Abstract

Introduction

In vitro studies are usually used to test materials and techniques before clinical application. Although considered generally of low clinical relevance, it is clear that results obtained in vitro are useful to guide protocols for several clinical approaches, especially considering the absence of evidence from well-designed clinical trials in dentistry.¹1 Bayne SC. Correlation of clinical performance with ‘in vitro tests' of restorative dental materials that use polymer-based matrices. Dent Mater. 2012 Jan;28(1):52-71.^,22 Skupien JA, Valentini F, Boscato N, Pereira-Cenci T. Prevention and treatment of Candida colonization on denture liners: A systematic review. J Prosthet Dent. 2013 Nov;110(5):356-362.^,33 Nassar U, Aziz T, Flores-Mir C. Dimensional stability of irreversible hydrocolloid impression materials as a function of pouring time: a systematic review. J Prosthet Dent. 2011 Aug;106(2):126-33.^,44 West NX, Davies M, Amaechi BT. In vitro and in situ erosion models for evaluating tooth substance loss. Caries Res. 2011;45 Suppl 1:43-52. Cementation of glass-fiber posts (GFPs) into the root canal can be considered one of those examples, as numerous attempts to improve the adhesion of GFPs to intra-radicular dentin have been tested in vitro,⁵5 Amaral M, Santini MF, Wandscher V, Amaral R, Valandro LF. An in vitro comparison of different cementation strategies on the pull-out strength of a glass fiber post. Oper Dent. 2009 Jul-Ago;34(4):443-51.^,66 Macedo VC, Faria e Silva AL, Martins LR. Effect of cement type, relining procedure, and length of cementation on pull-out bond strength of fiber posts. J Endod. 2010 Sep;36(9):1543-6.^,77 Shiratori FK, Valle AL, Pegoraro TA, Carvalho RM, Pereira JR. Influence of technique and manipulation on self-adhesive resin cements used to cement intraradicular posts. J Prosthet Dent. 2013 Jul;110(1):56-60. but few clinical evaluations are avalilable.⁸8 Sarkis-Onofre, R, Jacinto RC, Boscato N, Cenci MS, Pereira-Cenci T. Cast metal vs. glass fiber posts: a randomized controlled trial with up to 3 years of follow up. J Dent. 2014 May;42(5):582-7.

Recently, a systematic review⁹9 Sarkis-Onofre R, Skupien J, Cenci M, Moraes R, Pereira-Cenci T. The role of resin cement on bond strength of glass-fiber posts luted into root canals: a systematic review and meta-analysis of in vitro studies. Oper Dent. 2014 Jan-Fev;39(1):E31-44.showed that the type of luting cement used influences the retention of GFPs in root canals but the large degree of heterogeneity of the studies included was emphasized. This heterogeneity was partly due to the various factors that can influence bonding, including cement application mode, post pretreatment, and sample storage conditions. The influence of some factors on bond strength (BS) of GFPs has been addressed;¹⁰10 Leme AA, Pinho AL, Gonçalves L, Correr-Sobrinho L, Sinhoreti MA. Effects of silane application on luting fiber posts using self-adhesive resin cement. J Adhes Dent. 2013 Jun;15(3):269-74.^,1111 Zicari F, De Munck J, Scotti R, Naert I, Van Meerbeek B. Factors affecting the cement-post interface. Dent Mater. 2012 Mar;28(3):287-97.^,1212 Cecchin D, Almeida JF, Gomes BP, Zaia AA, Ferraz CC. Influence of chlorhexidine and ethanol on the bond strength and durability of the adhesion of the fiber posts to root dentin using a total etching adhesive system. J Endod. 2011 Sep;37(9):1310-5. however, it is important to evaluate as many variables as possible to determine the interactions between these factors associated with the retention of posts in root canals. Identifying a clear influence of post/sample-related factors will aid researchers in standardizing preclinical and clinical studies.

The aim of this study was to evaluate the influence of variables related to post cementation by systematically reviewing the in vitro literature on the retention of GFPs luted into root canals. The hypothesis tested was that factors other than the type of resin cement used for luting the posts would also have a role on the retention of GFPs.

Methodology

This systematic review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.¹³13 Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gotzsche PC, Ioannidis JP, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration. BMJ. 2009 Jul;21:339:b2700. PubMed and Scopus databases were searched to identify in vitro studies that evaluated and compared the retention (bond strength values in MPa) of GFPs cemented into root canals of human or bovine teeth using both regular and self-adhesive resin cements. The search strategy included the following: (glass fiber post) AND (resin cement) AND (bond strength); (glass fiber post) AND (push out); (self* resin cement) AND (glass fiber post) AND (bond strength); (glass-fiber OR glass fiber), and (post) AND (bond* OR adhes*). The same strategy was used changing the term post for dowel, resin cement for luting agent, and fiber for fibre.

