of glass ionomer
liners
on bonding
Kalipcilar,
DDS,
strength
of laminate
veneers P. Sema Kedici, DDS, dmer G. Bilk, PhDb University
of Ankara,
PhD,a
and METU,
Betiil Ankara,
PhD,a
and
Turkey
This study compared shear bond strengths of porcelain laminate veneers, fabricated on refractory dies, which were lengthened incisally by 0.5 mm. Specimens were divided into four separate groups. In group A, the teeth were reduced 0.5 mm and the bonding was to enamel. The teeth of the remaining groups were reduced 1.0 mm and the bonding was to dentin. For two of the groups glass ionomer liners were applied before etching. Bonding to enamel was best, with cohesive fractures iu porcelain. In the other groups, failure was adhesive in nature, occurring at the resin-tooth interface. (J PROSTHET DENT 1992;68:29-32.)
T
of and clinical techniques for bonded laminate veneers (PLV) are well documented.l-g Although tooth reduction for most laminate veneers is approximately 0.5 mm, with deep discoloration, malalignment, or malposition, teeth may require deeper, more extensive reduction to accomplish the desired esthetic result. In such instances where dentin is exposed, the application of etchants will increase the permeability of dentin, increasing the possibility of pulpal irritation or damage, and increasing sensitivity. lo-I3 Bonding to dentin presents mechanical and chemical problems because of inherent moisture in the substrate and the higher organic content of the dentin.‘* It has been suggested that adequate bond strength can be achieved with minimal sensitivity if the dentin is adequately protected before etching.l Glass ionomer liners have been used successfully to protect dentin by sealing tubules and reducing acid penetration.15-la The purpose of this study was to determine the effect of protective liners on the bonding strength of porcelain veneers when the incisal length of the veneers was lengthened for esthetic reasons. he
advantages
MATERIALS
AND
METHODS
Forty extracted human maxillary central incisor teeth that had been stored in 10 % neutral buffered formalin were randomly distributed into four experimental groups of 10 teeth each. Each tooth was embedded in autopolymerizing poly methylmethacrylate resin poured into a mold to provide a base for testing the crown, which was left exposed. The long axis was positioned vertically with a parallelometer (Fig. 1). After the preliminary set of the resin, the mold was submerged in water to dissipate the heat of reaction.lg aAssociate Dentistry, bProfessor, 10/l/36066
THE
JOURNAL
Professor, University Department
Department of Prosthodontics, of Ankara. of Mechanical Engineering,
OF PROSTHETIC
DENTISTRY
Faculty METU.
of
Preparation of the teeth for laminate veneering was accomplished with facial reduction gingivally and proxi&ally to ensure optimal stress distribution.20 No incisal reduction was made because lengthening of the veneer was desired.21 For group A, tooth preparation was confined to enamel with 0.5 mm reduction. Groups B, C, and D were reduced 1.0 mm in depth to expose the dentin. Preparation reduction was gauged by 0.5 mm and 1.0 mm chamfer diamond instruments, respectively. Porcelain laminate veneers were fabricated on refractory dies with Vitadur-N porcelain (Vita Zahnfabrik, H-Rauter GMBH & Co. K.G., Bad Sackingen, Germany) according to the manufacturer’s instructions (Fig. 2). To further test the cohesive strength of the porcelain and the bond strength of the laminate system, the veneers were lengthened incisally 0.5 mm to allow the indenter of the testing system to rest upon the incisal part of the veneer (Figs. 3 and 4). Prebonding procedures for all samples were carried out as follows: 1. The veneers were completed, removed from the die material by abrasive blasting with fine alumina powder, etched for 5 minutes with diluted hydrofluoric acid solution, and thoroughly washed and dried. 2. Porcelain conditioner, a priming agent that alters free surface energy and removes any contaminant, was applied for 20 seconds to the boundary surface of the veneers, which were then completely washed and dried. 3. Dry Bond (Den-Mat Corporation, Santa Maria, Calif.), a combination of slow volatilizing solvents that ensures a dry, oil-free field and leaves a silane layer on the porcelain that enhances bonding of the composite resin, was applied and gently air-dried. 4. Cerinate prime (Den-Mat Corp.), a combination of phosphorus ester, a silane, and an unfilled bonding resin liner, was applied, dried for 60 seconds, and protected from a visible light source before placement.
