Direct Anterior Restorations—Aesthetics and Function
Since their introduction (Bowen 1956), composite restorations have become increasingly more important in the treatment of anterior and posterior teeth. Skillfully placed composite restorations can be superior to indirect restorations as far as their natural appearance is concerned (Buda 1994) and at the same time they can withstand the occlusal forces. The adhesion of the resin to both dentin and enamel makes it possible not only to restore teeth but also to fundamentally change them. Only little tooth substance needs to be removed for composite restorations. The margins can be gap-free, preventing bacterial penetration. Composites belong to the most important materials in cosmetic dentistry (Christensen 1995b). They can restore fractured or decayed anterior teeth cosmetically, they can close diastemas, and they can alter the color of the teeth. A person’s whole appearance can be improved through a combination of bleaching, ceramic veneers, and composite restorations.
Indications for Composite Restorations
To restrict the loss of tooth substance, one should prepare as conservatively as possible. The younger the patient is, the more important it is to minimize the loss of enamel and dentin. Direct composite restorations are the most conservative material available in present-day aesthetic dentistry. The age of the patient should not affect the use of composites.
Selecting Which Teeth to Restore
Small defects can be treated with small fillings, particularly if the tooth is intact and is aesthetically acceptable. As far as larger defects or poor aesthetics of the remaining tooth substance are concerned, an indirect ceramic restoration or an all-ceramic crown should be considered.
The opinions of both patient and dentist should be considered when drawing up the treatment plan. Have both decided on an aesthetic goal, or is the objective only to restore the defect? The higher the aesthetic goal, the more extensive the restorations may have to be.
Composites do not resist high occlusal forces. If the natural tooth substance has been destroyed due to occlusal force, one should use conventional restorations, such as ceramics or metal. Cohesive and adhesive fractures can appear with direct composites. The risk of fracture can be reduced if the enamel area is increased in an attempt to increase the bonding area with the composite. The most stable resin should be used.
The dentist usually chooses the material that fulfills the aesthetic needs, has sufficient occlusal stability, and is easy to process. Hybrid composites are most frequently used because of their strength and surface smoothness. They are available in different shades, opacities, and qualities—from very rigid to fluid. Microfilled composites are chosen primarily when one wants to simulate the appearance of enamel.
Many studies show that bonding systems bond to enamel and dentin with sufficient strength. By bonding, cohesive fractures are avoided in the tooth or in the composite restoration. Bonding to enamel is reliable and durable.
All margins must be plaque-free. In vitro tests show a decrease in marginal leaching when the composite is bonded to dentin. Dentin margins need to be observed more closely due to the risk of plaque accumulation and caries. Instructions regarding oral hygiene are crucial, particularly when composites are used.
The Ability of the Dentist
Aesthetic or cosmetic dental treatments are the plastic surgery of dentistry. The dentist’s understanding of shape, proportion, color, material, and the psychological effect of aesthetic dentistry are essential for diagnosis and treatment. The dentist must model the appearance of the teeth so that it corresponds to the physical and psychological requirements of the patient.
Direct composites are more advantageous than indirect fillings. Patients often choose composites to avoid high expenses, even if they are informed about the inferior durability in comparison to other restoration types.
Choosing a Composite
Hybrid composites are chosen because of their high stability and hardness. Microfilled composites are easier to polish. However, they are more susceptible to fractures and the so-called sandwich technique is often used to cover the hybrid composite. By doing so, the stability of the hybrid composite can be combined with the ename appearance of the surface of the microfilled composite. Microfilled composites are also used for fillings with little stress and on facial surfaces where an enamel look and high polish are important. The differences He in the shades, the opacity, and the processing. The dentist should choose the composite that gives the best aesthetics and fulfills the functional requirements.
Clinical Application of Composites
Placing the Composite
1. Determining Color
The color of the tooth must be decided before it is isolated, while it is still moistened with saliva. Commercial shade guides do not usually show the real tone. The use of specially prepared shade guides, made from the composite used, makes it possible to improve color selection. Teeth appear polychromatic through the deeper layers of dentin covered with translucent enamel. The color at the gingival margin can be distinguished from areas of the middle of the tooth as well as from the proximal and incisal regions.
Selecting and placing the individual color layers and changing opacity requires careful analysis and great skill (Buda 1994). Composites transfer color and light unevenly on enamel and dentin. The irregularities of the natural tooth should be reproduced as close as possible and to achieve this the dentist must place layers of different color tones. Hybrid composites appear like dentin, while microfilled composites imitate the enamel better.
Several layers of composites or color tones can be placed without losing adhesion or stability, as long as the surface of the polymerizing composite has a moist oxygen-inhibited layer.
2. Field Isolation
Saliva and blood components decrease the bonding ability to the tooth. A rubber dam is the most effective method to avoid contamination with saliva. Drawbacks of this method can be an inferior view and decreased access (Knight et al. 1993). Alternative isolation methods include cheek retractor, retraction cords, and suction, methods that are often sufficiently effective if they are used properly. However, each of these methods must be regarded as compromises in comparison with the absolutely dry field that can be achieved with a rubber dam. The dentist must always guarantee that during all procedures the tooth and the partly finished restoration are free from contaminating saliva.
4. Adhesion to Enamel and Dentin
As was shown in the chapter on bonding, enamel and dentin are conditioned with phosphoric acid. Both tooth structures are etched and then rinsed with water. The primer and the adhesive are placed on enamel and dentin according to manufacturer’s instructions. The correct procedure is decisive for the quality of the margins and the bonding of the restoration.
Fifth-generation dentin adhesives are suitable for direct composite restorations. The dentist and the assistant should consider the following:
The teeth must be kept moist. Directly before placing the adhesive, open the bottle (the solvent acetone evaporates immediately), place the adhesive on an applicator, close the bottle immediately, briefly dry the tooth, and place the adhesive, wait for 20 seconds (the adhesive must penetrate into all structures and the solvent must evaporate), blow lightly, and polymerize. Always place a second layer.
5. Placing the Restoration
Principles of proper composite placement: