Hypo and hyperbaric pressure effect on the fracture resistance of three types of dental crowns: PFM, LD, and Y-TZP.

OBJECTIVES: Loss of dental restorative materials can lead to severe problems in some occupations, especially diving and piloting. This study aimed to compare the fracture resistance of three types of materials (PFM, LD, and Y-TZP) under hyper and hypobaric conditions to simulate diving and flight and control conditions for introducing a suitable restorative material for individuals under these conditions. METHODS: Three dental crowns related to the upper premolar were prepared. Seven pieces of these materials were subjected to hyperbaric pressure and seven to hypobaric pressure. Cases related to the flight conditions were investigated after exposure to low-pressure conditions equivalent to 0.5 atm, while cases pertaining to diving conditions were exposed to a pressure of 2 atm. After using the pressure cycles, the crowns were subjected to fracture tests with occlusal force. Further, a finite element study on maxillary premolar behavior was performed under the three working conditions. RESULTS: A significant difference between each crown in flight condition was noted. In the diving condition, no significant difference between LD and Y-TZP was observed, while in the control condition, no significant difference between PFM and Y-TZP was noted. Finite element results showed that PFM exhibited higher principal stresses in all working conditions. CONCLUSIONS: This study shows that PFM has better resistance to failure in diving and flight conditions among other groups, while Y-TZP offers better resistance in control conditions. Further studies on other working conditions and different experimental conditions on dental crowns are needed.