OMR NOTES

(reference www.pgdoctors.com)

the rate of loss of energy from particle as it moves through irradiated material is linear energy transfer. The dose required to produce a certain biologic effect is reduced as linear energy transfer of radiation is increased
alpha rays have higher linear energy transfer and are more damaging to biologic system than x rays

0.2 to0.8 percent of cathode rays are transformed into x rays after striking anode target

average wavelength of x rays used in dentistry is 0.6 to 1 Au

kvp control the wavelength and penetration power of x rays

kvp increased x ray of short wavelength produced and penetration power ishigher (hard x rays )

density is directly proportional to milli ampere and kvp and inversely to focal spot

exposure time is inversely proportional to kvp and ma and directly proportional tosquare of focal spot film
distance

the useful range of density for a dental x ray is 0.3 to 2 density increase with increase in film fog thomson effect or classical effect or coherent scattering energy of scattered photon is equal to energy of incident photon it account for 8 percent of total interaction and photo electric absorption account for 30 percent of interaction and compton scattering form 62 percent so is the major source of secondary radiation ionization chamber film badges and thermoluminiscent dosimeter are method to measure radiation exposure SI UNIT :: absorbed dose - Gray equivalent dose - sievert radioactivity - becquerel exposure columb/kg. The mnemonic is AGES absorbed dose - gray equivalent dose - sievert about two third of radiation induced biologic damage result from indirect effect maximum permission dose for skin in 1 year is 15 rem (1 siev= 100 rem ) maximum permission dose for gonad / bone marrow in 1 year is 5 rem maximum permission dose for whole body for radiation workers in 1 year is 5 rem maximum permission dose for gestation period in relation to foetus is0.5 rem maximum permission dose for whole body for general public in 1 year is0.5 rem maximum permission ford for whole body for radiation worker in 1 week 0.1 rem

the amount of radiation necessary to produce a noticeable skin reaction is called as Erythema dose. The skin erythema dose is 300 to 400R mean exposure radiation from pantomograph 90mR in treatment of oral cancer fraction of total dose given in each appointment is in range of 150 rads umbra image clearity penumbra dull zone the distance of safe light from working area in dark room is 4 feet a typical full mouth set of radiograph involves 21 films including 3rd molar horizontal angulation of beam primarily influence the degree of overlapping of images of crown at inter proximal space radiation exposure is less for panoramic radiography compared to ct scan. it is highest for arthography.

smv gives diagnostic information about zygoma zygomatic arche and mandible. This film is taken with SOURCE BELOW MANDIBLE and FILM ABOVE THE HEAD WATERS VIEW one of best films for radiographic diagnosis of mid facial fracture cervical burn out refer to diffuse radiolucent area with ill defined border that may be apparent radiographically on mesial or distal aspect of teeth in cervical region between cervical edge of enamel cap and crest of alveolar ridge. It is caused by normal configuration of affected teeth (the cemento enamel junction which result in decrease x say absorption in those areas if tube head is directed at floor it is called as plus angulation and if toward ceiling it is minus angulation excessive vertical angulation causes foreshortened images while insufficient angulation causes elongated images

colimation donot reduce amount of radiation received by exposed tissue but reduce the radiation to surrounding tissue due to x ray beam divergence.

Filteration reduce patient dose decreases contrast and decreases density of the film. It increases penetration quality of beam by absorbing longer wavelength x rays so they will be less penetrating also

half value layer is an indicator of quality of an x ray beam

charged couple device consist of silicon chip with active array of rows and column called pixel (picture element ) these pixels are analogous to silver crystal in conventional film but are 80 percent more sensitive to radiation thus reduction in radiation dose to patient all of following are advantages of digital radiography except digital subtraction ability to enhance image size of intra oral sensor patient education answer is c the method of obtaining a digital image similar to scanning a photograph to computer screen is termed as indirect digital imaging direct digital imaging storage phosphor imaging answer is a the storage phosphor imaging is wireless digital radiography system. Here resuable imaginin plate coating with phosphor is used instead of sensor with fiber optic cable cementosis in female mandible

lingual development grove on intra oral periapical radiograph is seen as
small pulp chamber size with constriction of canal as compared to contra lateral tooth
constriction of pulp canal only
blurring of root canal
large pulp chamber and widening of canal as compared to contra lateral tooth

