Community
Dent. Oral Epidemiol.
1978: 6: 17-23
(Key words: dental caries; dental plaque; gingivitis; public dental health)
Effect of a field program based on systematic plaque control on caries and gingivitis in schoolchildren after 3 years S,-E, HAMP, J. LINDHE, J. FORNELL, L.-A. JOHANSSON AND R . KARLSSON Clinic oj Periodontotogy, Public Dentat Health, Linkoptng and Department oj Periodontotogy, Facutty of Odontology, University oj Gotlienburg, Gothenburg, Sweden ABSTR,\CT - The effect of a field program, based on systematic plaque control, on caries and gingivitis was tested during a 3-year period on 1,100 schoolchildren, Onee every 3rd week the children were given oral hygiene instructions, professional tootheleaning and fluorides topieally delivered by speeially trained dental nurses. The ehildren of a control group of approximately the same number of pupils, participated in a preventive program consisting of mouthrinsings once every 2nd week with a 0,2 % sodium fluoride solution. The children of the third and fourth grades were, at the start of the experiment, selected as reference groups and then eontinuously examined onee every year. At the end of the trial the mean reduction of surfaces harboring plaque and units with gingival inflammation was 59 % and 73 %, respectively. The reduction in caries inerement was 51 %, (Accepted jor pubtication 25 September 1977)
Microorganisms which colonize the deiitogingival region constitute the main etiologic factor in gingivitis and chronic destructive periodontitis, Iti the absence of plaque, teeth will not decay and the periodontal tissues will not deteriorate (reviews'*''' " ) . Attempts have been made to assess the possibility of preventing caries and gingivitis in schoolchildren by introducing meticulous plaque control programs^''*'". Even though plaque control programs, in comparison with other preventive measures, make more demands on time, space and personnel, remarkable effects on caries development and gingivitis have been reported by several investigators"'°'''''^°. In the studies referred to, the plaque control programs embraced only small groups of children and were managed by a few well-trained and devoted dental nurses. The aim of the present investigation was to organize an extensive field program based on systematic plaque control and to assess the effect of the preventive measures on caries and gingivitis in a large group of schoolchildren.
MATERIAL AND METHODS The material consisted of all pupils aged between 7 and 16 years in two school districts of Linkoping, Sweden; approximately 2,200 children were enrolled at the start of the experiment in Mareh 1974. The experimental group children (approx, 1,100) were recruited from one school district of the eity (Munkhagen), A similar number of ehildren from a neighboring school district (Berga) sei-ved as eontrols. The families from the two distriets displayed similar socioeeonomic backgrounds. All children belonging to the third (Group 1, 10 years old) and fourth (Group 2, 11 years old) grade.s, in all 406 pupils (201 test and 205 control children), were selected as reference groups (Table 1), During the 3-year period 32 % of the test and control group children were lost owing to their transfer to other school districts or absence from any of the annual examinations. Hereby 277 of the reference subjects completed the 3-year trial (137 test and 140 control children). Prior to the start of the trial the ehildren of the referenee groups were subjeeted to a clinical examination comprising assessments of plaque, gingivitis and caries. No preexperimental sealing or caries therapy was performed. All children were, once a year, given traditional dental treatment at the school dental clinics.
18
H A M P , L I N D H E , F O R N E L L , J O H A N S S O N AND K A R L S S O N
Table 1, Distribution of age and sex of the ehildren belonging to the reference groups at the baseline examination and after 3 years of trial Gontrol group
Test group Grade/age
Group
Boys
Girls
Total
Boys
Girls
Total
1974
3/10 4/11
1 2
53 47
60 41
113 88
46 53
55 51
101 104
1977
6/13 7/14
1 2
33 30
44 30
77 60
37 34
36 33
73 67
TEST GROUP Parents — Pamphlets containing written information, regarding the etiology and pathogenesis of caries and periodontal disease, were distributed to the parents of all ehildren in the school district a few weeks before the experiment started. The design of the preventive program was deseribed and results from similar trials^^ presented. It was also pointed out that partieipation in the trial was voluntary. School-teachers — The same information as presented to the parents was given to the teachers of the schools of the Munkhagen district (the test district). After 1 and 2 years of trial all teachers were assembled and, in seminars, presented with information on the goals and means of preventive dentistry. In addition, the effeet of the preventive program during lhe previous years of the trial was reported. Pupils - Prior to the initiation of the new preventive treatment the schoolchildren in the test group were informed of the eause of earies and gingivitis. In addition, the design of the preventive program was deseribed. The ehildren were informed that participation was voluntary. Equipment and auxiliaries - The school district of Munkhagen (the test district) consisted of three separate elementary sehool units. One classroom in each school was especially equipped for the trial. In order to minimize the cost of the program, rejected, secondhand dental units from the Pubhc Dental Health clinics were installed at the schools. Seven dental nurses (chairside assistants) were recruited for the program. They were given special training in the delivery of oral hygiene instruction and professional tootheleaning using mechanical instruments (low speed dental engines), , . Prophylactic activities . . ' • First year — The children of the test group were given a thorough prophylaxis once every 3rd week. At each session dental plaque was stained with a disclosing pellet containing erythrosine. The Bass technique of toothbrushing was described and demonstrated using a soft multitufted toothbrush. All tooth surfaees were then eleaned using a prophylactic paste containing 5 % sodium monofluorophosphate. The toothcleansing was performed using dental floss for interproximal surfaces, a rotating rubber cup for free smooth surfaces and a rotating pointed bristle for the fissure systems. The eleaning program required around 10-
15 min per child per session. For further details regarding the design of the professional cleaning program the reader is referred to a paper by AXEI,SSON & LINDIIEI,
.!
