The Lincoln Dental Caries Study II. The Effect of Acidulated Carbonated Beverages on the Incidence of Dental Caries

O R IG IN A L A R T IC L E S

T h e

L in co ln

II. T h e

d e n ta l c a rie s

effect of a c id u la te d

b e v e ra g e s

on

th e

stu d y c a rb o n a te d

in c id e n c e

Arnold D. Steinberg, DDS, MS, Chicago Stuart O. Zimmerman, PhD, Houston Max L. Bramer, DDS, Chicago

Mentally subnormal patients at the Lincoln State School participated in this three-year study on the effect of a daily consumption of carbonated bev­ erages on the incidence of dental caries. In addi­ tion to a diet that is similar to that consum ed'in normal populations, the experim ental group at LSS was given 12 oz of carbonated, acidulated beverage daily. This consumption did not produce a statistically significant increase in dental caries rates, except as the scores were analyzed by tooth surfaces. Scores for the buccal surfaces of max­ illary anterior teeth and for the buccal and buccolingual surfaces of the m andibular posterior teeth were statistically significant.

of d e n ta l c a rie s

It has long been known that a relationship exists between carbohydrate intake and dental car­ ie s .1"4 Studies involving experimental animals, as well as humans, have helped to clarify the nature of this relationship and have led to the conclusion that such factors as physical form, oral clearance, and the frequency o f betweenmeal consumption are o f more importance than the quantity o f sugar ingested.4-7 Experiments on animals reported in the sci­ entific literature indicate a lower cariogenicity of liquid food s.8,9 H owever, definite limitations must be set if a comparison is to be made with humans. Studies with humans, in which sugar solu­ tions were used as mouth rinses, have shown that production of acid in dental plaque de­ pressed the pH within a short time to a value that might dissolve enam el.1011 Ludwig and Bibby,12 using common foods, found less acid production in plaque after a cola beverage was drunk or apples were eaten than after mbre re­ tentive foods such as fig cookies or bread with jam were eaten. H owever, Caldwell and Bib­ b y ,13 measuring pH changes in small cavities, observed that the pH curves were not the same for cola beverages, fig cookies, and other foods as those observed in near neutral pH plaque on intact enamel surfaces. Bibby14 noted that sa­ liva may affect the plaque on intact enamel surJ A D A , V o l. 8 5 , J u l y 1 9 7 2 ■ 8 1

faces, but that in open cavities with the absence of a flow of saliva and the persistence of food, a different situation may exist. H e thus specu­ lated that foods that are involved in the initia­ tion o f caries may not be as important in expand­ ing the lesion. Published studies involving human saliva5,6 and mouth washings7,15 have, in general, shown that sugar in liquid form has a lower oral reten­ tion than sticky foods. Thus, there is some ex­ perimental evidence involving human beings that supports the theory that liquid carbohy­ drates are less cariogenic that carbohydrates in solid form. This, however, cannot be considered as the only determinant o f cariogenicity. Actual evidence of the relationship between physical form and degree of cariogenicity was obtained by Gustafsson and others.4 They con­ ducted a study at Vipeholm in an institution for mentally subnormal individuals (average age 35) and concluded: Increasing sugar consump­ tion produced an increase in caries; sugar in li­ quid form is less cariogenic than sugar contained in a more adhesive vehicle; and the more fre­ quently sugar is eaten between meals, the great­ er is the increase in caries. Research concerning the erosive effects of acidulated carbonated beverages has been limit­ ed to animals. Restarski and co-workers,16 M cCay and W ill,17 and M cClure18 all observed erosion and décalcification o f the teeth in ani­ mals drinking either acidulated-carbonated bev­ erages or fruit juices. Such observations have not been substantiated in any known controlled human studies. The evidence indicates that the physical form o f a sugar is an important factor in caries po­ tential. Therefore, it has becom e advisable to conduct more investigations in human popula­ tion groups of the effects o f sugars in various forms. Much has been theorized but little actu­ ally is known of the effects o f carbonated, bot­ tled beverages on the human dentition. In an effort to clarify these effects, a three-year study was conducted at the Lincoln State School, at Lincoln, 111.

