Evaluation of materials and techniques for restoration of erosion areas

ECKER

POSITION 2

POSITION 1

Fig. 1. Placement of tip of fiberoptic instrument. within the canal can be seen, especially when magnifying lenses are used. Secondary dentin also appears darker. During post space preparation, transillumination produces a “bulls-eye” effect, which changes in its appearance depending on the location of the light source. If the light source is below the level of the gutta-percha or filling material, the canal filling material appears dark or shadowed against the surrounding orangeyellow dentin (Fig. 1). As the light source is moved occlusally, the guttapercha assumes a dark orange hue. With the continued instrumentation of the canal, it is possible to follow the alignment of the preparation and to determine a potential perforation before it occurs. Fiberoptic illumination is also used to disclose vertical root fractures in endodontically treated teeth. One method is to air dry the root canal thoroughly and then transilluminate at positions 1 and 2 in Fig. 1. The

dentin-air interface creates a zone of refraction, highlighting the fracture line. A mod&z&on includes use of a disclosing agent (iodine solution) on the suspected fracture site.4 This helps delineate the fracture line more readily from the surrounding tooth structure. Surrounding lights should be dimmed temporarily to improve the contrast. Fiberoptic illumination has also proved helpful in revealing tags of impression material and particles of dental cement that remain within the gingival crevice. These materials are defined by transillumination as darkened areas. A fiberoptic endoscope was also developed to provide direct visualization of instrumented root canals for research purposes and endodontic treatment.4,’ It is hoped that these suggestions may be useful to dentists who treat teeth that need radicular restorations. REFERENCES Friedman JM: Trans-illumination of the oral cavity with the use of fiber optics. J Am Dent Assoc 80~801, 1971. Friedman JM: The use of fiber optics as a diagnostic aid. Dent Survey 48:38, 1972. lxtrn JM: Fiber optic light sources and handpiwes. Quintessenct Ink 9:923, 1983. Drwh SG, Cunningham WT, Longlors %JILl.Endoswpy as an aid to endodontic diagnosis. J Endodont 5:60, 1979. Marshall GW Jr, Lipsey MR, Ffeuer MA, Koi C:, Smart R, Epskein M: An endodontic Iiber optic endoscope for viewing inwumented root canals. J Endodont 7:85-88, 1981. lzL~/m,/

W,Ud\.’

DR. CARRY ECKER UNIVERSITY OF CONNECTICUT SCHOLL OF DENTAL MEDICINE FARMINGTON, CT 06032

Indiana University, School of Dentistry, Indianapolis, Ind.

Taken in part from theses of the first two.authors in partial fulIillment of the requirements for the M.S.D. degree, Indiana University School of Dentistry. *Graduate Student. 434

*“Professor of Dental Materials. ***Associate Dean for Research, Research- Professor of Dental Materials and Chairman of Department of Dental Materials. ‘**‘Laboratory Technician. APRIL 1986

VOLUME 55

NUMBER 4

RESTORATION

OF EROSION

AREAS

Whereas preventive dentistry has reduced the loss of teeth from caries, longer tooth life has increased the occurrence of noncarious cervical erosions. These lesions are unsightly and often sensitive to toothbrushing or thermal shock. The traditional method for restoring an erosion area is to prepare a Class V cavity preparation and insert an amalgam, foil, resin, or fused porcelain restoration. Unfortunately this technique requires extensive removal of sound tooth structure for retention of the nonadhesive restorative material. Two conservative methods have emerged whereby the area is restored without the need for a cavity preparation or anesthesia. One is to make use of a glass ionomer cement.lm3Because the cement will bond chemically to enamel and dentin, this adhesion provides the mechanism for retention without mechanical means. The other method makes use of mechanical bonding. In this procedure the enamel is acid etched and a composite resin is used as the restorative material, generally without the use of mechanical retention. Provided the margins are all in enamel, the technique is successful!*’ Unfortunately, in the typical eroded lesion, the gingival portion of the restored area is located in cementum and/or dentin. Because nonadhesive bond agents and resins have been used, the cervical margin is a potential site for microleakage, leading to the possibility of stain, postoperative sensitivity, or caries.6 This may occur even if the restorative material is still retained by the mechanical bonding to the acid-etched enamel. Several manufacturers have marketed so-called dentin bonding agents said to bond to dentin and the resin supplied with the agent, thus providing a seal at the gingival wall. Acid etching of the enamel is usually recommended in conjunction with the dentin bonding agent. Data to make a determination as to the efficacy of these materials or to compare the concept with that of the glass ionomer system are lacking. Whether mechanical retention in the dentin is desirable, even with use of these adhesives, remains controversial. The purpose of this in vitro study was to examine the ability of two commercial resin-dentin bonding agent systems to seal simulated erosion lesions prepared in extracted teeth. The resin restorations were then compared with similar restorations placed without a bonding agent and to glass ionomer cement restorations. In addition, the effect of conservative preparation of the cavity on the marginal seal was compared with the seal of restorations inserted in cavities that were not prepared. Resin-dentin and resin-enamel bond strength was also measured after applying the bonding agents.

