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Use of Sodium Fluoride for Desensitizing Dentin
T
he
J
ournal of th e
A m e r ic a n D e n t a l A s s o c ia t io n
Certainly, the collection, tabulation and regular publication of data based on uncomplicated, uniform records will en courage their study by investigators in and outside federal, state and city o f f i r cial agencies. T o bury the records in the filés o f the various agencies, where they are only accessible to governmental researchers, would tend toward sterility of professional thought. Every thoughtful person appreciates
the debt that we owe to those who have preceded us. We, should accumulate and preserve as much as possible for those who follow us. W hat greater heritage can we leave than facts or the material for the use of those who seek facts? In accumulating these facts, the dental di visions of state health departments should take the lead.
600 Street.
West
One
Hundred
Sixty-Eighth
USE OF SODIUM FLUORIDE FOR DESENSITIZING DENTIN W
il l ia m
H. H
o y t ,*
D.D.S., and B a s i l G. B i b b y , ! D .M .D ., Ph.D., Boston, Mass.
H E exposure of dentin at the necks of the teeth by erosion or caries is one of the commonest causes of dental pain in adults. From time to time,
T
As presented in his report in the English language, Lukomsky’s claims for it are not very convincing. N o rationale of treatment is offered; little detail is given
methods of alleviating this discomfort have been advocated. These include treating the sensitive areas with silver nitrate, phenol, zinc chloride or formal dehyde. In our hands, these agents have been far from satisfactory. A ll are de structive to the soft tissues of the mouth, and silver nitrate has an additional dis advantage in that it discolors the den tin, and therefore cannot be used on teeth in the anterior part of the mouth. T h e greatest disadvantage with all of them is their failure to give really satis factory results, and the critical practi tioner must always use them more in hope than in expectation. Recently, a new means of desensitizing dentin, sodium fluoride, as an e ffe c tiv e obtundent, was suggested by Lukomsky.1
as to the manner of use, and no definite results are listed. However, since the halogen group of elements have many remarkable biologic effects, and because fluorine acts specifically on dental tis sues to cause mottling of enamel,2 com bines with enamel and dentin to change their chemical properties3 and has some very specific effects on bacterial and cel lular enzymes,4 it seemed possible that it might produce effects of the kind re ported by Lukomsky. Consequently, it seemed worth while to follow his lead and to determine by experiment the ef fects of applications of sodium fluoride mixtures on the sensitivity of the teeth.
^Professor of prosthetics, Tufts College Dental School. fProfessor of bacteriology and dean, Tufts College Dental School. Jour. A .D .A., V ol. 30, September 1, 1943
TESTS W I T H S O D I U M FLUORIDE
In the first tests, areas of sensitive dentin were treated with a 2 per cent aqueous solution of sodium fluoride. This gave obtunding effects which, although slight, were fairly definite and
H p y r a n d B ib b y — S o d iu m F l u o r id e
suggested the desirability of using more concentrated solutions. Accordingly, a 4 per cent solution was employed (satu rated solution of sodium fluoride in water). W ith solutions of this concentra tion, repeated treatment gave more definite obtunding effects. There was no escharotic action on the soft tissues, nor were there any unforeseen results. A p proximately twenty patients were treated with the 4 per cent solution, all of whom reported some degree of desensitization. Exceptions were noted only where areas of hyaline dentin had been treated. In accordance with the suggestions of Lukomsky,1 sodium fluoride was then in corporated into a paste with white clay and glycerin. Several mixtures of this sort were tested, with the sodium fluoride percentage ranging from 10 to 33.3 per T able
1373
of the same teeth with the 33 per cent sodium fluoride paste produced desensiti zation. Soon after the treatments with the fluoride paste were begun, it became evi dent that the results were remarkably satisfactory. After short treatments, teeth that had caused trouble for years ceased to be sensitive. Soon patients were com menting voluntarily on the satisfactory results of the fluoride applications, and requesting treatment of the remaining sensitive teeth. It soon became obvious that, in desensitizing effects, sodium fluoride was greatly superior to any of the obtundents previously used. T o place the observations on a more definite basis, the method of treatment was standardized, and detailed records were kept on a series of treatments.
