RECENT ADVANCES IN CARIES DIAGNOSIS & PREVENTION

INTRODUCTION

DIAGNOSTIC TOOLS

VISUAL TACTILE VISUAL TACTILE RADIOGRAPHS - Conventional – IOPAR & Bitewing

- Xeroradiography- Digital – 1. Enhancement

2. Subtraction3. Tuned Aperture Computed Tomography (TACT)

BASED ON VISIBLE LIGHTOptical caries monitor (OCM)FOTI and DIFOTIQLF & DIAGNODENT, DELFUltraviolet

BASED ON ELECTRICAL CURRENTElectric conductanceElectric Impedence

ULTRASOUND ENDOSCOPY, Videoscope DYES – Enamel & Dentin

NEWER TECHNOLOGIES:1. Terahertz2. Multi-photon Imaging3. Optical coherence tomography4. Infrared fluorescence5. Infrared thermography

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CARIES PREVENTION

Current Strategies

1. Combating microorganisms2. Diet modification3. Increasing tooth resistance4. Increasing host resistance.

Minimally Invasive preparation

CONCLUSION

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INTRODUCTION

Caries diagnosis is the art or act of identifying a disease from its signs and

symptoms.

Caries process is dynamic, with demineralization and remineralization

occurring overtime such that the net balance of these events determines whether a

lesion ever progresses to the stage where it can be seen as a white spot / detected

by other means. In recent years, a dramatic decline in caries incidence and

prevalence has occurred in most industrialized countries, as a result of efficacy of

various form of fluoride. Clearly, a decrease prevalence also indicates that fewer

lesions now progress from the stage of sub surface demineralization to frank

cavitations. The changing nature of the disease process has therefore accentuated

the need for more precise detection methods. Unfortunately, because of the nature

of disease process in the past, the currently available diagnostic methods have

limitations due to which the dynamic nature of lesion is not measured.

Most currently used diagnostic methods are subjective in nature.

1. Detect lesion only at an advanced level.

2. Cannot quantify the mineral loss

3. Cannot measure the small changes in mineral loss (gain) on demineralization

Early detection of carious lesions is an important and necessary process in

order to detect the early stages of demineralization. Operative treatment should be

required only when the caries process has reached a non reversible point. The

same treatment philosophy should apply to secondary caries. Secondary caries is a

major reason for replacing restorations, however it is difficult to detect at early

stages. Wall lesion cannot easily be detected until they have reached an advanced

stage. Colors next to restoration are not always predictive of secondary caries.

Stained composites margins and ditching of amalgam restorations are not

necessarily signs of decay, although they indicate greater risk. Despite the fact that

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sharp probes have been used, visual examination with tactile instrument is still the

most commonly widely used method. Several additional detection techniques are

available for secondary caries detection and quantification. They include ECM,

light and laser induced fluorescence, fibrocoptic transillumination and ultrasonic

measurement.

Due to nature of secondary caries, which in many instances presents an

outer and wall lesion, validation of secondary caries is difficult. There are several

methods available to measure mineral loss such as histopathology (Silverstone

1973) which requires thin section 100 micro meter and micro radiography

(Arends 1987), which involves use of radiation and thin section. Confocal laser

scanning microscopy presents several advantages such as not requiring a thin

section / involving radiation and can be done in a shorter times.

DIAGNOSTIC TOOLS FOR CARIES

Several methods have been employed for caries diagnosis. These include

a. Visual method

b. Tactile method (probing)

c. Visual – Tactile – European system, USA system

d. Radiographs

Conventional –IOPAR, Bitewing

Xeroradiography

Digital

Digital enhancement

Subtraction Radiography

TACT (Tuned aperture computed tomography)

e. Based on visible Light

Optical caries monitor

FOTI & DIFOTI

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Quantitative Light Induced fluorescence (QLF)

f. Based on Laser Light

Laser Auto fluorescence (Diagnodent)

Dye enhanced Laser fluorescence (DELF)

g. Electrical current

ECM (Electrical Conductance Measurement)

Electrical Impedance (ACIST)

h. Ultrasound – Ultrasound caries detector

i. Ultraviolet

j. Endoscope (Endoscopic filtered fluorescence EFF)

k. Dyes – Enamel & Dentin

l. Dye penetration method

A) VISUAL METHOD

Ranking systems:

Criteria for clinical and radiography

Score Criteria

0 Sound

1 Active, surface intact

3 Active, surface discontinuity

4 Active with cavity

5 Inactive, surface intact

6 Inactive, surface discontinue

7 Inactive, cavity

8 Filled with active lesion

9 Filled with inactive lesion

10 Extracted due to caries

MACHIULSKIENE, et al (1998)

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Criteria for visual examination

0 No or slight change in enamel transparency after prolonged drying

1 Opacity or discoloration hardly visible on wet surface but distinct

on air drying

2 Opacity distinctly visible without air drying

3 Localized breakdown in opaque or discolored enamel and gray

discoloration of dentin

4 Cavitations in opaque/enamel exposing the dentin

B) PROBING (TACTILE EXAMINATION)

During the past 10 years the role of explorers in caries detection has

become a controversial issue. There was no difference in diagnostic accuracy

between explorer and visual inspection.

Sensitivity – 62%

Specificity – 84%

Disadvantage

- It can produce traumatic defects in lesions arrested by plaque control alone.

- Does not improve accuracy of diagnosis.

- Inter operative variables.

