0099-2399/90/1601-0019/$02.00/0 JOURNAL OF ENOOOONTICS Copyrigl~t 9 1990 by The American Assooatlon of Endodontists
Printed in U.S.A. VOL. 16, NO. 1,d~u~upu~Y1990
An In Vitro Comparison of the Sealing Ability of Materials Placed in Lateral Root Perforations Steve Dazey, DMD, and E. Steve Senia, DDS, MS, BS, FACD
contribute to failure (2, 7-9). Although the desirability of a seal is emphasized, little has been done to measure how well materials used to repair perforations achieve this objective. The purpose of this study was to compare the sealing ability of Tylin amalgam (Kerr Manufacturing Co., Romulus, MI), Ketac-Silver (Espe-Premier Sales Corp., Non-istown, PA), and Prisma VLC Dycal (L. D. Caulk, Co., Milford. DE) used to repair lateral root perforations in vitro.
The in vitro sealing ability of Tytin amalgam, KetacSilver, and Prisma VLC Dycal was compared. Roots of extracted teeth were perforated laterally. After the defects were repaired, the teeth were immersed in dye for 10 days and then sectioned, and the linear extent of dye penetration was measured. Statistical analysis showed that the Prisma VLC Dycal group exhibited significantly less dye penetration than the other two groups (p < 0.01). No difference was found between the Tytin and Ketac-Silver groups.
M A T E R I A L S AND M E T H O D S Eighteen extracted human maxillary canines were placed into 5.25% sodium hypochlorite at room temperature for 30 min to clean the root surfaces and remove the remaining periodontal ligament. Each tooth was secttoned longitudinally (Fig. IA) into a facial and palatal half using an Isomet saw (Buehler Ltd., Lake Bluff, 1L). Fifteen facia/ halves were placed inlo experimental group 1 and 15 palatal halves were designated group 2. Five halves were used as controls. In order to simulate a periodontal ligament, each tooth half was depressed into a patty of vinyl polysiloxane ~mpression material (Espe-Premier), cemental surface down, to the level of the cut surface. The resulting mold also served as a holder. Two perforations approximately 5-mm apart were made into each tooth half with a #2 round bur. The bur entered at the pulpal surface and exited at the root surface. The perforations were angled apically to approximate what might occur clinically if a bur was misdirected during access preparation (Fig. 2). The first perforation exited at the cervial third of the root and the second was placed apically and parallel to the first (Fig. 1B). Ten of the 30 perforations in group 1 and 10 of the perforations in group 2 were repaired with Prisma VLC Dycal. The same was done with Ketac-Silver and with Tytin so that each material was used in 20 perforations. To simulate clinical conditions, a piece of filter paper moistened with physiological saline was placed between the mold and the tooth so that the repair materials would be in contact with a moist environment. The repair materials were introduced into the perforations from the pulpal surface and placed against the filter paper-impression material matrix (simulated periodonr, d ligament) on the root surface. Prior to placement of the repair materials, the dentin surfaces of all specimens were rinsed wilh a water spray and dried with compressed air but were not chemically prepared. The amalgam was placed into the perforation in small increments and gently condensed into place, trying to avoid
Successful end~xlontics depends, in pat~t, on accurate diagnosis and appropriate treatment planning. Because the prognosis for a tooth worsens when a perforation occurs, this potential procedural accident and its prevention should be identified as pa~ of the treatment planning process. As more teeth arc retained throughout the life of adult dental patients, there is an increased demand fbr endodontic treatment of teeth that previously might have been extracted. These salvaged teeth arc often extensively restored and calcified and present a formidable challenge when searching for canals or preparing an adequate post space. Investigators have based the prognosis of an endodontic perforation on its location, the promptness of identification and treatment of the defect, the extent of the defect and the amount of periodontal ligament irritation, the biocompatibility of the material used for repair, and the ability of the repair material to provide a seal (1-8). Of these, location is often the main determinant of success or failure. Several researchers have indicated that a perforation in the apical or middle third of the root has a better prognosis than one in the cervical third ( 1,3, 9). As the perforation and its repair encroach upon the crest of the alveolar bone and the attachment apparatus, the chances for success diminish. When a perforative defect communicates with the oral environment through the gingival sulcus, the prognosis is poor (1, 4, 6, 9). Perforation into a furcation frequently leads to failure (1.3, 4, 8, 9). Several materials have been evaluated in vivo to treat molar perforation nonsurgically. Amalgam has been shown to be successful as have calcium hydroxide and Cavil (1, 2, 5, I 0 15). It appears that long-term success of a perforation repair is reliant on a material with low solubility (2, 13, 16). Several authors indicate tha! the lack of an adequate seal can also 19
20
Dazey and Senia
Joumal of Endodontics
/ A
B
C
%/
D
FIG 1. Sample preparation. A, Tooth was longitudinally sectioned into a palatal and facial half. B, Root perforations were angled apically to simulate a procedural accident. C, After the perforations were repaired and immersed in dye, longitudinal slices were cut parallel to the long axis of the tooth and through the perforations. D, Sections were photographed and linear dye penetration measured.
