Aesthetics

Enhancing Smiles Using Microhybrid Composite Systems

Dentistry Today September 1, 20039 Mins read1k Views

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Direct-bonded anterior composite systems available today allow dentists to create the illusion of tooth structure and provide patients with conservative, beautiful restorations. One of the recent “new” categories of composites is the microhybrid composite resin. There are a number of improvements of composites in this category that make microhybrid composites an excellent choice for aesthetically restoring teeth. These materials are basically hybrid composites in composition. Therefore, they have excellent strength characteristics.^1-3 Although microhybrids are similar to hybrids, they differ in their particle size. Whereas hybrids are generally 1.0 to 3.0 µm in average particle size, microhybrids are on average 0.4 µm in particle size. This reduction in particle size enhances polishability.^1-4 Furthermore, the new microhybrids are being designed to have shades outside of the traditional Vita shade range. These new microhybrid systems are available in not only body (dentin) shades, but they also have numerous translucent and opaque shades. This allows the dentist to recreate tooth structure in a manner that is similar to how a ceramist creates a crown or veneer in porcelain.^1-3

There are numerous examples of microhybrids available on the market today. Some of the more popular are Point 4 by Kerr, Esthet.X by DENTSPLY Caulk, Vit-l-escence by Ultradent, Venus by Heraeus Kulzer, Miris by Coltene, and Filtek Supreme by 3M ESPE.

In clinical application, microhybrid composites provide the dentist with a predictable and conservative way to restore many different clinical situations. The following case studies will demonstrate just a few of the ways that microhybrid composites can be used to restore patients’ teeth and enhance their smiles.

CASE 1
A 32-year-old male presented with a chipped incisal edge on tooth No. 9 (Figure 1).

Using 3 different shades of a microhybrid composite (Opaque Snow, A1, and TransIce, Vit-l-escence, Ultradent), it is possible to create an invisible restoration. Figure 2 is a 1-year postoperative photograph of the restoration. This demonstrates the strength of the material over time, the ability to create an excellent color match, and the maintenance of the polish of the material between dental visits.


Figure 1. A fractured incisal edge on tooth No. 9.	Figure 2. Three different shades of a microhybrid composite are used to restore tooth No. 9.

CASE 2
A 15-year-old patient presented after completion of orthodontic therapy (Figure 3). The patient and parents requested to have the diastema between teeth Nos. 8 and 9 closed.

A number of treatment options were available. It is important to evaluate the case closely. After clinical evaluation and consultation with the orthodontist, it was agreed that the patient’s problem was associated with an arch width/tooth size discrepancy. Her teeth were not wide enough for her arch. To be more accurate, her maxillary lateral incisors were too narrow and too short.


Figure 3. A young patient would like to aesthetically enhance her smile.	Figure 4. Minimal preparations can be used when restoring teeth with composite.

Figure 5. A “lingual shelf” is created using an opaque shade of a microhybrid composite.	Figure 6. A final layer of translucent microhybrid composite will help to create lifelike vitality.

Figure 7. The 6-month postoperative photograph demonstrates the ability of microhybrid composites to create lifelike restorations.	Figure 8. Upon completion of orthodontics, a young patient wishes to close the diastema distal to tooth No. 10.

The patient and parent were advised of the clinical findings. Two treatment options were given. The first option was to use composite and direct bond the mesial aspects of teeth Nos. 8 and 9. The second option was to conservatively place direct-bonded veneers on teeth Nos. 7 through 10 to create a more ideally proportioned smile. Option 1 was certainly the most conservative option. However, by only closing the diastema, the central incisors, which were already too wide, would become even wider. This would result in the visual exaggeration of the appearance of the central incisors.

Option 2 was recommend because by using direct-bonded veneers on the maxillary lateral incisors, it would be possible to make them longer and wider. This would create an end result that would appear more natural and proportionate.

