PorovnaÂnõÂ vazebneâ sõâlyadheziv pouzïõâvanyâ ch v ortodoncii Comparative studyof bond strength in adhesives used in orthodontics

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PorovnaÂnõ vazebne sõÂlyadheziv pouzÏõÂvanyÂch v ortodoncii

Comparative studyof bond strength in adhesives used

in orthodontics

*Bartøomiej Pawlus, **Dr n. med., Dr n. tech. Andrzej Dyszkiewicz, *Doc. MUDr MilosÏ SÏpidlen, Ph.D. *Ortodonticke oddeÏlenõ Kliniky zubnõÂho leÂkarÏstvõ LF UP Olomouc, CÏeska Republika

*Department of Orthodontics, Clinic of Dental Medicine, Medical Faculty of Palacky University, Olomouc, Czech Republic

**Institut Fyzioterapie Opolske Polytechniky, Laboratorium BiotechnologieªLabiotª, Cieszyn, Polsko **Institute of Physiotherapy, Opole Polytechnics, Laboratorium Biotechnologie ªLabiotª, Cieszyn, Poland

Souhrn

CõÂl:CõÂlem praÂce bylo porovnaÂnõ a hodnocenõ pevnosti adheziv vyuzÏõÂvanyÂch k lepenõ ortodontickyÂch zaÂmkuÊ. Metodika:Celkem bylo hodnoceno 11 adheziv. DaÂle bylo kvantitativneÏ hodnoceno mnozÏstvõ ponechaneÂho adheziva na povrchu skloviny prostrÏednictvõÂm ukazatele ARI - Adhesive Remnant Index. Studie byla provedena na 330 extrahovanyÂch premolaÂrech rozdeÏlenyÂch do 11 skupin podle druhu adheziva po 30 vzorcõÂch. Pevnost vazby byla zkoumaÂna pro kazÏde adhezivum ve smyku, tahu a krutu. Ke studii byly pouzÏity kovove zaÂmky RMOIn-tegra. Byl stanoven Adhesive Remnant Index pro testovana adheziva.

VyÂsledky:StrÏednõÂ hodnoty ve smyku meÏl nejvysÏsÏõÂ Transbond XT, nejnizÏsÏõÂ zõÂskal No-Mix Dentaurum. StrÏednõÂ hodnoty v tahu meÏl nejvysÏsÏõÂ Medicept Light Cure, nejnizÏsÏõÂ zõÂskal Tetric flow. StrÏednõÂ hodnoty v krutu meÏl nejvysÏsÏõÂ Light Bond Reliance, nejnizÏsÏõÂ zõÂskal Granitec Falcon(Ortodoncie 2012, 21, cÏ. 1, s. 16-23).

Abstract

Aim:The aim was to compare and evaluate bond strength of adhesives used for orthodontic brackets atta-chment.

Method:11 different adhesives were tested. The amount of adhesive left on the enamel surface was quanti-tatively evaluated with ARI (Adhesive Remnant Index). The study included 330 extracted premolars classified into 11 groups (30 samples each) according to the type of adhesive. Bond strength of each adhesive was evaluated by shear, tensile, and torsion test. Metal brackets RMOIntegra were used. Adhesive Remnant Index was set for the adhesives tested.

Results:The highest mean values in shear test were found for Transbond XT, the lowest for No-Mix Dentau-rum. The highest mean values in tensile test were found for Medicept Light Cure, the lowest for Tetric flow. The highest mean values in torsion test were found for Light Bond Reliance, the lowest for Granitec Falcon(Ortodoncie 2012, 21, No. 1, p. 16-23).

KlõÂcÏova slova:adheziva v ortodoncii, hodnocenõ v tahu, smyku, krutu, pevnost vazby

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Introduction

The advancement and development of new adhe-sive materials for the attachment of brackets to enamel have a significant impact on the orthodontic treatment with fixed appliances [1,2]. Adhesive materials should resist to the force used during the treatment that is transferred on the teeth by means of orthodontic brac-kets, as well as to the force applied in normal mastica-tion.

A rather frequent problem occurring during the orthodontic treatment with fixed appliance seems to be the bond failure of brackets due to careless bite, in-correct technique of the brackets attachment, or due to the enamelstructure which cannot be etched cor-rectly [3]. Another problem is represented by an exces-sive adheexces-sive bond strength (over 10 MPa) that may sult in the enamel prism pull-off during the brackets re-moval[4,5]. Bishara says the bond strength below 12.75 MPa is optimum and safe during the ceramic brackets detachment [6]. Laboratory research focused on the values of bond strength between an orthodontic bracket and a tooth proved that sufficient adhesion of fixed appliances is secured by the strength between 5.8 and 7.8 MPa [7]. The shear strength of 1 to 3 MPa, originating during the treatment, should not re-sult in the detachment of orthodontic components [8,9].

However, we should remember that the tensile strengths within the complex enamel-adhesive-brac-ket, occurring during mastication, may be greater.

Knowledge of characteristics of individual adhesive materials is of a great help in the selection of appro-priate adhesives for different clinical cases. The bond strength depends on the adhesive materialused as well as on the bracket base, enamel surface, and the technique of attachment.

The aim of our study was to compare and evaluate bond strength of adhesives used for the attachment of orthodontic brackets. The amount of adhesive rem-nant on the enamelsurface was evaluated quantitati-vely with help of ARI (Adhesive Remnant Index) [10].

