J. Dent. 1991: 19: 369-372

369

Microleakage veneers*

in porcelain

laminate

A. [email protected] and L. [email protected](jlu Department

of Prosthodontics,

Faculty of Dentistry,

University

of Ankara, Turkey

ABSTRACT The effectiveness of two dentine-enamel bonding agents has been investigatedin vitro when used together with an untilled, low viscosity resin in eliminating the microleakage of porcelain laminate veneers. The restoration margins were located below and above the amelocemental junction of extracted maxillary central incisors. The bonded specimens were thennocycled and investigated for microleakage by employing a standard dye penetration technique. Leakage was scored at the cervical and incisal margins. Tenure was found more effective than Creation 3 in 1 in preventing leakage at both the cervical enamel and dentine/composite lute interfaces. With Tenure dentine bonding agent, the leakage observed at the cervical dentine/composite lute interface was found to be similar to that observed at the cervical enamel/composite lute interface. Sealing of finished veneer margins reduced the leakage at all interfaces. KEY WORDS: .I. Dent. 1991)

1991;

Microleakage, 19: 369-372

Correspondenceshouldbe Beqevler, Ankara, Turkey.

Veneers, Porcelain (Received

9 November

1990:

reviewed

22 February

addressed to: Dr L. [email protected], Ankara hiversitesi,

1991;

accepted

1 June

Dis Hekimliai Fakiiltesi, 06500

INTRODUCTION

MATERIALS AND METHODS

Microleakage may lead to the failure of porcelain laminate veneers. Differences between the coefficient of thermal expansion of tooth tissues and dental restoratives and the curing shrinkage of luting agents may contribute to this leakage (Craig, 1989; Tjan et al., 1989). Leakage around enamel-contained veneers may be minimized by acid etching of enamel. However, in cases in which the preparation includes dentine, leakage may only be controlled by the use of dentine bonding agents (DBA) capable of effecting a strong bond between dentine and composite resin (Asmussen, 1985). ‘Sealing’ procedures, involving the application of unfilled low viscosity resin around the margin of the finished and polished restoration (Garcia-Godoy and Malone, 1987; Kemp-Scholte and Davidson, 1988), may also be of assistance. The purpose of the present in vitro study is to evaluate the effectiveness of two dentine-enamel bonding agents and a sealing procedure in limiting the marginal leakage of porcelain laminate veneers with cervical margins in enamel and dentine.

Forty recently extracted intact human maxillary central incisors were selected for this investigation. The teeth were placed in 10 per cent neutral buffered formalin at room temperature immediately after extraction, and thereafter kept wet except during bonding procedures. As reported in a related study (Zaimoglu et al., 1991), two preparations, one contained in enamel and the other extending into dentine beyond the amelocemental junction, were cut in equal numbers of teeth. The mesial and distal margins of the preparations were extended to the contact areas. Incisal reduction of 0.5 mm was included to create an incisal overlap. Following preparation, the teeth were divided at random into eight groups each of five teeth (Table I). Impressions of the preparations were taken using Hi-Ceram Duplicating Paste (Vita Zahnfabrik, Bad Stickingen, Germany), and refractory dies were prepared (Hi-Ceram Refractory Die Material, Vita Zahnfabrik). Using standardized laboratory procedures Vitadur N (Vita Zahnfabrik) porcelain laminate veneers were fired and glazed on the refractory dies. The internal surfaces of the veneers were etched by means of a 60-s application of 40 per cent hydrofluoric acid (Riedel-de Hgen AG,

*Presented at the 78th Annual World Dental Congress of the FDI, Singapore. @ 1991 Butterworth-Heisnemann Ltd. 03OO-5712/91/060369-04

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J. Dent.

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Table 1. Experimental Experimental groups

groups and restorative

procedures

Position of cervical margin

Dentine/enamel bonding agent

lncisal to the amelocemental junction

Creation 3 in 1 Creation 3 in 1 Tenure Tenure

Apical to the amelocemental junction

Creation 3 in 1 Creation 3 in 1 Tenure Tenure

Sealing

Tab/e II. Mean (+ s.d. of mean) leakage scores for the enamel-contained Experimental woum

n

A B C D

5 5 5 5

Interface

1

0.50 + 0.32 1.80 + 0.20 0.10~0.10 0.70+0.20

Interface

2

0.30 * 0.20 0.50 + 0.22 0.10~0.10 0.50,0.16

Interface

0.00 + 0.00 0.50 + 0.22 o.oo+-0.00 0.20+0.12

Interfaces: 1, cervical enamel/composite resin; 2, porcelain/composite incisal enamel/composite resin; 4, porcelain/composite resin incisally.

