Clinical long-term retention of etch-and-rinse and self-etch adhesive systems in non-carious cervical lesions

d e n t a l m a t e r i a l s 2 3 ( 2 0 0 7 ) 1101–1107

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Clinical long-term retention of etch-and-rinse and self-etch adhesive systems in non-carious cervical lesions A 13 years evaluation ¨ ˚ Jan W.V. van Dijken ∗ , Karin Sunnegardh-Gr onberg, A. Lindberg ˚ Umea˚ University, 901 87 Umea, ˚ Sweden Department of Odontology, Dental School Umea,

a r t i c l e

i n f o

a b s t r a c t

Article history:

Objectives. The aim of this study was to evaluate the clinical long-term retention to dentin

Received 13 May 2006

of seven adhesive systems.

Received in revised form

Methods. A total of 337 Class V restorations of three three-step etch-and-rinse, one two-step

4 October 2006

etch-and-rinse and three self-etch adhesive systems were placed in non-carious cervical

Accepted 7 October 2006

lesions without intentional enamel involvement. The restorations were evaluated at baseline and then every 6 months during a 13 years follow-up. Dentin bonding efficiency was determined by the percentage of lost restorations.

Keywords:

Results. During the 13 years, 275 restorations could be evaluated. The cumulative loss rate at

Adhesion

13 years was 60.3%, with significant different failures rates for the different systems varying

Clinical

between 26.3 and 94.7%. Three materials fulfilled the ADA 18 months full acceptance criteria.

Dental material

Three systems showed already at 18 months or earlier catastrophical debonding rates. The

Etch

annual failure rates for the three-step etch-and-rinse systems were: Allbond 2 4.1%, Clearfil

Resin

LB 2.0% and Denthesive 7.3%. For the two-step etch-and-rinse Gluma 2000 6.5%, and for the

Restoration

self-etch systems ART 3.2%, Denthesive 2 5.7% and PUB 3 4.5%

Self-etch

Conclusion. A continuous degradation of the resin–dentin bond was observed for all bonding systems during the follow-up expressed by the increasing loss rates. A wide variation of dentin bonding effectiveness was seen between the systems independent to adhesion strategy. © 2006 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

1.

Introduction

Adhesive techniques have been developed to such an extent that they are now involved in a large number of clinical procedures. The heterogeneous composition of dentin tissue, its hydrophilicity and the presence of a smear layer after cutting, makes it a more difficult substrate to bond to than enamel tissue. Earlier adhesive systems showed low laboratory bond strength and limited durability in vivo [1]. The introduction of amphyphilic monomers, dissolved in solvents such as water,

∗

acetone or alcohol, made the bond to dentin more reliable and improved clinical retention [2,3]. The monomers can infiltrate the moist dentin surface and create, after polymerization, a molecular entanglement network with the collagen fibrils. A high, micromechanical bond to the dental tissue can be obtained by formation of the so called hybrid layer. To predict the performance of adhesive systems, laboratory tests such as tensile or shear bond strength and microleakage tests are commonly used, which are easy and relatively cheap to perform [1]. Unfortunately, in vitro screening tests do not always

Corresponding author. Tel.: +46 90 7856034/6226; fax: +46 90 770580. E-mail address: [email protected] (J.W.V.v. Dijken). 0109-5641/$ – see front matter © 2006 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2006.10.005

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reflect the true behavior of a materials clinical performance and clinical testing remains therefore the ultimate proof of effectiveness [1,4]. A reduction in bond strength and morphological changes in the resin–dentin bond during storage in

water have recently been demonstrated [5–7]. A degradation of the demineralized dentin and depletion of collagen fibrils has been predicted leading to the reduction in bond strength over time [5,8,9]. Hashimoto et al. [10] confirmed recently the

Table 1 – Composition and handling of the bonding systems Adhesive system Allbond 2/