METHODS AND MATERIAL Leakage tests Simulated Class V erosions were prepared in 180 extracted canine and premolar teeth that had been stored THE JOURNAL

OF PROSTHETIC

DENTISTRY

Fig. 1. Cross sections through simulated V-shaped erosions prepared in extracted teeth.

in water after extraction. The teeth were removed from water only long enough to carry out the operative procedures. V-shaped cavities of similar dimension were prepared so that the incisal or occlusal margins were located in enamel and in the gingival margins in cementum and/or dentin (Fig. 1). The teeth were randomly divided into two groups (A and B) of 90 teeth each. Before restoration, the simulated lesions in the first group of 90 teeth (cavity A) were brushed in a mechanical toothbrushing machine for 15 minutes in a 1:1 slurry of a nonfluoride dentifrice (Pepsodent, Lever Bras., New York, N.Y.). This surface finish more closely resembled that of an erosion than did the freshly cut tooth surface. The surface of a natural lesion is comparable to that of the simulated lesion (Fig. 2). In this series there was no preparation of the cavity prior to restoration. The V-shaped form of the cavities in the remaining 90 teeth (cavity B) was modified by conservative preparation as suggested for the restoration of this type of lesion.7,8 The modification consisted of a slight bevel on the incisal or occlusal enamel margin by means of a tapered diamond rotary instrument operated at high speed with an air coolant. A No. l/2 round bur operated at high speed with air-water spray was used to prepare a groove for retention in the dentin of the gingival wall just pulpal to the cavosurface angle (Fig. 3). The two resins and the glass ionomer cement are listed in Table I. Teeth treated with each of the two resin systems were restored with the following combinations of materials in the following groups of 10 teeth each: (a) resin only, (b) resin plus enamel etch, (c) resin plus dentin bond agent, and (d) resin plus enamel etch plus dentin bonding agent. 435

MONTE.IRO

ET AL

Fig. 2. A, Photomicrograph of the surface of a natural erosion lesion. B, Simulated erosion lesion after 15-minute brushing with a toothbrush and dentifrice.

Table I. Materials

tested Etching agent

Material Silux resin Clearfil FII resin Ketac-Fil glass ionomer

Yes Yes

Dentin bond agent Scotchbond brand Bonding agent

cement

An additional 10 teeth were restored with glass ionomer cement (Ketac-Fil, Premier, Philadelphia, Pa.). Each of the two resin materials was manipulated in strict accordance with the directions of its manufacturer. Both resins were placed with a matrix strip. The light-cured resin (Silux, 3M Dental Products, St. Paul, Minn.) was polymerized by 60 seconds exposure to the light. Both resin restorations were finished with Soflex disks (3M Co.) 15 minutes after insertion. The restored teeth were then immersed in water and stored at 37” C. Before restoration with the glass ionomer cement (Ketac-Fil), the surface of the erosion lesion was treated with a 25% solution of polyacrylic acid for 10 seconds, rinsed with water, and dried. The cement mix was then inserted into the cavity, contoured with a matrix strip, and held under pressure for 3 minutes. Twelve minutes later the matrix was removed; the restoration was coated with varnish and finished by the same procedures as were the resin restorations. The teeth were then immersed in water at 37” C. All restored teeth were stored in water at 37” C for 2 weeks, during which time period they were subjected to 2500 thermocycles, at 15” and 55” C. At the end of the storage period the seal of the cavity was assessedby means of the isotope technique.9 The teeth were sealed with a combination of nail enamel and 436

Manufacturer 3M, St. Paul, Minn. Kuraray Co., Osaka, Japan Premier, Philadelphia, Pa.

