X-ray Microscope Designed To Study Jet Engine Components Now Probes Tooth Dentin

March 17, 1998

Using an x-ray microscope developed at Lawrence Livermore National Laboratory for the Department of Energy, researchers at the UC San Francisco School of Dentistry are probing the intricate structure of dentin, the porous material that lies under the hard enamel of teeth.

An x-ray tomographic microscope (XTM), invented by a Lawrence Livermore scientist to analyze ceramic components used in jet engines, allows the dental researchers to observe structures in the dentin as small as two micrometers -- about the size of a human cell.

Atomic force microscopy (AFM), another technology used at UCSF and Lawrence Livermore, provides an even closer view. Researchers test the strength and stiffness of dentin by pushing the very atoms and molecules apart and using the device to observe how they respond.

Researchers want to understand the structure and properties of dentin in order to find methods and materials that will create a tighter, more permanent bond between the tooth and the plastic-based fillings now used to repair most cavities.

Metal alloys create a more durable restoration than newer plastic-based and ceramic materials used for filling tooth cavities, but the ability to match the color of these materials to the natural color of a tooth makes the newer materials much more popular choices.

"We want to make the polymer (plastic-based) and ceramic materials as strong and long-lasting as metal," explains Sally J. Marshall, PhD, UCSF professor of restorative dentistry. She and Grayson W. Marshall Jr., DDS, MPH, PhD, UCSF professor of restorative dentistry, led the UCSF research team working with John H. Kinney, PhD, senior research scientist at Lawrence Livermore National Laboratory.

The team of researchers recently reported on the progress of their study at the annual scientific meeting of the American Association for Dental Research. The study is funded by a grant from the National Institute for Dental Research. In the first stage of the study, the researchers examined the way dentin is structured and how a bond forms between the natural material of the tooth and the plastic filling.

Strong bonds form easily between restorative materials and the surface enamel of teeth because about 97 percent of the hard surface material is mineral. But because tooth decay eats through the enamel and into the underlying layer of the tooth, a bond must be formed with the dentin.

Because dentin contains a great deal of moisture and organic tissue -- only about 50 percent of dentin is mineral -- bonds are more difficult to form. By using the powerful microscopes to observe the bonding process, the UCSF researchers now can offer a better explanation of the reasons bonds succeed and fail.

When dentists prepare a tooth for bonding a filling, they use an acid to demineralize the surface of the cavity. This process removes the mineral material from the dentin, leaving a framework of collagen tissue and tiny tubules that run from the center of the tooth toward the surface.

When a plastic-based filling is placed in the cavity it is in a liquid form, allowing the material to penetrate the exposed framework before hardening. The UCSF researchers study how quickly and efficiently different acids work in the demineralization process and how various materials used to form bonds withstand the constant stress placed on teeth.

AFM is unique in its ability to provide a high resolution image in any environment, including wet or acid solutions. As a result, the UCSF researchers were the among the first to describe why the polymer bonding process works best when the dentin remains moist. In the bonding process the liquid filling penetrates moist dentin more easily than drier dentin -- much as a moist sponge more quickly absorbs water than a dried sponge, Sally Marshall explains.

In the next stage of the study, the research team is examining how tooth decay progresses differently in different areas of dentin and how age affects the process of tooth disease.
-end-


University of California - San Francisco

Related Dental Research Articles from Brightsurf:

Journal of Dental Research special issue explores a new era for the oral microbiome
The June 2020 issue of Journal of Dental Research brings together a collection of the latest research on the oral microbiome.

Journal of Dental Research study: Fluoridation is not associated with increase in osteosarcoma
The Journal of Dental Research published today the results of a study that demonstrated that community water fluoridation is not associated with increased risk of osteosarcoma.

IADR's Women Pioneers: Celebrating a Century of Achievement published in Advances in Dental Research
The latest issue of Advances in Dental Research, an e-Supplement to the Journal of Dental Research (JDR), 'IADR's Women Pioneers: Celebrating a Century of Achievement' highlights the history of the tremendous advancements in dental research made by women, while also identifying areas where the profession needs to continue to grow to be more inclusive in the promotion of women scientific innovators.

Advances in precision oral health research proceedings published in Advances in Dental Research
On November 8-9, 2018 the American Association for Dental Research (AADR) held the '9th AADR Fall Focused Symposium: Advances in Precision Oral Health Research' meeting on the National Institutes of Health (NIH) campus in Bethesda, Maryland, USA.

Details of dental wear revealed
The teeth of mammals experience constant wear. However, the details of these wear processes are largely unknown.

journal of Dental Research centennial featured article: Tooth bioengineering and regene
Over the past 100 years, tremendous progress has been made in the fields of dental tissue engineering and regenerative dental medicine.

Journal of Dental Research Centennial July 2019: Fluoride Revolution and Dental Caries
While the global epidemic of dental caries that began about 140 years ago was very largely caused by the rise in sugar consumption, the more recent decline in caries during the last 50 years has been due largely to the use of fluoride.

Dental fillings could last twice as long
A compound used to make car bumpers strong and protect wood decks could prevent return visits to the dentist's office.

Irish Famine victims' heavy smoking led to dental decay, new research reveals
Irish Famine victims were heavy smokers which caused badly rotten teeth, researchers from the University of Otago and Queen's University Belfast, in Ireland, have discovered.

Dental research shows that smoking weakens immune systems
Researchers at the Case Western Reserve University School of Dental Medicine found that smoking weakens the ability for pulp in teeth to fight illness and disease.

Read More: Dental Research News and Dental Research Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.