Second and third year - From the start of the 2nd year of experimentation, a polishing paste based on silieon dioxide with 0,22 % sodium fluoride, pH 5,2, was used. This was a eonsequence of findings from in vitro studies^^ that the fluorine content of the surface enamel could, under certain circumstances, decrease when polishing and prophylaetic pastes were used. Each toothcleaning session was terminated with a 2-min mouthrinse of a 0,2 % sodium fluoride solution. During the 2nd year of trial the efficiency of the professional cleaning was regularly checked by one of the investigators. At the end of the 3rd year teeth extracted Tor orthodontic reasons, exelusively permanent premolars, were analyzed for the fluorine content in the outermost layer of the enamel using an etching technique described by FRIBERGER". The surfaee enamel of the whole crown from eaeh tooth was analyzed and the mean value for the tooth determined.
Table 2, Surfaees harboring plaque at the baseline and at the annual reexaminations (mean, s,e,m,). Teeth examined: 16, 12, 11, 21, 22, 26, 36, 32, 31, 41, 42 and 46; in total 48 surfaces were examined. The figures are based on the 137 test and 140 control children who completed the trial Test group Group Group 1 2
Control group Total
Group Group 1 2
Total
J
1974
31,5 1,20
30,0 1,38
30,8 0,91
34,4 1,23
34,3 1,06
34,4 0,82
1975
16,6 1,16
17,2 1,24
16,9 0,84
31,5 1,33
31,8 1,17
31,7 0,90
1976
15,1 1,22
8,6 0,88
12,0 0,80
30,9 1,24
30,5 1,43
30,8 0,93
1977
13,1 1,13
14,9 1,08
14,0 0,78
35,0 1,06
32,4 1,18
33,8 0,79
Systematic plaque control GONTROL GROUP The control group children participated in a earies-preventive program established in Linkoping in 1963, This program eonsisted of mouthrinsing using a 0,2 % sodium fluoride solution, once every 2 weeks, GLINIGAL EXAMINATIONS Reexaminations were carried out 12, 24 and 36 months after the baseline examination. The clinical examinations were always performed 10-14 days after a prophylactic session. Recordings of plaque and gingivitis were made by the same investigator at all four examinations. The number of tooth surfaees, showing presenee of continuous plaque in the dentogingival area (following staining with erythrosine), and gingival units displaying signs of inflammation (bleeding on probing) were assessed. The criteria used for plaque and gingivitis assessments were recently described by AxELSsoN & LINDHE^, The plaque and gingivitis examinations were eonfined to the following tooth regions: 16, 12, 11, 21, 22, 26, 36, 32, 31, 41, 42, 46*, Assessments of clinical and radiographic caries were made by two investigators working independently, AU permanent teeth were included in the examinations, Maillefer® explorers (No, 6) were used. Posterior bitewing radiographs were taken with a parallel long cone teehnique. The radiographs were analyzed in a viewer with a magnifying glass. The earious lesions were diagnosed according to eriteria defined by Kocni", Clinical caries: loss of tooth substanee having reaehed the stage of eavitation that can be diagnosed with certainty by clinical examination with mirror and explorer after drying with air, not having the eharacter of erosion or hypoplasia, and appearing on an otherwise intact tooth surface, pits and fissures, not earlier restored, where the probe with a little pressure sticks without doubts and requires a definite pull for removal (Gode 1), "Radiographic" caries: well-defined decrease in the density of the enamel on the proximal surface which is diagnosed roentgenographieally but eannot be verified by examination with mirror and probe (Gode 3), The DFS-index was used for describing the increment of earies. This simplified index was equivalent to DMFSindex beeause the number of teeth whieh during the experiment were extracted as a consequence of earies was nil, OBSERVATION ERROR Duplieate registrations of gingival inflammation (sound or inflamed gingival units diagnosed at two examinations within 2 days) and caries (sound or carious tooth surfaees diagnosed at two examinations within 7 days) were made in one randomly selected elass after the baseline examiThe two-digit system adopted by the FDI in 1970 was used. The first digit specifies the quadrant of the mouth, the second the actual tooth. (maxilla right) . , 16 , ,
(maxilla left) . 26
.
