- Email: [email protected]
Marginal leakage in class V composite resin restorations with glass ionomer liners in vitro
Marginal leakage with glass ionomer R. S. Mathis, M.S., D.D.S.,* J. L. Ferracane, Ph.D.**
in class V composite liners in vitro J. P. DeWald,
D.D.S.,*
resin
C. R. Moody,
D.D.S.,*
restorations and
Baylor College of Dentistry, Dallas, Tex., and Oregon Health Sciences University, School of Dentistry, Portland, Ore. This in vitro study evaluated the use of a glass ionomer lining cement in conjunction with composite resin in class V preparations in terms of marginal sealing ability. Two preparations, the occlusal walls in enamel (etched) and the gingival walls in dentin, were place in each tooth. One contained the etched glass ionomer liner, a dentin bonding agent, and a microill composite resin. The second contained the dentin bonding agent and the microfill composite resin. The teeth were thermocycled, stained with methylene blue dye, sectioned, and evaluated for leakage at the occlusal and gingival margins on a scale of 0 to 3. No significant leakage was recorded at the occlusal margin for either restoration. Leakage at the gingival margin was significantly reduced for the lined restorations, and in no instance did the dye penetrate beyond the liner, which suggests that the lining cement may significantly decrease leakage at the gingival aspect of composite resins in class V restorations.(J PROSTRETDENT~QQ~;~~:S~~-~.)
M
arginal leakage around compositeresin restorations, particularly at the gingival aspect, is a major problem in clinical dentistry.l Reducing marginal leakagewill decreasesecondarycaries,pulpal sensitivity, pulpal injury, and discoloration, thereby increasingthe clinical successof the restoration.2p3 Compositeresinsare widely usedin clinical applications, especially where esthetics are a primary concern, for example, in classV restorations. Although there is little leakage at the occlusal aspect of class V restorations becauseof the strength of the etched enamel/composite bond,4*5the bond at the gingival aspect is insufficient becauseof the lack of enamel for adherenceor inadequate prism structure in the available enamel for acceptabletag formations Therefore, to improve the clinical successof compositeresinsin classV restorations, marginal leakage at the gingival aspectmust be minimized. Glassionomer cementsoffer improved marginal sealing ability by chemical adhesionto enameland dentin.7-gAlthough the bond of glassionomer cement to enamel is weaker than the bond of compositeresinsto enamel,1°the bond of glassionomer to dentin is greater than that of compositeresinto dentin and can be further enhancedwith the use of a 25% polyacrylic acid pretreatment.l’ Glass-
Supported by funds from the 3M Foundation, St. Paul, Minnesota and G-C Dental Industrial Corporation, Tokyo, Japan. Presented at the IADR/AADR/CADR, Montreal, Canada. *Assistant Professor, Department of Operative Dentistry, Baylor College of Dentistry. **Associate Professor, Department of Dental Materials, Oregon Health Sciences University, School of Dentistry. 10/l/17711
522
ionomer cement has a coefficient of thermal expansion similar to natural tooth, structure and has been shown to elicit no marginal leakage.5p12-15 However, other properties such as high solubility, low strength, poor esthetics, and surface roughnesslimit its use as a restorative material.16-lsThe bond of etched glassionomer cement to composite resin is stronger than the cement itself.“* lg Therefore, it is logical to expect that glass ionomer cement would serve asan excellent dentinal bonding agent under a composite resin. In addition, becauseglassionomer cementhas a coefficient of thermal expansionsimilar to tooth structure and, unlike compositeresin, doesnot have the potential to “debond” from polymerization shrinkage,oneexpects better adaptation to the cavity wall. Its use alsoreducesthe amount of compositeresin needed, thus further reducing the effects of polymerization shrinkage. This study evaluated the useof glassionomer lining cement under composite resin in classV cavities in terms of in vitro marginal sealingability.
MATERIAL
AND
METHODS
Freshly extracted sound human molars were selected and stored in 70% ethano1.lPrior to tooth preparation the 12teeth were stripped of attached gingiva with a knife and cleaned with flour of pumice using a rubber cup at slow speed.Twenty-four class V preparations were prepared with a rectangular outline form, one on the buccal and one on the lingual surface of each tooth (Fig. 1). The preparations were standardized
in size and extended
4 mm mesio-
distally with a width of 2 mm. The preparations extended into dentin to a total depth of 2 mm. The occlusalcavosurface endedin enameland the gingival cavosurfaceended in dentin.