answer is a

for computer tomography image is recorded and displayed as matrix of individual blocks called as voxel . Each square of image matrix is called as pixel for image display each pixel is assigned with a CT number representing density . And these number are HOUNSFIELD units. Each constitute a different level of optical density. This scale of relative density is based on AIR. -1000, water 0 and dense bone +1000 to convert two dimensional CT Image into three dimensional image each rectangular solid voxel is dimensionally altered into multiple cuboidal voxel. And this is interpolation. The most extreme form of dens invaginatus is referred as dilated odontome chloroma foci of leukemic cells presenting mass and may behave as localized malignant tumor ARCELIN INTRODUCED SIALOGRAPHY 1913 Calcification OF BASAL GANGLION in Hypoparathyroidism

the periapical radiograph in area of maxilary canine shows Y LINE OF ENNIS a radio opaque line formed by super imposition of floor of maxilary sinus and nasal cavity in panoramic smiling appearance when chin is tilted downward and frowning appearance when chin is tilted upward narrow angle tomography is called zonography with linear tomograms there are some deficiency as compared with tomograms produced by other typeof movements as with linear tomogram there appear streaks and these streaks are called as PARASITE LINES MACH BAND = INCIPIENT OCCLUSAL CARIES

zygomatic process of maxilla appears as j or u shaped radio opacity located superior to maxilary first molar

the normal healthy alveolar crest is located 1.5 to 2 mm apical to cemento enamel junction of adjacent teeth

brown tumor of hyper para thyroidism is same as that of central giant cell granuloma

on dental radiograph root surface caries appear as cupped out or crater shaped radiolucency just below cemento enamel junction.

On radiograph irregularity were found on roots of lower incisor. It may be
sub gingival calculus
root caries
cej
answer is a

tradetionaly size 2 adult film are used for bite wing from age 7 to 8 year own ward

in ocipitomental view trapnell line run along inferior border of mandible from angle to angle cy just below cemento enamel junction.

On radiograph irregularity were found on roots of lower incisor. It may be
sub gingival calculus
root caries
cej
answer is a

tradetionaly size 2 adult film are used for bite wing from age 7 to 8 year own ward

in ocipitomental view trapnell line run along inferior border of mandible from angle to angle

moth eaten appearance is seen in all except osteomyelitis okc osteosarcoma hemorhagic bone cyst answer okc okc is always a well defined radiolucency with moderately or well defined scaloped borders radiolucency with poorly defined ragged border traumatic bone cyst osteomyelitis multiple myeloma peri apical cyst or granuloma when producing radiograph to detect sialolith exposure time should be reduced to half of normal. This help in detecting stone that are lightly calcified parotid gland stone are more radiolucent than submandibular because of low mineral content of parotid secretion 40 percent demineralisation is required for radiographic detection of leison and minimal depth of detectable lesion is 500 micro meter

increasing kvp reduce subject contrast and (longer scale of contrast ) and decreasing kvp increase subject contrast and shorter the scale of contrast

the function of developing solution is to reduce silver halide to crystal of pure silver while function of fixing solution is to stop development and dissolve remaining pure silver crystal

the action of radiation can be direct or indirect. Direct energy of photon is transferred directly to biological molecule and indirect photon is absorbed by water and form free radical which react with biological macro molecule. Gap one phase occur between mitotic and synthetic phase gap two phase between synthetic and mitotic phase

the exposure time needed for regular film is 9 second and exposure time needed for E speed film is0.2 second.

Decrease in kilo voltage result in decrease of energy and increase in image contrast best suited for caries detection or soft tissue calcification

increase in kilo voltage result in increase in energy and decrease in image contrast that is used for perio dontal diagnosis where minute change in bone must be detected.

The field radiated should be collimated such that diameter of field should not be more than 2.75 inches or 7 cm

loss of hair on exposure to radiation is epilation increase in kvp increases density and reduce contrast optimum temperature for developing radiographic film is 68 F dental radiograph film least sensitive to red and yellow and most sensitive to blue and green canthomeatal line joining external auditory meatus to outer canthus of eye trans pharyngeal view is parma or Mc queen trans orbital is zimer projection with advantage of less super imposition