033b83 22081 634756

tin foil so that only the area of restoration and a 1 mm wide band of surrounding tooth surface were exposed. They were immersed for 2 hours in a calcium chloride solution (Ca”C1) having a concentration.of 0.1 mCi/ml, Upon removal from the isotope the teeth were rinsed in water, the foil was removed, and the surfaces were brushed with a detergent and water. The teeth were then sectioned longitudinally through the restorations. The pulps were removed and the sectioned surfaces WIFE cleaned by brushing with a detergent. The to§icms were dried and placed on dental x-ray fiim for pro&ctian of the autoradiographs. In the curse of preliminary studies a substantial number of restorations were lost from cavity A during sectioning. To alleviate this problem, after immersion of the teeth in the isotope and scrubbing but before sectioning, a layer of an unfil$ed resin was flowed over the surface of the .reatoratioJls and onto the surrounding tooth surface to stabilii the restoration. Autoradiographs depicting three distinct degrees of leakage were chosen from the 90 autoradi~~ap~ of restorations in the cavity A group to serve as S&X&& for ranking the degree of leakage depicted in the autoradiographs (Fig. 4). In group B, where there was an incrF@se&area of cavity due to the enamel bevel and the groove, four degrees of leakage were autoradiographs of the restorations. Four fitms were APRIL

1986

VOLUME

55

NUMBER

4

RESTORATION

OF EROSION

AREAS

Fig. 4. Standard series of autoradiographs used for grading leakage of restorations in cavity A. Dark line along restoration-tooth interface is result of isotope penetration.

Cavity B: Silux resin + acid etch + resin bond agent (Concise Enamel Bond, 3M Co.)

Bond strength tests

Fig. 3. Cross section of prepared lesion. Note bevel of enamel margin and retentive groove just inside gingival cavosurface margin.

selected as standards for grading leakage of restorations in this cavity (Fig. 5). Autoradiographs of teeth in both cavity series were assigned random code numbers to permit a blind evaluation. Three evaluators independently scored the coded autoradiographs three times and assigned leakage values. At least 24 hours elapsed between subsequent evaluations by any evaluator. The code was not broken until all evaluations were completed. Pearson’s R was used to determine intraevaluator and interevaluator agreement. Because there was no significant difference between the interevaluator or intraevaluator scores, all evaluations were combined. Ridit analysis was then performed to determine the population ridit values. The ridit means and standard deviations were calculated. The data then were analyzed by means of analysis of variance, with the Welch test used for multiple comparison of materials. After completion of the 2-week tests, longer term tests were conducted by storing three experimental series in water for 6 months at 37” C. During the last 2 weeks they were subjected to 2500 thermocycles at the 40” C temperature differential. The three test groups were: Cavity A: Silux resin + acid etch + dentin bond agent Cavity B: Silux resin + acid etch + dentin bond agent THE JOURNAL

OF PROSTHETIC

DENTISTRY

The bond strengths of the two resins to etched enamel and dentin were determined when the respective dentin bond agents were used, and they were compared to the bond strength of the glass ionomer cement. Bovine incisors were used for the adhesion test procedure.‘O The tooth roots were removed and flat areas of enamel or dentin approximately 1 cm in diameter were produced by wet grinding on the facial surfaces. The teeth were then mounted in cold cure acrylic cylinders to expose the flat areas. Just before preparation of the specimens, the ground tooth surface was finished by hand grinding it on wet No. 400 grit silicon carbide paper. Specimens were rinsed with a stream of water, dried with compressed air, and given the appropriate pretreatment. A split silicone ring with an inside diameter of 7 mm was placed on the tooth to form the cavity to receive the restorative material. Once the cavity was filled, a plastic ball containing a hole filled with the same resin was placed on top of the silicone ring so that the two portions of resin bonded to each other. The ball served to attach the specimens to the grips of the testing machine. Materials were manipulated in the same manner as were restorations of the cavities. The specimen with light-cured resin was built up in 2 mm increments, with each increment cured for 60 seconds. Five minutes after completion, the specimens were placed in a humidor at 37” C. Fifty-five minutes later the silicone ring matrix was removed and the specimens were stored in water at 37” C for 2 weeks. Twenty specimens of each material were prepared and during the storage period 10 specimens of each material were subjected to 2500 thermocycles in the same manner as were the restored teeth. The specimens were then loaded to failure in tension at a crosshead speed of 0.77 mm/min. 437

MONTEIRO ET Al.

