Identifying Features Flashcards
1
Q
Maxillary first permanent incisor
A
- largest crown of all incisors (almost as wide as it is long)
- smooth labial surface, slightly convex
- mesio -incisal angle is sharp; disto - incisal angle is rounded
- lingual surface is concave with with mesial and distal marginal ridges with meet at the cervix forming a convex cingulum
- viewed mesially or distally, crown appears wedge shaped and leans palatally
- One tapering root, when looked at in cross section is roughly triangular with rounded angles. One root canal, 2 pulp horns (cornua) one mesial one distal. Externally if a groove is present it will be more prominent on the distal side
Variations:
- malformed macrodent (larger than normal)
- very exaggerated marginal ridges (shovel shaped form)
- very elongated cingulum
- mineralisation defects near incisal edge
- ethnic variations
2
Q
Maxillary second permanent incisor
A
- labial outline not as rectangular as central incisor
- less bulky and more slender
- cervical region narrowed mesio-distally, giving a long mesial surface with sharp mesio-incisal anngle and short distal surface with a pronounced rounding of the disto-incisal angle
- crown appears wedge shaped when viewed medically or distally
- lingual surface has 2 pronounced marginal ridges
- sometimes where the ridges meet at the cervix they enclose a depression or fossa
- One tapering root, slightly flattened. One root canal; two cornea one mesial and one distal. Distal groove is more prominent than the mesial
Variations:
- peg shaped lateral (congenital) very conical and non functional
- tooth often absent from dentition (congenital) hypodontia
- dens invaginatus where palatal pit is abnormally deep, enamel and destine finds within the pulp chamber. Causes pulpal necrosis in 5% of cases (dens in dente tooth within a tooth)
3
Q
Mandibular first permanent incisor
A
- manually crown appears flat, almost symmetrical
- disto-incisal angle is marginally rounded than mesio-incisal angle
- from mesial or distal aspect crown appears wedge shaped, leans lingually
- lingually faint marginal ridges and small cingulum
- one root flattened mesio-distally. Mesial and distal surfaces are grooves, distal groove more pronounced. One root canal with mesial and distal pulp horns
Variations:
- may get two root canals
- root may be bifurcated at the apex
4
Q
Mandibular second permanent incisor
A
- labially crown appears more fan shaped than the central incisor
- mesio incisal angle is sharp and disto incisal angle rounded
- mesial side is slightly longer than distal side
- from mesial or distal aspect crown is wedge shaped and leans lingually
- lingual surface similar to central incisor
- viewed from incisal edge crown is slightly twisted on root to follow the dental arch. One root, flattened mesio distally and sometimes distally inclined. Distal groove more pronounced than mesial groove. One root canal, two cornua mesial and distal
No variations to note
5
Q
Maxillary permanent canine
A
- Crown comes to a point or cusp at the incisal surface
- labial surface is convex and has a mesial slope and a distal slope, distal being longer
- distal surface is also more bulbous than mesial surface
- palatal surface has marginal ridges, large cingulum and mesial and distal fossa
- one long tapering root, one root canal no pulp horn
- longest tooth in the mouth
Variations:
- labiopalatal measurement may be exaggerated
- cingulum maybe pointed
- tip of root bend sharply distally
6
Q
Mandibular permanent canine
A
- less bulky than upper canine
- viewed labially the crown is tall compared to its width, it is smooth, convex and has a single cusp which tends to incline distally
- whole tooth tends to have a distal sweep
- distal surface is more bulbous than mesial surface
- lingually - similar to maxillary permanent canine though the marginal ridges and cingulum are less pronounced
- two lingual fossae distal being greater if the two
- one root, flattened mesio-distally with a mesial and distal groove. Distal usually the more prominent. One root canal no pulp horns
Variations:
- partial bifurcation of root to a labial and lingual root
- single longitudinal root with two root canals
