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01 Oct 2003 | Australasian Dental Practice

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Germ warfare in the dental surgery

By Professor Laurence J Walsh

Infection Control Technology

Our High Tech Dentistry feature commences on page 82. In this introductory article, Queensland University's Professior L.J. Walsh summarises some of the many new tools and technologies available on the oral health battleground.

Due to the fact that dental caries, endodontic infections and periodontal disease are bacterial infections, it is worth considering what emerging technologies could be brought into the warfare which is waged on a daily basis in dental practices. Using an analogy to a military battle, let us consider briefly how technology is helping to "win the war".

Intelligence and surveillance

Colonisation of infants, children and adults with decay-causing species of bacteria can be detected by using microbiological culture-based tests (Vivadent CRT) or a chairside rapid immunoassay using monoclonal antibodies (GC Saliva-Check SM).

Risk factors which facilitate colonisation of the mouth by acid-tolerant caries-causing bacteria can be checked for using samples of saliva (GC Saliva-Check Buffer).

One of the acids produced by dental plaque when the bacteria ferment sugars (lactic acid) can be measured using an enzyme test and the information used to help assess the caries activity in a patient (3M Espe Cario L-Pop).

Occlusal and cervical caries can be detected at an early stage because of the unique fluorescence profile of cariogenic bacteria (infrared light elicited by visible red laser light), as employed in the KaVo DiagnoDENT.

Armour plating

At-risk areas of teeth (such as fissures and exposed root surfaces) can be protected using glass ionomers with high fluoride release designed specifically for "tooth surface protection" (GC Fuji 7).

Some types of lasers can be used in combination with fluoride to change the surface chemistry, making the tooth surface very resistant to dental caries or dental erosion (KTP, argon, or PAD laser).

Biological warfare

Caries can be prevented by implanting genetically-engineered forms of the bacterial species Streptococcus mutans, which have super-colonising abilities. These bacteria take over the plaque flora but do not cause dental caries. Alternatively, vaccines which stop dental caries exist. The most recent form of this vaccine uses plantibodies, that is, antibodies developed in plants (in this case, tobacco plants) which are infected with a harmless virus.

The adhesion and growth of cariogenic Streptococcus mutans can be inhibited by a range of synthetic antimicrobial agents (such as chlohexidine, as in Colgate Periogard gel), or naturally derived substances, such as Recaldent from cow's milk, and xylitol from the birchwood tree, both of which are in Recaldent chewing gum (GC).

Mineral loss which occurs in the subsurface of enamel (the white spot lesion of dental caries) can be repaired fully using topically applied Recaldent (GC Tooth Mousse). This buffers acids from plaque as well as inhibiting the growth of Streptocccus mutans.

High fluoride products (such as Colgate NeutraFluor gel and NeutraFluor 5000 toothpaste) stop bacteria fermenting sugars and disrupt bacterial enzymes, causing the bacteria to die.

Star wars

Bacteria in root canals, periodontal pockets, and deep carious lesions can be killed rapidly using a photo-chemical reaction where a dye which binds to bacteria but not human cells is triggered by a penetrating low power visible red laser (Denfotex SaveDent). This dye delivers reactive oxygen compounds at point blank range which cause the killing. A different oxygen-based strategy is to apply ozone gas directly to open cavities, to stop them progressing (KaVo HealOzone).

Artillery assault

Several technologies exist which can effectively sterilise a cavity preparation during its preparation, for instance chemo-mechanical caries removal with Carisolv gel (Trollplast), or cavity preparation with a middle infrared laser (e.g.Lumenis Opus Duo, KaVo KEY Laser 3, Fotona Fidelis, Biolase Waterlase). Most high power lasers (such as those used for surgery or cavity preparation) have powerful sterilising capabilities and some systems have tips which allow the laser to be used in periodontal pockets or root canals.

Guided missile attack

Caries removal can be guided using the fluorescence signal from bacteria (KaVo DiagnoDENT), or both caries and subgingival calculus can be detected, targeted, and destroyed using the fluorescence signal to control an Erbium:YAG laser beam (KaVo KEY Laser 3) which functions in a seek-and-destroy manner.

Damage control

Synthetic materials including ceramics and hydroxyapatite have been developed which can be applied onto a tooth as a powder and then fused into a solid form, with the potential to act as a replacement for carious tooth structure.


This short article has outlined some of the military intelligence behind the battle, revealing a comprehensive surveillance operation, and the specifics of multi-pronged assault employing a range of munitions.

To the victor go the spoils.

About the author

Laurence Walsh is Professor of Dental Science at the University of Queensland School of Dentistry, and also holds an appointment within the University's Centre for Biophotonics and Laser Science. He maintains a busy referral-only part-time clinical practice in the area of special needs dentistry. Professor Walsh has research interests in advanced technologies such as lasers, and in biomaterials, clinical microbiology and infection control.


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