This document provides information on the morphology, root canal anatomy, and access cavities for various individual teeth. Key details include: - The maxillary first molar typically has 3 roots (mesiobuccal, distobuccal, palatal) and 4 canals, or occasionally 3 canals. The mesiobuccal root is the most challenging to treat due to its morphology. - The mandibular first molar usually has 3-4 canals, with two in the mesial root that are highly curved, and one or two straight canals in the distal root. - Various teeth may have anatomical variations or anomalies, such as extra roots, fused roots, or additional

1. Morphology and
Access Cavity Preparations for
Individual Teeth
Dr. Hadil Abdallah Altilbani
BDS Santiago de Compostela University Spain.
MSc. University of Valencia Spain.
Department of Endodontics University of Palestine .

2. • Always Only One Root Canal That Is Straight Or Almost Straight.
• From A Proximal View, The Long Axis Of The Canal Meets The
Incisal Area At The Inslcisal Edge Or slightly Palatally.
• While Access To The Pulp Chamber Is Made From The Palatal
Surface For Aesthetic Reasons
• Average Length - 22.5 Mm
• Morphology - Type I.
• Canal Cross-section Is Slightly Triangular At The Cervical Area,
Gradually Becoming Round In The Apical Area.
• Root May Have A Slight Distal And Lingual Curvature.
• Access - Triangular (If Pulp Horns Present) Lingual Access
Just Above Cingulum; Lingual Shoulder May Prevent Direct
Access And Should Be Removed.
MAXILLARY CENTRAL INCISOR

3. Anomalies
• Talon’s Cusp
• Dens invaginvatus
• Fusion
• Gemination
• Palatogingival Groove
Maxillary Central Incisor
• Mid root and apical lateral canals 24% are common
• Root apex & apical foramen are located disto-labially.
• PULP CHAMBER
• Located in the centre of crown equidistant from dentinal walls
• Broad mesiodistally – broadest part incisally
• Follows contours of crown & has 3 pulp horns which correspond
to mammelons

7. Maxillary Lateral Incisor
• One Canal With An Oval Or Round Cross-section.
• Lateral canals are more frequent (26%) than in maxillary central
incisors
• The Apical Canal Often Curves Distally
• Sometimes The Root Tip Curves Labially, Which Is Difficult To See
In The Radiograph
• Average Length - 22.0 mm
• Morphology - Type I.
• Canal Is Ovoid In The Cervical Area And Round In The Apical Area.
Root Apex Commonly Has A Distal Dilaceration.
• Access - Triangular To Ovoid;
• Pulp Chamber
• Similar To Maxillary Central Incisor (Smaller)
• 2 Pulp Horns Corresponding To Developmental Mammelons
Anomalies
•Dens invaginvatus
•Peg laterals (Gardner’s syndrome)
•Fusion (with Central Incisor)
•Gemination
•Palatogingival Groove

10. Penetration into the tooth is accomplished
along this root's long axis until the roof of
the pulp chamber is penetrated; frequently
a “drop-in effect” is felt when this occurs.
a drop-off will only be felt when the pulp
chamber is at least 2mm deep.

12. Maxillary Canine
• The Longest Tooth
• The Root Canal Is Typically Quite Large, But Often The Few Most Apical
Millimeters Before The Foramen Are Much Narrower.
• Lateral canals are present in 30% cases
• This May Lead To Incorrect Working Length If The Position Of The Apical
Constriction Is Determined Only With Tactile Sensation With The File And
Fingertips.
• May Have A Pronounced Curve, Usually Either Distally Or Labially
• Average Length - 27.0 Mm
• Morphology - Type I.
• Apical Foramen Frequently Not Located At Anatomic Apex.
• Access- Ovoid Above Cingulum; Beware Of Buccal Apical Dilaceration.
• Only one pulp horn is present

14. Pulp Chamber
• Triangular In Shape With Apex
Towards Single Cusp & Broad Base In Cervical
Third Of Crown
• Mesiodistally : Narrow
Resembling A Flame
It has the largest pulp chamber than any
single rooted tooth
Cross-section
• Cervical Slightly Ovoid
• Middle Canal Is Smaller And
Remains Ovoid
• Apical Round
Anomalies
•Dilaceration
•Dens evaginvatus
•Dens invaginvatus
•Supernumery Canine
•2 canals / 2 roots