M aterials and m ethods A group of 567 institutionalized, mentally sub­ normal, male and female individuals, ages 8 to 21, with an average initial age of 16.64, partici­ 8 2 ■ J A D A , V o l. 8 5 , J u l y 1 9 7 2

pated in this investigation. Lincoln State School (LSS) was selected because there was a history o f low turnover of patients at this school. A lso, the diet was the same throughout the institution (although all patients had spending money that was used mostly for candies and other confec­ tioneries, and between-meal snacking was as frequent as in a noninstitutionalized popula­ tion). Further, a low fluoride concentration, 0.4 parts per million (ppm), was found in the drink­ ing water. Residency at LSS was year-round. Finally, the staff was interested and willing to cooperate and ensure proper dispersal and utili­ zation of the bottled beverages. The clinical examinations were conducted by one examiner (A .D .S .) who used a mouth mir­ ror, explorer, portable dental light and chair, compressed air, and radiographs. Because it was difficult to obtain intraoral radiographs on the majority o f these patients, radiographs were taken with the use of occlusal film that was placed extraorally, for bitewing radiographs.19 A dental assistant recorded all data on specially designed examination sheets. Taped record­ ings o f the examination helped reduce possible recording errors. ' The criteria for qualification of patients were: an intelligence quotient o f 20 or more; sufficient cooperation to permit examination and to en­ sure beverage consumption; and constant resi­ dence while partaking o f the normal diet. The patients were assigned randomly into control and experimental groups. The groups were matched in respect to number o f filled and de­ cayed teeth, tooth surfaces, number o f missing teeth, and age. The quantity of carbonated beverage to be consumed was determined from data obtained from the U S Chamber of Commerce.20 It re­ ported that the highest beverage intake occurs between the ages o f 5 and 19, and that this pop­ ulation consumed an average of 6 oz per day per person. The patients in the present investiga­ tion received 12 oz per day per person. The pro­ cedure for dispensing the beverage was as fol­ lows: Each morning between breakfast and lunch, and each evening before bedtime, the ex­ perimental and control groups were removed to separate rooms. The experimental group was given 6 oz o f carbonated beverage; the control group was given 6 oz o f water. The patients re­ mained in the room until they had finished drink­ ing at their own pace. A weekly supply o f the

beverage was kept under lock at each cottage and a daily record was kept o f the beverage intake. N o one specific brand or type of carbonated beverage was used exclusively, but rather a variety o f flavors and brands was given in rota­ tion during the study. The fluoride content of the beverages was checked regularly, and was found to be 0.4 ppm. After the initial examination, the subsequent examinations were conducted every six months for the three-year duration of this study. All data were transferred to computer punch cards and were statistically evaluated (by S .O .Z .). The diet from LSS was evaluated by a dieti­ tian from the Northwestern University M ed­ ical School and was compared with the diets at the Glenwood School for Boys (GS) at Glenwood, 111, (an institution for boys); at the Illi­ nois Soldiers’ and Sailors’ Children’s School (ISS) at Normal, 111, (coeducational institution for orphan children); and at the Lincoln Public High School (LPH S) at Lincoln, 111. T hese schools were used as representative normal populations, o f a similar age range, for a com ­ parison o f caries rates with those at L SS .21

Table 3 shows how the diet at LSS compared with that at the other schools. A comparison o f these and other data collected by our dietitian showed that patients at LSS received a more than adequate diet and that it was by no means restricted in refined carbohydrates. T he Nation­ al Research Council recommends a daily diet­ ary allowance o f 2,800 calories.22 The data in Table 4 show that in the nonmongoloid population at LSS 62% of. the teeth lost by the control group and 48% o f the teeth lost by the experimental group were extracted because of carious lesions. In this type o f evalu­ ation, every tooth that was extracted during the three-year period was assessed and records were checked for indication o f caries at the examination immediately before extraction. If the tooth was carious on two or more surfaces or severely carious on one surface, the loss was attributed to caries. If the tooth had no active caries, it was considered lost because of other causes. A few teeth that had only slight caries involvement of a single surface at the prior ex­ amination were considered questionable. In the control and experimental groups in the mongoloid population, it was found that about 95% of

Table 1 ■ Age distribution of the total population at the initial examination at the Lincoln State School.

Results In this study, 567 subjects were examined ini­ tially. This total population (mongoloid and nonmongoloid) was divided, as evenly as pos­ sible, into a control group of 286 and an experi­ mental group o f 281 (Table 1 and 2). The total population (364 males and 203 females) also was randomly separated by sex between the control and experimental groups.

