LETTER TO EDITOR.

Abstract

Dear Editor,This letter is regarding an article published in your journal titled “Comparison of the Mechanical Properties and Push-out Bond Strength of Self-adhesive and Conventional Resin Cements on Fiber Post Cementation” (http://doi:10.2341/21-015-L).We would like to compliment the authors on the detailed comparative study of the mechanical properties and push-out bond strengths, which result when glass fiber posts are cemented with self-adhesive resin cements and conventional resin cements.In this correspondence, we would like to draw attention to the property of the RelyX Ultimate cement, which has an integrated dark cure activator (Sodium Toluene 4- sulfinate) for Scotchbond Universal Adhesive rendering it less dependent on light curing.1Because of this, we feel that the requirement for light to reach the deeper thirds of the root canal spaces and its subsequent impact on the bond strength may not be as critical as reported by the authors. We would appreciate it if the authors could enlighten us on our observation.Dear Dr Grover and Dr Shetty,On behalf of all authors, I am pleased to respond your letter.First, I would like to state that your comments are deeply appreciated. Second, the authors would like to point to the importance of performing scientific research that confirms the commercial claims of materials manufacturers. In that regard, although dual-cured resin cements were developed to benefit from the self- and light-curing mechanisms, previous studies show that the self-cure mechanisms on dual-cure cements, do not necessarily result in mechanical characteristics that are as good as those obtained whether by dual- or light-curing of the cements.1–8 These results are confirmed by a recent study, which included the Rely X Ultimate cement, finding that despite the presence of a dark-cure activator, self-curing produced a lower degree of conversion and hardness compared to the light-cure mode.8 In general, regarding dual-curing cements, previous studies showed that the polymerization of dual cure resin cements is not optimal in the absence of light.1–8Thus, the authors consider that the argument regarding the importance of light-curing the Rely X Ultimate remains valid, especially in the apical third of the root, because self-curing mechanical properties still benefit greatly from light-curing.State University of CampinasUniversidade Estadual de CampinasOperative DentistryAv Limeria 901Piracicaba, São Paulo 13414-903 Brazilemail: mrs.santi@hotmail.com