THE EFFECT OF THERMOCYCLING ON THE DURABILITY OF DENTIN ADHESIVE SYSTEMS

Young-Hoon Moon; Jong-Ryul Kim; Kyung-Kyu Choi; Sang-Jin Park

doi:10.5395/JKACD.2007.32.3.222

Articles

Page Path: HOME > Restor Dent Endod > Volume 32(3); 2007 > Article

Original Article THE EFFECT OF THERMOCYCLING ON THE DURABILITY OF DENTIN ADHESIVE SYSTEMS: Young-Hoon Moon, Jong-Ryul Kim, Kyung-Kyu Choi, Sang-Jin Park^,*; Journal of Korean Academy of Conservative Dentistry 2007;32(3):222-235.
DOI: https://doi.org/10.5395/JKACD.2007.32.3.222
Published online: January 14, 2007

Department of Conservative Dentistry, Division of Dentistry, Graduate of Kyung Hee University

*Corresponding Author: Sang-Jin Park, Department of Conservative Dentistry, Division of Dentistry, Graduate of Kyung Hee University 1, Hoegi Dong, Dongdaemun Gu, Seoul, Korea, 130-702, Tel: 82-2-958-9335 E-mail: psangjin@khu.ac.kr

• Received: March 2, 2007 • Revised: April 24, 2007 • Accepted: April 30, 2007

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

17 Views
0 Download

prev next

Full Article

Download PDF

Abstract
REFERENCES
참고문헌

Abstract

The objectives of this study was to evaluate the effect of thermocycling on the μTBS (microtensile bond strength) to dentin with four different adhesive systems to examine the bonding durability.

Freshly extracted 3^rd molar teeth were exposed occlusal dentin surfaces, and randomly distributed into 8 adhesive groups: 3-steps total-etching (Scotchbond Multi-Purpose Plus; SM, All Bond-2; AB), 2-steps total-etching (Single Bond; SB, One Step plus; OS), 2-steps self-etching (Clearfil SE Bond; SE, AdheSE; AD) and single-step self-etching systems (Promp L-Pop; PL, Xeno III; XE). Each adhesive system in 8 adhesives groups was applied on prepared dentin surface as an instruction and resin composite (Z250) was placed incrementally and light-cured. The bonded specimens were sectioned with low-speed diamond saw to obtain 1 × 1 ㎜ sticks after 24 hours of storage at 37 °C distilled water and proceeded thermocycling at the pre-determined cycles of 0, 1,000 and 2,000. The μTBS test was carried out with EZ-tester at 1 mm/min. The results of bond strength test were statistically analyzed using one-way ANOVA/ Duncan's test at the α〈 0.05 confidence level. Also, the fracture mode of debonded surface and the interface were examined under SEM.
The results of this study were as follows;
1. 3-step total etching adhesives showed stable, but bond strength of 2-step adhesives were decreased as thermocycling stress.
2. SE showed the highest bond strength, but single step adhesives (PL, XE) had the lowest value both before and after thermocycling.
3. Most of adhesives showed adhesive failure. The total-etching systems were prone to adhesive failure and the single-step systems were mixed failure after thermocycling.
Within limited results of this study, the bond strength of adhesive system was material specific and the bonding durability was affected by the bonding step/ procedure of adhesive. Simplified bonding procedures do not necessarily imply improved bonding performance.
Keywords: Thermocycling; Bond strength; μTBS; Type of solvent; Total-etch; Self-etch

Figure 1.

Specimen preparation for microtensile bond testing. Composite bonding on dentin surface and vertical slice with 1 ㎜ thickness.

Figure 2.

Failure modes of the fractured specimens. A. adhesive failure, B. mixed failure, C. cohesive failure

Figure 3.

Multiple comparison of microtensile bond strength for each adhesive as thermocycling.

Figure 4.

Bar charts showing the microtensile bond strength according to thermocycling for each adhesive type.

