An epidemiological study of chronic periodontal disease

Ad.

md Bid.

AN

Vul.lO, pp.553-566,

1965. Pergamon PressLtd. Printed in Ct. Britain.

EPIDEMIOLOGICAL PERIODONTAL

Departments

STUDY OF DISEASE

CHRONIC

B. LILIENTHAL, V. AMERENA and G. GREGORY of Bacteriology and Statistics, University of Melbourne, Australia

Summary-The characteristics of chronic gingivitis and chronic periodontitis were studied in a group of 854 subjects in Melbourne. Analysis of the data indicated that: (i) for males and females aged 5-9 years the oral debris only influenced the Russell periodontal index; (ii) up to the age of 20 years for females and 24 years for males both oral debris and calculus strongly influenced the periodontal index and (iii) in the older age-groups only calculus affected the periodontal index. An analysis of the significance between sites of oral debris on one age-group (20-24 years) showed that : (i) less debris was present on the anterior region than on the teeth in the posterior regions, (ii) the buccal or labial sites were cleaner than the lingual sites, (iii) the maxillary sites had significantly less debris than the mandibular sites and (iv) a bilateral symmetry of distribution of debris was evident. Among the 600 individuals for whom tooth brushing frequency was recorded, the periodontal index was influenced significantly by age, brushing frequency and the presence of pockets. Education, sex, smoking habits, occupation, race and skin colour did not exert a significant effect on the periodontal index. INTRODUCTION ONLY a few reports

have been published on the prevalence of periodontal disease in Australia. CAMPBELL (1937) and CRAN (1955) examined Australian aborigines and found 50 per cent of them had periodontal disease whilst MOODY (1949) reported a universal generalized gingival hyperplasia among 1557 aborigines in Arnhem Land. In the European population CLEMENTSand KIRKPATRICK (1939) noted that 63 per cent of 530 pre-school and school children had gingivitis whereas SHANNON (1949) reported a prevalence of gingivitis of only 14 per cent in a comparable group of 550 children. These variations appear to be due to the different diagnostic criteria employed by these investigators. Tn Queensland, KRUGER (1955) used the P.M.A. index to examine 1126 children aged between 3 and 13 years. He found the prevalence of gingivitis to be 57 per cent (4.6 P.M.A. units) in the 3-5 year-old group, 85 per cent (8.3 P.M.A. units) in the 6-8 year-old group and 87.6 per cent (13.2 P.M.A. units) in the 12-13 year-old group. Russell’s periodontal index was used first in Australia by LILIENTHAL and LEVINE (personal communication, 1958) on approximately 500 subjects in Sydney. However, this index has not been used previously in a broad epidemiological investigation in this country. The object of the survey was to obtain information on the prevalence of chronic periodontal disease in the city of Melbourne (Australia) and to examine the possible 553

554

B. LILIENT~AL, V. AMERENA AM)G. GREGORY

relation of social, economic, educational and other factors to the aetiology of the disease. METHODS Sample studied The examinations were carried out in a suburban general practice in Melbourne so situated that the patients examined were drawn from the lower, middle and upper income groups ofthe surrounding suburbs. However, approximately one-third of all the subjects examined were from other suburbs of the city. The examinations were made over a 2-year period and included only individuals who voluntarily attended the dental surgery. Collection of data A survey form was used for the compilation of information obtained from each patient. The following data were recorded : sex, age, place of birth, occupation, educational status, smoking habits, skin colour and toothbrushing frequency. Individuals were grouped into seven age groups, i.e. 5-9 years, lo-14 years to 55 years and over. Because of the recent immigration of numerous people to Australia from Europe and the Mediterranean countries the place of birth was recorded as an indication of racial type. Only two “racial” groupings were employed; (1) British and European and (2) Mediterranean and Asian. The Asian group was relatively small in number. The International Standard Classification of Occupations (Ninth International Conference of Labour Statisticians, 1957) was used to classify occupation and to simplify the statistical analysis, Subjects were grouped into only two classes; (1) farmers, transport workers, tradesmen and housewives and (2) professional men and women, clerks and students. The occupation of a full-time student or housewife was recorded as that of the father or husband respectively. Occupation was used as a guide to the economic status of an individual or of a family. Only a qualitative assessment of smoking was made i.e., whether a person smoked regularly or not. Three classes of skin colour were used as a guide to genetic type i.e., very fair, fair and olive. Toothbrushing was classified on the reply to the simple question “How many times each day do you clean your teeth?” The classification was less than once a day, once a day, twice a day and more than twice a day. Educational status was assessed from the number of years of full-time education received. Three divisions of educational status were used which corresponded to primary (less than 9 years), secondary (9-12 years) and tertiary education (more than 12 years). Evaluation of periodontal disease RUSSELL’S(1956) method of scoring periodontal disease was used because of its simplicity, ease of application and amenability of results to statistical treatment. Each patient was examined in the dental chair using non-colour-corrected artificial light, a mouth mirror (plane No. 5), chip air syringe to remove saliva and a periodontal probe (Fox No. 3). The examinations were made systematically and each erupted

