1. MINIMAL INTERVENTION
DENTISTRY

2. INTRODUCTION
For almost the whole of the last century, both the teaching and practice of
operative dentistry have been influenced to a very great extent by Dr. G.V
Black. His contributions to this field are numerous and were supported by
extensive studies and meticulous observations based on the scientific
knowledge available in his time. His classification of cavities is followed to
this day and most of the principles of cavity preparation taught by him are
still in use.
Black‟s principles of cavity preparation were based on the facts
about dental caries known in his time and on the dental materials available
at that time. It was believed that once caries had begun, it would continue
to progress until the tooth was lost. The concept of remineralization of early
dental caries was unknown and widespread use of various forms of fluoride
for prevention of dental caries was not as prevalent as it is today.

3. Also the few materials that were available then were all non-adhisive
and depended upon macro-retention. Therefore most of the cavity outlines
proposed by Black were wide and relied on the concept of extension for
prevention that is, extension of the cavity outline into uninvolved pits and fissures
to prevent recurrence of caries in the tooth.
This resulted in a “mechanistic” or “surgical” approach to treatment planning
rather than a “biologic” or “holistic” or “therapeutic” one.
Over the last few decades there has been extensive research in various
fields like cariology, effect of fluorides and other preventive methods in reducing
the incidence of caries and in the cements and composite resins. Also clinical
observations on the modes and patterns of failure of various, restorative
materials using conventional and conservative methods of cavity preparation
have been carried out.

4. All this has encouraged researchers and clinicians to question existing
concepts and to adopt more conservative, less destructive methods and
approaches to the treatment of dental caries.
This has ushered in an exciting new era in the practice of dentistry where
the emphasis is on prevention and remineralization of caries whenever possible
rather than blindly following the traditional “drill and fill” approach.
Extensive use of fluorides, pit and fissure sealants and diet modification
have reduced the incidence of caries. When caries is detected early enough it is
monitored and remineralization is encouraged rather than placing restorations.
Newer methods of ultraconservative, nonrotary cavity preparation like air abrasion
are being introduced. The increasing popularity of adhesion in dentistry has
reduced the need for preparing wide cavities with undercuts and unnecessary
extensions. Also repair of existing restorations. Instead of total replacement is
being advocated

5. Diet modification
Since dietary sucrose plays a major role in caries activity, modifying the diet
can be an effective means of preventing dental caries.
Diet modification is recommended to patients with active caries and those who
are at high risk for caries development. These patients should be advised to
increase their consumption of foods with anticariogenic properties.
Foods with anticariogenic effects
Milk.
Cheese.
Fibrous foods, raw vegetables and grains.
Sugar substitutes and artificial sweeteners.
Tea.

6. Anticariogenic foods are those which neutralize the acids produced by
bacteria, stimulate saliva and enhance the remineralization process.
Milk: Cow‟s milk contains lactose which is the least cariogenic of all mono
and disaccharides. It also contains calcium phosphate and casein which
prevent demineralization.
Cheese: Cheese contains casein phosphopeptides (CPP) which makes it
anticariogenic. So a cube of cheese consumed after a sugery snack reduces
demineralization.
Fibrous foods: Raw vegetables and grains have natural protective factors
like organic and inorganic phosphates, polyphenol‟s, phytates and other non-
digestible fibe‟s. They also stimulate salivary flow.

7. Sugar substitutes and artificial sweeteners: Nutritive sugar alcohols like
sorbitol, xylitol. And mannitol have an anticariogenic effect. Of these, xylitol has
a specific anticariogenic effect.
Xylitol is a recent addition to caries prevention prgrammes. It is a natural five
carbon sugar that is obtained from birch trees, oats, corn cobs, stawberries and
bananas. Patients who are at high risk for dental caries are recommended to
chew xylitol gums for 5 to 30 minutes after eating or snacking.

8. Xylitol gums- mechanisms of action
 Prevent Streptococcus mutans from binding to
sucrose.
 Increase the concentration of amino acids and
ammonia thus neutralizing the plaque acids.
Bacteriostatic effect as they are non –fermentable.
Increase salivary flow.
Enhance remineralization.

