JJOD 2302 1–7 journal of dentistry xxx (2014) xxx–xxx
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/jden 1 2 3
Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems
4 5
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Jennifer O. Kearns, John G. Barry, Garry J.P. Fleming * Materials Science Unit, Division of Oral Biosciences, Dublin Dental University Hospital, Lincoln Place, Trinity College Dublin, Dublin 2, Ireland
article info
abstract
Article history:
Objectives: To assess the adhesive performance of three universal bonding systems (self-
Received 26 March 2014
etch and total-etch protocols) with cuspal deflection and cervical microleakage score
Received in revised form
protocols.
21 May 2014
Methods: Forty-eight standardised sound maxillary premolar teeth with uniform mesio-
Accepted 23 May 2014
occlusal-distal (MOD) cavities were randomly allocated to six groups. Restoration with resin-
Available online xxx
based composite (RBC) was performed in conjunction with a universal bonding system facilitated by a quartz-tungsten-halogen light-curing-unit. The dependent variable was the
Keywords:
universal bonding protocol (self-etch or total-etch). Buccal and palatal cuspal deflections
Universal bonding systems
were recorded at 0, 30, 60 and 180 s post-irradiation using a twin channel deflection
Resin-based composite
measuring gauge. Following restoration, the teeth subjected to 500 thermocycles, immersed
Cuspal deflection measurement
in a 0.2% basic fuchsin dye for 24 h, sectioned and examined for cervical microleakage.
Cervical microleakage score
Results: Comparing between bonding protocol (self-etch or total-etch), a decrease in total cuspal deflection and a concomitant increase in cervical microleakage were evident when employing the total-etch compared with the self-etch protocol for two of the three universal dental adhesives. Conclusions: The ‘Adhesion-Decalcification concept’ suggests a trend towards ‘mild selfetch’ adhesives. Differences in adhesive performance (cuspal deflection and cervical microleakage) between the teeth restored using the self-etch or total-etch protocols is suggested to be a result of the pH of the self-etch solutions. ‘Mild self-etch’ (pH 2.0) adhesives outperformed ultra-mild (pH > 2.5) or strong (pH < 1.5) self-etch solutions. Clinical significance: Poorly performing adhesives could be identified using the cuspal deflection and cervical microleakage protocol reported which could save the complications encountered clinically with Class II RBC restorations. # 2014 Published by Elsevier Ltd.
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* Corresponding author. Tel.: +353 1 6127371; fax: +353 1 6127297. E-mail address: [email protected] (Garry J.P. Fleming). http://dx.doi.org/10.1016/j.jdent.2014.05.013 0300-5712/# 2014 Published by Elsevier Ltd.
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
JJOD 2302 1–7
2
14
journal of dentistry xxx (2014) xxx–xxx
1.
Introduction
15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
The demand for the aesthetic replacement of natural dentition in the posterior region of the mouth has resulted in increased usage1,2 and teaching3,4 of resin-based composite (RBC) materials worldwide. The disadvantages of RBC restoratives include the increased technique sensitivity and time required to adequately place restorations which can be up to two and a half times longer when compared with nominally identical dental amalgam restorations.5 The acid-etch, wash/dry and light irradiation component steps were reported to account for 86% of the increased time required for RBC restoration placement.6 In an effort to reduce RBC placement times, ‘etch and rinse’ adhesive bonding systems which include a separate etch with acid and rinse step, a priming step followed by the application of the adhesive resin have been simplified by dental adhesive manufacturers.7 Two-step ‘etch and rinse’ adhesives were developed8 and today ‘self-etch’ adhesives which eliminate the rinsing phase have been advocated to significantly reduce RBC placement time.7 However, the effectiveness of self-etch adhesives has been questioned8,9 since simplification of the application procedure with selfetch adhesives was identified (albeit product dependently10) to reduce bond effectiveness.8,9 More recently, a new family of bonding agents known as universal or multi-mode adhesives have been introduced into the dental market and are essentially one-step self-etch adhesives that can be employed with or without a separate etch with acid.11–16 The universal or multi-mode adhesives thereby offer the dentist versatility during RBC restoration placement by the inclusion of monomeric constituents (Table 1) capable of producing chemical adhesion to sound natural dentition.11–16 Previously the authors have used a cuspal deflection and cervical microleakage score protocol to investigate RBC formulations,17–19 placement techniques,20–22 light curing unit (LCU) technologies23,24 and adhesive potential.19 The authors employed similar teeth (size and type), a controlled cavity configuration, RBC and LCU in these studies so that factors including shrinkage on polymerisation,25,26 onset of gelation,27 polymerisation rate,28 RBC elastic modulus26,29 and Cfactor30 could be variously excluded from the analyses. The authors aimed in the current project to use a similar protocol to assess the adhesive performance of three universal bonding system using self-etch and total-etch protocols and the respective RBC formulation advocated by the manufacturers. A conventional self-etch adhesive was used as a control group for the study. The hypothesis proposed was the combination of RBC and universal bonding system protocol (self-etch and total-etch) would significantly impact upon the cuspal deflection measurements recorded and the associated cervical microleakage scores in RBC restored teeth.
