Influence of Bleaching Agents and Desensitizing Varnishes on the Water Content of Dentin

Abstract

The dehydration of tooth structure is discussed as a possible factor for tooth hypersensitivity arising during bleaching; however, it still remains unclear to what extent glycerinebased bleaching gels dehydrate dentin and whether dentin hydration can be maintained by protective dentin varnishes. SUMMARYThis in vitro study investigated the possible dehydration of dentin caused by bleaching agents. Furthermore, it tested whether protective dentin varnishes can maintain the physiological moisture of dentin during bleaching treatment. Fifty-five standardized dentin cylinders were prepared from freshly extracted bovine incisors under constant water irrigation. Prior to bleaching, the treatment specimens were conditioned at room temperature in a hygrophor for 14 days. The samples were divided into 11 groups. The Group A specimens, which were completely dehydrated, and Group B, which was stored for 2 weeks in a hygrophor, served as controls (A, B n=5). The other samples (n=10 each group) were coated with Vivasens [VS] (C), Bilfuorid [BF] (D) and Seal&Protect [SP] (E). Five specimens from each group (C-E) were subsequently treated with an experimental bleaching gel (Exp BG) (20% carbamide peroxide [CP], glycerine-based gel): Cb, Db, Eb. The remaining specimens were bleached with Exp BG (F) only, Vivastyle (G: 16% CP, glycerine-based gel) or Vivastyle Paint On (H: 6% CPvarnish) for 7 days (n=5 each group) with bleaching time for gels: 2 hours/day, paint on: 20 minutes/day. After the respective treatments, the overall water content of each specimen was determined using the analytical method of KarlFischer-titration. The water content of bovine dentin (Group B, mean%±SD) obtained in this

Diffusion of peroxides through dentine in vitro with and without prior use of a desensitizing varnish

“…This was also shown in an in vitro simulation [43]. Additionally, Vivasens is able to reduce dentin dehydration during bleaching, which is also supposed to contribute to bleaching-induced hypersensitivities [44]. …”

The role of fluoride in the preventive management of dentin hypersensitivity and root caries

“…The natural desensitization process, although slow, is nature's protection, allowing dentinal sclerosis through secondary dentin formation. Different desensitizers and fluoride measures also show various potential abilities to promote partially or total obstruction of dentin tubules and reduce DHS and tooth wear [14, 15]. The concept of tubule occlusion as a method of reducing DHS is a logical conclusion from the hydrodynamic hypothesis.…”

Dehydration-induced shrinkage of dentin as a potential cause of vertical root fractures

“…With the periodontal blood supply remaining, a moisture gradient from the root canal wall to the outer surface of a root may be established. Numerous authors have already addressed the factor ''moisture content of dentin'' which decreases with patient's age (Arola and Reprogel, 2005), after endodontic treatment (Soares et al, 2007;Kishen and Asundi, 2005) and after bleaching (Betke et al, 2006) making these teeth more brittle than vital teeth (Kishen and Asundi, 2005;Jameson et al, 1993). Dehydrated dentin however has been shown to have a decreased toughness (Arola and Reprogel, 2005;Jameson et al, 1993) and fatigue crack growth resistance (Bajaj et al, 2006) and shows higher strains after the application of heat and cold stimuli (Shrestha et al, 2010).…”