Effects of Cement-curing Modes on Dentin Bonding of Inlays R. ZUELLIG-SINGER, I. KREJCI, and F. LUTZ Department of Preventive Dentistry, Periodontology and Cariology, Dental Institute, University of Zurich, Plattenstrasse 11, 8028 Zurich, Switzerland

The aim of this in vitro study was to evaluate dentin adhesion after strong as that to etched enamel (Fassbinder et al., 1989). Neverthecementation of immediate direct "All Purpose" Hybrid (AP.H) com- less, a high composite-dentin bond strength does not guarantee the posite inlays (Dentsply) and Cerec Dicor-MGC (Dentsply) inlays prevention of gaps along the dentinal wall, because there is a with the dentin adhesive Prisma Universal Bond 2 (Dentsply) and competition between the composite-dentin bond strength and the polymerization contraction stress (Davidson et al., 1984). The flow the dual-curing Dicor-MGC luting composite (Dentsply). In 24 extracted human molars, standard MOD cavities were of curing composite is an important mechanism in reduction ofthe prepared with one approximal margin located in enamel and the shrinkage effect (Davidson and de Gee, 1984). Since chemicallyother one located in dentin. They were divided into four groups: (I) cured composites polymerize more slowly than light-cured ones, the AP.H inlays, luting composite only, chemically cured; (II) AP.H time during which the flow from the free surface will take place is inlays, luting composite, immediately-light-cured; (III) AP.H in- longer (Itoh et al., 1986). The aim of this study was to determine whether the bond lays, luting composite, initially chemically and delayed-light-cured (15 min); and (IV) MGC inlays, luting composite, initially chemi- between tooth-colored adhesive inlays and dentin covered with PUB cally and delayed-light-cured (15 min). In vitro load cycles corre- 2 may be influenced by different curing modes of a dual-cured luting sponding to five years ofclinical stress followed. Initially and after composite. specimens were loaded, the margins were analyzed quantitatively by SEM. The tooth/cement and cement/inlay interfaces were scored Materials and methods. separately. The initial percentages of "continuous margin"-at both the Twenty-four caries-free extracted human molars were mounted on tooth/luting composite and luting composite/inlay interfaces-were carriers (Balzers Union AG, Balzers, Liechtenstein) with resin higher than 94% for all groups. At the end of the load cycles, the (Paladur, Kulzer and Co. GmbH, Friedrichsdorf, Germany). They quality of the margins at the tooth/luting composite interface were divided into the following four groups (n = 6) of similar-sized significantly decreased for all groups. The highest decrease was molars: (1) chairside composite inlays (PrismaAP.H, De Trey/Dentsply, found for the cervical margins located in dentin, where only 37%61% were scored as "continuous margin". The AP.H inlay/luting Konstanz, Germany), composite cement (Dicor MGC luting composcomposite interface showed almost no change. At the MGC inlay/ ite, De Trey/Dentsply, Konstanz, Germany), solely chemically cured; (2) chairside composite inlays, composite cement immediately luting composite interface, the percentage of "continuous margin" light cured; decreased to 74%. (3) chairside composite inlays, composite cement chemically After specimens were loaded, the percentage of "continuous margin" in dentin was lower than in enamel, despite the use of a cured for 15 min, then light-cured; and (4) CEREC glass ceramic inlays (Dicor MGC, De Trey/Dentsply, dentin bonding agent (PUB 2). Chemical curing alone and immediate- and delayed-light-curing modes of the dual-cured luting com- Konstanz, Germany), composite cement chemically cured for 15 posite showed "continuous margin" scorings which were not statis- min, then light-cured. Standard MOD cavities with equal dimensions were prepared tically different from each other. with one approximal gingival margin in dentin and the other 1 mm above the cemento-enamel junction. The molars of all groups were J Dent Res 71(11):1842-1846, November, 1992 prepared without beveled margins. Group 4 was prepared as follows: in the occlusal part, parallel walls; in the approximal parts, Introduction. 40 divergent walls. This is the CEREC preparation recommended Patient demand for tooth-colored posterior restorations is increas- by the manufacturer. All cavities were finished and controlled ing. The chairside composite and ceramic inlays are superior under a stereomicroscope with 12x magnification (Stereomikroskop alternatives to direct composite fillings (Sheth et al., 1989; Shortall M5A, Wild Ag, Heerbrugg, Switzerland). et al., 1989). The CEREC method is a newly developed CAD-CAM The composite inlays were fabricated as follows: A translucent restorative method which facilitates the direct chairside placement matrix band (Hawe-Molar transparent bands, Hawe-Neos Dental, of ceramic inlays (Smith and Cardwell, 1989) and has been used Lugano, Switzerland) was wrapped around the tooth, and an insuclinically since 1986 (Moermann et al., 1989). lating gel (Kulzer and Co. GmbH, Friedrichsdorf, Germany) was Adhesive restorations require a perfect seal, because they do not applied twice to the cavity to facilitate the removal of the inlay. The produce caries-protective corrosion products as do amalgam fillings. cavity was filled with the AP.H composite and light-cured (Translux An almost-perfect marginal adaptation for composite and ceramic CL, Kulzer and Co. GmbH, Friedrichsdorf, Germany) for 60 s for inlays to enamel margins can be achieved when the enamel margins each surface. After removal ofgross excesses, the inlaywas removed are acid-etched and the in situ shrinking composite mass is reduced from the cavity and heated to 100'C for 10 min in an oven (Hovo, Dr. (Buonocore, 1955; Krejci et al., 1990c). Prisma Universal Bond 2, an A Hofmann, Ostfildern, Germany). The inner cementing surfaces improved version is of PUB (De Trey/Dentsply, Konstanz, Ger- were then roughened with a 25-jin diamond bur (Intensiv SA, many), is a two-component enamel-dentin adhesive which was Lugano-Viganello, Switzerland). designed to adhere to both the organic and the inorganic compoThe CEREC inlays were cut by means of a CEREC machine nents of dentin. The bond strength of PUB 2 to dentin is almost as (Model 01 406 S 02, Siemens, Bensheim, Germany) with 1989 software. It consisted of a three-dimensional video camera, an electronic processor, and a computer connected to a miniature milling machine. The camera head was positioned over the tooth so Received for publication October 31, 1991 that an optical impression of the cavity could be taken. A static Accepted for publication May 11, 1992 Downloaded from jdr.sagepub.com at Univ of Connecticut / Health Center / Library on June 4, 2015 For personal use only. No other uses without permission.

