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Bleaching tetracycline-stained vital teeth
Bleaching tetracycline-stainedvital teeth Rephen Cohen, B.A., M.A., D.D.S.,” md Prede,rick ill. Parkins, D.D.X., M.S.D., Ph.D.,** Philadelphia, Pa. UNIVERSITY
OF PEIQXYLVANIA
SCHOOL OF DENTAL
MEDICINE
T
etracycline antibiotics, when administered during tooth development, are deposited in the forming dentine. 1 Following eruption, the dentine OS these teeth exhibits a brown to gray discoloration through the overlying enamel. TJntil recently, tetracyclines were commonly the drugs of choice for treatment of patients with cystic fibrosis. Consequently, tooth discoloration has bcvn frequently found in children with this disease. Therefore, more attention has been focused on the unusually severe discoloration of the permanent, teet,h of these persons. The tooth discoloration in thirty-eight of fifty-two patients with cystic fibrosis is described by Zegarelli and his co-authors,” who also states3 that of forty-one patients with cystic fibrosis, twenty-four had teeth that were classified as dark (intense yellow to dark brown). Swallow and associates4found that 37 per cent of sixty-three children wibh cystic fibrosis had significantly discolored incisors, whereas Shwachman and colleagues5 found that approximately 80 per cent of fifty patients with cystic fibrosis were so affected. Zegarelli and associates”,i have suggested that tooth discoloration in persons with cystic fibrosis is a result. of either (1) the disease alone; (2) one or more therapeutic agents (especial1.v tetracyclines) ; or (3) combinations of the two factors. Because many cyst>ic fibrosis patients have received tetracyclines during their early years, the exact cause of the intrinsic discoloration is difficult to determine. The probable mechanism by which tetracycline molecules bind to dentinc is reviewed by Mel1o.l Chelation is thought to occur with calcium at the hydroxyapatite crystal surface of dentine to form a tetracycline-orthophosphate, causing tooth discoloration. Tetracycline-stained teeth, when exposed to sunlight, gradually turn to shades of dark gray or brown. Following eruption, fluorescence A thesis submitted by the senior author in partial fulfillment of the requirements of the Division of Advanced Education, Department of Endodontics, University of Pennsylvania. “Present address: 450 Sutter St., San Francisco, Cnlif. 94108. **Assistant Professor and Director of Pedodontics. At present Chairman, Department of Pedodontics, University of Iowa.
465
466
Oral Surg. March, 1970
Cohen and Parkins
is seen under Wood’s ultraviolet light.s This fluorescence decrea.ses with posteruption time. The labial surfaces of the incisors are the first to darken, while the molars remain yellow for a longer period of time because they remain in the shadows of the mouth. Tooth discoloration can cause esthetic problems. If untreated, this disfigurement can produce social and psychologic difficulties, especially among teenagers. One solution to this problem is to crown all the teeth with acrylic or porcelain jackets; however, this requires subjecting the patient to extensive, time-consuming, and costly dental procedures which occasionally result in pulpal pathosis. Furthermore, these jackets, even if they are not accidentally fractured, have to be replaced periodically as the patient matures. Bleaching of these discolored vital teeth to a more normal tooth color, if effective, would be the treatment of choice. Several techniques have been suggested9-I5 for reducing the enamel stains of dental fluorosis. The fact that sound enamel and dentine are porous tissues16~l7 suggests that it might be possible to bleach vital dentine. In this preliminary study, a technique for bleaching discolored dentine of patients with cystic fibrosis is evaluated. MATERIALS AND METHODS Six patients (one boy and five girls, ranging in age from 6 to 18 years) with cystic fibrosis and with caries-free dentitions participated in this study. They were selected at random from a list of outpatients at Hahnemann Hospital and St. Christopher’s Hospital for Children in Philadelphia. For all subjects in this study, the following information was recorded : Name Age Sex History and dates of tetracycline administration Fluorescence under Wood’s ultraviolet light (slight, moderate, strong) Initial vitality (using the same Ritter vitalometer) Vitality after each treatment Radiographic abnormalities Photographic appearance before and after each treatment Comments of patients and their parents Observations of the clinician After a thorough prophylaxis, the two upper right incisors were isolated by means of a rubber dam, using Orabase emollient* for gingival protection. During the first five treatments only these two incisors were isolated and bleached. The change was evaluated by visual and photographic comparison with the contralateral teeth, which were untreated. Three more appointments (generally at one-week intervals) were devoted to bleaching all the upper anterior teeth. After the completion of treatment (a total of eight appointments) the patients were seen monthly to determine whether changes had occurred and for an additional bleaching treatment. “E. R. Squibb & Sons, New Brunswick,