with sticky wax except for 1 to 2 mm around the repair material on the root surface. All of these specimens had varying amounts of repair material extruded onto the root surface. In group 2 this excess repair material was removed from the root surfaces with the aid of a #15 blade and a dissecting microscope. Then the repair materials were recessed approximately 0.5 m m with a high speed # 170L bur to ensure that they were not in contact with the external root surface. All surfaces of the teeth in this group were also coated with sticky wax except for the recessed perforations. Two root halves, not perforated, were entirely coated with sticky wax to serve as negative controls to verify that the wax provided an adequate barrier against dye penetration. To show that dye flowed into all exposed dentinal tubules, two positive control halves were perforated but not repaired and coated with sticky wax except for the openings on the external root surface. Another root half was used to evaluate the possibility of intertubular leakage (Fig. 3). All specimens were submerged in 2% methylene blue dye for 10 days at room temperature. After rinsing the specimens thoroughly, an Isomet saw with a 0.3-mm blade thickness was used to make thin multiple cuts parallel to the long axis of the tooth and through the perforations (Fig. 1C). After the resulting sections were photographed and projected onto a screen, linear dye penetration was measured independently by two observers from where the repair material made outermost contact with dentin/ cementum to the m a x i m u m depth of penetration along the perforation. The accuracy of the measurements taken from the projected photographs of five specimens from group 1 and five from group 2 was verified by measuring the linear dye penetration directly with a dissecting microscope equipped with an ocular micrometer (Carl Zeiss, Inc., Oberkochen, West Germany). RESULTS In both groups, all of the Tytin and Ketac-Silver repairs demonstrated dye penetration along the entire length of the
Fio 2. Representation of a root perforation caused by a misdirected bur.
excessive extrusion. Using the manufacturer's precapsulated delivery system, the Ketac-Silver was flowed into the perforation and gently patted to place with an endodontic condenser. The Prisma VLC Dycal was placed with a lightprotected l-ml syringe with a 23-gauge endodontic irrigation needle. It was placed incrementally as suggested by the manufacturer and each layer was cured for 60 sec with a handheld curing light (focus activator light; Teledyne Getz, Elk Grove Village, IL). The perforations were repaired and the specimens left untouched in the moist environment at room temperature for 24 h. All surfaces of the teeth in group 1 were then coated
FiG 3. Longitudinally sectioned control tooth showing no intertubular dye penetration. Sample is a facial root half with apical third removed. Preparation into dentin was made by directing a #56 high-speed bur coronally into apical surface. Resulting cavity preparation was surrounded by dentin and did not contact pulp space or external root surface. Dye entered bur hole (b) then penetrated into exposed dentinal tubules (arrows) and pulp space (ps) subjacent to exposed tubules. Once dye entered the pulp space, it seeped along the canal wall but did not enter unexposed dentinal tubules, rs, root surface
Vol. 16, No. 1, January 1990
Lateral Root Per/orations
21
FIG 4. A to D, Experimental samples (original magnification x l for A and B; x l 0 for C and D). The two sections in A are adjacent sections as are those in B. The sections with greatest dye penetration were measured. C, Arrows indicate direction of dye penetration. D, Dye penetration (arrows) into the dentinal tubules exposed by the perforation repaired with amalgam but not those repaired with Prisma VLC Dycal. AM, amalgam; KS, Ketac-Silver; VLC, Prisma VLC Dycal; rs, root surface; ps. pulpal surface. The background grid is 1.0 mm per interval.
