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The effect of calcium hydroxide and zinc oxide-eugenol on dentine in extracted human teeth
The effect of calcium hydroxide and zinc oxide-eugenolon dentine in extracted human teeth Louis W. Ripa, D.D.S., M.S.,+ Cesar Guxman, MS., D.M.D.,*+ Wayne Dilzell, D.D.S.,+‘* Rochester, N. Y. EASTMAN
DENTAL
and
CENTER
An in vitro investigation using clinical radiographs and microradiography was designed to test the effects of zinc oxide-eugenol and calcium hydroxide (Dycal) on sound and carious dentine in sixty-four previously extracted human teeth. No change in radiodensity was detected for the sound samples treated with calcium hydroxide or zinc oxide-eugenol or for the carious samples treated with zinc oxideeugenol. Seven of the sixteen carious samples (42 per cent) treated with calcium hydroxide demonstrated, on microradiographs, a radiopaque area beneath the treatment site which was interpreted as a penetration of the calcium hydroxide into the carious dentinal tubuli.
T
he effects of calcium hydroxide and zinc oxide-eugenol are of interest because of the use of these materials on sound dentine for pulp protection and on carious dentine in the indirect pulp treatment technique. In the latter technique a thin layer of carious dentine is left intact in a prepared cavity when it is thought that the removal of all carious tissue might lead to a pulp exposure. Several investigators have studied the effects of calcium hydroxide or zinc oxide-eugenol on sound dentine applied in vivo. IKlein reported that sclerosis of the underlying dentine occurred in 93 per cent of treated teeth when calcium hydroxide was used as a base in deep cavity preparations after the removal of all carious tissue. Mjiir, Finn, and Quigley2 and Mj6r3 applied calicum hydroxide to sound dentine in prepared cavities of permanent teeth which were later extracted for orthodontic reasons and then sectioned. The dentine treated with calcium hydroxide showed an increase in microhardness and microradio*Chairman, Department of Pedodontics. **Chairman, Department of Radiology. ***In private practice, Gretna, La.
531
graphic density, although the response was variable. Zinc oxitle-eugenol produced no difference in microradiographic appearance,” although a slight but, statistically significant change in microhardness was recorded.4 Clarke ant1 Hampson5 reported no histologic changes when they assessed ground sections of dentin prepared from buccal cavities to which a mixture of zinc oxide and oil of cloves had been applied in viva. The application of calcium hydroxide or zinc oxide-eugenol to cnrious dentine has been studied with regard to the indirect pulp treatment technique. Sowden and Law and Lewis7 observed, on clinical radiographs, an increase in the radiopacity of the residual carious dentine as early as 7 days after treatment with calcium hydroxide. Sowden interpreted this change as remineralization of carious tissue. Ehrenreich8 reported t,hat zinc oxide-eugenol was effective in increasing the microhardness and causing remineralization of carious dentine in vivo, while dentine treated with calcium hydroxide showed no change. Kerkove and associates9 reported that neither calcium hydroxide nor zinc oxide-eugenol was consistently associated with radiopaque changes in dentine ; nor did they find radiographic evidence of remineralization of the residual carious dentine. However, when teeth were reopened one year after treatment, they found that the residual carious dentine was dry and hard, similar to an arrested lesion. King and associates’O also reopened teeth subjected to indirect pulp treatment with either calcium hydroxide or zinc oxide-eugenol; they also found the dentine to be harder than at the time of initial excavation. It was thought that the lack of uniformity in the reported clinical results might be a reflection of variable pulpal viability and response. Therefore, we decided to investigate the effects of calcium hydroxide and zinc oxide-eugenol on sound and carious dentine in already extracted teeth in which a “vital response” would not be possible. Any change reported might be attributed to an interaction between the dentine and the medicating agent per se, rather than to an intervening systemic factor. METHODS Noncarious
AND MATERIALS dentine
Thirty-two teeth were selected from noncarious, unrestored extracted premolars and permanent molars. The occlusal enamel was removed with a rotating diamond wheel to leave a flat dentine surface. The buccal and lingual surfaces were cut parallel to each other, so that all enamel was removed and a relatively rectangular block of dentine remained. The teeth were individually mounted on a plastic stage so that the flat top surface was parallel with the bottom of the stage (Fig. 1). The medication was placed on one half of the flattened occlusal surface of each tooth. The untreated half of each tooth served as its own control. Sixteen teeth were treated with zinc oxide-eugenol* and sixteen with calcium hydr0xide.t The teeth were stored at all times in a high-humidity environment. *U.S.P. Chemicals; 250 mg. zinc oxide, 5 cc. eugenol. tDyca1, L. D. Caulk Co., Milford, Del. (Base-titanium dioxide Catalyst-calcium hydroxide [53.5 per cent], zinc oxide [9.7 per cent] fonamide.)
