Root Canal Irrigants
Matthias Zehnder, Dr. med. dent., PhD
Local wound debridement in the diseased pulp space is the main step in root canal treatment to prevent the tooth from being a source of infection. In this review article, the specifics of the pulpal microenvironment and the resulting requirements for irrigating solutions are spelled out. Sodium hypochlorite solutions are recommended as the main irrigants. This is because of their broad antimicrobial spectrum as well as their unique capacity to dissolve necrotic tissue remnants. Chemical and toxicological concerns related to their use are discussed, including different approaches to enhance local efficacy without increasing the caustic potential. In addition, chelating solutions are recommended as adjunct irrigants to prevent the formation of a smear layer and/or remove it before filling the root canal system. Based on the actions and interactions of currently available solutions, a clinical irrigating regimen is proposed. Furthermore, some technical aspects of irrigating the root canal system are discussed, and recent trends are critically inspected.
Endodontic Treatment Outcome: Survey of Oral Health Care Professionals
Ilan Rotstein, DDS, Robert Salehrabi, DDS, Jane L. Forrest, BSDH, MS, EdD
This study assessed the opinion of oral health care professionals regarding the predictability of initial endodontic treatment, expected long-term outcome and the importance of placing a coronal coverage after completion of treatment. An eight-item questionnaire was distributed among oral health care professionals. There were 49% of participants who responded that the expected retention rate of teeth 5 to 10 yr after endodontic treatment was more than 90%, whereas 44% responded that such retention rate was between 70 to 80%. The majority of the participants also responded that the need for additional treatment, such as retreatment, apical surgery or extraction, was expected to occur within the first 3 yr after endodontic treatment if initial treatment has failed. About 87% of participants responded that placing coronal coverage after completion of endodontic treatment in premolars and molars was very important for long-term tooth retention and 92% responded that overall, endodontic treatment was a predictable procedure with long-term tooth retention rate. Statistically significant associations were found between years of experience and expected rate of retention for both the total group of respondents (p < 0.001) and for general practitioners when examined separately (p < 0.002). Statistically significant associations were only found for general practitioners between years of experience and their responses regarding the need for additional treatment (p < 0.05) and overall predictability of endodontic treatment (p < 0.02). A trend was found between the professionals’ years of experience and their opinion regarding the importance of coronal coverage. Of the group who had more than 20 yr of experience, about 87% considered coronal coverage to be very important for long-term tooth retention. In conclusion, it appears that most clinicians participating in this study consider endodontic therapy to be a predictable procedure with long-term tooth retention rate. Their opinions also reflect the variations that currently exist in the literature regarding the reported outcome of endodontic treatment.
Effects of Nd:YAG Laser Pulpotomy on Human Primary Molars
Jeng-fen Liu, DDS, MS
The purpose of this study was to compare the effects of Nd:YAG laser pulpotomy to formocresol pulpotomy on human primary teeth. Patients with a primary tooth that required pulpotomy because of pulpal exposure to caries, were selected for this study. After removal of coronal pulpal tissue, Nd:YAG laser at 2 W, 20 Hz, 100 mJ or a 1:5 dilution of formocresol was introduced into the canal orifice for complete hemostasis. IRM paste was then placed over the pulp stump, and the tooth was restored either with composite resin or stainless steel crown. Sixty-eight teeth were treated with Nd:YAG laser and followed up for 6 to 64 months. Clinical success was achieved in 66 out of the 68 teeth (97 %), and 94.1 % were radiographically successful. In the control group, 69 primary molars were treated with formocresol and followed up for 9 to 66 months; 85.5 and 78.3% achieved clinical and radiographic success, respectively. The success rate of Nd:YAG laser pulpotomy was significantly higher than that of formocresol pulpotomy. The permanent successors of the laser-treated teeth erupted without any complications.