9. Artificial sweeteners like saccharin and aspartame are also non-cariogenic
Tea: Green, oolong and black teas contain fluorides and pclyphenols or flavionoids
which suppress bacterial groqth and reduce the acidogenic potential of sucrose.
Key dietary recommendations
in caries prevention
• Reduce the frequency and amount of sugary roods and drinks.
Limit these foods to mealtimes.
• Recommend diet9s high in proteins instead of sugar rich sweets
and sticky foods.
• Avoid snacks in between meals. If between meal snacking is
unavoidable, recommend foods and drinks with low caries risk or
those with anticariogenic effects.
• Encourage consumption of foods which enhance
mastication, salivary production and oral clearance at each eating
session.
• Encourage consumption of milk and water instead of sugary
acidic soft drinks

10. Salivary Stimulants
Saliva has a very important role in caries prevention due to its antiacterial,
buffering and flushing actions. In patients with xerostomia, there is an increased
risk for dental caries. For these patients, salivary stimulants like gums, paraffin
waxes or salivary substitutes can be prescribed as adjuncts to other preventive
methods. Artificial saliva with added protective agents like mucins are being
clinically tested on patients with xerostomia to check their anticariogenic potential.
Flourides
Small amounts of fluoride can increase the resistance of tooth structure to
demineralization. So fluorides are an important component of any caries
prevention program. Fluoride is an essential nutrient for humans and is required
only in very small quantities. Natural sources of fluorides in the diet include fish
like salmon and sardines, rock salt, tea leaves, potatoes, jower, and bananas.
Minerals water contains 1.5 to 7 parts per million (ppm) of fluoride depending on
the geological source.

11. The changing paradigms in modern operative dentistry and briefly discusses the
various approaches which are being currently proposed.
MODERN TRENDS
“Minimal intervention dentistry”, “minimally invasive dentistry” or “ “preservative
dentistry” is the way dentistry will be practiced in the future. Practice of dentistry
based on this philosophy depends upon the following principles:
1. Accurate caries diagnosis.
2. Classification of the severity of caries using ragiographs .
3. Assessment of individual caries risk (as low, moderate or high).
4. Disease control.
5. Remineralization of early carious lesions.
6. Reduction in cariogenic bacteria.
7. Minimal surgical intervention of cavitated lesions.
8. Repair, rather than replacement of defective restorations.
9. Follow up at periodic intervals to assess the outcome of caries management
strategies.

12. To embrace these principles and to integrate them into daily practice
requires a change in the mindset regarding caries. Caries is no longer considered a
process of irreversible demineralization of tooth structure requiring surgical removal
of the pathological tissue and replacement with a suitable restorative material it is
now accepted that caries is a demineralization process where the tooth structure
alternately loses and picks up calcium and phosphate lons depending on the
surrounding microenvironment. A drop in the pH below 5.5 can cause subsurface
demineralization and the presence of fluoride can help in remineralization.
With the introduction of technological advances like digital fiberoptic
transillumination quantitative laser fluorescence, digital radiography etc, the
diagnosis of dental caries is becoming more accurate and follow up more
predictable.

13. If evidence of demineralization is found radiographically, it is classified as
follows:
E0 = Tooth with no caries.
E1 = Caries in the outer half of enamel.
E2 = Caries in the inner half of enamel.
D1 = Caries in the outer third of dentin.
D2 = Caries in the middle third of dentin.
D3 = Caries in the inner third of dentin.
No surgical intervention is needed if subsurface demineralization is found
in enamel or in the outer third of dentin. This is because the rate of progression of
caries may be slowed down if fluoride therapy is provided or if the patient
consumes fluoridated water. Studies have shown that it can take as long as 6 to 8
years for caries to progress through enamel. Therefore, it is important to delay
operative intervention for as long as possible.

14. Xeroradiography
This technique simulates the photocopying machine. It is a technique in which
the image is recorded on an aluminium plate coated with a layer of selenium
particles. These selenium particles are given a uniform electrostatic charge and
are stored in a unit called conditioner. When X-rays are passed on to the film, it
causes selective discharge of the particles. This forms the latent image and is
converted to a positive image and is converted to a positive image by a process
called „development‟ in the processor unit . the main characteristics of xero-
radiographic technique are the ability to have both positive and negative prints
together. When positive current is applied to the film, negative are attracted and
when negative current is applied, positive particles are attracted.

