d e n t a l m a t e r i a l s 3 0 ( 2 0 1 4 ) e245–e251
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A randomized controlled three year evaluation of “bulk-filled” posterior resin restorations based on stress decreasing resin technology Jan W.V. van Dijken a,∗ , Ulla Pallesen b a b
Dental School, Faculty of Medicine, Umeå University, Umeå, Sweden Institute of Odontology, Faculty of Health Science, University of Copenhagen, Denmark
a r t i c l e
i n f o
a b s t r a c t
Article history:
Objective. The objective of this randomized controlled prospective clinical trial was to
Received 10 January 2014
evaluate the efficacy of a flowable resin composite (SDR) bulk fill technique in posterior
Received in revised form
restorations and to compare it intraindividually with a conventional 2 mm resin composite
16 April 2014
curing technique in a 3-year follow up.
Accepted 21 May 2014
Materials and methods. Thirty-eight pairs Class II and 15 pairs Class I restorations were placed in 38 patients with a mean age of 55.3 years (range 32–87). Each patient received at random at least two, as similar as possible, Class II or Class I restorations of two restorative techniques.
Keywords:
In all cavities a single step self-etch adhesive (Xeno V) was applied. In one of the cavities
Adhesive
of each pair, a flowable resin composite (SDR) was placed, in bulk increments up to 4 mm
Bulk fill
as needed to fill the cavity 2 mm short of the occlusal cavosurface. The occlusal part was
Clinical
completed with a nano-hybrid resin composite (Ceram X mono) layer. In the second cavity,
Resin composite
the hybrid resin composite was placed in 2 mm increments. The restorations were evaluated
Self etch
using slightly modified USPHS criteria at baseline and then yearly during 3 years. Caries risk and parafunctional habits of the participants were estimated. Results. After three years, 76 Class II and 28 Class I restorations could be observed. One molar resin composite-only tooth showed post-operative sensitivity during 3 weeks for temperature changes and occlusal forces. Two failed Class II molar restorations in the resin composite-only group were observed during the first year, one cusp fracture and one resin composite fracture. An annual failure rate of 1.3% was found for the resin composite only restorations and of 0% in the bulk-filled restorations (n.s.). Ten participants were estimated as having high caries risk and eleven showed active bruxing habits. Significance. The 4 mm bulk-fill technique with the flowable resin composite SDR showed highly clinical effectiveness, which was comparable during the 3-year follow-up with the 2 mm resin composite layering technique. © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
∗ Corresponding author at: Department of Odontology, Dental School Umeå, Umeå University, 901 87 Umeå, Sweden. Tel.: +46 90 7856047/135074. E-mail address: [email protected] (J.W.V. van Dijken). http://dx.doi.org/10.1016/j.dental.2014.05.028 0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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1.
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Introduction
In many countries resin composites do have almost totally replaced amalgam as restorative in posterior teeth [1]. The majority of the resin composites are today methacrylate based and cure by means of a free radical polymerization. During curing of the monomers, a network of polymers is formed which becomes rigid due to increasing cross-linking of the polymer chains. In the post-gel contraction phase, the shrinkage manifests as a strain on the resin composite and cavity walls which may result in interfacial deficiencies, enamel fractures, cuspal movements and cracked cusps. Gap formation may increase the potential for post-operative sensitivity, microleakage and secondary caries. The resulting stress depends on factors like: resin monomers involved, filler technology, gel point, C-factor of the cavity, elastic modulus of the resin composite, curing technique and conversion rate. Several clinical techniques have been suggested to minimize interfacial stress formation like decreasing the C-factor by using selected layering technique, to use stress reducing curing techniques such as the soft start curing and placement of stress absorbing intermediary layers in sandwich techniques [2–8]. Extensive efforts have been made during the last years to develop low shrinkage materials by changes in filler technology and monomer chemistry [9,10]. The intensity of the curing light decreases when the light is transmitted through the resin composite. The conversion rate in the resin composite restoration will decrease at increasing distance from the curing light and by decreased energy [11,12]. A lower conversion rate will influence the physical properties of the resin composite and increased elution of monomers have been reported [13,14]. To prevent clinical failures because of a non-optimal cured resin composite and decrease the elution of non-reacted monomers, the resin composite restoration is cured in increments. The maximal incremental thickness which provides adequate light penetration and polymerization has been generally defined as 2 mm [15,16]. The layering technique makes the restorative procedure time consuming, voids may be included and the failure risk increases [17]. The main concern regarding applying thicker increments is whether the resin composite cures enough in the deeper parts to obtain acceptable mechanicical, physical and biocompatible properties. Recently, a new class of resin composite materials the bulk-fill resin composites have been introduced. During the early 2000th a first approach to apply posterior resin composite restorations with thicker layers was introduced as a rather high transluscent resin composite [18]. More recently an on stress decreasing resin technology based flowable resin (SDR) was introduced to be used in 4 mm layers as open or closed dentin replacement beneath a conventional resin composite [19]. The rheology of the material was suggested to be improved allowing improved adaptation to the cavity walls. A polymerization modulator, a patented urethane di-methacrylate, is chemically embedded in the resin backbone of the resin composite. This results in a slower modulus development, allowing for stress reduction without decreasing conversion rate [19,20]. In vitro studies showed that the application of fewer and thicker increments could be equally successful as the conventional layering technique [20–23]. Ilie and Hickel showed that SDR showed the
lowest shrinkage stress and shrinkage rate in comparisons to regular methacrylate resin composites [20]. The degree of cure and mechanical properties were shown to be constant within the 4 mm increment at a curing time of 20 s [24]. The bulk-fill material exhibited an acceptable creep deformation and within the range exhibited by other resin composites [17]. Cuspal deflections were significantly reduced when a single increment of the flowable resin composite was used as dentin replacement base to restore Class II cavities [22]. No clinical study has yet reported the clinical effectiveness of the SDR flowable base and its claimed 4 mm thick layer curing. The aim of this study was to investigate in a randomized controlled intraindividual comparison the clinical effectiveness of the flowable resin composite placed with maximally 4 mm increments (bulk fill) in large and deep Class I and Class II cavities. SDR is used to fill the cavity 2 mm short of the occlusal cavosurface and is then covered with a nano-hybrid resin composite. The SDR restoration is compared intraindividually with a nano-hybrid resin composite-only restoration placed and cured with a 2 mm layering technique. In both the experimental- and resin composite-only control cavity a onestep self-etching bonding system was used. The hypothesis tested was that bulk-fill restorations show similar durability as the resin composite-only restorations
2.
Material and methods
During may-october 2010, all adult patients attending the Public Dental Health Service clinic at the Dental School Umeå who needed one or two pair similar Class II or Class I restorations, were asked to participate in the follow up. All patients invited, participated in the study. No participant was excluded because of high caries activity, periodontal condition or parafunctional habits in order to mirror the whole patient population. Pregnant female patients were excluded. All patients were informed on the background of the study, which was approved by the ethics committee of the University of Umeå (Dnr 07-152M). Reasons for placement of the resin composite restorations were primary and secondary carious lesions, fracture of old amalgam fillings or replacement because of esthetic or other reasons. In order to make an intra-individual comparison possible, each patient received two or four as similar sized and located restorations as possible. The cavity pairs in each individual were randomly distributed to be restored with either the experimental or the control restoration before the operative procedure started, according to a predetermined scheme of randomization. The participants were not aware in which cavity, the experimental and control restoration were placed. In the experimental cavity an intermediate layer of the SDR flowable RC (Dentsply/DeTrey, Konstanz, Germany; Table 1) was placed in the dentinal part followed by a covering layer of the nano-hybrid resin composite Ceram X mono (Dentsply/DeTrey; from now on called Ceram X). The control restoration was filled with Ceram X (resin composite-only restoration). Thirty-eight pairs Class II and 15 pairs Class I restorations were placed in 38 patients with a mean age of 55.3 years (range 32–87) by one experienced operator (JvD). The distribution of the involved experimental teeth is shown in Table 2. The sample size was calculated on the basis
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Table 1 – Resin composites and adhesive system used. Material
Composition
Type
SDR
Filler: Barium-alumino-fluoroborosilicate glass, strontium alumino-fluoro-silicate glass Matrix: modified urethane dimethacrylate resin, ethoxylated bisphenol-A dimethacrylate (EBPADMA), triethyleneglycol dimethacrylate, camphorquinone, butylated hydroxyl toluene, uv stabilizer, titanium oxide, iron oxide pigments. The SDR flow base is covered with at least 2 mm RC.
