Effects of a chlorhexidine-fluoride-strontiuni rinsing program on caries, gingivitis and some salivary bacteria among Finnish schoolchildren

SATU SPETS-HAPPONEN', HEIKKI LUOMA', HELENA FORSS', JUKKA KENTALA^ SATU ALALUUSUA-', ANJA-RIITTA LUOMA\ LISA GRONROOS', SIRKKU SYVAOJA', HELENA TAPANINEN' AND PERTTI HAPPONEN'^ ' Department of Preventive Dentistry and Cariology, University of Kuopio, Kuopio, -Public Health Center, Vaasa, 'Institute of Orthodontics and Pedodontics, University of Helsinki, Helsinki, ^Public Health Center, Espoo, and ^Department of Community Medicine, University of Kuopio, Kuopio, Finland

Spets-Happoncn S, Luoma H, Forss H, Kentala J, Alaluusua S, Luoma A-R, Gronroos L, Syvaoja S, Tapaninen H, Happonen P: Effects of a chlorhexidine-fluoride-strontium rinsing program on caries, gingivitis and some salivary bacteria among Finnish schoolchildren. Scand J Dent Res 1991; 99: 130-8. Abstract In order to find out if it is possible to prevent caries and gingivitis by periodical use of chlorhexidine-fluoride mouthrinses with or without strontium, and to find out what effects they have on salivary mutans streptococci and lactobacilli counts, a total of 243 schoolchildren aged 11 yr with high DMFS scores were randomly divided into four groups. One group (C) served as a basic control. Subjects in the second group (GXF) rinsed their mouths twice a day every third week with a rinsing solution containing 0.05% chlorhexidine gluconate and 0.04% NaF. In the third group (CXFS) the rinsing solution contained 500 ppm Sr during the first and second year and 15 ppm during the last 6 months, in addition to chlorhexidine and fluoride. In tho fourth group (CX) the solution contained only 0.05% chlorhexidine gluconate. All the rinsing solutions had pH 5.8 buffered with succinic acid-NaOH buffer. After 2 yr and 9 months, the mean DMFS (SD) increments in the G. GXF, GXFS, and GX groups were 3.8 (5.7), 2.5 (3.2), 3.5 (4.8), and 3.4 (5.5), respectively. The percentage of subjects with bleeding gingival units had decreased from initial to final values as follows: G, 81-38; GXF, 88-42; GXFS, 89-56; GX, 89-37. The number of lactobacilli and mutans streptococci in saliva remained virtually unchanged throughout the study. For caries increment and gingival bleeding, the differences between groups were not statistically significant. The chlorhexidine-fluoride combination tended to prevent caries, but the effect on gingival bleeding and salivary counts of mutans streptococci and lactobacilli was negligible. Key words: caries prevention; chlorhexidine; fluoride; gingival bleeding; lactobacilli; mutans streptococci; strontium. Satu Spets-Happonen, P'aculty of Dentistry, University of Kuopio, P.O. Box 6, 70211 Kuopio, Finland. Accepted for publication 23 August 1990.

PERIODICAL MOUTHRINSING AND ORAL HEALTH Caries and gingivitis are reduced simultaneously by chlorhexidine-fluoride applications (1-4). In schoolchildren with high DMFT scores, daily rinses with chlorhexidine and fluoride for 2 yr yielded a 53% reduction in caries incidence (1). It has also been shown that four topical applications of sodium fluoride-chlorhexidine gluconate once a week plus daily rinses with sodium fluoride-chlorhexidine solution prevent radiation caries completely and cause gingival healing in cancer patients undergoing radiation treatment (2). Home use of dentifrice containing both fluoride and chlorhexidine resulted in a slightly smaller caries increment than the use of dentifrice containing either fluoride or chlorhexidine alone (3). Chlorhexidine gel used with toothbrushing resulted in a reduction of the level of mutans streptococci in saliva (4). The reduction seemed to be most evident in individuals with a high pretreatment level of mutans streptococci. In the study of EMILSSON et al. (5), mutans streptococci could not be detected in plaque after using fluoride-containing chlorhexidine gel for 3 months. By the addition of strontium to the chlorhexidine-fluoride solution, some additional caries prevention has been obtained in rats (6). DEDHIYA et al. (7) found that in vitro, strontium, when present together with fluoride and phosphate in acidic solution adjacent to the enamel, strongly protects the enamel against subsequent acid attacks. Strontium alone has been shown to have little effect on extracellular polysaccharide production by mutans streptococci in vitro (8). The counts of mutans streptococci in saliva and gingival bleeding were markedly reduced by mouthrinses containing chlorhexidine and fluoride with or without strontium (9). The reduction was temporary, however, and complete recovery was reached within 2-3 wk. The aim of the present trial was to determine whether it is possible to prevent caries and gingivitis among schoolchildren by peri-