Age

8 9

10 11 12 13 14 15 16 17 18 19

20 21

I patients

Control group

Experimental group

1

1

5

5

10 8

10 10 10 20 11

18 7 15 27 38 31 31 32 33 25 281

18 35 31 37 33 30 35 286

Table 2 ■ Initial examination of the total population at the Lincoln State School. Data

Average age No. unerupted teeth per person No. missing teeth per person No. permanent teeth per person Clear surfaces per person DFT per person DFS per person DMFS per person DMFT per person All values are means

Control group (286 patients) 16.72

Experimental group (281 patients) 16.54

Combined (567 patients) 16 64

1.89 ± 0.245

1.96 ± 0.257

1.92 ± 0.177

1.94 ±0.160

1.91 ± 0.146

1.93 ± 0.108

24.17 ± 0.270 115.88 3.57 4.53 14.24 5.51

± 1 388 ± 0.224 ± 0 335 ± 0.944 ± 0.308

24.12 ± 0.264

24.15 ± 0.189

115.87 ± 1.344 3.57 t 0.233 4 50 ± 0.342 14.04 ± 0.868 5.48 ± 0.303

115.89 ± 0.966 3.58 ±0.161 4.53 ± 0.239 14.15 ± 0.557 5.50 ± 0.216

±standard error of the mean S t e i n b e r g — Z i m m e r m a n — B r a m e r : L IN C O L N D E N T A L C A R I E S S T U D Y ■ 8 3

Table 3 ■ Diet evaluation of protein, refined carbohydrates, and total calories per day, for LSS, GS, ISS, and

LPHS. Refined carbohydrates Meals and snacks

Lincoln State School (LSS) Glenwood School (GS) Illinois Soldiers’ and Sailors’ Children’s School (ISS) Lincoln Public High School (LPHS)

Snacks

Gm

Calories

Gm

Calories

Calories

Total calories intake

140 150

236 206

948 821

138 108

554 427

394 394

2,870 3,300

110

118 69

472 274

92 39

368 156

104 118

2,900 1,735

Protein (gm)

Institution

Meals

77.5

National Research Council

26 30

Recommended daily dietary allowance, average boys and girls

2,800

Table 4 ■ Comparison of number of teeth lost because of dental caries and other causes in the mongoloid and nonmongoloid population at LSS, three-year results. Control group

Experimental group

because of dental caries because of other causes

113 69

94 102

because of dental caries because of other causes

3 54

3 36

Population Nonmongoloid Teeth missing Teeth missing Mongoloid Teeth missing Teeth missing

Table 5 ■ Incremental DFT, DMFT, DFS, and DMFS scores of experimental group compared

with those of control group for the total population at LSS, at end of three years.

Score DFT DMFT D FS DMFS

Control group (132 patients) incremental score 2.69 4.06 4 37 10.25

± 0.268 ± 0.273 ± 0.386 ± 0.850

Experimental group (119 patients) incremental score

p Value

2.88 ± 0 252 4.55 ± 0.291 4.76 ±0.334 12.16 ± 1.142

Not significant Not significant Not significant Not significant

All values are means ± standard error of the mean.

the teeth were missing because o f other causes. Analysis revealed that in the mongoloid popu­ lation periodontal disease was almost always the cause of tooth loss. The effects of the consumption o f carbonated beverages on the total population are shown in Table 5. (Only data pertaining to those patients who remained in the study throughout the three years are included in Tables 4 to 9.) Although the various indexes indicated a slight increase in the caries scores of the experimental group versus the control group in the total population, these increases were not statistically significant. Similarly, as shown in Table 6, there was no sta­ tistically significant difference between the non­ mongoloid experimental and control groups. Table 7 shows the results of a comparison of incremental D F S and D M FS scores per child on the posterior teeth, anterior teeth, and vari­ 8 4 ■ J A D A , V o l. 8 5 , J u l y 1 9 7 2

ous tooth surfaces of patients in the control and experimental groups. This analysis does show significant differences (p<0.05) in the buccal D F S , buccal D M F S, and buccolingual D M FS. In a further evaluation, Table 8 shows the re­ sults of comparisons o f D M F S scores on vari­ ous surfaces that are separated in maxillary and mandibular, and anterior and posterior regions. For the maxillary anterior teeth, significant sta­ tistical levels (p<0.05) were reached only for the buccal surfaces. For the lower posterior teeth and for the combined evaluation of the lower anterior and posterior teeth, significant differences were attained for the buccal and buccolingual surfaces. Similarly, in the com­ parison of scores for all surfaces o f the man­ dibular posterior teeth and of the mandibular anterior and posterior teeth combined, signifi­ cant differences were found.