N. J.
J
Bleaching
tetracycline-stained
vital
teeth
467
Table I. Summary of clinician’s observations and comments of patients and parents Patient E. G.
Palient D. C.
Patient R. G.
Patient C. G.
Patient G. w.
Patient G. D.
Age
17
18
10
6
11
13
Sex
F
F
F
F
F
M
Fluorescence
None
None
None
Slight
None
None
+**
***
ii**
x
IX
***
Clinician’s observations A. bleaching effect B. patient’s attitude
Patient’s comments
Smiles more Smiles more readily and readily more broadly Satisfied ; friends remark that teeth “seem
whiter”
Parents’ comments
‘LExcellent ~;gholoizresults” ; talks and smiles without covering mouth
Less shy and No change reticent
Parts
her lips when she smiles
Smiles more readily
“Teeth seem “Teeth.. , a lot seem lighter . . . brighter. .. surprised very that it happy” lasted.. . people have noticed the change”
Believes teeth I‘. . . are a little bett,er”
“Likes the new color”
Teeth “look nicer”
Readily ;,“,“;;J
“Disappointed”
‘Very pleased”
Teeth look
events
“People have stopped staring at her teeth”
“muc11
better”
*No change. **Slight improvement. ***Marked improvement.
Bleaching was accomplished with 30 per cent hydrogen peroxide (Superoxol*) warmed by a hand-held heating source (bleaching tooli ) which was notched at the end to receive the tooth. Each tooth was covered with peroxide-saturated gauze, and the heating source was placed over this gauze. This technique is illustrated in Fig. 2. A rheostat was used to control the temperature. The temperature was adjusted to just below each patient’s pain threshold. Each tooth was asymptomatically blea.ched for 30 minutes. After treatment, the teeth were washed with warm water and the rubber dam was removed. Ektachrome 127 film in a dental photographic unit. (Startech+ with a 1:l lens attachment) was used to photograph the teeth before and after each appointment. A shade guide was employed for the assessment of color changes. The comments of the patients and their parents were also recorded. All observa*Merck & Co., Inc., Rahway, N. J. tFluro-Ted Co., Davis, Calif. *Lester Dine, Inc., New Hyde Park,
N. Y.
Oral Surg. March, 1970
Fig. 1. Tetracycline staining is similiar to that of all subjects
in patient with cystic fibrosis included in this study.
Pig. maxillary
source
8. Hand-held heating right incisors.
and
prior
peroxide-saturated
tions and evaluations of photographs, patient’s attitudes, were made and recorded by the same clinician.
to treatment.
gauze
in position
Appearance
to bleach
and parents’ comments
RESULTS
There was noticeable esthetic improvement in five of the six patients treated in this study. A comparison of Figs. 1 and 4 shows results typical of those
Volume Numlw
29 -3
Pig. 4. dppenraucc
at time of 3-month recall visit, lIefore
“touch-up”
tfwtrnenl.
