339
Estimation of Dental Plaque Levels and Gingival Inflammation Using a Simple Oral Rinse Technique Haim Tal* and Mel
Rosenberg?
A simple, non-invasive test (the Oratest) has recently been proposed, which provides an estimate of oral microbial levels based on the rate of oxygen depletion in expectorated milk samples. Following 30 seconds of vigorous rinsing with sterilized milk, 3 ml of the expectorate is added to a test tube containing the redox indicator, méthylène blue, and the time required for a color change from blue (i.e., aerobic conditions) to white (anaerobic conditions) at the bottom of the test tube is recorded. In the present study, Oratest scores were compared to clinical parameters (Plaque Index [PI] and Gingival Index [GI]) in a group of 49 volunteers. Significant correlations were found between the logarithm of Oratest results and PI (r= -0.58; 0.001) as well as GI (r= -0.66; 0.001). The data indicate that the Oratest provides a reliable estimate of gingival inflammation, thus extending the previously reported strong correlations between Oratest scores and microbial counts. The data suggest that the Oratest may have potential as a clinical and research tool. / Periodontol 1990; 61:339-342. =
=
Key Words: Plaque index; gingival index; Oratest; mouth/microbiology; gingivitis.
large body of evidence supports the hypothesis that microorganisms present in dental plaque constitute the primary etiological factor in periodontal diseases.1-3 It has similarly been established that dental plaque accumulation induces and promotes gingivitis.4 Prior to the 1970s, periodontal A
ascribed to the overall increase in microorganisms, concept referred to as the "non-specific plaque hypothesis."5 More recently, specific groups of bacteria were found to be associated with particular periodontal ailments, leading to the "specific plaque hypothesis."5 In 1985, Moore et al.6 reported that periodontal diseases are associated with elevated levels of at least 57 bacterial species. The observation that many suspected periodontal pathogens require or prefer anaerobic growth conditions has led to speculation that oxygen depletion by aerobic plaque microorganisms is a prerequisite for the development and progression of periodontal diseases.7 Recently, Rosenberg and coworkers7 reported a simple, non-invasive technique (the Oratest^) which estimates oral microbial levels, based on the rate of oxygen depletion in expectorated milk samples. The test is performed by rinsing the mouth with sterilized milk. A sample of the expectorate diseases
were a
is then added to a test tube containing the redox indicator, méthylène blue. The time required for anaerobic conditions to be attained at the bottom of the tube, as indicated by a blue-to-white color change, is recorded. In a previous investigation, strong correlations were observed between Oratest scores and counts of aerobic and aerotolerant microorganisms.7 The present study was undertaken to compare Oratest scores with commonly used techniques for clinical evaluation of plaque levels and gingival inflammation. MATERIALS AND METHODS Forty-nine volunteers (mean age 42.7 years) participated in the study. The plaque level of each volunteer was scored using the Plaque Index (PI) described by Quigley and Hein:8 0 no visible plaque; 1 isolated flecks of stain at gingival margin; 2 continuous definite line of plaque at gingival margin; 3 gingival third surface covered by plaque; 4 more than 2/3 of surface covered by plaque; and 5 2/3 of surface covered by plaque. The severity of gingivitis was assessed using the GI system of Löe and Silness:9 0 clinically normal, pink color, no edema or altered contour; 1 mild inflammation, slight change in color (erythema) moderate inflammation, and little change in texture; 2 moderate glazing, redness, edema, and enlargement, bleeding on pressure with a blunt instrument; and 3 severe inflammation, marked redness and enlargement, tendency for spontaneous bleeding. The Oratest has been previously described.7 Briefly, vol=
=
=
=
=
=
=
=
=
"Section of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. Laboratory of Oral Microbiology, The Maurice and Gabriela Goldschleger School of Dental Medicine and Department of Human Microbiology, Sackler Faculty of Medicine. Agis, Ltd., Tel Aviv, Israel.
