endodontics Editor: MILTON SISKIN, D.D.S.
College of Dentistry The University of Tennessee 847 Monroe Avenue Memphis, Tennessee 38163
The apical seal via the retrosurgical approach II. An evaluation
Abdul K. Abdal, B.Ch.D., H.D.D., M.S.D.,* D. Hugo Retief, M.Sc., B.D.S., Ph.D. Dent., ** and Homer C. Jamison, D.D.S., D.P.H., ** Mosul, Iraq, and Birmingham, Ala. UNIVERSITY
In this investigation heat-sealed gutta-percha (A) reinforced with Adaptic (B), ASPA (C), Cupralloy without (D) and with (E) varnish, Spheraloy without (F) and with (G) varnish were used as retrofilling materials. Seventy maxillary central incisors with Class I canal anatomy were selected. Marginal leakage at the apical filling/root canal interface was evaluated quantitatively by means of a fluorescent dye technique. All statistical tests were computed at the 5 percent level of significance. Analysis of variance revealed that differences in microleakage among retrofillings were significant. Tukey’s test of multiple contrasts was used to isolate statistically significant differences between all pairs of means. The following results were obtained: EAGECB Retrofillings significantly
are ranked different
order of microleakage.
I n a preliminary study the apical seal produced by
17 retrofilling materials was evaluated qualitatively by scanning electron microscopy (SEM) and quantitatively by a fluorescent dye technique.’ The results of the study indicated that heat-sealed gutta-percha alone and when reinforced with a composite dental resin (Adaptic) or a glass ionomer cement (ASPA) provided the most effective apical seal. The purpose of this investigation was to evaluate the apical seal obtained by postresection filling with
Submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry (Dr. Abdal) *Lecturer and Clinician, Department of Surgery, University of Mosul College of Medicine. **Professor, Department of Biomaterials, and Professor, Director of Dental Computer Services, University of Alabama School of Dentistry. 0030.4220/82/080213
+ 06$00.60/[email protected]
1982 The C. V. Mosby Co.
Means that are linked were not
heat-sealed gutta-percha alone and when reinforced with Adaptic, ASPA, Cupralloy without and with cavity varnish, and Spheraloy without and with cavity varnish. Cupralloy was selected as representative of the high-copper amalgams and Spheraloy of the conventional zinc-free amalgams. METHODS
Seventy teeth with Class I canal anatomy, as confirmed by labiopalatal and mesiodistal radiographs, were chosen for this definitive study. The teeth were randomly numbered from 1 to 70. All the teeth were stored in 70 percent ethanol at 37” C. in separate containers. A postresection filling technique with heat-sealed gutta-percha was carried out on all the teeth. The 70 teeth were divided into 10 groups of seventeeth each. The experimental design was determined statistically. A pseudorandom distribution 213
Abdal, Retief, and Jamison
Oral Surg. August, 1982
Fig. 1. Three reference points used to determine the depth of dye penetration. A, The specimen. The postresection filling technique reinforced with a retrograde filling material. The retrograde cavity depth = 3.0 mm. approximately. A’, Projection on the screen. The postresection filling technique reinforced with a retrograde filling material. EDPS, Extent of dye penetration on the screen; RCDS, retrograde cavity depth on the screen. B, Control specimen. The postresection filling technique with heatsealed gutta-percha only. B’, Control projection on the screen.The postresectionfilling technique with heat-sealed gutta-percha only. EDPS, Extent of dye penetration on the screen; RCDS, average depth of 60 retrograde cavity preparations.
table was computer processedto determine the order in which the treatment procedures were to be carried out. Each group of seven teeth contained a control tooth which was filled with heat-sealed gutta-percha via the postresection filling technique (procedure A). The remaining six teeth in each group were reinforced with a retrofilling material after the retrograde cavities were prepared as previously described. The following retrofilling materials were used: Adaptic radiopaque dental restorative (procedure B), Caulk ASPA (procedure C), Cupralloy amalgam (procedure D), Cupralloy amalgam with Copalite varnish* (procedure E), Spheraloy zinc-free amal*Copalite Texas.
