NON CONVENTIONAL METHODS FOR THE ASSESSMENT
OF MANDIBLE BONE QUALITY
Malvina Orkoula
Dept. of Pharmacy, University of Patras, 265 00 Patras, Greece
Sofia Panteliou
Machine Design Laboratory, Dept. of Mechanical Engineering and Aeronautics
University of Patras, 265 00 Patras, Greece
Christos Kontoyannis
Dept. of Pharmacy, University of Patras, 265 00 Patras, Greece
Konstantinos Lianos
Machine Design Laboratory, Dept. of Mechanical Engineering and Aeronautics
University of Patras, 265 00 Patras, Greece
Keywords: Damping, Raman, Mandible, Bone Quality.
Abstract: The contemporary methods for the assessment of the quality of human mandible, in order to facilitate the
decision making for dental implants, include bone density measurements through dual-energy X-Ray
absorptiometry (DEXA) or its variations. The estimation of mandible quality with these methods is related
to subjectivity, comparability and reliability problems, which result in restricted capability of secure
assessment of bone quality. Monitoring of loss of structural integrity is applied in this work through modal
analysis and Raman Spectroscopy, in order to obtain objective assessment of mandible bone quality.
Specifically, modal damping factor (MDF), bone mineral density (BMD) and Raman measurements are
performed on human cadaveric mandibles. From the data acquired clearly arises a very promising
correlation between MDF, BMD and RAMAN, reinforcing the belief from our previous research findings
that the MDF method can lead to a mandible quality assessment tool, thus encouraging further research
investigation.
1 INTRODUCTION
Bone quality is a term that may on occasion refer to
one or more of the following: density,
macrostructure, microstructure, mechanical
properties and biologic response to physiologic
stimulae and external influences, one of them being
placement of implants.
Bone density is often used as an estimator of
bone quality. There is a variety of in-vitro and in-
vivo methods that are used for evaluation of
mandibular bone density and they can be broadly
categorized in:
1. Histomorphometry of biopsy samples
2. Empiric topographic prediction methods based
on combinatio of anthropometric data and
panoramic radiographs
3. Torque resistance measurements during implant
insertion
4. X-ray absorption methods
The histological and morphometric bone
measurement has been considered the golden
standard for bone density measurements (Molly L.,
2006). It is an invasive and deleterious method for
the donor site, during which, small biopsy specimens
of 2mm diameter are harvested from patient’s jaws
353
Orkoula M., Panteliou S., Kontoyannis C. and Lianos K..
NON CONVENTIONAL METHODS FOR THE ASSESSMENT OF MANDIBLE BONE QUALITY.
DOI: 10.5220/0003157103530358
In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2011), pages 353-358
ISBN: 978-989-8425-37-9
Copyright
c
 2011 SCITEPRESS (Science and Technology Publications, Lda.)

immediately before implant placement (3,75mm
diameter).
The empiric method of Lekholm and Zarb
(Branemark P.I., 1985) lacks precision and is related
to subjectivity, comparability and reliability
problems, which result in restricted capability of
secure assessment of bone quality. Although it is an
easy and inexpensive method it cannot discriminate
between osseous sites at the same individual.
Insertion torque measurements are not a true
bone density evaluator. A variety of implant
parameters, as design characteristics and insertion
technique features, co-influence the actual
measurements (Ostman P.O., 2005).
From the clinical standpoint, a bone density
evaluation method should have a preoperative
character, in order to be useful for appropriate
treatment planning. Therefore, histomorphometry
and insertion torque measurements are not
convenient, since the decisions have already been
taken and the results can be used only for post
insertion evaluation and statistical correlation with
success data. The empiric method is a general, crude
estimation which is non accurate between potential
implant sites.
The most commonly used density evaluation
methods in dental practice are the radiographic ones
and mainly the computed tomography (CT).
Estimation of radiographic density on Hounsfield
units allows for site specific presurgical evaluation
of bone density and selection of the most suitable
implant placement (Norton M.R., 2001). The main
disadvantage of CTs is the high irradiation dose the
patient has to be exposed to. Other radiographic
methods with lower irradiation burden are used
[(panoramic, periapical, cone beam CT) and Dual
Energy X-ray Absorptionmetry (DEXA)] having the
lowest irradiation dose of 1-10μSV equivalent to the
average natural irradiation dose received by the
human body (7μSV)). The measurements accuracy
is affected by the fat content of the soft tissue and
the discrimination between cortical and trabecular
bone is impossible due to superimposition (Blake
G.M., 1997). DEXA is mainly used for evaluation of
bone mineral density (BMD) of the lower spine and
femoral neck. It is used for osteoporosis clinical
diagnosis and in epidemiological studies for
assessment of fracture risk. In the stomatognathic
area it is used only for research purposes and only in
the mandible (Horner K., 1998).