The cavities were prepared
with a No. 56 tungsten
carbide bur at ultrahigh speedusing air and water spray MAY
1990
VOLUME
68
NUMBEB
5
CLASS
V COMPOSITE
RESIN
RESTORATIONS
Etch Bonding Composite
Agent
Dentin Conditioner Glass lonomer Etch Bonding Agent Composite
Fig. 1. Schematic of cavity preparation and restorations
GINGIVAL MARGIN
OCCLUSALMARGIN 101 9..
-
0 -
LINED UNLINED
- 10 -. Q -. 6 -7 --8
* i2
6 -L 7-w 6-m
Fz
5--
-- 5
E
4--
-- 4
E
3-b
-3
2-1 -. I
O0
1
2
used in study.
r 10
10
-
9--
U -
6 --
LINED UNLINED
-9
--6
*
7--
--7
g
6--
-- 6
5 --
-. 5
4 --
-4
3--
-3
-- 2
2 --
-2
-. 1
1 --
.- 1
-0
o-
3
iG :
-0 0
1
2
3
Fig. 2. Histogram compares leakage scores at occlusal margin for lined and unlined restorations.
Fig. 3. Histogram compares leakage scores at gingival margin for lined and unlined restorations.
coolant. Cavosurface angles were 90 degrees. Prior to restoring, the teeth were rinsed and stored for 1 hour in distilled water. Lining cement was alternately placed in the buccal or lingual preparation for each tooth to avoid bias of data. The remaining preparation of each tooth received no lining cement. The preparations of the lined teeth were rinsed with water and air dried. One drop of dentin conditioner (25 % polyacrylic acid, G-C Dental Industrial Corporation, Tokyo, Japan) was placed on a cotton pellet in a Dappen dish, and the pellet was used to scrub the dentinal surface for 20 seconds. The tooth was rinsed for 10 seconds and dried. The glass ionomer lining cement was weighed at the recommended powder-to-liquid ratio of 1.2 g powder to 1 g liquid (G-C) on an electronic balance to 2 0.001 g.20 The powder was divided into two parts, and each was mixed into the liquid for 15 seconds for a total of 30 seconds. The liner was applied in a thin layer on all internal dentinal surfaces with a calcium hydroxide applicator, and as close to the gingival cavosurface angle as possible to allow room for the composite resin to cover it (Fig. 1). After the initial set of the liner (approximately 4 to 5 minutes) the remaining enamel was acid etched with 35 %
phosphoric acid in a gel base for 40 seconds. After 40 seconds, additional etchant was applied to the liner so that the enamel was etched for 60 seconds and the liner for 20 seconds. The preparation was rinsed for 30 seconds and dried. One drop of resin and one drop of catalyst (Silux LightCured Bonding Agent, Scotchbond, 3M, St. Paul, Minn.) was mixed and applied to the internal surfaces of the cavity with a brush. A gentle stream of air was used to evenly disperse the liquid. The bonding agent was cured for 10 seconds with a Command (Kerr, Romulus, Mich.) light source. Silux composite resin was placed with a plastic instrument and cured 20 seconds with the light-curing unit. The restorations were subsequently finished using all four grades of Sof-flex disks (3M). The restorations that did not receive the liner were treated in the same manner, except without dentin conditioning and liner, and only the enamel was etched. The bonding agent was applied to all internal surfaces of the preparation prior to placing the composite resin. The teeth were then placed in distilled water at 37” C for 48 hours to achieve final cure. The teeth were thermocycled between distilled water baths at 5’ and 55’ C. Each cycle lasted 1 minute for a to-
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
523
MATHIS
tal of 1700 cycles. The root portions and crowns, within 1 mm of the restoration margins, were sealedprior to staining by placing two coatsof acrylic resinvarnish.21The teeth werethen inverted in a thick mix of dental stone in a polyethylene beaker and the stonewasallowedto harden. Subsequently, 0.5% methylene blue dye was poured into the beaker until it covered the restorations by about 2 mm. This procedure prevented dye from penetrating root apices.The beaker wassubsequentlyplaced in the 5’ C bath for 17 hours to causea contraction of the materials which enhancedthe penetration of the dye. The teeth were rinsed with distilled water, air dried, and sectionedlongitudinally in a buccolingual direction on a low-speeddiamond saw. The sectioned sampleswere observed using surface reflection microscopy by two investigators. Leakage around the restorations was rated using the scale of Myers as in Gordon et al.22according to maximum penetration of the dye: 0 = none at the interface of the tooth and restorative material 1 = at the cavosurfaceangle 2 = along the gingival or occlusal walls, but not to the pulpal wall 3 = to the pulpal wall The results were analyzed by using Wilcoxon’s signed ranks test at the p I 0.01 level of significance.