A. 3 step adhesive, B. 2 step total-etching adhesive, C. 2 step self-etching adhesive, D. 1 step self-etching adhesive. Vertical bar means the statistical significance in same adhesive.

Figure 5.

Failure modes of the fractured specimens.

Figure 6.

SEM image of interfaces bonded with SM and fractured surfaces.

A,B. Immediate tested specimen. C,D. A specimen after 2,000 thermocycling.

The adhesive resin is not deeply infiltrated into dentinal tubules so that resin tags are blunt, but relative thicker hybrid layer are examined. There is no specific difference between both groups. Both fractured surfaces show adhesive failure at mainly the base of hybrid layer and tubules are occluded by fractured resin tags (HL: Hybrid Layer, C: Composite Resin, RT: Resin Tag, DT: Dentinal Tubule).

Figure 7.

The adhesive interfaces bonded with OS and fractured surface.

A. Immediate tested specimen. Hybrid layer was formed uniformly and resin tags were deeply infiltrated into dentinal tubules so that formed lateral braches. B. A specimen after 2,000 thermocycling. Note some gaps on the top of hybrid layer. C. Mixed failed surface that adhesive failure at the top or bottom of hybrid layer in upper side and cohesive failure of composite in lower side of micrograph (HL: Hybrid Layer, C: Composite Resin, RT: Resin Tag, DT: Dentinal Tubule).

Figure 8.

The adhesive interfaces bonded with AD.

A. Immediate tested specimen. Relative thin hybrid layer that was well integrated without defect was formed uniformly and resin tags were deeply infiltrated into dentinal tubules. B. A specimen after 2,000 thermocycling. Some broken resin tags below hybrid layer were observed though long tags were formed (HL: Hybrid Layer, C: Composite Resin, RT: Resin Tag, DT: Dentinal Tubule).

Figure 9.

SEM image of interfaces bonded with single-step adhesives.

A. Immediate tested specimen bonded with PL. Relative thicker hybrid layer was formed uniformly and well demarcated from adhesive layer and greater number of resin tags were deeply infiltrated into dentinal tubules that was connected each other by lateral braches. B. Fractured surface of PL after 2,000 thermocycling shows adhesive failure that peritubular dentin is remained partially. C. Adhesive failed surface of PL 2,000 group. Adhesive layer is a worm-eaten appearance that allows water movement between the interface and the underlying hydrated dentin. D. A specimen after 2,000 thermocycling. Note some gaps between adhesive layer and top of hybrid layer (HL: Hybrid Layer, C: Composite Resin, RT: Resin Tag, DT: Dentinal Tubule).

Table 1.

The 8 adhesives used in this study

Type	Adhesives(codes)	Composition	Application mode
3-step total etching systems		PrimerA:- NTG-GMA (N(p-tolyl)glycine-glycidyl	a, b1,
		methacrylate), acetone, ethanol, water	c1, e, f
		Primer B:
		BPDM (biphenyl dimethacrylate), photoinitiator, acetone
	All-Bond 2	D/E bonding resin:
	(AB)	Bis-GMA (bisphenol A glycidyl methacrylate),
		UDMA(urethane dimethacrylate), HEMA
		(2-Hydroxyethyl methacrylate),
		CQ (camphorquinone)
	Scotchbond	HEMA, Polyalkenoic acid copolymer,	a, b1,
	MP (SM)	Bis-GMA	c1, e, f
2-step total-etching- systems	One-Step (OS)	Bis-GMA, BPDM, HEMA, Acetone, CQ	a, d,
			c1, e, f
	Single Bond	Bis-GMA, HEMA, Bisphenol A glycerolate	a, d,
	(SB)	dimethacrylate, Water, UDMA, Polyalkenoic	c1, e, f
		acid copolymer, Ethanol
2-step self etching-systems	Clearfil SE	MDP (10-methacryloyloxydecyl dihydrogen phosphate),	b2, d,
	Bond (SE)	HEMA, N,N-Diethanol p-toluidine, water, Bis-GMA,	c2, e, f
		HEMA, N,N-Diethanol p-toluidine, microfiller, CQ
		Phosphoric acid ether acrylate, Hydrolytically stable	b2, d,
	AdheSE(AD)	bisacrylamide, Water, Initiators and stabilizers,	c2, e, f
		Bis-GMA, GDMA (glycerol dimethacrylate), HEMA,
		Highly dispersed silica filler
Single-step self-etching systems	Adper-	Water, stabilizer, parabenes, methacrylated phosphoric	e, d,
	Prompt	acid esters, fluoride complex, photoinitiator BAPO	c2, f
	L-pop (PL)	(bisacylphosphine oxide)
	Xeno III (XE)	Water, ethanol, HEMA, methacryloxyethyl-pyrophosphate,	e, d,
		F-releasing phosphazene, UDMA, micro-filler, CQ	c2, f

