Composite restoration is the most demanding procedure in dentistry. There are numerous composite materials and a wide variation of restorative defects. Understanding an extensive amount of information is essential to obtain proper and long lasting health, function and esthetics. This article will organize a list of factors which are required for proper composite restoration. Figure 1.

Composite restoration is used to restore defects in tooth color, shape or position caused by developmental problems, acute or chronic trauma, or caries. Restoration can be simple or complex. A simple restoration may involve a surface defect while a complex case may involve complete smile design. A dentist is responsible for understanding

1. Smile Design

2. Color and Color Analysis

3. Tooth Color

4. Tooth Shape

5. Tooth Position

6. Esthetic Goals

7. Composite Selection

8. Tooth Preparation

9. Bonding Techniques

10. Composite Placement

11. Composite Sculpture and

12. Composite Polishing to properly restore anterior teeth with composite:

1. SMILE DESIGN

A dentist must understand proper smile design so composite restoration can achieve a beautiful smile. This is true for extensive veneering and small restorations. Factors which are considered in smile design include A. Smile Form which includes size in relation to the face, size of one tooth to another, gingival contours to the upper lip line, incisal edges overall to the lower lip line, arch position, teeth shape and size, perspective, and midline. B. Teeth Form which includes understanding long axis, incisal edge, surface contours, line angles, contact areas, embrasure form, height of contour, surface texture, characterization, and tissue contours within an overall smile design. C. Tooth Color of gingival, middle, incisal, and interproximal areas and the intricacies of characterization within an overall smile design.

2. COLOR AND COLOR ANALYSIS

Color is a study in and of itself. In dentistry, the effect of enamel rods, surface contours, surface textures, dentinal light absorption, etc. on light transmission and reflection is difficult to understand and even more difficult replicate. The intricacies of understanding matching and replicating hue, chroma, value, translucency, florescence; light transmission, reflection and refraction to that of a natural tooth under various light sources is essential but far beyond the scope of this article.

3. TOOTH COLOR

Analysis of color variation within teeth is improved by an understanding of how teeth produce color variation. Enamel is prismatic and translucent which results in a blue gray color on the incisal edge, interproximal areas and areas of increased thickness at the junction of lobe formations. The gingival third of a tooth appears darker as enamel thins and dentin shows through. Color deviation, such as craze lines or hypocalcifications, within dentin or enamel can cause further color variation. Aging has a profound effect on color caused by internal or external staining, enamel wear and cracking, caries, acute trauma and dentistry.

4. TOOTH SHAPE

Understanding tooth shape requires studying dental anatomy. Studying anatomy of teeth requires recognition of general form, detail anatomy and internal anatomy. It is important to know ideal anatomy and anatomy as a result of aging, disease, trauma and wear. Knowledge of anatomy allows a dentist to reproduce natural teeth. For example, a craze line is not a straight line as often is produced by a dentist, but is a more irregular form guided by enamel rods.

5. TOOTH POSITION

Knowledge of normal position and axial tilt of teeth within a head, lips, and arches allows reproduction of natural beautiful smiles. Understanding the goals of an ideal smile and compromises from limitations of treatment allows realistic expectations of a dentist and patient. Often, learning about tooth position is easily done through denture esthetics. Ideal and normal variations of tooth position is emphasized in removable prosthetics so a denture look does not occur.

6. ESTHETIC GOALS

The results of esthetic dentistry are limited by limitations of ideals and limitations of treatment. Ideals of the golden proportion have been replaced by preconceived perceptions. Limitations of ideals are based on physical, environmental and psychological factors. Limitations of treatment are base on physical, financial and psychological factors.

7. COMPOSITE SELECTION

Esthetic dentistry is an art form. There are different levels of appreciation so individual dentists evaluate results of esthetic dentistry differently. Artistically dentists select composites based on their level of appreciation, artistic ability and knowledge of specific materials. Factors which influence composite selection include require‑.rents for A. Restoration Strength, B. `'Fear and C. Restoration Color.

A. Restoration Strength is determined to be sufficient if force applied to a tooth is resisted by a restoration. Measuring sufficient restoration strength is done by examining and comparing direction, magnitude and frequency of applied force to resistance provided by material and support structure. This includes analysis of occlusion and parafunctional forces.

Material strength determines longevity of anterior composites if force is directed onto a composite portion of a restoration. Technical information which describes compressive, tensile, shear, modulus of elasticity, and the like determines the ability of a composite to resist breakdown. Increased thickness of material, ability to resist crack propagation and technique sensitivity further determines material strength.

