Showing posts with label Dentist. Show all posts
Showing posts with label Dentist. Show all posts

Wednesday, 18 December 2013

My current rant topic: E Cigarettes

Even the writing of the above “product” as a title offends me. For those who have managed to bypass the tsunami of people walking the streets/sitting on public transport/your favourite restaurant with what looks like a tiny musical flute sticking out of their mouth, e cigarettes are the new “cool” way to smoke.
They are advertised as being the best thing you can do for your health and from the sheer volume of marketing bumph surrounding them you would think they were some sort of miracle that purified even the finest mountain air.

In this blog post I will therefore attempt to work out
1)      What the hell they are
2)      What the hell is in them
3)      Why the hell people think it is acceptable to use them like a lollipop


The premise of the e cigarette is that it is supposedly a healthier alternative to regular cigarettes because they do not contain tobacco. This sounds all well and good as we know the damage that tobacco can cause – in particular reference to my area of “expertise” it can lead to a whole range of oral cancers which can involve not just the areas of your mouth visible when you yawn but a whole realm of other areas in the head and neck. Most brands of this device also claim that they do not contain tar. Another benefit of course unless of course you wish for your lungs to look like the surface of the M6.
They were primarily designed as an addition to the realms of nicotine replacement therapy (NRT) alongside patches, gum, medication like Champix etc and therefore used to cut down smoking.
All of this sounds very positive, so much so that one lady who switched to using a certain brand of the e cigarette to write the poem below:

No more cigarettes for me
What could I do, I liked the taste
Went to e-cigarette with much haste
Cigarettes without the bad bits
Made it easy to kick the habit
They come in lots of different flavours
For me to try and quickly savour
The prices are great
Delivery is never late
So give Smokers Angel a go
And try their range of Halo

Now that is quite a gushing testimonial. Similarly, the woman below appears extremely pleased with her e cigarette. It has even managed to get her a gentleman willing to photobomb her holiday snaps.  What could possibly be so bad.

 



On that note, let’s see if we can find any information at all about what is in them. Now trust me, I spent a good few hours trying to research this and the only thing I consistently came across was marketing BS. So I turned to the BMA (as I so often do)

What are they?

“E-cigarettes are battery-powered products designed to replicate smoking behaviour without the use of tobacco – some look like conventional cigarettes, while others appear more like an electronic device”  They consist of a cartridge containing liquid nicotine, an atomiser (heating element), a rechargeable battery, and electronics.

E-cigarettes have been marketed as cheap and healthier alternatives to cigarettes as well as to look and feel like cigarettes for use in places where smoking is not permitted since they do not produce  smoke. E-cigarettes are products operated by a single use or rechargeable battery that heats a liquid based solution (often containing nicotine) into a vapour. This is then inhaled by the user, simulating the effect of cigarette smoking.

They are primarily used (apparently) as a means to quit smoking and therefore the major studies conducted on e-cigarettes have analysed nicotine content, as addiction to this apparently why people cannot quit smoking. “An analysis of the total level of nicotine generated by e-cigarettes which vaporise nicotine effectively found that the amount inhaled from 15 puffs was lower compared with smoking a conventional cigarette”. Please note the extremely vague wording used by the usually extremely un-vague British Medical Association. Another study analysed sixteen e-cigarette brands and found the total level of nicotine in vapour generated by 20 series of 15 puffs varied from 0.5 to 15.4 mg. Again, there is no regulation, nor any standard or reproducible results that can be produced from e cigarette testing.

In 2009, the United States Food and Drug Administration (FDA) released results of an analysis of some e-cigarette product, it showed that the tested e-cigarette cartridges contained carcinogens and toxic chemicals. Analysis of two leading brands by the FDA also revealed:
  • diethylene glycol (a toxic chemical) in one cartridge at approximately 1%
  • tobacco-specific nitrosamines (which are human carcinogens) in half of the samples
  •  tobacco-specific impurities suspected of being harmful to humans (anabasine, myosmine, and ßnicotyrine) in a majority of the samples


The tests also suggested that quality control was inconsistent or non-existent:

  • cartridges with the same label emitted a markedly different amount of nicotine with each puff
  • one high-nicotine cartridge delivered twice the amount of nicotine compared to a nicotine inhalation product approved by the FDA.

 i.e. the biggest food and drug regulatory body in the world cannot conclusively say that is in the products or what they give out.

