Manungso Lawas

Principal Axis Method

# The principal axis method is an age independent analysis method for dental attrition [1538:203]

# High slopes indicate rapid rates of wear. Because rate of wear rather than degree of wear is the parameter of interest, the procedure is AGE INDEPENDENT [1538:230]

# To avoid the problem of age dependence inherent [yg menjd sifatx/bg tetap] with dental attrition data, Smith (1972) suggested using the rate of wear as a useful parameter for comparisons of dental attrition [1538:203]

# Teeth have a ‘built in’ rate indicator in that not all teeth erupt at the same time, so that differences in wear between teeth erupting at different times provide information about the rate of wear [1538:203]

# Miles (1963) used the difference between teeth erupting at different times to indicate the age at death of a specimen; this can of course be used to indicate rate of wear as well (Nowell 1978) [1538:204]

# To determine rate of wear, Smith (1972) suggested using pairs of adjacent molar teeth.Since molar teeth erupt at approximately six year intervals, the tooth first to erup will have some amount of wear on it before the second tooth erupts [1538:204]

# From the time the second tooth reaches the level of occlusion until one or another is worn down to roof level, the initial differences in wear of the tooth should be retained. This wear difference indicates the rate of wear in the population [1538:204]

# There is evidence that teeth erupt at about the same intervals (for molars, approximately 6 years apart) in all populations, thought the age of onset of these eruptions differs. For example first molar appears at age 6 years old [1538:204]

# The rate of wear is a useful contribution to the study of dental attrition. For purpose of showing populational differences in dental attrition, the method of principal axis analysis is most appropriate [sesuai, cocok][1538:204]

# Mandibular and maxillary teeth were visually scored according to two ordinal scale procedures that of Molnar (1972) and Scott (1976, 1979). Mandibles were analyzed separately from maxillae. Teeth from the left side of the jaw were used except where unavailable, in which case a pair from the right side were substituted [1538:205]

# The analysis method yielded most consistent results when used upon data scored with the 4-40 scale [1538:210]

# In the Molnar scoring, SEVERELY WORN TEETH were those with a score of 7 or 8; in Scott scoring these were teeth with a score in excess of 36 [1538:205]

# the wear scores of the molar first to erupt were plotted on the Y axis and the molar second in series on the X axis. While it would be possible to use the M1M2, M1M3 or M2M3 pairs, I used M1M2 because of the frequent problems in archaeological populations of non eruption and agenesis of third molars. Also, the eruption of the third molar is more variable in timing, complicating rate calculations for M1M3 or M2M3 pairs [1538:205]

# Rates calculated for mandibular teeth and those calculated for maxillary teeth differ for the two food producing groups. The reason for this is not clear. It may be that the maxillary and mandibular molars, having different average numbers of cusps and being differently subjected to [dikenakan] occlusal stress, actually do wear at different rates [1538:207]


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