Proper support of a composite restoration further defines resistance to force. The interrelationship of composite placement and proper support through tooth preparation determines if force onto composite is compressive, shear, tensile, or debonding. Bond strength, which is determined by technique and material used to bond and surface area bonded to, also determines resistance to forces which could debond composite from support structure. In addition, strength of support structure is important to prevent fracture of a support foundation.

A restoration is strongest if failure of resistance to force requires fracture of composite material, debonding of material and fracture of support structure . Ultimate strength determination of a restoration is often the weakest link in this chain.

B. Wear is determined by resistance to abrasive, adhesive, chemical, and corrosive wear. Additional forms of wear include hydrolysis of silane and fatigue. Composite chemical structure and filler type are primary factors which affect wear.

C. Restoration Color is determined by analysis of composite hue, chroma, value, translucency and florescence with interaction of a tooth defect. Tooth defects are classified into two major categories including those with tooth backing and those with no tooth backing. Tooth backing is determined by observing teeth from a facial view.

The back of the mouth receives little light and is considered a dark space. Restoring tooth defects with no tooth backing are influenced by this fact because composite materials which are transparent show through darkness of the back of the mouth and appear dark themselves. The influence of darkness in the back of the mouth does not exist while a patient is in a dental chair because the overhead dental light illuminates the space. A dentist must recognize this condition so when a patient stands composite does not look dark.

Blocking out the influence of darkness in the back of the mouth can be accomplished in several ways. A dentist can 1. Apply sufficient thickness of material to block out the effects of darkness. 2. Apply a translucent composite on the facial aspect with an opaque composite on the lingual with a combined thickness sufficient to block out the effects of darkness. 3. Use an opaquer within a restoration to block out the affects of darkness.

Tooth defects with tooth backing require analysis of defect color and depth. The hue, chroma, value and translucency of a defect influences the effectiveness of a composite material to block out defect color such that it does not show through composite. The depth of a defect defines the amount of material thickness which can be used to block out color. Different composites require different thickness to block out background color. This is dependant on the translucency of a composite and the hue, chroma, value and translucency of a defect. Selecting a composite or combination of composites requires knowing translucency characteristics of a composite material. Blocking out color can be achieved in the same three techniques as for tooth defects with no tooth backing except that opaquer can be applied directly onto a defect.

D. Placement Characteristics defines how easy handling characteristics are to place composite within or on tooth defects. Ideally composite should flow into small defects, not sag when in place, be sticky to a defect surface and non‑sticky to instruments.

E. Ability to Use and Combine Opaquers and Tints is important to change composite color or block out defect background effects. In addition, these materials must provide ability to produce natural characterization when desired.

F. Ease of Shaping is especially important when producing larger restorations. The ability to mold material into position, have it stay in position and not be sensitive to ambient light which would result in premature thickening is also important.

G. Polishing Characteristics defines how easy it is to polish a composite and the appearance of a polished surface. It is further important to have the ability to polish different types of surfaces such as finely contoured or highly textured.

H. Polish and Color Stability defines long term esthetic excellence. If a polished surface fades or color changes, the results of excellent dentistry diminish as well.

8. TOOTH PREPARATION

Tooth preparation often defines restoration strength. Small tooth defects which receive minimal force require minimal tooth preparation because only bond strength is required to provide retention and resistance. In larger tooth defects where maximum forces are applied, mechanical retention and resistance with increased bond area can be required to provide adequate strength.

9. BONDING TECHNIQUES

Understanding techniques to bond composite to dentin and enamel provide strength, elimination of sensitivity and prevention of microleakage. Enamel bonding is a well understood science. Dentinal bonding, however, is constantly changing as more research is being done and requires constant periodic review. Microetching combined with composite bonding techniques to old composite, porcelain, and metal must be understood to do anterior composite repairs.

10. COMPOSITE PLACEMENT TECHNIQUE

Understanding techniques which allow ease of placement, minimize effects of shrinkage, eliminate air entrapment and prevent material from pulling back from tooth structure during instrumentation determine ultimate success or failure of a restoration. It is important to incorporate proper instrumentation to allow ease of shaping tooth anatomy and provide color variation prior to curing composite. In addition, a dentist must understand placement of various composite layers with varying opacities and color to replicate normal tooth structure.

11. COMPOSITE SCULPTURE

Composite sculpture of cured composite is properly done if appropriate use of polishing strips, burs, cups, wheels and points is understood. In addition, proper use of instrumentation maximizes esthetics and allows minimal heat or vibrational trauma to composite resulting in a long lasting restoration.

12. COMPOSITE POLISHING

Polishing composite to allow a smooth or textured surface shiny produces realistic, natural restorations. Proper use of polishing strips, burs, cups, wheels and points with water or polish pastes as required minimizes heat generation and vibration trauma to composite material for a long lasting restoration.