=
340
J Periodontol June 1990
PLAQUE AND GINGIVITIS ASSESSED BY AN OXYGEN DEPLETION TEST
1000
on
Figure 1: The Oratesi The bottom of the test tubes, prior to (left) following (right) the blue-to-white color change. Table 1.
Relationship
between Oratest Results* and Number
Population
49 30 19
All volunteers Did not eat or drink*
Did eat
or
drink*
"Logarithm of time (minutes) bottom of test tube. 90 minutes prior to test.
required
Correlation Coefficient r
=
r
=
r
=
-0.58 -0.64 -0.48
Plaque
100 +
and
Index
Significance = =
=
for blue-to-white color
0.001 0.001 0.019
change
at
vigorously with 10 ml of ultrahigh-temperature sterilized cow's milk containing 3% butunteers rinsed their mouths
PLAQUE INDEX Figure 2: Correlation between Oratest results and Plaque Index. The time required for color change is plotted on a logarithmic scale as a function of the Plaque Index for the 30 volunteers who refrained from drinking or eating within 90 minutes prior to testing.
terfat§ for 30 seconds. The expectorate
was collected into small cup and 3 ml immediately transferred to a disposable polystyrene test tube containing 0.12 ml of a 0.1% aqueous solution of méthylène blue. The test tube was capped, mixed briefly, and allowed to stand over a mirror at room temperature. The time required for a color change from blue to white within a 6 mm diameter circle on the bottom of the test tube was recorded (Fig. 1). Pearson correlations between clinical parameters (PI and GI) and Oratest (i.e., the logarithm [base 10] of time required for the color change) were calculated. Spearman rank correlation analysis was also performed. Despite the ordinal nature of the clinical scores, both methods of analysis yielded essentially the same results.
1000
a
RESULTS A comparison of Oratest and PI indicated that the two parameters are related (i.e., in general, the higher the Oratest scores, the lower the PI). Results are summarized in Table 1 and Figure 2. When all 49 volunteers were grouped together, linear regression analysis of the logarithm of time required for color change, as a function of PI, yielded a correlation coefficient of -0.58 (P 0.001). When the 19 volunteers who ate or drank within 90 minutes prior to the test were excluded (Fig. 2), the correlation coefficient rose to -0.64 (P 0.001); the correlation coefficient of those who ate or drank within 90 minutes prior to the test was only -0.48 (P 0.019). As summarized in Figure 3 and Table 2, significant correlations (P 0.001) were also observed between the log=
=
=
=
G.I. Figure 3: Correlation between Oratest results and Gingival Index. The time required for the color change is plotted on a logarithmic scale as a function of the Gingival Index for all 49 volunteers. arithm of Oratest
scores
and GI values. These correlations
equivalent, whether or not the 19 volunteers who ate or drank within 90 minutes prior to the test were included -0.66, and -0.65 respectively). The correlation (r
were
=
coefficient obtained with those who ate or drank within 90 minutes of the test was -0.71 [P 0.001). Overall, Oratest scores varied greatly, from 17 to 585 =
äTnuva Ltd., Rehovot,
Israel.
Volume 61 Number 6 Table 2.
TAL, ROSENBERG
Relationship
Between Oratest Result* and
Population
Number
All volunteers Did not eat or drink1" Did eat or drink1
49 30 19
Logarithm of time (minutes) bottom of test tube. '90 minutes prior to test.
required
Correlation Coefficient r
=
r
=
r
=
-0.66 -0.65 -0.71
Gingival
Index
Significance =
=
=
for blue-to-white color
0.001 0.001 0.001
change
at
of 178 minutes. The correlation between the logarithm of Oratest scores and increasing age of volunteers (r 0.34; 0.009) was weaker than with either clinical parameter.
