Removal of
smear layer and disinfection of canals are important objectives of teeth root canal cleaning. In order to achieve this purpose, rinsing substances, intra canal drugs as well as ultrasound are used. Today, use of
laser to remove
smear layer and to disinfect root canals has increasingly attracted the attentions. Till now different
lasers such as CO2, Nd:YAG, Er:YAG, Er,Cr:YSGG have been used for debris and smear removal from the canals. Numerous studies have shown that Er:YAG is the most appropriate
laser for intra canal debris and smear removal. In addition different
laser wavelengths have been used directly or as an adjunctive to disinfect canals.
Laser light can penetrate areas of canals where irrigating and disinfecting solutions cannot reach, like secondary canals and deep dentinal tubules and also can eliminate microorganisms. Different studies have confirmed the penetration of
Nd:YAG laser in deep dentin and reduction of microorganisms penetration. But studies on comparison of antibacterial effects of
Nd:YAG laser with
sodium hypochlorite showed effectiveness of both, with a better effect for
sodium hypochlorite. Studies performed in relation with anti-microbial effects of
Diode laser with various parameters show that this
laser can be effective in reducing intra canal bacterial count and penetration in the depth of 500 microns in dentin. In studies performed on
Diode laser in combination with canal irrigating solutions such as
sodium hypochlorite and oxygenated water better results were obtained. Although studies on disinfection by the
Erbium laser family show that use of this
laser alone can be effective in disinfecting canals, studies evaluating the disinfecting effects of this
laser and different concentrations of
sodium hypochlorite show that the latter alone is more effective in disinfecting canals. And better results were obtained when
Erbium laser was used in combination with
sodium hypochlorite irrigating
solution in canals. Results of the aforementioned articles indicate that this
laser is effective in combination with a rinsing
solution such as
sodium hypochlorite. Results from studies including several types of the different Er:YAG, Ho:YAG, Nd:YAG, Er,Cr:YSGG
lasers in disinfecting canals showed that all wavelengths used in disinfection for different thicknesses of dentin were efficacious without damaging thermal effect. Considering that use of different
lasers in canals can be accompanied with temperature increase which can sometimes lead to damages to teeth and surrounding tissues, thus the use of photochemical phenomenon for elimination of microorganisms have attracted attention of many researchers. Studies in this field imply the efficacy of this method in reducing canal bacterial count and recommend its use as an adjunctive after biomechanical preparation of canals. Results from performed studies show removal of intra canal debris and
smear layer by different
lasers and particularly the
Erbium laser family. Furthermore various
laser wavelengths, particularly of Diode and
Nd:YAG lasers can be effective in reducing intra canal microbial count. Maximum effect is obtained when
laser light is used in canals in combination with
sodium hypochlorite irrigating substance in appropriate concentration. Therefore use of
laser energy can improve success rate of root canal treatments.