Morphology of teeth

Teeth in the frontal section

Upper lateral permanent incisor

Upper Jaw (Maxilla)

Upper central incisor

This is pillar II. classes according to Voldřich.

The vestibular surface has a quadrangular shape, is convex and is divided by two grooves oriented longitudinally with the long axis of the tooth. These grooves gradually disappear with physiological abrasion.

The palatal surface is, unlike the labial, concave. At the neck, it passes into a pronounced tuberculum dentale . On the sides of the palatal surface are the so-called enamel ridges.

The incisal edge is perpendicular to the mesial surface , while the distal surface is rounded in the transition to the incision. Contact points between the central incisors in the upper jaw are located in the incisal third of the mesial surfaces. The characteristic shape of the large upper incisor is given by the ratio of both approximal surfaces to the incisal edge.

The root is massive, conical, slightly curved distally and approximately circular in cross-section. The medullary cavity is first very spacious and extends into three corners. The root canal often has a circular cross-section.

Upper lateral incisor

The small incisor is similar in shape to the middle incisor, but unlike it, it is smaller and more graceful. The shape of the tooth shows considerable variability, we find a rudimentary, so-called cone-shaped shape, relatively often the tooth is not rooted at all.This is pillar III. class according to Voldřich.

The labial surface is convex, more pronounced in the mesial part. Grooving rarely occurs.

The palatal surface is strongly concave, its edges are lined with enamel strips. In the cervical part, we find a well-developed tuberculum dentale, on the coronal side of the bump there is usually a depression - foramen caecum , which can be the place of invagination of enamel and dentin - the formation of dens in dente.

The approximal surfaces are arched, have the shape of a triangle. As with the middle upper incisor, the mesial surface is straighter, it passes into the incisal edge at a sharper angle. In contrast, the distal surface is more convex and slopes gradually towards the cutting edge.

The root is one, more slender and weaker than the root of the upper central incisor. It has an oval shape in cross-section, flattened mesiodistally. From the median plane, the root often deviates in a palatal or distal direction. The root canal is also one, it follows the shape and curvature of the root, which makes the tooth very difficult to treat endodontically.

Upper canine

The canine is the longest tooth in the human dentition, forming the transition of the frontal and lateral sections of the dental arch. It is classified as a first class pillar according to Voldřich. This is the tooth with the least caries, agenesis is rare . It is well amenable to conservation and prosthetic treatment.

Canines

The labial surface of the tooth is noticeably convex, extending into the tip of the crown (apex coronae). The tip divides the initiation edge into a mesial and distal part. The distal part descends more steeply to the proximal surface and is longer. From the tip towards the neck of the tooth, there is an enamel bar dividing the labial surface into a mesial, more arched part, and a distal, larger and flatter part.

The palatal surface is slightly concave, the tuberculum dentale is usually well developed . Not infrequently we can find an enamel mound extending from the tuberculum dentale to the tip of the crown. This ridge then divides the palatal surface into two facets, both of which create small depressions.

The approximal surfaces have a triangular shape, the point of contact is shifted mesially more in the incisal direction. The cementoenamel border is conspicuously arched, but runs in an arcuate fashion, but does not create sharp transitions (V-shaped) as in the incisors.

The root is one, very long (15−18 mm), noticeably massive. It has the shape of an elongated cone, mesiodistally it is flattened, sometimes it bends distally. The tip of the root often reaches the maxillary sinus, it is located near the branching of the vasa infraorbitalis, which can facilitate the spread of inflammation.

Spitz

The pulp cavity is relatively spacious, follows the shape of the tooth, and extends incisally into the corner of the pulp (cornu pulpae).

The root canal is one, spacious, apical ramifications occur in 25% of cases.

Table of the number of roots and canals

Tooth	Designation (Two-digit)	Length [mm]		Number of roots (in percent)			Number of channels (in percent)			The root of the south	Crown Height	Mesiodistal crown width	Labiooral crown width
		According to	According to	1	2	3	1	2	3
Middle Incisor	11 / 21	23	23	100			100			13,0	10,5	8,5	7,0
Lateral Incisor	12 / 22	21 – 22	22,5	100			100			13,0	9,5	6,5	6,0
Spitz	13 / 23	26,5	27	100			100			17,0	10,0	7,5	8,0

Údaje převzaty ze Základů klinické endodoncie, Peřinka 2009 a z Preklinické stomatologie, I. část – morfologická, Jansová–Eber.