minutes, with
a mean
=
=
-
DISCUSSION The growing interest in the microbiological aspects of periodontal diseases has led to the development of a variety of diagnostic approaches. Investigations have suggested relationships between the presence or level of certain microorganisms and evidence of periodontal diseases;10 others have proposed to detect microbial products, such as proteolytic enzymes, or DNA.12 Unfortunately, many of these approaches require extensive work-up time and additional equipment, including incubators and microscopes for morphological counts;10 often samples must be sent out for analysis. Simple, inexpensive techniques which do not demand sophisticated skills or consume costly "chair" time, are required in order to expedite the diagnosis and appropriate management of periodontal diseases. In a previous study, the Oratest was shown to be a simple, rapid technique for estimating oral microbial levels.7 In the present study, the potential of the Oratest as a clinical diagnostic tool was examined. Consequently, correlations were sought between Oratest scores and commonly used clinical parameters (PI and GI). In both instances, significant (P 0.001) overall correlations were observed beOratest data and both PI and GI. Clearly, the subjective tween and GI measurements themselves may have of PI nature contributed to the somewhat weaker correlations observed here, as compared to the extremely strong correlations observed between Oratest scores and microbial counts.7 In order to further establish the clinical significance of this technique in detecting progression of Periodontitis, longitudinal studies comparing Oratest scores with loss of gingival attachment are required. In addition, the finding that the correlations are slightly altered by drinking or eating prior to the test warrants further investigation. The data of the present study suggest that volunteers with high plaque levels almost invariably yield relatively rapid color changes in the Oratest. Thus, as can be observed in the upper right quadrant of Figure 2, not one of the volunteers with PI scores above 2 yielded color changes of longer duration than 120 minutes. Thus, Oratest scores of 2 hours or more may largely rule out the possibility of high plaque scores. On the other hand, Oratest scores of less
341
than 2 hours may not necessarily indicate high plaque scores. Such "false positives" (i.e., suggesting a high oral microbial level, despite a low PI) may result from heavy colonization of buccal or tongue surfaces. Such conditions may predispose to other oral ailments, such as halitosis.13 Moreover, soft oral surfaces may harbor periodontal pathogens.14 In a separate study it was shown that baseline Oratest scores are significantly lengthened following the use of antibacterial mouthrinse.15 Thus, one may speculate that patients exhibiting rapid Oratest color change, in spite of proper dental hygiene, are those who would benefit most from additional mouthrinse regimens. The Oratest is based on whole mouth rinsing with sterile milk. We have previously proposed that milk is a suitable liquid for dislodging oral microorganisms mildly, yet effectively, while providing an excellent medium for subsequent metabolism.7 Although whole mouth tests such as the Oratest do not identify the source of oral microorganisms, their relative simplicity and non-invasive nature make them potentially suitable for clinical use. Moreover, since whole mouth treatment regimens are routinely employed, whole mouth diagnostic tests may provide more relevant data than site-specific sampling techniques. Other potential advantages of the Oratest are: 1) it can be rapidly performed by auxiliary personnel; 2) positive results are easily visualized by both practitioner and patient; and 3) no special instrumentation is required. Recent reports have suggested that the Oratest can serve as a simple, convenient technique to estimate oral microbial levels,7 and to monitor mouthrinse regimens.15 The present study extends these previous correlations to include two commonly used clinical parameters, PI and GI. Studies are underway to test the ability of the Oratest to provide a baseline with which subsequent changes in clinical status and oral hygiene (e.g., following scaling and instruction) can be monitored in a chairside, or even home, environment.
=
Acknowledgments discussions,
to P. Birek and M. Arkin for valuable to I. Gelernter for statistical consultations, and
to R. Lazar
for editorial assistance.
We
are
grateful
REFERENCES 1. Ellison SA. Oral bacteria in
1970;49(Suppl. 2):198.
periodontal
disease. J Dent Res
2. Genco RJ, Evans RT, Ellison SA. Dental research in microbiology with emphasis on periodontal disease. J Am Dent Assoc 1969;78:1016. 3. Socransky SS. Relationship of bacteria to the etiology of periodontal disease. / Dent Res 1970;49 (Suppl. 2):203. 4. Schluger S, Yuodelis RH, Page R. Periodontal Disease. Philadelphia: Lea & Febiger; 1977:82. 5. Loesche WJ. Chemotherapy of dental plaque infections. Oral Sei Res
1976;9:65.