ART Bond/Brilliant

Clearfil Liner Bond/Clearfil Lustre

Denthesive/Charisma

Denthesive 2/Charisma

Gluma 2000/Pekafill

PUB 3/Prisma APH

Composition Conditioner: 32% phosphoric acid Primer: (A) 2% NTG-GMA (N-p-tolyl-glycine glycidyl methacrylate), photoinitiator. (B) 16% BPDM (biphenoldimethacrylate), photoinitiator; ethanol, acetone Bonding resin: (Dentin Enamel Bond): bis-GMA, UDMA, 2-HEMA Self-etching primer: (A) 1.6% maleic acid, NaF, water. (B) 36% HPMA (hydroxypropylmethacrylate), 6.2% polymethacrylic oligomaleic acid (PMA), 47% 2-HEMA, 9.8% water Bonding resin: 44% isopropylidenbis, 7% PMA (polymethacrylic oligomaleic acid), 49% DMA (dioxaoctamethylendimethacrylate), bis-GMA, TEGDMA Conditioner (CA agent): 10% citric acid, 20% CaCl2 , 6% colloidal silica thickener, water

Treatment C: 15 s, dry (wet bonding technique) P: apply five times, dry

Bisco, Schaumburg, Il, USA

B: apply, light cure 20 s P: 30 s, remove excess and dry 15 s

´ ¨ Coltene, Altstatten, Switzerland 9205522

B: brush 20 s and air thin, light cure 20 s

C: 40 s, rinse, dry

Primer (SA primer): 3% 5-NMSA (N-methacryloxyl-5-amino salicylic acid), ethanol Bonding resin: (Photo Bond): 10-MDP (10-methacryloxydecyl dihydrogen phosphate), bis-GMA, HEMA, photoinitiator Conditioner: 5% EDTA-(2 NaOH to pH 4.5)

P: 30 s, dry

Primer: (A) methacryloxyethylmaleate, ethanol. (B) 2-HEMA, phosphate, ethanol (pH 2.3) Bonding resin: highly filled dimethacrylate

P: 20 s, dry

Primer: (A) 2% maleic acid, water. (B) 82%HEMA, 3.6% maleic acid-mono-methacryloyl-oxy-propylester, 3.6% methacrylated polycarboxylic acid, TEGDMA, photoinitiator, stabilisator, 10% water Bonding resin (Adhesive Bond II): 43.5% bis-GMA, 7% maleic acid-mono-2-methacryloyloxyethyl, 48.5% TEGDMA, photoinitiator

Manufacturer

Kurary Co. Ltd., Osaka, Japan /Cavex, Holland Lot nr 41116

B: brush, air, light cure 20 s

C: 20 s, rinse, dry gently

B: brush, air blow, light cure 20 s P: 30 s, air blow, no light cure

Hereaus–Kulzer GmbH, Wehrheim, Germany primer: ChB22 bonding: 047

Hereaus–Kulzer GmbH, Wehrheim, Germany

B: 15 s, air blow, light cure 40 s

primer A:ChB24 B: ChB023 adhesive: ChB21

Conditioner (solution 1): oxalic acid 1.6%, aluminium nitrate 2.6%, glycine 2.7%; water (pH 1.3) Primer/adhesive (solution 2): N-methacryloyloxyethyl-N-methylformamide, bis-GMA, acetic acid, ethanol Primer: 30% 2-HEMA, 6% PENTA (dipentaerythrietol pentacrylate phosphonate ester), ethanol

C: 30 s, rinse 10 s, dry

Bayer Dental, Leverkusen, Germany 2014J

Bonding resin: 4.5% PENTA, 25% TEGDMA, HEMA, 0.5% glutaraldehyde, 50%UDMA; <1% photoinitiator