obtained. The one patient in whom there was no noticcablc improvement was the youngest in this study (Table I). The observations of the clinician and the comments of the patients and parents have been summarized in Table I. Bleaching was most effective in the incisal half of the crown (where the dentine is thinner). The lateral incisors showed the most apparent shatic improvement. Five of the six patients could comfortably keep the heating source on the teeth for 30 minutes at a. temperature of 88O F. 0ne patient. was premedicatcd by her physician with 600 mg. of A.S.A. plus 30 m g. of phenobarbital to raise her pain threshold. After premeditation, a bleaching temperature of SO0 5’. could be comfortably tolerated for 30 minutes. The physician stated that it was routine for this patient to receive premcdicatiou prior to any medical or dental treatment. For all patients, t.hc clect.ric pulp test readings for the incisors rcmaincd
470
Cohen and Parkins
Oral Surg. March, 1970
unchanged between the initial and final treatments, that is, variance was no greater than one half unit. No effect on the gingival tissue was observed. All patients were pleased with the final results. Only one patient showed slight fluorescence; the others demonstrated none. At least equal in importance to the esthetic improvement were the psychologic changes reported by the parents (Table I). Several of these patients, prior to bleaching treatment, were reluctant to smile; most overcame this characteristic after treatment. DISCUSSION The results of this preliminary investigation suggest that significant esthetic improvement occurs when tetracycline-stained vital teeth are bleached with a warmed solution of 30 per cent hydrogen peroxide. Possibly the thinness of the enamel, compared to that of the adjacent central incisor and cuspid, accounted for the lateral incisors showing the most dramatic shade improvement. After the rubber dam was removed, the enamel surface in some subjects had a chalky white appearance which disappeared within an hour after treatment. This opacity was probably due to desiccation of the enamel surface during the rubber-dam isolation, as suggested by Mumford.18 Initially, two patients had a transient hyperemia when the heating source was plugged directly into a. 110 volt outlet. A rheostat was then added to control the temperature of the heating source; thereafter, all teeth under treatment remained asymptomatic during and after treatment. All patients were cautioned that their teeth might darken after completion of treatment. To preclude this possibility, monthly “touch-up” treatments were performed. Little change was observed by the clinician or by the patients and parents at these monthly visits. This bleaching technique probably causes temporary dehydration. Consequently, it is contraindicated for any tooth bearing a silicate or resin restoration. The shades of the teeth varied considerably with the region examined. As a result, shade guides were of little value and were, therefore, discarded. These patients will be kept under observation, and. at a later time the long-term effects of this technique will be presented. SUMMARY 1. Six patients with cystic fibrosis, ranging in age from 6 to 18 years, were selected at random for a preliminary study of a technique for bleaching vital teeth which were stained by tetracycline administration. 2. Bleaching was accomplished by warming a 30 per cent hydrogen peroxide solution to approximately W F. with a hand-held heating source which was placed over the external surface of the tooth for 30 minutes. The peroxide solution was kept in contact with the tooth by means of a gauze matrix. 3. Each patient was given eight treatments, generally at one-week intervals, and was seen and treated monthly thereafter.
Volume
29
Number 3
Bleaching
tetracycline-stained
vital
teeth
471
4. There was significant esthetic improvement in five of the six patients. The results were evaluated on the basis of the clinician’s observations, pre- and postoperative color photographs, and the recorded comments of the patients and their parents. REFERENCES