Ceram XMono
Filler: Barium–aluminum-borosilicate glass (1.1–1.5 m), methacrylate functionalized silicone dioxide nano filler (10 nm) Matrix: Methacrylate modified polysiloxane, dimethacrylate resin, fluorescent pigment, UV stabilizer, stabilizer, camphorquinone, ethyl-4 (dimethylamino) benzoate, titanium oxice pigments, aluminum silicate pigments
Xeno V
Application steps
Manufacturer
4 mm layers, light cured 20 s
Dentsply DeTrey, Konstanz, Germany
Nanohybrid 76%, w/w filler 57%, v/v filler average size nanofillers 10 nm and nano particles 2.3 nm
2 mm layers, light cured 20-30 s
Dentsply DeTrey.
1-component one-step Self-etching adhesive
Apply primer 20 s, careful air drying for >5 s, light cured 10 s.
Dentsply DeTrey
of previous sample size calculations performed in similar designed studies of posterior restoration evaluations. The theoretical sample size was set to 40 restorations per group to determine significant differences in outcomes at the 95% confidence level, with an alpha value = 0.05 and 80% power. Significant differences between material groups in similar intraindividual comparison design evaluations have been possible to determine with this sample size in earlier evaluations [26–28]. The number of participants was increased to safeguard against possible drop outs. All teeth were in occlusion and had at least one proximal contact with an adjacent tooth.
2.1.
Clinical procedure
Existing restorations and/or caries were removed under constant water cooling. No bevels were prepared. The operative field was carefully isolated with cotton rolls and suction device. For all Class II cavities a thin metallic matrix was used and carefully wedging was performed with wooden wedges (Kerr/Hawe Neos, Switzerland). The cavities were cleaned
Table 2 – Distribution and size of the experimental restorations. Surfaces
Mandibula
Maxilla
Total
Premolars Molars Premolars Molars 1 surfaces 2 surfaces ≥3 surfaces
3 16 –
8 8 3
2 26 –
17 20 3
30 70 6
Total
19
19
28
40
106
by thoroughfull rinsing with water. In none of the cavities Ca(OH)2 or other base materials was applied. Application of the 1-step self etching adhesive XenoV (DeTrey Dentsply) in both cavities was performed according to the manufacturers instructions (Table 2). After 20 s gently agitating, the solvent was evaporated thoroughly during at least 5 s. Curing was then performed with a well controlled high power curing unit (Smartlite PS, Dentsply/DeTrey) for at least 10 s. In the by randomization chosen experimental SDR restoration, the flow material was dispensed directly into the cavity from the compula tip using slow steady pressure, starting dispensing at the deepest portion of the cavity, keeping the tip close to the cavity floor. The tip was gradually withdrawn as the cavity was filled. The material was available in one semi-transluscent universal shade. It was placed in bulk increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface. After curing of the flow increment(s)(20 s), the occlusal part of the restoration was completed using the Ceram X resin composite material. In the control cavity the resin composite Ceram X was applied in 2 mm layers with, if possible, an oblique layering technique. Selected resin composite instruments (Hu Friedy) were used. The pairs of restorations were placed by the same with adhesive dentistry experienced operator (the first author). After checking the occlusion/articulation and contouring with finishing diamond burrs, the final polishing was performed with the Shofu polishing system (Brownie) or the Enhance polishing system (DeTrey Dentsply).
2.2.
Evaluation
At baseline (after placement of the restorations) and after one, two and three years the restorations were assessed by the
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Table 3 – Modified USPHS criteria for direct clinical evaluation [28]. Category
Score (acceptable/unacceptable)
Anatomical form
0 1
2 3
0 Marginal adaptation
1 2 3 4
Color match
0 1 2 3 4
Marginal discoloration
Surface roughness
Restoration is contiguous with existing anatomic form, explorer does not catch Explorer catches, no crevice is visible into which explorer will penetrate Crevice at margin, enamel exposed Obvious crevice at margin, dentin or base exposed Restoration mobile, fractured or missing Very good color match Good color match Slight mismatch in color, shade or translucency Obvious mismatch, outside the normal range Gross mismatch
3
3
Smooth surface Slightly rough or pitted Rough, cannot be refinished Surface deeply pitted, irregular grooves
1
No evidence of caries contiguous with the margin of the restoration Caries is evident contiguous with the margin of the restoration
0 1 2
following parameters: anatomic form, marginal adaptation, marginal discoloration, surface roughness, color match and secondary caries by slightly modified USPHS criteria according to van Dijken 1986 (Table 3) [28]. The follow up registrations were performed blindly by the operator and at regular intervals by two calibrated evaluators. During the evaluation sessions, evaluators did not know which study or which restorative material group the scoring concerned. The caries risk for each participant and their parafunctional habits activity at baseline and during the follow ups was estimated by the treating clinician by means of clinical and socio-demographic information routinely available at the annual clinical examinations, e.g. incipient caries lesions and former caries history [29,30].
2.3.
The restoration is contiguous with tooth anatomy Slightly under- or over-contoured restoration; marginal ridges slightly undercontoured; contact slightly open (may be self-correcting); occlusal height reduced locally Restoration is undercontoured, dentin or base exposed; contact is faulty, not self-correcting; occlusal height reduced; occlusion affected Restoration is missing partially or totally; fracture of tooth structure; shows traumatic occlusion; restoration causes pain in tooth or adjacent tissue
No discoloration evident Slight staining, can be polished away Obvious staining can not be polished away Gross staining
0 1 2
0
Caries
Criteria
Statistical analysis
The characteristics of the restorations are described by descriptive statistics using cumulative frequency distributions of the scores. The experimental and control restorative techniques were compared intra-individually with the non parametric Friedman’s two-way analysis of variance test [31].
of the participant. After 3 years, 104 restorations, 28 Class I and 76 Class II were evaluated. One molar resin compositeonly tooth showed post-operative sensitivity during the first 3 weeks for temperature changes and occlusal forces. Two failed Class II resin composite-only molar restorations were observed during the first year, one cuspfracture and one resin composite fracture. This resulted in annual failure rates of 1.3% for the resin composite-only group and 0% for the experimental SDR/Ceram X group. The overall difference between the two restoration groups for the evaluated variables in both cavity classes was not significant. The scores at baseline and 3 years for the evaluated restorations are given as relative frequencies in Table 4. The color match deteriorated significantly during the follow up (p < 0.05). Ten participants were estimated as having high caries risk and eleven showed mild to severe parafunctional habits during the observation period. No secondary caries was observed. The resin composite fracture occurred in a bruxing participant. No further statistical analysis were performed due to the low failure rate.
4. 3.
