Three Composite Finishing Systems: A Multisite In Vitro EvaIuat ion Steven R. Jefferies, M.S., D.D.S." Wayne W . Barkmeier, D.D.S., M.S. A. John Gwinnett, Ph.D., B.D.S., L.D.S.R.C.S., F.A.D.M.
'
Selection of appropriate finishing and polishing devices is critical to the optimal appearance and longevity of composite resin restoratives. This report compares the effectiveness of three specific finishing and polishing systems when used to prepare the surfaces of composite restorative materials provided by the respective manufacturers. Profilometer surface roughness analyses were conducted at two separate laboratories to cross-correlate numerical smoothness data in this study. Statistically significant differences in mean surface roughness were found between various finishing system/composite resin pairings. Surprisingly, a hybrid composite resin finished and polished with its respective finishing/polishing system gave a significantly smoother surface than a microfill composite surface prepared with its corresponding sequentially coated abrasive disc system. This finding was corroborated at a second site using a separate methodology for profilometer analysis.
P
burs; (3)application of a 1-p aluminous oxide polishing paste using a soft rubber cup; and (4) final polishing using a 0.3-p polishing paste and a soft rubber cup. Both polishing pastes are applied first dry, then with increasing amounts of water for optimal polishing. This finishing system is recommended by the manufacturer for their hybrid resin composite, Herculite XR. The Sof-Lex (3M Dental F'roducts, St. Paul, MN) Finishing System is a series of four coated abrasive discs that decrease in aggressiveness and particle size as one progresses from coarse through medium, fine, and super-fine discs. This finishing system has demonstrated efficacy with microfill composite restoratives such as Silux and Silux-Plus.' Most recently a unique finishing and polishing system was introduced. The Enhance Finishing and Polishing System (L.D. Caulk/Dentsply, Milford, DE) consists of (1)a flexible, bonded abrasive finishing disc that can be used for contouring and initial finishing of the restoration, (2) a 1-p aluminous oxide polishing paste applied with a synthetic foam polishing cup, and (3)final polishing with a 0.3-p aluminous oxide polishing paste, also applied with a synthetic foam polishing cup. Both pastes are applied fist dry, then with increasing amounts of water for optimal polishing. The manufacturer of the Enhance System recommends this method for their hybrid composite restorative, Prisma AP.H., and other composite restoratives. The primary objective of this evaluation was to determine the comparative effectiveness of three spe-
roper finishing and polishing of dental restorations are critical clinical procedures that enhance both esthetics and longevity of restored teeth. Residual surface roughness, associated with composite resin restorations, can result in a number of clinical problems for the dentist and the patient, namely: plaque accumulation, gingival irritation, and surface staining. Finishing and polishing devices may be grouped into four broad classifications: (1) coated abrasives such as abrasive finishing discs, (2) cutting devices such as carbide burs, (3)micron-sized diamond finishing burs and other bonded or rubberized abrasives, and (4)loose, particulate abrasives such as polishing pastes or powders. Three well-known ihishing systems are available that utilize one or more of these finishing/ polishing methods. The X R Finishing System (Kerr Manufacturing, Romulus, MI) employs four separate steps: (1) initial contouring using 8- and 12-bladed finishing burs; (2) finishing and minor contouring with 30-fluted finishing *Director of Clinical Research. L.D. Caulk Division/Dentsply International, Milford, Delaware: t h s o c i a t e Dean for Research and Professor of Operative Dentistry. Creighton University. School of Dentistry, Omaha, Nebraska: $ Professor of Oral Biology and Pathology, School of Dental Medicine. Health Sciences Center, SUNY at Stony Brook, Stony Brook. New York This study was supported in part by the L.D. Caulk Division/Dentsply International and the Health Future Foundation. Address reprint requests to Steven R Jefferies. M.S.. D.D.S., Director of Clinical Research, L.D. CauIk Division/Dentsply International. Milford, DE 19963-0359 0 1992 Decker Periodicals Inc.
