person with dental cheek retractor

TEETH & DENTAL ANOMALIES

Forensic Odontology

Forensic odontology is a branch of dentistry that focuses on identifying the remains of people who have died. This is generally a single victim, but in mass catastrophe scenarios, comparisons between post-mortem results and ante mortem dental records have been found to be the most reliable way of identification. Forensic odontology contributes to the identification process by bringing knowledge of orofacial features, their variance among persons of different ancestries, and the consequences of dental treatment.

Forensic odontologists are highly trained dentists with extensive skill in identifying unknown remains and tracing bite marks back to a specific person. Police officers, the medical examiner, or the coroner may request the services of a forensic odontologist. The forensic odontologist attends the autopsy in death cases and collects pictures, cranial measurements, dental imprints, and x-rays of the body. These samples are then matched to those of people who are known to be missing. The remains can be identified if a match can be found. When bite marks are detected on a victim’s or suspected perpetrator’s body, or on food, chewing gum, or another item, a forensic odontologist uses the same approach to try to determine or rule out probable bite origins.

Forensic odontologists, often known as forensic dentists, are frequently called in to:

  • Identify human remains that aren’t identifiable by facial recognition, fingerprints, or other methods.
  • Identify bodies in large-scale tragedies like airline crashes and natural disasters.
  • In situations of assault or suspected abuse, determine the source of bite mark injuries.
  • Estimation of how old the skeletal remains are.

INTRODUCTION TO DENTITION PATTERN

The mature human dentition is made up of 32 teeth that are arranged into two arches: the maxillary jaw and the mandibular jaw. Due to the symmetry of the arches, each quadrant of the jaw has the same number and kind of teeth: 2 incisors, 1 canine, 2 premolars, and 3 molars. Incisors are large, forward-facing teeth with smooth, tiny biting edges. The canine, often known as the “eye tooth,” is located near the arch’s edge and possesses a piercing cusp. Each premolar has two cusps in most cases. To chew and break food, the molars contain 3 to 5 cusps and a broad biting surface. The wisdom tooth, often known as the third molar, is the final tooth in the arch. A crown and a root are both present on each tooth. The crown is the visible part of the tooth that sticks out above the gum line. The root of the tooth is encased in a socket in the jaw. Canines and incisors both have a single root. Premolars generally have one or two roots, whereas molars usually have two or three roots. Enamel, the human body’s toughest tissue, covers the crown of the tooth.

DIFFERENT TYPES OF TEETH

Temporary and permanent dentition are the two forms of dentition. Temporary dentition has Incisors, Canines, Premolars, and Molars but no Premolars. Permanent dentition has Incisors, Canines, Premolars, and molars.

  1. Permanent Maxillary Central Incisor
  2. Permanent Mandibular Central Incisor
  3. Permanent Maxillary Lateral Incisor
  4. Permanent Mandibular Lateral Incisor
  5. Permanent Maxillary Canine
  6. Permanent Mandibular Canine
  7. Permanent Maxillary First Premolar
  8. Permanent Mandibular First Premolar
  9. Permanent Maxillary Second Premolar
  10. Permanent Mandibular Second Premolar
  11. Permanent Maxillary First Molar
  12. Permanent Mandibular First Molar
  13. Permanent Maxillary Second Molar
  14. Permanent Mandibular Second Molar
  15. Permanent Maxillary Third Molar
  16. Permanent Mandibular Third Molar

Dental Anomalies

Dental anomalies are described as “abnormalities” in the shape, function, or location of teeth and the structures that support them. There are also some common identifying features of teeth that pertains to:

  • Faulty alignment: The problem with the alignment might be in the space between the teeth, such as widely separated teeth or overriding teeth, or between the upper and lower jaw teeth. Overbite is a bite pattern that occurs when the top incisor protrudes, causing the bottom incisor to overlap. Cross-bite refers to the opposite pattern.
  • Faulty development: As a result of improper development and malformation, teeth may be undersized, enlarged, notched, or have some other abnormality. Hutchinson’s teeth are a well-known example of incisor deformity in congenital syphilis. The most noticeable alterations are in the central incisors, which are often tiny, widely spaced, notched, and narrower at the cutting edge than at the gum line, giving them the appearance of a screw driver tip.
  • Stains: The habit of chewing pan (betel leaf, tobacco) leaves a dark, brown, or black coating on the teeth. Cigarette smokers often have yellowish or dark brown stains on the back of their incisor teeth. Fluorosis causes regions of discolouration, striations, and mottling on enamel that are chalky white or yellowish brown (excessive fluoride intake). Metal poisoning can produce gum coloration, which might indicate death. Copper creates a green stain on the gums, whereas mercury and lead cause a blue-black stain.
  • Missing teeth: Teeth detach from their bone sockets and are discovered in the surrounding soil in decomposing corpses or skeletal remains. Displaced teeth should be labelled and kept.
  • Localized attrition: Due to the location of the pipe, a pipe smoker’s teeth may have localised wear, either on the incisors or at the angles of the mouth.

