November/December 2006, Volume 2, Issue 9
Published by AEGIS Communications
Clinical Uses of Reciprocating Handpieces
Howard E. Strassler, DMD
The principles of restorative dentistry and periodontics dictate that restorations must fulfill the clinical requirements of having correct form and function in relation to the adjacent teeth, occlusion, and periodontium. After placement of composite resins, porcelains, and cast metals, there is the difficult challenge of margination and contouring in areas that are difficult to access because these materials are not finished at marginal areas until they have reached a final set or the cement has set. Also, with the increased emphasis on esthetic dentistry, the reshaping of teeth to their natural form after wear or chipping can be difficult with conventional rotary instrumentation.
A significant problem with Class 2 restorations is the presence of overhangs at the gingival–interproximal margin, which can be responsible for plaque retention, periodontal inflammation, and bone loss.1-3 These interproximal areas are difficult to assess and an overhanging margin may not be seen until a postoperative reevaluation bitewing radiograph is taken on recall. Although there are a variety of finishing instruments that can be used, there is concern for potential damage of the tooth structure adjacent to these marginal areas.4-6 Rotary instruments, burs, and diamonds have the potential of notching root surfaces and ending with an unsatisfactory result. Finishing strips, whether diamond-impregnated or another type of abrasive particle, do not offer the precision required to remove and reshape inadequate areas of the restoration. With the newer resin and glass ionomer cements, it can be difficult to remove excess set cement in gingival interproximal areas with hand instruments. And, because of the difficulty of controlling rotary instruments at the gingival margins, there is concern for notching root surfaces.4,6
As patients age, tooth wear contributes to changes in anatomic forms that not only compromise esthetics, but can also have an impact on their ability to clean their teeth interproximally. As teeth wear, the marginal ridge areas and occlusal embrasure areas of posterior teeth and the incisal embrasures of anterior teeth change in appearance and shape, which leads to a flattening of these areas and loss of embrasure form (Figure 1). When this occurs in posterior teeth, a patient will have difficulty placing floss between these teeth because the occlusal embrasure is no longer present to guide the dental floss. For anterior teeth, the same effect occurs combined with a change in the esthetic appearance of these teeth.
For young, non-worn teeth, the incisal embrasure contributes to the esthetic appearance of individual teeth. As these teeth wear, there are changes to the incisal length and apparent height differences in the maxillary incisors until there becomes no difference in length between the maxillary central and lateral incisors. In fact, these anterior teeth with the loss of incisal embrasures can appear as a single block of four teeth with no individualization in appearance from tooth to tooth.
The aforementioned challenges create a need for instrumentation that allows for reshaping restorations and teeth back to their natural form. These changes to teeth and restorations are delicate ones, and the use of conventional rotary handpieces may not be able to attain the slight and subtle changes required. To meet this need, there are reciprocating handpieces and flat-tip inserts that fit these handpieces, which move not in a rotary motion, but in a back-and-forth reciprocating motion.
Reciprocating Motor-Driven Handpieces and Abrasive Tips
Although there are many shapes and grits of diamonds and finishing burs that can be used with rotary instrumentation to remove excess composite resin and metallic restorative materials, these are easier to control and used only on fully accessible margins on the facial and lingual. When one needs access to remove excess material interproximally or shape an incisal edge or embrasure, the rotary instrument is more difficult to control for these more delicate tasks. Sometimes in interproximal areas the sites cannot be reached by the bur.6,7 Recently, there has been a redesign of the Profin® reciprocating handpiece (Dentatus, New York, NY) to a smaller, lighter, more ergonomic handpiece—Profin®et Directional Reciprocating handpiece—that is the same size as a disposable prophy angle (Figure 2). For any reciprocating handpiece, there are a wide variety of safe-sided diamond abrasive flattened tips (Lamineer tips, Dentatus) (Figure 3 and Figure 4) that, once inserted into the handpiece head, provide a back-and-forth reciprocal motion. Because of the flat shape of the tips, they can be easily placed in interproximal and embrasure areas. For the Profinet system, these tips can either be locked into a set position or placed to be freely rotating when shaping a large surface area of a restoration or tooth. The reciprocation of the tips allows for controlled removal of any excess restorative material that may be present to reshape and recontour a restoration. These tips have been shown to be effective for polishing composite resin, porcelain, amalgam, base metals, and gold.5,8 The Lamineer tips are available in an assortment of diamond grit particle sizes from coarse (150 µm) to fine (15 µm).9 The Lamineer tips have a variety of shapes and sizes that can be selected for the specific task.6,10
Clinical Uses of a Reciprocating Handpiece
The thinness of flattened tips with a variety of different abrasive grits allows for the delicate and subtle reduction of all restorative materials and tooth structure with the reciprocating motion of the handpiece. For anterior restorations, the gingival interproximal areas of the restoration can be finished and polished leaving no overhanging margins. Figure 5 demonstrates a case with porcelain veneers in which the gingival margin of porcelain was slightly overcontoured. Using the safe-sided flat tip, the area was reshaped. In another case of porcelain veneer placement, an excess of resin cement was removed and the surfaces polished (Figure 6).