12
11
21
22
,
,
, , 46 , , , (mandible right)
42
41
31
32
,
, , 36 (mandible left)
19
nation and following the predetermined annual examinations. The reprodueibility of gingivitis and caries diagnoses was calculated, STATISTIGAL ANALYSIS Student's t-test was used to assess the significance of differences between the test and the control groups in incremental caries, number of tooth surfaees showing presenee of plaque, and gingival units displaying signs of inflammation. Because distributions were skewed, s,e,m, (standard error) is presented in the tables. Differences in frequeney distributions of age and sex in the test and eontrol groups were analyzed by the ehi-square test,
RESULTS ORAL HYGIENE
'
Assessments of plaque at the baseline examination revealed that 30.8 (test) atid 34.4 (control) surfaces out of 48 examined (64.1 % and 7 1 . 6 % ) showed the presence of stainable deposits (Table 2). This difference between the test and control children was not statistically significant. The results of the annual reexaminations demonstrated that in the test groups a pronounced reduction in the number of surfaces harboring plaque occurred; 16.9 in 1975, 12,0 in 1976 and 14.0 in 1977. In the control group there was no obvious improvement of the oral hygiene status during the 3 years of observation. The differences between the test and control groups were statistically highly significant {P < 0.001) at each reexamination. • . GINGIVAL INFLAMMATION At the baseline examination 19.7 (test) and 19.2 (control) out of the 48 examined gingival units displayed signs of gingival inflammation (41.1 % and 40,1 % ; Table 3 ) . The plaque control program, bnt not the mouthrinsing program, markedly reduced the frequency of gingivitis. Hence, in the test groups after 1, 2 and 3 years of professional toothcleaning, the number of inflamed gingival units had been reduced to 13.2 (1975), 6.9 (1976) and 9.0 (1977), respectively. In the control group the number of itiflamed gingival units gradually iticreased during the observation period (26.3 in 1975, 26.5 in 1976 and 32.9 in 1977). The differences in gingivitis between the test and control groups were highly significant ( P < 0.001) at all reexaminations. GARIES
:
^
The number of DFS and tooth surfaces at risk, at
20
H A M P , LINDHE, FORNELL, JOHANSSON AND K A R L S S O N
Table 3, Inflamed gingival units at the baseline and at the annual reexaminations (mean, s,e,m,). Teeth examined: 16, 12, II, 21, 22, 26, 36, 32, 31, 41, 42 and 46; in total 48 gingival units were examined. The figures are based on the 137 test and 140 control children who completed the trial Gontrol group
Test group Group Group 1 2
Total
Group Group 1
Total
1974
19,5 1,15
20,0 1,44
19,7 0,91
19,6 1,18
18,7 1,31
19,2 0,88
1975
14,4 1,10
12,0 1,29
13,2 0,84
24,4 1,32
28,7 1,41
26,3 0,98
1976
8,3 1,03
5,4 0,83
6,9 0,67
26,5 1,12
26,6 1,26
26,5 0,83
1977
10,4 1,27
7,6 1,05
9,0 0,83
33,8 1,25
31,8 1,39
32,9 0,93
the baseline examinations in the test and control group children, are presented in Table 4. There were no significant differences in initial caries experience between the test and the age-matched control children. There were no differences between test and control groups regarding the increase in the number of newly erupted teeth during the three experimental years (Table 5 ) . T h e annual increment of caries is presented in Tables 6, 7 and 8. During the 1st year, the test group children developed 1.6 and the control children 1.9 new DFS ( P > 0 . 0 5 ) . During the 2nd year, the test groups developed 2.0 and the control group 5.1 new DFS ( ? < 0.001). Corresponding figures for the 3rd year were 2.6 and 5.8, respectively ( P < 0.001). Table 7 shows the number of ehildren who either were free from new carious lesions or developed 1-3, 4 - 6 , 7-9, 10-12 or more than 12 new D F S during each of the three experimental years. During the 2nd and 3rd years the number of schoolchildren with an annual D F S score of 0 - 3 was 109 (80 % ) and 99 ( 7 2 % ) , respectively, in the test group. Corresponding figures for the control group were 44 (31 % ) and 38 (27 % ) . During the 2nd and 3rd years 44 and 49 control ehildren developed more than 7 new D F S ; in the test groups the corresponding figures were 15 and 15. Table 8 gives the number of new D F S present in the two groups on approximal, oeclusal and free
Table 4, Initial balanee regarding earies experienee (mean, s,e,m,) Test group
DFS Surfaces at risk
Control group Group Group 1 2
Total
Group Group 1 2
Total
6.3 0,38
8,6 0,71
7,3 0,39
5,5 0,40