1. Mello, H. 5.: The Mechanism of Tetracycline Staining in Primary and Permanent TeeIll, J. Dent. Child. 34: 478, 1967. I’.: Dis2. Zegarelli, E. V., Denning, C. R., Kutscher, A., Tuoti, F., and diSant’Agnese, coloration of the Teeth in Patients With Cystic Fibrosis of the Pancreas, New York Dent. J. 27: 237, 1961. 3. Zegarelli, E. V., Kutseher, A., Denning, C. P., Saporito, R., and Slaughter, T.: Coloration of the Teeth in Patients With Cystic Fibrosis of the Pancreas, ORAL SURG. 15: 929, 1962. 4. Swallow, J. N., DeHaller, in Cystic J., and Young, W. F.: Side Effects to Antibiotics Fibrosis: Dental Changes in Relation to Antibiotic Administration, Arch. Dis. Child. 42: 311,1967. 5. Shwachman, H., Fekete, E., Kulezycki, L. I., and Foley, G. E.: The Effects of Long Term Antibiotic Therapy in Patients With Cystic Fibrosis of the Pancreas, Antibiotic Annual, New York, 1958-59, Medical Encyclopedia, Inc., pp. 692-699. 6. Zegarelli, E. V., Denning, C. R., Kutscher, A., Fahn, B., Kirshner, G., and Slaughter, T.: Discoloration of the Teeth in Patients With Cystic Fibrosis: Role of Tetracycline Therapy, Clin. Pediat. (Phila.), 2: 329, 1963. E. V., Kutscher, A., Denning, C. R., and Ragosta, J.: Discoloration of the 7. Zegarelli, Teeth in a 24-Year-Old Patient With Cystic Fibrosis of the Pancreas Not Primarily Associated With Tetracycline Therapy, ORAL SURG. 24: 62, 1967. 8. Stewart, D. J.: The Effects of Tetracycline8 Upon the Dentition, Brit. J. Derm. 76: 374,1964. 9. Boushor, C. F.: ‘(Stained Teeth,” Question and Answer section, J. Amer. Dent. Aqs. 77: 18, 1968. 10. Ku&tad, H. M. : Question and Answer section, Dent. Survey 44: 57, 1968. 11. Caldwell, C. P.: Bleaching Vital or Nonvital Teeth, J. Calif. Dent. Ass. 42: 234, 1966. 12. Younger, H. B.: Bleaching Mottled Enamel, Texas Dent. J. 60: 469, 1942. Peabody, J. B. : Discussion of Dr. Younger’s Paper, Texas Dent. J. 60: 469, 1942. :t Merwe, P. K.: The Removal of the Stain From Mottled Teeth, S. Afr. Dent. J. 18: 31, 1944. 15. Bailey, R. W., and Christen, A. G.: Bleaching of Vital Teeth Stained With Endemic Dental Fluorosis, ORAL SURG.26: 871, 1968. 16. Wainwright, W. W., and Lemoine, F. A.: Rapid Diffuse Penetration of Intact Enamel and Dentin by Carbon-6-14-Labled Urea, J. Amer. Dent. Ass. 41: 135, 1950. 17. Jenkins, G. N.: The Physiology of the Mouth, ed. 3, Philadelphia, 1966, F. A, Davis Company. 18. Mumford, J. M.: Drying of Enamel Under Rubber Dam, Brit. Dent. J. 121: 178, 1966.
OF PEIQXYLVANIA
SCHOOL OF DENTAL
MEDICINE
T
etracycline antibiotics, when administered during tooth development, are deposited in the forming dentine. 1 Following eruption, the dentine OS these teeth exhibits a brown to gray discoloration through the overlying enamel. TJntil recently, tetracyclines were commonly the drugs of choice for treatment of patients with cystic fibrosis. Consequently, tooth discoloration has bcvn frequently found in children with this disease. Therefore, more attention has been focused on the unusually severe discoloration of the permanent, teet,h of these persons. The tooth discoloration in thirty-eight of fifty-two patients with cystic fibrosis is described by Zegarelli and his co-authors,” who also states3 that of forty-one patients with cystic fibrosis, twenty-four had teeth that were classified as dark (intense yellow to dark brown). Swallow and associates4found that 37 per cent of sixty-three children wibh cystic fibrosis had significantly discolored incisors, whereas Shwachman and colleagues5 found that approximately 80 per cent of fifty patients with cystic fibrosis were so affected. Zegarelli and associates”,i have suggested that tooth discoloration in persons with cystic fibrosis is a result. of either (1) the disease alone; (2) one or more therapeutic agents (especial1.v tetracyclines) ; or (3) combinations of the two factors. Because many cyst>ic fibrosis patients have received tetracyclines during their early years, the exact cause of the intrinsic discoloration is difficult to determine. The probable mechanism by which tetracycline molecules bind to dentinc is reviewed by Mel1o.l Chelation is thought to occur with calcium at the hydroxyapatite crystal surface of dentine to form a tetracycline-orthophosphate, causing tooth discoloration. Tetracycline-stained teeth, when exposed to sunlight, gradually turn to shades of dark gray or brown. Following eruption, fluorescence A thesis submitted by the senior author in partial fulfillment of the requirements of the Division of Advanced Education, Department of Endodontics, University of Pennsylvania. “Present address: 450 Sutter St., San Francisco, Cnlif. 94108. **Assistant Professor and Director of Pedodontics. At present Chairman, Department of Pedodontics, University of Iowa.