7
Q
Maxillary first premolar
A
- crown has two cusps, one buccally and one palatally
- buccally cusp is the larger or the two
8
Q
Maxillary second premolar
A
- two cusps, one buccal and one palatal the buccal being slightly larger
- cusps not as high as the first premolar making crown appear shorter
- as with first premolar, cusp is tilted mesially
- the crown is flattened mesio distally
- the cusps sit directly above the root
- oval occlusal outline, fairly symmetrical
- mesiodistal fissure does not interrupt mesial marginal ridge
- root is flattened mesio-distally. Longer than roots of maxillary first premolar. Root may curve distally at the apex. More prominent groove on the distal side. There may be one or two root canals and two pulp horns
Variations:
- crown may flare out or taper in at the cervix
- may see an accessory cusp on distal slope of buccal cusp
- additional shallow grooves radiating from central fissure may be visible
- very rarely root may bifurcate similar to first premolar (no more than 10%)
9
Q
Mandibular first premolar
A
- crown has 2 cusps - one large buccal cusp and a much smaller lingual cusp
- viewed mesially or distally the buccal cusp leans lingually
- lingual cusp tends to overhang the root
- occlusal surface shows a rounded outline distally and a slight angled outline mesially With a developmental groove interrupting the mesio-lingual marginal ridge
- overall shape of crown (for both lower premolars) more rounded compared to the more squashed shape in mesio-distal dimension of upper premolars
- two fossae, one medial and one distal, the distal being the larger of the two.
- one root, triangular in cross section with rounded angles and medial and distal groove. may curve distally at the apex. One root canal and one buccal pulp horn
Variations:
- lingual cusp may be larger than normal, or may be missing altogether therefore resembling cingulum of mandibular canine
- accessory cusps may be present on slopes of buccal/ lingual cusps
- rarely the root may be bifurcated
- crown may have two lingual cusps
10
Q
Mandibular second premolar
A
- crown may comprise two or three cusps, one buccal and one or two smaller lingual cusps
- if there is a single lingual cusp it will be displaced mesially. If two lingual cusps the mesio lingual cusp will be the larger of the two
- viewed buccally the crown has one cusp where the mesial slope is shorter than the distal slope
- mesial marginal ridge is higher than the distal marginal ridge
- from the mesial or distal aspect the buccal cusp leans lingually and the lingual cusps overhang the root
- occlusal outline is rounded when there is only one lingual cusp and more angular when a second lingual cusp is present. In both cases t shared the overall rounded occlusal profile of the lower first premolar compared to the uppers
- in the two cusped crown form central fissure curves around buccal cusp to join the medial and distal fossae (distal largest)
- In the three cusped form there is a central pit with three grooves radiating from it: Mesial and distal developmental grooves running to mesial and distal fossae, lingual groove extends between the lingual cusps to lingual surface
- single root similar to mandibular first premolar. Root curves distally at the apex. One root canal and a pulp horn to each cusp
Variations:
- crown may flare out to a wide occlusal surface from a narrow cervix
- very rarely the root may be partially bifurcated
11
Q
Maxillary first permanent molar
A
- largest maxillary tooth
- crown has 4 cusps - mesio palatal, mesio buccal, disto palatal and disto buccal
- mesio palatal cusp is the largest, mesio buccal cusp is the highest
- viewed occlusally the crown is an equilateral rhomboid in shape
- in approximately 50-70% of people, a fifth cusp is present on the palatal surface of the mesio-palatal cusp (cusp of carai)
- oblique ridge (made up of triangular ridge of DB cusp and distal ridge of MP cusp) joins the mesio palatal and disto buccal cusps
- four cusps are separated by a fissure pattern roughly in the shape of the H, the horizontal bar of the H is formed by a fissure which crosses the oblique ridge
- 3 occlusal fossae: mesial buccal and palatal.