in glycol salicylate. in ethyl toluene sul-
Efect of CaOH and ZOE on dentine
Volume 34 Number 3
533
Fig. 1. Noncarious tooth mounted on plastic stage. The top of the tooth has been cut parallel with the stage, so that there will be no radiographic superimposition between the medication and the treated dentine. Buecal and lingual enamel have been removed to enhance visualization of the dentine on the radiograph.
All thirty-two treated teeth were radiographed before and immediately after the medication was applied. Standard clinical radiographic techniques were used, employing a long (16-inch) cone, 10 Ma., 65 KVP, and an exposure time of 1 second. A holder for the film and mounted teeth was designed so that the teeth could always be radiographed in the same position relative to the film and x-ray source. Two weeks after treatment the thirty-two teeth were again clinically radiographed, after which eight of them (four treated with calcium hydroxide and four treated with zinc oxide-eugenol) were embedded in Ward’s Bioplastic, and longitudinal ground sections, approximately 150 microns thick, were prepared with a Gillings-Hamco thin sectioning machine. A representative section from each tooth was mounted on Eastman Kodak 649-O spectroscopic plates, and microradiographs were prepared by means of a Picker x-ray machine with a copper target. The unit was operated at 10 Ma., 20 KVP. The x-ray target-tospectroscopic-plate distance was 10 cm., and the exposure time was approximately 4 minutes. Three months following treatment the twenty-four teeth remaining were again clinically radiographed, after which four teeth treated with calcium hydroxide and four teeth treated with zinc oxide-eugenol were sectioned and microradiographs were prepared as described. The same procedure was followed at 6 months for the sixteen teeth remaining and at 1 year, when the last eight teeth were clinically radiographed and all were sectioned for microradiographic study. Table I presents the schedule for taking clinical radiographs and for the sectioning and microradiography. Microradiographs were evaluated microscopically at the end of the study by a single examiner with no knowledge of which treatment agent had been used. Carious
dentine
Thirty-two carious, unrestored premolars and permanent molars were mounted on plastic stages. The crowns were cut to expose a maximum of the
Oral Surg. September, 1972
Ripa, Gunman, and Dike11
534
Table I. Schedule of clinical sixty-four teeth in this study
radiography
and microradiography
Radiographic
T’reatment agent Noncarious teeth Total
nonearious
Carious teeth
Total
Zinc oxideeugenol Calcium hydroxide teeth
Zinc oxideeugenol Calcium hydroxide carious
teeth
No.of
Pre-
teeth per grozlp
‘ze$-
Immeai$$\~e$-
B weeks posttreatment
3 months posttreatment
C”
C
c
16
16
16
16
4
12
4
16
16
16
16
4
12
32
32
32
32
Is@lt
and sectioning
s
c
ii
1S$M
for the schedule
6 months posttreatment c
1 year posttreatment
IS&M
c
IS&&f
8
4
4
4
4
8
4
4
4
s
__16
8
s
;
16
4
4
4
4
16
4
4
4
4
32
s
s
s
s
“C = Clinical radiography. tS & M = Sectioning and microradiography.
