In vitro and in vivo evaluation of the effectiveness of three dentin desensitizing treatment regimens.

PURPOSE: To evaluate the in vitro and in vivo effects of three treatment regimens on dentin permeability and reduction of dentin hypersensitivity (DH). METHODS: The desensitization treatments were: Gluma Desensitizer PowerGel (GLU), MS Coat One (MSC), and dentin burnishing with fiber-resin burs (STB). A split-chamber device was used to determine the permeability of dentin slices cut from human molars in vitro. Fluid flow through dentin was recorded with a photochemical method after EDTA cleaning, albumin soaking and desensitization treatment (n = 10). 61 study participants with three severely hypersensitive teeth each were enrolled. Sensitivity was determined with an air stimulus before, immediately after treatment, and after 1, 3 and 6 months, using a verbal rating scale. RESULTS: From the 61 study participants enrolled, 52 completed the trial. Permeability at baseline and after albumin soaking was not significantly different. All treatments produced reduced fluid flow through dentin (P > 0.05). All treatments reduced DH significantly (no or moderate sensitivity). Statistical results revealed significant differences among the treatments (P = 0.03). Mann-Whitney comparisons showed GLU, STB < MSC.

Surface texture and roughness of polished nanofill and nanohybrid resin composites.

Nanofiller-containing resin composites have gained appreciable market share in dentistry due to their claims of high mechanical strength and low polymerization contraction. In this study, the polishability of one nanofill (Filtek Supreme XT/FIL) and three nanohybrid materials (Grandio/GRA, Tetric EvoCeram/TET, Venus Diamond/VED) was investigated using surface profilometry and SEM. After the specimens were cured under a Mylar strip or pre-ground with 600-grit SiC paper, three polishing systems were applied and their polishing effects compared: diamond polishing points, a diamond paste, and urethane-backed aluminum oxide disks. Except for the profilometry results obtained by glass filler-containing GRA and VED with one polishing system that comprised the consecutive application of diamond particles and a diamond polishing paste, the final roughness (Ra) of all other specimens were lower than the clinically acceptable 0.2 microm threshold. The surface textures of the polished nanofill FIL and nanohybrid TET were uniformly smooth, whereas relief polishing effects and filler extrusion of varying extents were seen on the nanohybrid composites GRA and VED.

Discoloration of coating resins exposed to staining solutions in vitro.

The purpose of this in vitro investigation was to study the effects of coffee and tea immersion on surface discoloration of one commercial temporary resin coating material, White Coat (WHC; Kuraray Medical Inc., Tokyo, Japan), and an experimental one, SI-R20209 (SIR; Shofu Inc., Kyoto, Japan). Disk-shaped specimens were prepared, their colors were determined at baseline, and after immersion in water (control), tea and coffee solutions for 24, 48, and 72 hours. Very little discoloration was found with the water-stored specimens. Staining response was most pronounced after coffee immersion for White Coat and after tea immersion for the experimental material, exceeding the clinically acceptable discoloration threshold value of deltaE=3.3. However, most of the resin shades tested are likely to be sufficiently safe against heavy discoloration when used for short-term restoration only.

Compatibility between self-etching adhesive and self-curing resin by addition of anion exchange resin.

OBJECTIVE: The aim was to investigate whether anion exchange resin powder in the OH(-) form, added to the amine component of self-cured resin can deprotonize acid groups of a self-etching adhesive and thus eliminate incompatibility caused by amine neutralization. METHODS: Shear bond strength (SBS) of a self-cured CorePaste (COP), bonded either with all-in-one adhesive iBond (IBO) or with IBO coated with a self-cured experimental resin (SCR), loaded with 0, 8, 16, or 32 wt% of anion exchange resin powder (AER) in OH- form, were determined on 80 enamel and dentin surfaces each after 24 h water storage. IBO specimens were either light-activated or not. Flexural modulus and strength of the four SCR resins were determined by three-point bending. Data was analyzed by one-way ANOVA and Duncan's post hoc test (p<0.05). RESULTS: Enamel SBSs of COP on IBO were 20-25 MPa, in combination with SCR (0 up to 32%) >25 MPa for activated or non-activated IBO. COP on IBO produced no bond on dentin, with the non-loaded SCR 5-10 MPa SBS was achieved, and 15 and 21 MPa were measured with the three AER-loaded SCRs on activated and non-activated IBO, respectively. Flexural moduli of SCR with 0 and 8% AER were higher than with 16 and 32%. Flexural strengths were not significantly different. SIGNIFICANCE: Addition of anion exchange resin to the amine component of self-cured resin is an effective means of enhancing the bond strength on dentin and to prevent amine neutralization through the acid groups of self-etching primer adhesives.