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Diagnostic aid

Advanced Diagnostic Aids in Periodontology and Oral Surgery; Probes, Bacterial Culture, Phase Contrast Microscopy, DNA-DNA hbridization Technique, Latest Radiographic Techniques

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Diagnostic aid

  1. 1. Introduction  Periodontal diseases are prevalence human diseases defined by signs and symptoms of gingival inflammation and/or periodontal tissue destruction.  These diseases are conventionally diagnosed by clinical evaluation of the signs of inflammation in the gingiva without tissue destruction in case of gingivitis  Or by presence of both inflammation and tissue destruction in case of periodontitis  Routinely used clinical and radiographic evaluation can provide evidence of past periodontal destruction and its extent and severity  But they do not provide any information on the cause of the condition, on the patients susceptibility to disease or whether the disease is progressing or in remission  Periodontitis is a multifactorial disease and is caused by the interplay of several factors such as periodontal pathogens, host response, genetic, systemic and behavioral risk factors  Considering this in addition to clinical and radiographic parameters several advances have been made that aid in the diagnosis of PDL diseases Diagnosis
  2. 2.  A periodontal diagnosis is an important label that clinicians place of a patient’s periodontal condition or disease  It is derived from information obtained from the patients medical and dental histories combined with findings from a thorough oral examination  Under the best of circumstances a periodontal diagnosis is a clinicians best guess as to what condition or disease the patient has  When a diagnosis is given it is implicated that the patient has ruled out other possible diseases  But because there is always some uncertainty, clinicians routinely provide a differential diagnosis that provides the clinician with other diagnostic. Options, the initial diagnosis is wrong Components  A basic periodontal examination should consist of a. History and chief complaint b. The initial periodontal examination c. Occlusal relationships are inspected that consists of recognition of gingival inflammation  The four most common signs of gingival inflammation that are routinely observed are a. Redness b. Swelling
  3. 3. c. Bleeding on probing d. Purulent exudate  Detection of departures from normal anatomy, shape and form such as aberrant frenal attachments, reduced width of keratinized gingiva  Assessment of etiologic and predisposing facial such as local factors, close roots, palato gingival grows furcation anatomy, cervical enamel projection etc.,  Assessment of periodontal damage  This should include measurement of PPD – gingival margin to the base of the pocket recorded at 6 sites for all teeth  Clinical attachment loss from CEJ to base of pocket  RAC from apical margin of a restoration or from incisal edge of the tooth  Gingival recession – CEJ to gingival margin  Furcation involvement a. I – Incipient b. II – Cul-de-sac c. III – through and through  Mobility  Inspection of teeth for caries, restoration problems, occlusal discrepancies etc.,  Despite our increased understanding of the etiology and pathogenesis of periodontal infections, the diagnosis and
  4. 4. classification of these diseases are still based on traditional diagnostic methods.  Most important among which are a. Periodontal probing that measures PPD, CAL & bleeding b. Mobility c. Detection and assessment of local factors Evaluation of a diagnostic test / aid  The validity of a diagnostic / prognostic test can be estimated  This involves the use of a two-by-two contingency table or decision matrix  A diagnostic aid / test is intended to detect the presence of a specified disease from a single examination  To evaluate a test, data is collected using cross-sectional sampling  The validity of any diagnostic test or aid can be estimated by several measures namely a. Sensitivity b. Specificity c. Positive predictive value d. Negative predictive value Sensitivity – it refers to the probability of the test being positive when the disease is truly present
  5. 5.  A perfect test should be able to detect the disease in all cases without registering a false negative  The sensitivity of such a perfect test would be 1.00.  Specificity – this refers to the probability of the test being negative when the disease is not present  A perfect test would be able to correctly identify all instances in that the disease was absence without registering a false positive  The specificity of such a perfect test would be 1.00.  However, a perfect diagnostic test does not exist, therefore a test sensitivity and specificity will always be less than 1.00.  But it is reasonable to expect that a clinically useful diagnostic test for periodontal disease should have high values for both sensitivity and specificity  Sensitivity and Specificity are calculated in disease or healthy individuals and not in mixed population  On the other hand predictive values are calculated in mixed populations  Positive predictive value – of a test refers to the probability that the disease is present when the test is positive.  Negative predictive value refers to the probability that the disease is absent when the test is negative. Sensitivity = A / A + B