Table 6 ■ Incremental DFT, DMFT, DFS, and DMFS scores of experimental group compared

with those of control group for the nonmongoloid population at LSS, at end of three years. Control group incremental score (115 patients) DFT DMFT DFS DMFS

2.93 4.13 4.80 10.17

Experimental group incremental score (100 patients)

p Value

3.05 ± 0.268 4.74 ± 0.302 5.25 ± 0.285 12.67 ± 1.239

Not significant Not significant Not significant 0.10 >p >0.05

± 0.283 ±0.299 ± 0.422. ± 0.952

All values are means ± standard error of the mean

Table 7 ■ Comparison on incremental DFS and DMFS scores per child for the experimental and control groups in a nonmongoloid population at LSS, three-year results. Control group

Experimental group (100 patients) incremental score

(115patients)

incremental score Posterior teeth Anterior teeth Proximal surfaces Occlusal surfaces Buccolingual surfaces Buccal surfaces Total DFS

p Value

±0.345 ±0.172 ± 0.247 ± 0.227

4.62 ± 0.302 0.63 ±0.145 0.80 + 0.185 3.22 ± 0.214

Not significant Not significant Not significant Not significant

0.83 ±0.131 0.54 ± 0 094 4.80 ± 0.422

1.23 ±0.163 0.89 ±0.139 5.25 ± 0.351

0.10 >p >0.05 p < 0 05’ Not significant

8.13 2.04 3.45 3.49

±0.698 ± 0.411 ± 0.454 ± 0.250

9.91 ±0.895 2.76 ± 0.587 3 90 ± 0.527 4.24 ± 0.308

0.10 >p >0.05 Not significant Not significant 0.10 >p >0.05

3.23 ± 0.389 1.72 ± 0.201 10.17 ± 0.952

4.53 ± 0.526 2.49 ± 0.290 12.67 ±1.239

p < 0.05* p < 0.05’ 0.10 >p >0.05

4.12 0.68 1.13 2.84

DMFS score Posterior teeth Anterior teeth Proximal surfaces Occlusal surfaces Buccolingual surfaces Buccal surfaces Total DMFS

All values are means ± standard error of the mean. ’ Significantly different.

Table 8 ■ Comparison of DMFS scoresper child, bytooth surface, between experimental and control groups in a

nonmongoloid population at LSS, three-year results. Control group (115 patients)

Experimental group (100 patients) Anterior, Posterior Combined

Tooth surface Maxillary teeth Proximal surface Occlusal surface Buccolingual surface Buccal surface All surfaces Mandibular teeth Proximal surface Occlusal surface Buccolingual surface Buccal surface All surfaces

Posterior

Anterior, Posterior Combined

0.64 + 0.125 0.17 ±0.054 0.44 ±0.121 0.17 ±0.059 1.25 ±0 278

1.34 1.67 1.21 0.57 4.21

±0.238 ±0.160 ± 0.219 ±0.115 ± 0.515

1.97 ± 0.316 1.84 ±0.176 1.65 ± 0.281 0.74 ±0.143 5.46 ± 0.679

0.73 ±0.185 0.29 ± 0.090 0.84 ±0.186 0.43 ± 0.098* 1.86 ±0.449

1.28 ± 0.236 1.96 ±0.162 1.34 ±0.232 0.60 ± 0.115 4.58 ±0.518

2.01 ± 0.359 2.25 ± 0.206 2.18 ± 0.350 1.03 ±0.188 6.44 ± 0.848

0.38 ± 0.126 0.11 ±0.039 0.30 ± 0.079 0.18 ± 0.049

1.11 ±0.162

1.49 ±0.239 1.66 ±0.124 1.59 ± 0.198 0.99 ± 0.131

0.37 ±0.133 0.16 ± 0.065 0.37 ±0.127 0.20 ± 0.065 0.90 ± 0.306

1.52 ±0.213 1.83 ±0.144 1.98 ±0.226* 1.26 ±0.140* 5.33 ±0.472*

1.99 ±0.167 2.35 *0.269* 1.46 ± 0.165’ 6.23 ±0.582*

0.79±0.226

1.54 ±0.117 1.29 ±0.163 0.81 ±0.106 3.94 ±0.355

4.74±0.468

1.89±0.257

All values are means ± standard error of the mean. ’ Significant at 0.05 level when the experimental group is compared with the control group.

Table 9 and the Figure provide the oppor­ tunity for a final evaluation. T he three-year D M FS increase, by six-month increments, of those patients at LSS in the nonmongoloid group who were present for every examination can be assessed. The number of patients report­ ed in this comparison is less than that indicated by the other tables. This apparent discrepancy

is due to the absence of some patients at isolated examinations. Weighted regression analysis, with the use o f weights proportional to the in­ verse o f the variance at each six-month interval, was used to estimate the increase in D M F sur­ faces of the two groups. The regression equa­ tions were: control group, Y i= 0 .1 6 0 + 0.945X; experimental group, Y2=0.279 + 1.308X. Esti-

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Table 9 ■ Three-year increase of DMFS scores of nonmongoloid population at LSS, by six-month increments, for control and experimental groups. 6 months

