The effect of a dicalcium phosphate chewing gum on caries incidence in children: 30-month results

The effect of a dicalcium phosphate chewing gum on caries incidence in children: 30-month results

The effect of a dicalcium phosphate chewing gum on caries incidence in children: 30-month results Sidney B. Finn, D M D , Hom er C. Jam ison, DDS, D ...

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The effect of a dicalcium phosphate chewing gum on caries incidence in children: 30-month results

Sidney B. Finn, D M D , Hom er C. Jam ison, DDS, D PH , Birm ingham , Ala.

A total of 606 school-age deaf and blind children a t the A la b a m a State School for the D eaf and Blind participated in a study of the effe ct of a dicalcium phosphate dihydrate chewing gum on the incidence of dental caries. The children were randomly assigned to groups th a t chewed a sugar, a sugar-phosphate, or a sugarless gum. A fte r 30 months, 416 students were in the study, but the number of students remaining in each group was a Imost equal. Results after six exam ina­ tions indicated a significant reduction in D FS and D M F S increments in the group th at chewed the sugar-phosphate gum compared with the group th at chewed the sugar gum, but there was a more sign ificant difference and reduction in dental caries in the former group compared with the latter group when only proximal lesions were considered. The significant reduction in caries increm ent in the group th at chewed the sugar-phosphate gum compared with the group th at chewed the sugar gum was greater than the reductions in the group th a t chewed the sugarless gum compared with the group th at chewed the sugar gum. Differences between the groups that chewed sugarless and sugar-phosphate gum were not significant.

987

There is increasing evidence from in vitro and animal studies1 that some phosphates, when incor­ porated into the diet, have the potential to reduce dental caries. There is, however, limited clinical evidence to indicate that human beings on a phos­ phate-enriched diet experience a reduction in dental caries. Averill and Bibby2 used flour and sugar in one study as a vehicle for transportation of 2 per­ cent dicalcium phosphate to the oral cavity. There was no observed reduction in dental caries after 2 years. In another study conducted in the Am­ azon region of Brazil, in which sodium phosphate was incorporated into the carbohydrate, manioc, no overall significant reduction in caries increment was observed. A significant reduction in caries increment, however, was observed in the newly erupted teeth.3 Ship and Mickelsen4 added 2 percent calcium acid phosphate to the dry flour used for bread, cakes, and other baked products for a group of 350 school children over 3 years. There was no significant reduction in caries increment in this group as compared with a control group. Stralfors5 added 2 percent dibasic calcium phos­ phate to bread, wheat flour, and sugar used in the lunches of more than 2,000 school children in Malmö, Sweden, and he found, after 2 years, a reduction of over 40 percent in DF surfaces in four anterior proximal areas. In these studies, the phosphate was added to food that was eaten according to personal pref­ erence, with some possible variance in the amounts of food containing phosphate consumed by each person, and perhaps in the thoroughness of chew­ ing and length of time the food remained in the mouth. Chewing gum, which is not swallowed and is chewed independently of other foods so that the length of chewing action can be con­ trolled and is not hampered by the presence of other foods of varying consistency, could provide an excellent vehicle for transporting anticariogenic agents and therefore might be helpful in combat­ ing dental caries. In the study reported here, a group of chil­ dren under strict supervision in their use of gum was secured to find a more definitive answer as to whether a phosphate gum can reduce dental caries. This study was undertaken to determine the effect on the incidence of dental caries of a dicalcium phosphate dihydrate gum compared with the same gum without the phosphate. For further comparative purposes, a nonsugar, non­ phosphate gum was also included. No nonchewing group was included because, in 988

■ JA D A , V o l. 74, A p ril 1967

the institution selected for the study, the children live in dormitories and it would not be feasible or practical to restrict gumchewing to a portion of the children living in each dormitory and to omit others. Also, the groups of children would be relatively small and further fragmentation into smaller groups would be undesirable. M a terial and methods

