Aesthetic Restoration of Maxillary Central Incisors

Anterior composite restorations present many aesthetic challenges to the clinician, and the difficulties increase with the size of the restoration. However, the quality of composite materials has advanced steadily in recent years, to the point that it is now more possible than ever to achieve both high aesthetics and high strength with a composite resin restoration. A careful and precise technique is of course vital to the success of any case, but the results that can be achieved with composite continue to grow more impressive.

UNDERSTANDING NANOFILLERS
To understand how the materials have advanced, a review of nanofiller technology is helpful. Nanofilled composites have been the object of much attention from the dental community for their ability to withstand wear better than other types of composite. However, experience shows that the use of nanoparticles in a composite does not automatically guarantee strong performance. The manner in which the nanoparticles are incorporated plays a significant role in how the material performs, both in the office and over time in the patient’s mouth.


Many currently available hybrid composites include nanoparticles in their formulations, but still lose polish over time. This is due to the blend of particles in these materials—hybrid filler particles are mixed with nanoparticles or fumed silica. The incorporation of the large filler particles in these materials allows for high-filler loading, which helps contribute to the composite’s strength. However, the size disparity between these different kinds of particles results in a lower degree of polish retention, due to the fact that over time, some of the larger particles can be plucked from the matrix during wear.

A composite resin must be used that incorporates a unique blend of particles to overcome this issue. One example is the Filtek line of restoratives from 3M ESPE, which are made with both individual nanoparticles as well as clusters of nanoparticles. These nanoclusters are lightly sintered prior to their incorporation in the composite, which allows them to break apart during the wear process. Unlike hybrid materials, from which the loss of large particles dulls the restoration’s finish, the breaking apart of the much smaller nanoclusters in this material allows restorations to maintain a greater degree of polish over time.

 

RETAINING POLISH FOR LONG-TERM WEAR
Microfill composites, often presented as a better-wearing alternative to hybrid restoratives, do in fact retain polish better, but do not offer the same strength. This is due to the weak link created by the bond between the resin matrix of the microfill and the prepolymerized “organic filler” matrix. Studies have demonstrated that under stress and fatigue, microfill composites often fracture along the lines between these particles.1,2 Evidence demonstrates that microfills are also more prone to marginal breakdown under occlusal loading.3 A nanocomposite, however, does not use a prepolymerized filler. Additionally, because the material’s nanoclusters act as a single unit, they enable a high filler loading. These characteristics result in higher strength than what is found in microfills. The combination of the highfiller loading and the material’s advanced resin matrix allows it to offer high compressive strength, flexural strength, and diametral strength, as well as fracture toughness.


Coupled with its polish retention ability, these characteristics make composite resins like the Filtek composites truly universal, providing the aesthetics needed for anterior treatments, as well as the strength required in posterior regions. A nanocomposite material is able to offer high polishability with the strength of a hybrid. The following case demonstrates the excellent aesthetics that can be achieved with this class of materials, along with the characteristics that make them easy to use.

 

CASE REPORT

Figure 1. The patient had broken both teeth Nos. 8 and 9 from a fall.

Figure 2. The teeth were prepared with infinite bevels.

Figure 3. A small amount of composite in shade A1E was placed in the lingual matrix.

Figure 4. A football burnisher was used to attach the resin.

Figure 5. The index was removed, leaving a lingual shell on which the remainder of the restoration was built.

Figure 6. A halo was created using white tint at the incisal edge.

Figure 7. Shade A2B was utilized for the dentin buildup.

Figure 8. The final enamel layer was shaped with an interproximal carver, gold Almore instrument and brushes.

Figure 9. Composite was placed first in the lingual matrix, then brought to the teeth and attached with a football burnisher and a brush to create the lingual shelf.

Figure 10. The distal contact and surface were formed.

The patient, a 22-year-old male, visited the clinic after having broken teeth Nos. 8 and 9 in a fall the previous night (Figure 1). The patient’s college graduation was in 3 days, and he was seeking a way to repair the teeth quickly and aesthetically. Radiographs were taken, and because of the severity of the break on tooth No. 9, it was also tested for vitality with an electric pulp test, a cold test, and a percussion test prior to determination of treatment. All test results showed the tooth to be vital, and the patient agreed to proceed with a resin buildup. The patient was informed at this time that tooth No. 9 would have to be monitored closely with regular 6-month checkups to ensure its ongoing vitality, and he understood that a root canal might eventually become necessary.


An alginate impression was taken for the creation of a diagnostic wax-up, and the patient was sent home with glass ionomer temporaries. The wax-up was used to fabricate a lingual index with a vinyl polysiloxane putty material (Exaflex putty [GC America]). 

The patient returned to the office the following day for the final restorations. Local anesthesia was administered and shade selection was performed. A significant amount of white stain was noted on the patient’s teeth during this step. 

Next, a rubber dam (Hygenic Dental Dam Latex [Coltène Whaledent]) was placed and ligated with floss. Then, the preparations were done using a flame diamond (8862-014 [Brasseler USA]) to create a bevel around the teeth. A flexible disc (Sof-Lex Contouring & Polishing Disc [3M ESPE]) was then used to blend the bevel on the tooth surface and to round the sharp angles interproximally (Figure 2).

The smaller break on tooth No. 8 was repaired first. Enamel was etched with phosphoric acid etching gel and Adper Easy Bond Self-Etch Adhesive (3M ESPE) was applied. Although a separate etching step is not always necessary when using Adper Easy Bond, I elected to perform it in this case due to the high amount of enamel with which the restoration was being used. The adhesive was cured, and the lingual matrix was tried in place to ensure its fit. 