Material and method

The following adhesive materials were tested: Composite resins: Transbond XT (3M), Medicept Light Cure (Medicept Dental), Resilience (Ortho Tech-nology), Light Bond (Reliance), Enlight (Ormco), No-Mix (Dentaurum), Tetric Flow (Vivadent), ConTec Prime (Denaturum), Granitec (Falcon), acrylate resin Spofac-ryl (Spofa Dental), glass-ionomer cement Fuji ORTHO LC (GC).

Samples were prepared in the following way: 330 extracted premolars were disinfected with Incidin li-quid and propanol(with the exception of enamelsur-UÂvod

Pokrok a rozvoj novyÂch adhezivnõÂch materiaÂl uÊ k prÏi-pevneÏnõ zaÂmkuÊ na zubnõ sklovineÏ vyÂznamneÏ ovlivnil mozÏnost ortodonticke l eÂcÏby fixnõÂmi aparaÂty [1, 2]. Ad-hezivnõ materiaÂl musõ odolat sõÂle pouzÏõÂvane v l eÂcÏenõÂ, ktera je prÏenaÂsÏena na zuby prostrÏednictvõÂm ortodon-tickyÂch zaÂmkuÊ, ale i sõÂle, vznikajõÂcõ prÏi beÏzÏnyÂch zÏvyÂka-cõÂch pohybech.

CÏastou potõÂzÏõÂ, ktera se vyskytuje v pruÊbeÏhu orto-donticke l eÂcÏby fixnõÂm aparaÂtem, je odlepovaÂnõ zaÂmkuÊ, zpuÊsobene neopatrnyÂm kousnutõÂm, nespraÂvnyÂm po-stupem prÏi lepenõ zaÂmkuÊ, nebo strukturou skloviny, kterou nelze kvalitneÏ leptat [3]. OpacÏny efekt muÊzÏe zpuÊsobit prÏõÂlisÏ velka sõÂla adheze ke sklovineÏ (võÂce nezÏ 10 MPa), ktera zpuÊsobõÂodtrhnutõÂprismy skloviny v pruÊ-beÏhu snõÂmaÂnõ zaÂmkuÊ [4,5]. Podle Bishary pevnost vazby nizÏsÏõ nezÏ 12,75 MPa je optimaÂlnõ a bezpecÏna prÏi snõÂmaÂnõ zejmeÂna keramickyÂch zaÂmkuÊ [6]. Labora-tornõ vyÂzkumy zkoumajõÂcõ hodnoty vazebne sõÂly mezi ortodontickyÂm zaÂmkem a zubem ukaÂzaly, zÏe dostatecÏ-nou adhezi fixnõÂch aparaÂtuÊ zajisÏt'uje sõÂla 5.8-7.8 MPa [7]. Bylo zjisÏteÏno, zÏe sõÂla smyku v rozsahu od 1 do 3 MPa, vznikajõÂcõ v pruÊbeÏhu l eÂcÏenõÂ, by nemeÏla zpuÊsobit odtrhaÂvaÂnõ ortodontickyÂch elementuÊ [8, 9].

Je trÏeba si uveÏdomit, zÏe sõÂly napeÏtõ v komplexu sklo-vina - adhezivum - zaÂmek, ktere vznikajõÂv pruÊbeÏhu aktu zÏvyÂkaÂnõÂ, mohou mõÂt vysÏsÏõ hodnoty.

Znalosti tyÂkajõÂcõ se vlastnostõ jednotlivyÂch adheziv-nõÂch materiaÂl uÊ jsou duÊl ezÏitou pomuÊckou prÏi vyÂbeÏru od-povõÂdajõÂcõÂch adheziv pro urcÏite klinicke prÏõÂpady. Pev-nost spoje zaÂvisõ nejenom na adhezivnõÂm materiaÂl u, ale rovneÏzÏ na baÂzi zaÂmku, povrchu skloviny a zpuÊsobu lepenõÂ.

CõÂlem praÂce bylo porovnaÂnõÂ a hodnocenõÂ pevnosti adheziv vyuzÏõÂvanyÂch pro prÏipevneÏnõÂ ortodontickyÂch zaÂmkuÊ na zubech. Bylo provedeno kvantitativnõÂ hod-nocenõÂ adheziva ponechaneÂho na povrchu skloviny, pomocõÂ ukazatele ARI - Adhesive Remnant Index [10].

MateriaÂl a metoda

AnalyÂze byly podrobeny naÂsledujõÂcõ adhezivnõ ma-teriaÂly: Kompozitnõ pryskyrÏice: Transbond XT (3M), Medicept Light Cure (Medicept Dental), Resilience (Ortho Technology), Light Bond (Reliance), Enlight (Ormco), No-Mix (Dentaurum), Tetric flow (Vivadent), ConTec Prime (Dentaurum), Granitec (Falcon), akrylaÂ-tova pryskyrÏice Spofacryl(Spofa Dental) tak rovneÏzÏ skloionomernõ cement Fuji ORTHO LC (GC).

ZhotovenõÂvzorkuÊ k studii probõÂhalnaÂsledujõÂcõÂm zpuÊ-sobem. Bylo prÏipraveno 330 extrahovanyÂch premolaÂruÊ po prÏedchaÂzejõÂcõ dezinfekci preparaÂtem Incidin liquid s propanolem s vyÂjimkou sklovinneÂho povrchu. Zuby byly po extrakci prÏechovaÂvane v roztoku 0,9 % NaCl

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face). The teeth were preserved in a 0.9% NaClsolu-tion at 37°C for two weeks. Then the teeth were placed in cubes 2 cm x 2 cm x 2 cm and fixed with polyester resin Plus 710 (Novol). By random 11 groups each of 30 samples were created. The groups were assigned to the relevant method of analysis (shear, tension, tor-sion) and to the adhesive tested (Fig. 1).