7,9 0,49
6,6 0,33
61,5 2,29
75,4 2,92
67,6 1,90
57,0 1,93
73,2 2,78
64,7 1,80
(buccal -1- lingual) smooth surfaces. T h e figures demonstrate that the professional toothcleaning program during the 2nd year was most effective in preventing caries on the approximal tooth surfaces (0.55 test and 2.49 control group) and least effective on the occlusal surfaces (1.14 and 1.96, respectively). This was also true for the third experimental year; the approximal D F S being 1.26 and 3.49, respectively {P< O.OOl). Corresponding figures for occlusal DFS were 1,15 and 1.80, respectively ( P < 0.001). T h e fluorine content in the enamel of 20 extracted permanent premolars, 10 from the test group and 10 from the controls, at the end of the 3rd experimental year is presented in Table 9. T h e figures demonstrate that the fluorine cotiteiit was significantly higher ( P < 0 . 0 5 ) in teeth from the test group eompared with the controls (1,867 and 1,208 F ' parts/10"°, respectively). DIAGNOSTIC ERROR T h e duplicate caries recordings carried out during the baseline examination in 27 children showed an agreement of 87.3 % . T h e figures for the subse-
Table 5, Changes in number of permanent teeth during the trial (mean, s,e,m,) Test group
Control group
Group 1
Group 2
Group 1
Group 2
1974-75
3,3 0,26
3,8 0,34
3,1 0,30
4,1 0,33
1975-76
4,8 0,38
3,1 0,36
5,2 0,33
3,1 0,33
1976-77
2,5 0,28
1,6 0,30
2,3 0,29
1,5 0,24
Systematic plaque control Table 6, Number of new DFS (mean, s,e,m,) deteeted at the annual examinations. The table also includes the numDcr
Ol
21
Table 8, Distribution of new DFS in different tooth surfaces (mean)
11
1975-76
1974-75
77)
Group Group 1 2
Total
Group Group 1 2
1,6 0,17
1,7 0,26
1,6 0,15
2,0 0,29
1,8 0,27
1,9 0,20
1975-76
1,4 0,23
2,9 0,42
2,0 0,23
4,9 0,38
5,4 0,39
5,1 0,27
1976-77 2,9 0,42
2,2 0,30
2,6 0,27
5,8 0,49
5,7 0,39
5,8 0,31
1974-77 5,9 0,65
6,8 0,70
6,3 0,48
12,8 0,87
12,9 0,70
12,8 0,56
quent duplicate registrations were (number of children examined within brackets) in 1975, 90.0 % (13); in 1976, 8 8 % ( 1 8 ) ; and in 1977, 8 9 % (18). Duplicate recordings of gingival inflammation of the same children showed an agreement of 75.6 % (at the baseline examination), 8 8 . 5 % (1975), 73.1 % (1976) and 86.3 % (1977).
DISCUSSION The present investigation has demonstrated that a field program, based on systematic plaque control, is effective in reducing gingival inflammation and in retarding the development of caries. In most respects, therefore, the findings of the present trial Table 7. Number of children in the test and control groups who were free from signs of earies (DFS = 0) or had developed 1-3, 4-6, 7-9, etc, new carious lesions 1975-76
1976-77
New DFS
Test
Control
Test
Control
Test
Gontrol
0 1- 3 4- 6 7- 9 10-12
43 74 17 3
50 63 18 6 3
54 55 13 12 3
6 38 52 31 10 3
34 65 23 9 2 4
7 31 53 29 13 7
140
137
140
137
140
Control
Test
Control
Test
Control
Approx-
0,68
0,74
0,55
2,49
1,26
3,49
Occlusal
0,60
0,69
1,14
1,96
1.15
1,80
Buceal -f lingual
0,31
0,48
0,34
0,69
0,21
0,48
Total
1974-75
1974-75
Test
Control group
Test group
137
1976-77
confirm observations made in studies utilizing similar plaque control programs^'*'^'"''°. It should be realized, however, that, whereas previous studies have been carried out on small groups of childreti involving well-defined age groups and supervised by one or two specially trained dental nurses, the present field program involved the participation of more than 1,000 children aged between 7 and 16 years and eight dental nurses. In March 1974 the test group children left a caries-preventive program involving mouthrinsing (0.2 % sodium fluoride) once every 2 weeks and entered a combined plaque control - fluoride rinsing program which, after a few months of introduction and summer vacation, i.e. in September 1974, was repeated once every 3 weeks. The control group children continued to participate in the bimonthly fluoride mouthrinsing program. No doubt the shift from a purely caries-preventive program to a combined plaque control-fltioride application program had both advantages and disadvantages. First of all, the more extensive plaque control program resulted in very low plaque and gingivitis scores and, in comparisoti with the controls, over a 3-year period in a 50 % reduction in the number of new Table 9, Fluoride content of the outermost layer of enamel from permanent premolars extracted for orthoclontic reasons (mean, s,e,m ,) at the end of the trial Test {n = 10)
Control ( « = 10)
P
F- parts/10-G
1,867 183
1,208 171
Dent. Oral Epidemiol.
