An SEM evaluation of several adhesive systems used for bonding ®ber posts under clinical conditions Alessandro Vichi a , Simone Grandini a , Carel L. Davidson b , Marco Ferrari a, * a Department of Dental Materials, School of Dentistry, University of Siena, Italy b Department of Dental Materials Science, ACTA, University of Amsterdam, Amsterdam, The Netherlands Received 5 December 2000; revised 24 April 2001; accepted 19 June 2001 Abstract Objectives: Theobjectiveofthisinvestigationwastoevaluatetheeffectivenessofthree`one-bottle'andtwo`threestep'adhesivesystems (ascontrols)intheformationofresintags,adhesivelateralbranchesandaresindentininterdiffusionzone(RDIZ)whenusedtobond®ber postsunderclinicalconditions.ThisstudywasperformedusingstandardizedSEMobservationsandscoringresintagformationanddensity. Methods: Fiftyrootcanaltreatedteeth,alreadyscheduledforextractionforendodonticorperiodontalreasons,wereselectedforthisstudy. Thepatientswereinformedandtheirwrittenconsentwasobtained.Thesampleswererandomlyallocatedto®vegroupsoftensampleseach. Group1:AllBond2withC&B(Bisco);Group2:ScotchbondMultipurposePluswithOpalLutingComposite(3M);Group3:Scotchbond1 incombinationwithRelyXARCresincement(3M);Group4:One-stepwithC&Bresincement(Bisco);Group5:AllBondExperimental with Post Cement HI±X (Bisco). The adhesive systems and resin cements were used strictly according to the manufacturers' instructions. Thepriming-adhesivesolutionofeach`one-bottle'systemwaslight-curedbeforeplacingtheresincementandthepost.FiftyAestheti-Plus posts (white quartz ®ber posts, RTD, France) were used. A week later, the roots were extracted and processed for SEM observations. Results: All the adhesive systems showed a RDIZ and resin tag and adhesive lateral branch formation. Microscopic examination of the restoredinterfacesofGroups1and2showedahigherpercentofRDIZthanthosefoundinsamplesofGroups3,4and5.RDIZmorphology was easily detectable and uniform in the ®rst two thirds of the root canals, whilst in the apical third the RDIZ was not uniformly present. Resin tag morphology and formation were signi®cantly more detectable in the cervical and middle areas than in the apical zone. No statistically signi®cant differences were found among the ®ve groups coronally, while in the apical and middle thirds two `one-bottle' systems (Groups 3 and 4) showed signi®cantly less resin tags than the control Groups 1, 2 and the experimental Group 5. No statistically signi®cant differences were found among the three `one-bottle' systems in the three evaluated areas. The standardization of SEM observa- tions and scoring resin tag formation allowed statistical evaluation. Conclusions: The `three step' adhesive systems can create a wider micromechanical interlocking between adhesive materials and etched dentin than `one-step' systems. q 2002 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved. Keywords: Fiber posts; Root dentin; Resin dentin interdiffusion zone; Resin tags 1. Introduction Recently, the use of adhesive systems for post cementa- tion have increased in popularity and resin materials have beenproposedtobeusedincombinationwithanacidetch- ing technique, adhesive system, luting resin cement and ®berposts[1±3]. The®berpostshavetwoimportantcharacteristics:(1)the modulus of elasticity of the ®ber posts is similar to that of dentin[2,4]and(2)thesepostsarecementedwithanadhe- sivetechniqueavoidingfrictionbetweenpostandrootcanal walls[1,2].Originally,®berposts(RTD,Grenoble,France) wererecommendedforusewithathreestepbondingsystem (All Bond 2, Bisco Co., Itasca, Il) and proprietary resin cement (C & B, Bisco). Recently, `one-bottle' adhesive systems have been introduced to simplify the clinical bonding procedure in restorative dentistry. The clinical indication for use of `one-bottle' systems has now increased [5]. The latest generation of adhesive systems produce, by means of an etch technique, removal or modi®cation of thesmearlayeranddemineralizationofthedentinexposing a®nenetworkofcollagen®brils[5].Thein®ltrationofthis network with resin permits formation of a resin±dentin interdiffusion zone (RDIZ), the so called `hybrid layer', with resin tags and adhesive lateral branches, thus creating micromechanicalretentionoftheresintothedemineralized Dental Materials 18 (2002) 495±502 dental materials 0109-5641/02/$22.00 + 0.00 q 2002 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved. PII:S0109-5641(01)00065-3 www.elsevier.com/locate/dental * Corresponding author. Tel.: 139-586-892283; fax: 139-586-898305. E-mail address: md3972@mclink.it (M. Ferrari).