Using a self-limiting depth cutting bur (No. 828-022, Axis), the facial surfaces of teeth Nos. 7 through 10 were uniformly reduced 0.3 mm. Additionally, it was necessary to open the proximal contacts between the central and lateral incisors. This would allow for the placement of composite on the mesial of the lateral incisors to achieve a wider, more proportionate tooth. Figure 4 shows the final conservative preparations.

The teeth were isolated using orthodontic retractors. After etching and bonding tooth No. 9, the microhybrid composite was added to the tooth. The first step (Figure 5) was to begin to close the diastema. An opaque shade of composite (OpaqueSnow, Vit-l-escence, Ultradent) was placed using techniques taught by Mopper⁵ and Nash.⁶ The opaque composite was placed so that it replaced natural lingual enamel. The opaque composite blocks out the dark color from the back of the mouth, which prevents the final restoration from looking too gray.

A thin layer of the body shade of composite was then added. Lastly, a final translucent layer was place on the surface of the restoration (TransGrey, Vit-l-escence, Ultradent) (Figure 6). The translucent layer of composite is virtually clear. This translucent composite will simulate the optical properties of enamel and give the final restoration a depth of color and create vitality in the tooth.

A 6-month postoperative photograph (Figure 7) demonstrates the excellent results that can be obtained with microhybrid composites. The direct-bonded veneers have a vitality and polish that mimic natural tooth structure. It should also be noted that a more natural proportion of the teeth^7,8 was created by adding the lateral incisors to the treatment plan.

CASE 3
A 14-year-old patient was referred by her orthodontist upon completion of her orthodontic treatment. Tooth No. 10 was proportionally narrow (Figure 8). The orthodontist and I agreed to leave the diastema distal to tooth No. 10 in order to maintain proper canine and first molar relationships.


Figure 9. Following laser gingivectomy, tooth No. 10 is prepared for a direct composite veneer using a minimal preparation design.	Figure 10. A silicone putty matrix assists with the placement of the opaque composite.

Figure 11. A final layer of translucent composite is placed.	Figure 12. At the 3-month recall, an improved smile can be seen.


Figure 13. A 20-year-old patient would like to enhance her smile.	Figure 14. Very conservative preparations are used to perform the direct-bonded procedure.

Figure 15. An opaque microhybrid composite is used to lengthen the incisal edge of tooth No. 10.	Figure 16. At the postoperative appointment, an improved smile is noted.

Although it would be possible to restore tooth No. 10 with a full-coverage crown or porcelain veneer, by using microhybrid composites it would be possible to aesthetically restore that tooth with minimal loss of tooth structure. Also, using direct composite would allow the dentist to have complete control of the color and contour as well as the ability to complete the case in one visit.

First, the soft tissue was evaluated. In order to create a more ideal final result, it would be necessary to remove a small amount of soft tissue using a soft-tissue diode laser (DioLase ST, Biolase). Using the parameters discussed by Kois⁹ and Robbins,¹⁰ a gingivectomy was performed without violating the biological width of tooth No. 10. The gingivectomy allowed for the potential to visually increase the length of the lateral incisor and also create more ideal soft-tissue contours for the distal papilla. The more ideal contour of the distal papilla would allow for the development of a natural emergence profile of the final restoration.

In the office lab, a study model of tooth No. 10 was waxed to ideal lingual and incisal contours. Using silicone putty, an impression was then made of the wax model. This silicone putty impression served as a matrix to help create the final restoration.^11-13The tooth was prepared by removing 0.3 mm of facial enamel, terminating the mesial preparation just facial to the proximal contact, terminating the distal margin at the lingual line angle, and terminating the gingival margin just short of the gingival height of tissue (Figure 9).

The preparation was acid-etched and bonded, and the silicone putty matrix was placed. The first layer of the microhybrid composite was an opaque dentin shade (Opaque A2, Point 4, Kerr) that was used to mimic the lingual enamel and block out the dark color from the back of the mouth (Figure 10). The putty matrix not only helped to create the proper width and length of the restoration, it served as a stable surface for the placement of the composite.