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EFFECTS OF CEMENT CURING MODES ON DENTIN BONDING

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pseudoplastic image ofthe tooth appeared on the screen. Individual marker points were set to define the cavity floor and the approximal contours. Then the restoration walls were determined automatically(Moermannetal., 1989). The electronically designed inlaywas then milled, through computer control, out of a machinable glass ceramic block (Dicor MGC, De Trey/Dentsply, Konstanz, Germany) based on the Dicor glass ceramic formulation (Adair and Grossmann, 1984). The CEREC surfaces to be cemented were etched for 30 s with 10% ammonium-bifluoride gel (Dicor etching gel, De Trey/ Dentsply, Konstanz, Germany), rinsed for 30 s, and carefully airdried. The silane coupling agent (Caulk/Dentsply, Milford, DE) was applied twice to the etched inlay surfaces and air-dried. Athin layer of PUB 2 adhesive was applied to both the composite and the glass ceramic inlays. The enamel margins of the cavities were etched for 30 s exclusively with 37% phosphoric acid (Etching gel, Dentsply, York, PA). The cavities were then rinsed for 30 s and air-dried. The PUB 2 primer was carefully applied, by brush, onto the dentinal parts of the approximal box with the gingival margin located in dentin and air-dried after 20 s of reaction time. The application and lightcuringfor60 s ofa thin layer of PUB 2 adhesive over the whole cavity followed. The teeth were mounted in a device with two natural teeth which simulated the approximal contacts, and translucent matrix bands (Hawe-Neos Dental, Lugano, Switzerland) were wedged with light-reflecting wedges (Hawe-Neos Dental, Lugano, Switzerland). The DicorMGC cementwas mixed 1:1 and applied to the inlays. The inlays were placed two-thirds of the way into the cavities, and the gross excess ofthe luting cement was removed. Finally, the inlays were seated completely, and the small excess was left for curing. Group 1 was stored in the dark to be chemically-cured for 24 h. Group 2 was light-cured for 60 s on each surface, and groups 3 and 4 were stored in the dark for 15 min and then light-cured in a manner analogous to that for group 2. Finally, all the inlays were contoured and polished with fine diamonds (Composhape, Intensiv SA, Lugano-Viganello, Switzerland) and flexible discs (Pop-On, 3M Co., St. Paul, MN). The restored teeth were exposed to in vitro load-cycling tests. The teeth were immersed in ethanol (75%) for 24-112 h and brushed with a toothpaste solution (Signal, Elida Cosmetics, Zurich, Switzerland) for 30-140 min with a force of 1.96 N. The teeth were then exposed to a chewing test (120,000-560,000 chewing cycles) with natural enamel cusp tips as antagonists (1.7 Hz), with a threshold loading of 49 N. This test was performed in a water chamber (1 mmol/L NaCl) with simultaneous thermocycling (5-55-50C). The cycles of the different stress tests varied and are shown in Fig. 1. This load-cycling corresponded to five years ofclinical stress (Krejci et al., 1990a,b). Polyvinylsiloxane impressions (Coltene AG, Altstatten, Switzerland) were taken, before and after the loading test, of all restoration surfaces, and epoxy models were made (Stycast, Emerson and Cuming, Westerlo-Oevel, Belgium). These replicas were used for a quantitative margin analysis with a SEM (Amray, Dortmund, Germany) with a 100x magnification. The