laboratory investigations in dentistry

Presented by:

Dr.Sachidanand GiriJR-3

1. Definition

2. Need for Lab investigations

3. Applications

4. Classifications

5. Laboratory Investigations (Frequently and

infrequently required)

a. Haematological Investigations

b. Biochemical Investigations

c. Microbiological Investigations

d. Immunological Investigations

e. Histopathological and Cytopathological

Investigations

7. Conclusion

8. References

Laboratory studies are an extension of physical examination in which tissue, blood, urine

or other specimens are obtained from patients and subjected to microscopic, biochemical,

microbiological or immunological examination.

Information obtained from these investigations help us in identifying the nature of the

disease.

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Evidence shows Case History and Clinical examination usually reveal most of ,but not

all of clinically relevant data.

The provisional diagnosis can be made on the basis of case history and clinical

examination but for definitive diagnosis laboratory investigations are required

Lab investigations supplement rather than replace other methods for gathering

information

It is a known fact that with the help of lab investigations, some underlying systemic

conditions of which the patients are unaware of, are often identified in dental practice

for the first time

Confirming or rejecting clinical diagnosis

Providing suitable guidelines in patient management

Providing prognostic information of the diseases under consideration

Detecting diseases through case-finding screening methods

Establishing normal baseline values before treatment

Monitoring follow up therapy

Providing information for Medico-Legal consultations

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Based on where investigation is done:

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Chair side Investigations Laboratory Investigations

Acts as a precursor to laboratory

investigations

Significantly higher sensitivity

and specificity

Egs : Toluidine blue staining for

grading dysplasia, Electric Pulp

testing for tooth vitality,

Egs: Glycated Haemoglobin

estimation,

Peripheral smear histology

Based on specificity/sensitivity:

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Screening Tests Diagnostic Tests

An ideal screening test is 100%

sensitive

An ideal diagnostic test is 100% specific

Useful in a large sample size at risk;

typically cheaper

Useful in symptomatic individuals to establish

diagnosis or asymptomatic individuals with +ve

screening test; expensive

Egs : blood glucose estimation for

screening diabetes,

Haematocrit values for anaemia,

VDRL test for syphilis

Egs: Glycated Haemoglobin estimation, OGTT

Peripheral smear histology

Based on Hospital Lab Services:

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Haematology

Histopathology

Biochemistry

Immunology

Urinalysis Biochemistry

Cytopathology

Based on frequency of dental use: (by Sonis, Fazio & Fang )

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Frequently used:

• CBC- Hb, Hct, Absolute and differential WBC

• Bleeding studies – BT,CT, PT, aPTT

• Peripheral Blood Smear

• Random Blood Glucose

Occasionally done:

• Tests for disturbance of bone – Ca, P, ALP

• ESR

• Urinalysis

• Screening Test for Syphilis

Rarely ordered:

• Enzyme testing

• Bilirubin Estimation

• Creatinine Estimation

• Acid Phosphatase

• BUN

SIGNIFICANCE OF BLOOD INVESTIGATION

Blood investigation helps in diagnosing

• Leukopenia

• Thrombocytopenia

• Myeloma

• Anemia *Iron deficiency

*Aplastic

*Sickle cell anemia

• Thalassemia

• Acute and Chronic leukemia

• liver disease

• Myxedema

•Diabetes

COLLECTION OF BLOOD SAMPLE

•CAPILLARY BLOOD SPECIMENS: The

specimen is obtained by pricking the patient`s

finger .

•VENOUS BLOOD SPECIMEN: Most

Commonly used method. Venipuncture is

usually performed in ANTECUBITAL vein.

•WBC count

•Differential

Leukocyte count

•RBC count

•Hemoglobin

•Hematocrit

•Erythrocytes indices

•Platelet Count

•Bleeding time

•Capillary Fragility Test

•Clotting Time

•Erythrocyte Sedimentation Rate

TYPES OF HEMATOLOGICAL INVESTIGATIONS

Complete Blood Count

COMPLETE BLOOD COUNT

Complete blood count (CBC) is one of the most commonly ordered blood tests.

