Salivary Streptococcus mutans levels in patients before, during, and after orthodontic treatment Richard G. Rosenbloom, DMD,* and Norman Tinanoff, DDS, MS** Farmington, Conn.
The purpose of this study was to evaluate salivary Streptococcus mutans levels in patients before, during, and after orthodontic treatment. S. mutans levels were significantly elevated during active treatment. However, when sampled 6 to 15 weeks into the retention phase of treatment, the microbial levels decreased significantly to levels comparable to age-matched untreated controls. In addition, patients who were no longer wearing any retention appliances had S. mutans levels similar to those subjects sampled in the retention phase of treatment as well as to subjects in age-matched control groups. The findings of the study suggest that orthodontic treatment does not result in any long-term elevations of S. mutans levels. (AM J ORTHODDENTOFACORTHOP 1991 ;100:35-7.)
P a t i e n t s who undergo orthodontic therapy have oral ecologic changes such as a low pH environment, increased retentive sites for Streptococcus mutans, and increased retention of food particles, which may lead to increased proportions and absolute numbers of salivary S. mutans. L~ These changes m a y be responsible, in part, for the observations of postorthodontic-treatment decalcification in certain cases. 7'8 It is not clear from previous studies, however, whether the level o f S. mutans remains elevated after orthodontic therapy. I f the elevated infection level that is associated with orthodontic appliances leads to an elevated infection level after appliances are removed, then patients m a y continue to be at increased risk for development of caries after orthodontic therapy is discontinued. Understanding o f the S. mutans levels in patients before, during, and after orthodontic therapy m a y help to determine caries risk levels and may thus lead to appropriate preventive or antimicrobial therapy.
METHODS AND MATERIALS The 75 subjects included in this essentially cross-sectional study were assigned to five groups, each of which consisted of 15 subjects. The subjects selected were either current or
From the Department of Orthodontics, University of Connecticut Health Center, Farmington, Conn, Submitted in partial fulfillment of the requirements for a certificate in orthodontics, *In private practice. Former Resident. Department of Orthodontics, University of Connecticut Health Center. **Professor, Department of Pediatric Dentistry, University of Connecticut Health Center. 811/16107
previous patients from a dental school orthodontic clinic. The "active treatment" group comprised subjects, 12 to 15 years of age, who were in active orthodontic treatment with attachments on at least 20 teeth. The "retention" group consisted of the patients in the "active treatment" group who were longitudinally followed up into the retention phase of their treatment. They had fixed and/or removable retainers. The "postretention" group comprised subjects, 16 to 21 years of age, who had received orthodontic care but who had not worn intraoral appliances of any kind in the previous 4 to 18 months. The "12- to 15-year-old untreated controls" were subjects with untreated malocclusions who served as a control group for the "active treatment" and "retention" groups. The "16- to 21-year-old untreated controls" were subjects with untreated malocclusions who served as a control group for the "postretention" group (Table I). Exclusion criteria included the use of oral antimicrobials or antibiotics within the past 3 months, the presence of prosthodontic appliances, or significant systemic disease. The microbial samples were obtained after the subjects had chewed on a piece of paraffin wax for 1 minute to stimulate salivary flow. After collection of each sample, 0,5 ml of saliva was transferred to a tube that contained 4.5 ml of reduced transport medium. In the laboratory the sample was sonicated for 1 minute, vortexed for 30 seconds to disperse the bacteria, and then serially diluted to 10-L From each of the dilutions, 25 mieroliters were spotted in triplicate, each on one third of the surface of a selective and nonselective growth medium. For determination of the number of S. mutans, a selective medium that consisted of Mitis salivarius agar, which contained 20% sucrose and was supplemented with 0.2 U/ml bacitracin (Sigma Chemical, St. Louis, Mo.) was used (MSB agar)? For determination of the total number of aerobic bacteria, a 10% sheep blood agar plate was used. Both the blood agar plates and the MSB agar plates were incubated in a carbon dioxide-rich environment over periods of 24 and 48 hours. 35
36
Rosenblooln and Tinanoff
Am. J. Orthod. Demofac. Orthop. July 199I 12lO 8
o
6
¢1 w
0
Untreated " Active Retention PostUntreated Controls Treatment (Age 12-15) Retention Controls (Age 12-15) (Age 12-15) (Age 16-21)(Age 16-21)
Fig. 1. Mean ( + SEM) S. mutans per milliliter of saliva in subjects with or without orthodontic treatment.
