Orthodontic positioner used for home fluoride treatments

Orthodontic positioner used for home Jluoride treatments Philip

A.

Trask,

D.D.S.,

M.S.*

Santa Monica, CaZif.

A

n orthodontic positioner that is typically used at the close of orthodontic treatment provides an excellent vehicle for daily home fluoride application. After band removal, the opened interproximal spaces provide a rare opportunity to fluoridate the otherwise nonaccessible tight proximal enamel surfaces. This will also aid in the treatment of any “white” lesions noticed circumferentially after band removal. Even if a positioner is not used after band removal, home fluoride trays or merely fluoride rinses can be used to fluoridate the interproximal and other enamel surfaces. Topical fluoride applications have been shown to reduce caries incidence drastically and remineralize decalcified enamel. Dispensing or prescribing standard topical fluoride gels with the positioner requires very little added time and will greatly benefit the patient. Fluoride has been one of the most widely studied chemicals in the history of mankind. But even today there exists doubt as to the efficacy of universal systemic fluoridation via municipal water supplies. However, the use of topical fluoride enjoys almost no opposition. The dental literature is full of articles demonstrating drastic reduction in caries incidence as a result of topical applications. The orthodontic patient exhibits a decrease in the normal self-cleansing activity of the mouth. Appliances act as food traps, and oral hygiene is more difficult. In his efforts to maintain and protect the dentition, the orthodontist can readily make use of topical fluorides. Topical

effect

When immature ment, the clinically

on the

enamel

a tooth erupts into the oral cavity, the enamel surface and permeable. The longer it remains in contact with the more mature and less porous the surface becomes.’ This by decreased permeability and increased resistance to

*Assistant Clinical Professor Angeles, Calif. ; in private Calif. 90401.

in Pediatric practice at

Dentistry, 520 Arizonia

UCLA Ave.,

School Suite

is relatively oral environis evidenced caries as the

of Dentistry, Los C. Santa Monica,

677

tooth age~.~ Fluoride ions, along with other ions, bclcaomo incorl)oratc~d in the so-called polished surface layer.‘, :( Therefore, young teeth benefit, the most, from topical applications of fluoride. Teeth which originally calcify in fluoridated arcas already contain fluoride throughout the enamel layer. The concentration of Auoridc in the csicrnal “polished” surface layer can be greatly increased by added contact wit,11 fluoride. Fluoride uptake by enamel is related to the amount of fuoridr already present, to the age of the teeth, and to the frequency of exposure to topical fluoritlc.‘, j This is why topical fluoride treatments are indicated in finoridatecl areas. Fluoride treatments, following prophylaxis, have been reported to tIecrease caries incidence by 21 to 54 per cent in fluoridated areas.“-!’ Iictacnt studies have also shown that applying fluoride to freshly cut enamel walls in cavity prepa,rations will decrease the enamel solubility from ‘75 to 97 per cent. Placing fluoride in a cavity preparation before insertion of the amalgam restorat,ion has been shown to decrease recurrent caries by 61 per cent. Some clinic*ians have also promoted the swabbing of exposed teeth with fluoride solution during rubber dam 01 cotton roll isolation. With the teeth dry, clean, and isolated during operative procedures, there is an excellent opportunity for maximum fluoride uptake. Remineralizing

decalcified

enamel

Topical application of fluoride has been shown to remineralize enamel lesions and subsurface layers of dentin which are demineralizccl but not infected? Typically, this has been explored in an effort to rcmineralize white-spot lesions noticed on the mesial proximal of permanent first molars after exfoliation of deciduous second molars.11-14 Topical fluoride may prove helpful in treating decalcified enamel seen adjacent to orthodontic bands or at the cervical areas when there has been a historp of plaque accumulation. Frequency