tooth/cement and cement/inlay interfaces were scored separately. The following evaluation criteria were used: "continuous margin", "gap", "enamel fracture", "inlay fracture", "overhang", and "underfilled margin" (Krejciet al., 1990c). Statistical analyses were performed by ANOVA and a Scheffe test (Phillips, 1978) so that the significance of the differences in percentage of "continuous margins" between the groups could be determined. The paired t test was used for the comparison of the percentages of "continuous margin" before and after the load-cycling for each group.

24 h 75% Ethanol dentin, and cervical margin of approximal box in enamel and 30 min Tooth Brushing dentin, respectively. Figs. 2-5 show the percentage of "continuous margin" at these loca120,000 Chewing Cycles, 49 N 300 Thermal Cycles tions. The criteria"overhang", (warm 550C, cold 50C), 2 min Intervals "underfilled margin", and "inlay fractures" were found in less than 1% for all groups. The initial percentage of 24 h 75% Ethanol enamel fractures was 0% for 30 min Tooth Brushing all groups, except for group 4 (CEREC-Dicor inlays, de120,000 Chewing Cycles, 49 N layed-light-cured cement), 300 Thermal Cycles where the percentage was (warm 550C, cold 50C), 2 min Intervals 2.5%. After the load cycles, 7.6% of group 3 (AP.H inlays, delayed-light-cured cement) had enamel fractures. Group 80 h 75% Ethanol 2 (AP.H inlays, immediately 100 min Tooth Brushing light-cured cement) had 5.1% and group 1 (AP.H inlays, 400,000 Chewing Cycles, 49 N chemically-cured cement) 3.8%. The lowest percentage 1000 Thermal Cycles ofenamelfractures (3.5%) was (warm 550C, cold 50C), 2 min Intervals found for group 4. The significance ofthe differences between the initial 112 h 75% Ethanol (before the load-cycling) and final (after the load-cycling) min percentages of "continuous 560,000 Chewing Cycles, 49 N margin" is shown in Table 1. In Table 2, the significance of Thermal the differences among the 55°C, 5°C), min groups after loading is represented. Fi g. 1-In vitro load cycles. The initial percentage of "continuous margin" at the tooth/luting composite interface for the total restoration margin was between 94% and 98%. There were no significant differences amongthe four groups. On the other hand, at the cervical margin located in dentin, 77-99% were scored as "continuous margin". Group 1, with the chemically-cured composite cement, had the lowest percentage of "continuous margin". The initial percentage of "continuous margin" at the inlay/ luting composite interface was higher than 97% for all groups, without significant differences among the groups. After the load cycles, the percentage of "continuous margin" for the total restoration margin dropped to 77-94% at the tooth/luting composite interface. The analysis ofthe different margin locations indicated that the cervical dentin margin had the largest reduction in marginal adaptation, where only 37-61% were scored as "continuous margin". There was no statistically significant difference found for the percentage of "continuous margin" in dentin between the different curing modes. The interface AP.H inlay/luting composite showed almost no change after the load cycles. The percentage of "continuous margin" for the total restoration was more than 93% in all composite inlay groups. Only the interface between MGC inlays and luting composite deteriorated, with statistical significance, to 73% after the load