Germany). Before bonding, porcelain conditioner (citric acid) and a silane coupling agent, Cerinate Prime (DenMat Corp., Santa Maria, CA, USA) were applied to the fitting surfaces of the veneers. Two different bonding agents (Creation 3 in 1 and Tenure) were used in experimental groups as detailed in Table I. Before the application of Creation 3 in 1, the enamel of the preparations was etched with a 37 per cent phosphoric acid gel for 60 s and then washed and thoroughly dried. Before Tenure application the enamel margins of the preparations were etched for 15 s. A low viscosity dual initiated hybrid composite, Ultra-Bond, was applied to the filling surfaces of the laminate veneers. After seating each veneer, excess resin was removed from the margins with the tip of a brush. The composite resin was light cured using four 30-s light applications (Optilux 50, Demetron Research Corp., USA). The light guide tip was placed over the incisal area of the restoration for the first 30 s and then directed from cervical, mesial and distal surfaces for 30 s each. The manufacturer’s recommendations on finishing procedures were followed. The restorations were finished wet with carbide finishing burs (790-9902, Densco Ltd, Denver, CO, USA) after 15 min. A porcelain laminate polishing paste (Den-Mat Corp.) was applied with a rubber wheel (except in groups A, C, E and G). To investigate the effect of a resin sealing procedure on marginal leakage, the margins of the veneers in groups A C, E and G were acid etched (Kemp-Scholte and Davidson, 1988) for 10 s immediately following finishing and the tooth-veneer junction was sealed with an untilled resin (Visar-Seal, Den-Mat Corp.) and light cured for 20 s. The bonded specimens were stored in distilled water at 37 “C for 14 days. These were then sealed with two coats of nail varnish to within 1 mm of the margins of the

3

veneers

Interface

4

0.00 + 0.00 0.30 + 0.12 0.00~0.00 O.lO~b.10 resin cervically; 3.

restorations and then subjected to 100 temperature cycles, each cycle consisting of 15 s at 37°C 15 s at 5°C 15 s at 37 “C and 15 s at 55 “C. After this procedure the teeth were placed in an 0.5 per cent aqueous solution of basic fuchsin dye for 24 h. The teeth were then retrieved, the varnish was removed and the teeth were lightly pumiced to remove superficial dye. Each tooth was sectioned longitudinally in a faciolingual direction through the centre of the veneer. The microleakage was evaluated at the following four interfaces (Fig. I): 1. 2. 3. 4.

The cervical tooth/composite resin interface. The cervical porcelain/composite resin interface. The incisal enamel/composite interface. The incisal porcelain/composite resin interface (Tjan et al., 1989).

The presence of dye was scored with the aid of a stereomicroscope (Wild M3Z Stereozoom Microscope, Wild Heerbrugg Ltd, Heerbrugg, Switzerland) at X 40 magnification as follows: no penetration of dye (0); penetration of dye up to one-fifth (1) two-fifths (2) threefifths (3) and four-fifths (4) of the cervical or incisal margin; penetration of dye along the entire cervical or incisal margin (5). Two examiners scored the specimens independently and a consensus score was obtained in the event of any disagreement. Mean scores were calculated for each group and analysed using three-way analysis of variance. RESULTS The mean leakage scores for the interfaces in the enamelcontained porcelain laminate veneers are detailed in Table II, and the mean leakage scores for the interfaces in

Zaimo#u

and L. [email protected]:

Microleakage

of feneers

371

Porcelain Laminate veneer

Y\ 5

Composite

4

3

2

0

1

luting agent q Fig. 7. Details of the leakage scoring system.

the porcelain laminate veneers with cervical margins extended apical to the amelocemental junction are set out in Table III.

Fig. 2 ‘. The cervical margin of a group C specimen which exhibiits no leakage.

DISCUSSION From the results, it is apparent that marginal leakage scores may be found to be higher beneath laminate veneers with cervical margins on root dentine. Also according to results, the use of the oxalate dentine bonding agent Tenure resulted in less leakage at the cervical tooth/composite lute interface compared with the use of a phosphate ester enamel/dentine bonding agent, Creation 3 in 1. In addition, by the use of this system, the leakage scores obtained beneath laminate veneers with the cervical margin below the cementoenamel junction approximated the mean scores for the enamel-contained veneers. If a comparison is made between these two agents, Tenure was found to be more effective in reducing microleakage at the cervical composite lute/enamel interface. It is suggested, from the results, that the sealing procedure is effective along all margins in preventing marginal leakage (Figs 2 and 3). The result is consistent

Fig. 3. Dye penetration (score 1) at the dentine/composite interface in an unsealed porcelain laminate veneer bonded with the use of Creation 3 in 1 bonding agent.

with several previous reports concerning the marginal seal of composite restorations (Garcia-Godoy and Malone, 1987; Kemp-Scholte and Davidson, 1988; Tjan et al., 1990). Although it is claimed that untilled resin sealant

Table 111.Mean (k s.d. of mean) leakage scores for the veneers with cervical margin apical to the amelocemental junction Experimental groups E : H

n

2 5 5

Interface

1

1.60 AZ0.43 3.60 + 0.24 O.lOfO.10 1 .lO rt 0.24

Interface

2

0.30 rfr 0.20 0.60 f 0.24 0.10~0.10 0.20 & 0.12

Interface

3

0.10 f 0.10 0.60 + 0.40 0.10~0.10 0.20 * 0.12

Interfaces: 1, cervical enamel/composite resin; 2, porcelain/composite incisal enamel/composite resin; 4, porcelain/composite resin incisally.