  6. 6. Specificity = D / C + D Positive predictive value = A / A + C Negative predictive value = D / B + D Advantages in traditional diagnostic methods Gingival temperature  Normal subgingival temperature falls between a range of 33.9 ± 0.40 C  Instruments that measure the temperature in the gingival tissues have been developed  Kung et al claim that thermal probes are sensitive diagnostic devices for measuring early inflammatory changes in the gingival tissues  Studies have shown that active periodontitis lesions can create measurable elevations in sulcular temperatures  One of the commercially available system is the periotemp probe (Abiodent, Inc, Danvers Mass)  It detects pocket temperature changes of 0.10 C from a referenced subgingival temperature  A naturally occurring temperature gradient exists between maxillary and mandibular teeth and between posterior and anterior teeth  Haffajee et al have shown that maxillary periodontal sites exhibit higher temperature than mandibular sites
  7. 7. with those expected for each tooth and higher temperature pockets are signaled with a red emitting diode  Haffajee et al used this probe to asses its predictability in identifying loss of attachment concluding that sites with a red temperature indication had more than twice the risk for future attachment loss than did those with a green indication  However the influence of pocket depth on temperature is still not clear and so the ability and accuracy of this device need further studies Periodontal probing  The periodontal probe is the most widely used diagnostic tool for the clinical assessment of connective tissue destruction in periodontitis  Increased probing depth and loss of clinical attachment are pathogenic for periodotitis  Pocket probing is a crucial procedure not only for diagnosing periodontitis but also to evaluate the outcome of periodontal therapy  However use of periodontal probes present problems in terms of sensitivity and reproducibility of the measurements  Clinical pocket depth readings do not normally coincide with the histologic pocket depth, since the probe
  8. 8. normally penetrates the coronal level of the junctional epithelium.  Also the precise location of the probe depends on the degree of inflammation of the underlying connective tissues  If tissue is inflamed it offers less resistances to probe penetration and the probe tip either coincides with or is apical to the coronal level of the connective tissue attachment  On the other hand healed gingival following therapy shows increased resistance to probing  Also the probing technique, probing force, size of the probe, angle of insertion of the probe and precision of the probe calibration  All these factors contributes to the large standard deviations (00.5 to 1.3mm) in clinical probing results that makes detection of small changes difficult  One of the main problems in reproducibility has been the variation in probing force  Therefore pressure – sensitive probes with standardized controlled insertion pressure have been developed  Mombelli et al – studies have shown that penetration of the probe positively correlated with probing force  These studies have shown that with forces up to 30g, the tip of the probe seems to remain within the junctional
  9. 9. epithelium and forces of up to 50g are necessary to diagnose periodontal osseous defects  Standardization of probe tips and use of registration stents to maintain reproducible probing angulation have also been used to overcome sources of error  But again fabrication of stents is time consuming and is impractical for clinical diagnosis  Also current techniques for data readont and storage are inaccurate and time consuming  New probing systems have been developed  Currently computers are routinely used in many dental offices only for billing and accounting  But there is enormous potential for the use of computers in data collections  One such use is the development of antomated probes  They fulfill the 9 criteria of the NIDCK by having a a. Precision – 0.1mm b. Range – 10mm c. Probing force – constant and standardized d. Applicability – non invasive, light out, easy to use e. Reach – easy to access any location f. Angulation – guidance system to ensure probes angulation g. Security - Complete sterilization of all portions entering the mouth
  10. 10. - No biohazard from material / electric shock h. Read out – digital electronic read out i. Recorded – digital output  After a National Institute of Craniofacial Research (NIDCR) workshop on the quantitative evaluation of periodontal diseases by physical measurement techniques there was a proposal to develop and clinically evaluate an improved periodontal pocket depth – attachment level measurement system that would meet the 9 criteria of conventional a. Precision – 1mm b. Range – 12mm c. Probing force – not standardized d. Applicability – non invasive and easy to use e. Reach – easy to access any location f. Angulation – subjective g. Security – simple stain steel instrument easily sterilizable h. Read out – on voice read out i. Recorded – in writing  Gene I – conventional probe  Gene II – pressure sensitive probe  Gene III – computerized  Gene IV – probes that aim at recording sequential probing positions along the gingival sulcus