AN

EPIDEMIOLOGICAL

STUDY

OF CHRONIC

PERIODONTAL

DISEASE

555

tooth (primary and permanent) was inspected and the gingival score recorded. These examinations were made by one of us (V.A.) who had received prior training and standardization in the scoring procedures. It was found impossible to compensate for a “learning effect”, if any occurred during the study. Oral hygiene index

Oral debris and calculus were scored by the methods of GREENEand VERMILLION (1960). The oral hygiene index is the addition of the values for debris and calculus. GREENEand VERMILLIONexcluded primary and third molar teeth because of their variable crown formation. In this study all teeth present were scored as they had already been assessed for periodontal involvement. Statistical analyses

Several analyses were carried out involving varied groupings of factors. The first of these examined the relation between RUSSELL’Speriodontal index, oral debris, calculus, age and sex. The second analysis examined for any significant difference between sites of oral debris. A third analysis included the factors of age, sex, presence of one or more periodontal pockets, frequency of toothbrushing, smoking, occupation, education, skin colour and periodontal index.

RESULTS The relationship between periodontal index, oral debris index and calculus index

The observed values for periodontal index, oral debris index, calculus index and oral hygiene index among 854 subjects are listed in Table 1 and subdivided into groups by age and sex. The combined scores for both sexes are shown in Table 2. Separate regression relationships were computed for all groups with adequate numbers to determine how the periodontal index varied with the oral debris index and the calculus index. An overall relationship was not attempted because of the possibility that the periodontal index would vary in its relationship to the other factors with different ages and sexes. In the regression relationship oral debris (x1) and calculus (xJ were designated the independent variables (i.e., it was assumed that they were measured without error) and were to be used to predict the value of the periodontal index (y). An equation of the form y = a+b,x,+b,x, was found to describe this relationship, the co-efficients a, b, and b, being estimated from the data. It was assumed implicitly that a linear relationship expressed the dependence over the range of the data. If the periodontal index y did not depend on either or both of the factors x1 and x2 this would be demonstrated by a non-significant value of the corresponding regression coefficients b, or b,. These coefficients were tested for significance against the residual mean squared error estimated from the data. The results appear in Table 3. The analysis indicated that (i) for males and females aged 5-9 years only oral debris influenced periodontal index, (ii) up to the age of 20 years for females and 24 years for males both oral debris and calculus strongly influenced the periodontal index and (iii) after these ages only calculus affected the periodontal index. However, the results

556

B.LILIENTHAL,V. AMERENAAND

G.GREG~RY

for the groups over 40 years did not indicate significance due partly to the increased variability of the periodontal index and partly to the small size of the samples. The standard error about the regression line is shown in the final column of Table 3. In 95 per cent of cases the periodontal index was within two standard errors of the TABLE 1. PERIODONTAL INDEX,ORAL DEBRIS INDEX,CALCULUS INDEX BY AGE AND SEX 4% (wrs)

Sex

5-9 lo-14 15-19 20-24 25-29 30-34 35-39 4@4l 45419 50-54 55-59 60+

HYGIENE

Number in group

Mean P.I.

Mean O.D.I.

Mean C.I.

