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A comparison of two temporary restorations: Light-cured resin versus a self-polymerizing temporary restoration
comparison of two temporary restorations: Light-cured resin versus a self-polymerizing temporary restoration Darlene Melton, BA, DDS,a Stuart Cobb, BS, DDS,O and Keith V. Krell, DDS, MS. IIIA,~ Iowa City, Iowa COLLEGE OF DENTISTRY, UNIVERSITY OF IOWA Temporary restorative materials are an important component of endodontic therapy. They must both adequately seal the access preparation between visits and protect the obturated canal(s) from microleakage until a permanent restoration can be placed. The efficacy of Cavit and T.E.R.M. (a new light-cured composite product) was compared with the use of a carbon black coronal microleakage protocol. The teeth examined had previously received coronal restorations. After the teeth were accessed, restored with Cavit or T.E.R.M., and exposed to the dye, they were cleared. Three-dimensional assessment then revealed that Cavit more consistently provided an effective seal. In addition, a great deal of microleakage was observed around the permanent restoration-tooth interface. This indicates that perhaps leaking permanent restorations should be removed in their entirety before initiation of endodontic treatment. (ORAL SURC ORAL MED ORAL PATHOL 1990;70:221-5)
R
outine endodontic therapy cannot always be completed in one visit, and frequently temporization of the accessis needed. The material sealing the accessshould prevent bacterial ingress, yet allow easy removal at subsequent visits. Several studies have dealt with the sealing ability of temporary restorative materials. ‘, 2 These authors have concerned themselves with intra-appointment sealability of temporary restorations, to prevent bacterial ingress or medicinal leakage from the unobturated root canal system. Recently, Swanson and Madison3 found that after a 3-day period a significant amount of coronal microleakage occurred in obturated but nontemporized human teeth. They postulated that deficient coronal seal with resultant coronal microleakage may very well be an etiologic factor for endodontic failure. Thesestudies emphasizethe importance of preventing recontamination of debrided and obturated canals. Because of the results from past sealability studies,4-9Cavit (Premier Dental Co., Norristown, Pa.), a pre-mixed, single paste, tube-dispensed com-
pound, has probably become the most extensively used temporary restorative material. However, controversy related to the use of Cavit as a temporary filling in endodontics still exists. Recently, a new light-cured, compule-dispensed endodontic composite temporary restorative material (T.E.R.M. compules, Caulk/Dentsply, Milford, Delaware) was introduced. Promotional literature that cited and illustrated results from a silver nitrate microleakage experiment involving noncarious, unrestored teeth found T.E.R.M. to be far superior to Cavit.‘O However, the T.E.R.M. material requires a light cure system that may not be a part of most endodontists’ armamentarium. Teplitsky and Meimaris’ 1found that Cavit maintained an effective seal 91.7% of the time whereas T.E.R.M. maintained an effective seal 33.3% of the time. These discrepancies in findings suggestfurther research is warranted. Therefore, the purpose of this study was to compare the sealing properties of Cavit and T.E.R.M. under two different conditions (as described in the Materials and Methods section). MATERIALS
aFormer Graduate Students, Department of Endodontics. bAssociate Professor, Department of Endodontics. 7/15/12442
AND METHODS
The study was performed in two phases. In phase I, 34 extracted human anterior and premolar teeth 221
222
Melton, Cobb, and Krell
Table
1.Leakage (in mm) Group I (Cavit)
1. Fractured-discarded 2. Fractured-discarded 3.0 mm
ORAL SURGORAL MED ORAL PATHOL August 1990
Group III (etch/Cavit)
Group II (T.E.R.M.)
1.5 mm 2. Fractured-discarded
1.0 mm 2. Fx-discard
4.0 5.0 6.0 7.0 8.0
3.0 4.5 5.0 6.0 7.0 8.2
3.0 4.0 5.0 6.0 7.0 8.0
X = 0 (Cavit’s)
X = 4.4 (T.E.R.M.‘s)
Microleakage
measured in the teeth used in phase 1 by experimental
Group IV (etch/T.E.R.M.)