  11. 11.  Gene V – have an ultrasonic device attached to the fourth gene probe for identifying attachment level without penetrating it  The NIDCR criteria were met by Gibbes et al who developed the Florida probe in 1988 system  Components of this system include a probe hand piece, digital read out, 3 pedal foot switch and computer interface  The hand piece probe tips are manufactured by micro polishing techniques and are 0.4mm in diameter and made of implant grade titanium  Can be steam sterilized in a standard autoclave  The 3 pedal foot switch helps a single operator enter data and eliminates error in visual reading and reduces contamination  The computer interface has color coded digital read outs and educates and motivates patients  Two models available  Stent model has a 1mm metal collar that rests on a prepared ledge on a prefabricated vasccuoform sleit  Disc model has a 1mm desk that rests on the occlusal or incisal surface of tooth  Jeffcoat probes (1986) automatically extend and retract under controlled force. Probe motion provided by custom low friction pneumatic cylinder  It can detect the CEJ by a rapid change in acceleration
  12. 12.  Working end of probe has Michigan O probe markings  Internal moving tip is Teflon coated stainless steel wire  It is circular in cross section and 0.15mm in diameter  Birek probe works under constant air pressure and measures attachment level using occlusal surface as reference  Toronto probes use occusal incisal surfaces as reference  Sulcus probes with 0.5mm Ni-Ti wire under air pressure  Mercury tilt sensor limits angulation with in 300 .  Interprobe (Goodson and Kondon, 1988) electronic probe using an optical encoder transduction element Merits  Controlling insertion forces  Automated entering of clinical information into a computer  Better resolution than manual probes, therefore detects smaller changes in CAL  Eliminates need for second operator Demerits  Tendency to underreslinate PD and CAL in untreated patients  Presence of subgingival calculus can interfere with probe insertion
  13. 13.  To minimize this problem the ‘double – pass’ method is used (measuring each site twice). Mobility  Periotest is a electronic device designed to perform quantization measurements of the damping characteristics of the periodontium, thereby establishing a value for tooth mobility  Mobility is measured as a function of the contact time of a small plug containing an accelerometer that is used to strike a tooth  The possible range of values are from –8 to +50 Merits  More reliable test of mobility Demerits  Lack of resolution  Poor sensitivity  Susceptibility to operator variables –08 to + 09  no mobility; +10 to +19  just discernible monometer; +20 to +29  obvious movement (visible); +30 to +50  mobile on pressure Calculus detection
  14. 14.  Detector is a table top electronic devices to detect calculus  Consists of a micro processor based power unit, electronic probe and foot pedal  Dimensions of the probe tip similar to standard PDL probe  Probe tip emits light from a light emitting diode  Reflected light is analyzed by the microprocessor  When calculus is detected the system light up and a beep is heard Merits  Light weight, well balanced, hand piece  Audible beep makes it easy to detect  Autoclavable probes Demerits  Expensive  Low sensitivity and specific Advances in radiographic assessment  Dental radiographs are routinely used to assess destruction of alveolar bone associated with periodontitis  They cannot accurately reflect bone morphology buccally and lingually  But they provide useful information on interproximal bone levels
  15. 15.  They also provide useful information regarding the periodontium such as a. Root length b. Root proximity c. Presence of periapical lesions d. Estimates of remaining alveolar bone  For bone loss to be detected in radiographs a substantial volume of bone must be lost  Approximately more than 30%  Therefore conventional radiographs are very specific but lack sensitivity  This low degree of sensitivity is mainly due to inherent sources of variability in radiographic technique such as a. Variations in projection geometry b. Variations in contrast and density due to differences in film processing, voltage and exposure time c. Masking of osseous changes by other anatomic structure  Variations in projection geometry can be minimized by using the paralleling cone techniques Digital radiography  Digital radiography uses computerized images that can be stored, manipulated and corrected for under and over exposure
  16. 16.  Two digital radiography systems are available that rely on a sensor  Direct and indirect methods  Direct method uses a charge coupled device (CCD) sensor linked with a fiber optic or other wire to the computer system  This direct method obtains real – time imaging, offering both clinician and patient improved visualization  The indirect method (Digera system) makes use of a phosphor luminescence plate that is a flexible film like radiations energy sensor placed intraorally and exposed to conventional x-ray tubes  A laser scanner reads the exposed plates offline and reveals digital image data that can be enhanced, stored and compared with previous images Advantages  Images can be stored, manipulated and corrected for under and over exposures  Very important dose reduction obtained with this technique (1/3 to 1/3 of dose)  Real time images obtained  With the indirect method these plate size and increase flexibility that is sinutar to conventional x-rays. So a paralleling cone techniques can be used with film holders  Patient can also see images patient education component
