December 2011, Volume 7, Issue 11
Published by AEGIS Communications
Study Describes How Enamel Forms
AUGUST—Researchers at the University of Pittsburgh School of Dental Medicine are piecing together the process of tooth enamel biomineralization, which could lead to novel nanoscale approaches to developing biomaterials. The findings are reported online in the Proceedings of the National Academy of Sciences.
“Enamel starts out as an organic gel that has tiny mineral crystals suspended in it,” said Elia Beniash, PhD, associate professor of oral biology, Pitt School of Dental Medicine. “We recreated the early steps of enamel formation so that we could better understand the role of a key regulatory protein called amelogenin in this process.”
Dr. Beniash and his team found that amelogenin molecules self-assemble in stepwise fashion via small oligomeric building blocks into higher-order structures. Just like connecting a series of dots, amelogenin assemblies stabilize tiny particles of calcium phosphate, which is the main mineral phase in enamel and bone, and organize them into parallel arrays. Once arranged, the nanoparticles fuse and crystallize to build the highly mineralized enamel structure.
“The relationship isn’t clear to us yet, but it seems that amelogenin’s ability to self-assemble is critical to its role in guiding the dots, called prenucleation clusters, into this complex, highly organized structure,” Dr. Beniash said. “This gives us insight into ways that we might use biologic molecules to help us build nanoscale minerals into novel materials, which is important for restorative dentistry and many other technologies.”
Source: University of Pittsburgh Schools of the Health Sciences
Cavity-Causing Microbes Can Invade the Heart
JUNE—Scientists have discovered the tool that bacteria normally found in our mouths use to invade heart tissue, causing a dangerous and sometimes lethal infection of the heart known as endocarditis. The work raises the possibility of creating a screening tool—perhaps a swab of the cheek, or a spit test—to gauge a dental patient’s vulnerability to the condition.
The identification of the protein that allows Streptococcus mutans to gain a foothold in heart tissue is reported in the June issue of Infection and Immunity by microbiologists at the University of Rochester Medical Center.
Normally, S. mutans confines its mischief to the mouth, but sometimes, particularly after a dental procedure or even after a vigorous bout of flossing, the bacteria enter the bloodstream. There, the immune system usually destroys them, but occasionally—within just a few seconds—they travel to the heart and colonize its tissue, especially heart valves. The bacteria can cause endocarditis—inflammation of heart valves—which can be deadly. Infection by S. mutans is a leading cause of the condition. Jacqueline Abranches, PhD, a microbiologist and the corresponding author of the study, and her team at the University’s Center for Oral Biology discovered that a collagen-binding protein known as CNM gives S. mutans its ability to invade heart tissue. In laboratory experiments, the scientists found that strains with CNM are able to invade heart cells, and strains without CNM are not.
When the team knocked out the gene for CNM in strains where it is normally present, the bacteria were unable to invade heart tissue. Without CNM, the bacteria simply could not gain a foothold; their ability to adhere was about one tenth of what it was with CNM.
The work may someday enable doctors to prevent S. mutans from invading heart tissue. Even sooner, though, since some strains of S. mutans have CNM and others do not, the research may enable doctors to gauge a patient’s vulnerability to a heart infection caused by the bacteria.
Source: University of Rochester Medical Center
Dentists Can Identify People with Undiagnosed Diabetes
JULY—In a study published in the July 2011 issue of the Journal of Dental Research, researchers at Columbia University College of Dental Medicine found that dental visits represented a chance to intervene in the diabetes epidemic by identifying individuals with diabetes or pre-diabetes who are unaware of their condition. The study sought to develop and evaluate an identification protocol for high blood sugar levels in dental patients and was supported by a research grant from Colgate-Palmolive. The authors report no potential financial or other conflicts.
“Periodontal disease is an early complication of diabetes, and about 70% of U.S. adults see a dentist at least once a year,” says Dr. Ira Lamster, dean of the College of Dental Medicine, and senior author on the paper. “Prior research focused on identification strategies relevant to medical settings. Oral healthcare settings have not been evaluated before, nor have the contributions of oral findings ever been tested prospectively.”
For this study, researchers recruited approximately 600 individuals visiting a dental clinic in Northern Manhattan who were 40-years-old or older (if non-Hispanic white) and 30-years-old or older (if Hispanic or non-white), and had never been told they have diabetes or pre-diabetes.
Approximately 530 patients with at least one additional self-reported diabetes risk factor (family history of diabetes, high cholesterol, hypertension, or overweight/obesity) received a periodontal examination and a fingerstick, point-of-care hemoglobin A1c test. In order for the investigators to assess and compare the performance of several potential identification protocols, patients returned for a fasting plasma glucose test, which indicates whether an individual has diabetes or pre-diabetes.
Researchers found that, in this at-risk dental population, a simple algorithm composed of only two dental parameters (number of missing teeth and percentage of deep periodontal pockets) was effective in identifying patients with unrecognized pre-diabetes or diabetes. The addition of the point-of-care A1c test was of significant value, further improving the performance of this algorithm.
Source: Columbia University Medical Center