Dental Library: December 2016

Wednesday 21 December 2016

Have more than eight dental fillings? It could increase the mercury levels in your blood

Dental surface restorations composed of dental amalgam, a mixture of mercury, silver, tin and other metals, significantly contribute to prolonged mercury levels in the body, according to new research from the University of Georgia's department of environmental health science in the College of Public Health

This research, which analyzed data from nearly 15,000 individuals, is the first to demonstrate a relationship between dental fillings and mercury exposure in a nationally representative population. The results were published online last week and will be available in the print edition of the journal Ecotoxicology and Environmental Safety in December

"Tooth decay is one of the most prevalent chronic diseases," said Lei Yin, a scientist in the department of environmental health science and the study's lead author. "I think a majority of people have experienced dental fillings, but the kind of materials the dentist uses isn't something that's really discussed."

Mercury exposure from dental fillings is not a new concern, but previous studies were inconsistent and limited, according to Xiaozhong "John" Yu, assistant professor of environmental health science and co-author of the study.

"This study is trying to provide the most accurate levels of exposure, which will form the scientific basis to make future risk assessment," Yu said, adding that the study was the first to also control for age, education, ethnicity, race, gender, smoking and seafood consumption, which is a known contributor to mercury levels in the body.

The researchers further analyzed exposure by specific types of mercury and found a significant increase in methyl mercury, the most toxic form of mercury, related to dental fillings. Yu said this result suggests the human gut microbiota, a collection of microorganisms living in the intestines, may transform different types of mercury

Dental amalgam has been the go-to dental filling material for more than 150 years, because it's affordable and durable. However, about half of the compound contains mercury, a heavy metal known to be toxic at high levels, causing brain, heart, kidney, lung and immune system damage. New research suggests that methyl mercury may cause damage even at low levels

"As toxicologists, we know that mercury is poison, but it all depends on the dose. So, if you have one dental filling, maybe it's OK. But if you have more than eight dental filings, the potential risk for adverse effect is higher," Yu said. People with numerous dental fillings who are also exposed to mercury from other sources, such as seafood or work environments, are most at risk.

The results show that individuals with more than eight fillings had about 150 percent more mercury in their blood than those with none. The average American has three dental fillings, while 25 percent of the population has 11 or more fillings

According to its website, the U.S. Food and Drug Administration considers dental amalgam fillings safe for adults, but says, "pregnant women and parents with children under six who are concerned about the absence of clinical data as to long-term health outcomes should talk to their dentist.

The study also looked at dental composite resins, a mercury-free alternative for dental fillings that can release small amounts of bisphenol A, or BPA, which may cause developmental or reproductive damage. The results found no association between dental fillings and urinary BPA, but further research is needed to understand BPA exposure from resin-based materials

It's important for doctors and patients to be informed in their selections," Yin said. "We now have an excellent starting point to evaluate the potential risk of dental material on human health.

Source :Science Daily

Monday 19 December 2016

MCQs

Complete denture Prosthodontics MCQs ( 10Nos )

It's Final: FDA Bans Powdered Gloves in Surgery, Medicine

The US Food and Drug Administration (FDA) has finalized a rule banning the use of
powdered gloves in medicine because they pose dangers to human health.
The ban, first proposed in March 2016, will further propel efforts already underway
to phase out the use of prepowdered surgeons' gloves, powdered exam gloves, and
absorbable powder for lubricating surgeons' gloves. Professional societies have
advocated for a ban, and many large health systems have already either restricted
or completely ended the use of such products, as have a majority of individual
clinicians.
"While medical gloves play a significant role in protecting patients, healthcare
providers, and other individuals in close proximity, powdered gloves are very
dangerous for a variety of reasons," the FDA said in a statement.
Powder used within all types of gloves has been associated with many potentially
serious adverse events, including severe airway inflammation, hypersensitivity
reactions, allergic reactions (including asthma), lung inflammation and damage,
granulomas, and peritoneal adhesions.
Respiratory allergic reactions can also result from proteins in aerosolized glove
powder, the FDA notes.
According to the agency, nonpowdered alternatives to both surgeons' and patient
examination gloves are available that provide similar protection, dexterity, and
performance but without any of the risks associated with powdered gloves. "Thus, a
transition to alternatives in the marketplace should not result in any detriment to
public health."
Most device removals from the US market are initiated by manufacturers, not the
FDA. In fact, this is only the second time the FDA has ever done so. The first was the
removal of prosthetic hair fibers in 1983. The FDA has now proposed one other ban,
on the use of electrical stimulation devices to treat self-injurious or aggressive
behavior.
Source : Medscape

