Simple Concepts to Shape and Polish Anterior Composites to Rival Porcelain

By David Chan, DMD, AAACD

With contemporary direct composite systems, the clinician can now truly be a dental artist by conservatively and esthetically creating restorations that are so life-like that they virtually emulate the beauty of natural tooth structure.

However, rehabilitating or enhancing a smile with direct composite resins can be challenging. The task not only requires an understanding of the intricacies of shade and color selection, but also a mastery of replicating the uniqueness of natural tooth morphology and surface texture of the composite restoration. It could be debated that the most important aspect of any dental restoration is its unique morphologic shape, since a restoration with the correct anatomic shape and texture will seamlessly blend into the dentition even if there are some small shade disparities.

By essentially using only a few simple instruments and regimentally following an established work- flow of finishing and polishing, it is possible to predictably convert this morphologic concept of unique morphological shapes into reality.

PRIMARY TOOTH ANATOMY

Primary tooth anatomy simply defines the geometric shape or outline of the tooth and usually falls into three categories: square, triangular and ovoid.

TRANSITIONAL LINE ANGLES

There are three transitional line angles in maxillary anterior teeth that represent the area of transition between the two proximal surfaces and incisal surface with the facial surface. Altering the distance between the two proximal line angles gives the illusion of making the tooth appear wider or narrower. The proximal transitional line angles also influence the size of the facial embrasures.

POINT ANGLES

Point angles are the junctions of the two proximal transitional line angles with the incisal facial line angle. The point angles determine the size of the incisal embrasures, where in esthetically oriented maxillary anterior teeth grow, larger away from the midline.

SECONDARY TOOTH ANATOMY

Secondary tooth anatomy is the result of normal tooth development and refers to the facial depressions and undulations commonly found in maxillary anterior teeth that give rise to the facial contours and accentuate the facial lobes.

TERTIARY ANATOMY

This commonly refers to perikymata and various forms of surface stippling usually present in younger teeth. This is commonly lost in mature teeth or those that are in function longer due to frictional forces that erode away this morphology over time.

ANTERIOR COMPOSITE FINISHING WORKFLOW

Suggested armamentarium for creating tooth anatomy and finishing composite resins that virtually mimic natural teeth are:

• Abrasive discs
• Fine diamond burs
• Aluminum oxide finishing cups and discs
• Diamond impregnated A.S.A.P® Polishers and Brushes and cotton wheel and aluminum oxide polishing paste

Optimal finishing and polishing of a composite restoration is probably the number one secret for a seamless integration of the restoration into the native dentition, especially when restoring a single tooth.
The technique described here is a very simple procedure the clinician can use to achieve a very life-like tooth appearance, with only subtle modifications necessary from patient to patient due to the variability of natural human tooth anatomy and luster of the native enamel. Armed with a sound knowledge of human tooth morphology, here is an effective, systematic approach to use.

STEP 1

Once the last layer of resin has been light-cured, use a coarse grit abrasive disc followed by a medium grit disc (such as ContoursTM Finishing and Polishing Discs from Clinician’s Choice®, Sof-LexTM Discs from 3M or FlexiDiscTM from Cosmedent) (FIG. 1) to develop the primary anatomy of the tooth based on proximal and cavo-surface line angles outlined in pencil on the restoration and adjacent tooth. Properly contour the following:

• Incisal edge position
• Three facial planes
• Location of the proximal line angles
• Location of the point angles
• Determine how open or closed the facial and incisal embrasures are
• Use a sharp pencil to visualize and if needed to modify or move the location of the proximal line angles with the finishing discs.

It is very important to keep in mind that the proximal line angles, point angles, facial embrasures, and incisal embrasures all influence the appearance of the tooth and are dependent on one another.

STEP 2

Once the primary anatomy has been obtained with the use of rotating discs, the secondary anatomy can be developed.

A very effective method of placing secondary anatomy in a tooth is to visualize it first by drawing the locations onto the tooth with a pencil.

Once the areas have been identified, use a single flame-shaped fine diamond bur (I use the Brasseler F8888.31.012) to create the depressions and at the same time accentuate the proximal/middle developmental lobes. (FIG. 2)

A series of 90 micron aluminum oxide diamond impregnated set of rubber points and cups (ContoursTM Coarse Anatomy Trimmers from Clinician’s Choice® or Astropol® from Ivoclar Vivadent) with water can be used to smooth out any surface irregularities and/or scratches left by the fine diamond flame shape bur to create a subtle, naturally flowing appearance of the secondary anatomy. (FIG. 3)

STEP 3

The anatomy and scratches can be further refined with the 44 micron purple A.S.A.P.® Pre-polisher and 6 micron A.S.A.P.® Final High Shine Polisher (diamond impregnated A.S.A.P. Polishers, Clinician’s Choice®) as these are very effective in accessing intricate parts of teeth without degrading the anatomy. (FIG 4)

The use of edible silver glitter (available at most cake-decorating establishments) is a quick and effective way to verify the anatomy and ensure that all scratches are removed. (FIG. 5)

After applying the glitter with a make-up brush, the silver glitter will quickly show areas that need additional smoothing or blending of the surface texture for a restoration that appears natural.

Tertiary anatomy generally presents in the form of perikymata or surface stippling that may or may not be present depending on the genetic variation of the patient or the age of the tooth. These characteristics are erased by the friction of mastication forces over time. Perikymata can be very simply placed by running a fine diamond bur at stall-out speed with an air turbine, or using an electric handpiece such as a Bien-Air EVO system at a very low RPM, in a mesiodistal direction on the facial surface. (FIG. 6)

Surface stippling, on the other hand, can be placed with a fine football high-speed diamond bur using a pecking motion on the facial surface where this effect is desired.

STEP 6

The final polish will depend on the desired degree of luster or that which matches the native dentition if restoring only a single tooth. It is paramount to adhere to this workflow and as the fine natural anatomy created thus far can be easily erased with the overuse of abrasives polishing.
A lower surface luster can be achieved by using any silicone-impregnated brush with aluminum oxide paste (EnamelizeTM from Cosmedent) over the entire surface of the composite resin. If a very high degree of luster is desired, a cotton wheel along with the aluminum oxide polishing paste will give a shine that rivals the highest natural luster of enamel that exists.

CONCLUSION

The systematic approach described here can simplify the understanding of each morphologic component of maxillary anterior teeth. Armed with this knowledge, the clinician can use the procedure and tools discussed to create anterior composite restorations that mimic the beauty of natural tooth structure.

ABOUT THE AUTHOR

David Chan earned his DMD degree in 1989 from Oregon Health Sciences University. He maintains a full-time practice focused on cosmetic and comprehensive dentistry located in Ridgefield, Washington. David currently serves as the President of the American Academy of Cosmetic Dentistry, as director at the Center for Dental Artistry and a Clinical Instructor at the Kois Center in Seattle, Washington.

He is an Accredited member of the AACD and has been published widely in peer reviewed dental articles, including several articles in the prestigious “Journal of Cosmetic Dentistry”. In addition, David travels nationally/internationally giving lectures to dentists on comprehensive esthetic dental care and serves as a key opinion leader for many dental products companies.