Quiz 6

Question 1

Mandibular molar overview

Answer 1

A. Crowns are roughly quadrilateral-longer mesiodistally than buccolingually
B.Remember that maxillary molars are widest buccolingually
C.Crowns are shorter cervico-occlusally than premolars, greater in all other dimensions
D.Usually the sum of the mesiodistal measurement of the molars is equal to or greater than thecombined measurements of all teeth anterior to the first molar to the midline

Question 2

Mandibular first molar basics

Answer 2

1.Five well developed cusps
twobuccal
B. twolingual
C. onedistal
2.Two well developed roots-mesial and distal widely separated at the apices
3.Crown measurement is greater mesiodistal than buccuolingual by about 1mm
4.Mesial root is broad, curved distally, with mesial and distal fluting for anchorage
5.Distal root is rounder, broad at cervical end, pointed in a distal direction

Question 3

Mandibular first molar buccal view

Answer 3

1.Crown is trapezoidal in shape
2.If posed vertically one should see all five cusps
3.Lingual cusps can be seen due to their longer length
4.There are two developmental grooves on the crown portion
A.mesiobuccal developmental groove separating the mesiobuccal lobe and distobuccal lobe
B. distobuccal developmental groove separating the distobuccal and distal lobes
5.The two buccal cusps are relatively flat with less curvature of the cusp ridge
A.distal cusp is small and more pointed than other two
B.flattened buccal cusps are typical for all mandibular molars
C.mesiobuccal cusp is the widest of the three
D.distal cusp is only a small part of the buccal surface-most is on the distal andprovidesthedistalcontactarea
E.distal cusp ridge is round and sharpest
6.Mesiobuccal and distobuccal grooves are lines of separation between cusps
A.mesiobucal groove is the shortest and ends mid crown and situated a little mesial torootbifurcation
B.distobucal groove ends near dis-buc line angle at cervical third traveling mesiobuccalparallelingtheaxisofdistalroot
7.Cervical line is regular, dipping in apical direction at bifurcation of the root
8.Mesial outline of the crown
A.concave at cervical third
B.is convex at contact area
9. Distaloutline
A.straight above cervical line, then convex at contact area
10.measurement of crown mesiodistal is about 1.5-2mm wider at contact than cervix
11. Buccalsurface
A.smoothly convex at cusp areas, with grooves between
B.at levels of the ends of the grooves will be a developmental depresionsrunning in a mesiodistal direction just above the cervical ridge
12.May see part of the distal surface of the distal root and distal part of mesial root
13.Mesial root
A.starts with a curve in mesial direction to middle third, then curves distally with the apex below the mesiobuccal cusp
B.distal outline of mesial root is concave from bifurcation to apex
14. Distalroot
A.Less curved than mesial
B.apex is more pointed is located below or distal to distal contact area
15.Both roots are wider at the buccal than they are at the lingual
A.developmental depressions present on mesial and distal of both roots
B.provides more anchorage to the roots
C.point of bifurcation is about 3 mm below cervical line
D.will see a developmental depression on root trunk

Question 4

Mandibular first molar lingual view

Answer 4

1.Three cusps seen-two lingual, and distal cusp
2.Two lingual cusps are pointed and high enough to hide the buccal cusps
A.mesiolingual cusp is the widest mesiodistal and cusp tip is higher
B.lingual developmental groove separates the two lingual cusps and goes down onto the lingual surface only for a short distance
C.where the cusp ridges meet at the groove, the angle is obtuse more so thantheanglesatthecusptips
D.Distal cusp is at a lower level than the mesial
E.Angle formed by the distal cusp ridge of the distolingual cusp and the marginalridge is abrupt giving the impression of a groove
3.Can see part of the mesial and distal surfaces of the crown and root trunk
4.Cervical line is irregular with a point in direction of the bifurcation below it
5.Surface of crown is smooth
6.Roots are about 1mm longer from the lingual and seems longer due to cusp ridges andcervixareatahigherlevel
7.Root bifurcation starts at about 4mm below the cervical line with a deep developmental depression fading as it nears the cervical line
8.Bifurcation groove is almost in line with the lingual developmental groove