12 months

18 months

24 months

30 months

36 months

0.77 ± 0.144 0.51 ± 0.166 0.64 ± 0.147

1.21 ± 0,180

1.16 ± 0.196

1.11 ± 0.170

1.56 ±0.224 2.10 ± 0.213 1.68 ± 0.220

2.19 ± 0.309 2.14 ± 0.206 1.99 ± 0.255

2.73 ± 0.363 2.98 ± 0.235 2.44 ± 0.230

3.50 ± 0.483 3.60 ± 0.274 3.18 ± 0.409

1.92 ± 0.355

3.48 ± 0.418

5.34 ± 0.494

6.32 ± 0.619

8.15 ±0.727

10.27 ± 1.002

0.85 ± 0.223 0.65 ± 0.157 0.87 ± 0.206

1.21 ±0.259 1.63 ± 0.220 1.64 ± 0.232

1.71 ± 0.308 2.44 ± 0.257 2.36 ± 0.328

2.18 ± 0.384 2.86 ± 0.372 2.67 ± 0.399

2.94 ± 0.503 3.78 ± 0.304 3.35 ± 0.495

3.71 ± 0.583 4.51 ± 0.331 4.41 ± 0.566

2.37 ± 0.472 4.48 ± 0.566 6.51 ± 0.775 All values are means ± standard error of the mean. 'Number of children In the control group, 95; in the experimental group, 87.

7.71 ± 0.922

10.07 ± 1.181

12.68 ± 1.356

Group____ Control group* Proximal surfaces Occlusal surfaces Buccolingual surfaces All surfaces xperimental group* Proximal surfaces Occlusal surfaces Buccolingual surfaces All surfaces

Experimental (beverage) group ■ Control group • Representation of six-month incremental relationship between time and buccolingual DMFS incremental scores for nonmon­ goloid population at LSS. Only data on those children present for entire three years are included.

mates o f the variance o f the slopes can be com­ puted in the usual manner.23 Difference of the slopes can then be tested by the Student’s t test:

t = b i - b2 V V ( b i ) + V ( b 2)

1.308 - 0.945 ---------------------------- =4.13 10 d.f. P<.01 V 0.00325 + 0.00922

Thus, the rate of mean caries attack in the ex­ perimental group is increasing at 1.31 new sur­ faces per year, and in the control group at the rate of 0.94 new surfaces per year; this differ­ ence is significant. N o assessm ent could be made as to when a significant difference be­ tween control and experimental groups became apparent.

86 ■

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For each individual surface type, the number o f surfaces that were carious at the first and second examination, sound at each examina­ tion, sound initially and subsequently carious, and carious initally and sound on reexamination was computed for each pair of examinations and was used to estimate the extent o f reversals by use o f the method o f L u.24 The probability of a correct diagnosis as calculated by this meth­ od ranged from a low o f 98.7% for the early ex­ aminations to 99.5% at the later examinations. With this degree o f accuracy and the corre­ spondingly small fraction of reversals, the dif­ ference between the true caries increment as calculated by Lu’s method and the increment with reversals included was only 1% to 2% of the incremental score. Because these differ­ ences were so small, the data have been report­ ed with the reversals included, without applica­ tion o f the correction.

Discussion A n initial study25 showed that some patients at LSS had a low caries index. In a subsequent in­ vestigation,21 this low index was compared with that of three groups o f normal children o f com­ parable ages. Two of the groups were institu­ tionalized populations (GS and ISS) and the third group was a noninstitutionalized popula­ tion (LPH S). It was shown that the nonmongo­ loid population at L SS, although mentally sub­ normal and possessing a delayed somatic growth rate, nevertheless showed a caries rate (incre­ mental D M FS or D M FT ) similar to that of both institutionalized and noninstitutionalized nor­ mal populations. It also was observed that in­ cremental scores including the “ missing” com­ ponent (D M FS or D M FT), rather than D F T or D F S were better indicators o f caries rate in the LSS population. Thus, in this investigation,