The enamelwas intact (proved by a digitalmicros-cope with CMOS 2.0 megapixels, software by Micro-Capture, interface PC USB 2.0) in the place where there was a bracket base attached. There was no fil-ling, caries or any enamel defect.

The teeth enamelwas cleaned with paste contai-ning pumice, etched for 30 seconds with 37% ortho-phosphoric acid, and then the teeth were washed with water and dried. Bracket base was degreased with al-coholand dried with compressed air. Adhesive mate-rials tested were used and polymerized in accordance with the manufacturer recommendations. Polymeriza-tion lamp with a monochromatic dioda 1000mW/cm2 (Heraeus Kulzer, Translux Power Blue) was used.

Metalbrackets RMO Integra .022ª were used for all adhesive materials. The testing was performed in vitro at 24°C, 60 minutes after the bracket was attached to the enamel. Thus an eventual influence of the oral ca-vity condition on the characteristics of polymers tested was eliminated. Study was performed with the equip-ment for strength of materialtesting with resistance strain gauge Vishay, model615 Tedea Huntleigh, weight meter VT 100, servomechanism by Eisel, ena-bling to carry out firmness static tests (shear, tension). The data obtained were sent via digital-to-analog con-verter to a PC computer, and the result was processed as a chart with the maximum value where the material was torn. The equipment with a scale in Newtons cer-prÏi teploteÏ 37°C podobu do 2 tyÂdnuÊ. Pote byly

umõÂ-steÏny v krychlõÂch o rozmeÏrech 2 cm x 2 cm x 2 cm, fixo-vane pomocõ polyesterove pryskyrÏice Plus 710 firmy Novol. NaÂhodneÏ bylo vytvorÏeno 11 skupin po 10 vzor-cõÂch. Skupiny byly prÏirÏazeny k odpovõÂdajõÂcõ metodeÏ zkoumaÂnõ (smyk, tah, krut), a zaÂrovenÏ ke zkoumaneÂmu adhezivu (Obr. 1).

Sklovina zubu v mõÂsteÏ, ke ktere bezprostrÏedneÏ prÏileÂ-hala baÂze zaÂmku, byla intaktnõÂ, cozÏ bylo zjisÏteÏno digi-taÂlnõÂm mikroskopem s cÏidlem CMOS 2,0 megapixeluÊ s programovyÂm vybavenõÂm MicroCapture a interfej-sem PC USB 2.0. Nebyla zde vyÂplnÏ cÏi zubnõ kaz, nebo vada skloviny.

Sklovina zkoumanyÂch zubuÊ byla ocÏisÏteÏna pastou s pemzou, leptaÂna 30 sekund 37% kyselinou ortofos-forecÏnou, oplaÂchnuta vodou a osusÏena. BaÂze zaÂmkuÊ byla odmasÏteÏna lihem a osusÏena stlacÏenyÂm vzdu-chem. PouzÏitõÂa polymerizace kazÏdeÂho ze zkoumanyÂch adhezivnõÂch materiaÂl uÊ byla provedena v souladu s do-porucÏenõÂmi vyÂrobce. K polymerizaci byla pouzÏita poly-meracÏnõÂ lampa s monochromatickou diodou o vyÂkonu 1000mW/cm2 firmy Heraeus Kulzer, Translux Power Blue.

Pro vsÏechna adheziva byly pouzÏity kovove zaÂmky firmy RMO Integra .022ª.

ZkousÏky byly provaÂdeÏny in vitro prÏi teploteÏ 24°C, hodinu po prÏipevneÏnõ zaÂmku ke sklovineÏ. TõÂm se vylou-cÏil prÏõÂpadny vliv podmõÂnek prostrÏedõ uÂstnõ dutiny na vlastnosti zkoumanyÂch polymeruÊ. VyÂzkum bylprovaÂ-deÏn na stroji pro pevnostnõ zkousÏky materiaÂlu s odpo-rovyÂm tenzometrem firmy Vishay, model615 Tedea Huntleigh, meÏrÏicÏem hmotnosti VT 100, a servomecha-nizmem firmy Eisel, umozÏnÏujõÂcõÂm provaÂdeÏnõ pevnost-nõÂch statickyÂch zkousÏek (smyk, tah). UÂdaje byly zasõÂ-laÂny prostrÏednictvõÂm analogoveÏ cÏõÂslicoveÂho

prÏevod-Obr. 1:ZkousÏky pevnosti vazby; zleva - tah, smyk, zkrut

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tified by PCA, performed measurement with the advancing speed of 5 mm/min. Torsionalmoment was tested with analog dynamometer fy Tohnichi FTD50CN2-S, scaled in cN*m within the range 1-50, measuring deviation of 0.01 cN*m.

For each adhesive material30 tests (torsion, ten-sion, shear) were performed. After the testing the sam-ples were evaluated with optical microscope equipped with a camera and digitalconverter of image, magnifi-cation 20 x. The main objective was to evaluate the quality of the surface in the place of a tear, and the amount of adhesive left on the enamel surface accor-ding to ARI (Adhesive Remnant Index).

ARI was evaluated according to the following crite-ria:

(0) No adhesive left

(1) Less than 50% of adhesive left (2) More than 50% of adhesive left

(3) - all adhesive left on the tooth, expressed imprint of the bracket base.

To compare the results of strength tests (tension, shear, torsion) one-factor variance analysis (ANOVA) was used (Table 1, 2, 3).

Results

In shear tests the highest value of the mean limit strength was recorded for Transbond XT. The lowest mean values were found for No-Mix Dentaurum (Table 1).

