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What is a Simulate shape design?Simulated shape design, or SSD, is a reversible method of demonstrating potential esthetic outcomes that involves creating trial restoration shapes and placing them over a patient's teeth and show patients potential tooth sizes, shapes and arrangements before carrying out treatment.
In essence, the technician makes new tooth shapes in wax, the dentist places these in the patient's mouth and the patient evaluates them.
Clinical Implications.With the decisions of shape, arrangement and size made at chairside, the whole flow of esthetic treatment can be handled smoothly. Preparations can be cut more accurately to better support the restorative material; decisions can be made to open or not open the contacts; and shapes can be agreed on in the earliest stage of evaluation, then duplicated faithfully in the provisional and final restorations.
There are no surprises for the patient, the dentist or the technician. Both the esthetic (smile design) and functional elements (anterior guidance) of the restoration can be checked with SSD.
SSD could become the standard in determining whether or not to proceed with esthetic treatment.
Simulated shape design is a method by which the dentist and patient can collaboratively work out tooth shape and arrangement issues.
SSD improves on the mock-up technique. It requires less clinical skill, as the wax addition can be delegated to a technician.
Involving the technician early in making the shape decision gives direction to the whole process. Function of the anterior teeth depends on the lingual surfaces of the maxillary teeth and the labial surfaces of the mandibular teeth.
It is easier to decide how to improve this function using wax on stone, using the improved visibility of an articulator, than it is to try to guess the lingual shapes with direct addition of composite in the mouth.
Therefore, the SSD technique is easier to perform and also can be used to plan proposed changes in anterior guidance.
THE TECHNIQUEThe best vehicle for communicating the benefits and drawbacks of esthetic anterior restorations is the final product.
Unfortunately, by this stage, there is no “out” for either patient or dentist; the commitment to treatment has been made.
To combat this difficulty, we developed SSD.
SSD shows patients how they will look after treatment—even in cases with several possible solutions.
SSD requires three stages:
- make a model
- transfer the model to the mouth;
- evaluate and adjust the proposed restoration according to the patient's wishes and the dentist's professional opinion.
Make a modelBefore beginning the SSD, the dentist should take a baseline photograph of the patient, then take accurate alginate impressions.
The dentist then mounts stone casts made from the impressions which clearly show the existing tooth shape, free gingival margin, palate and vestibule in centric occlusion with no bite registration, using a facebow on a semiadjustable articulator.
The technician waxes up the cast using some of the principles of macroesthetic smile design.
The diagnostic wax-up helps both dentist and patient make choices about veneers vs. full-coverage restorations, the need to improve anterior guidance, the need to involve lower incisors by recontouring or restoration, and the need for altering gingival contours.
Transfer the information to the mouthAn impression of the wax-up is taken in putty the esthetic matrix.
The dentist tries the esthetic matrix in the patient's mouth and marks the midline to help subsequent placement, then dries the teeth using a gauze.
Doctor fills the esthetic matrix three-quarters full with provisional material and seats it firmly over the teeth.
After the material sets initially, the dentist removes the esthetic matrix facially, leaving the SSD on the teeth .
The patient is taken to a wall mirror and asked to evaluate the proposed esthetic enhancement.
Evaluation/adjustmentThe most important feature of SSD is that patients can see the change in tooth shape in their own mouths.
It provides a working model of the proposed restoration. Adjustments can be made at the patient's request.
Of course, the patient must know that the temporary material has different optical properties from the restorative material, so it will not look exactly the same.
With the size, shape and arrangement decisions made, the dentist removes the simulated shapes.
USES OF SIMULATED SMILE DESIGN
Information derived from SSD is extensive. Patients are excited about it, because they can see what the dentist can do; they do not need to use their imaginations.
It is equally important for the patient to better understand the dentist's restorative limitations, and with SSD, they can see those limitations with their own eyes.
Should the patient like the shapes generated by the SSD technique, this information can be used directly by the dental laboratory in fabrication of the final restorations.
The SSD technique helps identify patients with unrealistic expectations. We found that patients expressions and body language told us more about their true expectations than their words did.
With SSD in place on the teeth, the dentist can check esthetic and functional factors.
These include the midline, arch form, profile, long axes, embrasure form, line angles, proportion, symmetry/asymmetry, amount of tooth revealed, tooth thickness, gingival contour, tooth macroanatomy and microanatomy, incisal edge position, smile line, shade and anterior guidance, speech, and the number and area of occlusal contacts in the edge-to-edge position.
SSD is an additive technique. There are a few situations in which SSD is of no use.
- When teeth have supraerupted or already look long owing to recession, SSD will be of limited use:
- When the anterior teeth already are prominent (facially placed), further addition material on the facial aspect may detract from esthetics.