a - acid etch for 15 sec and rinse, b1 - primer, b2 - SEP (self-etch primer), c1 - moist surface properly, c2 - dry, d - dwell for 10 – 40 sec, e - adhesive, f - light cure (10sec, 600 mW/cm²

Table 2.

μTBS (㎫, mean ± SD) of each groups before and after thermocycling. Multiple comparison tests were performed within each adhesive type. Same superscript means no statistically difference in each adhesive type at α≤ 0.05 confidence level. TEA: Total etching adhesive, SEA: Self etching adhesive

Adhesive\Thermo cycling	3 step TEA		2 step TEA		2 step SEA		1 step SEA
Adhesive\Thermo cycling	SM	AB	OS	SB	SE	AD	PL	XE
Immediate	34.4 ± 14.4	36.4 ± 12.8	36.9 ± 14.2^c	36.5 ± 9.9^c	48.5 ± 10.2^D	34.1 ± 16.6^B	24.1 ± 8.4^γ	22.4 ± 7.2^γ
1,000 cycles	39.1 ± 11.1	32.1 ± 15.3	33.0 ± 14.1b c	28.4 ± 7.4^ab	44.4 ± 15.0^CD	25.1 ± 6.3^A	21.7 ± 7.9 βγ	15.5 ± 6.9^αβ
2,000 cycles	35.3 ± 15.0	29.6 ± 12.6	26.4 ± 10.4^ab	21.0 ± 8.2^a	36.5 ± 10.1^BC	28.0 ± 7.2^AB	18.7 ± 6.9 αβγ	13.5 ± 9.7^α