carious dentine surface. Calcium hydroxide was applied to one half of the exposed surface of sixteen teeth ; zinc oxide-eugenol was applied in the same fashion to the remaining sixteen teeth. The nontreated carious half of each tooth served as its own control. Because the carious test areas were not flat, it was impossible to obtain clinical radiographs without superimposition of the medicating agent over areas of the treated dentine ; therefore, clinical radiographs of the carious samples were not taken. Four teeth treated with calcium hydroxide and four treated with zinc oxide-eugenol were embedded and sectioned at intervals of 2 weeks, 3 months, 6 months, and 12 months (Table I). Microradiographs of representative sections were prepared and analyzed as previously described. RESULTS Noncarious
dentine
By the two methods used to evaluate the effects of calcium hydroxide and zinc oxide-eugenol (that is, clinical radiographs of “intact” teeth and microradiographs of longitudinal ground sections), no difference in radiodensity between the control and treatment sides was observed in any of the thirty-two samples of sound dentine. Fig. 2 shows a radiograph, taken 6 months postoperatively, of a noncarious tooth treated with zinc oxide-eugenol. Note the similar radiographic density of both the control and treated dentine. The sections shown in Fig. 3 are characteristic of the uniform density observed microradiographically for the noncarious series. Carious
dentine
Of the sixteen carious samples treated with zinc oxide-eugenol, none showed a change in radiodensity during the observation period of 2 weeks to 1 year (Fig. 4).
Volume Number
after
34 3
Efect
of CaOH and ZOE on dentine
535
Fig. 8. Noncarious tooth treated with zinc oxide-eugenol. Radiograph taken 6 months application. There is no difference in radiodensity between treated and control surfaces.
Pig. 3. Microradiographs of control (A) and treated (B) dentinal surfaces from a soncarious tooth treated with zinc oxide-eugenol. (The zinc oxide-eugenol was lost during sectioning.) No difference in radiodensity between the two sides is evident. (Magnification, x35.)
Of the sixteen carious teeth treated with calcium hydroxide, seven (42 per cent) showed a difference in radiodensity between treated and control sides. In all instances the treated side was more radiopaque than the control side. Fig. 5 shows microradiographic images of a calcium hydroxide-treated sample. Note the penetration of the radiopaque medication into the carious dentinal tubules. This change was observed in one sample at each of the first three time intervals-2 weeks, 3 months, and 6 months-and in all four of the teeth in which calcium hydroxide had been in place for 12 months. DISCUSSION In the absence of vital pulp tissue, none of the sixty-four teeth demonstrated a change in radiodensity similar to that reported in the in vivo situation. This negative result lends indirect support to the concept that a “vital response” of the tooth to the medicating agent or to the residual caries is necessary for this reported clinical change to occur.
Fig. 4. Microradiographs of control (A) and treated (B) dentinal surfaces from a cnrious tooth treated with zinc oxide-eugenol. Dentinal tubules are clearlg outlined in thrb carious tissue, There is no difference in radiodensity betwen the tvo sides. (Magnification, x100.)
Fig. 5. Microradiographs of control (A and f) and treated (H and 11) dentinal surfaces from a carious tooth treated with calcium hytlroxide. The calcium hydroxide has penetrated patent carious dentinal tubules. (Magnifications: A and B, x35; C and I), x100.)
The only series of teeth in which a change in radiodensity was recorded was the carious teeth treated with calcium hydroxide. The increased radiopacity was limited to discrete areas of the carious surface and appeared to be the result of a physical penetration of the calcium hydroxide into the carious dentine, following the direction of the dentinal tubules. While 42 per cent of the sixteen carious teeth treated with calcium hydroxide showed this change, it was not observed
Volume 34 Number 3
Effect of CaOH and ZOE on dentine
537
in the sixteen sound teeth treated with calcium hydroxide. Johansen and Parksll have reported a widening of the dentinal tubules and loss of intertubular matrix at the superficial margin of dentinal caries. Apparently, the carious process opened spaces in the affected dentine wide enough for the calcium hydroxide to penetrate. The normal-sized dental tubules and intertubular structure in sound dentine prevented a similar penetration. None of the thirty-two sound or carious teeth treated with zinc oxideeugenol demonstrated any penetration. Zinc oxide-eugenol, at the consistency tested, lacks the physical penetrating ability of calcium hydroxide, even when applied to carious dentine. While extrapolation from an in vitro experiment to the in vivo situation is tenuous, the penetration of calcium hydroxide into carious tissue might have clinical significance, especially in teeth in which an indirect pulp treatment is performed. Such physical penetration should provide additional sealing of patent dentinal tubules which, in the in vivo situation, might serve as pathways for the progression of bacterial and chemical irritants into the pulp. This action is desirable in terms of maintaining pulp vitality. REFERENCES 1. Klein,
2. 3. 4. 5.