Mean O.H.I.

20 26 61 71 75 94 63 85 50 53 53 50 29 32 22 8 14 13 9 12

0.61 0.49 0.78 0.66 0.91 0.95 1.10 1.04 1.16 1.26 1.76 1.64 1.73 1.73 3.20 1.64 3.05 2.59 2.70 2.57 2.64 2.04 244 2.85

0.67 0.45 0.72 0.63 0.79 0.65 0.83 0.74 0.84 0.79 0.88 0.86 0.91 0.81 0.89 0.83 0.88 0.73 0.94 0.87 1XKl 0.70

0.04 0.01 0.90 0.03 0.20 0.20 0.46 0.49 0.61 0.51 1.07 0.89 I.10 0.72 1.36 1.03 1.21 1.26 1.33 1.22 2.00 0.86 1.14 1.23

0.71 0.46 0.81 0.66 0.99 0.85 1.29 1.23 1.45 1.30 1.95 1.75 201 1.53 2.25 1.86 2.09 1.99 2.27 2.09 3.00 1.56 2.18 2.11

M F M F M F M F M F M F M F M F M F M F M F M F

TABLE 2. COMBINED

INDEX,ORAL

VALUES FOR PERIODONTAL INDEX, ORAL DEBRIS INDEX, CALCULUS INDEX,ORALHYGIENEINDEXBYAGE

Age (years>

Number in Group

5-9 lo-14 15-19 20-24 25-29 3fX.34 35-39 40-44 45-49 50-54 55-59 60+

46 132 169 148 103 103 61 30 27 21 8 6

Mean P.I. 0.55 0.72 0.93 1.07 1.21 1.70 I .73 2.42 2.82 2.63 2.34 2.64

Mean O.D.I.

Mean C.I.

Mean O.H.I.

0.56 0.67 @72 0.78 0.81 0.87 0.86 0.86 0.80 0.90 0.85 0.96

0.03 0.06 0.20 0.47 0.56 0.98 0.91 1.19 1.23 I .27 1.43 1.18

0.59 0.73 0.92 1.25 1.37 1.85 1.77 2.05 2.03 2.17 2.28 2.14

AN EPIDEMIOLOoICAL STUDY OF CHRONIC TABLE

3. RELATIONSHIP OF PERIODONTAL

PERIODONTAL

INDEX TO ORAL DEBRIS INDEX AND INDEX

CALCULUS

n = number

a = bI = bz = s.e. (b 1) = s.e. (b,) --

Age 5-9 lo-14 15-19 20-24 25-29 30-34 35-39 40-44 4549 50-54

Sex M F M F M F M F M F M F M F M F M F M F

* Significant t Significant

in group. a constant. regression coefficient for O.D.I. regression coefficient for C.I. standard error of regression coefficient standard error of regression coefficient _----

557

DISEASE

b,

s.e. (b,)

bl

0.4919* 0.556Ot 0.8061 t 0.6734t 0.6282t 0,761Ot 0.7899t 0.0259 0.1338 0.0638 0.7356 1.7780* 2.3201 -0.5591 -0.9225 -0.5277 1.7116 1.2438 1.5382 06458

0.2001 0.1692 0.1496 0.1214 0.1729 0.2334 0.2800 0.2332 0.6887 0.673 1 0.9141 0.8182 14026 0.6380 2.0312 2.3715 2.4342 I .3492 2.4765 3.1451

1.2317 0.2752 0,7187* 04048 0.6680 t 1.0351t 0.6572t 0.5908t 0.9554t 0.87327 1.1429f 1.1301t 1.2703t I.08227 2.4945 t I .5752 I .3696 I .2795 2.1788* I.0129

s.e. (b?) 0.7113 I.1810 0.2265 0.4980 0.1542 0.1996 0.126L 0.1144 0.1872 0.2334 0.2552 0.2230 0.3256 0.2586 0.5572 0.8883 0.7754 0.6167 0.8672 0.6923

for O.D.I. for C.I. ___ a

0.2332 0.2506 0.1559 0.2208 0.2820 0.2358 0.1468 0.7287 0.4657 0.7710 - 0.0886 - 0.9099 - 1.5432 I.1839 0.1355 0.4538 0.1107 0.059 I I .6655 O-7727

Std. error regression

n 20 26 61 71 75 94 63 85 50 53 53 50 29 32 22 8 14 13 9 12

-

0.228 0,227 0.332 0.266 o-413 0.586 0.496 0.516 0.715 0.851 I.109 0.944 0.988 0.710 1441 0.989 I ,492 I.003 I.248 1.388

at 5 per cent level. at 1 per cent level.

value predicted by the regression equation. These standard due to the inherent increase in variability of the periodontal

errors increased with age index with age.

