Dentition and Root Morphology Study Notes
Dentition: Arrangement, Development, and Root Morphology
Arrangement of Teeth
Dentition: Refers to the arrangement of teeth.
Primary Dentition: Consists of the deciduous (baby) teeth.
Secondary Dentition: Consists of the permanent teeth.
Stages of Dentition (p. 37)
Primary Dentition Period:
Begins with the eruption of the first deciduous tooth (typically a central incisor at approximately months).
Lasts as long as only deciduous teeth are present in the oral cavity.
Mixed Dentition Period:
Begins around age with the eruption of the first permanent molar.
Characterized by the presence of both primary and secondary teeth.
Ends when the last deciduous tooth exfoliates (sheds).
Permanent Dentition Period:
Begins when the last primary tooth is lost, usually around age .
Ideally, this period never ends (if all permanent teeth are retained).
Edentulous: Term used when all permanent teeth are lost, meaning no period of dentition exists.
Partially Edentulous: Term used when some permanent teeth are lost.
Permanent Tooth Eruption Schedule (Approximate Ages)
Upper Teeth (Maxillary Arch):
Central Incisor: - Years
Lateral Incisor: - Years
Canine (Cuspid): - Years
First Premolar (First Bicuspid): - Years
Second Premolar (Second Bicuspid): - Years
First Molar: - Years
Second Molar: - Years
Third Molar (Wisdom Tooth): - Years
Lower Teeth (Mandibular Arch):
Central Incisor: - Years
Lateral Incisor: - Years
Canine (Cuspid): - Years
First Premolar (First Bicuspid): - Years
Second Premolar (Second Bicuspid): - Years
First Molar: - Years
Second Molar: - Years
Third Molar (Wisdom Tooth): - Years
Dental Arches and Quadrants
Dental Arches: The dentition is divided into two arches:
Maxillary Arch: Teeth in the upper jaw.
Mandibular Arch: Teeth in the lower jaw.
Each arch comprises half of the dentition, containing teeth.
Quadrants: The arches are further divided into right and left halves by the midline, creating four quadrants (two in each arch).
Each quadrant contains one-fourth of the dentition, or teeth.
A quadrant has a mirror image on the other side of its arch and an opposing quadrant in the opposite arch.
Midline: The vertical midsagittal plane dividing the right and left sides of the body and face, separating the quadrants.
Quadrant Composition:
Permanent Dentition Quadrant: Contains a central incisor, lateral incisor, canine, first premolar, second premolar, first molar, second molar, and third molar.
Deciduous (Primary) Quadrant: Contains five teeth: two incisors (central and lateral), a canine, a first molar, and a second molar.
Succedaneous and Non-Succedaneous Teeth
Succedaneous Teeth: Permanent teeth that replace (succeed) deciduous teeth (e.g., permanent incisors, canines, and premolars).
Permanent premolars replace the deciduous molars.
Non-Succedaneous Teeth: Permanent teeth that do not replace deciduous teeth (e.g., permanent molars).
Naming and Coding Teeth
Identification Order: When identifying a specific tooth, the sequence is: dentition, arch, quadrant, and tooth name (e.g., permanent, mandibular, right, central incisor).
Standard Systems:
Universal System
FDI System (Federation Dentaire Internationale)
Palmer Notation System
Universal System
Uses Arabic numerals through for permanent teeth and letters A through T for primary teeth.
Permanent Teeth: Number is assigned to the most posterior molar on the upper right (permanent maxillary right third molar). The numbering proceeds clockwise through the maxillary arch, then drops to the mandibular left third molar and proceeds counter-clockwise to the mandibular right third molar.
Primary Teeth: Letter A is given to the primary maxillary right second molar, and the letter T to the primary mandibular right second molar. The lettering follows a similar clockwise/counter-clockwise pattern.
Palmer Notation System
Quadrants are determined by the intersection of a vertical and a horizontal line.
Each of the four quadrants is given its own quadrant bracket.
Depicts teeth as if looking at a patient.
Right quadrant teeth have the bracket to their right (e.g., for permanent maxillary right canine).
Left quadrant teeth have the bracket to their left (e.g., 3_ for permanent maxillary left canine).
Numbers or letters are assigned based on position relative to the midline.
Lowest number is closest to the midline; numbers increase farther from the midline.