Congratulations to Hockey India Junoirs

Much awaited Victory

India beats Belgium 2-1 to Claim its Second World cup Junior Hockey title after 15yrs

The victorious Indian team after beating Belgium in the hockey junior World Cup final in Lucknow on Sunday

Indian team captain Harjeet Singh with the junior World Cup hockey trophy.

Source: HockeyIndia

Saturday 17 December 2016

Dental materials - Cements (ZnOE)

They are cements of low strength discovered in early 1860s

CLASSIFICATION

Type I ZOE: For temporary cementation
Type II ZOE: Permanent Cementation
Type III ZOE: Temporary filling and thermal base
Type IV ZOE: Cavity Liners

ZOE cement is available as

Powder and liquid System

Two – paste system

SETTING REACTION
In the First Step Hydrolysis of Zinc Oxide to its hydroxide takes place

Water is essential for the reaction (dehydrated zinc oxide will not react with dehydrated eugenol )

ZnO + H2O →Zn (OH)2

The reaction proceeds as a typical acid – base reaction

Zn (OH)2 + 2HE → ZnE2 +2H2O

(Zinc hydroxide)( Eugenol)- (Zinc eugenolate )

The Chelate formed is an amorphous gel that tends to crystallize imparting strength to the set mass

Structure of set cement:

The set cement consists of particles of zinc oxide embedded in a matrix of zinc eugenolate.

Setting time is around 4-10min.

FACTORS AFFECTING SETTING TIME

Particle size: Smaller zinc oxide particles set faster
Powder to liquid ratio: Higher the ratio, faster the set
Addition of accelerators, e.g. alcohol, glacial acetic acid and water makes the cement set faster.
Cooling the glass slab: Slows the reaction
The set can be retarded by addition of glycol and glycerine which act as retarders.

MANIPULATION

Power – Liquid System

Powder/liquid ratio: 4:1-6:1 wt%

After shaking the bottles gently, measured quantity of powder and liquid are dispensed onto a cool glass slab.

The bulk of the powder is incorporated into the liquid and saturated thoroughly in a circular motion with a stiff bladed stainless steel spatula.

Smaller increments are then added until the mix is complete.

TWO PASTE SYSTEM

Equal lengths of each paste are dispersed and mixed until a uniform colour is observed

MODIFIED ZINC OXIDE EUGENOL CEMENTS

EBA- alumina modified cements

Polymer reinforce ZOE cement

These were introduce to improve the mechanical properties of zinc oxide eugenol cement.

PROPERTIES

Compressive strength – ranges from 3 to 4 MPa up to 50-55 MPa

Tensile strength – ranges from 0.32 to 5.3MPa

Modules of elasticity – 0.22 to 5.4GPa

Thermal properties – their thermal insulating properties are excellent

Solubility and disintegration – The solubility of the set cement is highest among the cements (0.4% - wt) they disintegrate in oral fluids

Adhesion – they do not adhere well to the enamel and dentin.This is one reason why they are not often used for final cementation of crowns and bridges.

Biological properties.

PH and effect on pulp (pH is 6.6 to 8) they are the least irritating of all cements. Pulpal responses are mild.They have soothing effect on the pulp

USES

For temporary and permanent cementation

For temporary fillings

Cavity lines and basE

Pulp capping agent

Secondary use – root canal restorations

Friday 16 December 2016

MCQs - Repeats

Hello Guys, How is your Preparation?
Here is some more to refresh your knowledge ....