A. I.: Association Between Deciduous Dentin Sclerosis and Calcium Hydroxide Methvleellulose Base Material, J. Am. Dent. Assoc. 63: 93-190, 1961. MjSr,” I. A., Finn, S. B., and ‘Quigley, M. B.: The Effect of Calcium Hydroxide and Amalgam on Non-carious, Vital Dentlne, Arch. Oral Biol. 3: 283-291, 1961. MjBr, I. A.: Histologic Studies of Human Coronal Dentine From the Insertion of Various Materials in Experimentally Prepared Cavities, Arch. Oral Biol 12: 441-452, 1967. MjGr, I. A.: The effect of Zinc Oxide and Eugenol on Dentine Evaluated by Microhardness Testing, Arch. Oral Biol. 7: 333-336, 1962. Clarke, J., and Hampson, E. L.: Effect of Cavity Preparation and Filling Materials on Human Dentine With Special Reference to Polystyrene Lining Agents, Br. Dent. J. 124:
456-461.
1968.
6. Sowden, J. ‘R.: A Preliminary Report on the Recalcifications of Carious Dentin, J. Dent. Child. 23: 187-188, 1956. 7. Law, D. B., and Lewis, T. M.: The Effect of Calcium Hydroxide on Deep Carious Lesions. ORAL Sum.14: 1130-1137.1961. D. W.: A Comparison of the Effects of Zinc Oxide-Eugenol and Cal8. Ehrenreich, cium Hydroxide on Carious Dentin in Human Primary Molars, J. Dent. Child. 35: 451-456, 1968. B. C., Jr., Herman, 8. C., Klein, A. I., and McDonald, R. E.: A Clinical and 9. Kerkove, Densitometric Evaluation of the Indirect Pulp Capping Technique, J. Dent. Child. 34: 192-201, 1967. J. J., and Lindahl, R. L.: Indirect Pulp Capping: A Bac10. King, J. B., Crawford, teriologic Study of Deep Carious Dentine m Human Teeth, ORAL SURG. 20: 663-671, 1965. 11. Johansen, E., and Parks, H. F.: Electron-Microscopic Observations on Soft Carious Human Dentin, J. Dent. Res. 40: 235-248, 1961. Reprint requests to : Dr. L. W. Ripa Eastman Dental Center 800 E. Main St. Rochester, N. Y. 14603
DENTAL
and
CENTER
An in vitro investigation using clinical radiographs and microradiography was designed to test the effects of zinc oxide-eugenol and calcium hydroxide (Dycal) on sound and carious dentine in sixty-four previously extracted human teeth. No change in radiodensity was detected for the sound samples treated with calcium hydroxide or zinc oxide-eugenol or for the carious samples treated with zinc oxideeugenol. Seven of the sixteen carious samples (42 per cent) treated with calcium hydroxide demonstrated, on microradiographs, a radiopaque area beneath the treatment site which was interpreted as a penetration of the calcium hydroxide into the carious dentinal tubuli.
T
he effects of calcium hydroxide and zinc oxide-eugenol are of interest because of the use of these materials on sound dentine for pulp protection and on carious dentine in the indirect pulp treatment technique. In the latter technique a thin layer of carious dentine is left intact in a prepared cavity when it is thought that the removal of all carious tissue might lead to a pulp exposure. Several investigators have studied the effects of calcium hydroxide or zinc oxide-eugenol on sound dentine applied in vivo. IKlein reported that sclerosis of the underlying dentine occurred in 93 per cent of treated teeth when calcium hydroxide was used as a base in deep cavity preparations after the removal of all carious tissue. Mjiir, Finn, and Quigley2 and Mj6r3 applied calicum hydroxide to sound dentine in prepared cavities of permanent teeth which were later extracted for orthodontic reasons and then sectioned. The dentine treated with calcium hydroxide showed an increase in microhardness and microradio*Chairman, Department of Pedodontics. **Chairman, Department of Radiology. ***In private practice, Gretna, La.