5.
4. 3.
u~
2.
1'
0
Untreated Active Retention PostUntreated Controls Treatment (Age 12-15) Retention Controls (Age 12-15) (Age 12-15) (Age 16-21)(Age 16-21)
Fig. 2. Percentage of S. mutans in total salivary flora in subjects with and without orthodontic treatment.
respectively. The plates that had from 20 to 100 colonyforming units (CFUs) were counted at a magnification of X 20.0n!y those colonies with morphologic characteristics of S. mutans were counted on the MSB plates. The total salivary CFUs obtained from the blood ag.ar plates were used in the denominator to determine the percentage of S. mutans colonies, which was calculated as S. mutans CFUs/total salivary CFUs x 100. After the bacterial counts were log-transformed, the comparisons among the groups (both total number of S. mutans and percentage of S. mutans) were performed by analysis of variance. The least significant difference test was used to determine significant differences between groups. RESULTS
The results indicated that those subjects in the "active treatment" group had significantly higher ( p
0.05) between the "retention" and "postretention" groups. Furthermore, there was no difference (p > 0.05) between the "postretention" subjects and those untreated
Volume 100
Salivaly S, mutans levels in orthodontic treatment
Number l
37
T a b l e I. Distribution and description of study populations Treatment
I Age J (yr)
N
Untreated control Active treatment Retention
12-16 12-16 12-16
15 15
Postretention Untreated control
16-21 16-21
15 15
15
Description
Had bands/brackets on at least 20 teeth Same subjects as active treatment group from whom saliva was also collected 6-15 weeks after debanding No appliances worn for 4-18 months
subjects of the same age in either total numbers or percentage of S. m u t a n s . DISCUSSION The elevated levels o f S . m u t a n s in the "active treatment" subjects confirms other reports 36 that show patients who undergo orthodontic treatment have elevated levels of S. mutans. Likewise, the proportional shift in t h e microbial population characterized by the elevated percentage of S. m u t a n s in those same subjects is in agreement with the findings o f Corbett et a l ) Such an alteration in the oral flora may be a factor in the increase in enamel decalcification (white spot lesions) often seen during orthodontic therapy. 7's Ideally, in a study of this nature, the experimental a n d control subjects should be followed up longitudinally, and samples o f their saliva should be collected at defined intervals before, during, and after orthodontic therapy. However, the time required to perform such a study would be at least 4 years. Such a longitudinal study may also have disadvantages because of "drift" o f experimental techniques over protracted time periods. The important observation o f a reduction in S. m u t a n s levels after full appliance removal was, in fact, carried out in a longitudinal manner. Those subjects in the "active treatment" group were followed up, and a second saliva sample was collected from each subject during the "retention" phase of treatment. The elapsed time interval between collection of samples varied from 6 to 15 weeks after removal of all bands and bonded attachments. Although elevated levels of S. m u t a n s originally existed in these subjects relative to an age-matched control group, both the number and the percentage o f S. m u t a n s decreased fourfold from those values o f 6 to 15 weeks after debanding and delivery of retention appliances, In the retention phase the levels of S. m u t a n s did n o t differ significantly from those in the untreated control subjects, which suggests that S. m u t a n s levels tend to decrease to pretreatment levels after active treatment. T h e rapid decline in S. m u t a n s levels in subjects with retainers was surprising since other studies have shown