15. Maxillary First Premolar
• Two Roots And Two Root Canals.
• Occasionally Only One Root Is Present, But Even Then Two
Canals Are Still Often Found.
• The Root Tips Are Very Fine Which May Result In Perforation
Even In A Straight Canal If A Large Apical Open Size Is
Attempted.
• Average length - 20.5 mm
• The Roots Are Often Equally Long But 1 - 2 mm Differences
May Occur.
• The Root Tips And Apical Canals May Curve In The Mesio-
Distal Or Bucco-palatal Dimensions.
• Prominent Developmental Depressions On Mesial And
Distal Root Surfaces (Mesial Root Concavity More Prominent)
• Broader Buccopalatally & Narrow Mesiodistally
• Kidney Shaped Cross Section At CEJ

17. PULP CHAMBER
• Narrow mesiodistally, wider buccopalatally
• Pulp horn under each cusp, buccal pulp horn
more prominent
• Floor is convex
• 2 canal orifices (lies deep in coronal third of
root below cervical line)
Cross-Section
• Cervical Ovoid
• Middle Round
• Apical Round
Canal System
• 2 roots
• When fused roots, a groove running in
occlusso- apical direction divides the root into buccal
& palatal portions each containing a single root canal
Anomalies
• Dens evaginvatus
• Gemination (rare)
• Taurodontism (rare)

24. Maxillary Second Premolar
• Single Root More Often Than The First Premolar.
• In The Cervical Area There Are Often Two Root Canals But In Many Cases They
Unite Before The Apical Foramen.
• The Root Is Normally Straight But May Curve In The Apical Area, Particularly
Distally.
• Prominent Developmental Depressions On Mesial And Distal Root Surfaces
• Upper Second Premolars With Three Roots (Molarization) Are Very Rare.
• Average Length - 21.5 Mm
• Morphology-
• Access - Ovoid

25. PULP CHAMBER
• Narrow mesiodistally
• Wider buccopalatally than Maxillary 1st premolar
• Pulp horn under each cusp, buccal pulp horn more
prominent
Cross-Section
• Cervical Ovoid
• Middle Round
• Apical Round
Canal System
• Single root – 90.3%
• 2 well developed roots – 2%
• 2 roots partially fused – 77%
• When 2 canals are present, they’ll be distinct &
separated along the entire length of root
Anomalies
• Dens invaginvatus
• Taurodontism
• Deep distal root concavity
• 2 roots, 3 canals

26. Mandibular Central Incisor
• Always Has One Root, But Often (20 %) Has Two Root
Canals.
• Av. Tooth Length 20.8 Mm
• The Canal(s) Is Very Flattened: Wide In The Bucco-
lingual Dimension And Narrow In The Mesio-distal
Dimension.
• • Developmental Depressions Present In
Mesial & Distal Root Surfaces
• • Ovoid To Hourglass In Cross Section
• • Usually Single Root Canal System, Ovoid/Ribbon
• Only The Most Apical Part Of The Canal Is More Round.
• The Long Axis Of The Canal Traverses The Incisal Edge Or
The Labial Surface Of The Crown.
• The Canal(s) Of The Lower Central Incisor Is Almost
Always Straight Unlike In The Lower Lateral Incisor, Where
The Root Tip And Canal Often Curve Sharply Distally.

27. PULP CHAMBER
• Small & flat – mesiodistally
• Wide labiolingually
• Tapers incisally
Cross-Section
• Cervical Slightly ovoid
• Middle Round
• Apical Round
Roots
• Straight - 60%
Canals
One canal, one foramen 70.1%
2 canals, 1 foramen 23.4%
2 canals, 2 formina 6.5%
Anomalies
• Fusion
• Gemination
• Dens invaginvatus
• Talon’s Cusp

28. Mandibular Lateral Incisor
• The Lower Lateral Incisor Is Quite Similar To The Lower Central Incisor.
• However, The Lateral Incisor Is Approximately 2 Mm Longer And The Apical Root And
Canal Often Curve Distally.
• Average Length – 20.5 Mm
• Frequently, There Is A Dentinal Bridge Separating The Buccal And Lingual Canals.
• Incidence Of Two Root Canals In Human Mandibular Incisor Teeth..
• One Canal/One Foramen - 57.3%
• Two Canals - 42.7%
• type ii - 41.4%
• type iii - 1.3%
• Thus, 98.7% Have A Single Foramen At Apex
• Access - Triangular To Ovoid.
• Lingual Shoulder Of Dentin May Hide Lingual Canal.
PULP CHAMBER
• Similar to central incisor but slightly larger dimension
• Small & flat – mesiodistally And Ribbon Shaped.
• Wide labiolingually
• Tapers incisally
Anomalies
• Fusion
• Gemination
• Dens invaginvatus
• Talon’s Cusp