465
466
Oral Surg. March, 1970
Cohen and Parkins
is seen under Wood’s ultraviolet light.s This fluorescence decrea.ses with posteruption time. The labial surfaces of the incisors are the first to darken, while the molars remain yellow for a longer period of time because they remain in the shadows of the mouth. Tooth discoloration can cause esthetic problems. If untreated, this disfigurement can produce social and psychologic difficulties, especially among teenagers. One solution to this problem is to crown all the teeth with acrylic or porcelain jackets; however, this requires subjecting the patient to extensive, time-consuming, and costly dental procedures which occasionally result in pulpal pathosis. Furthermore, these jackets, even if they are not accidentally fractured, have to be replaced periodically as the patient matures. Bleaching of these discolored vital teeth to a more normal tooth color, if effective, would be the treatment of choice. Several techniques have been suggested9-I5 for reducing the enamel stains of dental fluorosis. The fact that sound enamel and dentine are porous tissues16~l7 suggests that it might be possible to bleach vital dentine. In this preliminary study, a technique for bleaching discolored dentine of patients with cystic fibrosis is evaluated. MATERIALS AND METHODS Six patients (one boy and five girls, ranging in age from 6 to 18 years) with cystic fibrosis and with caries-free dentitions participated in this study. They were selected at random from a list of outpatients at Hahnemann Hospital and St. Christopher’s Hospital for Children in Philadelphia. For all subjects in this study, the following information was recorded : Name Age Sex History and dates of tetracycline administration Fluorescence under Wood’s ultraviolet light (slight, moderate, strong) Initial vitality (using the same Ritter vitalometer) Vitality after each treatment Radiographic abnormalities Photographic appearance before and after each treatment Comments of patients and their parents Observations of the clinician After a thorough prophylaxis, the two upper right incisors were isolated by means of a rubber dam, using Orabase emollient* for gingival protection. During the first five treatments only these two incisors were isolated and bleached. The change was evaluated by visual and photographic comparison with the contralateral teeth, which were untreated. Three more appointments (generally at one-week intervals) were devoted to bleaching all the upper anterior teeth. After the completion of treatment (a total of eight appointments) the patients were seen monthly to determine whether changes had occurred and for an additional bleaching treatment. “E. R. Squibb & Sons, New Brunswick,
N. J.
J
Bleaching
tetracycline-stained
vital
teeth
467
Table I. Summary of clinician’s observations and comments of patients and parents Patient E. G.
Palient D. C.
Patient R. G.
Patient C. G.
Patient G. w.
Patient G. D.
Age
17
18
10
6
11
13
Sex
F
F
F
F
F
M
Fluorescence
None
None
None
Slight
None
None
+**
***
ii**
x
IX
***
Clinician’s observations A. bleaching effect B. patient’s attitude
Patient’s comments
Smiles more Smiles more readily and readily more broadly Satisfied ; friends remark that teeth “seem
whiter”
Parents’ comments
‘LExcellent ~;gholoizresults” ; talks and smiles without covering mouth
Less shy and No change reticent
Parts
her lips when she smiles
Smiles more readily
“Teeth seem “Teeth.. , a lot seem lighter . . . brighter. .. surprised very that it happy” lasted.. . people have noticed the change”
Believes teeth I‘. . . are a little bett,er”
“Likes the new color”
Teeth “look nicer”
Readily ;,“,“;;J
“Disappointed”
‘Very pleased”
Teeth look
events
“People have stopped staring at her teeth”
“muc11
better”
*No change. **Slight improvement. ***Marked improvement.
