Study of the Correlation between the Gingival Immunologic Defense Index
and Parameters Associated with Dental Caries
Maria Cristina Monteiro de SOUZA-GUGELMIN1
Izabel Yoko ITO1
Geraldo MAIA CAMPOS2
1Faculdade de Ciências Farmacêuticas de Ribeirão
Preto,
2Faculdade de Odontologia de Ribeirão Preto,
Universidade de São Paulo, Ribeirão Preto, SP, Brasil
Braz Dent J (1996) 7(2): 91-95 ISSN 0103-6440
| Introduction | Material
and Methods | Results and Discussion | References
|
The objective of the present study was to determine the possible existence
of a correlation between the gingival immunologic defense index (GIDI)
and parameters associated with dental caries such as number of teeth with
cavities, number of colony forming units (CFU) of streptococci of the mutans
group, decay missing filling deciduous teeth (dmft), and decay missing
filling permanent teeth (DMFT). Since no correlation was detected with
the above parameters, we conclude that the simple presence of caries or
of CFU is not sufficient to stimulate IgA production and/or secretion.
For this to occur, an unfavorable action of these parameters on gingival
health is needed, with the production of gingival inflammation.
Key Words: gingival immunologic defense index, IgA, number of CFU of
streptococci of the mutans group.
Introduction
In addition to periodontal disease, another oral disease - caries - has
been related to salivary immunoglobulin levels, as also are DMF/dmf and
number of colony forming units (CFU) of streptococci of the mutans group.
In a study of unstimulated total saliva from 63 children aged 6 to 13 years,
Riviere and Papagiannoulis (1987) noted that 29 presented dental caries
and 34 did not. They investigated salivary IgA, IgG and IgM levels related
to the streptococcus strains because, in their opinion, if salivary anti-S.
mutans antibodies effectively acted on resistance to caries, then children
with higher levels of these antibodies should have a smaller number of
caries. However, no significant difference was detected with respect to
salivary IgA levels. Camling et al. (1987) noted that individuals with
active caries and/or with high decay missing filling surface (DMFS) indices
manifested a tendency to present lower IgA levels in total saliva than
individuals with a low caries experience. IgA levels were mostly higher
in the group with a small number of S. mutans (<5 x 104). Camling and
Köhler (1987), looking for a correlation between salivary S. mutans
and IgA levels of mothers and their children, observed that IgA levels
did not differ significantly between children whose mothers had received
preventive treatment against caries and children of untreated mothers,
although children of untreated mothers presented higher S. mutans levels.
Reinholdt and Kilian (1987) demonstrated that bacterial IgA-proteases that
cleave sIgA in the fold region can interfere with the mechanism of action
of this immunoglobulin, a mechanism that impairs the adhesion of oral streptococci
to hydroxyapatite and to cell surfaces. Some investigators explain the
effects mediated by IgA-protease by a reduction in the ability of Fab-alpha
fragments separated by cleavage to bind to the antigen. Reinholdt and Kilian
(1987), however, showed that, after exposure of specific sIgA to IgA-protease,
the streptococci are covered with Fab-alpha fragments. Gråhn et al.
(1988) reported a total absence of correlation between salivary IgA level
and presence of caries, as well as the absence of any correspondence between
salivary S. mutans levels and salivary anti-S. mutans antibodies. The objective
of the present study was to determine the possible existence of a correlation
between the gingival immunologic defense index (GIDI) and caries, looking
for a correlation between this new index and the number of teeth with caries
and also with the number of CFU of the mutans group.