Question 5

Mandibular first molar mesial view

Answer 5

1.Buccolingual measurement of crown is greater at the mesial than at the distal
2.Same holds true for the mesial root width compared to distal
3.Can see the rhomboidal outline to crown with its lingual tilt
4.Comparing the outline with the second premolar:
A.crown of the first molar is 1mm or less than the premolar
B.root is also shorter by same amount
C.buccolingual measurement of crown and root are 2mm greater in the molar
D.lingual cusp is longer than the buccal cusp in the molar-opp in premolar
5.Buccal cusps do not approach center axis like 2ndpremolar
6.Lingual cusps are within the lingual outline of roots-not in line with root as premolar
7.Outline of the buccal is convex from just above the cervical line with buccal cervicalridgelocatedincervicalthird
8.Mesiobuccal cusp is just above the buccal third of the mesial root
9.Lingual outline of crown
A. straight uptothemiddlethird
B.convex from middle third to cusp tip
10.Tip of mesiolingual cusp is directly above the lingual third of the mesial root
11.Marginal ridge is about 1mm below the level of the cusp tips
12.Cervical line is irregular with slight curve (1mm)toward the center of the mesialsurface of the mesial rootfig 12-15, 1, 4, 9, 10
13.Cervical line on the lingual is 1mm higher than buccal
A.due to the lingual lean, the cervical line is nearly level
14.Surface is convex, smooth
A.will have a flat or concave area just above the center of the root, below the contact area
15.Contact area is almost centered buccolingual, just below the marginal ridge -1/3 distancefrommarginalridgetocervicalline
16.Buccal outline of the root drops in a straight line from cervical line to junctioncervical and middle thirds, then curves lingually-apex is below mesial of buccal root
17.Lingual outline of root slants buccally to junction of middle and apical 1/3s
18.Root form of mesial root gives the appearance of two roots fused

Question 6

Mandibular first molar distal view

Answer 6

1.Outline is similar to mesial
2.Crown is shorter with surfaces converging distallyfigs 12-10, 12-12, 12-13
3.Can see part of occlusal surface and all five cusps-like second premolar
4.Distal cusp is slightly buccal to center with contact area on its distal contour
5.Distal contact area is just below distal cusp ridge, slightly higher above thecervicallinethanmesialcontactarea
6.Distal marginal ridge is short
A.made up of cusp ridges
B.cusp ridges meet at an obtuse angle
C.where cusp ridges meet, there may be a groove or depression
7.The point of this angle or depression is above lingual 1/3 of distal root unlike mesial which is centered
8.Cervical line is usually straight across
9.End of the distobuccual groove is on the distal surface with a concavity at cervicalportionoflineangle
10.Can see the lingual part of the mesial root from this view

Question 7

Mandibular first molar occlusal view

Answer 7

1.Outline is sort of hexagonal
2.Crown measurement is 1mm greater mesiodistal than buccallingual
3.Buccallingual measurement is greater mesial than distal
4.Mesiodistal measurement is greater on buccal than lingual
5.Cusp sizes-largest is mesiobuccal, then two lingual cusps, distobuccal, then distal
A.see fig 12-16 1,7, 10 for variations
6.Can see a lot of the buccal surface, with only small part of lingual past the cusps
7.Some 4-cusp first molars are seen-
A.Most of them will show distalbucal cusp fused with distal cusp
B.Allmandibular molars have 4 major cusps-maxillary have 3
8. Majorfossa-centralfossa
9.Minor fossae-mesial triangular, distal triangular
10. Developmental grooves
A. central
B. mesiobuccal
C. distobuccal
D. lingual
E.supplemental grooves
11.Central fossa-with all grooves converging into a central pit
12.Mesial triangular fossa will have a mesial pit
13.Distal triangular fossa is less distinct and may not have a pit
14.Central groove takes an irregular course from central pit going mesially to mesial triangular fossa.
A.part way it joins the mesiobuccal groove
B.lingual groove also joins
C.this arrangement makes the triangular ridges of the lingual cusps longer than the buccal ridges

Question 8

Mandibular second molar buccal view

Answer 8

Normally the 2ndmolar is smaller than the 1st molar in all dimensions-not always
C.four cusps are present
D. Buccalview
1.Crown is somewhat shorter than the 1st molar and narrower mesiodistal
2.Only has one buccal developmental groove
3.Cervical line usually points in sharp fashion toward bifurcation
4.Roots may be shorter than 1st molar but may vary a lot, but are closer together withparallelaxes
5.Roots show more distal inclination in relation to crown - 3rd molars incline even more

Question 9

Mandibular second molar lingual view

Answer 9

1.Differences between the second and the first molars-
A.crown and root converge lingually to a lesser degree
B.mesiodistal measurement at cervix is greater than the 1st molar
C.see more of the curvatures on crown at contact areas
D.contact areas are lower, esp. the distal

Question 10

Mandibular second molar mesial view

Answer 10

1. Very little difference from 1stexcept for measurements
   
   2. Buccal cervical ridge is less pronounced
   3. Occlusal surface is more constrictedfig 12-24
   4. Cervical line has less curvature

Question 11

Mandibular second molar distal view

Answer 11

1.Most noted is the absence of a distal cusp

Question 12

Mandibular second molar occlusal view

Answer 12

1. Nodistalcusp
   2.Distobuccal lobe is just as pronounced as the 1st molarif not more so
   3.No distobuccal developmental groove
   4.Buccal and lingual groove meet at right angles at central pit, forming a crosskind of divides the surface into 4 equal parts
   5. Importantcharacteristics
   A.many are rectangular-fig 12-25, 7 and 9
   B.many show prominence cervically at mesiobuccal lobe–fig 12-25, 1,3, 6
   C.many show more curvature distally than mesially
   D.cusp ridge of distobuccal cusp is buccal to cusp ridge of mesiobuccal cusp

