Aiims 2010 November 2010 Dental

DENTAL

Speed Madurai | Speed Bhubaneswar | Speed Vijayawada | Speed Ahmedabad | Speed Lucknow

DENTAL

AIIMS NOVEMBER 2010

ANSWER DISCUSSION

THIS BOOK IS

DEDICATED

TO

DENTAL STUDENTS

“There is no secret ingredient but you“

(From the hollywood movie “Kung Fu Panda“)

As I pen these words now, a feeling of relief and exitement goes through my mind. With hard work,

prayers of my parents and wellwishers and blessings of Lord Almighty, I have been able to achieve my dream

a post graduate seat at one of the best institutes in India.

I would like to share a few words regarding this eventful journey. Having narrowly missed a PG seat through

State entrance examination due to indecipherable quota and roster system and thrownaway a PG seat in Manipal

University simply because I can't afford the tuition fees, and having missed a PG seat through COMEDK 2009

by just one mark, I made up my mind to be determined and focussed to achieve my goal in the simplest way

possible to go for a good rank that remains immune to all the obstacles and what I have achieved now has

never occurred even in the wildest of my dreams. My parents, my brother and my relatives have been a constant

source of encouragement and moral support.

Getting to the point, dental post graduate entrance examination has become more unpredictable in

recent years and I got the first hand experience of it when I appeared for the All India Dental PGEE 2009.

Shocked at the reality and my preparation level, I decided to up the ante to be in the race. The most important and

significant thing which I realised was that solving the previous year's medical papers is equally or sometimes

more important as compared to dental papers. It helped me to know and learn about numerous intricate and

complicated things in General Medicine, Pathology, Pharmacology, Biochemistry and Physiology. But to go to

that level I should be confident with the dentistry subjects and that's what I got by preparing it during the initial

stages of my preparation.

It's not possible to read each and every line from all standard textbooks, but what can be done is

having a clarity in basic concepts and reading all the important topics from textbooks. Solving as many MCQs as

possible before reading the theory helped me in gaining an insight in what topics and areas importance must be

given and in what possible ways questions may be asked. Being clear about the basics helps to save precious time

in reading and understanding complicated topics.

Discussing on online forums helps in clearing doubts, knowing some entrirely new things which you may not be

familiar with but others may have an idea about or even well versed in them.

As much as working hard, it's equally important to relax and not to lose your cool even in most frustrating

circumstances when nothing goes right.

It would be fitting here to thank Dr.Vinayak Senthil, Director, Speed Medical Institute and Dr.

Senthil Moorthy, Co-Ordinator of dental faculties and all the faculty members for their constant motivation and

inspirational words. I am grateful to my Alma Mater, St. John's Matriculation HSS, Chennai and SRM

University, Chennai for being the backbone of my progress throughout my school and college days and to my

friends, who always lend a helping hand, motivate me and take pride in my achievements. Last, but never the

least, I am grateful to my parents for making me what I am today and my sweet brother who keeps my energy

levels always high. Hard work always pays, Later if not sooner.

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Letters to Readers

Wishing you all the bestR. Suresh

AIIMS 2009, Rank - 1

R. Suresh

AIIMS 2009, Rank - 1

Speed Highlights

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Sixty Five Expert Faculty members will conduct the classes.

Exhaustive study materials containing more than 10,000 salient MCQs will be

discussed & analysed.

Interactive discussion & clarification of doubts.

Twenty five topic-wise Exams covering more than 2500 MCQs.

Seven Revision Tests covering more than 2000 MCQs.

Special Classes for House Surgeons, Video Lectures for students on their duty

days.

Entrance Exam Study Room, Chat Room for all registered candidates.

Group discussion with Online &Audio Visual Multimedia facilities.

Interaction with Expert Faculty members from other states.

Total of 500 working hours.

Classes will be held on ALL SUNDAYS & SECOND SATURDAYS

(REGULAR COURSE) at Chennai, Bangalore, Coimbatore and Hyderabad.

Fully equipped MEDICALLIBRARYwith all Textbooks and MCQs Books.

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Regular course for MDS will be conducted fromApril to December on all Sundays and Second Saturdays.

Duration period : April - December

First Class : 10 th April 2011

MDSDENTAL

Duration period : April - December

First Class : 3 rd April 2011

MDSDENTAL

SPEED DENTAL AIIMS NOVEMBER 2010 _ Answer Discussion

SPEED 1

1. Z score indicates a. normal

b. binomial

c. chi score

Answer: a. normal

Z-score Explanation: Thus z is a measure of how far away a measurement is from the mean, measured in standard deviations. Calculation:

z = (X - X-bar)/S

Where X is a measured value, X-bar is the mean of all measured values and S is the standard deviation of all measured values.

Example

John gets a mark of 64 in a physics test, where the mean is 50 and the standard deviation is 8.

Jane gets a mark of 74 in a chemistry test, where the mean is 58 and the standard deviation is 10.

John's z = (64 - 50) / 8 = 1.75

Jane's z = (74 - 58) / 10 = 1.6

Although Jane's score is higher, John's score is further above the mean, and it might be concluded that John has achieved greater success.


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Comments: The z-score provides a simple measure by which different measures can be compared in terms of their deviation from the mean. This is often called standardization. The z-score in use generally assumes parametric data.

2. Standard error of mean. All the following is true except

a. Increases as the sample size increases b. decreases as the sample size increases c. Is independent of sample size

Answer: b

Explanation:

Standard error of mean decreases as the sample size increases as the level of significance decreases along with the increase in sample size (i. e) more the difference, lesser the sample size and lesser the difference more is the sample size required.

3. Which of the following is the impact indicator for evaluation of ASHA’s performance?

a. Number of ASHAs trained

b. Infant mortality rate

c. Number of ASHA s attending meeting

d. Percentage of institutional deliveries

Answer: b

Explanation and Comments:


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MONITORING AND EVALUATION

Government of India has set up following indicators for monitoring ASHA. Process Indicators:

Number of ASHAs selected by due process; Number of ASHAs trained, % of ASHAs attending review meetings after one year;

Outcome Indicators: % of newborn who were weighed and families counseled; % of children with diarrhoea who received ORS, % of deliveries with skilled assistance; % of institutional deliveries, % of JSY claims made to ASHA, % completely immunized in 12-23 months age group. % of unmet need for spacing contraception among BPL; % of fever cases who received chloroquine within first week in an malaria endemic area;

Impact indicators:

IMR; Child malnutrition rates; Number of cases of TB/leprosy cases detected as compared to previous year. While MIS to be setup for NRHM will ensure timely information on key inputs and process indicators, information on impact indicators will come through DRHS being planned for RCH-II. During bi-monthly meetings, ANM should get information from ASHAs regarding the progress made and consolidate the report at PHC by Medical officer.


SPEED 4

CONSERVATIVE DENTISTRY AND ENDODONTICS

4. A dentin primer

a. Etches the dentin

b. Increase the surface energy and wets the dentin surface

c. Removes the smear layer

d. Bonds with composite

If less than 3mm, the dressing will probably break and fall out.

Reference: http://faculty.ksu.edu.sa/alobaida/Pages/mcqinfection.aspx

http://www.dentistry.bham.ac.uk/ecourse/pages/page.asp?pid=80

5. Magnification allowed in working length determination by paralleling technique

a. none

b. 1mm

c. 2mm

d. 3mm Answer: b. 1mm Explanation:

Initial working length – The tooth is measured on a good preoperative radiograph taken using the


SPEED 5

Paralleling technique.

Tentative working length – As a safety factor, allowing for image distortion or magnification at least 1mm is subtracted from the initial measurement for determining tentative working length.