Forensic odontology and anthropology both help human identification. There are numerous different types of anomalies that are categorised based on their size, number, form, and structure which include:

Dental Anomalies based on Size:

  • Micro-dontia: It is a condition in which a single tooth seems to be smaller than normal tooth size outside the range of variation. Micro-dontia is further categorised into three kinds:
Dental Anomalies and Their Significance, Pathshala
  1. True generalised: This is a rare condition in which all the teeth are abnormally small. This can be a result of dwarfism, down syndrome etc.
  2. Relatively generalised: Within the range of tooth size, teeth are normal or slightly smaller than normal, but the jaw size is somewhat bigger than usual, creating the impression of micro-dontia.
  3. Localized micro-dontia: This condition involves only a single tooth. The maxillary lateral incisor and third molar are the most often affected teeth. Only one or two teeth are small in localized micro-dontia.
  • Macro-dontia: It is a condition in which teeth are significantly bigger than normal, beyond the typical range of variation.
Dental Anomalies and Their Significance, Pathshala
  1. True generalized macro-dontia: This is a condition in which a person’s jaw is normal in size but all of their teeth are unusually big. It is a very rare condition that can occur in people who have pituitary gigantism, or an excess of growth hormones.
  2. Relative generalized macro-dontia: This is a condition in which the teeth are normal in size but the jaws are tiny, causing the teeth to be bigger in contrast. This is owing to the outcome of each parent’s inheritance, where the size of the teeth can be inherited from one parent while the size of the jaw can be inherited from another.

Dental Anomalies based on Shape:

  • Fusion: The fusion is caused by the joining of two distinct teeth; it is a form abnormality in which the tooth count is normal. Depending on the stage of development, the fusion might be full (one root or crown fused) or incomplete (root separate crown fused).
  • Germination: It’s a dental condition in which two teeth seem as though they grew from one, with just one root.
Quintessence jounrals
  • Concrescence: Cementum covers the roots of at least two teeth and joins them together in this condition. It is a developmental anomaly which is related to dental hard tissues.
Diagram showing the concrescence condition or shape of the teeth
Dental Anomalies and Their Significance, Pathshala
  • Dilacerations: It is a shape anomaly in which the tooth shape and structure are altered in an angular manner, resulting in a sharp bend in the tooth, which can occur in either the crown or root part. It is not present in completely grown teeth, and it is mostly caused by any type of damage or trauma during the eruption stage.
  • Talon cusp: It is the anolmous protrusion that extends from the lingual/facial surface of teeth, similar to an eagle’s talon.
BMJ Journals, Type I talon cusp on mandibular incisor, https://casereports.bmj.com/content/2017/bcr-2017-220736
  • Dens evaginatus: It is a developmental abnormality of a tooth that appears as an additional bump or cusp on the tooth’s surface, mainly on the premolars.
Dental Anomalies and Their Significance, Pathshala
  • Peg laterals: It’s a condition caused by the lateral incisor’s small size and unusual form. The roots are shorter than typical, and the mesial and distal surfaces converge to the top, producing a cone-shaped crown.
  • Shovel Incisor: Due to enamel deposition, the edge of the incisor curves towards the palatal surface from the side of the palate. It refers to the lingual expansion of the incisor teeth’s lateral margins.
Type I shovel-shaped incisor: Trace shovel. Arrows indicate distinct traces of enamel rim at the palatal surface of maxillary central incisor, and lateral incisor teeth, https://www.researchgate.net/figure/Type-I-shovel-shaped-incisor-Trace-shovel-Arrows-indicate-distinct-traces-of-enamel-rim_fig1_259169427
  • Protostylid: It’s a term for an additional cusp on the buckling surface of the mandibular first molar.

Dental Anomalies based on Number:

  • Anodontia: It is a hereditary condition characterised by the loss of all teeth, and it is exceedingly unusual to find a pure form without any other defects. This is a condition in which the number of teeth is less than normal. It can be partial or full.
  • Hypodontia: It is genetic in origin and the most common location is between two central incisors, hence the name “Mesiodens.” It refers to the presence of more teeth than the normal or common number, also known as supernumerary teeth. It is genetic in origin and the most common location is between two central incisors, hence the name “Mesiodens.” Another typical site is after the third molar, which is referred to as “Paramolar.”
Dental Anomalies and Their Significance, Pathshala
  • Oligodontia: It is often used to describe a disease in which more than six teeth are missing and is hereditary in nature.
Dental Anomalies and Their Significance, Pathshala

Dental Anomalies based on Structure:

  • Environmental enamel hypoplasia: It’s a defect related to the teeth’s organic enamel matrix’s development. Enamel hypoplasia can be caused by a variety of environmental causes, including: vitamin A, C, and D insufficiency, hypocalcaemia, birth damage, and congenital syphilis are all examples of nutritional deficiencies.
  • Amelogenesis imperfecta: These are enamel defects that are passed down through the generations. Because the mesodermal components of the teeth are normal, it is an ectodermal disruption.
Dental Anomalies and Their Significance, Pathshala

FORENSIC SIGNIFICANCE

  • When soft tissues are damaged, carbonised, or missing for whatever cause, bones and teeth sometimes become the primary source of information about the deceased’s identity.
  • Anything unusual in the human dentition, such as deviations from normality, might aid in identifying a person. This is a useful tool when attempting to determine the identity of the deceased.
  • Teeth and jaws are typically resistant to fire and mechanical stress, as well as post-mortem decomposition and destruction.
  • After mass disasters such as explosions, house fires, aircraft accidents, earthquakes, and shipwrecks, dental findings establish the identification of single individuals after accidental death or homicide, as well as the differential identification of large numbers of individuals after mass disasters such as explosions, house fires, aircraft accidents, earthquakes, and shipwrecks.
  • Bite marks can be used as circumstantial evidence to link a perpetrator to a crime.
  • Teeth may be used to determine sex and blood group from the pulp cavity of cells.
  • When accessible, a dental radiograph is one of the most important pieces of evidence for forensic purposes. The Panorex X-ray method produces an outstanding graphic dental record that is simple to understand. The Computer-Assisted Postmortem Identification (CAPMI) System analyses dental data of mass catastrophe victims to enable fast identification of victims of plane crashes, floods, and explosions.
SOURCES AND REFERENCES

Authored By:

AKHILA PRABHAKAR

BSc Forensic Science

Jain (Deemed-to-be-University)