A group of 606 deaf or blind children of school age residing at the Alabama State School for the Deaf and Blind was selected for the study. This group included the entire school population ex­ cept for adults. These children are resident in school for 9 months of the year, generally be­ ginning at 6 years of age and remaining until graduation at about 18 years of age. After grad­ uation, they may stay for additional vocational training. These children reside in modern dormi­ tories with a supervisor for about every 20 chil­ dren. All children are served the same foods, which are portioned out on their plates. They eat well, and little food is left on their plates after meals. They have limited access to sweets. They attend school on campus and have a 2-week vacation over the Christmas holidays. The 606 Caucasian and Negro children initially in this study were assigned to groups according to age, sex, race, infirmity, previous use of a dentifrice, and total DMF teeth. The stratified groups were then randomly assigned to one of three groups. Group 1 chewed a sugar gum, group 2 a sugarless giim, and groiip 3 a sugar gum containing 225 mg. of dicalcium phosphate dihydrate per stick. All children were instructed to brush their teeth after breakfast (before chew­ ing) with a nontherapeutic dentifrice supplied to them. They were told to chew five sticks of gum daily for 20 minutes each chewing period—two sticks between breakfast and lunch, one stick after school, and two sticks between dinner and bedtime. All gum had the same flavor and was packaged in unmarked wrappers so that there were no recognizable differences. Each box was marked with the child’s name and with a code number so that the type of gum chewed was unknown to the child, the supervisors, the dental examiner, and the statistician. The sealed code was locked in a safety-deposit box. The gum was distributed daily to each child by the supervisors, who re­ ceived extra compensation to see that the chewing was carried out. Supervisors checked and signed

a daily record sheet indicating each time the child chewed. These records were collected monthly. Unannounced visits to the dormitories were made by members of the study team to see if the chew­ ing instructions were being obeyed. Gum was distributed to the children when they left for vacation, and extra gum was dis­ tributed for other members of the family. During the summer, additional gum was delivered state­ wide to these homes by dental students who en­ couraged continued chewing. There was, however, no way of supervising the summer chewing. Clinical examinations were conducted by one examiner (S.B.F.) by use of a sharp explorer (Cookson-Stratford) under good light. Each ex­ plorer was discarded after 20 examinations. Pits or fissures were not considered carious unless the tine of the explorer contacted soft dentin at the base of the fissure or unless the margins of the fissures gave indications of being undermined. The finding on each surface was recorded on mouth maps designed for the purpose. The find­ ings were simultaneously recorded on a tape, and the notations on the tape were later compared with the notations on the mouth map to elimi­ nate any possible recording errors. Six anterior periapical radiographs and two or four posterior bitewing radiographs, depending on the number of posterior teeth erupted, were taken of every child. The radiographs were read by the same examiner under the same light, by use of a magnifying glass, and findings were recorded on mouth maps in red crayon to contrast with clinical findings recorded in pencil. The proximal surface of every tooth had to be visible on the radiograph for the radiograph to be acceptable. Radiographs were taken by use of a 90 KVP machine and fast film to avoid excessive ex­ posure. Since most of the dental work for these children was done in the school clinic, these radiographs were used for diagnosis and treat­ ment. Initial examinations were conducted in the Fall of 1963 and every 6 months thereafter for 30 months, resulting in six examinations. The mouth maps were then coded and subjected to statistical analysis. Analysis of the data was done relative to DF teeth and DMF teeth per subject, DF teeth per 28 teeth per subject, DF surfaces and DMF surfaces per subject, and DF surfaces per 122 surfaces per subject. In addition, similar analysis was made of all surfaces of posterior teeth, prox­ imal surfaces of all teeth, and proximal surfaces of posterior teeth. One hundred twenty-two sur­ faces were used, excluding the incisal edges of

the anterior teeth and the lingual surfaces of the lower anterior teeth because of their extreme re­ sistance to dental caries or the absence of avail­ able surfaces for caries attack. Since the person is the unit of measurement, the results are com­ puted as though each person had 28 teeth and 122 surfaces and the caries attack rate is assessed on this basis rather than per 100 teeth or 1,000 surfaces, as sometimes done. No difference was considered significant below the 95 percent level, regardless of percentage dif­ ference. This figure was chosen before the be­ ginning of the study and would require a t value of at least 1.96. Results

At the initial examination, there were 606 sub­ jects, with at least 200 in each of the three groups. At the sixth examination, after 30 months, there remained a total of 416 subjects: 129 in the group that chewed sugar gum, 149 in the group that chewed sugarless gum, and 138 in the group that chewed sugar-phosphate gum. The differences between the initial numbers of children and those remaining after 30 months were caused by graduation, school dropouts, and by a few who had received orthodontic appli­ ances after the study began. A few subjects re­ fused to chew gum and were excluded from the study. The age and sex distribution of the three groups were comparable. Caucasian children composed 63 and 64 percent of each group, and the other children in each group were Negro. Table 1 in­ dicates the distribution of the groups according to age and sex. The mean ages, at the initial examination, of the 416 children who remained in the study were found to be 12.357 in group 1, 12.450 in group 2, and 12.377 in group 3. Thus, there were no significant age differences between these groups. Those children remaining after 30 months in the study presented an initial ratio of DMF teeth and DF surfaces that was not significantly different in all three groups when comparing the sugar, sugarless, and sugar-phosphate groups. The num­ bers of DMF teeth and DF surfaces per person are not significantly different as are the numbers of sound teeth and surfaces. When one group is compared with the other two, as shown in Tables 2 through 4, there are no statistically significant differences between these groups. After 30 months on the chewing gum regimens,