Permanent teeth are numbered through (central incisor to third molar) within each quadrant.
Primary teeth use capital letters A through E (central incisor to second molar) within each quadrant.
Federation Dentaire Internationale (FDI) System
Each tooth (deciduous or permanent) is assigned a two-digit number, with no duplicates.
First Digit: Indicates the quadrant and whether the tooth is permanent or deciduous.
Permanent quadrants are numbered: (upper right), (upper left), (lower left), (lower right).
Deciduous quadrants are numbered: (upper right), (upper left), (lower left), (lower right).
All teeth within a specific quadrant share the same first digit.
Second Digit: Denotes the tooth's position relative to the midline.
The lowest number is given to the tooth closest to the midline (e.g., for central incisor, for third molar).
Example: Permanent maxillary right central incisor is . Primary mandibular left first molar is .
Permanent Dentition – Incisors (Chapter 10)
General Characteristics:
Incisal two-thirds appear flattened on labial and lingual sides.
Possess an incisal (biting) edge, not a cusp.
Permanent Maxillary Incisors (Chapter 12):
Crown is wider mesiodistally than faciolingually.
Root has a triangular cross-section, broader on the facial side.
Permanent Central Incisor – Maxillary (Chapter 12):
Greater crown : root ratio (crown larger; root similar to or smaller than lateral incisor).
Mesioincisal angle is relatively sharp ( angle), with the contact area in the incisal third.
Distoincisal angle is more rounded.
Broad, smooth lingual fossa and a well-developed cingulum.
Pulp cavity is one large single chamber and root canal.
Pulp chamber ends incisally as one rounded form or two less sharp pulp horns (mesial and distal).
Permanent Lateral Incisor – Maxillary:
Smaller crown : root ratio (crown smaller; root similar to or larger than central incisor).
Mesioincisal angle is more rounded, with contact area at the junction of the middle and incisal thirds.
Small cingulum; often features a lingual pit (a common site for caries).
Lingual anatomical features are similar to central incisors but are often more highly developed, with more prominent marginal ridges (mesial/distal) and a deeper lingual fossa.
Exhibits three sharp pulp horns.
Note: This tooth exhibits the most deviation in morphology among all teeth.
Lateral Incisor Right vs. Left Differentiation:
Mesioincisal angles are generally more square than distoincisal angles.
Crest of the cervical line is more often displaced toward the distal when viewed from the labial or lingual.
Mesiocervical line curves more incisally than the distocervical line.
Maxillary vs. Mandibular Incisors (Chapter 12):
Mandibular incisors are smaller than maxillary central or lateral incisors; the mandibular central incisor is the smallest tooth in the oral cavity.
Mandibular crowns are wider faciolingually than mesiodistally.
Mandibular roots have an oval cross-section.
Incisal edge wears on the labial surface in mandibular incisors.
Permanent Central Incisor – Mandibular:
Incisal View: Incisal edge is perpendicular to the faciolingual axis of the tooth.
Mesial and distal lobes appear identical.
Occludes with only one opposing tooth.
Derived from lobes ( labial; lingual).
May exhibit mamelons (developmental lobes on incisal edge of newly erupted incisors).
This tooth is bilaterally symmetrical, making it very difficult to differentiate left from right without other cues.
Permanent Mandibular Central Incisor - Right vs. Left Differentiation:
Cervical line curves more incisally on the mesial than on the distal surface.
Height of curvature of the cervical line on the mesial is greater than on the distal surface.
Root tip may have a slight distal curve.
Incisal edge often appears worn wider on the distal surface.
Permanent Lateral Incisor – Mandibular:
Incisal View: Distoincisal edge is angled or rotated toward the lingual side.
Distal lobe appears larger than the mesial lobe.
Generally bigger, wider, and longer than the mandibular central incisors.
Root is slightly wider, thicker, and longer than the central incisor root.
Proximal grooves on the root may give the appearance of a double root.
Root is usually straight.
Both central and lateral mandibular incisors have three pulp horns and a single, straight, and narrow root canal.
Permanent Mandibular Lateral Incisor - Right vs. Left Differentiation:
Cervical line curves more incisally on the mesial than on the distal surface.
Incisal View: Distal half of the incisal edge is rotated toward the lingual side.
Incisal edge is worn wider and longer on the distal surface.
Permanent Canines (Chapter 13)
General Characteristics:
Possess a single conical cusp with a well-developed mesiofacial lobe.