15. Xeroradiography is twice as sensitive as conventional D-speed films and a
phenomenon of „Edge Enhancement‟ is possible with this technique. Edge
enhancement means differentiating areas of different densities especially at the
margins or edges.
Xeroradiography was considered to be superior as far as caries detection
was considered, but recent studies have indicated that these are comparable to E-
speed films of conventional radiography for diagnosing caries. disadvantages of
this technique are:
• The electric charge over the film, many a times, causes discomfort to the
patient since the oral cavity has a humid environment which acts as a medium
for flow of current.
• Exposure time varies, as manufacturers not indicate the exact thickness of the
plate.
•The process of development can‟t be delayed and is to be completed within 15
minutes.

16. Although Xeroradiography technique seemed to be promising. But
features of edge enhancement etc. were soon taken over by fast developing
digital imaging systems.
Digital imaging
With the advent of computers in dentistry, researchers have even utilized
computers for diagnostic purposes also e.g. in digital imaging techniques.
A digital image is an image formed and represented by a spatially
distributed set of discrete sensors and pixels. When viewed from a
distance, the image appears continuous, but closer inspection reveals
individual pixels. Digital image in simple means is an image that has been
recorded with non-film receptors. There are two types of non-film receptors
for recording digital images.

17. •The digital image receptor (DIR) which collects the X-rays directly (Direct digital
imaging).
•Video camera for forming digital images of a radiograph (Indirect digital
imaging).
Digital image receptor works on a charged couple device (CCD), which
is electronically connected, to a computer. CCD is a semiconductor made up of
metal oxides such as silicon that is coated with x-ray sensitive phosphorous.
The CCD is sensitive both to x-rays and visible light. The intraoral DIR is placed
in the mouth instead of the x-ray film. The image area is limited by the size of
the CCD present in the digital image receptor, once the image is captured by the
CCD, (like an image of silver halide crystals in an x-ray film) it can be stored in
the computer memory for image processing and can be displayed for viewing.

18.  Radio – Visio-Graphy (RVG) 19 x 28 mm
(Trophy – Japan)
 Flash Dent 20 x 24 mm
(Villa – Italy)
 Sens-A – Ray 17 x 26 mm
(Regam – Sweden)
 Vixa 18 x 24mm
 (Gendex – Italy)
Advantages
1. Darkroom is not required, instant image is viewed.
2. The quality of image is consistent.
3. Signal to noise ratio is high.
4. Greater exposure latitude.
5. Elimination of the hazards of film development.
6. Radiation dose is decreased.
7. Capability for teletransmission.

19. Disadvantages
1.High cost of system
2.The life expectancy of CCD is not fixed.
Conventional film radiographs may provide insufficient density contrast
in the area under suspicion for a carious lesion. Contrast can be enhanced by
digital mode. It has been shown that by digital mode one can enhance density
and contrast upto 70%. It has also been observed that digital method is 50%
more sensitive in detecting occlusal caries as compared to conventional films.
d) Computer image Analysis
The variation between observers in the interpretation of radiographs is well
known. Development of computers in the last few years have made it possible
to use automated procedures which are able to overcome the shortcomings of
human eye to quite a great extent. Software have been developed for
automated interpretation of digital radiographs in order to standardize image -

20. Assessment. These programs are based on the “expert system” which contains
facts about the pathologic conditions. The clinician enters the patient‟s data
and the programme compares the patient‟s data with the basic knowledge of
the pathology. This programme tells us the possible diagnosis, and even tells
the possibilities of other ailments. The system can suggest the need for
additional tests to improve the reliability of the diagnostic outcome.
Automated analysis provides sensitive and objective
observations, which may also permit the detection of small lesions that
otherwise, may not be visible to naked eyes. Various authors have described a
system that is able to recognise features of teeth in intraoral as well as
extraoral radiography. Applications have been developed to support the
interpretation of angular periodontal bone defects and to quantity carious
lesions.