that clasps and denture bases in removable partial dentures m a y increase levels of S. m u t a n s . ~o In addition to the large decrease in S. m u t a n s levels after removal of fixed appliances, no difference was o b s e r v e d between the "postretention" subjects and the age-matched untreated controls. Thus both o f these findings suggest that fixed orthodontic appliances m a y play a small role in permanently elevating S. m u t a n s levels, and antimicrobial therapy may not be necessary to reduce the elevated levels after discontinuation of active orthodontic therapy. REFERENCES 1. Balenseifen JW, Madonia JV. Study of dental plaque in orthodontic patients. J Dent Res 1970;49:20-3, 2. Chatterjee R, Kleinberg I. Effect of orthodontic band placement on the chemicalcomposition of human incisor tooth plaque. Arch Oral Biol 1979;24:97-I00. 3. Corbett JA, Brown LR, Keene HI, Hot-ton IM. Comparison of Streptococcus mutans concentration in banded and non-banded orthodontic patients. J Dent Res 1981;60:1936-42. 4. Matt[ngly JA, Sauer GJ, Yancey JM, Arnold RR. Enhancement of Streptococcus mutans colonization by direct bonded appliances. J Dent Res 1983;62:1209-11. 5. Scheie AA, Arnesberg P, Krogstad O. Effects of orthodontic treatment on prevalence of Streptococcus mutans in plaque and saliva. Scand J Dent Res 1984;92:211-7. 6. Vierrou AM, Manwell MA, Zameck RL, Sachdeva R, Tinanoff N. Control of Streptococcus mutans with topical fluorides in patients undergoing orthodontic treatment. J Am Dent Assoc 1986;113:644-6. 7. Gorelick L, Geiger AM, Gwinnet AJ. Incidence of white spot formation after banding and bonding. AM J ORTHOD1982;81" 93-8. 8. StratemannMW, ShannonlL. Controlofdecalcificationlnorthodontic patients by daily self-administered application of a water free 0.4% SnF2 gel. AM J ORTrtOD 1974;66:273-9. 9. Gold DG, Jordan HV, van Houte J. A selective medium for Sn'eptococcus mutans. Arch Oral Biol 1973;18:1357-64. 10. Mihalow DM, Tinanoff N. The influence of removable partial dentures on the levels of Streptococcus mutans in saliva. J Prosthet Dent 1988;59:49-51. Reprint requests to:
Dr. N, Tinanoff Department of Pediatric Dentistry University of Connecticut Iteaith Center Farmington, CT 06032
The purpose of this study was to evaluate salivary Streptococcus mutans levels in patients before, during, and after orthodontic treatment. S. mutans levels were significantly elevated during active treatment. However, when sampled 6 to 15 weeks into the retention phase of treatment, the microbial levels decreased significantly to levels comparable to age-matched untreated controls. In addition, patients who were no longer wearing any retention appliances had S. mutans levels similar to those subjects sampled in the retention phase of treatment as well as to subjects in age-matched control groups. The findings of the study suggest that orthodontic treatment does not result in any long-term elevations of S. mutans levels. (AM J ORTHODDENTOFACORTHOP 1991 ;100:35-7.)
P a t i e n t s who undergo orthodontic therapy have oral ecologic changes such as a low pH environment, increased retentive sites for Streptococcus mutans, and increased retention of food particles, which may lead to increased proportions and absolute numbers of salivary S. mutans. L~ These changes m a y be responsible, in part, for the observations of postorthodontic-treatment decalcification in certain cases. 7'8 It is not clear from previous studies, however, whether the level o f S. mutans remains elevated after orthodontic therapy. I f the elevated infection level that is associated with orthodontic appliances leads to an elevated infection level after appliances are removed, then patients m a y continue to be at increased risk for development of caries after orthodontic therapy is discontinued. Understanding o f the S. mutans levels in patients before, during, and after orthodontic therapy m a y help to determine caries risk levels and may thus lead to appropriate preventive or antimicrobial therapy.