Finn— Ja m iso n : D IC A L C IU M P H O S P H A T E C H E W IN G G U M A N D C A R IE S

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Table 1 " Distribution o f 416 subjects who were present for examination 1 and examination 6, according to ag e, sex, and treatment

Group 1 (sugar gum) M

F

M

F

1945 and earlier 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1 956 and later

2 7 2 2 6 7 4 13 8 5 3 8

1 3 6 4 6 2 10 11 3 4 5 7

3 10 8 6 12 9 14 24 11 9 8 15

5 8 3 8 4 6 4 15 7 3 6 9

4 1 1 4 8 6 7 10 10 8 5 7

Total

67

62

129

78

71

Year of birth

Group 3 (sugar-phosphate gum)

Group 2 (sugarless gum)

Total

Total

Total

M

F

9 9 4 12 12 12 11 25 17 11 11 16

1 6 6 7 7 2 5 13 9 8 2 9

2 2 3 3 3 7 8 14 4 6 5 5

3 8 9 10 10 10 13 27 13 14 7 14

149

76

62

138

Table 2 m Initial, condition of the teeth at beginning o f study (all surfaces, all teeth), comparing a sugar with a sugarless chewing gum Sugar gum (mean)

Sugarless gum (mean) Difference

Difference (% )

“ t” value

Ratio of DMFT/subject

5.019

5.372

-0.353

-6.564

-0.580

Ratio of DFS/subject

7.468

8.158

-0.690

-8.456

-0.625

79.070

78.221

0.848

1.073

0.232

Sound surfaces/ subject

5.876

6.389

-0.513

-8.034

-0.545

Sound teeth/ subject

16.109

15.906

0.202

1.257

0.268

DMFT/subject

4.163

4.517

-0.354

-7.837

-0.604

DFS/subject

Table 3 m Initial condition of the teeth at beginning o f study (all teeth, all surfaces), comparing a sugar with a sugar-phosphate chewing gum

Sugar gum (mean)

Sugarphosphate Difference gum (mean) Difference (% )

“ t" value

Ratio of DMFT/subiect

5.019

5.210

-0.191

-3.666

-0.304

Ratio of DFS/subject

7.468

8.173

-0.705

-8.629

-0.596

79.070

80.275

-1.206

-1.502

-0.315

Sound surfaces/ subject

5.876

6.783

-0.907

-13.367

-0.863

Sound teeth/ subject

16.109

16.348

-0.239

-1.464

-0.299

DMFT/subject

4.1 63

4.543

-0.381

-8.379

-0.624

DFS/subject

Table 4 * Initial condition of the teeth at beginning o f study (all teeth, all surfaces), comparing a sugarless with a sugar-phosphate chewing gum SugarSugarless phosphate gum gum (mean)(mean) Différence

Différence (% )

"t” value

Ratio of DMFT/subject

5.372

5.210

0.162

3.008

0.254

Ratio of DFS/subject

8.158

8.173

-0.016

-0.1 90

-0.013

78.221

80.275

-2.054

-2.559

-0.562

Sound surfaces/ subject

6.389

6.783

-0.393

-5.799

-0.366

Sound teeth/ subject

15.906

16.348

-0.442

-2.702

-0.566

DMFT/subject

4.517

4.543

-0.027

-0.588

-0.043

DFS/subiect

990

■ JA D A , V o l. 74, A p ril 1967

considering all teeth and surfaces, a comparison between the group that chewed the sugar gum and the group that chewed the sugar-phosphate gum reveals that there is a significant reduction in the latter group in DF surfaces and in DMF surfaces whether one includes or does not include reversals. No significant differences were observed when considering teeth only, although the figures ap­ proach significance. When the unit of measure­ ment is based on 28 teeth of 122 surfaces, there are no significant differences, as depicted in Table 5. A similar trend is revealed when the gfoup that chewed the sugar gum is compared with the group that chewed the sugarless gum (Table 6). The latter group shows a significant reduction in number of DF teeth and DMF teeth per subject and DMF teeth and DF surfaces when reversals are included. No significant differences are ob­ served when considering 28 teeth or 122 surfaces per child. When the group that chewed the sugarless gum is compared with the group that chewed the sugar-phosphate gum (Table 7), there are no ap­ preciable mean differences between the groups, whether one considers teeth or surfaces. There is evidence from animal studies and human studies that phosphates are more effective in the prevention of smooth-surface lesions than the pit and fissure variety.5 It seemed advisable to determine if there were any differences be­ tween gum groups relative to smooth-surface le­ sions. In these groups, all but a few of the smoothsurface lesions were proximal cavities perhaps because of the unusual cleanliness of the posterior segments of the dentition and because of the age factor. The findings of this study confirm the observa­ tion that phosphates have a preferential cariesreducing potential for interproximal lesions. Initially, a comparison of all three gum groups reveals no statistically significant mean differences (Tables 8-10). Regarding the proximal surfaces of all teeth after 30 months, the group that chewed the sugarphosphate gum shows a statistically significant mean difference in all of the computations over the group that chewed the sugar gum, amount­ ing to between 39.7 and 52.9 percent. Table 11 presents these comparisons. In the group that chewed the sugarless gum, there were significant differences in some of the computations of that group and the group that chewed the sugar gum. Reductions ranged from