29
KEDICJ,
ig. 1. Positioning
Fig.
Bonding
2. Construction
procedure
the specimen
of porcelain
for enamel
into mold.
laminate
veneers.
and dentin
1. The bonding procedure was the same for all groups except for the application of liners to groups C and D, which had two types of glass ionomer liners applied to dentin only. LCL 6 (Voco Chemie, Cuxhaven, Germany), a lightcuring and chemical-curing two-component glass ionomer liner, and Ionoseal (Voco Chemie), a light-curing, onecomponent glass ionomer liner, were applied to dry dentin only. Both liners were cured on the teeth using a halogen light source for 20 seconds. The excess material on the enamel was carefully removed with a rotary instrument. 2. All specimens, including those coated with the glass ionomer, were etched for 30 seconds with 37 % phosphoric acid, rinsed for 30 seconds, and dried for 20 seconds.s2 3. All specimens were processed with Dry Bond and with Creation 3-in-1 bonding agent (Den-Mat Corp.), a dry enamel-dentin bonding agent containing a drying agent,
30
Fig. 3. Lengthening neers.
KALIPCILAR,
the tooth by porcelain
AND
BILIR
laminate
ve-
phosphorus esters, and a light-curing resin liner. This agent was thinly and carefully placed on enamel, dentin, and ionomer surfaces in accordance with the manufacturer’s recommendations. This agent acts as an adhesion promoter. It is recommended for tooth surfaces that are extremely sensitive because of its very low acidity (pH 6.8). It was not exposed to a visible light source before placing the veneer. 4. The porcelain veneers were bonded with a heavyfilled, light-curing hybrid composite resin (Ultrabond, DenMat Corp.) exposed to a visible light source for 60 seconds. 5. An unfilled bonding resin was painted over the margins to remove the excess luting resin, to seal any gaps, and to produce a smooth margin.23 6. The margins were finished with rubber wheels and porcelain laminate polishing paste. After bonding, all specimens were stored in room temperature water for 7 days before testing. Each specimen was placed in the custom-designed apparatus, and aligned with a 15-degree taper using a 15-degree acrylic resin incline prop for the shear test (Fig. 5). All specimens were tested to destruction by center loading in a tensile testing machine (Mohr and Federhaff A.G., Mannheim, Germany) with a continuous loading rate of 0.5 mm/min until failure of the veneer or bond occurred. The shear bond strength was calculated and recorded in megapascals.
RESULTS Shear bond strengths of the test groups are listed in Table I. These data were subjected to a one-way analysis of variance. Identification of different groups was done with Duncan’s multiple range test. Statistically significant differences were found between groups A and C!, where
JULY
1992
VOLUME
68
NUMBER
1
BONDING
Table
STRENGTH
I.
Group A
B C D
OF LAMINATE
VENEERS
Bond strength data and statistical analysis Liner treatment
Mean OfPa)
None None LCL 8* Ionoseal*
*Voco Chemie, Cuxhaven,
8.2 9.8 4.5 7.3
Standard deviation
2.114 2.471 1.545 2.004
% Cohesive failure
90 0 0 0
Germany.
p < 0.01, and betweengroupsB and C, and B and D, where p < 0.05. There were no significant differences in other combinations of groups. Mean bond strength values show that group B has the highest bond strength, followed by groups A, D, and C, in that order. In observing the nature of the failures, only group A showed90% cohesivefailure in porcelain. All other groups showedadhesive failure from the tooth-resin interface.
Fig. 4. Indenter of testing apparatus.