1 .— R e s u l t s o f D e s e n s i t i z a t i o n T r e a t m e n t s w it h 3 3 P e r C e n t S o d iu m F l u o r id e P a s t e
Number of Patients Treated
Complete - and Immediate Desensitization
Second Treatment Successful*
Partial Desensitiza tion
Failure
Slight Return
70
54
2
6
2
6
There was a slight reaction to first treatment. cent. T h e most satisfactory results were obtained with the 33 per cent paste (sodi um fluoride 1 part, white clay 1 part, glycerin 1 part.) Use of this paste pro duced desensitization in practically every instance with the first application. H ow ever, since this paste contained glycerin, which is a dehydrating agent, it seemed possible that the obtunding effect might be due to the dehydration of the dentinal tubules, with consequent loss of their capacity for conducting pain. Therefore, a series of control tests were made to de termine whether the desensitization was caused by the fluoride or by other con stituents. Six highly sensitive teeth were treated with a paste containing no sodium fluoride. In no instance did desensitizatipn occur. Subsequent treatment
S T A N D A R D IZ E D M E T H O D O F A P P L I C A T I O N
After a preliminary cleaning with a pledget of cotton moistened with a 4 per cent sodium fluoride solution,: the area to be treated was isolated with cot ton rolls, a pledget of cotton being used to remove free moisture. A small amount o f 33 per cent sodium fluoride paste was then taken on the end of a small plastic instrument and placed on the tooth. T h e paste was then rubbed vigorously on the sensitive surface of the tooth with the plastic instrument, with concentra tion on any areas where pain (sensation of refrigeration) was encountered. This was continued until all sensation disap peared, the time necessary ranging from one to five minutes. Occasionally, when pain became acute, the paste was washed
1374
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c i a t i o n
off with a warm spray. In such instances, a second treatment was given imme diately, without difficulty. When the pain disappeared, the cotton rolls were re moved, and, at the same time, as much paste as possible was wiped off. This was followed by prompt washing with a spray bottle, and a thorough rinsing of the mouth by the patient. RESU LTS
From the time that the standardized treatment was adopted, results were al most uniformly satisfactory. Records have been accumulated on approxi mately even numbers of patients treated in private practice and in the clinics of Tufts College Dental School. A sum mary of the results obtained with private
patients after four months.; in one patient, after nine months, and in an other patient, after ten months. Table 2 summarizes the evidence on duration of the desensitization, including the cases that showed a slight return of sensation and those with single resistant teeth. T he data on age distribution and types of teeth treated are summarized in Table 3. The failures are noted in parenthesis. It is obvious, from this tabulation, that the treatment seems equally effective on all types of teeth regardless of the age of the patient. T h e results in the cases treated in the dental school clinics were fairly uniformly satisfactory, but difficulties in obtaining reliable follow-up reports re duced the value of the findings. There-
T a b l e 2 .— D u r a t i o n o f D e s e n s i t i z a t i o n *
Time in Months
1
2
3
4
5
6
7
8
9
10
11
Number of Patients
7
2
2
4
9
5
3
9
9
14
4
*All teeth still desensitized at time of this check-up. patients is given in Table 1. This tabu lation shows that of the seventy patients treated, there were only two in whom some of the teeth were not desensitized by the treatments. It is interesting to note that in the two patients in whom complete failures were recorded, other teeth in the mouth were completely de sensitized. T h e resistant tooth in one case proved to have an inflamed pulp. In the other case, persistent hemorrhage at the gingival margin interfered with the ef fectiveness of the treatment. In two in stances, a second treatment was required to bring about complete desensitization of some of the teeth. In six cases, some sensation gradually returned during a period of a month, with no change there after, the patient continuing to be comfortable. In six other cases, a slight return of sensitivity was noted in four
fore, a detailed presentation of results is not possible. S U P P L E M E N T A R Y E V ID E N C E
Confirmation of the value of the fore going method of desensitization has been received from a number of professional associates who have begun to use these treatments in their practices. It is their general opinion that the procedure works in practically all observed, as we are less effective showing marked
instances. Some have have, that treatments in areas of the teeth hyaline dentin.