Lower Jaw

Lower central and lateral incisor

Human Teeth

The lower permanent incisors are very similar in shape, they differ only in size. The lower central permanent incisor is the smallest permanent tooth. In general, the lower permanent incisors are gracile and therefore difficult to use prosthetically. There is also frequent compression and associated rotation. The crown has a so-called chisel shape. These are pillars III. class according to Voldřich.

• The labial surface is slightly convex with a smooth surface. Similar to the upper antagonist, there is serration on the incisal edge.
• The lingual surface is slightly concave with a distinct tuberculum dentale. Marginal approximal ridges are not very prominent in these teeth .
• The approximal surfaces are triangular in shape and pass at a right angle to the incisal edge.
• The root of the middle lower incisor is straight, conical and flattened on the sides. The root of the lateral lower incisor quite often has a distal inclination. Both have a longitudinal groove on the sides of the root.

Lower canine

Incisor

The lower canine is similar to the upper. However, it is smaller (narrower and slimmer).

This is a 1st class pillar according to Voldřich.

The labial surface has a slightly convex shape. The mesial portion is more arched than the distal.

The lingual surface has a slightly concave shape. It is shorter than the labial surface due to the inclination of the crown of the tooth in the oral direction.

The approximal surfaces are triangular in shape.

The root is shorter compared to the root of the upper canine, has grooves on the sides and is flattened on the sides.

The shape of individual teeth

Table of the number of roots and canals

Tooth	Designation (Two-digit)	Length [mm]		Number of roots (in percent)			Number of channels (in percent)			The root of the south	Crown Height	Mesiodistal crown width	Labiooral crown width
		According to	According to	1	2	3	1	2	3
Middle Incisor	31 / 41	21	21,5	100			60	40		12,5	9,0	5,0	6,0
Lateral Incisor	32 / 42	21	23,5	100			60	40		14,0	9,5	5,5	6,5
Spitz	33 / 43	22,5	26,5	98	2		85	14		15,5	11,0	7,0	7,5

Údaje převzaty ze Základů klinické endodoncie, Peřinka 2009 a z Preklinické stomatologie, I. část – morfologická, Jansová–Eber.

Teeth in the distal section

Upper Jaw (Maxilla)

First upper premolar

First upper premolar

Two cusps – the buccal cusp points distally and is higher and sharper than the palatal cusp. As the only one of all premolars, it has the largest percentage of cases (60%) two roots and 92% two canals. The roots are gracile and twisted - difficult to treat endodontically. Frequent extraction for orthodontic reasons. This is pillar II. class according to Voldřich.

Second upper premolar

It is smaller in volume than the first premolar , to which it is very similar except for a few differences. Unlike the first upper premolar, both cusps are the same height. In 90%, it has only one root, which has a close relationship with the maxillary cavity. Like all premolars, they belong to pillars II. class according to Voldřich.

First upper molar

Molar diagram

The largest of all three molars (crown width 10.5 mm, root length 12.5 mm, tooth length 20.5 mm). It belongs to the first class pillar according to Voldřich.

The buccal surface of the dental crown is trapezoid-shaped, narrower in the area of ​​the neck of the tooth. It is slightly arched, divided by a fissure, which divides the entire surface into two equally large parts of the part - mesial and distal.

The palatal surface is slightly arched, it also has the shape of a trapezoid. The fissure, which divides the two palatal bumps of the masticatory surface, passes into the palatal plane, which it divides into a smaller distal and a larger mesial one.

The approximal surfaces have a square shape. It ends in the enamel wall of the occlusal surface. The mesial surface is higher, flat, slightly concave at the neck of the tooth. The proximal distal surface is lower and shorter.

The occlusal surface has the shape of a rhombus with four bumps, which are separated from each other by three fissures. The interbuccal cusp is the largest together with the mesiopalatine, followed by the distobuccal and the smallest distopalatinal. In approximately 17% of cases, a fifth tubercle, the so-called tuberculum anomale Carabelli, may develop mesio-palatally .

