A Minimally Invasive Anterior Makeover: Fabricating Direct Veneers Using Microhybrid Resin Composites

INTRODUCTION
The development of dental ceramics established new paradigms in aesthetic dentistry. Nowadays, indirect porcelain veneers can provide extremely satisfactory results,^1-3 increasing long-term durability;^4,5 this treatment modality may be considered the primary choice for aesthetic enhancements for anterior teeth. However, due to the higher cost and time demands associated with indirect procedures, the use of direct composite resins may prove more suitable for some patients.

As an alternative to indirect lab-fabricated restorations, direct resin composite veneers can also promote quite good aesthetic outcomes at lower costs and can be done with a very conservative clinical technique.^6,7 Modern composite resins have distinct advantages owing to the high number of shades (with varied translucency and opacity). These composite systems are now designed to be used employing a layering technique, providing very satisfactory aesthetic results⁸ with acceptable long-term durability.^9-11

The main difficulty with the direct composite resin veneer technique is the dependence on the ability (knowledge, skills, and experience) of the individual clinician in recreating the proper and natural tooth morphology,¹¹ and in selecting the correct shades.

The purpose of this article is to outline a detailed restorative technique, involving the clinical fabrication of 4 direct microhybrid composite resin veneers, which was done to provide the patient with a minimally invasive aesthetic solution for a compromised smile.

CASE REPORT
A 50-year-old female patient was dissatisfied with her smile and was referred to our dental clinic for an aesthetic solution (Figure 1). She presented with color change in maxillary incisors associated to small discrepancies in shape and positioning. Upon examination, it was also observed that some old and discolored composite restorations were in need of replacement. The treatment of choice would be to place 4 direct resin composite veneers. Compared to a more traditional approach using lab-fabricated all-ceramic veneers, this treatment choice would be a more conservative approach with a lower cost for the patient.

Figure 1. Initial preoperative smile photo. The color and shape alterations associated with the unsatisfactory existing composite resin restorations in the maxillary central and lateral incisors can be observed.

Clinical Protocol
Before isolating the maxillary arch, the initial shade was taken of the (hydrated) teeth, and VITA A3.5 (Vident) was selected. A rubber dam was then applied, and the involved teeth (Nos. 7 to 10) were prepared at a depth of 0.8 mm on the labial surface. Care was taken to create anatomic preparations that followed the natural mesio-distal and cervico-incisal convexities (Figure 2). Next, the enamel surfaces were etched with 37% phosphoric acid gel (DENTSPLY Caulk) for 20 seconds, rinsed thoroughly, and then slightly dried with absorbent paper. A primer and adhesive (Adper Scotchbond Multi-Purpose [3M ESPE]) were applied with a microbrush (Blue Star 2 [Microdont]), per manufacturer’s directions, and then light cured for 20 seconds. (Figure 3).

Figures 2a and 2b. Maxillary central and lateral incisors were prepared at a depth of 0.8 mm on the labial surface to receive 4 direct microhybrid composite resin veneers. (a) Sample of tooth preparation (labial view). (b) Lateral view showing the cervico-incisal convexity kept with the anatomical preparations.

Figures 3a to 3c. (a) The teeth conditioning was performed with 37% phosphoric acid (DENTSPLY Caulk) for 20 seconds, (b) followed by the application of primer, and (c) adhesive (Adper Scotchbond Multi-Purpose Plus [3M ESPE]), then light cured for 20 seconds.

Figures 4a and 4b. (a) Resin composite application started with a white opaque increment (Vit-l-escence [Ultradent Products]) selected to mask the underlying multi-colored tooth structure. (b) After that, increments of A3.5 were applied degrading from cervical to incisal third. The final layer consisted of a thin and uniform increment of Pearl Neutral.

The first layer of microhybrid composite used was a White Opaque (WO) (Vit-l-escence [Ultradent Products]). This layer was applied to mask the color alteration of the underlying substrate. After that, an increment of A3.5 was inserted with higher volume in the cervical area, decreasing in the thickness as it was layered toward the incisal edge. Finally, a thin increment of Pearl Neutral (P-2) was applied uniformly on the labial surface (Figure 4).

