Effectiveness of Reciprocal-Action Instrumentation for Polishing Composite Resin: An In Vifro Study Keith L. Small, D .M.D. * Marvin H. Goldfogel, D.D.S. Sheldon M . Newman, D.D.S., M.S.
This in uitro study investigates the use of reciprocal-action instrumentation for polishing composite resin restorative materials. Electron photomicrographs were made of surfaces of a microfiled and a hybrid composite resin restorative material polished by various reciprocal-action polishing procedures, including several types of polishing pastes used with nonabrasive plastic tips. The best polish on the microfilled composite resin restorative material tested was produced by ending with 3-p diamond polishing paste. The best polish on the hybrid composite resin restorative material tested was produced by ending with 0.5-1.1diamond polishing paste. The surfaces produced were comparable to those produced by polishing discs.
S
everal previous studies have analyzed the surface smoothness obtained with conventional rotary abrasives for polishing composite resin restorative materials.l-15These methods include the use of discs, finishing burs, diamonds, rubber polishers, abrasive compounds, and glazes. Rotary instrumentation has produced consistently good results when access to the surface being polished is not limited. However, interproximal, gingival, and subgingival restoration surfaces and margins are often inaccessible to rotary instrumentation and may remain rough. It is well accepted that rough surfaces are generally more receptive to the formation and retention of bacterial plaque.I6 Therefore, lack of sufAcient polishing in these areas may pose a significant periodontal hazard. The Profin Directional Handpiece, manufactured in Sweden (Dentatus AB, Hagersten, Sweden), is being distributed in this country (weissman Technology International, Inc.. New York, Ny) as an instrument suitable for contouring and polishing a variety of restorative materials. It is especially useful in difllcult-toreach areas such as interproximal and subgingival
surfaces. The instrument is used with thin spatulashaped diamond-coated metal tips for polishing restorative materials. This reciprocal-action instrument system is being marketed as effective for shaping, contouring, and polishing composite resin restorative materials as well as various other types of restorative materials. Nonabrasive plastic tips for use with polishing pastes are available as part of this system for application of finer grit polishing pastes. A previous study by Small, Goldfogel, and Hicks” tested reciprocal-action instrumentation for polishing Type I1 gold, especially at the gold/tooth interface (margin).The results of that study showed that it was possible to create acceptable to excellent polished gold surfaces when using the diamond-coated metal tips. This in uitro SEM investigation assesses the effectiveness of a reciprocal-action instrument in polishing various composite resin restorative materials. Several advantages as well as some disadvantages were discovered in this study.
MATERIALS AND METHODS Multiple specimens of two brands of light-cured composite resin restorative materials were produced in a silicone-lined, plexiglass mold. The approximate dimensions of these ovoid specimens with flat ends was 6 mm wide, 9 xmn long, and 3 mm deep. Hollow plastic casting sprues were placed in the underside of each specimen to act as a handle. These specimens were first light cured with a visible light-curing unit for 60 seconds using the Visilux 2 Visible Light Curing Unit (3M,
‘Private Practice, Denver. Colorado: t Professor and Chairman. Division of Fixed hosthodontics. Chairman. Department of Restorative Dentistry: thsoclate Professor.Departmentof Restorative Dentistry:University of Colorado School of Dentistry. Denver. Colorado This study was supported in part by a grant from Weissman Technology, InC. Address reprint requests to Dr. Marvin H. Goldfogel.Universityof Colorado School of Dentistry, 4200 East 9th Avenue, Box C284. Denver, CO 80262 01992 Deckex Periodicals Inc.
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dentist (EUS).Each polishing step was concluded when the operator felt that further application of the instrument would provide n o further clinical benefit to the surface. This averaged 15 to 20 s per step. At least five specimens were selected for each polishing sequence. The study was divided into three phases:
Phase I. In order to establish which surfaces would best serve a s controls, Sof-Lex discs (3M) were used at two speeds. The first speed was the manufacturer's recommended speed of 10,000 rpm for coarse and medium grits and 30,000 rpm for fine and superfine grits. The second speed was a slower "clinical" speed in a conventional slow speed friction grip contra angle handpiece. This slower clinical speed was established at approdmately 7500 rpm. Many specimens of each type of composite resin restorative material were polished and evaluated by the authors using scanning electron microscopy in order to determine which would serve as controls for the study. It was demonstrated in several previous studies that polishing with Sof-Lex discs produced polished surfaces that were highly acceptable for composite resin restorative material^.^,'^, l5
Figure Ik Profin reciprocal-action contra angle handpiece.
Phase 11. A series of polishing procedures that began with a 50-p reciprocal-action diamond-coated metal tip was performed on a number of specimens of each type of composite resin restorative material. These procedures were done with a Profin (Fig. 1A) reciprocalaction contra angle, a previous version of which was marketed as the Dentatus EVA. The Profin instrument was used with a series of Lamineer diamond-coated metal tips (Weissman Technology International, Inc., New York, Ny) (Fig. 1B) in the order that the manufacturer recommended and as listed in Table 1. Following the polishing with the series of diamond-coated metal tips, Dentatus EVA No. 6 nonabrasive plastic tips (Dentatus AB, Hagersten. Sweden) (Fig. 1C)were used in the Profin reciprocal-action contra angle with several different polishing pastes.
Figure 1B. Lamineer diamond-coated metal tips.
St. Paul, MN). They were then transferred to the stage of a Triad curing unit (Dentsply International, York, PA) for 5 minutes of additional curing. As was suggested in a previous study, these specimens were stored in air for a minimum of 48 hours to allow for complete maturation of cure. l2 The two brands of composite resin restorative materials were Silux Plus (3M, St. Paul, MN) and Herculite X R (Sybron/Kerr, Romulus, MI). These products represent two widely used classes of composite resin restorative materials. Silux Plus is a visible light-cured heterogeneous microfllled composite resin restorative material consisting of a submicron silica-reinforced BIS/ GMA organic matrix incorporating splintered prepolymerized particles.8 Herculite X R is a visible light-cured hybrid composite resin restorative material consisting of fine-ground barium aluminum borosilicate particles in a submicron silica-reinforced BIS/GMA organic matnix.* Low power light microscopy was used to select specimens with the fewest imperfections on their flat surfaces for polishing. Specimens with a noticeable number of bubbles or large porosities were discarded. AU of the polishing procedures were performed by one
P h a s e IZZ. This series began with a repetition of PHASE I1 except that the procedures were started with a 30-p diamond-coated metal tip instead of a 50-p diamond-coated metal tip. These procedures and a
Table 1. Polishlng Procedures Used in Phase It on Both Microfilled and Hybrid Composites A. B. C. D. E.