64
2.
65 66 67 68
Extracted human maxillary premolars identified to be caries-, hypoplastic defect- and crack-free, were selected for use when the mean of the maximum buccal-palatal-width (BPW) measured 10 mm with a digital micrometre gauge (Mitutoyo,
Materials and methods
Kawasaki, Japan) were within 9.2–9.6 mm. Following handscaling to remove calculus deposits and randomisation, the teeth were distributed into seven groups (n = 8). The teeth were mounted crown uppermost and long axis of the tooth vertical in stainless steel moulds with orthodontic resin (Meadway Rapid Repair, Mr Dental Supplies Ltd., Surrey, UK) extending to within 2 mm of the amelocemental junction (ACJ) prior to cavity preparation under copious water irrigation.17–24 Mesioocclusal-distal (MOD) cavities were prepared with all cavosurface margins at 908 with rounded internal line angles where standardisation of the width of the approximal box (twothirds the BPW), the occlusal isthmus (half the BPW) and the cavity at the occlusal isthmus (3.5 mm from the tip of the palatal cusp and 1 mm above the ACJ at the cervical aspect of the approximal boxes) was checked with the digital micrometre screw gauge (Fig. 1). The prepared teeth were stored in high-purity double distilled water (23 1 8C) prior to preparation for bonding. Following removal from the high-purity double distilled water all teeth were air-dried for 30 s prior to the application of three universal adhesives according to a total-tech or self-etch protocol and a self-etch adhesive to act as a control. The protocols were applied in accordance with the recommendations of the manufacturers outlined in Table 1. RBC restoration was subsequently carried out and involved the oblique incremental placement technique where three triangularshaped increments (2 mm thickness) were performed in the mesial approximal box, three in the distal approximal box and two occlusal increments were also placed. FiltekTM Supreme XTE (Shade A3, Lot No. N438264; 3M ESPE, St. Paul, MN, USA) was used for Groups A and B in addition to Group G (the selfetch control), GrandioSO (Shade A2, Lot no. 1243296; Voco GmbH, Cuxhaven, Germany) for Groups C and E and Spectrum TPH3 (Shade A2, Lot no. 1301000713; Dentsply Caulk, Milford DE, USA) for Groups D and F. The adhesives and RBCs were light irradiated with a quartz tungsten halogen (QTH) light curing unit (LCU) (Optilux 501, Kerr Mfg. Co., Orange, CA, USA) at 660 32 mW cm2 where the output was checked regularly using a radiometer contained within the LCU.
69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107
2.1.
108
Cuspal deflection
The palatal measuring gauge of a twin channel deflection measuring gauge (Twin Channel Analogue Gauge Unit, Thomas Mercer Ltd., St. Alban’s, UK) was placed 2.5 mm from the palatal cusp tip (Fig. 2) prior to recording the baseline cuspal deflection measurement. The buccal and lingual cusps were free to contact the receptors of the measuring gauges by shaping a Tofflemire matrix band around the maxillary teeth. In accordance with a well-defined protocol,17–24 RBC increments were light irradiated (20 s) with the LCU tip maintained at 2 mm above the cusp tips and cuspal deflection measurements were recorded at 0, 30, 60 and 180 s post-irradiation. Beyond 180 s, it was assumed that no cuspal recoil of the buccal and palatal cusp deflections occurred. Eight buccal and eight palatal cusp deflection measurements were recorded for each premolar tooth and sum of the buccal and palatal cusp deflections were calculated. Statistically significant differences31 in mean total cuspal deflection measurements between groups (p < 0.05) were determined using one-way
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
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JJOD 2302 1–7
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journal of dentistry xxx (2014) xxx–xxx
Table 1 – Adhesive composition and application procedure as supplied by the manufacturers.35–38 Group
Adhesive
Composition
Mode
Application procedure employed Tooth surfaces were etched (15 s) with 35% phosphoric acid etching gel (ScotchbondTM Universal Etchant), rinsed with water (20 s) and lightly dried with an air-syringe. Adhesive was rubbed in with a saturated brush tip (20 s), lightly air-dried with a syringe (5 s) and light irradiated (10 s) with a quartz tungsten halogen (QTH) light curing unit (LCU) at 660 32 mW cm2 Adhesive was rubbed in with a saturated brush tip (20 s), lightly air-dried with a syringe (5 s) and light irradiated (10 s) with the QTH LCU at 660 32 mW cm2
A
Scotchbond Universal Adhesive (Lot No. 459407) 3M ESPE, St. Paul, MN, USA
