Principles of Investigations
Plan of treatment
Special investigation should only be requested to answer specific question
Some investigation have high specification and sensitivity for particular Disease
Few diseases like mumps may be diagnosed on the basis of a single test, but
others such as Sjogren’s syndrome may require many tests
Fine needle aspiration
(2) Exfoliative cytology
Thick needle/ core biopsy
All special Investigation needed in Oral
Molecular biological test.
* Percussion test
* Palpation test
* Thermal changes test:
- Heat test
- Cold test
* Electric sensitivity testing
• Conventional Radiography:
– Intra-oral [occlusal, Periapical, bitewing]
• Computerized tomography (CT scan)
• Sialography & Arteriography
To detect: Caries – Periodontal disease – Periapical lesion. Neoplasm –
cysts – TMJ disease - Results of trauma to teeth or Jaws – to locate foreign
objects and to find impacted teeth.
Computerized tomography (CT):
CT Scanning provides tomographic images (Section) of high clarity in any plane
Disease in the Maxillofacial complex
CT scanning images of cysts
CT is sensitive for neoplasm
Not always available
High x-ray dose
Less information on soft tissue lesion
Radio-opaque dental restoration cause artifact shadow
It produces clear tomographic images particularly for soft tissue lesion, it can
differentiate between two densities of soft tissues 4 times better than CT Scan
and 40 times better than conventional radiograph, no x-ray dose is present in
Disadvantages: - MRI is expensive and limited availability
- Does not image the bone.
- Long imaging time.
Magnetic Resonance Imaging (MRI)
Ultrasound examinations use high frequency sound pulses. Ultrasound requires
-Used to determine whether any structure is solid or cystic [solid
objective absorb almost all of the sound and are less echoes than the
- Examination of salivary gland (Tumors, cyst, stones). Detect the lesion
in the thyroid gland and neck. Evaluation of lymph node, post surgical
edema and hematoma.
Radio-opaque contrast agent like (Iodine derivative) is infused into the ductal
system of salivary gland. There is low radiation exposure.
•There is some discomfort or pressure when the contrast material is injected
into the ducts.
•The contrast material may taste unpleasant.
Sialography is contraindicated in acute infection of salivary gland. We use with
acute infection the ultrasound to demonstrate the abscess.
Salivary calculi is questionable
Biopsy: Removing tissue from a patient for histopathological examination.
1- Persistent oral ulcers.
2- Persistent red and white lesion
3- suspected neoplasm or any
unidentical tissue masses.
A- surgical biopsy
1- Excisional biopsy: is the removal of whole lesion.
- Can be performed when the lesion no larger than 1 cm
- When it is removal doesn’t necessitate a major
If the lesion is too large for an excisional procedure.
Incisional biopsy of parotid gland tumors (plemorphic adenoma)
is contraindicated but may be examined microscopically only after
excision with a margin of surrounding normal tissue.
2- Incisional biopsy:
Removal only part of lesion which also include normal
The biopsy must be:
- choose from the most suspected area
- Avoid ulcers slough or necrotic area
- Give regional or local anesthesia far from the
- Include normal tissue margin.
- Specimen should preferably at least 1x 0.6
cm x 3mm deep.
- Specimen edges should be vertical not
Diagnosis of swelling in lymph node
Metastatic carcinoma, Hodgkin’s and non Hodgkin’s
Tumors of parotid gland.
The fine needle is inserted into the lesion and cell aspirated and smeared on a slide.
The cells can be fixed, stained and examined within minutes.
B- Fine needle aspiration
1- Avoid damage in vital structures in the neck and head
2- To prevent the spread of tumor cells
3- Less risk of delayed wound healing and infection
4- Rapid diagnosis and treatment
5- It is economy.
C- Thick needle/ Core biopsy.
This method useful for inaccessible tumors, e.g. in the pharynx.
•it has risks of seeding some types of neoplasm into the tissues and
•damaging adjacent anatomical structures.
•It is less used in the head and neck now that FNA is more widely available.
D- Exfoliative cytology
It is examination of cells scraped from the surface of the lesion
• -Most useful for detecting virally- damaged cells, acantholytic
cells of pemphigus or candidal hyphae.
• -Used for patient who should be biopsied but for whom
surgical risk or some other factors prevent it.
• -For patients refuse biopsy.
• -In obvious malignancy.
• -In leukoplakia
• Pemphigus and pemphigoid
• Suspected Lymphoma
• Undifferentiated Malignant neoplasm
• Autoimmune disease
Use of highly specific binding between antibody and
antigen to stain specific molecules within the tissue
1- Culture and antibiotic sensitivity testes
a) Detect un usual pathogens e.g: Actinomycosis in soft
b) Antibiotic sensitivity for all infections, especially:
-Osteomyelitis and acute facial soft tissue infection.
-Exudates from sinus infections.
-Root canal infections.
-Skin, mucus membrane infection.
2- Smear for candida: for candidiasis.
3- Viral culture or antigen screen.
Diagnosis of Disease such as leukaemia, Myloma and leukopenia
which have oral manifastation.
Diagnosis of other conditions such as some infections, sore tongue
and recurrent aphthae which are sometimes associted with
Hematology & Blood chemistry
Types of blood tests useful in oral
CBC: RBC (number–size) Hb And white cell count:
Anaemia, lenkaemias, infections
ESR (erythrosedimentation rate)
Rais in systemic inflammatory and autoimmune disease
Angular cheilitis, painful atrophic glossitis, microcytic anemia
Folate level and vit. B12 level.
Recurrent aphthous, ulceration, recurrent candidosis and
atrophy of papillae of the tongue
Viral antibody titers e.g herpes simplex, varicella zoster, mumps virus
Syphilis serology: Syphilis
Types of blood tests useful in oral
Serum calcium and parathormone level
– A- increase the level of Ca++
Hyperparathyroidism, Malignent Metastasis to bone, Multiple
Myeloma, Hypovitaminosis, paget’s disease of bone.
– B- decrease the level of Ca++
Hypoparathyroidism, Vitamin D diffeciency (rickets,
osteomalacia decrease intestinal calcium absorption and renal
insufficiency and in cases of tetani
Serum phosphate po4
– A- increase the level of po4
Chronic renal disease, healing bone fracture, hypopara-
thyrodism, Hypervitaminosis D, increase of level of Growth
– B- decrease the level of po4
Rickets disease and osteomalacia
Types of blood tests useful in oral
• Blood Glucose level
– A- Increase blood glucose level.
Diabetic Mellitus, cushinges diseases, in patient taking corticosteriod and
thiazid diuretic drug.
– B- decrease blood glucose level.
Insulin –secreting tumor, extensive liver disease, pituitary hypofunction,
addison’s disease Mal absorption of monosaccharides.
• Serum Bilirubine
Haemolytic anaemia, biliary obstruction, hepatitis, hepatic malignancy.
• Serum uric acid
Gout, renal failure, leukaemia lymphoma, thiazid diuretic.
• Serum Alkaline phosphate
High level in condition with increased bone turnover e.g paget’s disease,
• Serum creatinin
Increased in kidny disease, acromegaly and patient with large muscle mass.
Diagnosis of diabetes, autoimmune conditions which damage the kidney
-if the bone or soft tissue infection are suspected
- It helps distinguish facial inflammatory odema from cellulitis
-Systemic effect of infection and the need for more aggressive treatment
BLEEDING TIME TEST