Fig. 5. Standard set of autoradiographs used for grading leakage of restorations in cavity B. Dark line at restoration-tooth interface is result of isotope penetration.

Table II. Test group A (no instrumentation

of cavity)

~-__.---

No. of specimens/ leakage category Material

2

3

No.

1 1

0 3

b d

2

10 10 IO

6

4 3

9 4 4

1

10

a b

0 0

1

8

Y

2

8

10

0.6690 0.6311

:

0

83

72

10 IO

: 0.5884 0.3750

6

3

1

10

0.2024

a f

Clearfil

Ketac-Fil

FII resin

glass ionomer

cement

Values connected by vertical lines are not significantly different

Ridit

a

b

C

d

Material CIearfil FII resin Silux r&sin Ketac-Fil glass ionomer cement Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement

Values connected by vertical (p < .05).

Mean

SD

0.6690 0.6521 0.2024

0.1423 0.2034 0.2074

0.6311

0.1800

0.4171 0.2024

0.2708 0.2074

0.5884 0.4387 0.2024

0.2062 0.2480 0.2074

0.3750 0.2024 0.2024

0.1800 0.2074 0.2074

lines are not significantly

different

MEGJLTS Cavity A micrsksa;rkrge Results of the leakage tests conducted on 2-week-old restorations in the unmodified erosion lesion, cavity A, are shown in Table II. With both resin systems the 438

I,..

yean

SD

.v

!I O&T1

"

0.4387 0.4171 0.2024

O.i& 0.2480 0.2480 0.2074 0.1423

0.1800 0.2062 0.1800 0.2074

-..----

& < -03).

Table III. Group A leakage comparisons

Subgroup

Ridit

__-

1

SUbgrOUp

Silux resin

Total

greatest amount of leakage occurred in group a, where neither enamel etching nor the bonding agent were used. The least amount of leakage was found :in gFWp d, where the enamel was et&& and the respective dentin bonding agents were applied to the cavity surfaces. The difference in the mean leakage values for groups a and d was significant (p < .OS) for both resins. The use of acid etching alone, group b, and the bonding agent alone, group c, produced intermediate degrees of leakage. However, with neither resin were groups b or c signnificantly different from group a. Table III presents a summary of the results of the statistical analysis. There was no statistical difference in the leakage values of the resin restczations with the two materials within a particular group. There,was sign&cantly less leakage of glass ionomer fxments than r&ns in groups a, b, and c. How-, t~~se~~~.~~~t~ of the resins in group d was not statistically d%&mt (p < .a$ from the glass ionomer cemeat restorations.

Cavity B micrdedage The leakage data for restorations pla@l in c&Q 3 and stored for 2 weeks are shown in Table IV. A+@, vaka mzxd w&h r6s~~atkm~ in the h@kst group a where the tooth was restored with the resins without acid etching of enamel or application of a dentin bonding agent. As in cavity A, the lowest values were APRIL

1986

VOLUME

55

NUM8L$C

4.

RESTORATION

OF EROSION

AREAS

Table IV. Test group B (conservative preparation of cavity) No. of specimens/leakage category Subgroup

Material

1

2

3

4

Total No.

Ridit

values

Mean

SD

Silux resin

a b c d

2 6 6 10

3 4 4 0

1 0 0 0

4 0 0 0

10 10 10 10

0.5569 0.2671 0.2671 0.1557

0.2750 0.1438 0.1438 0.0000

Clearfil

a

0 2 4 9

3 7 3 1

1 0 3 0

5 1 0 0

9 10 10 10

0.6770 0.4186 0.3766 0.1835

0.1957 0.1867 0.2038 0.0881

7

2

0

0

9

0.2176

0.1228

FII resin

C

b d Ketac-Fil

glass ionomer

cement

Values connected by vertical lines are not significantly different (p < .05).

obtained for restorations in series d, where the enamel was etched and dentin bonding agents used. The difference in leakage values between groups a and d was significant (p < .05) for both resins. The use of acid etching only, group b, and the dentin bonding agent only, group c, resulted in intermediate degrees of leakage, but in neither case were values for these two groups significantly different from each other or different from groups a and d. Statistical analysis of these data is summarized in Table V. There was no statistical difference in the leakage values of the two resins under a specific set of conditions. Only for group a was the sealing ability of the glass ionomer cement statistically superior to that of the resins.