A small amount of Filtek Supreme Ultra Universal Restorative (3M ESPE) in shade A1E was placed in the lingual matrix (Figure 3), and the matrix was then held to the lingual of the teeth. This composite is available in an expanded range of body shades. I have found that the availability of new bleach shades makes it simpler to create a restoration that blends in with bleached teeth, an important ability as the popularity of whitening grows. I have noticed that the handling of the material’s translucent shades has been improved as well, in response to previous concerns that these shades were sticky. The resin was attached to tooth No. 8 with a football burnisher and cured in place (Figure 4). This process created a lingual shell upon which to build the remainder of the restoration, with the proper width and height predetermined by the diagnostic wax-up (Figure 5). 

A fine line of white tint was then applied at the incisal edge to create a “halo” on the tooth (Figure 6), and the dentin buildup was then performed with the more opaque and dark A2B shade (Figure 7). The dentin component was cured, and incisal translucent material was placed in the incisal third. These layers were followed with additional white tint to recreate the white spot effect on the patient’s other teeth. The final enamel layer was placed with A1E material, and was then shaped with an interproximal carver, a gold Almore instrument, and brushes to make the surface smooth and to bring the restoration to the proper contour (Figure 8). 

 

Figure 11. The mesial contact, surface and embrasure were created.

Figure 12. The final proximal surfaces.

Figure 13. Final contour of the restorations before finishing.

Figure 14. The completed restorations.

Figure 15. A very natural emergence profile was achieved.

Following completion of tooth No. 8, tooth No. 9 was treated similarly. Celluloid strips (Epitex clear matrix [GC America]) were placed to protect the adjacent teeth during etching and bonding, then removed following curing of the bonding agent. Composite resin was again placed first in the lingual matrix (Figure 9), then brought to the teeth and attached with a football burnisher (Tarno hac No. 6 [S.S. White]) and a brush to create the lingual shelf. A metal matrix (Original Tofflemire matrix band No. 1, .0015 in [Water Pik]) was placed and the distal contact and surface were built with A1E material (Figure 10). The same process was then used to create the mesial contact, surface and embrasure (Figure 11).


With the lingual, mesial and distal components in place (Figure 12), the dentin buildup was performed with A2B material. The dentinal lobes were shaped and cured, and an incisal halo was again created using white tint. Clear translucent material was used in the incisal third between the dentinal lobes, and white tint was then applied and cured. The final layer of A1E was placed and shaped as described for No. 8 (Figure 13). 

Finishing was performed with Sof-Lex Contouring and Polishing Discs, which were used to open up the incisal embrasures and refine the incisal contour and length. Surface anatomy was refined with a fine diamond (8862-014), and a No. 12 scalpel blade was used to remove excess material at the gingival as well as to refine the embrasures. A series of coarse, medium and fine polishers was then used, and an aluminum oxide polishing paste completed the finishing procedures. 
The completed restorations showed a very natural emergence profile and the overall match to the patient’s teeth was excellent (Figures 14 and 15). The patient was very pleased with the final result and felt confident heading in to his graduation. Despite the success of this treatment, the patient understood that the area must be monitored carefully in the future due to the trauma the teeth suffered. However, if tooth No. 9 remains vital, it is hoped that these restorations will serve for a number of years.

 

DISCUSSION
Composite resin is an appealing restorative option, especially for young patients. While conservative, the material can still provide a very good aesthetic outcome. The additional time demand demonstrated in this case also illustrates an important benefit of composite—it can be used to quickly create large restorations that help patients feel confident in their appearance. Rather than being fitted with a temporary crown for his graduation, this patient was able to attend his event with a lifelike final restoration in place.


As seen here, careful shade selection and technique throughout the restorative process can help assure a natural-looking result. The effort is well worth it, however, as the wear properties and strength of this nanocomposite material will serve the patient nicely over the coming years. 

As a longtime user of the Filtek line of restoratives, and now the recently introduced Filtek Supreme Ultra Universal Restorative material, I have become very familiar with its properties. In my opinion and clinical experience, the most recent advances have made it more clinically useful than ever.

 


References

  1. Lambrechts P, Vanherle G. Structural evidences of the microfilled composites. J Biomed Mater Res. 1983;17:249-260.
  2. Drummond JL. Cyclic fatigue of composite restorative materials. J Oral Rehabil. 1989;16:509-520.
  3. Ferracane JL, Condon JR. In vitro evaluation of the marginal degradation of dental composites under simulated occlusal loading. Dent Mater. 1999;15:262-267.

Dr. Bergeron graduated from Laval University (Québec, Canada) in 1993, where she also completed an Advanced Education in General Dentistry program the following year. She received a Certificate in Operative Dentistry and a Master of Science degree from the University of Iowa in 1999, after which she taught as an associate professor at the Faculty of Dentistry of Laval University from 1999 to 2007. She joined the department of Operative Dentistry at the University of Iowa in 2007 as clinical associate professor where she currently teaches undergraduate and graduate students. Dr. Bergeron maintains an intra-university practice limited to operative dentistry with a strong emphasis on aesthetic dentistry. Her primary interests are in the areas of aesthetics, composite resins, dental adhesion and minimally invasive dentistry. She is involved in giving continuing dental education courses, lectures and hands-on programs, to professional organizations and study clubs internationally. She can be reached via e-mail at cathia-bergeron@uiowa.edu.

Disclosure: Dr. Bergeron has disclosed that the composite and adhesive materials for this case were made available for use at no charge by 3M ESPE. Their support is hereby acknowledged and appreciated.