diagnosis

Conventional diagnostic methods of periodontal diseases:

Clinical evaluation of signs of inflammation (change in color. Swelling)
Measurement of connective tissue attachment loss by periodontal probing.
Measurement of alveolar bone loss by radiograph.
Limitation of conventional methods:
They will not provide information regarding:
Cause of condition,
Patient susceptibility to diseases,
Whether the disease is progressing or remission,
Whether the response to therapy will be positive or negative.

Advance in clinical diagnosis:

A.1. Gingival bleeding:
- There may be underlying structural alterations without corresponding clinical signs (such as change in color or texture)
- The use of gingival bleeding is more objective, since color changes require a subjective estimation.
- Gingival bleeding is a good indicator of the presence of an inflammatory lesion in the connective tissue at the base of the sulcus and that the severity of bleeding increases with an increase in size of the inflammatory infiltrate.

A.2. Gingival temperature:

- Thermal probes are sensitive diagnostic devices for measuring early inflammatory changes in the gingival tissues.
- Active periodontitis lesions can create measurable elevations in sulcular temperature.
- The PerioTemp® probe is one of commercially available, which detects pocket temperature differences of 0.1° C from a referenced subgingival temperature.
- A naturally occurring temperature gradient exists between maxillary and mandibular teeth and between posterior and anterior teeth.
periotemp


A.3. Periodontal probing:
- Limitation of conventional periodontal probing:
the probe normally penetrates the coronal level of the junctional epithelium and the precise location of the probe tip depends on the degree of inflammation of the underlying connective tissues
The difference between measurements also depends on the probing technique, probing force, size of the probe, angle of insertion of the probe, and precision of the probe calibration.
All these factors make detection of small changes difficult, and some of these problems have been overcome by:
Development of pressure-sensitive probes, which have a standardized controlled insertion pressures (with forces of up to 30 g, the tip of the probe seems to remain within the junctional epithelium , 4 and forces of up to 50 g are necessary to diagnose periodontal osseous defects)
Standardization of probe tips (less than 1 mm)
Use of registration stents to maintain reproducible probing angulation; However, fabrication of stents is time consuming and impractical for clinical diagnosis.
Florida Probe System is an automated probe system consists of a probe hand-piece, digital readout, foot switch, computer interface, and computer with end tip of 0.4 mm in diameter.
But such probe lack tactile sensitivity. Also the use of a fixed force setting throughout the mouth, regardless of the site or inflammatory status, may generate inaccurate measurements or patient discomfort, In addition to underestimation of deep probing depths pockets.

Radiographic assessment:

B.1. Conventional radiographs:
It is very specific, but lack sensitivity because more than 30% of the bone mass at the alveolar crest must be lost for a change in bone height to be recognized on radiographs.
This low degree of sensitivity is mainly due:
variations in projection geometry;
variations in contrast and density due to differences in film processing, voltage and exposure time;
Masking of osseous changes by other anatomic structures.
The solution for such problems are:
variations in projection geometry reduced by the use of well-standardized long cone parallel radiographic techniques
To standardize the radiographic assessment, radiographs should be obtained in a constant and reproducible plane, using film holders with a template containing some kind of impression material, which is placed in a constant position on a group of teeth, and an extension arm that can be precisely attached to both the film holder and the x-ray tube.


Radiographic parallel technique

B.2. Digital radiography:

It enables the use of computerized images, which can be stored, manipulated, and corrected for under- and over exposures. Also there is an important dose reduction obtained with this technique (between 1/3 to 1/2 of dose reduction compared with conventional radiographs).
Digital Radiographic System

B.3. Subtraction Radiography:

It relies on the conversion of serial radiographs into digital images. Which are superimposed and the resultant composite viewed on a video screen. Changes in the density and/or volume of bone can be detected as lighter areas (bone gain) or dark areas (bone loss). It requires a parallelization technique to obtain a standardized geometry and accurate super imposable radiographs. This technique has:
A high degree of correlation between changes in alveolar bone determined by it and attachment level changes in periodontal patients after therapy.
Increased detection ability of small osseous lesions compared with the conventional radiographs from which the subtraction images are produced.
B.4. Computer-Assisted Densitometric Image Analysis System (CADIA):
It is a video-based analysis system where a video camera measures the light transmitted through a radiograph, and the signals from the camera are converted into gray-scale images. It offer a method for assessing alveolar bone density changes quantitatively over time, with a higher degree of reproducibility and accuracy.