Results.

Discussion.

The following sections in the restoration margin were analyzed separately: total restoration margin, occlusal, approximal box with cervical margin in enamel, approximal box with cervical margin in

All parts of the restorations had initially a high degree of "continuous margin" score in all groups, because the adhesive inlay technique was used. Cementing an already-cured inlay reduced the

1

140

Tooth

Brushing

Cycles

(warm

cold

2

Intervals

test.

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J Dent Res November 1992

TABLE 1 SIGNIFICANCE OF THE DIFFERENCE IN PERCENTAGE OF "CONTINUOUS MARGIN" BETWEEN THE INITIAL AND FINAL RESULTS 1 Group Interface Enamel! Cement * Occlusal * Approximal Box w/Cerv. Margin in Enamel * Cervical Margin in Enamel * Approximal Box w/Cerv. Margin in Dentin * Cervical Margin in Dentin ** Total Restoration Interface Cement/Inlay n.s. Occlusal n.s. Approximal Box w/Cerv. Margin in Enamel n.s. Cervical Margin in Enamel * Approximal Box w/Cerv. Margin in Dentin n.s. Cervical Margin in Dentin * Total Restoration The tooth/cement and cement/inlay interface was analyzed separately. * p < 0.05; ** p < 0.01; *** p < 0.001. mass of shrinking composite in situ. The effects of the residual shrinkage were mitigated by the deformation of the cavity walls (McCulloch and Smith, 1986). Because light-cured composites always contract toward the curing-light source, the light-reflecting wedges used for groups 2-4 directed the contraction of the luting composite toward the cervical margins (Lutz et al., 1986). Prisma

2

3

4

n.s. n.s. n.s. * ** *

n.s. n.s. n.s. ** ***

n.s. n.s. n.s. * * *

n.s. n.s. n.s. n.s. n.s.

n.s. n.s. n.s. n.s. n.s.

n.s. n.s. n.s.

n.s.

n.s.

**

**

Universal Bond 2 provided an excellent bond to dentin, which corresponds to the results found by Bronwasser et al. (1991). Although the chemically-cured composite cement showed a porous structure, attributable to incomplete polymerization, there was no statistically significant difference between the effects ofthe curing modes and the inlay materials used.

TABLE 2 SIGNIFICANCE OF THE DIFFERENCES BETWEEN THE EXPERIMENTAL GROUPS AFTER THE LOAD CYCLES (ANOVA AND SCHEFFE TEST) Comparison between Groups 2 and 3 2 and 4 1 and 3 1 and 4 1 and 2

Enamel /Cement Occl. Approx. w/Cerv. E Cerv. Enamel Approx. w/Cerv. D Cerv. Dentin Total Cement/Inlay Occl. Approx. w/Cerv. E Cerv. Enamel Approx. w/Cerv. D Cerv. Dentin Total

* * * n.s. n.s. n.s.

n.s. n.s. n.s. n.s. n.s. n.s.