Discussion
Results
One male patient with 2 molar Class I restorations could not be observed at the 2 and 3 years recalls due to death
Incremental placement techniques have been necessary to obtain adequate light penetration and have been suggested to reduce shrinkage stress [2]. Therefore, the general practitioner
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Table 4 – Scores for the evaluated posterior restorations at baseline (106) and after 3 years (104) of the XenoV/SDR-Ceram X mono (SDR/CX) and XenoV/Ceram X mono (CX) restorations given as relative frequencies (%). 0
1
2
3
Anatomical form
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
96.2 100 92.3 94.3
3.8 0 7.7 1.9
0 0 0 1.9
0 0 0 1.9
Marginal adaptation
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
100 100 96.2 88.5
0 0 3.8 5.8
0 0 0 1.9
0 0 0 1.9
0 0 0 1.9
Color match
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
26.9 25.0 5.8 6.0
71.2 75.0 80.8 86.0
1.9 0 13.4 8.0
0 0 0 0
0 0 0 0
Marginal discoloration
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
100 100 100 100
0 0 0 0
0 0 0 0
0 0 0 0
Surface roughness
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
100 100 100 100
0 0 0 0
0 0 0 0
0 0 0 0
placed as a standard technique 2 mm increments, each exposed to separate light curing. A procedure which is time consuming, increased the risk of contamination and may include voids in the restoration. One of the goals of adhesive dentistry is to obtain a tight interfacial adaptation. Inferior adaptation may increase the risk of microleakage, debonding, secondary caries and postoperative sensitivity. Therefore, there is a need for materials and methods which decrease stress formation during placement and curing procedures. The stress reducing effect of the incremental filling techniques have been questioned and finite element calculations showed that an oblique layering technique produced more stress concentration at the interface compared to a horizontal filling technique [32,33]. Versluis et al. showed that additional increments increased the cuspal deformation of the weakened cusps [32]. During the last years several materials and techniques have been introduced to simplify the resin composite procedure. Most of these simplifications concerned fewer steps and a self etching function of adhesive systems. Another simplification, “bulk-filling” resin composites was recently introduced. One of the first marketed composites in this material class, the flowable resin composite SDR was investigated in our study. Bulk filling for current marketed materials means in practice placement of layers up to 4 mm thickness [19,20,22]. A higher translucency and incorporation of a photoactive group in the methacrylate resin enables SDR to be injected and cured in 4 mm layers (Dentsply DeTrey technical information). In vitro research showed that the flowable resin composite exhibited acceptable properties compared with other resin composite materials [17,22,34,35]. The polymerization stress was considerably lower for SDR compared to other conventional flowable materials and comparable with that of low-shrinkage resin composites [20,22,36]. Moorthy et al. assessed the cuspal deflection of standardized MOD cavities using SDR to restore the cavities within 2 mm of the palatal cusp in a single increment. They showed
4
that the mean cuspal deflections were significantly reduced compared with the multiple oblique increments (2 mm) filling technique with a nanohybrid resin composite [22]. Roggendorf et al. showed that 4 mm layers of SDR combined with five different resin composites showed good interfacial adaptation [35]. Van Ende et al. [34] reported that the flowable bulkfil material provided satisfactory microtensile bond strength to cavity-bottom dentin. This was also observed in high Cfactor cavities regardless of filling technique and cavity depth, where conventional RC failed when used in bulk. The bulkfill flowable base could maintain its bond strength without any pre-testing failures. No difference in gap size in Class II resin composite restorations was observed comparing bulk and incremental filling techniques. However the rates of conversion were not reported which makes the results questionable [37]. To obtain sufficient depth of cure requires high light energy and this may influence the quality of adaptation due to a higher stress formation at the interface. Morever, the mechanical properties of the resin composite are compromized with an inferior cure in the deeper parts of the resin composite restoration. The mechanical properties are dependent on the material’s formulation, the extent of the curing reaction and the placement technique of the operator. Campocodino et al. investigated the effect of a bulk filling technique with a nanofiller resin composite (Filtek Supreme Plus, 3M/ESPE) on curing depth [23]. Bulk filling with the material resulted in a continuous drop in hardness values as the depth increased. The values were significantly lower than those placed with a 2 mm layering technique. The observed compromized depth of cure of the nanofiller resin composite confirmed the use of incremental application methods for conventional resin composites. The enhanced translucency of SDR promotes light transmittance and enables adequate curing efficiency up to 4 mm layers maintaining the mechanical properties of the RC [20,24,34]. However, as indicated by the manufacturer, Ilie et al. showed that addition of the
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occlusal capping layer made of a regular resin composite is a necessity. The modulus of elasticity and hardness of the flowable material was considerably below the mean values of regular nanohybrid and microhybrid resin composites [38]. A short observation period of three years was chosen in this study for the clinical evaluation of the new bulk filling technique to observe the occurrence of catastrophic failures which may be caused by a not-optimal conversion in the deeper layers. In earlier similar designed studies it has been shown that restorative materials with a high rate of catastrophic failures can be detected already in 2–3 year follow ups compared to control materials [25–27]. The clinical relevance of this study was to evaluate the effectiveness of the new bulk fill resin composites and their increased layer thickness curing technique. To observe if they were comparable with an established conventional nano-hybrid resin composite with 2 mm layering technique or that they could result in a new catastrophic failure material group. In the present clinical study, annual failure rates (AFR) observed in the 3 year evaluation were for the SDR restorations 0% and the controls without SDR 1.3%. No difference in overall clinical outcome was observed between the restorations and the hypothesis was therefore accepted. However, despite the observed nonstatistical significance, a clinical significance can be stated for the bulk-fill technique. The observed AFR can be compared with the 1.8% and 1.9% AFR reported recently in a 3 year follow up of the same ormocer-based nanohybrid resin composite placed incrementally in combination with a 1step SEA or a 2-step etch-and-rinse adhesive, respectively [6]. Recently published clinical evaluations of different nanohybrid resin composites reported annual failure rates between 0 and 1.8% [6]. However, several of these studies included low numbers of Class II restorations and selected participants. Three studies, including the one mentioned above, reported the durabilitity of the ormocer-based nano-hybrid resin composite. Schirrmeister et al. [39] observed two failures of 24 Class II restorations after 4 years and Monteiro et al. [40] one failure of 30 restorations after 2 years. Both used etch-andrinse adhesives. This resulted in annual failure rates of 1.8% and 1.7%, respectively, slightly higher then the AFR found in the present study with the 1-step SEA bonded restorations. A low frequency of postoperative sensitivity was reported in the present study, which is in accordance with findings in other evaluations of self-etching adhesives [6,18,41–44]. In contrast to several nanofilled resin composite evaluations, no patients were excluded in the present study because of high caries activity, not acceptable oral hygiene or parafunctional habits [45–47]. In this way the sample represents a normal clinical patient population. A number of at least 50 restorations per group can be proposed, according to power analysis and experience in our research group. A number confirmed by a recently performed sample size estimate in a randomized intra-individual comparison of resin composites [48,49]. It can be concluded that the bulk-filling technique based on SDR technology showed highly acceptable clinical results comparable to the conventional 2 mm incremental technique in the 3-year follow-up.
Acknowledgement The support from the County Council of Västerbotten and DeTrey/Dentsply is gratefully acknowledged.
references
[1] Sunnegårdh-Grönberg K, van Dijken JWV, Funegårdh U, Lindberg A, Nilsson M. Selection of dental materials and longevity of replaced restorations in Public Dental Health clinics in northern Sweden. J Dent 2009;37:673–8. [2] Feilzer AJ, de Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res 1987;66:1636–9. [3] Lindberg A, van Dijken JWV, Lindberg M. Nine-year evaluation of a poly-acid-modified resin composite open sandwich technique in class II cavities. J Dent 2006;35: 124–9. [4] van Dijken JWV. Durability of resin composite restorations in high C-factor cavities. A 12-year follow-up. J Dent 2010;38:469–74. [5] van Dijken JWV, Pallesen U. Clinical performance of a hybrid resin composite with and without an intermediate layer of flowable resin composite: a 7-year evaluation. Dent Mater 2011;27:150–6. [6] van Dijken JWV, Pallesen U. Four-year clinical evaluation of Class II nano-hybrid resin composite restorations bonded with a one-step self-etch and a two-step etch-and-rinse adhesive. J Dent 2011;39:16–25. [7] van Dijken JWV, Pallesen U. A 7-year randomized prospective study of a one-step self-etching adhesive in -carious cervical lesions. The effect of curing modes and restorative material. J Dent 2012;40:1060–7. [8] Stefanski S, van Dijken JWV. Clinical performance of a nanofilled resin composite with and without a flowable composite liner. A 2-year evaluation. Clin Oral Investig 2012;16:147–53. [9] Weinmann W, Thalacker C, Guggenberger R. Siloranes in dental composites. Dent Mater 2005;21:68–74. [10] van Dijken JWV, Lindberg A. Clinical effectiveness of a low shrinkage resin composite. A five-year study. J Adhes Dent 2009;11:143–8. [11] Lindberg A, Peutzfeldt A, van Dijken JWV. Effect of power density of curing unit, exposure duration, and light guide distance on composite depth of cure. Clin Oral Investig 2005;9:71–6. [12] Lindberg A, Enami N, van Dijken JWV. A Fourier Transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units. Swed Dent J 2005;29:105–12. [13] Poskus LT, Placido E, Cardoso PEC. Influence of placement techniques on Vickers and Knoop hardness of Class II composite resin restorations. Dent Mater 2004;20: 726–32. [14] Michelsen VB, Kopperud HB, Lygre GB, Björkman L, Jensen E, Klever IS, Svahn J, Lygre H. Detection and quantification of monomers in unstimulated whole saliva after treatment with resin-based composite fillings in vivo. Eur J Oral Sci 2012;120:89–95. [15] Pilo R, Oelgiesser D, Cardash HS. A survey of output intensity and potential for depth of cure among light-curing units in clinical use. J Dent 1999;27:235–41. [16] Flury S, Hayoz S, Peutzfeldt A, Hüsler J, Lussi A. Depth of cure of resin composites. Is the ISO 4049 method suitable for bulk fill materials? Dent Mater 2012;28:521–8.
