title: Low force cementation.
abstract: OBJECTIVE
  The marginal adaptation of full coverage restorations is adversely affected by the introduction of luting agents of various minimum film thicknesses during the cementation process. The increase in the marginal opening may have long-term detrimental effects on the health of both pulpal and periodontal tissues. The purpose of this study was to determine the effects of varying seating forces (2.5, 12.5, 25 N), venting, and cement types on post-cementation marginal elevation in cast crowns.
  
  
  METHODS
  A standardized cement space of 40 microns was provided between a machined gold crown and a stainless steel die. An occlusal vent was placed that could be opened or closed. The post-cementation crown elevation was measured, following the use of two commercially available capsulated dental cements (Phosphacap, and Ketac-cem Applicap).
  
  
  RESULTS
  The results indicate that only the combination of Ketac-Cem Applicap and crown venting produced post-cementation crown elevation of less than 20 microns when 12.5 N seating force was used. Higher forces (25 N) and venting were required for comparable seating when using Phosphacap (19 microns).
  
  
  CONCLUSIONS
  The amount of force required to allow maximum seating of cast crowns appears to be cement specific, and is reduced by effective venting procedures.
authors.affiliation: School of Dental Science, University of Melbourne, VIC, Australia.
authors.forename: P R
authors.initials: PR
authors.lastname: Wilson
mesh_terms: D002484:Cementation / Q000379:methods*; D003442:Crowns; D003738:Dental Cements / Q000737:chemistry*; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D006801:Humans; D008277:Magnesium Oxide; D011076:Polycarboxylate Cement; D014086:Tooth Mobility / Q000517:prevention & control; D015034:Zinc Oxide; D015036:Zinc Phosphate Cement
chemical_list: D003738:Dental Cements; D011076:Polycarboxylate Cement; D008277:Magnesium Oxide; D015036:Zinc Phosphate Cement; C040235:Ketac-cem; C086629:Phosphacap; D015034:Zinc Oxide