The last search was conducted in December 2013 and no publication year or language limits were set. The references of eligible papers were hand-searched for additional studies. In vivo or in situ studies, posts that were not GFPs, studies that luted the GFPs into artificial devices, and studies that did not compare the BS between regular and self-adhesive resin cements were excluded. Two independent reviewers screened the titles, and shortlisting for inclusion was followed by abstract evaluation. The abstracts were assessed and eligible papers identified. In case of doubt, the paper underwent full text evaluation. In cases of disagreement, a third reviewer decided whether the article should be included (Figure 1).

Two authors independently extracted all data. In case of BS values reported separately for different root thirds (for instance, in studies in which the push-out test was used), the BSs of all root thirds were averaged. In studies where the BS tests performed included other types of cement or post, only the data of interest were extracted. Variables that were considered similar among the studies were extracted and classified according to: tooth type (human or bovine); prior endodontic treatment (yes or no); post pretreatment (cleaning/pretreatment, silane application, or both); bonding agent type (if used); and mode of cement application (around the post, into the root canal, or both). Categories were created with indicator variables (reference group) for each category; in case of missing data, the category “Unknown” was created to make regression model statistics possible.

Statistical analyses were performed using SPSS 22 software for Mac (SPSS Inc., Chicago, USA). Analysis of Variance (ANOVA) with Tukey's post hoccomparison was used to analyze the bond strength values at a significance level of 5%. To analyze the influence of the studied variables on GFP retention, a model of linear regression was created. The first plot to check whether regression was feasible was doubtful, thus logarithm transformation of bond strength values was performed. Next, for the significant variables, an exponential effect was applied followed by transformation as percentage effect. Thus, two regression analyses were carried out: one for all data and another for the two types of cement separately, to verify the influence of the same factors for each category. Descriptive statistics was used to describe the variables according to the included studies.