1978: 6: 17-23
(Key words: dental caries; dental plaque; gingivitis; public dental health)
Effect of a field program based on systematic plaque control on caries and gingivitis in schoolchildren after 3 years S,-E, HAMP, J. LINDHE, J. FORNELL, L.-A. JOHANSSON AND R . KARLSSON Clinic oj Periodontotogy, Public Dentat Health, Linkoptng and Department oj Periodontotogy, Facutty of Odontology, University oj Gotlienburg, Gothenburg, Sweden ABSTR,\CT - The effect of a field program, based on systematic plaque control, on caries and gingivitis was tested during a 3-year period on 1,100 schoolchildren, Onee every 3rd week the children were given oral hygiene instructions, professional tootheleaning and fluorides topieally delivered by speeially trained dental nurses. The ehildren of a control group of approximately the same number of pupils, participated in a preventive program consisting of mouthrinsings once every 2nd week with a 0,2 % sodium fluoride solution. The children of the third and fourth grades were, at the start of the experiment, selected as reference groups and then eontinuously examined onee every year. At the end of the trial the mean reduction of surfaces harboring plaque and units with gingival inflammation was 59 % and 73 %, respectively. The reduction in caries inerement was 51 %, (Accepted jor pubtication 25 September 1977)
Microorganisms which colonize the deiitogingival region constitute the main etiologic factor in gingivitis and chronic destructive periodontitis, Iti the absence of plaque, teeth will not decay and the periodontal tissues will not deteriorate (reviews'*''' " ) . Attempts have been made to assess the possibility of preventing caries and gingivitis in schoolchildren by introducing meticulous plaque control programs^''*'". Even though plaque control programs, in comparison with other preventive measures, make more demands on time, space and personnel, remarkable effects on caries development and gingivitis have been reported by several investigators"'°'''''^°. In the studies referred to, the plaque control programs embraced only small groups of children and were managed by a few well-trained and devoted dental nurses. The aim of the present investigation was to organize an extensive field program based on systematic plaque control and to assess the effect of the preventive measures on caries and gingivitis in a large group of schoolchildren.
MATERIAL AND METHODS The material consisted of all pupils aged between 7 and 16 years in two school districts of Linkoping, Sweden; approximately 2,200 children were enrolled at the start of the experiment in Mareh 1974. The experimental group children (approx, 1,100) were recruited from one school district of the eity (Munkhagen), A similar number of ehildren from a neighboring school district (Berga) sei-ved as eontrols. The families from the two distriets displayed similar socioeeonomic backgrounds. All children belonging to the third (Group 1, 10 years old) and fourth (Group 2, 11 years old) grade.s, in all 406 pupils (201 test and 205 control children), were selected as reference groups (Table 1), During the 3-year period 32 % of the test and control group children were lost owing to their transfer to other school districts or absence from any of the annual examinations. Hereby 277 of the reference subjects completed the 3-year trial (137 test and 140 control children). Prior to the start of the trial the ehildren of the referenee groups were subjeeted to a clinical examination comprising assessments of plaque, gingivitis and caries. No preexperimental sealing or caries therapy was performed. All children were, once a year, given traditional dental treatment at the school dental clinics.
18
H A M P , L I N D H E , F O R N E L L , J O H A N S S O N AND K A R L S S O N
Table 1, Distribution of age and sex of the ehildren belonging to the reference groups at the baseline examination and after 3 years of trial Gontrol group
Test group Grade/age
Group
Boys
Girls
Total
Boys
Girls
Total
1974
3/10 4/11
1 2
53 47
60 41
113 88
46 53
55 51
101 104
1977
6/13 7/14
1 2
33 30
44 30
77 60
37 34
36 33
73 67
TEST GROUP Parents — Pamphlets containing written information, regarding the etiology and pathogenesis of caries and periodontal disease, were distributed to the parents of all ehildren in the school district a few weeks before the experiment started. The design of the preventive program was deseribed and results from similar trials^^ presented. It was also pointed out that partieipation in the trial was voluntary. School-teachers — The same information as presented to the parents was given to the teachers of the schools of the Munkhagen district (the test district). After 1 and 2 years of trial all teachers were assembled and, in seminars, presented with information on the goals and means of preventive dentistry. In addition, the effeet of the preventive program during lhe previous years of the trial was reported. Pupils - Prior to the initiation of the new preventive treatment the schoolchildren in the test group were informed of the eause of earies and gingivitis. In addition, the design of the preventive program was deseribed. The ehildren were informed that participation was voluntary. Equipment and auxiliaries - The school district of Munkhagen (the test district) consisted of three separate elementary sehool units. One classroom in each school was especially equipped for the trial. In order to minimize the cost of the program, rejected, secondhand dental units from the Pubhc Dental Health clinics were installed at the schools. Seven dental nurses (chairside assistants) were recruited for the program. They were given special training in the delivery of oral hygiene instruction and professional tootheleaning using mechanical instruments (low speed dental engines), , . Prophylactic activities . . ' • First year — The children of the test group were given a thorough prophylaxis once every 3rd week. At each session dental plaque was stained with a disclosing pellet containing erythrosine. The Bass technique of toothbrushing was described and demonstrated using a soft multitufted toothbrush. All tooth surfaees were then eleaned using a prophylactic paste containing 5 % sodium monofluorophosphate. The toothcleansing was performed using dental floss for interproximal surfaces, a rotating rubber cup for free smooth surfaces and a rotating pointed bristle for the fissure systems. The eleaning program required around 10-
15 min per child per session. For further details regarding the design of the professional cleaning program the reader is referred to a paper by AXEI,SSON & LINDIIEI,
.!