Upregulation of Basic Fibroblast Growth Factor in Human Periapical Lesions
Ivan Moldauer, DDS, MS, Ines Velez, DDS, MS, Sergio Kuttler, DDS
Basic fibroblast growth factor is one of a class of heparin-binding growth factors that stimulates endothelial cell proliferation and migration in vitro and angiogenesis in vivo. The purpose of this study was to investigate the expression of basic fibroblast growth factor in chronic periapical lesions of endodontic origin. Ten chronic inflammatory periapical lesions were examined using immunohistochemical staining. The experimental control group consisted of four specimens of uninflamed periodontal ligament tissue. Two independent observers graded the staining intensity for basic fibroblast growth factor. An immunopositive, cytoplasmic, and nuclear reaction for basic fibroblast growth factor, with varying degrees of upregulation was observed in all 10 chronic periapical lesions. We speculate that the formation of granulation tissue and the activation of epithelial cell rests in chronical apical lesions might be associated with a local rise in the tissue level of basic fibroblast growth factor. Therefore, this growth factor could play an important role in the pathogenesis of chronic apical periodontitis and periapical cysts.
Retrospective Evaluation of Surgical Endodontic Treatment: Traditional versus Modern Technique
Igor Tsesis, DMD, Eyal Rosen, DMD, Devorah Schwartz-Arad, DMD, PhD, Zvi Fuss, DMD
The aim of this retrospective study was to compare the outcome of surgical endodontic treatment preformed using the traditional versus modern techniques. There were 110 patients who were treated by surgical endodontic treatment between 2000 and 2002 and evaluated from their dental charts. The surgical endodontic treatment was preformed using a traditional or modern technique. The traditional technique included root-end resection with a 45 degrees bevel angle, and retrograde preparation using a carbide round bur. The modern technique included root-end resection with minimal or no bevel, and retrograde preparation using ultrasonic retro-tips with the aid of a dental operating microscope. The retrograde filling material for both techniques was intermediate restorative material. There were 71 patients with 88 treated teeth that were compatible with the inclusion criteria. Complete healing rate for the teeth treated with the modern technique (91.1%) was significantly higher than that for teeth treated using the traditional technique (44.2%) (p < 0.0001). In the traditional technique a significant (p = 0.032) negative influence of the tooth type was found. Modern surgical endodontic treatment using operative microscope and ultrasonic tips significantly improves the outcome of the therapy compared to the traditional technique.
Determination of the Minimum Instrumentation Size for Penetration of Irrigants to the Apical Third of Root Canal Systems
Abbasali Khademi, DDS, MS, Mohammad Yazdizadeh, DDS, MS, Mahboobe Feizianfard, DDS, MS
The purpose of this study was to determine the minimum instrumentation size required for the effective penetration of irrigants and elimination of debris and smear layer from the apical third of the root canals. The mesiobuccal canals of 40 freshly extracted human mandibular first molar teeth were instrumented using the crown-down technique. The teeth were divided into four test groups according to the size of their Master Apical File (#20, #25, #30, #35), and two control groups. After final irrigation, the removal of debris and smear layer from the apical third of root canals was determined under a scanning electron microscope. The data was analyzed using Kruskal-Wallis and Mann-Whitney tests. Based on the results, it appears that the minimum instrumentation size needed for penetration of irrigants to the apical third of the root canal is a #30 file.
Effect of Blood Contamination on Retention Characteristics of MTA When Mixed With Different Liquids
Richard A. VanderWeele, DMD, Scott A. Schwartz, DDS, Thomas J. Beeson, DDS
Simulated furcation perforations were repaired with and without blood contamination utilizing tooth-colored mineral trioxide aggegrate (MTA) mixed with either MTA liquid (sterile water), lidocaine, or saline. Samples underwent Instron testing at either 24 or 72 hours and at 7 days. Data were analyzed using a 3-way ANOVA and post-hoc testing using Tukey’s true test for significance. All of the 72-hour samples displayed significantly greater resistance to displacement than the 24-hour samples. All of the 7-day samples displayed significantly greater resistance to displacement than the 24-hour and 72-hour samples. Non-contaminated samples displayed significantly greater resistance to displacement than their blood-contaminated counterparts at 7 days. Non-contaminated samples mixed with sterile water, lidocaine, or saline performed similarly at all time periods. Allowing tooth-colored MTA to set undisturbed for 72 hours or longer prior to placement of a coronal restoration may decrease the chance of MTA displacement in furcation perforation repairs.