Analysis of sites of oral debris Scores for oral dkbris were divided into four groups for analysis viz: (i) upper and lower, (ii) buccal and lingual, (iii) anterior and posterior and (iv) right and left. An analysis to test for significant differences between these positions was carried out on one age group only (20-24 years), using both male (63) and female (85) patients. A simple “cross-classification” model was used and observations were taken on each individual in each position. The results are summarized in Table 4. The last column (F) gives the value of the ratio of the mean square to the mean square error. This should be close to unity if there is no effect, whilst large values indicate significant effects. The variance ratio test yielded the significant results indicated by asterisks. Only the following significant comparisons were found, (i) the most significant of the “position” effects was that of anterior-posterior, (ii) the buccal-lingual effect was highly significant, (iii) the upper-lower effect was significant at the 5 per cent level and (iv) there was apparently no right-left effect. Further, the anterior, buccal and upper

B. LILIENTHAL,V. AMERENAAND

558

G. GREGORY

TABLE 4. A COMPARISON OF THE DIFFERENCES BETWEENTHE SITESOF ORAL DEBRIS d.f. = degrees of freedom S.S. = sum of the squares M.S. = mean square F. = Ratio of the mean square to the mean square error. (1) Upper, Lower d.f. 142 142 285

S.S. 6.8 661.7 165.2 833.7

M.S. 6.80 4.66 1.16

F 5.86* 4.02t

(2) Buccal, Lingual Between positions Between individuals Error Total

1 142 142 285

112.1 662.0 209.4 983.5

112.10 4.66 1.47

76.26t 3.17t

(3) Anterior, Posterior Between positions Between individuals Error Total

1 142 142 285

1077.1 662.0 206.4 1945.5

1077.10 4.66 1.45

742.83t 3.21t

0.1 320.7 117.9 438.7

0.10 2.26 0.83

0.12 2.72t

Between positions Between individuals Error Total

I

(4) Right, Left Between positions Between individuals Error Total

1 142 142 285 _____ * Significant at 5 per cent level. t Significant at 1 per cent level.

______

-

sites of accumulation were less important than the posterior, lingual and lower sites respectively. The significance of the “between individuals” mean squares merely indicated a difference between the general levels of individuals and was of no interest in this analysis. Age, sex, pockets, brushing frequency, education, smoking, occupation and skin colour and the periodontal index A statistical model was assumed where the effects of the factors listed could be expressed as the addition of constants to a general mean value. The variability in the periodontal index under the same conditions appeared to increase as the mean level of the scores increased. Hence throughout the analysis, the logarithms of the periodontal indices were used and in addition this caused all the effects to be multiplicative on the general mean. Tooth-brushing frequency was recorded for approximately 600 individuals and the nine classifications of these subjects were too many for a complete analysis to be carried out in a single step. Thus the four most important classifications were first selected for analysis and then the remaining classifications were considered sequentially. Within each classification as broad a grading as possible was taken, because

AN EPIDEMIOLOGICAL STUDY OF

CHRONICPERIODONTAL DISEASE

559

too fine a division would only obscure the true effects. The modified classification appears in Table 5. TABLE5. MODIFIEDCLAssrrrCATr0~OF ~NFoRM.~T~ON COLLECTED Classification

No. of groups

Description -~ British and European Mediterranean and Asian

1.

Race

2

2.

Age

6

3.

Sex

Male Female

4.

Pockets

Present Absent

5.

Brushing frequency

2 per

6.

Education

<9 years at school 9-12 years at school > 12 years at school

7.