Table 5 m Increment of d e c a y experienced for teeth and surfaces (all surfaces, a(l teeth), comparing a sugar with a sugar-phosphate chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/28T/subject DFS/122S/subject

SD*

Sugarphosphate gum (mean)

SD*

Difference

Difference (% }

3.101 5.597 3.124 5.915 3.085

2.657 4.909 2.678 5.081 2.710

2.522 4.500 2.536 4.725 2.507

2.258 3.988 2.287 4.223 2.280

0.579 1.097 0.588 1.190 0.578

18.674 19.598 18.815 20.121 18.735

1.923 2.01 Of 1.933 2.087f 1.890

5.233

5.101

3.877

4.335

1.356

25.910

2.345f

4.891 7.808

4.076 6.640

4.364 6.810

4.164 6.324

0.527 0.997

10.772 12.774

1.044 1.257

Sugar gum (mean)

"t” value

‘ Standard deviation. ■{■Significant at 95 percent level.

Table 6 " Increment of d ecay experienced for teeth and surfaces (all surfaces, all teeth), comparing a sugar with a sugarless chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/28T/subject DFS/122S/subject

Sugar gum (mean)

SD*

Sugarless gum (mean)

SD*

Difference

Difference (% )

3.101 5.597 3.124 5.915 3.085

2.657 4.909 2.678 5.081 2.710

2.523 4.584 2.530 4.919 2.503

2.152 4.241 2.Î61 4.588 2.174

0.577 1.013 0.594 0.995 0.582

18.617 18.099 19.008 16.827 18.861

2.0011 1.846f 2.045 1.716 1.985

5.233

5.101

3.933

4.038

1.300

24.838

2.3<59f

4.891 7.808

4.076 6.640

4.264 7.016

3.983 7.483

0.627 0.792

12.816 10.142

1.294 0.927

“ t" value

‘ Standard deviation. fSignificant at 95 percent level.

Table 7 m Increment of d ecay experienced for teeth and surfaces (all surfaces, all teeth), comparing a sugarless with a sugar-phosphate chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/28T/subject DFS/1 22S/subject

SD*

Sugarphosphate gum (mean)

SD*

Difference

Difference (% )

"t" value

2.523 4.584 2.530 4.919 2.503

2.152 4.24? 2.161 4.588 2.174

2.522 4.500 2.536 4.725 2.507

2.258 3.988 2.287 4.223 2.280

0.002 0.084 -0.006 0.195 -0.004

0.069 1.830 -0.238 3.960 -0.155

0.007 0.172 -0.023 0.373 -0.015

3.933

4.038

3.877

4.335

0.056

1.426

0.113

4.264 7.016

3.983 7.483

4.364 6.810

4.164 6.324

-0.1 00 0.206

-2.292 2.930

-0.208 0.250

Sugarless gum (mean)

‘ Standard deviation.

Table 8 a Initial condition of the teeth at beginning of study (proximal surfaces, posterior teeth), comparing a sugar with a sugarless chewing gum Sugar gum (mean)

Sugarless gum (mean) Difference

Difference (% )

“ t” value

Table 9 m Initial condition of the teeth at beginning of study (proximal surfaces, posterior teeth), comparing a sugar with a sugar-phosphate chewing gum

Sugar gum (mean)

Sugarphosphate gum Difference (mean) Difference (% )