Question 13

Mandibular third molar overview

Answer 13

A.It varies a lot in different persons and has many anomalies in form and position
1.Will find some with 5 cusps
2.Some will be larger than 2ndmolars
3.Roots of the oversized tend to be short, poorly formed
4.If congenitally absent on one side of maxilla or mandible, most likely to be alsoonotherside-notsowithmax-mandrelation
B.Enamel is usually thicker which needs to be considered when doing restorations

Question 14

Mandibular third molar buccal view

Answer 14

1.Outline is similar to other Mandibular molars
2. Generallyshowstworoots
A.may be shorter and poorly developed with distal inclination greater

Question 15

Mandibular third molar lingual view

Answer 15

similar to second molar

Question 16

Mandibular third molar mesial view

Answer 16

1. Usually smaller in dimensions

2. Mesial root is shorter with more taper to more pointed apex

Question 17

Mandibular third molar distal view

Answer 17

1. Similar to second

2. Those with oversize crowns are more spheroid above cervical line

Question 18

Mandibular third molar occlusal view

Answer 18

1. Again similar to second-fig 12-36

2. Will be more rounded and smaller buccolingually at distal

Question 19

Pulp Chamber Intro

Answer 19

Terminology:
Dental pulp is the soft tissue component of the tooth and occupies the internal cavities of the tooth.
Outline of the chamber and canal corresponds to the shape of the crown and root
Crown portion of the tooth that contains the pulp (soft) tissue
1. Pulp Chamber
2. Pulp Cavity
3. Coronal Pulp
Root portion of the tooth that contains the pulp
1. Pulp Canal
2. Root pulp
3. Radicular Pulp
4. Root Canal
Dental pulp originates from the Mesenchyme
Has different functions
1. Formative
2. Nutritive
3. Sensory
4. Defensive

Question 20

Radiographs

Answer 20

Remember- taking a three-dimensional tooth and compressing it into a two-dimensional image
Orientation shows a monoplane, buccolingual view

Question 21

size of pulp cavity

Answer 21

Depends on the age of the tooth
1. Secondary dentin is formed continuously throughout the life of tooth
2. Pulp cavity is much larger in a young individual than an adult
History of trauma
1.Initiates a different type of dentin formation
2. Irritation-induced or reparative dentin is fornmed in response to:
A. Carious process
B. Abrasion
C. Attrition
E. Operative procedures
The size of the pulp cavity in a given tooth should be compared with other teeth in same dentition
Extreme calcification present- elective endodontics before complex restorative procedures

Question 22

foramen

Answer 22

Opening at the apex of the tooth in which the neurovascular bundle enters the tooth.
In tooth development, the apical foramen is actually larger than the pulp chamber.
At the completion of root formation it becomes more constricted
Possible to have multiple apical foramina
1. If openings are large enough and lead to the main canal they are called supplementary or lateral canals.
2. If they break up into multiple tiny canals it is referred to as a delta system

Question 23

Demarcation of the Pulp cavity and canal

Answer 23

This demarcation is mainly microscopic and the transition from pulp chamber to pulp canal is not a sharp demarcation.
The cementoenamel junction (CEJ) is not quite at the level at which the pulp canal becomes the pulp chamber.
Is simpler in multirooted teeth because the pulp cavity within the root is the pulp canal and the remaining pulp cavity is the pulp chamber

Question 24

pulp horns

Answer 24

Projections or prolongations in the roof of the pulp chamber.
Corresponds to the various major cusps or lobes
If cusps or labial lobes are prominent (young individuals),expect to find equally prominent pulp horns
They become less prominent with time as a result of secondary formation

Question 25

Clinical Applications

Answer 25

Operative:
Be aware of the location and size of the pulp cavities during operative procedures to prevent unnecessary encroachment on the pulp
Endodontics:
Requires a thorough knowledge of the pulp cavity
1. Perforation during access
2. Failure to locate all canals
3. Lack of knowledge leading to the above may result in the ultimate loss of the tooth
Preforming endodontics requires knowing the size and location of the pulp chamber and expected number of roots and canals
Radiographic detection of all accessory roots or canals may not be possible
Thorough knowledge of the pulp cavities = greater degree of endodontic success

Question 26

Maxillary Central Incisor Pulp Cavity

Answer 26

Labiolingual Section:
1. General outline of the crown and root
2. Very narrow in the incisal region
3. Cervical area the pulp chamber increases to its largest labiolingual dimension
4. Below cervix area, the root canal tapers, gradually ending in a constriction at the apex
Mesiodistal Section:
1. Chamber is wider in the mesiodistal dimension than the labiolingual
2. Conforms to the general shape of the tooth
3. If prominent mamelons, usually prolonged pulp horns in incisal region
4. Pulp cavity tapers evenly until apical constriction
Cervical and Midroot Sections:
1. Widest at cervical level
2. Triangular outline with base at the labial
3. When tooth ages, dentin increases and chamber becomes more rounded or crescent – shaped
4. Root and canal are more rounded at midroot level