Despite the wide range of bone density
evaluation methods there is both clinical and
research interest in the preoperative planning of
implant placement, for a non-invasive, non-
irradiating, non-destructive method. Hence, it is
obvious that other more reliable methods are needed,
capable to assess bone structural integrity and effect
of therapeutic treatment in a non invasive manner.
Loss of structural integrity of an ageing
component is usually due to fatigue, which in turn
leads to initiation and propagation of starting failure
points, and finally to structure failure. Methodology
has been developed for changes identification e in
structural integrity through modal analysis and
monitoring of modal damping factor (MDF). From
our previous experimental work (Panteliou S.D.,
1997a, 1997b, 2000, 2001, 2010) it was shown that
damping factor is sensitive to fatigue and change in
porosity. For better understanding of experimental
results, model has been developed quantifying the
relation between changes in damping and porosity.
This model, including analytic – arithmetic tool and
dedicated measuring device, has been successfully
applied on components made out of a variety of
materials, conventional and advanced. One very
successful application of the method was the
assessment of bone structural integrity, for
monitoring metabolic diseases of bones (i.e.
osteoporosis) (Panteliou S.D., 1999, 2004,
Anastassopoulos G., 2010, A. Stavropoulou A.,
2005, Christopoulou G.E., 2006).
Raman spectroscopy is a recently developed tool
for bone chemical quality assessment. A bone
Raman spectrum contains information on collagen
and bioapatite vibrations, thus chemical analysis of
its major constituents can be obtained. Most of
available techniques e.g. DEXA, yield information
on the mineral content but with Raman additional
information is harvested for organic matrix as well,
which is also considered important, as, though
mineral gives bone hardness, collagen contributes to
its elasticity. Raman has been applied on bone
samples for various purposes such as evaluation of
osteoradionecrosis resulting from radiation therapy
(Lakshmi R., 2003), establishment of bone apatite
(BAP)/matrix (MTX) ratio
(Chen T., 2002, Kosloff
K., 2004), assessment of influence of bone tissue
specimen preparation, mineralization and
biomechanical studies as described by Morris-
Finney (Morris M, 2004). Recently, some attempts
were made to non-invasively record bones Raman
signal (through the skin) but no quantitative results
were obtained yet (Eliasson C, 2007, Schulmerich
MV., 2009).
The target of this work is the development of non
invasive tools, based on MDF and Raman, for
objective assessment of mandible bone quality
(assessment of structural integrity and chemical
BIODEVICES 2011 - International Conference on Biomedical Electronics and Devices
354

quality). The techniques were experimentally
applied on cadaveric human mandibles. Besides,
conventional DEXA measurements were performed
on the same mandibles. The results from the
comparison of the measured data with the three
methods constitute a promising basis, which
reinforces our belief that we can build assessment
tools for use in the process of dental implants
placement.
2 EXPERIMENTAL WORK
Ten cadaveric human mandibles of random age were
used to acquire in-vitro measurements of mandible
quality with three methods: Modal Damping Factor
(MDF), BMD (Bone Mineral Density) with DEXA
and Raman Spectroscopy (RAMAN).
2.1 Modal Damping Factor
Modal Damping Factor is measured with designed
and constructed dedicated device (Figure 1).
Thorough description of device principle can be
found in (Panteliou S.D., 2004)
.
Figure 1: Experimental device for damping measurement.
For MDF calculation half power bandwidth
method is applied (Dimarogonas A.D., 1992). The
sensor used is a PCB accelerometer of 1 gr. Its
output signal is transferred through an A/D converter
to a PC. Triggering is produced by computer
controlled sound electronics and is applied through a
metallic stem to the selected mandible anatomic site.
