Dental Attrition:

Introduction:  The degree of tooth wear (attrition), when seriated within a population, is a useful indicator of an individual's age at death.  Dental attrition varies with types of food consumed, thus it is important to compare teeth within the group of interest, and understand their mode of subsistence.  Numerous methods have been developed to determine age using wear patterns, several are listed below:

Inventory: Before embarking on a survey of tooth wear, it is important to have an inventory of the teeth present and their general degree of preservation. The following scoring procedure is presented in Buikstra et. al. (1994) and the diagram to the left displaying a cross section thru a tooth adapted from White (1999):

Categories for Recording the Dentition
1. Present, but not in occlusion
2. Present, development completed, in occlusion
3. Missing, w/no associated alveolar bone
4. Missing, w/alveolus resorbing or fully resorbed: premortem loss
5. Missing, w/no alveolar resorption: postmortem loss
6. Missing, congenital absence
7. Present, damage renders measurement impossible, other observations are recorded
8. Present, but unobservable (e.g. deciduous or permanent tooth in crypt)


Tooth Types:   Primates display reduced complexity in the heterodont dentition, a characteristic most notable in the omnivorous mouths of humans.  The four types of teeth found in the adult dental arcade are displayed to the right (diagram adapted from White, 1999).  The adult human's mouth contains a total of 32 teeth, with a dental formula of 2:1:2:3  (2 incisors:1 canine:2 premolars:3 molars).   Food is taken into the mouth with the anterior dentition, the incisors and canines, and processed by the premolars and molars.  These posterior teeth grind, pulp, slice and dice the foods consumed, which increases the surface area for the digestive enzymes in the mouth to act upon to begin the digestion process.
 

Dental Attrition Scoring Methods:   Wear patterns for these teeth, given their differential functions, are scored accordingly as seen in the methods outlined below.

Smith System for Age Determination Using Dental Attrition -- B. Holly Smith's (1984) method for age determination using dental attrition was based on studies of numerous populations with markedly different subsitence patterns.

Incisors and Canines:
1. Unworn to polished or small facets (no dentin exposure)
2. Point or hairline of dentin exposure
3. Dentin line of distinct thickness
4. Moderate dentin exposure no longer resembling a line
5. Large dentin area w/enamel ring complete
6. Large dentin area w/enamel ring lost on one side or very thin enamel only
7. Enamel rim lost on two sides or small remnants of enamel remain
8. Complete loss of crown, no enamel remaining; crown surface takes on shape of roots

Premolars:
1. Unworn to polished or small facets (no dentin exposure)
2. Moderate cusp removal (blunting)
3. Full cusp removal and/or moderate dentin patches
4. At least one large dentin exposure on one cusp
5. Two large dentin areas (may be slight coalescence)
6. Dentinal areas coalesced, enamel rim still complete
7. Full dentin exposure, loss of rim on at least one side
8. Severe loss of crown height; crown surface takes on shape of roots
 

Brothwell System for Scoring Surface Wear in Molars:    Brothwell's method is demonstrated diagramatically, and is useful for scoring wear on the molars (Brothwell, 1981).

Scott (1979) System for Scoring Surface Wear in Molars:

Score 0:  No information available (tooth not occluding, unerupted, antemortem or postmortem loss, etc.)

Score 1: Wear facets invisible or very small

Score 2: Wear facets large, but large cusps still present and surface features (crenulations, noncarious pits) very evident.  It is possible to have pinprick size dentine exposures or dots which should be ignored.  This is a quadrant with much enamel.

Score 3:Any cusp in this quadrant is rounded rather than being clearly defined as in 2.  The cusp is becoming obliterated but is not yet worn flat.

Score 4:Quadrant area is worn flat (horizontal) but there is no dentine exposure other than a possible pinprick sized dot.

Score 5:Quadrant is flat, with dentine exposure one-fourth of qudrant or less.  (Be careful not to confuse noncarious pits with dentine exposure.)

Score 6:Dentine exposure greater: more than one-fourth of quadrant area is involved, but there is still much enamel present.  If the quadrant is visualized as having three sides, the dentine patch is still surrounded on all three sides by a ring of enamel.

Score 7:Enamel is found on only two sides of the quadrant.

Score 8:Enamel on only one side(usually outer rim) but the enamel is thick to medium on this edge.

Score 9:Enamel on only one side as in 8, but the enamel is very thinójust a strip.  Part of the edge may be worn through at one or more places.

Score 10:No enamel on any part of the quadrantódentine exposure complete.  Wear is extended below the cervicoenamel junction into the root.
 


Miles Method for Assessing Dental Attrition:

The method developed by Miles permits within group assessment of age based on dental attrition.  It requires a subadult sample as baseline.

The upper and lower scales show ages in years from birth, with different scales for each of the molars (representing separate functional ages of the teeth).  The first molars are marked at 6 year intervals, the second at 6.5 and the third at 7 year intervals.

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Literature Cited:

BROTHWELL, D.  (1981).  Digging Up Bones.  Ithaca:  Cornell University Press, p. 72.

BUIKSTRA, J and DH UBELAKER.  (1994).  Standards for Data Collection from Human Skeletal Remains.  Proceedings of a Siminar at the Field Museum of Natural History,  Fayetteville:  Arkansas Archaeological Survey Research Series, No. 44.

HILSON, S.  (1996)  Dental Anthropology.  New York:  Cambridge University Press.

MILES, AEW.  (1962).  Assessment of age from the dentition.  Proceedings of the Royal Society of Medicine.  51:1057-1050.

SCOTT, EC.  (1979).  Dental Wear Scoring Technique.  AJPA, 51:213-218.

SMITH, BH.  (1984).  Patterns of Molar Wear in Hunter-Gatherers and Agriculturalists.  AJPA, 63:39-56.

WHITE, T.  (1999).  Human Osteology.  San Diego:  Academic Press.

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To return to the Age Determination page, click here.   To view other Age Determination methods, click on the indicated link:
  pubic symphysis
  auricular surface morphology
  bone growth and development
  epiphyseal closure
  dental eruption

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