Morphology of tooth | Temporary and Permanent Tooth | Incisors, Canines, Pre-Molars and Molars

Morphology of tooth refers to the study of physical structure, types, classification, characteristics and anatomy of tooth. Tooth morphology is essential for

FORENSIC ODONTOLOGY FORENSIC SCIENCE

Shubham Kumar

1/29/20245 min read

Morphology of tooth refers to the study of physical structure, types, classification, characteristics and anatomy of tooth. Tooth morphology is essential for understanding how teeth function and for dental diagnosis and treatment.

Teeth are arranged in two sets, one on the top (maxillary) and one on the bottom (mandibular). You can split each set-in half down the middle. Teeth fit into sockets in the jawbone and are held in place by a ligament called the periodontal ligament.

This informative blog includes the information required to understand the "Information related to classification, morphology of tooth and anatomy of tooth.". Please read it with patiently.

Temporary and Permanent Dentine | Morphology

Temporary dentine, also known as primary or baby dentine, is a crucial component of the human tooth that plays a vital role during the early stages of tooth development. This dentition has a total of 20 primary teeth, also known as baby teeth. These teeth start to erupt around the age of 6 months and continue until the child is about 2 to 3 years old. The eruption of these teeth is a natural part of tooth development. However, the process of tooth development begins long before we are born. Temporary dentine is the first type of dentine formed during this process.

Permanent dentine, also known as secondary or adult dentin, it is a crucial component of the adult tooth system and plays a significant role in one's survival. Permanent dentine evolves from the temporary dentine. Therefore, it contains 32 teeth in total.

Anatomy of Tooth | Tooth Structure | Morphology

A tooth can be categorized into two primary sections: the crown and the root. The crown, which is the visible portion within the mouth, and the root, which is the concealed part by definition. The visible portion in the mouth is referred as clinical mouth whereas, the part which is not visible is called clinical root.

The structure of the tooth is classified as

  • Crown: the part of the tooth visible in the mouth.

  • Neck: the constricted area of the crown and tooth.

  • Enamel: the outer part of the crown, the hardest tissue in our body. It helps in chewing and grinding.

  • Dentine: below the enamel, it consists of organic components made up of tubules and is covered by enamel in the crown portion and cementum in the root portion. However, any exposed part of the tooth can cause sensitivity due to enamel or cementum decay.

  • Cementum: the hard tissue covering the root portion of the dentine. It may contain cells in some areas and may not in others.

  • Pulp chamber: the innermost portion of the tooth that contains nerves and blood vessels. It provides nourishment and helps in dentine formation. It can cause severe pain and infection and may require root canal treatment.

  • Alveolar bone: part of the mandible and maxillae that surrounds and supports the tooth and gums. The soft tissue covering around the teeth covers the alveolar bone. Infection at the gum level may cause bleeding, swelling, pus, and discharge due to the deposit of calculus, plaque, or improper brushing techniques.

  • Periodontal ligament: tissue ligaments that attach the tooth to the base at the root level. It helps the tooth withstand biting force through a

Note:

Dentin is a crucial layer beneath the tooth's outer coverings (enamel and cementum), found throughout the tooth's visible and hidden parts. It's a vital, sensitive tissue that makes up most of the hard structure of a tooth.

Where dentin meets enamel, it's called the Dentino-enamel junction (DEJ). The place where the crown and root meet, where enamel meets cementum, is known as the Cemento-enamel junction (CEJ).

Inside the root of a tooth, there's a space called the pulp cavity. It's filled with the dental pulp, a pink tissue with nerves and blood vessels. At the very tip of the root is the apex. The apical foramen is a small opening at the apex that lets blood vessels and nerves reach the dental pulp and can also be a pathway for pulp infections to spread to the surrounding tissues.

Classifying the types of Teeth | Morphology

There are four main types of teeth – incisors, canines, premolars, and molars. The premolars are only present in the permanent dentition.

Incisors

Incisors are the teeth used for cutting. There are 8 incisors in both the primary and permanent dentine: 4 maxillary and 4 mandibular. Both the maxilla and mandible have 2 frontal incisors called central incisors and 2 more incisors along the sides of central incisors called lateral incisors. Incisors have a slightly constrained neck and a single root.

Temporary Dentine has 8 incisors. Four on maxilla and four on mandible. Permanent Dentine has 8 incisors. Four on maxilla and four on mandible.

Incisor teeth, especially in the upper jaw, can easily get injured in accidents because they're not well-protected and because of their size and shape. These kinds of injuries happen a lot to kids; at least 1 in 10 children get affected. When these accidents happen, they can cause big problems for the way their teeth work, how they look, how they feel about going to the dentist, and their overall quality of life. This affects not just the kids but also the people taking care of them.

Canines

Canines are sharp teeth specialized for cutting and tearing flesh. They are placed next to the lateral incisors in both the maxilla and mandible jaw. Moreover, they have a sharp edge and a thin neck, a prime reason for their deep penetration and hard tearing of food and flesh we eat.

Permanent Dentine has 4 canines. Four on maxilla and four on mandible. Temporary Dentine has 4 canines. two on maxilla and two on mandible.

Canines have strong, long roots that can handle more pressure compared to incisors. When teenagers have too many teeth and not enough space for them to come in properly (dental crowding), their canines might not come out as they should. In X-rays, these unerupted canines are often found either up in the roof of the mouth or high up in the outer part of the gums. Sometimes, oral surgery is needed to help these teeth come out the right way.

Premolars

Premolars are teeth with 2 cups on their heads, usually called as cuspids. However, they are not found in temporary dentine but present in permanent dentine and are present after the canines. Furthermore, are smaller and shorter in size than the canines.

Temporary Dentine has 0 premolars. On the other hand, Permanent Dentine has 8 premolars. Four on maxilla and Four on mandible.

Premolar teeth sit between the canines and molars and have features of both. In baby teeth, there are no premolars. Dentists often remove premolar teeth to make more room in the mouth, especially before getting braces to fix crooked teeth.

Molars

Molars are the biggest and largest among all the teeth in dentine. They have three to five cups on their heads usually called as tri-cuspids. In temporary dentine, molars are present behind the canines, but in permanent dentine, molars are present behind the 2nd premolars.

Temporary Dentine has 8 Molars. Four on maxilla and Four on mandible. Permanent Dentine has 12 molars. six on maxilla and sex on mandible.

Molar teeth are prone to tooth decay because they have deep grooves on the top surface and a wide area where they touch neighboring molars. These spots are harder to clean compared to the flat surfaces on the front, back, tongue, and roof of the mouth.

This blog has achieved its aim to provide you valuable insights about the morphology of tooth.

Reference

  • "Forensic DNA Typing" by John M. Butler

  • "The Forensic Casebook: The Science of Crime Scene Investigation" by Ngaire E. Genge

  • "Forensic Science: A Very Short Introduction" by Jim Fraser

  • "Practical Crime Scene Processing and Investigation" by Ross M. Gardner