209
50-pdiamond-coatedmetal tip 5O-p+ 30-pdiamond-coatedmetal tips 50-p + 30-b+ 15-pdiamond-coatedmetal tips 50-p+ 30-p + 15-pdiamond-coatedmetal tips + 1520-p wolfram-coatedmetal tip Weissman Technology International, inc.) 50-p+ 30-p + 15-pdiamond-coatedmetal tips + 1520-p wolfram-coatedmetal tip + 0.3-pLuster Paste aluminum oxide polishing paste (Sybron/Kerr) applied with a plastic tip
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4. NUMBER 6 November/December 1992
safer and more practical technique for use in the mouth because using 30,000 rpm with the discs poses a risk to soft tissues and could potentially heat the surface of the resin. The slower clinical speed also gave the operator more control. There was little or no observable difference between the surfaces polished by these two speeds. As expected, the microfilled composite resin restorativematerial surfaces were consistently smoother than the hybrid composite resin restorative material surfaces. The specimens that were polished at clinical speed were chosen as controls for polishing each type of composite resin restorative material. The reciprocal-action abrasive instruments were then evaluated in Phase I1 and Phase 111. In Phase 11, it was observed that a 50-y diamond-coated metal tip scratched the composite resin restorative material sur-
Figure 1C. D e n t a t u s EVA No. 6 nonabrasive plastic tips.
Table 2. Polishing ProceduresUsed in Phase 111 on Both Microfilled and Hybrid Composites
series of others tested in this phase are outlined inTable 2. After producing the SEM photomicrographs, several were selected and given to 20 dentists for ranking according to smoothness. In order to accomplish this, representative photomicrographs of specimens were selected, numbered randomly, and assembled into four packets for evaluation by the dentists. Each evaluator ranked the photomicrographs from roughest to smoothest for each packet according to detailed instructions supplied in writing. These instructions directed the evaluator to (1)consider the scratches and (2) ignore the porosities. The results of these rankings were subjected to nonparametric statistical analysis. All polishing with the diamond-coated metal tips was done dry, and all of the diamond and aluminum oxide polishing pastes were applied using the nonabrasive plastic tips, which were designed for this function. After each use of a diamond-coated metal tip, the tip was cleaned against a hard rubber cleaning block. Individual tips were used on only one type of composite resin restorative material. Polishing pastes were used as they were supplied by the manufacturer without modification. After each polishing step, the surfaces were thoroughly washed with an air-water syringe and air dried. At the completion of the polishing procedure in all three phases, the specimens were cleaned in tap water in an ultrasonic cleaner and then stored dry in sealed plastic bags. Each specimen was sputter-coated with platinum in preparation for direct viewing in the SEM. The specimens were oriented at a 45 degree angle to the beam to help show more clearly the surface roughness.18 The polished surfaces, including the control specimens, were scanned in an IS1 DS 130 scanning electron microscope (International ScientificIndustries, Santa Clara, CAI, and representative sites of each specimen were photographed. Exposures were made within the magnification range of x 124 to x 138.
A.
B. C. D.
E. F.
G.
H.
i.
J.
K.
L.
M.
RESULTS
30-p diamond-coated metal tip 15-p diamond-coated metal tip 30-1 + 15-pdiamond-coatedmetal tips 30-p diamond-coated metal tip + 3-p diamond polishing paste (George Taub Products, Jersey City, NJ) applied with a plastic tip 30-p + 15-pdiamond-coated metal tips + 3-p diamond polishing paste applied with a plastic tip 30-p + 15-pdiamond-coated metal tips, + 3-p diamond polishing paste + 1-p Micro 1 aluminum oxide polishing paste (Sybron/Kerr) + 0.3-p Luster Paste aluminum oxide polishing paste, all applied with plastic tips 30-p + 15-1 diamond-coated metal tips, + 3-1 diamond polishing paste + 1-p Prisma Gloss aluminum oxide polishing paste (L.D. Caulk). both applied with plastic tips' 30-p + 15-p diamond-coated metal tips, + 3-p diamond polishing paste + 1-pPrisma Gloss aluminum oxide polishing paste + 0.3-p Prisma Gloss Extra Fine aluminum oxide polishing paste (L.D. Caulk). all applied with plastic tipst 30-p + 15-pdiamond-coated metal tips, + 3-1 diamond polishing paste + 0.8-pCompoSite aluminum oxide polishing paste (Shofu Dental, Menlo Park, CAI, both applied with plastic tips 30-1+ 15-pdiamond-coated metal tips, + 3-p diamond polishing paste + 0.5-p diamond polishing paste (George Taub Products), both applied with plastic tips 30-1 + 15-p diamond-coated metal tips, + 3-p diamond polishing paste + 0.5-pdiamond polishing paste + 1-p Micro 1 aluminum oxide polishing paste + 0.3-p Luster Paste aluminurn oxide polishing paste, ail applied with plastic tips 30-p + 15-p diamond-coated metal tips, + 3-p diamond polishing paste + 0.5-pdiamond polishing paste + 1-p Prisma Gloss aluminum oxide polishing paste, all applied with plastic tips 30-p + 15-p diamond-coated metal tips, + 3-1 diamond polishing paste + 0.5-pdiamond polishing paste + 0.8-p CompoSite aluminum oxide polishing paste, all applied with plastic tips
*Performedon microfilled composite resin restorative material only. t Performed on hybrid composite resin restorative material only.
In Phase I, it was determined that polishingwith the Sof-Lex disc series at the slower clinical speed was a 210
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Table 3. Comparison of ProgressivePolishingof Microfilled Composite with Diamond-CoatedMetal Tips
faces to such an extent that subsequent polishing with h e r abrasives did not consistently remove the scratches. Therefore, in Phase I11 of this study, a 30-p diamondcoated metal tip was used as the initial polishing instrument. The results of Phase I11 of the selected series for ranking are shown in Tables 3, 4, 5, and 6. Table 3 shows that polishing the microfilled composite resin restorative material with reciprocal-action instrumentation followed an expected progression of smoothness when going from a 30-p diamond-coated metal tip to a 15-p diamond-coated metal tip followed by a 3-pdiamond polishing paste applied with a nonabrasive plastic tip. Table 4 gives results when submicron polishing pastes are introduced in the series for polishing the microfilled composite resin restorative material. The roughest surface was produced when a 0.5-p diamond polishing paste ended the polishing procedure. In addition, this surface was statistically rougher than the SofLex disc polished control. A surface smoother than the control was produced by ending the series with a 3-p diamond polishing paste. Further polishing with aluminum odde polishing paste did not improve, nor did it degrade the smoothness of the surface. Table 5 shows that polishing the hybrid composite resin restorative material with reciprocal-action instrumentation did not follow the expected progression of smoothness. A 30-p diamond-coated metal tip gave a
~~~~~
~~
Mean Rank
Grit Size
~~
~~
~
~~~
1
10.5 30.5 50.5
30-k 30-p + 15-p 30-1 + 15-p + 3-p diamond paste ~
~
~~
I
I
~
Ranked from roughest to smoothest from top to bottom. Kruskai-Wallis, p. < 0.01, Vertical bars group sets that are not significantly differenton Mann-WhitneyU pairwise comparisons, p < 0.01.
