Oral Health Group
Feature

Free Hand Bonding of a Discoloured Central Incisor

April 1, 2003
by Marcos Vargas, DDS, MS


One of the greatest challenges in restorative dentistry is achieving natural aesthetics of the single anterior tooth. Matching the hue, chroma, and value, along with the proper contour takes artistic skill. Communicating the proper anatomy, color, opacity, translucency and polychromatic variations can be a frustrating experience for the dentist and laboratory technician.

Chair side composite restorations provide the clinician with greater control over the restorative process by allowing incremental build up and sculpting of the final restoration to the desired morphology and color.

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Improvements in composite technology have helped dentists achieve polychromatic restorations that more closely resemble the optical properties of dentin and enamel, but with less invasive preparations.1

The choice between a direct vs. an indirect restorative approach with composite resins depends on the specific case and personal preference of the dentist.

Patient demand for aesthetic dentistry with minimally invasive procedures has resulted in the extensive utilization of free hand bonding of composite resin to anterior teeth.2

This article presents a technique to mask a dark central incisor with a conservative preparation and the use of opaquers, hybrid, and microfill composites.

CLINICAL PROCEDURE

The patient presented with a discolored right central incisor and disto-facial composite resin. The patient was given different treatment options, form full coverage crown, porcelain veneer, or direct resin veneer. After discussing the options and benefits of each, the patient elected to have the most conservative treatment done which was the direct resin veneer.

Anytime you are dealing with a discolored tooth, the most difficult aspect to achieve is the correct value of the tooth. This is the most important of the color dimensions of hue, chroma, and value.3 The value can be defined as the “brightness” of color.4 The selection and variation of the composite resin that reproduces the “artificial enamel layer” is a principal determinant of the value of a restored tooth.

Figure one shows the pre-operative smile of the discolored right central incisor. The tissue health of the patient is impeccable. At the cervical of the tooth you will notice the higher chroma and discoloration which will get darker the deeper the preparation goes (Fig. 2).

Prior to tooth preparation a small piece of gingival retraction cord was placed. Depth cutters from the Nixon Brasseler kit were used to achieve an approximate depth of 0.5mm. The cervical chamfer was placed following the free gingival margin from papilla tip to papilla tip with a long tapered diamond (Fig. 3).

The “total etch” technique was utilized due to its ability to minimize the potential of microleakage and enhance bond strength to dentin and enamel.5 The tooth was etched for 15 seconds with 37.5% phosphoric acid gel, rinsed for 15 seconds and lightly air thinned, keeping the tooth slightly moist (Fig. 4).

A hydrophilic adhesive agent, OptiBond Solo was applied in numerous coats, air thinned and light cured for 20 seconds.

In order to neutralize the dark shade at the cervical, an opaquer was used. This will have a tendency to increase the value of the final restoration. Without the opaquer the final restoration may be lower in value, with a gray tone. Pink opaque (Cosmedent) was placed directly on the tooth and thinned out toward the incisal edge (Fig. 5). This will do a great job of blocking out the underlying dark color, without making it too bright.

The development of the dentin layer was achieved by applying a hybrid composite (Renamel, Cosmedent, Inc.) with an IPC instrument and smoothed out toward the margins (Fig. 6). This layer must be thin enough to allow room for the microfill layer on the surface. The hybrid is used because of its ability to block out dark underlying color. It is more opaque then the microfill, thus keeping the value at the proper level.

To achieve the high luster of enamel, a microfill composite (Renamel, Cosmedent, Inc.) was placed over the hybrid layer by sculpting and brushing the material over the entire facial surface (Fig. 7). The final layer was slightly over contoured to allow sufficient thickness for contouring and polishing (Fig. 8).

The initial contouring was performed using a series of finishing disks (Soflex, 3M) to define the embrasures and smooth any rough surface irregularities (Fig. 9).

A fine grit flame shaped diamond is used to develop surface characterization and texture. This will allow the operator to develop secondary anatomy. Secondary anatomy allows for proper light deflection (Fig. 10).

In order to polish the interproximal areas and remove any residual flash, Epitex strips (GC America) were used in a shoe-shine motion from course to fine (Fig. 11).

The final luster was placed using D-Fine polishing points and cups (Figs. (12 & 13).

CONCLUSION

Advances in adhesive dentistry have enabled dentists to use free-hand bonding as an everyday part to their practice. The techniques are easily learned, and direct composite restorations are an efficacious means for restoring various anterior conditions. The final restoration is shown in Figures 14 & 15. A step by step method and a clear understanding of the materials and process is all that is required to achieve results that will exceed your patients expectations.

Marcos Vargas is graduate program director, University of Iowa College of Dentistry, Operative Dentistry Department. He lectures on adhesive dentistry.

Oral Health welcomes this original article

REFERENCES

1.Miller M. Microfill. In: Reality 1998. 12th ed. Houston, TX: Reality Publishing, 290.

2.Dietschi D. Free-hand composite resin restorations: A key to anterior aesthetics. Pract Periodont Aesthet Dent 1995; 7(7):15-25.

3.Touati B, Miara P, Nathanson D. Esthetic Dentistry & Ceramic Restorations. London, UK: Martin Dunitz, 1999:39-60.

4.Baratieri LN. Esthetic Principles. Sao Paulo, Brazil: Quintessence Publishing, 1998:48.

5.Kanca J. Improving bond strength throughout etching of dentin and bonding to wet dentin surfaces. J Am Dent Assoc. 1992: 123(9):35-43.