See next subheading.

E cigarettes – the new enemy?

Whilst I absolutely cannot deny that any improvement on smoking normal cigarettes is beneficial to health in general and therefore oral health, e cigarettes are a dangerous realm to enter into.
The reason they are cheaper is because they are not taxed in the same way as regular cigarettes. Hurray, I hear you shout. Sadly, these taxes pay my wages in the NHS, they also put people off smoking because it makes it so darn expensive. Without this deterent what is to stop people continuing to pump dangerous chemicals into their bodies. Similarly, they are not regulated in the same way as normal cigarettes. For cigarettes to be sold they have to go through rigorous quality control, the same does not apply for e cigarettes. Due to this, we have absolutely no clue what is in them.
All that can be said is that they are not licensed as a medicine in the UK, and there is no peer-reviewed evidence that they are safe or effective for the purpose of helping to cut down smoking, as a “healthier” alternative to smoking or in fact any other reason except making you look like you’re smoking a marker pen.

The World Health Organisation document (which is 50 pages long I might add); WHO STUDY GROUP ON TOBACCO PRODUCT REGULATION raises further concern about the use of these products as nicotine replacement therapy. “Delivery of nicotine to the lung raises concern about safety and addiction that go beyond that related to currently approved NRT, concern…is associated with the probable exposure of the lung to repeated dosing, perhaps hundreds of times a day for many months, if these products are used as a smoking cessation aid, or for years, for smokers who use them as long-term cigarette substitutes”. That is to say, the delivery of nicotine directly to the lungs has never before been studied, and whilst manufacturers get away with using certain chemicals in e-cigarettes because they approved for human consumption, we have no idea of the effect they have when inhaled.

Most people who purchase and use e-cigarettes claim they do so as a means to cut down on smoking i.e. smoking cessation, instead of things like patches, gum and so on. Sadly, the World Health Organisation(WHO) who govern most of what we do in terms of medication, health choices, prevention etc state that “as of July 2013, the efficacy in using electronic cigarettes to aid in smoking cessation has not been demonstrated scientifically”. They tend to err on the side of caution as they are such a huge body of people of differing backgrounds and motivations that having a strong unified opinion on something is a difficult task. However, so unified was their opinion in this case that they recommend "consumers should be strongly advised not to use" electronic cigarettes until a reputable national regulatory body has found them safe and effective”. Nuff said.

The British Medical Association have also been forced to offer up an opinion on the damn things and their summary is not much more positive than the WHO. They state that “four out of five e-cigarette users continue smoking, and use e-cigarettes primarily as a substitute where smoking is not allowed” thus completely defeating the object of switching to e-cigarettes for a smoking cessation purpose. Again, the BMA agree, expressing their concern that e-cigarettes may undermine smoking prevention and cessation, as their use is likely to reinforce the normalcy of the smoking behaviour”.
This normalcy was nicely illustrated just last week when I walked past a patient sitting IN THE DENTAL HOSPITAL WAITING ROOM smoking one of these devices, regarding me with confusion at my anger with her behaviour. Similarly, the fact that the e cigarettes are generally quite aesthetically pleasing and gadgetty-looking means that people are far more likely to openly smoke them, and thus consume more nicotine than they would should they smoke their normal cigarettes, thus negating the intended purpose of switching.

Our Australian cousins also echo this. “Other unintended consequences of e-cigarette use include the potential to induce nicotine addiction in non- smokers or maintain addiction in current smokers who might otherwise quit. Furthermore, concerns have been raised that e-cigarettes may undermine the comprehensive indoor  smoking restrictions and smokefree air policies” and making it generally acceptable for people to be seen smoking after years of hard work aiming to make them feel as embarrassed about smoking in public as public urination – people still do it but its few and far between, although maybe I grace the wrong areas of town at the wrong time of night.

The National Institute for Health Care and Excellence (NICE) recently published new public health guidance backing the use of licensed nicotine products to help people cut down as well as stop smoking. However, these guidelines did not cover e-cigarettes. Again, without having to say it, I imagine several suited men sitting round a table and laughing at the concept of e-cigarettes even being considered in this category of something that they would advise or recommend as something of health benefit.