Bleaching was accomplished with 30 per cent hydrogen peroxide (Superoxol*) warmed by a hand-held heating source (bleaching tooli ) which was notched at the end to receive the tooth. Each tooth was covered with peroxide-saturated gauze, and the heating source was placed over this gauze. This technique is illustrated in Fig. 2. A rheostat was used to control the temperature. The temperature was adjusted to just below each patient’s pain threshold. Each tooth was asymptomatically blea.ched for 30 minutes. After treatment, the teeth were washed with warm water and the rubber dam was removed. Ektachrome 127 film in a dental photographic unit. (Startech+ with a 1:l lens attachment) was used to photograph the teeth before and after each appointment. A shade guide was employed for the assessment of color changes. The comments of the patients and their parents were also recorded. All observa*Merck & Co., Inc., Rahway, N. J. tFluro-Ted Co., Davis, Calif. *Lester Dine, Inc., New Hyde Park,
N. Y.
Oral Surg. March, 1970
Fig. 1. Tetracycline staining is similiar to that of all subjects
in patient with cystic fibrosis included in this study.
Pig. maxillary
source
8. Hand-held heating right incisors.
and
prior
peroxide-saturated
tions and evaluations of photographs, patient’s attitudes, were made and recorded by the same clinician.
to treatment.
gauze
in position
Appearance
to bleach
and parents’ comments
RESULTS
There was noticeable esthetic improvement in five of the six patients treated in this study. A comparison of Figs. 1 and 4 shows results typical of those
Volume Numlw
29 -3
Pig. 4. dppenraucc
at time of 3-month recall visit, lIefore
“touch-up”
tfwtrnenl.
obtained. The one patient in whom there was no noticcablc improvement was the youngest in this study (Table I). The observations of the clinician and the comments of the patients and parents have been summarized in Table I. Bleaching was most effective in the incisal half of the crown (where the dentine is thinner). The lateral incisors showed the most apparent shatic improvement. Five of the six patients could comfortably keep the heating source on the teeth for 30 minutes at a. temperature of 88O F. 0ne patient. was premedicatcd by her physician with 600 mg. of A.S.A. plus 30 m g. of phenobarbital to raise her pain threshold. After premeditation, a bleaching temperature of SO0 5’. could be comfortably tolerated for 30 minutes. The physician stated that it was routine for this patient to receive premcdicatiou prior to any medical or dental treatment. For all patients, t.hc clect.ric pulp test readings for the incisors rcmaincd
470
Cohen and Parkins
Oral Surg. March, 1970
unchanged between the initial and final treatments, that is, variance was no greater than one half unit. No effect on the gingival tissue was observed. All patients were pleased with the final results. Only one patient showed slight fluorescence; the others demonstrated none. At least equal in importance to the esthetic improvement were the psychologic changes reported by the parents (Table I). Several of these patients, prior to bleaching treatment, were reluctant to smile; most overcame this characteristic after treatment. DISCUSSION The results of this preliminary investigation suggest that significant esthetic improvement occurs when tetracycline-stained vital teeth are bleached with a warmed solution of 30 per cent hydrogen peroxide. Possibly the thinness of the enamel, compared to that of the adjacent central incisor and cuspid, accounted for the lateral incisors showing the most dramatic shade improvement. After the rubber dam was removed, the enamel surface in some subjects had a chalky white appearance which disappeared within an hour after treatment. This opacity was probably due to desiccation of the enamel surface during the rubber-dam isolation, as suggested by Mumford.18 Initially, two patients had a transient hyperemia when the heating source was plugged directly into a. 110 volt outlet. A rheostat was then added to control the temperature of the heating source; thereafter, all teeth under treatment remained asymptomatic during and after treatment. All patients were cautioned that their teeth might darken after completion of treatment. To preclude this possibility, monthly “touch-up” treatments were performed. Little change was observed by the clinician or by the patients and parents at these monthly visits. This bleaching technique probably causes temporary dehydration. Consequently, it is contraindicated for any tooth bearing a silicate or resin restoration. The shades of the teeth varied considerably with the region examined. As a result, shade guides were of little value and were, therefore, discarded. These patients will be kept under observation, and. at a later time the long-term effects of this technique will be presented. SUMMARY 1. Six patients with cystic fibrosis, ranging in age from 6 to 18 years, were selected at random for a preliminary study of a technique for bleaching vital teeth which were stained by tetracycline administration. 2. Bleaching was accomplished by warming a 30 per cent hydrogen peroxide solution to approximately W F. with a hand-held heating source which was placed over the external surface of the tooth for 30 minutes. The peroxide solution was kept in contact with the tooth by means of a gauze matrix. 3. Each patient was given eight treatments, generally at one-week intervals, and was seen and treated monthly thereafter.
