Laboratory diagnostic methods and biopsy in dentistry

Laboratory and immunological diagnostics

In modern dentistry, laboratory tests are widely used to make an accurate diagnosis, differentiate it, and assess therapy efficacy. General clinical studies evaluate blood parameters (sugar, calcium levels, enzyme activity), urine, and gastric juice.

Of particular importance is immunological screening, which allows for the assessment of two defense arms:

• Systemic (general) immunity: the absolute and relative counts of T-lymphocytes (CD3+), regulatory T-helper cells (CD4+), and T-suppressor cells (CD8+), as well as B-lymphocytes, are analyzed.
• Local oral immunity: saliva is examined. Its concentration of secretory immunoglobulin A (sIgA), lysozyme, $\beta$-lysins, and polymorphonuclear leukocytes is determined.

Functional tests and instrumental assays

To clarify the diagnosis, clinicians use functional tests and specialized instrumental assays.

The main functional tests include:

• Blister and histamine tests;
• Schiller-Pisarev test;
• Language test (Yakovets modification) and Rotter test;
• Kavetsky and Yasinovsky tests;
• Determination of capillary resistance (Kulazhenko method).

The list of instrumental methods includes biomicroscopy, masticaciography, rheodentography, polarography, laser Doppler flowmetry, and electric pulp testing (EPT). During EPT, a current intensity from 0 to 200 µA is applied. Values strictly depend on the pathology: 2–6 µA for caries, 20–90 µA for pulpitis, and over 100 µA for periodontitis.

Diagnosis of liquorrhea in trauma

In fractures of the maxilla or skull base, it is critically important to promptly recognize liquorrhea — the leakage of clear, pale yellow cerebrospinal fluid (CSF) from the nose. The process intensifies if the patient leans forward, strains, or if the large neck veins are compressed.

Two signs are used for the differential diagnosis of CSF from nasal secretions:

1. «Handkerchief» sign: if secretions are blotted with an ordinary handkerchief, the fabric remains soft after the CSF dries. In case of a runny nose, the handkerchief becomes stiff ("starched").
2. «Medical napkin» sign: if a mixture of blood and CSF is discharged from the nose, a specific pattern forms on the napkin — a red blood spot in the center with a light halo spreading peripherally.

X-ray imaging methods

Radiological diagnostics is often the only objective way to confirm a diagnosis in lesions of the facial bones, teeth, and paranasal sinuses. CT, MRI, radionuclide diagnostics, and contrast-enhanced methods (sialography, fistulography, maxillary sinusography) are used.

Intraoral radiography is performed using dental units in four ways:

• Contact (periapical): the patient presses the film against the mucosa themselves.
• Occlusal (bite): used for an elevated gag reflex, trismus in children, or for assessing large areas of the alveolar process.
• Interproximal: the film is fixed with a holder, eliminating distortion of the marginal areas (ideal for detecting proximal caries).
• Long-cone: the film is placed parallel to the tooth axis. It eliminates distortions and is suitable for assessing dynamics, dental dislocations, and fractures.

To evaluate the entire dentition, orthopantomography is used (30% magnification). Magnified panoramic radiography (1.2x magnification) is most informative for the anterior regions, diagnosing neoplasm contours, and detecting mandibular osteomyelitis (assimilated periosteal reactions).

Clinical examination algorithm

All examination methods in dentistry are divided into main (taking complaints, history, questioning, visual inspection, palpation, percussion, probing) and additional (radiography, CT, EPT, thermometry, laboratory tests).

For a thorough examination, the doctor uses special instruments: a mirror, tweezers, a plastic instrument, an excavator, a spatula, as well as probes (button-tipped for fistulas, periodontal, and salivary). The entire process of interaction between medical personnel and the patient is based on the principles of deontology — the science of medical ethics.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Radionuclide diagnostics and the use of radioactive nuclides
• Projections for facial bone radiography (axial, semi-axial, etc.)
• Principles of deontology in dental practice
• Instrumental functional methods: rheoparadontography and polarography

Other topics in "Chapter 3. Features of patient examination in surgical dentistry (M.M. Pozharitskaya, V.V. Afanasyev)"

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