The Effect of Simulated Field Storage Conditions on Dental Restorative Materials for Military Field Use

Dental readiness, one critical component of medical readiness, is adversely impacted by dental emergencies. Many dental emergencies require restorative materials such as glass ionomers, resins, and zinc oxide eugenols to remedy them. The Authorized Dental Allowance List (ADAL) and Authorized Medical Allowance List (AMAL) contain the equipment and materials used by Navy dentists to treat Sailors and Marines. These supplies are subjected to harsh storage conditions on deployments. Much is known about how materials behave when stored at room temperature, but less is known about how their properties are affected after exposure to high temperatures and humidity. We subjected five dental restorative materials to storage in aggravated conditions, and then tested them to determine which products are more robust.

Unopened packages of Fuji Triage, Fuji IX GP (both GC America Inc., Alsip, Illinois), TPH Spectra ST Low Viscosity, Intermediate Restorative Material (both Dentsply Sirona, York, Pennsylvania), and Herculite XRV (Kerr Corporation, Orange, California) were exposed to 0, 5, or 10 days' storage at 30-60°C with 95% relative humidity. After storage in these aggravated conditions, we tested the compressive strength, hardness, elastic modulus, flexural strength, flexural modulus, sorption, and solubility of each material.

The physical properties of all materials were affected by storage in aggravated conditions, though the properties of some materials degraded more than others. Both glass ionomers, Fuji Triage (P = 0.0012) and Fuji IX GP (P = 0.0031), and the composite Herculite XRV (P = 0.0253) lost compressive strength after 5 or 10 days in aggravated conditions. The hardness values for all materials were affected (P < 0.05) by the aggravated conditions, though the elastic modulus of TPH Spectra was not affected (P > 0.05). None of the materials lost flexural strength (P > 0.05) or had changes in their flexural modulus (P > 0.05). The water sorption behavior of Fuji Triage (P = 0.0426) and Fuji IX GP (P = 0.0201) changed after 10 days of aggravated storage, and the solubility of all materials was altered by the harsh conditions.

Some materials degrade more than others in aggravated conditions. Both resin composite materials were more resistant to high temperatures and humidity levels than the glass ionomers tested. These changes in physical characteristics should be considered when reviewing or optimizing the ADAL/AMAL for different projected operational environments.