d e n t a l m a t e r i a l s 3 0 ( 2 0 1 4 ) e245–e251
[17] El-Safty S, Silikas N, Watts DC. Creep deformation of restorative resin-composites intended for bulk-fill placement. Dent Mater 2012;28:928–35. [18] Manhart J, Chen H-Y, Hickel R. Clinical evaluation of the posterior composite QuiXfil in class I and II cavities: 4-year follow-up of a randomized controlled trial. J Adhes Dent 2009;12:1–7. [19] Jin X, Bertrand S, Hammesfahr PD. New radically polymerizable resins with remarkably low curing stress. J Dent Res 2009;88(Spec Issue A):1651. [20] Ilie N, Hickel R. Investigations on a methacrylate-based flowable composite based on the SDRTM technology. Dent Mater 2011;27:348–55. [21] Tjan AHL, Bergh BH, Lidner C. Effect of various incremental techniques on the marginal adaptation of class II composite resin restorations. J Prosthet Dent 1992;67:62–9. [22] Moorthy A, Hogg CH, Dowling AH, Grufferty BF, Benetti AR, Fleming GJP. Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials. J Dent 2012;40:500–5. [23] Campodonico CE, Tantbirojn D, Olin PS, Versluis A. Cuspal deflection and depth of cure in resin-based composite restorations filled by using bulk, incremental and transtooth-illumination techniques. J Am Dent Assoc 2011;142:1176–82. [24] Czasch P, Ilie N. In vitro comparison of mechanical properties and degree of cure of bulk fill composites. Clin Oral Investig 2012;17:227–35. [25] van Dijken JWV. Clinical evaluation of three different adhesive systems in Class V non-carious lesions. Dent Mater 2000;16:285–91. [26] van Dijken JWV, Sunnegårdh-Grönberg K. A two-year clinical evaluation of a new calcium aluminate cement in Class II cavities. Acta Odontol Scand 2003;61:235–40. [27] van Dijken JWV, Sunnegårdh-Grönberg K. A three-year clinical evaluation of a new calcium aluminate cement in Class V cavities. Swed Dent J 2004;28:111–8. [28] van Dijken JWV. A clincial evaluation of anterior conventional, microfiller and hybrid composite resin fillings. A six year follow up study. Acta Odontol Scand 1986;44:357–67. [29] Isokangas P, Alanen P, Tiekso J. The clinician’s ability to identify caries risk subjects without saliva tests – a pilot study. Community Dent Oral Epidemiol 1993;21:8–10. [30] Seppä L, Hausen H, Pöllänen L, Helasharju K, Karkkainen S. Past caries recording made in Public Dental Clinics as predictors of caries prevalence in early adolescence. Community Dent Oral Epidemiol 1989;17:277–81. [31] Siegel S. Nonparametric Statistics. New York: McGraw-Hill Book Company, Inc.; 1956. p. 166–72. [32] Versluis A, Douglas WH, Cross M, Sakaguchi RL. Does an incremental filling technique reduce polymerization shrinkage stresses. J Dent Res 1996;75:871–8. [33] Abbas G, Fleming GJ, Harrington E, Shortall AC, Burke FJ. Cuspal movement and microleakage in premolar teeth restored with a packable composite cured in bulk or increments. J Dent 2003;31:437–44. [34] Van Ende A, De Munck J, Van Landuyt KL, Poitevin A, Peumans M, Van Meerbeek B. Bulk-filling of high C-factor posterior cavities: effect on adhesion to cavity-bottom dentin. Dent Mater 2012;29:269–77.
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[35] Roggendorf MJ, Krämer N, Appelt A, Naumann M, Frankenberger R. Marginal quality of flowable 4-mm base vs conventionally layered resin composite. J Dent 2011;39:643–7. [36] Rullmann I, Schattenberg A, Marx M, Willershausen B, Ernst CP. Photoelastic determination of polymerization shrinkage stress in low-shrinkage resin composites. Schweiz Monatsschr Zahnmed 2012;122:294–9. [37] Idriss S, Habib C, Abduljabbar T, Omar R. Marginal adaptation of class II resin composite restorations using incremental and bulk placement techniques: an ESEM study. J Oral Rehabil 2003;30:1000–7. [38] Ilie N, Bucuta S, Draenert M. Bulk-fill resin-based composites: an in vitro assessment of their mechanical performance. Oper Dent 2013;38, http://dx.doi.org/10.2341/12-395-L [E-pub ahead of print]. [39] Schirrmeister JF, Huber K, Hellwig E, Hahn P. Four-year evaluation of a resin composite including nanofillers in posterior cavities. J Adhes Dent 2009;11: 399–404. [40] Monteiro PM, Manso MC, Gavinha S, Melo P. Two-year clinical evaluation of packable and nanostructured resin-based composites placed with two techniques. J Am Dent Assoc 2010;141:319–29. [41] Ergücü Z, Türkün LS. Clinical performance of novel resin composites in posterior teeth: 18 month results. J Adhes Dent 2007;9:209–16. [42] Perdigão J, Geraldeli S, Hodges JS. Total-etch versus self-etch adhesive. Effect on postoperative sensitivity. J Am Dent Assoc 2003;134:1621–9. [43] Poon ECM, Smales RJ, Yip KHK. Clinical evaluation of packable and conventional hybrid posterior resin-based composites. Results at 3.5 years. J Am Dent Assoc 2005;136:1533–40. [44] Ermis RB, Kam O, Celik EU, Temel UB. Clinical evaluation of a two-step etch&rinse and a two-step self-etch adhesive system in class II restorations: two-year results. Oper Dent 2009;34:656–63. [45] Dresch W, Volpato S, Gomes JC, Ribeiro NR, Reis A, Loguercio AD. Clinical evaluation of a nanofilled composite in posterior teeth: 12-month evaluation. Oper Dent 2006;31: 409–17. [46] Palaniappan S, Bharadwaj D, Mattar DL, Peumans M, Van Meerbeek B, Lambrechts P. Three-year randomized clinical trial to evaluate the clinical performance and wear of a nanocomposite versus a hybrid composite. Dent Mater 2009;25:1302–14. [47] Mahmoud SH, El-Embaby AE, Abdallah AM, Hamama HH. Two-year clinical evaluation of ormocer, nanohybrid and nanofill composite restorations in posterior teeth. J Adhes Dent 2008;10:315–22. [48] Hickel R, Roulet J-F, Bayne S, Heintze SD, Mjör IA, Peters M, Rousson V, Randall R, Schmalz G, Tyas M, Vanherle G. Recommendations for conducting controlled clinical studies of dental restorative materials. Clin Oral Investig 2007;11:5–33. [49] Shi L, Wang X, Zhao Q, Zhang Y, Ren Y, Chen Z. Evaluation of packable and conventional hybrid resin composites in class I restorations: three-year results of a randomized, double-blind and controlled clinical trial. Oper Dent 2010;35:11–9.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/dema
A randomized controlled three year evaluation of “bulk-filled” posterior resin restorations based on stress decreasing resin technology Jan W.V. van Dijken a,∗ , Ulla Pallesen b a b
Dental School, Faculty of Medicine, Umeå University, Umeå, Sweden Institute of Odontology, Faculty of Health Science, University of Copenhagen, Denmark
a r t i c l e
i n f o
a b s t r a c t
Article history:
Objective. The objective of this randomized controlled prospective clinical trial was to
Received 10 January 2014
evaluate the efficacy of a flowable resin composite (SDR) bulk fill technique in posterior
Received in revised form
restorations and to compare it intraindividually with a conventional 2 mm resin composite
16 April 2014
curing technique in a 3-year follow up.