REFERENCES

참고문헌

1. Raskin A, Mechotte-Theall B, Vreven J, Wilson NH. Clinical evaluation of a posterior composite 10-year report. J Dent 27:130-19. 1999.Article PubMed
2. Wilder AD, May KN, Bayne SC, Taylor DF, Leinfelder KF. Seventeen year clinical study of ultraviolet-cured posterior composite class I and II restorations. J Esthetic Dent 11:135-142. 1999.Article PubMed
3. Sano H, Takatsu T, Ciucchi B, Horner JA, Matthews WG, Pashley DH. Nanoleakage: leakage within the hybrid layer. Oper Dent 20:18-25. 1995.PubMed
4. Yoshida Y, Van Meerbeeek B, Nakayama Y, Snauwaert J, Hellemans L, Lambrechts P, Vanherle G, Wakasa K. Evidence of chemical bonding at biomateri-al?hard tissue interfaces. J Dent Res 79:709-714. 2000.Article PubMed PDF
5. Primenta LAF, Amaral CM, Bredrane de Castro AKB, Ritter AV. Total-etch, deproteinization and self-etching. Oper Dent 29:592-598. 2004.PubMed
6. Paul SJ, Welter DA, Ghazi M, Pashley D. Nanoleakage at the dentin adhesive-interface vs. microtensile bond strength. Oper Dent 24:181-188. 1999.PubMed
7. Giannini M, Seixas CAM, Reis AF, Pimenta LAF. Six-month storage-time evaluation of one-bottle adhesive systems to dentin. J Esth Rest Dent 15:43-49. 2003.Article PubMed
8. Tay FR, Pashley DH, Yoshiyama M. Two mondes of nanoleakage expression in single-step adhesives. J Dent Res 81:472-476. 2002.Article PubMed PDF
9. Carracho AJL, Chappell RP, Glaros AG, Purk JH, Erick JD. The effect of storage and thermocycling of the shear bond strength of three dental adhesive. Quintessence Int 22:745-752. 1991.PubMed
10. Marshall GW, Marshall SJ, Kinney JH, Balooch M. The dentine substrate: structure-and properties related to bonding. J Dent 25:441-458. 1997.PubMed
11. Ferracane JL, Berge JR, Condon JR. In vitro aging of dental composites in-water-effect of conversion, filler volume, and filler/ matrix coupling. J Biomed-Mater Res 42:465-472. 1998.PubMed
12. Gale MS, Darvel BW. Thermal cycling procedures for laboratory testing of dental restorations. J Dent 27:89-99. 1999.Article PubMed
13. Sano H, Yoshikawa T, Pereira PNR, Kanemura N, Morigami M, Tagami J, Pashley . Long-term Durability of dentine bonds made with a self-etching primer, in vivo. J Dent Res 78:906-911. 1999.PubMed
14. Tanumiharja M, Burrow MF, Tyas MJ. Microtensile bond strengths of seven-dentine adhesive systems. Dent Mater 16:180-187. 2000.PubMed
15. Burrow MF, Satoh M &, Tagami J. Dentin bond durability after three years using a dentin bonding agent with and with-out priming. Dent Mater 12(5):302-307. 1996.Article PubMed
16. Li HP, Burrow MF, Tyas MJ. The effect of long-term storage on nano-leakage. Oper Dent 26:609-616. 2001.PubMed
17. Tay FR, Pashley DH, Suh BI, Carvalho RM, Itthagarun A. Single-step adhesives are permeable membranes. J Dent 30:371-382. 2002.PubMed
18. Kanca 3rd J, Gwinnett AJ. Successful marginal adaptation of a dentin-enamel bonding system in vitro and vivo. J Esthet Dent 6:286-94. 1994.PubMed
19. Nakajima M, Kanemura N, Pereira PN, Tagami J, Pashley DH. Comparative microtensile bond strength and SEM analysis of bonding to wet and dentin. Am J Dent 13:324-8. 2000.PubMed
20. Reis A, Loguercio AD, Carvalho RM, Grande RH. Durability of resin dentin interfaces: effects of surface moisture and adhesive solvent component. Dent Mater 20(7):669-76. 2004.Article PubMed
21. Reis A, Loguercio AD, Azevedo CLN, Carvalho RM, Siger JM, Grande RHM. Moisture spectrum of demineralized dentin for different solvent -based adhesive system. J Adhes Dent 5:183-192. 2003.PubMed
22. Takahashi A, Inoue S, Kawamoto C, Ominato R, Tanaka T, Sato Y, Pereira PNR, Sano H. In vivo longterm durability of the bond to dentin using two adhesive systems. J Adhes Dent 4:151-159. 2002.PubMed
23. Miyazaki M, Sato M, Onose H, Moore BK. Influence of thermal cycling on dentin bond strength of two-step bonding systems. Am J Dent 11:118-122. 1998.PubMed
24. Nikaido T, Kunzelman KH, Chen H, Ogata M, Harada N, Yamaguchi S, Cox CF, Hickel R, Tagami J. Evaluation of thermal cycling and mechanical loading on bond strength of a self-etching primer system to dentin. Dent Mater 18:269-275. 2002.Article PubMed
25. Shirai K, De Munck J, Yoshida Y, Inoue S, Lambrechts P, Suzuki K, Shintani H, van Meerbeek B. Effect of cavity configuration and ageing on the bonding effectiveness of six adhesives to dentin. Dent Mater 21:110-124. 2005.PubMed
26. 조영 곤, 반일 환, 유미 경. 상아질 접착 후 저장기간에 따른 접착 제의 접착력의 변화. 대한치과보존학회지 30(3):204-205. 2006.
