title: In vitro evaluation of microleakage under ceramic and metal brackets bonded with LED and plasma arc curing.
abstract: OBJECTIVE
  The aim of the present study was to evaluate these two high intensity light curing units regarding microleakage beneath metal and ceramic brackets.
  
  
  METHODS
  A total of 60 freshly extracted human premolar teeth were randomly divided into four groups of 15 samples; group I: Metal bracket + LED cured, group II: Ceramic bracket + LED cured, group III: Metal bracket + plasma arc cured, group IV: Ceramic bracket + plasma arc cured. After photopolymerization, the teeth were immersed in water and thermocycled (500 cycles between 5 and 55). Specimens were further sealed with nail varnish and stained with 5% basic fuchsin for 24 hours. All of the teeth were sectioned with two parallel longitudinal occlusogingival cuts and examined under a stereomicroscope. The microleakage was measured with a digital caliper and scored from 0 to 3 for marginal microleakage at the bracket-adhesive and adhesive-enamel interfaces from both the occlusal and gingival margins.
  
  
  RESULTS
  Microleakage was detected in all groups. The plasma arc cured group showed less microleakage than light emitting diode (LED) cured in all samples at the enamel-adhesive interface at the gingival margin (ceramic brackets, p = 0.009 and metal brackets, p = 0.005). The plasma arc cured samples showed less microleakage than LED cured in metal brackets at the adhesive-brackets interface at the occlusal margin (p = 0.033). While curing with an LED unit, ceramic brackets displayed significantly less microleakage than metal ones at the gingival margin of adhesive-enamel interface (p = 0.013). The gingival margin in all groups exhibited higher microleakage compared with those observed in occlusal sides in all sample groups (p < 0.001).
  
  
  CONCLUSIONS
  1. LED units cause more microleakage than plasma arc units. 2. In all groups the microleakage at the gingival margin is greater than the occlusal margin.
  
  
  CONCLUSIONS
  The microleakage formation permits the passage of bacteria and oral fluids initiating white spot lesions beneath the bracket base.
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Abdolrahim
authors.initials: A
authors.lastname: Davari
authors.forename: Soghra
authors.initials: S
authors.lastname: Yassaei
authors.forename: Mariam
authors.initials: M
authors.lastname: Karandish
authors.forename: Fateme
authors.initials: F
authors.lastname: Zarghami
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D001641:Bicuspid / Q000648:ultrastructure; D002516:Ceramics / Q000737:chemistry*; D004396:Coloring Agents; D055117:Curing Lights, Dental / Q000145:classification*; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry* / Q000528:radiation effects; D003743:Dental Enamel / Q000648:ultrastructure; D003763:Dental Leakage / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets / Q000145:classification*; D010756:Phosphoric Acids / Q000737:chemistry; D055668:Photochemical Processes; D058105:Polymerization; D012394:Rosaniline Dyes; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D003722:Dental Alloys; D003738:Dental Cements; D003764:Dental Materials; D010756:Phosphoric Acids; D012394:Rosaniline Dyes; D014867:Water; C025485:basic fuchsin; C030242:phosphoric acid