The complete blood count is the calculation of the cellular (formed elements) of blood.

What are the components of the complete blood count (CBC)?

The complete blood count, or CBC, lists a number of many important values. Typically, it

includes the following:

• White blood cell count (WBC or leukocyte count)

• WBC differential countWBC

• Red blood cell count (RBC or erythrocyte count)

• Hematocrit (Hct)

• Hemoglobin (Hbg)

• Mean corpuscular volume (MCV)

• Mean corpuscular hemoglobin (MCH)

• Mean corpuscular hemoglobin concentration (MCHC)

RBC

• Platelet countPLATELET

•White blood cell count (WBC) is the number of white blood cells in a volume

of blood.

• Normal range of WBC= 4,500 - 10,000 cells/mm3 of blood.

WBC/Leukocyte Count

Specific causes of Leukocytosis:

1. Infection- Acute and Chronic

2. Leukaemia

3. Polycythemia

4. Trauma

5. Exercise , Stress and fear

6. After general anesthesia

7. Allergy

8. Drugs, such as corticosteroids and epinephrine

9. Rheumatoid arthritis

10. Smoking

Specific causes of Leukopenia:

1. Aplastic anaemia

2. Influenza, measles and Respiratory tract infection

3. Early Leukaemia

4. Depression of Bone marrow

5. Drug and chemical toxicity

6. Shock

WBC

Granulocytes

Neutrophils Eosinophils Basophils

Agranulocytes

Lymphocytes Monocytes

White blood cell (WBC) differential count:

White blood cells are comprised of several different types of cells that are

differentiated, or distinguished, based on their size and shape.

Differential Count WBC

Normal values:• Granulocytes (or polymorphonuclears)

Neutrophils: 43-77% (3000-7000)

Eosinophils: 0-4% (50-200)

Basophils: 0-2% (0-100)

• Agranulocytes (or mononuclear)

Lymphocytes: 17-47 %(1000-3500)

Monocytes: 2-9%(100-600)

CLINICAL SIGNIFICANCENeutrophils

INCREASES in: DECREASES in:

Inflammatory disease Aplastic Anaemia

Stress Cyclic Neutropenia

Exercise Malignant Neutropenia

Pregnancy Early Leukemia

Acute Infection

Excitement

Eosinophils

INCEASES in: DECREASES in:

Parasitic infections Immune defect

Hypersensitivity/ Acute stress

Allergic responses Typhoid Fever

Scarlet Fever Aplastic Anaemia

Basophils


Chronic leaukemia Acute Infection

Myelofibrosis Severe injury

Polycythemia

Lymphocytes

INCEASES in: DECREASES in:

Lymphocytic Leukemia Aplastic Anaemia

Mumps

Whooping Cough

Chronic Infection

Monocytes


Monocytic leukemia

Hodgkin disease Aplastic Anaemia

Malaria – Kala -azar

SABE

TB

Infectious mononucleosis

Most common sign of neutropenia is ulceration of oral mucosa.

Ulcers lack surrounding inflammation and are characterized by necrosis.

Advanced periodontal disease,paricoronitis, pulpal infections.

Most common sign of leukemia- cervical lymphadenopathy

Others-pallor of the mucosa, petechiae,echymosis, gingival bleeding,

oral ulcers, oral infections(candidiasis)

RBC Count

•Red Blood cell count (RBC) signifies the number of red blood cells in a volume of

blood.

• Normal range : 4.2 to 5.9 million cells/cmm.

• This can also be referred to as the Erythrocyte count

• It can be expressed in international units:4.2 to 5.9 x 1012 cells

per liter.

•An increase in red blood cell mass is known as Polycythemia.

•PV is a chronic myeloproliferative disease characterized by a predominant proliferation of the erythroid

cell line.

•Oral manifestations: purplish red discoloration of oral mucosa, gingivae and tongue,

•Gingivae are markedly swollen and bleed spontaneously but not ulcerated

•Petechiae are common

•Severe hemorrhage after dental extractions and periodontal surgery

•Smokers also have a higher number of red blood cells than non-smokers.