  17. 17. Disadvantages  With direct method the sensory area is limited therefore only one or two teeth can be depicted at a time  Also sensor rigidity that is attached to a wire makes ideal image projection with film holders difficult  Also sterilization poses a problem Subtraction radiography  This technique relies on the conversion of serial radiographs into digital images  These serially obtained digital images can then be superimposed and the resultant composite can be viewed on a video screen  Changes in the density or volume of bone can be detected as lighter areas that indicate bone gain or dark areas that indicate bone loss  Quantitative changes in comparison with the baseline images can be detected using an algorithm for gray scale levels  This is achieved by using a computer and is called computer assisted subtraction radiography  This technique requires a parallelization technique to obtain a standardized geometry and accurate super- imposable radiographs
  18. 18.  Radiographs taken with identical exposure geometry can then be scanned and superimposition of radiographs can show differences in relative densities Advantages  High degree of correlation between alveolar bone changes and attachment level changes  Increase detects ability of small osseous lesions. Grondahl et al showed a nearly perfect accuracy at a lesion depth corresponding to 0.49mm of compact bone but for conventional radiographs the lesion must be 3 times larger than that.  High degree of sensitivity it can detect a change in bone mass as little as 5%  Facilitates both qualitatives and quantitative visualization of even minor density changes in bone by removing unchanged anatomic structures from the image. This shows bone structures with true density change Disadvantages  Identical projection geometry for the sequential radiographs  Makes method very impractical in a clinical setting  Recently diagnostic subtraction radiography (DSR) has been introduced that corrects for the effects of angular alignment discrepancies
  19. 19. CADIA  It is a video based technique  A video camera measures the light transmitted through a radiograph and the signals from the camera are connected into gray scale images  The camera is interfaces an image processor and a computer that allows storage and manipulation Advantages  It can follow density changes in alveolar bone over time  It has higher sensitivity than DSR  High degree of reproducibility and accuracy Computed tomography  Specialized radiographic technique that allows visualization of planes or slices of interest  Unlike conventional tomography that bluss all structure not in the place of interest, computer tomo actually removes the structures not in the plane of interest that gives us an image with a clear visualization of the slice through the organ under study  A CT scanner is used for this purpose Disadvantages  CT equipment is expensive
  20. 20.  Procedure carries a relatively high radiation burden for the patient  Mostly used to assess sites planned to receive dental implants Nuclear medicine bone scan’s  Nuclear medicine is the branch of radiology that uses radiolabelled pharmacentraical that are specifically intended to image particular organs or detect specific disease processes  The radiopharmacentrical is in effect, a magic bullet that is taken up selectively by the tissue of interest  Routinely used to image the brain, bone, kidneys, heart, liver, lungs etc.,  For the diagnosis of periodontal disease, bone scans have been used to detect sites of active bone loss  The radiopharmacentrical is a techniquim labeled disphosphate called 99m – TC – methylene disphosphonate  The disphosphonate moiety is the bone seeker that is adsorbed onto the forming front of bone that occurs either during bone apposition or behind the bone resorption  Bone scans do not image the anatomy of the area of interest but they detect changes in bone metabolism that may occur prior to radiographically detectable changes
  21. 21. To perform a bone scan  The radio pharma is infected I.V  Following a period of 2 hours to allow for bony uptake of the agent, uptake is alter imaged using a gamma camera or measured using special detection  Areas of active bone loss appear as hot spots in the image  It has a sensitivity and specificity of 90% in prognosticating alveolar bone loss due to periodontitis  Measurement of bone seeking radiopharmacentical uptake (BSRU) would be indications of bone loss occurring at the time of examination  A miniature hand held BSRU detector was designed by Kaplan et al  It could measure the BSRU around individual teeth  Jeffcoat et al showed that a tooth with a high BSRU at time zero lost significant bone radiographically, whereas a tooth with a low BSRU lost little bone.