perforations. Hence, the sealing ability of these two materials was very poor. The Prisma VLC Dycal repairs did not show this maximal penetration in any of the specimens (Fig. 4D). There was significantly less leakage in the Prisma VLC Dycal repairs than in the Tytin and Ketac-Silver repairs (sign test, p < 0.01). Since all of the Tytin and Ketac-Silver repairs in groups 1 and 2 leaked the full length of the repair (mean, 2.9 mm), no statistical difference was discernible between the two groups. The Prisma VLC Dycal repairs in group 1 were compared with those in group 2 using Student's t test. The recessed repair group (group 2) had greater dye penetration (p < 0.05). In group 1, only 20% (2 of 10) showed leakage (mean, 0.16 mm), while 90% (9 of 10) in group 2 had leakage (mean, 1.06 mm). The repairs made in the coronally placed perforations were compared with the more apically located repairs. The difference in leakage between the apical and coronal repairs made with Prisma VLC Dycal was not significant (Student's t test, p > 0.01). Both positive controls showed maximal dye penetration into the perforations while the negative controls showed none. DISCUSSION In all specimens where dye penetration occurred, the dye not only penetrated along the dentin-repair material interface, but also through the entire length of the dentinal tubules that communicated with the perforation. Fox et al. (17) and others describe frequent branching and anastomosing of the odontoblasl processes within the radicular dentinal tubules. The possibility exists that the dye may not only penetrate along the repair material interface, but also may penetrate by means of intertubular leakage via these anastomoses. If this occurs,
an accurate evaluation of dye penetration may not be possible. Although it was not the purpose of this investigation to evaluate the possibility of intertubular leakage, observation of the experimental specimens and a .separate control tooth (Fig. 3) indicated that no significant penetration of this type occurred under the conditions of this study. However, when the dye entered into a tubule, it penetrated the entire length o f the tubule. This resulted in a greater amount of leakage into the tubules than along the interface. It also allowed the dye to travel to areas far removed from the perforation site. The experimental design was intended to allow standardization of the perforations in a controlled environment so a valid comparison could be made. The maxillary canine was selected because of the long root and relatively constant root thickness. The canine root was not long enough to allow three side by side perforations but there was enough length for two. To standardize the angle of the perforations, the teeth were split in half and both halves were used. This procedure does not simulate clinical access to a perforation and it is not meant to imply that midroot perforations arc amenable to such a repair. It does, however, provide standardized perforations which can be used to compare leakage. Statistical analysis indicated the midroot perforations did not leak differently than the cervical ones. During a pilot study, concerns were raised as to what effect extruding a repair material onto the root surface would have on its sealing ability. For this reason, a second experimental group, group 2, was included. Group 1 represented perforation repairs where the material was allowed to extrude, as it would clinically, resulting in excess material on the surface o f the tooth. In group 2. this excess was removed and the repair material recessed slightly below the external root surface. Dye penetration in this group was expected to occur into the dentinal tubules exposed when the repair was recessed. Indeed
22
Dazey and Senia
F,a 5. Spe~men from group 2. DentinaJ tubules dose to the root surface were exposed when the excess repair matenal was removed. Arrows point out dye penetration along the length of these tubules. VLC, Prisma VLC Dycal; AM, amalgam; ps, pulpal surface; rs, root surface.
this was observed with the Prisma VLC Dycal specimens where the leakage occurred only along the length of these few exposed tubules (Fig. 5). In a sense, these exposed tubules provided an additional positive control. The excess material had no observable effect on the Tytin or Ketac-Silver repairs. Both of these materials leaked the full length ofthe perforation whether the excess material was present or removed. The same was not true for the Prisma VLC Dycal repairs. Only two specimens showed leakage in group 1. Although group 2 demonstrated a greater frequency of leakage than group 1, the linear depth of penetration was still significantly less with Prisma VLC Dycal than with Tytin or Ketac-Silver. C o m m o n postendodontic restorative techniques use metal posts cemented within the root canal space. Luting cements such as zinc phosphate, polycarboxylates, and glass ionomers are often used. Core build-up materials are also placed in the pulp chamber and canal orifices. These core materials include amalgam, composites, glass ionomers, intermediate or temporary filling materials, and various combinations. Dental amalgam may be condensed directly into the canal orifices as part of an amalgam core technique. Glass ionomer-amalgam combinations and composite resins are also used as core materials. With such a variety of materials available for use in build-up and post and core techniques, it would seem reasonable to select ones which would be compatible with an undetected perforation. It would also be desirable to use materials and techniques that can be used at the time the perforation occurs, that provide a good seal, do not absorb, are biocompatible, can be placed noninvasively, and do not cause additional physical damage to the periodontal tissue by extruding outside the root through the defect. The biocompatibility of amalgam has been demonstrated (13, 16, 18). It has performed well when used as a core buildup and retrofilling material. It is very durable and effective when adequately condensed. It can, however, cause a gingival tattoo when used subgingivally. For this and other esthetic reasons, its restorative and endodontic uses near gingival tissues are usually restricted to posterior teeth. When a perforation is repaired with amalgam from within the tooth, the potential exists for extruding excess material during conden-
