Week 1 Endo - Access

Question 1

1. Which of the following teeth most commonly have a second mesiobuccal canal (MB2)?
   a) Lower central incisors
   b) Upper first molars
   c) Lower first premolars
   d) Upper canines

Answer 1

b

Question 2

2. What is the average root length of a lower canine?
   a) 22 mm
   b) 24 mm
   c) 27.5 mm
   d) 25 mm

Answer 2

c

Question 3

3. What percentage of lower first premolars have three canals?
   a) 0.5%
   b) 1%
   c) 10%
   d) 15%

Answer 3

b

Question 4

4. Which canal is often missed due to its lingual position in lower incisors?
   a) MB2
   b) DL canal
   c) Lingual canal
   d) Buccal canal

Answer 4

c

Question 5

5. According to the Law of Colour Change, the pulp chamber floor is:
   a) Lighter than the walls
   b) Same colour as walls
   c) Darker than the walls
   d) Irregular in colour

Answer 5

c

Question 6

6. In a lower first molar, how often does the mesial root have two canals?
   a) 12%
   b) 87%
   c) 70%
   d) 60%

Answer 6

b

Question 7

7. C-shaped molars are characterized by:
   a) A central oval orifice
   b) Separate mesial and distal canals
   c) A single ribbon-shaped orifice
   d) Two straight canals

Answer 7

c

Question 8

8. The Law of Orifice Location I states that canal orifices are found:
   a) On the pulpal roof
   b) In the middle of the floor
   c) At the junction of the walls and floor
   d) Randomly along the root surface

Answer 8

c

Question 9

9. Which of the following is true about lower incisors?
   a) They never have two canals
   b) 40% have two canals
   c) They have three canals in 10% of cases
   d) Lingual canal is always dominant

Answer 9

b

Question 10

10. Which law suggests that canals are found along the root developmental fusion lines?
    a) Law of Symmetry II
    b) Law of Colour Change
    c) Law of Orifice Location III
    d) Law of Access

Answer 10

c

Question 11

11. What percentage of upper first molars have four canals?
    a) 99%
    b) 95%
    c) 60%
    d) 40%

Answer 11

b

Question 12

12. In the lower first molar, how often is the distal root found to have two canals?
    a) 70%
    b) 60%
    c) 30%
    d) 10%

Answer 12

c

Question 13

13. Which tooth most frequently presents with a C-shaped canal system?
    a) Lower first premolar
    b) Maxillary first molar
    c) Mandibular second molar
    d) Maxillary lateral incisor

Answer 13

c

Question 14

14. The average root length of a maxillary first molar is:
    a) 20 mm
    b) 22 mm
    c) 23 mm
    d) 25 mm

Answer 14

b

Question 15

15. Which law helps in identifying orifices by observing fusion lines on the pulp floor?
    a) Law of Orifice Location I
    b) Law of Orifice Location III
    c) Law of Symmetry I
    d) Law of Colour Change

Answer 15

b

Question 16

16. What is the frequency of two foramina in the lower incisor?
    a) 40%
    b) 25%
    c) 10%
    d) 90%

Answer 16

c

Question 17

7. In lower first premolars, how often are two canals present?
   a) 24%
   b) 1%
   c) 50%
   d) 80%

Answer 17

a

Question 18

18. The Law of Orifice Location II states that canal orifices are located at:
    a) The middle of the pulp floor
    b) The apex of the root
    c) Angles in the floor-wall junction
    d) Cusp tips

Answer 18

c

Question 19

19. Which of the following teeth has the greatest variation in canal number and configuration?
    a) Upper lateral incisor
    b) Lower first premolar
    c) Upper first molar
    d) Lower canine

Answer 19

b

Question 20

20. What is the most consistent location of the second canal in lower incisors when present?
    a) Buccally placed
    b) At the CEJ level
    c) Lingually placed
    d) Mid-root level

Answer 20

c

Question 21

21. What percentage of lower canines have two foramina?
    a) 5%
    b) 10%
    c) 20%
    d) 25%

Answer 21

a

Question 22

22. Which of the following is NOT part of Krasner and Rankow’s laws?
    a) Law of Symmetry I
    b) Law of Orifice Location II
    c) Law of Pulp Chamber Geometry
    d) Law of Curvature

Answer 22

d

Question 23

23. In maxillary first molars, MB2 joins MB1 in approximately what percentage of cases?
    a) 40%
    b) 60%
    c) 90%
    d) 95%

Answer 23

b

Question 24

24. The law stating that orifices lie on a line perpendicular to the mesiodistal line through the pulp floor refers to:
    a) Law of Symmetry II
    b) Law of Orifice Location I
    c) Law of Floor Angulation
    d) Law of Central Alignment

Answer 24

a

Question 25

25. What percentage of lower first molars have three canals in the mesial root? a) 1% b) 10% c) 25% d) 12%

Answer 25

a

Question 26

26. Which statement is TRUE about the pulp chamber floor in terms of visual guidance? a) It is the same shade as the walls b) It becomes lighter when dried c) It is darker than the walls d) It is translucent

