SCANNING ELECTRON MICROSCOPIC INVESTIGATION OF DENTINAL TUBULES IN Cebus apella DENTIN
Rafael Rodrigues Lima,1 Leila Marques Araújo,2 Priscilla Rocha Affonso,2
Kalena Melo Maranhão3 and Suely Santos Lamarão4
1. Mestre e doutorando em Neurociências e Biologia Celular, professor de Histologia da UFPA.
E-mail: rafalima@ufpa.br
2. Mestranda em Clínica Odontológica. UFPA
3. Mestre em Odontologia. UFPA
4. Doutora em Endodontia, professora de Endodontia da UFPA.
ABSTRACT
The aim of the study was to
investigate the number and diameter of the Cebus apella dentinal
tubules. The roots of the Cebus apella teeth were examined in specific
tooth locations: the apical, middle and cervical dentin. The
calculations were based on the scanning electron microscope photographs
of the fractured surfaces. The results showed that the average number
of dentinal tubules for each location was: 74,800 tubules/mm2 for
apical root dentin, 90,000 tubules/mm2 for mid-root dentin, 91,600
tubules/mm2 for cervical root dentin. The average diameter was the
following: apical root dentin, 4,30µm; mid-root dentin,
4,37µm; cervical root dentin, 5,23µm. These findings
demonstrate that the Cebus apella teeth are a suitable substitute for
human in endodontics studies.
KEY WORDS: Dentin, dentinal tubules, teeth.
RESUMO
MICROSCOPIA ELETRÔNICA DE VARREDURA DOS TÚBULOS DENTINÁRIOS DA DENTINA DE Cebbus apella
O objetivo deste estudo foi
investigar o número e diâmetro de túbulos
dentinários em Cebus apella. Avaliaram-se as raízes
dentais de Cebus apella em regiões específicas:
terço apical, terço médio e teço cervical.
Para os cálculos, baseou-se em micrografias de eletrônicas
de varredura das faces internas após fratura. Os resultados
mostraram que a média do número de túbulos
dentinários por área em cada região foi de: 74.000
túbulos/mm² no terço apical, 90.000
túbulos/mm² no terço médio, 91.600
túbulos/mm² no terço cervical. A média dos
diâmetros foi de 4,30 µm no terço apical, 4,37
µm no terço médio e 5,23 µm no terço
cervical. Estes achados demonstram que os dentes do Cebus apella
são adequados substitutos de dentes humanos em estudos
endodônticos.
PALAVRAS-CHAVES: Dente, dentina, túbulos dentinários.
INTRODUCTION
The dentin is a mineralized
tissue that surrounds the dental pulp and the odontoblasts processes.
On average, the dentin contains approximately 50% of mineral volume
(hydroxyapatite crystals), 30% of organic components (mostly type I
collagen), and 20% of fluid (MJÖR et al., 2001).
The main dentin feature is
the presence of dentinal tubules, which are the responsible for the
dentin permeability. The dentinal tubules allow a direct communication
between the dentin and the pulp, and as a result of this pathway,
various therapeutic agents may affect the pulp if they are directly
applied to the exposed dentin. The rate of transport and subsequent
effect of such agents depend on the number and size of the dentinal
tubules.
Although dentin has been examined extensively (SCHILKE et al., 2000; VONGSAVAN et al., 2000; RIFAI et al.,
2004), very few studies have compared the dentin in different areas of
the root. Thus, the knowledge of the dentinal tubular pattern is
extremely important to understand the course of endodontic research.
Considering the limited
number of studies on monkey root dentin, the purpose of this study was
to investigate the number and diameter of the dentinal tubules in
monkey dentine.
MATERIALS AND METHODS
The material consisted of 8 canines with completed root development from adult animals. Two skulls of adult Cebus apella
were obtained from the postmortem room of the Institute of Research
Evandro Chagas (Pará, Belém, Brazil). The extracted teeth
were immediately stored in distilled water.
Within 24 hours after
extraction, the teeth were sectioned at the cementum-enamel junction
with a high-speed handpiece. The crowns were discarded and the roots
were fractured mesiodistally. Each specimen was placed in an ultrasonic
with 0,5% sodium hypochlorite for 5 min to remove soft tissue debris.
Next, the specimens were
placed into a vacuum and the surface was gold sputter-coated. With the
use of a scanning electron microscope, the dentin of each specimen was
examined in three areas of the root structure (apical, middle and
cervical third). A magnification of 3000 was used to facilitate the
counting of dentinal tubules and to help differentiate tubules from
artifacts.
The number of tubules was calculated according to the following formula:
X= 1.000.000 x n / (l / i )2
Where: X= number of tubules/mm2
n= number of tubules on the picture
l = length of side of picture (μm
i= magnification
Photomicrographs were taken
of each examined surface and the diameter of the tubules was measured
on the pictures. Only the tubules that showed an almost circular lumen
were selected.
RESULTS AND DISCUSSION
The permeability of dentin
in monkey is not fully understood. Therefore, the knowledge of root
dentin features is important for the endodontic research development.
The present study
calculations, obtained from the measure of the dentinal tubules number,
revealed that the average number of the dentinal tubules for each of
the three locations was the following: apical root dentin, 74,800
tubules/mm2; mid-root dentin, 90,000 tubules/mm2; cervical root dentin, 91,600 tubules/mm2.
The literature provides
little information about the distribution of dentine tubules and their
diameters in monkey teeth. Two studies concern only the coronal dentin
(FORSSELL-AHLBERG et al., 1975; KROON et al., 1986). KROON et al.
(1986) observed that the dentinal tubules run continuously from the
dentin-enamel junction (DEJ) to the pulp of the tooth. Similar findings
are described for human dentine (BRANNSTROM & GARBEROGLIO, 1972;
OUTHWAITE et al., 1976; WATERS, 1980).
Referring to the number of tubules, it was noted their decreasing according with the dentin location (Figure 1).
MJOR & NORDAHL (1996) related that the density of the tubules at
the pulpal level was lowest in the root, especially apically, in human
dentin.
ge number one each location
was the following: apical root dentin, 4,30µm; mid-root dentin,
4,37µm; cervical root dentin, 5,23µm.
In addition, the diameter of the tubules was uniform at the pulpal wall, similar of those reported by FORSSELL-AHLBERG et al. (1975).
Furthermore, the
permeability of the investigated species dentin do not differ much from
the human dentin. Finally, these results suggest that the Cebus apella
teeth are a suitable substitute for human teeth in endodontics studies.
Further studies are required to clarify this animal.
ACKNOWLEDGMENTS
Animal supported by IBAMA (process. no. 02018.005455/02-13)
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Protocolado em: 11 abr. 2007. Aceito em: 7 ago. 2008.