In tension tests the highest value of the mean limit strength was found in Medicept LightCure. The lowest values were found in Tetric flow (Table 2).

In torsion tests, during which the materialgot torn, the highest mean values were recorded for Light Bond Reliance and for Transbond XT. The lowest mean va-lues were measured for Granitec Falcon (Table 3).

In groups tested for tension strength higher ARI va-lues were found in most tested teeth (adhesive left on enamel) with the exception of resins Spofacryl, Light Bond, Medicept LightCure - more adhesive remnants were detected in brackets (Table 4). Similarly, in groups tested for shear and torsion strength adhesives were mostly left on the enamel, with the exception of resin Spofacryl, Light Bond, Medicept Light Cure -again, more adhesive remains were found on the brac-ket base (Table 5, 6).

Discussion

For the bracket attachment filled acrylate resins (formula Bis GMA) are used most frequently. A great variety of resins is available. Individual resins differ in the composition and amount of filler and in the method of polymerization, either chemical or light-cured [11]. nõÂku do pocÏõÂtacÏe trÏõÂdy PC a vyÂsledek byl promõÂtaÂn

v podobeÏ tabulky s maximaÂlnõ hodnotou, ve ktere do-chaÂzelo k prÏetrzÏenõ materiaÂlu. ZarÏõÂzenõÂ, opatrÏene stup-nicõ v newtonech s certifikaÂtem PCA, provaÂdeÏl o meÏrÏenõ s rychlostõ posunu 5 mm/min. VyÂzkum kroutõÂcõÂho mo-mentu bylprovaÂdeÏn analogovyÂm dynamometrem firmy Tohnichi FTD50CN2-S kalibrovaneÂho v cN*m v rozsahu od 1-50, s odchylkou meÏrÏenõ 0.01 cN*m.

Bylo provedeno 30 pevnostnõÂch zkousÏek (krut, tah, smyk) pro kazÏde adhezivum. Po provedenyÂch testech byly vzorky hodnoceny v optickeÂm mikroskopu vyba-veneÂm kamerou a cÏõÂslicovyÂm prÏevodnõÂkem obrazu, pracujõÂcõÂm ve zveÏtsÏenõ 20x, s cõÂlem kvalitativnõÂho hod-nocenõ plochy odtrzÏenõÂ, a zvlaÂsÏteÏ, co do mnozÏstvõ po-nechaneÂho adheziva na povrchu skloviny zubu podle ukazatele ARI (Adhesive Remnant Index).

HodnocenõÂ ukazatele ARI bylo provedeno podle naÂ-sledujõÂcõÂch kriteÂriõÂ:

(0) bez adheziva

(1) meÂneÏ nezÏ 50 % adheziva (2) võÂce nezÏ 50 % adheziva

(3) - vsÏechno adhezivum na zubu s vyÂraznyÂm otiskem baÂze zaÂmku.

K porovnaÂnõ vyÂsledkuÊ pevnostnõÂch testuÊ (tah, smyk a krut) byla pouzÏita jednofaktorova analyÂza variance (ANOVA), viz (Tab. 1, 2, 3).

VyÂsledky

V testech pro smyk meÏlnejvysÏsÏõ hodnotu pruÊmeÏrne meznõ sõÂly Transbond XT. NejnizÏsÏõ pruÊmeÏrne hodnoty vykaÂzalNo-Mix Dentaurum (Tab. 1). Ve vzorku pro tah meÏlnejvysÏsÏõ hodnoty pruÊmeÏrne meznõ sõÂly Medi-cept LightCure . NejnizÏsÏõ pruÊmeÏrne hodnoty byly vykaÂ-zaÂny pro Tetric flow (Tab. 2).

NejvysÏsÏõ pruÊmeÏrne hodnoty pro kroutõÂcõ moment, prÏi ktereÂm dosÏl o k prÏetrzÏenõ materiaÂlu, byly zaregistro-vaÂny u Light Bond Reliance a Transbond XT . NejnizÏsÏõ pruÊmeÏrne hodnoty projevilGranitec Falcon (Tab. 3).

Hodnoty ukazatele ARI v testovanyÂch skupinaÂch pro tah prezentovaly veÏtsÏõÂ rezidua adheziva ponecha-neÂho na sklovineÏ u veÏtsÏiny testovanyÂch. VyÂjimkou byly pryskyrÏice Spofacryl, Light Bond, Medicept Light Cure u kteryÂch bylo nameÏrÏeno vysÏsÏõÂ procento zbytkoveÂho adheziva na zaÂmcõÂch (Tab. 4). Analogicky u hodnot ARI pro smyk a krut bylo zaregistrovaÂno, zÏe veÏtsÏina ad-heziva zuÊstaÂvala na sklovineÏ. VyÂjimkou byla pryskyrÏice Spofacryl, Light Bond, Medicept Light Cure, kde zuÊ-staÂvalo adhezivum na baÂzi zaÂmku (Tab. 5, 6).

