Effect of two desensitizing agents on dentin permeability in vitro

Abstract

Objective The aim of this in vitro study was to investigate the effect of two desensitizing agents and water on hydraulic conductance in human dentin.Material and Methods GLUMA Desensitizer PowerGel (GLU) contains glutaraldehyde (GA) and 2-hydroxyethyl methacrylate (HEMA), and Teethmate Desensitizer (TD) is a powder comprising tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) that is mixed with water. Deionized water was used as a negative control (CTR). Thirty discs with a thickness of 1.2 mm were cut from the coronal dentin of the third molars and cleaned with 0.5 M EDTA (pH 7.4). After being mounted in a split-chamber device, the discs were pressurized with water at 1 kPa and 3 kPa in order to measure flow rates with a highly sensitive micro-flow sensor and to calculate hydraulic conductance as a baseline value (BL). Following the application of GLU, TD, and CTR (n=10), hydraulic conductance was remeasured with intermittent storage in water after 15 min, 1 d, 1 w, and 1 m. Reduction in permeability (PR%) was calculated from hydraulic conductance. Data were statistically analyzed using nonparametric methods (α<0.05). Representative discs were inspected by SEM.Results PR% for GLU and TD were 30-50% 15 min and 1 m after their application. Post hoc tests indicated that PR% of CTR was significantly greater than those of GLU and TD at all time points tested. The PR% of GLU and TD were not significantly different. SEM examinations showed noncollapsed collagen meshes at the tubular entrances after GLU, and crystalline precipitates occluding the tubular orifices after TD, whereas CTR specimens showed typical patterns of etched dentin.Conclusions The present study on hydraulic conductance in dentin discs treated with two chemically different desensitizing agents and water as a control demonstrated that both products may be characterized as effective.

Effect of Erosion/Abrasion Challenge on the Dentin Tubule Occlusion Using Different Desensitizing Agents

“…Professionally applied desensitizing agents include sealers, varnishes, gels, pastes or adhesive systems. These products generally contain fluorides, oxalates, potassium nitrate and calcium phosphate, already investigated in vitro for their ability to occlude dentinal tubules and reduce dentin permeability (5)(6)(7)(8)(9). The precipitates or barriers formed by the desensitizing agents may be removed or dissolved between applications or shortly after (10).…”

A photochemical method for in vitro evaluation of fluid flow in human dentine

“…We developed a new measuring system to determine dentine permeability 10,11 and used it to investigate the time needed to transfer a liquid through the patent tubules of human dentine specimens.…”

“…10,11 Two cylindrical acrylic chambers were sealed with O-rings on each sliced surface of the specimen and clamped in a metal frame connected with the ring. The chamber on the occlusal side of the sliced surface was sealed with a glass cover slip and filled with a chemical illuminant reagent (aqueous solution of 0.02% luminal [5-amino-2, 3-dihydro-1, 4-phtalazinedione] and 1% sodium hydroxide).…”

Effect of artificial saliva on permeability of dentin treated with phosphate containing desensitizer measured by digital flow meter

“…However, the testing method had a paramount effect on the result of in vitro trials. Human dentin disc models, as originally introduced in 1981 by Greenhill and Pashley 8) are still frequently used with some modifications to assess hydraulic conductance as a measure for the ease of fluid flow through dentin [9][10][11][12][13][14][15] , however a relatively high pressure should be applied the dentin disc to obtain a clear results and this high pressure could not be assumed to occur in vivo. Recently a new fluid flow measurement using a highly sensitive micro digital flow meter was introduced, which could determine a little flow quantity exactly under pressure in vivo; therefore, precision and reliability are improved in comparison with a previous fluid flow measurement…”