Endodontic Management of a Fused Mandibular Second Molar and Paramolar with the Aid of Spiral Computed Tomography: A Case Report
Suma Ballal, MDS, Gurmeet Singh Sachdeva, BDS, Deivanayagam Kandaswamy, MDS
Fusion and gemination are developmental anomalies of the dental hard tissues that might require endodontic and surgical treatment for functional, orthodontic, or esthetic reasons. In this article, we report a rare case of successful endodontic management of unilateral fused mandibular second molar with a paramolar. The rarity with which this entity appears, along with its complex characteristics, often makes it difficult to diagnose and treat. The use of high-end diagnostic imaging modalities such as spiral computed tomography can help the clinician in making a confirmatory diagnosis and determining the treatment plan before undertaking the actual treatment. This case report highlights the usefulness of spiral computed tomography in accurate diagnosis and endodontic management of these unusual cases.
Does Electropolishing Improve the Low-cycle Fatigue Behavior of a Nickel–Titanium Rotary Instrument in Hypochlorite?
Gary S.P. Cheung, MDS, MSc, PhD, Ya Shen, BDS, PhD, Brian W. Darvell, PhD, DSc
The purpose of this study was to compare the low-cycle fatigue (LCF) behavior of electropolished and nonelectropolished nickel-titanium (NiTi) instruments of the same design in hypochlorite. Forty-five electropolished and 62 nonelectropolished NiTi engine files were subjected to rotational bending at various curvatures in 1.2% hypochlorite solution. Number of revolutions to failure, crack-initiation sites, extent of slow crack extension into the fracture cross-section, and surface-strain amplitude were noted. A linear relationship was found between LCF life and surface-strain amplitude for both groups, with no discernible difference between the two (p > 0.05). No electropolished instrument showed more than one crack origin, significantly fewer than for the nonelectropolished instruments (p < 0.05). The square root of crack extension and strain amplitude were inversely related. Although surface smoothness is enhanced by electropolishing, this did not protect the instrument from LCF failure.
Effect of Selected Accelerants on the Physical Properties of Mineral Trioxide Aggregate and Portland Cement
Kenneth B. Wiltbank, DMD, Scott A. Schwartz, DDS, William G. Schindler, DDS, MS
To decrease setting time by a clinically significant amount, classic Portland cement accelerators (calcium chloride, calcium nitrite/nitrate, and calcium formate) were added to gray and white mineral trioxide aggregate (MTA) (GMTA, WMTA) as well as to Portland cement (PC). Time to initially set was measured, as well as dimensional stability, temperature during set, and pH. The data were analyzed by one-way analysis of variance and Bonferroni multiple comparison test. It was found that all 3 accelerators significantly accelerated the set of GMTA and PC; only calcium chloride and calcium formate significantly accelerated WMTA. Dimensional stability was not significantly different between control and experimental groups. A statistically significant increase in temperature was observed in one group, but it was considered insignificant clinically (less than 3°C). There were seemingly minor but statistically significant differences in pH between groups set with calcium nitrite/nitrate and calcium formate. The results indicate that GMTA, WMTA, and PC mixed with these accelerators merit further study including evaluation of biocompatibility and sealing ability.
CD44 Presence in Inflamed Pulp Tissue
Gabriela Viviana Pisterna, DDS, PhD, Martha Siragusa, DDS, PhD
Inflammation of pulp tissue appears as a consequence of caries progression. Its main characteristic is inflamed infiltrate whose cells contain lymphocytes. CD44 is a widely expressed adhesion molecule present in several body cells such as leukocytes and parenchymatous cells, including endothelial cells, epithelial cells, and unstriated muscle cells. It interacts with hyaluronic acid, collagen, laminin, and fibronectin, and there are data that indicate an important role in the migration of leukocytes from the bloodstream toward inflammation areas. This project, which applied the immunologic assay method of agglutination inhibition of the CD44-hyaluronate system, evaluated the presence of CD44 in inflamed pulp tissue in both asymptomatic and symptomatic processes, as well as in healthy pulp tissue. The results demonstrated significant differences between both groups of pulp inflammatory processes with strong presence of the receptor. Moreover, healthy pulp had low to nondetectable levels of CD44. These results suggest that the expression of the CD44 molecule is higher during the initiation or maintenance of inflammatory processes.
