Shrinkage of endodontic sealers
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Methods.—The tested combinations were AH26 þ gutta-percha, Resilon þ Epiphany, and Ketac-Endo Aplicap þ gutta-percha. AH26 is an epoxy resin sealer, Resilon is a dual-curable thermoplastic synthetic resin material, and Ketac-Endo Aplicap is a glass ionomer-based sealer. Fifteen root canals that had been instrumented were treated with each of the combinations, forming three treatment groups; another 15 root canals had no obturation. All were sub- jected to gradually increasing force until they fractured. Results.—All of the roots fractured, and most fractures were oriented vertically (Table 1). The groups differed sig- nificantly, with higher resistance for the AH26 þ gutta-per- cha group than for the other three groups. The Resilon þ Epiphany and Ketac-Endo Aplicap þ gutta-percha groups also had significantly different resistance values. However, the fracture resistance of the Ketac-Endo Aplicap þ gutta- percha group did not differ significantly from that of controls. Discussion.—The greatest fracture resistance was achieved with the AH26 þ gutta-percha obturation combi- nation. Gutta-percha also has the properties of availability, ease of manipulation, and relative reinforcement effect, making it still an attractive first choice for root canal obturation. Clinical Significance.—Root fracture is a com- mon mode of failure for root canal filled teeth. Of the three filling techniques analyzed here, AH26 D gutta-percha was the most resistant to fracture. The effect of post placement on strength with these materials was not addressed in this study. Ulusoy O ¨ _ IA, Genc ¸O ¨ , Arslan S, et al: Fracture resistance of roots ob- turated with three different materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 104:705-708, 2007 Reprints available from O ¨ _ IA Ulusoy, Dept of Operative Dentistry and Endodontics, Gazi Univ Dental Faculty, 8.St, Emek, Ankara, Turkey; e-mail: [email protected] Shrinkage of endodontic sealers Background.—In root canal therapy, three-dimensional obturation is carried out to prevent leakage and reinfection. Leakage from apical and coronal sites may cause more fail- ure of endodontically treated teeth than any other factor. The methacrylate resin systems developed bond to tooth structure better than traditional gutta-percha, which should minimize leakage. However, resin materials suffer from polymerization shrinkage, which can lead to stress on the root canal walls, marginal gaps, microleakage, and clinical failure. Polymerization shrinkage causing strain is time- dependent and not fully understood. The most recently developed root canal sealers were investigated to deter- mine their polymerization shrinkage behavior. Methods.—The EndoRez, RealSeal, and GuttaFlow products were tested. The first two are dual cure resin- based materials and the last is silicon based. Tubli-Seal (a zinc-oxideeugenol-based material) was used as a stan- dard to which the other materials were compared. The bonded disk method was used for 60 specimens tested at 23 C and 37 C. Samples underwent tests for 24 hours, with the dual cure resin-based sealers tested as chemically cured only and as dual cured. Polymerization shrinkage be- havior and polymerization shrinkage-strain were measured. Results.—At 23 C all of the sealers except GuttaFlow demonstrated polymerization shrinkage (Table 2). The highest shrinkage-strain value of 7.81% was noted for En- doRez dual cure; the lowest value of 0.14% was found with Tubli-Seal. At 37 C the shrinkage-strain values were comparable to those at 23 C except for Tubli-Seal. With increased temperature there was a decline in setting time for all groups. Overall, Tubli-Seal was dimensionally stable, with polymerization shrinkage-strain values that were very low at both temperatures. GuttaFlow was also quite stable but showed a slight expansion, as expected. EndoRez dual cure demonstrated higher shrinkage-strain values than the other materials. The working time of the Tubli-Seal Table 1.—Mean, Standard Deviation, and Minimum and Maximum Values of Forces for Experimental Groups (in Newtons) Groups n Mean SD Min Max 1 (AH26 þ gutta-percha) 15 1021.04 226.74 684.31 1365.01 2 (Resilon þ Epiphany) 15 886.33 175.15 600.00 1223.96 3 (Ketac-Endo Aplicap þ gutta-percha) 15 741.38 175.46 426.73 1053.56 4 (No obturation) 15 831.40 163.07 598.00 1202.00 (Courtesy of Ulusoy O ¨ _ IA, Genc ¸O ¨ , Arslan S, et al: Fracture resistance of roots obturated with three different materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 104:705-708, 2007.) 314 Dental Abstracts
Transcript of Shrinkage of endodontic sealers
Methods.—The tested combinations were AH26 þgutta-percha, Resilon þ Epiphany, and Ketac-Endo Aplicapþ gutta-percha. AH26 is an epoxy resin sealer, Resilon isa dual-curable thermoplastic synthetic resin material, andKetac-Endo Aplicap is a glass ionomer-based sealer. Fifteenroot canals that had been instrumented were treated witheach of the combinations, forming three treatment groups;another 15 root canals had no obturation. All were sub-jected to gradually increasing force until they fractured.
