Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface

Abstract

The aim of this study was to evaluate the thickness of resin cements in the root thirds when using conventional fiberglass posts (CP) and relined fiberglass posts (RP) in weakened roots and to evaluate the morphological characteristics of the dentin-resin interface. Forty human maxillary anterior teeth had the crown sectioned below the cemento-enamel junction. The canals were endodontically treated and weakened with diamond burs. Teeth were divided into four groups (n = 10): Group 1 -CP + RelyX ARC; Group 2 -CP + RelyX U200; Group 3 -RP + RelyX ARC; and Group 4 -RP + RelyX U200. Prior to luting, 0.1% Fluorescein and 0.1% Rhodamine B dyes were added to an adhesive and resin cement, respectively. Slices were obtained from the apical, middle, and cervical thirds of the root. Confocal laser scanning microscopy images were recorded in four areas (buccal, lingual, mesial, distal) of each third. In each area, four equidistant measures of the resin cement were made and the mean value was calculated. The interface morphology was observed. The data were submitted to three-way ANOVA and Tukey's test (α = 0.05). The interaction between fiberglass posts, resin cement, and root thirds was significant (p < 0.0001). The resin cement thicknesses were significantly lower for RP in comparison with CP, except in the apical third. There was no significant difference between the resin cements for RP. There was formation of resin cement tags and adhesive tags along the root for RP. RP favored the formation of thin and uniform resin cement films and resin tags in weakened roots.

Bond strength values of fiberglass post to flared root canals reinforced with different materials

“…5 Although the ideal thickness of the resin cement for glass fiber post cementation remains unknown, prospective and retrospective clinical studies indicate that a higher frequency of debonded fiberglass posts occurs when the thickness of the cement layer is larger. 5 Thus, some alternatives for reducing the layer of the resin cement have been suggested in the literature such as the use of accessory fiber posts, 6 direct and indirect anatomical post 6,7,8,9 and root reinforcement with a restorative material. 8,10,11 Theoretically, the latter approach seems to be promising; however, the study by Gomes et al 8 reported that root reinforcement with a conventional light-cured composite resin showed very low bond strength values, which could be attributed to inadequate polymerization in the deeper regions of the root canal, 11 affecting the material properties.…”

Effect of intra-radicular cleaning protocols after post-space preparation on marginal adaptation of a luting agent to root dentin

“…Studies on the adaption behavior between endodontic materials and root canal walls are needed to test the adhesive performance of different products and to study experimental variables [1,7]. A variety of experimental setups have been described for this purpose [7,13,[26][27][28][29], and much of the current understanding on this subject has been based on studies using scanning electron microscopy (SEM) [27,30]. SEM is a 2-dimen-sional method that allows qualitative and quantitative assessments of the morphological characteristics of the resin-dentin interface [27].…”

“…SEM is a 2-dimen-sional method that allows qualitative and quantitative assessments of the morphological characteristics of the resin-dentin interface [27]. However, technical artifacts can occur during specimen preparation [29]. Vichi et al [30] demonstrated that gaps noted in SEM images may be caused by the vacuum pressure of the sputtering device and SEM chamber.…”

Effect of lubricant substances on the bond strength of relined posts to root canals

“…This clinical condition presents a challenge to cementation of GFP. It's already stated in literature that a gap of about 50 µm between post and canal walls it is recommended for a precise fit of the post to the root canals walls [14][15][16], since the lack of adaptation of the post could generate a thick layer of the luting agent and non-homogeneous distribution of the occlusal forces in the interface post-cement [17,18], leading to lower bond strength values [9,19,20].…”