"t" value

Ratio of DMFT/subject

1.484

1.830

-0.346

- Ì 8.927

-1.116

Ratio of DMFT/subject

1.484

1.828

-0.345

-18.851

-1.003

Ratio of DFS/subject

1.513

1.722

-0.209

-12.117

-0.578

Ratio of DFS/subject

1.513

1»817

-0.304

-16.733

-0.716

19.140

18.792

0.348

1.816

0.313

19.140

19.457

-0.317

-1.629

-0.275

DFS/subject

1.202

1.342

-0.141

-10.484

-0.457

DFS/subject

1.202

1.543

-0.342

-22.153

-0.914

Sound teeth/ subject

9.178

8.966

0.212

2.308

0.391

Sound teeth/ subject

9.178

9.304

-0.126

-1.355

-0.220

DMFT/subject

1.248

1.550

-0.302

-19.497

-1.076

DMFT/subject

1.248

1.616

-0.368

-22.766

-1.146

Sound surfaces/ subject

Sound surfaces/ subject

Finn— Ja m iso n : D IC A L C IU M P H O S P H A T E C H E W I N G G U M A N D C A R IE S



991

16.8 to 35.0 percent in the group that chewed the sugarless gum (Table 12). Essentially, there are no significant differences when the group that chewed the sugarless gum is compared with the group that chewed the sugar-phosphate gum (Table 13). Although the difference between the groups chewing the sugar­ less gum and the sugar-phosphate gum ranged between 24.8 percent and 31.1 percent in favor of the latter group, statistical significance was only obtained in one parameter. Since one chews principally with the posterior teeth, it was of interest to study the mean in­ cremental differences in all surfaces of the pos-

Table 10 * Initial condition of the teeth at beginning of study (proximal surfaces, posterior teeth), comparing a sugarless with a sugar-phosphate chewing gum SugarSugarless phosphate gum gum (mean) (mean) Difference

Difference (% )

“ t" value

Ratio of DMFT/subject

1.830

1.828

0.002

0.093

0.005

Ratio of DFS/subiect

1.722

1.817

-0.095

-5.252

-0.242

18.792

19.457

-0.665

-3.416

-0.608

Sound surfaces/ subject DFS/subject

Ì.342

1.543

-0.201

-13.035

-0.577

Sound teeth/ subject

8.966

9.304

-0.388

-3.632

-0.628

DMFT/subject

1.550

1.616

-0.066

-4.060

-0.215

T ab le 11 * Increment of d ecay experienced for teeth and surfaces (proximal surfaces, all teeth), comparing a sugar with a sugar-phosphate chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals i ncluded) Difference in DFS/subject (reversals included) DFT/28T/subject DFS/ 56S/subject

SD*

Sugarphosphate gum (mean)

SD*

Difference

Difference (% )

2.054 2.636 2.109 2.791 2.078

2.682 3.555 2.679 3.568 2.697

1.065 1.413 1.094 1.514 1.065

1.640 2.253 1.678 2.344 1.701

0.989 1.223 1.014 1.276 1.012

48.146 46.387 48.106 45.731 48.726

3.662f 3.379t 3.733f 3.476f 3.693f

2.512

3.578

1.181

2.405

1.330

52.972

3.587t

2.593 3.217

3.249 4.230

1.484 1.939

2.236 3.141

1.108 1.277

42.754 39.708

3.265f 2.81 3 f

Sugar gum (mean)

"t " value

‘ Standard deviation. fSignificant at 95 percent level.

T ab le 12 * Increment of d ecay experienced for teeth and surfaces (proximal surfaces, ail teeth), comparing a sugar with a sugarless chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/28T/subiect DFS/56S/subject

Sugar gum (mean)

SD*

Sugarless gum (mean)

SD*

Difference

Difference (To)

2.054 2.636 2.109 2.791 2.078

2.682 3.555 2.679 3.568 2.697

1.483 1.879 1.517 2.040 1.497

2.009 2.751 2.065 2.920 2.059

0.571 0.756 0.592 0.750 0.581

27.798 28.701 28.065 26.890 27.960

2.025f 1.997f 2.077f 1.928 2.033f

2.512

3.578

1.631

2.702

0.881

35.067

2.333f

2.593 3.217

3.249 4.230

2.156 2.636

3.022 4.177

0.437 0.581

16.848 16.064

1.161 1.150

“ t” value

‘ Standard deviation. fSignificant at 95 percent level.

T ab le 13 B Increment of d ecay experienced for teeth and surfaces (proximal surfaces, all teeth), comparing a sugariess with a sugar-phosphate chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/28T/subject DFS/56S/subject ‘ Standard deviation. fSignificant at 95 percent level.