181
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4.NUMBER 6 November/December 1992
x 3 mm, and were prepared by extruding the resin from the syringe onto a glass microscope slide and being compressed into a planoparallel, rectangular shape by pressing a second slide on top of the ribbon or resin. The covered resin was polymerized according to the manufacturer’s instructions using a Max curing light (L.D. Caulk/Dentsply). The glass cover slide was removed prior to finishing and polishing. The surface of each Silwr-Plus specimen was prepared sequentially using medium, fine, and superfine Sof-Lex discs. The Prisma AP.H specimens were fmished and polished using the Enhance Finishing and Polishing System (L.D. Caulk/Dentsply) according to the manufacturer’s directions. Each step in both finishing and polishing methods was optimized based on visible and light optical microscope examination of the surface. Each step was discontinued when no further improvement occurred. Surface roughness was measured using a Mitutoyo Surftest 402 roughness tester (Mitutoyo Corporation, Tokoyo, Japan). Three profiles were run, each 0.5 mm apart with sampling length of 0.75 mm divisible by three increments. The registered R a value was averaged for the three traverses. The profilometer results at both sites were statistically analyzed using analysis of variance (ANOVA) and the Student-Neuman-Kuels procedure to test for differences among means.
cific finishing and polishing systems when utilizing composite restorative materials provided by the respective manufacturer. A secondary objective was to crosscorrelate numerical smoothness data, using profilometer analysis conducted at two separate laboratories.
MATERIALS AND METHODS Sample preparation, finishing procedures, and profdometer analysis at Site 1 were conducted as described below. Cylindrical samples of composite resin were prepared as described previously.2 Duplicate cylindrical samples, 5 mm in diameter by 2 mm in depth, were luted onto either end of a glass microscope slide. Each set of duplicate samples were finshed with one of the following three finishing/polishing systems: (1)Soft-Lex(3M). medium, fine, and superfine discs, (2) X R Finishing System (Ken-),used as per manufacturer’s instructions, and (3)Enhance Finishing and Polishing System (L.D. Caulk), used as per manufacturer’s instructions. Each of these Snishing systems were used with their respective composite systems, namely SiluxPlus (3M). Herculite XR (Kerr),and prisma AP.H (L.D. Caulk). A crossover of two of the finishmg systems and composite resins was conducted using Sof-Lex and Prisma AP.H, and the Enhance Finishing/Polishing System and Silux-Plus. The Enhance and X R Finishing Systems were used as per manufacturer’s instructions. The Sof-Lex system was used as described in a prior report2 Profdometer analysis at Site 1was conducted in the followingmanner. After completing a specific finishing/ polishing procedure, the specimen was rinsed with water and air dried. All specimens at this site were then tested for average surface roughness using a Surftest 201, Series 178 Surface Texture Analyzer (Mitutoyo Corporation, Tokoyo, Japan). The roughness average (Ra) of a surface is defmed as the average value of the height of the surface profile above and below a center line throughout a prescribed sample length. To minimize the effects of surface waviness, the Surftest 201 was set to use three intervals to calculate the average surface roughness (Ra).The interval evaluation length used in this study was 0.25 mm, and the total transverse length was 0.75 mm. The diamond stylus had a radius of 5 microns and the stylus speed was 0.5 mm per second. Three profllometer tracings were made near the center of each specimen. Each tracing was made adjacent and pardel to the previous tracing. Therefore, each resin evaluated (at Site 1) had a total of six Ra readings (2 samples x 3 tracings). The numerical average of the six profilometer tracings was designated as the mean Ra for that (material/finishingmethod) system. Specimen preparation and profilometer analysis was conducted at Site 2 in the following manner. Five samples were made from two composite resins: AP.H (L.D. Caulk/Dentsply) and Silux-Plus (3M).The samples were approximately rectangular, measuring 20 x 5
RESULTS The surface smoothness data for the three respective composite/finshing systems pairings are presented inTable 1 and Figure 1.While all three finishing/polishing systems yielded relatively smooth surfaces, some differenceswere noted. The average surface roughness of the systems tested ranked in the followingorder from AVERAGE SURFACE ROUGHNESS (Ra) FOR VARIOUS COMPOSITES/FINISHING SYSTEMS KFW ERCU-ITE
-2
1 .
0.21
0-14
x
m SFI
SlLUx PL!Js
m EFs/
miw
s n
I
t I
Figure 1. Graph denotes the average surface roughness (Ra) for three composite resins flnished with their respective Anishing systems. (KFS=XRFinishing System, Herculite X=Hercullte XR, SF=Sof-Lex, EFS=EnhanceFinishing System)
182
Composite Finishing Systems
Table 1. Average Surface Roughness (p)for Resin Restorative Materials Finished with Different Finishing/PolishingMethods Materia//Finishing Method
Mean SD
AP.H/Enhance
.068 2 ,009
Silux-Plus/Sof-Lex
.127 2.031
HerculiteXR/ Kerr Finish. System
,182f,134
Table 2. Comparison of Profilometer Resultsfrom Two Sites for Average Surface Roughness (p)for Resin Restorative Materials Finished with Different Finishing/PolishingMethods Material/Finishing Method
Site 1
Site2
AP. H/Enhance
Mean SD ,068 f ,009
Mean SD ,078 k .008
Silux-Plus/Sof-Lex
,127 f ,031
.158f .026
Figure 3. Amalaligned short right lateral incisor in a 24-yearold patient.