although w e will be expressing many o f our re­ sults without the “ missing” component, w e nevertheless believe that the D M FS or D M F T scores are the more reliable indexes. It should be noted that our initial examination included both mongoloid and nonmongoloid populations. This was done because w e were uncertain about inclusion o f the mongoloid pop­ ulation in such a study. Data from Table 4 and from our previous investigation21 showed that tooth loss because o f dental caries in the non­ mongoloid population at LSS was comparable to that in a normal population. Table 4 also showed that nearly 95% of teeth lost by the mongoloids who were included in this study were lost as the result of periodontal disease. Similar findings have been reported by Cohen and co-workers,26 who found severe periodon­ tal disease in 96% of young institutionalized mongoloids. In consideration o f the high tooth loss rate in mongoloids due to causes entirely unlike those in the nonmongoloid population, retention o f the mongoloid group in this study made a valid comparison in caries rates difficult. Specifically, the “ missing” component o f any score such as D M FS or D M F T would not re­ flect caries activity as would the other two com­ ponents. Therefore, it became necessary to drop the atypical mongoloid group from the study. This deletion in no way altered the bal­ ance between the control and experimental groups. D iet evaluations were made of all the involved children (Table 3). A t the three institutions (LSS, G S, ISS), diet charts were obtained di­ rectly from the staff dietitians. Information re­ garding the diet o f children attending LPHS was obtained from diet charts that were kept by the students them selves. Only 15 o f the 42 stu­ dents who received their second dental exam­ ination at LPH S returned the charts. H owever, the accuracy of these charts is doubted, and it is with reservation that w e include them. The LSS and GS diets were remarkably similar in protein content and in the intake o f refined car­ bohydrates, both at meals and in snacks; but, the GS diet offered more starches and showed a greater calorie intake. These and other data col­ lected by the dietitian showed that LSS patients were receiving a more than adequate diet, along with ample carbohydrates. The diets of all of the populations that were investigated appeared to be similar in cariogenicity; therefore diet was probably not a factor to be considered in the present undertaking.

The effects of the consumption o f carbonated beverages by the total population and for the nonmongoloid population at LSS, during three years, are shown in Table 5 and Table 6, respect­ ively. Although the various indexes indicated a slight increase in the caries scores of the ex­ perimental groups versus the control groups, these increases were not statistically signifi­ cant. The attrition o f patients during the threeyear study was greater than had been anticipat­ ed. Originally, there were 281 patients in the experimental group and 286 patients in the con­ trol group. A t the project’s termination, 119 re­ mained in the experimental group and 132 in the control group. This high loss was primarily caused by the opening of several new state insti­ tutions to which many of the patients trans­ ferred. In the normal use of bottled beverages, the anterior teeth are exposed more to the beverage than the posterior teeth. Similarly, the occlusal and buccolingual regions may receive greater exposure than the proximal regions. The caries increments for these regions are compared in Table 7. The D F S values indicate that the dif­ ferences for the buccolingual surfaces approach­ ed statistical significance, and that the differ­ ences for the buccal surfaces were significant. In the D M F S evaluation o f both the bucco­ lingual and buccal surfaces, a statistically sig­ nificant difference appeared between the con­ trol and the experimental groups. Table 8 shows the results o f a comparison of D M FS scores, by surfaces, in the maxillary and mandibular and anterior and posterior re­ gions. Significant statistical levels (p<0.05) were reached for the buccal surfaces of the max­ illary anterior teeth. Significant differences also were attained for the buccolingual surface eval­ uation o f the mandibular posterior teeth alone and for the mandibular anterior and posterior teeth combined. N o effect was found for the mandibular anterior region, indicating that the D M FS scores of the posterior buccolingual sur­ faces were raising the D M F S scores o f the antero-posterior combination to significant levels of difference. Significant findings also were shown for the buccal surfaces o f the mandibu­ lar posterior teeth, for the buccal surfaces o f the mandibular anterior and posterior teeth com ­ bined, for all the surfaces o f mandibular poster­ ior teeth, and for all surfaces of mandibular an­ terior and posterior teeth. It is believed that the significant effect seen on the D M F S scores for all the surfaces of mandibular teeth again was

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due to the scores for the buccolingual surfaces. This effect is strong enough to carry the indica­ tor for all surfaces to a significant level. The buccal surfaces of the upper anterior teeth and the buccolingual surfaces of the lower posterior teeth are those that have greatest contact with the beverage, and perhaps these areas are more susceptible to the action of the drink. An assessm ent o f teeth lost because of dental caries (Table 4) over the three-year study showed no statistically significant difference between the experimental and control groups. In the nonmongoloid population, 62% o f the teeth in the control group and 48% in the experimental group were missing because of dental caries. It is interesting that the experimental group has 14% fewer teeth lost because o f dental caries than the control group although this difference is not statistically significant. In the mongoloid population, 5% of the teeth were missing in the control group because of dental caries and 8% in the experimental group. Several reports have been published16'18 on erosions and décalcifications that were pro­ duced in various experimental animals by acid­ ulated beverages. N o erosion or décalcification effect could be observed during this three-year study o f humans. This difference in results be­ tw een studies with humans and animals may be due to these factors: The children had 6 oz of beverage twice daily; but in many experiments, animals are fed ad libitum and, therefore, the quantity and time of exposure to the beverage can vary greatly. The drinking habits o f experi­ mental animals may be totally different from those o f humans; the buffering capacity in the saliva and plaque may not be as effective in experimental animals as it is in man. The 12 oz of carbonated beverage that was given to the experimental group in the present study was calculated to be 34 gm of additional sugar per day per person. When this is added to the 98 gm (Table 4) obtained as snacks, it can be seen that the experimental group received 132 gm of snack carbohydrates or roughly a third more than the control group. In the Vipeholm study,4 300 gm o f sugar in solution per day was given to one group, only at meals. N o increase in caries was detected when this amount was given in liquid form; however, less sugar, which was given in a sticky form, produced a caries increase. It appears, therefore, that sugar in liquid form, given at meals, does not contact the teeth long enough to produce a measurable deleterious effect. 88