131

odical use of chlorhexidine-fluoride mouthrinses. It was anticipated that with periodical rinsing, it might be possible to lower the cost and effort involved in continuous rinsing programs. We also wanted to find out whether the addition of strontium would further increase the effectiveness of the chlorhexidine-fluoride solution. This eombination has in fact been proposed by FEATHERSTONE et al. (10).

Material and methods Subjects and groups ~ Altogether 243 subjects from the town of Espoo in Finland were selected from a total of 2000 schoolchildren aged 11 yr. The plan of the study was accepted by the local ethical committee for medical research, and written informed consent was obtained from the parents or guardian of each participant. All subjects admitted to the trial had developed at least one caries lesion in the 2 yr preceding the trial. The subjects were randomly divided into four groups (Table I). Rinsing program ~ The procedures for each group were as follows: Group C, control group, no rinsing. Group CX, rinsing with chlorhcxidme solution containing 0.05% chlorhexidine (CHX). Group CXF, rinsing with chlorhexidine-fluoride solution containing 0.05% CHX and 0.04% sodium fluoride (NaF). Group CXFS, rinsing with chlorhexidinefluoride-strontium solution containing 0.05% CHX, 0.04% NaF and 500 ppm strontium (as SrCL,). During the last 6 months, the Sr content was lowered to 15 ppm. Table 2 shows the exact composition of each rinsing solution. All rinsing solutions were used and the other study procedures performed on a double blind basis except for the control group which received no rinses. The rinsing program was initiated in September 1985 and lasted for 2 yr and 9 months. The rinsing period for each of the test groups was 5 days every third week. During the rinsing period, the subjects were advised to rinse their mouths with 5 ml of solution once after lunch al school and once in the evening al home before going lo bed. The rinsing procedure at school was controlled by a dental nurse. Toothbrushing without toothpaste was always performed before rinsing at school. The chil-

132

SPETS-HAPPONEN ET AL. Table 1 Baseline characteristics by group

Group Variable n Sex (% Boys) DMFS* GBI* S. mulam* score (0, 1, 2, 3) Lactobacilli* ('"LOG) No. of sealants*

C

CX

CXF

CXFS

62 39 5.7 (4.5) 0.3 (0.2) 2.0 (0.7) 4.5 (1.2) 2.2 (1.5)

54 50 6.6 (4.4) 0.3 (0.2) 2.0 (0.7) 4.2(1.1) 2.0 (1.8)

56 50 5 .0 (3.7) 0 .3 (0.2) 1.9 (0.6) 4 .8(1.1) 2 .3 (1.5)

54 54 5.5 (4.5) 0.4 (0.3) 1.8 (0.8) 4.4 (1.2) 2.0 (1.7)

* Mean (SD).

dren were also lold to brush their teeth before the evening rinse at home but no instructions concerning the use of toothpaste were given. The children were told not lo eat or drink anything alter the evening rinse. During the weekends and vacations, the children were advised to perform both rinsing procedures at home. Due to progression of the students to the "upper school level" and the resulting change of schools,

Table 2 Compo.silimi of solutions

Base solution pH 5.8

Substance

Amount

Suecinic acid (0.075 M) NaOH (0.075 M) Menthol Sodium saccharine

222 379 50 250

ml ml mg mg

Solution 1 Base solution + CX chlorhexidine gluconate solution (20»,;,)

2.5 ml

Solution 2 Base solution + CXF ehlorhexidine gluconate solution (20%)

2.5 ml

NaF

0.4 g

Solution 3 Base solution+ CXFS chlorhexidine gluconate 2.5 ml solution (20%) NaF 0.4 g SrCl, 1.52 g SrClj in the last 6 months 0.125 g Distilled water ad.