C) VISUAL TACTILE METHOD

Makes use of both visual along with tactile sensitivity with a probe /

explorers.

European System depends on detailed visual examination. Subjects clean their

teeth before examination, tooth surface dried with compressed air, and

examination requires 10 minutes / subject.

American Dental Association Criteria (USA) uses the softened enamel that

catches an explorer and resists its removal and allows the explorer to penetrate the

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proximal surfaces with moderate to firm probing pressure. Here teeth are well lit,

but neither cleaned nor dried and it takes 3 minutes per subject.

D) RADIOGRAPHIC

The purpose of the radiograph is to detect lesions that are clinically hidden

from careful visual examination.

CRITERIA (MEJARE et al 1999)

R0 = no radioluscency

R1 = Radioluscency confined to outer half of enamel

R2 = Radioluscency in inner half of enamel + extending upto but not beyond DEJ.

R3 = Radioluscency in dentin, broken DEJ, but with no obvious spread in dentin

R3 = Radioluscency with obvious spread in outer half of dentin.

R4 = Radioluscency with obvious spread in inner half of dentin (> half way

through to the pulp)

(Five point scale for occlusal caries) (Espelidel, 1994)

Based on clinical visual examination + radiographs

Grade 1: Non cavitated white spot / slightly discolored caries lesion in enamel not

detected in the radiograph.

Grade 2: Some superficial cavitation in the fissure entrance, some non cavitated

mineral loss in the surface of the enamel. Surrounding the fissure / and a caries

lesion in enamel detected on the radiograph.

Grade 3: Moderate mineral loss with limited cavitation in the extreme of fissure /

lesion in the outer third of dentin, detected on radiograph.

Grade 4: Considerable mineral loss with cavitation / or lesion into the middle third

of the dentin, detected on the radiograph.

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Grade 5: Advanced cavitation / or lesion into the inner thirds of dentin, detected on

radiograph.

Disadvantages

- Overlapping of approximal contact

- Cavitation not made out

- two dimensional representation

- Cervical burnout may mimic cervical caries

- False diagnosis of lesion depth

Radiographic appearance of caries

a) Occlusal caries

radiography are ineffective for detection until it reaches the dentin.

Limitations

-Super imposition of enamel over fissures, lesions involving buccal groove

can simulate an occlusal lesion.

-Difficult to diagnose between occlusal caries and internal resorption.

b) Interproximal

A considerable loss of mineral content is mandatory before lesion becomes

visible on radiograph. The actual depth of lesion is always deeper than on

radiograph.

Root caries / cemental caries / senile caries

Lesions on root with ill defined saucer appearance.

Grading

Grade I – Incipient

II – Shallow, less than 0.5 mm

III – Deep

IV – Pulpally involved

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Diagnosis is not difficult except where lesion is hidden by periodontal pockets..

Secondary Caries

Limitations of radiographs

Difficult to diagnose between residual and secondary caries

Cannot be visualized unless it reaches an additional stage.

Other problems

- Discoloration at margins could be due to corrosion products

- Cannot differentiate between activity of lesion

- Marginal failure to be distinguished from secondary caries

XERORADIOGRAPHY

Image is recorded on aluminum plate coated with layer of selenium

particles. These particles have a uniform electrostatic charge. When x-rays are

passed on the film, this causes selective discharge of particles.

> latent image formed > converted to a positive image by a process called

“development.”

-Advantages: Edge enhancement, no dark tooth procession

-Disadvantages: The electric charge over the film may cause discomfort to the

patient, exposure time varies

DIGITAL IMAGING

A digital imaging is an image formed and represented by a image formed

and represented by a spatially distributed set of discrete sensors and pixels when

viewed from a distance the image appear continuous, but on closer inspection it

has individual pixels. Digital image is simple means where image is recorded in

non film receptors. There are 2 types.

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-Direct- the direct image receptor that collects the x-ray directly e.g. RVG

-Indirect- E.g. Video camera is used for forming digital images of a radiograph.

The advent of digital imaging has revolutionized digital imaging. The term

digital refers to the numerical format of the image content as well as its

discreteness.

-DIGITAL DETECTORS

Charged Couple Device (CCD)

Complementary metal oxide semi conductor (CMOS)

Phosphostimulable phosphorous plates

CCD was the first direct digital image receptor adapted for intra oral imaging and

was introduced the dentistry in 1987. The CCD is a solid state detector array with

metal oxide semi conductor structure, such as silicon that is coated with X-ray

sensitive phosphorous and is extremely sensitive to electromagnetic radiation

whether X-rays / visible light. These phosphorous converts incoming x-rays to

wavelength that match the peak response of silicon. The detector array consists of

either a column (Linear detector) or a chip (in which pixels are arranged in row

and columns (area detector).

Mechanism of image formation

When exposed to radiation, the covalent bunds between silicon atoms are

broken – electron hole pairs – get attracted to the potential to form charge packet.

Each pocket corresponds to 1 pixel___ the charged pattern from individual pixels

form the latent image.

The image is read by transferring each row of pixel charges form one pixel

to the next. As the charge reaches the end of the row – transferred to a read out

amplifier and transmitted as voltage – gets converted to digital image.

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Voltages from each pixels are sampled and assigned a numerical value on

the gray scale. Pixel size varies from 20-70%

CMOS

These detectors are silicon based and are fundamentally different from

CCD’s in the way that each pixel charge is read. Each pixel as connected directly

to a transistor.