Smoking

Smoker Non-smoker

8.

Occupation

Farmers, transport, trades, housewives. Professional, clerical, students

9.

Skin colour

Very fair Fair Olive

-

5-14 years 15-24 years 25-34 years 35-44 years 45-54 years 55 + years

day day day day

In the initial analysis the only classifications considered were age, sex, pockets, and tooth-brushing frequency. The method was the standard form (KEMPTHORNE, 1952) for a non-orthogonal design (different numbers in all the cells), with the exception that a linear regression equation was assumed for the relationship with age. The results of the analysis were as follows : (a) Base periodontal index.

index. A value of 0.985 was calculated for the periodontal

(b) Sex efict. The bias consisted of a multiplicative factor of 0.999 for males and of 1.OOl for females. Tested against the error, there was not a significant difference between the sexes. (c) Age effect. The age effect was found to be significant. In the transformed (log) data, a linear regression on age group was fitted, resulting in the following multiplicative factors (Table 6)

B. LILIENTHAL, V. AMERENAAND G. GREGORY

560

TABLE6. MULTIPLICATIVE FACTORSBY AGE Age group (years)

5-14

15-24

25-34

354l

45-54

55+

Multiplicative factor

1.137

1.294

1.472

1.674

I.905

2.167

(d) Brushingfrequency efSect. The effect of frequency of brushing was also significant and the corresponding multiplicative factors are shown in Table 7. TABLE7. MULTIPLICATIVE FACTORS FORFREQUENCY OF TOOTHBRUSHING Brushing frequency (times per day) Multiplicative factor


1

2

>2

1.267

1.064

0.945

0.784

(e) E&et of presence of pockets. The presence of pockets had a marked influence on periodontal index. Table 8 lists the appropriate factors. TABLE8. MULTIPLICATIVE FACTORS FORPRESENCE OFPOCKETS

Multiplicative factor

Pockets

No Pockets

l-549

0645

(f) Example of calculation of P.I. using multiplicative Factors. Thus to calculate the expected periodontal index for an individual (male or female) aged 30, who brushed her/his teeth twice per day and had no pockets, the base periodontal index is multiplied by the factors for age effect, brushing frequency effect and absence of pockets, e.g. Expected periodontal index

Base = periodontal index = 0.985 = 0.884

x

Age factor

x 1.472

x

Brushing factor x

x

0.945

Pocket factor

x 0.645

x

Sex factor

x 1.0

(g) Efict of other factors. For the consideration of further factors the error sum of squares was taken and partitioned by the factor introduced. In other words, considering only the three factors established, the within groups variability was due to error plus the effect of any other factors. If now, taking one of the factors, the groups were divided up by the levels of this new factor, then the new within groups variability would be reduced if the factor was significant. This was in effect treating the model as an hierarchical classification with the analysis of variance: df (degrees of freedom) Between new sub-groups m Within new sub-groups (new error) 598-m Total (previous error) 598 where m = number of new sub-groups introduced.

AN EPIDEMIOLOGICAL STUDY 0~ CHRONIC PERIODONTAL DISEASE

561

The variance was tested for a between new sub-groups effect by the variance ratio test of the mean square against the within new sub-groups mean square. A ratio of approximately 1 (or less) indicated no significance. In fact all the effects tested were not significant as is indicated in Table 9. TABLE 9. VARIANCE RATIO TESTS FOR EDUCATION,SMOKING,OCCUPATION,

RACE AND

SKIN COLOUR ___

_

Education Smoking Occupation Race Skin colour

Between subgroups MS

d.f.

Error M.S.

d.f.

F.