Table V. Group B leakage comparisons Ridit Subgroup a

b

C

d

Leakage: cavity A versus cavity B The leakage results obtained for each of the materials placed in the unprepared cavity A and prepared cavity B are compared in Figs. 6 through 8. The graphs present the number of teeth in each group that demonstrated particular degrees of leakage. Because there were only three categories of leakage for restorations in cavity A, but four categories for cavity B, the comparison was facilitated by combining the two most severe leakage categories for the restorations in the cavity B series. The data for the Silux and the Clearfil FII (Kuraray Co., Osaka, Japan) resins (Figs. 6 and 7) indicates that conservative preparation of the cavity tends to reduce the incidence and severity of marginal leakage of the resin restorations. However, Fig. 8 shows that this trend did not apply to the Ketac-Fil glass ionomer cement. There was little difference between the two cavities with respect to the numbers of restorations depicting no and slight leakage.

Leakage at 6 months Table VI demonstrates that the sealing properties of the &month old restorations of Silux placed with acid etching and the dentin bond agents were comparable to

Material

Mean

SD

Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement Clearfil FII resin Silux resin Ketac-Fil glass ionomer cement

0.6770 0.5569 0.2176

0.1957 0.2750 0.1228

0.3766 0.2671 0.2176

0.2038 0.1438 0.1228

0.4186 0.2671 0.2176

0.1867 0.1438 0.1228

0.1835 0.1557 0.2176

0.0881 0.0000 0.1228

Values connected by vertical lines are not significantly @>< .OS).

different

restorations tested after 2 weeks. The restorations placed with the resin bonding agent exhibited a higher incidence of leakage than did those placed with the dentin

bond agent. Bond strength In Table VII the bond strengths bf the resins to bovine enamel with acid etching followed by application of the dentin bonding agents are compared with the bond strengths of the glass ionomer cement. The mode of failure of the specimens, adhesive (separation at the material-tooth interface) or cohesive (failure through the material), are also listed. The tensile, stress required to produce failure to the resins to acid-etched enamel treated with the dentin bonding agents was four to six times that of the glass ionomer enamel specimens. Ketac-Fil glass ionomer cement and Silux resin specimens each failed in cohesion

MONTEIRO

ET AL

LEAKAGE OFEROStONLESIONS

LEAKAGE OFEROSIONLESIONS No Instrumentation

No Instr~;lentation

Instru~Zntatlon ( Ketacfil )

Instrunktation (Silux)

LEAKAGE

cQgu-

AB Resin

AB Resin Acid Etch

AB Resin Bond Agt.

AB Resin Acid Etch Bond Agt.

:: I

A

i&ht ldatmtetom

B B

n

In

l

Fig. 8. Comparison of c@g~ of k&zt~ of ,K+-Eil LEAKAGE A - No ~nstrumentatlon 0 No B = lnstrumsntatlon m Slight I Modarateto Severe Fig. 6. Comparison of degree of leakage of Silux resin restorations in cavities A and B. LEAKAGE OFEROSIONLESIONS No instrumentation vs Instrumentation (Clearfil F II 1

glass ionomer cement re&&atiqnsin

c&ties

A and ‘8.

thermocyckd qxcimens was obtained fw the &.a&1 resin system.Comparabk values Silux resin systemand 4&m&U The resins f&d in a$k&n values for dentin were lower than .fQr enaqgl. A surprising aspectis the lower bo~dvalu~&$~g4 for the glassionomer cement on do bopld to enamel even though in cohesive. The failed q&&n~~ wa tpx fi&&&F-to WaS

microscopic examination at’&& rnag&i~&.‘*

,*

beendone, a difference in r&ef+ilum m& of GIG&G~wA and dentin specimensm&k* have been &scnwSd. The data obtained in this in v$o study on the &i&y of these two composite q&n sysGma to:.s& qrogiun lesions without the classical cavity .preqara@n are encouraging. In all instanqs the useof-&* e&%iqg.jq conjunction with the respective dentin AB Resin

AB Resin Acid Etch

AB Resin BondAgt.

AB Resin AcWftch Bond Agt.

LEAKAGE A No Instrumentation B = Instrum&Wlon l

g Fight I Abamtetosevere

Fig. 7. Comparison of degree of leakage of Clearfil resin restorations in cavities A and 8.