9 9 2 ■ JA D A ,

Vol. 74,

A p ril

1967

SD*

Sugarphosphate gum (mean)

SD*

Difference

(%>

“ t" value

1.483 1.879 1.517 2.040 1.497

2.009 2.751 2.065 2.920 2.059

1.065 1.413 1.094 1.514 1.065

1.640 2.253 1.678 2.344 1.701

0.418 0.466 0.423 0.526 0.431

28.1 82 24.806 27.860 25.770 28.826

1.922 1.563 1.893 1.674 1.927

1.631

2.702

1.181

2.405

0.450

27.575

1.485

2.156 2.636

3.022 4.177

1.484 1.939

2.236 3.141

0.672 0.696

31.155 26.416

2.12 7f 1.586

Sugarless gum (mean)

terior teeth. The data in Table 14 show a signif­ icant reduction in caries increment in the group that chewed the sugar-phosphate gum when com­ pared with the group that chewed the sugar gum in all but two of the parameters analyzed. These reductions range from 17 to 30 percent. When all surfaces of the posterior teeth are considered (Table 15), there are significant re­ ductions in caries increments in the group that chewed the sugarless gum when compared with the group that chewed the sugar gum. These re­ ductions range from 15 to 27 percent. When the group that chewed the sugarless gum is compared with the group that chewed the sugar-phosphate gum (Table 16), the data reveal that there are minor and insignificant differences

in the caries increments in all surfaces of posterior teeth. Analysis of the proximal surfaces of the pos­ terior teeth reveals (Table 17) that there is a sig­ nificant reduction in caries increment in the group that chewed the sugar-phosphate gum when com­ pared with the group that chewed the sugar gum. These significant reductions range from 52 to 62 percent. The posterior proximal surface data in Table 18 show a significant reduction in caries incre­ ments of from 25 to 44 percent in the group that chewed the sugarless gum when compared with the group that chewed the sugar gum. In the posterior proximal surfaces, the group that chewed the sugar-phosphate gum experienced

Table 14 * Increment of d ecay experienced for teeth and surfaces (all surfaces, posterior teeth), comparing a sugar with a sugar-phosphate chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subiect (reversals included) Difference in DFS/subject (reversals included) DFT/161/subject DFS/80S/subject

SD*

Sugarphosphate gum (mean)

SD*

Difference

Difference (% )

2.814 5.186 2.837 5.481 2.814

2.493 4.545 2.518 4.727 2.540

2.232 3.986 2.246 4.210 2.232

2.005 3.506 2.014 3.652 2.019

0.582 1.201 0.591 1.270 0.582

20.685 23.149 20.824 23.181 20.685

2.1091 2.426t 2.12 4f 2.467t 2.080t

4.845

4.777

3.377

4.138

1.468

30.303

2.689t

5.877 8.373

5.060 7.491

4.818 6.924

4.760 7.105

1.059 1.449

18.026 17.307

1.763 1.622

Sugar gum (mean)

“ f" value

‘ Standard deviation. tSignificant at 95 percent level.

Table 15 * Increment of d ecay experienced for teeth and surfaces (all surfaces, posterior teeth) comparing a sugar with a sugarless chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/1 6T/siibj6ct DFS/80S/subject

SD*

Sugarless gum (mean)

SD*

Difference

Difference (% )

2.814 5.186 2.837 5.481 2.814

2.493 4.545 2.518 4.727 2.540

2.221 4.054 2.228 4.383 2.208

1.193 3.526 1.911 3.878 1.911

0.592 1.132 0.609 1.098 0.606

21.055 21.835 21.466 20.036 21.532

2.238f 2.336t 2.288t 2.1 27t 2.265t

4.845

4.777

3.490

3.452

1.355

27.968

2.735t

5.877 8.373

5.060 7.491

4.705 7.099

4.281 7.532

1.172 1.274

19.946 15.213

2.092t 1.410

Sugar gum (mean)

" t " value

‘ Standard deviation. tSignificant at 95 percent level.

Table 16 * Increment o f d ecay experienced for teeth and surfaces (all surfaces, posterior teeth) comparing a sugarless with a sugar-phosphate chewing gum. Results after 30 months

(mean)

SD*

Sugarphosphate gum (mean)

2.221 4.054 2.228 4.383 2.208

1.913 3.526 1.911 3.878 1.911

2.232 3.986 2.246 4.210 2.232

2.005 3.506 2.014 3.652 2.019

-0.010 0.068 -0.018 0.172 -0.024

-0.466 1.682 -0.810 3.934 -1.068

-0.045 0.164 -0.079 0.387 -0.103

3.490

3.452

3.377

4.138

0.113

3.241

0.252

4.705 7.099

4.281 7.532

4.818 6.924

4.760 7.105

-0.113 0.175

-2.343 2.470

-0.211 0.203

Sugarless

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/16T/subject DFS/80S/subject

SD*

Difference

(% )

"t” value

‘ Standard deviation.