Question 27

Maxillary Lateral Incisor Pulp Cavity

Answer 27

Labiolingual Section:
1. Similar to the central incisor
2. Narrow incisor, widest at cervical, tapers to the apex
Mesiodistal:
1. Pulp cavity follows outline of tooth
2. Gradual taper to apex
3. Significant curve toward the distal in apical region
Cervical and Midroot Cross Sections:
1. Large variation of shape – triangular, oval, or round

Question 28

Maxillary Canine Pulp Cavity

Answer 28

Labiolingual Section:
1. Has the largest labiolingual dimension of any tooth in the mouth
2. If a prominent cusp – a long narrow pulp horn is present
3.Pulp chamber and cervical third –middle third of root may be very wide
4. Very abrupt constriction of root canal in the apical region – then gentle taper to apex
Mesiodistal Section:
1. Pulp cavity much narrower in the mesiodistal aspect.
2. Gental taper to apex – similar to central and lateral incisors; however much longer root
3. Mesial or distal curve at apex
Cervical Cross Section:
1. shape is oval, triangular, or elliptical

Question 29

Maxillary 1st premolar pulp cavity

Answer 29

Buccolingual Section:
1. May have two well developed roots(majority), two root projections that are not fully separated, or one broad root
2. Small percentage have three roots
3.Pulp horn extends further occusally under buccal cusp
4. Pulp chamber floor is below the cervical level
5. Chambers of teeth having least root separation show largest occlusal – apical dimension
6 Shape of chamber tends to be square or rectaingular
Mesiodistal Section:
1. Chamber cannot be differentiated from the root canal
2.If two canals are present, x-ray radiopacity will increase in apical half of the tooth as a result of increase in dentin and bone and decrease in pulp cavity
Cervical Cross Section:
1. Cervical level – Kidney shaped due to the mesial developmental depression

Question 30

Maxillary 2nd premolar pulp cavity

Answer 30

Buccolingual Section:
1. Two root are possible or two canals within one root may also be found
2. Chamber and root canal very broad in teeth with single canals
3. Some possess dental islands in apical third or root – treat as two canals
4. Can have canals that bifurcate at apical third of root
5. Buccal and lingual pulpal projections or fins present at the level of CEJ
Mesiodistal Section:
1. Same as the 1st premolar
Cervical Cross Section:
1. Oval, kidney or elliptical shaped

Question 31

Maxillary 1st molar pulp cavity

Answer 31

Buccolingual Section:
1. Shows pulp cavities of mesiobuccal and palatal(lingual) roots
2. Mesiobuccal used because of the complexity – distobuccal root is striaghter with fewer variations
3. Palatal root has largest dimensions, then mesiobuccal and distobuccal respectively
4. Mesiobuccal root often very wide - usually possesses.an accessory canal(MB2)
5. MB2 smallest of all the canals
6. Pulp horns usually prominent
7. Chamber is rectangular in shape
8. Mesiobuccal canals are widest at midroot level then taper to very fine diameter at apex
Mesiodistal Section:
1. Mesiobuccal pulp horn usually larger than distobuccal
2. Chamber somewhat square
Cervical Cross Section:
1. Rhomboidal with rounded corners
2. If MB2 present it will be lingual and mesial to the mesiobuccal canal
3. Canals of this tooth form a triangle pattern – Longest side from palatal to mesiobuccal
Midroot Cross Sectiion:
1. Palatal usually largest and rounded
2. Distobuccal smaller and oval
3. Mesiobuccal is elongated oval to kidney shaped – indentation toward the furcation

Question 32

Maxillary 2nd molar pulp cavity

Answer 32

Buccolingual Section:
1. Buccal roots are straighter and closer together than Maxillary 1st
2. Mesiobuccal root not as complex as Maxillary 1st
3. Presence of two canals in Mesiobuccal root not as common
4. Chamber is rectangular
Mesiodistal Section:
1. Chamber appears much smaller in this section
2. Chamber is square
3. Canals gently taper to apical constriction
Cervical Cross Section:
1. Mesiobuccal angle more acute, distobuccal angle more obtuse
2. Mesiobuccal orifice is farther to the buccal and mesial
3. Distobuccal approaches the midpoint between the mesiobuccal and palatal canals
4. Orifices of canals are much closer together

Question 33

Maxillary 3rd molar pulp cavity

Answer 33

Most variable of any of the maxillary teeth
They are 8-9 years younger than maxillary 1st and 2nd molars so pulp chamber will have less secondary dentin than the 1st or 2nd
This allows easier access to canals
High incidence in malformations of the root= endodontic procedures may be very difficult

