Recent Advances In Caries Diagnosis Corrected Today

RECENT ADVANCES IN CARIES DIAGNOSIS & PREVENTION INTRODUCTION DIAGNOSTIC TOOLS ♦ ♦ ♦ ♦

VISUAL TACTILE VISUAL TACTILE RADIOGRAPHS

- Conventional – IOPAR & Bitewing - Xeroradiography - Digital – 1. Enhancement 2. Subtraction 3. Tuned Aperture Computed Tomography (TACT)

♦ BASED ON VISIBLE LIGHT Optical caries monitor (OCM) FOTI and DIFOTI QLF & DIAGNODENT, DELF Ultraviolet ♦ BASED ON ELECTRICAL CURRENT Electric conductance Electric Impedence ♦ ULTRASOUND ♦ ENDOSCOPY, Videoscope ♦ DYES – Enamel & Dentin NEWER TECHNOLOGIES: 1. Terahertz 2. Multi-photon Imaging 3. Optical coherence tomography 4. Infrared fluorescence 5. Infrared thermography

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CARIES PREVENTION ♦ Current Strategies 1. 2. 3. 4.

Combating microorganisms Diet modification Increasing tooth resistance 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 3

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

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• FOTI & DIFOTI • 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) Criteria for visual examination

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0 1

No or slight change in enamel transparency after prolonged drying Opacity or discoloration hardly visible on wet surface but distinct

2 3

on air drying Opacity distinctly visible without air drying Localized breakdown in opaque or discolored enamel and gray

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discoloration of dentin 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 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.

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

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

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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. -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.

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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. Voltages from each pixels are sampled and assigned a numerical value on the gray scale. Pixel size varies from 20-70%

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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

-Advantages ♦ Instant image, no dark room, Consistent image ♦ Eliminates hazards of film development 11

♦ 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 called a psedohologram. TACT slices and pseudohologram are adequately detect primary and secondary caries.

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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. c) Quantitative Laser or Light Induced Fluorescence (Laser Auto Fluorescence ) : The use of Fluorescence for detection of caries dates back 13

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 > 35 advanced dentinal lesion.

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

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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 18

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. 19

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 demineralization 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 premolars. 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. 23

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+.

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But 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%)

}10 ml solution for 1 min

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 Cu 2+ 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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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. : 27

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 Flchewed 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 :-

2)



Neutral sodium fluoride 2% (1% F)



Stannous fluoride 8% (2% F)



Acidulated phosphate fluoride (1.23% F)

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  Employment of protective components in food.

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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) ♦ Atraumatic restorative treatment (ART) 34

♦ 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 α

-

Essential fatty acids – linoleic acid

CONCLUSION :

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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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