Raman Spectroscopy Jnrt2009!1!16

8/12/2019 Raman Spectroscopy Jnrt2009!1!16

1/6

JOURNAL Of NUCLEAR And Related TECHNOLOGIES, Volume 6, No. 1, Special Edition, 2009

141

17

AN EXPLORATORY STUDY OF HUMAN TEETH ENAMEL BY

USING FT-RAMAN SPECTROSCOPY

Afishah Alias

1

, Siti Rahayu Mohd Hashim

1

, Judith Mihaly

2

, Julynnie Wajir

1

&Fauziah Abdul Aziz1

1School of Science and Technology, Universiti Malaysia Sabah, Kota Kinabalu, 88502,

Sabah, MALAYSIA2Chemical Research Center, Hungarian Academy of Sciences, H-1525, Budapest, P.O.

Box 17, Hungary

ABSTRACT

Unaffected, affected and heavily affected teeth enamel were studied by using FT-Raman

spectroscopy. The 14 permanent teeths enamel surface were measured randomly, resulting intotal n=43 FT-Raman spectra. The results obtained from FT-Raman spectra of heavily affected,

affected and unaffected tooths enamel surfaces did not show any significant difference. In this

study, Kruskal-Wallis and Wilcoxon rank sum tests were used to compare the intensity between

the categories of enamel as well as the surfaces of teeth samples.

ABSTRAK

Tidak terjejas, terjejas dan terjejas dengan teruk enamel gigi telah dipelajari dengan

menggunakan spektroskopi FT-Raman. 14 enamel gigi kekal permukaan telah diukur secararawak, mengakibatkan dalam jumlah n=43 spektrum FT-Raman. Keputusan-keputusan itu

diperolehi dari spektrum FT-Raman terjejas dengan teruk, gigi terjejas dan tidak terjejaspermukaan-permukaan enamel melakukan tak tunjuk mana-mana perbezaan penting. Dalam

kajian ini, Kruskal-Wallis dan Wilcoxon ujian-ujian jumlah lebat adalah sudah biasa

bandingkan keamatan antara kategori-kategori enamel serta permukaan-permukaan contoh-

contoh gigi.

Keywords:human teeth enamel, FT- Raman spectroscopy, Kruskal-Wallis, Wilcoxon

INTRODUCTION

Dental caries is the common oral disease in the developed country. Carious lesions are regularly

found at area between adjacent teeth. The detection of the caries lesions in these areas is

difficult. These characteristics of the caries problem magnify the limitations of caries detectionthrough conventional diagnostic methods that involve subjective clinical criteria and the use of

diagnostic tools such as the dental explorer and dental radiographs (Alex et al., 2006). These

conventional methods are adequate for detection of larger, possibly cavitated lesions, but due to

poor specify and sensitivity, they are not suitable for detection of early stage, non-cavitated

lesions (Alex et al., 2006). Therefore, better diagnostic tools are needed to detect early non-

cavitated lesions and to monitor their activity (Alex et al., 2006). Polarized Raman spectroscopy

and optical coherence tomography have been used to detect these changes and potentially offer

a means to detect and monitor early caries development (Michael et al., 2006).


2/6


142

In this study, unaffected, affected and heavily affected teeth enamel were studied by using FT-

Raman spectroscopy and the first attempt was to analyze the data by using General Linear

Modeling (GLM) method, two-way ANOVA. Unfortunately, the tests failed to identify

significant differences of intensity amongst the three conditions. The results could be due to the

critical violation of the normality assumption. This study has carried out non-parametric test as

an alternative, as the data failed to follow the normality distribution after severaltransformations.

EXPERIMENTAL METHOD

The samples of human adult teeth were obtained from Dr. Rashid Dental Clinic. From theseteeth samples obtained, its have been categorized to 3 types of teeth: - heavily affected, affected

and unaffected enamel. The enamel that has more than 3 affected surfaces was classified as

heavily affected enamel, 3 or less affected surfaces as affected enamel and has non affectedsurface as unaffected enamel. They were then sterilized with sodium-hypochlorite of 5% water

solution for 4 hours. These were then treated in a 6.85 M KOH water solution for 50 hour whilechanging the solution for every 2-3 hour (Fattibene et al., 2005).

The enamel samples were then investigated by FT-Raman spectroscopic method at Chemical

Research Center, Hungarian Academy of Sciences, Budapest, Hungary. The measurements

were performed by BioRad (Digilab) dedicated FT-Raman spectrometer equipped with liquid

nitrogen cooled germanium detector and Nd:YAG excitation laser with radiation line at 1064

nm. No sample preparation was required and the measurements were completely non-

destructive. All spectra were collected using 500mW laser power, 4 cm-1 resolution and co-

addition of 512 individual spectra. The spectra were than baseline corrected and normalized to

the strongest 958 cm-1peak, using Grams32 spectral evaluation program.

