not to touch neighboring teeth of course.
Img. 6 – We keep opening the cavity until we find healthy enamel on the margins. Sometimes we will find any, but it is mandatory to work carefully and try to do so. In a case like this one we should keep going.
Img. 7 – Caries detector is particularly useful in big cavities to detect remaining infected tissue under the enamel in big cavities.
Img. 8 – After opening of the second cavity, still working with high speed and generous water irrigation, a big amount of infected tissue is still visible. At a time in which the cavity looks rather clean, we switch for the low speed contrangle and no irrigation, while the assistant air blows directly towards the bur. This strategy allows the clinician to have a clear vision of the tissue that is being removed.
Img. 9 – This is the point where magnification and the caries detector play an important role, by bringing out the decay/debris that remain in the enamel wall.
Img. 10 – With a low speed diamond bur we take the remaining debris out. Low speed diamond bur is used against these delicate structures in order not to break the wall. Note how the enamel at the level of the full wedge is hollow, thus extremely weak and delicate.
Img. 11 – At this stage we have a big problem: if we now placed the matrices, these two walls would collapse at the moment of reinsertion and tightening of the wedge, and the margin would most probably end up subgingivally in cementum and dentin. Given the fact that we cannot afford to take that risk, we will make everything in our power to maintain those thin walls intact.
Img. 12 – Heres the main tip of this article.
Without removing the wedge, we will carry out the bonding procedures, in this case clorhexidine 2% for 2 minutes followed selective etching of the enamel with 37% orthophosphoric acid, rinse, dry (thoroughly), application of a universal bonding adhesive and 1 minute polymerization to ensure a perfect hybrid layer. We can now apply a flowable bulk fill material in order to back up the tiny enamel ridges with the internally added material, making them resistant again. After this step, if we are lucky enough, we can remove the wedge and place the matrices without a single drop of blood spilling. In the opposite case of blood contamination, wash thoroughly and apply the universal bonding once again.
Flowable bulk fill materials, are easy to place in a small area like this one, and the volumetric contraction of these materials is near to zero, thus eliminating the unnecessary stress that a conventional composite could transfer to such a delicate area.
Img. 13 – Synchronized Matrix strategy, as described for anterior teeth in previous articles, and ring positioning ensure a tight contact. Note that the build-up of the walls will be done alternating the removal of the matrix.
Img. 14 – Build-up of the distal wall of tooth 2.5. The color was an A3 body shade.
Img. 15 – Construction of mesial wall of 2.6 with the same material (A3 body).
Img. 16 – After removal of the ring and matrices, the fill-up of the cavity is done with a bulk fill material in paste. The space left for the veneering material should be 1,5 mm thick.
Img. 17 – The veneering material was a conventional A3 body composite, modeled with successive cusp build-up technique.
Img. 18 – After passing very delicately a rubber tip (Shofu Brownie) we polish with a natural bristles brush (Kerr-Hawe) and a diamond polishing paste (Diamond Twist SCL, Premier).
Img. 19 – Restorations after polishing.
Img. 20 – Another view to better appreciate the glossy surface achieved with this simple polishing protocol.
Img. 21 – After rubber dam removal, occlusion is checked.
Img. 22 – Control after 2 years. No sensitivity and good integration.
There are only very few pieces of `hopeless´ enamel that are worth saving, preserving and using all of our weapons to play the ultraconservative dentist. Cervical enamel is, in fact, one of them. Tunnel approaches and minimal invasive concepts, as well as careless preservation methods can sometimes mislead the clinician to an improper caries removal stage. Hollow cervical enamel after caries removal in young patients should be carefully treated and reinforced with flowable bulk fill materials.