Clinical Considerations for Digital Restorative Veneers
A functional and esthetic outcome achieved with modern materials
Often we tend to build dental treatment workflows around known or assumed limitations and past experiences. The dental profession is experiencing rapid changes in material options, impression techniques, and manufacturing processes for dental restorations. To ensure the most conservative, esthetic, or long-lasting outcomes for our patients, traditional treatment methods may be replaced with newer materials or techniques where appropriate.
The case presented here is one such example of improving a patient’s smile with advanced treatment options. The chief aim of this article is to illustrate a restorative methodology using digital restorative veneers that embraces the potential advantages of newer techniques and materials to arrive at a positive functional-esthetic outcome for a patient.
Case Presentation
A generally healthy 39-year-old female patient presented to the office with a primary concern over the appearance of her smile (Figure 1), particularly the shape, size, and color of her teeth. Radiographs and clinical and periodontal exams revealed good periodontal health, no dental caries, and evidence of bruxism and malocclusion and associated traumatic occlusal wear.
The risks and benefits of three treatment options were discussed with the patient: no treatment, enamelplasty/occlusal equilibration/esthetic gingivecomy, and/or veneers. The patient agreed to proceed with enamelplasty, occlusal equilibration, and esthetic gingivectomy first. For the gingivectomy, the proper biologic width was preserved using bone sounding and periodontal probing techniques along with pre-surgical marking of the desired gingival zeniths with an indelible marker (Figure 2). Then, to ensure a successful outcome during alteration of the patient’s occlusal function in lateral and protrusive movements, an assessment was made both intraorally and on articulated casts. Conservative enamelplasty and occlusal equilibration were completed in two subsequent visits. The tissues were allowed to heal for 4 weeks (Figure 3).
Pretreatment Considerations for Veneers
The patient was pleased with the result to this point but requested further improvements to the appearance of her smile, so the process of veneering teeth No. 5 through No. 12 began. The following pre-treatment considerations were made in the context of the intent to prep the teeth, design and mill the restorations and deliver them in a single visit using a digital restorative workflow.
Veneers in many respects are deceptively difficult to create in a manner that is both esthetically pleasing and functionally correct.1,2 This difficulty can be compounded when one intends to utilize a single-visit workflow, in which the preparation, design, milling, finishing, and bonding of the veneers occurs in one visit, as was the case with this patient, particularly if appropriate planning was not achieved.3,4 When a few key questions are answered prior to beginning treatment, however, the process can work to an advantage in that the patient does not have to endure wearing temporaries or have a second anesthesia event. The pretreatment considerations specific to the single-visit approach are described below.
Desired Final Tooth Form and Shade
To control the outcome as it relates to tooth form during a single-visit digital restorative procedure, one may elect to pre-arrange for the fabrication of a functionally correct diagnostic wax-up, as was done for this patient. The wax-up may serve as a communication aid for the treatment planning/presentation phase5 and as a guide that may be scanned into CAD software for duplication during the design of restorations. In this case, the patient’s diagnostic wax-up was scanned into the Planmeca PlanCAD (www.planmecacadcam.com) software for this purpose prior to the treatment visit. Prior to beginning the procedure, one should also determine the desired final shade. In this case, it was ascertained that the patient wanted a final result matching shade BL3 (Ivoclar Vivadent, www.ivoclarvivadent.us).
Stump Shade and Ceramic Material Selection
It is generally difficult to determine the stump (prep) shade prior to preparation. In the case of minimal preparation veneers, however, one can assume a shade that is approximately the same value as the preoperative shade, which was determined to be A2 in this case.6 At this point in the process, the author finds that it is ideal to pre-select a material by porcelain type, shade, and translucency, in part because selecting the desired block prior to the appointment reduces inventory costs.
IPS e.max® CAD Impulse Opal 2 (Ivoclar Vivadent) was the material selected for this case. Although the corresponding shade was actually BL2, which is slightly higher value than the desired shade of BL3, the anticipated prep shade of A2 was expected to sufficiently lower the value of the final restorations. The material characteristics of moderately high flexural strength, medium translucency, and opalescence made e.max CAD Impulse Opal 2 an ideal selection for this case.
Treatment Protocol
During the treatment phase, there are several steps that require special attention to ensure a smooth progression to delivery. Some of the relevant questions that a treatment strategy should include are discussed here.