Joumal of Endodontics
sation. Its physical presence in the periodontal ligament space can contribute to chronic inflammation (5, 6, 9, 10). In this regard, a flowable material could have an advantage over a condensable one. Amalgam used without a cavity varnish will almost certainly allow leakage. Investigators that have used amalgam as a perforation repair material (6, 9, 10, 13, 14) either have not included a cavity varnish in their technique or neglect to mention its use. The experimental design selected for this investigation did not utilize a cavity varnish to point out this leakage potential. Glass ionomer cements can be flowed and gently patted into place. When formulated into an amalgam-containing preparation such as Ketac-Silver, the glass ionomers have become a very popular and efficient core build-up material. Calcium hydroxide preparations are used extensively in dentistry. A recently introduced product, Prisma VLC Dycal, combines calcium hydroxide into a visible light-curing preparation. It has been shown to have nearly a 3-fold increase in compressive strength and at least a 3-fold decrease in water solubility when compared with other hardening calcium hydroxide preparations (19). When used for direct pulp capping, this material does not produce a layer of mummification or necrosis. Prisma VLC Dycal has passed all of the recommended initial and secondary tests for biocompatibility. It can be flowed into place and adequately cured with the 4m m light wands designed for use in posterior teeth. The setting and working times are not sensitive to humidity or moisture. It is also capable of bonding with composite resins. Although Prisma VLC Dycal has been shown to be effective when used in pulp capping procedures, its in vivo potential for perforation repair has not been evaluated. Amalgam, glass ionomer, and calcium hydroxide materials are currently used in various restorative and endodontic procedures. They each possess a therapeutic potential for treating known and undetected root perforations. The outcome of a perforation repair depends on a combination of conditions and circumstances which determine the chances for a biologically acceptable result. The sealing ability of the repair material is one of these. In vitro data on the sealing abilities of repair materials would appear to be a logical precursor to an in vivo investigation of long-term success. This study was supported by research funding from the United States Air Force. The opimons and assertions are those of the authors and are not to he construed as official or as reflectin(j the views of the United States Air Force or the Department of Defense. The authors w=sh to thank Dr. Carlos E. del Rio for his support and suggestions. We also wish to thank Or. George M Barnwell for his guidance in prepanng the statistical analysis. Dr. Dazey is a former resident. Department of Endodontics. Wifford Hall USAF Med~,al Center. Lackland Air Force Base, TX. Dr. Senia is associate professor and director, graduate endodontics, The University of Texas Health Science Center, San Antonio. TX.
References 1. Seltzer S, Sinai IH, August D. Periodontal effects of root perforations before and during endodontlc I~OCedures. J Dent Res 1970;49:332-9. 2. Jew RCK. Weine FS, Keene J J, Smulson MH. A histologic evaluation of
Vol. 16, No. 1, January 1990 penodontal tissues adjacent to root perforations filled with Cavil Oral Surg 1982:54:124-35. 3. Frank A L Resorption, perforation, and fTactures. Dent Clin North Am 1974;18:465-87. 4. Frank AL, Simon JHS, Abou-Rass M, Ghck DH. Chnlcal and surgical endodontics. Philadelphia JB Lipp~ncott, 1983;154-62. 5. Frank AL, Weine FS. NonsurgEal therapy for the perforative defect of internal resorption. J Am Dent Assoc 1973:87:863-8 6 Oswald RJ. Procedural accidents and their repair. Dent Clin North Am 1979,23:593-617. 7. Bhaskar SN, Rappaport HM. Histologic evaluation of endodontic procedures Jn dogs. Oral Surg 1971;31.526-35. 6. Lantz B, Persson P. Periodontal t~ssue reactions after root perforations in dogs' teeth: a histologlc study Odonto~ Tidskr 1967:75:209-20. 9. Sinai IH Endodontic perforatK)ns: their prognosis and treatment. J Am Dent Assoc 1977;95:90-5. 10. Ntchotls E. Treatment of traumatic pertoratlons of the pulp cavity. Oral Surg 1962;15:603-12. 11. Martin LR, Gilbert B. Dickerson AW. I1: Management of endodontic perforations Oral Surg 1982;54:668-77.
Lateral Root Perforations
23
12. Harris WE A simplified method of treatment for endodontic perforations. J Endodon 1976;2;126--34. 13. EIDeeb ME, EIOeeb M, Tabibl A, Jensen JR An evaluation of the use of amalgam, Cavil, and cal~um hydroxide in the repair of furcation perforations. J Endodon 1982;8:459-66. 14. Benenati FW, Roane JB, Biggs JT. Recall evaluation of iatrogenic root perforations repaired with amalgam and gutta-percha J Endodon 1986; 12:161 6. 15 Ingle Jr, Ta~ntor JF. Endodont~cs. 3rd edition. PhiTadelphia: Lea & Febiger, 1985:27-52, 666-72,776-9. 16. Finne K, Nord PN, Persson G. Lennartsson B. Retrograde root filling with amalgam and Cavil. Oral Surg 1977;43;621-6 17. Fox LT, Senia ES, Zeagler J Another look at the odontobtast process. J Endodon 1984;10:538-43. 18. Spangberg L Biological effects of root canal filling material Reactions of bony tissue to implanted root canal filling material in guinea pigs. Odontol Tidskr 1969;77:133-59. 19. Stanley HR, Pameijer CH Pulp capping wdh a new visible-light.-cunng calcium hydroxide composition (Prisma VLC Dycal). Oper Dent 1986:10:15663.
