Gustafson's Formula | Step by Step explanation for determining the age from tooth

Gustafson's formula allows one to estimate the age of a person by examining their dental characteristics such as tooth wear, attrition, and other dental change

FORENSIC SCIENCEFORENSIC ODONTOLOGY

Shubham Kumar

1/29/20247 min read

In victims of mass destruction or any accidental or homicidal, the age of the dead body can be as certain by application of Gustafson's formula, based on the progressive change in their dentine due to continues aging and decaying process. However, this formula is useful only while examining the skeleton or dead body, because the tooth is to be plugged out from the socket and examined under microscope for further knowledge and information.

This blog aims to provide the information regarding Gustafson's Formula and illustration of this formula.

Gustafson's Formula | by Dr. Gustafson in 1950

The phenomenal Swedish dentist and researcher, Dr. F. Gustafson introduced the system in 1950, to estimate the age of any person via examining their dental characteristics. The research and the work of Dr. F. Gustafson hold prominent grounds in expanding the approaches in dentistry, especially in the field of Forensic Odontology and Anthropology. This formula allows one to estimate the age of a person by examining their dental characteristics such as tooth wear, attrition, and other dental changes that occur with aging. Moreover, this method has been an important tool in forensic science for determining the age of individuals based on their dental remains.

The age determination consists of microscope examination of longitudinal section of the central part of the tooth followed by radiological techniques. Gustafson in 1950 studied changes in the physiological & morphological tooth of an individual. He estimated the age of that individual by focusing on 6 landscapes which further became the 6 pillars of Gustafson's Formula.

The Gustafson's Formula focuses on 6 landscapes while examining the dental characteristics, so as to estimate the approx age of a person. These 6 landscapes are

  • An= Attrition

  • Sn= Secondary Dentine

  • Pn= Periodontitis

  • Cn= Cementum Deposition

  • Rn= Root Reabsorption

  • Tn= Transparency of Tooth

Gustafson's Formula:

11.43 + 4.56 (T.S) ± (3.63)
Where T.S= An + Sn + Pn + Cn + Rn + Tn

How to Estimate the Age of Tooth by Gustafson's Formula

Gustafson's Formula focuses on 6 landscapes while examining the dental characteristics of the subject. These 6 landscapes are:

An= Attrition

Sn= Secondary Dentine

Pn= Periodontitis

Cn= Cementum Deposition

Rn= Root Reabsorption

Tn= Transparency of Tooth

Attrition

Attrition is the change occurs due to mastication of surface of teeth of upper and lower gums due to continuous friction. The psychological wear and tear involves changes in structure, durability and morphology of enamel.

In the Gustafson's formula -: 11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

The An represents the degree of attrition on the dentine of the subject. Its value of An ranges from 0 to 3

An = 0 (No Attrition) - There are no signs of decay or significant wear and tear on the enamel.

An = 1 (Primary Attrition) - There is minimal wear and tear on the enamel, with only slight signs of degradation.

An = 2 (Secondary Attrition) - Moderate wear and tear on the enamel, indicating a medium level of degradation.

An = 3 (Last Stage) - The tooth enamel has experienced significant decay and degradation, leading to a substantial loss of durability and stability.

Secondary Dentine

With increasing age, there is a deposition of dentine tissue in the cavity. Majorly this occurs due to age factor, however pathological does play significant role in it. It starts from above in case of mandibular teeth, whereas in maxillary teeth, it starts from below. The secondary dentine is the layer of present in dentine which is produced after the tooth is completely formed. The rate of deposition of this layer depends upon age, however pathological conditions are also one of the causes. Gustafson's Formula examines the amount of deposition in order to estimate the age.

In the Gustafson's formula -:

11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

The Sn represents the degree of deposition of secondary dentine in the dentine of the subject. The value of Sn ranges from 0 to 3

Sn = 0 (No Deposition) - There is no significant deposition of secondary dentine, and the tooth shows no signs of this process.

Sn = 1 (Primary Deposition) - There is minimal deposition of secondary dentine, indicating only slight signs of this process.

Sn = 2 (Intermediate Deposition) - Moderate deposition of secondary dentine is present, indicating a medium level of this process.

Sn = 3 (Advanced Deposition) - The tooth exhibits significant deposition of secondary dentine, signifying an advanced stage of this process.

Periodontitis

Periodontitis is a type of tissue that attach the tooth to the base at the root level. It helps the tooth to withstand biting force through cushion effect. The destruction of periodontitis ligament or tissue is one of the major cause of increasing mobility of tooth.

When the maintenance of the teeth and gums are improper, this may result in lessening of teeth, eruption of gums and deposition of debris along the boundary of gums. The regression of gums and periodontitis tissues surrounding the teeth takes place in advancing stage of age, however eating habits also stands as major cause. Furthermore, leading to exposure of neck and root parts of teeth. Moreover, causing inflammation, bleeding, loosening of teeth and decay of periodontitis ligament. Gustafson's Formula examines the degree of destruction of periodontitis in order to gain valuable insights on eating habits and stage of age.

