Tag Archives: dentistry

Diamonds in your teeth—for health reasons

Scientists at the University of California at Los Angeles (UCLA) in collaboration with their colleagues at the NanoCarbon Research Institute (Japan) are investigating the possibility of using nanodiamonds to promote bone growth that supports dental implants. From the Sept.18, 2013 news item on ScienceDaily,

UCLA researchers have discovered that diamonds on a much, much smaller scale than those used in jewelry could be used to promote bone growth and the durability of dental implants.

Nanodiamonds, which are created as byproducts of conventional mining and refining operations, are approximately four to five nanometers in diameter and are shaped like tiny soccer balls. Scientists from the UCLA School of Dentistry, the UCLA Department of Bioengineering and Northwestern University, along with collaborators at the NanoCarbon Research Institute in Japan, may have found a way to use them to improve bone growth and combat osteonecrosis, a potentially debilitating disease in which bones break down due to reduced blood flow.

The Sept. 17,2013 UCLA news release by Brianna Deane (also on EurekAlert), which originated the news item, describes how osteonecrosis affects bones and the impact that this new technique using nanodiamonds could have on applications for regenerative medicine (Note: A link has been removed),

When osteonecrosis affects the jaw, it can prevent people from eating and speaking; when it occurs near joints, it can restrict or preclude movement. Bone loss also occurs next to implants such as prosthetic joints or teeth, which leads to the implants becoming loose — or failing.
Implant failures necessitate additional procedures, which can be painful and expensive, and can jeopardize the function the patient had gained with an implant. These challenges are exacerbated when the disease occurs in the mouth, where there is a limited supply of local bone that can be used to secure the prosthetic tooth, a key consideration for both functional and aesthetic reasons.
….
During bone repair operations, which are typically costly and time-consuming, doctors insert a sponge through invasive surgery to locally administer proteins that promote bone growth, such as bone morphogenic protein.
Ho’s team discovered that using nanodiamonds to deliver these proteins has the potential to be more effective than the conventional approaches. The study found that nanodiamonds, which are invisible to the human eye, bind rapidly to both bone morphogenetic protein  and fibroblast growth factor, demonstrating that the proteins can be simultaneously delivered using one vehicle. The unique surface of the diamonds allows the proteins to be delivered more slowly, which may allow the affected area to be treated for a longer period of time. Furthermore, the nanodiamonds can be administered non-invasively, such as by an injection or an oral rinse.
“We’ve conducted several comprehensive studies, in both cells and animal models, looking at the safety of the nanodiamond particles,” said Laura Moore, the first author of the study and an M.D.-Ph.D. student at Northwestern University under the mentorship of Dr. Ho. “Initial studies indicate that they are well tolerated, which further increases their potential in dental and bone repair applications.”
“Nanodiamonds are versatile platforms,” said Ho, who is also professor of bioengineering and a member of the Jonsson Comprehensive Cancer Center and the California NanoSystems Institute. “Because they are useful for delivering such a broad range of therapies, nanodiamonds have the potential to impact several other facets of oral, maxillofacial and orthopedic surgery, as well as regenerative medicine.”
Ho’s team previously showed that nanodiamonds in preclinical models were effective at treating multiple forms of cancer. Because osteonecrosis can be a side effect of chemotherapy, the group decided to examine whether nanodiamonds might help treat the bone loss as well. Results from the new study could open the door for this versatile material to be used to address multiple challenges in drug delivery, regenerative medicine and other fields.

Here’s a citation for and a link to the researchers’ published paper,

Multi-protein Delivery by Nanodiamonds Promotes Bone Formation by L. Moore, M. Gatica, H. Kim, E. Osawa, & D. Ho. Published online before print September 17, 2013, doi: 10.1177/0022034513504952 JDR September 17, 2013 0022034513504952

This paper is behind a paywall.

Dental fillings that improve your teeth

If you have lousy teeth, this is exciting news. From the May 2, 2012 news item on Nanowerk (I have removed a link),

Scientists using nanotechology at the University of Maryland School of Dentistry have created the first cavity-filling composite that kills harmful bacteria and regenerates tooth structure lost to bacterial decay. [emphasis mine]

Rather than just limiting decay with conventional fillings, the new composite is a revolutionary dental weapon to control harmful bacteria, which co-exist in the natural colony of microorganisms in the mouth, says professor Huakun (Hockin) Xu, PhD, MS. [emphasis mine]

While the possibilities are promising, I find the idea of a weapon in my mouth disconcerting. (They might want to check out their metaphors a little more closely.) Moving on, there’s a little more detail about this new composite  (from the news item),

Fillings made from the School of Dentistry’s new nanocomposite, with antibacterial primer and antibacterial adhesive, should last longer than the typical five to 10 years, though the scientists have not thoroughly tested longevity. Xu says a key component of the new nanocomposite and nano-structured adhesive is calcium phosphate nanoparticles that regenerate tooth minerals. The antibacterial component has a base of quaternary ammonium and silver nanoparticles along with a high pH. The alkaline pH limits acid production by tooth bacteria.

“The bottom line is we are continuing to improve these materials and making them stronger in their antibacterial and remineralizing capacities as well as increasing their longevity,” Xu says.

The new products have been laboratory tested using biofilms from saliva of volunteers. The Xu team is planning to next test its products in animal teeth and in human volunteers in collaboration with the Federal University of Ceara in Brazil.