21. Advantages
1. Automated analysis may provide sensitive and objective observation of smaller
lesions which otherwise are not perceptible to naked eye.
2. It is possible to monitor the lesions.
3. Quantification of small lesions is possible.
Disadvantages
1. There is always a need for standardization of exposure geometry.
2. Sensitivity is higher but specificity is lesser.
3. Time consuming and less economical.
It is too early yet to say that the computer-aided diagnosis would replace the
routine diagnosis. Much research is needed on this subject.

22. e) Subtraction Radiography
Subtraction radiography is a technique by which structured noise is
reduced in order to increase the detectability of changes in the
radiographic pattern. The structured noises are the images, which are not
of diagnostic value and interfere in routine interpretation of radiographis.
Subtraction images can be obtained from photographic, electronic and
digital methods. Presently Digital Subtraction Radiography (DSR) is being
used and popularized in every field of dentistry. Other methods have the
disadvantages such as:
i) Inability to produce correct projection geometry.
ii) Density and contrast may not be proper.
The development of Digital Subtraction Radiography has overcome many
of the Limitations of photographic images.

23. Digitization is achieved by taking a picture of the radiograph using high
quality video camera. This is fed to a computer-imaging device, termed as digitizer.
Two standardized radiographs produced with identical exposure geometry are
used. The first one is the “Reference Image” and the subsequent images are for
comparison. The reference image is displayed on the screen. Then the subsequent
images are superimposed. The difference between the original and the subsequent
images will slow as dark bright areas, which can be interpreted readily. One should
remember that digitzation does not increase the information available in the original
radiograph. Only turns the image into a form, which can be read by the computer.
It has been demonstrated that approximal carious lesions are clearly
visible by digital subtraction solution (Halse et al 1990)29. Subtraction radiography
has also been demonstrated to be superior to conventional film radiography for
detecting artificially produced recurrent caries by reducing the false positive
diagnosis. It also useful in detecting the progress of re-mineralization and de-
mineralization patterns of dentinal caries.

24. The assessment of alveolar bone height is determining the progression of
periodontal disease has been one of the major uses of subtraction digital
radiography. It is demonstrated that Digital subtraction radiography is 90 %accurate
in detecting as little as 5 % mineral loss of bone compared to the 30-60 % of the
mineral content of the bone that has to be lost before a radiographic lesion could be
seen on a conventional radiograph. The minimal thickness of bone that can be
detected under optimal conditions has been found to be 0.12 mm. For all these
observations, correct projection geometry is mandatory.
II. Electrical resistance
Sound tooth enamel is a good electrical insulator due to its high inorganic content.
Caries/enamel demineralization results in increased porosity. Saliva fills these pores
and forms conductive pathways for electric current. The electric conductivity is
hence directly proportional to the amount of demineralisation that has occurred.
Electrical resistance is measuring the electrical conductivity through these pores.
An instrument called „Van Guard electronic caries detector‟ has been
designed to measure the electrical conductivity of the tooth. The diagrammatic
version is shown in Fig. 4.9. The electrical conductivity is expressed numerically on
a scale from 0-9, indicating a change from sound tooth to an increased degree of
demineralization. Various studies have confirmed the validity of this test.

25. Advantages
• Very effective in detecting early pit and fissure caries.
• It can monitor the progress of caries during caries control programme.
Disadvantages
• It can only recognise demineralization and not caries specifically. The
hypomineralization areas, may be of developmental origin or carious origin will
give similar type of readings.
• Presence of enamel cracks may lead to false positive diagnosis.
• A sharp metal explorer is utilized which is pressed into the fissure causing
traumatic defects.
• Separate measurements are required for different sites making full mouth
examination quite time consuming.
A modified form of the instrument „Electronic caries Monitor‟ not only
detects caries at a single point on tooth but also can screen whole of the occlusal
surface for caries by covering the surface with a conducting medium before placing
probe tip.