Elemental Analysis of Crystal Precipitate from Gray and White MTA
T. Brian Bozeman, DDS, Ronald R. Lemon, DMD, Paul D. Eleazer, DDS, MS
Crystal growth and elemental dissolution characteristics of gray Mineral Trioxide Aggregate (GMTA), white MTA (WMTA), and an experimental material, Dentalcrete, were compared. For part A, comparing amount and composition of surface crystal growth, twelve cylinders of each material were suspended in Phosphate Buffered Saline (PBS) solution without Ca. The crystals were analyzed by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Inductively Coupled Plasma—Atomic Emission Spectroscopy (ICP-AES). For part B, three cylinders of each material were suspended in distilled, deionized water. The water was analyzed by ICP-AES for Ca content at 24 h, 72 h, and 5, 7, 10, and 14 days. Data were analyzed using one-way ANOVA and Tukey test. Both MTA materials released more Ca initially, followed by a decline and then rise in elution. GMTA produced the most surface crystal, which may be clinically significant. The crystals on GMTA and WMTA were chemically and structurally similar to hydroxyapatite (HA).
Is An Oxygen Inhibited Layer Required for Bonding of Resin-Coated Gutta-Percha to a Methacrylate-Based Root Canal Sealer?
Noriko Hiraishi, DDS, PhD, Robert J. Loushine, DDS, Michele Vano, DDS, MS, Nicoletta Chieffi, DDS, MS, R. Norman Weller, DMD, MS, Marco Ferrari, DDS, PhD, David H. Pashley, DMD, PhD, Franklin R. Tay, BDSc (Hons), PhD
Removal of the oxygen inhibition layer from the surface of resin-coated gutta-percha cones during packaging has been hypothesized for their weak adhesion to a methacrylate-based root canal sealer, resulting in their frequent delamination from the sealer after root canal obturation. This study examined the feasibility of creating oxygen inhibition layers on resin-coated gutta-percha cones via the adjunctive application of a dual-cured dentin adhesive just before bonding. Composite cylinders were bonded with EndoREZ to flat, resin-coated gutta-percha disks and similar disks that were post-treated with Prime&Bond NT Dual Cure adhesive and stressed to failure using a modified microshear testing design. Although shear strengths for both groups were relatively low, a 5-fold increase in shear strength was observed after adhesive application, with complex interfacial failures instead of complete sealer delamination from the resin-coating. In-situ dentin adhesive application appears to have merits in enhancing the coupling of resin-coated gutta-percha to methacrylate sealers.
The Effect of Exposure to Irrigant Solutions on Apical Dentin Biofilms In Vitro
M.S. Clegg, DDS, F.J. Vertucci, DMD, C. Walker, PhD, M. Belanger, PhD, L.R. Britto, BDS, MS
This study assessed the effectiveness of different concentrations of sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) (Vista Dental Products, Racine, WI), and BioPure MTAD (Dentsply Endodontics-Tulsa Dental, Tulsa, OK). Intracanal contents were collected from 10 patients diagnosed with chronic apical periodontitis. The samples were cultured on hemisections of root apices to generate a polymicrobial biofilm. Each biofilm was separately immersed in 6% NaOCl, 3% NaOCl, 1% NaOCl, 2% CHX, 1% NaOCl followed by BioPure MTAD, and sterile phosphate buffered solution (PBS). SEM analysis showed 6% NaOCl and 3% NaOCl were capable of disrupting and removing the biofilm; 1% NaOCl and 1% NaOCl followed by MTAD were capable of disrupting the biofilm, but not eliminating bacteria; 2% CHX was not capable of disrupting the biofilm. Viable bacteria could not be cultured from specimens exposed to 6% NaOCl, 2 % CHX, or 1% NaOCl followed by BioPure MTAD. These results indicate that 6% NaOCl was the only irrigant capable of both rendering bacteria nonviable and physically removing the biofilm.