smoothest (lowest Ra) to roughest (highest Ra): Enhance/AP.H < Sof-Lex/Silux-Plus< X R Finishing System/Herculite X R . Of note is the significant variability displayed in the Herculite X R surface finished and polished with the X R Finishing System. Table 2 and Figure 2 demonstrate the comparative surface smoothness of AP.H finished with the Enhance System versus that obtained with Silux-Plus Anished with the Sof-Lex disc finishing system. The surface smoothness of the AP.H is significantly smoother (p < .05)than that obtainable on the microfill, SiluxPlus, when finished with the sequential disc system. This statistically signislcantdifferencein surface smooth-
Figure 4. The same maxillary right lateral incisor restored with Prisma AP.H at 3-year recall. Table 3. Average Surface Roughness (p) for AP.H Hybrid Restorative Finished with Two Different Finishing/Polishing Methods
AVERAGE SURFACE ROUGHNESS (Ra)FOR VARIOUS COMPOSITES/FINISHING SYSTEMS SFI
SlLllX
020
5
Rus
MateriaVFjnishIng Method
ma EFsl
PRlSMA APH
1
0.12
No.of Procedure Steps
Mean SD
AP.H/Enhance Finishing System
3 steps
,0682.009
AP. H/Sof-Lex, Enhance Pad, Prisma Gloss, Prisma Gloss Extra Fine
5 steps
.067 2 ,005
B Table 4. Average Surface Roughness (p) for Microfil Composite Silux-Plus Finished with Enhance Finishing System or SofLex Abrasive Discs
0.08
0.04
0.00
Figure 2. Graph denotes the average surface roughness (Ra) for the microtlll, Sflux-Plus,finishedwith Sof-Lex,as compared tothe hybrid,PrismaAP.H, finishedwiththeEnhanceFinishing System. (SF=Sof-Lex,EFS=EnhanceFinishing System)
183
Material/Finishing Method
No. of Procedure Steps
Silux-Plus/Sof-Lex
3 steps
.158 2 ,026
Silux-Plus/Enhance Finishing System
3 steps
,144 .019
Mean
SD
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 6 November/December 1992
ciently low to produce a highly polished surface that is light reflective to visual inspection. The Enhance Finishing System employs an altemative approach to initial contouring and finishing, namely a flexible bonded-abrasive disc. After initial finishing and polishing with the disc, the restoration is polished with sequential aluminous oxide polishing pastes applied with a porous foam cup. The results of this study indicate that this system can produce a highly polished surface, with low average surface roughness, on hybrid composite materials such as Prisma M . H . This system may also be appropriate for finishing microfill composites, with surface smoothness results similar to those achieved with the Sof-Lex system. The variation of surface smoothness, as exhibited by the standard deviations presented in the various data sets, is noteworthy. Standard deviations in the data ranged from a high of k .134p for the Herculite X R finished with the X R Finishing System; to k .031p for Silux-Plus finished with Sof-Lex; and to an extremely low coefficient of variance, f .009 p, for Prisma AP.H finished with the Enhance Finishing System. It appears that fluted finishing burs and, to a lesser extent, coatedabrasive discs, while effective, may leave residual surface anomalies that are difficult to completely eliminate in subsequent polishing steps in the finishing procedure. It is worth noting that earlier published studies have clearly demonstrated the effectiveness of aluminous oxide polishing pastes in improving the surface smoothness and appearance of hybrid composites such as Prisma AP.H and Herculite XR.24 In two of the investigations, initial contouring and finishing was accomplished with three grades of Sof-Lex discs (medium, fine, and superfine),followed by the sequential application of 1 .O- and 0.3-paluminous oxide polishing pastes. The results obtained with the Enhance System, a threestep approach involving a bonded-abrasive disc, and two aluminous oxide pastes applied with a foam-cup device, appear very comparable to the Sof-Lex/Paste combination mentioned above, but with two fewer finishing steps. Also as noted in one of these earlier s t ~ d i e s , ~ traditional microfill composites composed of organic filler, such as Silux-Plus, appear to have a distinct lower threshold of surface smoothness. This level of surface smoothness does not improve, regardless of method or specific fmishing/polishing devices that are employed. Hybrid composites, such as Prisma AP.H and Herculite X R , however, appear to undergo additional improvement in surface finish below this level of surface roughness, reflected by statistically lower Ra values. This improvement in surface finish is produced by sequential application of polishing pastes, optimally by felt or foam rotary application devices. This ability of polishing pastes, when applied after coated abrasive discs (Sof-Lex) or a bonded abrasive disc (Enhance Sensor Finishing Disc), to render a highly smooth surface on hybrid composites, may improve the