Answer 26

c

Question 27

27. In a C-shaped molar, the canal begins at which angle and sweeps to which side? a) Mesiobuccal to distolingual b) Mesio-lingual to distal c) Buccal to lingual d) Central to buccal

Answer 27

b

Question 28

28. Which tooth most consistently presents a single root and canal anatomy? a) Maxillary central incisor b) Maxillary first premolar c) Mandibular second molar d) Mandibular canine

Answer 28

a

Question 29

29. Why is the MB2 canal in upper first molars often missed? a) It is not visible on radiographs b) It does not connect to the pulp chamber c) It is often obliterated and small d) It is usually buccal to the main canal

Answer 29

c

Question 30

30. What is the most important prerequisite to successful canal location? a) Rubber dam placement b) Canal instrumentation c) Anatomical knowledge d) Working length determination

Answer 30

c

Question 31

31. Which of the following teeth has the highest frequency of two canals in a single root? a) Maxillary central incisor b) Mandibular lateral incisor c) Maxillary second molar d) Mandibular canine

Answer 31

b

Question 32

32. The term “MB2” in upper first molars refers to: a) The second distal canal b) A second canal in the mesiobuccal root c) A canal found in the palatal root d) An accessory canal in the furcation

Answer 32

b

Question 33

33. What is the most likely anatomical configuration of the lower first premolar? a) 2 roots, 2 canals b) 1 root, 1 canal c) 1 root, 3 canals d) 2 roots, 1 canal

Answer 33

b

Question 34

34. Which anatomical law aids in detecting pulp floor landmarks through color variation? a) Law of Symmetry I b) Law of Orifice Location III c) Law of Colour Change d) Law of Canal Fusion

Answer 34

c

Question 35

35. Which of the following applies to maxillary molars in terms of symmetry laws? a) Law of Symmetry I does not apply b) Canal orifices are asymmetrically located c) They often violate the Law of Colour Change d) Fusion lines are more pronounced

Answer 35

a

Question 36

36. How frequently do lower first molars have three roots? a) 1% b) 3% c) 5% d) 7%

Answer 36

c

Question 37

37. The orifices of the canals are always located at: a) The middle of the pulp chamber b) Along the crown-root junction c) The junction of the walls and floor d) Apical foramen

Answer 37

c

Question 38

38. In what percentage of lower first molars is the distal root reported to have two canals? a) 20% b) 30% c) 50% d) 70%

Answer 38

b

Question 39

39. The clinical implication of the Law of Orifice Location II is that: a) Orifices are typically found midway along the floor b) Orifices lie at floor-wall angles c) Orifices are at the apex of developmental grooves d) Orifices lie below the DEJ

Answer 39

b

Question 40

40. What is a key takeaway from the C-shaped molar description? a) It has round canal orifices b) It is usually found in the maxillary arch c) It has a sweeping 180° arc orifice d) It has three distinct canals

Answer 40

c

Question 41

41. What feature makes locating canals in lower first premolars particularly difficult? a) Frequent canal calcification b) Variability in canal number and configuration c) Thick lingual enamel d) Dual pulp chambers

Answer 41

b

Question 42

42. How often does the MB2 canal join MB1 in upper first molars? a) 40% b) 60% c) 80% d) 90%

Answer 42

b

Question 43

43. What is the average length of the lower incisor root? a) 20 mm b) 21 mm c) 22 mm d) 23 mm

Answer 43

c

Question 44

44. According to the presentation, a key principle in access cavity design is: a) To create a triangular access shape regardless of tooth b) To locate all canals while preserving dentine c) To access canals via the cusp tips d) To flatten the pulpal floor for better visibility

Answer 44

b

Question 45

45. What is the incidence of two canals in lower canines? a) 5% b) 10% c) 20% d) 30%

Answer 45

c

Question 46

46. What principle helps you identify that canal orifices follow a consistent spatial orientation across the chamber floor (excluding maxillary molars)? a) Law of Floor Geometry b) Law of Symmetry II c) Law of Pulpal Angulation d) Law of Root Curvature

Answer 46

b

Question 47

47. Which of the following is correct regarding lower first molars? a) Mesial root typically has one canal b) Distal root usually has two foramina c) Mesial root most often has two canals d) Distal root never has more than one canal

Answer 47

c

Question 48

48. The Law of Orifice Location III refers to canal orifices being located at: a) Furcation entrances b) Root developmental fusion line terminations c) Pulp horns d) Crown-root interface

Answer 48

b

Question 49

49. What is the frequency of a single foramen in the distal root of lower first molars? a) 85% b) 75% c) 60% d) 50%

Answer 49

a

Question 50

50. What is the main clinical utility of understanding the laws of canal location? a) To complete the procedure faster b) To ensure esthetic shaping c) To increase predictability of canal detection d) To decide on obturation material

Answer 50

c