Varnish, Cooly & Cooly, Ltd., Houston,
gam (procedure F), and Spheraloy zinc-free amalgam with Copalite varnish (procedure G). The Copalite varnish was applied to the walls and floors of the retrograde cavities by means of cotton wool pellets. The amalgams were inserted after the varnish had dried. The retrofilling materials were mixed and inserted in their respective retrograde cavities as previously described.’ Mesiodistal and labiopalatal postoperative radiographs were taken of each tooth to check the obliteration of the root canals. The integrity of the apical seal was evaluated quantitatively by a fluorescent dye technique. The mounted specimens were viewed in a Leitz Wetzlar Dialux 20 microscope with fluorescent attachment* and photomicrographs were taken with a Nikon M 35 camera? with Kodak Ektachrome 200 film for color slides ED 13536.$ The eyepiece magnification was 10X and the objective magnification was 1.6~. The extent of dye penetration was evaluated in each specimen. The sections were examined in numerical order with the investigator unaware of the retrofilling material or treatment procedure used for each tooth. The extent of dye penetration was determined as follows. The data were collected by projecting each photomicrograph slide on a screen. The projector was set at a fixed distance from the screen. The projector was switched on and the field of projection outlined on the screen. For each slide examined, a graph sheet tracing paper was fixed on the screen within the boundaries of the abovementioned field. Three reference points were marked on the graph sheet tracing paper. The first point was marked on the resected root apex, the second point indicated the depth of dye penetration along the retrograde filling material/root canal interface, and the third point indicated the depth of the retrograde cavity preparation (Fig. 1). For a control group, the third point was obtained from the average depth of the cavities in the 60 teeth with retrofillings. The distances between the points were measured by means of a metric ruler. The distance between the first and second points represents the amount of dye penetration and the distance between the first and third points represents the depth of the retrograde cavity preparation. The average depth of the retrograde cavity preparation in all the teeth was 3.0. The following equation was used to determine the depth of dye penetration in millimeters EDPS x 3.0 Depth of dye penetration = RCDS *Ernest Leitz, GmbH D, 6330 Wetzlar, West Germany. tNippon Kogaku, Tokyo, Japan. *Eastman Kodak Company, Rochester, N. Y.
Apical seal via retrosurgical
Volume 54 Number 2
I. Means and standard deviations of the microleakage obtained with the different treatment procedures
Microleakage Treatment procedure Gutta-percha Gutta-percha Gutta-percha Gutta-percha Gutta-percha Gutta-percha Gutta-percha
(A) + Adaptic (B) + ASPA (C) + Cupralloy (D) + Cupralloy + varnish (E) + Spheraloy (F) + Spheraloy + varnish (G)
10 10 IO 10 10 10 10
1.83 0.03 0.06 3.00 0.35 3.00 0.38
(mm) Standard deviation 1.14 0.04 0.09 0.00 0.43 0.00 0.93
Results of analysis of variance*
Source Treatment procedure Residual Total
Sum of squares
Degrees of freedom
Critical value of the variance ratio at the 5% level of signiJcance
109.47 21.10 130.57
6 63 69
18.25 0.34 1.89
*Pooled standard deviation = 0.58; pooled standard error = 0.18; mean of all observations = 1.23
EDPS = extent of dye penetration on the screen, RCDS = retrograde cavity depth on the screen, and 3.0 = average retrograde cavity depth in millimeters. The results were matched with their corresponding random numbers and treatment procedures. All statistical tests were computed at the 5 percent level of significance. An analysis of variance was used to determine whether there were significant differences in microleakage among the treatment procedures. Tukey’s test of multiple contrasts was used to isolate statistically significant differences among all pairs of means. RESULTS
The means and standard deviations of the microleakage obtained with the different treatment procedures are given in Table I and represented graphically in Fig. 2. The results obtained with the analysis of variance are given in Table II. The variance ratio was 54.47. The critical value of the variance ratio at the 5 percent level of significance was 2.25. Thus the analysis of variance revealed that there were significant differences in microleakage among the various treatment procedures. Tukey’s test of multiple contrasts was used to isolate statistically significant differences among all pairs of means. The results are given in Table III. The value for multiple contrasts at the 5 percent level of significance was 4.31. The critical value for multiple contrasts was obtained by multiplying the
Ill. Mean depth and lower limit of microleakage of each treatment procedure ranked in descending order of magnitude (Tukey’s test)* Table
Treatment procedure Gutta-percha + Cupralloy CD) Gutta-percha + Spheraloy (F) Gutta-percha (A) Gutta-percha + Spheraloy + varnish (G) Gutta-percha + Cupralloy + varnish (E) Gutta-percha + ASPA (C) Gutta-percha + Adaptic (B)
Mean depth (mm.1 t
Lower limit (mm.)