BISCUSSION The strength values obtained are adequatefor retention of laminate veneersin groupsA, B, and D. When silaneplus enamel-dentin bonding adhesivewasused,neither the extent of the preparation nor the liner application had an adverse effect on the bonding strength. The values obtained would have been higher had the laminate veneers not been lengthened. Bond strengths of porcelain to composite resin are about 1100psi (7.5 MPa), sufficient for retention of etched porcelain veneers.24Silane coupling agents used with etched porcelain increased the bond strength to compositeto 2083psi (14.3MPa).25 In comparison, bond strength between the bonding agent and etched enamelsites reached a maximum of 13.27MPa.26 The present research showedthat, although the values for group A were approximately 8.2 MPa, the adhesive bond strength between laminates and enamelwas better than the values obtained in the other groups.Ninety-percent of the failures in group A were cohesivein nature, indicating that the bond strength of laminate to enamelsurpassesthe strength of the porcelain. Cohesive failures have been reported in other studies.27-2gThe highest bond strength obtained in the present study was in group B (9.8 MPa), in which the laminate veneer wasbonded to dentin, indicating that dentin bonding may be used reliably. Failures in group B, alsodetected in groupsD, were adhesive in nature from the compositeresin-tooth interface. This hasbeenassessed to bethe result of pulling away from the dentin becauseof the stronger bond of the resin to porcelain.30 The etching of the glassionomer surface increasesthe strength of the bond to the bonding agent.31In the present study, good results were obtained in group D (7.5 MPa) where the glassionomer liner showeda stronger bond to composite resin and offered adequate stability against
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Fig.
5. Position of specimenfor shearbond strength test-
ing.
pressure. In group C a lower bond strength was obtained (4.5 MPa), which was not as strong as that in group D.
Conclusion 1. Laminate veneerscan belengthenedbeyond supporting tooth structure. To resistcohesivefailure, the porcelain veneer thickness should be increased. 2. When dentin bonding and silane coupling agentsare used, sufficient bond strengths can be achieved for successfulplacement of laminate veneers. 3. When dentin is exposedin tooth preparation for laminate veneer placement, glassionomer liners are effective in protecting dentin surfaces from etchants, and will allow good bonding strength for the veneer to tooth structure.
31
KEDICI,
REFERENCES 1. Calamia JR. High-strength porcelain bonded restorations: anterior, and posterior. Quintessence Int 1989;20:717-26. 2. Oliva RA. Handling and bonding of porcelain veneers-clinical evaluation of a new veneer handling instrument. Quintessence Int 1988; 19593-7. 3. Barr&o MT, Shiu A, Renner RP. Anterior porcelain laminate veneers; clinical and laboratory procedures. Quintessence Dent Technol 1986;1.&493-9. 4. Goldstein RE. Diagnostic dilemma: to bond, laminate, or crown? Int J Periodont Restor Dent 1987;5:9-28. 5. Garher DA. Direct composite veneers versus etched porcelain laminate veneers. Dent Clin North Am 1989;33:301-4. 6. Hobo S, Iwata T. A new laminate veneer technique using a castable ceramic material. Quintessence Int 1985;16:451-7. 7. Boksman L, Jordan RE, Suzuki M, Galil KA, Burgoyne AR. Etched porcelain labial veneers. Ontario Dent 1985;62:11-9. 8. Clyde JS, Gilmour A. Porcelain veneers: a preliminary review. Br Dent J 1988;164:9-14. 9. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 1983;27:671-84. 10. Fuks AG, Funnel B, Jones PC. Pulp response to a composite resin inserted in deep cavities with and without a surface seal. J PROSTHET DENT 1990;63:129-34. Il. Pashley D, Michelich V, Kehl T. Dentine permeability: effects of smear layer removal. J PROSTHET DENT 1981;46:531-7. 12. Br5nnstr8m M, AstrEjm A. The hydrodynamics of the dentine, its possible relationship to dentinal pain. Int Dent J 1972;22:219-27. 13. Franquin JC, Brouillet JL. Biocompatibility of an enamel and dentine adhesive under different conditions of application. Quintessence Int 1988;19:813-26. 14. Kanka J. An alternative hypothesis to the cause of pulpal inflammation in teeth treated with phosphoric acid an the dentine. Quintessence Int 1990;21:83-6. 1.5, Swift EJ Jr. An update on glass-ionomer cements. Quintessence Int 1988;19:125-30. 16. Godoy FG. Glass ionomer materials in class II composite resin restorations: to etch, or not to etch? Quintessence Int 1988;19:241-2. 17. Kedici PS, Alkumru HN, Ercan MT. Autoradiographic determination of penetration of phosphoric acid during cementation in vitro. J Dent 1988;16:242-3.
32
KALIPCILAR,
AND
BILIR
18. Arends J, Ruben J. Fluoride release from a composite resin. Quintessence Int 1988;19:513-4. 19. Davis EL, Joynt RB, Wieczkowski G Jr, Laura JC. Bond durability between dentinal bonding agents and tooth structure. J PROSTHET DENT 1989;62:253-6.