MDF is extracted by Fast Fourier Transform (FFT)
analysis of time response data (Dimarogonas A.D.,
1992). Ten points are selected on each mandible
(Figure 2). Mandible mid-span is selected for
triggering. The output sensor (accelerometer) is
placed consecutively on the other points. MDF
values (approximately 25) are acquired at each
mandible point to ensure statistically sufficient
population. MDF of each point occurs as average of
all 25 measurements. The procedure is repeated for
all points of all mandibles. From these data an
overall average MDF value is extracted
corresponding to each anatomic point selected.
Figure 2: Triggering and measuring points.
2.2 Bone Mineral Density
Bone mineral density is measured according to
standard protocol by Dual-energy x-ray
absorptiometry (DEXA), using Norland XR-26
MARK-II bone densitometer. Scans are acquired
and processed with ultra-high resolution software
(from manufacturer). Anatomic regions examined
are the same as above mandible points (Figure 2).
Time required for typical scan at each point
approximately 3 minutes.
Overall average of measured MDF-BMD in
relation to anatomic site of measurement are
presented in Figure 3, while the correlation between
MDF and BMD is presented in Figure 4.
2.3 Raman Spectroscopy
Raman spectra is recorded using a FRA-106/S FT-
Raman (Bruker, Karlsruhe, Germany) with the
following characteristics: Laser excitation line used
is the 1064nm of a Nd:YAG laser. Reference source
(He-Ne laser) is used to measure the instrumental
response and check the interferometer. Filters are
used to remove the Rayleigh line and the optical
output of the He-Ne laser.
Scattered light is collected at an angle of 180°
(back-scattering). The system is equipped with a
LN
2
cooled Ge detector (D 418). The power of
Measuring Points
Triggering Point
1
2
3
4
5
10
9
8
7
6
NON CONVENTIONAL METHODS FOR THE ASSESSMENT OF MANDIBLE BONE QUALITY
355

Figure 3: Correlation of MDF-BMD with anatomic site for
all mandibles.
Figure 4: Correlation MDF-BMD for all mandibles.
incident laser beam is about 150 mW on sample's
surface. Typical spectral width is 2 cm
-1
. The system
is interfaced with computer. Laser beam spot size on
sample is 100 μm
2
. An X-Y-Z motor (Bruker,
Karlsruhe, Germany) is used for sample “mapping”.
Raman spectra are obtained from the same as
above mandibles points (Figure 2). Raman spectrum
taken on a random spot of a mandible bone is shown
in Figure 5. It contains all characteristic bands of its
constituents corresponding to their vibrations. For
the analysis, peaks at 960 and 1600 cm
-1
, for
biological apatite and collagen respectively, are
used.
0 500 1000 1500 2000 2500 3000 3500 4000
Organic matrix (Collagen)
Mineral (Apatite)
Relative Intensity
Raman Shift (cm
-1
)
Figure 5: Raman spectrum of mandible bones.
Characteristic bands of mineral (960 cm
-1
) and organic
matrix (1600 cm
-1
) used in analysis are indicated.
Average areas under the 960/cm peak of all
mandibles for each measurement point are shown in
Fig. 6.
Respective average Raman signals for collagen
(areas under the 1600cm
-1
peak) for all measuring
spots are plotted in Fig. 7.
3 DISCUSSION
Bone density measurements (BMD) with DEXA
method, as well as assessment of bone mandible
structural integrity through measurement of Modal
Damping Factor (MDF), and Raman Spectroscopy
(Raman) were performed.
Average values of all MDF–BMD measurements
in relation to anatomic mandible site are presented in
Figure 3, while correlation between all MDF-BMD
average values for all mandibles is presented in
Figure 4.
From both Figures (3, 4), the expected, from our
previous research findings (Panteliou S.D., 1999,
2004, Anastassopoulos G., 2010, A. Stavropoulou
A., 2005, Christopoulou G.E., 2006), correlation
between MDF and BMD is revealed. Specifically,
low BMD, expressing reduced bone density and low
bone quality, corresponds to high MDF, which in
turn expresses bone quality deterioration.
At this point, let’s note that MDF is material and
system property and index of structural integrity,
which takes dimensionless values between (0-1),
with higher values corresponding to low and lower
values corresponding to high structure quality.
Besides, MDF method has the following
BIODEVICES 2011 - International Conference on Biomedical Electronics and Devices
356

024681012
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
Point on the mandible bone
Area at 960 cm
-
1
(apatite)
Figure 6: Average Raman signal (area) for mineral part
alongside mandible bones.