RESULTS Occlusal scoresfor both treatments are shown in Fig. 2 and the gingival scoresappear in Fig. 3. The gingival walls of the unlined restorations showedsignificantly more dye penetration than did both the occlusalwalls of the unlined restorationsand the occlusaland gingival wallsof the lined restorations.
DISCUSSION The occlusalaspect of both lined and unlined restorations revealed only slight leakageat the cavosurfacein only five of the 24restorations. However, onerestoration showed grossleakage.Had the enamelbeen beveledocclusally, the degreeof leakagewould be expected to be even less.At the gingival aspect,however, 10 of the 12 unlined restorations showedgrossleakage.Three of the lined restorations had no leakage,and nine had minimal leakageconfined to the cavosurfacemargin, in all casesnot penetrating beyond the liner. The minimal leakagecan be explained becauseof the difficulty in applying the liner completely to the cavosurface angle,thus allowing the compositeresin to contact the dentin at the point at which leakageoccurred. As evidenced by the unlined restorations, this gingival bond is inadequate. Other studies support these results in that greater leakagehas been observed gingivally versus occlusally1s5 and no leakage occurred below the Silux resin and GI cementz2
524
ET AL
In this study, the reduction in microleakageappearsto be a direct result of the liner, not the bonding agent.23The liner, by chemically adhering to the dentin and providing an adequatesurface for retention of compositeresin, minimizesleakagein two ways: (1) the liner provides a sealing of the dentin below the compositeresin; and (2) the effects of polymerization shrinkage and thermal expansionof the compositeare reduced becausethere is lesscompositeresin in the preparation.
CONCLUSION The resultsof this in vitro study indicate that the useof glass-ionomerlining cementsbelow classV compositeresin restorations may significantly decreasemarginal leakageat the gingival aspect.
REFERENCES 1. Retief DH, Woods E, Jamison HC. Effect of cavosurface marginal leakage in Class V composite resin restorations. DENT
treatment on J PR~STHET
1982;47:496-501.
Hembree JH. Marginal leakage of microfilled composite resin restorations. J PROSTH~ DENT 1983;50:632-5. Christen AG, Mitchell DF. A fluorescent dye method for demonstrating leakage around dental restorations. J Dent Res 1966;45:1485-92. Buonocore MG, Matsui A, Gwinnett AJ. Penetration of resin dental materials into enamel surfaces with reference to bonding. Arch Oral Biol 1968;13:61-70. 5. Welsh EL, Hembree JH Jr. Microleakage at the gingival wall with four Class V anterior restorative materials. J PR~STHET DENT 1985;54: 370-3. 6. Gwinnett 7.
8. 9.
10. 11.
AJ. The ultrastructure of “prismless” enamel of permanent human teeth. Arch Oral Biol 1967;12:381-8. McLean JW, Wilson AD. The clinical development of the glass-ionomer cements. I. Formulations and properties; II. Some clinical applications; III. The erosion lesion. Aust Dent J 1977;22:31-6;120-7;190-5. Hotz P, McLean JW, Seed I, Wilson AD. The bonding of glass ionomer cements to metal and tooth substrates. Br Dent J 1977;142:41-7. Jenkins CBG. A comparison of bond strength of glass ionomer cements and acid etch resin systems [Abstract]. J Dent Res 1976;55:D134. Murray GA, Yates JL. A comparison of the bond strengths of composite resins and glass ionomer cements J Pedod 1984;8:172-7. Powis DR, Folleras T, Merson SA, Wilson AD. Improved adhesion of a glass ionomer cement to dentin and enamel. J Dent Res 1982;61:1416-
22. 12. Hembree
restorative
JH Jr, Andrews JT. Microleakage of several Class V anterior materials: a laboratory study. J Am Dent Assoc 1978;97:179-
83. 13. Kidd
EAM. Cavity sealing ability of composite and glass ionomer cement restorations. Br Dent J 1978;144:139-42. A, Swarm M, Phillips RW. An in vitro study of certain 14. Maldonada properties of a glass ionomer cement. J Am Dent Assoc 1978;96:785-91. GJ. Longevity of glass ionomer cements. J PROSTHET DENT 15. Mount 1986;55:682-5. 16. Tobias RS, Browne
RM, Plant CG, Ingram DV. Pulpal response to a glass ionomer cement. Br Dent J 1978;144:345-50. 17. McLean JW. Alternatives to amalgam alloys: 1. Br Dent J 1984;157: 432-3.