The Kruskal-Wallis test is applied to compare two or more populations with the data are either

ordinal or interval but non-normal (Keller and Warrack, 2003). In this study, the populationsreferred to are the classification of enamels and the position of enamel during the spectroscopy

test. The test statistic of Kruskal-Wallis test is;

H =( )

( )131

12

1

2

+

+

=

nn

T

nn

k

j j

j (1)

Where, n = the number of observations

k = the number of populations compared

j = 3 ( classification of enamels) @ 2 (enamel positions)

T = the total of ranks

However, the Kruskal-Wallis can determine only whether a difference exists. To

determine whether one population is larger than another, this study applied the Wilcoxon rank

sum test. The standardized test statistic is;

Z =( )

T

TET

(2)

Where,


3/6


143

E (T) =( )

2

1211 ++ nnn (3)

and,

( )12

12121 ++= nnnnT (4)

Both n1and n2is the number of observations belonged to two groups, lower ranks group and

higher ranks group respectively.

RESULT AND DISCUSSION

The results obtained from FT-Raman spectra of heavily affected, affected and unaffected tooth

enamels surfaces did not show any significant difference. Figure 1 showed FT-Raman spectraof heavily affected (upper spectrum), affected (middle spectrum) and unaffected (lowerspectrum) tooths enamel surfaces. For discriminating the 3 types of tooth enamel with FT-

Raman spectral features, Kruskal-Wallis was applied. The result in Table 1 showed that there is

significant difference between the types of enamel and the positions of enamel with p-value 0.05). It showed that the difference of the mean rank of intensity is depends on

the categories of the teeth.

1664

1448 1

068

1042

958

877

606588

578

445 4

29

606

0

.2

.4

.6

.8

1

1.2

1800 1600 1400 1200 1000 800 600 400 200

1664

1448 1

068

1042

958

877

606588

578

445 4

29

606

0

.2

.4

.6

.8

1

1.2

1800 1600 1400 1200 1000 800 600 400 200

3PO

4

1099

1PO4

4PO

4

2PO

4

ACO3

Figure 1: Spektra FT-Raman of heavily affected (upper spectrum),

affected (middle spectrum) and unaffected (lower spectrum)

enamel teeth.


4/6


144

Table 1: The Kruskal-Wallis results on determining a significant difference of intensity between

the types of enamel and the surface.

Intensity by enamel types Intensity by surface

Chi-square statistic 63.951 19.463

Degree of freedom 2 1

Significant value, p < 0.001 < 0.001

Mean ranks between side enamel surface and

occlusal enamel

4900

4950

5000

5050

5100

5150

5200

5250

5300

5350

Surface

In

ten

sity

side enamel surface

occlusal surface

Figure 2: The mean ranks between side enamel surface and occlusal

enamel.


5/6


6/6


146

CONCLUSIONS

The results obtained from FT-Raman spectra of heavily affected, affected and unaffectedtooths enamel surfaces did not show any significant difference. However, by using Kruskal-

Wallis and Wilcoxon rank sum tests, the intensity between the categories of enamel as well as

the surfaces of teeth samples can be discriminated. The results showed that Wilcoxon rank sum

tests can be an indicator to characterize the conditions of the teeth.

ACKNOWLEGMENT

The authors acknowledge the Hungarian Academy of Sciences and Universiti Malaysia Sabah

for full support and cooperation.

REFERENCES

Alex C.-T. Ko, Lin-P'ing Choo-Smith, Mark Hewko, Michael G. Sowa, Cecilia C. S. Dong,

and Blaine Cleghorn., (2006), Detection of early dental caries using polarized Raman

spectroscopy Optics Express, Vol. 14, 1: 203-215.

Michael, G. S., Dan P. Popescu, Jeffrey Werner, Mark Hewko, Alex C.-T. Ko, Jeri Payette,

Cecilia C. S. Dong, Blaine Cleghorn and Lin-Ping Choo-Smith., (2006), Precision

of Raman depolarization and optical attenuation measurements of sound tooth

enamel. Analytical and Bioanalytical Chemistry. ISSN 1618 - 2642. Vol. 387, 5:1613-1619.

Keller, G. and Warrack, B., (2003), Statistics for Management and Economics. ISBN 0-534-

39186-9, 6thedition, Thomson Learning.

Documents

Raman Spectroscopy Jnrt2009!1!16