MDP phosphate monomer, Vitrebond copolymer, HEMA, BisGMA, dimethacrylate resins, filler, silane, initiators, ethanol, water
Total etch
B
Scotchbond Universal Adhesive (Lot No. 459407) 3M ESPE, St. Paul, MN, USA
Self etch
C
Prime&Bond Elect Universal Dental Adhesive (Lot no. 120822; Dentsply Caulk, Milford DE, USA)
MDP phosphate monomer, Vitrebond copolymer, HEMA, BisGMA, dimethacrylate resins, filler, silane, initiators, ethanol, water Mono-, di- and tri-methacrylate resins, PENTA (dipentaerythritol penta acrylate monophosphate), diketone, organic phosphine oxide, stabilisers, cetylamine hydrofluoride, acetone, water
D
Prime&Bond Elect Universal Dental Adhesive (Lot no. 120822; Dentsply Caulk, Milford DE, USA)
E
Futurabond U Adhesive (Liquid 1: Lot No. V50609; Liquid 2: (Lot no. V50610; Voco GmbH, Cuxhaven, Germany)
F
Futurabond U Adhesive (Liquid 1: Lot no. V50609; Liquid 2: Lot no. V50610; Voco GmbH, Cuxhaven, Germany)
G
Prompt-L-Pop (Lot no. 453921; 3M ESPE, St. Paul, MN, USA)
Mono-, di- and tri-methacrylate resins, PENTA (dipentaerythritol penta acrylate monophosphate), diketone, organic phosphine oxide, stabilisers, cetylamine hydrofluoride, acetone, water Liquid 1: 2-hydroxyethyl methacrylate, BisGMA, HEDMA, acidic adhesive monomer, UDMA, catalyst Liquid 2: ethanol, initiator, catalyst
Liquid 1: 2-hydroxyethyl methacrylate, BisGMA, HEDMA, acidic adhesive monomer, UDMA, catalyst Liquid 2: ethanol, initiator, catalyst Methacrylated phosphoric esters, BisGMA, initiators, stabilisers, water, 2-hydroxyethyl methacrylate, polyalkenoic acid
127 128
analyses of variance (ANOVA) and post hoc Tukey’s tests using SPSS 12.0.1 software (SPSS Inc., Chicago, IL, USA).
129
2.2.
130 131 132 133 134 135 136
The restored teeth were finished with Sof-Lex Finishing discs (3M ESPE, St. Paul, MN, USA) and 15 mm grit Composhape finishing diamond burs (Intensiv, Viganello-Lugano, Switzerland) with a slow hand-piece under water. Root apices were sealed with sticky wax, tooth surfaces sealed with nail varnish (Rimmel 60 Seconds, London, UK) except for a 1 mm band around the restoration margins and the teeth were
Cervical microleakage assessment
Total etch
Self etch
Total etch
Self etch
Self etch
Tooth surfaces were acid etched for 15 s with Vococid1, rinsed with water (20 s) and lightly dried. Prime&Bond Elect Universal Dental Adhesive was applied with a saturated brush tip, lightly dried (5 s) and light irradiated with the QTH LCU (10 s). Prime&Bond Elect Universal Dental Adhesive was applied with a saturated brush tip, lightly dried (5 s) and light irradiated (10 s) with the QTH LCU.
Tooth surfaces were acid etched for 15 s with Vococid1, rinsed with water (20 s) and lightly dried. An equal mixture of Futurabond U Adhesive Liquid 1 and Liquid 2 was mixed. Adhesive application with a saturated brush tip, lightly dried (5 s) and light irradiated with the QTH LCU (10 s). An equal mixture of Futurabond U Adhesive Liquid 1 and Liquid 2 was mixed. Adhesive application with a saturated brush tip, lightly dried (5 s) and light irradiated with the QTH LCU (10 s). The blister pack was activated, the adhesive ‘massaged’ onto the tooth surfaces (15 s), dried thoroughly, a second adhesive coat ‘massaged’ (15 s), dried under an air stream and light irradiated with the QTH LCU for 10 s.
thermocycled between two water-baths maintained at 4 1 and 65 1 8C.32 Following 500 cycles33 of submerging the teeth for 10 s in each water-bath (with a 25 s transfer between water-baths), all teeth were immersed in 0.2% basic fuchsin dye for 24 h and sectioned mid-sagitally in the mesio-distal plane at 125 rpm using a ceramic cutting disc (Struers, Glasgow, Scotland). The sectioned teeth were examined under a stereo-microscope (Wild M3C, Heerburg, Switzerland) at 25 magnification and the extent of the cervical microleakage was recorded.17–24 A score of: ‘00 – no evidence of dye penetration; ‘10 – superficial dye penetration not beyond the ADJ; ‘20 – dye penetration along the gingival floor and up to the axial wall; ‘30
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
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JJOD 2302 1–7
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journal of dentistry xxx (2014) xxx–xxx
Fig. 1 – Schematic representation of the mesio-occlusaldistal (MOD) cavity (C) utilised. The buccal-palatal-width (BPW) of the proximal boxes of the cavity were cut to two thirds of the buccal-lingual-width (B) from the buccal to the palatal cusp. The occlusal isthmus (A) was prepared to half the buccal-lingual-width of the tooth and the cavity depth of the isthmus was standardised to 3.5 W 0.1 mm from the tip of the palatal cusp and to 1.0 W 0.1 mm above the ACJ at the cervical aspect of the proximal boxes.