Accepted 21 May 2014
Materials and methods. Thirty-eight pairs Class II and 15 pairs Class I restorations were placed in 38 patients with a mean age of 55.3 years (range 32–87). Each patient received at random at least two, as similar as possible, Class II or Class I restorations of two restorative techniques.
Keywords:
In all cavities a single step self-etch adhesive (Xeno V) was applied. In one of the cavities
Adhesive
of each pair, a flowable resin composite (SDR) was placed, in bulk increments up to 4 mm
Bulk fill
as needed to fill the cavity 2 mm short of the occlusal cavosurface. The occlusal part was
Clinical
completed with a nano-hybrid resin composite (Ceram X mono) layer. In the second cavity,
Resin composite
the hybrid resin composite was placed in 2 mm increments. The restorations were evaluated
Self etch
using slightly modified USPHS criteria at baseline and then yearly during 3 years. Caries risk and parafunctional habits of the participants were estimated. Results. After three years, 76 Class II and 28 Class I restorations could be observed. One molar resin composite-only tooth showed post-operative sensitivity during 3 weeks for temperature changes and occlusal forces. Two failed Class II molar restorations in the resin composite-only group were observed during the first year, one cusp fracture and one resin composite fracture. An annual failure rate of 1.3% was found for the resin composite only restorations and of 0% in the bulk-filled restorations (n.s.). Ten participants were estimated as having high caries risk and eleven showed active bruxing habits. Significance. The 4 mm bulk-fill technique with the flowable resin composite SDR showed highly clinical effectiveness, which was comparable during the 3-year follow-up with the 2 mm resin composite layering technique. © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
∗ Corresponding author at: Department of Odontology, Dental School Umeå, Umeå University, 901 87 Umeå, Sweden. Tel.: +46 90 7856047/135074. E-mail address: [email protected] (J.W.V. van Dijken). http://dx.doi.org/10.1016/j.dental.2014.05.028 0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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1.
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Introduction
In many countries resin composites do have almost totally replaced amalgam as restorative in posterior teeth [1]. The majority of the resin composites are today methacrylate based and cure by means of a free radical polymerization. During curing of the monomers, a network of polymers is formed which becomes rigid due to increasing cross-linking of the polymer chains. In the post-gel contraction phase, the shrinkage manifests as a strain on the resin composite and cavity walls which may result in interfacial deficiencies, enamel fractures, cuspal movements and cracked cusps. Gap formation may increase the potential for post-operative sensitivity, microleakage and secondary caries. The resulting stress depends on factors like: resin monomers involved, filler technology, gel point, C-factor of the cavity, elastic modulus of the resin composite, curing technique and conversion rate. Several clinical techniques have been suggested to minimize interfacial stress formation like decreasing the C-factor by using selected layering technique, to use stress reducing curing techniques such as the soft start curing and placement of stress absorbing intermediary layers in sandwich techniques [2–8]. Extensive efforts have been made during the last years to develop low shrinkage materials by changes in filler technology and monomer chemistry [9,10]. The intensity of the curing light decreases when the light is transmitted through the resin composite. The conversion rate in the resin composite restoration will decrease at increasing distance from the curing light and by decreased energy [11,12]. A lower conversion rate will influence the physical properties of the resin composite and increased elution of monomers have been reported [13,14]. To prevent clinical failures because of a non-optimal cured resin composite and decrease the elution of non-reacted monomers, the resin composite restoration is cured in increments. The maximal incremental thickness which provides adequate light penetration and polymerization has been generally defined as 2 mm [15,16]. The layering technique makes the restorative procedure time consuming, voids may be included and the failure risk increases [17]. The main concern regarding applying thicker increments is whether the resin composite cures enough in the deeper parts to obtain acceptable mechanicical, physical and biocompatible properties. Recently, a new class of resin composite materials the bulk-fill resin composites have been introduced. During the early 2000th a first approach to apply posterior resin composite restorations with thicker layers was introduced as a rather high transluscent resin composite [18]. More recently an on stress decreasing resin technology based flowable resin (SDR) was introduced to be used in 4 mm layers as open or closed dentin replacement beneath a conventional resin composite [19]. The rheology of the material was suggested to be improved allowing improved adaptation to the cavity walls. A polymerization modulator, a patented urethane di-methacrylate, is chemically embedded in the resin backbone of the resin composite. This results in a slower modulus development, allowing for stress reduction without decreasing conversion rate [19,20]. In vitro studies showed that the application of fewer and thicker increments could be equally successful as the conventional layering technique [20–23]. Ilie and Hickel showed that SDR showed the
lowest shrinkage stress and shrinkage rate in comparisons to regular methacrylate resin composites [20]. The degree of cure and mechanical properties were shown to be constant within the 4 mm increment at a curing time of 20 s [24]. The bulk-fill material exhibited an acceptable creep deformation and within the range exhibited by other resin composites [17]. Cuspal deflections were significantly reduced when a single increment of the flowable resin composite was used as dentin replacement base to restore Class II cavities [22]. No clinical study has yet reported the clinical effectiveness of the SDR flowable base and its claimed 4 mm thick layer curing. The aim of this study was to investigate in a randomized controlled intraindividual comparison the clinical effectiveness of the flowable resin composite placed with maximally 4 mm increments (bulk fill) in large and deep Class I and Class II cavities. SDR is used to fill the cavity 2 mm short of the occlusal cavosurface and is then covered with a nano-hybrid resin composite. The SDR restoration is compared intraindividually with a nano-hybrid resin composite-only restoration placed and cured with a 2 mm layering technique. In both the experimental- and resin composite-only control cavity a onestep self-etching bonding system was used. The hypothesis tested was that bulk-fill restorations show similar durability as the resin composite-only restorations
2.
Material and methods
During may-october 2010, all adult patients attending the Public Dental Health Service clinic at the Dental School Umeå who needed one or two pair similar Class II or Class I restorations, were asked to participate in the follow up. All patients invited, participated in the study. No participant was excluded because of high caries activity, periodontal condition or parafunctional habits in order to mirror the whole patient population. Pregnant female patients were excluded. All patients were informed on the background of the study, which was approved by the ethics committee of the University of Umeå (Dnr 07-152M). Reasons for placement of the resin composite restorations were primary and secondary carious lesions, fracture of old amalgam fillings or replacement because of esthetic or other reasons. In order to make an intra-individual comparison possible, each patient received two or four as similar sized and located restorations as possible. The cavity pairs in each individual were randomly distributed to be restored with either the experimental or the control restoration before the operative procedure started, according to a predetermined scheme of randomization. The participants were not aware in which cavity, the experimental and control restoration were placed. In the experimental cavity an intermediate layer of the SDR flowable RC (Dentsply/DeTrey, Konstanz, Germany; Table 1) was placed in the dentinal part followed by a covering layer of the nano-hybrid resin composite Ceram X mono (Dentsply/DeTrey; from now on called Ceram X). The control restoration was filled with Ceram X (resin composite-only restoration). Thirty-eight pairs Class II and 15 pairs Class I restorations were placed in 38 patients with a mean age of 55.3 years (range 32–87) by one experienced operator (JvD). The distribution of the involved experimental teeth is shown in Table 2. The sample size was calculated on the basis
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Table 1 – Resin composites and adhesive system used. Material
Composition
Type
SDR
Filler: Barium-alumino-fluoroborosilicate glass, strontium alumino-fluoro-silicate glass Matrix: modified urethane dimethacrylate resin, ethoxylated bisphenol-A dimethacrylate (EBPADMA), triethyleneglycol dimethacrylate, camphorquinone, butylated hydroxyl toluene, uv stabilizer, titanium oxide, iron oxide pigments. The SDR flow base is covered with at least 2 mm RC.