26. III. Fibre Optic Trans IIIumination (FOTI)
Fibre Optic Trans IIIumination (FOTI) works under the principle that since a
carious lesion has a lowered index of light transmission, an area of caries
appears as a darkened shadow that follows the spread of decay through the
dentine. Fibre Optic Trans IIIumination was initially designed for the detection of
proximal caries. (Friedman and Marcus, 1970)25.
Fiberoptic consists of a halogen lamp and a rheostat to produce a light
of variable intensity. The 150-watt lamp generates a maximum light intensity of
4000 lx at the end of 2 mm diameter cable. Two attachments are used; a plane
mouth mirror mounted on a steel cuff and a fiberoptic probe of 0.5 mm diameter
so that it can be placed in the embrasure region. It produces a narrow beam of
light for transillumination. The reheostat is set to give a light of maximum intensity.
For examination, the tip of the probe is placed in the embrasure immediately
beneath the contact point of the proxmial surface to be examined either on the
buccal or lingual surface depending on the tooth. The marginal ridge is viewed
from the occlusal surface.
A shadow extending to the dentino-enamel junction beneath marginal
ridge may be evident if there is a break in the integrity of the enamel of marginal
ridge.

27. Advantages
• No hazards of radiations.
• Simple and comfortable for the patients.
• Lesions, which cannot be diagnosed radiographically, can be diagnosed by
this method.
• Not time consuming.
Disadvantages
• Permanent records are difficult to maintain as can be kept in radiographs.
• It is subjected to intra and inter observer variations.
• Difficult to locate the probe in certain areas.
IV. Laser Auto Fluorescence (LAF)
In this, visible light has been used as the light source for the detection of smooth
surface and fissure caries at an early stage (Bejlkagen et al., 1982)8. The tooth is
illuminated with a broad beam of blue green light of 488 nm wavelengths from an
argon ion laser and the fluorescence observed in the 540 nm range. This
fluorescence of enamel occuring in the yellow region (540 nm) is observed
through a yellow high pass filter to exclude the tooth scattered blue light.

28. Demineralized areas appear dark in this region. Healthy tooth fluoresces
differently from that of carious tissue impregnated with fluorescent dyes.
Demineralized tissues absorb dyes like Fluorol TGA, Sodium fluorescein etc
and fluoresce strongly. This is referred to as dye enhanced lased
fluorescence.
Recently, a quantified version of laser fluorescence has been developed and
tested successfully. In this technique a micro camera is used to capture the
real image. A computer screen displays the real images of the teeth under
examination.
Advantages
• It is convenient and a relatively fast method.
• Carious lesions can be detected and their mineral loss measure. Natural
lesions with a diameter of less than 1mm and a depth of 5-10mm have been
detected and measured with this technique.
• Preventive measures can be evaluated.
• It is suitable for quantifying mineral loss around different restorations.

29. V. Ultraviolet illumination
Ultraviolet light (UV) has been used to increase the optical contrast between the
carious region and the surrounding sound tissue. The natural fluorescence of tooth
enamel, as seen under UV light illumination is decreased in areas of less mineral
content such as in carious lesions, artificial demineralization or development
defects. The carious lesions appears as a dark spot against a fluorescent
background.
Advantage
• It is a more sensitive method than the visualtactile method.
Disadvantages
• The specificity is a problem between the carious lesions and the development
defect.
• Still this method has not been developed into a quantitative method.
VI. Endoscope/Videoscope
Endoscopic technique is based on observing the fluorescence that occurs when
tooth is illuminated with blue light in the wavelength range of 400-500 nm.
Difference is seen in the fluorescence of sound enamel and carious enamel. When
this fluoresced tooth is viewed through a specific broadband gelatine filter, white
spot lesions appear darker than enamel.

30. Similarly a white light source can be connected to an endoscope by a
fiberoptic cable so that the teeth can be viewed without a filter. This technique is
referred to as white light endoscopy.
It has been demonstrated in vitro that this technique allows visualization of
small carious lesions in the enamel that are difficult to detect with the naked eye or
with radiographs. The clinical detection of small carious lesions would greatly
facilitate the preventive management of lesions in vivo because „early‟ lesions have
the potential to remineralize and the remineralized lesions are more resistant to
subsequent attack than the adjacent sound enamel.
Additionally, a camera can be used to store the image. The integration of
the camera with the endoscope is called a videoscope. A miniature colour video
camera is mounted in a custom-made metal mirror holder. This is designed in such
a way that the image of the surface of enamel can be viewed by expert
independent examiners who had also examined the teeth visually and by
conventional methods.
Advantages
• It provides a magnified image.
• Clinically feasible.