In the Gustafson's formula -:

11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

The Pn represents the degree of destruction of periodontitis ligament or tissue in the dentine of the subject. The value of Pn ranges from 0 to 3

Pn = 0 (No Destruction) - No destruction of the periodontal ligament is detected.

Pn = 1 (Primary Destruction) - Minor destruction is observed, resulting in an increase in mobility of approximately 1/3 of the tooth (Loosening of teeth).

Pn = 2 (Intermediate Destruction) - Moderate destruction is evident, leading to an increase in mobility of approximately 2/3 of the tooth.

Pn = 3 (Advanced Destruction) - Significant destruction of the periodontal ligament is present, causing increased mobility of more than 2/3 of the tooth.

Cementum Resorption

Cementum is the hard tissue covering the root portion of the dentine. It may contain cells in some areas and may not in others. With advancing age, cementum continuously thickens, primarily near the root area of the tooth. However, an increase in deposition can also occur due to changes in the position of the tooth's root, which is significantly influenced by eating habits and the individual's stage of aging. Cementum continues to be deposited throughout one's life. Gustafson's Formula assesses the amount of cementum deposition to estimate the age of the subject

In the Gustafson's formula -:

11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

The Cn represents the degree of deposition of cementum in the dentine of the subject. The value of Cn ranges from 0 to 3

Cn = 0 (No Deposition) - There is no significant deposition of cementum, and the tooth shows no signs of this process.

Cn = 1 (Primary Deposition) - There is minimal deposition of cementum, indicating only slight signs of this process.

Cn = 2 (Intermediate Deposition) - Moderate deposition of cementum is present, indicating a medium level of this process.

Cn = 3 (Advanced Deposition) - The tooth exhibits significant deposition of cementum, signifying an advanced stage of this process.

Root Reabsorption

The tooth's roots are surrounded by a layer of cementum, and the pulp cavity encompasses the integration of these roots. The roots play a vital role in providing the necessary nutrients and minerals to the tooth. However, as age advances, changes in the roots can occur. This progressive change can result from cementum deposition, enamel decay, or the destruction of the periodontal ligament. The progressive changes in the roots of the tooth are facilitated by the actions of odontoblasts (decay cells) and may lead to the progressive loss of cementum and increased root sensitivity.

In the Gustafson's formula -:

11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

The Rn represents the degree of root reabsorption in the dentine of the subject. The value of Rn ranges from 0 to 3

Rn = 0 (

No Resorption) - There is no significant resorption of root is observed.

Rn = 1 (Primary Resorption) - There is minimal resorption of tooth can be seen.

Rn = 2 (Intermediate Resorption) - Moderate resorption of root is observed.

Rn = 3 (Advanced Resorption) - The tooth exhibits significant resorption of root.

Transparency of Root

The final stage of age estimation using Gustafson's Formula involves examining the transparency of the tooth. With advancing age and due to improper care and uneven eating habits, debris may accumulate within the dentine tubules. This criterion is typically observed after the age of 30.

In the Gustafson's formula -:

11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

The Tn represents the degree of transparency in the dentine of the subject. The value of Tn ranges from 0 to 3

Tn = 0 (No Transparency) - There is no significant transparency of tooth observed.

Tn = 1 (Primary Transparency) - There is minimal or slight transparency is observed.

Tn = 2 (Intermediate Transparency) - Moderate or 1/3 portion of tooth shows transparency

Tn = 3 (Advanced Transparency) - The tooth exhibits significant transparency, showing in more than 2/3 area.

Example of Estimating Age via Gustafson's Formula

Illustration

The 3rd molar of upper left jaw shows root reabsorption and dentine of teeth is so thick that is almost cover the pulp cavity. The crown of the teeth shows slight wear and tear. The canine shows removal of gums and periodontitis membrane. Odontoblast of first pre-molar is absent. Estimate the age?

Answer:

  • An= 1 (slight wear and tear)

  • Sn= 3 (dentine of teeth is so thick that is almost cover the pulp cavity)

  • Pn= 3 (removal of gums and periodontitis membrane.)

  • Cn= 0

  • Rn= 1 (3rd molar of upper left jaw shows root reabsorption)

  • Tn= 3 (almost cover the pulp cavity)

Gustafson's formula -: 11.43 + 4.56 (T.S) ± (3.63)

T.S= An + Sn + Pn + Cn + Rn + Tn

11.43 + 4.56 (T.S) ± (3.63)
11.43 + 4.56 (1+3+3+0+1+3) ± (3.63)
11.43 + 4.56 (12) ± (3.63)
11.43 + 54.72 ± (3.63)
66.15 ± (3.63)

66.15 + 3.63 and 66.15-3.63
69.78 and 62.52


Therefore the estimated age of the subject is between 62.52 years to 69.78 years

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