6. Moore WE, Holdeman LV, Cato EP, et al. Comparative bacteriology of juvenile Periodontitis. Infect Immun 1985;48:507. 7. Rosenberg M, Bárki M, Portnoy S. A simple method for estimating oral microbial levels. J Microbiol Methods 1989;9:253.
342
8.
PLAQUE AND GINGIVITIS ASSESSED
J Periodontol June 1990
BY AN OXYGEN DEPLETION TEST
Quigley GA, Hein JW. Comparative cleansing efficiency and power brushing. J Am Dent Assoc 1962;65:26.
of manual
9. Löe H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odont Scan 1963;21:533. 10. Greenstein G. Microbiologie assessments to enhance periodontal diagnosis. / Periodontol 1988;59:508. 11. Breta WA, Loesche WJ. Characteristics of trypsin-like activity in subgingival plaque samples. J Dent Res 1987;66, 1668. 12. French CK, Savitt ED, Siomon SL, et al. DNA probe detection of periodontal pathogens. Oral Microbio! and Immunol 1986;1:58. 13. van der Veiden U, Kippuw N, Petit M, Van Winkelhoff AJ, DeGraeff
J. Localization of microorganisms on the tongue and the effect of cleaning. J Dent Res 1989;68:1007. 14. Tonzetich J. Production and origin of oral malodor: A review of mechanisms and methods of analysis. J Periodontol 1977;48:13. 15. Rosenberg M, Barki M, Goldberg S. The antimicrobial effect of mouthrinsing as measured using the Oratest. "J Dent Res 1989;68:661. "
Send reprint requests to: Dr. Haim Tal, Chairman, Section of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel. Accepted for publication November 27, 1989.
Estimation of Dental Plaque Levels and Gingival Inflammation Using a Simple Oral Rinse Technique Haim Tal* and Mel
Rosenberg?
A simple, non-invasive test (the Oratest) has recently been proposed, which provides an estimate of oral microbial levels based on the rate of oxygen depletion in expectorated milk samples. Following 30 seconds of vigorous rinsing with sterilized milk, 3 ml of the expectorate is added to a test tube containing the redox indicator, méthylène blue, and the time required for a color change from blue (i.e., aerobic conditions) to white (anaerobic conditions) at the bottom of the test tube is recorded. In the present study, Oratest scores were compared to clinical parameters (Plaque Index [PI] and Gingival Index [GI]) in a group of 49 volunteers. Significant correlations were found between the logarithm of Oratest results and PI (r= -0.58; 0.001) as well as GI (r= -0.66; 0.001). The data indicate that the Oratest provides a reliable estimate of gingival inflammation, thus extending the previously reported strong correlations between Oratest scores and microbial counts. The data suggest that the Oratest may have potential as a clinical and research tool. / Periodontol 1990; 61:339-342. =
=
Key Words: Plaque index; gingival index; Oratest; mouth/microbiology; gingivitis.