ness between the microfilland the hybrid was confirmed in a separate independent profilometer evaluation undertaken at Site 2 (Table2). Based on these corroborated findings, a statistically significant difference exists between mean Ra values obtained for AP.H using the Enhance Finishing System compared to the optimal value achieved for Silux-Plus using the Sof-Lex disc system. Figures 3 and 4 illustrate a typical clinical example of the surface smoothness of the AP.H system. Table 3 compares the surface smoothness of the AP.H hybrid composite finished with the Enhance Finishing System to that obtainable with the Sof-Lex disc system followed by application of two sequential polishing pastes. The data from the system (AP.H/Sof-Lex, Enhance Pad, Prisma-Gloss, and Prisma-Gloss Extra Fine) comes from an earlier study.3The final two polishing paste steps of this finishing procedure are almost identical to the final two steps of the Enhance Finishing System: the only difference is the use of a foam cup for paste application in the Enhance System, whereas the Enhance Pad is a foam pad of different dimensions used to apply the polishing pastes after finishing with the SofLex system. Table 4 compares data concerning the finishing efficacy of the Sof-Lex disc system2 and, alternatively, the Enhance Finishing System on the microfill composite, Silux-Plus. The average surface roughness data presented in this comparison indicates a lack of a statistically sigmikant difference between the finishing systems at the (95%)confidence level.
DISCUSSlON The three finishing systems evaluated in this investigation represent four distinct types of finishing devices used in restorative dental procedures. The X R Finishing System relies heavily upon the use of sequential fluted finishingburs followed by sequentiallyapplied composite polishing pastes. While this appears to be an efficacious approach, permitting the use of high-speed handpieces in the initial finishing procedure, the profilometer data of this investigation indicates a large variance in the average surface smoothness produced by the XR System on Herculite X R . It may be that the initial sequential finishing bur steps can leave irregulaxities of such magnitude that they can not be refined and eliminatedby the subsequent polishingpaste steps. 'The use of finishing burs at high speed may have also created more operator-dependent variability in the final overall smoothness of the composite resin surface. The Sof-Lex disc system is a classic, coated-abrasive system, utilizing abrasive particles of decreasing size and abrasiveness over the three or four discs used clinically to h i s h and polish composite resins. Data from this, and other studies, indicate that the Sof-Lex disc system is highly effective for microfill composites, such as Silux-Plus. The average surface roughness on Silux-Plus, after Sof-Lexfinishing, appears to be suffi184
Composite Finishing Systems
longevity of surface smoothness and polish on these hybrids. This investigation has provided evidence for this concept; however, more data are needed.
storative group and the Silux-Plus/Sof-Lex restorative group was statistically significant. This difference in mean surface roughness was corroborated at a second site using a separate methodology for profilometer analysis.
CONCLUSIONS 1.
2.
3.
Statistically significant differences in mean surface roughness exist between various composite finishing systems when used to finish and polish the respective composite resin produced by the same manufacturer. The rank order of the finishing system/composite resin groupings in mean surface smoothness (Ra) were as follows, from lowest to highest mean surface roughness: Prisma AP.H/Enhance Finishing system < Silux Plus/Sof-Lex < Herculite XR/xRFinishing System. The difference in mean surface roughness between the Prisma AP.H/Enhance Finishing Surface re-
REFERENCES Chen RCS, Chan DCN, Chan KC. A quantitative study of finishing and polishing techniques for a composite. J Prosthet Dent 1988: 59(2):292-297. Jefferies SR, Smith RL, Barkmeier WW, Gwinnett AJ. Comparison of surface smoothness of restorative resin materials. J Esthet Dent 1989: 1(5):169-175. Jefferies SR, Smith RL, Barkmeier WW, Gwinnett A J . Benefit of polishing pastes on various resin composites. J Dent Res 1991: 70 (Special Issue):291. (Abstr 1006). Northeast SE, Van Noort R. Surface characteristics of finished composite resins. Dent Mat 1988: 4:278-288.