Creating a Desirable Tooth Form
With any digital restorative workflow, the opportunity exists to either copy a tooth form or to create one using software templates and tools, for which there are three methods. One may scan the teeth before preparation; scan provisionals that have been used for verification of the esthetics, phonetics, and occlusion; or scan a wax-up directly. The last option was performed in this case.
Ensuring Uniform Thickness
As has been previously mentioned, IPS e.max CAD Opal 2 was selected for this case. The relative translucency of this material will allow the underlying prep to influence the final shade of the restoration. Because this is the case, careful attention needs to be paid to uniform reduction of the teeth such that the final restorations will have even thickness.
Three strategies may be used to ensure uniform and minimal thickness. First, one may create a silicone matrix of the diagnostic wax-up and then use that matrix to verify that the reduction geometry is similar for all teeth. Second, in this patient’s case, the right maxillary lateral incisor (tooth No. 7) was rotated medially, causing the mesiofacial aspect of the tooth to be lingual to the desired final preparation position. To correct for this discrepancy, a very conservative composite esthetic core build-up was placed on this surface (Figure 4). When doing build-ups where the intent is to mimic the underlying tooth structure, dentin opacity composite is the ideal choice rather than universal composites that are not opaque enough.7 Third, one may leverage the CAD software to re-verify that the desired uniform thickness has been achieved during the restoration design phase. In the PlanCAD design software used in this case (Figure 5), the restorations were visible in a translucent mode over the tooth preparations. Using this visualization, it was determined that the restorations were uniform in thickness.
Achieving a Translucency and Chroma Gradient
Uniform preparation reduction will lead to a harmonious influence of the tooth on the overall final restoration coloration.8 Additionally, a transition in reduction geometry may be leveraged to create a gradient in chroma from the cervical to the middle/incisal one thirds. When it is advantageous to create additional incisal translucency, the reduction of the incisal aspect of the preparation will generate a situation where the light is transmitted through the tooth, thus increasing translucency where there is no preparation backing the restoration (Figure 6 and Figure 7).
Finishing for Natural Surface Texturing
The goal for surface characterization when performing digital restorative veneers in one visit might be described as “rational esthetics.” While there are a plethora of methods possible, the most practical method from the author’s experience is to follow these steps after verification of passive intraoral fit of the milled restorations.
1. Crystallize the restorations as per manufacturer instruction.
2. Add surface texturing with a lab bur, creating mamelon depressions, etc.
3. Bevel the incisal edges to create a prismatic effect and thus a “halo.”
4. Polish the restorations.
Polishing was completed in this case with Diashine® Extraoral Fine (VH Technologies, www.diashinepolish.com). Application of surface stain was not necessary because the attention to the preparation geometry resulted in the desired chroma and translucency gradients.
Delivery and Follow-Up
The main difference one will appreciate when digitally creating and delivering veneers in one visit is the relative ease of controlling sulcular bleeding and retraction. In this case, bonding of the veneers was achieved using Variolink® Veneer cement (Ivoclar Vivadent) with a total-etch technique with strict adherence to the manufacturer’s instructions for preparing the ceramic surface. The retraction cord that was placed prior to beginning the tooth preparations is left in place until the cleanup phase of bonding (Figure 8). This technique of using one cord for the entire procedure avoids induction of bleeding and inflammation from repeated placement and removal of cord.
It is unrealistic to assume that a final occlusal adjustment is possible when the patient has undergone a prolonged procedure such as the one presented here. The goal initially is to achieve a generally comfortable occlusion through assessment and adjustment of both the patient’s static occlusal contacts and those in the normal envelope of function (Figure 9 and Figure 10). The patient is then appointed for a minimum of two follow-up visits to further refine the occlusion.
Conclusion
Using the techniques described, the treatment goals of minimal tooth reduction, highly efficient workflow, and a functional/esthetic result were maintained (Figure 11). Dentistry is continuously evolving. As we gain new insights, materials, and manufacturing processes, we are given the opportunity to blend proven methods with new ones for exceptional outcomes.
About the author
Alex Touchstone, DDS
Adjunct Assistant Professor,
Department of Prosthodontics
Tufts University School of Dental Medicine
Boston, Massachusetts
Private Practice
Hattiesburg, Mississippi
For more information, contact:
Planmeca CAD/CAM Solutions
972-234-3880
planmecacadcam.com
References
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