27. Kato G, Nakabayashi N. The durability of adhesion to phosphoric acid etched, wet dentine substrates. Dent Mater 14:347-352. 1998.PubMed
28. International Organization for Standardization. ISO TR 11405, Dental materials-guidance on testing of adhesion to tooth structure 1994.
29. Hashimoto M, Ohno H, Kaga M, Endo K, Sano H, Oguchi H. In vivo degradation of resin-dentin bonds in humans over 1 to 3 years. J Dent Res 79:1385-1391. 2000.
30. Fumiaki K, Takafumi O, Tetsuo I, Naoyuki M. Influence of thermal cycles in water on flexural strength of laboratory-processed composite resin. J Oral Rehabil 703-707. 2001.
31. Hakimeh S, Vaidyanathan J, Houpt ML, Vaidyanathan TK, Hagen SV. Microleakage of compomer class V restorations: effect of load cycling, thermal cycling, and cavity shape differences. J Prosthet Dent 83:194-203. 2000.Article PubMed
32. Wendt SL, Mcinnes PM, Dickinson GL. The effect of therm- cycling in microleakage analysis. Dent Mater 8:181-184. 1992.PubMed
33. Krejci I, Lutz F. Mixed class V restorations: the potentials of dentine bonding agent. J Dent 18:263-270. 1990.PubMed
34. Nakajima M, Ogata M, Okuda M, Tagami J, Sano H, Pashley DH. Bonding to caries-affected dentin using self-etching primers. Am J Dent 12:309-314. 1999.PubMed
35. Tay FR, Pashley DH. Dental adhesives of the future. J Adhes Dent 4:91-103. 2002.PubMed
36. De Munck J, Van Landuyt K, Peumans M, Poitevin A, Lambrechts P, Braem M, Van Meerbeek B. A critical review of the durability of adhesion to tooth tissue: methods and results. J Dent Res 84(2):118-32. 2005.Article PubMed PDF
37. Frankenberger R, Strobel WO, Lohbauer U, Kramer N, Petschelt A. The effect of six years of water storage on resin composite bonding to human dentin. J Biomed Mater Res Part B: Appl Biomater 69(1):25-32. 2004.
38. 장 영인, 최 경규, 박 상진. 복합레진에 대한 자가부식형 접착제의 적합성에 관한 연구. 대한치과보존학회지 31(in process) 2006.
39. Armstrong SR, Vargas MA, Fang Q, Laffoon JE. Microtensile bond strength of a total-etch 3-step, total-etch 2-step, self-etch 2-step, and a self-etch 1-step dentin bonding system through 15-month water storage. J Adhes Dent 5:47-56. 2003.PubMed
40. Tay FR, Gwinnett JA, Wei SH. Relation between water content in acetone/alcohol-based primer and interfacial ultrastructure. J Dent 26:147-156. 1998.Article PubMed
41. Choi KK, Condon JR, Ferracane JL. The effects of adhesive thickness on polymerization contraction stress of composite. J Dent Res 79:812-817. 2000.PubMed
42. Yoshida Y, Nagakane K, Fukuda R, Nakayama Y, Okazaki M, Shintani H, Inoue S, Tagawa Y, Suzuki K, De Munck J, Van Meerbeek B. Comparative study on adhesive performance of functional monomers. J Dent Res 83(6):454-8. 2004.Article PubMed PDF
43. Burrow MF, Harada N, Kitasako Y, Nikaido T, Tagami J. Seven-year dentin bond strengths of a total-and self-etch system. Eur J Oral Sci 113(3):265-70. 2005.Article PubMed
44. Brackett MG, Dib A, Brackett WW, Estrada BE, Reyes AA. One-year clinical performance of a resin- modified glass ionomer and a resin composite restorative material in unprepared Class V restorations. Oper Dent 27(2):112-6. 2002.PubMed
45. Tu¨rku¨n SL. Clinical evaluation of a self-etching and a one-bottle adhesive system at two years. J Dent 31:527-534. 2003.PubMed
46. Hashimoto M, Ohno H, Sano H, Kaga M, Oguchi H. Degradation patterns of different adhesives and bonding procedures. J Biomed Mater Res Part B: Appl Biomater 66(1):324-30. 2003.Article PubMed
47. Tay FR, King NM, Suh BI, Pashley DH. Effect of delayed activation of light-cured resin composites on bonding of all-in-one adhesives. J Adhes Dent 3(3):207-25. 2001.PubMed
48. El Zohairy AA, De Gee AJ, Hassan FM, Feilzer AJ. The effect of adhesives with various degrees of hydrophilicity on resin ceramic bond durability. Dent Mater 20:778-787. 2004.Article PubMed
49. Carrilho MR, Carvalho RM, Tay FR, Pashley DH. Effects of storage media on mechanical properties of adhesive systems. Am J Dent 17(2):104-8. 2004.PubMed
50. Yiu CK, King NM, Pashley DH, Suh BI, Carvalho RM, Carrilho MR, Tay FR. Effect of resin hydrophilicity and water storage on resin strength. Biomaterials 25:5789-96. 2004.Article PubMed
51. Yiu CK, King NM, Carrilho MR, Sauro S, Rueggeberg FA, Prati C, Carvalho RM, Pashley DH, Tay FR. Effect of resin hydrophilicity and temperature on water sorption of dental adhesive resins. Biomaterials 27(9):1695-703. 2006.Article PubMed

