title: Enamel resistance to demineralization following Er:YAG laser etching for bonding orthodontic brackets.
abstract: BACKGROUND
  Several studies have shown that laser-etching of enamel for bonding orthodontic brackets could be an appropriate alternative for acid conditioning, since a potential advantage of laser could or might be caries prevention. This study compared enamel resistance to demineralization following etching with acid phosphoric or Er:YAG laser for bonding orthodontic brackets.
  
  
  METHODS
  Fifty sound human premolars were divided into two equal groups. In the first group, enamel was etched with 37% phosphoric acid for 15 seconds. In the second group, Er:YAG laser (wavelength, 2 940 nm; 300 mJ/pulse, 10 pulses per second, 10 seconds) was used for tooth conditioning. The teeth were subjected to 4-day PH-cycling process to induce caries-like lesions. The teeth were then sectioned and the surface area of the lesion was calculated in each microphotographs and expressed in pixel. The total surface of each specimen was 196 608 pixels.
  
  
  RESULTS
  Mean lesion areas were 7 171 and 7532 pixels for Laser-etched and Acid-etched groups, respectively. The two sample t-test showed that there was no significant difference in lesion area between the two groups (P = 0.914).
  
  
  CONCLUSIONS
  Although Er:YAG laser seems promising for etching enamel before bonding orthodontic brackets, it does not reduce enamel demineralization when exposed to acid challenge.
authors.affiliation: Dental Research Center, Islamic Azad University, Tehran, Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Ahrari
authors.forename: Maryam
authors.initials: M
authors.lastname: Poosti
authors.forename: Pourya
authors.initials: P
authors.lastname: Motahari