Volume
29
Number 3
Bleaching
tetracycline-stained
vital
teeth
471
4. There was significant esthetic improvement in five of the six patients. The results were evaluated on the basis of the clinician’s observations, pre- and postoperative color photographs, and the recorded comments of the patients and their parents. REFERENCES
1. Mello, H. 5.: The Mechanism of Tetracycline Staining in Primary and Permanent TeeIll, J. Dent. Child. 34: 478, 1967. I’.: Dis2. Zegarelli, E. V., Denning, C. R., Kutscher, A., Tuoti, F., and diSant’Agnese, coloration of the Teeth in Patients With Cystic Fibrosis of the Pancreas, New York Dent. J. 27: 237, 1961. 3. Zegarelli, E. V., Kutseher, A., Denning, C. P., Saporito, R., and Slaughter, T.: Coloration of the Teeth in Patients With Cystic Fibrosis of the Pancreas, ORAL SURG. 15: 929, 1962. 4. Swallow, J. N., DeHaller, in Cystic J., and Young, W. F.: Side Effects to Antibiotics Fibrosis: Dental Changes in Relation to Antibiotic Administration, Arch. Dis. Child. 42: 311,1967. 5. Shwachman, H., Fekete, E., Kulezycki, L. I., and Foley, G. E.: The Effects of Long Term Antibiotic Therapy in Patients With Cystic Fibrosis of the Pancreas, Antibiotic Annual, New York, 1958-59, Medical Encyclopedia, Inc., pp. 692-699. 6. Zegarelli, E. V., Denning, C. R., Kutscher, A., Fahn, B., Kirshner, G., and Slaughter, T.: Discoloration of the Teeth in Patients With Cystic Fibrosis: Role of Tetracycline Therapy, Clin. Pediat. (Phila.), 2: 329, 1963. E. V., Kutscher, A., Denning, C. R., and Ragosta, J.: Discoloration of the 7. Zegarelli, Teeth in a 24-Year-Old Patient With Cystic Fibrosis of the Pancreas Not Primarily Associated With Tetracycline Therapy, ORAL SURG. 24: 62, 1967. 8. Stewart, D. J.: The Effects of Tetracycline8 Upon the Dentition, Brit. J. Derm. 76: 374,1964. 9. Boushor, C. F.: ‘(Stained Teeth,” Question and Answer section, J. Amer. Dent. Aqs. 77: 18, 1968. 10. Ku&tad, H. M. : Question and Answer section, Dent. Survey 44: 57, 1968. 11. Caldwell, C. P.: Bleaching Vital or Nonvital Teeth, J. Calif. Dent. Ass. 42: 234, 1966. 12. Younger, H. B.: Bleaching Mottled Enamel, Texas Dent. J. 60: 469, 1942. Peabody, J. B. : Discussion of Dr. Younger’s Paper, Texas Dent. J. 60: 469, 1942. :t Merwe, P. K.: The Removal of the Stain From Mottled Teeth, S. Afr. Dent. J. 18: 31, 1944. 15. Bailey, R. W., and Christen, A. G.: Bleaching of Vital Teeth Stained With Endemic Dental Fluorosis, ORAL SURG.26: 871, 1968. 16. Wainwright, W. W., and Lemoine, F. A.: Rapid Diffuse Penetration of Intact Enamel and Dentin by Carbon-6-14-Labled Urea, J. Amer. Dent. Ass. 41: 135, 1950. 17. Jenkins, G. N.: The Physiology of the Mouth, ed. 3, Philadelphia, 1966, F. A, Davis Company. 18. Mumford, J. M.: Drying of Enamel Under Rubber Dam, Brit. Dent. J. 121: 178, 1966.