Introduction to Teeth - Dental Biotribology - page 3

Table 1.1 Classiica tions and definitions of tooth surface loss
Mode Deinition
Abrasion The pathological wearing away of dental hard tissue through an abnormal
mechanical process involving foreign objects or substance repeatedly
introduced in the mouth and contacting the teeth
Attrition The physiological wearing away of dental hard tissue as a result of
tooth-to-tooth contact with no foreign substance intervening
Erosion The physical result of a pathologic, chronic, localized, painless loss of
dental hard tissue chemically etched away from the tooth surface by acid
and/or chelation without bacterial involvement
Resorption The process of biological degradation and assimilation of substances or
structures previously produced by the body
Abfraction A special form of wedge-shape defect at the cementoenamel junction of a tooth
Demastication The wearing away of tooth substance during the mastication of food with
the bolus intervening between opposing teeth
Source : From Imfeld [ 11 ]
particles between two surfaces. Adhesive wear is the process by which material is
transferred from one surface to another during relative motion. Fatigue wear is fre-
quently related to the formation of surface or subsurface cracks, and then particles
of detachment under repeated and higher contact stress condition. Wear by erosion
mainly describes surface damage in either a liquid-solid or gas-solid flow system.
Corrosive wear is considered substance loss under chemical or electrochemical
action often combined with relative motion. Fine debris detached from the surface
and fresh contact surface exposed to be oxidized are typical forms of corrosive wear.
With the help of an Internet search engine ( http://scholar.google.com ) in July
2012, on the keywords “teeth and wear,” more than 400,000 pieces of information
are recorded mainly in the archaeological and medical literature, extending over
many centuries. Dental wear is considered a tribological problem. However, major
research papers that have been published in various medical journals related to den-
tal research, dental material, oral rehabilitation, and the like focus on the conse-
quences of dental wear but not on the mechanisms of dental wear [ 8 - 10 ]. This topic
will illustrate why researchers and dental scientists need a deepened understanding
of the behaviors of dental wear.
In the dental literature, there are many different classifications and definitions to
describe tooth surface loss, including surface wear [ 9 , 10 ]. A representative overview
on tooth wear was made by Imfeld [ 11 ]; six kinds of noncarious tooth loss, including
abrasion, attrition, erosion, abfraction, resorption, as well as demastication, were
identified, as listed in Table 1.1 .
In most cases, the terms “dental abrasion,” “attrition,” “erosion,” and “abfrac-
tion” have been frequently used in the field of dental research. However, it should
be noted that the definition and classification of tooth surface lesions have been in a
state of confusion when used in tribology terminology. For example, there is no
such term “attrition” in the research of general wear for tribologists. In fact, “attri-
tion” merely indicates a two-body contact, such as tooth to tooth or tooth to denture