of application

When topical fluoride is applied to the enamel surface, OINJ of the initial reactions is the formation of calcium fluoride and fluoride-containing complexes on the surface of the enamel.*” The actual incorporation of fluoritlcs into the enamel as fluorapatitc is a much slower pro(*css.1”-20 Immediately following a topical fluoride treatment, much of the superficial fluoride compounds is washed away by the saliva before the fluoride can be incorporatctl as fluorapatite.“. Ii The more a tooth is exposed to fluoride, the greater the concentration of fluoride in the cxtcrnal surface layer of the enamel aIl(l the grcat,er t,hc caries protection.“, 16,‘: This is borne out by clinical studies which show that semiannual fluoride treatments afford greater caries protection than just,‘ annual treatment@ lo and chewing fluoride tablets (topicdal effect) affords greater caries protection t,han ,just swallowing the tablets with no contact between the fluoride and the erupted enamel surfaces. *’ The high-frequency topical effect may be one explanation for the greater caries protection of fluoridated water supplies (continued topical fluoride from liquids and footls) versus prescribed fluoride supplements.21 The concentration of fluoride in the surface enamel is related to the amount of exposure to fluoride and the age of the tooth.”

Positioner

used for home fluoride

treihnents

679

Practically speaking, it appears that the most important place for the fluoride to be when the tooth initially encounters the caries attack is at the external surface. Topical fluoride penetrates only 30 microns into the ename1.2, ” Once the active carious lesion enters the enamel layer, it will continue to progress, whether or not there is fluoride in the enamel apatite. Clinically, therefore, it is advantageous to expose the teeth to fluoride often in order to increase the caries resistance of the surface enamel. Oral

rinses

and

individual

tmys

with

fluoride

In an effort to increase the frequency of exposure of the enamel surface to fluoride, many methods have been developed. 23 Incorporation of small amounts of fluoride in toothpaste has been popular for years. Daily or weekly rinsing with fluoride solution is another technique which has been successfully explored. The use of individual trays for home fluoride application has also been shown to be highly effective.24 These trays are made in the same manner as that used to produce an athletic mouth guard. An individual tray is fabricated directly in the mouth with thermoplastic vinyl material or indirectly from dental casts with a variety of materials. The most popular is a thermoplastic vinyl material which is first heated, vacuum adapted over the cast, then trimmed with scissors at the necks of the teeth. This produces a well-adapted, comfortable tray. With patients wearing fixed orthodontic appliances, a cast made from an alginate impression (with all appliances in place) is fabricated in the same fashion. This pliable tray easily fits over the teeth and appliances and is used for home fluoride applications during orthodontic treatment. At the end or close of orthodontic treatment, when the appliances are removed, typically an orthodontic positioner is used for final alignment and space closure. This positioner can serve an added function as a vehicle for home fluoride treatment. The fluoride used in the home-tray procedures is the same as is used for topical application in the dental office, usually 1.25 per cent acidulated phosphate fluoride gel. Acidulated phosphate fluoride preparations for topical use appear to provide greater uptake than stannous or sodium fluoride. They have a better taste, have greater stability, and do not stain the enamel surface.“’ I9 Convenient 4 or 8 ounce squeeze plastic dispenser bottles can be readily obtained from dental suppliers or from the neighborhood pharmacist. If the patient is already using an orthodontic positioner, athletic mouth guard, etc., it is a simple matter to prescribe or dispense fluoride gel for home USC. Recommended

procedures

and

patient

instructions

1. Each night (or weekly) thoroughly brush and floss the teeth. Place a small amount of fluoride gel in the occlusal portions of the orthodontic positioner. 2. Seat the positioner (or tray) over the teeth and leave in place for 5 minutes or longer. 3. Expectorate excess saliva. Do not swallow. Do not rinse mouth after treatment.