1.5 mm 2.0 3.0 4.0 5.0 6. Fx-discard 7.0 8.5
group
were collected. The teeth were stored in deionized water with thymol until ready for experimentation. One operator performed standard endodontic access preparations on all 34 teeth with a No. 557 high-speed water-cooled carbide bur. No attempt was made to debride the radicular pulp spaces,and the teeth were randomly placed into four groups of eight teeth each. Two teeth were left to serve as controls. Dry cotton pellets were placed on the chamber floor, and then standard accesspreparations were sealed with one of four techniques: (1) Cavit alone, (2) T.E.R.M. alone, (3) acid etching and Cavit, and (4) acid etching with T.E.R.M. Manufacturer’s directions were followed for placement of the materials, with the exception of the introduction of the 37% phosphoric acid etchant variable. (The manufacturer of T.E.R.M. does not specify the need for the etching procedure). Root surfaces and unrestored carious lesions were coated with sticky wax. The entire root and crown of the negative control was covered with sticky wax, whereasthe positive control had the root covered with wax, but no temporary restoration was placed. Teeth were stored 1 week at 37’ C in an artificial saliva solution (1 ml calcium chloride, 3 ml monosodium acid phosphate, 20 ml sodium bicarbonate). All specimens were then transferred to an Indian ink solution (Pelikan ink; Gunther Wagner) for 48 hours to demonstrate the presence of coronal microleakage. After dye exposure, the sticky wax was removed and the teeth decalcified in 5% nitric acid for 48 hours with constant stirring, followed by 4 hours of immersion in a running water bath. The teeth were dehydrated overnight in 80% ethyl alcohol followed by two hourly rinses of 90% ethyl alcohol and three hourly rinses of 100% ethyl alcohol. The teeth were cleared and rendered transparent by placing them in a methyl salicylate solution. After clearing, all teeth with stained coronal fracture lines wre removed from the study to eliminate the
previously undetected fractures as potential leakage sources. Of the 32 experimental teeth, 5 had to be eliminated because of fractures. A blinded assessmentof dye penetration in the remaining teeth was performed by two other operators, independent from the restoring dentist, each using a 7-power illuminated viewer (Mitutoyo Co., Japan). Three teeth failed to decalcify and clear completely, so these teeth were sectioned longitudinally to enable linear dye penetration assessment. Phase II was similar to phase I except for two major changes. Twenty-four teeth were selected and prepared as in phase I. Acid etching was not performed, so the two experimental groups consisted of 12 teeth restored with Cavit and 12 with T.E.R.M. After 1 week in the artificial saliva solution, all teeth were thermocycled between water baths maintained at 10” C + 2” C and 50” C f 2” C for 540 cycles, remaining in each bath for 60 seconds.The dye penetration and penetration assessmentsteps were then carried out as per phase I. Statistical analysis of the data from phaseI was not required. In phase II, an unpaired t test was used for comparison. RESULTS
The positive control demonstrated gross dye ingress, whereas the negative control showed no dye penetration. In phaseI, none of the teeth restored with Cavit (groups I and III) showedany leakage, whereas 9 of the 14 teeth restored with T.E.R.M. were leakage free. Becausethe differences were obvious, statistical analysis was deemedunnecessary.Data summarization may be seenin Table I. Of the teeth restored with T.E.R.M. with coronal leakage (n = 5), the mean dye penetration was 4.4 mm. Acid etching did not appear to be a factor in leakage reduction for either material. In phase II, only 1 of 12 teeth restored with Cavit exhibited detectable microleakage (Fig, 1, A and B),
Volume 70 Number 2
Light-cured
resin versus self-polymerizing
temporary restoration
223
Fig. 1. A, Mesial view of cleared premolar restored with Cavit. B, Distal view of cleared premolar restored with Cavit.
Fig. 2. A, Mesial view of cleared premolar restored with T.E.R.M. B, Distal view of cleared premolar restored with T.E.R.M.
whereas 6 of 12 teeth restored with T.E.R.M. displayed leakage (Fig. 2, A and B). A t = -2.057 was significant at p < 0.05. A summary of specific results may be seen in Table II.