** *

3 and 4

* * * n.s. n.s. n.s.

* * * n.s. n.s. n.s.

n.s. n.s. n.s. n.s. n.s. n.s.

n.s. n.s. n.s. n.s. n.s. n.s.

n.s. n.s. n.s. n.s. n.s. n.s.

n.s. n.s. n.s. n.s. n.s.

* * * n.s. n.s. *

n.s. n.s. n.s. n.s. n.s. n.s.

* * * n.s. n.s. *

* * * n.s. n.s. *

n.s.

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EFFECTS OF CEMENT CURING MODES ON DENTIN BONDING

Vol. 71 No. 11

Interface Cementlinlay:

Interface Tooth/Cement:

Interface Cement/Inlay: Interface Tooth/Cement: Eli Initial S Initial m After Load Cycles _ After Load Cycles

E Initial m After Load Cycles

1M Initial - After Load Cycles

100

Total

Cccl.

Approx.w Approx.w Cerv. D Cev. E

Cerv. E

Cerv. D

Total

Occ.

Approx. w Approx. w Cerv. E Cerv. D

Cerv. E

Cerv. D

Fig. 3-Bar diagram showing the mean percentage of "continuous

Fig. 2-Bar diagram showing the mean percentage of "continuous margin" (% "CM") of group 1 (AP.H inlays, composite cement chemically-

margin" of group 2 (AP.H inlays, light-cured composite cement). Key as in

cured), initially and afterthe load cycles. The differentlocations and the two interfaces were analyzed separately. D = dentin. E = enamel.

Fig. 2.

At the end ofthe load cycles, the marginal adaptation of the total restoration at the tooth/cement interface was significantly reduced. However, more than 77% were still scored as "continuous margin". Only'"continuous margin" is clinically acceptable and guarantees no microleakage. Even a minute gap can widen to a critical size, allowing bacteria to pump into the gap, because of the elastic deformation of the tooth and the restorative materials during fiction (Jensen and Chan, 1985). In enamel, the marginal quality was still excellent. This indicates that the bond to enamel was stable. The biggest decrease of marginal quality was found for the cervical margin in dentin. Nevertheless, the percentage of "continuous margin" in dentin was clearly higher than in a comparable study without dentin adhesives (Holz et al., 1991). Despite the good initial results, the dentin adhesive disintegrated during the load cycles. One way to counteract the deterioration of the compound between the composite cement and the dentin during function is to maximize the bond

initially. Less shrinkage results in a stronger bond. One way to reduce shrinkage is to take advantage of the flow of curing composite material from the free surface (Davidson and de Gee, 1984). The amount of flow is highly dependent on the cavity configuration (Feilzer et al., 1987). In thin composite layers, bonded to two opposing walls and with a small free surface, the flow capacity decreases (Feilzer et al., 1989). Itoh et al. (1986) found more compensation by flow for chemically-cured composites, which cure more slowly than light-cured materials. The surface of the lightcured composite cures first and stops any flow fromthe surface. This study confirmed that the flow in thin bonded composite layers did not allow a reduction of the shrinkage forces (Feilzer et al., 1989), since there were no significant differences among the slow-chemical-, the immediate-, and the delayed-light-curing modes. The whole contraction was directed in only one direction, perpendicular to the walls. The marginal adaptation at the composite inlay/cement interface after the load test showed no significant difference from the

Interface Cement/inlay:

Interface Tooth/Cement:

Interface Cementlinlay: Interface Tooth/Cement: Initial E MI Initial - After Load Cycles - After Load Cycles

E3 Initial - After Load Cycles

100 -

100-

80 -

80 -

60-

60-

40-

40-

20-

20-

E Initial - After Load Cycles

0-

0-

Total

Occl.