METHODS AND MATERIALS The 75 subjects included in this essentially cross-sectional study were assigned to five groups, each of which consisted of 15 subjects. The subjects selected were either current or
From the Department of Orthodontics, University of Connecticut Health Center, Farmington, Conn, Submitted in partial fulfillment of the requirements for a certificate in orthodontics, *In private practice. Former Resident. Department of Orthodontics, University of Connecticut Health Center. **Professor, Department of Pediatric Dentistry, University of Connecticut Health Center. 811/16107
previous patients from a dental school orthodontic clinic. The "active treatment" group comprised subjects, 12 to 15 years of age, who were in active orthodontic treatment with attachments on at least 20 teeth. The "retention" group consisted of the patients in the "active treatment" group who were longitudinally followed up into the retention phase of their treatment. They had fixed and/or removable retainers. The "postretention" group comprised subjects, 16 to 21 years of age, who had received orthodontic care but who had not worn intraoral appliances of any kind in the previous 4 to 18 months. The "12- to 15-year-old untreated controls" were subjects with untreated malocclusions who served as a control group for the "active treatment" and "retention" groups. The "16- to 21-year-old untreated controls" were subjects with untreated malocclusions who served as a control group for the "postretention" group (Table I). Exclusion criteria included the use of oral antimicrobials or antibiotics within the past 3 months, the presence of prosthodontic appliances, or significant systemic disease. The microbial samples were obtained after the subjects had chewed on a piece of paraffin wax for 1 minute to stimulate salivary flow. After collection of each sample, 0,5 ml of saliva was transferred to a tube that contained 4.5 ml of reduced transport medium. In the laboratory the sample was sonicated for 1 minute, vortexed for 30 seconds to disperse the bacteria, and then serially diluted to 10-L From each of the dilutions, 25 mieroliters were spotted in triplicate, each on one third of the surface of a selective and nonselective growth medium. For determination of the number of S. mutans, a selective medium that consisted of Mitis salivarius agar, which contained 20% sucrose and was supplemented with 0.2 U/ml bacitracin (Sigma Chemical, St. Louis, Mo.) was used (MSB agar)? For determination of the total number of aerobic bacteria, a 10% sheep blood agar plate was used. Both the blood agar plates and the MSB agar plates were incubated in a carbon dioxide-rich environment over periods of 24 and 48 hours. 35
36
Rosenblooln and Tinanoff
Am. J. Orthod. Demofac. Orthop. July 199I 12lO 8
o
6
¢1 w
0
Untreated " Active Retention PostUntreated Controls Treatment (Age 12-15) Retention Controls (Age 12-15) (Age 12-15) (Age 16-21)(Age 16-21)
Fig. 1. Mean ( + SEM) S. mutans per milliliter of saliva in subjects with or without orthodontic treatment.
5.
4. 3.
u~
2.
1'
0
Untreated Active Retention PostUntreated Controls Treatment (Age 12-15) Retention Controls (Age 12-15) (Age 12-15) (Age 16-21)(Age 16-21)
Fig. 2. Percentage of S. mutans in total salivary flora in subjects with and without orthodontic treatment.
respectively. The plates that had from 20 to 100 colonyforming units (CFUs) were counted at a magnification of X 20.0n!y those colonies with morphologic characteristics of S. mutans were counted on the MSB plates. The total salivary CFUs obtained from the blood ag.ar plates were used in the denominator to determine the percentage of S. mutans colonies, which was calculated as S. mutans CFUs/total salivary CFUs x 100. After the bacterial counts were log-transformed, the comparisons among the groups (both total number of S. mutans and percentage of S. mutans) were performed by analysis of variance. The least significant difference test was used to determine significant differences between groups. RESULTS
The results indicated that those subjects in the "active treatment" group had significantly higher ( p
0.05) between the "retention" and "postretention" groups. Furthermore, there was no difference (p > 0.05) between the "postretention" subjects and those untreated
Volume 100
Salivaly S, mutans levels in orthodontic treatment
Number l
37
T a b l e I. Distribution and description of study populations Treatment
I Age J (yr)
N
Untreated control Active treatment Retention
12-16 12-16 12-16
15 15
Postretention Untreated control
16-21 16-21
15 15
15
