Effect of acid etching and laser treatment of dentin surface on intracoronal bleaching efficacy

In the present in vitro study, the efficacy of intracoronal bleaching was evaluated after preparation of dentin with 37% phosphoric acid and Er,Cr:YSGG laser separately and compared with the conventional method in which no surface preparation is used.

The efficacy of bleaching depends on the penetration of the bleaching agent into dentinal tubules. An effective method to enhance permeability of tubules is to remove the smear layer.

Fifty-nine sound human central and lateral incisors were selected. After preparation of access cavities and canal-orifice debridement, the teeth were decoronated apical to the CEJ and artificially stained. Subsequent to glass-ionomer plug placement, the teeth were divided into five groups consisting of three experimental (n = 15) and two control groups (n = 7). Experimental groups were prepared as follows: no surface preparation; surface preparation with 37% phosphoric acid for 30 s; and surface preparation with 0.5-W Er,Cr:YSGG laser for 6 s; respectively. Then the bleaching procedure was carried out. Shade changes before and after bleaching were evaluated. Data were analyzed by using the Kruskal-Wallis test at a significance level of p < 0.05.

No statistically significant differences were found among the experimental groups (p = 0.87).

The results indicated that the efficacy of the intracoronal bleaching procedure subsequent to dentin surface preparation with 37% phosphoric acid or with Er,Cr:YSGG laser is comparable to that of a conventional bleaching procedure, without surface preparation.