Phosphostimulable Phosphor Plate (PSP)

PSP absorb and store energy from X rays and then release this energy as

light (phosphorescence) when stimulated by light of appropriate wavelength. The

material used in Europeum doped Barium Fluorohalide. Barium in combination

with iodine, chlorine, bromine forms crystal lattice. The addition of europium

creates imperfections in this lattice. When simulated, valence electrons Europium

can absorb energy and move into conduction bond. These electron migrate to

nearby (F centers) halogen valencies in the fluorohalide lattice and become

trapped there.

When stimulated by Red Light around 600 nm, the barium fluorohalide

releases trapped electrons to the conduction band. When an electron returns to

Europium ions, energy is released in the green spectrum between 300-500 nm.

Fiber optics conduct light from PSP plate to photo multiplier tube.__ Converts

light to electrical energy (A red light filter removes the stimulating light, and the

remaining green light is detected and converted to varying voltage – digital image.

E.g. of Direct digital radiography.

RVG (Trophy Japan) 10 x 28 mm

Flash (Villa Italy) 20 x 24

Sens – A ray (Regan) 17 x 26

Vixa – (Gendex) 18 x 24

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-Advantages

Instant image, no dark room, Consistent image

Eliminates hazards of film development

Radiation dose is decreased

Capable of tele transmission

-Disadvantage

Cost

Life expectancy of chip

DIGITAL IMAGE ENHANCEMENT

It was shown that the resolution of digital image is lower than radiographs

and the range of grey shades is limited to 256, where as in a radiographic film,

over one million shades of grey appear. The diagnostic performance of un

enhanced digital image does not exceed radiographs. Therefore, the contract can

be digitally enhanced using a mathematical rule often decided by the algorithm /

filter.

DIGITAL SUBTRACTION RADIOGRAPHY

Here, a digital bitewing radiograph is taken and sometime later a second

radiograph of exactly the same region is produced with identical exposure time,

tube current and voltage. By subtracting the gray values for each coordinate of the

first radiograph from equivalent coordinate of second, a subtraction image is

obtained.

TUNED APERTURE COMPUTED TOMOGRAPHY (TACT)

This technique is recently introduced and is still under development. This

method contracts radiographic section through teeth. The slices can be viewed for

presence of radioluscencies. Slices can be brought together in 3-D computer model

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called a psedohologram. TACT slices and pseudohologram are adequately detect

primary and secondary caries.

E) DIAGNOSTIC METHODS BASED ON VISIBLE LIGHT :

Includes

a) Optical caries monitor

This comprises of light source, measuring and reference units and a

detection part. The light is transported through a fiber bundle to the tip of

hand piece. The tip is placed against the tooth surface and the reflected light

is collected by different fibers of the same tip. Disadvantage – used only for

smooth surface lesion.

b) Quantitative fiber optic transillumination : FOTI works under the

principle that since an area of carious lesion has a lowered index of light

transmission, an area of caries appears as a darkened shadow. FOTI was

initially developed for proximal caries detection.

Method -- A 150 watt halogen lamp and rheostat is used to produce a light

of variable intensity. A fiber optic probe of 0.5 mm diameter is used to

place in embrasure area. The marginal ridge is viewed from occlusal

surface.

Advantage : No hazards , lesion not diagnosed by radiographs can be

diagnosed

Disadvantage : Subject to inter and intra observer variation.

The major problem being low sensitivity.

Therefore DIFOTI was introduced. Here instead of human eye a CCD

receptor is used. The receptor with photocells converts photon energy to

electrical energy – transmitted to a video processor-converted into colour

value and displayed on video monitor. Advantage initial results indicate

that both specificity and sensitivity are high.

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c) Quantitative Laser or Light Induced Fluorescence (Laser Auto

Fluorescence ) : The use of Fluorescence for detection of caries dates back

to 1929, when Benedict observed that normal teeth fluoresce under

ultraviolet illumination. There is a difference in the Fluorescence of sound

and caries teeth.

Loss of Auto- Fluorescence is due to

1) Light scattered and thus the absorption per unit volume is small.

2) Light scattering in the lesion and prevents the light from reaching the

Fluorescing dentin.

3) Protenic chromophores are removed by caries process

Method :- Blue-green visible light emitted from a argon ion laser of

wavelength 488 nm wavelength is used. When the tooth is exposed to this

light, Fluorescence of enamel occurring in yellow wavelength is observed.

(540 nm) through a yellow high pass filter to exclude the scattered blue/green

light. Demineralized appear as dark spots. To facilitate clinical studies a

portable variant QLFTM is used. QLF is two step procedure. –

1) Image acquisition with CCD camera

2) Image analysis using the software

DIAGNODENT : A variant of QLF system, a diagnodent (KAVO – 1999) was

based on research Hibst and Gal. Light source – diode laser red light 655 nm.

Method :

Red light is transported via an angulated tip with central fiber. Reflected

light is eliminated by and taken up by the photo-diode and processed and

presented on display as 0-99.

Values : 5-25 initial lesions in Enamel

25-35 initial dentinal caries

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> 35 advanced dentinal lesion.

ULTRAVIOLET : UV light is used to increase the optical contrast between

caries region and surrounding sound teeth.

Advantage : Sensitive than visual tactile method

Disadvantage : Specificity is a problem as it cannot detect between caries lesion

and developmental defect.