Reference: Ingle 5th edition, pg: 515

6. What is the depth of etching in enamel?

a. 0.5 – 5 µm

b. 5- 50 µm

c. 50 – 500 µm

d. 500 – 1000 µm Answer: b. 5- 50 µm

Explanation:

Acid etching removes about 10 µm of the enamel surface & creates a micro porous layer from 5- 50µm deep.

Ref: James Summit 3rd edition, pg:210

8. The protaper F2 series Gutta percha when cut 1 mm in apical position of canal of the diameter of the tip of GP point is

a. 0.29 mm

b. 0.30 mm

c. 0.31mm

d. 0.33 mm


SPEED 6

Answer: d. 0.33 mm

Explanation:

Finishing files F1, F2, F3 are marked with a yellow, red & blue identification rings, respectively. The finishing files have a fixed taper in the first 3mm from D0 to D3 .

F1 – 7% taper

F2 – 8% taper

F3 – 9% taper

Over the remaining length, reverse taper can be found. These finishing files have matching GP points for obturation.

As the tip diameter of F2 is 0.25mm & its taper in apical 3mm is 8%, when 1mm is cut in the apical portion, resulting tip diameter will be 0.33 mm (i.e. 0.25 + 0.08) as the raise in taper in this will be 0.08mm/mm of GP.

Ref: DCNA – Jan 2004. Vol 48.No 1,pg: 98.

9. Why etchant is preferred in gel form than solution?

a. better control over placement

b. easily rinsable

c. increased concentration of acid in that area

d.

Answer: a. better control over placement

Explanation:


SPEED 7

An acid gel is generally preferred over a liquid because its application is easier to control.

Ref: James Summit 3rd edition, pg: 210.

10. Pulp tissue closely resembles

a. neural tissue

b. loose connective tissue

c. granulation tissuevascular tissue

Answer: b. loose connective tissue

Explanation:

Pulp tissue closely resembles loose connective tissue. Pulp polyp closely resembles granulation tissue.

11. An apical third fracture of the root will most commonly?

a. remain vital and functional

b. ankylosed

c. will require extraction

d. iscoloration of the teeth

Answer: a. remain vital and functional

Explanation:

Mid root & Apical root fractures:

Pulp necrosis occurs in 25% of root fractures. In the vast majority of cases, the necrosis occurs in the coronal segment only, with the apical segment remaining vital.


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Ref: Ingle 6th edition, pg: 1341.

12. In a deep carious lesions, the method to protect pulp while etching

a. calcium hydroxide liner

b. light cure resin modified GIC

c. cavity varnish

d. chemfill

Answer: b. light cure resin modified GIC.

Explanation:

RMGIC is used to seal the deep dentin. After light curing, it can be etched along with the rest of the dentin.

13. Salivary microorganism content

a. 750million /ml

b. 800 million /ml

c. 87million/ml

d. 43million/ml

Answer: a. 750million /ml

Explanation:

Saliva of a normal individual contains approximately 750 million microorganisms / ml.

Ref: Text book of Oral Microbiology & infectious disease, pg:231.


SPEED 9

14. A patient is with necrotizing pulp due to trauma with periapical rarefaction & with closed pulp. The percentage of viable micro organisms obtained in culture is

a. 10%

b. 40%

c. 70%

d. 80 %

Answer: a.10%?

Explanation:

When the root canals of intact teeth with necrotic pulp were cultured in one study, strict anaerobes accounted for more than 90% of the bacteria.

So, if anaerobic culture is performed, percentage of viable micro organisms obtained will be around 90%.If aerobic culture is performed, it will be around 10%.But the question is vague here & so the ans is uncertain.

Ref: Cohen 9th edition, pg 582.

15. All the following about dentin conditioner are true except?

a. Increase free surface energy of dentin

b. Bonds composite to dentin

c. Removes smear layer.

Answer: a. Increase free surface energy of dentin

Explanation:


SPEED 10

Complete or partial removal of the smear layer can be achieved by applying acidic or chelating solutions, called conditioners. The more acidic and aggressive the conditioner, the more completely the smear layer and smear plugs are removed. Strong acids not only remove the smear layer, but they also demineralize intact dentin, remove smear plugs to a depth of 1 to 5µm and widen the dentinal tubule orifices. Contemporary etch and rinse adhesives usually use a 30% to 40% phosphoric acid gel for the conditioning step. Alternatively, maleic, nitric, citric and tannic acids may be used in varying concentrations. A polyalkenoic acid conditioner used in GIC restorative techniques also provides clean dentin surfaces, although without substantial dentin demineralization and without rendering dentinal tubules patent.

The high protein content exposed after conditioning with acidic agents is responsible for the low surface free energy of etched dentin (44.8 dynes/cm), which differentiates it from etched enamel.

Reference:

Operative dentistry – James Summit 3rd edition, pg: 191,212.

Also refer the explanation for Q.1.

PERIODONTITIS 16. After prophylaxis and pumice polishing, the time taken for plaque to develop

a. within few minutes

b. after 1 hr

c. 2-4 hr

d. 0.5 – 1 hr.

Answer: a


SPEED 11

Explanation:

Within nano seconds after tooth polishing, acquired pellicle covers the tooth surface. Bacteria adheres to this pellicle within seconds after prophylaxis. Among the options, the appropriate answer is - within few minutes

Within 2-8 hrs – streptococci saturate the pellicle

After 1 day- organization of plaque is completed to form BIOFILM

First 24 hours- plaque growth is negligible clinically. After 3 days-plaque growth increases at a rapid rate. Microbial generation time:1 hour for initial plaque, 12 hours for 3 day old plaque

Reference: Carranza 10th ed pg no 140,141,145

17. The following condition do not create gingival defects necessitating gingivoplasty except

a. ANUG

b. Desquamative gingivitis

c. Erosive lichen planus

d. Acute herpetic Gingivostomatitis

Answer: a

Explanation:

ANUG- clinically,Punched out crater like depressions at the crest of the interdental papilla, covered by a pseudomembrane, seperated from the adjacent gingiva by linear erythema is seen. Healing of ANUG usually leads to restoration of the normal gingival contour. But, if there is severe loss of interdental bone, or if entire papilla is lost, healing results in the formation of shelf like gingival margin, which favours


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plaque accumulation and is of esthetic concern. This defect is corrected by gingivoplasty

Desquamative gingivitis- first reported in 1894.

Term was coined in 1932 by Prinz

Diseases clinically presenting as desquamative gingivitis are Lichen Planus, Cicatricial Pemphigoid, Bullous Pemphigoid, Pemphigus Vulgaris, Linear Iga Diseadse, Dermatitis Herpetiformis, Lupus Erythematosus, Chronic Ulcerative Stomatitis

Lichen planus, Cicatricial pemphigoid- account for 95% of cases

All these desquamative lesions do not cause any gingival deformity, hence does not require any surgical reshaping procedure like gingivoplasty

Acute herpetic gingivostomatitis- in the occurinitial stage- discrete spherical grey vesicles . After 24 hours, vesicle rupture to form painful small ulcers with a red elevated halo like margin and a depressed yellowish or grayish white central portion-. Course of the disease is usually 7-10 days. It heals without scarring. Hence does not require gingivoplasty.Treatment- Acyclovir 15mg/kg 5 times daily for 7days

Reference: Carranza 10th ed pg no 391-392,398-399, 707-711

18. A periodontal pocket of 8 mm deep having the junctional epithelium coronal to the CE junction

a. an infrabony pocket

b. a pseudopocket

c. a true periodontal pocket

d. a furcation involvement


SPEED 13

Answer: b

Explanation:

Normally in health, the junctional epithelium is at the level of CEJ. When there is a pocket of 8mm, with the JE at or coronal to CEJ, it implies it is a false pocket or gingival pocket or pseudopocket.