Question 34

Mandibular Central Incisor pulp cavity

Answer 34

Labiolingual Section:
1. Smallest tooth in the mouth but labiolingual dimension is very large
2.Usually one canal, but two can be present
3.Well developed pulp horn
4. Attrition causes dentin production and moves the pulp tissue farther apically
5. Pulp chamber can be large, intermediate, or small
6. Pulp canal tapers gently to apex or narrows abruptly in the apical 3-4 mm
Mesiodistal Section:
1. Narrow pulp cavity
2. Single prominent pulp horn
Cervical Cross Section:
1. Chamber shape is variable – round, oval, or elliptical
2. Two separate canals may be present or a dentinal island

Question 35

Mandibular Lateral Incisor pulp cavity

Answer 35

Labiolingual Section:
1. larger than the mandibular central incisor in all dimensions
2. Pulp horn is usually porminent
3. Chamber Can be very large, intermediate, or small
4. Pulp canal can taper gently to the apex or narrow abruptly in the last 3-4 mm of the canal
Mesiodistal Section:
1. Chamber and canal demonstrate a slender cavity
2. Resembles Mandibular central but larger
3. Pulp horn is prominent
4. Chamber and canal taper gently to apex
Cervical Cross Section:
1. considerable variation in shape – oval to elliptical
2. Larger lateral may resemble smaller mandibular canines

Question 36

Mandibular Canine pulp cavity

Answer 36

Labiolingual Section:
1. Pulp cavity similar in size and shape to Maxillary canines
2. Not uncommon to have two roots or two canals in one root
3. A dentinal island may be present
Note A dentinal island may be found in any tooth that demonstrates an extremely wide labiolingual dimension and a narrow mesiodistal dimension
4. Pulp horn is porminent unless attrition has occurred
5. Demonstrates an abrupt narrowing of the pulp cavity when it passes from the chamber to the pulp canal
6. Canal gently tapers to the apex
Mesiodistal Section:
1. Very similar to the maxillary canine
2. Curvature of the apical portion of the root – may be in a mesial direction
3. Pulp horn is prominent
4. Chamber and canal show a continous gentle taper to the apex
Cervical Cross Section:
1. Variation in size and shape – may be oval, rectangular, or triangular

Question 37

Mandibular 1st premolar pulp cavity

Answer 37

Buccolingual Section:
1. Pulp cavity looks like a small mandibular canine
2. Majority have one canal but two or three canals are possible
3. Pulp horn is prominent in buccal cusp
4. Horn in lingual cusp may be present but smaller
5. Chamber is usually very large
6. Pulp cavity tapers gently to apex
Mesiodistal Section:
1. Pulp horn is prominent but narrow
2. Chamber and canal taper gently to apex
Cervical Cross Section:
1. Crown and root size vary considerably, as does the pulp cavity
2. Outline of root may be oval. Rectangular, or triangular

Question 38

Mandibular 2nd premolar pulp cavity

Answer 38

Buccolingual Section:
1. Larger than the mandubilar 1st premolar, especially in the crown and cervical portion of the root
2. Pulp horns are more prominent than in the 1st premolar and the lingual horn present more often
3. Chamber usually large and may abruptly constrict or gently taper to the apex
Mesiodistal Section:
1. Very similar to the mandibular 1st premolar, except dimensios are larger
2. Similar to the mandibular canine
3. Pulp horns are prominent
4. Chamber and canal taper gently to the apex
Cervical Cross Section:
1. Outline form of the root is rectangular, oval, or triangular

Question 39

Mandibular 1st molar pulp cavity

Answer 39

Buccolingual Section:
1. Large pulp chamber that may extend well down into the root formation
2. Mesial root usually more complicated because of the presence of two canals
3. Distal root usually has one large canal, but two canals are often present
4. Occasionally a fourth canal is present that has its own separate root
5. Pulp horns are prominent in most molars
6. one or both mesial canals may be significantly curved, moderately curved, or relatively straight
7. The two canals may join each other in the apical region to exist in a common foramen or they may have separate apical foramina
8. Distal root usually has one large canal – very wide in the buccolingual dimension
9. When two canals are present, they may be partially are completely separated by a dentinal island
Mesiodistal Section:
1. Pulp chamber is usually retangular and may be large or smaller canal
2. Mesial root and canal show considerable curvature
3. Distal root is usually shorter ; however, may be the same length os slightly longer
4. Dictal canal is usually larger than the mesial canal
Cervical Cross Section:
1. Midroot view shows mesial root somewhat kidney-shaped with two separate canals
2. Two mesial canals may be separate or confluent with the other
3. Even three canals may be found in this root
4. Distal root is usually rounder but can be broader with two canals