Now of course, I cannot complete an analysis of the use of this product without referring to the superpowers of the USA – namely the Food and Drug Administration department (FDA). They basically regulate everything that is consumed, injected or applied by our friend across the pond and thus you could argue, have probably become fairly used to seeing products come and go, and are unlikely to have any emotional response related to items they are asked to assess. So strongly therefore did the FDA feel about e cigarettes that way back in 2010 long before the e cigarette phenomenon reached our shores, they issued warning letters to a grand total of 5 electronic cigarette distributors for various violations of the Federal Food, Drug, and Cosmetic Act (FDCA) including unsubstantiated claims and poor manufacturing practices. What is more worrying is that the FDA only regulates products intended for therapeutic use i.e. as a nicotine replacement therapy, and therefore, if a company decides to purely register their e cigarette product as recreational, or a hobby based item, then it completely negates all regulation by any drug agencies. Still fancy puffing away on one of them?

Dental Impact

What most people don’t consider is the effect that smoking has on their mouth. Whilst smoking e cigarettes should technically reduce risk of oral cancer, the presence of carcinogens in most of the leading brand’s e cigarettes negates this benefit. Similarly, the main causative factor of smoking related gum disease is nicotine. As the e cigarettes are rammed with the stuff, they offer no benefit in terms of “the leading cause of tooth loss” (thanks Corsodyl). That is to say, puffing away on your e-cigarette is just as harmful to your gums as smoking regular cigarettes and so your path on the road to dentures is just as speedy. In fact the WHO state that 90% of the nicotine that people smoking e-cigarettes are so desperate to get into their lungs, is actually deposited in the mouth.

In Summary.

The Medicines and Healthcare Products Regulatory Agency in the United Kingdom reported that it planned to regulate e-cigarettes as medicines from 2016 when new European tobacco laws come into force so until then, it remains that we have no idea what e-cigarettes are. In my mind, used as a nicotine replacement therapy, i.e. to smoke less and less over a set period until smoking has been stopped, completely, is fine, so long as they smoke it miles away from me, not around children, and that the whole thing stops being glamorised.

What I trawled through in order to write this blog:

BMA, E-cigarettes in public places and workplaces A briefing from the BMA Occupational Medicine Committee and the Board of Science, March 2012
BMA calls for stronger regulation of e-cigarettes
March 2012 (updated January 2013) A briefing from the Board of Science and the Occupational Medicine Committee

Monday, 7 October 2013

Root canal treatment. Run for cover or run to the dentist?

Today's topic to be tackled is the touchy subject of root canal treatment. 

It seems to be that whenever the notion of this is mentioned to a patient they turn pale, clammy, and leave me reaching for the medical emergency drug kit. Sadly I believe along with smear tests, the MMR vaccine and Marmite, this tooth-saving therapy has been the victim of many misconceptions and media scare mongering. 

Most often I am met with "but that hurts doesn’t it?" "my cousin/friend/that woman off of *insert American sitcom here* had one of those done and they didn't get out of bed for a year" and whilst anything that requires prolonged and/or regular contact with one of us tooth workers is never the top of anyone's bucket list, it is very far removed from the nightmare people make it out to be. 

The technical bit

Again with a little help from my friends at nhs.uk a handy definition goes a little like this....."Root canal treatment is a dental procedure to treat infection at the centre of a tooth (the root canal system). Root canal treatment is also called endodontics". Professionals in the field of root canal treatments are therefore called endodontists and there may be certain situations where you need to see one of these. 

Why you need it:

Below is an x ray of some teeth (taken from www.dentistryunited.com). Just as a side note, us tooth workers refer to x ray pictures as "radiographs" so when you hear us bandying this around thinking we sound fancy, now you can nod along. 


I have added some very technical labels as you can see. 

For some reason - usually due to decay, leaking around fillings over time or due to shoddy dental work - the nerve of your tooth becomes inflamed and infected. (You may hear the nerve being referred to by us dental folk as "the pulp")

Please note: This is just one of many scenarios that lead to the need for root canal. You may also require it for things like trauma - falling off your bike, drunken brawls etc - but the basic principles of why root canal is necessary remain the same. 

At this point you may experience some sensitivity. In some cases people experience no symptoms at all but 99% of the time the story goes something like this:

 "I was in agony for a week but then it went away so I thought it was fine"

It will never be fine. There is a reason it hurt. The reason is that your nerve is dying off. 

During the nerve's demise, a tonne of bacteria and toxic chemicals from the necrotic (fancy word for dead/dying/rotten) nerve leak out the end of the tooth and start to eat away at the bone. This causes a dark area at the end of the root on an x ray (see above) and is often what leads to an abscess, or at least it has the potential to become an abscess. 