large body of evidence supports the hypothesis that microorganisms present in dental plaque constitute the primary etiological factor in periodontal diseases.1-3 It has similarly been established that dental plaque accumulation induces and promotes gingivitis.4 Prior to the 1970s, periodontal A
ascribed to the overall increase in microorganisms, concept referred to as the "non-specific plaque hypothesis."5 More recently, specific groups of bacteria were found to be associated with particular periodontal ailments, leading to the "specific plaque hypothesis."5 In 1985, Moore et al.6 reported that periodontal diseases are associated with elevated levels of at least 57 bacterial species. The observation that many suspected periodontal pathogens require or prefer anaerobic growth conditions has led to speculation that oxygen depletion by aerobic plaque microorganisms is a prerequisite for the development and progression of periodontal diseases.7 Recently, Rosenberg and coworkers7 reported a simple, non-invasive technique (the Oratest^) which estimates oral microbial levels, based on the rate of oxygen depletion in expectorated milk samples. The test is performed by rinsing the mouth with sterilized milk. A sample of the expectorate diseases
were a
is then added to a test tube containing the redox indicator, méthylène blue. The time required for anaerobic conditions to be attained at the bottom of the tube, as indicated by a blue-to-white color change, is recorded. In a previous investigation, strong correlations were observed between Oratest scores and counts of aerobic and aerotolerant microorganisms.7 The present study was undertaken to compare Oratest scores with commonly used techniques for clinical evaluation of plaque levels and gingival inflammation. MATERIALS AND METHODS Forty-nine volunteers (mean age 42.7 years) participated in the study. The plaque level of each volunteer was scored using the Plaque Index (PI) described by Quigley and Hein:8 0 no visible plaque; 1 isolated flecks of stain at gingival margin; 2 continuous definite line of plaque at gingival margin; 3 gingival third surface covered by plaque; 4 more than 2/3 of surface covered by plaque; and 5 2/3 of surface covered by plaque. The severity of gingivitis was assessed using the GI system of Löe and Silness:9 0 clinically normal, pink color, no edema or altered contour; 1 mild inflammation, slight change in color (erythema) moderate inflammation, and little change in texture; 2 moderate glazing, redness, edema, and enlargement, bleeding on pressure with a blunt instrument; and 3 severe inflammation, marked redness and enlargement, tendency for spontaneous bleeding. The Oratest has been previously described.7 Briefly, vol=
=
=
=
=
=
=
=
=
"Section of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. Laboratory of Oral Microbiology, The Maurice and Gabriela Goldschleger School of Dental Medicine and Department of Human Microbiology, Sackler Faculty of Medicine. Agis, Ltd., Tel Aviv, Israel.
=
340
J Periodontol June 1990
PLAQUE AND GINGIVITIS ASSESSED BY AN OXYGEN DEPLETION TEST
1000
on
Figure 1: The Oratesi The bottom of the test tubes, prior to (left) following (right) the blue-to-white color change. Table 1.
Relationship
between Oratest Results* and Number
Population
49 30 19
All volunteers Did not eat or drink*
Did eat
or
drink*
"Logarithm of time (minutes) bottom of test tube. 90 minutes prior to test.
required
Correlation Coefficient r
=
r
=
r
=
-0.58 -0.64 -0.48
Plaque
100 +
and
Index
Significance = =
=
for blue-to-white color
0.001 0.001 0.019
change
at
vigorously with 10 ml of ultrahigh-temperature sterilized cow's milk containing 3% butunteers rinsed their mouths
PLAQUE INDEX Figure 2: Correlation between Oratest results and Plaque Index. The time required for color change is plotted on a logarithmic scale as a function of the Plaque Index for the 30 volunteers who refrained from drinking or eating within 90 minutes prior to testing.
terfat§ for 30 seconds. The expectorate
was collected into small cup and 3 ml immediately transferred to a disposable polystyrene test tube containing 0.12 ml of a 0.1% aqueous solution of méthylène blue. The test tube was capped, mixed briefly, and allowed to stand over a mirror at room temperature. The time required for a color change from blue to white within a 6 mm diameter circle on the bottom of the test tube was recorded (Fig. 1). Pearson correlations between clinical parameters (PI and GI) and Oratest (i.e., the logarithm [base 10] of time required for the color change) were calculated. Spearman rank correlation analysis was also performed. Despite the ordinal nature of the clinical scores, both methods of analysis yielded essentially the same results.