Table
II. Leakage (in mm) Cavit 1.0 mm 2.0 3.0 4.0 5.0 6.0 7.2 8.0 9.0 10.0 11.0 12.0 ti = 0.16
DISCUSSION
Manufacturer’s directions were closely followed for placement of the temporary restorative materials. As per the recommendations of Webber and coworkers,‘* we attempted to ensure that all Cavit restorations were at least 3.5 mm in depth. An equal (or greater) thickness of T.E.R.M. was used, although the manufacturer does not claim that this is necessary. Two layers of T.E.R.M. were successively placed, with each placement followed by a 30-second application of visible light to ensure complete polymerization. Cavit’s compressivestrength has been shown to be less than that of zinc oxide+ugenol and zinc phosphate cement.6The T.E.R.M. versus Cavit investigation also claims superior Shore A50 hardness and tensile and compressive strengths with T.E.R.M.‘O Although this may be true, clinical experience has shown that an adequate bulk of Cavit, as used here, suitably withstands masticatory stress between appointments if used to seal a routine accesspreparation. (Most likely, neither Cavit nor T.E.R.M. would be recommended to replace large amounts of missing tooth structure when a badly broken down tooth is treated). As alluded to before, the one main departure from the manufacturer’s recommendations involved the use of acid etching of exposed enamel before placement of restoration in two of the four groups in phase I. (The manufacturer of T.E.R.M. does not state that etching is required). It was decided to include this variable out of curiosity, primarily be-
I
Microleakage
measured
T.E.R.M. 1.0 mm 2.1 3.1 4.2 5.4 6.2 7.2 8.0 9.0 10.0 11.0 12.0 x= 1.0
by the teeth
used in phase
II by experimental
group.
causeof the plethora of restorative dentistry literature showing that etching greatly increases bond strength and decreasesmarginal microleakage for composite restorations. However, acid etching was not found to have any modifying effect on leakage reduction in the two phaseI experimental groups in which etchant was employed. Therefore, it was not used in phase II. After the clearing process, all teeth with stained, previously undetectable fracture lines were removed from the study to eliminate the fracture as a leakage source. Five teeth were discarded from the experimental teeth in phase I (none in Phase II), somewhat diminishing the sample size. However, approximately equal numbers of teeth restored with Cavit and T.E.R.M. were discarded, and the decreasedsample size still rather dramatically portrayed the differences in leakage betweenthe two materials. Our results tend to confirm those of Teplitsky and Meimaris in their
224
Melton, Cobb, and Krell
Table
III. Cavit-T.E.R.M. leakage
ORAL SURG ORAL MED ORAL PATHOL August I990
Unpaired s test DF:
Xl: Trealment Unpaired t value.
YI: Leakage Prob. (I-tail):
22
-2.057
0.0259
Group
count
Mean
SD
SE
Cavit T.E.R.M.
12 12
0.167 1
0.577 1.279
0.167 0.369
recent work. 11Although their method departed somewhat from that used in this study, they showed that Cavit maintained an effective marginal seal 9 1.7%of the time versus only 33.3% for T.E.R.M. None of the teeth in either of the Cavit groups in phase I of this study were found to exhibit leakage, whereas 67% of the composite-filled teeth were free from leakage. Of the 33% of the composite-filled teeth that did demonstrate leakage (n = 4), an average penetration depth of 4.4 mm was recorded. As before, no specific statistical analysis was considered necessary. Phase II was included in the investigation, primarily to determine whether thermocycling might alter the results. Thermocycling probably more closely approximates the intraoral milieu. Moreover, the manufacturer’s study used thermocycling, and the investigators wanted to follow that microleakage protocol as closely as possible. As hypothesized, phase II results were indeed somewhat different from those of phase I. One of the 12 teeth restored with Cavit did exhibit microleakage, but 6 of the 12 teeth restored with T.E.R.M. leaked. Thus, a higher percentage of teeth restored with T.E.R.M. leaked in Phase II, but the mean depth of leakage was less than for the teeth in phase I. The means (0.167 mm for Cavit versus 1.O mm for T.E.R.M.) were, however, significantly different statistically. Our study also used an artificial saliva solution for sample storage. This was believed to again more closely resemblethe intraoral environment than would storage in distilled water, as has been done in previous investigations. In this study, the teeth were cleared, enabling a three-dimensional assessment of the carbon black coronal marginal microleakage. This was deemed preferable to the standard practice of longitudinally sectioning a sample and examining leakage in a random sagittal plane of the restorative material, as was the case in the manufacturer’s investigation. However, as mentioned before, the investigators were forced to longitudinally section three samplesbecause of incomplete decalcification and clearing. Since Cavit setsand expands by absorbing moisture,6 a lon-