Material and Methods
The study was conducted on 135 healthy children aged 5 to 13 years and
residing in Araraquara, State of São Paulo, from whom unstimulated
total saliva samples were obtained. The dmft/DMFT indices and the number
of CFU of the mutans group were also determined. Saliva samples were collected
into 20 x 150 mm sterile tubes; after collection, part of the saliva was
transferred to 12 x 75 mm sterile tubes and frozen for later measurement
of salivary IgA content by single radial immunodiffusion as described in
the first part of this research (Souza-Gugelmin et al., 1993). The portion
of saliva destined to the counts of CFU of the mutans group was left in
the 20 x 150 mm tubes and cooled on dry ice in a styrofoam box for transportation
to Ribeirão Preto, where it was processed by the serial solution
method. The method was used to determine the number of CFU of the mutans
group by first diluting 0.1 ml saliva in 10.0 ml sterile phosphate buffered
saline (PBS). This provided the 10-2 dilution from which the 10-3 dilution
was obtained by transferring 1.0 ml to a second tube containing 9.0 ml
PBS. Similarly, the successive transfer of 1.0 ml of a freshly prepared
dilution to the next tube containing 9.0 ml PBS provided the subsequent
dilutions, 10-4 and 10-5. The different saliva dilutions were inoculated
into SB20 medium by the glass rod technique (Davey and Rogers, 1984). This
medium was chosen because it is selective for the mutans group. Inoculation
was carried out in duplicate and the plates were incubated in anaerobiosis
jars containing 10% CO2 at 37ºC for 48 hours and at room temperature
for an additional 24 hours. CFU of streptococci of the mutans groups were
then counted using a stereoscopic microscope. After recording the counts
of the 4 duplicate dilutions for each sample, the number of CFU of the
mutans group was calculated as follows: the number of CFU of the mutans
group for each dilution was multiplied by 2 and the number of zeros corresponding
to the absolute value of its exponent plus 1 was added. The number of CFU
for each dilution was summed and divided by the number of plates counted
to obtain the mean for the first series. The same procedure was applied
to the plates of the 2nd series (duplicates), and the final number of CFU
of the mutans group present in 1.0 ml saliva was determined by the mean
calculated for the two series. Since these values were very high their
logarithms were used in the subsequent statistical calculations in order
to reduce data variability. In cases in which the number of CFU in the
first dilution was zero, the use of the logarithm was inviable since the
logarithm of zero is infinity. To overcome this drawback, we assumed 2000
to be the minimum number of colonies that would correspond to the finding
of a single colony in the lowest dilution. This strategy permitted the
lowest logarithm to be 3.30103. The DMFT/dmft indices were determined by
the same examiner immediately after saliva collection. The GIDI was calculated
as described in the second part of this study (Souza-Gugelmin et al., 1995),
i.e., by dividing the IgA level measured in saliva (mg/100 ml saliva) by
the number of inflamed gingival surfaces (NIGS) present.
Results and Discussion
A total of 135 saliva samples were obtained from children aged 5 to 13
years. IgA concentration was measured in the samples by the single radial
immunodiffusion technique as described previously (Souza-Gugelmin et al.,
1993) and the GIDI value was then calculated. This index evaluates the
immunologic potential of the gingiva with respect to IgA, as demonstrated
in the second part of this study (Souza-Gugelmin et al., 1995). Table
1 lists the results obtained for the different parameters studied in
relation to the different class intervals of GIDI. Table 1 is simply illustrative
since in the regression and correlation tests performed in the present
study we used the 135 data pairs related to each parameter. Thus, the table
is simply a summary of the general table of the original data. In the present
study we tested the possibility of a correlation between GIDI and parameters
such as CFU of streptococci of the mutans group and number of teeth with
caries (lesions present). We first tested the correlation between IgA concentrations
in saliva and dmft/DMFT indices and number of CFU of streptococci of the
mutans group for all 135 children. The statistical tests performed revealed
a complete absence of correlation between these parameters and IgA level,
with a correlation coefficient of 0.2191, i.e., corresponding to a 5.88%