Tables & Figures

REFERENCES

Citations

Citations to this article as recorded by

ePub Link

Cite

CITE: export Copy Download Format; Close

Download Citation

Download a citation file in RIS format that can be imported by all major citation management software, including EndNote, ProCite, RefWorks, and Reference Manager.

Format:

RIS — For EndNote, ProCite, RefWorks, and most other reference management software
BibTeX — For JabRef, BibDesk, and other BibTeX-specific software

Include:

Citation for the content below
Citation and abstract for the content below

THE EFFECT OF THERMOCYCLING ON THE DURABILITY OF DENTIN ADHESIVE SYSTEMS

J Korean Acad Conserv Dent. 2007;32(3):222-235. Published online January 14, 2007

DOI: https://doi.org/10.5395/JKACD.2007.32.3.222

XML Download

Figure

THE EFFECT OF THERMOCYCLING ON THE DURABILITY OF DENTIN ADHESIVE SYSTEMS

Figure 1. Specimen preparation for microtensile bond testing. Composite bonding on dentin surface and vertical slice with 1 ㎜ thickness.

Figure 2. Failure modes of the fractured specimens. A. adhesive failure, B. mixed failure, C. cohesive failure

Figure 3. Multiple comparison of microtensile bond strength for each adhesive as thermocycling.

Figure 4. Bar charts showing the microtensile bond strength according to thermocycling for each adhesive type.

Figure 5. Failure modes of the fractured specimens.

Figure 6. SEM image of interfaces bonded with SM and fractured surfaces. A,B. Immediate tested specimen. C,D. A specimen after 2,000 thermocycling. The adhesive resin is not deeply infiltrated into dentinal tubules so that resin tags are blunt, but relative thicker hybrid layer are examined. There is no specific difference between both groups. Both fractured surfaces show adhesive failure at mainly the base of hybrid layer and tubules are occluded by fractured resin tags (HL: Hybrid Layer, C: Composite Resin, RT: Resin Tag, DT: Dentinal Tubule).

Figure 7. The adhesive interfaces bonded with OS and fractured surface.

Figure 8. The adhesive interfaces bonded with AD.