DYE-ENHANCED LASER FLUORESCENCE :

It had higher sensitivity than laser auto Fluorescence alone. Dyes used are

- Pyro methane 556

- Sodium Fluorescin

F) DIAGNOSTIC METHODS BASED ON ELECTRIC CURRENT :

a) Electrical conductance measurement : This is based on the principle that

a demineralized tooth has more pores filled with water and this is more

conductive than intact tooth surface. When current is applied by placing an

electrode on tooth surface, the electrical conductance is measured between

this electrode and contra electrode.

b) Electrical impedance measurement : Impedance is a measure of degree

which an electric current resists electric current flow when a voltage is

applied across two electrodes. Caries tissue has lower impedance(or

conduct electricity better) than sound tooth.

G) DIAGNOSTIC METHODS BASED ON ULTRASOUND

MEASUREMENTS :

Ultrasound makes use of sound wave with a frequency ranging from 1.6 to

10 MHz. Ultrasound interacts differently with different tissues. Ultrasound

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production – by application of an alternating voltage applied to an piezo electric

crystal.

Method :

To reach the target tissue, a coupling agent namely water, glycerin is used.

A flexible probe tip is fit into wedge shaped inter proximal contours to confirm to

the shape of the tooth.

Disadvantages : Only for superficial enamel lesions.

H) ENDOSCOPE :

A blue light (400-500 nm) is used to excite Fluorescence with in the tooth.

Advantage : 5-10 fold magnification

Disadvantage :

Requires meticulous drying and isolation. Takes 5-10 minutes compared to 3-5

minutes for conventional technique.

Additionally a camera can be used to store the image. The integration of camera +

endoscope is called video scope. A miniature colour video camera is mounted in a

custom made metal holder. Thus image is directly viewed on a television screen.

I) DYE-PENENTRATION METHODS :

a) For caries Enamel :

● Procion disadvantage - irreversible as dye reacts with

nitrogen and hydroxyl groups of enamel.

● Calcein : Complexes with calcium

● Fluorescent Dye : i) Brilliant blue ii) ZygtoZX - 22

b) For Caries Dentin :

● 0.5% basic fuschin in propylene glycol

● 1% acid red in propylene glycol

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Modified dye penetration method – Iodine penetration method for

measuring enamel porosity of incipient caries region was developed

by Balnos in 1977.

NEW DIAGNOSTIC MODALITIES FOR CARIES LESION

- Multi photon imaging

- Terahertz imaging

- Transversal wavelength independent microradiography

- Infra red thermography or infra red fluorescence

- Frequency domain photo thermal radio metry and

Frequency domain luminescence

Multiphoton imaging :

Advantage :

1) Non invasive method – that measures the amount of mineral loss as a

function of fluorescence loss.

2) Low average level of laser power. Therefore lower risk of photo toxicity to

the pulp.

3) Longer incident wave length results in increased penetration.

Disadvantage :

1) The Micron assay movements required to produce serial tomographic

images over a period of 1 min or so is well beyond the capabilities of

most dentists.

2) Can collect information from caries lesion up to 500 µm

3) Currently the technique is performed only on extracted teeth and large

laser equipment required to produce such an image will take years to

develop.

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Infra-Red Thermography :

This technique has described as method of determining lesion activity

rather than a method of determining of presence or absence of disease.

Principle - thermal radiation energy travels in the form of waves. It is possible to

measure changes in thermal energy when fluid is lost from a lesion by

evaporation.

Disadvantages :

1) Not used intra orally

2) Variation will exist in temperature of mouth with respiration or fluid

evaporation from oral surfaces.

3) The source to specimen distance is unsuitable for posterior teeth.

4) There is no data that the rate of fluid loss from the lesion is directly related

to the reactivity of the lesion.

Infra-red Fluorescence :

Method : Tooth is exposed to light with the wave length between 700 and 15,000

nm. Barrio filters are used to observe any resulting Fluorescence.

Disadvantages :

1) Results are not documented.

2) May have potentially damaging effects on the pulp given the increased

penetration and decreased scattering of the longer wave length.,

3) Sources of such irradiation are difficult to acquire.

4) Detection involves the use of infra red sensitive detectors as CCDs or film.

Optical Coherence Tomography (OCT)

OCT is a method of imaging that has been developed for transparent and

semi transparent structures. It was first developed in medicine for use in

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ophthalmology and only in recent years interest in use of OCT for dental imaging

has grown. Wave length of light 840-1310 nm depth 0.6-2 mm.

Principle : It is based on interference of light. When a light beam is split into two

and then recombine interference produces a pattern the intensity of which is

determined by the level of light in each beam. OCT uses super luminescent

diodes. (SLD) as light source. This type of source produces light with the broad

range of wave length.

Advantage :

1) Non-invasive diagnosis of secondary caries

2) Development of prototype hand pieces for intra-oral OCT

Disadvantage

1) Stain uptake will interfere with the intake.

Terahertz Imaging : Uses waves with terahertz frequency (15 µm to 1 mm) This

wavelength form a short enough to provide a reasonable resolution but long

enough to prevent a serious loss of signal due to scattering. A good overview of

this technique is provided by Arnone et. al.

Source of Terahertz radiation – In 1980 It was discovered that photoconductive

emitters of certain crystals (Zinc telluride) exposed to short pulses (<10-12)

seconds of visible infra red light would emit electromagnetic waves with the

frequency in the terahertz range.