185
'
Selection of appropriate finishing and polishing devices is critical to the optimal appearance and longevity of composite resin restoratives. This report compares the effectiveness of three specific finishing and polishing systems when used to prepare the surfaces of composite restorative materials provided by the respective manufacturers. Profilometer surface roughness analyses were conducted at two separate laboratories to cross-correlate numerical smoothness data in this study. Statistically significant differences in mean surface roughness were found between various finishing system/composite resin pairings. Surprisingly, a hybrid composite resin finished and polished with its respective finishing/polishing system gave a significantly smoother surface than a microfill composite surface prepared with its corresponding sequentially coated abrasive disc system. This finding was corroborated at a second site using a separate methodology for profilometer analysis.
P
burs; (3)application of a 1-p aluminous oxide polishing paste using a soft rubber cup; and (4) final polishing using a 0.3-p polishing paste and a soft rubber cup. Both polishing pastes are applied first dry, then with increasing amounts of water for optimal polishing. This finishing system is recommended by the manufacturer for their hybrid resin composite, Herculite XR. The Sof-Lex (3M Dental F'roducts, St. Paul, MN) Finishing System is a series of four coated abrasive discs that decrease in aggressiveness and particle size as one progresses from coarse through medium, fine, and super-fine discs. This finishing system has demonstrated efficacy with microfill composite restoratives such as Silux and Silux-Plus.' Most recently a unique finishing and polishing system was introduced. The Enhance Finishing and Polishing System (L.D. Caulk/Dentsply, Milford, DE) consists of (1)a flexible, bonded abrasive finishing disc that can be used for contouring and initial finishing of the restoration, (2) a 1-p aluminous oxide polishing paste applied with a synthetic foam polishing cup, and (3)final polishing with a 0.3-p aluminous oxide polishing paste, also applied with a synthetic foam polishing cup. Both pastes are applied fist dry, then with increasing amounts of water for optimal polishing. The manufacturer of the Enhance System recommends this method for their hybrid composite restorative, Prisma AP.H., and other composite restoratives. The primary objective of this evaluation was to determine the comparative effectiveness of three spe-
roper finishing and polishing of dental restorations are critical clinical procedures that enhance both esthetics and longevity of restored teeth. Residual surface roughness, associated with composite resin restorations, can result in a number of clinical problems for the dentist and the patient, namely: plaque accumulation, gingival irritation, and surface staining. Finishing and polishing devices may be grouped into four broad classifications: (1) coated abrasives such as abrasive finishing discs, (2) cutting devices such as carbide burs, (3)micron-sized diamond finishing burs and other bonded or rubberized abrasives, and (4)loose, particulate abrasives such as polishing pastes or powders. Three well-known ihishing systems are available that utilize one or more of these finishing/ polishing methods. The X R Finishing System (Kerr Manufacturing, Romulus, MI) employs four separate steps: (1) initial contouring using 8- and 12-bladed finishing burs; (2) finishing and minor contouring with 30-fluted finishing *Director of Clinical Research. L.D. Caulk Division/Dentsply International, Milford, Delaware: t h s o c i a t e Dean for Research and Professor of Operative Dentistry. Creighton University. School of Dentistry, Omaha, Nebraska: $ Professor of Oral Biology and Pathology, School of Dental Medicine. Health Sciences Center, SUNY at Stony Brook, Stony Brook. New York This study was supported in part by the L.D. Caulk Division/Dentsply International and the Health Future Foundation. Address reprint requests to Steven R Jefferies. M.S.. D.D.S., Director of Clinical Research, L.D. CauIk Division/Dentsply International. Milford, DE 19963-0359 0 1992 Decker Periodicals Inc.
181
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4.NUMBER 6 November/December 1992
x 3 mm, and were prepared by extruding the resin from the syringe onto a glass microscope slide and being compressed into a planoparallel, rectangular shape by pressing a second slide on top of the ribbon or resin. The covered resin was polymerized according to the manufacturer’s instructions using a Max curing light (L.D. Caulk/Dentsply). The glass cover slide was removed prior to finishing and polishing. The surface of each Silwr-Plus specimen was prepared sequentially using medium, fine, and superfine Sof-Lex discs. The Prisma AP.H specimens were fmished and polished using the Enhance Finishing and Polishing System (L.D. Caulk/Dentsply) according to the manufacturer’s directions. Each step in both finishing and polishing methods was optimized based on visible and light optical microscope examination of the surface. Each step was discontinued when no further improvement occurred. Surface roughness was measured using a Mitutoyo Surftest 402 roughness tester (Mitutoyo Corporation, Tokoyo, Japan). Three profiles were run, each 0.5 mm apart with sampling length of 0.75 mm divisible by three increments. The registered R a value was averaged for the three traverses. The profilometer results at both sites were statistically analyzed using analysis of variance (ANOVA) and the Student-Neuman-Kuels procedure to test for differences among means.