18. Council on Dental Materials and Devices: Status report on the glass ionomer cements. J Am Dent Assoc 1979;99:221. 19. McLean JW, Powis DR, Prosser HJ, Wilson AD. The use of glass-ionomer cements in bonding composite resins to dentin. Br Dent J 1985;158:410-4. 20. Wong TC, Bryant RW. Glass ionomer cements: dispensing and strength. Aust Dent J 1985;3@336-40.
MAY
1090
VOLUME
63
NUMBER
6
CLASS
V COMPOSITE
RESIN
RESTORATIONS
21. Bassiouny MA, Sabri R, Carrel R. Microfilled composites: in vitro marginal seal. J Pedod 1983;7:308-17. 22. Gordon M, Plasschaert AJM, Soelberg KB, Bogdan MS. Microleakage of four composite resins over a glass ionomer cement base in class V restorations. Quintessence Int 1985;16:817-20. 23. Crim GA, Shay JS. Microleakage pattern of a resin-veneered glass-ionomer cavity liner. J PROSTHET DENT 1987;58:273-6.
Correlation of composite
between air-drying resins to teeth
Kazuyoshi Ichiki, D.D.S.,* Tadao Yutaka Yoshida, D.D.S., Ph.D.,*** Fukuoka
Dental
College,
Fukuoka,
Reprint requests to: DR. J. L. FERRACANE SCHOOL OF DENTISTRY OREGON HEALTH SCIENCES 611 S. W. CAMPUS DRIVE PORTLAND, OR 97201
duration
UNIVERSITY
and bond strength
Fukushima, M.S., Ph.D.,** and Takashi Horibe, Ph.D.****
Japan
Cavity preparations involve both enamel and dentinal walls, but moisture contamination of these surfaces adversely influences the effectiveness of bonding interface. This in vitro study investigated the relationship between air-drying time and the bond strength to bovine enamel and dentin for two types of composite rssifis and their bonding agents. Comprehensive shear bond tests were performed with a universal testing machine, and mean bond strengths were computed by an analysis of variance and by ScheffB’s multiple comparison test. No statistical differences were noted between the bond strength to the unetched and etched enamel and air-dryiqg duration for bondings. The bond strengths to the etched dentin was comparable despite the time of air drying, but the bond strengths to unetched dentin were dependent upon the length of air drying. (J PROSTHET DENT 1990;63:525-9.)
N
umerous physical factors affect the tooth-composite resinbond strength intraorally.‘-3 Moisture contamination of the bonding surface adversely influencesthe effectivenessof the bonding interface. A moisture-free tooth surface is strongly recommendedto ensure an effective bond between the compositeresin and the tooth surface. Young et a1.2and Fuse4 studied the effects of various drying times on the tensile bond strength to etched enamel for Nuva-Seal (L.D. Caulk Co., Milford, Del.) and Concise (3M Dental Products, St. Paul, Minn.) resins.Both reports recommendedthat prolonged drying of etched enamelwas innecessary for maximal bond strength. However, there is a dearth of information on the relationship between air-drying durations and bond strengths of composite resin to dentin. Only a few manufacturers’ instructions have indicated the desired air-drying time for compositeresin bonding to the tooth surface.
*Research Associate, Department of Pedodontics. **Assistant Professor, Department of Dental Materials and Devices. ***Professor and Chairman, Department of Pedodontics. ****Professor and Chairman,Departmentof Dental Materials
andDevices. 10/1117134
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Table
I. Materials* used in study
Code NB PB *All materials
Bonding agent Clearfil Clearfil
Composite resin
New Bond Photo Bond
used were manufactured
Clearfil SC-II Photo Clearfil by Kuraray
A
Co., Osaka, Japan.
This investigation examined the relationship between air-drying time and the bond strength to enameland dentin for two compositeresinsand their bonding agents.
MATERIAL
AND
METHODS
Table I lists the bonding agents and composite resins usedin this &udy. Freshly extracted bovine teeth substituted for human teeth5 were used as adherents.
