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Veneers: Utilizing Silicon Matrices to Optimize Ideal Preparation Design by David Hornbrook, DDS, FAACD, FACE

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Simplifying and providing predictability at your smile-design appointment
As the clinical director of education at Keating Dental Arts, I am asked often by our dentists how to best take control of the veneer preparation appointment to ensure optimal results.

With this in mind, I have created a series of matrices that will simplify this very important, and often times, confusing appointment with your patient.

When preparing natural teeth, the goal should be to remove a minimal amount of tooth structure while optimizing esthetics and function, all the while providing adequate room for the restorative material.

The first step in a successful esthetic result is the initial smile-design visit. At this appointment, the clinician evaluates the deficiencies of the patient's smile and determines key elements, such as incisal edge position, smile line, incisal edge inclination, midline, profile, and buccal corridor. This information should then be transferred to the diagnostic esthetic waxer so that an aesthetic and functional wax-up can be designed (Figs. 1-3).

The goal of the kit is to provide a set of matrices to act as prep guides to ensure that you do not under prep or over prep.

This kit includes an esthetically designed wax-up, a stone duplicate of the wax-up, a modelplasty model marked by the waxer, a clear, thin, plastic suck-down stint of the wax-up, two preparation silicone matrices, and a silicone matrix of the wax-up to be used to fabricate beautiful provisionals easily and predictably (Fig. 4).

The facial and lingual matrices are used as clearance guides. One is for the buccal or facial surfaces, and the other is for the lingual surfaces (Figs. 5 & 6).

The final item that is made is a clear plastic matrix. This is used to match any tissue changes in the mouth that may have been made on the model during the wax-up to improve symmetry and esthetics. This clear matrix can also be used to ensure adequate reduction (Figs. 7 & 8).

The diagnostic or esthetic waxer will send you a model of the areas that had to be modified prior to beginning the wax-up (Figs. 9 & 10).







Usually these areas are marked in black. I call this modelplasty. Any areas where the teeth are misaligned or over-contoured to meet the esthetic and functional desires will need to be modified prior to beginning the wax-up.

Using this model where changes are made, reproduce this in the mouth (Figs. 11-13). I prefer to use a fine-tip Sharpie felt pen to mark areas on the teeth to match the reduced model.

If the enameloplasty exposes dentin, anesthesia will be required. If the tissue levels were modified by the waxer, this can be evaluated and marked using the clear matrix (Fig. 14).





A diode laser can be used to modify the gingival contours to match the wax-up (Fig. 15). After the enameloplasty is performed, in the facial and lingual/incisal matrices try to ensure that you have removed enough of the enamel or dentin (Figs. 16 & 17). With a malposition­­—instant-orthodontic case as the one presented—the facial silicone matrix is also used to ensure enough proximal reduction was performed to match the facial embrasures of the wax-up.

After reduction is verified, load the putty matrix with a bis-acryl material, which is placed in the mouth for two minutes and then removed (Fig. 18).

After putty removal, evaluate the esthetics of the wax-up transferred to the mouth (Fig. 19)

After aesthetics are approved, use a cutting diamond of 0.3mm–0.5mm depth and place depth cuts into the intraoral mock-up transfer in the gingival, middle and incisal thirds (Figs. 20 & 21).



Depending on the amount of incisal characteristics you want (I prefer at least 1.5mm), place a depth cut into the incisal edge using a chamfer diamond (Fig. 22).



After incisal and facial reduction is made, remove excess bis-acryl using an explorer or scaler, and evaluate the teeth for any remnant of the depth cuts. Remove the tooth structure down to the depth cuts. Final preparations should utilize light chamfer margins placed at tissue level (slightly supragingival) and rounded line angles.

The positon of the lingual margins will be determined by where the waxer had to extend wax to achieve ideal function and aesthetics. Due to the extent of the malpositions in this case and the attempt to lateralize a canine, the amount of tooth structure was significant.

After final impressions and all additional records are taken, provisionals are made using a "shrink to fit" technique and the original putty matrix with bis-acryl. Photos are taken of provisionals at full-smile close-up, chin-to-eyebrow, and profile for further evaluation and lab communication.

The objective, as mentioned previously, is to design the preparations so that the wax-up can be reproduced in ceramic, assuming the clinician took the time to design the smile correctly and then transfer this information to the aesthetic and diagnostic waxer. The utilization of silicone matrices ensure this is the case when used properly and decreases the chances of under or over-reducing the natural tooth structure to yield the desired results. In the case presented, the patient was given the option of orthodontics followed by restorative, but was adamant about only wanting "instant-orthodontics" utilizing all-ceramic restorations.

After two years, the patient has not experienced pain, microleakage, or gingival concerns, and is extremely satisfied with the final results.

Dr. David Hornbrook maintains an active private practice in San Diego, California. He is also the clinical director of education and technology at Keating Dental Arts in Irvine, California. He is one of the original founders and past directors of LVI, and founded PAC~live and the HornbrookGroup live- patient educational programs, as well as the founding director of Clinical Mastery. He has lectured internationally on all facets of esthetic and restorative dentistry and is an adjunct faculty member at numerous universities. He can be reached at David@hornbrook.com



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