Feature a lingual cusp ridge extending from the cusp tip to the lingual fossa.
Permanent Maxillary Canines:
Lingual surface has well-developed marginal ridges, cingulum, and fossa.
Larger and bulkier than the incisors and mandibular canines, with more distal convexity.
Cusp tip is directly mid-center over the root.
Formed from developmental lobes ( facial & lingual), with the middle lobe extension forming the single cusp.
Have the longest roots of any teeth, with a conical shape and a blunt root apex.
Root may turn sharply to the distal or mesial side in the apical third, most commonly distally.
Permanent Maxillary Canines - Right vs. Left Differentiation:
Cervical line curves more incisally on the mesial than on the distal surface.
Incisal View: Distofacial lobe is elongated or “pulled out”.
Facial View: Distal surface is more rounded, and the contact area is located more cervically.
Permanent Mandibular Canines (Chapter 13):
Lingual surface is almost smooth with poorly developed ridges, cingulum, and fossa.
Have a smaller mesiodistal width than the maxillary canines.
Exhibit more wear on the facial surface compared to maxillary canines.
Permanent Premolars (Chapter 14)
General Characteristics:
Possess at least two cusps: one single facial cusp and one or two lingual cusps.
Permanent Maxillary Premolars (Chapter 14):
Typically have two major cusps (one buccal and one lingual) that are approximately equal in size.
Are distinctly wider faciolingually than mesiodistally.
Proximal View: Facial and lingual cusps are almost the same height and both are located over the root trunk.
Permanent First Premolars – Maxillary:
Facial cusp is slightly longer than the lingual cusp.
Frequently has two roots (buccal and lingual).
Occlusal surface has a well-developed central groove with minimal supplemental grooving.
Mesial surface often has a depression above the contact area that starts below the cervical line and usually extends onto the root.
Permanent First Premolars - Maxillary Right vs. Left Differentiation:
Features a mesial marginal groove.
Cervical line on the mesial surface curves more occlusally than on the distal surface.
Occlusal View: Mesiofacial cusp ridge forms a angle with the mesial marginal ridge; the distofacial cusp ridge forms a more rounded angle with the distal marginal ridge.
Permanent Second Premolars – Maxillary:
Facial and lingual cusps are nearly the same height.
Usually single-rooted.
Central groove is short, with frequent and numerous supplemental grooves.
Lack the depression found on the mesial and distal crown surfaces of first premolars.
Permanent Second Premolars - Maxillary Right vs. Left Differentiation:
Lingual cusp is displaced slightly toward the mesial side.
Permanent First Premolars – Mandibular:
Proximal View: Occlusal surface is tilted strongly toward the lingual side.
Occlusal View: Oval outline with a strong transverse ridge and no central pit.
Permanent First Premolars - Mandibular Right vs. Left Differentiation:
Cervical line on the mesial surface curves more occlusally than on the distal surface.
Frequently has a depression or groove where the mesial marginal ridge joins the lingual cusp ridge.
Distal marginal ridge is more prominent.
Permanent Second Premolars – Mandibular:
Occlusal View: Pentagonal (five-sided) outline, with a central pit and no transverse ridge.
Proximal View: Occlusal surface is less tilted lingually compared to the first premolar.
May have two lingual cusps.
Permanent Second Premolars - Mandibular Right vs. Left Differentiation:
Proximal View: More of the occlusal surface is visible from the distal than from the mesial due to the distal inclination of the crown axis to the root axis.
Permanent Molars
General Characteristics:
Possess three to five cusps, with at least two on the facial side.
Tooth roots do not always curve; if they do, they typically curve distally.
Permanent Maxillary Molars:
Crowns are wider faciolingually than mesiodistally.
Have three roots (two on the facial side and one on the lingual side).
Occlusal View: Wider on the lingual than on the buccal.
Permanent First Molars – Maxillary (Chapter 15):
Occlusal View: Features a strong oblique ridge that is less likely to be crossed by a groove.
Three widely separated roots.
Frequently has a fifth cusp, known as the Cusp of Carabelli, located on the mesiolingual cusp.
Permanent First Molars - Maxillary Right vs. Left Differentiation:
Mesiolingual cusp is always much larger than the distolingual cusp.
