title: Influence of Erbium:YAG laser energies on the microleakage of Class V resin-based composite restorations.
abstract: OBJECTIVE
  To evaluate the influence of three Erbium:YAG laser energies on the microleakage of Class V resin-based composite restorations.
  
  
  METHODS
  60 extracted human premolar teeth stored in 0.12% thymol solution were randomly allocated to three groups. Buccal and lingual box-shaped Class V cavities were prepared on each tooth. One cavity served as the control and was cut using a conventional diamond bur in a high-speed handpiece. The test cavity was prepared using a pulse repetition rate of 5 Hz with 1 of 3 pulse energies; 200 mJ, 240 mJ, and 300 mJ with a 100 mJ dentin finish. The cavities were restored with Scotchbond Multi-Purpose and Z100 and were finished immediately before being stored for 3 months in thymol solution at 37 degrees C. Following thermocycling between 5 degrees C and 55 degrees C for 240 cycles and a further 12 hrs storage, the teeth were immersed in a 2% aqueous solution of methylene blue for 24 hrs. They were then sectioned through the mid-point of the restorations in a bucco-lingual plane and dye penetration was scored as 0 (none) to 4 (to the axial wall) for the enamel and dentin margins of both sections. The worst score for each margin was used for statistical analysis using the Kruskal Wallis and Mann-Whitney U tests at P < 0.05.
  
  
  RESULTS
  When the lased groups were compared, optimum sealing was achieved with energies of at least 240 mJ at the enamel margin and with energies no higher than 200 mJ to finish the dentin margin. However, while all the pulse energies compared favorably to the control group in enamel, a similar result was found only using the 300 mJ, with 100 mJ, finish at the dentin margins.
authors.affiliation: Department of Child Dental Health, Glasgow Dental Hospital and School, Scotland, UK. lizroebuck@mac.com
authors.forename: E M
authors.initials: EM
authors.lastname: Roebuck
authors.forename: W P
authors.initials: WP
authors.lastname: Saunders
authors.forename: C J
authors.initials: CJ
authors.lastname: Whitters
mesh_terms: D000538:Aluminum Silicates; D001641:Bicuspid; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification / Q000295:instrumentation / Q000379:methods; D003743:Dental Enamel / Q000528:radiation effects / Q000648:ultrastructure; D003754:Dental High-Speed Equipment; D003763:Dental Leakage / Q000145:classification*; D003775:Dental Polishing; D003793:Dental Restoration, Permanent / Q000145:classification*; D003804:Dentin / Q000528:radiation effects / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004871:Erbium; D006801:Humans; D007834:Lasers; D008751:Methylene Blue; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry; D012822:Silicon Dioxide; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D015019:Yttrium; D015040:Zirconium
chemical_list: D000538:Aluminum Silicates; D004396:Coloring Agents; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C083568:Z100 composite resin; D015019:Yttrium; D012822:Silicon Dioxide; D004871:Erbium; D015040:Zirconium; D008751:Methylene Blue