Approx. w Approx. w Cerv. E Cerv. D

Cerv. E

Cerv. D

Fig. 4-Bar diagram showing the mean percentage of "continuous margin" of group 3 (AP.H inlays, delayed-light-cured composite cement). Key as in Fig. 2.

Total

Occl.

Approx. w Cerv.

E

Approx. w Cerv. D

Cerv. E

Cerv. D

Fig. 5-Bar diagram showing the mean percentage of "continuous margin" of group 4 (CEREC Dicor inlays, delayed-light-cured composite cement). Key as in Fig. 2.

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ZUELLIG-SINGER et al.

initial results, except for group 1. Chemical curing alone resulted in a porous composite surface, which had a negative effect on the marginal adaptation. Roughening the cementing surfaces of immediately-cured composite inlays led to a high percentage with "continuous margin". The interface between glass ceramic and cement suffered more than the interface between composite and cement. Nathanson (1991) found a shear bond strength of 121 kg/cm2 for Dicor MGC cement to silanized and etched Dicor glass ceramic. This strength was not sufficient to resist the load completely. This pretreatment method is obviously not as good for Dicor as it is for feldspathic porcelain (Fett et al., 1991). The results for the composite inlays were comparable with those of previous studies (FUllemann and Lutz, 1988; Krejciet al., 1990c). In a similar in vitro study (Glauser, 1991), MOD cavities were prepared in extracted molars, and inlays were made with AP.H composite. The dentin was covered with PUB 2, and the inlays were cemented with the AP.H composite, which is light-cured. The restorations were then exposed to the same in vitro loading test as used in this study. The percentage of continuous margin" in dentin before the load cycling was already much lower compared with the percentage in this present study. After the load cycling, only 7.9% scored as 'continuous margin" compared with 38-41% in this study. Therefore, it can be concluded that the use of a dual-cured luting composite achieved better marginal adaptation in dentin than did a light-cured composite. The results found for the CEREC inlays confirmed previous studies (Bronwasseretal., 1991; Fettetal., 1991; Petersetal., 1991). Bronwasser et al. (1991) exposed the Dicor CEREC inlays to an in vitro test, which corresponded to only six months of clinical stress and the percentage of continuous margin" in dentin was 84%. Since this result is superior to the 61% achieved in this present study, the bond to dentin deteriorated further during the more extensive load test. So that meaningful conclusions can be drawn about the stability of the adhesion to dentin, the restorations should be exposed to a long-term load test. The search for a dentin adhesive that guarantees a continuous margin in dentin on an on-going basis must be continued.

Acknowledgments. We thank Mr. Sagesser, Ms. B. Sener, and Ms. J. Jenss for assistance with the laboratory tests. REFERENCES Adair PJ, Grossmann DG (1984). The castable ceramic crown. Int JPerio and Rest Dent 2:32-45. BronwasserP, MoermannWH, Krejci I, Lutz F (1991). Marginal adaptation of adhesive Cerec-Dicor-Inlays. In: Moermann WH, editor. International symposium on computer restorations. Berlin (Germany): Quintessence Publishing Co., 377-391. Buonocore MG (1955). A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res 34:849-853. Davidson CL, de Gee AJ (1984). Relaxation of polymerization contraction stresses by flow in dental composites. J Dent Res 63: 146-148. Davidson CL, de Gee AJ, Feilzer A (1984). The competition between the composite-dentin bond strength and the polymerization contraction stress. J Dent Res 63:1396-1399. FassbinderDJ, Burgess JO, Robbins JW, TheoboldWD (1989). Tensile bond