Table 4. Comparison of ProgressivePolishingof Microfilled Composite with Diamond-CoatedMetal Tips Followed by Plastic Tips Plus PolishingPastes Grit Size
Mean Rank
30-p + 15-p + 3-1diamond paste + 0.5-pdiamond paste Sof-Lex disc series, Control 30-p + 15-1+ 3-p diamond paste + Micro 1/Luster Paste 30-p + 15-p + 3-1 diamond paste
14.5 28.5
I
I
I
585 60.5
Ranked from roughest to smoothest from top to bottom. Kruskal-Wallis,p. < 0.01, Vertical bars group sets that are not significantly differenton Mann-Whitney U pairwise comparisons, p < 0.01.
Mean Rank
Grits&
produced by ending the series with the 3-p diamond polishing paste applied with a nonabrasive plastic tip. Table 6 shows that, with the hybrid composite resin restorative material, any progression beyond a 3-p diamond polishing paste to a ?mer grit polishing paste produced a statistically smoother surface. Three different brands of aluminum oxide polishing pastes could not be differentiated on the basis of surface smoothness produced. Ending the series with a 0.5-p diamond polishing paste produced a significantly smoother surface than any of the aluminum oxide polishing pastes. None of these surfaces were as smooth as the Sof-Lex disc polished control when polishing the hybrid composite resin restorative material.
3oy + 1 30-p 30-p + 15-p + 3-p diamond paste
13.5 27.5 50.5
I
I
I
Ranked from roughest to smoothest from top to bottom. Kruskal-Waliis, p. < 0.01, Vertical bars group sets that are not significantly different on Mann-WhitneyU pairwise comparisons, p < 0.01.
Table 6. Comparison ol ProgressivePolishing of Hybrid Composite with Diamond-Coated Metal Tips Followed by Plastic Tips Plus Polishing Pastes ~~
~
~
~~
Grit Size
~~
~~
Mean Rank
DISCUSSION
30-p + 15-p + 3-1 diamond paste 30-p + 15-p + 3-p diamond paste +
26.5
A feature of the ProAn Directional Handpiece design is that the operator can engage the diamond tip to lock it for more precise control of the directional movement. After the restoration contour has been perfected, the Lamineer diamond-coated metal tip can be unlocked to allow the ti^ to rotate in the handDiece and follow the contoured &rface for the Anal pilishing procedures. The original Dentatus EVA contra angle design does not allow the diamond-coated metal tip to be locked or fixed in a speciflc position.
Micro 1/Luster Paste 30-p + 15-p + 3-p diamond paste + Prisma Gloss/Extra Fine 30-p + 15-p + 3-p diamond paste + CompoSite 30-p + 15-p + 3-p diamond paste Sof-Lex disc series, control
49.5
1
49.5 51 -5 83.5 102.5
I I
Ranked from roughest to smoothest from top to bottom. Kruskal-Wallis,p. < 0.01. Vertical bars group sets that are not significantly different on Mann-WhitneyU pairwise comparisons, p < 0.01.
21 1
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 6 November/December 1992
Figure 2A. The hybrid composite surface polished with a 50-kdiamond-coatedmetal tip.
shows a surface that was polished with a 50-pdiamondcoated met& tip and subsequently polished by using 30-p+ 15-pdiamond-coated metal tips (seeTable 1: C). Note that the hook pattern produced by a 50-p diamond-coated metal tip still remains. The use of a wolfram (tungsten)-coated metal tip did not appear to improve the surface smoothness (seeTable 1: D, E). The width of these hook-like scratches were as large as 60 p. These scratches may not have been the result of the diamond particles coating the tip but could have been caused by an accumulation of debris retained on the surface of the tip (Fig. 3).Another study should be done to determine the most effective means of removing the debris from these tips. Although this phenomenon was observed for both the microfilled composite resin restorative material and the hybrid composite resin restorative material, it was more dramatic on the hybrid composite resin restorative material. Each sequence in Phase 111 began with a 30-p diamond-coated metal tip. A 30-pdiamond-coated metal tip seemed to the operator to be just as effective for removing coarse surface irregularities as a 50-p diamond-coated metal tip. When a 15-p diamond-coated metal tip was used following a 30-p diamond-coated metal tip (see Table 2;C), a further improvement in the surface was produced for the microfilled composite resin restorative material but not for the hybrid composite resin restorative material. Progressing from 30-pto 15-p diamond-coated metal tips followed by a 3-p diamond polishing paste (see Table 2; E) observably improved the smoothness of the surface for both the microfilled and the hybrid composite resin restorative materials. If a 15-p diamond-coated metal tip was omitted from the sequence (see Table 2: D). the 3-11 diamond polishing paste did not seem to adequately remove the scratches produced by the 30-11 diamondcoated metal tip for either type of material. Further, it was observed that the use of a 15-p diamond-coated
Figure 28. The hybrid composite polished with a 50-p + 30-p + 15-pdiamond-coated metal tip.
Figure 3. Diamond-coated metal tip with debris on the abrasive surface.
A two-body abrasion technique was used in polishing procedures for particle sizes down to 15 p. For all particle sizes of the 3 p or smaller. a three-body abrasion technique was used. The abrasive was applied to the surface of the composite resin restorative material in a water-soluble suspension. The reciprocal-action tips in the three-body abrasion were made of a flexible plastic. During these procedures, there was observable degradation of the surface of the plastic tips after each use. In Phase II of this study, a 50-pdiamond-coated metal tip was used as the initial polishing tip. In viewing the photomicrographs, it was observed that subsequent polishing with finer diamond-coated metal tips did not consistently remove the coarser scratches produced by a 50-p diamond-coated metal tip. Figure 2A shows the surface that resulted from using a 50-p diamond-coated metal tip (see Table 1; A). Figure 2B
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Reciprocal-Action Polishing
Figure 4B. The microfilled composite surface polished with 30-p + 15-p diamond-coated metal tips, then 3-p diamond paste.
Figure 5B. The hybrid composite surface polished with 30-p + 15-p diamond-coated metal tips, then 3-p + 0.5-p diamond paste.
metal tip as the initial polishing tip was not effective in removing surface irregularities on either type of composite resin restorative material. For the microfilled composite resin restorative material specimens, the best polished surface was produced by 30-p + 15-p diamond-coated metal tips followed by a 3-p diamond polishing paste (see Table 2; E). In the evaluation series (Table 4), the Micro 1/Luster Paste procedure (see Table 2; F) was chosen as representative of all of the aluminum oxide polishing procedures (seeTable 2; F, G , I), since no differences could be detected in the photomicrographs by the authors. Aluminum oxide p o l i s h g pastes produced no improvement when using reciprocal-action instrumentation on the microfilled composite resin restorative rnaFigure 4C. The microfilled composite surface polished with 30-p + 15-c~diamond-coated metal tips, then 3-p + 0 . 5 ~ ~ terial. These polished surfaces produced by the instrumentation (see Table 2: E [Fig. 4Bl and Fl were Signifldiamond paste. There area few porosities on this surface as well cantly smoother than the surfaces of the control specias pits and erosion from the polishing procedure.