Question 40

Mandibular 2nd molar pulp cavity

Answer 40

Many similarities with the mandibular 1st molar
Roots may be straighter and less divergence from the furcation in the 1st molar
Roots may be shorter
Buccolingual Section:
1. Pulp chamber and canals tend to be more variable and complex than the 1st molar
2. Pulp chamber is somewhat square
3. Mesial root usually has two canals, but only one may be present
4. Curve of canals may be severe, moderate, or virtually absent
5. Chamber and canal of distal root is large and usually has one canal
6. Can also have two totally or partially separate canals
Mesiodistal Section:
1. Similar to Mandibular 1st molar except roots tend to be striaghter and closer together
2. Pulp horns usually prominent
3. Chamber is rectangular and varies from very large to very small
4. Mesial canal curvature may be severe, moderate or straight
5. Distal canal may be slightly curved or straight
6. Distal root may be shorter or longer than the mesial root
7. Distal canal is usually larger ,but may be equal to the mesial canals
Cervical Cross Section:
1. Similar to the 1st molar
2. Pulp chamber tends to be triangular
Midroot Cross Sectiion:
1. Mesial root is very broad buccollingually and narrow mesiodistally
2. Outline form is kidney-shaped
3. Distal root may be rounde with one canalr, but broad root having two canals are are also seen

Question 41

Mandibular 3rd molar pulp cavity

Answer 41

Pulp cavities vary greatly
Buccolingual Section:
1. Two roots and three canals are often present
2. Two canals or two roots also possible
3. One canal and one root can also be found – usually these teeth are not of much value for restorative purposes
4. Prominent pulpal horn
5. Mesial root usually two canals, but single canal can be found
6. Distal root possesses large pulp chamber and canal
Mesiodistal:
1. Pulp chamber usually square or rectangular
2. Mesial root curve may be slight, moderate or severe
3. Canals in these roots may be large to very small
4. Distal canal may be larger than mesial, but may be equal in size
Cervical and Midroot Cross section:
1. Outline variable

Question 42

Crown and Root fractures

Answer 42

Fractures may involve the crown, the crown and root, or the root.
May only involve the enamel, the enamel and the dentin, or involve the pulp
Fractures can occur without loss of tooth structure, involve a cusp or incisal edge.
In severe trauma, the whole crown may be lost
Most likely places involve developmental grooves – often in relation to restorations
May occur in connection with bruxism and clenching
Fractures to the root cause symptoms that resemble those of other dental problems; therefore difficult to diagnose
Usually does not appear on a radiograph
Horizontal root fractures likely result from external physical trauma, clenching, or burxism
Vertical root fractures may be caused by bruxing, clinching, or result from endodontic post in the root canal

Question 43

maxillae

Answer 43

osseous structures that support the teeth are the maxilla and mandible; maxilla (upper jaw) consists of 2 bones (R/L) suture together at median line; makes up a large part of the bony framework of the facial portion of the skull; form major portion of roof of mouth (hard palate), floor of orbit, sides and base of nasal cavity, support 16 permanent max teeth; irregular bone, cuboidal in shape; consists of a body and 4 processes; maxilla is hollow and contains maxillary sinus air space (Antrum of Highmore); body of the maxilla has (anterior or facial, infratemporal, orbital, nasal)

Question 44

Anterior surface of maxilla

Answer 44

infraorbital foramen; incisive fossa (above roots of the incisors, anterior to the canine eminence), canine eminence (root of the canine), canine fossa (above roots of the premolars)

Question 45

Infratemporal (posterior) surface

Answer 45

inferior portion or this surface is more prominent (overhangs the root of the 3rd molar) called the maxillary tuberosity

Question 46

orbit surface

Answer 46

smooth surface forming the floor of orbit

Question 47

nasal surface

Answer 47

nasal spine, nasal process

Question 48

zygomatic process

Answer 48

triangular eminence whose apex is directly over the first molar roots

Question 49

frontal process

Answer 49

anterior

Question 50

palatine process

Answer 50

forms the hard palate; inferior surface is rough and pitted for the palatine mucous glands; pierced by numerous small foramina for passage of blood vessels and nerve fibers; posterior border has a greater palatine foramen that passes the greater palatine nerve and vessels to the palatal soft tissue; immediately posterior to the central incisors is the incisive foramen (foramina of Stenson) carrying the nasopalatine nerves and vessels

Question 51

Alveolar process

Answer 51

portion of the bone that surrounds the roots of maxillary teeth and gives osseous support; extends from the tuberosity posteriorly to the median line anteriorly; the process has a facial and lingual surface- plates of very dense but thin cortical bone separated by interdental septa of cancellous bone; facial plate is thin, alveoli are frail and their edges are sharp and thin; buccal plate over the 2nd and 3rd molars is thicker; lingual plate is heavier than the facial plate; alveolar process is maintained by the presence of the teeth; should a tooth be lost, the portion of the alveolar process will be subject to atrophic reduction; should all teeth be lost, the alveolar process will eventually be virtually lost

Question 52

alveoli (tooth sockets)