INCREASE in RBC Count

DECREASE in RBC Count

•Massive RBC loss, such as acute hemorrhage

• Abnormal destruction of red blood cells

• Lack of substances needed for RBC production

• Chemotherapy or radiation side effects from treatment of bone marrow malignancies

such as leukemia can result in bone marrow suppression.

HEMOGLOBLIN

Hemoglobin is the protein molecule within red blood cells that carries oxygen and gives

blood its red color.

•Normal range =13-18 grams per dl for men and

12-16 grams per dl for women

A low haemoglobin count can also be due to blood loss

Diseases and conditions that cause the body to destroy red blood cells faster than

they can be made:

• Enlarged spleen (splenomegaly)

• Sickle cell anemia

• Thalassemia

• Vasculitis

•It is a measure of volume percent of packed red blood cells to that of whole blood.

Normal results :

Male: 40.7 - 50.3%

Female: 36.1 - 44.3%

Hematocrit (Hct)

Erthrocytes Indices

•To evaluate the nature of Anaemia, assistance is obtained by calculating standard indices

relating to the size of RBCs.

•By measuring these indices we can classify anaemia as Microcytic, Macrocytic And

Normocytic and Hypochromic and Normochromic.

Types

MCH MCHC MCV

The Haemoglobin content of erythrocyte is referred to as the Mean Corpuscular

Haemoglobin(MCH) expressed in picogram of haemoglobin per cell.

MCH = Haemoglobin concentration (g/dl) × 100

RBC in million/mm3

Mean Corpuscular Haemoglobin (MCH)

The concentration of Haemoglobin in the erythrocyte is referred to as the Mean Corpuscular

Haemoglobin Concentration.(MCHC) expressed in picogram of haemoglobin per cell.

MCHC = Haemoglobin concentration (g/dl) × 100

Hematocrit

Mean Corpuscular

Haemoglobin Concentration (MCHC)

The average red cell volume is referred to as the Mean Corpuscular Volume(MCV) .

It is expressed in cubic microns per cell.

MCHC = Hematocrit × 100

RBC in million /mm3

Mean Corpuscular Volume (MCV)

Different types of Anaemia and Indices

Types of Anemia MCV MCH MCHC

Microcytic

Hypochromic

Decreased Decreased Decreased

Macrocytic

Normochromic

Increased Increased Normal

Normocytic

Normochromic

Normal Normal Normal

The common causes of Microcytic & Hypochromic Anemia (decreased

MCV and MCH) are:

• Iron deficiency anemia

• Anemia of chronic disease

• Thalassemia

• Sideroblastic anemia

Angular cheilitis (58%),

Glossitis with different degrees of atrophy of fungiform and filliform papillae

(42%),

Pale oral mucosa

Oral candidiasis

Recurrent aphthous stomatitis

Erythematous mucositis

And burning mouth for several months to 1 year’s duration.

The common causes of Macrocytic Anemia (increased MCV and MCH) are as

follows:

•Folate or Vit B12 deficiency anemia

•Liver disease

•Hemolytic or Aplastic anemias

•Hypothyroidism

•Excessive alcohol intake

•Myelodysplastic syndrome

Patients with pernicious anemia may have complaints of:

Painful glositis and glosopyrosis-early symptoms

Sore tongue, Dysphagia

Burning sensation in the tongue, lips, buccal mucosa, and other mucosal

sites.

The tongue and mucosa may be smooth or patchy areas of erythema.

And loss of taste sensation

The common causes of Normocytic And Normochromic Anemia (normal

MCV, MCH and MCHC) are:

•Anemia of chronic disease

•Acute blood loss

•Hemolytic anemia, such as autoimmune hemolytic anemia, hereditary

spherocytosis, or nonspherocytic congenital hemolytic anemia (G6PD deficiency,

other)

•Anemia of renal diseases.