1000 ml

rinsing during the third study year was supervised by the teacher only on the first day of each rinsing period. Like their schoolmates, all subjects both in the control and the test groups were treated once a year with fluoride varnish (Duraphat) and were given restorative dental treatment when needed. Instructions for correct oral hygiene and dietary habits were also given annually. Caries - For the assessment of caries increment, the permanent teeth of the subjects were examined clinically with a mirror and explorer. Fiber optic illumination was used on approximal surfaces of the incisors and the mesial surfaces of the canines. Bitewing radiographs were taken for diagnosis of approximal caries of the premolars and molars and the distal surfaces of the canines. For radiography, the cone of the apparatus was positioned parallel to the guide mark of a film holder. Caries was scored aeeording to the criteria of MoLLER & PouLSEN (11) with some modifications, such as avoiding inserting the explorer into fissures to detect stickiness. Grade 1 was not included in the DMFS score used for calculations. The examiners did not know which group the children belonged to. To diminish disagreement between the two examiners (S. S.-H. and H. F ) , stable caries models were used for calibration during the week before every examination. The models consisted of 280 extracted permanent teeth which were embedded in plaster of Paris so that every model had seven teeth with approximal contacts to form a quadrant of the jaw. The models were kept moist with ethanol in plastic bags for the duration of the

PERIODICAL MOUTHRINSING AND ORAL HEALTH whole study. Caries was diagnosed as explained above. Radiographs were taken for diagnosis of approximal caries. Table 3 shows the intraclass correlation coefficients (12) thus obtained prior to the clinical examination each year. The intraclass correlation coefficient over the years was 0.84 and 0.45 for the two examiners. To estimate the inter- and intraobserver disagreement in assessing caries prevalence, 10% of the subjects were also reexamined on the day of the last examination. The kappa (13) for interobserver agreement was 0.70 and for intraobserver agreement 0.79, both of which indicated a good level of reliability. Gingival bleeding - For assessment of the gingival status, a modification of the gingival bleeding index (GBI) described by AINAMO & BAY (14) was

used. The gingival margins on the vestibular and mesial aspects of the permanent maxillary right canine, the two premolars and the permanent first molar were gently massaged with the side of a periodontal probe. After about 15 s, color photographs of the area were taken using a Medical Nikkor camera with a 200 mm lens and a ring flash. The bleeding was recorded by J.K. from the mesial and vestibular aspects of the gingiva of the four teeth involved from the color slides (Kodak Ektachrome-X). Bleeding was scored as 1 and no bleeding as 0. The intraexaminer error was checked by reexamining 10% of the slides from every examination, which yielded an average kappa of 0.97. Salivary parameters - To assess the salivary counts of mutans streptococci and lactobacilli, paraffin wax-stimulated saliva was collected from each subject. The secretion of saliva was stimulated by chewing a sterile piece of paraffin wax. Before collection, the saliva was swallowed for 30 s, and then collected for 5 min and the quantity mea-

Table 3 Intraclass correlation coefficients (ICC) obtained from fixed caries model prior to each clinical examination

Year

ICC

1985 1986 1987 1988

0.66 0.38 0.77 0.86

133

sured. The nuniber of mutans streptococci in saliva was estimated with the method described by ALALUUSUA et al. (15) using Dentocult-SM slides (Orion Diagnostica, Espoo, Finland). The growth density of mutans streptococci was categorized as recommended by the manufacturer as negative, no growth = score 0; low = score 1 ( 10^ CFU/ml, but < 10'^ CFU/ml) and high = score 3 (>10'' CFU/ml). A dissecting microscope was used for the evaluation of the growth density. The number of lactobacilli in saliva was estimated with the method described by LARMAS (16) using Dentocult-LB slides (Orion Diagnostica, Espoo, Finland). The lactobacilli count was expressed in powers of 10. All children were reexamined after 1 yr, 2 yr, and 2 yr 9 months. The reexaminations were made 1 wk after the rinsing period had been completed. Statistical methods - The computations and statistical analyses were made using SPSS-X and SAS software. The arithmetic mean was used as a measure of central tendency for the DMFS-score and GBI. Changes within groups were tested with the t-test for paired samples. Between-group differences were tested with the Kruskall-Wallis analysis of variance. To control for the baseline differences between groups, analysis of covariance with the respective baseline value as a covariate was carried out. Ordinal variables were analyzed with the Kruskall-Wallis analysis of variance. All /-• values reported are two-sided. No adjustment was made for multiple comparisons.