gitudinal cross section of a Cavit specimen would be more likely to show dye ingress than would the cross section of a less hydrophilic material, such as T.E.R.M. Even though only 1 of 28 Cavit specimens showed leakage in our three-dimensional assessment, all Cavit samples were examined for staining of the dry cotton pellets subjacent to the Cavit. This was done to ensure that leakage through the body of the Cavit (versus marginal microleakage) would not be overlooked. No cotton pellets showed dye staining in any of the total of 28 teeth restoration with Cavit. Furthermore, Pelikan ink (a carbon black compound) was determined to be a more suitable indicator of microleakage than silver nitrate (used in the manufacturer’s experiment). The particle size of carbon black much more closely approximates the size of bacteria. Second, silver nitrate is not compatible with the clearing processused in this study. One rather dramatic difference in our methods led to a potentially very important, clinically directed observation. Other coronal leakage studies have used noncarious extracted teeth; however, it is the exception rather than the rule to seea patient with a coronally nonrestored or caries-free tooth undergoing endodontic therapy. The teeth used here were restored teeth, more closely simulating a clinical setting. Interestingly, much of the microleakage seen appeared to be around: (1) permanent restoration-tooth interfaces and (2) the T.E.R.M.-access interface. Leakage around the T.E.R.M.-access interface was also observed by Teplitsky and Meimaris.’ ’ These findings pose an additional potential dilemma to the endodontist. If a leaky composite or amalgam restoration is present, should not the entire restoration be removed and the missing tooth structure temporized? Possibly, this could prevent potentially harmful bacterial ingress at the proximal areas. Recurrent microleakage at the permanent restoration-tooth interface may also be a cause of flare-ups and/or failures similar to coronal microleakage through inadequately sealed accesspreparations. This study did not specifically addressthese questions; nonethelessthey are of substantial interest and warrant further investigation. CONCLUSIONS
Phase I and II results indicate significant differencesbetweencoronal microleakage observedin teeth restored with Cavit versus those restored with T.E.R.M. The clinical significance of the results obtained from both phases of this investigation cannot be directly extrapolated from our in vitro data. To do so would constitute the most basic fallacy in experimental interpretation.
Volume 70 Number 2
Light-cured resin versus self-polymerizing temporary restoration
However, under the conditions of both phasesI and II, the results indicate that Cavit does provide an effective temporary seal for endodontic accessopenings, whereas T.E.R.M. does not as consistently preclude dye ingress and would not be as predictably successful as Cavit. Dye ingress seemed to be more prominent in the region of proximal boxes than from coronal seals. REFERENCES 1. Fraser JL. A study of the efficiency of dental fillings. J Dent
Res 1929;9:507-17. 2. Grossman LI. A study of temporary fillings as hermetic sealing agents. J Dent Res 1939;18:67-71. 3. Swanson K, Madison S. An evaluation of corona1microleakage in endodontically treated teeth. Part I. Time periods. J Endod 1987;13:56-9. 4. Parris L, Kapsymalis P. Effect of temperature change on the sealing properties of temporary filling materials. Part 1. ORAL SURG ORAL MED ORAL PATHOL196&13:982-g. 5. Parris L, Kapsimalis P, Code JH, Evans R. The effect of temperature change on the sealing properties of temporary filling materials. Part II. ORAL SURG ORAL MED ORAL PATHOL 1964:17:771-g.
BOUND VOLUMES AVAILABLE
225
6. Widerman FH, Eames WB, Serene TB. The physical and biologic properties of Cavit. J Am Dent Assoc 1971;82:378-82. 7. Krakow AA, de Stoppelaar JD, Grg’n P. In vivo study of temporary filling materials used in endodontics in anterior teeth. ORAL SURGORAL MED ORAL PATHOL1977;43:615-20. 8. Oppenheimer S, Rosenberg PA. Effect of temperature change on the sealing properties of Cavit and Cavit-G. ORAL SURG ORAL MED ORAL PATHOL1979;48:250-3. 9. Chohayeb AA, Bassiouny MA. Sealing ability of intermediate restoratives used in endodontics. J Endod 1985;11:241-4. 10. Bennett RJ (Senior Research Chemist, Caulk/Dentsply, Milford, Delaware). Physical properties and microleakage evaluation of a new temporary endodontic filling material (T.E.R.M.).-AG IADR 1987. 11. Teplitsky PE, Meimaris IT. Sealing ability of Cavit and T.E.R.M. as intermediate restorative materials. J Endod 1988;14:278-82. 12. Webber RT, de Rio CE, Brady JM, Segall RO. Sealing quality of a temporary filling material. ORAL SURG ORAL MED ORAL PATHOL 1978;16:123-9.