Description
Had bands/brackets on at least 20 teeth Same subjects as active treatment group from whom saliva was also collected 6-15 weeks after debanding No appliances worn for 4-18 months
subjects of the same age in either total numbers or percentage of S. m u t a n s . DISCUSSION The elevated levels o f S . m u t a n s in the "active treatment" subjects confirms other reports 36 that show patients who undergo orthodontic treatment have elevated levels of S. mutans. Likewise, the proportional shift in t h e microbial population characterized by the elevated percentage of S. m u t a n s in those same subjects is in agreement with the findings o f Corbett et a l ) Such an alteration in the oral flora may be a factor in the increase in enamel decalcification (white spot lesions) often seen during orthodontic therapy. 7's Ideally, in a study of this nature, the experimental a n d control subjects should be followed up longitudinally, and samples o f their saliva should be collected at defined intervals before, during, and after orthodontic therapy. However, the time required to perform such a study would be at least 4 years. Such a longitudinal study may also have disadvantages because of "drift" o f experimental techniques over protracted time periods. The important observation o f a reduction in S. m u t a n s levels after full appliance removal was, in fact, carried out in a longitudinal manner. Those subjects in the "active treatment" group were followed up, and a second saliva sample was collected from each subject during the "retention" phase of treatment. The elapsed time interval between collection of samples varied from 6 to 15 weeks after removal of all bands and bonded attachments. Although elevated levels of S. m u t a n s originally existed in these subjects relative to an age-matched control group, both the number and the percentage o f S. m u t a n s decreased fourfold from those values o f 6 to 15 weeks after debanding and delivery of retention appliances, In the retention phase the levels of S. m u t a n s did n o t differ significantly from those in the untreated control subjects, which suggests that S. m u t a n s levels tend to decrease to pretreatment levels after active treatment. T h e rapid decline in S. m u t a n s levels in subjects with retainers was surprising since other studies have shown
that clasps and denture bases in removable partial dentures m a y increase levels of S. m u t a n s . ~o In addition to the large decrease in S. m u t a n s levels after removal of fixed appliances, no difference was o b s e r v e d between the "postretention" subjects and the age-matched untreated controls. Thus both o f these findings suggest that fixed orthodontic appliances m a y play a small role in permanently elevating S. m u t a n s levels, and antimicrobial therapy may not be necessary to reduce the elevated levels after discontinuation of active orthodontic therapy. REFERENCES 1. Balenseifen JW, Madonia JV. Study of dental plaque in orthodontic patients. J Dent Res 1970;49:20-3, 2. Chatterjee R, Kleinberg I. Effect of orthodontic band placement on the chemicalcomposition of human incisor tooth plaque. Arch Oral Biol 1979;24:97-I00. 3. Corbett JA, Brown LR, Keene HI, Hot-ton IM. Comparison of Streptococcus mutans concentration in banded and non-banded orthodontic patients. J Dent Res 1981;60:1936-42. 4. Matt[ngly JA, Sauer GJ, Yancey JM, Arnold RR. Enhancement of Streptococcus mutans colonization by direct bonded appliances. J Dent Res 1983;62:1209-11. 5. Scheie AA, Arnesberg P, Krogstad O. Effects of orthodontic treatment on prevalence of Streptococcus mutans in plaque and saliva. Scand J Dent Res 1984;92:211-7. 6. Vierrou AM, Manwell MA, Zameck RL, Sachdeva R, Tinanoff N. Control of Streptococcus mutans with topical fluorides in patients undergoing orthodontic treatment. J Am Dent Assoc 1986;113:644-6. 7. Gorelick L, Geiger AM, Gwinnet AJ. Incidence of white spot formation after banding and bonding. AM J ORTHOD1982;81" 93-8. 8. StratemannMW, ShannonlL. Controlofdecalcificationlnorthodontic patients by daily self-administered application of a water free 0.4% SnF2 gel. AM J ORTrtOD 1974;66:273-9. 9. Gold DG, Jordan HV, van Houte J. A selective medium for Sn'eptococcus mutans. Arch Oral Biol 1973;18:1357-64. 10. Mihalow DM, Tinanoff N. The influence of removable partial dentures on the levels of Streptococcus mutans in saliva. J Prosthet Dent 1988;59:49-51. Reprint requests to:
Dr. N, Tinanoff Department of Pediatric Dentistry University of Connecticut Iteaith Center Farmington, CT 06032