Permanent Second Molars – Maxillary:
Occlusal View: Features a smaller oblique ridge usually interrupted by a groove.
Roots are closer together compared to first molars.
Does not possess a fifth cusp (no Cusp of Carabelli).
Distolingual cusp is smaller than on the first molar.
Permanent Second Molars - Maxillary Right vs. Left Differentiation:
Mesiolingual cusp is always much larger than the distolingual cusp.
Permanent Third Molars – Maxillary:
Distolingual cusp is progressively smaller or may be missing entirely.
Roots are either fused or very close together and much shorter.
Lack an oblique ridge.
Permanent Third Molars - Maxillary Right vs. Left Differentiation:
Distofacial cusp is much shorter.
Roots typically curve distally.
Permanent Mandibular Molars:
Crowns are wider mesiodistally than faciolingually.
Lingual height of contour is located at the middle third.
Have two roots (one mesial and one distal).
Permanent First Molars – Mandibular:
Possess three facial cusps and two facial (buccal) grooves.
Roots are widely separated and relatively vertical.
Permanent First Molars - Mandibular Right vs. Left Differentiation:
Distal cusp is the smallest facial cusp.
Permanent Second Molars – Mandibular:
Possess only two facial cusps and one facial groove.
Occlusal groove is well-defined, travels straight mesial to distal, and forms a cross (+) with the facial and lingual grooves.
Roots are close together.
Permanent Second Molars - Mandibular Right vs. Left Differentiation:
Buccal height of contour is in the cervical third; lingual height of contour is in the middle third.
Permanent Third Molars – Mandibular:
Exhibit secondary and tertiary anatomy (more variable and irregular features).
Roots: Short, often fused, and curved distally.
Permanent Third Molars - Mandibular Right vs. Left Differentiation:
Crown tapers distally, making it wider faciolingually on the mesial than on the distal surface (also true for mandibular first and second molars).
Deciduous / Primary Dentition (Chapter 16)
Deciduous Teeth: Also known as primary or milk teeth; they are shed and replaced by their permanent successors.
Exfoliation: The process of shedding and replacement.
Begins - years after the deciduous root is completely formed, when the root starts to resorb at its apical end.
Resorption continues crown-ward until the entire root is resorbed, leading to the tooth's loss due to lack of anchorage.
Eruption Sequence:
First deciduous teeth to erupt (around months average) are typically the mandibular central incisors.
Maxillary central incisors usually erupt about a month later.
Generally, the first primary mandibular tooth erupts before the corresponding maxillary tooth.
Deciduous Eruption Times (Approximate Months):
Upper Teeth:
Central Incisor: - Months
Lateral Incisor: - Months
Canine (Cuspid): - Months
First Molar: - Months
Second Molar: - Months
Lower Teeth:
Central Incisor: - Months
Lateral Incisor: - Months
Canine (Cuspid): - Months
First Molar: - Months
Second Molar: - Months
Easier Eruption Sequence to Remember:
Central Incisors
Lateral Incisors
First Molars
Canines
Second Molars
Essential Differences Between Deciduous and Permanent Teeth
Size and Proportions:
Deciduous anterior teeth are smaller in crown and root proportions than their permanent successors.
Deciduous molars are wider mesiodistally than the permanent premolars that replace them.
Root Shape (Anterior): Roots of deciduous anterior teeth are narrower and longer relative to crown length, tooth length, and width, compared to permanent roots.
Root Shape (Posterior): Roots of deciduous posterior teeth are very narrow at their cervical enamel junctions (CEJ). Deciduous molar root trunks are very short.
Cervical Ridge (Anterior): The cervical ridge of enamel at the cervical third of anterior crowns (labially and lingually) is much more prominent in deciduous teeth, extending from their narrow cervical necks.
Buccocervical Ridges (Molars): Buccocervical ridges on deciduous molars are much more pronounced, especially on first molars. These prominences give deciduous crowns a bulbous appearance and accentuate the narrower cervical portion of the roots.
Occlusal Taper (Molars): Buccal and lingual surfaces of deciduous molars taper occlusally above the cervical curvatures much more than permanent molars, resulting in a much narrower buccolingual occlusal table.
Molar Roots: Deciduous molar roots are more slender and longer than permanent roots. They also flare apically to accommodate the developing permanent tooth crowns between them.
