The direct dental restoration process involves drying the dentin substrate, which can cause significant strain in the dentin and affect the bonding efficiency of the restoration. To investigate the impact of relative humidity variation during dental surgery on restoration lifetime, a study was conducted to measure the dilatation of dentine under changes in relative humidity and its effect on dentin elastic properties. The study used an environmental chamber to control temperature and humidity on carefully prepared samples placed on a compression device, with an optical microscope to precisely measure surface strain after quantifying measurement noise. Results showed that dentin dilates when relative humidity increases, with a coefficient of hygroscopic expansion typically at 6.10-3 % (%RH)-1, occurring within ten minutes. Young modulus and Poisson's ratio were not affected by relative humidity variation. The study concluded that hygroscopic expansion is an order of magnitude larger than thermal expansion during dental surgery (around 0.3% compared to 0.03%), which may decrease the life-expectancy of a restoration despite being low levels for dental rupture. This research highlights the importance of considering relative humidity during dental procedures to ensure optimal restoration outcomes and longevity for improved patient care.
When dentists fix teeth, they need to dry them first. This can make it harder for the fixing to stick properly. Scientists did a study to see how humidity (how much water is in the air) affects this. They used a special room to control the humidity and measured how much the teeth moved. They found that when there was more water in the air, the teeth moved more and this could make the fixing not last as long. Dentists need to think about humidity when they fix teeth so that they can do a good job and help their patients.
Definitions
- Direct dental restoration process: When dentists fix a tooth by putting something on it directly.
- Dentin substrate: The part of your tooth under the hard outer layer.
- Bonding efficiency: How well something sticks to another thing.
- Relative humidity: How much water is in the air compared to how much it could hold at that temperature.
- Hygroscopic expansion: When something gets bigger because it absorbs water from the air.
The Impact of Relative Humidity Variation on Dental Restoration Longevity
Dental restoration is a common procedure used to repair damaged or decayed teeth. The direct dental restoration process involves drying the dentin substrate, which can cause significant strain in the dentin and affect the bonding efficiency of the restoration. To investigate the impact of relative humidity variation during dental surgery on restoration lifetime, a study was conducted to measure the dilatation of dentine under changes in relative humidity and its effect on dentin elastic properties.
Study Design
The study used an environmental chamber to control temperature and humidity on carefully prepared samples placed on a compression device, with an optical microscope to precisely measure surface strain after quantifying measurement noise.
Findings
Results showed that dentin dilates when relative humidity increases, with a coefficient of hygroscopic expansion typically at 6.10-3 % (%RH)-1, occurring within ten minutes. Young modulus and Poisson's ratio were not affected by relative humidity variation.
Conclusion
The study concluded that hygroscopic expansion is an order of magnitude larger than thermal expansion during dental surgery (around 0.3% compared to 0.03%), which may decrease the life-expectancy of a restoration despite being low levels for dental rupture. This research highlights the importance of considering relative humidity during dental procedures to ensure optimal restoration outcomes and longevity for improved patient care.
Implications for Dentists
This research has important implications for dentists performing direct restorations as it suggests that controlling relative humidity is essential in order to maximize bond strength between tooth structure and restorative material while minimizing potential damage due to thermal or hygric stress caused by rapid drying processes associated with direct restorations such as composite resin fillings or ceramic crowns/bridges/veneers etc.. Controlling RH also helps reduce shrinkage forces generated from polymerization reactions leading to better marginal integrity over time thus improving long term clinical success rates for these types of restorations . Furthermore, this research provides evidence that controlling RH can help minimize microleakage around margins leading to improved esthetics as well as reduced risk for secondary caries formation due to moisture accumulation around margins . In conclusion , controlling RH should be considered an integral part of any successful direct restorative procedure .
Background: Direct dental restoration implies a drying of the dentin substrate. This drying may induce significant strain in the dentin, affecting the bonding efficiency of the restoration. Objective: We measure the dilatation of dentine under changes of relative humidity as well as the impact of humidity on dentin elastic properties. This investigates the role of relative humidity variation during dental surgery on restoration lifetime. Methods: We have coupled an environmental chamber to control both temperature and humidity on the sample, with an optical microscope to measure precisely the strain on the sample surface, after a quantification of the measurement noise. This set-up is used on carefully prepared samples placed on a compression device to measure the elastic parameters. Results: Dentin dilates when the relative humidity increases, with a coefficient of hygroscopic expansion of typically 6.10-3 %.(%RH)-1. This dilatation occurs in about ten minutes. Young modulus and Poisson's ratio are not modified by the variation of relative humidity. Conclusions: Hygroscopic expansion is an order of magnitude larger than thermal expansion during dental surgery: around 0.3% with respect to 0.03%. These levels are low with respect to dental rupture, but may induce a significant decrease of the life-expectancy of a restoration.