20. Highton R, Caputo AA, Matyes J. A photoelastic study of stresses on porcelain laminate preparations. J PROSTHET DENT 1987;58:157-61. 21. Calamina JR. Etched porcelain veneers: the current state of the art. Quintessence Int 1985;1:5-12. 22. Godoy FG, Draheim RN, Titus HW. Shear bond strength of a posterior composite resin to glass ionomer bases. Quintessence Int 1988$9:357-g. 23. Tay WM, Lynch E, Anger D. Effects of some finishing techniques on cervical margins of porcelain laminates. Quintessence Int 1987;18:599602. 24. Simonsen RJ, Calamia JR. Tensile bond strength of etched porcelain [Abstract]. J Dent Res 1983;62:297. 25. Calamia JR, Simonsen RJ. Effect of coupling agents on bond strength of etched porcelain [Abstract]. J Dent Res 1984;63:179. 26. Cooley RL, Dodge WW. Bond strength of three dentinal adhesives on recently extracted versus aged teeth. Quintessence Int 1989;20:513-6. 27. Pratt RC, Burgess JO, Schwartz RS, Smith JH. Evaluation of bond strength of six porcelain repair systems. J PROSTHET DENT 1989;62:11-3. 28. Diaz-Arnold AM, Aquilino SA. An evaluation of the bond strengths of four organosilane materials in response to thermal stress. J PROSTHET DENT 1989;62:257-60. 29. Stangel I, Nathanson D, Hsu CS. Shear strength of the composite bond to etched porcelain. J Dent Res 1987;66:1460-5. 30. Tjan AHL, Dunn JR, Sanderson IR. Microleakage patterns of porcelain and castable ceramic laminate veneers. J PROSTHET DENT 1989;61:27682. 31. Hinoura K, Moore OK, Phillips RW. Tensile bond strength between glass ionomer cements and composite resins. J Am Dent Assoc 1987; 114~167-72. Reprint requests to: DR. P. SEMA KEDICI ~~.SOKAK.NO:~/~, BAHCELIEVLER ANKARA, TURKEY
JULY
1992
VOLUME
68
NUMBER
1
liners
on bonding
Kalipcilar,
DDS,
strength
of laminate
veneers P. Sema Kedici, DDS, dmer G. Bilk, PhDb University
of Ankara,
PhD,a
and METU,
Betiil Ankara,
PhD,a
and
Turkey
This study compared shear bond strengths of porcelain laminate veneers, fabricated on refractory dies, which were lengthened incisally by 0.5 mm. Specimens were divided into four separate groups. In group A, the teeth were reduced 0.5 mm and the bonding was to enamel. The teeth of the remaining groups were reduced 1.0 mm and the bonding was to dentin. For two of the groups glass ionomer liners were applied before etching. Bonding to enamel was best, with cohesive fractures iu porcelain. In the other groups, failure was adhesive in nature, occurring at the resin-tooth interface. (J PROSTHET DENT 1992;68:29-32.)
T
of and clinical techniques for bonded laminate veneers (PLV) are well documented.l-g Although tooth reduction for most laminate veneers is approximately 0.5 mm, with deep discoloration, malalignment, or malposition, teeth may require deeper, more extensive reduction to accomplish the desired esthetic result. In such instances where dentin is exposed, the application of etchants will increase the permeability of dentin, increasing the possibility of pulpal irritation or damage, and increasing sensitivity. lo-I3 Bonding to dentin presents mechanical and chemical problems because of inherent moisture in the substrate and the higher organic content of the dentin.‘* It has been suggested that adequate bond strength can be achieved with minimal sensitivity if the dentin is adequately protected before etching.l Glass ionomer liners have been used successfully to protect dentin by sealing tubules and reducing acid penetration.15-la The purpose of this study was to determine the effect of protective liners on the bonding strength of porcelain veneers when the incisal length of the veneers was lengthened for esthetic reasons. he
advantages
MATERIALS
AND
METHODS
Forty extracted human maxillary central incisor teeth that had been stored in 10 % neutral buffered formalin were randomly distributed into four experimental groups of 10 teeth each. Each tooth was embedded in autopolymerizing poly methylmethacrylate resin poured into a mold to provide a base for testing the crown, which was left exposed. The long axis was positioned vertically with a parallelometer (Fig. 1). After the preliminary set of the resin, the mold was submerged in water to dissipate the heat of reaction.lg aAssociate Dentistry, bProfessor, 10/l/36066
THE
JOURNAL
Professor, University Department
Department of Prosthodontics, of Ankara. of Mechanical Engineering,
OF PROSTHETIC
DENTISTRY
Faculty METU.