Results

From the 34 studies included,¹⁴14 Bitter K, Paris S, Pfuertner C, Neumann K, Kielbassa AM. Morphological and bond strength evaluation of different resin cements to root dentin. Eur J Oral Sci. 2009 Jun;117(3):326-33.^,1515 Bitter K, Perdigao J, Exner M, Neumann K, Kielbassa A, Sterzenbach G. Reliability of fiber post bonding to root canal dentin after simulated clinical function in vitro. Oper Dent. 2012 Jul-Ago;37(4):397-405.^,1616 Calixto LR, Bandéca MC, Silva FB, Rastelli ANS, Porto-Neto ST, Andrade AM. Effect of light curing units on push out fiber post bond strength in root canal dentin. Laser Physics. 2009 Aug;19(8):1867-71.^,1717 Farina AP, Cecchin D, Garcia LF, Naves LZ, Correr Sobrinho L, Pires-de-Souza FC. Bond strength of fiber posts in different root thirds using resin cement. J Adhes Dent. 2011 Apr;13(2):179-86.^,1818 Farina AP, Cecchin D, Garcia LFR, Naves LZ, Pires-de-Souza FCP. Bond strength of fibre glass and carbon fibre posts to the root canal walls using different resin cements. Aust Endod J. 2011 Aug;37(2):44-50.^,1919 Erdemir U, Sar-Sancakli H, Yildiz E, Ozel S, Batur B. An in vitro comparison of different adhesive strategies on the micro push-out bond strength of a glass fiber post. Med Oral Patol Oral Cir Bucal. 2011 Jul 1;16(4):e626-e34.^,2020 Erdemir U, Mumcu E, Topcu FT, Yildiz E, Yamanel K, Akyol M. Micro push-out bond strengths of 2 fiber post types luted using different adhesive strategies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010 Oct;110(4):534-44.^,2121 Durao Mauricio PJ, Gonzalez-Lopez S, Aguilar- Mendoza JA, Felix S, Gonzalez-Rodriguez MP. Comparison of regional bond strength in root thirds among fiber-reinforced posts luted with different cements. J Biomed Mater Res B Appl Biomater. 2007 Nov;83(2):364-72.^,2222 Goracci C, Sadek FT, Fabianelli A, Tay FR, Ferrari M. Evaluation of the adhesion of fiber posts to intraradicular dentin. Oper Dent, 2005 Sep-Oct;30(5):627-35.^,2323 Goracci C, Tavares AU, Fabianelli A, Monticelli F, Raffaelli O, Cardoso PC, et al. The adhesion between fiber posts and root canal walls: Comparison between microtensile and push-out bond strength measurements. Eur J Oral Sci. 2004 Aug;112(4):353-61.^,2424 Leme AA, Coutinho M, Insaurralde AF, Scaffa PM, Silva LM. The influence of time and cement type on push-out bond strength of fiber posts to root dentin. Oper Dent. 2011 Nov-Dec;36(6):643-48.^,2525 Lindblad RM, Lassila LV, Salo V, Vallittu PK, Tjaderhane L. Effect of chlorhexidine on initial adhesion of fiber-reinforced post to root canal. J Dent. 2010 Oct;38(10):796-801.^,2626 Kececi AD, Ureyen Kaya B, Adanir N. Micro push-out bond strengths of four fiber-reinforced compos- ite post systems and 2 luting materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008 Jan;105(1):121-8.^,2727 Mumcu E, Erdemir U, Topcu FT. Comparison of micro push-out bond strengths of two fiber posts luted using simplified adhesive approaches. Dent Mater J. 2010 May;29(3):286-96.^,2828 Rathke A, Haj-Omer D, Muche R, Haller B. Effectiveness of bonding fiber posts to root canals and composite core build-ups. Eur J Oral Sci. 2009 Oct;117(5):604-10.^,2929 Radovic I, Mazzitelli C, Chieffi N, Ferrari M. Evaluation of the adhesion of fiber posts cemented using different adhesive approaches. Eur J Oral Sci. 2008 Dec;116(6):557-63.^,3030 Roperto RC, El-Mowafy O, Porto-Neto ST, Marchesan MA. Microtensile bond strength of radicular dentin to non-metallic posts bonded with self-adhesive cements. Int J Clin Dent. 2010;3(2):73-80.^,3131 Soares CJ, Pereira JC, Valdivia ADCM, Novais VR, Meneses MS. Influence of resin cement and post configuration on bond strength to root dentin. Int Endod J. 2012 Feb;45(2):136-45.^,3232 Zaitter S, Sousa-Neto MD, Roperto RC, Silva-Sousa YT, El-Mowafy O. Microtensile bond strength of glass fiber posts cemented with self-adhesive and self-etching resin cements. J Adhes Dent. 2011 Feb;13(1):55-9.^,3333 Xü N, Hu SH, Yang Y, Ren X, Zuo EJ. Effect of different resin cements and silane coupling agents on bond strength of glass fiber post to root dentin. J Dalian Med Univ. 2011 Aug 20;33(4):321-324, 329.^,3434 Zicari F, Couthino E, De Munck J, Poitevin A, Scotti R, Naert I, et al. Bonding effectiveness and sealing ability of fiber-post bonding. Dent Mat. 2008 Jul;24(7):967-77.^,3535 Sadek FT, Goracci C, Monticelli F, Grandini S, Cury AH, Tay F, et al. Immediate and 24-hour evaluation of the interfacial strengths of fiber posts. J Endod. 2006 Dec;32(12):1174-7.^,3636 Mesquita GC, Veríssimo C, Raposo LH, Santos-Filho PC, Mota AS, Soares CJ. Can the cure time of endodontic sealers affect bond strength to root dentin? Braz Dent J. 2013;24(4):340-3.^,3737 Gomes GM, Gomes OM, Reis A, Gomes JC, Loguercio AD, Calixto AL. Effect of operator experience on the outcome of fiber post cementation with different resin cements. Oper Dent. 2013 Sep-Oct;38(5):555-64.^,3838 Calixto LR, Bandéca MC, Clavijo V, Andrade MF, Vaz LG, Campos EA. Effect of resin cement system and root region on the push-out bond strength of a translucent fiber post. Oper Dent. 2012 Jan-Fev;37(1):80-6.^,3939 Bergoli CD, Amaral M, Druck CC, Valandro LF. Evaluation of four cementation strategies on the push-out bond strength between fiber post and root dentin. Gen Dent. 2011 Nov-Dec;59(6):498-502.^,4040 Kadam A, Pujar M, Patil C. Evaluation of push-out bond strength of two fiber-reinforced composite posts systems using two luting cements in vitro. J Conserv Dent. 2013 Sep;16(5):444-48.^,4141 Bergoli CD, Amaral M, Boaro LC, Braga RR, Valandro LF. Fiber post cementation strategies: effect of mechanical cycling on push-out bond strength and cement polymerization stress. J Adhes Dent. 2012 Aug;14(5):471-8.^,4242 Sterzenbach G, Karajouli G, Naumann M, Peroz I, Bitter K. Fiber post placement with core build-up materials or resin cements-an evaluation of different adhesive approaches. Acta Odontol Scand. 2012 Sep;70(5):368-76.^,4343 Amaral M, Rippe MP, Bergoli CD, Monaco C, Valandro LF. Multi-step adhesive cementation versus one-step adhesive cementation: push-out bond strength between fiber post and root dentin before and after mechanical cycling. Gen Dent. 2011 Sep-Oct;59(5):e185-91.^,4444 Pereira JR, Lins do Valle A, Ghizoni JS, Lorenzoni FC, Ramos MB, Dos Reis Só MV. Push-out bond strengths of different dental cements used to cement glass fiber posts. J Prosthet Dent. 2013 Aug;110(2):134-40.^,4545 Gomes GM, Gomes OM, Reis A, Gomes JC, Loguercio AD, Calixto AL. Regional bond strengths to root canal dentin of fiber posts luted with three cementation systems. Braz Dent J. 2011;22(6):460-67.^,4646 Daleprane B, Pereira CNB, Oréfice R, Bueno A, Vaz R, Moreira A, et al. The effect of light-curing access and different resin cements on apical bond strength of fiber posts. Oper Dent. 2014 Mar-Apr;39(2):E93-100. DOI: 10.2341/12-477-L. Epub 2013 Oct 22.^,4747 Liu C, Liu H, Qian YT, Zhu S, Zhao SQ. The influence of four dual-cure resin cements and surface treatment selection to bond strength of fiber post. Int J Oral Sci. 2014 Mar;6(1):56-60. DOI: 10.1038/ijos.2013.83. Epub 2013 Nov 1. 35 distinct data sets were extracted because one article had two different data sets.²³23 Goracci C, Tavares AU, Fabianelli A, Monticelli F, Raffaelli O, Cardoso PC, et al. The adhesion between fiber posts and root canal walls: Comparison between microtensile and push-out bond strength measurements. Eur J Oral Sci. 2004 Aug;112(4):353-61. BS values are presented in Table 1. No statistically significant difference was found between resin cements (p = 0.379) or bonding agents (p = 0.068).