Answer 52

the alveolar cavities are formed by the facial and lingual plates of the alveolar process and by connecting septa of bone placed between the 2 plates; the form and depth of each alveolus are determined by the form and length of the root it supports

Question 53

maxillary sinus

Answer 53

the sinus overlies the alveolar process in which the molar teeth are implanted; usually over the 1st and 2nd molars but can include the 3rd molar and extend to the premolars; not uncommon to see some roots of posterior teeth extending above the floor of the sinus forming small hillocks; a layer of bone always separates the roots and the floor of the sinus- in absence of pathological conditions; a layer of sinus mucosa is also always between the root tips and sinus cavity

Question 54

The mandible

Answer 54

The mandible is horseshoe-shaped and supports the teeth of the lower dental arch; This bone is movable and has no bony articulation with the skull; It is the heaviest and strongest bone of the head and serves as a framework for the floor of the mouth; Its condyles rest in the mandibular fossa of the temporal bone; This articulation is the temporomandibular joint (TMJ);
Consists of two lateral halves, which join at the median line – usually marked by a slight ridge called the symphysis; Left and right of the symphysis, near the lower border of the mandible, are two prominences called the mental tubercles; A prominent triangular surface of these three is called the mental protuberance; The oblique ridge extends obliquely across the external surface of the mandible from the mental tubercle to the anterior border of the ramus; Lies below the mental foramen and usually more prominent in the molar area; This ridge thins and progresses upward and becomes the anterior border of the ramus and ends at the tip of the coronoid process; The coronoid process and the condyloid process (condyle) make up the superior border of the ramus
The condyle is convex and fits into the mandibular fossa of the temporal bone and forms, with the interarticular cartilage that lies between the two surfaces, and with the tissue attachment, the TMJ; An important landmark on the lateral aspect of the mandible is the mental foramen positioned a little below the apex of the second premolar

Question 55

Internal surface of the mandible

Answer 55

the mandible from the rear shows a slight vertical depression, representing the union of left and right halves; immediately below this, at the lower third, the bone is roughened by eminences called the superior and inferior mental spines, or genial tubercles; the internal surface of the body is divided into 2 portions by a well defined ridge, the mylohyoid line; it’s position closely corresponds to the oblique ridge on the outside; it starts on the lowest part of the mental spines and passes backward and upward, increasing in prominence until the anterior portion of the ramus; increasing in prominence until the anterior portion of the ramus; this ridge is the origin of the mylohyoid muscle; immediately posterior to the median line and above the mylohyoid ridge is a smooth depression called the sublingual fossa-where the sublingual gland sits; toward the center of the mandible, between the mylohyoid line and the lower border is a smooth oblong depression called the submandibular fossa- where the submandibular gland lies; the mandibular foramen is located on the medial surface of the ramus midway between the mandibular notch and the angle of the jaw and also midway between the internal oblique line and the posterior border of the ramus; the mandibular canal begins at this point, passing downward and forward horizontally

Question 56

mandibular alveolar process

Answer 56

The border outlines the alveoli of the teeth and is very thin anteriorly but thicker posteriorly where it encompasses the roots of the molars; It is not as cancellous as the maxilla and instead of the facial plate being thin, it is equally as heavy as the lingual plate; The bone over the anterior teeth is thin and may be entirely missing over the cervical portion of the root, the bone that does cover the root is compact; The inferior border is strong and rounded and gives the greatest strength; When looking at the alveolar process from above, more of the bone may be seen lingual to the anterior teeth and buccal to the posterior teeth; The dental arch is narrower posteriorly than the mandibular arch, therefore, the outline of the arch of the teeth does not correspond to the outline of the arch of the mandibular arch;
Posterior to the third molar a triangular shallow fossa is outlined called the retromolar triangle

Question 57

Arterial supply to the teeth

Answer 57

The arteries and nerve branches to the teeth are mere terminals of the central systems

Question 58

Internal maxillary Artery

Answer 58

The arterial supply to the jaw bones and the teeth comes from the maxillary artery, which is a branch of the external carotid artery; The branches of the maxillary artery that feed the teeth directly are the inferior alveolar artery and the superior alveolar arteries

Question 59

Inferior Alveolar Artery

Answer 59

Branches from the maxillary artery medial to the ramus of the mandible; It gives off the mylohyoid branch then enters the mandibular foramen and continues downward and forward through the mandibular canal, giving off branches to the molar and premolar teeth; In the vicinity of the mental foramen, it divides into the mental and incisive branch; The mental branch passes through the mental foramen to supply the tissues of the chin;The incisive branch continues forward in the bone to supply the anterior teeth; The inferior alveolar arteries and incisive arteries give off dental branches to the individual tooth roots for the supply of the pulp and periodontal membrane

