Biomedical Engineering Reference
In-Depth Information
Chapter 10
Dental Materials
Drilled molar crowns of adult persons were discovered in a Neolithic graveyard in
Pakistan (Mehrgarh, Baluchistan) dating back 8,000 years. The practice is quoted
as a type of
proto-dentistry
. Drilling was probably performed for therapeutic rea-
sons (caries?) but trace of filling material was not detected. Anyway, one thing was
clear: the drilling tool was a flint tip [313]. Flint is amorphous silica and at different
instances we underlined the basic significance of amorphous materials for mankind.
A tooth consists of an outer shiny part,
enamel
, the hardest substance in the human
body and formed during childhood, and an inner much softer part
dentine
, continu-
ously renewed like other bony tissue. The historical hierarchy of the two parts has an
interesting consequence. Concentration and isotopic ratio of, for example, strontium
in enamel is determined by childhood diet, while that of dentine is governed by the
diet of the last few years, an archaeological clue for mobility studies of early men.
An exciting example of the use of this isotopic ratio conservatism is given by the
identification of a recently found body of an unknown soldier killed during World
War I in Flanders Fields. Based on the combination of DNA analysis and determina-
tion of the isotopic ratio of strontium in enamel, he was identified by a consortium
of the Universities of Leuven, Oxford and Cranfield and Governmental Departments
of Great Britain and Australia as Private Alan James Mather. The isotopic ratio of
strontium in its enamel matched the geological characteristics of one region. DNA
analysis of potential family members in that particular region confirmed the identi-
fication. The Australian Army reburied him with full military honors alongside his
comrades in a Commonwealth War Graves Commission cemetery in Belgium on
July 22, 2010.
Tooth degradation is a problem at all times. In a Gallo-Roman necropolis archae-
ologists discovered an iron implant, substituting the right second upper premolar of
an adult man. The original tooth stood model for the implant: it fitted well the alveo-
lar wall and was
osseointegrated
. As stressed in former chapter for hydroxyapatite-
coated cementless prostheses, 'optimal fit' is the condition
sine qua non
prior to
osseointegration [314]. Once more,
we do not discover but uncover!
But before proceeding to the problems of today, mention should be made of
the name of Professor Per-Ingvar Branemark: born in Sweden in 1929, graduated
as orthopedic surgeon at Lund University, started as an Associated Professor at
Gothenburg University in 1960, where he was promoted to Professor of Anatomy