Table 2 shows the regression model for all data. Prior endodontic treatment led to a 22.7% decrease in BS values (p = 0.013). Regarding post pretreatment, cleaning or silanizing the post did not statistically affect BS values (p = 0.198 and p = 0.06, respectively) compared with the use of these two pretreatments together. When the cement was applied into the root canal alone, or when the mode of cement application was not described, retention was statistically higher compared with the application of cement both into the root canal and around the post (34.7% with p = 0.003 and 71.7% with p < 0.001, respectively).

The regression model divided according to the type of resin cement used is shown inTable 3. For self-adhesive resin cement, only the “Unknown” category of cement application presented statistically significant differences (p = 0.001), increasing GFP retention by 106% compared with application both around the post and into the root canal. Regarding regular resin cement, post retention was influenced by: (i) cleaning the post prior to its cementation, which increased retention in 43.4% compared with silane application without cleaning (p = 0.032); (ii) applying the cement around the post and into root canal, which decreased retention compared to cement application around the post only (p = 0.02) or into root canal only (p = 0.041), and when the method of cement application was unknown (p = 0.004). In all conditions, cleaning was defined as ethanol or phosphoric acid application or air abrasion. In contrast to the results obtained using the regression model for all data, prior endodontic treatment did not influence post retention using the regression model divided according to the type of resin cement used (p = 0.137 and p = 0.81, respectively). In both models, BS values were unaffected by tooth type (human or bovine).