Printed in U.S.A. VOL. 16, NO. 1,d~u~upu~Y1990
An In Vitro Comparison of the Sealing Ability of Materials Placed in Lateral Root Perforations Steve Dazey, DMD, and E. Steve Senia, DDS, MS, BS, FACD
contribute to failure (2, 7-9). Although the desirability of a seal is emphasized, little has been done to measure how well materials used to repair perforations achieve this objective. The purpose of this study was to compare the sealing ability of Tylin amalgam (Kerr Manufacturing Co., Romulus, MI), Ketac-Silver (Espe-Premier Sales Corp., Non-istown, PA), and Prisma VLC Dycal (L. D. Caulk, Co., Milford. DE) used to repair lateral root perforations in vitro.
The in vitro sealing ability of Tytin amalgam, KetacSilver, and Prisma VLC Dycal was compared. Roots of extracted teeth were perforated laterally. After the defects were repaired, the teeth were immersed in dye for 10 days and then sectioned, and the linear extent of dye penetration was measured. Statistical analysis showed that the Prisma VLC Dycal group exhibited significantly less dye penetration than the other two groups (p < 0.01). No difference was found between the Tytin and Ketac-Silver groups.
M A T E R I A L S AND M E T H O D S Eighteen extracted human maxillary canines were placed into 5.25% sodium hypochlorite at room temperature for 30 min to clean the root surfaces and remove the remaining periodontal ligament. Each tooth was secttoned longitudinally (Fig. IA) into a facial and palatal half using an Isomet saw (Buehler Ltd., Lake Bluff, 1L). Fifteen facia/ halves were placed inlo experimental group 1 and 15 palatal halves were designated group 2. Five halves were used as controls. In order to simulate a periodontal ligament, each tooth half was depressed into a patty of vinyl polysiloxane ~mpression material (Espe-Premier), cemental surface down, to the level of the cut surface. The resulting mold also served as a holder. Two perforations approximately 5-mm apart were made into each tooth half with a #2 round bur. The bur entered at the pulpal surface and exited at the root surface. The perforations were angled apically to approximate what might occur clinically if a bur was misdirected during access preparation (Fig. 2). The first perforation exited at the cervial third of the root and the second was placed apically and parallel to the first (Fig. 1B). Ten of the 30 perforations in group 1 and 10 of the perforations in group 2 were repaired with Prisma VLC Dycal. The same was done with Ketac-Silver and with Tytin so that each material was used in 20 perforations. To simulate clinical conditions, a piece of filter paper moistened with physiological saline was placed between the mold and the tooth so that the repair materials would be in contact with a moist environment. The repair materials were introduced into the perforations from the pulpal surface and placed against the filter paper-impression material matrix (simulated periodonr, d ligament) on the root surface. Prior to placement of the repair materials, the dentin surfaces of all specimens were rinsed wilh a water spray and dried with compressed air but were not chemically prepared. The amalgam was placed into the perforation in small increments and gently condensed into place, trying to avoid
Successful end~xlontics depends, in pat~t, on accurate diagnosis and appropriate treatment planning. Because the prognosis for a tooth worsens when a perforation occurs, this potential procedural accident and its prevention should be identified as pa~ of the treatment planning process. As more teeth arc retained throughout the life of adult dental patients, there is an increased demand fbr endodontic treatment of teeth that previously might have been extracted. These salvaged teeth arc often extensively restored and calcified and present a formidable challenge when searching for canals or preparing an adequate post space. Investigators have based the prognosis of an endodontic perforation on its location, the promptness of identification and treatment of the defect, the extent of the defect and the amount of periodontal ligament irritation, the biocompatibility of the material used for repair, and the ability of the repair material to provide a seal (1-8). Of these, location is often the main determinant of success or failure. Several researchers have indicated that a perforation in the apical or middle third of the root has a better prognosis than one in the cervical third ( 1,3, 9). As the perforation and its repair encroach upon the crest of the alveolar bone and the attachment apparatus, the chances for success diminish. When a perforative defect communicates with the oral environment through the gingival sulcus, the prognosis is poor (1, 4, 6, 9). Perforation into a furcation frequently leads to failure (1.3, 4, 8, 9). Several materials have been evaluated in vivo to treat molar perforation nonsurgically. Amalgam has been shown to be successful as have calcium hydroxide and Cavil (1, 2, 5, I 0 15). It appears that long-term success of a perforation repair is reliant on a material with low solubility (2, 13, 16). Several authors indicate tha! the lack of an adequate seal can also 19
20
Dazey and Senia
Joumal of Endodontics
/ A
B
C
%/
D
FIG 1. Sample preparation. A, Tooth was longitudinally sectioned into a palatal and facial half. B, Root perforations were angled apically to simulate a procedural accident. C, After the perforations were repaired and immersed in dye, longitudinal slices were cut parallel to the long axis of the tooth and through the perforations. D, Sections were photographed and linear dye penetration measured.