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Table 17 B Increment of d ecay experienced for teeth and surfaces (proximal surfaces, posterior teeth), comparing a sugar with a sugar-phosphate chewing gum. Results after 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/1 6T/subject DFS/32S/subject

Sugarphosphate gum (mean)

SD*

Difference

Difference (% )

1.860 2.372 1.915 2.519 1.899

2.458 3.241 2.459 3.253 2.465

0.826 1.072 0.855 1.174 0.841

1.372 1.851 1.412 1.937 1.415

1.034 1.300 1.060 1.345 1.059

55.598 54.788 55.342 53.405 55.741

4.281 f 4.057f 4.353f 4.1 3 8 f. 4.338f

2.271

3.266

0.855

2.109

1.416

62.353

4.236f

2.552 3.155

3.104 4.157

1.199 1.503

1.863 2.533

1.353 1.652

53.026 52.352

4.352f 3.949f

Sugar gum (mean)

SD*

“ t” value

‘ Standard deviation. fSigniflcant at 95 percent level.

Table 18 1 Increment of decay experienced for teeth and surfaces (proximal surfaces, posterior teeth), com parin g a sug ar with a sugarless chew ing gum. Results a fte r 30 months

DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/16T/subject DFS/32S/subject

Sugar gum (mean)

SD*

Sugarless gum (mean)

SD*

Difference

Difference (% )

“ t” value

1.860 2.372 1.915 2.519 1.899

2.458 3.241 2.459 3.253 2.465

1.188 1.450 1.221 1.604 1.201

1.706 2.151 1.759 2.319 1.748

0.673 0.922 0.693 0.915 0.698

36.149 38.887 32.206 36.332 36.746

2.677f 2.829f 2.729Í 2.727f 2.749f

2.271

3.266

1.255

2.112

1.016

44.744

3.119f

2.552 3.155

3.104 4.157

1.912 2.231

2.817 3.671

0.641 0.924

25.099 29.274

1.803 1.967f

‘ Standard deviation. fSigniflcant at 95 percent level.

T ab le 19 • Increment of d ecay experienced for teeth and surfaces (proximal surfaces, posterior teeth), com parin g a sugarless with a sugar-phosphate chewing gum. Results a fte r 3 0 months

Sugarless gum (mean) DFT/subject DFS/subject DMFT/subject DMFS/subject Difference in DMFT/subject (reversals included) Difference in DFS/subject (reversals included) DFT/1 6T/subject DFS/32S/subject ‘ Standard deviation

SD*

SD*

Difference

Difference (% )

t" value

0.362 0.377 0.366 0.430 0.361

30.459 26.020 29.997 26.815 30.030

1.970f 1.587 1.937 1.698 1.913

1.188 1.450 1.221 1.604 1.201

1.706 2.151 1.759 2.319 1.748

0.826 1.072 0.855 1.174 0.841

1.372 1.851 1.412 1.937 1.415

1.255

2.112

0.855

2.109

0.400

31.869

1.604

1.912 2.231

2.817 3.671

1.199 1.503

1.863 2.533

0.713 0.728

37.285 32.630

2.507f 1.941

fSigniflcant at 95 percent level.

less of a caries increment than the group that chewed the sugarless gum. The reductions, as shown in Table 19, ranged from 26 to 37 per­ cent, and these differences were significant only When considering DF teeth.

Discussion

There was a total of 36 reversals found when findings of the first examination were compared with findings of the sixth examination. These were divided as follows: 9 in the group that chewed the sugar gum, 15 in the group that chewed the sUgarless gum and 12 in the group that chewed the sugar-phosphate gum. These differences in 994 ■ JA D A , V ol. 74, A p ril 1967

Sugarphosphate gum (mean)

numbers of reversals did not affect the results of the study to any appreciable degree. It is interesting to speculate on the pronounced caries reduction on the proximal surfaces of the teeth, particularly the posterior teeth, and the lack of comparable reductions in the pit and fis­ sure surfaces, in the group that chewed the sug­ arless gum and the group that chewed the sugarphosphate gum. Why these should differ is highly speculative, but might be caused by the differences in relative susceptibility of the two types of areas. The attacking force may be so extreme on the occlusal surfaces of particularly the first molars that it might overwhelm the caries-reducing effect of the phosphate. This attacking force might ac­ count for no significant reduction in the study of Ship and Mickelsen,4 in which all surfaces were

