Dentin Permeability of a New Protective Coating Material

Objectives:  Compare the convective fluid movements across dentin after placement of an experimental coating material, versus a nanofilled adhesive and an RMGI liner.

Methods:    Crown segments were cut from extracted unerupted third molars, and cemented onto a plexiglass slab fitted with a stainless steel tube allowing filling of the pulp chamber with water under 140 cm H₂O of pressure.  This was attached to a device that measured fluid movement through the dentin.  The dentin surface was etched with 37% phosphoric acid for 15 sec, presenting a model for the exposed tubules typical of root sensitivity.  The dentin was coated with either 3M™ ESPE™ Adper™ Single Bond Plus Adhesive (SBP), 3M™ ESPE™ Vitrebond™ Plus Liner/Base (VBP), or EXM-713 experimental coating material.   EXM-713 is a resin-modified glass ionomer coating material in a paste/paste delivery.  Permeabilty was measured on the etched and the coated dentin for each sample.  Data were analyzed via one-way ANOVA and compared with Tukey's T-test (p<0.05).

Results:  The permeability in microliter/min @140 cm H₂O is shown below.

Material	n	Etched	Coated	% Reduction
SBP	11	13.8(5.6)a	0.9(1.3)b	93.3(8.0)c
EXM-713	12	10.5(6.1)a	1.5(2.4)b	87.7(18.6)c
VBP	11	12.1(6.1)a	1.3(1.4)b	87.9(13.9)c

Groups identified by the same superscript letter are not significantly different (p>0.05).

In all groups the permeability of the coated surface was much lower than the etched surface.  Etched permeability was equivalent for all groups; coated permeability was equivalent for all groups; percent reduction in permeability was equivalent for all groups.

Conclusions: SBP,  EXM-713, and VBP are effective at sealing open dentin and reducing fluid flow through dentin.  EXM-713 was equivalent  to SBP and VBP in its ability to reduce fluid flow.