Question 60

Superior Alveolar Arteries

Answer 60

The posterior superior alveolar artery branches from the maxillary artery superiorly to the maxillary tuberosity to enter the alveolar canal and supplies the maxillary teeth, alveolar bone, and sinus membrane; A middle superior alveolar branch is usually given off by the infraorbital continuation of the maxillary artery and supplies the premolar teeth; Anterior superior alveolar branches arise from the infraorbital artery just before this vessel leaves its foramen;
They course down the anterior aspect of the maxilla to supply the anterior teeth and supporting tissues

Question 61

Descending Palatine and Sphenopalatine Arteries

Answer 61

The palatal blood supply comes from two sources: the descending palatine artery, which descends from its origin from the maxillary through the greater canal; Its greater palatine branch enters the palate through the greater palatine foramen and runs forward in a groove at the junction of the palatine and alveolar processes and enters the palate through the incisive; It distributes to the bone, glands, and mucosa of the hard palate; The nasopalatine branch of the sphenopalatine artery courses obliquely forward and downward on the septum and enters the palate through the incisive canal; It has a limited distribution to the incisive papilla and adjacent palate

Question 62

Nerve supply to the jaws and teeth

Answer 62

The sensory nerve supply to the jaws and teeth is derived from the maxillary and mandibular branches of the fifth cranial nerve, or trigeminal nerve; The innervation of the orofacial region includes, in addition to the trigeminal nerve(including V2 and V3), other cranial nerves, (VII,XI,XII)

Question 63

maxillary N

Answer 63

The maxillary nerve courses forward through the wall of the cavernous sinus and leaves the skull through the foramen rotundum; The branches of clinical significance include a greater palatine branch that enters the hard palate through the greater palatine foramen; The lesser palatine branch from the ganglion that enters the soft palate through the lesser palatine foramina, and a nasopalatine branch – entering the palate through the incisive canal; The maxillary nerve also has a posterior superior alveolar branch that distributes to the molar teeth and supporting tissues; A middle superior alveolar branch arises from the infraorbital nerve and runs to the premolar teeth and surrounding tissues; An anterior superior alveolar branch leaves the infraorbital nerve just inside the infraorbital foramen and distributes to the incisor and canine teeth; All three superior alveolar nerves join in a plexus and give off dental branches to each tooth root and interdental branches to the bone, periodontal membrane, and gingiva

Question 64

Mandibular N

Answer 64

The mandibular nerve leaves the skull through the foramen ovale and almost immediately breaks up into its several branches; The chief branch to the lower jaw is the inferior alveolar nerve and travels downward to reach the mandibular foramen; Just before entering the foramen, it releases the mylohyoid branch; The inferior alveolar nerve continues forward through the mandibular canal beneath the roots of the molar teeth to the mental foramen; It gives off branches to the molar and premolar teeth and their supporting bone and tissues; The nerves do not arise as individual branches but as two or three larger branches that form a plexus from which inferior dental branches enter individual tooth roots and interdental branches supply alveolar bone, periodontal membrane, and gingiva; At the mental foramen, the nerve divides and a smaller incisive branch continues forward to supply the anterior teeth and bone; A larger mental branch emerges through the foramen to supply the skin of the lower lip and chin; Other branches of the mandibular nerve, such as the buccal nerve, supply innervation to a small area of the buccal gingiva in the first molar area ( can extend from the third molar to the canine); The lingual nerve enters the floor of the mouth and innervates the lingual mucosa and gingiva; The mylohyoid nerve may sometimes enter the side of the mandible through small foramina and contribute to the innervation of the central incisors and periodontal ligament

Question 65

Innervation of Maxilary Teeth

Answer 65

Anterior Superior Alveolar N: upper incisors and canines (CN V-2)
Middle Superior Alveolar N: upper premolars and the mesio- buccal root of the maxillary first molar (CN V2)
Posterior superior alveolar N: upper molars except the mesiobuccal root of the maxillary first molars (CN V2)

Question 66

Innervation of Mandibular Teeth

Answer 66

Inferior Alveolar N: mandibular teeth, gingiva, and lower lip unilaterally (CN V3)
Lingual N: anterior 2/3 of tongue and mucosa of the floor of the mouth (CN V3)
Buccal N: gingiva on the buccal side of posterior teeth (CN V3)

Question 67

Trigeminal Neuralgia

Answer 67

Or tic douloureux is sometimes described as the most excruciating pain known to humanity; this intense, stabbing, electric shock like pain is caused by irritation of the trigeminal N; anticonvulsive medications are normally the first treatment of choice;

Prevalence and Incidence: advanced age is a major risk factor; rarely affects anyone younger than 50; more common in women than in men; hypertension and multiple sclerosis are also risk factors; an estimated one million people worldwide

Initially short, mild attacks, but trigeminal neuralgia can progress, causing longer, more frequent bouts of searing pain; they may also be provoked by even mild stimulation of face

Triggers may include: shaving, stroking your face, eating, drinking, brushing your teeth, talking, putting on makeup, encountering a breeze, smiling