31. Disadvantages
• Requires meticulous drying and isolation of teeth.
• Time consuming.
• Very costly.
VII. Ultrasonic imaging
Ultrasonic imaging was introduced for detecting early carious lesions in smooth
surfaces. The demineralisation of natural enamel is assessed by ultrasound pulse
echo technique. It is observed that there is a definite correlation between the
mineral content of the body of the lesion and the relative echo amplitude
changes.
The ultrasonic probe is used which sends longitudinal waves to the
surface of the tooth and also serves the function of receiving the waves. Initial
white spot lesions, which extend only upto enamel, produce no or weak surface
echoes. The sites with visible cavitation produce echoes with substantially higher
amplitude. The method, if improved, can be a realistic alternative to radiographic
diagnosis of caries on the approximal surfaces. It is also more sensitive than
visua-tactile method, however it is not a quantitative method.

32. VIII. Dye Penetration Method
Dyes have a widespread use in dentistry. Dyes can visualise a subject from its
routine background or if several objects have a similar appearance, colouring by a
dye may discriminate between them and allow identification. The observation of
the colouring can be qualitative or quantitative. For a qualitative assessment, it is
sufficient to observe for colour or differentiate coloured objects from the non
coloured ones.
Dyes such as basic fuschin is used.

33. The focus should be on preservation of enamel and dentin, even in the event of
demineralizatin as long as cavitation has not occurred.
Attempts are made to first control caries progression, assess the caries risk
status of the individual and monitor evidence of remineralizatin of initial lessions. If
such an attempt which focuses on infection control rather than placement of
restorations is adopted, it results in at least a 50 % reduction in restoration
placement.
After all attemps have been made to shift a patient from the high risk to low
risk group, only then should surgical intervention be made, that is, cavity preparation
and restoration. This is necessary if there is frank cavitation, patient
discomfort, unacceptable form, function or esthetic

34. RESTORATIVE OPTIONS
Once surgical intervention is deemed necessary three factors determine the
future course of action:
1. The use of adhesive restorative materials.
2. Ultraconservative cavity preparation techniques and outlines.
3. Repair instead of replacement of defective old restorations.

35. 1. Adhesive restorative materials
a. Glass ionomer cements: In the context of minimally invasive dentistry, glass
ionomer cements possess two desirable properties adhesion to tooth structure
and release of fluoride.
Glass ionomer cements being water based are relatively brittle materials.
Therefore their use is limited to fissure sealing, cevical restorations, proximal
cavities in anterior teeth and for restorations in the deciduous dentition. It can
also be used as a long term intermediate restoration in extensive cavities to
arrest the progress of demineralization.

36. b. Composite resins: Bonding of composite resins enamel is now in practice of
the least over three decades and is a well established procedure.
Bonding to dentin however was the weak link until Fusayama developed the total
etch concept and Nakabayashi proposed the concept of hybrid layer formation.
At present, the effectiveness of a suitable hydrophilic monomer as a primer before
using the adhesive has been proved beyond doubt and is a well accepted
procedure.
This has opened up previously unthought of techniques and ultraconservative
cavity preparations which will go a long way in preserving the structural integrity of
teeth thereby reducing the need for frequent replacement of old restorations.

37. 2. Cavity preparation
For patients in a high caries risk group, sealing pits and fissures in recently erupted
teeth which demonstrate a highly convoluted fissure system will greatly reduce risk
of developing caries in future.
Once cavitations has occurred, surgical intervention is necessary as
plaque control becomes impossible. At this point, it becomes important to
reconsider standard cavity preparation procedures.
As emphasis is being placed on caries preventive methods and the use of
adhesive materials, the approach to cavity preparation should also be conservative.
It is necessary to prepare cavities only to gain access to the caries, to remove
infected and degraded enamel and dentin. Slightly undermined enamel may be left
behind to be supported by the restoration and adjacent uninvolved fissures can be
sealed without unnecessary widening. Therefore the approach shifts from the
previously taught “extension for prevention” to “prevention of extension”. This
preserves as much original tooth structure as possible.

38. For proximal cavities in posterior teeth, various new approaches are being
investigate like “tunnel” preparation; which preserve the marginal ridge above the
carious lesion. If the proximal lesion is close to the marginal ridge, “slot” or
“minibox” preparations are being advocated without involving the occlusar surface.