Pocket is a pathologically deepened gingival sulcus

In a pseudopocket, the deepening occurs as a result of coronal migration of gingival margin

In a true pocket, deepening is due to an apical shift in the JE, ie, the JE is apical to the CEJ

Infrabony pocket is also a type of true pocket, wherein base of pocket is apical to the crest of alveolar bone. It is usually associated with vertical or angular bone loss. Transseptal and periodontal ligament fibres are arranged obliquely. In a suprabony pocket, the base of the pocket is coronal to the crest of the alveolar bone. Patern of bone destruction is usually horizontal with the transseptal and PDL fibres arranged horizontally

Furcation involvement also results in a true pocket

Reference: Carranza 10th ed ,pg no 434, 446-448

19. According to Glickman, maximum plaque formation occurs by

a. 7 days

b. 15 days

c. 30 days

d. 60 days


SPEED 14

Answer: b

Explanation:

Clinically early undisturbed plaque formation on teeth follows an exponential growth curve. During the first 24 hours, plaque growth is negligible from a clinical viewpoint. During the next 3 days, plaque growth increases at a rapid rate. After 4 days, 30% of the tooth is covered with plaque. As per the experimental gingivitis model curve, it is seen that gram positive cocci begin to saturate and reach a peak at about 8-10 days and then reach a plateau. Gram negative rods reach a peak by the 10 th day and then attain a plateau. Spirilles and spirochetes begin appearing from 7 th day, reach a peak by 12-13 th day and then reach a plateau.

Summing these findings, it would be apt to choose 15 days as the answer

Normally in experimental subjects, to induce gingivitis, subjects are made to refrain from oral hygiene for 7-21 days. This protocol further substantiates the above answer

Referenc: Carranza 10th ed; pg no 144-146

20. Modification of Koch postulate, to identify the key micro organism was done by

a. Russell

b. socransky

c. Glickmann

d. vermillon

Answer.b

Explanation:


SPEED 15

In 1879, Robert Koch, developed the postulates, by which a microorganism is identified as a causative organism which stipulates the following

Must be routinely isolated from diseased individuals Must be grown in pure culture in the lab Must produce a similar disease when inoculated in susceptible laboratory animals Must be recovered from lesions in diseased laboratory animal

For periodontitis, these postulates could not be applied due to

1. Inabilitiy in culturing the periodontal pathogens

2. difficulty in defining sites of active disease

3. lack of good animal model for the study of periodontitis

Hence Koch’s postulates were modified BY SIGMUND SOCRANSKY, which specifies the following criteria

1. Must be associated with the diisease as seen as an increase in the no of organisms at the diseased sites

2. Must be decreased in sites that show clinical resolution after treatment

3. Must demonstrate a host response in the form of cellular or humoral response

4. Must be capable of causing disease in experimental animals

5. Must demonstrate virulence factors responsible for destruction of periodontium

RUSSELL gave the PERIODONTAL INDEX in 1956. This index considers both clinical and radiographic findings.Disadvantage is it underestimates the prevalence of disease


SPEED 16

VERMILLON and GREENE gave the ORAL HYGIENE INDEX – SIMPLIFIED IN 1964

Reference: Carranza 10th ed; pg no 155, 120

21. Soft tissue attachment after a flap surgery on a denuded root surface occurs by

a. long junctional epithelium

b. Connective tissue attachment

c. scar formation

d.

Answer: a

Explanation:

Normally, after conventional periodontal surgical procedures, the most common type of healing observed is a long junctional epithelium.

After flap surgery, within the first 24 hours, a blood clot is established between the flap and tooth/ bone. 1-3 days after surgery, epithelial cells migrate over the border of the flap. 1 week after , an epithelial attachment is established by means of hemidesmosomes and a basal lamina. Blood clot is replaced by granulation tissue. 2 weeks after surgery, collagen fibres appear parallel to tooth surface. One month after surgery, fully epithelialised gingival sulcus with a well defined epithelial attachment is seen. Though collagen fibres appear they are only parellely arranged and hence do not contribute to any functional attachment

New attachment is the embedding of new periodontal ligament fibres into new cementum and the attachment of gingival epithelium to a tooth surface previously denuded by disease. This kind of healing does


SPEED 17

not normally occur unless specific procedures like GTR, root biomodification is carried on which ensures that new collagen fibres are formed that get attached perpendicularly to the tooth

After scaling and curettage, healing occurs by long junctional epithelium

When healing occurs by long JE, pocket is not completely obliterated, but it does not permit passage of probe. This long JE is resistant to disease similar to connective tissue attachment

Healing by scar refers to healing by Repair wherein a normal gingival sulcus is reestablished at the same level as the base of the preexisting periodontal pocket. There is no gain in attachment.

Reference: Carranza 10th ed pg no 935-936, 912, 632-634

22. Radiographic appearance of Chronic gingivitis

a. Normal bony contour

b. Horizontal bone loss

c.. Vertical bone loss

d. increased bone density

Answer: a

Explanation:

Chronic gingivitis is a pathology involving only the soft tissues. Hence it is not associated with any radiographic change. A normal bony contour is seen

When the inflammation extends to the bone as in periodontitis, it can be visualized on a radiograph. Bone destruction is seen on a radiograph


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only when atleast 30% of the bone is lost. Hence radiographs are highly specific but are not sensitive.

Reference: Carranza 10th ed , pg no 563-566

23. All are true about Kochs Postulates except?

a. The organism can be isolated from disease

b. pure culture obtained

c. organism can be isolated from diseased organism

d. the isolated organism may or may not produce disease.

Answer: d

According to Koch postulates, the isolated organism should necessarily produce disease when inoculated in laboratory animals

In 1879, Robert Koch, developed the postulates, by which a microorganism is identified as a causative organism which stipulates the following

Must be routinely isolated from diseased individuals Must be grown in pure culture in the lab Must produce a similar disease when inoculated in susceptible laboratory animals Must be recovered from lesions in diseased laboratory animal

Reference: Carranza 10th ed; pg no 155, 120

24. Depth of clinical gingival sulcus?

a. gingival margin to apical of J.E

b. gingival margin to apical penetration of probe


SPEED 19

c. crest of alveolar bone

d. gingival margin to CEJ

Answer: b Explanation: The clinical probing depth is the distance to which a probe penetrates into the pocket, i.e the distance from the gingival margin to the apical end of the probe. The depth of penetration of the probe depends on size of probe, force of introduction, direction of penetration, resistance of tissues, convexity of crown. In animals, in health, probe penetrated to 2/3 rd of the epithelium. In gingivitis, the probe stopped 0.1 mm short of the apical end in periodontitis, the probe tip consistently went past the apical cells of junctional epithelium

In humans, the probe penetrates the most coronal fibres of the connective tissue attachment. In a periodontal pocket, the depth of penetration of the probe apical to the JE is 0.3 mm

Thus penetration of the probe is highly variable. Hence the depth of clinical gingival sulcus is the distance between the gingival margin and apical penetration of probe. The probing depth of a clinically normal gingival sulcus is 2-3mm

The biologic depth is the distance between the gingival margin and base of the pocket (coronal end of junctional epithelium)

Under absolute conditions, depth is 0 mm. Histologic depth is 1.8mm with variations between 0-6mm

Reference: Carranza 10th ed; pg no 46-47, 551-552

25. The defect in Localised Juvenille periodontitis is?

altered neutrophil chemotaxis


SPEED 20

Ans: Patients with aggressive periodontitis display functional defects of polymorphonuclear leukocytes and monocytes.