U S E IN C A V I T Y P R E P A R A T IO N
T h e success obtained in obtunding naturally occurring sensitive dentin sug gested the possibility that sodium fluoride might have value in relieving the pain of cavity preparation in sensitive areas.
H o y t and
B ib b y — S o d iu m F l u o r i d e
Following the general procedure out lined above, we found that with the 33 per cent sodium fluoride paste, desen sitization was complete. T h e principal disadvantage was the intense pain ex perienced when the paste was applied to freshly exposed dentin. -This sensation
1375
in detail are somewhat limited in num ber, they do represent a careful clinical study, the conclusions of which are more than amply supported by our repeated clinical experience and that of our asso ciates. A t this time, it is not possible to of fer a logical explanation as to why sodium fluoride has this remarkable ef
is one of intense cold, which disappears when the paste is washed off with the spray. A second application is usually tolerated without difficulty. T h e shock resulting from direct application of the fluoride paste may be minimized by soak
fect. Four possibilities suggest themselves : 1. Since fluorides have been shown to combine readily with dental tissues,3 and have a general affinity for calcium salts, their presence might bring about increased calcification of the tubules or kindred changes in the dentin which
ing the cavity with a 1 per cent and then a 4 per cent sodium fluoride solution be fore the paste is used. The desensitizing
T a b l e 3 . — -D i s t r i b u t i o n o f R e s u l t s A c c o r d i n g t o A g e a n d T y p e s o f T e e t h T r e a t e d
Age Group
No. of Pa tients
Upper Cuspids Bicuspids
Left 10-15
Right
Lower Cuspids Bicuspids
Left
Right
Upper Molars
Left
Lower Molars
Right
3.
Left
Anterior Teeth
Right
Left
2
1
2
Total
Right 5
15-20
6
3
5
3
4
4
5
3
3
6
4
40
20-30
14
10
9
8
7
6
8
4
8
7
8
75
30-50
25
24
19
22
16
13
14(1*)
17
27
23
187
50-
22
7
6.
16
10
4
6
4
5
20
11
89
49
37
27
33
30
29
62
46
396
Total
70
44
39
12(1 *)
*Failure. effects of such treatments were notice able, not only during - the process of cavity preparation, but also after fillings had been placed. For instance, teeth in which cervical alloy fillings have been placed, which are often sensitive for days, immediately tolerated heat and cold when fillings were placed over fluorine-treated dentin.
would
result
in
additional
protection
for the dentinal tubules. However, in view of the rapidity of the desensitizing action, this does not seem very probable. 2. It is possible that the fluoride pene trates to the pulp, interfering with its function or lowering its vitality so that it is no longer receptive to pain. Evidence against this possibility is found in L u -
T h e results recorded in this paper present definite evidence that sodium fluoride mixtures effectively desensitize
komsky’s report where he notes that the desensitization in one area of the tooth does not prevent pain sensation in other areas of the same tooth. W e have con firmed this finding.