1 second = 60 impulses

thickness of emulsion used for IOPA X RAY FILM is 0.7mm

after taking radiograph an operator should wait zero minutes before entering a room where dental radiograph is taken

permitted divergence in bisecting angle technique is 20 percent

permissible range of magnification in fore shortening is upto 2mm

over head lights are put on after 2 minutes of fixation during processing

filament in x ray tube is heated by
step up high voltage transformer
auto transformer
step down low voltage transformer
ammeter

answer is c

quality of x ray beam is dependent on which component of dental unit
auto transformer
ammter
step down transformer

answer is a

which of following change should be done to change from long scale contrast film technique to short scale contrast film technique while maintaining same density

answer decrease the kvp and increase ma

somatic determinstic or non stochastic that will definitely result from specific high dose of radiation somatic stochastic that may develop and depend on law of chance

the residual biological damage that remain following an exposure to radiation is called direct effect in direct effect cumulative effect tolerance answer c aiims 94 in treatment of oral cancer fraction of total dose in each appointment is in range of 150 rad using b film if exposure is 1R the exposure using d film will be 1/4 R.

badges should be worn by dental technician every 1 month

when taking radiograph for children exposure should be reduced by what percentage of adult
25 percent
50 percent
75 percent
same exposure

answer is b

open ended lead lined cones reduce
intensity of scattered radiation
level of scattered radiation
answer is b

all of following form radiolucent stone except xanthine cysteine allopurinol orotic acid AIIMS-03 Answer is D

the dose required to activate 37 percent of yeast invertase is 60kGY 80kGY 110kGY 30kGY ANSWER : C

only one arm of affected chromosome is broken if radiation exposure occur in
G2
mid S
late S phase
all

answer : d

the radio resistance of many biological factor increases by two or three when irradiation is conducted with reduced oxygen
most radiosensitive cell among following are
a)basal cell of oral mucosa
b)spermatocytes
c)vascular epithelial cells
d)inner enamel epithelium of developing tooth
ans a

after short term irradiation is completed mucosa begin to heal the healing is usually completed by 2 month taste acuity usually decrease by factor of 1000 to 10000 during the coarse of radio activity .

clinically how many types of radiation caries exist.
2 types
3 types
4 types
5 types
answer is b

Oral Medicine and Radiology

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1. A 16 years old female attends your dental practice for an appointment. She is fit and healthy but has a phobia of dental injections. During administration of an inferior dental nerve block she becomes unwell and faints. What do you think is the most likely cause? a) Addisonian crisis b) Cerebrovascular accident c) Hypoglycemic shock d) Vasovagal attack@@@

2. A 60 Y old male with a history of Insulin-dependant Diabetes Mellitus loses consciousness during the course of dental treatment. What do you think is the most likely cause? a) Addisonian crisis b) Anaphylaxis c) Hypoglycemia@@@ d) Hyperglycemia

3. A 45 Y old female develops acute anaphylaxis following administration of amoxicillin. Which one of the following drugs would be the most appropriate first line therapy? a) Adrenaline@@@ b) Chlorpheniramine c) Diazepam d) Hydrocortisone

4. A 4 Y old, child presents with fever, gingival bleeding and extensive oral ulceration in his mouth. His medical history is unremarkable. What would be your most likely diagnosis: a) Candidal infection b) Herpes Simplex infection@@@ c) Herpes Zoster infection d) Paramyxovirus infection

5. A 60 Y old male presents with unilateral facial paralysis, cutaneous lesions of external auditory meatus hearing defects, and vertigo. What would be your most likely diagnosis : a) Bell’s palsy b) Melkerson Rosenthal syndrome c) Moebius syndrome d) Ramsay Hunt syndrome@@@

6. A 60 Y old female presents with recurrent oral and corneal ulceration. Her biopsy specimen reveals sub-epithelial bullae. What is your most likely diagnosis: a) Candidal infection b) Lichen Planus c) Mucous membrane pemphigoid@@@ d) Pemphigus vulgaris

7. A 55 Y old female presents with severe, electrical and shocking pain in her right cheek triggered by light touch. Clinical examination does not reveal any local cause. Which drug is most likely to be effective for her? a) Baclofen b) Carbamazepine@@@ c) Ergotamine d) Paracetamol

8. Which one of the following is the least likely indication for antibiotic prophylaxis to prevent bacterial endocarditis a) Congenital heart disease b) Diabetes mellitus@@@ c) Previous history of endocarditis d) Rheumatic fever

9. A 55 Y old edentulous female presents with an erythematous patch on her palate. She wears complete dentures and has a history of Insulin Dependant Diabetes Mellitus. You make a diagnosis of Denture stomatitis. Which drug is most likely to be effective for her? a) Augmentin b) Hydrocortisone c) Ibuprofen d) Miconazole@@@