Actually, a picture is worth 1.5 words

Everyone knows the saying “a picture is worth a thousand words.” Bound by that axiom, magazines, newspapers, and most of all, TV, bombard us with pictures every day. The latest hot internet properties aren’t text-based sites like Google but picture-based sites like Flickr and YouTube. Psychological research backs this up: we do remember pictures more readily than we remember words.

The next question, of course, is “why?” Recent research by Paul W. Foos and Paula Goolkasian is beginning to shed light on the difference between memory for pictures and words. They had previously found that while short-term memory for simple line drawings was superior to memory for printed words, the advantage disappeared when the word was spoken. This suggests that perhaps the difference between pictures and words in memory isn’t as different as we might think.

In a new study, they set out to explore these differences more systematically. Volunteer participants were asked to complete two tasks simultaneously: they had to answer a question about a visual problem while committing a word to memory. This distractor task was designed to make the memory task more difficult, so differences in results could more readily be observed. There were two types of distractors: easy, or difficult. Here are two sample tasks:

One second after the task was displayed on a computer screen, the word they were required to remember was presented. After viewers saw six problems together with the corresponding words — either pictures, spoken, or printed — they were asked to recall as many of the words as possible. The experiment was repeated until the list of 54 words (simple nouns like “baby,” “whale,” and “handcuffs”) had each been used in picture, spoken, and print form. Here are the results:

As expected, pictures and spoken words were recalled more accurately than printed words, and the more difficult distractor task impaired memory in every case. Pictures were correctly recalled about 1.5 times as often as printed words. Thus, technically, a picture may in fact only be worth about 1.5 words.

But what about the printed words makes them more difficult to remember? Foos and Goolkasian suspected that printed words are processed too rapidly, and so don’t attract the viewer’s attention as readily as spoken words or pictures. To address this issue, in a new experiment they asked participants to say the word out loud after it was presented. This time, the results were different:

For printed words, accuracy improved significantly compared to the the first experiment. While spoken words and pictures were still recalled at a slightly better rate, the difference had shrunk considerably. Perhaps all that is needed to improve recall for printed words is to force viewers to pay more attention to them. In a final experiment, that’s precisely what Foos and Goolkasian did. Each word to be recalled was “degraded” by either adding visual distractors to the image like this:

Or, in the case of spoken words, adding a background tone to the sound recording. Again the experiment was repeated, but instead of using easy and difficult distractor tasks, the difficult task was always used. Half the time, participants had to remember degraded images and sounds, and half the time, they recalled normal images and sounds, as before. Here are the results:

As expected, fewer printed words were recalled when the words were presented normally. But when the words were degraded, the advantage of pictures and spoken words disappeared: the printed words were recalled as easily as pictures or sounds. What’s more, memory for printed words actually improved when the text was degraded, while memory for pictures and sounds worsened.

Foos and Goolkasian argue that the same mental process underlies short term memory for pictures, sounds, and printed words. The difference, it appears, lies in how we process the words when they are presented differently.

More practically, if you need to remember a word, saying it out loud will probably improve your memory. If you’re presenting words you want others to remember, pictures or spoken words are still probably your best bet — just not 1,000 times better.

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Thursday 15 December 2016

Universal Immunisation Program

What is Immunisation ?

Immunization, or Immunisation, is the process by which an individual's immune system becomes fortified against an agent (known as the immunogen)

Vaccination is the administration of antigenic material (a vaccine) to stimulate an individual's immune system to develop adaptive immunity to a pathogen. Vaccines can prevent or ameliorate morbidity from infection. When a sufficiently large percentage of a population has been vaccinated, this results in herd immunity.

Which vaccine should I give my baby?
At what age?
What if I forget?
Ok, so you probably already know that Immunization is vital for your baby...

LETS CHECK UIP Schedule 2016

If certain vaccination doses are missed or delayed due to unforeseen circumstances, a CATCH-UP VACCINATION SCHEDULE kicks into gear.First thing you need to do is consult your child paediatrician immediately.The catch-up vaccination schedule makes sure that all the vaccines are administered appropriately after taking the delayed/missed dose into account.

MCQs -General

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MCQs- Periodontics

These are Frequently asked MCQs in most of the entrance examinations...
Test your knowledge here.....
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