Reprint requests to: Keith V. Krell, DDS, MS Associate Professor, Department of Endodontics College of Dentistry, University of Iowa Iowa City, IA 52242
TO SUBSCRIBERS
Bound volumes of ORAL SURGERY,ORAL MEDICINEANDORALPATHOLOGYare available to subscribers (only) for the 1990 issuesfrom the Publisher, at a cost of $42.00 ($54.00 international) for Vol. 69 (January-June) and Vol. 70 (July-December). Shipping charges are included. Each bound volume contains a subject and author index and all advertising is removed. Copies are shipped within 60 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact MosbyYear Book, Inc., Circulation Department, 11830Westline Industrial Drive, St. Louis, MO 63146-3318, USA; phone (800) 325-4177, ext. 7351. Subscriptions must be in force to qualify. Bound volumesare not available in place of a regular journal subscription.
R
outine endodontic therapy cannot always be completed in one visit, and frequently temporization of the accessis needed. The material sealing the accessshould prevent bacterial ingress, yet allow easy removal at subsequent visits. Several studies have dealt with the sealing ability of temporary restorative materials. ‘, 2 These authors have concerned themselves with intra-appointment sealability of temporary restorations, to prevent bacterial ingress or medicinal leakage from the unobturated root canal system. Recently, Swanson and Madison3 found that after a 3-day period a significant amount of coronal microleakage occurred in obturated but nontemporized human teeth. They postulated that deficient coronal seal with resultant coronal microleakage may very well be an etiologic factor for endodontic failure. Thesestudies emphasizethe importance of preventing recontamination of debrided and obturated canals. Because of the results from past sealability studies,4-9Cavit (Premier Dental Co., Norristown, Pa.), a pre-mixed, single paste, tube-dispensed com-
pound, has probably become the most extensively used temporary restorative material. However, controversy related to the use of Cavit as a temporary filling in endodontics still exists. Recently, a new light-cured, compule-dispensed endodontic composite temporary restorative material (T.E.R.M. compules, Caulk/Dentsply, Milford, Delaware) was introduced. Promotional literature that cited and illustrated results from a silver nitrate microleakage experiment involving noncarious, unrestored teeth found T.E.R.M. to be far superior to Cavit.‘O However, the T.E.R.M. material requires a light cure system that may not be a part of most endodontists’ armamentarium. Teplitsky and Meimaris’ 1found that Cavit maintained an effective seal 91.7% of the time whereas T.E.R.M. maintained an effective seal 33.3% of the time. These discrepancies in findings suggestfurther research is warranted. Therefore, the purpose of this study was to compare the sealing properties of Cavit and T.E.R.M. under two different conditions (as described in the Materials and Methods section). MATERIALS
aFormer Graduate Students, Department of Endodontics. bAssociate Professor, Department of Endodontics. 7/15/12442
AND METHODS
The study was performed in two phases. In phase I, 34 extracted human anterior and premolar teeth 221
222
Melton, Cobb, and Krell
Table
1.Leakage (in mm) Group I (Cavit)
1. Fractured-discarded 2. Fractured-discarded 3.0 mm
ORAL SURGORAL MED ORAL PATHOL August 1990
Group III (etch/Cavit)
Group II (T.E.R.M.)
1.5 mm 2. Fractured-discarded
1.0 mm 2. Fx-discard
4.0 5.0 6.0 7.0 8.0
3.0 4.5 5.0 6.0 7.0 8.2
3.0 4.0 5.0 6.0 7.0 8.0
X = 0 (Cavit’s)
X = 4.4 (T.E.R.M.‘s)
Microleakage
measured in the teeth used in phase 1 by experimental
Group IV (etch/T.E.R.M.)