024681012
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Point on the mandible bone
Area at 1600 cm
-1
(collagen)
Figure 7: Average Raman signal (area) for organic matrix
(collagen) alongside mandible bones.
advantages in comparison to conventional methods
for in-vivo and in-vitro bone quality assessment:
non-invasive, paneless, short duration, low cost,
easy use, portable, more sensitive than all
conventional methods (Anastassopoulos G., 2010),
objective, data can be tele-transfered for diagnosis of
patients in remote areas. In fact, MDF identifies
changes in bone structure. Thus, external factors (i.e.
soft tissues etc.) do not affect MDF measurements
because, once an initial MDF value is obtained, it's
subtraction from any other expresses change only in
bone density, given that all external factors remain
unchanged.
From apatite Raman vibration (Figure 6) it can
be seen that the middle part (foreground) exhibits
increased apatite signal compared to the sides. This
is ascribed to corresponding increased mineral
amount in this specific area which is in absolute
accordance with BMD measurements (Figure 3).
The same trend is recorded in Fig. 7 from collagen
vibrations i.e. there is substantial increase for
mandible bone foreground part. Matrix content
(Figure 7) is consistent with mineral variations
(Figure 6) leaving mineral to matrix ratio constant
along the mandible. This ratio is a crucial parameter
because it is indicative of bone quality status. Ratio
disorders conclude to severe pathological conditions
(osteoporosis, osteopetrosis, osteogenesis imperfecta
etc.). Information on collagen is exclusively
harvested by Raman Spectroscopy as none
conventional technique (DEXA) refers in any way to
collagen. Raman Spectroscopy complements MDF
testing, analyzing its chemical constituents in
molecular level. Results actually surpass BMD, as
they are more accurate in mineral analysis and probe
organic matrix.
4 CONCLUSIONS
In our previous research works (Panteliou S.D.,
1997a, 1997b, 1999, 2000, 2001, 2004, 2010,
Anastassopoulos G., 2010, A. Stavropoulou A.,
2005, Christopoulou G.E., 2006) the application of
the damping method as a tool for assessment of
structural integrity for a variety of materials
(conventional and advanced, i.e. composites) and
geometries, has been elaborated. Specific application
was on bones in order to create a bone quality
assessment tool applicable for monitoring of
metabolic bone diseases, especially osteoporosis.
Comparison of measured data with MDF and all
conventional methods (DEXA, pQCT, biochemical
markers, histomorphometry, Raman Spectroscopy)
gave very promising results, and constituted the
basis for this initial experimental work, aiming to
build an objective assessment tool of human
mandible quality that will help the decision making
during dental implants placement.
The results of this work present a clear
correlation in the expected direction. Specifically,
MDF and BMD as well as Raman data expand in an
inverse manner. High BMD values, expressing high
bone density, and high Raman intensities indicating
more mineral and organic material correspond to
low MDF values, which in turn express
improvement of bone structure and vice versa.
Hence, this work reinforces the belief that MDF can
be advanced to a valuable assessment tool for
mandible bone quality.
REFERENCES
Anastassopoulos G., Panteliou S. D., Christopoulou G. E.,
Stavropoulou A., Panagiotopoulos E., Lyritis G.,
Khaldi L, Varakis J., 2010, Vibrational Bone
NON CONVENTIONAL METHODS FOR THE ASSESSMENT OF MANDIBLE BONE QUALITY
357

Characteristics vs Bone Density in Assessing
Osteoporosis in ovariectomized rats, Journal of
Medical Engineering & Technology, 34(01), pp. 35-
42, DOI: 10.3109/03091900903324056.
Blake G. M., Fogelman I., 1997, Technical principles of
dual energy X-ray absorptionmetry, Semin Nucl Med,
27:210-228.
Branemark P. I, Zarb G. A, Albrektsson T., 1985, Tissue
Integrated Prostheses, Quintessence Publishing Co.,
Inc..
Chen T., Shea D., Morris M., 2002, Effect of hydrogen
peroxide bleaching on bone mineral/matrix, Applied
Spectroscopy, 56, pp. 1035-1037.
Christopoulou G. E., Stavropoulou A., Anastassopoulos
G., Panteliou S. D., Papadaki E., Karamanos N. K,
Panagiotopoulos E., 2006, Evaluation of modal
damping factor as a diagnostic tool for osteoporosis
and its relation with serum osteocalcin and collagen I
N-telopeptide for monitoring the efficacy of aledronate
in ovariectomized rats, Journal of Pharmaceutical and
Biomedical Analysis, 41, pp. 891-897.