29. Mandibular Canine
• Average length - 25 mm
• Morphology-
• Canal is ovoid at cervical and round apically from midroot.
• Lingual dentinal shoulder may be present.
• Root canal anatomy of the mandibular anterior teeth
• One canal/one foramen - 78%
• Two canals - 22%
• Type II - 16%
• Type III - 6%
• Access - Ovoid in shape.
• PULP CHAMBER
• • Resembles maxillary canine but smaller
• • Narrow mesiodistally
• • One pulp horn
• Cross-Section
• • Cervical Ovoid
• • Middle Ovoid (smaller)
• • Apical Round
Anomalies
• Dilaceration
• 2 canals, 2 roots
• 2 canals in single root
• 2 canals in single apical foramen
• Dens evaginvatus

31. • Double canals are particularly frequent in the mandibular first premolars, with
approximately 30% of these teeth having two root canals.
• Molarization in the lower first premolar is very rare.
• Developmental depressions on distal root surface is deeper than mesial surface
• Av. Tooth Length 21.9 mm
• PULP CHAMBER
• • Narrow mesiodistally
• • Wider buccolingually with prominent buccal pulp horn
• • Prominent buccal cusp & small lingual cusp
• Cross-Section
• • Cervical Very narrow and ovoid
• • Middle 2 branches of canals are Round
• • Apical Round
Mandibular First Premolar

32. Canal System
• Single root
•Usually 1 canal – 70%
•1 canal bifurcates into 2 and ends in 2 foramina – 24%
Anomalies
• Dens invaginvatus/ evaginatus
• Gemination
• H-shaped canal
Single Canal Can Split Into 2 Of Which The Buccal
Is Straight & The Lingual Canal Splits At A Right
Angle, This Gives The Appearance Of The Letter
‘H’

35. Mandibular Second Premolar
• The lingual canal is present only occasionally.
• Instead, molarization is more frequent than in the first premolar, yet still quite rare.
• The root canal is oval in cross-section and rather straight with only a slight distal curvature in some canals.
• Average length - 22.5 mm
• Morphology –
• One canal - 97.5%
• Two canals - 2.5% (Type IV)
• Access - ovoid access, with a little more of a M-D extension than the mandibular first
bicuspid.
PULP CHAMBER
• Narrow mesiodistally
• Wider buccolingually
• Prominent Lingual pulp horn
Cross-Section
• Cervical Very narrow and ovoid
• Middle Less ovoid
• Apical Round
Canal System
• Single canal – 97.5%
• Some roots bifurcates exiting in 2 foraminas – 2.5%
Anomalies
• Dens evaginatus
• 2 roots

39. Maxillary 1st Molar
3 Roots– MB, DB, P.
4 Canal– MB1,MB2,DB,P/ 3 Canals MB,DB,P.
•Mesiobuccal Root :
•Broad buccolingually .. is the most challenging to treat.
•Developmental depressions in both mesial & distal root surfaces
•Distobuccal Root :
•Round / ovoid in cross section
•Palatal Root :
•Broad mesiodistally
•Ovoid in cross section
The palatal canal always looks straight radiographically but often has a buccal curvature.
The palatal canal is often 1 - 2 mm longer than the buccal canals.
• Av. Tooth Length 21.3 mm
PULP CHAMBER
•Largest in the arch
•4 pulp horns : MB, MP, DB, DP
•Roof – Rhomboidal in shape
•Roof converges, lingual wall disappears and forms a triangular form
•Orifices are located in the 3 angles of the floor
•Mesiobuccal orifice under mesio-buccal cusp
•May have a depression in the palatal end of the mesiobuccal orifice where a 4th canal may be present
•MB2 canal is located mesial to or directly on a line between the MB and palatal orifice

47. • Dentists are quite familiar with the mesiobuccal,
distobuccal and palatal canals, but not with the fourth canal,
which is known as
the mesiocentric or mesiopalatal, mb2 or accessory mesiobuccal
canal.
Higher occurrence of MB2 discovery in ages 20-40
Locating MB2 orifice –
• Difficult as its buried under dentine bridge formed as a
result of aging reparative dentin formation
• Canal located mesial to or directly on a line between
the MB1 and palatal orifices ,within 3.5mm palatally and 2mm
mesially of MB1 orifice.
Anomalies
• Taurodontism
• Root fusion
• 2 palatal canals
• Single root and single canal
• 2 distal canals
• 2 palatal roots
• C-shaped canals - Rhomboidal (“heart
shaped”)