Figure 9. SEM image of interfaces bonded with single-step adhesives.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

THE EFFECT OF THERMOCYCLING ON THE DURABILITY OF DENTIN ADHESIVE SYSTEMS

Type	Adhesives(codes)	Composition	Application mode
3-step total etching systems		PrimerA:- NTG-GMA (N(p-tolyl)glycine-glycidyl	a, b1,
		methacrylate), acetone, ethanol, water	c1, e, f
		Primer B:
		BPDM (biphenyl dimethacrylate), photoinitiator, acetone
	All-Bond 2	D/E bonding resin:
	(AB)	Bis-GMA (bisphenol A glycidyl methacrylate),
		UDMA(urethane dimethacrylate), HEMA
		(2-Hydroxyethyl methacrylate),
		CQ (camphorquinone)
	Scotchbond	HEMA, Polyalkenoic acid copolymer,	a, b1,
	MP (SM)	Bis-GMA	c1, e, f
2-step total-etching- systems	One-Step (OS)	Bis-GMA, BPDM, HEMA, Acetone, CQ	a, d,
			c1, e, f
	Single Bond	Bis-GMA, HEMA, Bisphenol A glycerolate	a, d,
	(SB)	dimethacrylate, Water, UDMA, Polyalkenoic	c1, e, f
		acid copolymer, Ethanol
2-step self etching-systems	Clearfil SE	MDP (10-methacryloyloxydecyl dihydrogen phosphate),	b2, d,
	Bond (SE)	HEMA, N,N-Diethanol p-toluidine, water, Bis-GMA,	c2, e, f
		HEMA, N,N-Diethanol p-toluidine, microfiller, CQ
		Phosphoric acid ether acrylate, Hydrolytically stable	b2, d,
	AdheSE(AD)	bisacrylamide, Water, Initiators and stabilizers,	c2, e, f
		Bis-GMA, GDMA (glycerol dimethacrylate), HEMA,
		Highly dispersed silica filler
Single-step self-etching systems	Adper-	Water, stabilizer, parabenes, methacrylated phosphoric	e, d,
	Prompt	acid esters, fluoride complex, photoinitiator BAPO	c2, f
	L-pop (PL)	(bisacylphosphine oxide)
	Xeno III (XE)	Water, ethanol, HEMA, methacryloxyethyl-pyrophosphate,	e, d,
		F-releasing phosphazene, UDMA, micro-filler, CQ	c2, f

Adhesive\Thermo cycling	3 step TEA		2 step TEA		2 step SEA		1 step SEA
Adhesive\Thermo cycling	SM	AB	OS	SB	SE	AD	PL	XE
Immediate	34.4 ± 14.4	36.4 ± 12.8	36.9 ± 14.2^c	36.5 ± 9.9^c	48.5 ± 10.2^D	34.1 ± 16.6^B	24.1 ± 8.4^γ	22.4 ± 7.2^γ
1,000 cycles	39.1 ± 11.1	32.1 ± 15.3	33.0 ± 14.1b c	28.4 ± 7.4^ab	44.4 ± 15.0^CD	25.1 ± 6.3^A	21.7 ± 7.9 βγ	15.5 ± 6.9^αβ
2,000 cycles	35.3 ± 15.0	29.6 ± 12.6	26.4 ± 10.4^ab	21.0 ± 8.2^a	36.5 ± 10.1^BC	28.0 ± 7.2^AB	18.7 ± 6.9 αβγ	13.5 ± 9.7^α

Table 1. The 8 adhesives used in this study

a - acid etch for 15 sec and rinse, b1 - primer, b2 - SEP (self-etch primer), c1 - moist surface properly, c2 - dry, d - dwell for 10 – 40 sec, e - adhesive, f - light cure (10sec, 600 mW/cm²

Table 2. μTBS (㎫, mean ± SD) of each groups before and after thermocycling. Multiple comparison tests were performed within each adhesive type. Same superscript means no statistically difference in each adhesive type at α≤ 0.05 confidence level. TEA: Total etching adhesive, SEA: Self etching adhesive