In Vitro Infrared Thermographic Assessment of Root Surface Temperatures Generated by High-Temperature Thermoplasticized Injectable Gutta-Percha Obturation Technique
Mariusz Lipski, DDS, PhD
The aim of this in vitro study was to measure the temperature rises on the outer surface of roots produced by high-temperature thermoplasticized injectable gutta-percha technique. Thirty extracted human teeth with a single canal (15 maxillary central incisors and 15 mandibular central incisors) were used in this study. After root canal cleaning and shaping, the teeth were obturated with the injected gutta-percha heated to 160°C (Obtura II). Temperature changes on the whole mesial outer surface of the roots was measured using an infrared thermal imaging camera. It showed that the use of gutta-percha heated to 160°C to fill the maxillary central incisors and mandibular central incisors resulted in the rises of the root surface temperature by 8.5°C and 22.1°C, respectively. In conclusion, the injection of the gutta-percha heated to 160°C into the root canal of maxillary central incisors produces temperature on the outer root surfaces below the theoretical critical level and, therefore, should not cause damage to supporting periradicular tissues. The injection of gutta-percha into the root canal space of the mandibular central incisors in vitro, resulted in an elevation of the root surface temperature by more than 10°C.
Role of Free Radicals and Metal Ions in Direct Current-Induced Cytotoxicity
Yuko Nakamura, DDS, Keiso Takahashi, DDS, PhD, Kazue Satoh, PhD, Akiko Shimetani, DDS, Hiroshi Sakagami, PhD, Hirofumi Nishikawa, DDS, PhD
The purpose of this study was to investigate the mechanism of direct current (DC)-induced cytotoxicity. To test the working hypothesis that electrolysis products are responsible for the DC-induced cytotoxicity, the cytotoxic effects between the direct and indirect DC treatment against human polymorphonuclear cells (PMNs) was compared. The indirect DC treatment (treatment with the culture medium exposed to DC) was comparable in cytotoxicity to the direct DC treatment, suggesting that electrolysis products have an important role in DC-induced cytotoxicity. Metal ions released from different electrodes into the culture medium were quantified by the inductively coupled plasma-mass spectroscopy. Higher concentrations of Ag, Zn, and Ni and chromium were released from Ag, Zn, and stainless steel (St) electrodes, respectively, whereas much lower concentrations of Ni and Ti were released from Ni-Ti electrode. Further, electron spin resonance spectroscopy with spin-trapping agent showed that the direct current with the following metal electrodes generated alkoxyl radical (St and Ni-Ti electrodes), hydrogen radical (Ag and Au electrodes), and both carbon and alkoxyl radicals (Zn electrode), respectively. These results suggest that free radicals and metal ions released from electrodes contribute to the cytotoxicity of DC treatment used for iontophoresis.
Improving the Quality of the Quartz Fiber Postcore Bond Using Sodium Ethoxide Etching and Combined Silane/Adhesive Coupling
Francesca Monticelli, Raquel Osorio, Manuel Toledano, Cecilia Goracci, Franklin R. Tay, Marco Ferrari
The influence of different silane/dentin adhesives on the microtensile bond strengths of a hybrid composite to sodium ethoxide-etched quartz fiber posts was investigated. A prehydrolyzed silane was applied without an adhesive and compared to two-component systems in which hydrolysis of the silane occurred after mixing with the acidic monomer present in the dentin adhesives. Nanoleakage along post/core interfaces was examined after silver nitrate tracer penetration using scanning electron microscopy. Higher interfacial strengths and more uniform adaptation between the etched fiber post surface and the composite core were recorded after post treatment with silane/adhesive couplings. The combination of silane with two-step self-etch adhesives improves the chemical retention of composites around etched fiber posts with minimal nanoleakage. Although the one-step self-etching adhesive/silane combination enhances post adhesion, the extensive nanoleakage provides channels for rapid water sorption that may expedite hydrolytic degradation of the post/core interface.
Contamination of Tooth-Colored Mineral Trioxide Aggregate Used as a Root-End Filling Material: A Bacterial Leakage Study
Angela M. Montellano, DMD, Scott A. Schwartz, DDS, Thomas J. Beeson, DDS
Abstract
This experiment investigated the ability of tooth-colored mineral trioxide aggregate (MTA) to maintain an apical seal in the presence of bacteria when contaminated with blood, saline or saliva. Ninety extracted human teeth with single canals were randomly placed into six groups of 15. Canals were prepared to size 50. The apical 3 mm of each root was removed and 3 mm root-end preparations were made with a #329 bur. Root-end preparations in groups 1 through 3 were filled with MTA after contamination with blood, saline, or saliva, respectively. In group 4, uncontaminated root-end preparations were filled with MTA. Groups 5 and 6 served as negative and positive controls. A tube/tooth assembly was utilized to suspend each root end in Trypticase Soy Broth (TSB). The access chambers were filled with Staphylococcus epidermidis. Positive growth over thirty days was demonstrated by turbidity of the TSB. Vitek analysis was used to confirm the presence of S. epidermidis in the positive samples. Data evaluation consisted of a χ2 analysis (p < 0.05). Although all experimental groups demonstrated leakage, tooth-colored MTA contaminated with saliva (group 3) leaked significantly more than the uncontaminated tooth-colored MTA (group 4) (p = 0.028).
