All Shapes and Sizes

Because teeth and restorations don’t come in perfect squares, finishing and polishing products are all about diversity. Cups, discs, points, barrels … tapers, flames, bullets… bonded, coated, unbonded. Here’s how your clients pull it all together in smooth restorations.

People come in all shapes and sizes — and no two of us shine in exactly the same way. The same is true of our teeth. So when patients visit the dentist for restorative dentistry, clinicians must have the instruments, devices and abrasives on hand to create the shape and shimmer that today’s patients expect.

Through the finishing and polishing process, tooth surfaces are smoothed and buffed to a high gloss, creating a lifelike appearance. The tools of the trade are finishing and polishing instruments, designed to snap into rotary handpieces. These little instruments themselves come in many shapes, styles and grit sizes. When used correctly, they deliver dazzling esthetics while staving off abrasion and plaque — a huge plus in the quest for oral health.

Although many of the instruments are labeled as “stones,” they are not actually rocks on a mandrel. Employed in the final stages of restorative processes, stones are composed of a variety of materials, including natural or synthetic minerals. Grit is determined by how finely the materials are crushed and then sorted through a screening process. The resulting instruments are characterized as one of three types of abrasives: bonded, coated or unbonded.

  • Stones fall under the category of bonded abrasives. These involve the integration of grit particles into a binder, or matrix, which may be resin, silicone rubber, or a glass/ceramic. Stones may be mounted on stainless steel shanks that are designed for use with handpieces.
  • Coated abrasives generally are available on discs or strips. These are made by bonding abrasives to flexible substrates, such as paper, cloth, resin, metal, polyester, rubber or Mylar.
  • Unbonded abrasive is simply grit that has been left loose so that it can be used as powder or added to various compounds that make up polishing pastes.

FINISHING AND POLISHING VERSUS POLISHING

To be prepared to talk with clients about polishing esthetic restorations, it is important for sales reps to first understand the difference between “finishing and polishing” and “polishing.”1 The two dovetail to a degree, as both involve rotary handpieces and abrasives. But they are distinct processes:

  • “Finishing and polishing” means removing a restoration’s marginal irregularities, defining anatomic contours, and smoothing surface roughness.2 The “finishing” part of this involves contouring and eliminating any imperfections resulting from the manufacturing process. Polishing — typically one of three or four steps in this finishing-and-polishing process — removes scratches to produce a smooth, reflective luster.2,3 This process is essential to the esthetic look of tooth-colored dental work, and can significantly improve the longevity and success of the restoration.4-6
  • “Polishing,” used alone, refers to maintaining the characteristics of esthetic restorations by recreating surface luster. This involves scratching surfaces by applying instruments with decreasing grit sizes, starting with coarse grit and finishing with fine or superfine grit. In essence, larger scratches are replaced with increasingly finer ones until the marks are virtually undetectable — smaller than the wavelength of visible light.1,7 To do otherwise (say, skip a grit level), can endanger restoration longevity.

For new restorations, the initial grit used in final finishing is the coarsest, to pick up where the cutting and trimming burs left off during contouring. At this stage, the clinician needs a variety of sizes, shapes and grits to create a natural look and feel — as abrasives cut and grind out the final form of a restoration. This includes carbide burs and diamond points (also sometimes called stones), as well as coarser grades of silicon carbide and aluminum oxide stones.

Polishing instruments, usually more finely gritted versions of the finishers, follow the finishing process. This polishing enhances esthetics through abrasion that, at the microscopic level, transforms light-dissipating, rough surfaces into light-reflective, smooth surfaces.

Beyond esthetics, glossy surfaces help prevent plaque from gaining a foothold. And many clinicians believe the most important result of polishing is to make restorations less abrasive and easier on opposing teeth. For example, lithium disilicate and zirconia restorations are very hard, creating the potential for abrasion. But when polished well, they can become less abrasive than conventional porcelain.8

THE ‘BIG THREE’ OF ABRASIVES

THESEAMUSS / ISTOCK / THINKSTOCK; DIGITAL VISION / DIGITAL VISION ; APTTONE / ISTOCK / ’THINKSTOCK

Although scores of abrasive materials are used in dentistry, the three principal options are aluminum oxide, silicon carbide and diamond.