Preparation
of tooth
surface
The teeth were embeddedwith acrylic resin in acrylic tubes (20 mmO)(Fig. 1). The surfaceswere finally polished with 6OO-gritsilicone carbide (Sic) paper under running water to obtain the unetched enamel and dentin. Etched enameland dentinal sampleswere treated with 407%phosphoricacid for 1 minute and washedwith water for 10 secondsafter polishing and etching. Subsequently,
525
in class V composite liners in vitro J. P. DeWald,
D.D.S.,*
resin
C. R. Moody,
D.D.S.,*
restorations and
Baylor College of Dentistry, Dallas, Tex., and Oregon Health Sciences University, School of Dentistry, Portland, Ore. This in vitro study evaluated the use of a glass ionomer lining cement in conjunction with composite resin in class V preparations in terms of marginal sealing ability. Two preparations, the occlusal walls in enamel (etched) and the gingival walls in dentin, were place in each tooth. One contained the etched glass ionomer liner, a dentin bonding agent, and a microill composite resin. The second contained the dentin bonding agent and the microfill composite resin. The teeth were thermocycled, stained with methylene blue dye, sectioned, and evaluated for leakage at the occlusal and gingival margins on a scale of 0 to 3. No significant leakage was recorded at the occlusal margin for either restoration. Leakage at the gingival margin was significantly reduced for the lined restorations, and in no instance did the dye penetrate beyond the liner, which suggests that the lining cement may significantly decrease leakage at the gingival aspect of composite resins in class V restorations.(J PROSTRETDENT~QQ~;~~:S~~-~.)
M
arginal leakage around compositeresin restorations, particularly at the gingival aspect, is a major problem in clinical dentistry.l Reducing marginal leakagewill decreasesecondarycaries,pulpal sensitivity, pulpal injury, and discoloration, thereby increasingthe clinical successof the restoration.2p3 Compositeresinsare widely usedin clinical applications, especially where esthetics are a primary concern, for example, in classV restorations. Although there is little leakage at the occlusal aspect of class V restorations becauseof the strength of the etched enamel/composite bond,4*5the bond at the gingival aspect is insufficient becauseof the lack of enamel for adherenceor inadequate prism structure in the available enamel for acceptabletag formations Therefore, to improve the clinical successof compositeresinsin classV restorations, marginal leakage at the gingival aspectmust be minimized. Glassionomer cementsoffer improved marginal sealing ability by chemical adhesionto enameland dentin.7-gAlthough the bond of glassionomer cement to enamel is weaker than the bond of compositeresinsto enamel,1°the bond of glassionomer to dentin is greater than that of compositeresinto dentin and can be further enhancedwith the use of a 25% polyacrylic acid pretreatment.l’ Glass-
Supported by funds from the 3M Foundation, St. Paul, Minnesota and G-C Dental Industrial Corporation, Tokyo, Japan. Presented at the IADR/AADR/CADR, Montreal, Canada. *Assistant Professor, Department of Operative Dentistry, Baylor College of Dentistry. **Associate Professor, Department of Dental Materials, Oregon Health Sciences University, School of Dentistry. 10/l/17711
522
ionomer cement has a coefficient of thermal expansion similar to natural tooth, structure and has been shown to elicit no marginal leakage.5p12-15 However, other properties such as high solubility, low strength, poor esthetics, and surface roughnesslimit its use as a restorative material.16-lsThe bond of etched glassionomer cement to composite resin is stronger than the cement itself.“* lg Therefore, it is logical to expect that glass ionomer cement would serve asan excellent dentinal bonding agent under a composite resin. In addition, becauseglassionomer cementhas a coefficient of thermal expansionsimilar to tooth structure and, unlike compositeresin, doesnot have the potential to “debond” from polymerization shrinkage,oneexpects better adaptation to the cavity wall. Its use alsoreducesthe amount of compositeresin needed, thus further reducing the effects of polymerization shrinkage. This study evaluated the useof glassionomer lining cement under composite resin in classV cavities in terms of in vitro marginal sealingability.
MATERIAL
AND
METHODS
Freshly extracted sound human molars were selected and stored in 70% ethano1.lPrior to tooth preparation the 12teeth were stripped of attached gingiva with a knife and cleaned with flour of pumice using a rubber cup at slow speed.Twenty-four class V preparations were prepared with a rectangular outline form, one on the buccal and one on the lingual surface of each tooth (Fig. 1). The preparations were standardized
in size and extended
4 mm mesio-
distally with a width of 2 mm. The preparations extended into dentin to a total depth of 2 mm. The occlusalcavosurface endedin enameland the gingival cavosurfaceended in dentin.
