title: Crown Cementing Strategy for Naval Divers.
abstract: BACKGROUND
  A large number of personnel working in hyperbaric environment such as divers and submariners during escape drills report to the out patient department with split teeth, displacement of restoration and pain during ascent after diving. These symptoms are probably attributable to dental barotraumas. Therefore, a need was felt to undertake a study in this area, with a specific interest for treating these patients.
  
  
  METHODS
  Sixty extracted single rooted premolar teeth were prepared and full cast crowns were cemented. Out of these, 20 were prepared with zinc phosphate, 20 with glassionomer and 20 with resin cement. After seven days of storage, each of the teeth in experimental group was pressure cycled 15 times to 3 atmospheres after which the force required to dislodge the crowns was tested on an Instron testing machine.
  
  
  RESULTS
  A significant difference was found (student's t test p value < 0.01) between the force required to dislodge the crowns with zinc phosphate cemented control group (141.70 ± 38.62) and experimental group (16.92 ± 10.13). Similarly a significant difference was observed in the glassionomer cemented control group (184.33 ± 25.33) and experimental group (90.50 ± 34.07). On the other hand, no difference was found between the resin cemented control group (289.15 ± 81.48) and experimental (279.43±87.48) group.
  
  
  CONCLUSIONS
  Within the limitations of this study and based on the results, it was concluded that environmental pressure cycling affected the retention of crowns cemented with zinc phosphate and glassionomer cement. Panavia resin cement used in this study appeared to be unaffected by environmental pressure cycling. On the basis of the results of this study, dental surgeons should consider cementing fixed prosthesis with resin cements for patients who are exposed to marked variations in environmental pressure, such as divers and submariners during escape drills.
authors.affiliation: Classified Specialist (Prosthodontics), AFDC, New Delhi.
authors.forename: A
authors.initials: A
authors.lastname: Khanna
keywords: Barodontalgia; Crowns; Luting cements