A Quantitative Comparison of the Fill Density of MTA Produced by Two Placement Techniques
Priscilla Yeung, DMD, Frederick R. Liewehr, DDS, MS, Peter C. Moon, PhD
This study compared the fill density of mineral trioxide aggregate (MTA) produced by hand condensation with that produced by hand condensation with indirect ultrasonic (US) activation. Sixty acrylic blocks with straight or curved canals were instrumented to an apical size 45, and weighed with a digital electronic balance. In 30 randomly chosen specimens, the canal was filled with MTA by hand condensation and weighed. The MTA was removed; the canal was rinsed and dried, and refilled using hand condensation with indirect US activation. In the other 30 specimens, the procedure was carried out identically but in reverse order. The blocks were then reweighed. The weight of the MTA fill produced by the two placement methods in the two canal configurations was analyzed by a two-way ANOVA. Hand condensation with indirect US activation resulted in an MTA fill that was statistically significantly heavier, and thus denser, than that accomplished by hand condensation alone in both curved and straight canals (p < 0.0001).
Interaction between EDTA and Sodium Hypochlorite: A Nuclear Magnetic Resonance Analysis
Nicola Maria Grande, DDS, Gianluca Plotino, DDS, Alessandro Falanga, DDS, Massimo Pomponi, Francesco Somma, MD, DDS
Recent studies detected erosion of the dentinal walls following the use of EDTA as a final flush. Several authors have studied degradation of EDTA and it appears to be caused by an oxidation reaction. The objective of this paper was to verify through nuclear magnetic resonance (NMR) analysis if the oxidizing property of sodium hypochlorite inactivates EDTA. Solutions of sodium hypochlorite and EDTA were analyzed. EDTA tracing and the appearance of new signals indicative of by-products of the reaction, were studied at different time intervals with a NMR analysis. The tracings of NMR analysis confirmed that the reaction between sodium hypochlorite and EDTA lead to a very slow but progressive degradation of this compound. Mindful of the limitations of an in vitro study, the results of this study nevertheless demonstrated that a final flush with sodium hypochlorite cannot limit the chelating effects of EDTA in a clinically realistic time period.
Ultramorphological and Histochemical Changes After ER,CR:YSGG Laser Irradiation and Two Different Irrigation Regimes
Emre Altundasar, DDS, Bahar Özçelik, DDS, PhD, Zafer C. Cehreli, DDS, PhD, Koukichi Matsumoto, DDS, PhD
The purpose of this study was to evaluate the ultramorphological and chemical changes in Er,Cr:YSGG laser-treated radicular dentin in comparison with two different irrigation regimes. Extracted human premolars were assigned into three experimental groups. Group 1: After each file size, root canals were irrigated with 5.25% NaOCL, followed by a final irrigation with 5.25% NaOCL. Group 2: At each file size, biomechanical preparation was performed in conjunction with Rc-Prep, followed by 5.25% NaOCL irrigation; and 5.25% NaOCL for the final flush. Group 3: 5.25% NaOCL was used after each file size, followed by Er,Cr:YSGG laser irradiation; and a final flush with 5.25% NaOCL. Scanning electron microscopic (SEM) evaluations revealed failure of smear removal in NaOCL-irrigated specimens. RC-Prep + NaOCL-treated dentin revealed moderate-to-total presence of the smear layer with distinct areas of exposed collagen. Er,Cr:YSGG laser irradiation of radicular dentin also resulted in partial or total removal of the smear associated with a few small regions of thermal injury, including carbonization and partial melting. Energy dispersive X-ray analysis (SEM-EDX) showed no significant difference between the Ca/P ratios of the test groups, suggesting absence of changes at the molecular level.