1.5 mm 2.0 3.0 4.0 5.0 6. Fx-discard 7.0 8.5
group
were collected. The teeth were stored in deionized water with thymol until ready for experimentation. One operator performed standard endodontic access preparations on all 34 teeth with a No. 557 high-speed water-cooled carbide bur. No attempt was made to debride the radicular pulp spaces,and the teeth were randomly placed into four groups of eight teeth each. Two teeth were left to serve as controls. Dry cotton pellets were placed on the chamber floor, and then standard accesspreparations were sealed with one of four techniques: (1) Cavit alone, (2) T.E.R.M. alone, (3) acid etching and Cavit, and (4) acid etching with T.E.R.M. Manufacturer’s directions were followed for placement of the materials, with the exception of the introduction of the 37% phosphoric acid etchant variable. (The manufacturer of T.E.R.M. does not specify the need for the etching procedure). Root surfaces and unrestored carious lesions were coated with sticky wax. The entire root and crown of the negative control was covered with sticky wax, whereasthe positive control had the root covered with wax, but no temporary restoration was placed. Teeth were stored 1 week at 37’ C in an artificial saliva solution (1 ml calcium chloride, 3 ml monosodium acid phosphate, 20 ml sodium bicarbonate). All specimens were then transferred to an Indian ink solution (Pelikan ink; Gunther Wagner) for 48 hours to demonstrate the presence of coronal microleakage. After dye exposure, the sticky wax was removed and the teeth decalcified in 5% nitric acid for 48 hours with constant stirring, followed by 4 hours of immersion in a running water bath. The teeth were dehydrated overnight in 80% ethyl alcohol followed by two hourly rinses of 90% ethyl alcohol and three hourly rinses of 100% ethyl alcohol. The teeth were cleared and rendered transparent by placing them in a methyl salicylate solution. After clearing, all teeth with stained coronal fracture lines wre removed from the study to eliminate the
previously undetected fractures as potential leakage sources. Of the 32 experimental teeth, 5 had to be eliminated because of fractures. A blinded assessmentof dye penetration in the remaining teeth was performed by two other operators, independent from the restoring dentist, each using a 7-power illuminated viewer (Mitutoyo Co., Japan). Three teeth failed to decalcify and clear completely, so these teeth were sectioned longitudinally to enable linear dye penetration assessment. Phase II was similar to phase I except for two major changes. Twenty-four teeth were selected and prepared as in phase I. Acid etching was not performed, so the two experimental groups consisted of 12 teeth restored with Cavit and 12 with T.E.R.M. After 1 week in the artificial saliva solution, all teeth were thermocycled between water baths maintained at 10” C + 2” C and 50” C f 2” C for 540 cycles, remaining in each bath for 60 seconds.The dye penetration and penetration assessmentsteps were then carried out as per phase I. Statistical analysis of the data from phaseI was not required. In phase II, an unpaired t test was used for comparison. RESULTS
The positive control demonstrated gross dye ingress, whereas the negative control showed no dye penetration. In phaseI, none of the teeth restored with Cavit (groups I and III) showedany leakage, whereas 9 of the 14 teeth restored with T.E.R.M. were leakage free. Becausethe differences were obvious, statistical analysis was deemedunnecessary.Data summarization may be seenin Table I. Of the teeth restored with T.E.R.M. with coronal leakage (n = 5), the mean dye penetration was 4.4 mm. Acid etching did not appear to be a factor in leakage reduction for either material. In phase II, only 1 of 12 teeth restored with Cavit exhibited detectable microleakage (Fig, 1, A and B),
Volume 70 Number 2
Light-cured
resin versus self-polymerizing
temporary restoration
223
Fig. 1. A, Mesial view of cleared premolar restored with Cavit. B, Distal view of cleared premolar restored with Cavit.
Fig. 2. A, Mesial view of cleared premolar restored with T.E.R.M. B, Distal view of cleared premolar restored with T.E.R.M.
whereas 6 of 12 teeth restored with T.E.R.M. displayed leakage (Fig. 2, A and B). A t = -2.057 was significant at p < 0.05. A summary of specific results may be seen in Table II.