39. Minimal cavity preparation techniques – The desire for preparing smaller
dimension, microcavities has stimulated several minimal preparation
techniques utilizing newer technologies like:
Air abrasion
Song abrasion.
Chemomechanical
Lasers.

40. Air Abrasion: Dental Health Without the Drill
Air abrasion is a drill-less technique that is being used by some dentists to remove tooth
decay and for other applications.
How Does Air Abrasion Work?
During air abrasion, an instrument that works like a mini sandblaster is used to spray
away decay. During air abrasion, a fine stream of particles is aimed at the decayed
portion of the tooth. These particles are made of silica, aluminum oxide, or a baking
soda mixture and are propelled toward the tooth surface by compressed air or a gas that
runs through the dental handpiece. Small particles of decay on the tooth surface are
removed as the stream of particles strikes them. The particles of decay are then
"suctioned" away.
Is Air Abrasion Safe?
Yes, air abrasion is safe. The only precautions needed before air abrasion are protective
eye wear (to prevent eye irritation from the spray) and the use of a rubber dam (a rubber
sheet that fits around teeth) or protective resin applied to nearby teeth and gums to
protect areas of the mouth that aren't being treated. The suctioning of particles also
prevents them from being breathed into the lungs.

42. What Are the Advantages of Air Abrasion?
Compared with the traditional drilling method, the advantages of air abrasion are many and
include the following:
Air abrasion generates no heat, sound, pressure, or vibration.
Air abrasion reduces the need for anesthesia, particularly if the cavity is shallow.
Air abrasion leaves much more of the healthy tooth tissue behind.
Air abrasion leaves the working area relatively dry, which is an advantage during the
placement of composite fillings.
Air abrasion reduces the risk of microfracturing and chipping of the tooth, which some
experts believe can lead to premature restorative failures.
Air abrasion allows the dentist to treat multiple sites in the mouth during a single visit.
The procedure is relatively simple and quick.

43. What Are the Disadvantages?
Air abrasion is not necessarily totally painless. The air can cause sensitivity and so
can the abrasives used.
Air abrasion is not recommended for deep cavities (those close to the tooth's pulp). It
is best suited for removing small cavities that form early on the surface of teeth.
Only composite filling material can be used following air abrasion because it adheres
well to the smooth surface created by the air abrasion (amalgam or silver fillings
require drill-based cuts to prevent the filling from falling out).
Who Are the Best Candidates for Air Abrasion Procedures?
Air abrasion is ideal for use in children and others who are fearful and have minimal
decay.
What Other Types of Procedures Are Performed With Air Abrasion?
Air abrasion can also be used to:
Remove some old composite restorations, but not metallic restorations such as silver
amalgam fillings
Prepare a tooth surface for bonding or sealants
Remove superficial stains and tooth discolorations

44. 3. Repair of defective restorations.
An embrrassingly high percentage of restorations require eventual
replacement. Invariably the outline of the next restoration is more extensive. This
sets off a “restorative cycle” where larger and larger restorations are placed till the
tooth requires endodontic treatment or extractions.
This approach should be discouraged and repair rather than replacement of
old restorations. Should be take up. This, however, is not well accepted by the
profession as it is considered “patchwork” dentistry and a departure from traditional
teaching. In the interest of long-term preservation however,repair of defective
restorations should be taken up as long as it does not compromise of the new and
old parts of the restoration.

45. As this approach is fairly new it is still difficult to lay down definite guidelines
regarding which restorations can be safely repaired and which require
replacement. When repair of an existing restoration is being considered the
patient‟s risk for caries, professional judgement regarding the risk versus
benefits and conservative principle should be taken into account

46. .
CONCLUSION
Minimal intervention techniques cause less tooth destruction than
conventional techniques, thus increasing the long-term survival of teeth. This
approach is intended to diagnose dental defects, mainly caries, early so that the
treatment options can combine a preventive philosophy, remineralization of early
lesions and minimal intervention for the materials, scientific background and
technology for the adoption o this approach are with us today and it is upto
practitioners and leachers to translate these concepts into everyday clinical use.