Method : For image to be obtained , the object is placed in the path of terahertz

beam or the terahertz beam can be scanned over the surface of the object, the

image is recorded using CCD imaging.

Advantages

1) Low powers used for imaging.

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2) Use of Non-ionizing radiation.

3) No alteration of electrical charge of tissue examined.

Disadvantages :

1) low spatial resolution due to long wave length of the source.

2) Alterations in image interpretation since terahertz waves are strongly

absorb by water, a potential complication in the mouth.

CARIES PREVENTION

Despite the major accomplishments of preventive dentistry in reducing caries

prevalence, the problem is still with us. There is a continuing need for improvement in

existing preventive products and technique. And the broadening of our anti-caries

armamentarium.

It is apparent that caries is considered as a infectious disease, and it should not be

considered as a result of infection with one specific type of microorganisms. The

infectious agents are the indigenous flora of the oral cavity.

Can caries be prevented ?

The formation of biofilm on tooth surface cannot be prevented in surface

irregularities such as occlusal fissures. The formation of cavities can be prevented by

controlling the caries process, but metabolic fluctuations in the biofilm cannot be

prevented. Thus caries is a ubiquitous natural process. Thus accepting that biofilm

constantly form and grow on any tooth surface, these regular demineralization and

remineralization, which occur at random cannot be prevented because they are a

ubiquitous and natural process. There effect on tooth surfaces overtime can however be

influenced and the metabolic process can be modified. Caries lesion development and

progression can thus be controlled. Therefore, by controlling the disease process it is

possible to prevent cavities from occurring.

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Thus, it is illogical to use the term “Preventive” as strictly speaking, preventing a

disease means to eliminate it, and it is not possible to eliminate the ubiquitos physiologic

process called caries process. But it is possible to avoid it resulting I extensive de-

mineralization by controlling the outcome.

CURRENT STRATEGIES IN CARIES PREVENTION

The current approaches to caries prevention are essentially the same as that

proposed by the NATIONAL CARIES PROGRMME 1971-1983. As such the national

institute of dental research has developed the following three part strategy. This includes

a) Combating caries inducing microorganisms and preventing plaque buildup

b) Modifying caries from promoting ingredients of the diet.

c) Increasing the resistance of tooth to decay

d) Enhancing host resistance

COMBATING CARIES INDUCING MICROORGANISMS AND PLAQUE

BUILD UP :

These include

i) Personal oral hygiene methods for plaque control

a) Mechanical b) Chemical plaque control

ii) Fluorides

iii) Caries vaccine

iv) Blocking plaque built up

A) ORAL HYGIENE METHODS :

a) Mechanical means:

Manual

i) Tooth brushes

Electric

Manual tooth brushes : Tooth brushing is the most widespread

mechanical means of plaque control in the world. The tooth brush has very

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limited access to the wide approximal surfaces of the molars and pre-

molars. Therefore supplementary plaque control methods should be

performed on these high risk surfaces.

Electric tooth brushes : In 1986, An international workshop on

Oral hygiene concluded that, to date power tooth brushes remove no more

plaque than manual tooth brushes regardless of methods.(Loe and

Kleinmal, 1996) Eg : Rotadent , Interplak , Sonicare electric brush.

ii) Inter dental cleaning aids : These include interdental brushes (manual and

electric) toothpick, dental floss and dental tape with or without holder.

iii) Professional tooth cleaning : (PMTC) : PMTC is a service provided by

dental personnel (Specially trained dental nurses , dental hygienist and

dentist.) and is defined as selective removal of all plaques from all tooth

surfaces. This is known as KARL STAD Programme, and was developed by

Axelson and Lindhe(1974)

b) Chemical plaque control

There are contrasting opinions among dental professionals as to the use of

chemical agents in the prophylaxis and treatment of dental caries. Those in favour are

of the opinion that any reduction of dental plaque is beneficial if accomplished safely,

self performed mechanical control of plaque is difficult to perform and often

inadequate. Thus, chemical agents may offer an adjunct. Those opposing the use of

these agents argue that they may disturb the ecological balance within the oral cavity,

and that resistant strains may emerge.

Principle modes of action of an anti-plaque agent are

- Inhibition of microbial colonization

- Inhibit microbial growth and metabolism

- Disrupts matured plaque

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- Modification of plaque, bio chemistry and ecology

Vehicles for administration of anti-biotics:

Toothpaste, Dentifrices, Mouth rinses, Irrigants, Gels, Spray, Chewing gum and

Losenges, sustained released devices.

Classification of Agents :

I. Cationic agents

II. Anionic agents

III. Nonionic agents

IV. Other agents

V. Comination of plaque control agents

I) CATIONIC AGENTS :

These includes

ii) Bisguanides – Chlorhixedene and Alexidene

iii) Quaternary ammonium compounds - Cetyl pyridinium chloride ,

Benzethonium chloride, Domiphen bromide

iv) Hesvy metal salts – Copper, Zinc , Tin

v) Pyrimidines - Hexitindene

vi) Herbal extracts – Sanguinarine

Cationic agents are generally more potent than nonionic or ionic agents. This is

because cationic agents bind readily to the negative charged microbial surface.

They interact with gram positive and gram negative micro organisms.

Binding sites

– On gram positive microorganisms – With the free carboxyl group from

Peptidoglycans, with phosphate groups from lipoteichoic and teichoic acid

within the cell wall.

– On gram negative microorganisms – Lipopolysaccharides in cell walls.