149 150 151 152 153 154 155 156
– dye penetration along the axial wall and across the pulpal floor and ‘40 – dye penetration into the pulp chamber from the pulpal floor. Statistically significant differences31 in cervical microleakage scores (p < 0.05) were assessed using nonparametric Kruskal–Wallis tests followed by paired Mann– Whitney U tests group comparisons facilitated by the SPSS software.
3.
Results
3.1.
Cuspal deflection
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The recorded mean total cuspal deflection measurements and associated standard deviations for the RBC/universal adhesive combinations placed according to self-etch or total-etch protocols and the self-etch (control) adhesive tested in the study are outlined in Table 2. The homogeneity of the
Fig. 2 – The placement of the teeth fixed approximately 2.5 mm from the palatal cusp tip where the buccal and lingual cusps of the extracted teeth were approximated to the receptors of a twin channel deflection-measuring gauge.
variances of the deflection measurements were tested using Levene statistics (p > 0.232) while statistically significant differences in mean total cuspal deflection measurements (p < 0.001) were identified between the groups tested (Groups A–G). Comparing between bonding protocol (total-etch or selfetch), no statistically significant differences in total cuspal deflection were evident for FiltekTM Supreme XTE/ScotchbondTM Universal Adhesive (p = 0.139), GrandioSO/Fururabond U Adhesive (p = 1.000) but a significant increase in total cuspal deflection was observed for Spectrum TPH3/Prime & Bond Elect Universal Dental Adhesive when employing the totaletch (p = 0.013) compared with the self-etch protocol (Table 2).
163 164 165 166 167 168 169 170 171 172 173 174
3.2.
175
Cervical microleakage assessment
The Kruskal–Wallis non-parametric test of the cervical microleakage scores revealed a significant difference between Groups A and G ( p < 0.001). The cervical microleakage scores recorded for the RBCs placed in conjunction with the appropriate bonding systems (total-etch or self-etch protocols) are presented using a box and whisker plot (Fig. 3). The median cervical microleakage score is indicated by the bold black line across the box, the whiskers represent the highest and lowest cervical microleakage scores recorded while the
Table 2 – Mean total cuspal deflection measurements for the RBC/Adhesive combinations employed in the current study. Statistical significance across the mean cuspal deflection data highlighted by different upper case letters imply significant differences at p < 0.05. Group A B C D E F G
RBC
Adhesive
Mode
Mean cuspal deflection (mm)
Filtek Supreme Filtek Supreme Spectrum TPH3 Spectrum TPH3 GrandioSO GrandioSO Filtek Supreme
ScotchbondTM Universal ScotchbondTM Universal Prime&Bond Elect Universal Prime&Bond Elect Universal Futurabond U Futurabond U AdperTM PromptTM L-PopTM
Total-etch Self-etch Total-etch Self-etch Total-etch Self-etch Self-etch
13.0 2.5A 10.2 2.9A 12.3 2.3A 8.4 1.9B 10.0 2.1A 10.3 1.6A 7.4 1.8B
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
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JJOD 2302 1–7 journal of dentistry xxx (2014) xxx–xxx
Fig. 3 – A box and whisker plot of the cervical microleakage scores of the MOD cavities (n = 8 for each group tested). The plot illustrates a summary of the cervical microleakage scores based on the median, quartiles, and extreme values. The box represents the inter-quartile range which contains 50% of the cervical microleakage scores, the whiskers represent the highest and lowest cervical microleakage scores and the bold black line across the box indicates the median cervical microleakage score for the self-etch (SE) and total-etch (TE) protocols.
185 186 187 188 189 190 191 192 193
box contain 50% of the values, namely the inter-quartile range. Comparing between bonding protocol (total-etch or self-etch), statistically significant increases in cervical microleakage scores were evident for FiltekTM Supreme XTE/ScotchbondTM Universal Adhesive (p = 0.015) and Spectrum TPH3/Prime&Bond Elect Universal Dental Adhesive (p = 0.031) in self-etch modes. However, no statistically significant differences were observed for GrandioSO/Futurabond U Adhesive (p = 0.721) under self-etch and total-etch protocols.