Explanation:

These defects include

impaired chemotactic attraction of PMN to the site of infection inability to phagocytose and kill microorganisms hyperresponsive monocyte phenotype, leading to increased prostaglandin production and hence increased connective tissue destruction or bone loss

PEADODONTICS 26. The root resorption in primary central incisor tooth starts at

a. 2 y

b. 4 y

c. 3 y

Answer: a

Explanation:

Resorption is believed to start immediately after root completion.

The following chart shows when primary teeth (also called baby teeth or deciduous teeth) erupt and shed. It's important to note that eruption times can vary from child to child.

Primary Teeth Development Chart

Upper Teeth When tooth emerges

When tooth falls out

Central incisor 8 to 12 months 6 to 7 years


SPEED 21

Lateral incisor 9 to 13 months 7 to 8 years Canine (cuspid) 16 to 22 months 10 to 12 years

First molar 13 to 19 months 9 to 11 years Second molar 25 to 33 months 10 to 12 years Lower Teeth Second molar 23 to 31 months 10 to 12 years First molar 14 to 18 months 9 to 11 years Canine (cuspid) 17 to 23 months 9 to 12 years

Lateral incisor 10 to 16 months 7 to 8 years Central incisor 6 to 10 months 6 to 7 years

Ref: Chronology table (Logan and Kronfeld 1933)-Pediatric Dentistry by MS Muthu and N Sivakumar

27. In a 6 yr old boy, the best way to diagnose caries is

a. past caries experience

b. snyder s test

c. mother s past caries experience

d. sibling s caries experience

Answer: a.

Explanation:

Each individuals past caries experience best helps to predict or diagnose caries.

Synders test only measures acid production. The Snyder Test is used to determine a person’s susceptibility to dental caries (cavities). The susceptibility is correlated with acid production that is assumed to result from fermentation by


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cariogenic Lactobacillus species on the teeth or in other areas of the mouth.

The Snyder Test agar contains 2% glucose and the pH indicator bromcresol green. The pH of the agar is ~ 4.8, which inhibits the growth of most organisms, but it is ideal for acidophiles such as Lactobacillus species. Saliva samples are inoculated into the tubes and allowed to incubate. If Lactobacillus is present in the saliva, it will ferment the glucose and produce lactic acid, causing the pH to drop to ~ 4.4. This causes the bromcresol green to change from green to yellow. A culture demonstrating ayellow color indicates a person is susceptible to the formation of dental caries

Reference: Pediatric Dentistry by MS Muthu and N Sivakumar

28. Deciduous teeth appear light because of

a. dentin is thinner

b. difference in crystalline structure leading to difference in refractive index

c. difference in reflection from adjacent surfaces

Answer: b.

Explanation:

Primary teeth are less mineralized and more porous, hence altering the refractive index. The refractive index is the same as milk and that’s why primary teeth are called milk teeth.


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ORAL AND MAXILLOFACIAL SURGERY

29. Antanalgesia is caused by

a. ketamine

b. Thiopentone

c. Etodimate

d. Propofol

Answer: b

Explanation:

It is applied to the action of a drug which appears to lower the pain threshold even when an analgesic has been previously given

This phemenon has been given by J.Clutton Bruck

The Antanalgesic effect may be related to the ability of those drugs to interfere with the descending inhibitory mechanism through a Gamma aminobutyric acid.

The antanalgesic effect may be related to the ability of those drugs to interfere with the descending inhibitory mechanism through a gamma aminobutyric acid receptor mechanism.

The antanalgesic effect only occurs at low blood levels of barbiturates such as with small induction doses of thiopental or after emergence from Thiopental .

when the blood levels are low Antanalgesia is also noted with the use of Pentobarbital.

Reference: B.J.Med 1963 July 2(129-130)


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30. Which of the following inhalational anaesthetic have analgesic effect?

a. NO 2

b. Sevoflurane

c. Isoflurane

d. Halothane

Answer: a

Nitrous oxide:

Nitrous oxide is a good analgesic even 20% produces analgesia equivalent to that produced by conventional doses of Morphine.

It is a poor muscle relaxant .

second gas effect and diffusion hypoxia occours with Nitrous oxide

N20 has little effect on respiration, heart and BP.

Sevoflurane:

It is a polyfluorinated inhalational anaesthetic.

Induction and emergence from anaesthesia are fast and rapid.

Acceptably good for paediatric patients.

Smooth recovery.


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Isoflurane:

Inhalation anaesthetic that produces rapid induction and recovery.

Heart rate is increased as a result of stimulation of BAdrenergic receptors.

Safer in patients with MI.

Respiratory depression is prominent.

Secretions are slightly increased.

It is a preferred agent in Neurosurgery.

Halothane:

It is a potent anaesthetic but not a good analgesic or muscle relaxant, however it potentiates N.M blockers.

It produces direct depression of myocardial contractility by reducing intracellular Ca conc.

HR is reduced because of depression.

It sensitizes the heart to arrythmogenic action of adrenalin.

It produces greated depression of respiration.

Pharyngeal and laryngeal reflex are abolished early and coughing is suppressed while bronchi dilate ,so it is preferred in asthmatics.

Its use during labor can prolong delivery and increase post partal blood loss.

Hepatitis occurs in susceptible individuals.

Malignant hyperthermia can rarely be induced.


SPEED 26

31. Needle does not pierce one of the following during an Epidural block when approached from midline?

a. Supraspinous

b. Interspinous

c. Posterior longitudinal ligament

d. ligamentum flavum

Answer: C

Anatomy for epidural block:

1. The superior boundry of the cervical epidural space is the fusion of periosteal and spinal layers of dura at the foramen magnum.

2. The cervical epidural space is bounded anteriorly by the posterior longitudinal ligament and posteriorly by the vertebral laminaeand ligamenteum flavum.

3. The vertebral pedicles and inter vertebral foramina form the lateral limits of epidural space.

4. The epidural space contains fat veins arteries ,lymphatics and connective tissue

5. when performing cervical epidural block in the midline after traversing the skin and subcutaneous tissue the needle will impinge on the ligamentum nuchae , which runs between the apices of the cervical spinous process.

6. The inter spinous process that runs between the spinous process is next encountered

A significant increase in resistance to needle advancement signals that the needle is impinging on the dense ligamentum flavum


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A sudden loss of resistance occurs as the needle pierces into the epidural space

Surgical technique:

A 25 Gauge inch needle is advanced in a slow and deliberate manner passing through the ligamentum flavum to enter the epidural space.

32. TMJ capsule is supplied by

a. Maxillary n.

b. Auriculo temporal n.

c. N. to mylohyoid

d. Facial n.

Answer: B

Branches of the auriclulotemporal nerve supply the sensory innervations of TMJ. This nerve arises from the mandibular division on the infratemporal fossa and sends branches to the capsule of the joint.

The deep temporal and massetric nerve supply the anterior position of the joint.

The auriculotemporal nerve a branch of the mandibular portion of the trigeminal nerve provides innervations of the TMJ.

About 75% of the time the massetric nerve, a branch of the maxillarydivision of trigeminal nerve innervates the anteromedial aspect of the capsule of TMJ.

In about 33% a separate branch from V2 comes trough the mandibular notch and innervates the anteromedial capsule .These nerves are


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primarily motor nerves, but they contain sensory fibres distributed to the anterior part of TMJ capsule.

33. Following a bilateral fracture of mandible in the canine region, the anterior segment of the mandible is displaced posteriorly by the action of

a. Anterior belly of digastrics, geniohyoid and genioglossus

b. Thyrohyoid, geniohyoid and genioglossus

c. Mylohyoid, geniohyoid and genioglossus

d. Mylohyoid, geniohyoid and thyrohyoid Answer: a

Explanation:

Bilateral body fractures are also infrequent. The anterior fragment is driven backwards and downwards and the position is maintained by unopposed action of the Genial muscles Geniohyoid and Genioglossus and the inframandibular muscles.The two posterior fragment and prevented from medial displacement by the anterior fragment and from upward displacement by occlusal contactand thus retain a relatively normal position .In a edentulous case the lack of occlusal contact results in severe displacement of the fragments.