The folks at the enewsparkforest blog are not quite so sanguine about this dental development as per their May 3, 2012 posting on the topic (I have removed llinks),

A study conducted in 2008 and confirmed by another study in 2009 shows that washing nano-silver textiles releases substantial amounts of the nanosilver into the laundry discharge water, which will ultimately reach natural waterways and potentially poison fish and other aquatic organisms. A study found nanosilver to cause malformations and to be lethal to small fish at various stages of development since they are able to cross the egg membranes and move into the fish embryos. A 2010 study by scientists at Oregon State University and in the European Union highlights the major regulatory and educational issues that they believe should be considered before nanoparticles are used in pesticides.

As Dexter Johnson in his May 3, 2012 posting on his Nanoclast blog (on the Institute for Electrical and Electronics Engineers website) notes,

The researchers are continuing with their animal and human testing with the nanocomposite. Given that some sectors of the public are concerned about the potential risks of silver nanoparticles, they should probably take a look at the issue as part of their research.

This is not unreasonable especially in light of the concern some folks have had over mercury in dental fillings. Sufficient concern by the way to occasion this cautionary note from Health Canada (from the Mercury and Human Health webpage on their website),

Minimizing Your Risk

Elemental mercury from dental fillings does not generally pose a health risk. There is, however, a fairly small number of people who are hypersensitive to mercury. While Health Canada does not recommend that you replace existing mercury dental fillings, it does suggest that when the fillings need to be repaired, you may want to consider using a product that does not contain mercury.

Pregnant women, people allergic to mercury and those with impaired kidney function should avoid mercury fillings. Whenever possible, amalgam fillings should not be removed when you are pregnant because the removal may expose you to mercury vapour. When appropriate, the primary teeth of children should be filled with non-mercury materials.

Side note: I find it interesting that while Health Canada has not banned the use of mercury in fillings, it does advise against adding more mercury-laced fillings to your mouth and/or using them in your children’s primary teeth, if possible.

Getting back to silver nanoparticles in our mouths, I reiterate Dexter’s suggestion.

Printing bones

Apparently all you need is an inkjet printer and some researchers from Washington State University (WSU) at Pullman to create new bone. From the Nov. 29, 2011 news item (written by Eric Sorenson of WSU) on Nanowerk,

Washington State University researchers have used a 3D printer to create a bone-like material and structure that can be used in orthopedic procedures, dental work and to deliver medicine for treating osteoporosis. Paired with actual bone, it acts as a scaffold for new bone to grow on and ultimately dissolves with no apparent ill effects. [emphasis mine]

The authors report on successful in vitro tests in the journal Dental Materials (“Effects of silica and zinc oxide doping on mechanical and biological properties of 3D printed tricalcium phosphate tissue engineering scaffolds” [behind a paywall]) and say they’re already seeing promising results with in vivo tests on rats and rabbits. It’s possible that doctors will be able to custom order replacement bone tissue in a few years, said Susmita Bose, co-author and professor in WSU’s School of Mechanical and Materials Engineering.

The printer works by having an inkjet spray a plastic binder over a bed of powder in layers of 20 microns, about half the width of a human hair. Following a computer’s directions, it creates a channeled cylinder the size of a pencil eraser.

After just a week in a medium with immature human bone cells, the scaffold was supporting a network of new bone cells.

Here’s a video of Dr. Bose discussing the inkjet printer that produces bone-like material,

The Nov. 30, 2011 news item about the bone scaffolding work on BBC News adds more detail,

Prof Bose’s team have spent four years developing the bone-like substance.

Their breakthrough came when they discovered a way to double the strength of the main ceramic powder – calcium phosphate – by adding silica and zinc oxide.

To create the scaffold shapes they customised a printer which had originally been designed to make three-dimensional metal objects.

It sprayed a plastic binder over the loose powder in layers half as thick as the width of a human hair.

The process was repeated layer by layer until completed, at which point the scaffold was dried, cleaned and then baked for two hours at 1250C (2282F).

Earlier this year I highlighted a story about a trachea transplant where they used scaffolding to grow trachea cells in much the same way the WSU team is using a scaffolding to grow bone cells. Here are the posts about the trachea transplant and scaffolding from the first to the last,

Body parts nano style

Making nanotechnology-enabled body parts

More on synthetic windpipe; Swedes and Italians talk about nanoscience and medicine

Nano dental technique promises a world without root canals

Unfortunately, it’s not here yet but according to a news item on Nanowerk,

Scientists are reporting an advance toward the next big treatment revolution in dentistry — the era in which root canal therapy brings diseased teeth back to life, rather than leaving a “non-vital” or dead tooth in the mouth. In a report in the monthly journal ACS Nano, they describe a first-of-its-kind, nano-sized dental film that shows early promise for achieving this long-sought goal (“Nanostructured Assemblies for Dental Application”).

I gather from further reading into the news item that we’re a long way from clinical trials (drat!),

The scientists are reporting development of a multilayered, nano-sized film — only 1/50,000th the thickness of a human hair containing a substance that could help regenerate dental pulp. Previous studies show that the substance, called alpha melanocyte stimulating hormone, or alpha-MSH, has anti-inflammatory properties. The scientists showed in laboratory tests alpha-MSH combined with a widely-used polymer produced a material that fights inflammation in dental pulp fibroblasts. Fibroblasts are the main type of cell found in dental pulp. Nano-films containing alpha-MSH also increased the number of these cells. This could help revitalize damaged teeth and reduce the need for a root canal procedure, the scientists suggest.

Sometimes I just like to focus on the benefits that nanotechnology offers and this would be a major benefit for a lot of people around the world.