213
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 6 November/December 1992
mond-coated metal tips left deep scratches. Gross shaping or contouring with 30-p diamond-coated metal tips may be too time consuming.
mens polished by the Sof-Lexdiscs(Fig. 4A).A submicron (0.5 p) diamond abrasive (see Table 2;J) seemed to cause pitting and erosion of the surface of the microfilled composite resin restorative material specimens (Fig. 4C). From this point, aluminum oxide polishing pastes (see Table 2; K, L, M) did not correct or improve the degradation. These results of reciprocal-action instrumentation with submicron polishing pastes correlate well with one manufacturer’s recommendations for not using these pastes on microfilled composite resin restorative materials. For the hybrid composite resin restorative material specimens, the same sequence of progressivelysmoother instruments was effective in polishing the surface. A completely different standard of smoothness was produced on the hybrid composite resin restorative material, which was not comparable to the microfilled composite resin restorative material at any stage in the progress of polishing. This was apparent from observing the gross specimens as well as the SEM photomicrographs. When observing the gross specimens of the microfilled composite resin restorative material, the descriptionof “mirror-like”came to mind, while a smooth but considerably less shiny surface described the gross specimens of the hybrid composite resin restorative material. This was confirmed quite graphically in the SEM comparisons. The best surface produced with the reciprocalaction instrumentation on the hybrid composite resin restorative material was produced by 30-p+ 15-pdiamond-coated metal tips followed by 3-p and then 0.5-p diamond polishing pastes (see Table 2; J). Using aluminum oxide pastes in place of the 0.5-pdiamond polishing paste (seeTable 2; F, H, I) produced a rougher surface. The three aluminum oxide polishing procedures produced surfaces that were indistinguishable from each other. The Sof-Lex disc polished control (Fig. 5A) was smoother than any of the reciprocal-action polishing procedures for the hybrid composite resin restorative material (Fig. 5B). Going to submicron abrasives of either diamond or aluminum oxide continued to improve the surface smoothness of the hybrid composite resin restorative material. The 0.5-pdiamond polishing paste may be more effective than aluminum oxide polishing pastes for polishing hybrid composite resin restorative material because it can more equally cut both the quartz (820 Knoop Hardness Number)lgand the resin (20 KHN).20 This is due to the greater degree of hardness of diamond (7000 KHN)lg versus aluminum oxide (2100 KHN).l9 The relative effect on surroundingtooth structure (enamel, 343KHN; dentin, 68 KHN)21of diamond versus aluminum oxide polishing pastes needs to be studied. Further investigation also needs to be done to ascertain the d c i e n c y of gross contouring of composite resin restorative materials with reciprocal-action instrumentation. This study demonstrated that 50-pdia-
CONCLUSIONS The following conclusions were reached when using reciprocal-action polishing procedures: 1.
2.
3.
4.
5.
6.
7.
8.
9.
A 50-p diamond-coated metal tip produced scratches that were not consistently removed by subsequent abrasives. The best tip of those tested for initial polishing is a 30-pdiamond-coated metal tip. The best sequence for polishing the microfilled composite resin restorative material was 30-l.~+ 15-pdiamond-coated metal tips followed by 3-p diamond polishing paste used with nonabrasive plastic tips. When this sequence was used, the level of polish was better than the surfaces of the controls, which were achieved by using the SofLex discs. The best sequence for polishing the hybrid composite resin restorative material was 30-p + 15-p diamond-coated metal tips followed by 3-p and then 0.5-pdiamond polishing pastes used with nonabrasive plastic tips. Using submicron polishing pastes, whether diamond or aluminum oxide, on microfilled composite resin restorative material may cause degradation of the surface polish. Using submicron diamond polishing paste produced a better polish than submicron aluminum oxide polishing pastes on the hybrid composite resin restorative material. Thereis a discerniblybetterpolishofthemicrofilled composite resin restorative material over the hybrid composite resin restorative material at all levels of polishing and with all instruments used. This instrumentation for polishingcompositeresin restorative materials would seem to be an advantage in accessing interproximal or subgingival areas. This type of instrumentation is a valuable adjunct to, but does not replace, disc polishing since discs are much faster and more eflcient for polishing accessible surfaces.
REFERENCES Stoddard J W . Johnson GH. An evaluation of polishing agentsfor composite resins.J Prosthet Dent 1991 ;65;491495. 2. Kanter J, Koski RE. An evaluation of new methods for polishing composite restorative resins. Quintessence Int 1980;8:91-95. 3. Kanter J, Koskl RE,Bogdan MS.How to achieve the best surface polish on composite resins. Can Dent Assoc J 1983;5:40-45. 1.
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4. 5. 6.
7.
8. 9. 10.
11.
12.
Lambrechts P. Vanherle G. Observation and comparison of polished composite surface with the aid of SEM and profilometer (part I). J Oral Rehabil 1982; 9: 169-182. Lambrechts P, Vanherle G. Observation and comparison of polished composite surface with the aid of SEM and profilometer (part 11). J Oral Rehabil 1982; 9:203-216. Bauer JG. Caputo AA. The surface of composite resin finished with instruments and matrixes. J Prosthet Dent 1983; 50:351-357. Lutz F, Setco J, Phillips R. New finishing instruments for composite resins. J Am Dent Assoc 1983; 107:575-580. BoghosianAA,Randolph RG, ValdemarsJJ. Rotary instrument finishing of microfilled and small-particle hybrid composite resins. J Am Dent Assoc 1987; 115:299-301. Weinstein AR. Composite resin finishing systems. Ohio Dent J 1983: 57:33-43. Quiroz L, Lentz DL. The effect of polishing procedures on light-cured compositerestorations. Compend Contin Educ 1985; VI:437439. Hosoda H, Yamada T, Inokoshi S. SEM and elemental analysis ofcompositeresins. J Prosthet Dent 1990;64:669676. Hansen EK, Asmussen E. Effect of postponed polishing on marginal adaDtation of resins used with dentin-bonding age;. Scandk Dent Res 1988;96:260-264.
13. Reinhaardt J W ,Denehy GE. Chan KC. et al. Determining smoothness of polished microfilled composite resins. J Prosthet Dent 1983; 49:485-490. 14. Staley C, Kopel H. Smoothness of composite restorations polished by various abrasives: a comparison by scanning electron microscopy. J Oper Dent 1979; 4:140-148. 15. Tjan AHL. Chan CA. The polishability of posterior composites. J Prosthet Dent 1989; 561:138-146. 16. Phillips RW. Science of dental materials. 8th Ed. Philadelphia: WB Saunders, 1982:595. 17. Small KL,Goldfogel MH, Hicks MJ. Marginal finishing for cast gold restorations: reciprocal-action instrumentation. J Prosthet Dent 1987: 5Ek403-408. 18. Barkmeier WW. Personal communication. Creighton University School of Dentistry, Omaha, NE. 19. Lide DR, ed. C.R.C. handbook of chemistry and physics. 72nd Ed. Boca Raton, FL: C.R.C. Press. 1991-92; Section 12:138. 20. Lambrechts P. Basic properties of dental composites and their impact on clinical performance. (Thesis).Katholieke Universiteit Leuven, Leuven, Belgium, 1983:92. 21. Craig RG. Restorative dental materials, 8th Ed. St. Louis: CV Mosby. 1989; 100:514.
