The Middle Layer
Just a tiny amount of a strong color can change completely the outcome of a restoration, taking integration to a next level. Talking about stratification of masses, the layer located between the dentin and the enamel is called the middle layer. Paradoxically, this layer is extremely easy to reproduce when the dentinal thickness is correctly managed.
In this case report, we would like to point out the importance of reproducing white spots, a feature generally related to the enamel layer in natural teeth and reproduced in the middle layer when stratifying.
The adjacent 21 showed a large white and opaque stain fig.1 (type 1M++++) (1 spot M medium ++++ Strong white) (1).
Looking from a lateral view, it could be appreciated that it was not only a simple blotch, but also an hypoplasic spot.
An underexposed picture showed the chromatic complexity of this tooth with a better contrast. (2)
At the second appointment, after the local anesthesia, the teeth were isolated with rubber dam.
Then the spot on 21 was slightly prepared using a low speed carbide bur in order to eliminate the rudest aspect of the opaque white spot. Less intense white spots were left intact.
The margin on the tooth 11 was regularized with diamond removing the uneven edges of thin enamel.
A 20 blade carbide bur was used to remove unsupported prisms invisible to the naked eye and a short bevel was prepared.
During acid etching, two wedgeguards were used to protect adjacent teeth from the acid.
Adhesive procedures were performed.
The silicon key was applied and the margin of 11 was marked with LM Fissura instrument.
In order to apply the exact amount of composite to create the first palatal layer.
A layer of A2 dentin was applied over the spot on 21, trying to cover it.
Then a sectional metallic matrix was placed on the mesial side of 11 and blocked with a plastic wedge (Img. 17); the anatomic shape of this kind of matrix, even if designed for posterior restorations, is very helpful to give the proper curvature to inteproximal areas of central incisors.
A thin layer of natural enamel was applied on the 21, while the central dentinal body of the 11 was made using an A2 dentin mass, mimicking the anatomy of the adjacent tooth.
Dentinal body being modeled.
Dentin body finished must have the right thickness in order to obtain an optimal enamel-dentin ratio.
As one of the most important stages, the white spot fabrication (type 1S ++) on the 11, applying a white stain with the LM Fissura instrument, according to the programmed characterizations decided on the color analysis phase.
The characterizations modeled and polymerized.
A final layer of natural enamel was applied on the vestibular surfcae, making sure thant the margin is perfectly sealed, but without surpassing the margin.
Glycerin was used to improve the light curing.
Prolonged light curing (not optional). under glycerine (optional).
Finishing procedure was made with LM Eccesso instrument, and a diamond bur on contra-angle (Perioset, flame bur); it is highly efficient and it allows the clinician to control speed and torque very easily.
After polishing with silicon points, stripes and pastes, the rubber dam can be removed.
Immediate aspect of the teeth whithout rehydration.
Before the restorations.
After two weeks, the good integration of the restorations can be appreciated, together with the natural aspect of the white stains.