Ceram XMono
Filler: Barium–aluminum-borosilicate glass (1.1–1.5 m), methacrylate functionalized silicone dioxide nano filler (10 nm) Matrix: Methacrylate modified polysiloxane, dimethacrylate resin, fluorescent pigment, UV stabilizer, stabilizer, camphorquinone, ethyl-4 (dimethylamino) benzoate, titanium oxice pigments, aluminum silicate pigments
Xeno V
Application steps
Manufacturer
4 mm layers, light cured 20 s
Dentsply DeTrey, Konstanz, Germany
Nanohybrid 76%, w/w filler 57%, v/v filler average size nanofillers 10 nm and nano particles 2.3 nm
2 mm layers, light cured 20-30 s
Dentsply DeTrey.
1-component one-step Self-etching adhesive
Apply primer 20 s, careful air drying for >5 s, light cured 10 s.
Dentsply DeTrey
of previous sample size calculations performed in similar designed studies of posterior restoration evaluations. The theoretical sample size was set to 40 restorations per group to determine significant differences in outcomes at the 95% confidence level, with an alpha value = 0.05 and 80% power. Significant differences between material groups in similar intraindividual comparison design evaluations have been possible to determine with this sample size in earlier evaluations [26–28]. The number of participants was increased to safeguard against possible drop outs. All teeth were in occlusion and had at least one proximal contact with an adjacent tooth.
2.1.
Clinical procedure
Existing restorations and/or caries were removed under constant water cooling. No bevels were prepared. The operative field was carefully isolated with cotton rolls and suction device. For all Class II cavities a thin metallic matrix was used and carefully wedging was performed with wooden wedges (Kerr/Hawe Neos, Switzerland). The cavities were cleaned
Table 2 – Distribution and size of the experimental restorations. Surfaces
Mandibula
Maxilla
Total
Premolars Molars Premolars Molars 1 surfaces 2 surfaces ≥3 surfaces
3 16 –
8 8 3
2 26 –
17 20 3
30 70 6
Total
19
19
28
40
106
by thoroughfull rinsing with water. In none of the cavities Ca(OH)2 or other base materials was applied. Application of the 1-step self etching adhesive XenoV (DeTrey Dentsply) in both cavities was performed according to the manufacturers instructions (Table 2). After 20 s gently agitating, the solvent was evaporated thoroughly during at least 5 s. Curing was then performed with a well controlled high power curing unit (Smartlite PS, Dentsply/DeTrey) for at least 10 s. In the by randomization chosen experimental SDR restoration, the flow material was dispensed directly into the cavity from the compula tip using slow steady pressure, starting dispensing at the deepest portion of the cavity, keeping the tip close to the cavity floor. The tip was gradually withdrawn as the cavity was filled. The material was available in one semi-transluscent universal shade. It was placed in bulk increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface. After curing of the flow increment(s)(20 s), the occlusal part of the restoration was completed using the Ceram X resin composite material. In the control cavity the resin composite Ceram X was applied in 2 mm layers with, if possible, an oblique layering technique. Selected resin composite instruments (Hu Friedy) were used. The pairs of restorations were placed by the same with adhesive dentistry experienced operator (the first author). After checking the occlusion/articulation and contouring with finishing diamond burrs, the final polishing was performed with the Shofu polishing system (Brownie) or the Enhance polishing system (DeTrey Dentsply).
2.2.
Evaluation
At baseline (after placement of the restorations) and after one, two and three years the restorations were assessed by the
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Table 3 – Modified USPHS criteria for direct clinical evaluation [28]. Category
Score (acceptable/unacceptable)
Anatomical form
0 1
2 3
0 Marginal adaptation
1 2 3 4
Color match
0 1 2 3 4
Marginal discoloration
Surface roughness
Restoration is contiguous with existing anatomic form, explorer does not catch Explorer catches, no crevice is visible into which explorer will penetrate Crevice at margin, enamel exposed Obvious crevice at margin, dentin or base exposed Restoration mobile, fractured or missing Very good color match Good color match Slight mismatch in color, shade or translucency Obvious mismatch, outside the normal range Gross mismatch
3
3
Smooth surface Slightly rough or pitted Rough, cannot be refinished Surface deeply pitted, irregular grooves
1
No evidence of caries contiguous with the margin of the restoration Caries is evident contiguous with the margin of the restoration
0 1 2
following parameters: anatomic form, marginal adaptation, marginal discoloration, surface roughness, color match and secondary caries by slightly modified USPHS criteria according to van Dijken 1986 (Table 3) [28]. The follow up registrations were performed blindly by the operator and at regular intervals by two calibrated evaluators. During the evaluation sessions, evaluators did not know which study or which restorative material group the scoring concerned. The caries risk for each participant and their parafunctional habits activity at baseline and during the follow ups was estimated by the treating clinician by means of clinical and socio-demographic information routinely available at the annual clinical examinations, e.g. incipient caries lesions and former caries history [29,30].
2.3.
The restoration is contiguous with tooth anatomy Slightly under- or over-contoured restoration; marginal ridges slightly undercontoured; contact slightly open (may be self-correcting); occlusal height reduced locally Restoration is undercontoured, dentin or base exposed; contact is faulty, not self-correcting; occlusal height reduced; occlusion affected Restoration is missing partially or totally; fracture of tooth structure; shows traumatic occlusion; restoration causes pain in tooth or adjacent tissue
No discoloration evident Slight staining, can be polished away Obvious staining can not be polished away Gross staining
0 1 2
0
Caries
Criteria
Statistical analysis
The characteristics of the restorations are described by descriptive statistics using cumulative frequency distributions of the scores. The experimental and control restorative techniques were compared intra-individually with the non parametric Friedman’s two-way analysis of variance test [31].
of the participant. After 3 years, 104 restorations, 28 Class I and 76 Class II were evaluated. One molar resin compositeonly tooth showed post-operative sensitivity during the first 3 weeks for temperature changes and occlusal forces. Two failed Class II resin composite-only molar restorations were observed during the first year, one cuspfracture and one resin composite fracture. This resulted in annual failure rates of 1.3% for the resin composite-only group and 0% for the experimental SDR/Ceram X group. The overall difference between the two restoration groups for the evaluated variables in both cavity classes was not significant. The scores at baseline and 3 years for the evaluated restorations are given as relative frequencies in Table 4. The color match deteriorated significantly during the follow up (p < 0.05). Ten participants were estimated as having high caries risk and eleven showed mild to severe parafunctional habits during the observation period. No secondary caries was observed. The resin composite fracture occurred in a bruxing participant. No further statistical analysis were performed due to the low failure rate.
4. 3.