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The significant finding for the buccal sur­ faces o f the upper anterior teeth and for the buc­ cal and buccolingual surfaces of the lower post­ erior teeth indicates an effect on the teeth that is unusual and limited. In an explanation of this effect, it is necessary to consider which surfaces of the teeth maintain maximum contact with the beverage. Normal drinking seems to show that the buccal surfaces of the upper anterior teeth are the first to make contact with the beverage. Gravity and muscular action then seem to pass the liquid to the lower posterior teeth where the occlusal, buccal, and lingual surfaces are con­ tacted. T he slower clearance in this region most likely is a contributing factor. It thus appears that o f the surfaces presumed to be in maximum contact with a normally consumed beverage, only the occlusal surfaces o f the lower posterior teeth were unaffected in the present study. Recent dental caries research indicates that specific streptococci are the agents that are chiefly responsible for both plaque formation and smooth surface caries.27,28 Edwardsson and K iesse27 said that streptococci in both hu­ mans and hamsters “ induce very little caries in animals fed on a glucose diet. . .sucrose seems to be the factor which determines their impor­ tance in caries.” The patients in the present study have been shown to develop a greater amount o f plaque than a normal population group, because of poor oral hygiene.25 It is pos­ sible to speculate that this plaque, adhering to the buccal and lingual surfaces of the teeth, con­ tains a sufficient number o f caries-producing streptococci to be influenced by sucrose. Be­ cause plaque is not thought to form on the oc­ clusal surfaces o f teeth, the absence o f a carious effect on the occlusal surfaces of the lower post­ erior teeth becom es more reasonable. A carious effect was observed on those surfaces that can be assumed to have maximum contact with the beverage and that at the same time are pre­ sumed to contain caries-producing strepto­ cocci. This explanation of what was said to be an unusual and limited effect of carbonated bev­ erages is admittedly speculative. It may help to explain, however, the possible mechanisms by which such a selective effect might have oc­ curred in this population.

C onclusions A comparison o f the children at Lincoln State School with a normal population o f children,

both institutionalized and noninstitutionalized, showed that this mentally subnormal popula­ tion had a diet similar to the diets o f the normal populations. The three-year consumption of 12 oz o f acid­ ulated carbonated beverage daily by the men­ tally subnormal population at LSS did not pro­ duce a statistically significant increase in dental caries except when the incremental caries scores were analyzed by surfaces. This evaluation showed that only for the buccal surfaces o f the maxillary anterior teeth and for the buccal and buccolingual surfaces o f the mandibular p ost­ erior teeth were statistically significant levels of difference attained (p<0.05). It must be noted that this difference was just at the point o f sta­ tistical significance. Therefore, although a cari­ ous effect was obtained, it cannot be considered to be strong, despite three years o f daily con­ sumption o f acidulated beverages. Further­ more, it must be emphasized that the oral hy­ giene in this population was poor compared with that in a normal population. Thus, the re­ sultant accumulation of plaque on the smooth surfaces of the teeth may have been in som e way responsible for the findings. N o erosive or décalcification effect was ob­ served in the experimental group during the three years of this study.

This investigation was supported by a grant from the Illinois Bottlers Association through the cooperation of the Illinois State Dental Society, and by US Public Health Service Research Grants FR 00258 and FR 00254 from the Research Facilities and Resources Branch, National Institutes of Health, Bethesda, Md. The authors extend sincere gratitude to Dr. Joseph Albaum (past director) and Dr. Louis Balinson (present director) and his staff of the Lincoln State School whose assistance has made this project possible. Thanks is also extended to the following for their cooperation: Mr. Andrew J. Spelios, superintendent, Illinois Soldiers’ and Sailors’ Children’s School, Normal, III; Gen H.R. Wesphalinger, director, Glenwood School fo r Boys, Glenwood, III: and Mr. J.O. Hodgson, principal, Lincoln Com­ munity High School, Lincoln, III. The authors also wish to acknowledge the programming effort of Elsie Roenigk, Jac­ queline Wheat, and Judy Kautz for the computation in this pro­ ject. Doctor Steinberg is assistant professor in the department of periodontology at the University of Illinois College of Den­ tistry and is associate attending in the dental department, Michael Reese Hospital, Chicago. His address is 3724 Arcadia, Skokie, III 60076. Doctor Zimmerman is head of the department of biomathematics and associate professor of biomathematics at the University of Texas M.D. Anderson Hospital and Tumor Institute at Houston. Doctor Bramer is senior attending in the dental department at Michael Reese Hospital, Chicago.