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a) Chlorhexidene : (CH) It is the most thoroughly studied and most effective anti

plaque agent. It is often used as old standards against which the measure potency

of other agents. CH is bisguanide used with both hydrophilic and hydro phobic

properties. It was first tested intra orally by Schroeder(1969)

Mechanism of action :-

- Bacteriacidal on high concentration, causing precipitation of cell wall constituents

and contents.

- Bacteriostatic at low concentration – causing interference with normal membrane

functions.

- Inhibits enzymes that are essential for microbial contamination on tooth surface.

Eg:- Glucosyltransferase and microbial metabolism.

Superior anti-plaque agent due to – substantivity

Microbial reduction –

80 to 95% via single mouth rinse with 0.2% CH

Dosage – In mouth rinse –

- 10 ml of 0.2% - twice daily

- 15 ml of 0.12% - twice daily

In chewing gums – 20 mg per piece.

In tooth paste 0.4%

b) Cetylpyridinium chloride : A quaternary ammonium compound used in mouth

rinses. The anti microbial activity of CPC is equal to or better than CH but its plaque

inhibitory property is inferior as it losses its anti microbial properties upon absorption

to tooth surfaces.

c) Heavy metal salts : (Cu2+ Sn2+ , Zn2+)

As early as 1890, Miller proposed the use of metal ions to treat rampant caries.

The anti microbial efficacy is proportional to the concentration of free metal ions.

The anti microbial effect is unspecific. Cu2+ and Sn2+ are more potent than Zn2+. But

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Zn2+ is a known anti calculus agent and it can combine with sulphur containing

compounds in the pellicle to form metal sulphides.

Disadvantage : Staining due to metal sulphides.

Dosage – mouth rinses containing Cu2+ (0.25 to 5%)

Zn2+ ( 5 to 30%)

Zinc citrate 0.5% in dentifrices.

Mechanism of action

- Inhibits glycolytic enzyme.

- Inhibits adsorption of bacteria to the tooth surface and growth of existing bacteria

in plaque.

- Increase substantivity of triclosal

d) Pyrimidines (Hexitidine) : It is a synthetic hexahydropyridine which has anti

microbial and anti fungal activity.

Mechanism of action : Not known.

Dosage : -,. 0.10 to 0.14% in mouth rinses along with divalent metallic ions like Cu2+

and Zn2+

e) Herbal extracts – Sanguinaria : Sanguinaria is a herbal preparation. It is a mixture

benzophenanthridine alkaloids, obtained by alcohol extraction , form the blood root plant

sanguinaria Canadensis.

Mechanism of action : - Suppresses the activity of several enzymes.

Bactericidal effect by interfering with essential steps in the synthesis of microbial cell

wall.

Dosage : Available along with Zncl2 in mouth rinses and tooth paste.

II) ANIONIC AGENTS :

Sodium dodecyl sulphate (sodium lauryl sulphate) : It is the most frequently

used detergent in commercial dentifrices.

Mechanism

i) gets absorbed on the microbial surface and interferes with cell wall integrity.

And causes cellular components.

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}10 ml solution for 1 min

ii) Inhibits specific microbial enzymes.

iii) Competes with negative charged microbes for absorption sites on tooth. Has

high affinity for tooth Ca2+

Negative effect –

SLS binds to hydroxyapatite and brings about increasing clearence of

sodium monofluoro phosphate in tooth paste thus decreasing the

fluoride effect of sodium mono fluro phosphate.

Interacts with CHx

III) NONIONIC AGENTS

- Triclosan , Thymol , Listerine , 2 poly phenol , Hexyle resorcinol

Listerine and triclosan are the most frequently used.

a) Triclosan : It has a broad anti microbial spectrum.

Mechanism of action: Inhibits lipid synthesis and leads to defective cell

membrane synthesis.

Disadvantage : Low substantivity and decreased anti microbial effect.

Formulation – in dentifrices and mouth rinses

Dosage – 10 ml of 0.03% mouth rinse and 0.3% in tooth paste

b) Listerine : Listerine named after Lister was tested for efficacy against

oral bacteria as early as 1884 by W.D. Miller. It is a combination of

thymol, Eucalyptus, Menthol and methyl salicylate in a hydro alcoholic

solution (Mandel 1988)

Mechanism of action :

o At low concentration – Inactivation of essential enzymes

o At high concentration – cell wall disruption and precipitation of proteins.

c) Salifluor : It is a chemical derivative of Aspirin with antibacterial and

anti inflammatory properties.

Dosage : 0.12% in mouth rinses

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IV) OTHER AGENTS

a) Delmopinol : It is a surface modifying agent that belongs to the group of

compounds known as substituted amino alcohol.

Mechanism of action : Unclear but disrupts bacterial matrix formation by

interfiering with bacterial attachment.

Dosgae : 0.1 and 0.2% in mouth rinses.

Side effects : Anesthesia

b) Enzymes : Hydrogen peroxide controls the proliferation of microorganisms and

through its peroxidase activity oxidizes thiocynate to hypo thiocynate that is an

anti microbial. Therefore this activity depends on presence of hydrogen peroxide.

Formulation : Toothpaste and mouth rinses

c) Xylitol : It is five carbon natural sugar alcohol (Pentilol) is used as alternative

sugar substitute. Like all other polyols, It can’t be fermented by oral

microorganisms, non acidogenic and does not promote dental caries.