of
Preparation of the teeth for laminate veneering was accomplished with facial reduction gingivally and proxi&ally to ensure optimal stress distribution.20 No incisal reduction was made because lengthening of the veneer was desired.21 For group A, tooth preparation was confined to enamel with 0.5 mm reduction. Groups B, C, and D were reduced 1.0 mm in depth to expose the dentin. Preparation reduction was gauged by 0.5 mm and 1.0 mm chamfer diamond instruments, respectively. Porcelain laminate veneers were fabricated on refractory dies with Vitadur-N porcelain (Vita Zahnfabrik, H-Rauter GMBH & Co. K.G., Bad Sackingen, Germany) according to the manufacturer’s instructions (Fig. 2). To further test the cohesive strength of the porcelain and the bond strength of the laminate system, the veneers were lengthened incisally 0.5 mm to allow the indenter of the testing system to rest upon the incisal part of the veneer (Figs. 3 and 4). Prebonding procedures for all samples were carried out as follows: 1. The veneers were completed, removed from the die material by abrasive blasting with fine alumina powder, etched for 5 minutes with diluted hydrofluoric acid solution, and thoroughly washed and dried. 2. Porcelain conditioner, a priming agent that alters free surface energy and removes any contaminant, was applied for 20 seconds to the boundary surface of the veneers, which were then completely washed and dried. 3. Dry Bond (Den-Mat Corporation, Santa Maria, Calif.), a combination of slow volatilizing solvents that ensures a dry, oil-free field and leaves a silane layer on the porcelain that enhances bonding of the composite resin, was applied and gently air-dried. 4. Cerinate prime (Den-Mat Corp.), a combination of phosphorus ester, a silane, and an unfilled bonding resin liner, was applied, dried for 60 seconds, and protected from a visible light source before placement.
29
KEDICJ,
ig. 1. Positioning
Fig.
Bonding
2. Construction
procedure
the specimen
of porcelain
for enamel
into mold.
laminate
veneers.
and dentin
1. The bonding procedure was the same for all groups except for the application of liners to groups C and D, which had two types of glass ionomer liners applied to dentin only. LCL 6 (Voco Chemie, Cuxhaven, Germany), a lightcuring and chemical-curing two-component glass ionomer liner, and Ionoseal (Voco Chemie), a light-curing, onecomponent glass ionomer liner, were applied to dry dentin only. Both liners were cured on the teeth using a halogen light source for 20 seconds. The excess material on the enamel was carefully removed with a rotary instrument. 2. All specimens, including those coated with the glass ionomer, were etched for 30 seconds with 37 % phosphoric acid, rinsed for 30 seconds, and dried for 20 seconds.s2 3. All specimens were processed with Dry Bond and with Creation 3-in-1 bonding agent (Den-Mat Corp.), a dry enamel-dentin bonding agent containing a drying agent,
30
Fig. 3. Lengthening neers.
KALIPCILAR,
the tooth by porcelain
AND
BILIR
laminate
ve-
phosphorus esters, and a light-curing resin liner. This agent was thinly and carefully placed on enamel, dentin, and ionomer surfaces in accordance with the manufacturer’s recommendations. This agent acts as an adhesion promoter. It is recommended for tooth surfaces that are extremely sensitive because of its very low acidity (pH 6.8). It was not exposed to a visible light source before placing the veneer. 4. The porcelain veneers were bonded with a heavyfilled, light-curing hybrid composite resin (Ultrabond, DenMat Corp.) exposed to a visible light source for 60 seconds. 5. An unfilled bonding resin was painted over the margins to remove the excess luting resin, to seal any gaps, and to produce a smooth margin.23 6. The margins were finished with rubber wheels and porcelain laminate polishing paste. After bonding, all specimens were stored in room temperature water for 7 days before testing. Each specimen was placed in the custom-designed apparatus, and aligned with a 15-degree taper using a 15-degree acrylic resin incline prop for the shear test (Fig. 5). All specimens were tested to destruction by center loading in a tensile testing machine (Mohr and Federhaff A.G., Mannheim, Germany) with a continuous loading rate of 0.5 mm/min until failure of the veneer or bond occurred. The shear bond strength was calculated and recorded in megapascals.