If this area of infection is left for a period of time, you may experience a lump on the gum, which feels like a blister or a gum boil, or simply a swelling of the face. This is because the infection is trapped within the bone of the jaw and has nowhere to release itself so it causes swelling. A bit like filling a balloon with water, or a really painful spot that hasn't developed that nice white head yet. 

At this stage, when the nerve has died completely, nothing except root canal work or taking the tooth out (extraction) will solve the problem. 

Yes that's right - antibiotics will not cure the problem. They help settle the infection so we can tackle it more effectively but they will not remove the cause. No. Not even bucket loads of the things will make a difference long term.

I can also advise at this point that there is almost a 100% guarantee that the time you will realise this fact is when your face balloons up (a little akin to when the Nutty Professor's magic potion wears off and he turns from Buddy Love to Sherman Klump) on Christmas Eve/New Years Eve/before you go on holiday. Sadly at these times myself, my colleagues and our non-oversized features will be eating/drinking/sunning ourselves/laughing about that person WHO THOUGHT THEY COULD GET AWAY WITH JUST ANTIBIOTICS.

The actual (post rant) technical bit.

The root canal/canal/where the nerve lies in the tooth is where we have to get to in order to do a root canal filling. The basic principles for a successful (in the eyes of our superiors who write guidelines) root treatment is to:

1.
Remove all the infected/dead nerve and bacteria from within the tooth. This is aided using certain disinfecting chemicals. For this reason, during treatment you will have to wear one of these:



Apologies for the morbid expression on this gentleman's face, I imagine inside he is feeling pure joy. 

The green sheet/frame/silver clamp around his teeth is referred to as a "rubber dam" (referred to by my Dad for several months as "a Ramadan" - yes the famous Islamic period of fasting - because apparently "that's what it sounded like when the dentist explained it")

Wearing this device means that your mucky bacteria-containing saliva doesn't get inside the nice clean tooth and re-infect it. Similarly it means that whatever chemicals we use to make the tooth squeaky clean go nowhere near the inside of your mouth. It also makes the whole process a lot more comfortable. As you can see, you also look pretty glamorous.

2.
Shape the canal where the nerve resided to a nice even conical shape with no ledges where bacteria can continue to breed. This is done using an endodontic file. These come in many shapes and sizes. They may be held by hand, or be used in a machine.

3.
Fill the canal COMPLETELY. This is the tricky bit. As you can imagine these pesky canals are very small and in order to make sure the tooth does not become reinfected, the tooth needs to be cleaned and filled right to the end of the root. 

Maybe this picture will help. 

Pic


The picture above shows a tooth with 2 roots and 2 root canals. There are generally a set of anatomical rules for teeth and root canals however as with everything in the human body, this is open to a lot of individual diversity. 
For example, upper front teeth usually have one canal and it would be very unlikely to find a front tooth that varied from this rule. However, upper first molar teeth for example should technically only have 3 root canals (one for each root) but we often find that they have 4. Similarly, for lower molar teeth, these have 2 roots but 3 root canals. 
As you are beginning to see it is quite a complicated process. 

Root filling done, what happens now

Often comes the question of what should be done with the teeth following completion of the "root canal filling" bit. Again this varies depending on which literature you read. In fact there is such debate in this field (oh yes, quite the hot potato of the dental world) that even the Cochrane review on this topic concluded "there is insufficient evidence to support or refute the effectiveness of conventional fillings over crowns for the restoration of root filled teeth". Which basically means, no one can come to an agreement. 

What cannot be refuted however, is that the tooth needs to be adequately sealed after root canal treatment (fortunately a number of scholarly people agree with this - Saunders and Saunders 1994) and in fact even way back in 1990, Torabinejad and his friends found that it only took 19 days for the entire length of the root canal to be reinfected if an adequate filling was not placed following root canal treatment. 

What this means is plain English is that you can't get away with having a root filling done and then live with a naff temporary filling for several years, or in fact months. 
If your dentist is planning on placing a crown on the tooth (which is perfectly reasonable), ensure that a good quality filling is placed, this will not be soft or crumbly. If they give you a temporary crown while your permanent one is being made, it needs to fit well, and if it falls off it should be replaced or recemented immediately. 

