Longevity of bond strength of resin cements to root dentine after radiation therapy

Abstract

Radiation was associated with a decrease in the push-out bond strength and with lower resin cement/root dentine interface adaptation. Self-adhesive resin cement was a better alternative for fibre post cementation in teeth subjected to radiation therapy. The bond strength decreased after 6 months.

Effect of carbodiimide and chlorhexidine on the bond strength longevity of resin cement to root dentine after radiation therapy

“…Radiotherapy has a semi-selective character, and the surrounding tissues are not always preserved (Ro s-Mazurczyk et al 2017) causing side effects in the oral cavity, including radiation carious lesions (Lieshout & Bots 2014, Gupta et al 2015, Dobro s et al 2016, Qing et al 2016, which can cause severe tooth destruction, leading these patients to seek functional and aesthetic restorations. Recent studies have shown that in these cases, the longevity of adhesive restorations is compromised (Naves et al 2012, Rodrigues et al 2018, Yamin et al 2018, confirming the importance of establishing clinical protocols that provide satisfactory dental treatments, thus improving the patient's quality of life.…”

“…Radiotherapy X‐rays act in the presence of water through the formation of free radicals and hydrogen peroxide (Cole & Silver , Fisher et al ), capable of acting as a strong oxidant, causing the denaturation and fragmentation of the dentine collagen fibres network (Pioch et al , Aggarwal , Kochueva et al , Gonçalves et al , Qing et al ), besides activating metalloproteinases (Strup‐Perrot et al , Mcguire et al ). Thus, the degradation of the collagen fibre network is probably related to the lower bond strength values of the resin cement to root dentine observed in the irradiated teeth (Aggarwal , Rodrigues et al , Yamin et al ), as well as in the greater mismatch of the adhesive interface observed in SEM (Figs and ) (Gonçalves et al , Lieshout & Bots ), since the RelyX U200 resin cement bonding mechanism is promoted by acid monomers that, when interacting with the organic part of the resin cement and with the root dentine, demineralize and penetrate the dentine, creating micromechanical retention and chemical bonding to the hydroxyapatite. It does not depend on hybrid layer formation or presence of tags (Ferracane et al ), but rather of an ionization medium for the chemical reaction to occur (Mushashe et al ), which when altered by irradiation may have led to a lower number of chemical bonds between the cement and root dentine (Yamin et al ).…”

“…the degradation of the collagen fibre network is probably related to the lower bond strength values of the resin cement to root dentine observed in the irradiated teeth (Aggarwal 2009, Rodrigues et al 2018, Yamin et al 2018, as well as in the greater mismatch of the adhesive interface observed in SEM (Figs 2 and 3) (Gonc ßalves et al 2014, Lieshout & Bots 2014, since the RelyX U200 resin cement bonding mechanism is promoted by acid monomers that, when interacting with the organic part of the resin cement and with the root dentine, demineralize and penetrate the dentine, creating micromechanical retention and chemical bonding to the hydroxyapatite. It does not depend on hybrid layer formation or presence of tags (Ferracane et al 2011), but rather of an ionization medium for the chemical reaction to occur (Mushashe et al 2016), which when altered by irradiation may have led to a lower number of chemical bonds between the cement and root dentine (Yamin et al 2018).…”

“…The force required for the displacement ( F ) was measured in Newtons (N). In order to calculate the bond strength (BS), the resulting force was converted to Megapascal (MPa) by dividing the lateral area of the intracanal material ( S L ) according to Yamin et al (), where BS = F / S L . To calculate S L , the following formula was used, in which ‘ R ’ is the radius of the fibre post and resin cement in its coronal portion, ‘ r ’ is the radius of the fibre post and resin cement in its apical portion, and ‘ h ’ is the height/thickness of the slice.…”

“…Radiation carious lesions are one of the major complications, differing from conventional lesions by their rapid progression and because they affect surfaces normally free of caries, such as cusp tips and exposed surfaces (Silva et al 2009, Lieshout & Bots 2014, Gupta et al 2015, Dobro s et al 2016, leading to severe tooth destruction (Gupta et al 2015, Dobro s et al 2016 which, in extreme cases, entails the total destruction of the originally healthy dentition within a short time (Dobro s et al 2016), besides causing pulpal and periradicular alterations (Gupta et al 2015, Dobro s et al 2016. In these cases, surgical procedures are restricted because of the risk of osteoradionecrosis (Moon et al 2017), and all attempts are made to maintain even teeth that have total loss of coronal structure (Aggarwal 2009), necessitating root canal treatment and use of intraradicular posts (Aggarwal 2009, Moon et al 2017, Yamin et al 2018.…”