Diskuse

K lepenõ zaÂmkuÊ jsou aktuaÂl neÏ nejcÏasteÏji pouzÏõÂvaÂny plneÏne akrylove pryskyrÏice (formule Bis GMA). Tyto pryskyrÏice jsou dostupne v mnoha variantaÂch, jezÏ se od sebe lisÏõ hlavneÏ slozÏenõÂm a mnozÏstvõÂm plniva a

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zpuÊ-shear [MPa]

Bond N mean SD min max

Tetric flow Vivadent 10 4.44 1.47 2.34 7.13 Medicept LightCure Dental 10 6.59 2.00 3.01 9.49 Light Bond Reliance 10 5.97 1.83 3.58 8.25 Spofacryl Spofa Dental 10 6.84 3.58 2.71 15.80 Enlight ORMCO 10 5.64 2.20 2.57 9.50 Transbond XT 3M 10 9.31 2.86 5.94 15.62 No Mix Dentaurum 10 3.11 2.25 1.01 8.69 Resilience Ortho Technology 10 4.55 3.41 0.95 13.68 Gc Fuji ORTHO LC 10 3.62 0.32 3.11 4.09 ConTec Prime Dentaurum 10 4.54 0.72 3.29 5.36 Granitec Falcon 10 3.50 1.11 1.22 5.36

TOTAL 110 5.28 2.74 0.95 15.80

Tab. 1.Hodnoty sõÂly v testech pro smyk u jednotlivyÂch adheziv [MPa]

Tab. 1.Adhesive bond strenght in shear tests for individualadhesi-ves [MPa]

tension [MPa]

Bond N mean SD min max

Tetric flow Vivadent 10 1.76 0.28 1.22 2.03 Medicept LightCure Dental 10 4.84 1.86 1.58 7.96 Light Bond Reliance 10 3.25 0.77 2.20 4.44 Spofacryl Spofa Dental 10 3.69 1.75 0.54 5.80 Enlight ORMCO 10 3.52 0.96 2.54 5.05 Transbond XT 3M 10 3.20 1.48 1.84 7.27 No Mix Dentaurum 10 1.99 0.85 0.61 3.21 Resilience Ortho Technology 10 1.96 0.75 0.84 3.21 Gc Fuji ORTHO LC 10 3.65 1.20 2.13 5.74 ConTec Prime Dentaurum 10 3.12 1.04 1.55 4.90 Granitec Falcon 10 2.98 1.21 1.58 5.29

TOTAL 110 3.09 1.43 0.54 7.96

Tab. 2.Hodnoty sõÂly v testech pro tah u jednotlivyÂch adheziv [MPa]

Tab. 2.Adhesive bond strenght in tension tests for individualadhe-sives [MPa]

torsion [cN*m]

Bond N mean SD min max

Tetric flow Vivadent 10 18.36 6.03 8.10 26.50 Medicept LightCure Dental 10 22.29 3.90 15.20 30.50 Light Bond Reliance 10 26.52 5.11 18.90 35.00 Spofacryl Spofa Dental 10 21.28 4.61 16.20 29.20 Enlight ORMCO 10 21.88 4.24 16.50 27.80 Transbond XT 3M 10 25.48 3.48 19.00 30.50 No Mix Dentaurum 10 13.73 4.49 5.00 21.10 Resilience Ortho Technology 10 21.74 6.45 6.00 30.00 Gc Fuji ORTHO LC 10 18.70 2.93 14.00 23.00 ConTec Prime Dentaurum 10 21.85 2.92 17.50 26.00 Granitec Falcon 10 8.80 2.15 6.00 11.00 TOTAL 110 20.06 6.42 5.00 35.00

Tab. 3.Hodnoty sõÂly ve krutu pro jednotliva adheziva [cN*m]

Tab. 3.Adhesive bond strenght in torsion tests for individualadhe-sives [cN*m] BOND N Tetric flow Vivadent 10 1 1 3 2 2 2 2 1 2 2 Medicept LightCure Dental 10 1 2 2 1 2 1 1 1 1 2 Light Bond Reliance 10 1 2 1 1 1 2 2 1 1 2 Spofacryl Spofa Dental 10 1 1 2 1 1 2 1 1 1 1 Enlight ORMCO 10 1 2 2 2 1 2 2 2 2 2 Transbond XT 3M 10 2 1 2 2 1 2 1 1 2 2 No Mix Dentaurum 10 3 2 3 2 2 2 2 2 3 2 Resilience Ortho Technology 10 2 2 3 2 2 2 1 2 2 2 Gc Fuji ORTHO LC 10 3 2 2 2 2 2 1 2 2 2 ConTec Prime Dentaurum 10 1 2 2 2 2 1 2 2 2 1 Granitec Falcon 10 1 2 2 1 2 2 1 3 2 3 TOTAL 110

Tab. 4.Hodnoty ARI u testuÊ tahem

Tab. 4.ARI in tension tests

TENSILE[ARI] BOND N Tetric flow Vivadent 10 2 1 2 2 2 2 2 2 2 2 Medicept LightCure Dental 10 1 3 2 1 1 1 1 1 2 1 Light Bond Reliance 10 2 1 2 1 1 2 2 1 1 1 Spofacryl Spofa Dental 10 1 1 1 1 1 1 1 1 3 3 Enlight ORMCO 10 2 2 2 2 2 2 1 2 2 1 Transbond XT 3M 10 1 1 2 2 1 2 1 2 2 2 No Mix Dentaurum 10 2 2 2 2 2 2 2 3 3 3 Resilience Ortho Technology 10 2 2 2 2 2 2 3 2 1 1 Gc Fuji ORTHO LC 10 2 2 2 2 2 2 2 2 2 1 ConTec Prime Dentaurum 10 2 2 2 1 2 1 2 2 1 2 Granitec Falcon 10 2 2 2 1 1 2 1 2 2 2 TOTAL 110