1. Schour, I., and Massler, M. Dental caries experience in postwar Italy. I. Prevalence in various age groups. JADA 35:1 July 1947. 2. Sognnaes, R. Analyses of wartime reduction of dental caries in European children with special regard to observations in Norway. Am J Dis Child 75:792 June 1948. 3. Shaw, J.H. Effect of carbohydrate-free and carbohydratelow diets on the incidence on dental caries in white rats. J Nutr 53:151 May 1954. 4. Gustafsson, B.E., and others. Vipeholm dental caries study. Acta Odontol Scand 11:232 Sept 1954. 5. Volker, J.F., and Pinkerton, D.M. Some observations on the clearance of glucose from the oral cavity. J Dent Res 26:9 Feb 1947. 6 . Lundqulst, C. Oral sugar clearance. Its influence on den­ tal caries activity. Odontol Revy (Supp) 3:121 1952. 7. Bibby, B.G.; Goldberg, H.J.V.; and Chen, E. Evaluation of caries-producing potentials o f various foodstuffs. JADA 42:491 May 1951. 8 . Haldi, J., and others. Relative cariogenicity of sucrose when ingested in solid form and in solution by the albino rat. J Nutr 49:295 Feb 1953. 9. Navia, J.M. Evaluation of nutritional and dietary factors that modify animal caries. J Dent Res 49:1213 Nov-Dee 1970. 10. Stephan, R.M. Changes in hydrogen-ion concentration on tooth surfaces and in carious lesions. JADA 27:718 May 1940. 11. Muntz, J.A. Production of acids from glucose by dental plaque material. J Biol Chem 148:225 April 1943. 12. Ludwig, T.G., and Bibby, B.G. Acid production from d if­ ferent carbohydrate foods in plaque and saliva. J Dent Res 36: 56 Feb 1957. 13. Caldwell, R., and Bibby, B.G. Effect of foodstuffs on the pH of dental cavities. JADA 57:685 Nov 1958. 14. Nizel, A.E. The science of nutrition and its application in clinical dentistry, ed 2. Philadelphia, W.B. Saunders Co., 1966, p 324. 15. Ludwig, T.G., and Bibby, B.G. Further observations upon the caries-producing potentials of various foodstuffs. J Dent Res 36:61 Feb 1957. 16. Restarski, J.S.; Gortner, R.A.; and McCay, C.M. Effect of acid beverages containing fluorides upon the teeth of rats and puppies. JADA 32:668 June 1945. 17. McCay, C.M., and Will, L. Erosion of molar teeth by acid beverages. J Nutr 39:313 Nov 1949. 18. McClure, F.J. The destructive action in vivo of dilute acid and acid drinks and beverages on rats' molar teeth. J Nutr 26: 251 Sept 1943. 19. Steinberg, A.D., and Bramer, M. New concept in extra and intraoral radiographs. J Dent Child 31:34 (1st quarter) 1964. 20. Personal communications. Chicago, US Department of Commerce. 21. Steinberg, A.D. A comparative study of caries in mentally subnormal and normal individuals. Proceedings of the First In­ ternational Congress on Dentistry for the Handicapped. Phil­ adelphia, Mitchell Press. To be published. 22. US Department of Argriculture. In Home Garden Bull (No. 72) Sept 1964. 23. Brownlee, K.A. Statistical theory and methodology in science and engineering. New York, John Wiley Co., 1961, p 288. 24. Lu, K.H. A critical evaluation of diagnostic errors, exam­ iner's accuracy and true increment in caries experience assess­ ment by a probabilistic model. Abstracted, IADR Program and Abstracts No. 251 March 1968. 25. Steinberg, A.D., and Zimmerman, S.O. The Lincoln den­ tal caries study. I. The incidence of dental caries in persons with various mental disorders. JADA 74:1002 April 1967. 26. Cohen, M „ and others. Oral aspects of mongolism. Part I. Periodontal disease in mongolism. Oral Surg 14:92 Jan 1961. 27. Edwardsson, S., and Kiesse, B. Human streptococci and caries in hamsters fed diets with sucrose or glucose. Arch Oral Biol 12:1015 Aug 1967. 28. Keyes, P. Research in dental caries. JADA 76:1357 June 1968.

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