Pallor of oral mucosa especially evident in soft palate, tongue,

sublingual tissues

Paresthesia of mucosa

For those with chronic conditions, hyperplastic marrow spaces

In the mandible, maxilla, and facial bones

PLATELET/THROMBOCYTE COUNT

The number of platelets in a specified volume of blood.

Platelets play a vital role in Haemostasis.

Normal range (Adult) =150,000 to 400,000/ cmm of blood.

(150 to 400 x 109/ L)

Normal range(Children) =150,000-450,000 /cmm of blood.

(150-450 x 109/L)

Interpretation of Platelet count

THROMBOCYTOSIS:

Post operative phase

Pregnancy

Post partum phase

Haemolytic Anemia

Trauma

Polycythemia vera

Chronic myelocytic leukemia

THROMBOCYTOPENIA:

Acute leukemia

Idiopathic thrombocytopenic purpura

Aplastic anemia

Effect of chemotherapy

Hypersplenism

•It is the measure of the rate at which RBCs sediments in a period of one hour.

•Also called as Sedimentation Rate or Westergren ESR

•It is a non-specific measure of inflammation.

•Also helpful in following progress of some chronic infections (TB and

Osteomylelitis)

Normal ESR

Male: 0-15 mm per hr

Female: 0- 20 mm per hr

Erythrocyte Sedimentation Rate (ESR)

Interpretation of ESR

ESR increased:

Tuberculosis

Osteomyelitis

Rheumatic fever

Myocardial infarction

Rheumatoid arthritis

Hodgkin's disease

Leukaemia

ESR decreased:

Congestive cardiac failure

Polycythemia

Severe dehydration like cholera

Physiologic condition where ESR is

increased: Pregnancy: After intake of full meal

It Measures the time required for hemostatic plug to form.

Lack of any clotting factor or platelet abnormalities will prolong the bleeding time.

It is used to screen disorders of platelet function and thrombocytopenia

Normal Bleeding Time: 2 - 6 minutes

Methods are: Duke method (7-8 min)and Ivy’s method(5-6min)

Bleeding Time

An abnormal Bleeding time- It is usually the result of abnormalities in the structure /

abilities of capillaries to contract or abnormalities in the number (Thrombocytopenia)

and functional integrity of platelets.

Interpretation of bleeding time

Prolonged in:

Thrombocytopenia

Acute leukaemia

Aplastic anaemia

Liver diseases

Von-Willebrand’s disease

•It is the test of the ability of superficial capillaries of the skin of the

forearm and hands to withstand an increased intra-luminal pressure and a certain

degree of hypoxia.

It is done by occluding the upper veins of the upper arm with a blood pressure cuff

for five minutes.

Also known as Tourniquet Test/ Rumpel Leede Test

Capillary Fragility Test

Indication:

1. Bleeding abnormalities

2. Petechiae in oral cavity

3. Scurvy

Positive result: unequivocal petechiae seen distal to cuff.(15-20/2.5cm2)

Negative result: If only 1 or 2 petechiae seen distal to cuff.

Time required for coagulation to occur in a sample of whole blood outside the body

is known as Clotting Time.

Normal time- 3 to 7 minutes

Method are:

• Capillary tube method

• Le and white’s test tube method

Clotting Time

An abnormal Clotting time- It is usually prolonged in diseases affecting stages of

coagulation.

It is also increased in:Cirrhosis

Hemophilia A and B

Factor XI deficiency,

Hypofibringenemia and

Heparin & Dicumarol therapy.

Interpretation of Clotting time

HEMATOLOGICAL INVESTIGATIONS

(not so frequent in dentistry)

•Prothrombin Time

•Partial Thromboplastin Time

•INR

It is the time in seconds that is required for development of a clot in citrated or

oxalated plasma, where known amount of tissue thromboplastin and calcium is

added.

It is used to check the extrinsic pathway factor (F 7) and the common pathway ( F 5,

10 , prothrombin and fibrinogen).

Normal range: 11 to 15 seconds

Prolonged time (>3 times) indicates a hemorrhagic tendency.