Expression of Toll-like Receptor 2 and 4 in Dental Pulp
Noriko Mutoh, DDS, Nobuyuki Tani-Ishii, DDS, PhD, Keiichi Tsukinoki, DDS, PhD, Keiko Chieda, DDS, Kiyoko Watanabe, PhD
Toll-like receptors (TLRs) are important factors in innate immune responses because they mediate signals from bacterial cell wall components during inflammatory reactions. However, the role of TLR in dental pulp, which is bounded by hard tissues, is little understood. The present study investigated the expression of TLR-2 and TLR-4 in experimentally inflamed pulp by quantitative real-time polymerase chain reaction and immunohistochemistry. Total RNA isolated from pulp tissue from 0 to 72 hours after bacterial dentinal infection. The TLR-2 messenger RNA (mRNA) level was 30-fold higher than the TLR-4 mRNA level at 9 hours. The TLR-2 mRNA level in pulp began to increase by 3 hours after bacterial infection, reaching a maximum level after 9 hours and gradually decreasing from 9 to 72 hours. Numerous TLR-2– and CD64-positive cells detected on macrophage and dendritic-like cells, TLR-4–positive cells detected a little in the pulp at 9 hours. These results suggest that TLR-2 may be mainly regulated during the early stage of pulp inflammation triggered by bacterial infection.
Iontophoresis Significantly Increases the Trans-dentinal Delivery of Osteoprotegerin, Alendronate, and Calcitonin
James A. Kitchens, DDS, Scott A. Schwartz, DDS, William G. Schindler, DDS, MS, Kenneth M. Hargreaves, DDS, PhD
The purpose of this study was to evaluate the delivery of alendronate, calcitonin, and osteoprotegerin (OPG) through human dentin by both diffusion and iontophoresis for the potential treatment of invasive cervical resorption. Radiolabeled alendronate, calcitonin, and OPG were added to the top of a split chamber device that contained 1-mm thick dentin disks devoid of a smear layer. Transdentinal movement of medicaments by either random diffusion or application of an iontophoretic current was measured by analysis of gamma emission of effluent fractions. In addition, calcitonin delivery was evaluated at differing magnitudes of current (0–4 mA) by using the aforementioned chamber. Diffusion of all 3 medicaments was minimal. In contrast, the application of a 3-mA iontophoretic gradient significantly increased delivery for all 3 compounds at 10-, 20-, and 30-minute intervals. In addition, a linear increase in permeability was seen for calcitonin as milliamperes were increased from 0 to 4 (r = 0.947), with more than a 100-fold increase in delivery observed with iontophoresis. Delivery of the tested medicaments by using iontophoresis might prove to be a useful technique for treatment of invasive cervical resorption.
Formation of Dentin-like Particles in Dentin Defects above Exposed Pulp by Controlled Release of Fibroblast Growth Factor 2 from Gelatin Hydrogels
Naoki Kikuchi, DDS, Chiaki Kitamura, DDS, PhD, Takahiko Morotomi, DDS, PhD, Yoshio Inuyama, DDS, Hirotaka Ishimatsu, DDS, Yashuhiko Tabata, PhD, DMedSci, DPharm, Tatsuji Nishihara, DDS, PhD, Masamichi Terashita, DDS, PhD
The induction of dentin formation on exposed dental pulp is a major challenge in research on the regeneration of the dentin-pulp complex. We examined the effects of fibroblast growth factor 2 (FGF2), which was delivered in either a collagen sponge (noncontrolled release) or incorporated into gelatin hydrogels (controlled release), on the formation of dentin in exposed rat molar pulps. During the early phase of pulp wound healing, pulp cell proliferation and invasion of vessels into dentin defects above exposed pulp were induced in both groups. In the late phase, the induction of dentin formation was distinctly different between the 2 types of FGF2 release. The noncontrolled release of free FGF2 from collagen sponge induced excessive reparative dentin formation in the residual dental pulp, although dentin defects were not noted. In contrast, controlled release of FGF2 from gelatin hydrogels induced the formation of dentin-like particles with dentin defects above exposed pulp. These results suggest the possibility of a novel therapeutic approach for dentin-pulp complex by controlled release of bioactive FGF2.