FII

because a layer of material remained on the enamel

surface, whereas Ckarfil FII resin specimensappeared to have separated at the interface. In the bond to dentin tests, the highest value for 440

resulted in a marginal seal that was d$@#$ that of the resin alone. In adclitjon;,the ~ZM$@WX an@ severity of leakage was less,&an which only the bonding agent or Resin restorationsplaced with the and d&in bond agt) a&&the h+qx$ ,ag-v&3 wdid the ghss ionomer cetit, 3 mqt&$: &B to fiawid &em&ally to enamel and de&A. B&daEata &e .in agreement with these of ,&pp et &*I a short-term sealing. It is of p~i~C

apparent dcteriorati~.& t&z s4 w;a test groups stored?n water for 6 men similar 2-week spec

bond will occur with, 1 more rigorous clinical cfxkdkkns of the callnot he predicted. APRIL

1966

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c&y

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RESTORATION

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Table VI. Comparison

AREAS

of sealing properties Leakage category,

Test group

None 1

Time

and No. of specimens

Slight 2

Moderate

to severe 3

Cavity A Silux resin + acid etch + dentin

bond agent

2 Weeks 6 Months

6 7

3 2

1 1

Cavity B Silux resin + acid etch + dentin

bond agent

2 Weeks 6 Months 6 Months

10 10 5

0 0 0

0 0 5

Silux resin + acid etch + resin bond agent (Concise enamel bond)

Table VII. Comparison

of bond strengths 37°C

Enamel Silux resin + acid etch + dentin bond Clearfil FII resin + acid etch t dentin Ketac-Fil glass ionomer cement Dentin Silux resin + acid etch t dentin bond Clearfil FII resin t acid etch t dentin Ketac-Fil glass ionomer cement A = adhesive;

MPa

SD

agent bond agent

6.5 9.2 1.7

3.6 3.0 0.5

agent bond agent

1.4 1.8 0.7

0.5 0.3 0.4

Thermocycled Failure mode

Failure mode

MPa

SD

C A C

9.3 8.9 1.6

2.3 2.2 0.3

C A C

A A C

0.7 2.2 0.6

0.6 0.8 0.4

A A C

C = cohesive.

A considerable amount of data has been reported indicating increased bond strength of resins to etched enamel and dentin with use of a dentin bonding agent.‘*-I6 Most of these data are based on measurements made after only 24-hour storage in water and often without temperature cycling. The data obtained here after 2 weeks in water plus thermostressing of the specimens are in agreement with these shorter term studies. it is notable that there appears to be no direct relationship between bond strength of a particular material and its sealing ability. The system demonstrating the highest strength at failure did not necessarily afford the best cavity seal. However, the bond strength test does not always measure the adhesive bond strength. For example, with glass ionomer cement, the strength of the bond to tooth structure exceeds that of the cohesive strength of the material. The data indicate that the bond to the tooth is in excess of the value reported for specimen failure. Bond strength tests per se are probably more reliable for screening materials for their retentive potential than for predicting their sealing qualities. Of interest is the finding that conservative preparation of the erosion improved the sealing ability of composite restorations, even when dentin bonding agents were used. Invariably there was less leakage of restorations in the prepared cavities compared with unprepared cavities. In addition no problems were encountered with

dislodgement of these restorations. However with the glass ionomer cements, similar preparation had no discernible influence on the sealing properties.

SUMMARY The data indicate that the two dentin bonding agents, used in conjunction with enamel acid etching, provided a superior seal of the cavity compared to the respective resins alone or with either the dentin bond agent or acid etching used alone. The seal of resin restorations placed with the total system (acid etch and dentin bond agent) were comparable to the seal of the glass ionomer cement restorations. Compared with the 2-week specimens, there was no increase in leakage of the &month resin restorations when inserted with dentin bond agents and acid etch. The sealing ability of the resin restorations in conservatively prepared cavities was superior to comparable resin restorations in cavities that had not been prepared. This did not appear to be true for glass ionomer cement restorations. Data obtained to compare the bond strength of resins as used in the study with that of glass ionomer cements do not indicate a precise correlation between bond strength and sealing ability. The exact role of dentin bonding agents await further evaluation of their stability over a prolonged period of time, particularly in clinical investigations.

MONTEIRO

REFERENCES

Il.