Mechanism of action

- Inhibitory effect on glycolysis in certain micro organisms.

- Reduces adhesiveness through impaired polysaccharide formation of

microorganism.

- Remineralization

- Less carcinogenic flora

Formulation

Dentifrices and chewing gums

However evidence is still lacking to confirm the claimed effects of xylitol.

V) COMBINATION OF AGENTS

Plaque is a complex aggregation of various bacterial species. It is therefore

unlikely that one single agent can be effective against the complex flora. The

combination of two or more agents may enhance the efficacy and reduce adverse effects

of chemo prophylactic agents. E.g. :

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1) Heavy metal salts + detergents (Cu2+ or Zn2+ + Sodium lauryl sulphate)

2) Triclosan combinations (Triclosan + Zn2+)

3) Fluoride + CHX(NaF (0.044% + CHX 0.05%)

4) Fluoride Combinations (Amine fluoride + Snf2)

B) FLUORIDES :

Fluorides is still the corner stone of modern non invasive dental caries

management. However the actual mechanism of fluoride action remains a subject of

debate. From earlier clinical and laboratory studies it can be concluded that the main

action of flurode is post eruptive.

Modes of Delivery :

Systemic

Topical

Systemic :

- Public water – 1-1.2 mg / L Fl-

- Fluoride tablets – 2.2 mg NaF (1 mg Fl-)

- Salt fluoridation – 90 mg / kg Fl-

- Milk fluoridarion – 0.05 mg / L Fl-

- Fluoride drops – 1 drop = 1 mg of Fl-

Topical

Self application Professional

Toothpaste Gels

Mouth rinse Varnishes

Tablets & Lozenges Slow release Fluoride

Gels & Foams Aqueous solutions

Toothpick, Floss, Tape Prophylaxis paste

Chewing gum

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Topical fluorides

Available fluoride agents include

a) Inorganic compounds

- NaF , SnF2 , Ammonium Fluoride, Titanium tetra Fluoride

b) Mono fluoro phosphate containing compounds

- Sodium monofluoro phosphate

c) Organic Fluorides

- Amine and silane fluorides

d) Combinations

- AmF+ NaF(Prophylaxis paste)

- NaF + SmFP

Topical Fluorides for self application includes

1) Dentifrices

Fluoride in the form of

NaF – (0.20%)

SmFP (076%)

SnF2 – (0.40%)

Formulation – 1000 ppm of fluoride that is 0.1% F= 1 mg Fl-/1 gm of paste

Caries reduction by 20%

2) Mouth rinses

Low doses – 0.04 – 0.05 % NaF (daily use 225 ppm of fluoride)

Caries reduction 30-40%

High doses – 0.2% NaF (909 ppm weekly or fortnight)

Caries reduction – 30-40% in 2 years

Typically 10 ml of solution is swished in the mouth for 1 min.

3) Fluoride gels and foams : They contain a variety of fluoride levels ranging from

those found in mouth rinses to 5000 ppm fluoride.

4) Fluoride lozenges : Slow release fluoride – 0.25 mg Fl-

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5) Fluoride chewing gums : (Fludent , Fluorette ) Each piece contains 0.25 mg of Fl-

chewed for a duration 20 min - releases 80% of fluoride.

6) Fluoridated toothpick or floss and tape

Wooden toothpick (4% NaF) used for 2 min – releases 0.15 mg of fluoride.

7) Fluoridated artificial saliva spray : Sprays of artificial saliva containing NaF to

be applied 20-30 times a day inpatients with xerostomia.

Professional Application :-

1) Aqueous Fluoride solutions : Introduced in 1940 this was the first method

professional fluoride application. Includes :-

Neutral sodium fluoride 2% (1% F)

Stannous fluoride 8% (2% F)

Acidulated phosphate fluoride (1.23% F)

2) Fluoride Gels: They are similar to those for self care but have higher

fluoride concentration.

Eg : 2% NaF (0.9% F) , 2% SnF2 (0.5F)

3) Fluoride Prophylaxis paste: Sodium fluoride is the most commonly used

agent. Fl- concentration ranges from 0.1 – 1%

4) Fluoride varnishes: Fluoride varnishes have been available in Europe

since 30 years and widely used for professional application.

Eg: Duraphat (5% NaF varnish containing 2.26% Fl-)

Fluorprotector – Polyurethane based varnish(0.9% silane

fluoride with 0.1% fluoride.)

5) Slow Release Fluoride Agents : Fluoride varnishes with retention for

about 1 week may be regarded as slow release agents. Intra oral slow

fluoride release is provided by a device that can deliver a constant supply

of fluoride ions over a period of 2 years or by Dental materials that release

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fluoride slowly and can be repeatedly replenished with fluorides from

topical agents.

Intra oral slow release device can be either

Co polymer membrane

Fluoride glass device

Fluoride releasing dental materials: The assortment of restorative materials, sealants ,

liners and cements that contain fluoride act as slow release fluoride agents.

Eg : Restorative materials

- Silicate and glass ionomer contain large amount of fluoride

- Fluorinated amalgam has been shown to increase the fluoride in surrounding

enamel and dentil.

