Types of Dentition
There are three main types of dentition in humans:
- Primary Dentition
Primary dentition, also known as baby teeth or deciduous teeth, is the first set of teeth that develop in the mouth. These teeth start to appear at around six months of age and continue to erupt until the child is around two or three years old. Primary dentition consists of 20 teeth in total, 10 in the upper jaw and 10 in the lower jaw. The primary teeth are eventually replaced by permanent teeth, which start to erupt at around six years of age.
- Permanent Dentition
Permanent dentition is the set of teeth that replaces the primary teeth. It consists of 32 teeth in total, 16 in the upper jaw and 16 in the lower jaw. Permanent dentition starts to erupt at around six years of age and continues until the late teenage years or early adulthood. The permanent teeth are divided into four types: incisors, canines, premolars, and molars.
- Mixed Dentition
The mixed dentition phase occurs when both primary and permanent teeth are present in the mouth. This typically starts around six years of age and lasts until all the primary teeth have been replaced by permanent teeth. During this phase, the child may experience some discomfort as the permanent teeth erupt, but this is normal.
Functions of Dentition
The primary function of dentition is to break down food into smaller pieces, which can be easily digested by the stomach and intestines. Teeth are also essential for speech, as they help to form certain sounds and words. In addition, teeth play a role in maintaining facial aesthetics, as they support the lips and cheeks and give shape to the face.
Maintaining Healthy Teeth
Maintaining healthy teeth is essential for good oral health, and there are several things that you can do to keep your teeth in good condition:
- Brushing and Flossing
Brushing your teeth twice a day and flossing at least once a day is essential for removing plaque and food particles from your teeth. Plaque is a sticky film of bacteria that can cause tooth decay and gum disease if not removed.
- Regular Dental Checkups
Regular dental checkups are important for detecting dental problems early and preventing them from getting worse. Your dentist can also provide advice on how to maintain good oral hygiene and recommend treatments if necessary.
- Eating a Healthy Diet
Eating a healthy diet that is rich in vitamins and minerals is essential for maintaining healthy teeth. Foods that are high in sugar and starch can contribute to tooth decay, so it is important to limit your intake of these foods.
- Avoiding Tobacco Products
Using tobacco products, such as cigarettes and chewing tobacco, can increase the risk of gum disease and oral cancer. Quitting tobacco use can help to improve your oral health and overall health.
Dentition is an important aspect of oral health, and understanding the different types of dentition and their functions can help you to maintain healthy teeth. By brushing and flossing regularly, scheduling regular dental checkups, eating a healthy diet, and avoiding tobacco products, you can keep your teeth and gums in good condition and prevent dental problems from developing.
TYPES OF DENTITION
There are two major types of dentition. They are
1. Homodont dentition and
2. Heterodont dentition
i. Homodont dentition: in this type of dentition, the organism possesses or has the same types or sets of teeth. In this type of dentition, there is no specialized sets of teeth for a particular type of function. All the teeth of a typical homodont dentition are of the same sizes, shapes and functions. Typical examples of homodont dentition is found in reptiles, amphibians and fishes
ii. Heterodont dentition: in this type of dentition, the organism has teeth of different sizes, shapes and functions. Examples of organisms having the heterodont dentition are mammals like rabbits, man, dogs, lions, cattle and pigs.
Mammals generally have four types or set of teeth. These are
i. Incisors
ii. Canines,
iii. Premolars and
iv. Molars
The type of teeth possessed by an animal depends on the types food it eats.
Mammals have two sets of teeth, they are milk teeth and permanent teeth.
WEED AND THEIR BOTANICAL NAMES
1. ENVIRONMENTAL FACTORS AFFECTING AGRICULTURAL PRODUCTION
2. DISEASES
3. 52. SOIL MICRO-ORGANISMS
4. ORGANIC MANURING
5. FARM YARD MANURE
6. HUMUS
7. COMPOST
8. CROP ROTATION
9. GRAZING AND OVERGRAZING10. IRRIGATION AND DRAINAGE
11. IRRIGATION SYSTEMS
12. ORGANIC MANURING
13. FARM YARD MANURE
14. HUMUS
15. COMPOST
16. CROP ROTATION
1. Milk teeth:
this is the set of teeth possessed by young ones that in the case of humans, the children. It is made up of incisors, canines and premolars and the molars are absent. It is common in children and infants and numbers around 20. It will later fall off to be replaced by permanent teeth.
