Micro invasive veneers

19 Aug 2013 - 13055

Veneers arrived to our daily practice many decades ago, and now-a-days they are part of dentistry, a treatment we cannot put aside and that is considered among the first choices in conservative dentistry. Many times we have seen these kind of restorations failing or creating problems, probably due to lack of tissue respect from the clinician or non adequate substrates where the restoration ins bonded. In this article we would like to show you a simple protocol adopted by many clinicians in the world, in order to do logical and reliable preparations. We would like to show you one case of indirect composite veneers.

Fig. 1

Initial situation, an unfavorable smile of a young-adult female patient, discromia on tooth 2.1, yellowish teeth, multiple old composite class III restorations, diastema presence and incongruous shape between laterals and centrals.

Fig. 2

Incisal/occlusal view of the case, probably the most important image to take into consideration for this kind of treatment, where we must analyze the lost horizontal (vestibular) substance due to abrasion or misalignment. In this image we can create a project of how much material we will add and subtract from the candidate teeth to be restored.

Fig. 3

Initial smile situation, where we can appreciate discromia, misalignment, diastemas and visible composite restorations.

Fig. 4

Wax-up project, made in a white extra hard type IV plaster in combination with a beige wax in order to have high contrast, shows exactly how much material we shall add and where teeth should be prepared in order to obtain correct space. (lab work by Daniele Rondoni, Savona, Italy).

Fig. 5

the wax project must be always analyzed from this perspective, in order to be able to predict teeth alignment, to calculate the over contour we will be giving to the teeth and how much space will be required in order to do so.

Fig. 6

The initial model with a silicone stint from the wax-up in place, show how much space is at our disposal before preparing the teeth. Clearly, 90% of the tooth structure will remain untouched as no extra space is needed whatsoever (see the two central incisors and the only area in distal of tooth 1.1 that needs preparation).

Fig. 7

The wax-up always have to come with a transparent silicone index that covers all the vestibular aspect of teeth, this silicone is of extreme importance because is the tool that is going to transfer the planning of the model to the mouth with the use of light-curing materials to the mouth.

Fig. 8

Flowable composite (A2 body flow) is placed inside the transparent silicone and carried into the mouth where we are going to polymerize.

Fig. 9

After polymerization the transparent silicone is removed and the predicted shape form the wax-up is now copied over the teeth without any bonding procedure done. This stage is useful as a mock-up in order to decide shape and global aesthetics. Once this project is approved we will start the teeth preparation.

Fig. 10

Important: This is the main tip to learn from this article.

In order to be as conservative as possible and to achieve the perfect space, we are going to prepare the teeth and the mock up-together (knowing that most of the preparation will happen on the mock-up material), when using a guide bur, the 0,5 mm space is very easy to achieve and almost no sound structure will be touched.

With the mock-up in place, we will mark the sound tooth structure that perforates the mock-up material. These areas are the ones where the bur will prepare dental structure, knowing from the beginning the kind of preparation and the amount of tissue sacrifice that will happen without improvising.

Fig. 11

Incisal segment of the vestibular silicone, after preparation, showing on the incisal vision how much space is at our disposal for the future restorations.

Fig. 12

The same view but with the silicone showing a more apical sector of the preps, where we can appreciate how on the middle third the space is enough as well.

Fig. 13

A vestibular detail of the initial preparations, showing clearly the difference between the mock-up material and natural teeth, not how much material still remains. Is under that material were we will find sound enamel, the perfect substrate for adhesive restorations. Excess from the mock-up will be removed with a scaler very easily.

Fig. 15

Provisional restorations mechanically attached to the teeth surface.

Fig. 16

Alveolar plaster model with separable dies.

Fig. 17

The single dies outside the model.

Fig. 18

Each restoration margin is marked, then covered with plaster hardener and wax as a spacer.

Fig. 19

Deep dentins and palatal enamel is layered with the aid of the silicon stint from the original project.

Fig. 20

Dentin for the middle third incisal edge is now modeled.

Fig. 21

Some subtle white features for the mammelons are added with a non saturated dentin.

Fig. 22

Enamel layer is placed, and the veneers are carefully separated and corrected before the last polymerization in a light oven.

Fig. 23

Veneers on the light oven, ready for post-polymerization.

Fig. 24

The veneers after polymerization are polished to high luster. Composite treated in laboratory oven and correctly polymerized to a high degree conversion improve significantly their physical properties.

Fig. 25

The veneers on the master model ready for delivery.

Fig. 26

The field is isolated with rubber dam, old composite is sandblasted with Al3o2 of 50microns and the neighbor teeth protected with a metal matrix, after cleaning generously with water TPFE teflon tape was used for the neighbor teeth during the etching stage.

Fig. 27

Acid etching was performed on the enamel for 30 seconds and rinsed.

Fig. 28

Detail of the sandblasted composite and the etched enamel surface. Each veneer was cemented one at a time and prolonged polymerization times was followed on every restoration. An article about cementation will be published in the near future.