B: light cure 20 s

P/A: 30 s, gentle air blow

P: 30 s, dried 5-10 s

Dentsply, Konstanz, Germany primer:021991 adhesive: 050791

d e n t a l m a t e r i a l s 2 3 ( 2 0 0 7 ) 1101–1107

in vivo degradation of the resin–dentin bond and showed that exposed collagen fibrils were susceptible to hydrolytic degradation. Despite numerous studies have been conducted to evaluate the integrity of resin–dentin bond structures and strength, most of these experiments were performed in vitro and over short time periods. The clinical bonding effectiveness can be demonstrated in non-carious cervical lesions located mainly in dentin, in which no cavity preparation or macromechanical retention is used. Due to the rapid development of dental materials and the time necessary for clinical testing and to publish results, clinical trials are limited in number and follow-up time [11]. Most of these trials run between 6 months and 3 years. More information about the clinical performance of different bonding systems over a significant period of time is necessary [4,11]. The purpose of this study was to present the long-term clinical effectiveness of seven different, threeand two-step etch-and-rinse and two-step self-etch, adhesive systems in non-carious cervical lesions.

marginal discoloration, secondary caries and surface roughness. The evaluations were performed by the operator and at regular time intervals by other evaluators with a kappa agreement of 80%. Slightly modified USPHS criteria were used [12]. Only the retention evaluations are reported here. The clinical bonding effectiveness was determined by the percentage of lost restorations during the evaluation period. In this study only the retention data, which are relevant for the long-term evaluation of the bond are given. The Statistical Package for Social Sciences, Version 14.0 (SPSS, Chicago, USA) was used to process the data. Descriptive statistics were used to present the results. Cumulative retention failures were calculated by dividing the number of lost restorations at the recalls by the total number evaluated. Differences in distribution of the ratings between the adhesive systems for the investigated variables were statistically analyzed by the binomial test for independent samples [13].

3. 2.

1103

Results

Materials and methods

A total of 337 Class V restorations were placed in 119 patients (68 men and 51 women) with a mean age of 54.5 years (range 24–83). All patients attending the authors dental clinic at the ˚ Sweden, for whom treatment of nonuniversity of Umea, carious cervical lesions was indicated were included. Six adhesive systems were successively placed between October 1991 and October 1994, two at a time in a randomized way as they became available in different time periods. All restorations were placed in dentin lesions without any intentional enamel involvement, by one experienced operator who was familiar with adhesive dentistry. The following adhesive systems: three three-step etch-and-rinse systems: Allbond 2 (n = 57), Clearfil Liner Bond (n = 57), Denthesive (n = 44); one two-step etch-and-rinse system: Gluma 2000 (n = 48) and three twostep self-etch systems: ART Bond (n = 44), Denthesive 2 (n = 44), PUB 3 (n = 43) (Table 1). Before conditioning, the lesions were cleaned preoperatively from plaque and/or saliva if necessary. The adjacent gingiva was retracted by gingival retraction instruments or matrix bands when necessary to secure unrestricted contamination free access to the field [3]. No bevel was placed. Conditioning of the lesions was performed for the etch-and-rinse systems by applying 32% phosphoric acid, 10% citric acid/20% CaCl2 , 1.6%, oxalic acid/2.6% aluminium nitrate, or 5% EDTA and for the self-etching primers by the included 1.6 or 2% maleic acid and 6% PENTA (Table 1). Conditioning of the etch-and-rinse lesions was followed by thoroughly water spraying for 20 s, carefully air drying in order to maintain a moist dentinal surface following the wet-bonding technique to prevent collapse of unsupported collagen. Applying of adhesive and/or light curing was performed according to the manufacturers instructions (Table 1). The resin composite material, was applied in at least two increments using a selected resin composite instrument (Hu Friedy). Each increment was light cured for 40 s with a light-unit, which was controlled for good light-intensity once a week (Luxor, ICI, Macclesfield, UK; 400 mW/cm2 ). The restorations were evaluated at baseline and then every 6 months during 13 years with regard to marginal adaptation/retention, color match,