194
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In the reported study, the mean BPW of the human maxillary premolar teeth were standardised ( 2.5) with a dentine interaction depth of
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/jden 1 2 3
Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems
4 5
6 7 8
Q1
Jennifer O. Kearns, John G. Barry, Garry J.P. Fleming * Materials Science Unit, Division of Oral Biosciences, Dublin Dental University Hospital, Lincoln Place, Trinity College Dublin, Dublin 2, Ireland
article info
abstract
Article history:
Objectives: To assess the adhesive performance of three universal bonding systems (self-
Received 26 March 2014
etch and total-etch protocols) with cuspal deflection and cervical microleakage score
Received in revised form
protocols.
21 May 2014
Methods: Forty-eight standardised sound maxillary premolar teeth with uniform mesio-
Accepted 23 May 2014
occlusal-distal (MOD) cavities were randomly allocated to six groups. Restoration with resin-
Available online xxx
based composite (RBC) was performed in conjunction with a universal bonding system facilitated by a quartz-tungsten-halogen light-curing-unit. The dependent variable was the
Keywords:
universal bonding protocol (self-etch or total-etch). Buccal and palatal cuspal deflections
Universal bonding systems
were recorded at 0, 30, 60 and 180 s post-irradiation using a twin channel deflection
Resin-based composite
measuring gauge. Following restoration, the teeth subjected to 500 thermocycles, immersed
Cuspal deflection measurement
in a 0.2% basic fuchsin dye for 24 h, sectioned and examined for cervical microleakage.
Cervical microleakage score
Results: Comparing between bonding protocol (self-etch or total-etch), a decrease in total cuspal deflection and a concomitant increase in cervical microleakage were evident when employing the total-etch compared with the self-etch protocol for two of the three universal dental adhesives. Conclusions: The ‘Adhesion-Decalcification concept’ suggests a trend towards ‘mild selfetch’ adhesives. Differences in adhesive performance (cuspal deflection and cervical microleakage) between the teeth restored using the self-etch or total-etch protocols is suggested to be a result of the pH of the self-etch solutions. ‘Mild self-etch’ (pH 2.0) adhesives outperformed ultra-mild (pH > 2.5) or strong (pH < 1.5) self-etch solutions. Clinical significance: Poorly performing adhesives could be identified using the cuspal deflection and cervical microleakage protocol reported which could save the complications encountered clinically with Class II RBC restorations. # 2014 Published by Elsevier Ltd.
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14
* Corresponding author. Tel.: +353 1 6127371; fax: +353 1 6127297. E-mail address: [email protected] (Garry J.P. Fleming). http://dx.doi.org/10.1016/j.jdent.2014.05.013 0300-5712/# 2014 Published by Elsevier Ltd.
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
JJOD 2302 1–7
2
14
journal of dentistry xxx (2014) xxx–xxx
1.
Introduction
15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
The demand for the aesthetic replacement of natural dentition in the posterior region of the mouth has resulted in increased usage1,2 and teaching3,4 of resin-based composite (RBC) materials worldwide. The disadvantages of RBC restoratives include the increased technique sensitivity and time required to adequately place restorations which can be up to two and a half times longer when compared with nominally identical dental amalgam restorations.5 The acid-etch, wash/dry and light irradiation component steps were reported to account for 86% of the increased time required for RBC restoration placement.6 In an effort to reduce RBC placement times, ‘etch and rinse’ adhesive bonding systems which include a separate etch with acid and rinse step, a priming step followed by the application of the adhesive resin have been simplified by dental adhesive manufacturers.7 Two-step ‘etch and rinse’ adhesives were developed8 and today ‘self-etch’ adhesives which eliminate the rinsing phase have been advocated to significantly reduce RBC placement time.7 However, the effectiveness of self-etch adhesives has been questioned8,9 since simplification of the application procedure with selfetch adhesives was identified (albeit product dependently10) to reduce bond effectiveness.8,9 More recently, a new family of bonding agents known as universal or multi-mode adhesives have been introduced into the dental market and are essentially one-step self-etch adhesives that can be employed with or without a separate etch with acid.11–16 The universal or multi-mode adhesives thereby offer the dentist versatility during RBC restoration placement by the inclusion of monomeric constituents (Table 1) capable of producing chemical adhesion to sound natural dentition.11–16 Previously the authors have used a cuspal deflection and cervical microleakage score protocol to investigate RBC formulations,17–19 placement techniques,20–22 light curing unit (LCU) technologies23,24 and adhesive potential.19 The authors employed similar teeth (size and type), a controlled cavity configuration, RBC and LCU in these studies so that factors including shrinkage on polymerisation,25,26 onset of gelation,27 polymerisation rate,28 RBC elastic modulus26,29 and Cfactor30 could be variously excluded from the analyses. The authors aimed in the current project to use a similar protocol to assess the adhesive performance of three universal bonding system using self-etch and total-etch protocols and the respective RBC formulation advocated by the manufacturers. A conventional self-etch adhesive was used as a control group for the study. The hypothesis proposed was the combination of RBC and universal bonding system protocol (self-etch and total-etch) would significantly impact upon the cuspal deflection measurements recorded and the associated cervical microleakage scores in RBC restored teeth.