531
graphic density, although the response was variable. Zinc oxitle-eugenol produced no difference in microradiographic appearance,” although a slight but, statistically significant change in microhardness was recorded.4 Clarke ant1 Hampson5 reported no histologic changes when they assessed ground sections of dentin prepared from buccal cavities to which a mixture of zinc oxide and oil of cloves had been applied in viva. The application of calcium hydroxide or zinc oxide-eugenol to cnrious dentine has been studied with regard to the indirect pulp treatment technique. Sowden and Law and Lewis7 observed, on clinical radiographs, an increase in the radiopacity of the residual carious dentine as early as 7 days after treatment with calcium hydroxide. Sowden interpreted this change as remineralization of carious tissue. Ehrenreich8 reported t,hat zinc oxide-eugenol was effective in increasing the microhardness and causing remineralization of carious dentine in vivo, while dentine treated with calcium hydroxide showed no change. Kerkove and associates9 reported that neither calcium hydroxide nor zinc oxide-eugenol was consistently associated with radiopaque changes in dentine ; nor did they find radiographic evidence of remineralization of the residual carious dentine. However, when teeth were reopened one year after treatment, they found that the residual carious dentine was dry and hard, similar to an arrested lesion. King and associates’O also reopened teeth subjected to indirect pulp treatment with either calcium hydroxide or zinc oxide-eugenol; they also found the dentine to be harder than at the time of initial excavation. It was thought that the lack of uniformity in the reported clinical results might be a reflection of variable pulpal viability and response. Therefore, we decided to investigate the effects of calcium hydroxide and zinc oxide-eugenol on sound and carious dentine in already extracted teeth in which a “vital response” would not be possible. Any change reported might be attributed to an interaction between the dentine and the medicating agent per se, rather than to an intervening systemic factor. METHODS Noncarious
AND MATERIALS dentine
Thirty-two teeth were selected from noncarious, unrestored extracted premolars and permanent molars. The occlusal enamel was removed with a rotating diamond wheel to leave a flat dentine surface. The buccal and lingual surfaces were cut parallel to each other, so that all enamel was removed and a relatively rectangular block of dentine remained. The teeth were individually mounted on a plastic stage so that the flat top surface was parallel with the bottom of the stage (Fig. 1). The medication was placed on one half of the flattened occlusal surface of each tooth. The untreated half of each tooth served as its own control. Sixteen teeth were treated with zinc oxide-eugenol* and sixteen with calcium hydr0xide.t The teeth were stored at all times in a high-humidity environment. *U.S.P. Chemicals; 250 mg. zinc oxide, 5 cc. eugenol. tDyca1, L. D. Caulk Co., Milford, Del. (Base-titanium dioxide Catalyst-calcium hydroxide [53.5 per cent], zinc oxide [9.7 per cent] fonamide.)
in glycol salicylate. in ethyl toluene sul-
Efect of CaOH and ZOE on dentine
Volume 34 Number 3
533
Fig. 1. Noncarious tooth mounted on plastic stage. The top of the tooth has been cut parallel with the stage, so that there will be no radiographic superimposition between the medication and the treated dentine. Buecal and lingual enamel have been removed to enhance visualization of the dentine on the radiograph.
All thirty-two treated teeth were radiographed before and immediately after the medication was applied. Standard clinical radiographic techniques were used, employing a long (16-inch) cone, 10 Ma., 65 KVP, and an exposure time of 1 second. A holder for the film and mounted teeth was designed so that the teeth could always be radiographed in the same position relative to the film and x-ray source. Two weeks after treatment the thirty-two teeth were again clinically radiographed, after which eight of them (four treated with calcium hydroxide and four treated with zinc oxide-eugenol) were embedded in Ward’s Bioplastic, and longitudinal ground sections, approximately 150 microns thick, were prepared with a Gillings-Hamco thin sectioning machine. A representative section from each tooth was mounted on Eastman Kodak 649-O spectroscopic plates, and microradiographs were prepared by means of a Picker x-ray machine with a copper target. The unit was operated at 10 Ma., 20 KVP. The x-ray target-tospectroscopic-plate distance was 10 cm., and the exposure time was approximately 4 minutes. Three months following treatment the twenty-four teeth remaining were again clinically radiographed, after which four teeth treated with calcium hydroxide and four teeth treated with zinc oxide-eugenol were sectioned and microradiographs were prepared as described. The same procedure was followed at 6 months for the sixteen teeth remaining and at 1 year, when the last eight teeth were clinically radiographed and all were sectioned for microradiographic study. Table I presents the schedule for taking clinical radiographs and for the sectioning and microradiography. Microradiographs were evaluated microscopically at the end of the study by a single examiner with no knowledge of which treatment agent had been used. Carious