Second and third year - From the start of the 2nd year of experimentation, a polishing paste based on silieon dioxide with 0,22 % sodium fluoride, pH 5,2, was used. This was a eonsequence of findings from in vitro studies^^ that the fluorine content of the surface enamel could, under certain circumstances, decrease when polishing and prophylaetic pastes were used. Each toothcleaning session was terminated with a 2-min mouthrinse of a 0,2 % sodium fluoride solution. During the 2nd year of trial the efficiency of the professional cleaning was regularly checked by one of the investigators. At the end of the 3rd year teeth extracted Tor orthodontic reasons, exelusively permanent premolars, were analyzed for the fluorine content in the outermost layer of the enamel using an etching technique described by FRIBERGER". The surfaee enamel of the whole crown from eaeh tooth was analyzed and the mean value for the tooth determined.
Table 2, Surfaees harboring plaque at the baseline and at the annual reexaminations (mean, s,e,m,). Teeth examined: 16, 12, 11, 21, 22, 26, 36, 32, 31, 41, 42 and 46; in total 48 surfaces were examined. The figures are based on the 137 test and 140 control children who completed the trial Test group Group Group 1 2
Control group Total
Group Group 1 2
Total
J
1974
31,5 1,20
30,0 1,38
30,8 0,91
34,4 1,23
34,3 1,06
34,4 0,82
1975
16,6 1,16
17,2 1,24
16,9 0,84
31,5 1,33
31,8 1,17
31,7 0,90
1976
15,1 1,22
8,6 0,88
12,0 0,80
30,9 1,24
30,5 1,43
30,8 0,93
1977
13,1 1,13
14,9 1,08
14,0 0,78
35,0 1,06
32,4 1,18
33,8 0,79
Systematic plaque control GONTROL GROUP The control group children participated in a earies-preventive program established in Linkoping in 1963, This program eonsisted of mouthrinsing using a 0,2 % sodium fluoride solution, once every 2 weeks, GLINIGAL EXAMINATIONS Reexaminations were carried out 12, 24 and 36 months after the baseline examination. The clinical examinations were always performed 10-14 days after a prophylactic session. Recordings of plaque and gingivitis were made by the same investigator at all four examinations. The number of tooth surfaees, showing presenee of continuous plaque in the dentogingival area (following staining with erythrosine), and gingival units displaying signs of inflammation (bleeding on probing) were assessed. The criteria used for plaque and gingivitis assessments were recently described by AxELSsoN & LINDHE^, The plaque and gingivitis examinations were eonfined to the following tooth regions: 16, 12, 11, 21, 22, 26, 36, 32, 31, 41, 42, 46*, Assessments of clinical and radiographic caries were made by two investigators working independently, AU permanent teeth were included in the examinations, Maillefer® explorers (No, 6) were used. Posterior bitewing radiographs were taken with a parallel long cone teehnique. The radiographs were analyzed in a viewer with a magnifying glass. The earious lesions were diagnosed according to eriteria defined by Kocni", Clinical caries: loss of tooth substanee having reaehed the stage of eavitation that can be diagnosed with certainty by clinical examination with mirror and explorer after drying with air, not having the eharacter of erosion or hypoplasia, and appearing on an otherwise intact tooth surface, pits and fissures, not earlier restored, where the probe with a little pressure sticks without doubts and requires a definite pull for removal (Gode 1), "Radiographic" caries: well-defined decrease in the density of the enamel on the proximal surface which is diagnosed roentgenographieally but eannot be verified by examination with mirror and probe (Gode 3), The DFS-index was used for describing the increment of earies. This simplified index was equivalent to DMFSindex beeause the number of teeth whieh during the experiment were extracted as a consequence of earies was nil, OBSERVATION ERROR Duplieate registrations of gingival inflammation (sound or inflamed gingival units diagnosed at two examinations within 2 days) and caries (sound or carious tooth surfaees diagnosed at two examinations within 7 days) were made in one randomly selected elass after the baseline examiThe two-digit system adopted by the FDI in 1970 was used. The first digit specifies the quadrant of the mouth, the second the actual tooth. (maxilla right) . , 16 , ,
(maxilla left) . 26
.