Discussion

This systematic review is the first study to evaluate factors related to the selection of materials and luting procedures that may influence the retention of GFPs in root canals. Although conducted based on in vitro studies because of the dearth of clinical trials, the parameters taken into account in this study may affect the performance of GFPs. Several cementation strategies have been proposed, mainly in vitro, to improve the retention of GFPs. The analysis of luting-related variables may support clinicians during evidence-based decision-making. Although BS values were considered in this study, the aim was not to compare different adhesive or luting materials but rather to evaluate factors associated with the retention of GFPs. A previous systematic review⁹9 Sarkis-Onofre R, Skupien J, Cenci M, Moraes R, Pereira-Cenci T. The role of resin cement on bond strength of glass-fiber posts luted into root canals: a systematic review and meta-analysis of in vitro studies. Oper Dent. 2014 Jan-Fev;39(1):E31-44. adopted a statistical approach to evaluate the influence of resin cements and adhesives on the retention of GFPs and demonstrated that self-adhesive cements perform best. However, the articles included in this study exhibited a large degree of heterogeneity;⁹9 Sarkis-Onofre R, Skupien J, Cenci M, Moraes R, Pereira-Cenci T. The role of resin cement on bond strength of glass-fiber posts luted into root canals: a systematic review and meta-analysis of in vitro studies. Oper Dent. 2014 Jan-Fev;39(1):E31-44. therefore, our regression model considered other variables to increase the reliability of our results. Tooth type, type of endodontic sealer used, and type of post used were considered in our model; however, because few studies included these variables, the comparisons were unfair, decreasing the reliability of the regression model.

Our results show that prior endodontic treatment can affect the BS of GFPs. We assumed that all studies performed some degree of preparation of the postholes before inserting the GFPs: it is full treatment of the endodontic canal that affects the performance of luted posts. Some types of canal sealer (e.g., calcium hydroxide cements) can be difficult to remove from the root canal walls and sealer residues can interfere with bonding. The presence of eugenol in other cements has been linked to reduced polymerization of adhesives and resin cements.⁴⁸48 Hansen EK, Asmussen E. Influence of temporary filling materials on effect of dentin-bonding agents. Scand J Dent Res. 1987 Dec;95(6):516-20.^,4949 Cohen BI, Volovich Y, Musikant BL, Deutsch AS. The effects of eugenol and epoxy-resin on the strength of a hybrid composite resin. J Endod. 2002 Feb;28(2):79-82. It is clear that endodontic treatment should always be performed prior to BS testing of GFPs. Conversely, the type of tooth used in the studies (human or bovine) did not influence the results. This finding can be considered relevant because the use of extracted human teeth, particularly single-root anterior teeth, is increasingly difficult.

Our findings also show that applying the cement into the root canal increased post retention when compared with the technique where the cement is also applied around the post. The use of lentulo drills or syringes for cement insertion could reduce the presence of voids and bubbles that could affect correct cementation of GFPs. However, lentulo drills might heat up the resin cement and speed up polymerization, reducing the cement working time.⁵⁰50 Ferrari M, Vichi A, Grandini S, Goracci C. Efficacy of a self-curing adhesive-resin cement system on luting glass-fiber posts into root canals: an SEM investigation. Int J Prosthodont. 2001 Nov-Dec;14(6):543-9.^,5151 Boschian Pest L, Cavalli G, Bertani P, Gagliani M. Adhesive post-endodontic restorations with fiber posts: push-out tests and SEM observations. Dent Mater. 2002 Dec;18(8):596-602. A longer time is necessary to apply the cement inside the canal and around the post, affecting working time and polymerization of self-and dual-cure cements. In addition, as cement application around the post is usually carried out with a spatula, this may not be a reliable procedure to prevent incorporation of voids. Interesting is the fact that unknown cementation procedures provided statistically higher post retention compared to the reference. Despite no information regarding the method of cement application was found in several studies, and due to the good results achieved for the unknown technique, it is hypothesized that manufacturers' instructions were followed without distinct cement application strategies when no information was available in the article.

The results of the regression model divided according to resin cement type show that post retention following the use of regular resin cements is more greatly influenced by the variables, suggesting that self-adhesive resin cements are less technique-sensitive. A recent study³⁷37 Gomes GM, Gomes OM, Reis A, Gomes JC, Loguercio AD, Calixto AL. Effect of operator experience on the outcome of fiber post cementation with different resin cements. Oper Dent. 2013 Sep-Oct;38(5):555-64. showed that, in contrast to regular resin cements, the performance of self-adhesive resin cements for luting GFPs was not influenced by operator experience. Nevertheless, for regular cements, luting the post without applying cement around it outperformed luting the post and applying cement around it. Cleaning the post before cementation with ethanol, air abrasion, or phosphoric acid also improved retention compared with silane application without cleaning.

Different variables were grouped according to their similarity, which could be considered a limitation of this study. For instance, post cleaning included studies that used ethanol, phosphoric acid, or air abrasion before cementation. Although air abrasion and ethanol are approaches that could have significant differences, the model might have been weak and unreliable if another category was created. Post cleaning and silane application was defined as the use of the above methods plus immersion in 24% H₂O₂, followed by silane application. Studies that did not provide any information about post pretreatment before silanization were categorized separately. Consequently, the findings for post pretreatment should be interpreted with caution and could be considered interesting topics for analysis in future research.

