CAD-CAM Liberty

Shadeguides - Indirect posteriors
27 Nov 2015

Are you unsatisfied of being unable to apply CAD-CAM technology in your daily practice? The first time we tried to do a chair side restoration, it was not as easy as promised by many. Finally a brainstorming from the Styleitaliano group opened my mind to follow a feasible method to be able to take the best of the latest technologies and in the less time as possible.

Few time and high quality are two characteristics we would like for any of our restorations, especially for the indirect ones, laboratory steps many times impede this, especially regarding time. CAD-CAM enthusiasts claim this is extremely easy and many people felt exactly the opposite in the first contact with this technology. In other words, expending a horrible amount of time.

The styleitaliano team propose a Feasible method for CAD-CAM restorations, thinking 360º not only regarding clinical timing but as well quality and economics.

Now-a-days the digital dentistry has overcome many problems, especially regarding the precision issues and the speed of the impression time.

Partial indirect restorations are the state-of-the-art when projecting cusp protection, margin adaptation, aesthetics and most of all tissue conservation.

Fig. 1

An everyday case that needs a fast and routine treatment, granting the highest quality should be treated with a trustworthy protocol. Initial situation, a patient comes after endo treatment with a temporary composite on the mesial of the tooth 16. The contact point from the previous restoration was impending the floss passing.

Fig. 2

In order to make the rubber dam pass passively we opened the medial part of the old restoration. The rubber dam is placed and invaginated properly. Immediately after we remove all of the old composite and proceed with a new build-up with a dentin A2 (Filtek Supreme XTE).

Fig. 3

After removing the rubber dam immediately we prepare 2mm occlusal, in order to give the right space for an indirect restoration. Without entering in debt with ultra thin restorations, the ultimate clinical and in-vitro evidence are into these thickness values in various aesthetic materials.

Fig. 4

Distal ridge was decided to be removed because of a distal enamel decay. Margins were taken to the zone where we meet the wedge, this area gives us plenty of security, meaning that is an area easily accessible with probes, proxa-brush, dental floss, etc.. not only during cementation stage, but as well in the future controls and follow-ups. It is said that partial coverage of posterior teeth can lead to destructive preparation of teeth, the state-of-the-art preparation which is a mixture of old techniques, some of them even from the gold era, reside on the quest of: 1 Thickest enamel margins, 2 Accessibility of all the margins, 3 Minimum space, 4 Flat surfaces, 5 Unique Geometrical positioning

Fig. 5

After removing the wedges and rubber dam, is very likely to have bleeding gums. In order to stop the bleeding, it is suggested to use an hemostatic agent (Astringent paste 3M ESPE). After letting it act for 5 minutes it can be generously rinsed with water and air.

Fig. 6

Operating area is slightly powdered with CAD-CAM contrasting agent and the intra-oral scanning is performed (TrueDef). The patient is dismissed for 30 minutes into the waiting room.

Fig. 7

Simple tools have been developed to help the clinician to carry out the impressions, which require different skills and movements from the conventional silicone impressions. The Styleitaliano team together with “Smile Line” developed under the guidance of Dr. Gaetano Paolone a series of soft tissue retractors called Photo-CAD, especially designed to separate in the lower arch the tongue and the cheek at the same time (Photo-CAD LOW), and in the upper arch to be able to separate the cheek in its full length up to the second and third molar (Photo-CAD UP). The name Photo-CAD comes from the ability to act as a retractor for Photography and for the CAD impression (Computer Assisted Design).

Fig. 8

The STL file is immediately sent to the trusted laboratory (Giuseppe Mignani, Bologne). In the mean time the clinician is entitled to do other tasks. In the classical approach, either the dentist should design or outsource the full work, wasting a lot of time in either situation.

Fig. 9

The antagonist and their relationship are recorded as well in very little time and received by the laboratory.

Fig. 10

It requires few time to set a fast digital workflow between the lab and the clinic, as soon as the lab receives the file, the 3D design is done rather quickly, in about 20 minutes the file goes back and forth with the final design.

Fig. 11

Immediately after receiving the file, in this case, the restoration was milled -in-house- so depending on the machine, the time of finalisation varies. Modern materials as Lithium disilicate are used frequently to perform this kind of treatments with superb results, but as well since many years, the best alternative to the ceramic restorations has been the laboratory made composite, due to many reasons as the softness of the material and its respect to the natural enamel of the antagonist, but most of all the kindness of this material is the capability it has to be maintained and repaired, superior to any other material. LAVA ultimate was chosen for this case because it has the same and better properties as a laboratory processed composite.

Fig. 12

Characterisation phase (stains) and polishing are done, rather fast, enhancing the anatomy with sharper burs, creating a sulcus with super sharp 4 edged bur, inserting stains and polishing. This phase was done by Mr. Giuseppe Mignani.

Fig. 13

The overlay is fitted and adjusted proximally (if necessary). If the fitting is good we can proceed to field isolation and cementation.

Fig. 14

Contact points must be veryfied and corrected with an abrasive rubber point until complete settlement of the restoration is achieved, full stability and marginal fit.

Fig. 15

CAD-CAM restorations are rather precise, and require few adjustments. At this stage, of course, color does not seem to integrate. After cement filling, the light will pass more effectively and the margin will likely disappear.

Fig. 16

The quadrant isolated and ready to perform the cementation steps.

Fig. 17

Sandblasting of the restoration is performed immediately after the build-up will be sandblasted intra-orally with 2bars pressure and 50 micron Al2O3 within at least 5 centimeters form the surface.

Fig. 18

After carefully sandblasting the composite build-up with the neighbor teeth protected with partial matrices and making special attention to properly sandblast the deep margin elevation material, we will perform selective acid etching of the enamel with 37% phosphoric acid during 15 seconds.

Fig. 19

The cavity is treated with a self-etch universal bonding system (Scotchbond Universal, 3M ESPE) and the solution is brushed during 20 seconds and left during 40 seconds undisturbed in order to act properly in the dentin, immediately after with air the excess of material will be removed. Do not polymerize.

Fig. 20

The same adhesive is placed in the inside of the restoration and excess is removed in the same way mentioned above.

Fig. 21

Dual curing cement is applied in the inside of the restoration.

Fig. 22

The cement excess flowing through the margins on the first fitting of the restorations.

Fig. 23

With a small instrument (Fissura, LM Arte, LM instruments, Parainen, Finland) the excess is removed from all the margins, including the interproximal.

Fig. 24

With a rounded condenser (Condensa, LM Arte, LM instrumetns, Parainen, Finland) the restoration is held in place, not often extra excess might come out. Floss is passed in the distal and medial area.

Fig. 25

If the restoration is stable we will remove the excess with a brush.

Fig. 26

Extended polymerization is done.

Fig. 27

Polymerized invisible excess is taken out with a sharp instrument (Eccesso, LM Arte, LM instruments, Parainen, Finalnd) taking much attention especially to the proximal area.

Fig. 28

The final aspect of the freshly cemented restoration.

Fig. 29

Occlusion prediction from the machine required minimum intervention.

Fig. 30

Final aspect of the restoration.

 

Bibliography