The Afternoon Drill: July 18, 2011

A collection of dentistry and health related links/comments for your day.

Print Your Own Teeth: Rapid Prototyping Comes to Dentistry

What if, instead of waiting days or weeks for a cast to be produced and prosthetic dental implants, false teeth and replacement crowns to be made, your dentist could quickly scan your jaw and "print" your new teeth using a rapid prototyping machine known as a 3D printer?

Researchers in Iran explain how medical imaging coupled with computer-aided design could be used to create a perfect-fit blueprint for prosthetic dentistry, whether to replace diseased or broken teeth and jaw bone. The blueprint can then be fed into a so-called 3D printer to build up an exact replica using a biocompatible composite material. Such technology has been used in medical prosthetics before, but this is an early step into prosthetic dentistry using rapid prototyping.

Writing in the International Journal of Rapid Manufacturing, mechanical engineer Hossein Kheirollahi of the Imam Hossein University and colleague Farid Abbaszadeh of the Islamic Azad University, in Tehran, Iran, explain how current technology used to convert an MRI or CT scan into a prosthetic component requires milling technology. This carves out the appropriate solid shape from a block of polymer but has several disadvantages, uppermost being that it is very difficult to carve out a complex shape, such as a tooth. By contrast, rapid prototyping uses a 3D image held in a computer to control a laser that then "cures" powdered or liquid polymer. Almost any solid, porous, or complicated shape can be produced by this 3D-printing technology.

Injectable Polymer Gel Mimics Properties of Human Vocal Cords

Henry Wadsworth Longfellow said that “The human voice is the organ of the soul”. That could explain why we’re always saddened to hear when prominent speakers, such as singer Julie Andrews or film critic Roger Ebert, lose their well-heard voices due to a disease or injury. It’s estimated that 6 percent of the U.S. population has some kind of voice disorder, often due to scarring or straining from disease or overuse.

At Harvard and MIT, researchers have been developing a new type of synthetic polymer that mimics the viscoelastic properties of human vocal cords. The polymer, PEG30, which is a modified form of polyethylene glycol (PEG), was shown to vibrate with a similar frequency to human vocal cords when air was blown through a vocal-fold model made of the polymer. Moreover, the polymer was shown to restore vibration to vocal folds that have become stiff and unable to vibrate due to scarring.

PEG has been shown to be safe in many FDA-approved drugs and medical devices, so researchers are hoping to use the modified polymer as an “injectable device” that is applied directly into the vocal folds every six months.

Pediatrician feels heat over child obesity idea

Boston pediatrician David Ludwig, the center of a media firestorm this week, wants to set the record straight on his view that a state should intervene in the most extreme cases of child obesity.

Ludwig and co-author Lindsey Murtagh at the Harvard School of Public Health triggered a backlash with an opinion piece in a leading U.S. medical journal about what could be done about highly overweight youngsters.

They argued that when all other efforts failed, a state should consider putting high-risk obese kids in foster care, and said doing so may be the more ethical choice that could avert drastic measures like weight-loss surgery.

Ludwig, of Boston's Children's Hospital, has since responded to dozens of e-mails this week from angry and terrified parents. Other medical experts have questioned the rationale of removing a child from an otherwise functional and supportive family if they are obese.

Falls Could Signal Early Alzheimer's Disease

Compared with older people with no signs of Alzheimer's, those whose brains show early signs of the disease are twice as likely to experience a fall, researchers have found.

In the new study, investigators looked at brain scans of 125 older adults who were participating in a study of memory and aging. The seniors were also asked to keep track of how many times they fell over the course of eight months.

An increased risk of falls was noted among individuals whose scans showed early signs of Alzheimer's. The study authors suggested that falls could indicate the need for an evaluation for the memory-robbing disease.

"To our knowledge, this is the first study to identify a risk of increased falls related to a diagnosis of preclinical Alzheimer's disease," study author Susan Stark, an assistant professor of occupational therapy and neurology at Washington University in St. Louis, said in a news release from the Alzheimer's Association International Conference.

"This finding is consistent with previous studies of mobility problems among persons with very early symptomatic Alzheimer's or mild cognitive impairment. It suggests that higher rates of falls can occur very early in the disease process," Stark added.

The study, which was slated for presentation Sunday at the Alzheimer's Association International Conference in Paris, found that of the 125 adults studied, 48 people experienced at least one fall.

The brain scans of the participants showed that higher levels of an imaging agent that binds to the abnormal protein growth that is a signature of Alzheimer's disease, was associated with a 2.7 times higher risk of a fall for each unit of increase on the scan.

Enjoy your day!