Characterization of the bone matrix and its contribution to tooth loss in human cadaveric mandibles.
OBJECTIVE
It is uncertain as to what extent the major bone matrix constituents, mineral and collagen, show inter-individual variation and dependence on age and sex in jawbones. The purpose of this study was to clarify this uncertainty using cadaveric mandibles and investigate the association of bone matrix with the number of existing teeth.


METHODS
Cortical bone samples (1 × 1 cm) collected from the mental of 48 cadaveric mandibles (27 men and 21 women; age range = 56-93 years and 63-103 years, respectively) were used to quantify three bone matrix indices: mineral content, collagen content and extent of lysine hydroxylation of collagen. Associations with age and comparisons by sex were evaluated based on bone matrix indices and the numbers of existing teeth. The numbers of existing teeth were compared between the groups showing low and high bone matrix index values.


RESULTS
A great amount of inter-individual variation was seen in all bone matrix indices. No bone matrix indices were associated with age, while the number of existing teeth was negatively associated with age. The bone matrix indices and number of existing teeth did not differ by sex. The number of existing teeth was nearly twice as high in the group showing high collagen content as in the low collagen group; however, an analysis of covariance showed a significant inter-group difference not from bone matrix indices, but rather from age. Interestingly, in comparison to femoral collagen, mandibular collagen showed lower lysine hydroxylation, which can represent an aspect of bone quality.


CONCLUSIONS
Mandibular bone matrix shows great inter-individual variation and is independent of age and sex, but did not show as strong a relationship with tooth loss as age. Even so, mandibular collagen may represent a unique characteristic of bone matrix and deserves to be further investigated.
Section of Fixed Prosthodontics, Department of Oral Rehabilitation.
Takashi
T
Matsuura
Michiko
M
Sasaki
Michitsuna
M
Katafuchi
Kentaro
K
Tokutomi
Emiri
E
Mizumachi
Michiko
M
Makino
Toru
T
Naito
Hironobu
H
Sato
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000032:analysis; D015519:Bone Density / Q000502:physiology; D001857:Bone Matrix / Q000737:chemistry*; D002102:Cadaver; D003094:Collagen / Q000032:analysis / Q000737:chemistry; D005260:Female; D005269:Femur / Q000737:chemistry; D006801:Humans; D006900:Hydroxylation; D008239:Lysine / Q000032:analysis; D008297:Male; D008334:Mandible / Q000737:chemistry; D008875:Middle Aged; D008903:Minerals / Q000032:analysis; D012737:Sex Factors; D014070:Tooth; D016388:Tooth Loss / Q000209:etiology*
D000596:Amino Acids; D008903:Minerals; D003094:Collagen; D008239:Lysine
age; collagen; lysine hydroxylation; mineral; sex