🌟 BASICS OF DENTAL ANTOMY
📌 TOOTH : Teeth are mineralized structures except for the pulp and are located in first part of the digestive tract.
A tooth is defined as “one of the hard tissues that are positioned on the jaws and help in holding and mastication of food, also as weapons of offense and defense in lower animals”.
💡DENTITION :
🔺All of the teeth in the mouth together are referred to as the dentition.
🔺Humans have two dentitions throughout life:
📌 Primary dentition – Dentition During childhood
🔹Synonyms of deciduous teeth are primary teeth, milk teeth, baby teeth or temporary teeth or lacteal teeth or juvenile teeth.
🔹There are a total of 20 primary teeth (8 incisors, 4 cuspids and 8 molars).
🔹Incisors – First tooth to erupt usually between 6–9 months.
🔹Last teeth usually erupt in by 24 months. These are present till the permanent are erupted, i.e. 6 years
📌 Transition or mixed dentition period
🔹Mixture of deciduous and succedaneous teeth present
🔹It lasts from about 6 to 12 years of age
🔹Ends when all the deciduous teeth have been shed.
📌 Secondary Dentition – lasts throughout adulthood
🔹Synonyms of permanent teeth are secondary, permanent or succedaneous teeth.
🔹There are a total of 32 secondary teeth (8 incisors, 4 cuspids, 8 premolars and 12 molars).
🔹First Molar – First secondary tooth to erupt in the oral cavity usually erupts around 6 years of age.
💡NOMENCLATURE :
🔺Teeth in the upper jawbones (called the maxillae) collectively form an arch shape known as the maxillary arch,
🔺Teeth in the lower jawbone (called the mandible) collectively form the mandibular arch.
🔺Each arch can further be divided into the Left and Right halves (also known as left and right quadrants since each quadrant contains one fourth of all teeth in that dentition).
🔸The Letters used in this Formula are based on the 4 types of Teeth like : I – Incisors, C – Canine P – Premolar and M – Molar
💡The Dental Formula Is Expressed As:
(The number of each type of teeth in the upper jaw) / (The number of teeth on one side of the lower jaw)
✴️The Primary Dentition (20 teeth): I2/2 C1/1 M2/2 = 10
✴️The Permanent Dentition (32 teeth): I2/2C1/1 P2/2 M 3/3 = 16
💡The Types or Different classes of teeth are as follows:
🔺Incisors:
🔹Used to incise or cut food,
🔹Located in the front part of the mouth and have sharp, thin edges for cutting
🔺Cuspids:
🔹Designed for cutting and tearing
🔹Also referred to as canines, are at the angles of the mouth.
🔹Has a single cusp instead of an incisal edge
🔺Bicuspids:
🔹Designed for cutting and tearing, and an occlusal surface that is wider to crush the food
🔹Also referred to as premolars
🔹Have two cusps
🔺Molars:
🔹Designed for grinding and chewing solid masses of food
🔹Located in the back part of the mouth.
🔹Size gradually becomes smaller from the first to third molar.
🔹Each molar has four or five cusps; these teeth are shorter and more blunt in shape than other teeth and provide a broad surface
💡EVOLUTION OF TEETH
📌 Homodont :
🔹Means ‘same teeth’.
🔹Which refers animals having one/single type of dentition where in all are similar in shape, indicative of a uniform diet.
▪️ Example: Fishes, amphibians, and most reptiles.
Crocodile has cone shaped teeth as also whales and dolphins
📌 Hetrodont :
🔹Means‘different teeth’,
🔹Which refers to animals having more than a single type tooth morphology and are of different sizes and shapes, specialized for different tasks.
▪️ Example: Man has different types of teeth
📌 Monophyodont :
🔹Dentition in which the species has only one set of teeth, which are functional through out the life.
▪️ Example: Reptiles
📌 Diphyodont :
🔹Dentition in which the species have two sets of teeth, one set (called ‘deciduous’) being shed and replaced by a permanent set of teeth, which are functional throughout the life.
▪️ Example: Cats, dogs, and humans
📌 Polyphyodont :
🔹Dentition in which the species has many sets of teeth, which get replaced and remain functional throughout the life.
▪️ Example: Seen in lower vertebrates, mainly fishes.
📣 Test Your Knowledge :
1. How many teeth are present in one quadrant of a complete adult (permanent) dentition?
a. 5
b. 8
c. 10
d. 20
e. 32
2. What class of teeth is present in the permanent dentition that is NOT present in the primary dentition?
a. Incisors
b. Canines
c. Premolars
d. Molars
3. In a permanent dentition, the fifth tooth from the midline is a
a. Canine
b. Premolar
c. Molar
d. Incisor
4. Posterior teeth in the permanent dentition include which of the following?
a. Premolars only
b. Molars only
c. Premolars and molars only
d. Canines, premolars, and molars
5. Which permanent tooth erupts into the space previously held by the primary second molar?
a. First molar
b. Second molar
c. First premolar
d. Second premolar
💠Answer Key :
1—b, 2—c, 3—b, 4—c, 5—d