Generalities-in-dental-anatomy
Introduction:
Anatomy is a discipline of biology that describes the shape and structure of living organisms and their parts (organs, tissues).
Dental anatomy is therefore the study of the form and structure of the dental organ.
I. Dental basics: Denture and dentition
1. Teething:
It is the set of anatomical and physiological phenomena leading to the establishment of teeth .
This is the dynamic phenomenon from the formation to the eruption (natural emergence) of teeth.
2. The teeth:
This is the static state ( Teeth already in place).
We have 3 sets of teeth
Temporary or milk teeth : Consisting of 20 teeth:
8 Incisors, 4 Canines and 8 Molars
Permanent or definitive teeth : Made up of 32 teeth:
4 Central incisors, 4 Lateral incisors, 4 Canines, 8 Premolars and 12 Molars.
Mixed dentition:
Temporary and permanent teeth will coexist within the dental arches,
This is why this dentition is called “Mixed”.
II. General shape of the teeth:
All teeth are made up of:
From a crown: it is the part of the tooth visible in the mouth, which comes out of the gum.
From one or more roots: this is the part of the tooth that is implanted in the alveolar bone, the end of the root is called Apex.
From a collar: it is the separation between the crown and the root.
III. Terminology in dental anatomy:
1. The tooth:
The tooth also called ” Odont ” is made up from the outside to the inside:
– Enamel: it is a highly mineralized hard tissue that covers the dental crown.
– Dentine: constitutes the major portion of the dental structure, it is covered by enamel at the coronal level and by cementum at the root level.
-Dental pulp: it occupies the central part and represents the living part of the tooth (vascular-nervous bundle).
2. The periodontium:
The tooth is surrounded by supporting elements which constitute the “periodontium”:
The gum
The alveolar bone
The periodontal ligament (desmodontium)
3. The different classes of teeth:
In humans, there are 4 classes of teeth: incisors, canines, premolars and molars.
The incisors:
There are 4 of them per jaw, they have a cutting edge and their function is to cut (incise).
Canines:
They follow the incisors.
There are 2 canines per maxilla.
The canine has 2 cutting edges which meet in a “V” shape, forming the canine tip.
Premolars:
There are 4 of them per jaw.
These teeth are, by definition, the teeth that are in front of the molars.
They have a grinding (occlusal) surface, their function being grinding (mastication).
Molars:
These are the most posterior teeth, there are 6 of them per arch.
They have a larger occlusal surface than the premolars and are also involved in chewing.
IV. Nomenclature of dental faces:
All teeth are made up of 5 faces:
The vestibular face : related to the cheeks, lips, visible face when smiling.
The lingual or palatine surface: related to the tongue (mandible), the palate (upper jaw).
The proximal faces:
The mesial face: this is the face closest to the sagittal plane
median.
The distal face: this is the face furthest from the sagittal plane.
The occlusal face and incisal edge (free edge):
Depending on whether it is the molar PM group or the incisor-canine group, we therefore speak of:
– Free edge for the incisor-canine group due to the thinness of the face.
– And the occlusal face for the premolar-molar group, it is the face which intervenes during chewing.
VI. General characteristics of crowns:
A. The coronary eminences:
A1. The cusps:
These are coronal elevations found on the occlusal surfaces of premolars and molars.
They consist of 2 right and left sides: (mesial and one distal).
Their number varies from 2 to 5 depending on the tooth.
A2. Tubers:
These are coronary elevations of variable shape and volume.
located on dental surfaces other than the occlusal surface.
The lingual surfaces of the incisors and canines have a tubercle
called “Cingulum”.
The lingual surface of the upper 1st molar may have a tubercle called the “Carabelli” tubercle (inconstant element).
The vestibular surface of the same tooth may also have a tubercle called the “Bolk” tubercle.
A 3. Marginal ridges:
These are linear elevations on the occlusal face of the premolars and molars, they limit the occlusal face mesially and distally.
They are also linear elevations on the lingual face of the incisors and canines, they limit the lingual face mesially and distally.
B. Coronary depressions:
B1. The furrows:
These are longitudinal depressions on the surface of the teeth,
They are found on the vestibular, lingual and occlusal surfaces.
The grooves of the occlusal surfaces are of 2 types:
*The main (intercuspid) grooves: these are those which separate the cusps.
*Secondary (accessory) grooves: they are located on the cusps and are less deep than the previous ones.
The main (intercuspal) grooves
B2. Cracks:
These are very deep grooves, they result from a defect in amelogenesis (enamel formation).
B3. The pits:
they characterize the occlusal faces. 2 types of pits:
The central pits which arise from the intersection of 2 furrows.
Marginal pits that arise from the intersection of a main furrow and a marginal ridge.
B4. Dimples:
These are more or less marked depressions on the vestibular and lingual faces of all teeth.
VII. Nomenclature of teeth:
The teeth are numbered from the midsagittal plane from 1 to 8 for the permanent dentition and from 1 to 5 for the temporary dentition.
Palmer’s tooth nomenclature:
Each arcade is divided into 2 hemi-arcades, each hemiarcade is represented by a quadrant:
The right upper hemiarcade
The left upper hemiarcade
The lower right hemiarch
The lower left hemiarcade
Palmer’s tooth nomenclature:
The combination of the tooth code and the hemiarch code allows us to identify the tooth.
Examples:
The upper right central
The 2nd lower left premolar
Nomenclature of teeth according to WHO:
Each arch is divided into 2 quadrants: we thus obtain 4
quadrants:
Quadrant 1: Right maxilla
Quadrant 2: Left maxilla
Quadrant 3: Left mandible
Quadrant 4: Right mandible
Nomenclature of teeth according to WHO:
Nomenclature of teeth according to WHO:
To identify a tooth we start with the quadrant code followed by a dot then the tooth code .
Example: The right upper canine 1.3 (read one three)
The lower left control unit 3.1 (read three one)
FDI International Tooth Nomenclature:
This is the nomenclature currently used; it follows the same principles as the WHO nomenclature without adding a period.
Example: The right upper canine 13 (read: thirteen)
The lower left central 31 (read thirty-one)
Generalities-in-dental-anatomy
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Interdental brushes prevent gum problems.
A diet rich in calcium strengthens teeth and bones.