sensitive dentin. While the cases recorded
3. Since fluorine is an active enzyme
d is c u ss io n
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
should b e . pointed out that further re finements of the methods of its applica tion should be worked out by continual research so that maximum benefit may through the dentin. 4. A reaction between fluorine and be conferred with a minimum risk. the free ions of some electrolytes, such SUMMARY as calcium, m ay make these ions un available for the normal mechanism of Experiments have been carried out pain conduction. to determine the effectiveness of sodium These possibilities are pure speculation, fluoride in obtunding sensitive dentin. but are in keeping with the known effects O n the basis of a large number of
poison, it is possible that it interferes with some unknown enzyme action con cerned in conduction of sensation
of fluorine in other fields. Should it be possible to demonstrate the manner in which the fluorides act, light would be cast on the as yet completely unknown mechanism by which pain is conducted from the dentin to the pulp. Were this problem solved, the way might be opened for the development of other desensitiz ing agents of even greater effectiveness. While it is too early yet to assess ac curately the value of sodium fluoride in desentizing dentin, the observations recorded seem to demonstrate that should it have no other uses than those already demonstrated, it will have a valuable place in dental practice. From the enthusiasm with which the dental practitioners who are acquainted with these results have adopted this method in their practices, there is little doubt that it will be widely used as soon as it becomes more generally known. This being so, it is not out of place to reem phasize the fact that sodium fluoride is a toxic drug, and that it should at all times be used with caution. Finally, it
treatments, which include those given to a well-controlled group o f seventy pri vate patients, it has been shown that sodium fluoride is an extremely effective agent in desensitizing dentin. T h e effects of treatment last for many months, varying with the individual pa tient. It is suggested that, pending further study, this reagent should be used with caution. s '
BIBLIOGRAPHY
1. L u k o m s k y , E. H.: Fluorine Therapy for Exposed Dentin and Alveolar Atrophy. /. D. Res., 20 :649, December 1941 . 2 . D ean , H. T.: Chronic Endemic Fluorosis (Mottled Enamel). Chap. 12 , Dental Science and Dental Art. Philadelphia: Lea and Febiger, 1938 . 3 . V olker , J. F.: Effect of Fluorine on Solubility of Enamel and Dentin. Proc. Soc. Exper. Biol. St. Med., 4 2 :725 , December 1939 . 4. B ib b y , B. G., and V an K esteren , M.: Effect of Fluorine on Mouth Bacteria. J. D. Res., 1 9 :391 , August 1940. 416 Huntington Avenue.
he
J
ournal of th e
A m e r ic a n D e n t a l A s s o c ia t io n
Certainly, the collection, tabulation and regular publication of data based on uncomplicated, uniform records will en courage their study by investigators in and outside federal, state and city o f f i r cial agencies. T o bury the records in the filés o f the various agencies, where they are only accessible to governmental researchers, would tend toward sterility of professional thought. Every thoughtful person appreciates
the debt that we owe to those who have preceded us. We, should accumulate and preserve as much as possible for those who follow us. W hat greater heritage can we leave than facts or the material for the use of those who seek facts? In accumulating these facts, the dental di visions of state health departments should take the lead.
600 Street.
West
One
Hundred
Sixty-Eighth
USE OF SODIUM FLUORIDE FOR DESENSITIZING DENTIN W
il l ia m
H. H
o y t ,*
D.D.S., and B a s i l G. B i b b y , ! D .M .D ., Ph.D., Boston, Mass.
H E exposure of dentin at the necks of the teeth by erosion or caries is one of the commonest causes of dental pain in adults. From time to time,
T
As presented in his report in the English language, Lukomsky’s claims for it are not very convincing. N o rationale of treatment is offered; little detail is given
methods of alleviating this discomfort have been advocated. These include treating the sensitive areas with silver nitrate, phenol, zinc chloride or formal dehyde. In our hands, these agents have been far from satisfactory. A ll are de structive to the soft tissues of the mouth, and silver nitrate has an additional dis advantage in that it discolors the den tin, and therefore cannot be used on teeth in the anterior part of the mouth. T h e greatest disadvantage with all of them is their failure to give really satis factory results, and the critical practi tioner must always use them more in hope than in expectation. Recently, a new means of desensitizing dentin, sodium fluoride, as an e ffe c tiv e obtundent, was suggested by Lukomsky.1
as to the manner of use, and no definite results are listed. However, since the halogen group of elements have many remarkable biologic effects, and because fluorine acts specifically on dental tis sues to cause mottling of enamel,2 com bines with enamel and dentin to change their chemical properties3 and has some very specific effects on bacterial and cel lular enzymes,4 it seemed possible that it might produce effects of the kind re ported by Lukomsky. Consequently, it seemed worth while to follow his lead and to determine by experiment the ef fects of applications of sodium fluoride mixtures on the sensitivity of the teeth.