J Dent Res November 1992

strength of dental adhesives to dentin and enamel. Dent Mater 5:272276. FeilzerAJ, de GeeAJ, Davidson CL (1987). Settingstress incomposite resin in relation to configuration of the restoration. JDentRes 66:1636-1639. Feilzer AJ, de Gee AJ, Davidson CL (1989). Increased wall-to-wall curing contraction in thin bonded resin layers. J Dent Res 68:48-50. Fett HP, Moermann WH, Krejci I, Lutz F (1991). The effects of short bevels and silanization on marginal adaptation of computer-machined mesioocclusodistal inlays. Quint Int 22:823-829. Fillemann J, Lutz F (1988). Direktes kompositinlay. Schweiz Monatsschr Zahnmed 98:759-764. Glauser R (1991). Verschleiss und marginale adaptation von zwei neuen feinpartikelhybridkomposit-inlays in vitro (dissertation). Zurich (Switzerland): University of Zurich. Holz V, Bouillaguet S, Ciucchi B, Holz J (1991). In vitro study of proximal adaptation and seal of Cerec inlays. In: Moermann WH, editor. International symposium on computer restorations. Berlin (Germany): Quintessence Publishing Co., 405-416. Itoh K, Yanagawa T, Wakumoto S (1986). Effect of composition and curing type of composite on adaptation to dentin cavity walls. Dent Mater J 5:260-266. JensenME, ChanDCN(1985). Polymerization shrinkage and microleakage. In: Vanherle G, Smith DC, editors. International symposium on posterior composite resin dental restorative materials. Utrecht (The Netherlands): Peter Szulc Publishing Co, 243-262. Krejci I, Albertoni M, Lutz F (1990b). In-vitro-testverfahren zur evaluation dentaler restaurationssysteme, 2. Zahnbiursten-zahnpastaabrasion und chemische degradation. SchweizMonatsschrZahnmed 100:1164-1168. Krejci I, Picco U, Lutz F (1990c). Dentinhaftungbei zahnfarbenen adhasiven MOD-sofortinlays aus komposit. Schweiz Monatsschr Zahnmed 100:1151-1159. Krejci I, Reich T, Lutz F, Albertoni M (1990a). In-vitro-testverfahren zur evaluation dentaler restaurationssysteme. 1. Computergesteuerter kausimulator. Schweiz Monatsschr Zahnned 100:953-960. Lutz F, Krejci I, Luischer B, Oldenburg TR (1986). Improved proximal margin adaptation ofclass II composite resinrestorations by use oflightreflecting wedges. Quint Int 17:659-664. McCulloch AJ, Smith BG (1986). In vitro studies of cuspal movement produced by adhesive restorative materials. Br Dent J 161:405-409. Moermann WH, Brandestini M, Lutz F, Barbakow F (1989). Chairside computer-aided direct ceramic inlays. Quint Int 20:329-339. Nathanson D (1991). Factors in optimizing the strength ofbonded ceramic restorations. In: Moermann WH, editor. International symposium on computer restorations. Berlin (Germany): Quintessence Publishing Co., 51-59. Peters A, Bieniek KW (1991). SEM examination of the marginal adaptation of computer machined ceramic restorations. In: Moermann WH, editor. International symposium on computer restorations. Berlin (Germany): Quintessence Publishing Co., 365-371. Phillips DS (1978). Single classification of ANOVA-independent data. In: Freedman J, Lindsey G, Thompson F, editors. Basic statistics for health science students. New York: W.H. Freedman and Co., 98. Sheth PJ, Jensen ME, Sheth JJ (1989). Comparative evaluation of three resin inlay techniques: microleakage studies. Quint Int 20:831-836. Shortall AC, Baylis RL, Baylis MA, Grundy JR (1989). Marginal seal comparisons between resin-bonded class II porcelain inlays, posterior composite restorations and direct composite inlays. Int J Prosthodont 2:217-223. Smith BG, Cardwell JE (1989). One visit ceramic restorations made at the chairside: the Cerec machine. Rest Dent 5:60-65.

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Effects of cement-curing modes on dentin bonding of inlays.

The aim of this in vitro study was to evaluate dentin adhesion after cementation of immediate direct "All Purpose" Hybrid (AP.H) composite inlays (Den...
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