with sticky wax except for 1 to 2 mm around the repair material on the root surface. All of these specimens had varying amounts of repair material extruded onto the root surface. In group 2 this excess repair material was removed from the root surfaces with the aid of a #15 blade and a dissecting microscope. Then the repair materials were recessed approximately 0.5 m m with a high speed # 170L bur to ensure that they were not in contact with the external root surface. All surfaces of the teeth in this group were also coated with sticky wax except for the recessed perforations. Two root halves, not perforated, were entirely coated with sticky wax to serve as negative controls to verify that the wax provided an adequate barrier against dye penetration. To show that dye flowed into all exposed dentinal tubules, two positive control halves were perforated but not repaired and coated with sticky wax except for the openings on the external root surface. Another root half was used to evaluate the possibility of intertubular leakage (Fig. 3). All specimens were submerged in 2% methylene blue dye for 10 days at room temperature. After rinsing the specimens thoroughly, an Isomet saw with a 0.3-mm blade thickness was used to make thin multiple cuts parallel to the long axis of the tooth and through the perforations (Fig. 1C). After the resulting sections were photographed and projected onto a screen, linear dye penetration was measured independently by two observers from where the repair material made outermost contact with dentin/ cementum to the m a x i m u m depth of penetration along the perforation. The accuracy of the measurements taken from the projected photographs of five specimens from group 1 and five from group 2 was verified by measuring the linear dye penetration directly with a dissecting microscope equipped with an ocular micrometer (Carl Zeiss, Inc., Oberkochen, West Germany). RESULTS In both groups, all of the Tytin and Ketac-Silver repairs demonstrated dye penetration along the entire length of the
Fio 2. Representation of a root perforation caused by a misdirected bur.
excessive extrusion. Using the manufacturer's precapsulated delivery system, the Ketac-Silver was flowed into the perforation and gently patted to place with an endodontic condenser. The Prisma VLC Dycal was placed with a lightprotected l-ml syringe with a 23-gauge endodontic irrigation needle. It was placed incrementally as suggested by the manufacturer and each layer was cured for 60 sec with a handheld curing light (focus activator light; Teledyne Getz, Elk Grove Village, IL). The perforations were repaired and the specimens left untouched in the moist environment at room temperature for 24 h. All surfaces of the teeth in group 1 were then coated
FiG 3. Longitudinally sectioned control tooth showing no intertubular dye penetration. Sample is a facial root half with apical third removed. Preparation into dentin was made by directing a #56 high-speed bur coronally into apical surface. Resulting cavity preparation was surrounded by dentin and did not contact pulp space or external root surface. Dye entered bur hole (b) then penetrated into exposed dentinal tubules (arrows) and pulp space (ps) subjacent to exposed tubules. Once dye entered the pulp space, it seeped along the canal wall but did not enter unexposed dentinal tubules, rs, root surface
Vol. 16, No. 1, January 1990
Lateral Root Per/orations
21
FIG 4. A to D, Experimental samples (original magnification x l for A and B; x l 0 for C and D). The two sections in A are adjacent sections as are those in B. The sections with greatest dye penetration were measured. C, Arrows indicate direction of dye penetration. D, Dye penetration (arrows) into the dentinal tubules exposed by the perforation repaired with amalgam but not those repaired with Prisma VLC Dycal. AM, amalgam; KS, Ketac-Silver; VLC, Prisma VLC Dycal; rs, root surface; ps. pulpal surface. The background grid is 1.0 mm per interval.