Tab. 5.Hodnoty ARI u testuÊ smykem

Tab. 5.ARI in shear tests

SHEAR[ARI] BOND N Tetric flow Vivadent 10 2 1 2 2 2 2 2 2 2 1 Medicept LightCure Dental 10 2 1 2 1 1 1 1 1 1 2 Light Bond Reliance 10 1 2 2 1 1 1 2 1 1 2 Spofacryl Spofa Dental 10 1 1 2 1 1 1 2 1 2 1 Enlight ORMCO 10 1 1 2 2 2 2 2 2 2 1 Transbond XT 3M 10 1 1 2 2 1 2 1 2 2 2 No Mix Dentaurum 10 3 2 2 2 3 2 2 3 2 3 Resilience Ortho Technology 10 3 2 2 2 1 2 3 2 2 2 Gc Fuji ORTHO LC 10 2 1 2 2 2 1 2 2 2 2 ConTec Prime Dentaurum 10 2 2 2 1 2 1 2 2 1 2 Granitec Falcon 10 1 2 2 3 2 2 1 2 2 3 TOTAL 110

Tab. 6.Hodnoty ARI u testuÊ pro krut

Tab. 6.ARI in torsion tests

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Bond strength of an adhesive between the bracket and enameldepends also on consistency and propor-tionalcomposition of an etching agent and the length of etching, on the quality of enamel surface, adhesive polymerization, distance between the source of light and a tooth. It also depends on the shape, structure, surface area and materialof the bracket base, on the oral chamber condition, and on the skills of an ortho-dontist [12].

In clinical practice, there are strengths arising during brackets removal, components of torsion, tension and shear [13]. The use of an optimum adhesive contribu-tes to shorter check-ups, and thus minimizes a pa-tient's discomfort, and eliminates the risk of brackets release [14].

Comparing methods and brackets used in different studies we conclude that the results obtained are diffe-rent and very often cannot be compared, actually [15]. Eliades [16] states that the advancing speed of a te-sting machine over 0.5 mm/min influences the validity of results. Cagri and Irmak [17] found out that haloge-nous light leads to increased adhesive bond strength (mean value - 8.35 MPa) compared to LED light (5.83 MPa).

Higher values of shear, torsion and tension tests were statistically significant in Transbond XT, lower va-lues were statistically significant for Fuji GC. Similar re-sults were quoted by Valetta and Prisco [13].

Our results may be different due to the structure of bracket base. Maijer and Smith [18] conclude that the results obtained for different brackets cannot be compared. The differences in measurements are also due to the fact that the bond strength of attached brac-kets increases during the first 24 hours - this was pro-ved also by Wendel and Droschl [19]. In our study the measurements were done during the first hour follo-wing the bracket attachment, and consequently the values obtained were lower than those given by the au-thors cited above.

According to Maijer and Smith the break between enameland adhesive results more from the errors occurring during the brackets attachment [20]. In fact, correct brackets attachment creates sufficient adhe-sion which, according to Valetta and Prisco [13], may damage enamel during the appliance removal. Enamel prism was damaged twice during shear tests in case of Spofacryl. Similarly, the results given by Regan and Van Noort [21] showed that the intensity of bond strength during shear tests is higher than in tension tests, and therefore the risk of damage to enamelis higher.

According to Valetta and Prisco [13] the mean va-lues of bond strength in torsion tests show statistically sobem iniciovaÂnõÂ polymerizace, chemicky nebo

sveÏ-telnyÂm tvrzenõÂm [11].

Vazebna sõÂla adheziva mezi zaÂmkem a sklovinou zaÂ-visõÂtake na konzistenci a procentoveÂm slozÏenõÂleptadla a doby leptaÂnõÂ, zaÂvisõ na kvaliteÏ povrchu skloviny, na polymerizaci adheziva, vzdaÂlenosti mezi zdrojem sveÏ-tla a zubem. ZaÂvisõ na tvaru, strukturÏe a velikosti po-vrchu a materiaÂl u baÂze zaÂmku, na prostrÏedõ uÂstnõ du-tiny, a zkusÏenosti leÂkarÏe [12].

V klinicke praxi jsou sõÂly, vznikajõÂcõ v pruÊbeÏhu snõÂ-maÂnõ zaÂmkuÊ, komponentou krutu, tahu a smyku [13]. PouzÏitõ optimaÂlnõÂho adheziva zkracuje cÏas naÂvsÏteÏvy, cozÏ v duÊsledku snizÏuje diskomfort pacienta a eliminuje riziko uvolneÏnõ zaÂmkuÊ [14].

PrÏi srovnaÂnõ metodiky jednotlivyÂch vyÂzkumuÊ a pou-zÏityÂch zaÂmkuÊ dochaÂzõÂme k zaÂveÏru, zÏe vyÂsledky meÏrÏenõ jsou rozdõÂlne a velmi cÏasto se nedajõ porovnat [15]. Podle Eliadese [16] rychlost posunu testujõÂcõÂho stroje vysÏsÏõ nezÏ 0.5mm/min. ovlivnÏuje uÂrovenÏ zõÂskanyÂch vyÂ-sledkuÊ. Podle Cagri and Irmak [17] pouzÏitõ halogeno-veÂho sveÏtla zpuÊsobuje zvyÂsÏenõ vazebne sõÂly lepidla, (pruÊmeÏrneÏ 8.35 MPa), nezÏ je u LED sveÏtla (5.83 MPa). PodobneÏ, jak u R. Valetta I D. Prisco [13], byly zõÂs-kane statisticky vyÂznamne vysÏsÏõ hodnoty v pruÊbeÏhu pevnostnõÂch testuÊ ve smyku, krutu a tahu u materiaÂl u Transbond XT a nizÏsÏõ u Fuji GC .