  • Aluminum oxide, sometimes known as India stone , is the synthetic version of alumina, or corundum. It is pure and hard, which also makes it noncontaminating and unlikely to cause discoloration of restorative materials. Used to make white stones as well as coated and unbonded abrasives, aluminum oxide is indicated for finishing and polishing precious metal, composites and ceramics. Adding chromium creates pink versions, used in prepping metal for porcelain.
  • Silicon carbide is extremely hard but brittle. It is commonly used in green stones, darkly colored abrasives, flexible discs, and vitreous- or rubber-bonded instruments. Featuring sharp particles that break off to form new edges, it may be used for finishing and polishing a range of materials.
  • Diamond abrasives may be natural or synthetic. Natural diamonds are sometimes called “superabrasives” because they can cut any surface known to man. Available on bonded instruments, as coating on metal strips and in diamond polishing pastes, they are used mostly for ceramic and resin-based composites. Synthetic diamonds have become popular for finishing and polishing because they offer more consistent size and shape than natural diamond grits — at lower cost. Through use, their sharp edges break down to expose fresh edges for efficient cutting or grinding. They may be resin- or metal-bonded or vitreously bonded in a glass matrix, or even combined with other abrasives. Used mostly for wheels and points, they can also be found in polishing pastes. They are indicated for ceramics, resin-based composites and natural tooth structure.

THE RIGHT TOOL FOR THE JOB

Finishing and polishing instruments generally consist of a head, neck and shank designed to fit onto a rotary handpiece. Some come in the form of attachment heads that snap onto a mandrel.

Sales professionals will want to get up to speed on what constitutes a well-stocked finishing and polishing armamentarium. Be prepared to offer the latest instruments to clients who are either already well versed in all-veramic materials, or who are just venturing into this increasingly complex realm.

The growing demand for natural-looking restorations has been a major driver in the development of new materials and techniques. Ceramic materials used in indirect restorations include feldspathic porcelain, leucite, lithium disilicate, spinel, alumina and zirconia. And when it comes to all-ceramic restorations, hand layering, pressing, casting, and machining via computer-aided design/computer-aided manufacturing (CAD/CAM) are all used to fabricate these lifelike prostheses.

Therefore, finishing and polishing instruments are constructed according to the material on which they will be used — meaning, instruments suited for ceramics are different than those used for other restorations. Instruments also can vary within the ceramic family itself.

When determining their approach, clinicians will consider the structural properties and hardness of the restorative material, the abrasive hardness of the polishing paste, and the manufacturer’s recommendations for the restorative material.1,2

POINT of SALE

FINISHING AND POLISHING

  • Finishing and polishing instruments are generally characterized as one of three types of abrasives: bonded, coated or unbonded.
  • The principal materials used for fine finishing and polishing are aluminum oxide, silicon carbide and diamonds.
  • Finishing is necessary to ensure the proper final shape and fit of a restoration.
  • Proper polishing creates a glossy surface, which staves off plaque, minimizes abrasion of opposing teeth, and improves the longevity of the restoration.
  • While instruments can be purchased separately, kits or “systems” often provide good value, offering all of the materials needed for finishing and polishing particular types of restorations — or a wide range of restorations.

 FLEX, FINESSE AND GROOVE

Because teeth and restorations don’t come in regularly shaped squares, manufacturers of abrasive instruments offer a range of shapes and sizes to accommodate the contours. Some of the more common shapes are cups, discs and points, though names vary according to manufacturer.