Discussion
Results
One male patient with 2 molar Class I restorations could not be observed at the 2 and 3 years recalls due to death
Incremental placement techniques have been necessary to obtain adequate light penetration and have been suggested to reduce shrinkage stress [2]. Therefore, the general practitioner
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Table 4 – Scores for the evaluated posterior restorations at baseline (106) and after 3 years (104) of the XenoV/SDR-Ceram X mono (SDR/CX) and XenoV/Ceram X mono (CX) restorations given as relative frequencies (%). 0
1
2
3
Anatomical form
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
96.2 100 92.3 94.3
3.8 0 7.7 1.9
0 0 0 1.9
0 0 0 1.9
Marginal adaptation
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
100 100 96.2 88.5
0 0 3.8 5.8
0 0 0 1.9
0 0 0 1.9
0 0 0 1.9
Color match
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
26.9 25.0 5.8 6.0
71.2 75.0 80.8 86.0
1.9 0 13.4 8.0
0 0 0 0
0 0 0 0
Marginal discoloration
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
100 100 100 100
0 0 0 0
0 0 0 0
0 0 0 0
Surface roughness
SDR/CX baseline CX baseline SDR/CX 3 years CX 3 years
100 100 100 100
0 0 0 0
0 0 0 0
0 0 0 0
placed as a standard technique 2 mm increments, each exposed to separate light curing. A procedure which is time consuming, increased the risk of contamination and may include voids in the restoration. One of the goals of adhesive dentistry is to obtain a tight interfacial adaptation. Inferior adaptation may increase the risk of microleakage, debonding, secondary caries and postoperative sensitivity. Therefore, there is a need for materials and methods which decrease stress formation during placement and curing procedures. The stress reducing effect of the incremental filling techniques have been questioned and finite element calculations showed that an oblique layering technique produced more stress concentration at the interface compared to a horizontal filling technique [32,33]. Versluis et al. showed that additional increments increased the cuspal deformation of the weakened cusps [32]. During the last years several materials and techniques have been introduced to simplify the resin composite procedure. Most of these simplifications concerned fewer steps and a self etching function of adhesive systems. Another simplification, “bulk-filling” resin composites was recently introduced. One of the first marketed composites in this material class, the flowable resin composite SDR was investigated in our study. Bulk filling for current marketed materials means in practice placement of layers up to 4 mm thickness [19,20,22]. A higher translucency and incorporation of a photoactive group in the methacrylate resin enables SDR to be injected and cured in 4 mm layers (Dentsply DeTrey technical information). In vitro research showed that the flowable resin composite exhibited acceptable properties compared with other resin composite materials [17,22,34,35]. The polymerization stress was considerably lower for SDR compared to other conventional flowable materials and comparable with that of low-shrinkage resin composites [20,22,36]. Moorthy et al. assessed the cuspal deflection of standardized MOD cavities using SDR to restore the cavities within 2 mm of the palatal cusp in a single increment. They showed
4
that the mean cuspal deflections were significantly reduced compared with the multiple oblique increments (2 mm) filling technique with a nanohybrid resin composite [22]. Roggendorf et al. showed that 4 mm layers of SDR combined with five different resin composites showed good interfacial adaptation [35]. Van Ende et al. [34] reported that the flowable bulkfil material provided satisfactory microtensile bond strength to cavity-bottom dentin. This was also observed in high Cfactor cavities regardless of filling technique and cavity depth, where conventional RC failed when used in bulk. The bulkfill flowable base could maintain its bond strength without any pre-testing failures. No difference in gap size in Class II resin composite restorations was observed comparing bulk and incremental filling techniques. However the rates of conversion were not reported which makes the results questionable [37]. To obtain sufficient depth of cure requires high light energy and this may influence the quality of adaptation due to a higher stress formation at the interface. Morever, the mechanical properties of the resin composite are compromized with an inferior cure in the deeper parts of the resin composite restoration. The mechanical properties are dependent on the material’s formulation, the extent of the curing reaction and the placement technique of the operator. Campocodino et al. investigated the effect of a bulk filling technique with a nanofiller resin composite (Filtek Supreme Plus, 3M/ESPE) on curing depth [23]. Bulk filling with the material resulted in a continuous drop in hardness values as the depth increased. The values were significantly lower than those placed with a 2 mm layering technique. The observed compromized depth of cure of the nanofiller resin composite confirmed the use of incremental application methods for conventional resin composites. The enhanced translucency of SDR promotes light transmittance and enables adequate curing efficiency up to 4 mm layers maintaining the mechanical properties of the RC [20,24,34]. However, as indicated by the manufacturer, Ilie et al. showed that addition of the
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occlusal capping layer made of a regular resin composite is a necessity. The modulus of elasticity and hardness of the flowable material was considerably below the mean values of regular nanohybrid and microhybrid resin composites [38]. A short observation period of three years was chosen in this study for the clinical evaluation of the new bulk filling technique to observe the occurrence of catastrophic failures which may be caused by a not-optimal conversion in the deeper layers. In earlier similar designed studies it has been shown that restorative materials with a high rate of catastrophic failures can be detected already in 2–3 year follow ups compared to control materials [25–27]. The clinical relevance of this study was to evaluate the effectiveness of the new bulk fill resin composites and their increased layer thickness curing technique. To observe if they were comparable with an established conventional nano-hybrid resin composite with 2 mm layering technique or that they could result in a new catastrophic failure material group. In the present clinical study, annual failure rates (AFR) observed in the 3 year evaluation were for the SDR restorations 0% and the controls without SDR 1.3%. No difference in overall clinical outcome was observed between the restorations and the hypothesis was therefore accepted. However, despite the observed nonstatistical significance, a clinical significance can be stated for the bulk-fill technique. The observed AFR can be compared with the 1.8% and 1.9% AFR reported recently in a 3 year follow up of the same ormocer-based nanohybrid resin composite placed incrementally in combination with a 1step SEA or a 2-step etch-and-rinse adhesive, respectively [6]. Recently published clinical evaluations of different nanohybrid resin composites reported annual failure rates between 0 and 1.8% [6]. However, several of these studies included low numbers of Class II restorations and selected participants. Three studies, including the one mentioned above, reported the durabilitity of the ormocer-based nano-hybrid resin composite. Schirrmeister et al. [39] observed two failures of 24 Class II restorations after 4 years and Monteiro et al. [40] one failure of 30 restorations after 2 years. Both used etch-andrinse adhesives. This resulted in annual failure rates of 1.8% and 1.7%, respectively, slightly higher then the AFR found in the present study with the 1-step SEA bonded restorations. A low frequency of postoperative sensitivity was reported in the present study, which is in accordance with findings in other evaluations of self-etching adhesives [6,18,41–44]. In contrast to several nanofilled resin composite evaluations, no patients were excluded in the present study because of high caries activity, not acceptable oral hygiene or parafunctional habits [45–47]. In this way the sample represents a normal clinical patient population. A number of at least 50 restorations per group can be proposed, according to power analysis and experience in our research group. A number confirmed by a recently performed sample size estimate in a randomized intra-individual comparison of resin composites [48,49]. It can be concluded that the bulk-filling technique based on SDR technology showed highly acceptable clinical results comparable to the conventional 2 mm incremental technique in the 3-year follow-up.
Acknowledgement The support from the County Council of Västerbotten and DeTrey/Dentsply is gratefully acknowledged.
references
[1] Sunnegårdh-Grönberg K, van Dijken JWV, Funegårdh U, Lindberg A, Nilsson M. Selection of dental materials and longevity of replaced restorations in Public Dental Health clinics in northern Sweden. J Dent 2009;37:673–8. [2] Feilzer AJ, de Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res 1987;66:1636–9. [3] Lindberg A, van Dijken JWV, Lindberg M. Nine-year evaluation of a poly-acid-modified resin composite open sandwich technique in class II cavities. J Dent 2006;35: 124–9. [4] van Dijken JWV. Durability of resin composite restorations in high C-factor cavities. A 12-year follow-up. J Dent 2010;38:469–74. [5] van Dijken JWV, Pallesen U. Clinical performance of a hybrid resin composite with and without an intermediate layer of flowable resin composite: a 7-year evaluation. Dent Mater 2011;27:150–6. [6] van Dijken JWV, Pallesen U. Four-year clinical evaluation of Class II nano-hybrid resin composite restorations bonded with a one-step self-etch and a two-step etch-and-rinse adhesive. J Dent 2011;39:16–25. [7] van Dijken JWV, Pallesen U. A 7-year randomized prospective study of a one-step self-etching adhesive in -carious cervical lesions. The effect of curing modes and restorative material. J Dent 2012;40:1060–7. [8] Stefanski S, van Dijken JWV. Clinical performance of a nanofilled resin composite with and without a flowable composite liner. A 2-year evaluation. Clin Oral Investig 2012;16:147–53. [9] Weinmann W, Thalacker C, Guggenberger R. Siloranes in dental composites. Dent Mater 2005;21:68–74. [10] van Dijken JWV, Lindberg A. Clinical effectiveness of a low shrinkage resin composite. A five-year study. J Adhes Dent 2009;11:143–8. [11] Lindberg A, Peutzfeldt A, van Dijken JWV. Effect of power density of curing unit, exposure duration, and light guide distance on composite depth of cure. Clin Oral Investig 2005;9:71–6. [12] Lindberg A, Enami N, van Dijken JWV. A Fourier Transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units. Swed Dent J 2005;29:105–12. [13] Poskus LT, Placido E, Cardoso PEC. Influence of placement techniques on Vickers and Knoop hardness of Class II composite resin restorations. Dent Mater 2004;20: 726–32. [14] Michelsen VB, Kopperud HB, Lygre GB, Björkman L, Jensen E, Klever IS, Svahn J, Lygre H. Detection and quantification of monomers in unstimulated whole saliva after treatment with resin-based composite fillings in vivo. Eur J Oral Sci 2012;120:89–95. [15] Pilo R, Oelgiesser D, Cardash HS. A survey of output intensity and potential for depth of cure among light-curing units in clinical use. J Dent 1999;27:235–41. [16] Flury S, Hayoz S, Peutzfeldt A, Hüsler J, Lussi A. Depth of cure of resin composites. Is the ISO 4049 method suitable for bulk fill materials? Dent Mater 2012;28:521–8.
