Dental Anatomy: Dentition

Introduction to Dental Anatomy

• Dental anatomy is the study of the development, morphology, function, and identity of teeth.
• It examines the shape, structure, and color of teeth, as well as their functions in chewing and speaking.
• Dental anatomy studies how teeth relate in shape, form, structure, and color.
• It assesses the function of teeth to other teeth in the same arch, and to teeth in the opposing arch.

Formation of the Dentitions

• There are two types of dentitions:
• Primary or deciduous dentition.
• Permanent or succedaneous dentition.

Primary or Deciduous Dentition

• These are the "baby teeth."
• There are twenty primary teeth that progressively appear between 6 and 24 months.
• They consist of four incisors and two canines and eight molars.
• The first teeth erupt in the oral cavity.
• There are twenty teeth in total, with ten in each jaw.
• The teeth begin to emerge into the oral cavity at about 6 months.
• A child typically has a complete set of primary teeth by 2.5 to 3 years old.
• A primary teeth quadrant will have 5 teeth, there is teeth in one arch and total teeth in the mouth
• Humans have two sets of teeth in their lifetime, making them diphyodont.

Permanent Dentition

• Eruption of permanent teeth typically starts around 6 years of age.
• A complete adult mouth has 32 permanent teeth, with 16 in each arch.
• The maxillary (upper) and mandibular (lower) arches each have six anterior teeth.
• These arches include four incisors, two canines, and ten posterior teeth, made up of four premolars and six molars.
• Permanent teeth begin to emerge at 6 years.
• The eruption process is completed by 12 to 13 years, with the exception of the four 3rd molars.
• The third molars erupt around 18 to 25 years of age.
• The number of teeth per quadrant is 8.
• The number of teeth in one arch is 16.
• The number of teeth in the whole mouth is 32.
• In each quadrant, 8 teeth are found.
• The transition or mixed dentition period is where there is a mix of deciduous and succedaneous teeth.
• Transition begins with the emergence of permanent teeth at 6 years
• It ends when all the deciduous teeth have been shed.
• Succedaneous teeth replace primary teeth and include permanent incisors, canines, and premolars.
• Non-succedaneous teeth do not precede primary teeth, such as permanent molars.

Tooth types

• Homodent: All teeth have the same shape and size.
• Heterodont: Teeth have different shapes and sizes.
• Polyphyodont: Teeth are continuously replaced throughout life.
• Diphyodont: There are two sets of teeth.

Types of Permanent Teeth

• Central Incisors
• Lateral Incisors
• Canine - cuspid
• 1st premolar - bicuspid
• 2nd premolar - bicuspid
• 1st molar
• 2nd molar
• 3rd molar – wisdom tooth

Nomenclature

• Nomenclature, or the system of names, is the first step in understanding dental anatomy.
• Mandibular refers to the lower jaw, or mandible.
• Maxillary refers to the upper jaw, or maxilla.
• The maxilla is the upper jawbone.
• It supports the upper teeth, and forms part of the eye sockets and nasal cavity.
• The mandible is the largest and strongest bone in the face
• It forms the lower part of the jaw and is the only moveable bone of the skull.

Oral Cavity

• The oral cavity is defined as the mouth.
• It is an oval-shaped opening in the skull, starting at the lips and ending at the throat.
• The oral cavity is important for bodily functions, including breathing, speaking, and digesting food.
• It includes the lips, lining inside the cheeks, tongue, upper and lower teeth and gums.
• The oral cavity also includes the floor and bony roof of the mouth.

Arches and Quadrants

• The teeth are arranged in two arches, with one in each jaw: the upper (maxillary) arch and the lower (mandibular) arch.
• The maxillary teeth are in the upper jaw, or maxilla.
• The mandibular teeth are in the lower jaw, or mandible.
• The mandible is the movable member of the two jaws, while the maxilla is stationary.
• The midline (median plane) is the imaginary vertical line dividing each arch into two equal halves. The two sections are quadrants.
• The arrangement in the dental arches are two
• They are Upper (Maxillary Arch) and Lower (Mandibular Arch).
• There are four quadrants in the mouth: two in each arch.
• The quadrants are described as maxillary right, maxillary left, mandibular right, and mandibular left. Teeth are divided by an imaginary median line.

Functions of Teeth

• Incisors help cut food.
• Canines allow tearing and grasping of food.
• Premolars help in crushing and tearing food.
• Molars help in chewing and grinding food.