Results.—All of the roots fractured, and most fractureswere oriented vertically (Table 1). The groups differed sig-nificantly, with higher resistance for the AH26 þ gutta-per-cha group than for the other three groups. The Resilon þEpiphany and Ketac-Endo Aplicap þ gutta-percha groups
also had significantly different resistance values. However,the fracture resistance of the Ketac-Endo Aplicap þ gutta-percha group did not differ significantly from that ofcontrols.
Discussion.—The greatest fracture resistance wasachieved with the AH26 þ gutta-percha obturation combi-nation. Gutta-percha also has the properties of availability,ease of manipulation, and relative reinforcement effect,making it still an attractive first choice for root canalobturation.
Clinical Significance.—Root fracture is a com-mon mode of failure for root canal filled teeth.Of the three filling techniques analyzed here,AH26 D gutta-percha was the most resistant tofracture. The effect of post placement onstrength with these materials was not addressedin this study.
Ulusoy O_IA, Genc O, Arslan S, et al: Fracture resistance of roots ob-turated with three different materials. Oral Surg Oral Med OralPathol Oral Radiol Endod 104:705-708, 2007
Reprints available from O_IA Ulusoy, Dept of Operative Dentistry andEndodontics, Gazi Univ Dental Faculty, 8.St, Emek, Ankara, Turkey;e-mail: [email protected]
Table 1.—Mean, Standard Deviation, and Minimumand Maximum Values of Forces for ExperimentalGroups (in Newtons)Groups n Mean SD Min Max
1 (AH26 þ gutta-percha) 15 1021.04 226.74 684.31 1365.012 (Resilon þ Epiphany) 15 886.33 175.15 600.00 1223.963 (Ketac-Endo Aplicap þ
gutta-percha)15 741.38 175.46 426.73 1053.56
4 (No obturation) 15 831.40 163.07 598.00 1202.00
(Courtesy of Ulusoy O_IA, Genc O, Arslan S, et al: Fracture resistance of roots
obturated with three different materials. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 104:705-708, 2007.)
Shrinkage of endodontic sealers
Background.—In root canal therapy, three-dimensionalobturation is carried out to prevent leakage and reinfection.Leakage from apical and coronal sites may cause more fail-ure of endodontically treated teeth than any other factor.The methacrylate resin systems developed bond to toothstructure better than traditional gutta-percha, which shouldminimize leakage. However, resin materials suffer frompolymerization shrinkage, which can lead to stress on theroot canal walls, marginal gaps, microleakage, and clinicalfailure. Polymerization shrinkage causing strain is time-dependent and not fully understood. The most recentlydeveloped root canal sealers were investigated to deter-mine their polymerization shrinkage behavior.
Methods.—The EndoRez, RealSeal, and GuttaFlowproducts were tested. The first two are dual cure resin-based materials and the last is silicon based. Tubli-Seal(a zinc-oxide�eugenol-based material) was used as a stan-dard to which the other materials were compared. The
314 Dental Abstracts
bonded disk method was used for 60 specimens tested at23�C and 37�C. Samples underwent tests for 24 hours,with the dual cure resin-based sealers tested as chemicallycured only and as dual cured. Polymerization shrinkage be-havior and polymerization shrinkage-strain were measured.