Two additional variables were considered important but discarded from the analysis because limited data was available: intra-radicular dentin pretreatment and aging/storage procedures. Dentin pretreatment before post cementation, was scarcely addressed in the papers included in this review,¹⁵15 Bitter K, Perdigao J, Exner M, Neumann K, Kielbassa A, Sterzenbach G. Reliability of fiber post bonding to root canal dentin after simulated clinical function in vitro. Oper Dent. 2012 Jul-Ago;37(4):397-405.^,2525 Lindblad RM, Lassila LV, Salo V, Vallittu PK, Tjaderhane L. Effect of chlorhexidine on initial adhesion of fiber-reinforced post to root canal. J Dent. 2010 Oct;38(10):796-801. and the role of chlorhexidine in the stability of dentin bonds was already demonstrated,⁵²52 Tjäderhane L, Nascimento FD, Breschi L, Mazzoni A, Tersariol IL, Geraldeli S, at al. Strategies to prevent hydrolytic degradation of the hybrid layer-A review. Dent Mater. 2013 Oct;29(10):999-1011. thus, additional studies on this topic could be advised. The same trend occurred for phosphoric acid application prior to use of self-adhesive resin cements.³⁹39 Bergoli CD, Amaral M, Druck CC, Valandro LF. Evaluation of four cementation strategies on the push-out bond strength between fiber post and root dentin. Gen Dent. 2011 Nov-Dec;59(6):498-502.^,4040 Kadam A, Pujar M, Patil C. Evaluation of push-out bond strength of two fiber-reinforced composite posts systems using two luting cements in vitro. J Conserv Dent. 2013 Sep;16(5):444-48.^,4141 Bergoli CD, Amaral M, Boaro LC, Braga RR, Valandro LF. Fiber post cementation strategies: effect of mechanical cycling on push-out bond strength and cement polymerization stress. J Adhes Dent. 2012 Aug;14(5):471-8. Besides the known benefits of selective enamel etching,⁵³53 Peumans M, De Munck J, Van Landuyt KL, Poitevin A, Lambrechts P, Van Meerbeek B. Eight-year clinical evaluation of a 2-step self-etch adhesive with and without selective enamel etching. Dent Mater. 2010 Dec;26(12):1176-84.^,5454 Federlin M, Hiller KA, Schmalz G. Effect of selective enamel etching on clinical performance of CAD/CAM partial ceramic crowns luted with a self-adhesive resin cement. Clin Oral Investig. 2014 Nov;18(8):1975-84. doi: 10.1007/s00784-013-1173-2. Epub 2014 Jan 10. dentin acid-etching before use of self-etch adhesives or self-adhesive resin cements may perform differently. The dentin bonding mechanism of self-adhesive cements could actually be jeopardized by previous acid-etching, and investigation regarding that effect on the retention of GFPs is recommended. For aging/storage conditions, the wide variability in protocols among studies would result in too many comparisons. Several studies did not perform any kind storage, which should be considered in in vitro studies as it is one of the only mechanisms that may simulate the aging taking place during clinical service.⁵⁵55 Wiskott HW, Nicholls JI, Belser UC. Stress fatigue: basic principles and prosthodontic implications. Int J Prosthodont. 1995 Mar-Apr;8(2):105-16. Several studies also did not compare bond strengths between resin cements. Standardizedin vitro protocols for testing and aging specimens of GFPs cemented into root canals would be useful.

Our results, although based on in vitro studies, provide evidence that may prepare the ground for clinical studies and/or protocols. For instance, because the use of post pretreatment was found to affect post retention in almost all studies, post pretreatment should be considered as a mandatory clinical step and evaluated in a clinical study. In addition, the mode of cement application must be considered an important factor influencing post retention. Following the manufacturers' instructions is strongly suggested in all situations, and using endodontically treated teeth as testing substrate should be a protocol since this factor seems to significantly affect the results of in vitrotests.

Conclusion

We can concluded that endodontic treatment, method of cement application, and post pretreatment are factors that might significantly affect the retention of glass-fiber posts into root canals, mainly when cemented with regular resin cement. Self-adhesive resin cements were found to be less technique-sensitive to luting procedures as compared with regular resin cements.

References

Publication Dates

History