The next appointment, one week later, consisted of completing the final finishing and polishing steps. Detailed shape adjustment was accomplished with ultrafine diamond finishing burs (Ultrafine Diamond Burs No. 4137 [KG Sorensen]) and abrasive discs (Sof-Lex Pop-On [3M ESPE]) (Figure 5). The last step was to impart a final luster and gloss, using a polishing paste (Diamond Polishing Paste [Ultradent Products]).

Figures 5a and 5b. After one week, the detailed finishing and polishing was done using (a) ultrafine diamond burs (Ultrafine Diamond Burs No. 4137 [KG Sorensen]) and (b) abrasive contouring and finishing discs (Sof-Lex Pop-On [3M ESPE]); followed by imparting the final luster and desired surface gloss with a polishing paste (Diamond Polishing Paste [Ultradent Products]).

Figures 6a and 6b. Close-up pictures of (a) before and (b) after placement of the direct composite veneers. Natural color and shape were restored.

The difference between before and after treatment can be observed in the close-up photo in Figure 6. The patient was extremely pleased with the aesthetic results provided with this minimally invasive treatment choice (Figures 7 and 8).

Figure 7. Lateral view of patient’s smile. (Note the natural luster/gloss on central incisors provided by following the proper polishing protocol for a microhybrid composite.)

Figure 8. Final smile. The direct composite resin veneers provided a harmonious smile, and the patient was very satisfied.

DISCUSSION
Despite the recent developments and significant improvements made with all-ceramic materials, direct resin composite veneers still have relevant indications in aesthetic dentistry, especially when a very conservative approach is desired.^9-11 In addition to this, the lower cost and, furthermore, the possibility of easily and affordably carrying out any future repairs that may become necessary, makes it easier for the clinician and the patient.

In the case report described, the dental substrate presented a great degree of color variation, which could have affected the color of the final restoration. To reduce this interference, a WO resin composite was used before any other resin increment. After that, A3.5 was selected to give some color to the restoration. This increment was applied with a higher volume in cervical third, decreasing to incisal third to simulate the degrading pattern of natural teeth. After that, a resin composite with more translucent properties was selected (P-2) to mimic natural enamel. The final color was A2, due to the combination of WO and A3.5. When treating younger patients, especially those who may have been whitening their teeth, A3.5 must be avoided, and A1 or A2 resin composites should be selected as the second increment in order to determine a final color at A1 or even lighter.

Finishing and polishing are also important steps that always should be done after at least 24 hours, so the resin composite is completely polymerized and any initial hygroscopic expansion has taken place.^12,13 If this time is not respected, the resin composite will become brittle, and the final surface polishing will not be adequate. Abrasive discs are excellent choices to correct and refine the incisal embrasures that are smaller between central incisors, and for increasing between lateral and central incisors. Ultrafine diamond burs are also indicated to finish the labial surface, determining the flat surface of central incisors, and to properly position the proximal edges. For polishing, a diamond polishing paste is applied with a small felt wheel to provide the final gloss for the restoration (Diamond Excel [FGM]).

CONCLUSION
Direct veneers with microhybrid resin composites are a lower cost, conservative approach that can still achieve high levels of success in aesthetic dentistry.

References

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Dr. Maenosono is in the department of operative dentistry, endodontics, and dental materials at the Bauru School of Dentistry, University of São Paulo in Bauru, Brazil. He completed his DDS and is also a PhD student. He can be reached via e-mail at rafamaenosono@usp.br.

Dr. Rodrigues is in the department of operative dentistry, endodontics, and dental materials at the Bauru School of Dentistry, University of São Paulo in Bauru, Brazil. She completed her DDS and is also a PhD student. She can be reached via e-mail at raphaela.rodrigues@usp.br.

Dr. Bella Ishikiriama is an assistant professor in the department of periodontology at the University of Sacred Heart in Bauru, Brazil. She can be reached via e-mail at the address bellacolombini@usp.br.

Dr. Sérgio Ishikiriama is an assistant professor in the department of operative dentistry, endodontics, and dental materials at the Bauru School of Dentistry, University of São Paulo in Bauru, Brazil. He can be reached via e-mail at serginho@usp.br.

Disclosure: The authors report no disclosures.