Efficacy of Different Rotary Instruments for Gutta-Percha Removal in Root Canal Retreatment
Jörg F. Schirrmeister, DDS, Karl-Thomas Wrbas, DDS, Katharina M. Meyer, DDS, Markus J. Altenburger, DDS, Elmar Hellwig, DDS, PhD, Prof.
The purpose of this study was to evaluate the efficiency of FlexMaster, ProTaper, and RaCe rotary instruments compared with Hedström files for removal of gutta-percha during retreatment. Sixty mandibular premolars with one single straight canal were instrumented with K-type files and filled using cold lateral compaction and sealer. The teeth were randomly divided into four groups of 15 specimens each. After repreparation with Gates Glidden burs and the test instruments the specimens were cleared. The area of remaining gutta-percha/sealer on the root canal wall was measured from two directions. The RaCe group showed significantly less residual obturation material than FlexMaster and Hedström group (p < 0.05; closed test procedure). There was no difference between ProTaper and all other instruments (p > 0.05). ProTaper and RaCe instruments required significantly less time for retreatment than FlexMaster and Hedström files (p < 0.05). One RaCe file, two ProTaper, and two FlexMaster instruments separated. RaCe cleaned obturated canals more effectively than hand files and FlexMaster files.
Ultrastructure of Intraradicular Dentin After Irrigation with BioPure MTAD. II. The Consequence of Obturation with an Epoxy Resin-Based Sealer
Franklin R. Tay, BDSc (Hons), PhD, Yumiko Hosoya, DDS, PhD, Robert J. Loushine, DDS, David H. Pashley, DMD, PhD, R. Norman Weller, DMD, MS, Danny C.Y. Low, BDS, MSc(Dent)
In addition to an initial report on the creation of thick demineralized collagen matrices in root dentin that were irrigated with BioPure MTAD or EDTA as final rinses for 5 minutes, this study examined the effect of a 2-minute irrigation time of these final irrigants on the extent of demineralization of intact intraradicular dentin and on interfacial nanoleakage after obturation with AH Plus and gutta-percha using warm vertical compaction. Transmission electron microscopy confirmed that the reduction in irrigation time did not compromise the smear layer removing capacity of these two irrigants when 1.3% NaOCl was employed as the initial rinse. BioPure MTAD created 5 to 6 μm thick demineralized dentin matrices, while 17% EDTA produced 1 to 2 μm thick matrices that were suboptimally infiltrated by the epoxy resin-based sealer, as manifested by the occurrence of silver tracer deposits within the hybrid layers.
Nonsurgical Endodontic Treatment of a Two-Rooted Maxillary Central Incisor
Wen-Chun Lin, DDS, Shue-Fen Yang, DDS, MS, Sheng-Fang Pai, DDS
This case report presents an uncommon case of a two-rooted maxillary central incisor with a periapical radiolucent lesion. A 17-yr-old female patient was referred for dental consultation after a motorcycle accident. The maxillary left central incisor had a bifurcated root that was confirmed by radiographs taken at different angles. Nonsurgical endodontic therapy was performed. At the 1 yr recall examination, the tooth was asymptomatic and the radiograph showed that the periapical radiolucent lesion had healed.
Management of the Perforations Due to Miniplate Application
Hümeyra Arikan, DDS, PhD, Figen Kaptan, DDS, PhD, Baybora Kayahan, DDS, PhD, Faruk Haznedaroğlu, DDS, PhD
Microdimensioned osteosynthesis using miniplates has been common practice in maxillofacial surgery. However, tooth injury during the application of the miniplates have been reported in few papers. In this case, a 32-yr-old female patient, whose two teeth were necrosed because of the perforation during screw insertion was presented. The reason of the perforations during the rigid internal fixation was the lack of radiographic assessment because of the pregnancy. Maxillary right first premolar and maxillary left canine were perforated and necrosed because of the screw insertion. The necrosed teeth were detected 1 yr after the rigid internal fixation. The root canals of nonvital teeth were filed using step-down approach. Cold lateral condensation of gutta-percha was used to fill the canals. Six-month recall visits were scheduled and there was no problem after 2-yr follow-up period.