Color: Deciduous teeth are usually lighter, with a whiter color and a bluish cast, whereas permanent teeth have more yellow, gray, or brown tones.
Pulp Chambers: Pulp chambers are relatively large compared to the deciduous crowns that enclose them.
Pulp Horns: Pulp horns extend rather high occlusally, placing them much closer to the enamel than in permanent teeth.
Dentin Thickness: Dentin thickness between the pulp chambers and enamel is much less than in permanent teeth.
Enamel Thickness: Enamel is relatively thin and of consistent depth.
Roots (Specifics):
Deciduous second molars have roots that are twice as long as the crown.
Roots are long, slender, and very flared.
Root trunk is very short, bifurcating immediately below the cervix of the tooth.
Mandibular deciduous molars have two roots (mesial and distal); the mesial root often has two root canals and a longitudinal groove, while the distal root has one canal and no grooves.
Pulp Cavities (Specifics):
Deciduous tooth pulp cavities mirror the outer form of the teeth, but pulp horns are longer and more pointed.
Pulp chambers are large in proportion to tooth size, and pulp horns are more extreme.
Importance of Deciduous Teeth
Developmental Guidance: Critical for proper muscle development of mastication, formation of jaw bones, and the eventual location, alignment, and occlusion of permanent teeth.
Precursor Function: Succedaneous teeth develop as buds from the deciduous tooth buds.
Space Maintenance: Deciduous teeth maintain space for the permanent teeth to erupt into.
Bone Growth: Their eruption facilitates bone growth of the dental arches.
Primate Spaces (Fig. 6-2): Spaces that develop between deciduous teeth as bone continues to grow.
Leeway Spaces (Fig. 6-3): Spaces between deciduous canines and first molars, and between first and second molars. These provide extra margin for the eruption of permanent canines ('s), first premolars ('s), and second premolars ('s).
This space is necessary because the mesiodistal width of the two permanent premolars combined is less than that of the two deciduous molars they replace.
However, this leeway space is often offset by mesial drift, where the first permanent molar tends to move mesially, shortening the space reserved for premolars.
Clinical Implication: If a deciduous molar is prematurely lost, a permanent molar will often push into this space, blocking the eruption of the premolar.
Eruption Guidance: Resorption of deciduous roots helps guide their erupting permanent replacements into proper locations. Succedaneous teeth follow the resorbing root through the bone until the deciduous tooth exfoliates due to lack of root anchorage.
Root Morphology (Chapter 11)
Functions of Roots
Support/Anchorage: Offer a system of support, anchoring the teeth firmly in the bone.
Sensory System: Afford a sensory system to warn of threats to the teeth.
Nerve of a tooth can be stimulated when a stimulus is carried from the root surface through dentin tubules to the nerve tissue.
Root decay, resorption, or abrasion exposes dentin tubules, causing a pain response.
Rubbing the root surface with an instrument can elicit pain.
Bare areas of dentin exposed by absent cementum can stimulate pulpal nerves.
Pulpal Inflammation: If pulp tissue is inflamed, hot or cold stimuli cause pain. The longer the pain subsides, the more damaged the pulpal tissue.
Infected/Necrotic Pulp: If gases are present due to infection/necrosis, a heated stimulus expands these gases, putting pressure on vital nerve tissue. Expanded gases can then force themselves out the root apex into the surrounding bone and periodontal ligament (PDL).
Pain vs. Pressure/Temperature: Pulp tissue only elicits pain responses. Pressure and temperature responses are elicited by nerve tissue within the bone, gums, and PDL, not the root canal tissues directly.
Reparative Methods: Provide methods to respond to pathology, pressure, trauma, or movement.
Dentin Formation: Odontoblasts inside the tooth allow for the formation of secondary and reparative dentin in response to trauma. This process occurs throughout the pulp chamber.
Cementum Formation: The apical third of the root can continue to form cementum on its outside.
Hypercementosis: Extreme formation of cementum, creating a cementoma at the root apex, usually associated with bone destruction and/or trauma.
Cellular Cementum: This type of cementum can continue to grow, trapping cells within it.
Nourishment System: Houses the nourishment system of the tooth.
Arteries, veins, and lymph tissue within the root canal nourish the tooth from the inside.
These vessels enter and exit through the apical foramen (an orifice at the root apex).
They circulate nutrients and oxygen, remove harmful products and carbon dioxide.