64
2.
65 66 67 68
Extracted human maxillary premolars identified to be caries-, hypoplastic defect- and crack-free, were selected for use when the mean of the maximum buccal-palatal-width (BPW) measured 10 mm with a digital micrometre gauge (Mitutoyo,
Materials and methods
Kawasaki, Japan) were within 9.2–9.6 mm. Following handscaling to remove calculus deposits and randomisation, the teeth were distributed into seven groups (n = 8). The teeth were mounted crown uppermost and long axis of the tooth vertical in stainless steel moulds with orthodontic resin (Meadway Rapid Repair, Mr Dental Supplies Ltd., Surrey, UK) extending to within 2 mm of the amelocemental junction (ACJ) prior to cavity preparation under copious water irrigation.17–24 Mesioocclusal-distal (MOD) cavities were prepared with all cavosurface margins at 908 with rounded internal line angles where standardisation of the width of the approximal box (twothirds the BPW), the occlusal isthmus (half the BPW) and the cavity at the occlusal isthmus (3.5 mm from the tip of the palatal cusp and 1 mm above the ACJ at the cervical aspect of the approximal boxes) was checked with the digital micrometre screw gauge (Fig. 1). The prepared teeth were stored in high-purity double distilled water (23 1 8C) prior to preparation for bonding. Following removal from the high-purity double distilled water all teeth were air-dried for 30 s prior to the application of three universal adhesives according to a total-tech or self-etch protocol and a self-etch adhesive to act as a control. The protocols were applied in accordance with the recommendations of the manufacturers outlined in Table 1. RBC restoration was subsequently carried out and involved the oblique incremental placement technique where three triangularshaped increments (2 mm thickness) were performed in the mesial approximal box, three in the distal approximal box and two occlusal increments were also placed. FiltekTM Supreme XTE (Shade A3, Lot No. N438264; 3M ESPE, St. Paul, MN, USA) was used for Groups A and B in addition to Group G (the selfetch control), GrandioSO (Shade A2, Lot no. 1243296; Voco GmbH, Cuxhaven, Germany) for Groups C and E and Spectrum TPH3 (Shade A2, Lot no. 1301000713; Dentsply Caulk, Milford DE, USA) for Groups D and F. The adhesives and RBCs were light irradiated with a quartz tungsten halogen (QTH) light curing unit (LCU) (Optilux 501, Kerr Mfg. Co., Orange, CA, USA) at 660 32 mW cm2 where the output was checked regularly using a radiometer contained within the LCU.
69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107
2.1.
108
Cuspal deflection
The palatal measuring gauge of a twin channel deflection measuring gauge (Twin Channel Analogue Gauge Unit, Thomas Mercer Ltd., St. Alban’s, UK) was placed 2.5 mm from the palatal cusp tip (Fig. 2) prior to recording the baseline cuspal deflection measurement. The buccal and lingual cusps were free to contact the receptors of the measuring gauges by shaping a Tofflemire matrix band around the maxillary teeth. In accordance with a well-defined protocol,17–24 RBC increments were light irradiated (20 s) with the LCU tip maintained at 2 mm above the cusp tips and cuspal deflection measurements were recorded at 0, 30, 60 and 180 s post-irradiation. Beyond 180 s, it was assumed that no cuspal recoil of the buccal and palatal cusp deflections occurred. Eight buccal and eight palatal cusp deflection measurements were recorded for each premolar tooth and sum of the buccal and palatal cusp deflections were calculated. Statistically significant differences31 in mean total cuspal deflection measurements between groups (p < 0.05) were determined using one-way
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126
JJOD 2302 1–7
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journal of dentistry xxx (2014) xxx–xxx
Table 1 – Adhesive composition and application procedure as supplied by the manufacturers.35–38 Group
Adhesive
Composition
Mode
Application procedure employed Tooth surfaces were etched (15 s) with 35% phosphoric acid etching gel (ScotchbondTM Universal Etchant), rinsed with water (20 s) and lightly dried with an air-syringe. Adhesive was rubbed in with a saturated brush tip (20 s), lightly air-dried with a syringe (5 s) and light irradiated (10 s) with a quartz tungsten halogen (QTH) light curing unit (LCU) at 660 32 mW cm2 Adhesive was rubbed in with a saturated brush tip (20 s), lightly air-dried with a syringe (5 s) and light irradiated (10 s) with the QTH LCU at 660 32 mW cm2
A
Scotchbond Universal Adhesive (Lot No. 459407) 3M ESPE, St. Paul, MN, USA