The cavities were prepared
with a No. 56 tungsten
carbide bur at ultrahigh speedusing air and water spray MAY
1990
VOLUME
68
NUMBEB
5
CLASS
V COMPOSITE
RESIN
RESTORATIONS
Etch Bonding Composite
Agent
Dentin Conditioner Glass lonomer Etch Bonding Agent Composite
Fig. 1. Schematic of cavity preparation and restorations
GINGIVAL MARGIN
OCCLUSALMARGIN 101 9..
-
0 -
LINED UNLINED
- 10 -. Q -. 6 -7 --8
* i2
6 -L 7-w 6-m
Fz
5--
-- 5
E
4--
-- 4
E
3-b
-3
2-1 -. I
O0
1
2
used in study.
r 10
10
-
9--
U -
6 --
LINED UNLINED
-9
--6
*
7--
--7
g
6--
-- 6
5 --
-. 5
4 --
-4
3--
-3
-- 2
2 --
-2
-. 1
1 --
.- 1
-0
o-
3
iG :
-0 0
1
2
3
Fig. 2. Histogram compares leakage scores at occlusal margin for lined and unlined restorations.
Fig. 3. Histogram compares leakage scores at gingival margin for lined and unlined restorations.
coolant. Cavosurface angles were 90 degrees. Prior to restoring, the teeth were rinsed and stored for 1 hour in distilled water. Lining cement was alternately placed in the buccal or lingual preparation for each tooth to avoid bias of data. The remaining preparation of each tooth received no lining cement. The preparations of the lined teeth were rinsed with water and air dried. One drop of dentin conditioner (25 % polyacrylic acid, G-C Dental Industrial Corporation, Tokyo, Japan) was placed on a cotton pellet in a Dappen dish, and the pellet was used to scrub the dentinal surface for 20 seconds. The tooth was rinsed for 10 seconds and dried. The glass ionomer lining cement was weighed at the recommended powder-to-liquid ratio of 1.2 g powder to 1 g liquid (G-C) on an electronic balance to 2 0.001 g.20 The powder was divided into two parts, and each was mixed into the liquid for 15 seconds for a total of 30 seconds. The liner was applied in a thin layer on all internal dentinal surfaces with a calcium hydroxide applicator, and as close to the gingival cavosurface angle as possible to allow room for the composite resin to cover it (Fig. 1). After the initial set of the liner (approximately 4 to 5 minutes) the remaining enamel was acid etched with 35 %
phosphoric acid in a gel base for 40 seconds. After 40 seconds, additional etchant was applied to the liner so that the enamel was etched for 60 seconds and the liner for 20 seconds. The preparation was rinsed for 30 seconds and dried. One drop of resin and one drop of catalyst (Silux LightCured Bonding Agent, Scotchbond, 3M, St. Paul, Minn.) was mixed and applied to the internal surfaces of the cavity with a brush. A gentle stream of air was used to evenly disperse the liquid. The bonding agent was cured for 10 seconds with a Command (Kerr, Romulus, Mich.) light source. Silux composite resin was placed with a plastic instrument and cured 20 seconds with the light-curing unit. The restorations were subsequently finished using all four grades of Sof-flex disks (3M). The restorations that did not receive the liner were treated in the same manner, except without dentin conditioning and liner, and only the enamel was etched. The bonding agent was applied to all internal surfaces of the preparation prior to placing the composite resin. The teeth were then placed in distilled water at 37” C for 48 hours to achieve final cure. The teeth were thermocycled between distilled water baths at 5’ and 55’ C. Each cycle lasted 1 minute for a to-
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
523
MATHIS
tal of 1700 cycles. The root portions and crowns, within 1 mm of the restoration margins, were sealedprior to staining by placing two coatsof acrylic resinvarnish.21The teeth werethen inverted in a thick mix of dental stone in a polyethylene beaker and the stonewasallowedto harden. Subsequently, 0.5% methylene blue dye was poured into the beaker until it covered the restorations by about 2 mm. This procedure prevented dye from penetrating root apices.The beaker wassubsequentlyplaced in the 5’ C bath for 17 hours to causea contraction of the materials which enhancedthe penetration of the dye. The teeth were rinsed with distilled water, air dried, and sectionedlongitudinally in a buccolingual direction on a low-speeddiamond saw. The sectioned sampleswere observed using surface reflection microscopy by two investigators. Leakage around the restorations was rated using the scale of Myers as in Gordon et al.22according to maximum penetration of the dye: 0 = none at the interface of the tooth and restorative material 1 = at the cavosurfaceangle 2 = along the gingival or occlusal walls, but not to the pulpal wall 3 = to the pulpal wall The results were analyzed by using Wilcoxon’s signed ranks test at the p I 0.01 level of significance.