Restricted blood flow (anoxia) can lead to death of nerves and other pulp tissues.
Detailed Support Functions of Roots
Shape and Length: Directly affect anchorage and support.
Longer and wider roots provide more support and are more firmly embedded.
Surface Area: Greater surface area allows more periodontal fibers to attach root to bone.
Concavities and grooves also increase surface area and allow PDL attachment at different angles.
Multiple Roots: Disperse periodontal ligaments in more directions than single-rooted teeth.
Cross Section: Roots with a triangular cross-section offer resistance to lateral displacement.
Curvature: Curved roots provide resistance to occlusal, apical, and distal forces.
Furcation Areas: Multiple periodontal fiber directions in furcation areas between roots give direct resistance to occlusal displacement.
Overall Resistance: The width, shape, length, curvature, and number of roots all influence a tooth's resistance to forces.
Tooth Movement
Periodontal Ligament (PDL):
Composed of collagenous connective tissue fibers, capable of being tensed or compressed.
Pressure on a tooth compresses PDL fibers on one side and tenses them on the other.
Mobility: A small movement of the tooth; a slight amount is healthy and normal.
Bone Remodeling (Orthodontics):
Strong external force exerts pressure on the bone, triggering a resorption process in the alveolar bone.
Osteoclasts (white blood cells) dissolve bone in areas of pressure.
After enough bone is resorbed, pressure ceases, PDL regains normal width, and the tooth moves into the newly remodeled area.
On the opposite side, the tensed PDL stimulates osteoblasts (bone-forming cells) to form new bone.
This pressure-and-tension remodeling moves the tooth to a new location.
Orthodontics: Achieved by sustained force causing gradual tooth movement.
Requires holding the tooth fixed in its new location for PDL collagenous fibers to remodel; otherwise, residual tension causes relapse.
Caution: Excessive pressure can lead to resorption of both bone and root.
Continuous Eruption: If a tooth lacks an occlusal antagonist, it continues to erupt.
Mesial Drift: A tooth moves mesially if there is no adjacent tooth on its mesial side. Root shape and residual PDL tension may contribute to this phenomenon.
Periodontal and Hygiene Considerations
Root Grooves and Depressions: These areas are harder to clean and more susceptible to periodontal disease.
Canines and premolars have longitudinal grooves but are generally easier to clean than molar roots.
Molars are further back, harder to reach, and have wider buccolingual roots, making the middle root areas difficult to access.
Furcation Involvement: A major source of periodontal problems.
Furcation: The point where multi-rooted teeth separate their roots.
Bifurcation: Where buccal and lingual roots divide (e.g., maxillary premolars, occasionally mandibular canines, mandibular molars at mesial/distal roots).
Trifurcation: Between three roots (e.g., maxillary molars).
Furcations are difficult to clean, often leading to severe periodontal issues.
Root Surface Roughness: The outer surfaces of roots are rougher than smooth enamel, making plaque, calculus, and debris harder to remove.
Root Canals (Internal Anatomy)
Anterior Teeth: Usually have one large root canal per tooth.
Mandibular canine sometimes has two canals, separated by a deep longitudinal groove (more prominent on the distal).
Apical Foramen and Accessory Canals:
Nerves and blood vessels enter/leave through the root apex.
Often, more than one opening exists: one main apical foramen and several accessory canals.
If a root has two apical openings, each is smaller than if there were only one.
Similarly, if a root has two root canals, each is smaller than if it had only one.
Maxillary First Molar:
Has three roots, with at least one canal per root (mesiobuccal, distobuccal, lingual).
The mesiobuccal root often has two canals, which are smaller than the canals in the other two roots.
Most likely tooth to have four canals (two in the mesiobuccal root).
Premolars:
Lower premolars usually have one canal.
Upper premolars often have two canals.
Maxillary first premolar may have two canals and even two roots (buccal and lingual).
Mandibular Molars:
Usually have two canals: mesial and distal.
The mesial canal is typically wider and larger than the distal.
The mandibular first molar is the most likely tooth to have two canals in its mesial root (a buccal and a lingual canal), which are considerably smaller than the distal canal in the same tooth.
Second Molars: Usually have only mesial and distal root canals.
Lower Third Molars: Can have one, two, three, or more canals.
Maxillary Molars: Usually have three canals (one for each root: mesiobuccal, distobuccal, and lingual).