680

Trask

Excess

fluoride

Any fluoride which exudes out of the tray on insertion is wasted. The patient soon learns the correct amount of fluoride gel to place in the tray. During the fluoride procedure the patient is cautioned against swallowing the fluorideladen saliva. Occasionally, nausea may develop immediately following ingestion of small amounts of fluoride. This is due to the combination of the fluoride ion with hydrogen ions in the gastric juices to form the stomach-irritating hydrofluoric acid.25 If this occurs, commonly available antacids will neutralize the acid and calm the stomach. Not overloading the tray and not swallowing t.he fluoride-laden saliva will prevent this problem. Discussion

Ever since the beginning of topical application of fluoride, a question has been raised as to whether or not fluoride would reach the proximal surface where many caries begin. Many techniques have been proposed for getting the fluoride interproximally, such as thoroughly drying the teeth and using capillary action to draw the fluoride solution interproximally; use of floss during treatment; and the use of rubber diaphragmed trays to force the fluoride interproximally. The use of fluoride solution rather than gel has been promoted because of the gel’s high viscosity and resistance to interproximal flow. After band removal, at the close of active orthodontic treatment, a space usually exists interproximally as a result of the thickness of the banding material. The accessibility of the opened proximal surface affords a rare opportunity to get fluoride interproximally easily. Also, in many instances an orthodontic “positioner” is then used to help close these spaces and complete final alignment. It would be a simple matter for the patient to place a little fluoride gel in the positioner before placing it on his teeth. Following this procedure each time the positioner is used will provide greater uptake of fluoride by the enamel from the high frequency of topical application, facilitate the contact of fluoride with the opened proximal surface, and provide an enhanced opportunity for the remineralization of decalcified enamel. Even if a positioner is not used after band removal, home fluoride trays or merely fluoride rinses can be used to fluoridate the opened interproximal and other enamel surfaces. Summary

It has been well documented that the more time the enamel surface is exposed to fluoride, the higher will be the caries protection. An extremely good method of greatly increasing caries resistance is by daily or weekly home fluoride treatments. This procedure is usually limited to special cases of rampant caries, patients with hemophilia, and handicapped patients in whom caries control is vital. It is not used more widely because of the added costs of impressions, tray fabrication, and professional time. If the patient already has a vehicle for applying fluoride, such as a positioner or mouth guard, it is a simple matter to prescribe or dispense fluoride gel to be used when these appliances are being worn. This is especially true for orthodontic positioners. When bands are re-

Positiolzer used for home fluoride

treahents

681

moved, a slight space usually exists interproximally. This space greatly facilitates fluoride contact with the proximal surfaces. Fluoride will tend to recalcify decalcified areas of enamel in addition to providing added caries protection for the patient. If positioners are not used after band removal, home fluoride trays or rinses can also be effective. Since many orthodontic patients wear a positioner when bands are removed, the orthodontist can provide his patients with the benefits of topical fluoride by prescribing fluoride gel and explaining how to use it along with his positioner. REFERENCES

