Written by Krasimira Krasteva, DDS Thursday, 01 January 2004 00:00
Conservative aesthetic anterior tooth restoration is one of the greatest challenges for dentists in clinical practice. The evolution of techniques and materials for direct and indirect restorations with composites and ceramics allows clinicians to recreate both tooth function and aesthetics more optimally than ever before. Patients expect contemporary dentistry to provide restorations that reproduce natural beauty while ensuring stability and functionality. In achieving this goal, the dentist faces numerous dilemmas. Tooth shape and size are both subordinated to the anatomical peculiarities of the jaws, face, lips, and nose. However, using proper technique, one can achieve excellent aesthetics without threatening the correct function.
Patients with damaged anterior teeth and affected incisal edges/angles seek dentists' help every day. The dentist is obligated to suggest all appropriate treatment variants.1-3 Thanks to modern adhesive dentistry, direct-bonded composite is a viable treatment in many cases, providing a stable bond between dental tissues and built-up composite material that is sufficient to withstand masticatory loading while providing excellent aesthetics.
Contemporary composites meet the requirements for layered structure of the tissues such as dentin, enamel, and transparent.4 Their different densities enable the restoration of the smallest details in any individual clinical situation, aesthetically reproducing the color of adjacent natural teeth. The conservative nature of direct methods of construction that are aimed at preserving intact tooth structure is a distinct advantage. The procedure can be accomplished in-office in one visit, which is efficient for the dentist while saving the patient time and money.
This paper presents a case report that describes a practical approach to the direct aesthetic anterior restoration using a new-generation, light-cured composite resin.
|Figure 1. Appearance of dentition prior to treatment.|
A 30-year-old female patient presented with upper central incisors that had been fractured years ago and restored using dentin retention pins and composite (Figure 1). The clinical examination revealed poor aesthetics and deterioration and discoloration of the restorations. There was a clear distinction of the color of the restoration, especially at its borderline with tooth tissues. The teeth themselves were vital and without any degenerative alterations. There was an orthognathic condition that resulted in midline discrepancy of the upper and lower jaws. No significant tooth abrasion could be detected.
The patient desired a new restoration that could satisfy her aesthetic and functional needs. She insisted that treatment be conservative, and this determined the choice of the direct composite construction. The newer generation adhesive materials are less invasive and easy to apply under such conditions. The decision was made to use the aesthetic direct composite restoration using the self-etching Clearfil SE Bond adhesive system and Clearfil ST light-cured restorative composite resin (Kuraray). (Note: in the United States, Clearfil ST is named Clearfil APX).
CLINICAL RESTORATIVE PROTOCOL
A clinical management plan was elaborated after careful examination of the patient and selection of both method and materials. It comprised the following stages: (1) defining the restoration color; (2) tooth color and contour design; (3) ultraconservative preparation; (4) adhesive processing of tooth surfaces; (5) construction; and (6) finishing and polishing.
Because the procedure for restoring both central incisors was identical, only the restoration of the right central incisor is described.
Color and shade selection is extraordinarily important, although it remains insufficiently understood and is difficult to accomplish. Several factors such as the patient's appearance, the time of day and the intensity of solar radiation, the type of light source, and the color of the adjacent objects may exert a definite effect on the selection of shades. All of these factors exert influences upon the dentist's color perception.5 In addition, there exists a fluctuation of eye retinal sensitivity. After approximately 15 seconds a retinal adaptation sets in, resulting in a substantial diminution of color discrimination.
|Figure 2. Digital design of tooth colors.|
Digital measurement provides the most reliable information about the hue and chroma composition of the corresponding tooth color. Therefore, a Digital Shade Guide DSG 4 (Rieth, Germany) apparatus was used in the present clinical case. Prior to color determination, the teeth should be cleaned with pumice to remove any surface depositions that could hamper the exact color estimation. A patient file was prepared by the DSG 4 apparatus software. The tooth under measurement was slightly moistened. The optical probe of the DSG 4 was placed perpendicularly on the tooth and held motionless until the values were read. The measurement was performed several times at different areas. In this way, the patient's color file was created and the primary tooth color of A2 was defined (Figure 2).
Color and Contour Design
The determination of the color and contour design was an important stage of the restoration process. The ideal length and width of the upper central incisors should be in concordance with the correct proportion between length and width that was done using a measurement line and caliper. Factors such as shape and size of adjacent teeth, line of smile, facial shape, occlusion, etc, are of great importance for the subjective aesthetic evaluation.
The exact selection of the primary color and subcolors defines the aesthetics of the area to be restored. It is not sufficient to establish only the hue, value, and chroma of the corresponding region; it is also necessary to describe in detail the superficial tissue. With the use of digital technology, subjective color selection is eliminated, making an accurate color match possible.6,7 Tooth angulation and position are important because they influence the manner of light reflection from the surface.
Any peculiarities of the tooth surface, such as hypoplastic spots, recession, color effects, etc, should be reproduced. That is why they should be plotted on the color and contour design. This facilitates the determination of the palette of necessary colors and the type of restorative materials to be used. In the present case, based on the result from the digital color file concerning the sum of colors and specific facts pertaining to the light-cured composite material to be used, a color and contour design was prepared (see diagram).
|Figure 3a. Conservative preparation of the right central incisor.||Figure 3b. Conservative preparation of the left central incisor.|
Secondary caries was present and carefully removed, preserving the intact zone by means of a carbide bur in a slow-speed, contra-angle handpiece. Then the enamel was shaped using a diamond finishing bur to a depth of 1.5 to 2 mm at the cervical area to achieve a smooth transition of the restoration to the tissue (Figures 3a and 3b). Contemporary adhesive dentistry enables the creation of a quality, stable bond between the dental tissues and buildup material,8 allowing conservative tooth preparation with no need for additional retention.