It gets prolonged when plasma level of any factor is below 10% of its normal value

PROTHROMBIN TIME

Prothrombin Time (PT):

Increased PT

Disseminated Intravascular Coagulation

Patients on Warfarin Therapy

Vit K deficiency

Early & End stage Liver failure

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It is the time in seconds that is required for a clot to form in a sample of oxalated

plasma, to which a partial thromboplastin reagent and calcium is added.

It is used to check the intrinsic system (8, 9, 11, 12) and the common pathways (5,

10, prothrombin and fibrinogen).

Normal range: 25-35 seconds

If PTT is prolonged it indicates deficiency of factor 8 or 10

PARTIAL THROMBOPLASTIN TIME

INR:

INTERNATIONAL NORMALIZED RATIO

The International Normalised Ratio (INR) is a laboratory measurement of how

long it takes blood to form a clot. It is used to determine the effects of oral

anticoagulants on the clotting system.

It is the ratio of Patient’s Prothrombin Time to that of normal Prothrombin time.

INR= Patient`s PT

Normal PT

It should be noted that INR is used to monitor Anti coagulant therapy & NOT be

used as coagulation screening test

INR values of 5.0 or greater indicate a serious risk of spontaneous bleeding

episodes.

NORMAL RANGE: 0.8-1.2 (No anticoagulant therapy)

02-03 (On anticoagulant therapy)

• Infiltration anesthesia , scaling and root planningINR <3

• Block anesthesia , minor surgery , extractionINR <2

• Major surgeryINR <1.5

Serum Iron and Total Iron Binding Capacity:

Iron deficiency is usually detected on the basis of the amount of iron

bound to transferrin in the plasma(serum iron) and the total amount of

iron that can be bound to the plasma transferrin in vitro.

Normal values

Serum iron – 80-180 µg/dl

TIBC – 250 – 370 µg/dl

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Glycated

Haemoglobin(HbA1

c

Fasting Plasma Glucose (FPG) Oral Glucose Tolerance

Test (OGTT)

Normal <5.7% <100 mg/dl <140mg/dl

Prediabetes 5.7% to 6.4% 100 mg/dl to 125 mg/dl 140 mg/dl to 199 mg/dl

Diabetes 6.5% or higher 126 mg/dl or higher 200 mg/dl or higher

High values are seen in Diabetes mellitus, Cushing’s disease,

pheochromocytoma, in patients taking corticosteroids

Low values seen in insulin secreting tumours, Addison’s, Pituitary

hypo function

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Oral Glucose Tolerance Test:

Used for the definitive diagnosis of diabetes mellitus and for

distinguishing diabetes from other causes of hyperglycaemia

like hyperthyroidism

Should be performed on only healthy ambulatory patients

who are not under any drugs which may interfere with

glucose estimation

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Glycated Haemoglobin(HbA1c):

Hb becomes Glycated by ketoamine reactions between glucose and other

sugars.

Once Hb is Glycated, it remains that way for a prolonged period(2-3

months)

Hence it provides a definitive value of blood sugar control of 2-3 month

duration

The HbA1c fraction is abnormally elevated in diabetic patients with chronic

hyperglycaemia

It is considered to be a better indicator for diabetic control compared to

blood glucose levels.65

Mucosal conditions include oral dysesthesia, including burning mouth,

Altered wound healing,

Increased incidence of infection,candidal infections (particularly acute pseudomembranous candidiasis of

the tongue, buccal mucosa, and gingiva).

Xerostomia and bilateral generalized salivary gland enlargement or sialadenitis (especially in the parotid

glands) can occur and both are often related to poor glycemic control

High incidence of dental caries.

Dry mucosal surfaces

Gingivitis and periodontitis

Poor wound healing

Serum Calcium, Phosphorus:

Indicated on suspicion of Paget’s disease, fibrous dysplasia, primary and secondary

hyperparathyroidism, osteoporosis, multiple myeloma or osteosarcoma

The concn. of Serum Ca varies inversely with serum P

Normal level Serum Ca – 9.2-11 mg/dl

Normal level Serum P – 3- 4.5 mg/dl

At levels less than 7 mg/dl Serum Ca, signs of tetany(n-m excitability,+ve chvostek’s

sign) may appear.