concepts in prevention and treatment of dental caries, J. Tenn. 1. Massler, M.: Changing Dent. Assoc. 48: 1, 1968. 2. Forrester, D. J., and Auger, M. F.: A review of currently available topical fluoride agents, J. Dent. Child. 38: 272, 1971. 3. Brudevold, F., Gardner, D. E., and Smith, F.: Distribution of fluoride in human enamel, J. Dent. Res. 35: 420, 1956. 4. Nicholson, C. R., and Mellberg, J. R.: Induence of tooth age and natural 5uoride level on effectiveness of a single in vitro Auoride application, I.A.D.R. annual meeting, San Francisco, 1968, Abstr. No. 489. 5. Averill, II. M., Averill, J. E., and Ritz, A. G.: A two year comparison of three topical fluoride agents, Am. J. Public Health 57: 1627, 1967. 6. Horowitz, H. S., and Heifetz, S. B. : Evaluation of topical applications of stannous fluoride to teeth of children born and reared in a 5uoridated community: Final report, J. Dent. Child. 36: 355, 1969. 7. Muhler, J. C.: The anticariogenic effectiveness of a single application of stannous fluoride in children residing in an optimal communal fluoride area. II. Results at the end of 30 months, J. Am. Dent. Assoc. 61: 431, 1960. 8. Mellberg, J. R., and others: Acquisition of fluoride in vivo by enamel from repeated topical sodium 5uoride applications in a fluoridated area: A preliminary report, J. Dent. Res. 47: 733, 1968. 9. Englander, H. R., and others: Incremental rates of dental caries after repeated topical sodium fluoride applications in children with life-long consumption of fluoridated water, J. Am. Dent. Assoc. 82: 354, 1971. 10. Wei, S. H. Y., Kawueler, J. C., and Massler, M.: Remineralization of carious dentin, J. Dent. Res. 47: 381, 1968. 11. Wei, S. H. Y.: Remineralization of enamel and dentin, a review, J. Dent. Child. 34: 444, 1967. 12. Muhler, J. C., and others: The arrestment of incipient dental caries in adults after the use of 3 different forms of SnF, therapy: Results after 30 months, J. Am. Dent. Assoc. 75: 1402, 1967. 13. Briner, W. W., and Rosen, 5.: Effect of duoride on hypomineralized areas in the molars of rats fed a cariogenic diet, Arch. Oral Biol. 12: 1077, 1967. 14. Zuniga, M. A., and Caldwell, R. C.: The effect of fluoride containing prophylaxis pastes on normal and “white spot” enamel, J. Dent. Child. 36: 345, 1969. 15. Stearns, R. I.: Incorporation of fluoride by human enamel. III. In viva &&,s of nonfluoride and fluoride prophylactic pastes and APF gels, J. Dent. Res. 52: 30, 1973. 16. Mellberg, J. R., Englander, H. R.; and Nicholson, C. R.: Acquisition of fluoride in vivo by deciduous enamel from daily topical sodium fluoride applications over 21 months, Arch. Oral Biol. 12: 1139, 1967. 17. Driscoll, W. S., Heifetz, S. B., and Korts, D. B.: Effect of acidulated phosphate 5uoride chewable tablets on dental caries in school children. Results after 30 months, J. Am. Dent. Assoc. 89: 115, 1974. 18. Wellock, W. D., and Brudevold, F.: Study of acidulated fluoride solution. II. The caries

602

.I i,i .I. Orthod. .Jr~ne 157.3

‘/‘msk

inhibiting effect of single annual topical applic:ltions of au witlic fluoritlo :~ntl phosph:lte solution : A two year experience, Arch. Oral Biol. 8: 179, 196:i. 19. Horowitz, H. S., and KRU, M. V. IV.: Retained anticaries protection from topically applied acidulated phosphate fluoride : SO and 36 month post-trrntmr~nt +iffects. J. I’rewnt. Dent. 1: 21, 1974. 20. DePaola, P. F., and Lax, M.: The caries inhibiting effect of acidulatrd phosphate fluoride chewable tablets: A two year double blind study, J. Am. Jjent. Assoc. 76: 554, 196X. of school water fluoridation on tlcntnl caries ; 21. Heifetz, S. B., and Horowitz, H. S.: Effect after four vc~+rs, 5. Am. Dent. Assoc. 88: interim results in Seagrove, North Carolina,

352, 1974. 22.

Wei, H.: Fluoride uptake by enamel from topical solutions and gels: An in vitro study, J. Dent. Child. 40: 299-302, 1973. 23. Heifetz, S. B., and Horowitz, H. R.: Fluoride dentifrices. Z?a Newbrun, E. (editor) : Fluorides and dental caries, Springfield, Ill., 1972, Charles C Thomas Publisher, p. 22. 24. Englander, H. R., and others: Clinical anticaries effect of repeated topical sodium fluoride applications by mouthpieces, J. Am. Dent. Assoc. 75: 638, 1967. 25. Hendeles, L. S., Department of Clinical Pharmacology, University of Iowa Pharmacy School, 10~:~ City, lowa: Personal c~ommunic~ation, 1974.

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