DuÊvodem odlisÏnyÂch hodnot nasÏeho vyÂzkumu vzhledem k jinyÂm studiõÂm bylpravdeÏpodobneÏ typ struktury baÂze pouzÏityÂch zaÂmkuÊ. Podle Majera a Smi-tha 1981 [18] se vyÂsledky vyÂzkumu provaÂdeÏneÂho na ruÊ-znyÂch zaÂmcõÂch nedajõ vzaÂjemneÏ porovnat. Jinou prÏõÂcÏi-nou potvrzeprÏõÂcÏi-nou Wendlem i Droschlem [19] v rozdõÂlech meÏrÏenõ je to, zÏe vazebna sõÂla lepenyÂch zaÂmkuÊ vzruÊsta v pruÊbeÏhu prvnõÂch 24 hodin. MeÏrÏenõ v nasÏem vyÂzkumu bylo provaÂdeÏno v prvnõÂhodineÏ po lepenõÂzaÂmkuÊ a v kon-sekvenci s tõÂm byly zõÂskane hodnoty mensÏõÂ, nezÏ u vyÂsÏe uvedenyÂch autoruÊ.

Podle Majera a Smitha je lom mezi sklovinou a adhe-zivem zpuÊsobeny spõÂsÏe chybami v pruÊbeÏhu lepenõ mkuÊ [20]. Ve skutecÏnosti spraÂvneÏ provedene lepenõ zaÂ-mkuÊ vytvorÏõ dostatecÏnou adhezi, ktera podle Valletty a Prisco [13] muÊzÏe zpuÊsobit posÏkozenõ skloviny v pruÊ-beÏhu snõÂmaÂnõ aparaÂtu. V nasÏem vyÂzkumu dvakraÂt do-sÏlo k posÏkozenõ prizmat skloviny v testech ve smyku u materiaÂlu Spofacryl. VyÂsledky Regana a Van Noorta [21] podobneÏ ukaÂzaly, zÏe velikost sõÂly spojenõ vznikajõÂcõ prÏi testovaÂnõ ve smyku vykazuje vysÏsÏõ hodnoty, nezÏ u testuÊ v tahu, cozÏ vytvaÂrÏõ vysÏsÏõ riziko posÏkozenõ sklo-viny.

U hodnocenõ vyÂzkumu Valletty a Prisco [13] vykazo-valy vyÂsledky meÏrÏenõ u pruÊmeÏrnyÂch hodnot silu kroutõÂ-cõÂho momentu hodnoty, ktere majõ statisticky vyÂ-znamne rozdõÂly, vysÏsÏõ pro Transbond XT a mensÏõ pro Fuji GC .

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significant differences - they are higher in Transbond XT, and lower in case of Fuji GC.

In randomly detached brackets during the ortho-dontic treatment, clinical examination often finds ad-hesive remnants only on the enamel which is the evi-dence of weak attachment between the bracket base and and adhesive [22].

In our study most adhesives available on the market were compared. The aim is to improve comparative methods for the assessment of their quality.

Conclusion

Based on the results of the analysis of the adhesive bond strength examined by shear, tension and torsion tests, we obtained the following results:

1. The highest mean values of bond strength in shear test were recorded for Transbond XT, the lowest for No-Mix Dentaurum.

2. The highest mean values of bond strength in ten-sion tests were recorded for Medicept Light Cure, the lowest for Tetric flow.

3. The highest mean values of bond strength in tor-sion tests were recorded for Light Bond Reliance, the lowest for Granitec Falcon.

4. ARI values were mostly on degree 2. In Spofacryl, Light Bond and Medicept Light Cure resins ARI values were mostly on degree 1.

Authors have no commercial, proprietary or financial interest in products or companies mentioned in the article.

PrÏi naÂhodneÂm odlepenõÂ zaÂmkuÊ v pruÊbeÏhu ortodon-tickeÂho l eÂcÏenõÂ, je cÏasto klinicky zjisÏteÏna prÏõÂtomnost ad-heziva jen na sklovineÏ, co sveÏdcÏõÂo slabeÂm spojenõÂmezi baÂzõÂ zaÂmku a adhezivem [22].

V nasÏem vyÂzkumu byla porovnaÂvaÂna veÏtsÏina adhe-ziv, ktere jsou na trhu dostupneÂ. CõÂlem je zlepsÏenõ jejich porovnaÂvatelnosti, kdyzÏ byla pouzÏita jednotna vyÂ-zkumna metoda.

ZaÂveÏr

Na zaÂkladeÏ provedeneÂho vyÂzkumu pevnosti vazby v testovaÂnõÂ lepenyÂch spojuÊ mezi zaÂmkem a povrchem zubu puÊsobenõÂm sõÂly ve smyku, tahu a krutu bylo zji-sÏteÏno:

1. StrÏednõÂ hodnoty pevnosti vazby ve smyku meÏl nejvysÏsÏõÂ Transbond XT, nejnizÏsÏõÂ zõÂskalNo-Mix Dentau-rum.

2. StrÏednõÂ hodnoty pevnosti vazby v tahu meÏlnej-vysÏsÏõÂ Medicept Light Cure, nejnizÏsÏõÂ zõÂskalTetric flow.

3. StrÏednõÂ hodnoty pevnosti vazby ve krutu meÏlnej-vysÏsÏõÂ Light Bond Reliance, nejnizÏsÏõÂ zõÂskalGranitec Fal-con.

4. Hodnoty ukazatele ARI se v testech prÏevaÂzÏneÏ ukazovaly na 2. stupni. VyÂjimkou byla pryskyrÏice Spo-facryl, Light Bond a Medicept Light Cure u kteryÂch prÏe-vazÏoval1. stupenÏ.

