title: Preimpression troughing with the diode laser: A preliminary study.
abstract: BACKGROUND
  The mechanical-chemical technique and the use of a laser are methods for displacing the gingiva to make an accurate impression of the preparation for a complete crown. The tissue needs to be displaced and the hemorrhage controlled to capture the prepared finishing line in the impression. The degree of undesirable gingival recession after these displacement techniques is unknown.
  
  
  OBJECTIVE
  The purpose of this pilot clinical study was to clinically monitor and compare the regeneration of the gingival tissue by using 2 methods of gingival displacement in the same participant: the mechanical-chemical technique with double cords impregnated with aluminum chloride and the 810 nm diode laser (Odyssey; Ivoclar Vivadent AG).
  
  
  METHODS
  A total of 6 participants needing 2 crowns on natural teeth were included in this study. At the first visit, the teeth were prepared with a 0.5-mm subgingival finishing line and interim crowns were fabricated. One of the teeth was randomly assigned to the double cord technique with 2 (# 000 and # 1) impregnated 5% aluminum chloride cords and the other to the 810 nm diode laser. An adjacent tooth served as a control. A device was made that would function as a fixed reference point for the measurements at different time intervals. A notch was created on the device to position the digital ruler between the occlusal notch and the free gingival margin to measure the distances. The measurements were recorded for each patient before displacement of the gingiva and at the time of cementation of the definitive crowns. The patients were followed at 1 week, 3 weeks, and 8 weeks after cementation of the definitive crowns.
  
  
  RESULTS
  The amount of recession with the cord impregnated with aluminum chloride was 0.26 mm 8 weeks after cementation of the definitive crowns with a range between 0.00 mm and 0.72 mm. The diode laser showed an average recession of 0.27 mm with a range between 0.01 mm and 0.68 mm.
  
  
  CONCLUSIONS
  This study found an average loss of gingival height of 0.26 mm for the double cord technique and 0.27 mm for the laser. The amount of recession was considered not clinically significant.
authors.affiliation: Private practice, Alkmaar, The Netherlands. Electronic address: mjstuffken@gmail.com.
authors.forename: Marguaritha
authors.initials: M
authors.lastname: Stuffken
authors.affiliation: Associate Professor, Department of Prosthodontics, New York University College of Dentistry, New York, NY.
authors.forename: Farhad
authors.initials: F
authors.lastname: Vahidi
mesh_terms: D002484:Cementation; D003442:Crowns; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D005881:Gingiva / Q000033:anatomy & histology*; D005889:Gingival Recession; D060745:Gingival Retraction Techniques / Q000295:instrumentation / Q000592:standards; D006801:Humans; D054023:Lasers, Semiconductor
chemical_list: D003760:Dental Impression Materials