^Professor of prosthetics, Tufts College Dental School. fProfessor of bacteriology and dean, Tufts College Dental School. Jour. A .D .A., V ol. 30, September 1, 1943
TESTS W I T H S O D I U M FLUORIDE
In the first tests, areas of sensitive dentin were treated with a 2 per cent aqueous solution of sodium fluoride. This gave obtunding effects which, although slight, were fairly definite and
H p y r a n d B ib b y — S o d iu m F l u o r id e
suggested the desirability of using more concentrated solutions. Accordingly, a 4 per cent solution was employed (satu rated solution of sodium fluoride in water). W ith solutions of this concentra tion, repeated treatment gave more definite obtunding effects. There was no escharotic action on the soft tissues, nor were there any unforeseen results. A p proximately twenty patients were treated with the 4 per cent solution, all of whom reported some degree of desensitization. Exceptions were noted only where areas of hyaline dentin had been treated. In accordance with the suggestions of Lukomsky,1 sodium fluoride was then in corporated into a paste with white clay and glycerin. Several mixtures of this sort were tested, with the sodium fluoride percentage ranging from 10 to 33.3 per T able
1373
of the same teeth with the 33 per cent sodium fluoride paste produced desensiti zation. Soon after the treatments with the fluoride paste were begun, it became evi dent that the results were remarkably satisfactory. After short treatments, teeth that had caused trouble for years ceased to be sensitive. Soon patients were com menting voluntarily on the satisfactory results of the fluoride applications, and requesting treatment of the remaining sensitive teeth. It soon became obvious that, in desensitizing effects, sodium fluoride was greatly superior to any of the obtundents previously used. T o place the observations on a more definite basis, the method of treatment was standardized, and detailed records were kept on a series of treatments.
1 .— R e s u l t s o f D e s e n s i t i z a t i o n T r e a t m e n t s w it h 3 3 P e r C e n t S o d iu m F l u o r id e P a s t e
Number of Patients Treated
Complete - and Immediate Desensitization
Second Treatment Successful*
Partial Desensitiza tion
Failure
Slight Return
70
54
2
6
2
6
There was a slight reaction to first treatment. cent. T h e most satisfactory results were obtained with the 33 per cent paste (sodi um fluoride 1 part, white clay 1 part, glycerin 1 part.) Use of this paste pro duced desensitization in practically every instance with the first application. H ow ever, since this paste contained glycerin, which is a dehydrating agent, it seemed possible that the obtunding effect might be due to the dehydration of the dentinal tubules, with consequent loss of their capacity for conducting pain. Therefore, a series of control tests were made to de termine whether the desensitization was caused by the fluoride or by other con stituents. Six highly sensitive teeth were treated with a paste containing no sodium fluoride. In no instance did desensitizatipn occur. Subsequent treatment
S T A N D A R D IZ E D M E T H O D O F A P P L I C A T I O N
After a preliminary cleaning with a pledget of cotton moistened with a 4 per cent sodium fluoride solution,: the area to be treated was isolated with cot ton rolls, a pledget of cotton being used to remove free moisture. A small amount o f 33 per cent sodium fluoride paste was then taken on the end of a small plastic instrument and placed on the tooth. T h e paste was then rubbed vigorously on the sensitive surface of the tooth with the plastic instrument, with concentra tion on any areas where pain (sensation of refrigeration) was encountered. This was continued until all sensation disap peared, the time necessary ranging from one to five minutes. Occasionally, when pain became acute, the paste was washed
1374
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c i a t i o n
off with a warm spray. In such instances, a second treatment was given imme diately, without difficulty. When the pain disappeared, the cotton rolls were re moved, and, at the same time, as much paste as possible was wiped off. This was followed by prompt washing with a spray bottle, and a thorough rinsing of the mouth by the patient. RESU LTS