RESULTS Shear bond strengths of the test groups are listed in Table I. These data were subjected to a one-way analysis of variance. Identification of different groups was done with Duncan’s multiple range test. Statistically significant differences were found between groups A and C!, where
JULY
1992
VOLUME
68
NUMBER
1
BONDING
Table
STRENGTH
I.
Group A
B C D
OF LAMINATE
VENEERS
Bond strength data and statistical analysis Liner treatment
Mean OfPa)
None None LCL 8* Ionoseal*
*Voco Chemie, Cuxhaven,
8.2 9.8 4.5 7.3
Standard deviation
2.114 2.471 1.545 2.004
% Cohesive failure
90 0 0 0
Germany.
p < 0.01, and betweengroupsB and C, and B and D, where p < 0.05. There were no significant differences in other combinations of groups. Mean bond strength values show that group B has the highest bond strength, followed by groups A, D, and C, in that order. In observing the nature of the failures, only group A showed90% cohesivefailure in porcelain. All other groups showedadhesive failure from the tooth-resin interface.
Fig. 4. Indenter of testing apparatus.
BISCUSSION The strength values obtained are adequatefor retention of laminate veneersin groupsA, B, and D. When silaneplus enamel-dentin bonding adhesivewasused,neither the extent of the preparation nor the liner application had an adverse effect on the bonding strength. The values obtained would have been higher had the laminate veneers not been lengthened. Bond strengths of porcelain to composite resin are about 1100psi (7.5 MPa), sufficient for retention of etched porcelain veneers.24Silane coupling agents used with etched porcelain increased the bond strength to compositeto 2083psi (14.3MPa).25 In comparison, bond strength between the bonding agent and etched enamelsites reached a maximum of 13.27MPa.26 The present research showedthat, although the values for group A were approximately 8.2 MPa, the adhesive bond strength between laminates and enamelwas better than the values obtained in the other groups.Ninety-percent of the failures in group A were cohesivein nature, indicating that the bond strength of laminate to enamelsurpassesthe strength of the porcelain. Cohesive failures have been reported in other studies.27-2gThe highest bond strength obtained in the present study was in group B (9.8 MPa), in which the laminate veneer wasbonded to dentin, indicating that dentin bonding may be used reliably. Failures in group B, alsodetected in groupsD, were adhesive in nature from the compositeresin-tooth interface. This hasbeenassessed to bethe result of pulling away from the dentin becauseof the stronger bond of the resin to porcelain.30 The etching of the glassionomer surface increasesthe strength of the bond to the bonding agent.31In the present study, good results were obtained in group D (7.5 MPa) where the glassionomer liner showeda stronger bond to composite resin and offered adequate stability against
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Fig.
5. Position of specimenfor shearbond strength test-
ing.
pressure. In group C a lower bond strength was obtained (4.5 MPa), which was not as strong as that in group D.
Conclusion 1. Laminate veneerscan belengthenedbeyond supporting tooth structure. To resistcohesivefailure, the porcelain veneer thickness should be increased. 2. When dentin bonding and silane coupling agentsare used, sufficient bond strengths can be achieved for successfulplacement of laminate veneers. 3. When dentin is exposedin tooth preparation for laminate veneer placement, glassionomer liners are effective in protecting dentin surfaces from etchants, and will allow good bonding strength for the veneer to tooth structure.