- Resin modified glass ionomer cements (Light and Chemically cured)

Eg : Photac - Fil , Vitremer

Compomers

Eg : Dyract , Compoglass,

Fissure Sealants

Low viscocity glass ionomer cements – Fuji III

RMGIC – Vetrebond

Fluorinatted resins – Helioseal F, Fissurit F

C) BLOCKING PLAQUE BUILDUP:

By

a) Inhibition of Glucosyltransferase(GTF) using

i) Competitive inhibition – Like analogues of sucrose that interfere with

glucan synthesis

ii) Plant and fungal products – That alter the adhesion of cell surface

glucans

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iii) Anti GTF antibodies – That reduces colonisation and accumulation of

S.mutans. Eg : Chicken antibodies in Egg. , Mouth rinse with Egg yolk

antibodies

b) Interfering with specific molecules involved in bacterial adhesion and

congregation by :

i) Soluble analogs of receptors

ii) Soluble adhesions

iii) Use of lectins

c) Use of effective antibacterial systems by –

i) Combination products – of heavy metals + antiseptics

ii) Slow release devices – Anti microbials Eg : 25% tetracycline HCl film

strips

D) CARIES VACCINE

The concept of preventing dental caries by vaccination has existed for almost as long

as dental caries has been known as infectious disease process and considerable

progress towards this goal has been accomplished during the past decades.

ACTIVE IMMUNIZATION

A variety of new approaches to active immunization against dental caries by oral and

systemic inoculation have been introduced. These include-

-synthetic streptococcus mutans peptide.

-s.mutans antigens coupled to cholera toxin subunit.

-s.mutans genes fused to avirulent salmonella.

-liposome coated delivery systems.

PASSIVE IMMUNIZATION

- topical application of monoclonal antibodies.

- immune bovine milk and whey (mouth rinse)

- egg yolk antibody.

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-Transgenic plant antibody

A) REPLACEMENT THERAPY

It is a subtle type of antibacterial treatment in which cariogenic bacteria are super

seeded by more benign counter parts.These include—

a) Since the dominant acid formed by S.mutans is lactic acid, mutation of this

organism lacking the gene responsible for lactate dehydrogenase (LDH) were

sought and propogated. Since it is difficult to be certain that only one gene is

mutated, genetic engineering techniques have been used to produce a inactivate

form of cloned LDH gene , which was then inserted in S.Mutans. chromosome to

create a known isogene.

b) An attempt to transfer an Arginine Deminase gene responsible for base

production streptococcus sanguas into S.mutans to counteract the acidogeneic

potential.

c) Transfer genes some bacteria that naturally produce enzymes such as mutanase ,

Dextranase which degrade the extra cellular sticky polymers involved in plaque

adhesion and buildup into oral bacteria such as strpeococcus gordonii.

B) MODIFYING CARIES PROMOTING INGREDIENTS OF THE DIET.

Initially dietary modification was synonymous with restricting intake of sugars

especially sucrose. This required a proper dietary assessment of each individual that

allotting them with a proper schedule dietary chart fulfilling the dietary needs. These

include

- Encouragement of sugar substitution – the use of hypo acido genic and non acido

genic Eg : Xylitol

Mechanism of action :

Enhances remineralization, decreases dental caries , alters metabolic pathways

and reduces S-mutans.

Use of preservatives with enhanced antibacterial activity

Increased use of natural inhibitors of demineralization such as various

phosphates

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Employment of protective components in food.

Eg : Polyphenols in chocolates. Protective components in Oat and pecan hulls

C) INCREASING TOOTH RESISTANCE

By :

i) Various forms of fluoride application

ii) Methods used to increase fluoride uptake

iii) Remineralizing agents – Calcium phosphates , CPP - ACP

iv) Polymeric coatings

v) Fissure sealants

vi) Laser application

vii) Disinfection therapies

These include

– Ozone therapy (Heal ozone)

– PAD (Photo Activated Disinfection) : It is a photodynamic therapy wherein

a diode laser of wavelength 635 nm is used in conjugation with a die tolonium

chloride.

– Antibacterial treatment :

Uses a step wise excavation and application of anti bacterial agents to

remineralize the lesion and sterlize the cavity.

Agents used are

Calcium hydroxide

Cements with metronidazole, Ciprofloxacin , Cefalor

Glass ionomer cements with antiseptics like chlorhexidine

Copper phosphate cements

- Minimally invasive preparations

Preventive resin restoration (PRR) Conservative resin restorations

(CAR)

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Atraumatic restorative treatment (ART)

Enameloplasty

D) AUGMENTING HOST RESISTENCE

1) By mimicking natural protective system present in human saliva – By

recombinant DNA technologies

Eg : Antibacterial – Lysozyme

Aggregating – Mucins

pH regulating – Histidine

Ionic regulation – Statherin

2) By use of artificial saliva with natural salivary molecules added to increase

their protective qualities inpatients with xerostomia

3) By adding protective pep tides to pacifiers for young children .

4) Salivary enhancement therapies

Local or topical sialogogues

Eg :

– Gustatory stimulation

– Masticatory stimulation

– Oral rinses, artificial saliva

– Anhydrous crustalline maltos

– Acupuncture

Systemic therapies Eg :

- Pilocarpine HCl i.e. 5-10 mg

- Cevimeline 30 mg

- Bromhexine , Yohimbine , Interferon

- Essential fatty acids – linoleic acid

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CONCLUSION :

The ultimate goal of any caries detecting diagnostic tool is to improve both the

sensitivity and specificity level. If disease can be detected before cavitations occurs,

preventive therapy may avoid the need for any unnecessary operatory intervention.

This would be stepping stone towards a more conservative and minimally invasive

treatment approach.

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