Reaction of the Lateral Periodontium of Dogs’ Teeth to Contaminated and Noncontaminated Perforations Filled with Mineral Trioxide Aggregate
Roberto Holland, DDS, MSc, PhD, Luciana Bisco Ferreira, DDS, MSc, Valdir de Souza, DDS, MSc, PhD, José Arlindo Otoboni Filho, DDS, MSc, Sueli Satomi Murata, DDS, MSc, PhD, Eloi Dezan Jr., DDS, MSc, PhD
It has been shown that the mineral trioxide aggregate (MTA) used to seal lateral/furcal perforations stimulates the deposition of newly formed cementum. Nevertheless, when the site of the perforation is contaminated, the healing process might occur under less favorable conditions. This study evaluated the repair healing process of noncontaminated and contaminated lateral perforations filled with MTA and the effect of previously filling the contaminated perforations with a bactericidal agent. Thirty lateral root perforations were prepared in endodontically treated dog’s teeth, thus forming 3 groups with 10 specimens each. In group 1 the perforations were immediately sealed with MTA. In group 2 the perforations were left open for 7 days and thereafter sealed with MTA. In group 3 the perforations were left open for 7 days, filled temporarily with a calcium hydroxide–based paste for 14 days, and then sealed with MTA. The animals were killed after 90 days, and the pieces were prepared for histomorphologic and histomicrobiologic evaluations. The statistical analysis showed that group 1 had significantly better repair than groups 2 (P < .05) and 3 (P < .05), which validates the superior results obtained when MTA was immediately used to seal root perforations. Groups 2 and 3 had statistically similar repair to each other (P > .05). There were a larger number of cases of complete or partial biologic seal in group 1 compared with the contaminated groups. It might be concluded that the lateral root perforations sealed with MTA after contamination presented worse repair than the noncontaminated, immediately sealed perforations. The temporary filling with a bactericidal agent (calcium hydroxide–based paste) did not improve the repair of perforations exposed to contamination, and the contaminated groups presented similar results to each other.
TRPM8 Axonal Expression is Decreased in Painful Human Teeth with Irreversible Pulpitis and Cold Hyperalgesia
Lisa T. Alvarado, DDS, Griffin M. Perry, BS, Kenneth M. Hargreaves, DDS, PhD, Michael A. Henry, DDS, PhD
Pulpitis pain might be triggered by a cold stimulus, yet the cellular mechanisms responsible for this phenomenon are largely unknown. One possible mechanism involves the direct activation of cold-responsive thermoreceptors. The purpose of this study was to evaluate the possible role of the TRPM8 thermoreceptor in cold-mediated noxious pulpal pain mechanisms by comparing expression patterns in pulpal nerves from healthy control molars to cold-sensitive painful molars with irreversible pulpitis. Samples were identically processed with the indirect immunofluorescence method, and images were obtained with confocal microscopy. The immunofluorescence intensity and area occupied by TRPM8 within N52/PGP9.5-identified nerve fibers were quantified. Results showed that relative to normal samples, TRPM8 nerve area expression was significantly less in the cold-sensitive painful samples (34.9% vs 8%, P <0.03), but with no significant difference in immunofluorescence intensity between the 2 groups. These results suggest that TRPM8 is most likely not involved in cold-mediated noxious pulpal pain mechanisms.
Expression of Nav1.9 Channels in Human Dental Pulp and Trigeminal Ganglion
Jason E. Wells, PhD, Val Bingham, DDS, MS, Kevin C. Rowland, PhD, John Hatton, DMD
There is a higher incidence of local anesthetic failure in endodontic patients experiencing pulpal hyperalgesia. Up-regulation of Nav1.9, a voltage-gated sodium channel isoform, might play a key role in local anesthetic failure because Nav1.9 channels increase neuronal excitability and have low sensitivity to blockade by local anesthetics. Immunocytochemistry was used to examine Nav1.9 channel expression in axons of symptomatic (painful) versus asymptomatic human dental pulp and to determine Nav1.9 expression levels in neuronal somata of the human trigeminal ganglion. Nav1.9 channel immunoreactivity on pulpal axons was significantly increased in painful teeth. Nav1.9 channels were expressed in membranes and cytoplasm of human trigeminal ganglion neurons, with the highest expression in small neuronal somata. Nav1.9 expression in the trigeminal ganglion coupled with increased expression in symptomatic pulp might contribute to hypersensitivity of inflamed pulps and local anesthetic failure. Furthermore, the present study suggests that Nav1.9 channels are potential targets for novel anesthetics.