perforations. Hence, the sealing ability of these two materials was very poor. The Prisma VLC Dycal repairs did not show this maximal penetration in any of the specimens (Fig. 4D). There was significantly less leakage in the Prisma VLC Dycal repairs than in the Tytin and Ketac-Silver repairs (sign test, p < 0.01). Since all of the Tytin and Ketac-Silver repairs in groups 1 and 2 leaked the full length of the repair (mean, 2.9 mm), no statistical difference was discernible between the two groups. The Prisma VLC Dycal repairs in group 1 were compared with those in group 2 using Student's t test. The recessed repair group (group 2) had greater dye penetration (p < 0.05). In group 1, only 20% (2 of 10) showed leakage (mean, 0.16 mm), while 90% (9 of 10) in group 2 had leakage (mean, 1.06 mm). The repairs made in the coronally placed perforations were compared with the more apically located repairs. The difference in leakage between the apical and coronal repairs made with Prisma VLC Dycal was not significant (Student's t test, p > 0.01). Both positive controls showed maximal dye penetration into the perforations while the negative controls showed none. DISCUSSION In all specimens where dye penetration occurred, the dye not only penetrated along the dentin-repair material interface, but also through the entire length of the dentinal tubules that communicated with the perforation. Fox et al. (17) and others describe frequent branching and anastomosing of the odontoblasl processes within the radicular dentinal tubules. The possibility exists that the dye may not only penetrate along the repair material interface, but also may penetrate by means of intertubular leakage via these anastomoses. If this occurs,
an accurate evaluation of dye penetration may not be possible. Although it was not the purpose of this investigation to evaluate the possibility of intertubular leakage, observation of the experimental specimens and a .separate control tooth (Fig. 3) indicated that no significant penetration of this type occurred under the conditions of this study. However, when the dye entered into a tubule, it penetrated the entire length o f the tubule. This resulted in a greater amount of leakage into the tubules than along the interface. It also allowed the dye to travel to areas far removed from the perforation site. The experimental design was intended to allow standardization of the perforations in a controlled environment so a valid comparison could be made. The maxillary canine was selected because of the long root and relatively constant root thickness. The canine root was not long enough to allow three side by side perforations but there was enough length for two. To standardize the angle of the perforations, the teeth were split in half and both halves were used. This procedure does not simulate clinical access to a perforation and it is not meant to imply that midroot perforations arc amenable to such a repair. It does, however, provide standardized perforations which can be used to compare leakage. Statistical analysis indicated the midroot perforations did not leak differently than the cervical ones. During a pilot study, concerns were raised as to what effect extruding a repair material onto the root surface would have on its sealing ability. For this reason, a second experimental group, group 2, was included. Group 1 represented perforation repairs where the material was allowed to extrude, as it would clinically, resulting in excess material on the surface o f the tooth. In group 2. this excess was removed and the repair material recessed slightly below the external root surface. Dye penetration in this group was expected to occur into the dentinal tubules exposed when the repair was recessed. Indeed
22
Dazey and Senia
F,a 5. Spe~men from group 2. DentinaJ tubules dose to the root surface were exposed when the excess repair matenal was removed. Arrows point out dye penetration along the length of these tubules. VLC, Prisma VLC Dycal; AM, amalgam; ps, pulpal surface; rs, root surface.
this was observed with the Prisma VLC Dycal specimens where the leakage occurred only along the length of these few exposed tubules (Fig. 5). In a sense, these exposed tubules provided an additional positive control. The excess material had no observable effect on the Tytin or Ketac-Silver repairs. Both of these materials leaked the full length ofthe perforation whether the excess material was present or removed. The same was not true for the Prisma VLC Dycal repairs. Only two specimens showed leakage in group 1. Although group 2 demonstrated a greater frequency of leakage than group 1, the linear depth of penetration was still significantly less with Prisma VLC Dycal than with Tytin or Ketac-Silver. C o m m o n postendodontic restorative techniques use metal posts cemented within the root canal space. Luting cements such as zinc phosphate, polycarboxylates, and glass ionomers are often used. Core build-up materials are also placed in the pulp chamber and canal orifices. These core materials include amalgam, composites, glass ionomers, intermediate or temporary filling materials, and various combinations. Dental amalgam may be condensed directly into the canal orifices as part of an amalgam core technique. Glass ionomer-amalgam combinations and composite resins are also used as core materials. With such a variety of materials available for use in build-up and post and core techniques, it would seem reasonable to select ones which would be compatible with an undetected perforation. It would also be desirable to use materials and techniques that can be used at the time the perforation occurs, that provide a good seal, do not absorb, are biocompatible, can be placed noninvasively, and do not cause additional physical damage to the periodontal tissue by extruding outside the root through the defect. The biocompatibility of amalgam has been demonstrated (13, 16, 18). It has performed well when used as a core buildup and retrofilling material. It is very durable and effective when adequately condensed. It can, however, cause a gingival tattoo when used subgingivally. For this and other esthetic reasons, its restorative and endodontic uses near gingival tissues are usually restricted to posterior teeth. When a perforation is repaired with amalgam from within the tooth, the potential exists for extruding excess material during conden-