1000
a
RESULTS A comparison of Oratest and PI indicated that the two parameters are related (i.e., in general, the higher the Oratest scores, the lower the PI). Results are summarized in Table 1 and Figure 2. When all 49 volunteers were grouped together, linear regression analysis of the logarithm of time required for color change, as a function of PI, yielded a correlation coefficient of -0.58 (P 0.001). When the 19 volunteers who ate or drank within 90 minutes prior to the test were excluded (Fig. 2), the correlation coefficient rose to -0.64 (P 0.001); the correlation coefficient of those who ate or drank within 90 minutes prior to the test was only -0.48 (P 0.019). As summarized in Figure 3 and Table 2, significant correlations (P 0.001) were also observed between the log=
=
=
=
G.I. Figure 3: Correlation between Oratest results and Gingival Index. The time required for the color change is plotted on a logarithmic scale as a function of the Gingival Index for all 49 volunteers. arithm of Oratest
scores
and GI values. These correlations
equivalent, whether or not the 19 volunteers who ate or drank within 90 minutes prior to the test were included -0.66, and -0.65 respectively). The correlation (r
were
=
coefficient obtained with those who ate or drank within 90 minutes of the test was -0.71 [P 0.001). Overall, Oratest scores varied greatly, from 17 to 585 =
äTnuva Ltd., Rehovot,
Israel.
Volume 61 Number 6 Table 2.
TAL, ROSENBERG
Relationship
Between Oratest Result* and
Population
Number
All volunteers Did not eat or drink1" Did eat or drink1
49 30 19
Logarithm of time (minutes) bottom of test tube. '90 minutes prior to test.
required
Correlation Coefficient r
=
r
=
r
=
-0.66 -0.65 -0.71
Gingival
Index
Significance =
=
=
for blue-to-white color
0.001 0.001 0.001
change
at
of 178 minutes. The correlation between the logarithm of Oratest scores and increasing age of volunteers (r 0.34; 0.009) was weaker than with either clinical parameter.
minutes, with
a mean
=
=
-
DISCUSSION The growing interest in the microbiological aspects of periodontal diseases has led to the development of a variety of diagnostic approaches. Investigations have suggested relationships between the presence or level of certain microorganisms and evidence of periodontal diseases;10 others have proposed to detect microbial products, such as proteolytic enzymes, or DNA.12 Unfortunately, many of these approaches require extensive work-up time and additional equipment, including incubators and microscopes for morphological counts;10 often samples must be sent out for analysis. Simple, inexpensive techniques which do not demand sophisticated skills or consume costly "chair" time, are required in order to expedite the diagnosis and appropriate management of periodontal diseases. In a previous study, the Oratest was shown to be a simple, rapid technique for estimating oral microbial levels.7 In the present study, the potential of the Oratest as a clinical diagnostic tool was examined. Consequently, correlations were sought between Oratest scores and commonly used clinical parameters (PI and GI). In both instances, significant (P 0.001) overall correlations were observed beOratest data and both PI and GI. Clearly, the subjective tween and GI measurements themselves may have of PI nature contributed to the somewhat weaker correlations observed here, as compared to the extremely strong correlations observed between Oratest scores and microbial counts.7 In order to further establish the clinical significance of this technique in detecting progression of Periodontitis, longitudinal studies comparing Oratest scores with loss of gingival attachment are required. In addition, the finding that the correlations are slightly altered by drinking or eating prior to the test warrants further investigation. The data of the present study suggest that volunteers with high plaque levels almost invariably yield relatively rapid color changes in the Oratest. Thus, as can be observed in the upper right quadrant of Figure 2, not one of the volunteers with PI scores above 2 yielded color changes of longer duration than 120 minutes. Thus, Oratest scores of 2 hours or more may largely rule out the possibility of high plaque scores. On the other hand, Oratest scores of less