Flexible shapes adapt to convex and concave irregularities inherent in tooth surfaces. For instance, cups adapt to the contours of buccal and lingual surfaces. They can be used to build in labial characterization and polish margins. Points excel at finishing and polishing lingual and occlusal reliefs and cervical areas. They, too, can be used to build in labial groove characterization in resin-based veneers and composites. Discs can shape and polish, even when working close to margins, where tissue damage is a concern. Thin enough to reach tight spots such as interproximals, they also are flexible enough to adapt to tooth structure, helping to burnish and feather restoratives so there is no demarcation or white line between surfaces.9

Other shapes include barrels, inverted cones, tapers, flames, spheres, cylinders, bullets, knives, lenses and even brushes whose bristles are loaded with grit. All shapes have uses when finessing restorations and natural dentition, and clinicians understandably have favorites. As a sales professional, it’s your job to understand those preferences and suggest suitable products.

LEXICON

  • Abrasion: In this context, the wearing via friction of one surface (abrasive material) against another (tooth or restorative surface).
  • Bonded abrasive: An abrasive material set in a matrix (or binder), often made of resin, ceramic or rubber and formed into shapes called “stones.”
  • Grit: The roughness or smoothness of the chosen carbide or diamond. Common grits include ultrafine, extra fine, fine, medium, coarse and super coarse.
  • Labial characterization: A technique for making anterior restorations appear more like natural teeth.
  • Vitreous: Glassy and nonporous.

 A SYSTEMATIC APPROACH

With such a diverse array of options, it’s no surprise that many practitioners are being drawn to finishing and polishing “systems” — otherwise known as kits. The simplification offered by these systems — often designed for use on particular restorative materials — can be invaluable. They frequently provide a succession of easily identified, color-coded instruments, plus step-by-step instructions that make clinicians’ — and sales reps’ — lives easier.

Some kits offer single-use polishers that can be attached to a mandrel. Others feature mounted stones that are autoclavable and reusable. Recommended steps vary, as well. There are one-step systems that some clinicians swear by as timesavers. One system, for example, is designed to deliver varying degrees of abrasion through pressure change, eliminating the need to change grits.

It should be noted that finishing and polishing concepts vary widely between manufacturers. Some kits include trimming and contouring instruments, while others are limited to the finer abrasives. This is where knowledgeable sales reps can help clinicians by developing a sound understanding of the various abrasives and systems, and what they are designed to do.

When endowed with the right grit for the job, well-chosen instruments, devices and abrasives can help ensure great esthetics while fostering good oral health. That leads to happy clinicians, satisfied pa­tients and successful long-term outcomes. In a world where no two people are the same, bright sales professionals can offer the right mix of tools to make every patient shine.

Featured photo by DIGITAL VISION/DIGITAL VISION/THINKSTOCK

REFERENCES

  1. Barnes CM. Polishing esthetic restorative materials. Dimensions of Dental Hygiene. 2010;8(1):24–28.
  2. Jeffries SR. Abrasive finishing and polishing in restorative dentistry: a state-of-the-art review. Dent Clin N Am. 2007;51:379–397.
  3. Yap AU, Lye KW, Sau CW. Surface characteristics of tooth-colored restoratives polished utilizing different polishing systems. Oper Dent. 1997;22:260–265.
  4. Goldstein RE. Finishing of composites and laminates. Dent Clin N Am. 1989;33:305–318.
  5. Goldstein RE, Garber DA. Maintaining esthetic restorations—a shared responsibility. J Esth Dent. 1995;7:187.
  6. Neme AL, Frazier KB, Roeder LB, Debner TL. Effect of prophylactic polishing protocols on the surface roughness of esthetic restorative materials. Oper Dent. 2002;27:50–58.
  7. Gladwin M, Bagby M. Clinical Aspects of Dental Materials, Theory, Practice and Cases. Baltimore: Lippincott, Williams & Wilkins; 2004:65–77, 209, 268.
  8. Stone R. Smooth operator. Mentor. 2013;4(4):33–37.
  9. Stone R. Rock stars. Mentor. 2013;4(6):35–38.
MENTOR July 2016;7(07):26–28,30.

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