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215
This in uitro study investigates the use of reciprocal-action instrumentation for polishing composite resin restorative materials. Electron photomicrographs were made of surfaces of a microfiled and a hybrid composite resin restorative material polished by various reciprocal-action polishing procedures, including several types of polishing pastes used with nonabrasive plastic tips. The best polish on the microfilled composite resin restorative material tested was produced by ending with 3-p diamond polishing paste. The best polish on the hybrid composite resin restorative material tested was produced by ending with 0.5-1.1diamond polishing paste. The surfaces produced were comparable to those produced by polishing discs.
S
everal previous studies have analyzed the surface smoothness obtained with conventional rotary abrasives for polishing composite resin restorative materials.l-15These methods include the use of discs, finishing burs, diamonds, rubber polishers, abrasive compounds, and glazes. Rotary instrumentation has produced consistently good results when access to the surface being polished is not limited. However, interproximal, gingival, and subgingival restoration surfaces and margins are often inaccessible to rotary instrumentation and may remain rough. It is well accepted that rough surfaces are generally more receptive to the formation and retention of bacterial plaque.I6 Therefore, lack of sufAcient polishing in these areas may pose a significant periodontal hazard. The Profin Directional Handpiece, manufactured in Sweden (Dentatus AB, Hagersten, Sweden), is being distributed in this country (weissman Technology International, Inc.. New York, Ny) as an instrument suitable for contouring and polishing a variety of restorative materials. It is especially useful in difllcult-toreach areas such as interproximal and subgingival
surfaces. The instrument is used with thin spatulashaped diamond-coated metal tips for polishing restorative materials. This reciprocal-action instrument system is being marketed as effective for shaping, contouring, and polishing composite resin restorative materials as well as various other types of restorative materials. Nonabrasive plastic tips for use with polishing pastes are available as part of this system for application of finer grit polishing pastes. A previous study by Small, Goldfogel, and Hicks” tested reciprocal-action instrumentation for polishing Type I1 gold, especially at the gold/tooth interface (margin).The results of that study showed that it was possible to create acceptable to excellent polished gold surfaces when using the diamond-coated metal tips. This in uitro SEM investigation assesses the effectiveness of a reciprocal-action instrument in polishing various composite resin restorative materials. Several advantages as well as some disadvantages were discovered in this study.
MATERIALS AND METHODS Multiple specimens of two brands of light-cured composite resin restorative materials were produced in a silicone-lined, plexiglass mold. The approximate dimensions of these ovoid specimens with flat ends was 6 mm wide, 9 xmn long, and 3 mm deep. Hollow plastic casting sprues were placed in the underside of each specimen to act as a handle. These specimens were first light cured with a visible light-curing unit for 60 seconds using the Visilux 2 Visible Light Curing Unit (3M,
‘Private Practice, Denver. Colorado: t Professor and Chairman. Division of Fixed hosthodontics. Chairman. Department of Restorative Dentistry: thsoclate Professor.Departmentof Restorative Dentistry:University of Colorado School of Dentistry. Denver. Colorado This study was supported in part by a grant from Weissman Technology, InC. Address reprint requests to Dr. Marvin H. Goldfogel.Universityof Colorado School of Dentistry, 4200 East 9th Avenue, Box C284. Denver, CO 80262 01992 Deckex Periodicals Inc.
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Reciprocal-Action Polishing
dentist (EUS).Each polishing step was concluded when the operator felt that further application of the instrument would provide n o further clinical benefit to the surface. This averaged 15 to 20 s per step. At least five specimens were selected for each polishing sequence. The study was divided into three phases:
Phase I. In order to establish which surfaces would best serve a s controls, Sof-Lex discs (3M) were used at two speeds. The first speed was the manufacturer's recommended speed of 10,000 rpm for coarse and medium grits and 30,000 rpm for fine and superfine grits. The second speed was a slower "clinical" speed in a conventional slow speed friction grip contra angle handpiece. This slower clinical speed was established at approdmately 7500 rpm. Many specimens of each type of composite resin restorative material were polished and evaluated by the authors using scanning electron microscopy in order to determine which would serve as controls for the study. It was demonstrated in several previous studies that polishing with Sof-Lex discs produced polished surfaces that were highly acceptable for composite resin restorative material^.^,'^, l5
Figure Ik Profin reciprocal-action contra angle handpiece.
Phase 11. A series of polishing procedures that began with a 50-p reciprocal-action diamond-coated metal tip was performed on a number of specimens of each type of composite resin restorative material. These procedures were done with a Profin (Fig. 1A) reciprocalaction contra angle, a previous version of which was marketed as the Dentatus EVA. The Profin instrument was used with a series of Lamineer diamond-coated metal tips (Weissman Technology International, Inc., New York, Ny) (Fig. 1B) in the order that the manufacturer recommended and as listed in Table 1. Following the polishing with the series of diamond-coated metal tips, Dentatus EVA No. 6 nonabrasive plastic tips (Dentatus AB, Hagersten. Sweden) (Fig. 1C)were used in the Profin reciprocal-action contra angle with several different polishing pastes.
Figure 1B. Lamineer diamond-coated metal tips.
St. Paul, MN). They were then transferred to the stage of a Triad curing unit (Dentsply International, York, PA) for 5 minutes of additional curing. As was suggested in a previous study, these specimens were stored in air for a minimum of 48 hours to allow for complete maturation of cure. l2 The two brands of composite resin restorative materials were Silux Plus (3M, St. Paul, MN) and Herculite X R (Sybron/Kerr, Romulus, MI). These products represent two widely used classes of composite resin restorative materials. Silux Plus is a visible light-cured heterogeneous microfllled composite resin restorative material consisting of a submicron silica-reinforced BIS/ GMA organic matrix incorporating splintered prepolymerized particles.8 Herculite X R is a visible light-cured hybrid composite resin restorative material consisting of fine-ground barium aluminum borosilicate particles in a submicron silica-reinforced BIS/GMA organic matnix.* Low power light microscopy was used to select specimens with the fewest imperfections on their flat surfaces for polishing. Specimens with a noticeable number of bubbles or large porosities were discarded. AU of the polishing procedures were performed by one
P h a s e IZZ. This series began with a repetition of PHASE I1 except that the procedures were started with a 30-p diamond-coated metal tip instead of a 50-p diamond-coated metal tip. These procedures and a
Table 1. Polishlng Procedures Used in Phase It on Both Microfilled and Hybrid Composites A. B. C. D. E.