31
KEDICI,
REFERENCES 1. Calamia JR. High-strength porcelain bonded restorations: anterior, and posterior. Quintessence Int 1989;20:717-26. 2. Oliva RA. Handling and bonding of porcelain veneers-clinical evaluation of a new veneer handling instrument. Quintessence Int 1988; 19593-7. 3. Barr&o MT, Shiu A, Renner RP. Anterior porcelain laminate veneers; clinical and laboratory procedures. Quintessence Dent Technol 1986;1.&493-9. 4. Goldstein RE. Diagnostic dilemma: to bond, laminate, or crown? Int J Periodont Restor Dent 1987;5:9-28. 5. Garher DA. Direct composite veneers versus etched porcelain laminate veneers. Dent Clin North Am 1989;33:301-4. 6. Hobo S, Iwata T. A new laminate veneer technique using a castable ceramic material. Quintessence Int 1985;16:451-7. 7. Boksman L, Jordan RE, Suzuki M, Galil KA, Burgoyne AR. Etched porcelain labial veneers. Ontario Dent 1985;62:11-9. 8. Clyde JS, Gilmour A. Porcelain veneers: a preliminary review. Br Dent J 1988;164:9-14. 9. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 1983;27:671-84. 10. Fuks AG, Funnel B, Jones PC. Pulp response to a composite resin inserted in deep cavities with and without a surface seal. J PROSTHET DENT 1990;63:129-34. Il. Pashley D, Michelich V, Kehl T. Dentine permeability: effects of smear layer removal. J PROSTHET DENT 1981;46:531-7. 12. Br5nnstr8m M, AstrEjm A. The hydrodynamics of the dentine, its possible relationship to dentinal pain. Int Dent J 1972;22:219-27. 13. Franquin JC, Brouillet JL. Biocompatibility of an enamel and dentine adhesive under different conditions of application. Quintessence Int 1988;19:813-26. 14. Kanka J. An alternative hypothesis to the cause of pulpal inflammation in teeth treated with phosphoric acid an the dentine. Quintessence Int 1990;21:83-6. 1.5, Swift EJ Jr. An update on glass-ionomer cements. Quintessence Int 1988;19:125-30. 16. Godoy FG. Glass ionomer materials in class II composite resin restorations: to etch, or not to etch? Quintessence Int 1988;19:241-2. 17. Kedici PS, Alkumru HN, Ercan MT. Autoradiographic determination of penetration of phosphoric acid during cementation in vitro. J Dent 1988;16:242-3.
32
KALIPCILAR,
AND
BILIR
18. Arends J, Ruben J. Fluoride release from a composite resin. Quintessence Int 1988;19:513-4. 19. Davis EL, Joynt RB, Wieczkowski G Jr, Laura JC. Bond durability between dentinal bonding agents and tooth structure. J PROSTHET DENT 1989;62:253-6.
20. Highton R, Caputo AA, Matyes J. A photoelastic study of stresses on porcelain laminate preparations. J PROSTHET DENT 1987;58:157-61. 21. Calamina JR. Etched porcelain veneers: the current state of the art. Quintessence Int 1985;1:5-12. 22. Godoy FG, Draheim RN, Titus HW. Shear bond strength of a posterior composite resin to glass ionomer bases. Quintessence Int 1988$9:357-g. 23. Tay WM, Lynch E, Anger D. Effects of some finishing techniques on cervical margins of porcelain laminates. Quintessence Int 1987;18:599602. 24. Simonsen RJ, Calamia JR. Tensile bond strength of etched porcelain [Abstract]. J Dent Res 1983;62:297. 25. Calamia JR, Simonsen RJ. Effect of coupling agents on bond strength of etched porcelain [Abstract]. J Dent Res 1984;63:179. 26. Cooley RL, Dodge WW. Bond strength of three dentinal adhesives on recently extracted versus aged teeth. Quintessence Int 1989;20:513-6. 27. Pratt RC, Burgess JO, Schwartz RS, Smith JH. Evaluation of bond strength of six porcelain repair systems. J PROSTHET DENT 1989;62:11-3. 28. Diaz-Arnold AM, Aquilino SA. An evaluation of the bond strengths of four organosilane materials in response to thermal stress. J PROSTHET DENT 1989;62:257-60. 29. Stangel I, Nathanson D, Hsu CS. Shear strength of the composite bond to etched porcelain. J Dent Res 1987;66:1460-5. 30. Tjan AHL, Dunn JR, Sanderson IR. Microleakage patterns of porcelain and castable ceramic laminate veneers. J PROSTHET DENT 1989;61:27682. 31. Hinoura K, Moore OK, Phillips RW. Tensile bond strength between glass ionomer cements and composite resins. J Am Dent Assoc 1987; 114~167-72. Reprint requests to: DR. P. SEMA KEDICI ~~.SOKAK.NO:~/~, BAHCELIEVLER ANKARA, TURKEY
JULY
1992
VOLUME
68
NUMBER
1