From the time that the standardized treatment was adopted, results were al most uniformly satisfactory. Records have been accumulated on approxi mately even numbers of patients treated in private practice and in the clinics of Tufts College Dental School. A sum mary of the results obtained with private
patients after four months.; in one patient, after nine months, and in an other patient, after ten months. Table 2 summarizes the evidence on duration of the desensitization, including the cases that showed a slight return of sensation and those with single resistant teeth. T he data on age distribution and types of teeth treated are summarized in Table 3. The failures are noted in parenthesis. It is obvious, from this tabulation, that the treatment seems equally effective on all types of teeth regardless of the age of the patient. T h e results in the cases treated in the dental school clinics were fairly uniformly satisfactory, but difficulties in obtaining reliable follow-up reports re duced the value of the findings. There-
T a b l e 2 .— D u r a t i o n o f D e s e n s i t i z a t i o n *
Time in Months
1
2
3
4
5
6
7
8
9
10
11
Number of Patients
7
2
2
4
9
5
3
9
9
14
4
*All teeth still desensitized at time of this check-up. patients is given in Table 1. This tabu lation shows that of the seventy patients treated, there were only two in whom some of the teeth were not desensitized by the treatments. It is interesting to note that in the two patients in whom complete failures were recorded, other teeth in the mouth were completely de sensitized. T h e resistant tooth in one case proved to have an inflamed pulp. In the other case, persistent hemorrhage at the gingival margin interfered with the ef fectiveness of the treatment. In two in stances, a second treatment was required to bring about complete desensitization of some of the teeth. In six cases, some sensation gradually returned during a period of a month, with no change there after, the patient continuing to be comfortable. In six other cases, a slight return of sensitivity was noted in four
fore, a detailed presentation of results is not possible. S U P P L E M E N T A R Y E V ID E N C E
Confirmation of the value of the fore going method of desensitization has been received from a number of professional associates who have begun to use these treatments in their practices. It is their general opinion that the procedure works in practically all observed, as we are less effective showing marked
instances. Some have have, that treatments in areas of the teeth hyaline dentin.
U S E IN C A V I T Y P R E P A R A T IO N
T h e success obtained in obtunding naturally occurring sensitive dentin sug gested the possibility that sodium fluoride might have value in relieving the pain of cavity preparation in sensitive areas.
H o y t and
B ib b y — S o d iu m F l u o r i d e
Following the general procedure out lined above, we found that with the 33 per cent sodium fluoride paste, desen sitization was complete. T h e principal disadvantage was the intense pain ex perienced when the paste was applied to freshly exposed dentin. -This sensation
1375
in detail are somewhat limited in num ber, they do represent a careful clinical study, the conclusions of which are more than amply supported by our repeated clinical experience and that of our asso ciates. A t this time, it is not possible to of fer a logical explanation as to why sodium fluoride has this remarkable ef
is one of intense cold, which disappears when the paste is washed off with the spray. A second application is usually tolerated without difficulty. T h e shock resulting from direct application of the fluoride paste may be minimized by soak
fect. Four possibilities suggest themselves : 1. Since fluorides have been shown to combine readily with dental tissues,3 and have a general affinity for calcium salts, their presence might bring about increased calcification of the tubules or kindred changes in the dentin which
ing the cavity with a 1 per cent and then a 4 per cent sodium fluoride solution be fore the paste is used. The desensitizing
T a b l e 3 . — -D i s t r i b u t i o n o f R e s u l t s A c c o r d i n g t o A g e a n d T y p e s o f T e e t h T r e a t e d
Age Group
No. of Pa tients
Upper Cuspids Bicuspids
Left 10-15
Right
Lower Cuspids Bicuspids
Left
Right
Upper Molars
Left
Lower Molars
Right
3.