341
than 2 hours may not necessarily indicate high plaque scores. Such "false positives" (i.e., suggesting a high oral microbial level, despite a low PI) may result from heavy colonization of buccal or tongue surfaces. Such conditions may predispose to other oral ailments, such as halitosis.13 Moreover, soft oral surfaces may harbor periodontal pathogens.14 In a separate study it was shown that baseline Oratest scores are significantly lengthened following the use of antibacterial mouthrinse.15 Thus, one may speculate that patients exhibiting rapid Oratest color change, in spite of proper dental hygiene, are those who would benefit most from additional mouthrinse regimens. The Oratest is based on whole mouth rinsing with sterile milk. We have previously proposed that milk is a suitable liquid for dislodging oral microorganisms mildly, yet effectively, while providing an excellent medium for subsequent metabolism.7 Although whole mouth tests such as the Oratest do not identify the source of oral microorganisms, their relative simplicity and non-invasive nature make them potentially suitable for clinical use. Moreover, since whole mouth treatment regimens are routinely employed, whole mouth diagnostic tests may provide more relevant data than site-specific sampling techniques. Other potential advantages of the Oratest are: 1) it can be rapidly performed by auxiliary personnel; 2) positive results are easily visualized by both practitioner and patient; and 3) no special instrumentation is required. Recent reports have suggested that the Oratest can serve as a simple, convenient technique to estimate oral microbial levels,7 and to monitor mouthrinse regimens.15 The present study extends these previous correlations to include two commonly used clinical parameters, PI and GI. Studies are underway to test the ability of the Oratest to provide a baseline with which subsequent changes in clinical status and oral hygiene (e.g., following scaling and instruction) can be monitored in a chairside, or even home, environment.
=
Acknowledgments discussions,
to P. Birek and M. Arkin for valuable to I. Gelernter for statistical consultations, and
to R. Lazar
for editorial assistance.
We
are
grateful
REFERENCES 1. Ellison SA. Oral bacteria in
1970;49(Suppl. 2):198.
periodontal
disease. J Dent Res
2. Genco RJ, Evans RT, Ellison SA. Dental research in microbiology with emphasis on periodontal disease. J Am Dent Assoc 1969;78:1016. 3. Socransky SS. Relationship of bacteria to the etiology of periodontal disease. / Dent Res 1970;49 (Suppl. 2):203. 4. Schluger S, Yuodelis RH, Page R. Periodontal Disease. Philadelphia: Lea & Febiger; 1977:82. 5. Loesche WJ. Chemotherapy of dental plaque infections. Oral Sei Res
1976;9:65.
6. Moore WE, Holdeman LV, Cato EP, et al. Comparative bacteriology of juvenile Periodontitis. Infect Immun 1985;48:507. 7. Rosenberg M, Bárki M, Portnoy S. A simple method for estimating oral microbial levels. J Microbiol Methods 1989;9:253.
342
8.
PLAQUE AND GINGIVITIS ASSESSED
J Periodontol June 1990
BY AN OXYGEN DEPLETION TEST
Quigley GA, Hein JW. Comparative cleansing efficiency and power brushing. J Am Dent Assoc 1962;65:26.
of manual
9. Löe H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odont Scan 1963;21:533. 10. Greenstein G. Microbiologie assessments to enhance periodontal diagnosis. / Periodontol 1988;59:508. 11. Breta WA, Loesche WJ. Characteristics of trypsin-like activity in subgingival plaque samples. J Dent Res 1987;66, 1668. 12. French CK, Savitt ED, Siomon SL, et al. DNA probe detection of periodontal pathogens. Oral Microbio! and Immunol 1986;1:58. 13. van der Veiden U, Kippuw N, Petit M, Van Winkelhoff AJ, DeGraeff
J. Localization of microorganisms on the tongue and the effect of cleaning. J Dent Res 1989;68:1007. 14. Tonzetich J. Production and origin of oral malodor: A review of mechanisms and methods of analysis. J Periodontol 1977;48:13. 15. Rosenberg M, Barki M, Goldberg S. The antimicrobial effect of mouthrinsing as measured using the Oratest. "J Dent Res 1989;68:661. "
Send reprint requests to: Dr. Haim Tal, Chairman, Section of Periodontology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel. Accepted for publication November 27, 1989.