12
11
21
22
,
,
, , 46 , , , (mandible right)
42
41
31
32
,
, , 36 (mandible left)
19
nation and following the predetermined annual examinations. The reprodueibility of gingivitis and caries diagnoses was calculated, STATISTIGAL ANALYSIS Student's t-test was used to assess the significance of differences between the test and the control groups in incremental caries, number of tooth surfaees showing presenee of plaque, and gingival units displaying signs of inflammation. Because distributions were skewed, s,e,m, (standard error) is presented in the tables. Differences in frequeney distributions of age and sex in the test and eontrol groups were analyzed by the ehi-square test,
RESULTS ORAL HYGIENE
'
Assessments of plaque at the baseline examination revealed that 30.8 (test) atid 34.4 (control) surfaces out of 48 examined (64.1 % and 7 1 . 6 % ) showed the presence of stainable deposits (Table 2). This difference between the test and control children was not statistically significant. The results of the annual reexaminations demonstrated that in the test groups a pronounced reduction in the number of surfaces harboring plaque occurred; 16.9 in 1975, 12,0 in 1976 and 14.0 in 1977. In the control group there was no obvious improvement of the oral hygiene status during the 3 years of observation. The differences between the test and control groups were statistically highly significant {P < 0.001) at each reexamination. • . GINGIVAL INFLAMMATION At the baseline examination 19.7 (test) and 19.2 (control) out of the 48 examined gingival units displayed signs of gingival inflammation (41.1 % and 40,1 % ; Table 3 ) . The plaque control program, bnt not the mouthrinsing program, markedly reduced the frequency of gingivitis. Hence, in the test groups after 1, 2 and 3 years of professional toothcleaning, the number of inflamed gingival units had been reduced to 13.2 (1975), 6.9 (1976) and 9.0 (1977), respectively. In the control group the number of itiflamed gingival units gradually iticreased during the observation period (26.3 in 1975, 26.5 in 1976 and 32.9 in 1977). The differences in gingivitis between the test and control groups were highly significant ( P < 0.001) at all reexaminations. GARIES
:
^
The number of DFS and tooth surfaces at risk, at
20
H A M P , LINDHE, FORNELL, JOHANSSON AND K A R L S S O N
Table 3, Inflamed gingival units at the baseline and at the annual reexaminations (mean, s,e,m,). Teeth examined: 16, 12, II, 21, 22, 26, 36, 32, 31, 41, 42 and 46; in total 48 gingival units were examined. The figures are based on the 137 test and 140 control children who completed the trial Gontrol group
Test group Group Group 1 2
Total
Group Group 1
Total
1974
19,5 1,15
20,0 1,44
19,7 0,91
19,6 1,18
18,7 1,31
19,2 0,88
1975
14,4 1,10
12,0 1,29
13,2 0,84
24,4 1,32
28,7 1,41
26,3 0,98
1976
8,3 1,03
5,4 0,83
6,9 0,67
26,5 1,12
26,6 1,26
26,5 0,83
1977
10,4 1,27
7,6 1,05
9,0 0,83
33,8 1,25
31,8 1,39
32,9 0,93
the baseline examinations in the test and control group children, are presented in Table 4. There were no significant differences in initial caries experience between the test and the age-matched control children. There were no differences between test and control groups regarding the increase in the number of newly erupted teeth during the three experimental years (Table 5 ) . T h e annual increment of caries is presented in Tables 6, 7 and 8. During the 1st year, the test group children developed 1.6 and the control children 1.9 new DFS ( P > 0 . 0 5 ) . During the 2nd year, the test groups developed 2.0 and the control group 5.1 new DFS ( ? < 0.001). Corresponding figures for the 3rd year were 2.6 and 5.8, respectively ( P < 0.001). Table 7 shows the number of ehildren who either were free from new carious lesions or developed 1-3, 4 - 6 , 7-9, 10-12 or more than 12 new D F S during each of the three experimental years. During the 2nd and 3rd years the number of schoolchildren with an annual D F S score of 0 - 3 was 109 (80 % ) and 99 ( 7 2 % ) , respectively, in the test group. Corresponding figures for the control group were 44 (31 % ) and 38 (27 % ) . During the 2nd and 3rd years 44 and 49 control ehildren developed more than 7 new D F S ; in the test groups the corresponding figures were 15 and 15. Table 8 gives the number of new D F S present in the two groups on approximal, oeclusal and free
Table 4, Initial balanee regarding earies experienee (mean, s,e,m,) Test group
DFS Surfaces at risk
Control group Group Group 1 2
Total
Group Group 1 2
Total
6.3 0,38
8,6 0,71
7,3 0,39