Interface

4

0.00 + 0.00 0.40 + 0.24 0.10~0.10 0.10 * 0.10 resin cervically: 3,

372

J. Dent.

1991;

19: No. 6

shows a retention of 80 per cent after 3 years (Craig, 1989), further investigation of retention under mechanical forces and marginal discolouration of sealing materials used at the margins of porcelain laminate veneers is needed. It may be concluded that microleakage beneath laminate veneers could be considered to be inevitable, but the amount is affected by the type of dentine-enamel bonding agent and by resin sealing of the veneer following finishing.

References Asmussen E. (1985) Clinical relevance of physical, chemical and bonding 61-73.

properties

of composite

resins. Oper. Dent 10,

Craig R. G. (1989) Restorative Dental Materials, 8th edn. St Louis, C.V. Mosby. Garcia-Godoy F. and Malone W. F. P. (1987) Microleakage of posterior composite restorations after rebonding. Compend. Contin. Educ. Dent 8, 606-610. Kemp-Scholte C. M. and Davidson C. L. (1988) Marginal sealing of curing contraction gaps in class V composite resin restorations. J. Dent. Res. 67, 841-845. Tjan A. H. L., Dunn J. R. and Sanderson I. R (1989) Microleakage patterns of porcelain and castable ceramic laminate veneers. J. Prosthet. Dent. 61,276-282. Tjan A. H. L., Tan D. E. and Grant B. E. (1990) Microleakage of composite restorations rebonded with various resin systems. J. Dent. Res. 69, 363 (abstr. 2035). Zaimoglu A, Karaagaqhoglu L. and ijqta$lf S. (1991) Influence of porcelain material and composite luting resin on microleakage of porcelain veneers. J. Oral Rehabil. 19, (in press).

Book Reviews AIDS and the Mouth. D. Greenspan, J. S. Greenspan, M. Schiodt and J. J. Pindborg. Pp. 204. 1990. Copenhagen, Munksgaard. Hardback, 450 DK. Perspectives on Oral Manifestations of AIDS. P. B. Robertson and J. S. Greenspan. Pp. 216. 1988. Littleton, USA, PSG (distributed by Wolfe Medical). Softback, f 29.50.

Perspectives on Oral Manifestations of AIDS is a transcript of the proceedings of a symposium held in January 1988, in California. Thirteen of the 15 contributors are based in the USA, and each presented a resume of his previous and current research. Tests for HIV infection and pathogenesis of AIDS are well explained and followed by papers on the oral manifestations. The sections on oral candidiasis and periodontal disease are particularly good and include excellent clinical photographs. Dental management of patients is well covered with the rationale behind selection of different therapeutic agents well explained. The risks of occupational transmission are comprehensively reviewed with emphasis on professional and ethical responsibilities. The book is a useful collection of papers by authors distinguished in their own fields and each paper is followed by a comprehensive list of references. It is interesting to see how the American dental profession is responding to the challenge of HIV, and the ethical questions posed will have increasing significance to those in the UK and elsewhere in the world. In AIDS and the Mouth the authors have updated their 1986 book AIDS and the Dental Team with the aim of covering recent developments and giving more details of non-oral aspects of HIV infection. The general format however has not been changed. The first part begins with definitions and classifications of AIDS and HIV-associated disease, and then deals with epidemiology, transmission and structure of the human immunodeficiency viruses

with brief details on culture, immunological assays and animal models. The information is up to date with a comprehensive list of references at the end of each chapter. The chapters ‘Human immune deficiency viruses’ and ‘Tests for HIV infection’ are particularly interesting and well written. The second part begins with a brief chapter on the natural history of HIV infection before dealing, in detail, with the oral manifestations. The latter information is organized into chapters on fungal, bacterial and viral infections; neoplasms; neurological manifestations and oral manifestations of unknown aetiology, and includes some excellent clinical photographs. The account of HIV-associated periodontal diseases is particularly good, and the chapter on treatment includes a table summarizing the diagnosis and management of oral HIV disease. The third part of the book deals with infection control, beginning with a comprehensive review of the risk of health care workers. Though easy to read, interesting and informative, several aspects of the book are disappointing. Systemic manifestations of HIV infection are not adequately covered; for example, there is little information on the neurological manifestations apart from the brief account of neuropathies of the trigeminal and facial nerves. Much of the information is anecdotal with little development of the discussion. There are very few photomicrographs and those included are rather poor. The constant use of abbreviations is irritating, and the layout is such that interpretation of figures and tables is not always easy. It is unfortunate that the small number of typographical errors include a confusing misprint in the units of measurement in one instance. The photograph of the ‘receptacle for waist’ is a more amusing error. However, despite these criticisms, the book does provide a good outline of the HIV problem, and it deals satisfactorily with the oral manifestations. In addition, it is a useful source of references for the reader wanting further information on other aspects of the disease. J. A. Woolgar

Microleakage in porcelain laminate veneers.

The effectiveness of two dentine-enamel bonding agents has been investigated in vitro when used together with an unfilled, low viscosity resin in elim...
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