Reference: Rowe and Williams Maxillofacial injuries Vol 1

34. A patient presents with swelling in relation to the left maxillary incisor with deep carious lesion, non-restorable having temperature 102F, swelling on left half of the face unable to open the left eye, unable to chew for 48hrs, swelling is soft and rebounds on palpation the treatment is?


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a. Aspiration

b. Incision and Drainage

c. sclerosing agent

d. Antibiotics heat and fluids

Answer: b

Explanation:

The presentation in the question indicates it as a patient suffering from space infection. The clinical features suggestive of canine space infection.

Canine space infection:

Infection of the canine is mostly on the labial side than on the palatal side.

If canine infection perforates lateral cortex of maxillary bone superior to the origin of muscle this space is affected.

infection Involving this space is less common

Involvement is even less in case of nasal infections.

• Patient exhibits swelling lateral to the nose

• obliteration of the nasolabial fold,

• swelling of the upper lip,

• edema occurs in the upper and lower lid that may close the eye

Differential diagnosis of upper face infections


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a. Dacrocystitis with minimal involvement of nasolabial fold

b. Odontogenic cellulitis where the nasolabial fold is effaced.

The treatment of choice for space infection is Incision and drainage:

• Incise in healthy skin and mucosa when possible.

• Incision placed at the site of maximum fluctuance results in a puckered, unesthetic scar.

• Place the incision in an esthetically acceptable area.

• When possible place the incision in a dependent position to encourage drainage by gravity.

• Dissect bluntly with closed surgical clamp or finger, through deeper tissues.

• Place a drain and stabilize it with sutures.

• Consider use of through and through drains in bilateral submandibular space infections.

• Do not leave drains in place for an overly extended period.

• Remove them when drainage becomes minimal.

• Clean wound margins daily under sterile conditions to remove clots and debris.

• Another approach to drainage is the use of computed tomographic (CT) guided catheter


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35. Patient on steroid therapy in order to extract a chronically infected teeth- premedication is

a. Antibiotics

b. Antihistamines

c. Atropine for vagal block

d. Antihypertensives

Answer: a

Explanation:

Dental management of pt with adrenal disease or steroid therapy for non adrenal disease:

• Assess potential for adrenal suppression

• Administer supplemental steroid, proportional to the presumed adrenal suppression and the anticipated stress.

• Taper supplemental steroid doses rapidly over 2-3 days to maintenance levels, unless there is infection, severe pain, or compromised oral intake

• Use appropriate sedation tech. to minimize stress

• Use antibiotic prophylaxis to minimize the risk of infection

Reference: Principle and practice of oral medicine, S. T. Sonis, R. C. Fazio, 2nd edition


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ORAL MEDICINE DIAGNOSIS AND RADIOLOGY

36. A 9 yrs. old child mother comes to dental clinic with the complaint of oral ulceration , fever , and shedding of skin of palms and soles she is giving history of premature shedding of teeth , teething and increased sweating , she is also giving 1 month history of using any new teething gel available in market. The child is suffering from

a. acrodynia

b. pemphigus vulgaris

c. epidermolysis bullosa

d. erosive lichen planus

Answer: a

Explanation:

Chronic mercury exposure in infants and children is termed ACRODYNIA (pink disease, swift disease). The children have cold clammy skin especially on the hands, feet, nose, ears, and cheeks. An erythematous and pruritic rash is present. Severe sweating, increased lacrimation, irritability, insomnia and photophobia, hypertension, weakness, tachycardia, and gastrointestinal upset also may be present. On occasion, these highly irritable children have torn out patches of their hair. Oral signs include excessive salivation, ulcerative gingivitis, bruxism, and premature loss of teeth. Because mercury salts were formerly used in the processing of felt, hat makers in past centuries were exposed to the metal and experienced similar symptoms, giving rise to the phrase “mad as a hatter.”

Comments: Even though oral ulcerations and shedding of skin of palms and soles are seen in pemphigus, epidermolysis bullosa, and


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erosive lichen planus, fever, premature loss of teeth and bruxism is not found in these diseases and the association of these features could be purely coincidental.

Reference: Neville, Damm, Allen, Bouqout, Oral and Maxillofacial Pathology, II edition page no. 273, Elsevier publication 2007 (Reprinted version)

37. Moth eaten appearance is seen in all of the following except

a. Osteomyelitis

b. Osteosarcoma

c. Hemorrhagic cyst

d. Odontogenic Keratocyst

Answer: d. Odontogenic keratocyst

Explanation:

Radiologic differential diagnosis is usually obtained from clues by:

Appearance of lesion Location of lesion Type of periosteal reaction Matrix of lesion Density of lesion Number of lesion

By appearance of lesion, they could be classified as:

Geographic: Destructive lesion with sharply defined border. It implies a less aggressive, more slow growing benign process with a narrow transition zone Moth eaten: Areas of destruction with ragged borders. It implies more rapid growth with high probability of malignancy


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Permeative: Ill-defined lesion with multiple “worm holes” spreading through marrow space with a wide transition zone. It implies an aggressive malignancy.

Both Osteomyelitis and Osteosarcoma show “moth eaten appearance” at various stages. An SBC may have an appearance similar to that of a true cyst, especially a KOT. This is because KOT’s tend to grow along bone with very little expansion and often have scalloped borders similar to those of an SBC. However, KOT’s usually have a more definite cortical boundary, resorb and displace teeth, and occur in an older age group. Because the SBC may remove bone around teeth without affecting the teeth, there may be a tendency to include a malignant lesion in the differential diagnosis. However, maintenance of some lamina dura and the lack of an invasive periphery and bone destruction should be enough to remove this category of diseases from consideration.

Note: Radiographic appearances of a disease should always be correlated with the clinical stages of the disease

Reference: White and Pharaoh, Oral Radiology, Principles and interpretation, Sixth edition, 2009: Elsevier publications.

Other sources: Internet- Bone tumor radiology

38. A periapical radiograph of upper anterior teeth with loss of cementum, increased horizontal anterior bone loss?

a. Hypophosphatasia

b. Vit D resistant rickets

c. Juvenile periodontitis

d. Osteomalacia

Answer: a. Hypophosphatasia


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Explanation:

Hypophosphatasia is a rare metabolic bone disease that is characterized by a deficiency of tissue nonspecific alkaline phosphatase. One of the first presenting signs of Hypophosphatasia may be the premature loss of the primary teeth, presumably caused by a lack of cementum on the root surfaces. Generally, the younger the age of onset, the more severe the expression of the disease. The common factors in all types include the following:

Reduced levels of the bone, liver, and kidney isozyme of alkaline phosphatase Increased levels of blood and urinary phosphoethanolamine Bone abnormalities that resemble rickets

Four types of Hypophosphatasia are generally recognized, depending on the severity and the age of onset of symptoms:

Perinatal Infantile Childhood Adult

The childhood form is usually detected at a later stage and has a wide range of clinical expression. One of the more consistent is the premature loss of primary teeth without evidence of a significant inflammatory response the deciduous incisor teeth are usually affected first and may be the only teeth involved. In some patients, this may be the only expression of the disease. The teeth may show enlarged pulp chambers in some instances, and a significant degree of alveolar bone loss may be seen. More severely affected patients may have open fontanelles with premature fusion of cranial sutures. Affected patients typically have a short stature, bowed legs, and a waddling gait. The development of motor skills is often delayed.