5,5 0,40
7,9 0,49
6,6 0,33
61,5 2,29
75,4 2,92
67,6 1,90
57,0 1,93
73,2 2,78
64,7 1,80
(buccal -1- lingual) smooth surfaces. T h e figures demonstrate that the professional toothcleaning program during the 2nd year was most effective in preventing caries on the approximal tooth surfaces (0.55 test and 2.49 control group) and least effective on the occlusal surfaces (1.14 and 1.96, respectively). This was also true for the third experimental year; the approximal D F S being 1.26 and 3.49, respectively {P< O.OOl). Corresponding figures for occlusal DFS were 1,15 and 1.80, respectively ( P < 0.001). T h e fluorine content in the enamel of 20 extracted permanent premolars, 10 from the test group and 10 from the controls, at the end of the 3rd experimental year is presented in Table 9. T h e figures demonstrate that the fluorine cotiteiit was significantly higher ( P < 0 . 0 5 ) in teeth from the test group eompared with the controls (1,867 and 1,208 F ' parts/10"°, respectively). DIAGNOSTIC ERROR T h e duplicate caries recordings carried out during the baseline examination in 27 children showed an agreement of 87.3 % . T h e figures for the subse-
Table 5, Changes in number of permanent teeth during the trial (mean, s,e,m,) Test group
Control group
Group 1
Group 2
Group 1
Group 2
1974-75
3,3 0,26
3,8 0,34
3,1 0,30
4,1 0,33
1975-76
4,8 0,38
3,1 0,36
5,2 0,33
3,1 0,33
1976-77
2,5 0,28
1,6 0,30
2,3 0,29
1,5 0,24
Systematic plaque control Table 6, Number of new DFS (mean, s,e,m,) deteeted at the annual examinations. The table also includes the numDcr
Ol
21
Table 8, Distribution of new DFS in different tooth surfaces (mean)
11
1975-76
1974-75
77)
Group Group 1 2
Total
Group Group 1 2
1,6 0,17
1,7 0,26
1,6 0,15
2,0 0,29
1,8 0,27
1,9 0,20
1975-76
1,4 0,23
2,9 0,42
2,0 0,23
4,9 0,38
5,4 0,39
5,1 0,27
1976-77 2,9 0,42
2,2 0,30
2,6 0,27
5,8 0,49
5,7 0,39
5,8 0,31
1974-77 5,9 0,65
6,8 0,70
6,3 0,48
12,8 0,87
12,9 0,70
12,8 0,56
quent duplicate registrations were (number of children examined within brackets) in 1975, 90.0 % (13); in 1976, 8 8 % ( 1 8 ) ; and in 1977, 8 9 % (18). Duplicate recordings of gingival inflammation of the same children showed an agreement of 75.6 % (at the baseline examination), 8 8 . 5 % (1975), 73.1 % (1976) and 86.3 % (1977).
DISCUSSION The present investigation has demonstrated that a field program, based on systematic plaque control, is effective in reducing gingival inflammation and in retarding the development of caries. In most respects, therefore, the findings of the present trial Table 7. Number of children in the test and control groups who were free from signs of earies (DFS = 0) or had developed 1-3, 4-6, 7-9, etc, new carious lesions 1975-76
1976-77
New DFS
Test
Control
Test
Control
Test
Gontrol
0 1- 3 4- 6 7- 9 10-12
43 74 17 3
50 63 18 6 3
54 55 13 12 3
6 38 52 31 10 3
34 65 23 9 2 4
7 31 53 29 13 7
140
137
140
137
140
Control
Test
Control
Test
Control
Approx-
0,68
0,74
0,55
2,49
1,26
3,49
Occlusal
0,60
0,69
1,14
1,96
1.15
1,80
Buceal -f lingual
0,31
0,48
0,34
0,69
0,21
0,48
Total
1974-75
1974-75
Test
Control group
Test group
137
1976-77
confirm observations made in studies utilizing similar plaque control programs^'*'^'"''°. It should be realized, however, that, whereas previous studies have been carried out on small groups of childreti involving well-defined age groups and supervised by one or two specially trained dental nurses, the present field program involved the participation of more than 1,000 children aged between 7 and 16 years and eight dental nurses. In March 1974 the test group children left a caries-preventive program involving mouthrinsing (0.2 % sodium fluoride) once every 2 weeks and entered a combined plaque control - fluoride rinsing program which, after a few months of introduction and summer vacation, i.e. in September 1974, was repeated once every 3 weeks. The control group children continued to participate in the bimonthly fluoride mouthrinsing program. No doubt the shift from a purely caries-preventive program to a combined plaque control-fltioride application program had both advantages and disadvantages. First of all, the more extensive plaque control program resulted in very low plaque and gingivitis scores and, in comparisoti with the controls, over a 3-year period in a 50 % reduction in the number of new Table 9, Fluoride content of the outermost layer of enamel from permanent premolars extracted for orthoclontic reasons (mean, s,e,m ,) at the end of the trial Test {n = 10)
Control ( « = 10)
P
F- parts/10-G
1,867 183
1,208 171