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Serum Alkaline Phosphatase: (ALP)

ALP produced in small amounts in the liver but most notably in osteoblasts

Normal values:

68

ADULT CHILD

King Armstrong Units 3-13 15-30

Bodansky Units 1-4 5-14

International Units(IU/l)

30-110


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High values Low values

Obstructive liver disease Hypophosphatasia

Paget’s disease of bonehyperparathyroidism

Hypothyroidism

Osteomalacia Osteoporosis

Rickets Aplastic/Pernicious anaemia

Sarcoidosis Chronic Myeloid Leukaemia

Lymphoma Wilson’s Disease


This test is very useful for diagnosing biliary obstruction.

Even in mild cases of obstructive disease, this enzyme is elevated.

It is not very useful for diagnosing cirrhosis.

If a patient has bone disease, this test may be highly inaccurate, as ALP

is also found in bone tissue.

70

Normal value:200-400U/L (LDH)

For CPK male: 5-35 ug/ml (mcg/ml);

female: 5-25 ug/ml

newborn: 10-300 IU/L

Iso-enzymes of CPK are:

CPK-1 (BB)

CPK-2(MB)

CPK-3(MM)

LDH1-2 : heart fractions

LDH5:liver fraction

LDH234:acute leukemia,chronic myelogenous leukemia, infectious

mononucleosis, lymphomas

In heart attack: CPK increase in 4 hours, SGOT in 12 hours, increase in

LDH 1-2 days later

Total Protein & Albumin/Globulin Ratio:

These proteins are important in coagulation, transport a variety of

hormones, act as buffer systems and help maintain osmotic pressure

Normal range:

Total protein – 6 – 8.3 g/dL

A/G ratio - 1.2 – 2.0

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Elevation: multiple myeloma, systemic lupus erythematosus,

amyloidosis, collagen diseases ets. Serum protein electrophoresis: albumins,fibrinogen,

globulins(alpha1,alpha2,beta,gamma),agammaglobulinemias Immunodifusion- IgA, IgM, IgG, IgE

Normal value:

Total cholestrol :75-169 mg/dL for those age 20 and younger

100-199 mg/dL for those over age 21

HDL: >40 mg/dl

LDL: <130 mg/dl

TRIGLYCERIDES: <150 mg/dl

Liver function tests(LFT) are helpful to detect the abnormalities and extent of liver

damage.

LFT assays are frequently more sensitive than clinical signs and symptoms.

Typically the LFT comprises of:

Total protein

Albumin and globulin

(Prothrombin Time)

Transaminases – AST & ALT

Alkaline PO4ase

Bilirubin, usually fractionated

Gamma Glutamyl Transpeptidase (GGT)

Alanine Aminotransferase (ALT)/SGPT

The test is primarily used to diagnose liver disease, to monitor the course of treatment for

hepatitis, active post-necrotic cirrhosis, and the effect of drug therapy.

Normal value: 8-45 U/liter

ALT is the most sensitive marker for liver cell damage.

Aspartate Aminotransferase (AST)/SGOP:

It may be elevated other conditions such as a myocardial infarct and muscle disease

Normal value:<25 U/L

.

Gamma glutamyl transpeptidase:

Normal value:9-48 U/L

Elevated levels of GGT : mainly alcoholic cirrhosis or individuals who are

heavy drinkers

Serum Bilirubin:

Bilirubin is a bile pigment derived from the breakdown of Haemoglobin

Normal value: 0.1 – 1.2 mg/100ml

This is routinely performed with ‘dip-sticks’.

It may reveal:

Glycosuria, which may suggest diabetes mellitus

Ketonuria, which may be a sign of diabetic ketoacidosis or starvation

Bilirubin or urobilinogen, which may indicate hepatobiliary disorders

Proteinuria, which may be due to menstruation, or indicate renal, urinary tract

or cardiac disease

Haematuria, which may be due to menstruation, or indicate renal or urinary

tract disease.