probability for the hypothesis of equality. When correlation with dmft
was tested, the coefficient obtained was 0.0107, i.e., corresponding to
a 90.66% probability for the hypothesis of equality. The correlation coefficient
with respect to DMFT was 0.0992, i.e., corresponding to a 25.28% probability
for the hypothesis of equality. The correlation coefficient with respect
to number of CFU of the mutans group was 0.0992, i.e., corresponding to
a probability of 25.28% for the hypothesis of equality. The lack of statistical
significance for the calculated r values for the dmft and DMFT indices
led us to conclude that there is no relationship between salivary IgA levels
and these conventional indices. Indeed, an objective evaluation of the
results leads to the following question: what is the role of teeth lost
or exfoliated in the past or of the number of teeth with previous fillings
in the production of IgA, which is always a current response to an inflammatory
reaction? On this basis, we decided to use only the number of teeth with
caries, i.e., with current lesions, a fact that, in addition to solving
the above problem, also offered a standardization of the parameter, since
most of the children sampled were in the phase of mixed dentition, with
the consequent need to utilize the dmft and DMFT, while exfoliated teeth
are known not to be representative of active caries. However, the present
comparison between number of teeth with caries with GIDI rather than with
dmft or DMFT, and not simply with IgA level continued to show a lack of
significant correlation between them since the regression and correlation
tests performed between GIDI and number of teeth with caries yielded r
= -0.0133 (non-significant) with a p(HO) = 87.86%. The same lack of significance
was obtained when the correlation between GIDI and number of CFU of streptococci
of the mutans group was tested, with r = 0.0370 and p(HO) = 67.60%. These
findings indicate that the simple presence of caries or of CFU of streptococci
of the mutans group in the oral cavity is not sufficient to stimulate IgA
production and/or secretion. For this to occur, the caries should be biologically
active, i.e., they should be acting unfavorably on gingival health, provoking
gingival inflammation. Only then will an antigenic stimulus occur for the
production and secretion of IgA at levels sufficient to bring about a possible
reversal of the clinical picture. These tests simply confirmed the impression
we already had that the influence of caries, of bacterial colonies and
even of poorly executed fillings on GIDI would be simply indirect and would
only manifest when these elements act as direct agents of gingival inflammation
due to excessive plaque accumulation and to the action of irregular tooth
borders (caused by caries or by defective filling borders).
References
Camling E, Köhler B: Infection with the bacterium Streptococcus and
salivary IgA antibodies in mothers and their children. Arch Oral Biol 32:
817-823, 1987
Camling E, Gahnberg L, Krasse B: The relationship between IgA antibodies
to Streptococcus mutans antigens in human saliva and breast milk and the
numbers of indigenous oral Streptococcus mutans. Arch Oral Biol 32: 21-25,
1987
Davey AL, Rogers AH: Multiple types of the bacterium Streptococcus mutans
in the human mouth and their intra-family transmission. Arch Oral Biol
29: 453-460, 1984
Gråhn E, Tenovuo J, Lehtonen O-P, Eerola E, Vilja P: Antimicrobial
systems of human whole saliva in relation to dental caries, cariogenic
bacteria, and gingival inflammation in young adults. Acta Odont Scand 46:
67-74, 1988
Reinholdt J, Kilian M: Interference of IgA protease with the effect
of secretory IgA on adherence of oral streptococci to saliva-coated hydroxyapatite.
J Dent Res 66: 492-497, 1987
Riviere GR, Papagiannoulis L: Antibodies to indigenous and loboratory
strain of Streptococcus mutans in saliva from children with dental caries
and from caries-free children. Pediat Dent 216-220, 1987
Souza-Gugelmin MCM, Ito IY, Maia Campos G: Study of the correlation
between salivary IgA and gingival inflammation in children. Bras Dent J
4: 91-96, 1993
Souza-Gugelmin MCM, Ito IY, Maia Campos G: Creation of a new index to
evaluate the immunological potential of the gingiva and the possible risk
for periodontal disease, the Gingival Immunologic Defense Index (GIDI).
Braz Dent J 6: 95-102, 1995
Correspondence: Maria Cristina Monteiro de Souza-Gugelmin, Faculdade
de Ciências Farmacêuticas de Ribeirão Preto, USP, 14040-903
Ribeirão Preto, SP, Brasil.
Accepted April 8, 1996
Electronic publication: February, 1997
BACK TO CONTENTS