Eliasson, C, Matousek P., 2007, A Noninvasive method
for deep Raman Spectroscopy of living tissue and
powders American Laboratory, 39, pp. 42.
Horner K., Devlin H., 1998, The relationship between two
indices of mandibular quality and bone mineral
density measured by dual energy X-ray
absorptionmetry, Dentomaxillofac Radiol, 27:17-21.
Kosloff K., Carden A., Bergwitz C., Forlino A., Uveges
T., Morris M., Marini J., Goldstein S., 2004, J. Bone
Miner Res 19, pp. 614.
Lakshmi R., Alexander M., Kurien J., Mahato K., Kartha
V., 2003, Applied Spectroscopy, 57, pp. 1100.
Molly L. 2006, Bone Density and Primary Stability in
Implant Therapy. Clin Oral Impl Res, 17:214-135).
Morris M. and Finney W., 2004, Recent developments in
Raman and infrared spectroscopy and imaging of bone
tissue Spectrosc-Int. J. 18, pp. 155-159 and references
therein.
Norton M. R., Gamble C., 2001, Bone classification: an
objective scale of bone density using the computerized
tomography scan, Clin Oral Impl Res, 12:79-84.
Ostman P. O., Hellman M., Sennerby L., 2005, Direct
implant loading in the edentulous maxilla using a bone
density-adapted surgical protocol and primary implant
stability criteria for inclusion. Clin Impl Dent Relat
Res, 7(supp I):S60-S69).
Panteliou S. D., Dimarogonas A. D., 1997a,
Thermodynamic Damping in Porous Materials with
Ellipsoidal Cavities, Journal of Sound and Vibration,
201(5), 555-565.
Panteliou S. D., Dimarogonas A. D., 1997b,
Thermodynamic Damping in Porous Materials with
Spherical Cavities, Journal of Shock and Vibration,
Vol. 4, No. 4, pp. 261-268.
Panteliou S. D., Abbasi-Jahromi Hassan, Dimarogonas A.
D., Kohrt W., Civitelli R, 1999, Low-Frequency
Acoustic Sweep of Bone Integrity and Osteoporosis,
Journal of Biomechanical Engineering, Aug. 99, Vol.
121, pp. 423-431.
Panteliou S. D., Dimarogonas A. D. 2000, Damping
Factor Associated with Porosity and Crack in Solid,
Theoretical and Applied Fracture Mechanics, 34 217-
223.
Panteliou S. D., Chondros T. G., Argyrakis V. C,
Dimarogonas A. D., 2001, Damping Factor as an
Indicator of Crack Severity, Journal of Sound and
Vibration, 235-245, 241(2).
Panteliou S. D., Xirafaki A. L., Panagiotopoulos E,
Varakis J., Vagenas N. V., Kontoyannis C. G., 2004,
Modal Damping for Monitoring Bone Integrity and
Osteoporosis", Journal of Biomechanical Engineering,
Vol. 126, pp. 1-5.
Panteliou S. D., Zonios K., Chondrou I. T., Fernandes H.
R., Agathopoulos S., Ferreira J. M. F., 2010, Damping
Factor Associated with Porosity in Alumina,
International Journal of Mechanics and Materials in
Design, 5:167-174, DOI 10.1007/s10999-008-9092-0.
Schulmerich M. V., Cole J. H., Kreider J. M., Esmonde-
White F., Dooley K. A., Golstein S. A., Morris M. D.,
2009, Transcutaneous Raman Spectroscopy of Murine
Bone In Vivo Applied Spectroscopy 63, pp 286-295.
Stavropoulou A., Christopoulou G. E., Anastassopoulos
G., Panteliou S. D., Lyritis G. P., Spiliotis B. E.,
Karamanos N. K., Panagiotopoulos E., Lambiris E.,
2005, Alteration in serum leptin correlates with
alterations in serum N-telopeptide of collagen type I
and serum osteocalcin during the progression of
osteoporosis in ovariectomized rats, Clinical Chemical
Laboratory Methods, 43(12): 1359-1365.
BIODEVICES 2011 - International Conference on Biomedical Electronics and Devices
358