Finally, whilst I say this is one of the 2 options for dead (non vital in science speak) teeth it does not guarantee 100% success. This means the following:

1) If your face resembles that of the elephant man, this means there is a whopping great infection at the root of the tooth, and while we could clean it and fill it to textbook perfection, the infection means there is a reduced chance of success
2) Even if you are the "perfect" candidate for root canal treatment (e.g. an infection caught early, nice wide root canals etc) and the root filling is a thing of beauty, this does not mean the tooth will last for the entirety of your days on the planet. At best it can extend the life of the tooth for several years. Some people are very lucky and it may even outlast your human self. Others sadly find it becomes reinfected down the line however at least it buys some time so you can save up for whatever tooth replacement option you fancy. 

"Lazy dentist syndrome"

As I mentioned above, canals are very tricky to negotiate and in some cases even find. Imagine the M6 on a Friday night at rush hour/that country pub in the middle of nowhere that you thought you would try and find. 

On an x ray rather than seeing a nice black line down the centre of the tooth/root as you can in the x ray I put up earlier, you may not be able to see anything. This is due to the fact that the canal(s) have "closed off" or become blocked due to a number of things such as the natural aging process, the infection itself, previous trauma etc. We call this "sclerosis". 

In these situations a specialist endodontist would be the absolute best person to treat you and a referal to such a person can be made by your dentist. 

Sadly I have encountered several patients referred to my place of work with canals the size of the channel tunnel because apparently "no one in the practice is qualified to do root canal", I would therefore suggest you raise the question "at what point was this removed as a necessary examinable requirement OF EVERY QUALIFYING DENTIST IN THE COUNTRY".  

I am not going to go into the many clauses and stipulations of the NHS contract as it is interpretable in many ways. Each dental practice will have their own rhyme and reason for treatments they provide. They may only provide root canal therapy on a private basis however every dentist is qualified to carry it out and in my opinion should at least provide you with an honest opinion and offer to "have a go" or show you on an x ray why they believe it is not feasible for them to attempt root canal (e.g. due to sclerosis). 


Final bit of advice

As you can see, I have been rambling on for many many lines now and could continue for many more about root canal treatment (because sadly I find this all very interesting) however my final pieces of advice are:

  1. Please don't wait until you are in agony to go to the dentist
  2. If your filling comes out with your bacon sandwich, it will not be fine, it is never fine, please go to the dentist to have it fixed
  3. Root canal fillings are an excellent treatment option and are frequently the only means of "saving your tooth"
  4. They however are not 100% in any cases because your tooth is already pretty messed up from the whole rotten tooth thing
  5. Therefore, please brush your teeth and keep the sugar exposures to a minimum. 
As always, ask ask ask away. If you have made it to this point I congratulate you. That's at least a years worth of lectures in one blog post. Maybe I could appeal to make it some sort of verifiable CPD......

References:


Fedorowicz Z, Single crowns versus conventional fillings for the restoration of root filled teeth.Cochrane Database Syst Rev. 2012 May 16;5

Saunders WP, Saunders EM (1994) Coronal leakage as a cause of failure in root anal therapy: a review. Endodontics and Dental Traumatology 10. 105-8

Torabinejad M. Umg B. Kettering JD  (1990) In vitro bacterial penetration of coronally unsealed endodontically treated teeth. Journal of Endodontics 16. 566


Thursday, 3 October 2013

Herpes. Nuff said.

It has come to my attention after having to rebook many patients attending for routine dental care with cold sores over the years, that maybe the infection has been misunderstood and so I thought seeing as it appears to be the time of year (a month I joyfully name "Herptober") where many of the public are being afflicted by said sorrow-causing virus that it would be topical for me to write a post on the subject. 

Anyone who knows me, has met me, has heard me scream or run across the room in horror when I encounter the above topic in the flesh will already have an idea of my opinion on the wonder that occurs on activation of the Herpes Simplex Virus. 

Of course I am referring to the "common" cold sore. According to nhs.uk "Cold sores are small blisters that develop on the lips or around the mouth. They are caused by the herpes simplex virus and usually clear up without treatment within 7-10 days." Although other sources will quote a longer time span of up to 14 days and I would heavily debate the definition "small blisters". 