The putty matrix was removed, and a thin layer of body shade (A1, Point 4, Kerr) and a final layer of translucent composite (T2, Point 4, Kerr) were placed (Figure 11). The 3-month postoperative photograph (Figure 12) shows how a conservatively placed direct microhybrid composite can enhance the patient’s smile.

CASE 4
A 20-year-old patient inquired about how she could improve her smile. Tooth No. 8 had been bonded, and she was not happy with the results of take-home bleaching (Figure 13).

The patient was given several treatment options. The patient chose to have 6 direct-bonded restorations placed on teeth Nos. 6 through 11 along with some minor soft-tissue recontouring. The soft tissue was evaluated using accepted parameters9,10 to determine if it was possible to increase the length of the teeth by removing soft tissue. It was determined that it was possible to remove a small amount (1 mm on average) of gingival tissue without violating biological width.

Using a diode soft-tissue laser, the gingivectomy was carefully performed.¹⁴ Chlorhexidine solution (Consepsis, Ultradent) was used to remove the excess gingival tissue. Tooth Nos. 6 through 11 were then conservatively prepared; 0.3 mm of facial tooth structure was removed, the interproximal margins were terminated slightly facial to the interproximal contact, and the gingival margins were terminated just short of the height of the gingival tissue (Figure 14).

Using a combination of opaque, body, and translucent shades of a microhybrid composite (Opaque B2, B1, and T1, Point 4, Kerr), the 6 teeth were restored. Figure 15 shows the application of the opaque composite to the incisal edge of tooth No. 10 in order to increase the final length of the tooth. The final result is a new appearance to the patient’s smile that meets her aesthetic objectives while using minimally invasive techniques made possible by direct-bonded resins (Figure 16).

CASE 5
The aforementioned cases demonstrate how direct bonded anterior restorations can be used in elective cases. However, the same techniques can be used for conventional restorative dentistry as well.

A 43-year-old patient presented with an old, large composite restoration on tooth No. 7. The restoration had recurrent decay and a bond failure (Figure 17). Given the amount of loss of natural tooth structure, a full-coverage restoration was indicated. However, the patient’s financial constraints made a crown prohibitive for him. An alternative treatment of directly restoring tooth No. 7 using direct bonding with microhybrid composites was within the budget of the patient.

The old restoration and recurrent decay were removed, as was a small amount (0.3 mm) of facial tooth structure.¹⁵ Figure 18 shows the final preparation design. Using the techniques described for the previous elective cases (Figure 19), tooth No. 7 was recreated using a microhybrid composite (Opaque A3, A2, T3, Point 4, Kerr).

The immediate postoperative photograph (Figure 20) shows that it is possible to use microhybrid composites to create a lifelike restoration for an extensively damaged tooth.


Figure 17. Tooth No. 7 has a failing, old composite resin.	Figure 18. The final preparation design.

Figure 19. A putty matrix is used to assist with the placement of the opaque composite.	Figure 20. The immediate postoperative photograph shows the lifelike restored tooth.

CONCLUSION
These cases have highlighted the aesthetic capabilities of the new microhybrid composites when restoring teeth. It should be noted that the excellent physical and aesthetic properties of these composites make them an appropriate material choice for restoration of posterior teeth as well.

In the constantly changing world of dental materials, it is imperative that dentists continually review and research the newest materials that become available. Many of these new materials will allow dentists to improve the aesthetics and longevity of the dentistry they provide their patients. Microhybrid composites allow dentists to practice minimally invasive dentistry and create lifelike restorations that will maintain their polish over time and have excellent strength characteristics.

References

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Dr. Radz practices in Denver. He is a graduate of the University of North Carolina School of Dentistry and has completed both AEGD and GPR residency programs. In the last 8 years, he has lectured extensively and has published more than 80 articles focusing on aesthetic materials and techniques. He recently served as the chairman of the American Academy of Cosmetic Dentistry’s 2003 Annual Scientific meeting. He can be contacted at radzdds@aol.com.