RESULTS Occlusal scoresfor both treatments are shown in Fig. 2 and the gingival scoresappear in Fig. 3. The gingival walls of the unlined restorations showedsignificantly more dye penetration than did both the occlusalwalls of the unlined restorationsand the occlusaland gingival wallsof the lined restorations.
DISCUSSION The occlusalaspect of both lined and unlined restorations revealed only slight leakageat the cavosurfacein only five of the 24restorations. However, onerestoration showed grossleakage.Had the enamelbeen beveledocclusally, the degreeof leakagewould be expected to be even less.At the gingival aspect,however, 10 of the 12 unlined restorations showedgrossleakage.Three of the lined restorations had no leakage,and nine had minimal leakageconfined to the cavosurfacemargin, in all casesnot penetrating beyond the liner. The minimal leakagecan be explained becauseof the difficulty in applying the liner completely to the cavosurface angle,thus allowing the compositeresin to contact the dentin at the point at which leakageoccurred. As evidenced by the unlined restorations, this gingival bond is inadequate. Other studies support these results in that greater leakagehas been observed gingivally versus occlusally1s5 and no leakage occurred below the Silux resin and GI cementz2
524
ET AL
In this study, the reduction in microleakageappearsto be a direct result of the liner, not the bonding agent.23The liner, by chemically adhering to the dentin and providing an adequatesurface for retention of compositeresin, minimizesleakagein two ways: (1) the liner provides a sealing of the dentin below the compositeresin; and (2) the effects of polymerization shrinkage and thermal expansionof the compositeare reduced becausethere is lesscompositeresin in the preparation.
CONCLUSION The resultsof this in vitro study indicate that the useof glass-ionomerlining cementsbelow classV compositeresin restorations may significantly decreasemarginal leakageat the gingival aspect.
REFERENCES 1. Retief DH, Woods E, Jamison HC. Effect of cavosurface marginal leakage in Class V composite resin restorations. DENT
treatment on J PR~STHET
1982;47:496-501.
Hembree JH. Marginal leakage of microfilled composite resin restorations. J PROSTH~ DENT 1983;50:632-5. Christen AG, Mitchell DF. A fluorescent dye method for demonstrating leakage around dental restorations. J Dent Res 1966;45:1485-92. Buonocore MG, Matsui A, Gwinnett AJ. Penetration of resin dental materials into enamel surfaces with reference to bonding. Arch Oral Biol 1968;13:61-70. 5. Welsh EL, Hembree JH Jr. Microleakage at the gingival wall with four Class V anterior restorative materials. J PR~STHET DENT 1985;54: 370-3. 6. Gwinnett 7.
8. 9.
10. 11.
AJ. The ultrastructure of “prismless” enamel of permanent human teeth. Arch Oral Biol 1967;12:381-8. McLean JW, Wilson AD. The clinical development of the glass-ionomer cements. I. Formulations and properties; II. Some clinical applications; III. The erosion lesion. Aust Dent J 1977;22:31-6;120-7;190-5. Hotz P, McLean JW, Seed I, Wilson AD. The bonding of glass ionomer cements to metal and tooth substrates. Br Dent J 1977;142:41-7. Jenkins CBG. A comparison of bond strength of glass ionomer cements and acid etch resin systems [Abstract]. J Dent Res 1976;55:D134. Murray GA, Yates JL. A comparison of the bond strengths of composite resins and glass ionomer cements J Pedod 1984;8:172-7. Powis DR, Folleras T, Merson SA, Wilson AD. Improved adhesion of a glass ionomer cement to dentin and enamel. J Dent Res 1982;61:1416-
22. 12. Hembree
restorative
JH Jr, Andrews JT. Microleakage of several Class V anterior materials: a laboratory study. J Am Dent Assoc 1978;97:179-
83. 13. Kidd
EAM. Cavity sealing ability of composite and glass ionomer cement restorations. Br Dent J 1978;144:139-42. A, Swarm M, Phillips RW. An in vitro study of certain 14. Maldonada properties of a glass ionomer cement. J Am Dent Assoc 1978;96:785-91. GJ. Longevity of glass ionomer cements. J PROSTHET DENT 15. Mount 1986;55:682-5. 16. Tobias RS, Browne
RM, Plant CG, Ingram DV. Pulpal response to a glass ionomer cement. Br Dent J 1978;144:345-50. 17. McLean JW. Alternatives to amalgam alloys: 1. Br Dent J 1984;157: 432-3.