My hatred and sheer phobia of the cold sore became such an undeniable fact that a colleague thought it appropriate to simply "give me Herpes" as a Christmas present. Now before your minds start whirring away on this information see below:



Yes, the above are in fact cuddly representations of what the Herpes Simplex looks like under the microscope. I am sure most will be in agreement that the above have a strange "cute appeal" to them, however in real life these little blighters are incredibly contagious and whilst they are hideous for the person whom they afflict they can cause some serious issues for health care workers including us dentist minions as well as having the potential to cause further misery to the owner of said blister following dental treatment. 

Complications of coldsores in the dental setting

Small disclaimer - please note this applies to only non urgent dental treatment and each case would be analysed separately on an individual risk benefit basis. 

Firstly, in the interests of fulfilling my GDC responsibilities of working in the best interests of the patient, carrying out dental treatment with a highly contagious cold sore outbreak can lead to spread of the virus around the patient's face and in a small number of documented cases it has even been found to cause nasty lesions on the neck and so not only is the following advice protective to myself but also to anyone we treat. 

This is where the science bit comes in (sorry).

Sotiriou et al. suggested that dental drilling procedures cause saliva to be made into such small droplets that they take on an aerosol form (like your deodorant or hairspray) and these particles are small enough to penetrate deep into the lungs. Which means they can also spray across the room and land on the person we are treating as well as ourselves. This point is echoed by Bentley et al. who measured the distribution of spatter and aerosols generated by dental drills (a thrilling task I'm sure) and found that contaminated aerosol droplets travel a high distance (up to a metre and a half away from the spot marked x) and linger there. Finally Checchi et al.showed that exposed areas of the dentist's face are at risk with contaminated particles.

What this means is that treatment of someone with an active coldsore (most contagious when it is at the nice crusty oozing stage) means risk of more coldsores occurring both on the patient and on us poor toothworkers. 

More seriously is a condition called "Herpetic keratoconjunctivitis". Nhs.uk describes this as "a secondary infection of the cold sore virus that affects your eyes [which] can cause inflammation (swelling and irritation) of your eye area and sores to develop on your eyelids...Left untreated, it can cause the cornea (the transparent layer at the front of your eye) to become infected, which can eventually lead to blindness". Whilst the glamourous protective goggles we insist both the patient and ourselves don during treatment have some role in preventing the aforementioned splatter droplets contaminated with the virus entering our eyes, they are sadly not impervious to everything. So bad news all around really considering that they make you look like you've walked right out of a year 10 chemistry lesson and don't protect you from the Herpes. 

Therefore, please understand that from tingle until the cold sore is completely gone PLEASE DON'T GO TO YOUR DENTIST (or anywhere near me in fact, I am considering appealing to the government for some sort of immediate restraining law should one be within in 500ft of me) unless it is an emergency as it can make it more miserable for yourself as well as the person happily drilling away at your teeth. 

As always, feel free to ask any questions or comments in relation to this. I am now going to douse myself with alcohol gel as even discussing the topic is making my lip tingle. Perhaps a hazmat suit might be a considered purchase for next Herptober.... 

References (apparently you can take the girl out of academia but can't take academia out the girl)
ONLINE RESOURCE www.nhs.uk

Bennett AM, Fulford MR, Walker JT, Bradshaw DJ, Martin MV, Marsh PD. Microbial aerosols in general dental practice. Br Dent J. 2000;189:664–7.
Browning A Case Series: Herpes Simplex Virus as an Occupational Hazard J Esthet Restor Dent. 2012 February; 24(1): 61–66
Essman J. The many challenges of facial herpes simplex virus infection. J Antimicrob Chemother.2001;47:17–27. 
Miller C, Redding S. Diagnosis and management of orofacial herpes simplex virus infections. Dent Clin North Am. 1992;36(4):879–95.
Netatidanesh Risk of Contamination of Different Areas of Dentist's Face During Dental Practices Int J Prev Med. 2013 May; 4(5): 611–615.
Prospero E, Savini S, Annino I. Microbial aerosol contamination of dental healthcare workers’ faces and other surfaces in dental practice. Infect Control Hosp Epidemiol. 2003;24:139–41
Szymanska J. Dental bioaerosol as an occupational hazard in a dentist's workplace. Ann Agric Environ Med. 2007;14:203–7.
Williams GH, 3rd, Pollok NL, 3rd, Shay DE, Barr CE. Laminar air purge of microorganisms in dental aerosols: Prophylactic procedures with the ultrasonic scaler. J Dent Res. 1970;49:1498–1504