At the end of the follow-up, 275 restorations could be evaluated. During the 13 years, 21 patients with 62 restorations (Allbond 2 16, ART 15, Denthesive 6, Denthesive 2 9, Gluma 2000 11, PUB 3 5), could not be evaluated at all recalls due to moving of the patients (46), death (14) or prosthetic reasons (4). A cumulative number of 164 restorations (60.3%) was lost during the 13 year follow-up. For the three-step etchand-rinse systems Allbond 2 53.7%, Clearfil LB 26.3%, Denthesive 94.7%. For the two-step etch-and-rinse Gluma 2000 83.8%, and for the self-etch systems Denthesive 2 74.3%, ART 41.3%, PUB 3 57.9%. The annual failure rates for the threestep etch-and-rinse systems were: Allbond 2 4.1%, Clearfil LB 2.0%, Denthesive 7.3%. For the two-step etch-and-rinse Gluma 2000 6.5%, and for the self-etch systems ART 3.2%, Denthesive 2 5.7%, PUB 3 4.5%. Significant differences in loss rates were observed between the systems (p < 0.05). The following ranking was found between the clinical effectiveness of the systems with the best material mentioned first: Clearfil LB > ART > Allbond 2 = PUB 3 > Denthesive 2 = Gluma 2000 > Denthesive. The cumulative loss rates at the recall periods during the follow-up of the different restorative systems are shown in Fig. 1. No recurrent caries was observed or postoperative sensitivity reported.

Fig. 1 – Cumulative loss rates (%) of the bonding systems tested in Class V non-carious lesions during the 13 years follow-up.

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Table 2 – Reported retention rates of restorations placed with the bonding systems investigated in the present study Bonding

Reference/year

Allbond 2

Snuggs et al. 1992 [23] Ianzano & Gwinnett 1993 [24] Jordan & Suzuki 1993 [25] Dickinson 1994 [26] Tyas 1994 [31] Tyas 1996 [32] Schwartz et al. 1995 [27]

6 months 1 year 6 months 6 months 14 months 3 years 1 year

Hermesch et al. 1996 [28]

2 years

Smith et al. 1996 [29] McCoy et al. 1998 [33] van Dijken [30]

2 years 3 years 5 years

20 1.4 0 0 30.4 26 8.2 4.8 14 6 8 28 21

Cowan 1995 [34] Tyas 1996 [35] McCoy 1998 [33]

1 year 2 years 3 years

3 5 15

Barkmeier et al. 1996 [36] van Meerbeek et al. 1996 [37]

3 years 3 years

Mandras et al. 1997 [38] Alhadainy & Abdalla 1996 [39]

1 year 3 years 3 years

Tyas 1994 [31] Tyas 1996 [32]

14 months 3 years

57.2 59

Jordan et al. 1993 [42] van Meerbeek et al. 1994 [44]

2 years 2 years

van Meerbeek et al. 1996 [37]

3 years

Bayne et al. 1995 [45]

1 year

¨ Horsted-Bindslev et al. 1996 [43] Alhadainy & Abdalla 1996 [39]

1 year 3 years 3 years

2.5 34 35 33 38 36 47 3.8 12 15

Jordan & Suzuki 1993 [25] Duke et al. 1994 [47]

1 year 2 years

Robbins et al. 1995 [50]

3 years

Schwartz et al. 1992 [48] Schwartz et al. 1995 [27] Barkmeier et al. 1996 [36] Hermesch et al. 1996 [28] Sturdevant et al. [49] McCoy 1998 [33]

1 year 1 year 3 years 2 years 3 years 3 years

ART

Clearfil LB

Years of evaluation

Loss of retention (%)

7.3 2 4 1.7 7.3 0

Comments A Bevel

A: 10% H3 PO4 enamel/dentin 32% H3 PO4 enamel Abstract, 10% H3 PO4 enamel/dentin 32% H3 PO4 enamel A

A: enamel etch Enamel etch H3 PO4 A Bevel, etch No bevel

Denthesive

Denthesive 2 Gluma 2000

PUB 3

3 0 0 7.5 2.5 0 3.1 7.3 12 7 21

Long bevel Bevel, etch No bevel Bevel, etch No bevel A: non-sclerotic lesions sclerotic lesions

Bevel, etch No bevel A: no bevel bevel, etch A: bevel, etch enamel A: bevel, enamel etch A A Enamel etch Enamel etch H3 PO4

A, reported as abstracts only; bevel, restorations are placed in lesions there the incisal enamel was beveled and/or etched with phosphoric acid.