18. Council on Dental Materials and Devices: Status report on the glass ionomer cements. J Am Dent Assoc 1979;99:221. 19. McLean JW, Powis DR, Prosser HJ, Wilson AD. The use of glass-ionomer cements in bonding composite resins to dentin. Br Dent J 1985;158:410-4. 20. Wong TC, Bryant RW. Glass ionomer cements: dispensing and strength. Aust Dent J 1985;3@336-40.
MAY
1090
VOLUME
63
NUMBER
6
CLASS
V COMPOSITE
RESIN
RESTORATIONS
21. Bassiouny MA, Sabri R, Carrel R. Microfilled composites: in vitro marginal seal. J Pedod 1983;7:308-17. 22. Gordon M, Plasschaert AJM, Soelberg KB, Bogdan MS. Microleakage of four composite resins over a glass ionomer cement base in class V restorations. Quintessence Int 1985;16:817-20. 23. Crim GA, Shay JS. Microleakage pattern of a resin-veneered glass-ionomer cavity liner. J PROSTHET DENT 1987;58:273-6.
Correlation of composite
between air-drying resins to teeth
Kazuyoshi Ichiki, D.D.S.,* Tadao Yutaka Yoshida, D.D.S., Ph.D.,*** Fukuoka
Dental
College,
Fukuoka,
Reprint requests to: DR. J. L. FERRACANE SCHOOL OF DENTISTRY OREGON HEALTH SCIENCES 611 S. W. CAMPUS DRIVE PORTLAND, OR 97201
duration
UNIVERSITY
and bond strength
Fukushima, M.S., Ph.D.,** and Takashi Horibe, Ph.D.****
Japan
Cavity preparations involve both enamel and dentinal walls, but moisture contamination of these surfaces adversely influences the effectiveness of bonding interface. This in vitro study investigated the relationship between air-drying time and the bond strength to bovine enamel and dentin for two types of composite rssifis and their bonding agents. Comprehensive shear bond tests were performed with a universal testing machine, and mean bond strengths were computed by an analysis of variance and by ScheffB’s multiple comparison test. No statistical differences were noted between the bond strength to the unetched and etched enamel and air-dryiqg duration for bondings. The bond strengths to the etched dentin was comparable despite the time of air drying, but the bond strengths to unetched dentin were dependent upon the length of air drying. (J PROSTHET DENT 1990;63:525-9.)
N
umerous physical factors affect the tooth-composite resinbond strength intraorally.‘-3 Moisture contamination of the bonding surface adversely influencesthe effectivenessof the bonding interface. A moisture-free tooth surface is strongly recommendedto ensure an effective bond between the compositeresin and the tooth surface. Young et a1.2and Fuse4 studied the effects of various drying times on the tensile bond strength to etched enamel for Nuva-Seal (L.D. Caulk Co., Milford, Del.) and Concise (3M Dental Products, St. Paul, Minn.) resins.Both reports recommendedthat prolonged drying of etched enamelwas innecessary for maximal bond strength. However, there is a dearth of information on the relationship between air-drying durations and bond strengths of composite resin to dentin. Only a few manufacturers’ instructions have indicated the desired air-drying time for compositeresin bonding to the tooth surface.
*Research Associate, Department of Pedodontics. **Assistant Professor, Department of Dental Materials and Devices. ***Professor and Chairman, Department of Pedodontics. ****Professor and Chairman,Departmentof Dental Materials
andDevices. 10/1117134
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Table
I. Materials* used in study
Code NB PB *All materials
Bonding agent Clearfil Clearfil
Composite resin
New Bond Photo Bond
used were manufactured
Clearfil SC-II Photo Clearfil by Kuraray
A
Co., Osaka, Japan.
This investigation examined the relationship between air-drying time and the bond strength to enameland dentin for two compositeresinsand their bonding agents.
MATERIAL
AND
METHODS
Table I lists the bonding agents and composite resins usedin this &udy. Freshly extracted bovine teeth substituted for human teeth5 were used as adherents.
Preparation
of tooth
surface
The teeth were embeddedwith acrylic resin in acrylic tubes (20 mmO)(Fig. 1). The surfaceswere finally polished with 6OO-gritsilicone carbide (Sic) paper under running water to obtain the unetched enamel and dentin. Etched enameland dentinal sampleswere treated with 407%phosphoricacid for 1 minute and washedwith water for 10 secondsafter polishing and etching. Subsequently,
525