Low T: The treatment of hypersensitive cervical abrasion cavities using ASPA cement. J Oral Rehabil 8:8 1, 198 1. 2. hfrLean JW, Wilson AD: The clinical developmem of the glass ionomer cement. 111: The erosion lesion. Aust Dent J 22190, 1977. 9 Powis DR, Tolleras T, Merson SA, Wilson AD: Improved adhesion of a glass ionomer cemem LO dentin. J Dent Res 61:1416. 1982. 4. Orriz RF, Phillips RW, Swartz ML, Osborne JW: Elf& of crm~posire bond agenl on microleakage and bond strength. J 1.

PROSTHET DENT 41:51,

12.

13.

14.

1979.

5.

I’orle A, IAIZ F, Lund MR. Swarm ML, Cochran MA: Cavity designs for wmposite resins. Oper Dem 9:5O, 1984. 6 Ifarris RK, Phillips RW, Swartz ML: An evaluation of IWO rwn sysrems for restoration of abraded areas. J PROSTHET DENT 31:537, 1974. 7. Baurn L, Phillips RW, Lund MR: Texlhook of Operative Demiswy, ed 1. Philadelphia, Pa., 1981, WB Saunders Co, pp 228-229. 8. Phillips RW: The restoration of eroded cervical areas. CDS Rev, April, p 31-34, 1980. 9. Swartz ML, Phillips RW: In vitro sludies on the marginal leakage of restorative materials. J Am Dent Assoc 62:9, 1961. IO. Phillips RW. Swaru ML, Rhodes BF: An evaluation of a carboxylate adhesive cement. J Am Dent Assoc 81:1353, 1970.

15.

16.

ET AL

Rupp NW, Ven? S, Cobb EN: Sealing of the gingival margin of composite restoraCons. J Den[ Res 62~254, 1983 (IADR Abslr No. 765). Share J, Bodkin J: Shear strenglh of composite resin to enamel and denlin with convenGonal and dentin bonding age”&. J Dent Res 63~199, 1984 (IADR Abstr No. 261). Wang S, Goldman M, Nathanson D: Bond swrngth of restorative resins with dentin bonding agents. J Dent Res 63:200, 1984 (IADR Abstr No. 262). Bassiouny M, Ying 1~: Adhesive compatibility of rescoraGve resins with dentin bonding agents. J Dent Res 63:232, 1984 (1.4DR Absw No. 554). Ghan DCN, Reinhardt JW, Jensen ME: Shear bond strength of a new dental adhesive. J Dent Res 63:320, 1984 (IADR Abstr No. 1341). Chalkey Yhl, Jensen ME: Enamel shear bond swengrhs of a denlinal bonding agent. J Dent Res 63:320, 1984 (IADR Absw No. 1342).

l:cp,.rrrl R’~,““‘/ \ lo: 1)~. RALPH W. PHILLIPS INDJANA UNIVERSITY ScHcm~ OF DENTISTRY INDIANAPOLIS. IN 46202

In vitro microleakage of a new dental adhesive system John H. Hembree, Jr., D.D.S.* University of Mississippi, School of Dentistry, Jackson, Miss.

T

reatment of enamel surfaces with an acid etch has provided dentists with a method of obtaining improved mechanical bonding of resin restorative material to enamel surfaces.‘, 2 Attempts at bonding restorative material to dentin have met with limited success.3*4The development of a restorative material that truly adheres to both enamel and dentin would significantly advance the state of the art in dtintistry. Microleakage surrounding the restorations is a major clinical problem associated with limited bonding of a restorative resin to dentin. Excessive microleakage may lead to staining of restorative margins, pulpal sensitivity, and, under certain conditions, secondary caries, as previous investigations have shown.5 Scotchbond (3M Dental Products, St. Paul, Minn.), a

*Professor and Chairman, DeparLment of Restorative Dentistry 442

dental adhesive bonding agent recently developed, has shown good adhesion for composite resins to dentin as well as to enamei.d8 While short-term studies have shown that this material is an effective barrier against microleakage, a question remains concerning the microleakage that may occur after a prolonged period of time. The purpose of this study was to evaiuate microleakage over a period of 1 year when Scotchbond was used on both enamel and dentin surfaces.

MATERIAL

AND METHODS

Ninety-six Class V cavities were prepared with an inverted cone bur in 48 clean, sound, extracted molar teeth. Forty-eight of the preparations were placed on the coronal portion of the tooth so that all margins of the restoration were in enamel. The remaining 48 preparations were placed on the root surface of the tooth so that APRIL

1986

VOLUME

55

NUMBER

4