Permanent teeth:
These are the sets of teeth possessed by adults and are usually four groups consisting of the incisors, canines, premolars and molars. The permanent teeth stay till old age and may number up to 32 for a full-grown adult human
TYPES OF TEETH
There are four types of teeth in mammals. These are incisors, canines, premolars and molars.
i. Incisors: these are located in the front of the jaw. They are flat, chisel-shaped and have sharp edges used in cutting and holding onto the prey so that they cannot escape.
ii. Canines: these sets of teeth are found next to the incisors. They are sharp and pointed at the tips. Canines are used for tearing flesh and bones in the case of carnivores
iii. Premolars: premolars are located at the back of the jaw following the canines. They have flat ridged surfaces or cusps used for grinding and chewing foods
iv. Molars: molars are located at the extreme back of the jaws. They are closely packed with ridged surfaces. They are used for chewing and grinding food
The structure of a tooth
A typical tooth such as the canine or incisor is made up of three parts or regions which are the crown, the neck and the root
1. The Crown: the crown is the parts of the tooth above the gum
2. The Root: the root is part of the tooth that is embedded in the socket of the gum
3. The Neck: This is the narrow junction between the crown and the root
Incisors and canines have one root each while the premolars and molars have two or three roots each
Starting with the external parts, the tooth consists of enamel which is manufactured by special cells of the gum. Enamel is a very hard, non-living substance containing calcium salts. The enamel protects the dentine and pulp cavity and forms an efficient hard-biting surface.
Below the enamel, the dentine is located. The dentine is a bony-like material which contains the pulp cells thereby making it alive.
At the centre of the tooth is the pulp cavity which is made of connective tissues, sensory nerves and blood capillaries.
The blood capillaries of the pulp are important in the transportation of oxygen and digested food substances. Due to the presence of sensory nerve endings, the tooth is able to respond to heat, cold and pain.
At the root region, the tooth is not covered by enamel but by a bone-like material called cement.
The tooth is embedded in the jaw bone of the maxilla (upper jaw) and the mandible (lower jaw). A fibrous tissue called periodontal membrane fixes the tooth into the jaw bone.
DENTAL FORMULA
Meaning of dental formula
What is the dental formula?
The dental formula refers to the numbers and types of teeth present in the mouth of an animal. The number and type of teeth present in the mouth of a mammal or animal is a reflection of the special adaptation of mammalian teeth for feeding.
The adaptation of mammalian teeth for feeding
Incisors
– The four front teeth in both the upper and lower jaws are called incisors. Their primary function is to cut food. The two incisors on either side of the midline are known as central incisors. The two adjacent teeth to the central incisors are known as the lateral incisors. Incisors have a single root and a sharp incised edge.
Canines
– There are four canines in the oral cavity. Two in the maxillary arch and two in the mandibular area. They are behind and adjacent to the lateral incisors. Their main function is to tear food. They have a single, pointed cusp and a single root. They have the longest root of any tooth. They also serve to form the corners of the mouth
Premolars (Bicuspids)
– These teeth are located behind and adjacent to the canines and are designed to crush food. There are eight premolars in the oral cavity. There are two in each quadrant of the mouth. The one closest to the midline is the first premolar and the one farthest from the midline is the second premolar. These teeth can have 3-4 cusps. The maxillary first premolar has two roots, and the remaining premolars have a single root. There are no premolars in the primary dentition.
Molars
– The most posterior teeth in the mouth are the molars. They have broader and flatter surfaces with 4-5 cusps. They are designed to grind food. Molars typically have two roots, although the maxillary first molar (behind the second premolar) has three roots. There are 12 molars in the permanent dentition with three in each quadrant of the mouth. They are named starting with the closest to the midline as the first molars, second molars and third molars. Although, some people do not fully develop the third molars. Third molars are often referred to as wisdom teeth. The primary dentition only contains eight molars.
The human teeth
The dental formula of man is as follows
I= ,c= ,p= ,m= total=32
Man is an omnivore, i.e. it feeds on both flesh and vegetables and the total number of teeth in the mouth is 32, which is also adapted to its type of diet.
i. Incisors: incisors are broad and sharp for cutting food
ii. Canines: canines are bluntly pointed and are used for gripping and tearing food
iii. Premolars: premolars and molars have strong cusps for chewing and grinding of food
The teeth of dogs
I= ,c= ,p= ,m= total=42
The dog is a carnivorous animal, which means it feeds on flesh hence it has 42 in number and is adapted to the kind of food it eats. So here is the arrangement of the teeth in the mouth of a dog
i. INCISORS: the incisors of carnivores are very small and pointed. They are mainly used for cutting and tearing off flesh from bones.
ii. Canines: the canines of a typical carnivore are long, a little curved, large and pointed. The canine is used for attack and defence as well as for seizing prey and tearing off flesh from the bones
iii. Premolars: premolars and molars are broad and thick. The last premolar in the upper jaw and the first molar in the lower jaw is large and modified to form CARNASSIAL TEETH. They possess sharp cutting edges which are used to cut up meat and tear it away from bones. They are also used for cracking bones. Premolars and molars are cusped, blunt with flat surfaces used mainly for cutting and grinding
the teeth formula of Rabbit
The dental formula of rabbits is
I= ,c= ,p= ,m= total=28
The rabbit is a herbivorous animal, that is to say, it feeds on vegetables mainly hence its teeth are 28 in number, and are adapted for the kind of food it eats.
i. The incisors of a rabbit are flat with sharp cutting edges for cutting vegetables or grasses.
ii. canines are practically absent in rabbits. So the space created by the absence of canines in rabbits is called DIASTEMA. The DIASTEMA allows the manipulation of grasses in the mouth.
iii. The premolars and molars of the rabbit are large, closely packed and have large ridge surface area cutting and grinding of food
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