*Tabled value for multiple contrasts = 4.31; critical value for multiple contrasts = 0.79. tMeans linked with vertical lines are not significantly different.
value for multiple contrasts, 4.31, by the pooled standard error, 0.18 (Table II). A value of 0.79 for the critical value for multiple contrasts was obtained (Table III). The mean depth and the lower limit of microleakage of each treatment procedure are given in Table III. The lower limit was obtained by subtracting the critical value for multiple contrasts from the mean. The mean microleakage values obtained with various treatment procedures were ranked in descending order of magnitude. Means
Abdal, Retief, and Jamison
Oral Surg. August, 1982
Meansand standarddeviationsof the microleakage.
linked with vertical lines were not significantly different. DISCUSSION
The results of this in vitro study under the defined experimental conditions indicated that the most severe microleakage was obtained with heat-sealed gutta-percha reinforced with Cupralloy and Spheraloy retrofillings without cavity varnish. When conventional amalgams are used in clinical restorative dentistry, marginal leakage at the amalgam/tooth interface is considerably reduced with time. This is due to accumulation of corrosion products derived from the y-2 phase.2It takes approximately 6 months for this process to develop fully. In the interim period, protection against marginal leakage is obtained by the use of cavity varnish prior to the placement of the amalgam restoration. Microleakage of high-copper amalgams is also reduced with time.3 The severe microleakage obtained with Cupralloy and Spheraloy retrofillings may be due in part to the fact that microleakage was evaluated 2 weeks after
placement of the retrofillings. This short observation period placed the amalgam restorations at a distinct disadvantage as they had not yet had the time to develop their optimal sealing effect. In clinical restorative dentistry freshly placed amalgam restorations develop micro1eakage.4-7 Similar results occurred in the present study when amalgams were used as retrofilling materials (Table III). Microleakage at the amalgam restoration/tooth interface is considerably reduced by the application of cavity varnish to the walls and floors of the preparations prior to the insertion of the amalgam restorations.*-lo In the present study microleakage was significantly reduced by the application of Copalite cavity varnish to the walls of the retrograde preparations prior to the placement of the Spheraloy and Cupralloy amalgams (Table III). The cavity varnish was applied twice as this procedure significantly reduces marginal leakage.” Since the postresection filling technique with heatsealed gutta-percha is commonly used in clinical endodontic practice, this procedure was utilized as
Volume 54 Number 2
the control treatment procedure in the present study. In this investigation this procedure resulted in severe microleakage at the heat-sealed gutta-percha/ resected root canal interface. The microleakage was significantly reduced when this technique was reinforced with amalgam restorations with cavity varnish, ASPA, and Adaptic (Table III). The concept of acid etching enamel surfaces, as initially suggestedby Buonocore,‘2 is now an accepted clinical procedure to produce mechanical interlocking of composite resins into etched enamel surfaces.13Pretreatment of cut dentinal walls with phosphoric acid removes the superficial smear layer of dentin and widens the cut ends of the dentinal tubules.14,I5The widening of the tubules results from the solution of the largely inorganic peritubular dentin and the drying and shrinkage of the exposed collagen matrix of the intertubular dentin.16Application of composite resins to these surfaces leads to the extension of the resin into the dentinal tubules, resulting in mechanical interlocking of the resin into the conditioned dentin surfaces.” In the present study this procedure significantly improved the apical seal. In vital teeth phosphoric acid etching to freshly cut dentin may have an adverse effect on the pulp’*; this obviously does not apply to teeth undergoing endodontic treatment. The minimal microleakage obtained with ASPA as a retrofilling material can be explained by the fact that this cement adheres to dentin as a result of physicochemical interaction with the substrate.19 Conditioning of tooth surfaces with 50 percent citric acid prior to the placement of the glass ionomer cement improves the wettability of the dentin surface and results in intimate interfacial contact between the cement and dentin.19 The objective of this in vitro study was to evaluate microleakage at the retrograde filling/dentin interface and to determine which of the materials under study would seal this interface optimally. Sealing is not the only factor, however, which should be considered prior to the recommendation of a restorative material for retrosurgical endodontic use. The retrofilling materials are in direct contact with vital periapical tissues and the host response to these implanted restorative materials should also be evaluated. In a recent study the biologic response to a conventional and a high-copper amalgam was assessed.*OIt was reported from cell culture and implant studies that the conventional amalgam was almost nonirritating and the high-copper amalgam only slightly irritating. An in vitro cell culture technique was used for screening dental restorative materials
Apical seal via retrosurgical
with regard to adversebiologic effects.2’A composite restorative material exhibited a minimal cytotoxic effect under these conditions. Kawahara and his co-workers22compared the biologic properties of a glass ionomer cement with other conventional cements and concluded that the glass ionomer cement may be applied as a pulp capping and root canal filling material. Although it would appear that the restorative materials under study are nonirritating or only slightly irritating under the defined experimental conditions, it is suggestedthat the biologic compatibility of these materials should be evaluated by means of usage tests before their clinical application as retrofilling materials in retrosurgical endodontics. CONCLUSIONS
Cavity varnish should be used in conjunction with retrofilling conventional or high-copper amalgams. The minimal microleakage obtained with Adaptic and with ASPA suggests that these restorative materials should be considered as retrofilling materials. The biocompatibility of these materials should be evaluated by means of usage tests before their clinical application as retrofilling materials is retrosurgical endodontic practice. The authors manuscript.
