Protocols for Mechanical Cleaning of the Post Space on the Bond Strength Between Root Dentin and Cementation System

Abstract

SUMMARY Objective: To evaluate the effects of mechanical versus chemical cleaning protocols for cleaning the root dentin surface before cementation of fiberglass posts for their effect on the bond strength, failure mode, and dentinal penetration of the cementing agent using an etch-and-rinse adhesive system on dentin prepared to receive a fiberglass post. Methods: Forty roots of bovine teeth were endodontically treated and prepared for fiber post cementation. The specimens were randomized into 4 groups of 10: Control group (CO) - irrigation with 2.5% NaOCl; DW group- irrigation with distilled water; RB group - rotating brush for cleaning root canals, and CUI group - continuous ultrasonic irrigation. The fiberglass posts were cemented, and the specimens were immersed in distilled water for 6 months. A push-out test was performed on the cervical, middle, and apical thirds of the samples. Dentinal penetration of the cementing agent and the fracture pattern were evaluated by laser confocal microscopy. Statistical analysis was performed using analysis of variance (ANOVA) and post hoc Tukey tests (α=0.05). Results: The RB and CUI groups showed significantly higher bond strength values when compared to the Control and DW groups (p<0.05). In addition, in the control and DW groups, the apical third presented lower bond strength values when compared to middle and cervical thirds. Conclusion: While DW showed the highest incidence of adhesive type failure, CUI resulted in the highest dentinal penetration of the cementing agent (p<0.05). RB and CUI resulted in the highest bond strength between cementation system and root dentin. In addition, CUI favored greater dentinal penetration of fiberglass post cementing agent.

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

“…It is important to bear in mind that the action of drills used to remove filling material from the root canal to create space for a post produces a smear layer rich in endodontic sealer and gutta-percha remnants plasticized by the heat of the drill's friction [5,6]. This smear layer is difficult to remove [8,18] and can act as an insulator against any type of adhesive material intended to promote bonding to root dentin [6], which can reduce the chemical penetration of self-adhesive resin cement and, consequently, negatively influence the post cementation process [1,6,9,11,28]. There seems to be evidence in the literature that the chances of success of procedures performed inside the canal are increased when the smear layer is removed [1,2,6,9,11].…”

“…Regardless of the technique used, the deposition of an irregular, granular and amorphous structure, known as the smear layer, on the root canal walls after post-space preparation is indisputable [3,[5][6][7][8]. The presence of this smear layer on root canal walls has been associated with unsatisfactory union between fiber post and root dentin [2,7,9,10], since it makes it difficult for the luting agent to penetrate the dentinal tubules and reduces the area of contact between the cement and the dentin [11].…”

“…The composition and morphology of the smear layer are dependent on the instrument used to prepare the root dentin walls, the pressure exerted by the operator, the solutions employed, and the operative technique chosen [8,10]. The smear layer associated with post-space preparation is similar to that of retreatment, comprising organic and inorganic components, remnant chemical substances, gutta-percha, and endodontic sealer [3,4,6,8]. This is notably more difficult to remove, requiring additional procedures [8,18].…”

“…The smear layer associated with post-space preparation is similar to that of retreatment, comprising organic and inorganic components, remnant chemical substances, gutta-percha, and endodontic sealer [3,4,6,8]. This is notably more difficult to remove, requiring additional procedures [8,18]. Agitation of chelating substances inside the root canal has been recommended for better removal of the smear layer [21].…”

Effect of mechanical cleaning protocols in the fiber post space on the adhesive interface between universal adhesive and root dentin

“…Thus, a mechanical cleaning protocol is an alternative procedure, which could be combined with different chemical solutions in order to adequately prepare the dentin surface for adhesive procedures. In addition, mechanical cleaning protocols could benefit of the use of distilled water and then it will avoid the presence of free radicals that could interfere with resin cements (Alencar et al, 2021).…”