10. A 35 Y old female presents with clicking in her right temporomandibular joint for the last six months. She does not have any pain or limitation of her mouth opening. Clinical examination does not reveal odontogenic cause. What does this condition most likely represent? a) Ankylosis of temporomandibular joint b) Fracture of the mandibular condyle c) Internal derangement of temporomandibular joint@@ d) Rheumatoid arthritis

11. Which one of the following conditions is least likely to be associated with immunosuppression : a) Acromegaly@@ b) Agammaglobulinemia c) Anemia d) Diabetes mellitus

12. Bone pain, renal calcinosis , and giant cell jaw lesions are most likely to be seen in which one of the following disorders? a) Acromegaly b) Fibrous dysplasia c) Hyperparathyroidism@@ d) Hyperthyroidism

13. A 55 Y old female presents with a non-healing ulcer on the lateral border of her tongue. The ulcer has not responded to local measures. You suspect a squamous cell carcinoma. Which type of investigation would you perform for her? a) Excisional biopsy b) Exfoliative cytology c) Immunoflourescence d) Incisional biopsy@@

14. Which one of the following statements regarding cluster headaches is least likely to be true? a) Affects mid-face & circum-orbital areas b) Causes nasal stuffiness & facial flushing c) May mimic anterior maxillary tooth ache d) Mostly affects elderly females

15. A 40 Y old gentleman with a 6 months history of trauma to his face and complains of slight burning in his temporal area accompanied by increased sweating. What is the most likely diagnosis? a) Bell’s palsy b) Cluster headache c) Frey’s syndrome d) Postherpetic neuralgia

16. Which one of the following terms is most appropriate to describe pain occurring at the site of nerve injury? a) Analgesia b) Anesthesia c) Causalgia@@ d) Hypesthesia

17. A 45 Y old female presents with a 6 months history of recurrent mealtime swelling and pain in her right submandibular region. Clinical examination does not reveal any dental abnormality. What is the most likely cause of her symptoms? a) Lymphadenitis b) Sia lolithiasis@@ c) Sialometaplasia d) Sialorrhea

18. A 55 Y old male presents with hemorrhagic crusting of his lips following a course of antibiotic therapy. He does not have any systemic manifestations.What would be your most likely diagnosis? a) Anaphylaxis b) Bechet’s syndrome c) Erythema multiforme@@ d) Lichen Planus

19. A 25 Y old female with a history of betel quid chewing presents severe limitation of mouth opening. Clinical examination reveals palpable white fibrotic bands in her buccal mucosa bilaterally. What would be your most likely diagnosis? a) Oral submucous fibrosis@@ b) Lichen planus c) Temporomandibular joint ankylosis d) Verrucous carcinoma

20. Which one of the following conditions is least likely to be associated with an increased risk of oral cancer a) Actinic cheilosis b) Erythroplakia c) Leukoedema@@ d) Leukoplakia

21. Perioral melanin pigmentation and intestinal polyps are most likely to be seen in which one of the following conditions? a) ACTH therapy b) Peutz Jegher’s syndrome@@ c) Gorlin Coltz Syndrome d) Addison disease

22. All of the following are associated with low complement levels except? a) Lupus nephritis b) Mesangio capillary glomerulonephritis c) Post-infections glomerulonephritis d) Diarrhea-associated hemolytic uremic syndrome@@

23. A fifty year old man presents in emergency ward with central chest pain. On examination his blood pressure is 90/60 mmHg and pulse is 106 per minute. He is pale and sweating profusely.The most likely diagnosis is: a) Esophagitis b) Myocardial infarction@@ c) Pericarditis d) Pleural effusion

24. A twenty year old girl is taking anti tuberculosis treatment. She presents in eye outdoor with visual complaints. The most likely cause of her symptoms is side effect of: a) Isoniazid b) Ethambutol@@ c) Rifampicin d) Pyrazinamide

25. A fifteen year old boy who is diabetic presents with pain abdomen, vomiting and shortness of breath. There is history of fever and sore throat two days back. The most likely cause of his symptoms is: a) Diabetic ketoacidosis@@ b) Gastritis c) Hypoglycemia d) Non ketotic hyperosmolar coma

26. Maximum permissible dose for occupationally exposed fertile women with respect to foetus during gestation period is : a) 0.5 rem@@ b) 1.5 rem c) .25 rem d) 10 rem