209
50-pdiamond-coatedmetal tip 5O-p+ 30-pdiamond-coatedmetal tips 50-p + 30-b+ 15-pdiamond-coatedmetal tips 50-p+ 30-p + 15-pdiamond-coatedmetal tips + 1520-p wolfram-coatedmetal tip Weissman Technology International, inc.) 50-p+ 30-p + 15-pdiamond-coatedmetal tips + 1520-p wolfram-coatedmetal tip + 0.3-pLuster Paste aluminum oxide polishing paste (Sybron/Kerr) applied with a plastic tip
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4. NUMBER 6 November/December 1992
safer and more practical technique for use in the mouth because using 30,000 rpm with the discs poses a risk to soft tissues and could potentially heat the surface of the resin. The slower clinical speed also gave the operator more control. There was little or no observable difference between the surfaces polished by these two speeds. As expected, the microfilled composite resin restorativematerial surfaces were consistently smoother than the hybrid composite resin restorative material surfaces. The specimens that were polished at clinical speed were chosen as controls for polishing each type of composite resin restorative material. The reciprocal-action abrasive instruments were then evaluated in Phase I1 and Phase 111. In Phase 11, it was observed that a 50-y diamond-coated metal tip scratched the composite resin restorative material sur-
Figure 1C. D e n t a t u s EVA No. 6 nonabrasive plastic tips.
Table 2. Polishing ProceduresUsed in Phase 111 on Both Microfilled and Hybrid Composites
series of others tested in this phase are outlined inTable 2. After producing the SEM photomicrographs, several were selected and given to 20 dentists for ranking according to smoothness. In order to accomplish this, representative photomicrographs of specimens were selected, numbered randomly, and assembled into four packets for evaluation by the dentists. Each evaluator ranked the photomicrographs from roughest to smoothest for each packet according to detailed instructions supplied in writing. These instructions directed the evaluator to (1)consider the scratches and (2) ignore the porosities. The results of these rankings were subjected to nonparametric statistical analysis. All polishing with the diamond-coated metal tips was done dry, and all of the diamond and aluminum oxide polishing pastes were applied using the nonabrasive plastic tips, which were designed for this function. After each use of a diamond-coated metal tip, the tip was cleaned against a hard rubber cleaning block. Individual tips were used on only one type of composite resin restorative material. Polishing pastes were used as they were supplied by the manufacturer without modification. After each polishing step, the surfaces were thoroughly washed with an air-water syringe and air dried. At the completion of the polishing procedure in all three phases, the specimens were cleaned in tap water in an ultrasonic cleaner and then stored dry in sealed plastic bags. Each specimen was sputter-coated with platinum in preparation for direct viewing in the SEM. The specimens were oriented at a 45 degree angle to the beam to help show more clearly the surface roughness.18 The polished surfaces, including the control specimens, were scanned in an IS1 DS 130 scanning electron microscope (International ScientificIndustries, Santa Clara, CAI, and representative sites of each specimen were photographed. Exposures were made within the magnification range of x 124 to x 138.
A.
B. C. D.
E. F.
G.
H.
i.
J.
K.
L.
M.
RESULTS
30-p diamond-coated metal tip 15-p diamond-coated metal tip 30-1 + 15-pdiamond-coatedmetal tips 30-p diamond-coated metal tip + 3-p diamond polishing paste (George Taub Products, Jersey City, NJ) applied with a plastic tip 30-p + 15-pdiamond-coated metal tips + 3-p diamond polishing paste applied with a plastic tip 30-p + 15-pdiamond-coated metal tips, + 3-p diamond polishing paste + 1-p Micro 1 aluminum oxide polishing paste (Sybron/Kerr) + 0.3-p Luster Paste aluminum oxide polishing paste, all applied with plastic tips 30-p + 15-1 diamond-coated metal tips, + 3-1 diamond polishing paste + 1-p Prisma Gloss aluminum oxide polishing paste (L.D. Caulk). both applied with plastic tips' 30-p + 15-p diamond-coated metal tips, + 3-p diamond polishing paste + 1-pPrisma Gloss aluminum oxide polishing paste + 0.3-p Prisma Gloss Extra Fine aluminum oxide polishing paste (L.D. Caulk). all applied with plastic tipst 30-p + 15-pdiamond-coated metal tips, + 3-1 diamond polishing paste + 0.8-pCompoSite aluminum oxide polishing paste (Shofu Dental, Menlo Park, CAI, both applied with plastic tips 30-1+ 15-pdiamond-coated metal tips, + 3-p diamond polishing paste + 0.5-p diamond polishing paste (George Taub Products), both applied with plastic tips 30-1 + 15-p diamond-coated metal tips, + 3-p diamond polishing paste + 0.5-pdiamond polishing paste + 1-p Micro 1 aluminum oxide polishing paste + 0.3-p Luster Paste aluminurn oxide polishing paste, ail applied with plastic tips 30-p + 15-p diamond-coated metal tips, + 3-p diamond polishing paste + 0.5-pdiamond polishing paste + 1-p Prisma Gloss aluminum oxide polishing paste, all applied with plastic tips 30-p + 15-p diamond-coated metal tips, + 3-1 diamond polishing paste + 0.5-pdiamond polishing paste + 0.8-p CompoSite aluminum oxide polishing paste, all applied with plastic tips
*Performedon microfilled composite resin restorative material only. t Performed on hybrid composite resin restorative material only.
In Phase I, it was determined that polishingwith the Sof-Lex disc series at the slower clinical speed was a 210
Reciprocal-Action Polishing
Table 3. Comparison of ProgressivePolishingof Microfilled Composite with Diamond-CoatedMetal Tips
faces to such an extent that subsequent polishing with h e r abrasives did not consistently remove the scratches. Therefore, in Phase I11 of this study, a 30-p diamondcoated metal tip was used as the initial polishing instrument. The results of Phase I11 of the selected series for ranking are shown in Tables 3, 4, 5, and 6. Table 3 shows that polishing the microfilled composite resin restorative material with reciprocal-action instrumentation followed an expected progression of smoothness when going from a 30-p diamond-coated metal tip to a 15-p diamond-coated metal tip followed by a 3-pdiamond polishing paste applied with a nonabrasive plastic tip. Table 4 gives results when submicron polishing pastes are introduced in the series for polishing the microfilled composite resin restorative material. The roughest surface was produced when a 0.5-p diamond polishing paste ended the polishing procedure. In addition, this surface was statistically rougher than the SofLex disc polished control. A surface smoother than the control was produced by ending the series with a 3-p diamond polishing paste. Further polishing with aluminum odde polishing paste did not improve, nor did it degrade the smoothness of the surface. Table 5 shows that polishing the hybrid composite resin restorative material with reciprocal-action instrumentation did not follow the expected progression of smoothness. A 30-p diamond-coated metal tip gave a
~~~~~
~~
Mean Rank
Grit Size
~~
~~
~
~~~
1
10.5 30.5 50.5
30-k 30-p + 15-p 30-1 + 15-p + 3-p diamond paste ~
~
~~
I
I
~
Ranked from roughest to smoothest from top to bottom. Kruskai-Wallis, p. < 0.01, Vertical bars group sets that are not significantly differenton Mann-WhitneyU pairwise comparisons, p < 0.01.