included in presenting the data with no special attention paid to the proximal surfaces. In their study and studies by Averill and Bibby13 and by Stralfors,5 the phosphates were placed in foods and eaten with other foods. The amount of bread eaten by each person may have varied consider­ ably and might have been swallowed with little chewing. In contrast to the vehicle used for the transport of the phosphate in the aforementioned studies, in the study reported here, each child chewed for 20 minutes without the gum being in contact with other bulky foods, without the possibility of premature swallowing and before the liberation of the phosphate. Stralfors,5 in con­ trast to the studies of Averill and Bibby2 and Ship and Mickelsen,4 observed about a 50 percent reduction the first year and a 43 percent reduction the second year when a phos­ phate was incorporated into the diet in the flour and sugar. He examined only four proximal sur­ faces on the maxillary central and lateral incisors. These teeth are in the midrange of caries sus­ ceptibility of the entire dentition. However, since this study indicates that when phosphates are used there appears to be a preferential difference in effectiveness between proximal caries and pit and fissure caries, the use of incisors for testing a phosphate may not be revealing as to the over­ all differences as studied by Averill and Bibby3 and Ship and Mickelsen.4 Since chewing gum involves the posterior teeth more than the anterior teeth, the beneficial prox­ imal effect should be greater in the posterior areas than in the anterior areas. Our study offers evi­ dence that this is true. Incidentally, it was observed that in those children in this study, regardless of what gum they chewed, the surfaces of the posterior teeth ap­ peared unusually clean even in the interproximal areas, whereas the upper anterior areas did not appear as clean. Although these children had not received a prophylaxis for a year, their pos­ terior teeth appeared free of calculus or plaque formation. Perhaps this condition was caused by the cleansing action of the gum or an increased salivary flow or both. There was a significant reduction in dental caries on proximal surfaces in the groups that chewed the sugarless gum and the sugar-phos­ phate gum when compared with the group that chewed the sugar gum. The differences, however, were greater in the group that chewed the sugarphosphate gum than in the group that chewed the sugarless gum. When the proximal surfaces of the posterior teeth in the group that chewed

the sugarless gum were compared with those sur­ faces in the group that chewed the sugar-phos­ phate gum, there were reductions of from 26 to 37 percent in the latter group over the former group, which had attained significance in two categories. This finding seems to suggest that the phosphate gum may be superior to the sugarless gum in combating dental caries among gum chewers. The anticariogenic effect on the proximal surfaces of gum chewers has increased with con­ tinued usage. After 30 months on the three regi­ mens, the reductions in the groups chewing the sugarless and the sugar-phosphate gums have in­ creased over what was observed after 24 months.6 Sum m ary

This study demonstrates, when all surfaces of all teeth are considered, that at the 95 percent level of confidence there is a significant reduction in DFS and DMFS increments in the group that chewed the sugar-phosphate gum when compared with the group that chewed the sugar gum. When proximal lesions are considered independently, there is more pronounced difference and signifi­ cant reduction in dental caries in the group that chewed the sugar-phosphate gum over the group that chewed the sugar gum, whether one considers teeth or surfaces as the unit of comparison. The significant reductions in caries increment obtained when comparing the sugar-phosphate gum with the sugar gum were greater than the reductions obtained when comparing the sugarless gum with the sugar gum. T h is research was supported by a grant from the A m erican C h icle Co., Long Island, N .Y ., a division of W a rn e r- L a m b e rt Ph arm aceutical Co. Doctor Finn is professor and chairm an of the d ep art­ ment of pedodontics and Doctor Jam iso n is professor of dentistry at the U n iversity of A la b a m a , M ed ica l C enter, School of Dentistry, Birm ingham , 35233. 1. N izel, A . E., and H arris, R. S. T h e effects of phos­ phates on experim ental dental caries: a literature review. J Dent Res (sup p l.) Nov.-D ec., 1964. 2. A ve rill, H. M ., and Bibby, B. G. A clinical test of additions of phosphate to the diet of children. J Dent Res (suppl.) 43 :1 150 Nov.-Dec., 1964. 3. Bibby, B. G., director, Eastm an D ental Center, Rochester, N .Y . Personal com m unication, 1966. 4. Ship, I. I., and M ickelsen, O. T h e effects o f c a l­ cium acid phosphate on dental caries in child ren : a co n ­ trolled clinical trial. J Dent Res (suppl.) 4 3 :1 1 4 4 Nov.Dec., 1964. 5. Stralfors, A . Th e effect of calcium phosphate on dental caries in school children. J Dent Res (s u p p l.) 4 3 :1 1 3 7 N ov.-D ec., 1964. 6. Finn, S. B., and Jam iso n , H. T h e role of a d ic a l­ cium phospate chewing gum in the control of hum an dental caries— 24-m onth results. Presented a t the Fédération D entaire Intern atio n ale, Tel A v iv , Israel, Ju ly , 1966.

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