27. Maximum dosage for red bone marrow in any 1 year in occupationally exposed individual is : a) 1 rem b) 5 rem@@ c) 10 rem d) 15 rem

28. SI unit of absorbed dose of radiation is : a) Roengton b) Gray@@ c) Rad d) Curie

29. Exposure time needed for regular and E speed film is : a) 9 sec and 0.2 sec@@ b) 5 sec and 0.4 sec c) 7 sec and 0.3 sec d) 8 sec and 0.4 sec

30. Safe light should be at what distance from working area ? a) 4 feet@@ b) 5 feet c) 6 feet d) 2 feet

31. When viewing a wet dental x ray film the image appear blurreed this is because of ? a) Light ray refracting through film of water before reaching the eye b) Light ray reflecting of surface of water film c) Swelling of emulsion with water d) Presence of double emulsion@@

32. It is best to retain dental radiographs for how many years ? a) 2 years b) 4 years c) 6 years d) Indefinitely@@

33. After processing a film, you notice that it appears brown in color. What is the most likely cause? a) Solutions are too strong b) Solutions are too weak c) Fixing time was not long enough@@ d) Fixing time was too long

34. Increasing the kilovoltage (kVp) causes the resultant x-ray to have : a) Decreased density b) More latitude c) A shorter scale of contrast d) A longer scale of contrast@@

35. Which of the following errors in radiographic technique is the most likely reason that an image on a radiograph would appear elongated ? a) Too much vertical angulation b) Too little vertical angulation@@ c) Incorrect horizontal angulat ion d) Beam not aimed at center of film

36. Image magnification may be minimized by : a) Using a short cone b) Placing the film as far from the tooth as possible c) Using a long cone@@ d) Shortening the exposure time

37. Suppose that in a periapical examination of the mandibular incisor region, an exposure time of 1/4 second and focus-film distance of 8 inches were used. If you increase the focus-film distance to 16 inches, what would be the new exposure time required to produce the same density in the radiograph? a) 1/2 second b) 1 second@@ c) 2 seconds d) 4 seconds

38. Resolution is expressed in terms of : a) Line pairs per cm@@ b) Dots per inch c) Gray d) None of the above

39. Digital radiography requires less radiation than conventional radiography because : a) The sensor is larger b) The exposure time is increased c) The sensor is more sensitive to x-rays@@ d) The pixels sense transmitted light quickly

40. Which of the following projections is best for examination of fractures of the zygomatic arch? a) Waters projection b) Submentovertex projection@@ c) Reverse Towne projection d) Lateral cephalometric projection

41. X-ray beam is relatively insensitive to ? a) White light b) Blue and green light c) Red light d) Yellow and red light@@

42. Radiolucent portion of x ray is formed by ? a) Silver particles@@@ b) Silver bromide crystals c) Silver nitrate crystal d) Potassium bromide crystals

43. The compton effect is seen when : a) Electron hit the target b) X-ray interact with matter@@ c) X-ray fall on photo graphic film d) The film is exposed to developing solution

44. What is function of filteration while taking radiograph ? a) Remove short wavelength phtons b) Remove portion of long wavelength photons@@ c) Increase radiation dose to patient d) To increase scatter of secondary radiation

45. Compared to round collimator use of rectangular collimator reduce patient skin surface exposed by : a) 15 % b) 30 % c) 45 % d) 60 %@@@

46. 1st step in developing film is : a) Stirring the solution@@@ b) Washing of film c) Dip in developer d) Dip in fixer

47. The optical density of gross fog typically is : a) 0.6 to 3 b) 0.2 to 0.3@@@ c) 0.2 to 0.4 d) 0.6 to 4

48. The radiation generated at the anode of the x-ray tube is called: a) Primary radiation@@ b) Scattered radiation c) Potential radiation d) Reverse radiation

49. Which of the following errors in radiographic technique is the most likely reason that an image on a radiograph would appear elongated? a) Too much vertical angulation b) Too little vertical angulation@@ c) Incorrect horizontal angulation d) Beam not aimed at center of film

50. The lingual developmental groove, on an intra-oral periapical radiograph is seen as: a) Small pulp chamber size, with constriction of the canal as compared to the contralateral tooth@@@ b) Constriction of the pulp canal only c) Blurring of the root canal d) Larger pulp chamber size and widening of the canal, as compared to the contralateral tooth