As markers of renal function creatinine, urea, uric acid and electrolytes are done for routine

analysis

Serum creatinine

Creatinine is filtered but not reabsorbed in kidney.

Normal range is 0.8-1.3 mg/dl in men and 0.6-1 mg/dl in women.

Not increased above normal until GFR<50 ml/min .

Blood urea

Many renal diseases with various glomerular, tubular, interstitial or vascular damage can

cause an increase in plasma urea concentration.

The reference interval for serum urea of healthy adults is 10-40 mg/dl.

Metabolic end product of nucleoprotein.

Normal value:4-8.5 mg/dl for male and 2.8-7.5mg/dl for female

Increases in gout, leukemias,lymphomas, anemia, pt on diuretics

Evaluation of intrinsic disease of TMJ

The GFR is the best measure of glomerular function.

Normal GFR is approximately 125 mL/min

When GFR is 5% to 10% of normal ESRD

Inulin clearance and creatinine clearance are used to measure the

GFR.

Stomatitis, gingivitis,

A bad taste and odor in the mouth, particularly in the morning( uremic fetor), an

ammoniacal odor

White plaques called “uremic frost” and occasionally found on the skin can be found

intraorally, although rarely.

Significant xerostomia, probably caused by a combination of direct involvement of the

salivary glands, chemical inflammation, dehydration, and mouth breathing (kussmaul’s

respiration).

Salivary function studies include:

1. Measurement of Na, K, Cl concentration in saliva

2. Measurement of total salivary flow

3. Rate of flow of saliva from orifices

4. Rate of discharge of radio-opaque dye from salivary gland following retrograde

sialography

5. Rate of uptake and secretion of 99m Tc-pertechnate by salivary glands

85

Normal values for unstimulated saliva are

K – 25 mEq/L

Na - <10 mEq/L

Cl - 15-18 mEq/L

Increase in K or Na values may indicate generic inflammation or

sialodenosis

In parotid enlargement accompanying cirrhosis

Parotid flow rate and salivary concn of Na,K,Cl, salivary amylase & protein

increases

Immunoglobulin levels remain normal

86

In Sjogren’s Syndrome

Flow rate is reduced

Salivary phosphate concn is reduced

Na & Cl concn is elevated

Salivary IgA concn elevated

Urea and K concn unchanged

Abnormal protein bands can be distinguished by electrophoresis

87

Culture and sensitivity tests are used to isolate and identify causative micro

organisms of an infection

May be obtained from blood or urine

Particularly helpful in evaluating infections related to throat, sinuses, root

canals or bone.

Sensitivity tests may also be ordered when patient relapses, the

identification of the organism is uncertain or the disease is severe

Most common limitation is the delay in receiving the report

Another problem is: in-vitro testing may not necessarily predict the same

result as in-vivo testing

90

This procedure employs the use of fluorescent labelled antibodies to

detect specific Ag-Ab reaction of known specificity in tissue sections

When tissue sections labelled in this fashion are illuminated with ultra

violet light in an UV microscope, specific labelled tissue component can

be identified by their bright apple green fluorescence against a dark

background

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1. ImmunoPrecipitation Assays:

Detects Antibody in solution

End point is visual flocculation of the antigen and the antibody in suspension

2. Complement Fixation:

Based on activation/fixation of complement following binding of

complement factors to Ag-Ab immune complexes

94

3. Particle Agglutination:

Relatively simple and fast

Capable of detecting lower concentration of antibodies

Designed to detect antibodies to viruses, subsequent to vaccination

Utilizes Ag coated latex particles, coal particles

95

4. Enzyme Immuno Assay:

Most sensitive

Usually indirect assay that depends on the use of anti human IgG or IgM Ab

conjugate

Antibody conjugate, if present is made to attach to enzyme which catalyses

conversion of substrate to a coloured product which is then read by a

spectrophotometer

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5. Radio Immuno Assay:

Extremely sensitive and specific procedure

Used to measure concentration of Ag in patient’s sera by using Ab

To perform this, a known quantity of Ag is made Radioactive and is made

to compete with Ag in patient’s sera for Ab binding sites

The radioactivity of free Ag remaining is measured using a Gamma

counter

97

Histopathology refers to the microscopic examination of

tissue in order to study the manifestations of the disease

Cytopathology refers to the scientific study of role of

individual cells or cell types in disease

98

A biopsy is a controlled & deliberate removal of tissue from a living organism for

the purpose of microscopic examination

Relatively simple procedure producing little discomfort when compared to

exodontia or periodontal surgery

Indications:

When signs and symptoms of an observed tissue change do not provide enough

information to make a diagnosis

When neoplasia is one of the differential diagnosis

To confirm a clinical diagnosis99

Contraindications:

The systemic health of the patient may contraindicate biopsy completely or at

least cause its postponement

Site of the lesion may pose a risk to biopsy (for eg. Biopsy in richly vascularized

areas may pose a risk of haemorrhage)

Cases of clinically obvious malignant neoplasm should be referred directly to the

appropriate specialist as biopsy would delay definitive care rather than accelerate

it

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Avoidance of Delay for Biopsy:

1. Rapid growth

2. Absent local factors

3. Fixed lymph node enlargement

4. Root resorption with loosening of teeth

5. History of malignancy

101

Uses:

1. Diagnosis

2. Grading of tumours

3. Metastatic lesions

4. Recurrence

5. Management Assessment

102

Excisional biopsy:

Total excision of a small lesion for microscopic exam.

Diagnostic + Therapeutic

Incisional Biopsy

Performed by removing a wedge shaped specimen of pathological tissue along with surrounding normal zone

Punch Biopsy:

With this technique the surgical defect produced is small and does not require suturing

Tissue is removed in same manner as incisional/excisional

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The biopsy report communicates the pathologist’s opinions concerning the specimen

to the practitioner

The format includes:

▪ Patient summary

▪ Gross description of the specimen

▪ Microscopic description of the specimen

▪ The diagnosis

▪ Additional comments

104

Developed by Dr. George Papanicolaou who is also known as “Father of

cytology”

In this, the surface of the lesion is either wiped with a sponge material or

scraped to make a smear.

The appreciation of the fact that some cancer cells are so typical that they

can be recognized individually has allowed the development of this

diagnostic technique

105

Advantages:

• Time saving

• Painless

• Low cost

• No anaesthesia

• Screening test

• Rapid diagnosis

Disadvantages:

• Firm tumours

• False negative results

• Non assessment

Indications:

• Patient preference

• Debilitated patients

• Adjunct

• Rapid evaluation

• Population screening

106

Interpretation:

107

Microscopic examination of an aspirate obtained by inserting a fine needle into a lesion

Painless and safe procedure for rapid diagnosis Indications:

Salivary gland pathology

As a replacement for extensive biopsy

Cystic lesions

Suspicious lymph nodes

Recurrence

Metastatic lesion

108

AUTO FLUORESCENCE

VELSCOPE

CHEMILUMINESCENCE

VIZILITE MICROLUX DL

NUCLEAR MEDICINE (BONE SCAN)

Lab investigations have become an integral component of a complete

examination of the patient

They confirm the authenticity of our clinical impression and also provides

a prognostic know how post treatment

As oral physcian we should have a thorough knowledge about different

investigations pertaining to our field of study

We should also know how to correlate our history taking and clinical

examination so as to order for the most appropriate investigation116

1. Burket’s oral medicine, diagnosis and treatment. 8th edition.

2. Burket’s oral medicine.11th edition.

3. Textbook of ORAL MEDICINE ,Anil Govindrao Ghom, Second Edition.

4. Stern.R. Karplis, Kinney, Glickman. Using International normalized ratio to standardize

prothrombin time

5. Coleman , Nelson ; Principle of Oral Diagnosis

117

laboratory investigations in dentistry

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