4.

Discussion

Traditional mechanical methods of retaining restorative materials have successively been replaced by adhesive methods during the last decennia. Enamel–resin bonds, when produced after acid etching with phosphoric acid have shown to be satisfactory and stable over time [14–16], but adhesion to dentin have shown to be much more complex. Adhesion technology, progressing significantly and rapidly during the 1990s,

included several new and modified methods to bond to dentin. In the early 1990s, the selective enamel-etching was replaced by a total-etch concept in etch-and-rinse and self-etch adhesive systems showing improved bond strength in vitro [1]. In the oral environment factors like moisture, physical stresses, chewing habits, dietary components and changes in temperature and pH acting simultaneously may accelerate degradation of the adhesive bonds, or result in catastrophic failures or even fatigue failures. Few in vitro bonding studies mimic more than one of these in vivo degradation involved factors

d e n t a l m a t e r i a l s 2 3 ( 2 0 0 7 ) 1101–1107

involved in the oral environment to disclose its effect on degradation. Therefore, once an adhesive performs well in vitro a clinical trial is necessary to evaluate its clinical effectiveness. The biomaterial–tooth interfaces are despite good initial bond strength subjected to mechanical as well as chemical degradation. Mechanically by occlusal forces and chemically by hydrolytic degradation of the exposed collagen fibrils and plasticizing of the polymer matrix. A reduction of the bond durability is the result of the ingression of water. Several in vitro studies and also a few in vivo ones observed that dentin bond strength declines over time [5,10,16–19]. Hashimoto et al. [20] found a 67% drop in micro-tensile strength between 24-h and 1-year aged specimens. Debonding after 6 months and 5 years occurred primarily in the top and the bottom of the hybrid layer [5,19]. The present clinical followup study confirms degradation of the dentin–resin bond over longer time periods expressed by a continuous increasing loss rate of restorations observed for all bonding systems tested. The rapid progression of adhesive materials during the recent 20 years has resulted in a situation where many adhesive systems have been replaced by modified successors, which were claimed to be better without clinical validation. Long-term trials have been limited in number since they require several years with regular recalls. In a review of Class V clinical trials published between 1998 and 2004, only 40% of 85 trials were published as peer reviewed articles [11]. Most of the trials were 3 years or shorter follow-ups and only a few studies reported observation times up to 5 years and longer. The present study is to our knowledge the first longer than 10-years follow-up of Class V resin based restorations placed in non-carious cervical lesions. The latest guidelines of the American Dental Association (Dental and enamel adhesive materials: ADA, Council on Dental Materials, Instruments, and Equipment, 1994) for submission of dentin and enamel adhesive materials require for provisional acceptance that no more than 5% of the restorations have been lost and not more than 5% of the restorations may show microleakage at the 6 month recall. To obtain full acceptance, the cumulative incidence of clinical failures in each of two independent clinical studies has to be lower than 10% lost restorations and 10% microleakage after 18 months. No long-term retention figures are required. Two of the three-step etch-and-rinse and one self-etch system evaluated fulfilled both the provisional and full acceptance. A second self-etch system fulfilled the 6 months criteria but not the 18 months ones. On the other hand, three of the other systems tested, one three-step and one two-step etch-and-rinse and one self-etch system did not fulfil the provisional and full acceptance criteria. They showed already at 6 and 18 months very high loss rates 20–23 and 36–58%, respectively. Marketing of these systems is really questionable. In vitro a discrepancy has been reported between bond values of the same bonding system in different studies [1,21]. In particular, the skill and experience of the operator is a source of variability in the results. In the present study all bonding systems were handled and restorations performed by the same dental team, in order to decrease the effect of the operator factor. This allows ranking of the systems tested but does not give information about variations in durability of the systems due to operator variability. The bonding systems