Results Data from 201 subjects (initially 243) were available after 2 yr 9 months for the flnal calculations of the results. Seventeen subjects were lost to follow-up during the first year and they were left out of the analyses. The mean baseline DMFS (SD) of those 17 subjects and of the 226 who continued was 5.9 (3.6) and 5.7 (4.3), respectively. After the first year, the percentage of drop-outs was 9.7, 21.4, 7.4, and 5.6 in the groups C, CXF, CFXS, and CX, respectively. In the group CXF the initial caries prevalence (SD) for the drop-outs was 6.4 (4.9) and 4.6 (3.2) for the rest of the children. The difference

134

SPETS-HAPPONEN ET AL.

between groups was not statistically significant. Caries prevalence was highest in the CX group both at the beginning and at the end of the study (Fig. 1), while in the CXF group caries prevalence was lowest throughout the study. At the final examination the DMFSindex in the CXF group was 3.1 units lower than that in the CX group, while at the beginning the difference was 1.6 units. The final increment values (95% confidence intervals) in groups C, CXF, CXFS, and CX were 3.8 (2.3-5.4), 2.5 (1.5-3.4), 3.5 (2.2-4.9), and 3.4 (1.8-4.9), respectively. The caries increment in the CXF group was 36% lower than that of the control group. The differences in caries prevalence and incidence between groups, however, were not statistically .significant (P = 0.51 for prevalence and P=0.92 for incidence). Adjusting the overall increments for the baseline DMFS values did not change the results. In all groups, the percentage of subjects with gingival bleeding decreased with time. The reduction was 53, 52, 37, and 58% in the groups C, CXF, CXFS, and CX, respectively {P=0.\9 for difference between groups). The gingival bleeding index was about the same in all four groups at the beginning of

Fig. 2. Mean GBI over time.

the study (Fig. 2). During the first year, the CBI decreased by about 60% in all groups (P= 0.0001 for change); thereafter it remained at the same level in all groups until the end of the study. At the end, the differences between groups were not statistically signifieant. The lactobaciUi count over time did not differ between groups, although there was a notable trend towards reduction in group CXF (Fig. 3). The mutans streptococci count in saliva remained almost constant in all groups throughout the study (Fig. 4). In the CXF, CXFS, and CX groups, yellowish brown staining of some dentitions was noticed. In most of these cases, however, staining was very mild or negligible.

DMFS 10-

CX

. • • • •

, •

c CXFS

8-

.•••'

/

/

• • • • • ' / • '

CXF

7•



1

1

2 TIME (YEARS)

Fig. 1. Caries prevalence over time.

^

Discussion Unfortunately we did not succeed in enrolling as many subjects into this study as intended (75 per group). Possibly the main reason was the general reduction of caries among Finnish schoolchildren, including the children in the Espoo area (17). As caries and its conservative treatment is nowadays considered less "threatening" than in the 197O's, children may be less motivated to participate in a rinsing program like ours. Also the parents or guardians might be less motivated to give their informed consent. The greatest proportion of drop-outs in the

PERIODICAL MOUTHRINSINC AND ORAL HEALTH GROUP C

19B6

1986

1987

135

GROUP CX

1985

1988

1986

1987

1988

YEAR

YEAR

4

GROUP CXFS 100%

Effects of a chlorhexidine-fluoride-strontium rinsing program on caries, gingivitis and some salivary bacteria among Finnish schoolchildren.

In order to find out if it is possible to prevent caries and gingivitis by periodical use of chlorhexidine-fluoride mouthrinses with or without stront...
6MB Sizes 0 Downloads 0 Views