Microbiological analysis:

C.1. Culturing subgingival periodontal bacteria:
It is the only in vitro method able to assess for antibiotic susceptibility of the microbes, and it one can obtain relative and absolute counts of the cultured species. But it can only grow live bacteria; therefore strict sampling and transport conditions are essential. Also it requires sophisticated equipment and experienced personnel and is relatively time consuming and expensive.
C.2. Dark field or phase contrast microscopy:
It gives a direct and rapid assessment for the morphology and motility of bacteria in a plaque sample.
However, most of the main putative periodontal pathogens, including Actinobacillus actinomycetemcomitans, P. gingivalis, B. forsythus, Eikenella corrodens, and Eubacterium species, are nonmotile, and therefore this technique is unable to identify these species. It is also unable to differentiate among the various species of Treponema. Therefore dark field microscopy seems an unlikely candidate as a diagnostic test of destructive periodontal diseases.
C.3. Immunologic assays:
It employs antibodies that recognize specific bacterial antigens to detect target microorganisms. This reaction can be revealed using a variety of procedures, including direct and indirect immune fluorescent microscopy assays (IFA), flow cytometry, enzyme-linked immune absorbent assay (ELISA), membrane assay, and latex agglutination.
Immunological assays can identify dead target cells, thus not requiring stringent sampling and transport methodology and they cannot be used to determine antibiotic susceptibility. Although it provide a quantitative or semiquantitative estimate of target microorganisms.
C.4. Enzymatic Methods of Bacterial Identification:
- B. forsythus, P. gingivalis, the small spirochete Treponema denticola, and Capnocytophaga species share a common enzymatic profile, since all have in common a trypsin like enzyme. The activity of this enzyme can be measured with the hydrolysis of the colorless substrate N-benzoyl-dl-arginine-2-naphthylamide (BANA). When the hydrolysis takes place, it releases the chromophore ß-naphthylamide, which turns orange red when a drop of fast garnet is added to the solution.
C.5. Nucleic Acid Probes:
Deoxyribonucleic acid (DNA) entail segments of single-stranded nucleic acid, labeled with an enzyme or radioisotope, that can locate and bind to their complementary nucleic acid sequences with low cross-reactivity to non-target organisms.
To prepare the probe, specific pathogens used as marker organisms are lysed to remove their DNA. Their double helix is denatured, creating single strands that are individually labeled with a radioactive isotope. Subsequently, when a plaque sample is sent for analysis, it undergoes lysis and denaturation. Single strands are chemically treated, attached to a special filter paper, and then exposed to the DNA library. If complementary base pairs hybridize (cross-link), the radiolabeled strands will also be fixed to the filter paper. After the filter is washed to remove any unhybridized strands, it is covered with a radiographic plate. The radioactive labels create spots on the film, which are read with a densitometer. The darkness and size of the spots indicate the concentration of the organisms present in the given plaque sample. The assay can rapidly test for multiple bacteria.
C.6. Restriction endonucleases
It recognizes and cleaves double-stranded DNA at specific base pair sequences. The DNA fragments generated are separated by electrophoresis, stained with ethidium bromide, and visualized with ultraviolet light. The genetic heterogeneity and homogeneity of strain can then be evaluated by comparing the number and size (electrophoretic pattern) of the DNA fragments obtained. These DNA fragment patterns constitute a specific "fingerprint" to characterize each strain. Restriction endonuclease analysis is thus a powerful tool for determining the distribution of a specific pathogenic strain throughout a population.
C.7. Polymerase chain reaction (PCR):
It involves a reiterate amplification of a region of DNA flanked by a selected primer specific for the target species. The presence of the specific amplification product indicates the presence of the target microorganism.
Characterizing host response:
Diagnostic tests that measure the inflammatory process may provide information on the destructive process itself, current activity of the disease, rate of disease progression, patterns of destruction, extent and severity of future breakdown, and likely response to therapy. Thus help in customizing the recommended treatment.
It depends on detecting mediators which are either specifically identified with the infection, such as antibody to a putative pathogen, or represent a less specific reaction like the local release of inflammatory mediators, host-derived enzymes, or tissue breakdown products.
Potential sample sources include saliva, gingival crevicular fluid (GCF), gingival crevicular cells, blood serum, blood cells, and urine.
Components of GCF have been studied and can be divided into three main groups: host-derived enzymes, tissue breakdown products, and inflammatory mediators.
GCF can be collected by using use of paper strips, microcapillary tubes and micropipettes, micro-syringes and plastic strips.
Periotron® is electronic device measures the change in capacitance across the wetted strip, and this change is converted to a digital readout, which can be correlated to the volume of GCF.


periotron

D.1. Inflammatory Mediators and Products:

Cytokines that are present in GCF include tumor necrosis factor alpha (TNF- a), interleukin-1 alpha (IL-la), interleukin-1 beta (IL-1ß), interleukin-6 (IL-6), and interleukin 8 (IL-8).
They are potent immuneregulatory molecules with a variety of biologic effects, including metalloproteinase stimulation and bone resorption; so they considered asmarkers of disease progression.
Prostaglandin E2 is a product of the cyclooxygenase pathway of the metabolism of arachidonic acid. It is a potent mediator of inflammation and induces bone resorption. In cases of untreated periodontitis, the concentration of prostaglandin E2 found in GCF increased during active phases of periodontal destruction.
D.2. Host-Derived Enzymes:
There are enzymes released from dead and dying cells of the periodontium; some come from polymorphonuclear neutrophils; and others are produced by inflammatory, epithelial, and connective tissue cells at affected site. They include saspartate aminotransferase (AST), akaline phosphatase, ß-glucuronidase, elastase, cathepsins, and matrix metalloproteinases.
D.3. Tissue Breakdown Products:
Analysis of GCF obtained from sites with periodontitis clearly shows elevated levels of hydroxyproline from collagen breakdown and glycosaminoglycans from matrix degradation.