cific finishing and polishing systems when utilizing composite restorative materials provided by the respective manufacturer. A secondary objective was to crosscorrelate numerical smoothness data, using profilometer analysis conducted at two separate laboratories.
MATERIALS AND METHODS Sample preparation, finishing procedures, and profdometer analysis at Site 1 were conducted as described below. Cylindrical samples of composite resin were prepared as described previously.2 Duplicate cylindrical samples, 5 mm in diameter by 2 mm in depth, were luted onto either end of a glass microscope slide. Each set of duplicate samples were finshed with one of the following three finishing/polishing systems: (1)Soft-Lex(3M). medium, fine, and superfine discs, (2) X R Finishing System (Ken-),used as per manufacturer’s instructions, and (3)Enhance Finishing and Polishing System (L.D. Caulk), used as per manufacturer’s instructions. Each of these Snishing systems were used with their respective composite systems, namely SiluxPlus (3M). Herculite XR (Kerr),and prisma AP.H (L.D. Caulk). A crossover of two of the finishmg systems and composite resins was conducted using Sof-Lex and Prisma AP.H, and the Enhance Finishing/Polishing System and Silux-Plus. The Enhance and X R Finishing Systems were used as per manufacturer’s instructions. The Sof-Lex system was used as described in a prior report2 Profdometer analysis at Site 1was conducted in the followingmanner. After completing a specific finishing/ polishing procedure, the specimen was rinsed with water and air dried. All specimens at this site were then tested for average surface roughness using a Surftest 201, Series 178 Surface Texture Analyzer (Mitutoyo Corporation, Tokoyo, Japan). The roughness average (Ra) of a surface is defmed as the average value of the height of the surface profile above and below a center line throughout a prescribed sample length. To minimize the effects of surface waviness, the Surftest 201 was set to use three intervals to calculate the average surface roughness (Ra).The interval evaluation length used in this study was 0.25 mm, and the total transverse length was 0.75 mm. The diamond stylus had a radius of 5 microns and the stylus speed was 0.5 mm per second. Three profllometer tracings were made near the center of each specimen. Each tracing was made adjacent and pardel to the previous tracing. Therefore, each resin evaluated (at Site 1) had a total of six Ra readings (2 samples x 3 tracings). The numerical average of the six profilometer tracings was designated as the mean Ra for that (material/finishingmethod) system. Specimen preparation and profilometer analysis was conducted at Site 2 in the following manner. Five samples were made from two composite resins: AP.H (L.D. Caulk/Dentsply) and Silux-Plus (3M).The samples were approximately rectangular, measuring 20 x 5
RESULTS The surface smoothness data for the three respective composite/finshing systems pairings are presented inTable 1 and Figure 1.While all three finishing/polishing systems yielded relatively smooth surfaces, some differenceswere noted. The average surface roughness of the systems tested ranked in the followingorder from AVERAGE SURFACE ROUGHNESS (Ra) FOR VARIOUS COMPOSITES/FINISHING SYSTEMS KFW ERCU-ITE
-2
1 .
0.21
0-14
x
m SFI
SlLUx PL!Js
m EFs/
miw
s n
I
t I
Figure 1. Graph denotes the average surface roughness (Ra) for three composite resins flnished with their respective Anishing systems. (KFS=XRFinishing System, Herculite X=Hercullte XR, SF=Sof-Lex, EFS=EnhanceFinishing System)
182
Composite Finishing Systems
Table 1. Average Surface Roughness (p)for Resin Restorative Materials Finished with Different Finishing/PolishingMethods Materia//Finishing Method
Mean SD
AP.H/Enhance
.068 2 ,009
Silux-Plus/Sof-Lex
.127 2.031
HerculiteXR/ Kerr Finish. System
,182f,134
Table 2. Comparison of Profilometer Resultsfrom Two Sites for Average Surface Roughness (p)for Resin Restorative Materials Finished with Different Finishing/PolishingMethods Material/Finishing Method
Site 1
Site2
AP. H/Enhance
Mean SD ,068 f ,009
Mean SD ,078 k .008
Silux-Plus/Sof-Lex
,127 f ,031
.158f .026
Figure 3. Amalaligned short right lateral incisor in a 24-yearold patient.