The Clearfil SE Bond self-etching adhesive system was used in this case. Its water-based, self-etching primer is "pulp-friendly,"9 a benefit in terms of postoperative sensitivity. The self-etching primers have successfully been used in operative dentistry for binding of composite to dentin and enamel, combining the steps of etching and primer processing. This shortens and simplifies the bonding procedure for the dentist. This advantage is particularly important in cases with affected dentin because overdrying induces collapse of the collagen network and substantially compromises adhesive bonding.
The adhesive technique required good isolation of the working field; a rubber dam was preferred. The prepared tooth surface was treated with Tubolicid (Dental Therapeuticus, Sweden) to remove the smear layer resulting from tooth preparation. If the smear layer is not removed, the adhesion could be affected. Then the surface was carefully dried. A celluloid matrix band fixed by small cotters was placed around each treated tooth.
|Figure 4. Application of Clearfil SE Bond self-etching adhesive system.|
Both enamel and dentin were covered with a Clearfil SE Primer layer (Figure 4) using a disposable microbrush and left for 20 seconds. After surface conditioning, a mild, oil-free flow of air was applied to vaporize the volatile components. The time for conditioning and drying should be strictly observed in order to achieve an optimal adhesion. The contamination of the layer of primer by blood or saliva should be avoided. A thin layer of Clearfil SE Bond was gently and evenly distributed on the primer layer, avoiding an intensive stream that could lacerate the thin film of bonding agent and destroy adhesion, and was light- cured for 10 seconds.
Success or failure in achieving optimum aesthetics depends on the correct understanding of exact color matching and structure of composite resins. This contributes to the creation of clinically and aesthetically acceptable restorations that have the correct combination of enamel and dentin shades.
The first step in the restoration of the adhesively prepared tooth structure was to restore the shape and volume of basic dentin in concordance with the patient's natural tooth appearance and age. Clearfil ST OA2 Opaquer was placed on the tooth dentin because in the middle part of the tooth a greater density should be created. This was done layer by layer and very carefully to avoid an overenlargement of this layer, which could hamper transparency. Data from the patient's computerized color file were used in the subsequent steps. Clearfil ST B2 was placed on the lingual side layer by layer to obtain the basic shades and enamel translucency. Each layer was light cured on the facial side. The transition between every layer should be smooth to prevent formation of air bubbles. There was double light reflection from the proximal surface and the incisal edge, therefore a light color was used.
|Figure 5. Preparation of the composite.|
The construction of the facial surface began with Clearfil ST A2 layer placement without reaching the incisal edge and proximal surface (Figure 5). Mamelons were formed in this layer to induce the so-called "halo" effect. To that purpose, light-curing coloring agents were used. Lingual light-curing was carried out. The enamel layer completed the final tooth contour. In this case, Clearfil ST Enamel was applied. It is important to note that light-curing of each layer can result in the formation of a fine, noncured superficial oxidized layer that has to be carefully removed by cotton pellet. Initially, the completed restoration was light-cured on the lingual side for 10 seconds, then on the facial side for 60 seconds.
FINISHING AND POLISHING
Prior to cofferdam removal, excess composite resin was removed using a diamond bur to prevent fracture during involuntary mouth closing. Then the restoration was shaped and finished with a diamond finishing bur. Teeth were not treated at least 10 minutes after cofferdam removal to allow complete polymerization of the restorative composite resin. Otherwise, microfissures could emerge during polishing.
After checking the occlusion, the lingual surface was shaped using a flame-shaped diamond finishing bur. The anterior occlusion contacts were also controlled to avoid interferences that could destroy the restoration. The facial surface was shaped using a diamond finishing bur. The transition between the composite and enamel should be smoothed slowly until it disappears. These burs can be used without water cooling to enable a better visualization of the edges and prepared form. However, slight pressure should be exerted to avoid overheating and eventual superficial damage. Polishing bands were used for the proximal surfaces. Polishing paste and conical rubber points were properly applied. Soft and flexible polishing disks of different sizes of abrasive particles were used for even and equal polishing. Prior to using a finer disk, the composite surface should be rinsed in order to remove the larger particles remaining from the previous disk. Unpleasant white lines and occurrence of tension and fissures in the material can be prevented through less intensive and proper polishing.10
|Figures 6a and 6b. Completed restorations entirely satisfied the patient in aesthetic and functional respects.|
|Diagram. The elaboration of restoration color design contributes to the aesthetic result.|
The entire procedure of clinical restoration was repeated with the left central incisor. That is why the finishing procedures should always be preceded by copious rinsing. The completed restorations entirely satisfied the patient in both aesthetic and functional respects (Figures 6a and 6b).
The introduction of adhesive technology is a major advancement in the development of aesthetic dentistry. To achieve optimal aesthetic and functional results, the dentist is obliged to have a comprehensive knowledge of the capacities of contemporary composites, enabling him or her to offer a new direct restoration with the optical and functional properties of a natural tooth.11 Preservation of healthy dental tissues and pulp vitality represents a significant advantage for the direct methods of construction.12 The lower abrasive capacity in comparison with that of porcelain preserves the antagonist teeth.13 The restoration can be completed in one office visit, thus saving the patient time and money.
Undoubtedly, patients' aesthetic requirements will continue to rise progressively. Our task consists of the reliable imitation of the natural dentition in order to meet these expectations. Dentists should simultaneously be both artists and sculptors, reproducing natural dentition to achieve the best that modern adhesive dentistry has to offer.
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