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2. Smith, G. A., Wilson, N. H. F., and Combe, E. C.: Microleakage of Conventional and Ternary Amalgam Restorations in vitro, Br. Dent. J. 144: 69-73, 1978. 3. Boyer, D. B., and Torney, D. L.: Microleakage of High Copper Amalgams, J. Dent. Res. 58A: 394(abst. No. 1213), 1979. 4. Going, R. E., Massler, M., and Dute, H. L.: Marginal Penetrations of Dental Restorations by Different Radioactive Isotopes, J. Dent. Res. 39: 273-284, 1960. 5. Going, R. E., Massler, M., and Dute, H. L.: Marginal Penetration of Dental Restorations as Studied by Crystal Violet Dye and I’j’, J. Am. Dent. Assoc. 61: 285-300, 1960. 6. Phillips, R. W., Gilmore, H. W., Swartz, M. L., and Schenker, S. I.: Adaptation of Restorations in vivo as Assessed by Caa5, J. Am. Dent. Assoc. 62: 9-20, 1961. 1. Wing, G., and Lyell, J. S.: The Marginal Seal of Amalgam Restorations, Aust. Dent. J. 11: 81-86, 1966. 8. Andrews, J. T., and Hembree, J. H.: In vitro Evaluation of Marginal Leakage of Corrosion-Resistant Amalgam Alloy, J. Dent. Child. 42: 367-370, 1975. 9. Forsten, L.: Sealing Effect of Cavity Varnishes, Proc. Finn. Dent. Sot. 73: 152-153, 1977. 10. Lund, N. H., Matthews, J. L., and Miller, A. W.: Cavity Varnish and Its Application: “Once Is Not Enough,” J. Prosthet. Dent. 40: 534-537, 1978. Il. McKerracher, P. W.: What Is Happening to Cavity Toilet and Lining? Aust. Dent. J. 23: 247-251, 1978.
Abdal, Retief, and Jamison
12. Buonocore, M. G.: A Simple Method of Increasing the Adhesion of Acrylic Filling Materials to Enamel Surfaces, J. Dent. Res. 34: 849-853, 1955. 13. Retief, D. H.: The Mechanical Bond, lnt. Dent. J. 28: 18-27. 1978. 14. Hoppenbrouwers, P. M. M., Driessens, F. C. M., and Standhouders, A. M.: Morphology, Composition and Wetting of Dentinal Cavity Walls, J. Dent. Res. 53: 1255-1262, 1974. 15. Barnes, I. E.: The Adaptation of Composite Resins to Dentine, Br. Dent. J. 142: 253-259, 1977. 16. Brannstrom, M., and Johnson, G.: Effects of Various Conditioners and Cleaning Agents on Prepared Dentin Surfaces: A Scanning Electron Microscopic Investigation. J. Prosthet. Dent. 31: 422-430, 1974. 17. Nordenvall, K. J.: Enamel Bond-Composite Filling in Etched Cavities. The Appearance of Resin Surfaces Facing Enamel and Dentin. Svensk Tandlak. Tidskr. 2: 141-150, 1978. 18. Retief, D. H., Austin, J. C., and Fatti, L. P.: Pulpal Response to Phosphoric Acid, J. Oral Pathol. 3: 114-122, 1974. 19. McLean, J. W.. and Wilson, A. D.: The Clinical Development
Oral Surg. August, 1982 of the Glass-Ionomer Cements. I. Formulations and Properties. II. Some Clinical Applications. III. The Erosion Lesion, Aust. Dent. J. 22: 31-36: 120-127: 190-195. 1977. 20. Mjiir, 1. V.: Biologic Assessment of Restorative Dental Materials: Interrelationship of Biologic and Technologic Properties, Oper. Dent. 3: 9-l 3, 1978. 21. Pettersen, A. H.. and Helgeland, K.: Evaluation of Biologic Effects of Dental Materials Using Four Different Cell Culture Techniques, Stand. J. Dent, Res. 85: 291-296, 1977. 22. Kawahara, H.. Imanishi, Y., and Oshima. H.: Biological Evaluation on Glass lonomer Cement, J. Dent. Res. 58: 1080-1086, 1979. Reprint requests to. Dr. D. H. Retief Institute of Dental Research University of Alabama School of Dentistry University Station Birmingham, Ala. 35294