MDP phosphate monomer, Vitrebond copolymer, HEMA, BisGMA, dimethacrylate resins, filler, silane, initiators, ethanol, water
Total etch
B
Scotchbond Universal Adhesive (Lot No. 459407) 3M ESPE, St. Paul, MN, USA
Self etch
C
Prime&Bond Elect Universal Dental Adhesive (Lot no. 120822; Dentsply Caulk, Milford DE, USA)
MDP phosphate monomer, Vitrebond copolymer, HEMA, BisGMA, dimethacrylate resins, filler, silane, initiators, ethanol, water Mono-, di- and tri-methacrylate resins, PENTA (dipentaerythritol penta acrylate monophosphate), diketone, organic phosphine oxide, stabilisers, cetylamine hydrofluoride, acetone, water
D
Prime&Bond Elect Universal Dental Adhesive (Lot no. 120822; Dentsply Caulk, Milford DE, USA)
E
Futurabond U Adhesive (Liquid 1: Lot No. V50609; Liquid 2: (Lot no. V50610; Voco GmbH, Cuxhaven, Germany)
F
Futurabond U Adhesive (Liquid 1: Lot no. V50609; Liquid 2: Lot no. V50610; Voco GmbH, Cuxhaven, Germany)
G
Prompt-L-Pop (Lot no. 453921; 3M ESPE, St. Paul, MN, USA)
Mono-, di- and tri-methacrylate resins, PENTA (dipentaerythritol penta acrylate monophosphate), diketone, organic phosphine oxide, stabilisers, cetylamine hydrofluoride, acetone, water Liquid 1: 2-hydroxyethyl methacrylate, BisGMA, HEDMA, acidic adhesive monomer, UDMA, catalyst Liquid 2: ethanol, initiator, catalyst
Liquid 1: 2-hydroxyethyl methacrylate, BisGMA, HEDMA, acidic adhesive monomer, UDMA, catalyst Liquid 2: ethanol, initiator, catalyst Methacrylated phosphoric esters, BisGMA, initiators, stabilisers, water, 2-hydroxyethyl methacrylate, polyalkenoic acid
127 128
analyses of variance (ANOVA) and post hoc Tukey’s tests using SPSS 12.0.1 software (SPSS Inc., Chicago, IL, USA).
129
2.2.
130 131 132 133 134 135 136
The restored teeth were finished with Sof-Lex Finishing discs (3M ESPE, St. Paul, MN, USA) and 15 mm grit Composhape finishing diamond burs (Intensiv, Viganello-Lugano, Switzerland) with a slow hand-piece under water. Root apices were sealed with sticky wax, tooth surfaces sealed with nail varnish (Rimmel 60 Seconds, London, UK) except for a 1 mm band around the restoration margins and the teeth were
Cervical microleakage assessment
Total etch
Self etch
Total etch
Self etch
Self etch
Tooth surfaces were acid etched for 15 s with Vococid1, rinsed with water (20 s) and lightly dried. Prime&Bond Elect Universal Dental Adhesive was applied with a saturated brush tip, lightly dried (5 s) and light irradiated with the QTH LCU (10 s). Prime&Bond Elect Universal Dental Adhesive was applied with a saturated brush tip, lightly dried (5 s) and light irradiated (10 s) with the QTH LCU.
Tooth surfaces were acid etched for 15 s with Vococid1, rinsed with water (20 s) and lightly dried. An equal mixture of Futurabond U Adhesive Liquid 1 and Liquid 2 was mixed. Adhesive application with a saturated brush tip, lightly dried (5 s) and light irradiated with the QTH LCU (10 s). An equal mixture of Futurabond U Adhesive Liquid 1 and Liquid 2 was mixed. Adhesive application with a saturated brush tip, lightly dried (5 s) and light irradiated with the QTH LCU (10 s). The blister pack was activated, the adhesive ‘massaged’ onto the tooth surfaces (15 s), dried thoroughly, a second adhesive coat ‘massaged’ (15 s), dried under an air stream and light irradiated with the QTH LCU for 10 s.
thermocycled between two water-baths maintained at 4 1 and 65 1 8C.32 Following 500 cycles33 of submerging the teeth for 10 s in each water-bath (with a 25 s transfer between water-baths), all teeth were immersed in 0.2% basic fuchsin dye for 24 h and sectioned mid-sagitally in the mesio-distal plane at 125 rpm using a ceramic cutting disc (Struers, Glasgow, Scotland). The sectioned teeth were examined under a stereo-microscope (Wild M3C, Heerburg, Switzerland) at 25 magnification and the extent of the cervical microleakage was recorded.17–24 A score of: ‘00 – no evidence of dye penetration; ‘10 – superficial dye penetration not beyond the ADJ; ‘20 – dye penetration along the gingival floor and up to the axial wall; ‘30
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
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JJOD 2302 1–7
4
journal of dentistry xxx (2014) xxx–xxx
Fig. 1 – Schematic representation of the mesio-occlusaldistal (MOD) cavity (C) utilised. The buccal-palatal-width (BPW) of the proximal boxes of the cavity were cut to two thirds of the buccal-lingual-width (B) from the buccal to the palatal cusp. The occlusal isthmus (A) was prepared to half the buccal-lingual-width of the tooth and the cavity depth of the isthmus was standardised to 3.5 W 0.1 mm from the tip of the palatal cusp and to 1.0 W 0.1 mm above the ACJ at the cervical aspect of the proximal boxes.