Table
II. Leakage (in mm) Cavit 1.0 mm 2.0 3.0 4.0 5.0 6.0 7.2 8.0 9.0 10.0 11.0 12.0 ti = 0.16
DISCUSSION
Manufacturer’s directions were closely followed for placement of the temporary restorative materials. As per the recommendations of Webber and coworkers,‘* we attempted to ensure that all Cavit restorations were at least 3.5 mm in depth. An equal (or greater) thickness of T.E.R.M. was used, although the manufacturer does not claim that this is necessary. Two layers of T.E.R.M. were successively placed, with each placement followed by a 30-second application of visible light to ensure complete polymerization. Cavit’s compressivestrength has been shown to be less than that of zinc oxide+ugenol and zinc phosphate cement.6The T.E.R.M. versus Cavit investigation also claims superior Shore A50 hardness and tensile and compressive strengths with T.E.R.M.‘O Although this may be true, clinical experience has shown that an adequate bulk of Cavit, as used here, suitably withstands masticatory stress between appointments if used to seal a routine accesspreparation. (Most likely, neither Cavit nor T.E.R.M. would be recommended to replace large amounts of missing tooth structure when a badly broken down tooth is treated). As alluded to before, the one main departure from the manufacturer’s recommendations involved the use of acid etching of exposed enamel before placement of restoration in two of the four groups in phase I. (The manufacturer of T.E.R.M. does not state that etching is required). It was decided to include this variable out of curiosity, primarily be-
I
Microleakage
measured
T.E.R.M. 1.0 mm 2.1 3.1 4.2 5.4 6.2 7.2 8.0 9.0 10.0 11.0 12.0 x= 1.0
by the teeth
used in phase
II by experimental
group.
causeof the plethora of restorative dentistry literature showing that etching greatly increases bond strength and decreasesmarginal microleakage for composite restorations. However, acid etching was not found to have any modifying effect on leakage reduction in the two phaseI experimental groups in which etchant was employed. Therefore, it was not used in phase II. After the clearing process, all teeth with stained, previously undetectable fracture lines were removed from the study to eliminate the fracture as a leakage source. Five teeth were discarded from the experimental teeth in phase I (none in Phase II), somewhat diminishing the sample size. However, approximately equal numbers of teeth restored with Cavit and T.E.R.M. were discarded, and the decreasedsample size still rather dramatically portrayed the differences in leakage betweenthe two materials. Our results tend to confirm those of Teplitsky and Meimaris in their
224
Melton, Cobb, and Krell
Table
III. Cavit-T.E.R.M. leakage
ORAL SURG ORAL MED ORAL PATHOL August I990
Unpaired s test DF:
Xl: Trealment Unpaired t value.
YI: Leakage Prob. (I-tail):
22
-2.057
0.0259
Group
count
Mean
SD
SE
Cavit T.E.R.M.
12 12
0.167 1
0.577 1.279
0.167 0.369
recent work. 11Although their method departed somewhat from that used in this study, they showed that Cavit maintained an effective marginal seal 9 1.7%of the time versus only 33.3% for T.E.R.M. None of the teeth in either of the Cavit groups in phase I of this study were found to exhibit leakage, whereas 67% of the composite-filled teeth were free from leakage. Of the 33% of the composite-filled teeth that did demonstrate leakage (n = 4), an average penetration depth of 4.4 mm was recorded. As before, no specific statistical analysis was considered necessary. Phase II was included in the investigation, primarily to determine whether thermocycling might alter the results. Thermocycling probably more closely approximates the intraoral milieu. Moreover, the manufacturer’s study used thermocycling, and the investigators wanted to follow that microleakage protocol as closely as possible. As hypothesized, phase II results were indeed somewhat different from those of phase I. One of the 12 teeth restored with Cavit did exhibit microleakage, but 6 of the 12 teeth restored with T.E.R.M. leaked. Thus, a higher percentage of teeth restored with T.E.R.M. leaked in Phase II, but the mean depth of leakage was less than for the teeth in phase I. The means (0.167 mm for Cavit versus 1.O mm for T.E.R.M.) were, however, significantly different statistically. Our study also used an artificial saliva solution for sample storage. This was believed to again more closely resemblethe intraoral environment than would storage in distilled water, as has been done in previous investigations. In this study, the teeth were cleared, enabling a three-dimensional assessment of the carbon black coronal marginal microleakage. This was deemed preferable to the standard practice of longitudinally sectioning a sample and examining leakage in a random sagittal plane of the restorative material, as was the case in the manufacturer’s investigation. However, as mentioned before, the investigators were forced to longitudinally section three samplesbecause of incomplete decalcification and clearing. Since Cavit setsand expands by absorbing moisture,6 a lon-