- 3 roots two buccal and one palatal, palatal root is the longest. Three root canals and four pulp horns
Variations:
- cusp of caravels sometimes absent
- occasionally partial fusion of buccal roots or of the palatal and disto buccal root
- rarely, palatal or mesio-buccal root may be partially divided
- enamel pearls occasionally present cervically on mesially or distal surfaces
- disto-palatal cusp may be underdeveloped
- rarely, an extra small root may be present on buccal side
- a shallow concavity sometimes present on palatal surface of palatal root next to cemento-enamel junction. Site may be prone to caries
12
Q
Maxillary second permanent molar
A
- crown has 4 cusps (mesio palatal, mesio buccal, disto buccal and disto palatal)
- disto palatal cusp much smaller than that of the first molar, sometimes absent
- bucco-palatal diameter of crown similar to maxillary first molar, mesio-distal diameter is much less in proportion
- no cusp of carabelli
- 3 roots, two buccal one palatal closer together and slope distally
- fusion of the roots more common than in maxillary first molar
- oblique ridge joins mesio-palatal cusp and disto-buccal cusp
- both distal cusps greatly reduced in size
- three root canals and three or four pulp horns depending on number of cusps
Variations:
- crown may have 3 cusps (disto-palatal absent)
- three cusps compressed
- root fusion particularly between two buccal roots or palatal and MB
- size and shape of palatal root may vary
- enamel pearls occasionally present on mesial and distal surfaces
13
Q
Mandibular first permanent molar
A
- largest mandibular tooth
- crown comprises 5 cusps: 3 cusps on the buccal side and 2 on lingual side
- occlusally a Y shaped fissure pattern formed by lingual and 2 buccal fissures
- occlusal aspect roughly oblong
- buccal surface is noticeably convex (bulbous) and divided into 3 lobes each topped by a buccal cusp; between the lobes runs a shallow groove ending in a buccal put in 60% of cases prone to dental caries
- viewed from the mesial aspect the buccal cusps leans lingually (as with lower premolars) the lingual cusps tend to overhang the root
- 2 roots, one mesial and one distal. Mesial is flattened mesio distally and curves distally with a longitudinal groove present. Distal root slightly shorter, more rounded and less distally curved. Two sometimes three root canals and a pulp horn to each cusp
Variations:
- four cusps instead of 5, giving more circular outline (similar to 2nd mandibular molar)
- mesial root may occasionally be bifurcated, giving tooth 3 apices
- rarely an accessory root grows out of base of distal root on lingual side
14
Q
Mandibular second permanent molar
A
- 4 cusps: two buccaneers and 2 lingual
- lingual cusps higher than the buccal cusps
- from the mesial or distal aspect the buccaneers cusps lean lingually, in a similar way to all other lower molars and premolars
- rectangular occlusal outline with a cusp at each corner
- central cruciform fissure pattern separates the cusps (hot cross bun)
- lingual cusps separated by lingual groove- extends from occlusal half of the lingual surface to the centre of the occlusal surface where it joins the buccal groove
- buccal groove separates buccal cusps terminating in a buccal pit
- not as wide mesio distally as mandibular first molar
- bulbous buccal surface lingually inclined
- 2 roots similar to mandibular permanent first molar, less wide and closer together
- two or three root canals, one pulp horn per cusp
Variations:
- crown form may be similar to mandibular first molar- three buccal and two lingual cusps
- roots partially fused
- distal curvature of roots vary greatly
- very rarely: partial division of mesial root
15
Q
Mandibular second permanent molar
A
- 4 cusps: two buccaneers and 2 lingual
- lingual cusps higher than the buccal cusps
- from the mesial or distal aspect the buccaneers cusps lean lingually, in a similar way to all other lower molars and premolars
- rectangular occlusal outline with a cusp at each corner
- central cruciform fissure pattern separates the cusps (hot cross bun)
- lingual cusps separated by lingual groove- extends from occlusal half of the lingual surface to the centre of the occlusal surface where it joins the buccal groove
- buccal groove separates buccal cusps terminating in a buccal pit
- not as wide mesio distally as mandibular first molar
- bulbous buccal surface lingually inclined
- 2 roots similar to mandibular permanent first molar, less wide and closer together
- two or three root canals, one pulp horn per cusp
Variations:
- crown form may be similar to mandibular first molar- three buccal and two lingual cusps
- roots partially fused
- distal curvature of roots vary greatly
- very rarely: partial division of mesial root