149 150 151 152 153 154 155 156
– dye penetration along the axial wall and across the pulpal floor and ‘40 – dye penetration into the pulp chamber from the pulpal floor. Statistically significant differences31 in cervical microleakage scores (p < 0.05) were assessed using nonparametric Kruskal–Wallis tests followed by paired Mann– Whitney U tests group comparisons facilitated by the SPSS software.
3.
Results
3.1.
Cuspal deflection
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158 159 160 161 162
The recorded mean total cuspal deflection measurements and associated standard deviations for the RBC/universal adhesive combinations placed according to self-etch or total-etch protocols and the self-etch (control) adhesive tested in the study are outlined in Table 2. The homogeneity of the
Fig. 2 – The placement of the teeth fixed approximately 2.5 mm from the palatal cusp tip where the buccal and lingual cusps of the extracted teeth were approximated to the receptors of a twin channel deflection-measuring gauge.
variances of the deflection measurements were tested using Levene statistics (p > 0.232) while statistically significant differences in mean total cuspal deflection measurements (p < 0.001) were identified between the groups tested (Groups A–G). Comparing between bonding protocol (total-etch or selfetch), no statistically significant differences in total cuspal deflection were evident for FiltekTM Supreme XTE/ScotchbondTM Universal Adhesive (p = 0.139), GrandioSO/Fururabond U Adhesive (p = 1.000) but a significant increase in total cuspal deflection was observed for Spectrum TPH3/Prime & Bond Elect Universal Dental Adhesive when employing the totaletch (p = 0.013) compared with the self-etch protocol (Table 2).
163 164 165 166 167 168 169 170 171 172 173 174
3.2.
175
Cervical microleakage assessment
The Kruskal–Wallis non-parametric test of the cervical microleakage scores revealed a significant difference between Groups A and G ( p < 0.001). The cervical microleakage scores recorded for the RBCs placed in conjunction with the appropriate bonding systems (total-etch or self-etch protocols) are presented using a box and whisker plot (Fig. 3). The median cervical microleakage score is indicated by the bold black line across the box, the whiskers represent the highest and lowest cervical microleakage scores recorded while the
Table 2 – Mean total cuspal deflection measurements for the RBC/Adhesive combinations employed in the current study. Statistical significance across the mean cuspal deflection data highlighted by different upper case letters imply significant differences at p < 0.05. Group A B C D E F G
RBC
Adhesive
Mode
Mean cuspal deflection (mm)
Filtek Supreme Filtek Supreme Spectrum TPH3 Spectrum TPH3 GrandioSO GrandioSO Filtek Supreme
ScotchbondTM Universal ScotchbondTM Universal Prime&Bond Elect Universal Prime&Bond Elect Universal Futurabond U Futurabond U AdperTM PromptTM L-PopTM
Total-etch Self-etch Total-etch Self-etch Total-etch Self-etch Self-etch
13.0 2.5A 10.2 2.9A 12.3 2.3A 8.4 1.9B 10.0 2.1A 10.3 1.6A 7.4 1.8B
Please cite this article in press as: Kearns JO, et al. Cuspal deflection and cervical microleakage scores to determine the adhesive potential of universal bonding systems. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.05.013
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JJOD 2302 1–7 journal of dentistry xxx (2014) xxx–xxx
Fig. 3 – A box and whisker plot of the cervical microleakage scores of the MOD cavities (n = 8 for each group tested). The plot illustrates a summary of the cervical microleakage scores based on the median, quartiles, and extreme values. The box represents the inter-quartile range which contains 50% of the cervical microleakage scores, the whiskers represent the highest and lowest cervical microleakage scores and the bold black line across the box indicates the median cervical microleakage score for the self-etch (SE) and total-etch (TE) protocols.
185 186 187 188 189 190 191 192 193
box contain 50% of the values, namely the inter-quartile range. Comparing between bonding protocol (total-etch or self-etch), statistically significant increases in cervical microleakage scores were evident for FiltekTM Supreme XTE/ScotchbondTM Universal Adhesive (p = 0.015) and Spectrum TPH3/Prime&Bond Elect Universal Dental Adhesive (p = 0.031) in self-etch modes. However, no statistically significant differences were observed for GrandioSO/Futurabond U Adhesive (p = 0.721) under self-etch and total-etch protocols.
194
4.
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In the reported study, the mean BPW of the human maxillary premolar teeth were standardised ( 2.5) with a dentine interaction depth of