gitudinal cross section of a Cavit specimen would be more likely to show dye ingress than would the cross section of a less hydrophilic material, such as T.E.R.M. Even though only 1 of 28 Cavit specimens showed leakage in our three-dimensional assessment, all Cavit samples were examined for staining of the dry cotton pellets subjacent to the Cavit. This was done to ensure that leakage through the body of the Cavit (versus marginal microleakage) would not be overlooked. No cotton pellets showed dye staining in any of the total of 28 teeth restoration with Cavit. Furthermore, Pelikan ink (a carbon black compound) was determined to be a more suitable indicator of microleakage than silver nitrate (used in the manufacturer’s experiment). The particle size of carbon black much more closely approximates the size of bacteria. Second, silver nitrate is not compatible with the clearing processused in this study. One rather dramatic difference in our methods led to a potentially very important, clinically directed observation. Other coronal leakage studies have used noncarious extracted teeth; however, it is the exception rather than the rule to seea patient with a coronally nonrestored or caries-free tooth undergoing endodontic therapy. The teeth used here were restored teeth, more closely simulating a clinical setting. Interestingly, much of the microleakage seen appeared to be around: (1) permanent restoration-tooth interfaces and (2) the T.E.R.M.-access interface. Leakage around the T.E.R.M.-access interface was also observed by Teplitsky and Meimaris.’ ’ These findings pose an additional potential dilemma to the endodontist. If a leaky composite or amalgam restoration is present, should not the entire restoration be removed and the missing tooth structure temporized? Possibly, this could prevent potentially harmful bacterial ingress at the proximal areas. Recurrent microleakage at the permanent restoration-tooth interface may also be a cause of flare-ups and/or failures similar to coronal microleakage through inadequately sealed accesspreparations. This study did not specifically addressthese questions; nonethelessthey are of substantial interest and warrant further investigation. CONCLUSIONS
Phase I and II results indicate significant differencesbetweencoronal microleakage observedin teeth restored with Cavit versus those restored with T.E.R.M. The clinical significance of the results obtained from both phases of this investigation cannot be directly extrapolated from our in vitro data. To do so would constitute the most basic fallacy in experimental interpretation.
Volume 70 Number 2
Light-cured resin versus self-polymerizing temporary restoration
However, under the conditions of both phasesI and II, the results indicate that Cavit does provide an effective temporary seal for endodontic accessopenings, whereas T.E.R.M. does not as consistently preclude dye ingress and would not be as predictably successful as Cavit. Dye ingress seemed to be more prominent in the region of proximal boxes than from coronal seals. REFERENCES 1. Fraser JL. A study of the efficiency of dental fillings. J Dent
Res 1929;9:507-17. 2. Grossman LI. A study of temporary fillings as hermetic sealing agents. J Dent Res 1939;18:67-71. 3. Swanson K, Madison S. An evaluation of corona1microleakage in endodontically treated teeth. Part I. Time periods. J Endod 1987;13:56-9. 4. Parris L, Kapsymalis P. Effect of temperature change on the sealing properties of temporary filling materials. Part 1. ORAL SURG ORAL MED ORAL PATHOL196&13:982-g. 5. Parris L, Kapsimalis P, Code JH, Evans R. The effect of temperature change on the sealing properties of temporary filling materials. Part II. ORAL SURG ORAL MED ORAL PATHOL 1964:17:771-g.
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6. Widerman FH, Eames WB, Serene TB. The physical and biologic properties of Cavit. J Am Dent Assoc 1971;82:378-82. 7. Krakow AA, de Stoppelaar JD, Grg’n P. In vivo study of temporary filling materials used in endodontics in anterior teeth. ORAL SURGORAL MED ORAL PATHOL1977;43:615-20. 8. Oppenheimer S, Rosenberg PA. Effect of temperature change on the sealing properties of Cavit and Cavit-G. ORAL SURG ORAL MED ORAL PATHOL1979;48:250-3. 9. Chohayeb AA, Bassiouny MA. Sealing ability of intermediate restoratives used in endodontics. J Endod 1985;11:241-4. 10. Bennett RJ (Senior Research Chemist, Caulk/Dentsply, Milford, Delaware). Physical properties and microleakage evaluation of a new temporary endodontic filling material (T.E.R.M.).-AG IADR 1987. 11. Teplitsky PE, Meimaris IT. Sealing ability of Cavit and T.E.R.M. as intermediate restorative materials. J Endod 1988;14:278-82. 12. Webber RT, de Rio CE, Brady JM, Segall RO. Sealing quality of a temporary filling material. ORAL SURG ORAL MED ORAL PATHOL 1978;16:123-9.
Reprint requests to: Keith V. Krell, DDS, MS Associate Professor, Department of Endodontics College of Dentistry, University of Iowa Iowa City, IA 52242
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