50. ➢ Roots have a tendency for fusion.
➢ 3 Roots—MB,DB,P/ 2 Roots B & P.
➢ 4 Canals/ 3 Canals / 2 Canal / 1 Canal.
➢ Basic outline is same as 1st M……
➢ The difference being that the orifices of the mb and db canals are closer together; sometimes almost forming a line (mb - db -
pal).
➢ The apical part of the palatal and the mesiobuccal canals is not as curved as in the first molar
MAXILLARY SECOND MOLAR

54. PULP CHAMBER
• Similar to maxillary 1st molar, except narrower
mesiodistally
• Roof – Rhomboidal in shape
• Floor – obtuse triangle
• Mesiobuccal and distobuccal canals closer together
Canal System
Mesiobuccal Root
• Broad buccolingually
• Prominent depression in mesial and distal surfaces
• 1 or 2 canals
Distobuccal Root
• Rounded / ovoid, single canal
• Orifice appears on same line joining mesiobuccal &
palatal canals
Palatal Root
• Broad mesiodistally
• Ovoid, Single canal
Anomalies
• Taurodontism
• Root fusion
• Single root, single canal
• 2 palatal canals in double palatal root
• Incidence of pulp stones

57. MANDIBULAR FIRST MOLAR
• The Mandibular First Molar Is Perhaps The Most Frequently
Endodontically Treated Molar.
• It Usually Has 3 - 4 Canals, Two In The Mesial Root And One Or Two In
The Distal Root.
• Both the mesiobuccal and mesiolingual canals are usually curved
along their whole length, and the curvature is typically greatest in the
apical region.
• The Distal Canal(s) Is Normally Straight All The Way To The Apex, Oval
Or Flattened In Cross-section.
• Often The Most Apical 1 - 2 mm Of This Canal Curves Up To 90
Degrees Distally.
• The mesial canals in the first molar are often a challenge for the
dentist.

59. The canals curve distally, but they also curve buccally or lingually at the
same time.
Bucco-lingual curvatures are not readily seen in the radiograph, which
emphasizes the importance of the dentist's knowledge of possible
variations in canal morphology.
One must routinely search for four canals in the lower first molar.
Both distal and mesial canals can join before the apex.
PULP CHAMBER
• 4 pulp horns : MB, ML, DB, DL
• 3 distinct orifices : MB, ML & distal
• Roof – Rectangular in shape
• Walls converge to form a Rhomboidal Floor
• Pulp horns recede with age and so decrease in chamber size
• Roof is located on the cervical 3rd of the crown just above the
cervix of tooth, floor is located on cervical third of root

60. Three Canals - 64%
Four Canals - 29%
• Mesial Root - Type III - 60%
Type II - 40%
• Distal Root - Type II - 60%
Type III - 40%
Access - Trapezoidal Access Is
Recommended To Locate All The
Canals.
Anomalies
• Taurodontism (most common)
• Supernumery Roots – Radix Entomolaris
• C-shaped canals

62. MANDIBULAR SECOND MOLAR
• The Curvatures Are Milder.
• Average length - 20.0 mm
• Only Two Canals Is A More Frequent Possibility Than In The First Molar.
• A Small Percentage Of Lower Second Molars Have A Special Root Canal Anatomy; Two Or
More Of The Canal Openings In The Pulp Chamber Floor Join To Form A C-shaped Groove.
• This Has Occasioned The Name
• "C-shaped Canals".
• • 2 Rooted
• • Mesial & Distal Roots Close Together
• • Roots Are Broader Buccolingually
• • More Frequently Roots Are Fused
• Pulp Chamber
• • Similar To 1st Molar But Smaller In Size
• Canal System
• • Mesial Root – Higher Incidence Of 1 Canal – 14%
• • Higher Incidence Of Root Fusion
• • C-shaped Canals Are Frequent
• Access– Trapezoidal, Or Oval, Depending On Configuration Found
• Anomalies
• • C-shaped Canals
• • Taurodontism
• • Fused Or Single Canal
• • Supernumery Roots – Radix Entomolaris