Joumal of Endodontics
sation. Its physical presence in the periodontal ligament space can contribute to chronic inflammation (5, 6, 9, 10). In this regard, a flowable material could have an advantage over a condensable one. Amalgam used without a cavity varnish will almost certainly allow leakage. Investigators that have used amalgam as a perforation repair material (6, 9, 10, 13, 14) either have not included a cavity varnish in their technique or neglect to mention its use. The experimental design selected for this investigation did not utilize a cavity varnish to point out this leakage potential. Glass ionomer cements can be flowed and gently patted into place. When formulated into an amalgam-containing preparation such as Ketac-Silver, the glass ionomers have become a very popular and efficient core build-up material. Calcium hydroxide preparations are used extensively in dentistry. A recently introduced product, Prisma VLC Dycal, combines calcium hydroxide into a visible light-curing preparation. It has been shown to have nearly a 3-fold increase in compressive strength and at least a 3-fold decrease in water solubility when compared with other hardening calcium hydroxide preparations (19). When used for direct pulp capping, this material does not produce a layer of mummification or necrosis. Prisma VLC Dycal has passed all of the recommended initial and secondary tests for biocompatibility. It can be flowed into place and adequately cured with the 4m m light wands designed for use in posterior teeth. The setting and working times are not sensitive to humidity or moisture. It is also capable of bonding with composite resins. Although Prisma VLC Dycal has been shown to be effective when used in pulp capping procedures, its in vivo potential for perforation repair has not been evaluated. Amalgam, glass ionomer, and calcium hydroxide materials are currently used in various restorative and endodontic procedures. They each possess a therapeutic potential for treating known and undetected root perforations. The outcome of a perforation repair depends on a combination of conditions and circumstances which determine the chances for a biologically acceptable result. The sealing ability of the repair material is one of these. In vitro data on the sealing abilities of repair materials would appear to be a logical precursor to an in vivo investigation of long-term success. This study was supported by research funding from the United States Air Force. The opimons and assertions are those of the authors and are not to he construed as official or as reflectin(j the views of the United States Air Force or the Department of Defense. The authors w=sh to thank Dr. Carlos E. del Rio for his support and suggestions. We also wish to thank Or. George M Barnwell for his guidance in prepanng the statistical analysis. Dr. Dazey is a former resident. Department of Endodontics. Wifford Hall USAF Med~,al Center. Lackland Air Force Base, TX. Dr. Senia is associate professor and director, graduate endodontics, The University of Texas Health Science Center, San Antonio. TX.
References 1. Seltzer S, Sinai IH, August D. Periodontal effects of root perforations before and during endodontlc I~OCedures. J Dent Res 1970;49:332-9. 2. Jew RCK. Weine FS, Keene J J, Smulson MH. A histologic evaluation of
Vol. 16, No. 1, January 1990 penodontal tissues adjacent to root perforations filled with Cavil Oral Surg 1982:54:124-35. 3. Frank A L Resorption, perforation, and fTactures. Dent Clin North Am 1974;18:465-87. 4. Frank AL, Simon JHS, Abou-Rass M, Ghck DH. Chnlcal and surgical endodontics. Philadelphia JB Lipp~ncott, 1983;154-62. 5. Frank AL, Weine FS. NonsurgEal therapy for the perforative defect of internal resorption. J Am Dent Assoc 1973:87:863-8 6 Oswald RJ. Procedural accidents and their repair. Dent Clin North Am 1979,23:593-617. 7. Bhaskar SN, Rappaport HM. Histologic evaluation of endodontic procedures Jn dogs. Oral Surg 1971;31.526-35. 6. Lantz B, Persson P. Periodontal t~ssue reactions after root perforations in dogs' teeth: a histologlc study Odonto~ Tidskr 1967:75:209-20. 9. Sinai IH Endodontic perforatK)ns: their prognosis and treatment. J Am Dent Assoc 1977;95:90-5. 10. Ntchotls E. Treatment of traumatic pertoratlons of the pulp cavity. Oral Surg 1962;15:603-12. 11. Martin LR, Gilbert B. Dickerson AW. I1: Management of endodontic perforations Oral Surg 1982;54:668-77.
Lateral Root Perforations
23
12. Harris WE A simplified method of treatment for endodontic perforations. J Endodon 1976;2;126--34. 13. EIDeeb ME, EIOeeb M, Tabibl A, Jensen JR An evaluation of the use of amalgam, Cavil, and cal~um hydroxide in the repair of furcation perforations. J Endodon 1982;8:459-66. 14. Benenati FW, Roane JB, Biggs JT. Recall evaluation of iatrogenic root perforations repaired with amalgam and gutta-percha J Endodon 1986; 12:161 6. 15 Ingle Jr, Ta~ntor JF. Endodont~cs. 3rd edition. PhiTadelphia: Lea & Febiger, 1985:27-52, 666-72,776-9. 16. Finne K, Nord PN, Persson G. Lennartsson B. Retrograde root filling with amalgam and Cavil. Oral Surg 1977;43;621-6 17. Fox LT, Senia ES, Zeagler J Another look at the odontobtast process. J Endodon 1984;10:538-43. 18. Spangberg L Biological effects of root canal filling material Reactions of bony tissue to implanted root canal filling material in guinea pigs. Odontol Tidskr 1969;77:133-59. 19. Stanley HR, Pameijer CH Pulp capping wdh a new visible-light.-cunng calcium hydroxide composition (Prisma VLC Dycal). Oper Dent 1986:10:15663.