Overhanging margins are easily managed with a reciprocating handpiece.11,12 With the increasing use of composite resin to restore posterior teeth, it is difficult to detect small overhanging margins. With a medium grit Lamineer tip, the gingival margins of the restoration can be marginated and adapted to the cavosurface margin (Figure 8; Figure 9; Figure 10). In the case of amalgam overhangs, the trauma to the pulp of removing an existing restoration can be eliminated by finishing the amalgam to be flush to the tooth surfaces (Figure 7). In the case of fiber-reinforced periodontal splints, the gingival embrasures can be shaped and polished with a reciprocating handpiece (Figure 11).
Although the uses of the reciprocating handpiece are typically for gingival margination, there are other uses for the thin-bladed tips and other specialized tips that are available. Oliver described using a reciprocating handpiece to remove resin after debonding orthodontic brackets.13 Similarly, a reciprocating handpiece can be used for the microabrasion removal of superficial enamel staining either from fluorosis or demineralization/remineralization on anterior teeth. Another orthodontic use is for anatomic shaping and stripping of interproximal contacts for teeth that are rotated and will be orthodontically aligned. Also, specialized plastic tips for reciprocating handpieces have expanded uses to include interproximal gingival polishing of composite (Figure 12), polishing stain from the facial embrasure areas of teeth (Figure 13), and for implant debridement.14 Axelsson described the use of the EVA tip on the Profin reciprocating handpiece as an important adjunct when maintaining periodontal health.15 When sonic, ultrasonic, and reciprocating scaling instruments were compared for calculus removal, the reciprocating inserts gave similar results to the ultrasonic instruments.16
There are prosthodontic uses for a reciprocating handpiece. In many cases, the use of resin and glass ionomer cements requires dynamic loading when seating the restoration because of their thixotropic nature and liquefying properties, as well as the flow under force of these materials when cementing restorations.17,18 Using a wooden insert, the reciprocating handpiece allows for mechanical seating of restorations during cementation (Figure 14). With the increased use of computer-aided design/computer-aided manufacturing systems for in-office fabrication of ceramic and composite resin restorations, the flat-bladed safe-sided paddle used in a reciprocating handpiece provides for the elimination of undercuts when preparing the proximal walls of inlay and onlays (Figure 15). The use of a reciprocating handpiece and its attachments to create guidelines when designing removable partial dentures has been described. When a reciprocating handpiece was compared with a conventional rotary handpiece, the reciprocating handpiece demonstrated a smoother surface.19 Tooth reshaping for esthetics can be accomplished with a reciprocating handpiece when the thin diamond flat tip allows for fine and delicate reshaping of incisal embrasures whereas a rotary diamond would be difficult to control (Figure 16).
If you are practicing state-of-the art restorative dentistry, a reciprocating handpiece is a must-have instrument for your operatory. The flat-bladed diamond-impregnated tips not only allow for safe and effective interproximal finishing, but also for many uses of which practitioners may be unaware. These reciprocating handpieces are multi-dimensional instruments that can improve the quality of practice for your patients.
The author receives grant/research and other financial or material support from Dentatus.
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About the Author
Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics, Prosthodontics, and Operative Dentistry
Baltimore College of Dental Surgery
University of Maryland Dental School