0.058584 0~060418 0.038736 0.057097 0.067583

51 36 35 31 51

0.05867 I 0.05855 I 0.059903 0.058749 0.057832

547 562 563 567 547

1.oo 1.03 0.65 0.97 1.17

DISCUSSION

In this sample of the population of Melbourne, periodontal disease was of greater severity at all ages than had been reported from the United States of America (RUSSELL, 1957). The periodontal disease scores were slightly higher in the younger age groups than those recorded for Ecuador, Vietnam and Lebanon whilst over the age of 50 years the results were similar to those for Ethiopia and Ecuador but much lower than those for Vietnam, Chile, Colombia and Thailand (Table 10). These differences between Australian and American (U.S.A.) data are most likely to be the result of factors other than those of nutrition, diet or economic status because of similarities between the two countries. Probably, such differences represent a greater interest in dental health among Americans than among Australians. Differences between Australian data and data for other countries may be explained by differences in oral hygiene, because variations in diet and nutrition appear to bear no relationship to the prevalence of periodontal disease according to RUSSELL (1963). Although

only

patients

it was felt that the sample Melbourne

presenting studied

voluntarily

at the dental

was a reasonable

surgery

cross-section

in spite of the fact that a rigid population

sampling

were examined,

of the population

technique

of

was not

followed. The individuals examined belonged to both low and high income groups, the educational status varied from the University level to almost illiteracy and approximately one-third of patients resided in suburbs of Melbourne other than that in which the dental practice was situated. However, as the patients of any individual dentist reflect to some extent his own personality, general interests and particular dental interests, the sample was biased at least to this degree. Further it was not known whether this sample was composed of individuals of different types in the same proportions as occurred in the general population of Melbourne. The increase in the periodontal index with age is in agreement with the results reported for other countries. The standard errors of the means were not tabulated for two reasons. Firstly, the periodontal index is not dependent solely on age and

reports

2.57

*From

2.61

40-49

1.13 1.71

50 and over LI_~-

0.93 0.72

;;I;;

;z

of nutritional

1.86

044

0.02

U.S.A. (R;E~LL)

Australia (Present study)

0.55

DISEASE

PERIODONTAL

s-9

group

Age

MEAN

10.

surveys

2.55

1.86

0.86 1.25

0.61 0.67

0.59

of these countries

1.06

I.45

% 1.39

-

Ethiopia* (1959)

RESULTS

published

2.34

1.43

8:;; 0.89

0.29

0.12

Ecuador* (1960)

3.45

2.28

?:%

0.45 0.46

@33

Colombia* (1960)

Committee

351

2.09

y:;:

X’%

for Nutrition

4.90

4.36

3.33 1.85

$54

-

1957)

5.19

3.24

7:;: I.99

0.56

0.46

Burma+ (1963)

AND

(1959-1963).

3.95

3.02

0.54 1.75

;:;;

Lebanon* (1962)

Defense

3.06

y:;:

and National

3.30

1.26

0.39 0.71

z:;;

Thailand’ (1962)

(RUSSELL,

.

0.20

China* (1961)

U.S.A.

0.23 1.01

west* Indies 11961)

WITH

INDEX

@I4

Chile’ (1961)

COMPARED

(1959-1963)

RUSSELL’S

USING

OF SURVEYS

by the Interdepartmental

459

2.62

;:;;

“0::;

0.21

Republicof’ Vietnam (1960)

OF 12 COUNTRJES

SUMMARIZED

SCORES IN POPULATION

Alaska* (1959)

(P.I.)

TABLE

STUDY.

4.58

4.42

2.25 3.78

I,32 1.25

0.70

U(y9y$Y*

3044 years 45-54 years 55+ years

PRESENT

z;