dentine
Thirty-two carious, unrestored premolars and permanent molars were mounted on plastic stages. The crowns were cut to expose a maximum of the
Oral Surg. September, 1972
Ripa, Gunman, and Dike11
534
Table I. Schedule of clinical sixty-four teeth in this study
radiography
and microradiography
Radiographic
T’reatment agent Noncarious teeth Total
nonearious
Carious teeth
Total
Zinc oxideeugenol Calcium hydroxide teeth
Zinc oxideeugenol Calcium hydroxide carious
teeth
No.of
Pre-
teeth per grozlp
‘ze$-
Immeai$$\~e$-
B weeks posttreatment
3 months posttreatment
C”
C
c
16
16
16
16
4
12
4
16
16
16
16
4
12
32
32
32
32
Is@lt
and sectioning
s
c
ii
1S$M
for the schedule
6 months posttreatment c
1 year posttreatment
IS&M
c
IS&&f
8
4
4
4
4
8
4
4
4
s
__16
8
s
;
16
4
4
4
4
16
4
4
4
4
32
s
s
s
s
“C = Clinical radiography. tS & M = Sectioning and microradiography.
carious dentine surface. Calcium hydroxide was applied to one half of the exposed surface of sixteen teeth ; zinc oxide-eugenol was applied in the same fashion to the remaining sixteen teeth. The nontreated carious half of each tooth served as its own control. Because the carious test areas were not flat, it was impossible to obtain clinical radiographs without superimposition of the medicating agent over areas of the treated dentine ; therefore, clinical radiographs of the carious samples were not taken. Four teeth treated with calcium hydroxide and four treated with zinc oxide-eugenol were embedded and sectioned at intervals of 2 weeks, 3 months, 6 months, and 12 months (Table I). Microradiographs of representative sections were prepared and analyzed as previously described. RESULTS Noncarious
dentine
By the two methods used to evaluate the effects of calcium hydroxide and zinc oxide-eugenol (that is, clinical radiographs of “intact” teeth and microradiographs of longitudinal ground sections), no difference in radiodensity between the control and treatment sides was observed in any of the thirty-two samples of sound dentine. Fig. 2 shows a radiograph, taken 6 months postoperatively, of a noncarious tooth treated with zinc oxide-eugenol. Note the similar radiographic density of both the control and treated dentine. The sections shown in Fig. 3 are characteristic of the uniform density observed microradiographically for the noncarious series. Carious
dentine
Of the sixteen carious samples treated with zinc oxide-eugenol, none showed a change in radiodensity during the observation period of 2 weeks to 1 year (Fig. 4).
Volume Number
after
34 3
Efect
of CaOH and ZOE on dentine
535
Fig. 8. Noncarious tooth treated with zinc oxide-eugenol. Radiograph taken 6 months application. There is no difference in radiodensity between treated and control surfaces.
Pig. 3. Microradiographs of control (A) and treated (B) dentinal surfaces from a soncarious tooth treated with zinc oxide-eugenol. (The zinc oxide-eugenol was lost during sectioning.) No difference in radiodensity between the two sides is evident. (Magnification, x35.)
Of the sixteen carious teeth treated with calcium hydroxide, seven (42 per cent) showed a difference in radiodensity between treated and control sides. In all instances the treated side was more radiopaque than the control side. Fig. 5 shows microradiographic images of a calcium hydroxide-treated sample. Note the penetration of the radiopaque medication into the carious dentinal tubules. This change was observed in one sample at each of the first three time intervals-2 weeks, 3 months, and 6 months-and in all four of the teeth in which calcium hydroxide had been in place for 12 months. DISCUSSION In the absence of vital pulp tissue, none of the sixty-four teeth demonstrated a change in radiodensity similar to that reported in the in vivo situation. This negative result lends indirect support to the concept that a “vital response” of the tooth to the medicating agent or to the residual caries is necessary for this reported clinical change to occur.
Fig. 4. Microradiographs of control (A) and treated (B) dentinal surfaces from a cnrious tooth treated with zinc oxide-eugenol. Dentinal tubules are clearlg outlined in thrb carious tissue, There is no difference in radiodensity betwen the tvo sides. (Magnification, x100.)