Results.—At 23�C all of the sealers except GuttaFlowdemonstrated polymerization shrinkage (Table 2). Thehighest shrinkage-strain value of 7.81% was noted for En-doRez dual cure; the lowest value of 0.14% was foundwith Tubli-Seal. At 37�C the shrinkage-strain values werecomparable to those at 23�C except for Tubli-Seal. Withincreased temperature there was a decline in setting timefor all groups. Overall, Tubli-Seal was dimensionally stable,with polymerization shrinkage-strain values that were verylow at both temperatures. GuttaFlow was also quite stablebut showed a slight expansion, as expected. EndoRez dualcure demonstrated higher shrinkage-strain values thanthe other materials. The working time of the Tubli-Seal
Table 2.—Final Polymerization Shrinkage-Strain (%) After 24 Hours of Tested Root Canal Sealers (StandardDeviations in Parentheses) and Time at Which the Polymerization Process of the Sealers Started (minutes)
23�C 37�C
Shrinkage-strain Start of Polymerization Shrinkage-strain Start of polymerization
Tubli-Seal 0.14% (0.06) 65.9 0.2% (0.09) 18.5GuttaFlow �0.16% (0.14) 124.8 �0.76% (0.10) 38.3EndoRezD* 7.81% (0.30) 27.7 9.33% (0.77) 1.9EndoRezCy 7.05% (0.13) 42.1 8.3% (1.04) 4.3RealSealD* 2.34% (0.25) 21.1 3.54% (0.22) 1.3RealSealCy 4.15% (0.18) 28.3 4.47% (0.15) 6.5
D, Dual cure; C, chemical cure.
(Courtesy of Hammad M, Qualtrough A, Silikas N: Extended setting shrinkage behavior of endodontic sealers. J Endod 34:90-93, 2008.)
and GuttaFlow was greater than for the resin-based sealers,possibly helping to achieve better adaptation in the rootcanal.
Discussion.—Resin-based sealers are becoming quitecommon in root canal therapy and offer advantages relatedto chemical bonding that other sealers do not have, such asincreased resistance to vertical fracture. However, theshrinkage associated with polymerization for these mate-rials presents a serious disadvantage. In the comparison,significant differences were found between the various ma-terials. The highest shrinkage-strain values were obtainedwith EndoRez, then, in descending order, RealSeal and Tu-bli-Seal. GuttaFlow exhibited expansion on polymerization,which may help to prevent gap formation and decreasemicroleakage.
Esthetic DentistryScrew access hole chipping fractur
Background.—Ceramic materials are used in dentistrybecause they are highly biocompatible, offer good es-thetic results, and show minimal accumulations of plaque.However, catastrophic failure can occur, affecting bothfunction and esthetics. Various systems for repairing ce-ramic restorations intraorally are now available. Advan-tages of these systems include the ability to obtainnatural color blending, excellent retention, and adhesivedurability of the composite resin to the fractured ceramicsurface. Screw-retained ceramic veneered implant fixedpartial dentures (FPDs) with restored or unrestoredscrew access holes (SAHs) were investigated to determineif dynamic loading produces more chipping fractureson the occlusal surface of the FPDs with or withoutrestorations.
Clinical Significance.—Resin-based sealersare enjoying popularity due to the anticipatedadvantage of their bonding to tooth structure,thus enhancing their sealing ability. However,they shrink on setting, and the forces therebygenerated may overcome the strength of thebond. Further studies, especially clinical trials,are needed to sort things out.
Hammad M, Qualtrough A, Silikas N: Extended setting shrinkagebehavior of endodontic sealers. J Endod 34:90-93, 2008
Reprints available from M Hammad, School of Dentistry, The Univof Manchester, Higher Cambridge St, Manchester M15 6FH, UK;e-mail: [email protected]
es
Methods.—A total of 20 screw-retained ceramicveneered five-unit FPDs were prepared for a three-implantsituation. After the ceramic surface was etched with hydro-fluoric acid for 1 minute, the SAHs were filled with a foampellet and silicone to the interface of metal and ceramic.A silane coupling agent and bonding agent were appliedto the surface, then composite resin was used to restorethe SAHs for 10 samples (Fig 2). These underwent adjust-ments of the static and dynamic occlusion and polishing.Ten other samples remained unrestored. All of the FPDswere loaded to the implant position for 20,000 cycles of100 N of force for 1 second, then no load for 1 second.The FPDs were then assessed by three investigators usinga light microscope and dental probe to determine the num-ber of chipping fractures present in each case.
Volume 53 � Issue 6 � 2008 315
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