smoothest (lowest Ra) to roughest (highest Ra): Enhance/AP.H < Sof-Lex/Silux-Plus< X R Finishing System/Herculite X R . Of note is the significant variability displayed in the Herculite X R surface finished and polished with the X R Finishing System. Table 2 and Figure 2 demonstrate the comparative surface smoothness of AP.H finished with the Enhance System versus that obtained with Silux-Plus Anished with the Sof-Lex disc finishing system. The surface smoothness of the AP.H is significantly smoother (p < .05)than that obtainable on the microfill, SiluxPlus, when finished with the sequential disc system. This statistically signislcantdifferencein surface smooth-
Figure 4. The same maxillary right lateral incisor restored with Prisma AP.H at 3-year recall. Table 3. Average Surface Roughness (p) for AP.H Hybrid Restorative Finished with Two Different Finishing/Polishing Methods
AVERAGE SURFACE ROUGHNESS (Ra)FOR VARIOUS COMPOSITES/FINISHING SYSTEMS SFI
SlLllX
020
5
Rus
MateriaVFjnishIng Method
ma EFsl
PRlSMA APH
1
0.12
No.of Procedure Steps
Mean SD
AP.H/Enhance Finishing System
3 steps
,0682.009
AP. H/Sof-Lex, Enhance Pad, Prisma Gloss, Prisma Gloss Extra Fine
5 steps
.067 2 ,005
B Table 4. Average Surface Roughness (p) for Microfil Composite Silux-Plus Finished with Enhance Finishing System or SofLex Abrasive Discs
0.08
0.04
0.00
Figure 2. Graph denotes the average surface roughness (Ra) for the microtlll, Sflux-Plus,finishedwith Sof-Lex,as compared tothe hybrid,PrismaAP.H, finishedwiththeEnhanceFinishing System. (SF=Sof-Lex,EFS=EnhanceFinishing System)
183
Material/Finishing Method
No. of Procedure Steps
Silux-Plus/Sof-Lex
3 steps
.158 2 ,026
Silux-Plus/Enhance Finishing System
3 steps
,144 .019
Mean
SD
JOURNAL OF ESTHETIC DENTISTRY VOLUME 4, NUMBER 6 November/December 1992
ciently low to produce a highly polished surface that is light reflective to visual inspection. The Enhance Finishing System employs an altemative approach to initial contouring and finishing, namely a flexible bonded-abrasive disc. After initial finishing and polishing with the disc, the restoration is polished with sequential aluminous oxide polishing pastes applied with a porous foam cup. The results of this study indicate that this system can produce a highly polished surface, with low average surface roughness, on hybrid composite materials such as Prisma M . H . This system may also be appropriate for finishing microfill composites, with surface smoothness results similar to those achieved with the Sof-Lex system. The variation of surface smoothness, as exhibited by the standard deviations presented in the various data sets, is noteworthy. Standard deviations in the data ranged from a high of k .134p for the Herculite X R finished with the X R Finishing System; to k .031p for Silux-Plus finished with Sof-Lex; and to an extremely low coefficient of variance, f .009 p, for Prisma AP.H finished with the Enhance Finishing System. It appears that fluted finishing burs and, to a lesser extent, coatedabrasive discs, while effective, may leave residual surface anomalies that are difficult to completely eliminate in subsequent polishing steps in the finishing procedure. It is worth noting that earlier published studies have clearly demonstrated the effectiveness of aluminous oxide polishing pastes in improving the surface smoothness and appearance of hybrid composites such as Prisma AP.H and Herculite XR.24 In two of the investigations, initial contouring and finishing was accomplished with three grades of Sof-Lex discs (medium, fine, and superfine),followed by the sequential application of 1 .O- and 0.3-paluminous oxide polishing pastes. The results obtained with the Enhance System, a threestep approach involving a bonded-abrasive disc, and two aluminous oxide pastes applied with a foam-cup device, appear very comparable to the Sof-Lex/Paste combination mentioned above, but with two fewer finishing steps. Also as noted in one of these earlier s t ~ d i e s , ~ traditional microfill composites composed of organic filler, such as Silux-Plus, appear to have a distinct lower threshold of surface smoothness. This level of surface smoothness does not improve, regardless of method or specific fmishing/polishing devices that are employed. Hybrid composites, such as Prisma AP.H and Herculite X R , however, appear to undergo additional improvement in surface finish below this level of surface roughness, reflected by statistically lower Ra values. This improvement in surface finish is produced by sequential application of polishing pastes, optimally by felt or foam rotary application devices. This ability of polishing pastes, when applied after coated abrasive discs (Sof-Lex) or a bonded abrasive disc (Enhance Sensor Finishing Disc), to render a highly smooth surface on hybrid composites, may improve the