Fig. 5. Microradiographs of control (A and f) and treated (H and 11) dentinal surfaces from a carious tooth treated with calcium hytlroxide. The calcium hydroxide has penetrated patent carious dentinal tubules. (Magnifications: A and B, x35; C and I), x100.)
The only series of teeth in which a change in radiodensity was recorded was the carious teeth treated with calcium hydroxide. The increased radiopacity was limited to discrete areas of the carious surface and appeared to be the result of a physical penetration of the calcium hydroxide into the carious dentine, following the direction of the dentinal tubules. While 42 per cent of the sixteen carious teeth treated with calcium hydroxide showed this change, it was not observed
Volume 34 Number 3
Effect of CaOH and ZOE on dentine
537
in the sixteen sound teeth treated with calcium hydroxide. Johansen and Parksll have reported a widening of the dentinal tubules and loss of intertubular matrix at the superficial margin of dentinal caries. Apparently, the carious process opened spaces in the affected dentine wide enough for the calcium hydroxide to penetrate. The normal-sized dental tubules and intertubular structure in sound dentine prevented a similar penetration. None of the thirty-two sound or carious teeth treated with zinc oxideeugenol demonstrated any penetration. Zinc oxide-eugenol, at the consistency tested, lacks the physical penetrating ability of calcium hydroxide, even when applied to carious dentine. While extrapolation from an in vitro experiment to the in vivo situation is tenuous, the penetration of calcium hydroxide into carious tissue might have clinical significance, especially in teeth in which an indirect pulp treatment is performed. Such physical penetration should provide additional sealing of patent dentinal tubules which, in the in vivo situation, might serve as pathways for the progression of bacterial and chemical irritants into the pulp. This action is desirable in terms of maintaining pulp vitality. REFERENCES 1. Klein,
2. 3. 4. 5.
A. I.: Association Between Deciduous Dentin Sclerosis and Calcium Hydroxide Methvleellulose Base Material, J. Am. Dent. Assoc. 63: 93-190, 1961. MjSr,” I. A., Finn, S. B., and ‘Quigley, M. B.: The Effect of Calcium Hydroxide and Amalgam on Non-carious, Vital Dentlne, Arch. Oral Biol. 3: 283-291, 1961. MjBr, I. A.: Histologic Studies of Human Coronal Dentine From the Insertion of Various Materials in Experimentally Prepared Cavities, Arch. Oral Biol 12: 441-452, 1967. MjGr, I. A.: The effect of Zinc Oxide and Eugenol on Dentine Evaluated by Microhardness Testing, Arch. Oral Biol. 7: 333-336, 1962. Clarke, J., and Hampson, E. L.: Effect of Cavity Preparation and Filling Materials on Human Dentine With Special Reference to Polystyrene Lining Agents, Br. Dent. J. 124:
456-461.
1968.
6. Sowden, J. ‘R.: A Preliminary Report on the Recalcifications of Carious Dentin, J. Dent. Child. 23: 187-188, 1956. 7. Law, D. B., and Lewis, T. M.: The Effect of Calcium Hydroxide on Deep Carious Lesions. ORAL Sum.14: 1130-1137.1961. D. W.: A Comparison of the Effects of Zinc Oxide-Eugenol and Cal8. Ehrenreich, cium Hydroxide on Carious Dentin in Human Primary Molars, J. Dent. Child. 35: 451-456, 1968. B. C., Jr., Herman, 8. C., Klein, A. I., and McDonald, R. E.: A Clinical and 9. Kerkove, Densitometric Evaluation of the Indirect Pulp Capping Technique, J. Dent. Child. 34: 192-201, 1967. J. J., and Lindahl, R. L.: Indirect Pulp Capping: A Bac10. King, J. B., Crawford, teriologic Study of Deep Carious Dentine m Human Teeth, ORAL SURG. 20: 663-671, 1965. 11. Johansen, E., and Parks, H. F.: Electron-Microscopic Observations on Soft Carious Human Dentin, J. Dent. Res. 40: 235-248, 1961. Reprint requests to : Dr. L. W. Ripa Eastman Dental Center 800 E. Main St. Rochester, N. Y. 14603