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evaluated used different mechanism of adhesion. One group of adhesives aimed to remove completely the smear layer (Allbond 2, Clearfil LB, Denthesive and Gluma 2000), while the other ones dissolved the smear layer rather than remove it and incorporated it in the hybrid layer (ART, Denthesive 2 and PUB 3) [4]). The acids used, phosphoric acid, citric acid, oxalic acid and maleic acid, vary in concentrations and acidity. Controversy have been reported about the etching efficiency of weaker acidic alternatives on enamel [22]. However, in the present study, the adhesive systems were tested in Class V non-carious lesions, there most of the bonding surface was dentinal tissue, while only a small incisal margin could consist of enamel. These surfaces are ideal to test clinical dentin bonding because they are widely available [11]. The three-step etch-and-rinse system Allbond 2 has been considered during many years as the golden standard of adhesive systems. It fulfilled in the present study the full acceptance ADA criteria and showed an annual failure of 4.1% during the study. A high retention rate was observed in short time evaluations [23–30], while other studies showed unacceptable high loss rates already after 1–2 years follow ups [31–33] (Table 2). The variability in clinical performance have been explained by the technique sensitivity of the acetone solvent used in the system [11]. Two other adhesives in this study showed better durability with annual loss rates of 3.2% (ART) and 2.0% (Clearfil Liner Bond). The ART adhesive system, a precursor of the today’s popular self-etch systems, required a selective etching of the enamel margins, which was not performed in the dentin lesions used in this study. It revealed low loss rates in short time studies, 5% after 2 years (no enamel etch), and 15% at 3 years (with enamel etch) [33–35]. The most favorable results in the present study were found for the three-step etch-and-rinse system Clearfil Liner Bond, which used a 10% citric acid/20% CaCl2 conditioner. Excellent results with the system were obtained in several up to 3 years studies confirming our results [36–39]. However, no longer time studies have been reported. Only one study have been reported concerning the third three-step etch-and-rinse system studied, Denthesive. Confirming the poor initial bonding effectiveness of the system, Tyas and van Dijken reported a 59% loss rate at 3 years, there most of the failures occurred during the first 6 months (50%) [30,31]. The Denthesive system used a EDTA conditioner, which was claimed to dissolve the smear layer allowing a chemical bond between the adhesive primer and the dentinal collagen and calcium. Low bond strength between 3.4 and 10.7 MPa have been reported for the adhesive [40,41]. The successor of the same manufacturer had almost the same name, Denthesive 2, but was actually a totally different self-etch system, containing a 2% maleic acid in the primer. A high initial loss rate was found for this system in contrast to the ART system, which used the same acid in the primer. Also the third self-etch system evaluated, Gluma 2000, used a name reminding of the manufacturer’s previous system (Gluma) but contained totally different ingredients with an oxalic acid/aluminium nitrate conditioner. Favorable results with a loss rate of 2% at 2 years have been reported in lesions with a long prepared bevel [42]. A 12% debonding at 3 years was [43] in large contrast to very unfavorable results in 1–2 years follow-ups with more than 30% loss rates [44–45]. van Meerbeek et al. [37] explained the poor results of the simplified

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system by the direct placement of the RC over the uncured adhesive, which may decrease the bond strength significantly [46]. Bonding systems using nitric acid-containing conditioners have performed much less effectively as shown by their high clinical loss rates [3]. The self-etch system PUB 3 has shown low debonding in studies up to 2 years in many studies in lesions with beveled enamel margins, but also in one study without intentional beveling [25,28,36,47–49]. A 3-year follow up showed a progressively degradation of the bond during the last year [50]. This was confirmed in the present study showing an increased loss rate after 3 years clinical service. It can be concluded that the initial efficacy, as measured by clinical retention, of several systems evaluated was acceptable, while three systems showed early catastrophic failure rates. All systems showed a continuous degradation of the bond with a wide variation, which was independent of the adhesion strategy.

Acknowledgment This study was supported in part by the County Council of ¨ Vasterbotten.

references

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