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The perinatal and infantile types are associated with a rather poor outcome. The childhood and the adult forms are compatible with a normal life span

Reference:

1. Neville, Damm, Allen, Bouqout, Oral and Maxillofacial Pathology, II edition, Elsevier publication 2007 (Reprinted version)

2. White and Pharaoh, Oral Radiology, Principles and interpretation, Sixth edition, 2009: Elsevier publications

39. Geniculate neuralgia is the uncommon neuralgia associated with

a. Trigeminal n.

b. Facial n.

c. Optic n.

d. Vagus n.

Answer: b. Facial nerve

Explanation:

Geniculate neuralgia is a condition where a small nerve (the nervus intermedius) is compressed by a blood vessel. This results in severe, deep ear pain which is usually sharp—often described as an "ice pick in the ear"—but may also be dull and burning, and can be accompanied by facial pain. This pain can be triggered by stimulation of the ear canal, or can follow swallowing or talking.

Doctors will typically prescribe treatment with medication before recommending surgery. If surgery is required, UPMC’s neurosurgeons


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may recommend Microvascular Decompression. Microvascular decompression is a surgical procedure that relieves abnormal compression of a cranial nerve.

The intermediate nerve of Wrisberg (the nervus intermedius) is a small sensory branch of the facial nerve (cranial nerve VII) carrying general visceral efferent, special visceral afferent (taste), and general somatic afferent fibers. The cell bodies of the sensory afferents dwell in the geniculate ganglion, and their peripheral axons innervate the inner ear, the middle ear, the mastoid cells, the eustachian tube, and part of the pinna of the ear.

40. Infectious Mononucleosis is caused by

a. Epstein barr virus

b. Cyto megalo virus

c. Human papilloma virus

d. herpes simples virus

Answer: a. Epstein barr virus

Explanation:

Infectious mononucleosis is a clinical syndrome caused by Epstein-Barr virus (EBV, Human Herpes Virus-4). EBV replicates primarily in beta-lymphocytes but also may replicate in the epithelial cells of the pharynx and parotid duct. The typical features of IM include fever, pharyngitis, lymphadenopathy, malaise, and an atypical lymphocytosis. The rarer complications include splenomegaly, hepatomegaly, jaundice, and splenic rupture. Children and young adults are usually affected. The virus is transmitted via intimate contact. Children may acquire the virus through sharing of saliva contaminated fingers, toys or serving spoons. Direct transfer of contaminated saliva may occur in adults following kissing (hence the name kissing disease) or sharing of straws. The incubation period is 4 to 8 weeks


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The Paul-Bunnel test is a serological test that detects heterophile antibodies by agglutination of sheep or horse red blood cells. However in the first week of infection, the false negative rate is as high as 25%. VCA-IgG and VCA-IgM tests are useful in diagnosing patients who have highly suggestive clinical features but negative heterophile antibody test results.

Antibody to Epstein-Barr nuclear antigen (EBNA), while typically not detectable until 6 to 8 weeks after the onset of symptoms, can help distinguish between acute and previous infections. Elevated hepatic transaminase levels may be seen in about 50% of the patients.

Reference: RavikiranOngole, Praveen BN, Textbook of Oral Medicine, Oral Diagnosis and Oral Radiology, First edition; Elsevier publications2010.

41. Hyponatremia with increased total body sodium

a. Nephrotic syndrome

b. Vomitting

c. Diuresis therapy

d. Renal tubular acidosis

Answer: d. Renal tubular acidosis,

Explanation:

There are four types of Renal tubular acidosis

Type 4: Hyperkalemic RTA

Type 4 is also called hyperkalemic RTA and is caused by a generalized transport abnormality of the distal tubule. The transport of electrolytes such as sodium, chloride, and potassium that normally occurs in the distal tubule is impaired. This form is distinguished from classical


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distal RTA and proximal RTA because it results in high levels of potassium in the blood instead of low levels. Either low potassium—hypokalemia—or high potassium—hyperkalemia—can be a problem because potassium is important in regulating heart rate.

Type 4 RTA occurs when blood levels of the hormone aldosterone are low or when the kidneys do not respond to it. Aldosterone directs the kidneys to regulate the levels of sodium, potassium, and chloride in the blood. Type 4 RTA also occurs when the tubule transport of electrolytes such as sodium, chloride, and potassium is impaired due to an inherited disorder or the use of certain drugs.

Drugs that may cause type 4 RTA include

diuretics used to treat congestive heart failure such as spironolactone or eplerenone

angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs)

the antibiotic trimethoprim

the antibiotic pentamidine, which is used to treat pneumonia

heparin

NSAIDs

some immunosuppressive drugs used to prevent rejection

Type 4 RTA may also result from diseases that alter kidney structure and function such as diabetic nephropathy, HIV/AIDS, Addison’s disease, sickle cell disease, urinary tract obstruction, lupus, amyloidosis, removal or destruction of both adrenal glands, and kidney transplant rejection.

For people who produce aldosterone but cannot use it, researchers have identified the genetic basis for their body’s resistance to the hormone.


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To treat type 4 RTA successfully, patients may require alkaline agents to correct acidosis and medication to lower the potassium in their blood.

If treated early, most people with any type of RTA will not develop permanent kidney failure. Therefore, the goal is early recognition and adequate therapy, which will need to be maintained and monitored throughout the person’s lifetime.

Source (internet): kidney.niddk.nih.gov/kudiseases/pubs/tubularacidosis/

Reference: e-Medicine article on Hyponatremia Harrison’s Internal Medicine 17th edition2010Vol

42. A wide eyed patient with increased systolic BP(widened pulse pressure) thin skin and hair,loss of weight, extremely nervous could have

a. hypothyroidism

b. hyperthyroidism

c. hyperparathyroidism

d. hyperpituitirism

Answer: b. hyperthyroidism

Explanation:

Grave’s disease or hyperthyroidism (Thyrotoxicosis) is 5 to 10 times more common in women than in men and is seen with some frequency. It affects almost 2% of the adult female population. Grave’s disease is most commonly diagnosed in patients during the third and fourth decades of life. Many of the signs and symptoms of hyperthyroidism can be attributed to an increased metabolic rate caused by excess thyroid harmone. Patients usually complain about nervousness, heart


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palpitations, heat intolerance, emotional liability, and muscle weakness. The following are noted during clinical evaluation:

Weight loss despite increased appetite Tachycardia Excessive perspiration Widened pulse pressure (increased systolic and decreased diastolic pressures) Warm and smooth skin Tremor Exophthalmos or proptosis.

Reference:

1. Ravikiran Ongole, Praveen BN, Textbook of Oral Medicine, Oral Diagnosis and Oral Radiology, First edition; Elsevier publications2010.

2. Neville, Damm, Allen, Bouqout, Oral and Maxillofacial Pathology, II edition, Elsevier publication 2007 (Reprinted version)

43. A 40 yr old patient withmultiple radiolucency in mandibular anterior region. The teeth are vital the probable diagnosis could be?

a. Cementoblastoma

b. chronic periapical abscess

c. periapical osteofibrosis

d. multiple granulomas

Answer: c. Periapical osteofibrosis

Explanation:


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Synonym for periapical cemental dysplasia - A benign, painless, non-neoplastic condition of the jaws which occurs almost exclusively in middle-aged black females. The lesions are usually multiple, most frequently involve vital mandibular anterior teeth, surround the root apices, and are initially radiolucent (becoming more radio opaque at later stages)

Reference:

White and Pharaoh, Oral Radiology, Principles and interpretation, Sixth edition, 2009: Elsevier publications.