Table 4. Comparison of ProgressivePolishingof Microfilled Composite with Diamond-CoatedMetal Tips Followed by Plastic Tips Plus PolishingPastes Grit Size
Mean Rank
30-p + 15-p + 3-1diamond paste + 0.5-pdiamond paste Sof-Lex disc series, Control 30-p + 15-1+ 3-p diamond paste + Micro 1/Luster Paste 30-p + 15-p + 3-1 diamond paste
14.5 28.5
I
I
I
585 60.5
Ranked from roughest to smoothest from top to bottom. Kruskal-Wallis,p. < 0.01, Vertical bars group sets that are not significantly differenton Mann-Whitney U pairwise comparisons, p < 0.01.
Mean Rank
Grits&
produced by ending the series with the 3-p diamond polishing paste applied with a nonabrasive plastic tip. Table 6 shows that, with the hybrid composite resin restorative material, any progression beyond a 3-p diamond polishing paste to a ?mer grit polishing paste produced a statistically smoother surface. Three different brands of aluminum oxide polishing pastes could not be differentiated on the basis of surface smoothness produced. Ending the series with a 0.5-p diamond polishing paste produced a significantly smoother surface than any of the aluminum oxide polishing pastes. None of these surfaces were as smooth as the Sof-Lex disc polished control when polishing the hybrid composite resin restorative material.
3oy + 1 30-p 30-p + 15-p + 3-p diamond paste
13.5 27.5 50.5
I
I
I
Ranked from roughest to smoothest from top to bottom. Kruskal-Waliis, p. < 0.01, Vertical bars group sets that are not significantly different on Mann-WhitneyU pairwise comparisons, p < 0.01.
Table 6. Comparison ol ProgressivePolishing of Hybrid Composite with Diamond-Coated Metal Tips Followed by Plastic Tips Plus Polishing Pastes ~~
~
~
~~
Grit Size
~~
~~
Mean Rank
DISCUSSION
30-p + 15-p + 3-1 diamond paste 30-p + 15-p + 3-p diamond paste +
26.5
A feature of the ProAn Directional Handpiece design is that the operator can engage the diamond tip to lock it for more precise control of the directional movement. After the restoration contour has been perfected, the Lamineer diamond-coated metal tip can be unlocked to allow the ti^ to rotate in the handDiece and follow the contoured &rface for the Anal pilishing procedures. The original Dentatus EVA contra angle design does not allow the diamond-coated metal tip to be locked or fixed in a speciflc position.
Micro 1/Luster Paste 30-p + 15-p + 3-p diamond paste + Prisma Gloss/Extra Fine 30-p + 15-p + 3-p diamond paste + CompoSite 30-p + 15-p + 3-p diamond paste Sof-Lex disc series, control
49.5
1
49.5 51 -5 83.5 102.5
I I
Ranked from roughest to smoothest from top to bottom. Kruskal-Wallis,p. < 0.01. Vertical bars group sets that are not significantly different on Mann-WhitneyU pairwise comparisons, p < 0.01.
21 1
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 6 November/December 1992
Figure 2A. The hybrid composite surface polished with a 50-kdiamond-coatedmetal tip.
shows a surface that was polished with a 50-pdiamondcoated met& tip and subsequently polished by using 30-p+ 15-pdiamond-coated metal tips (seeTable 1: C). Note that the hook pattern produced by a 50-p diamond-coated metal tip still remains. The use of a wolfram (tungsten)-coated metal tip did not appear to improve the surface smoothness (seeTable 1: D, E). The width of these hook-like scratches were as large as 60 p. These scratches may not have been the result of the diamond particles coating the tip but could have been caused by an accumulation of debris retained on the surface of the tip (Fig. 3).Another study should be done to determine the most effective means of removing the debris from these tips. Although this phenomenon was observed for both the microfilled composite resin restorative material and the hybrid composite resin restorative material, it was more dramatic on the hybrid composite resin restorative material. Each sequence in Phase 111 began with a 30-p diamond-coated metal tip. A 30-pdiamond-coated metal tip seemed to the operator to be just as effective for removing coarse surface irregularities as a 50-p diamond-coated metal tip. When a 15-p diamond-coated metal tip was used following a 30-p diamond-coated metal tip (see Table 2;C), a further improvement in the surface was produced for the microfilled composite resin restorative material but not for the hybrid composite resin restorative material. Progressing from 30-pto 15-p diamond-coated metal tips followed by a 3-p diamond polishing paste (see Table 2; E) observably improved the smoothness of the surface for both the microfilled and the hybrid composite resin restorative materials. If a 15-p diamond-coated metal tip was omitted from the sequence (see Table 2: D). the 3-11 diamond polishing paste did not seem to adequately remove the scratches produced by the 30-11 diamondcoated metal tip for either type of material. Further, it was observed that the use of a 15-p diamond-coated
Figure 28. The hybrid composite polished with a 50-p + 30-p + 15-pdiamond-coated metal tip.
Figure 3. Diamond-coated metal tip with debris on the abrasive surface.
A two-body abrasion technique was used in polishing procedures for particle sizes down to 15 p. For all particle sizes of the 3 p or smaller. a three-body abrasion technique was used. The abrasive was applied to the surface of the composite resin restorative material in a water-soluble suspension. The reciprocal-action tips in the three-body abrasion were made of a flexible plastic. During these procedures, there was observable degradation of the surface of the plastic tips after each use. In Phase II of this study, a 50-pdiamond-coated metal tip was used as the initial polishing tip. In viewing the photomicrographs, it was observed that subsequent polishing with finer diamond-coated metal tips did not consistently remove the coarser scratches produced by a 50-p diamond-coated metal tip. Figure 2A shows the surface that resulted from using a 50-p diamond-coated metal tip (see Table 1; A). Figure 2B
212
Reciprocal-Action Polishing
Figure 4B. The microfilled composite surface polished with 30-p + 15-p diamond-coated metal tips, then 3-p diamond paste.
Figure 5B. The hybrid composite surface polished with 30-p + 15-p diamond-coated metal tips, then 3-p + 0.5-p diamond paste.
metal tip as the initial polishing tip was not effective in removing surface irregularities on either type of composite resin restorative material. For the microfilled composite resin restorative material specimens, the best polished surface was produced by 30-p + 15-p diamond-coated metal tips followed by a 3-p diamond polishing paste (see Table 2; E). In the evaluation series (Table 4), the Micro 1/Luster Paste procedure (see Table 2; F) was chosen as representative of all of the aluminum oxide polishing procedures (seeTable 2; F, G , I), since no differences could be detected in the photomicrographs by the authors. Aluminum oxide p o l i s h g pastes produced no improvement when using reciprocal-action instrumentation on the microfilled composite resin restorative rnaFigure 4C. The microfilled composite surface polished with 30-p + 15-c~diamond-coated metal tips, then 3-p + 0 . 5 ~ ~ terial. These polished surfaces produced by the instrumentation (see Table 2: E [Fig. 4Bl and Fl were Signifldiamond paste. There area few porosities on this surface as well cantly smoother than the surfaces of the control specias pits and erosion from the polishing procedure.