Left
Anterior Teeth
Right
Left
2
1
2
Total
Right 5
15-20
6
3
5
3
4
4
5
3
3
6
4
40
20-30
14
10
9
8
7
6
8
4
8
7
8
75
30-50
25
24
19
22
16
13
14(1*)
17
27
23
187
50-
22
7
6.
16
10
4
6
4
5
20
11
89
49
37
27
33
30
29
62
46
396
Total
70
44
39
12(1 *)
*Failure. effects of such treatments were notice able, not only during - the process of cavity preparation, but also after fillings had been placed. For instance, teeth in which cervical alloy fillings have been placed, which are often sensitive for days, immediately tolerated heat and cold when fillings were placed over fluorine-treated dentin.
would
result
in
additional
protection
for the dentinal tubules. However, in view of the rapidity of the desensitizing action, this does not seem very probable. 2. It is possible that the fluoride pene trates to the pulp, interfering with its function or lowering its vitality so that it is no longer receptive to pain. Evidence against this possibility is found in L u -
T h e results recorded in this paper present definite evidence that sodium fluoride mixtures effectively desensitize
komsky’s report where he notes that the desensitization in one area of the tooth does not prevent pain sensation in other areas of the same tooth. W e have con firmed this finding.
sensitive dentin. While the cases recorded
3. Since fluorine is an active enzyme
d is c u ss io n
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
should b e . pointed out that further re finements of the methods of its applica tion should be worked out by continual research so that maximum benefit may through the dentin. 4. A reaction between fluorine and be conferred with a minimum risk. the free ions of some electrolytes, such SUMMARY as calcium, m ay make these ions un available for the normal mechanism of Experiments have been carried out pain conduction. to determine the effectiveness of sodium These possibilities are pure speculation, fluoride in obtunding sensitive dentin. but are in keeping with the known effects O n the basis of a large number of
poison, it is possible that it interferes with some unknown enzyme action con cerned in conduction of sensation
of fluorine in other fields. Should it be possible to demonstrate the manner in which the fluorides act, light would be cast on the as yet completely unknown mechanism by which pain is conducted from the dentin to the pulp. Were this problem solved, the way might be opened for the development of other desensitiz ing agents of even greater effectiveness. While it is too early yet to assess ac curately the value of sodium fluoride in desentizing dentin, the observations recorded seem to demonstrate that should it have no other uses than those already demonstrated, it will have a valuable place in dental practice. From the enthusiasm with which the dental practitioners who are acquainted with these results have adopted this method in their practices, there is little doubt that it will be widely used as soon as it becomes more generally known. This being so, it is not out of place to reem phasize the fact that sodium fluoride is a toxic drug, and that it should at all times be used with caution. Finally, it
treatments, which include those given to a well-controlled group o f seventy pri vate patients, it has been shown that sodium fluoride is an extremely effective agent in desensitizing dentin. T h e effects of treatment last for many months, varying with the individual pa tient. It is suggested that, pending further study, this reagent should be used with caution. s '
BIBLIOGRAPHY
1. L u k o m s k y , E. H.: Fluorine Therapy for Exposed Dentin and Alveolar Atrophy. /. D. Res., 20 :649, December 1941 . 2 . D ean , H. T.: Chronic Endemic Fluorosis (Mottled Enamel). Chap. 12 , Dental Science and Dental Art. Philadelphia: Lea and Febiger, 1938 . 3 . V olker , J. F.: Effect of Fluorine on Solubility of Enamel and Dentin. Proc. Soc. Exper. Biol. St. Med., 4 2 :725 , December 1939 . 4. B ib b y , B. G., and V an K esteren , M.: Effect of Fluorine on Mouth Bacteria. J. D. Res., 1 9 :391 , August 1940. 416 Huntington Avenue.