44. An anxious mother of a 8 yr old boy complains of greenish discoloration on the labial margin of the central incisor which can’t be removed by brush it could be?

a. Neonatal line

b. Chromogenic bacteria

c. Calculus

d. none of the above

Answer: b. Chromogenic bacteria

Explanation:

The green discoloration associated with chromogenic bacteria or the frequent consumption of chlorophyll containing foods can resemble the pattern of green staining secondary to gingival hemorrhage. As would be expected, this pattern of discoloration occurs most frequently in patients with poor oral hygiene and erythematous hemorrhagic and enlarged gingiva. The color results from the breakdown of hemoglobin into green biliverdin


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Reference: Ravikiran Ongole, Praveen BN, Textbook of Oral Medicine, Oral Diagnosis and Oral Radiology, First edition; Elsevier publications2010.

Neville, Damm, Allen, Bouqout, Oral and Maxillofacial Pathology, II edition, Elsevier publication 2007 (Reprinted version)

45. Which of the following is true about calcification of teeth?

a. calcification of primary teeth is almost complete at the time of birth

b. calcification of all primary teeth and few permanent teeth complete at birth

c. calcification of all permanent teeth complete at birth

d. calcification of all primary teeth starts around birth

Answer: a. Calcification of primary teeth is almost complete at the time of birth

46. Ehler Danlos syndrome is inherited by a. Autosomal dominant

b. Autosomal recessive

c. X-linked dominant

d. Xlinked recessive

Answer: a. Autosomal dominant,

Explanation:

The pattern of inheritance and the clinical manifestations vary with the type of Ehlers-Danlos syndrome being examined. About 80% of patients have the classical type in either the mild or severe form.


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Classical Ehler Danlos syndrome is inherited as autosomal dominant trait. Typical clinical findings include hypermobility of the joints, easy bruisability, and marked elasticity of the skin. Some patients have worked in circus sideshows as the “rubber” man and the “contortionist” as a result of their pronounced joint mobility and ability to stretch the skin.

The oral manifestations of Ehlers-Danlos syndrome include the ability of 50% of these patients to touch the tip of their nose with their tongue (Gorlin sign). A variety of dental abnormalities have been described, however, including malformed, stunted tooth roots, large pulp stones, and hypo plastic enamel

Reference: 1.Ravikiran Ongole, Praveen BN, Textbook of Oral Medicine, Oral Diagnosis and Oral Radiology, First edition; Elsevier publications2010 2.Neville, Damm, Allen, Bouqout, Oral and Maxillofacial Pathology, II edition, Elsevier publication 2007 (Reprinted version)

47. Radicular cyst is always associated with?

a. Vital teeth

b. Non vital teeth

c. Deep caries

d. Pericoronitis.

Answer: b. Nonvital teeth

Explanation:

Radicular cyst is defined as an odontogenic cyst of Inflammatory origin that is preceeded by a chronic periapical granuloma & stimulation of cell rests of malaseez present in the


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periodontal membrane.

Classification:-

It is classified as follows---

Periapical Cyst:- These are the radicular cysts which are present at root apex.

Lateral Radicular Cyst:- These are the radicular cysts which are present at the opening of lateral accessory root canals of offending tooth.

Residual Cyst:- These are the radicular cysts which remains even after extraction of offending tooth.


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Clinical Features:-

Frequency:- It is most common cystic lesion of jaw comprising about approximately 52.3% of jaw cystic lesions

Age:- Large no. of cases are found in 4th & 5th decades of life after which there is gradual decline.

Sex:- It is more common in males comprising about 58% & in females comprising about 42%.

Race:-White patients are involved with a frequency of about twice that of Black patients.

Site:- It occurs with frequency of 60% in Maxilla. Though it may occur in all tooth bearing areas of both the jaws but preferably it occurs in maxillary anterior region. Upper lateral Incisors and Dense in Dente are usually the offending teeth. It occurs most commonly at apices of involved teeth. They may however be found at lateral accessory root canals.

Gross Features:-

Gross Specimen may be spheroidal or ovoid intact cystic masses, but often they are irregular & collapsed. The walls vary from extremely thin to a thickness of about 5mm. The inner surface may be smooth or corrugated yellow mural nodules of cholesterol may project into the cavity. The fluid contents are usually brown from breakdown of blood and when cholesterol crystals are present they impart a shimmering gold or straw colour.

Clinical Presentation:-


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Smaller radicular cysts are usually symptomless and are discovered when IOPAs are taken with non-vital teeth.

Larger lesions show slowlyenlarging swelling. At first the enlargement is bony hard but as cyst increases in size, the covering bone becomes very thin, despite subperiosteal deposition & swelling exhibits springiness, only when cyst has become completely eroded, the bone will show fluctuation.

In Maxilla, there may be buccal and palatal enlargement Whereas in mandible it is usually labial or buccal & only rarely lingual.

Pain & infection are other clinical features of some radicular cysts. These cysts are painless unless infected. However, complain of pain is also observed in patient without any evidence of infection. Occasionally, a sinus may lead from cyst cavity to the oral mucosa Quite often there may be more than one radicular cyst. Scientists believe that there are cyst prone individuals who show particular susceptibility to develop radicular cysts. Radicular cysts arising from deciduous tooth are very rare.Deciduous tooth which had been treated endodontically with materials containing Formecresol which in combination with tissue protein is antigenic & may elicit a humoral or cell-mediated response like rapid buccal expansion of cyst. On rare occasion, there may be occurrence of parasthesia or there may be pathologic fracture of jaw bone take place. Radiographic Features:-

Intra Oral Peri Apical Radiographs i.e. IOPAs are common radiographs which are used as diagnostic aid from radiological point of view.

Radiographically , Radicular Cysts are round or ovoid radiolucent areas surrounded by a narrow radio-opaque margin, which extends from Lamina Dura of involved tooth. In infected or rapidly enlarging cysts, radio-opaque margins may not be seen. Root resorption is rare but may occur.


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It is often difficult to differentiate radiologically between radicular cysts & apical granulomas.

Radiologic presentation of Radicular Cyst is given in detail as follows --- Periphery & Shape--- Periphery usually have a well defined cortical border. If Cyst is secondarily infected, the inflammatory reaction of surrounding bone may result in loss of this cortex or alteration of cortex into more sclerotic border. The outline of radicular cyst usually is curved or circular unless it is influenced by surrounding structures such as cortical boundaries.

Internal structure--- in most cases, internal structure of radicular cyst is radiolucent. Occasionally, dystrophic calcification may develop in long standing cysts appearing as sparsely distributed, small particulate radio-opacities.

Effects on surrounding structures--- If a radicular cyst is large, displacement and resorption of roots of adjacent teeth may occur. The resorption pattern may have a curved outline. In rare cases, the cyst may resorb the roots of related non-vital teeth. The cyst may invaginate the antrum, but there should be evidence of a cortical boundary between contents of cyst and internal structure of antrum. The outer cortical plates of maxilla and mandible may expand in a curved or circular shape. Cyst may displace the mandibular alveolar nerve canal in an inferior direction.

48. The radiograph of a boy with radiopacity in the apical region in relation to his young permanent incisor having chronic pulpitis

a. apical condensing osteitis

b. radicular cyst

c. peri apical granuloma

d. chronic periodontitis


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Answer: a. Apical condensing osteitis

Explanation:

Early periapical inflammatory lesions may show no radiographic change in the normal bone pattern. The earliest detectable change is loss of density, which usually results in widening of the periodontal ligament space at the apex of the tooth and later involves a large diameter of surrounding bone. At this early stage no evidence may be seen of a sclerotic bone reaction. Later in the evolution of the disease, a mixture of sclerosis and rarefaction (loss of bone giving a radiolucent appearance) of normal bone occurs. The percentage of these two bone reaction varies. When most of the lesion consists of increased bone formation, the term periapical sclerosing osteitis is used, and when most of the lesion is undergoing bone resorption, the term periapical rarefying osteitis is used. The area of greatest bone destruction usually is centered on the apex of the tooth, with the sclerotic pattern located at the periphery. The radiolucent regions may be bereft of any bone structure or may have a faint outline of trabeculae. Close inspection of sclerotic regions reveals thicker than normal trabeculae per unit area. In chronic cases the new bone formation may result in a very dense sclerotic region of bone, obscuring individual trabeculae. Occasionally the lesion may appear to be composed entirely of sclerotic bone (sclerosing osteitis), but usually some evidence exists of widening of the apical portion of the periodontal membrane space.