213
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 6 November/December 1992
mond-coated metal tips left deep scratches. Gross shaping or contouring with 30-p diamond-coated metal tips may be too time consuming.
mens polished by the Sof-Lexdiscs(Fig. 4A).A submicron (0.5 p) diamond abrasive (see Table 2;J) seemed to cause pitting and erosion of the surface of the microfilled composite resin restorative material specimens (Fig. 4C). From this point, aluminum oxide polishing pastes (see Table 2; K, L, M) did not correct or improve the degradation. These results of reciprocal-action instrumentation with submicron polishing pastes correlate well with one manufacturer’s recommendations for not using these pastes on microfilled composite resin restorative materials. For the hybrid composite resin restorative material specimens, the same sequence of progressivelysmoother instruments was effective in polishing the surface. A completely different standard of smoothness was produced on the hybrid composite resin restorative material, which was not comparable to the microfilled composite resin restorative material at any stage in the progress of polishing. This was apparent from observing the gross specimens as well as the SEM photomicrographs. When observing the gross specimens of the microfilled composite resin restorative material, the descriptionof “mirror-like”came to mind, while a smooth but considerably less shiny surface described the gross specimens of the hybrid composite resin restorative material. This was confirmed quite graphically in the SEM comparisons. The best surface produced with the reciprocalaction instrumentation on the hybrid composite resin restorative material was produced by 30-p+ 15-pdiamond-coated metal tips followed by 3-p and then 0.5-p diamond polishing pastes (see Table 2; J). Using aluminum oxide pastes in place of the 0.5-pdiamond polishing paste (seeTable 2; F, H, I) produced a rougher surface. The three aluminum oxide polishing procedures produced surfaces that were indistinguishable from each other. The Sof-Lex disc polished control (Fig. 5A) was smoother than any of the reciprocal-action polishing procedures for the hybrid composite resin restorative material (Fig. 5B). Going to submicron abrasives of either diamond or aluminum oxide continued to improve the surface smoothness of the hybrid composite resin restorative material. The 0.5-pdiamond polishing paste may be more effective than aluminum oxide polishing pastes for polishing hybrid composite resin restorative material because it can more equally cut both the quartz (820 Knoop Hardness Number)lgand the resin (20 KHN).20 This is due to the greater degree of hardness of diamond (7000 KHN)lg versus aluminum oxide (2100 KHN).l9 The relative effect on surroundingtooth structure (enamel, 343KHN; dentin, 68 KHN)21of diamond versus aluminum oxide polishing pastes needs to be studied. Further investigation also needs to be done to ascertain the d c i e n c y of gross contouring of composite resin restorative materials with reciprocal-action instrumentation. This study demonstrated that 50-pdia-
CONCLUSIONS The following conclusions were reached when using reciprocal-action polishing procedures: 1.
2.
3.
4.
5.
6.
7.
8.
9.
A 50-p diamond-coated metal tip produced scratches that were not consistently removed by subsequent abrasives. The best tip of those tested for initial polishing is a 30-pdiamond-coated metal tip. The best sequence for polishing the microfilled composite resin restorative material was 30-l.~+ 15-pdiamond-coated metal tips followed by 3-p diamond polishing paste used with nonabrasive plastic tips. When this sequence was used, the level of polish was better than the surfaces of the controls, which were achieved by using the SofLex discs. The best sequence for polishing the hybrid composite resin restorative material was 30-p + 15-p diamond-coated metal tips followed by 3-p and then 0.5-pdiamond polishing pastes used with nonabrasive plastic tips. Using submicron polishing pastes, whether diamond or aluminum oxide, on microfilled composite resin restorative material may cause degradation of the surface polish. Using submicron diamond polishing paste produced a better polish than submicron aluminum oxide polishing pastes on the hybrid composite resin restorative material. Thereis a discerniblybetterpolishofthemicrofilled composite resin restorative material over the hybrid composite resin restorative material at all levels of polishing and with all instruments used. This instrumentation for polishingcompositeresin restorative materials would seem to be an advantage in accessing interproximal or subgingival areas. This type of instrumentation is a valuable adjunct to, but does not replace, disc polishing since discs are much faster and more eflcient for polishing accessible surfaces.
REFERENCES Stoddard J W . Johnson GH. An evaluation of polishing agentsfor composite resins.J Prosthet Dent 1991 ;65;491495. 2. Kanter J, Koski RE. An evaluation of new methods for polishing composite restorative resins. Quintessence Int 1980;8:91-95. 3. Kanter J, Koskl RE,Bogdan MS.How to achieve the best surface polish on composite resins. Can Dent Assoc J 1983;5:40-45. 1.
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4. 5. 6.
7.
8. 9. 10.
11.
12.
Lambrechts P. Vanherle G. Observation and comparison of polished composite surface with the aid of SEM and profilometer (part I). J Oral Rehabil 1982; 9: 169-182. Lambrechts P, Vanherle G. Observation and comparison of polished composite surface with the aid of SEM and profilometer (part 11). J Oral Rehabil 1982; 9:203-216. Bauer JG. Caputo AA. The surface of composite resin finished with instruments and matrixes. J Prosthet Dent 1983; 50:351-357. Lutz F, Setco J, Phillips R. New finishing instruments for composite resins. J Am Dent Assoc 1983; 107:575-580. BoghosianAA,Randolph RG, ValdemarsJJ. Rotary instrument finishing of microfilled and small-particle hybrid composite resins. J Am Dent Assoc 1987; 115:299-301. Weinstein AR. Composite resin finishing systems. Ohio Dent J 1983: 57:33-43. Quiroz L, Lentz DL. The effect of polishing procedures on light-cured compositerestorations. Compend Contin Educ 1985; VI:437439. Hosoda H, Yamada T, Inokoshi S. SEM and elemental analysis ofcompositeresins. J Prosthet Dent 1990;64:669676. Hansen EK, Asmussen E. Effect of postponed polishing on marginal adaDtation of resins used with dentin-bonding age;. Scandk Dent Res 1988;96:260-264.
13. Reinhaardt J W ,Denehy GE. Chan KC. et al. Determining smoothness of polished microfilled composite resins. J Prosthet Dent 1983; 49:485-490. 14. Staley C, Kopel H. Smoothness of composite restorations polished by various abrasives: a comparison by scanning electron microscopy. J Oper Dent 1979; 4:140-148. 15. Tjan AHL. Chan CA. The polishability of posterior composites. J Prosthet Dent 1989; 561:138-146. 16. Phillips RW. Science of dental materials. 8th Ed. Philadelphia: WB Saunders, 1982:595. 17. Small KL,Goldfogel MH, Hicks MJ. Marginal finishing for cast gold restorations: reciprocal-action instrumentation. J Prosthet Dent 1987: 5Ek403-408. 18. Barkmeier WW. Personal communication. Creighton University School of Dentistry, Omaha, NE. 19. Lide DR, ed. C.R.C. handbook of chemistry and physics. 72nd Ed. Boca Raton, FL: C.R.C. Press. 1991-92; Section 12:138. 20. Lambrechts P. Basic properties of dental composites and their impact on clinical performance. (Thesis).Katholieke Universiteit Leuven, Leuven, Belgium, 1983:92. 21. Craig RG. Restorative dental materials, 8th Ed. St. Louis: CV Mosby. 1989; 100:514.
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