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Gustafson's Method / Gustafson's Changes in Teeth
Introduction
Gustafson's method (proposed by Gosta Gustafson in 1950, published in J Am Dent Assoc 41:45-54) is an objective, semi-quantitative forensic technique for estimating the age of an adult individual from teeth. It is applicable only in deceased individuals (cadavers/skeletal remains), since the procedure is destructive. It is useful for estimating age between 25 and 60 years, and is not applicable in persons below 15 years (changes are absent at that age).
The method involves microscopic examination of a longitudinal section of a tooth, assessing six progressive age-related changes.
The Six Criteria (Mnemonic: APSRTC)
The six changes are remembered by the mnemonic A P S R T C (like the name of a bus company!):
| Letter | Criterion | What Happens with Age |
|---|
| A | Attrition | Wearing of the occlusal surface |
| P | Periodontosis | Regression of gums/periodontal tissue |
| S | Secondary dentine | Deposition in pulp cavity |
| R | Root resorption | Resorption of root apex |
| T | Transparency of root | Translucency due to rarefaction of dentine |
| C | Cementum apposition | Increased cementum deposition on root surface |
Detailed Description of Each Criterion (Scored 0 to 3)
1. Attrition (A) - Wearing of the Biting Surface
Progressive wearing of the occlusal (mastication) surface due to continuous friction between opposing teeth.
| Grade | Description |
|---|
| A0 | No attrition |
| A1 | Attrition confined to enamel only |
| A2 | Attrition extends into dentine |
| A3 | Attrition exposes the soft pulp |
2. Periodontosis (P) - Gum and Periodontal Regression
Regression of the gums and periodontal tissues surrounding the teeth, with gradual exposure of the root. Poor oral hygiene accelerates this. Hardened debris may also deposit over time.
| Grade | Description |
|---|
| P0 | No periodontosis / no root exposure |
| P1 | Exposure of less than 1/3rd of the root (from crown) |
| P2 | Exposure of more than 1/3rd but less than 2/3rd of root |
| P3 | Periodontosis beyond 2/3rd of the root length near the crown |
Note: The degree of periodontosis must be assessed before the tooth is extracted from the body.
3. Secondary Dentine (S) - Infilling of Pulp Cavity
With advancing age, secondary dentine is deposited within the pulp cavity, gradually reducing its size. In mandibular teeth, it starts from above (pulp chamber); in maxillary teeth, it starts from below. Also caused by pathological conditions (caries, periodontosis).
| Grade | Description |
|---|
| S0 | No secondary dentine deposition |
| S1 | Deposition in the upper part of pulp cavity only |
| S2 | Deposition in the upper half of the pulp cavity |
| S3 | Almost the whole pulp cavity is filled |
4. Root Resorption (R) - Decay of Root Apex
A destructive process involving both cementum and dentine. Characteristically shows sharp grooves. Begins at the apex and extends upward. Usually occurs in late age; may be due to pathological processes.
| Grade | Description |
|---|
| R0 | No root resorption |
| R1 | Resorption seen only in some (small) parts |
| R2 | Seen over a large area |
| R3 | Involves both cementum and dentine extensively |
5. Transparency of Root (T) - Most Reliable Criterion
Not seen until about 30 years of age. Occurs due to rarefaction (osteoporosis/mineralization) of dentinal tubules, which fills the wide canals with minerals, making the dentine translucent.
- In the lower jaw: transparency progresses from below upwards (apex upward)
- In the upper jaw: transparency progresses from above downwards
This is the most reliable of all six criteria for age estimation.
| Grade | Description |
|---|
| T0 | No transparency anywhere |
| T1 | Transparency mostly in the apical region |
| T2 | Transparency up to 1/3rd from the apical region |
| T3 | Transparency up to 2/3rd of root length from apex |
6. Cementum Apposition (C) - Increased Cementum
Cementum deposition increases with age due to changes in tooth position and surface near the root apex. It forms visible incremental lines.
| Grade | Description |
|---|
| C0 | Only the normal layer of cementum is present |
| C1 | Slightly greater than normal |
| C2 | A thick layer has occurred |
| C3 | A very heavy layer is present |
The Gustafson's Method Diagram
Here is the classic diagram showing all four grades (0-3) for each criterion side by side in longitudinal tooth sections:
The four tooth diagrams show progressive grades 0 to 3. A = Attrition, S = Secondary dentine, P = Periodontosis, C = Cementum, T = Transparency, R = Root resorption.
Procedure
- Before extraction: Note and score the degree of periodontosis (P) while the tooth is still in the jaw.
- Extract the tooth from the jaw.
- Gross examination by naked eye: assess attrition, root resorption, cementum apposition.
- Grind down the tooth on a glass slab to about 1 mm thickness - this allows assessment of root transparency.
- Further grind to 0.25 mm (1/4 mm) for microscopic examination of secondary dentine, etc.
Scoring and Age Estimation Formula
Each of the six criteria is graded 0, 1, 2, or 3.
Total Score = An + Pn + Sn + Rn + Tn + Cn
(Maximum possible score = 18; minimum = 0)
The total score is then plotted on a regression graph comparing point values to teeth of accurately known age, with a regression line drawn. Age is read off the graph.
Gustafson's regression equation:
Age (years) = 11.43 + 4.56 × (Total points)
- The error margin is ± 3.5 years (some sources quote ± 4 to 7 years, with the error increasing above 50 years of age).
- Scoring is relative: 0 = no change; 1 = beginning of change; 2 = obvious change; 3 = maximum change.
Important Points to Remember
| Feature | Details |
|---|
| Applicable age range | 25-60 years (adults after dental development is complete) |
| Changes absent below | 15 years of age |
| Most reliable criterion | Transparency of root (T) |
| Best teeth to use | Anterior teeth (incisors > canines > premolars) |
| Worst tooth for this method | Third molar (quite unsuitable) |
| Nature of examination | Destructive - applicable only in dead bodies |
| Error of estimation | ± 3.5 years (increases after age 50) |
| Published by | Gosta Gustafson, 1950 |
Modifications and Related Methods
- Johanson's modification of Gustafson's method is considered more accurate than the original.
- Boyde's method: Uses incremental cross-striations in enamel (daily growth lines counted from the neonatal line) - most accurate for estimating age of dead infants.
- Stack's method: Uses weight and height of erupting teeth to estimate age in infants/children.
- Miles' method (1963): Specifically uses root transparency; the tooth is ground to 1 mm, placed on a dotted paper, and the percentage of visible dots through the transparent root is calculated for age estimation.
Sources:
- The Essentials of Forensic Medicine and Toxicology, 36th Edition (Nagesh Kumar & Siddham), p. 82-83
- P.C. Dikshit Textbook of Forensic Medicine and Toxicology, p. 68-69
- Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology, p. 88