Tuberculum anomale Carabelli

Roots- the upper first molar has three roots, two are placed buccally, one palatally. The palatal root is the largest, straight, conical in shape. It has the shape of a circle in cross-section. Buccal roots are oval in cross-section. The roots of the upper molars often reach the bottom of the maxillary cavity.

The medullary cavity is spacious, narrowing in the landscape of the neck and continues into the roots as root canals. The palatal canal is straight and the widest. Buccals are narrower. Bifurcation may occur in the mesiobuccal canal.

Second upper molar

Its shape is similar to the first upper stool , but it is smaller (crown width 9.5 mm, root length 11.5 mm, tooth length 18.5 mm). It belongs to the first class pillar according to Voldřich.

The occlusal surface usually has a four-cusped shape, it differs from the first upper molar only in size. However, the three-bump form is also often found. Only one palatal cusp is formed on the occlusal surface and it is the largest of all cusp. The palatal surface is very narrow and convex. The distopalatinal tubercle disappears.

There are usually three roots , placed in the same way as for the first upper molar (two buccally, one palatally). However, they live closer to each other. Sometimes they can merge into one root. They are shorter and less curved.

The medullary cavity has a cylindrical shape, mesiodistally flattened.

There are usually three narrow root canals. The interbuccal canal is difficult to access.

Third upper molar

Another name is wisdom tooth ( dens sapientiae ), crown width 8.5 mm, root length 11 mm, tooth length 17.5 mm. It differs from other stools in size. The shape is individually variable. It is often not established at all. The classification of pillar teeth according to Voldřich is individual and depends on the morphology of the particular tooth of the given individual.

The crown can have the shape of a four-cusped or three-cusped tooth, there is also a multi-cusped type.

The roots are also very variable in number, shape and arrangement.

Table of the number of roots and canals

Tooth	Designation (Two-digit)	Length [mm]		Number of roots (in percent)				Number of channels (in percent)			The root of the south	Crown height	Mesiodistal crown width	Labiooral crown width
		According to	According to	1	2	3		1	2	3
First Premolar	14 / 24	21	23	36	60	4		4	92	4	14,5	8,5	7,0	9,0
Second Premolar	15 / 25	21,5	22,5	90	9	1		75	24	1	14,0	8,5	7,0	9,0
First Molar	16 / 26	22	20,5		3	97	MB. k.	26 – 45	55 – 97		12,5	7,5	10,5	11,0
							DB. k.	100
							P. k.	100
Second Molar	17 / 27	21	18,5	1	19	80					11,5	7,0	9,5	11,0
Third Molar	18 / 28		17,5								11,0	6,5	8,5	10,0

Údaje převzaty ze Základů klinické endodoncie, Peřinka 2009 a z Preklinické stomatologie, I. část – morfologická, Jansová–Eber.

Bottom Jaw

Lower first premolar

Lower first premolar

It is the smallest premolar in the oral cavity. We classify it as pillars II. class according to Voldřich.

The cusps are divided by the edge into a shorter, higher mesial part and a longer, higher distal part. The buccal cusp is very sharp and points in a lingual direction. The lingual tubercle, on the other hand, is smaller and considerably lower.

We can find only one root here, oval or circular in shape.

In 75% of cases, there is only one root canal , it has an oval shape.

The pulp cavity is cylindrical and extends into two corners of the pulp - the larger buccal and the smaller lingual.

Second lower premolar

second lower premolar (adult dentition on the left)

It is generally the largest of all premolars. Its chewing surface differs from others in that it can exist in several forms (double-cusped, triple-cusped and multi-cusped). This is pillar II. class according to Voldřich .

First lower molar

Lower left first molar(center)

It is the largest tooth in the lower jaw (crown width 11 mm, root length 14 mm, tooth length 21.5 mm). It is a pillar tooth of Class I according to Voldřich . The first lower molar is mesiodistally elongated, its shape is given by the cusps of the masticatory surface.