ness between the microfilland the hybrid was confirmed in a separate independent profilometer evaluation undertaken at Site 2 (Table2). Based on these corroborated findings, a statistically significant difference exists between mean Ra values obtained for AP.H using the Enhance Finishing System compared to the optimal value achieved for Silux-Plus using the Sof-Lex disc system. Figures 3 and 4 illustrate a typical clinical example of the surface smoothness of the AP.H system. Table 3 compares the surface smoothness of the AP.H hybrid composite finished with the Enhance Finishing System to that obtainable with the Sof-Lex disc system followed by application of two sequential polishing pastes. The data from the system (AP.H/Sof-Lex, Enhance Pad, Prisma-Gloss, and Prisma-Gloss Extra Fine) comes from an earlier study.3The final two polishing paste steps of this finishing procedure are almost identical to the final two steps of the Enhance Finishing System: the only difference is the use of a foam cup for paste application in the Enhance System, whereas the Enhance Pad is a foam pad of different dimensions used to apply the polishing pastes after finishing with the SofLex system. Table 4 compares data concerning the finishing efficacy of the Sof-Lex disc system2 and, alternatively, the Enhance Finishing System on the microfill composite, Silux-Plus. The average surface roughness data presented in this comparison indicates a lack of a statistically sigmikant difference between the finishing systems at the (95%)confidence level.
DISCUSSlON The three finishing systems evaluated in this investigation represent four distinct types of finishing devices used in restorative dental procedures. The X R Finishing System relies heavily upon the use of sequential fluted finishingburs followed by sequentiallyapplied composite polishing pastes. While this appears to be an efficacious approach, permitting the use of high-speed handpieces in the initial finishing procedure, the profilometer data of this investigation indicates a large variance in the average surface smoothness produced by the XR System on Herculite X R . It may be that the initial sequential finishing bur steps can leave irregulaxities of such magnitude that they can not be refined and eliminatedby the subsequent polishingpaste steps. 'The use of finishing burs at high speed may have also created more operator-dependent variability in the final overall smoothness of the composite resin surface. The Sof-Lex disc system is a classic, coated-abrasive system, utilizing abrasive particles of decreasing size and abrasiveness over the three or four discs used clinically to h i s h and polish composite resins. Data from this, and other studies, indicate that the Sof-Lex disc system is highly effective for microfill composites, such as Silux-Plus. The average surface roughness on Silux-Plus, after Sof-Lexfinishing, appears to be suffi184
Composite Finishing Systems
longevity of surface smoothness and polish on these hybrids. This investigation has provided evidence for this concept; however, more data are needed.
storative group and the Silux-Plus/Sof-Lex restorative group was statistically significant. This difference in mean surface roughness was corroborated at a second site using a separate methodology for profilometer analysis.
CONCLUSIONS 1.
2.
3.
Statistically significant differences in mean surface roughness exist between various composite finishing systems when used to finish and polish the respective composite resin produced by the same manufacturer. The rank order of the finishing system/composite resin groupings in mean surface smoothness (Ra) were as follows, from lowest to highest mean surface roughness: Prisma AP.H/Enhance Finishing system < Silux Plus/Sof-Lex < Herculite XR/xRFinishing System. The difference in mean surface roughness between the Prisma AP.H/Enhance Finishing Surface re-
REFERENCES Chen RCS, Chan DCN, Chan KC. A quantitative study of finishing and polishing techniques for a composite. J Prosthet Dent 1988: 59(2):292-297. Jefferies SR, Smith RL, Barkmeier WW, Gwinnett AJ. Comparison of surface smoothness of restorative resin materials. J Esthet Dent 1989: 1(5):169-175. Jefferies SR, Smith RL, Barkmeier WW, Gwinnett A J . Benefit of polishing pastes on various resin composites. J Dent Res 1991: 70 (Special Issue):291. (Abstr 1006). Northeast SE, Van Noort R. Surface characteristics of finished composite resins. Dent Mat 1988: 4:278-288.
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