AutorÏi nemajõ komercÏnõÂ, vlastnicke nebo financÏnõ zaÂjmy na pro-duktech nebo spolecÏnostech popsanyÂch v tomto cÏlaÂnku.

Literatura/References

1. Newman G. V.: Adhesion and orthodontic plastic atta-chments. Amer. J. Orthodont. dentofacialOrthop. 1969, 56, cÏ. 6, s. 573-588.

2. Reynolds I. R.; von Fraunhofer J. A.: Direct bonding of orthodontic attachments to teeth: the relation of adhe-sive bond strength to gauze mesh size. Brit. J. Ortho-dont. 1976, 3, cÏ. 2, s. 91-95.

3. Kao E. C.; Eliades T.; Rezvan E.; Johnston W. M.: Torsio-nalbond strength and failure pattern of ceramic brackets bonded to composite resin laminate veneers. Eur. J. Orthodont. 1995, 17, cÏ. 6, s. 533-540.

4. Relief, D.H.: Failure AT the dental adhesive etched ena-melinterface: J. OralRehab. 1974 , 1, cÏ. 3, s. 265-284. 5. Bishara, S.E.; Fehr, D.: Comparisons of the effectiveness

of pliers with narrow and wide blades in debonding cera-mic brackets. Amer. J. Orthodont. dentofacialOrthop. 1993, 103, cÏ. 3, s. 253-257.

6. Nkenke N.; Hirsfelder U.; Martus P.: Evaluation of the bond strength of different bracket-bonding systems to bovine enamel. Eur. J. Orthodont. 1997 , 19, cÏ. 3, s. 259-270.

7. Reynolds I. R.: A review of direct orthodontic bonding. Brit. J. Orthodont. 1975, cÏ. 2, s. 171-178.

8. Kallio T. T.; LastumaÈki T. M.; Vallittu P. K.: Bonding of re-storative and veneering composite resin to some poly-meric composites. Dent. Mater. 2001, 17, cÏ. 1, s. 80-86. 9. Nosowicz P.; Czarnecka B.: Clinical aspects of bonding orthodontic brackets to various dentalrestorative mate-rials. Czas. Stomatol. 2006, 59, cÏ. 4, s. 279-284. 10. Artun J.; Bergland S.; Clinical trials with crystal growth

conditioning as an alternative to acid-etch enamel pre-treatment. Amer. J. Orthodont. 1984, 85, cÏ. 4, s. 333-340.

11. Proffit W.R.,; Fields H.W.: Ortodoncja wspoÂcÇzesna. Cze-lej Publishing House 2001.

12. Bishara S. E.; Ostby A. W.; Laffoon J. F.; Warren J.: Shear Bond Strength, Bond comparison of two adhesive sy-stems following thermocycling. A new self-etch primer and a resin-modified glass ionomer. Angle Orthodont. 2007, 77, cÏ. 2, s. 337-341.

13. Valletta R.; Prisco.D.; Ambrosio L.: Evaluation of the de-bonding strength of orthodontic brackets using three dif-ferent bonding systems. Eur. J. Orthodont., 2007, 29, cÏ. 6, s. 571-577.

14. Graber T. M.; Vanarsdall Jr. R. L. Orthodontics, current principles and techniques. 3rd end. Mosby, St Louis 2000.

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15. Prietsch J.R. et al: Development of a device to measure bracket debonding force in vivo. Eur. J. Orthodont. 2007, 29, cÏ. 6, s. 564-570.

16. Eliades T.; Brantley W.A.: The inappropriateness of con-ventionalorthodontic Bond strength assessment proto-cols. Eur. J. Orthodont. 2000, 22, cÏ. 1, s. 13-23.

17. Cagri U.; Ozgur I.: Temperature rise and shear bond strength of bondable buccal tubes bonded by various light sources. Eur. J. Orthodont. 2000, 30, cÏ. 4, s. 413-417.

18. Smith D. C.; Maijer R.: Improvements in bracket base de-sign. Amer. J. Orthodont. 1983, 83, cÏ. 4, s. 227-281.

19. WendlB.; DroschlH.: A comparative in vitro study of the strength of directly bonded brackets using different cu-ring techniques. Eur. J. Orthodont. 2004, 26, cÏ 5, s. 535-544.

20. Maijer R.; Smith D.C.: Variables influencing the bond strength of metalorthodontic bracket bases. Amer. J. Orthodont. 1981, 79, cÏ. 1, s. 20-34.

21. Regan D.; Van Noort R.: Bond strengths of two integral bracket base combinations: an in vitro comparison with foil-mesh. Eur. J. Orthodont. 1989, 11, cÏ. 2, s. 144-153. 22. Lopez J.: Retentive shear strengths of various bonding attachment bases. Amer. J. Orthodont. 1980, 77, cÏ. 6, s. 669-678.

Bartøomiej Pawlus Klinika zubnõÂho leÂkarÏstvõÂ PalackeÂho 12, 772 00 Olomouc

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PodeÏkovaÂnõÂ

RaÂdi bychom podeÏkovali koleguÊm MUDr. Tvardkovi a MUDr. SucheÂmu za vynikajõÂcõ ortodonticke seminaÂrÏe, ktere probeÏhly v lednu a v uÂnoru letosÏnõÂho roku na Stomatologicke klinice 3. LF UK v Praze v raÂmci seminaÂrÏuÊ postgraduaÂlnõÂho studia oboru ortodoncie. MUDr. Tvradek s prÏehledem a velmi srozumitelneÏ prÏednaÂsÏelo biomechanice a MUDr. Suchy naÂs seznaÂmils vyÂsledky terapie a s uÂskalõÂmi praÂce se samoligovacõÂmi zaÂmky.

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