Buccal surface of the dental crown

it has the shape of a mesiodistally elongated trapezoid. It is very convex, the central cusp protrudes considerably buccally. The fissure between the mesiobuccal and median cusp is deep to the buccal surface, where it often ends with a blind opening ( foramen caecum ). It separates the mesial and distal part of the buccal surface. It is larger and higher than the lingual surface and is narrowed towards the neck of the tooth.

Lingual surface

it is convex and shorter than the buccal surface.

Mesial approx

the surface is flat. It tends to be higher than the distal surface.

Distal approximal surface

is convex.

Occlusal surface

it has a five-bump arrangement. The mesiodistally running fissure divides the chewing surface into two unequal parts – the lingual part has two bumps, the buccal part has three. The lingual cusps are the same size, unlike the buccal cusps, where the largest is the mesiobuccal cusps.

Roots

there are two and they are placed in the dental arch, one mesially and the other distally. They tend to be massive, mesial is wider, mesiodistally flattened. They are inclined in a distal direction.

Medullary cavity

it has a cylindrical shape. It is extensive. It extends into three root canals.

Second lower molar

Its shape is similar to the first lower stool , but it is smaller (tooth width 10.5 mm, root length 12 mm, tooth length 19 mm). This is a 1st class pillar according to Voldřich.

The buccal surface is usually very arched. A fissure passing from the occlusal surface divides the buccal surface into two approximately equal parts.

The lingual surface is slightly convex. It has a pronounced lingual inclination.

The mesial approximal surface is flat.

The distal proximal surface is convex.

The chewing surface has a four-bump shape. It is divided by a longitudinal groove, with a connecting transverse fissure in the shape of a cross. Of the four cusps formed, two are placed buccally and two lingually.

There are two roots, mesial and distal. They are bent distally in the apical third. The roots can sometimes merge into a single cone that has one or two canals.

The medullary cavity has a cylindrical shape as the first lower molar. It extends occlusally into the four corners of the pulp.

The root canals are one to two in the mesial root and one wide in the distal root.

Third lower molar

Unerupted lower right third molar (OPG image)

Lower wisdom tooth, tooth width 10mm, root length 11mm, tooth length 18mm

The shape of the dental crown, as well as the number, shape and arrangement of the roots, is very individual. The four- to five-bump variant is most common. Variability is also the classification between abutment teeth according to Voldřich .

The shape of the crown can be compared to the crown of the second lower molar.

The roots are stored either separately, or they can be fused together. There are different numbers of them.

Due to the lack of space in the lower jaw, or the inclination of the tooth germ, the eruption of the lower wisdom tooth very often causes problems known as dentitio difficilis.

Table of the number of roots and canals

Tooth	Designation (Two-digit)	Length [mm]		Number of roots (in percent)				Number of channels (in percent)			The root of the south	Crown height	Mesiodistal crown width	Labiooral crown width
		According to	According to	1	2	3		1	2	3
First premolar	34 / 44	21,5	22,5	100				75	23	2	14,0	8,5	7,0	7,5
Second premolar	35 / 45	21,5	22,5	100				89	10	1	14,5	8,0	7,0	8,0
First molar	36 / 46	21	21,5		98	2	M. k.		87	13	14,0	7,5	11,0	10,0
							D. k.	62	38
Second molar	37 / 47	20	19	15	85						12,0	7,0	10,5	10,0
Third molar	38 / 48		18								11,0	7,0	10,0	9,5

Údaje převzaty ze Základů klinické endodoncie, Peřinka 2009 a z Preklinické stomatologie, I. část – morfologická, Jansová–Eber.

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References

• PEŘINKA, Luděk – BARTŮŠKOVÁ, Štěpánka – ZÁHLAVOVÁ, Eva. Základy klinické endodoncie. 2. edition. Art D - Grafický ateliér Černý s. r. o, 2009. 288 pp. ISBN 978-8090-38768-3.

• JANSOVÁ, K – EBER, M. Preklinická stomatologie. 2., dopl edition. Vydavatelství Univerzity Palackého, 1996. 72 pp. pp. 39–55. ISBN 80-7067-596-9.

• ŠEDÝ, Jiří – FOLTÁN, René. Klinická anatomie zubů a čelistí. 1. edition. Triton, 2010. ISBN 978-80-7387-312-7.