s

x

5

q F P

$

.-

“$ c

f

AN EPIDEMIOLOCZCAL

STUDY OFCHRONIC PERIODONTAL DISEASE

563

secondly, the scores vary considerably within an age group due to the influence of such factors as oral hygiene and the presence or absence of pockets. The close correlation between oral hygiene index and, the periodontal index observed by GREENE(1960) in India, RUSSELL(1963) in South Vietnam and Lebanon is seen also in this study. However, the individual contributions of oral debris and of calculus within this relationship were examined and emphasized. ARN~M(1963) has shown by the microscopic examination of oral debris stained with a suitable disclosing solution that it is bacterial plaque in approximately 90 per cent of instances and not food debris. SKINNER(1914) realised the great difficulty of recognising this plaque as did RAMFJORD(1959). Thus it is probably preferable to discard the term oral debris and to discuss, instead, the influence of bacterial plaque on the periodontal index. Up to the age of 20 years amongst females and 24 years amongst males both oral debris and calculus strongly influenced the periodontal index. However, in older age groups only calculus exerted any effect. This might be interpreted to be a reflection of the change in the nature of the oral debris or bacterial plaque. MANDEL,LEVYand WASSERMANN (1957) described histological and histochemical investigations of early developing calculus. They placed celluloid strips around the necks of teeth and at different time intervals removed the strips for examination. Calculus was deposited in many instances, but in every instance bacterial plaque was present, irrespective of the presence or absence of calcification. TURESKY,RENSTRUPand GL~CKMAN (1961) using a similar technique demonstrated the accumulation of an adherent plaque on cellulose-acetate strips. Microscopic evidence of calcification was noted in each specimen removed between the second and sixteenth days from subjects in the 13-70 year-old age range. Nevertheless, four of the fourteen subjects in the 5-12 year-old group did not demonstrate any calcification during a 30-day period. Thus oral debris or bacterial plaque can be regarded as the precursor of calculus but in the young agegroups little calcification seems to occur. By the age of 20-24 years more calcification has occurred but thereafter so much of the plaque has calcified that only calculus influences the periodontal index. In future studies there is a need to develop a method to score bacterial plaque in the different stages leading from the uncalcified to the calcified state. Analysis of the importance of the location of oral debris in the mouth showed that for one age group the maxillary teeth were cleaner than the mandibular teeth, and anterior teeth were cleaner than the posterior teeth and the labial and buccal surfaces showed less debris than the lingual surfaces. This confirms the generally held clinical impressions formed by the examination of the mouths of individual patients. The differences between the cleanliness of various areas of the mouth may be explained by not only variations in frequency of tooth brushing but also by variations in efficiency of cleaning the teeth. Age and toothbrushing frequency were shown to influence the periodontal index. This is in agreement with RUSSELL(1963) who found that in surveys of South Vietnam and Lebanon 90 per cent of the variance in group periodontal indices could be explained by the combined influence of age and mouth cleanliness. He measured mouth

564

B. LILIENTHAL, V. AMERENA AND G. GREGORY

cleanliness by the oral hygiene index but this index is obviously related to toothbrushing habits (ARNIM, 1963). The influence of the presence or absence of pockets on the periodontal index is inherent in the scoring system itself. The score assigned to bone loss is deliberately weighted to influence the periodontal index and thus give some indication of the severity of the disease. It has been observed that the clinical diagnosis is related to the periodontal index in the following manner (RUSSELL, 1956). Clinical diagnosis

Periodontal

Normal Gingivitis Severe gingivitis or incipient Frank destructive gingivitis Terminal stages

O-0.1 or O-2 0.1-1.0 0.5-1.9 1.5-5.0 4.0-8.0

destructive

gingivitis

index

Among those examined in this survey destructive gingivitis commenced at about 15 years and became common in the age range 20-30 years. After 30 years of age destructive gingivitis was very prevalent. Thus, there appears to be a marked change in the nature of periodontal disease during this period (15-30 years), manifesting itself in changes from a simple marginal gingivitis to periodontitis with its characteristic bone loss. The present investigation offers no explanation for this change. However, the problem may be considered in relation to present knowledge of the aetiology of periodontal disease. The inflammatory reaction in any disease, including periodontal disease, is a tissue response to irritation, but the exciting factors producing inflammation in the gingiva are intimately associated with the growth and proliferation of the bacterial plaque in close proximity to the gingival tissues. The relative importance of bacterial irritation compared with mechanical irritation in the mechanism of action of these deposits (including calculus) on the periodontal tissues is the subject of much discussion. WAERHAUG (1958) stated that in the gingival tissue irritation is caused by microorganisms and their toxins rather than by mechanical agents. Thus, whether plaque is calcified or not is of minor significance, for bacteria are present in and around both KING and MARTIN (1951), however, described the influence of types of deposit. bacteria as secondary to traumatic irritation of the gingival tissues and STAHL (1960) stated that a gingival injury initiated the periodontal lesion whilst further changes Further, ORLAND (1962) working with were probably due to enzymatic activity. gnotobiotic rats reported a gingivitis caused by food impaction between the teeth and inflammatory cells were seen despite the absence of bacteria. In young children the balance between the resistance of the gingival tissue to inflammatory agents and the offensive mechanisms of these agents often results in a mild chronic gingivitis. This may be enhanced for example by systemic disturbances which deplete the resistance of the tissue or cause the tissue to react in an exaggerated manner to the inflammatory agent. Why is this equilibrium disturbed between the ages of 15 and 30 years with a consequent change from a marginal gingivitis to a periodontitis? Perhaps the answer to this question lies in a fuller knowledge of the metabolism