d e n t a l m a t e r i a l s 3 0 ( 2 0 1 4 ) e245–e251
[17] El-Safty S, Silikas N, Watts DC. Creep deformation of restorative resin-composites intended for bulk-fill placement. Dent Mater 2012;28:928–35. [18] Manhart J, Chen H-Y, Hickel R. Clinical evaluation of the posterior composite QuiXfil in class I and II cavities: 4-year follow-up of a randomized controlled trial. J Adhes Dent 2009;12:1–7. [19] Jin X, Bertrand S, Hammesfahr PD. New radically polymerizable resins with remarkably low curing stress. J Dent Res 2009;88(Spec Issue A):1651. [20] Ilie N, Hickel R. Investigations on a methacrylate-based flowable composite based on the SDRTM technology. Dent Mater 2011;27:348–55. [21] Tjan AHL, Bergh BH, Lidner C. Effect of various incremental techniques on the marginal adaptation of class II composite resin restorations. J Prosthet Dent 1992;67:62–9. [22] Moorthy A, Hogg CH, Dowling AH, Grufferty BF, Benetti AR, Fleming GJP. Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials. J Dent 2012;40:500–5. [23] Campodonico CE, Tantbirojn D, Olin PS, Versluis A. Cuspal deflection and depth of cure in resin-based composite restorations filled by using bulk, incremental and transtooth-illumination techniques. J Am Dent Assoc 2011;142:1176–82. [24] Czasch P, Ilie N. In vitro comparison of mechanical properties and degree of cure of bulk fill composites. Clin Oral Investig 2012;17:227–35. [25] van Dijken JWV. Clinical evaluation of three different adhesive systems in Class V non-carious lesions. Dent Mater 2000;16:285–91. [26] van Dijken JWV, Sunnegårdh-Grönberg K. A two-year clinical evaluation of a new calcium aluminate cement in Class II cavities. Acta Odontol Scand 2003;61:235–40. [27] van Dijken JWV, Sunnegårdh-Grönberg K. A three-year clinical evaluation of a new calcium aluminate cement in Class V cavities. Swed Dent J 2004;28:111–8. [28] van Dijken JWV. A clincial evaluation of anterior conventional, microfiller and hybrid composite resin fillings. A six year follow up study. Acta Odontol Scand 1986;44:357–67. [29] Isokangas P, Alanen P, Tiekso J. The clinician’s ability to identify caries risk subjects without saliva tests – a pilot study. Community Dent Oral Epidemiol 1993;21:8–10. [30] Seppä L, Hausen H, Pöllänen L, Helasharju K, Karkkainen S. Past caries recording made in Public Dental Clinics as predictors of caries prevalence in early adolescence. Community Dent Oral Epidemiol 1989;17:277–81. [31] Siegel S. Nonparametric Statistics. New York: McGraw-Hill Book Company, Inc.; 1956. p. 166–72. [32] Versluis A, Douglas WH, Cross M, Sakaguchi RL. Does an incremental filling technique reduce polymerization shrinkage stresses. J Dent Res 1996;75:871–8. [33] Abbas G, Fleming GJ, Harrington E, Shortall AC, Burke FJ. Cuspal movement and microleakage in premolar teeth restored with a packable composite cured in bulk or increments. J Dent 2003;31:437–44. [34] Van Ende A, De Munck J, Van Landuyt KL, Poitevin A, Peumans M, Van Meerbeek B. Bulk-filling of high C-factor posterior cavities: effect on adhesion to cavity-bottom dentin. Dent Mater 2012;29:269–77.
e251
[35] Roggendorf MJ, Krämer N, Appelt A, Naumann M, Frankenberger R. Marginal quality of flowable 4-mm base vs conventionally layered resin composite. J Dent 2011;39:643–7. [36] Rullmann I, Schattenberg A, Marx M, Willershausen B, Ernst CP. Photoelastic determination of polymerization shrinkage stress in low-shrinkage resin composites. Schweiz Monatsschr Zahnmed 2012;122:294–9. [37] Idriss S, Habib C, Abduljabbar T, Omar R. Marginal adaptation of class II resin composite restorations using incremental and bulk placement techniques: an ESEM study. J Oral Rehabil 2003;30:1000–7. [38] Ilie N, Bucuta S, Draenert M. Bulk-fill resin-based composites: an in vitro assessment of their mechanical performance. Oper Dent 2013;38, http://dx.doi.org/10.2341/12-395-L [E-pub ahead of print]. [39] Schirrmeister JF, Huber K, Hellwig E, Hahn P. Four-year evaluation of a resin composite including nanofillers in posterior cavities. J Adhes Dent 2009;11: 399–404. [40] Monteiro PM, Manso MC, Gavinha S, Melo P. Two-year clinical evaluation of packable and nanostructured resin-based composites placed with two techniques. J Am Dent Assoc 2010;141:319–29. [41] Ergücü Z, Türkün LS. Clinical performance of novel resin composites in posterior teeth: 18 month results. J Adhes Dent 2007;9:209–16. [42] Perdigão J, Geraldeli S, Hodges JS. Total-etch versus self-etch adhesive. Effect on postoperative sensitivity. J Am Dent Assoc 2003;134:1621–9. [43] Poon ECM, Smales RJ, Yip KHK. Clinical evaluation of packable and conventional hybrid posterior resin-based composites. Results at 3.5 years. J Am Dent Assoc 2005;136:1533–40. [44] Ermis RB, Kam O, Celik EU, Temel UB. Clinical evaluation of a two-step etch&rinse and a two-step self-etch adhesive system in class II restorations: two-year results. Oper Dent 2009;34:656–63. [45] Dresch W, Volpato S, Gomes JC, Ribeiro NR, Reis A, Loguercio AD. Clinical evaluation of a nanofilled composite in posterior teeth: 12-month evaluation. Oper Dent 2006;31: 409–17. [46] Palaniappan S, Bharadwaj D, Mattar DL, Peumans M, Van Meerbeek B, Lambrechts P. Three-year randomized clinical trial to evaluate the clinical performance and wear of a nanocomposite versus a hybrid composite. Dent Mater 2009;25:1302–14. [47] Mahmoud SH, El-Embaby AE, Abdallah AM, Hamama HH. Two-year clinical evaluation of ormocer, nanohybrid and nanofill composite restorations in posterior teeth. J Adhes Dent 2008;10:315–22. [48] Hickel R, Roulet J-F, Bayne S, Heintze SD, Mjör IA, Peters M, Rousson V, Randall R, Schmalz G, Tyas M, Vanherle G. Recommendations for conducting controlled clinical studies of dental restorative materials. Clin Oral Investig 2007;11:5–33. [49] Shi L, Wang X, Zhao Q, Zhang Y, Ren Y, Chen Z. Evaluation of packable and conventional hybrid resin composites in class I restorations: three-year results of a randomized, double-blind and controlled clinical trial. Oper Dent 2010;35:11–9.