Reference:White and Pharaoh, Oral Radiology, Principles and interpretation, Sixth edition, 2009: Elsevier publications.

Note: Out of these four choices, only Condensing osteitis will have a radio opaque appearance

49. Maximum Magnification allowed in working length determination by paralleling technique is:

a. none


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b. 1

c. 2

d. 3

Answer: a. 1, (0.5 to 1mm)

Explanation:

The rules of Projection geometry are:

Use as small an effective focal spot as practical Increase the distance between the focal spot and the object by using a long, open-ended cylinder Minimize the distance between the object and the film

The third consideration of projection geometry is clearly violated in paralleling technique and this is the reason why long cones have been used in this technique so that to allow the more central and parallel rays of the beam to the film and teeth and to reduce image magnification while increasing image sharpness and resolution

Reference: White and Pharaoh, Oral Radiology, Principles and interpretation, Sixth edition, 2009: Elsevier publications.

50. Modern radiologic technique employed to detect posterior proximal caries in children is

a. Bitewing with bisecting angle technique

b. Bitewing with paralleling technique

c. Bitewing with RVG

d. Digital OPG

Answer: c. Bitewing with RVG


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Explanation:

Note: Using tabs are not compatible with solid state detectors It is sometimes not possible to use an image receptor holder (with beam aiming device) and achieve these ideal technical requirements particularly with children. Clinicians therefore still need to be aware of the original technique of using a tab attached to the film packet or phosphor plate and aligning the X-ray tubehead by eye

The Bitewing technique (using tabs) can be summarized as follows:

The appropriate sized barrier-wrapped film packet or phosphor plate is selected and the tab attached, oriented appropriately for horizontal or vertical projections. Large film packets/ phosphor plates (31x41 mm) for adults Small film packets/ phosphor plates (22x35mm) for children under12 years. Once the second molar is erupted the adult size is required Occasionally a long film packet/ phosphor plate (53x26 mm) is used for adults The patient is positioned with the head supported and with the occlusal plane horizontal The shape of the dental arch and the number of films required are assessed. The operator holds the tab between thumb and forefinger and inserts the image receptor into the lingual sulcus opposite the posterior teeth The anterior edge of the image receptor should again be positioned opposite the distal aspect of lower canine – in this position, the posterior edge of the film packet extends usually just beyond the mesial aspect of the lower third molar The tab is placed on to the occlusal surfaces of the lower teeth The patient is asked to close the teeth firmly together on the tab As the patient closes the teeth, the operator pulls the tab firmly between the teeth to ensure that the image receptor and the teeth are in contact


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The operator releases the tab The operator assesses the horizontal and vertical angulations and positions the X-ray tubehead so that the X-ray beam is aimed directly through the contact areas, at right angles to the image receptor, with an approximately 50- 80 downward vertical angulation The exposure is made If required, the procedure is repeated for the premolar teeth with a new image receptor and X-ray tubehead position

Reference: Eric Whaites: Essentials of Dental Radiography and Radiology, Fourth edition, Elsevier Publications 2007.

51. Radiolucency between the root apex of vital lateral incisors and canine could be:

a. Globulomaxillary cyst

b. Nasolabial cyst

c. Radicular cyst

d. Nasopalatine cyst

Answer: a. Globulomaxillary cyst,

Explanation:

As originally described, the “Globulomaxillary cyst” was purported to be a fissural cyst that arose from epithelium entrapped during fusion of the globular portion of the medial nasal process. This concept has been questioned, however, because the globular portion of the medial nasal process is primarily united with the maxillary process and a fusion does not occur. Therefore, epithelial entrapment should not occur during embryologic development of this area. Current theory holds that most (if not all) cysts that develop in the Globulomaxillary area are actually of Odontogenic origin


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The “Globulomaxillary cyst” classically develops between the maxillary lateral incisor and cuspid teeth, although occasional Globulomaxillary lesions have been reported between the central and the lateral incisors. Radiographs typically demonstrate a well-circumscribed unilocular radiolucency between and apical to the teeth. Because this radiolucency often is constricted as it extends down between the teeth, it may resemble an inverted pear. As the lesion expands tipping of the tooth toots may occur.

Virtually all cysts in the Globulomaxillary region can be explained on an Odontogenic basis. Many are lined by inflamed stratified squamous epithelium and are consistent with periapical cysts. Some exhibit specific histopathologic features of an Odontogenic keratocystore developmental lateral periodontal cyst or rarelycan be lined by respiratory epithelium because of the close proximity of sinus lining. It also has been theorized that some of these lesions may arise from inflammation of the reduced enamel epithelium.

Reference: 2.White and Pharaoh, Oral Radiology, Principles and interpretation, Sixth edition, 2009: Elsevier Neville, Damm, Allen, Bouqout, Oral and Maxillofacial Pathology, II edition, Elsevier publication 2007 (Reprinted version) publications.

52. Which of the following is the principle of bisecting angle technique?

a. Rule of isometry

b. ALARA

c. SLOB rule

d. none of the above

Answer: a. Rule of isometry,


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The bisecting- angle technique was used often in the first half of the 1900s but has been largely replaced by the paralleling technique. This method may be useful when the operator is unable to apply the paralleling technique because of large rigid sensors or the anatomy of the patient. The bisecting-angle technique is based on simple geometric theorem, Cieszynski’s rule of isometry, which states that two triangles are equal when they share one complete side and have two equal angles. Dental radiography applies then theorem as follows as follows. The receptor is positioned as close as possible to the lingual surface of the teeth, resting in the palate or in the floor of the mouth. The plane of the receptor and the long axis of the teeth form an angle with its apex at the point where the receptor is in contact with the teeth along an imaginary line that bisects this angle and directs the central ray of the beam at right angles to this bisector. This forms two triangles with two equal angles and a common side ( the imaginary bisector).consequently, when these conditions are satisfied, the images cast on the receptor theoretically are the same length as the projected object. To reproduce the length of each root of a multirooted tooth accurately, the central beam must be angulated differently for each root. Another limitation of this technique is that the alveolar ridge often projects more coronally than its true position, thus distorting the apparent height of the alveolar bone around the teeth.


53. Longitudinal radiolucency between central and lateral incisor can be identified as:

a.Nutrient canal

b.artefact

c.fracture

d. None of the above


SPEED 55

Answer: a. Nutrient canal,

Explanation:

Nutrient canals carry a neurovascular bundle and appear as radiolucent lines of fairly uniform width. They are most often seen on mandibular periapical radiographs running vertically from the inferior dental canal directly to the apex of a tooth or into the interdental space between the mandibular incisors. They are visible in about 5% of all patients and are more frequent in blacks, males, older persons, and individuals with high blood pressure or advanced periodontal disease. They also indicate a thin ridge, useful in implant assessment. Because they are anatomic spaces with walls of cortical bone, their images occasionally have hyperostotic borders. At times a nutrient canal will be oriented perpendicular to the cortex and appear as a small round radiolucency simulating a pathologic radiolucency.


Aiims 2010 November 2010 Dental

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