AN EPIDEMIOLOGICAL STUDY OF CHRONIC PERIODONTAL DISEASE

565

and growth of the bacterial plaque and of the quantitative relationship of the product(s) to the gingival tissue. Acknowledgement--We are indebted assistance with the statistical analyses.

to Miss Betty

LABY

for her invaluable

R&me-Les signes caracteristiques des gingivites chroniques et des parodontites chroniques sont etudies dans un groupe de 845 sujets de Melbourne. L’analyse des resultats montre que (1) pour les sujets de sexes masculin et feminin, ages de 5-9 ans, les debris buccaux n’influencent que l’index parodontique de Russell. (2) jusqu’a l’age de 20 ans, pour les sujets de sexe feminin, et de 24 ans, pour les hommes, & la fois les debris buccaux et le tartre influencent fortement l’index parodontique et (3) dans les groupes d’bges plus Blevts, seul le tartre affecte l’index parodontique. Une analyse de la signification des regions d’accumulation des debris buccaux, chez des sujets de 20 a 24 ans, montre (1) que moins de debris s’accumulent dans les regions anterieures par rapport aux regions postbieures; (2) que les faces vestibulaires sont plus propres que les faces linguales et palatines; (3) qu’il y a moins de debris au maxillaire superieur qu’au maxillaire inferieur, et (4) qu’une distribution bilaterale symetrique des debris est Cvidente. Parmi les 600 individus dont la frequence du brossage dentaire est notte, l’index parodontique est significativement influence par I’Pge, la frequence du brossage et la presence de cul-de-sacs pyorrheiques. L’education, le sexe, le fait de fumer, la profession, la race et couleur de la peau n’exercent aucun effet significatif sur l’index parodontique. Zusammenfassung-An einer Gruppe von 854 Personen in Melbourne wurden die Charakteristika der chronischen Gingivitis und der chronischen Parodontitis untersucht. Die Analyse der Ergebnisse zeigte, dass (i) die Zelltriimmer der Mundhohle bei 5-9 jlhrigen Knaben und Madchen den Periodontalindex von Russell nur beeinflussten, dass (ii) sowohl Zelltriimmer als such Zahnstein bei Frauen bis zum Alter von 20 Jahren und bei Mannern bis zu 24 Jahren den Periodontalindex stark beeinflussten, und dass (iii) in den llteren Gruppen nur der Zahnstein einen Effekt auf den Periodontalindex erkennen liess. Eine Signifikanzanalyse zwischen den Ablagerungsorten der Zelltrtimmer bei einer Altersgruppe (20-24 Jahre) zeigte, dass (i) im Frontzahnbereich weniger Zelltriimmer vorhanden waren als in den posterioren Regionen, dass (ii) die bukkalen oder labialen Stellen sauberer waren als die lingualen, dass (iii) im Oberkiefer signihkant weniger Zelltriimmer vorhanden waren als im Unterkiefer und dass (iv) eine bilaterale Symmetrie der Verteilung der Zelltriimmer bestand. Bei 600 Individuen, bei denen hlufiges Zlhnebiirsten festgestellt worden war, wurde der Periodontalindex signitikant durch Alter, Haufigkeit des Putzens und Gegenwart von Taschen beeinflusst. Erziehung, Geschlecht, Rauchergewohnheiten, Reruf, Rasse und Hautfarbe bewirkten keinen signifikanten Effekt auf den Periodontalindex.

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221-245.

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B. LILIENTHAL,V. AMERENAAND G. GREC~RY

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