Antimicrobial Effect of Triclosan and Triclosan with Gantrez on Five Common Endodontic Pathogens
William J. Nudera, DDS, MS, Mohamed I. Fayad, BDS, MS, PhD, Bradford R. Johnson, DDS, MHPE, Min Zhu, DDS, PhD, Christopher S. Wenckus, DDS, Ellen A. BeGole, PhD, Christine D. Wu, MS, PhD
Microbial control of the root canal system is one of the key objectives of root canal therapy. Triclosan is a widely accepted broad spectrum antimicrobial agent proven to be effective against many gram-positive and gram-negative bacteria. Triclosan acts by blocking bacterial fatty acid biosynthesis. The addition of Gantrez copolymer has been shown to enhance the antimicrobial activity of triclosan. The purpose of this study was to determine the minimum inhibitory and bactericidal concentrations of triclosan and triclosan with Gantrez against Prevotella intermedia, Fusobacterium nucleatum, Actinomyces naeslundii, Porphyromonas gingivalis, and Enterococcus faecalis. The minimum inhibitory concentration (MIC) of both test solutions was determined for each of the 5 microorganisms by using microtiter serial dilutions. Samples were streaked on 5% sheep blood agar plates and placed in an anaerobic incubator to determine the minimum bactericidal concentration (MBC). The MBC of triclosan ranged from 12–94 μg/mL. The MBC of triclosan with Gantrez ranged from <0.3–10.4 μg/mL. The addition of Gantrez enhanced the bactericidal activity of triclosan. Both triclosan and triclosan with Gantrez demonstrated bactericidal activity against the 5 specific endodontic pathogens.
Fracture Resistance of Electropolished Rotary Nickel–Titanium Endodontic Instruments
Margot E. Anderson, BSc, BDSc, John W.H. Price, MEngSci, PhD, Peter Parashos, MDSc, PhD
The purpose of this study was to investigate the effect of electropolishing on cyclic flexural fatigue and torsional strength of rotary nickel-titanium endodontic instruments. Electropolished and nonelectropolished ISO size 30 (0.04 taper) EndoWave (J Morita Corporation, Osaka, Japan), ProFile (Dentsply Maillefer, Ballaigues, Switzerland), and RaCe (FKG, La-Chaux De Fonds, Switzerland) instruments from the same manufacturing batches were investigated. The number of rotations to fracture and torque at fracture were determined and compared among the instruments tested. Instruments were viewed under a scanning electron microscope (SEM) to assess the degree and quality of electropolishing. Overall, electropolished instruments performed significantly better than nonelectropolished instruments in cyclic fatigue testing and, to a lesser extent, in static torsional loading. When viewing electropolished instruments with the SEM, milling grooves, cracks, pits, and areas of metal rollover were observed, although they were more evident in the nonelectropolished instruments. Electropolishing may have beneficial effects in prolonging the fatigue life of rotary NiTi endodontic instruments. The benefits of electropolishing are likely to be caused by a reduction in surface irregularities that serve as points for stress concentration and crack initiation.
Influence of Injection Speed on the Effectiveness of Incisive/Mental Nerve Block: A Randomized, Controlled, Double-blind Study in Adult Volunteers
John Martin Whitworth, PhD, Mohammad Dib Kanaa, MPhil, Ian Porter Corbett, PhD, John Gerald Meechan, PhD
This randomized, double-blind trial tested the null hypothesis that speed of deposition has no influence on the injection discomfort, efficacy, distribution, and duration of pulp anesthesia after incisive/mental nerve block in adult volunteers. Thirty-eight subjects received incisive/mental nerve blocks of 2.0 mL lidocaine with 1:80,000 epinephrine slowly over 60 seconds or rapidly over 15 seconds at least 1 week apart. Pulp anesthesia was assessed electronically to 45 minutes after injection. Injection discomfort was self-recorded on visual analogue scales. Overall, 48.7% of volunteers developed pulp anesthesia in first molars, 81.8% in bicuspids, and 38.5% in lateral incisors. The mean duration of pulp anesthesia was 19.1 minutes for first molars, 28.5 minutes for bicuspids, and 19.0 minutes for lateral incisors. Speed of injection had no significant influence on anesthetic success or duration of anesthesia for individual teeth. Slow injection was significantly more comfortable than rapid injection (P < .001). The null hypothesis was supported, although slow injection was more comfortable.
Alternative Adhesive Strategies to Optimize Bonding to Radicular Dentin
Serge Bouillaguet, DMD, PhD, Bruno Bertossa, DMD, Ivo Krejci, DMD, PhD, John C. Wataha, DMD, PhD, Franklin R. Tay, DMD, PhD, David H. Pashley, DMD, PhD
This study tested the hypothesis that bond strengths of filling materials to radicular dentin might be optimized by using an indirect dentin bonding procedure with an acrylic core material. Roots of human teeth were endodontically prepared and obturated with EndoREZ, Epiphany, or the bonding of an acrylic point with SE Bond by using a direct or an indirect bonding technique. Bond strengths of endodontic sealers to radicular dentin were measured with a thin slice push-out test. Push-out strengths of EndoREZ and Epiphany to radicular dentin were less than 5 megapascals (MPa). The direct bonding technique with acrylic points and the self-etching adhesive had push-out strengths of 10 MPa, increasing to 18 MPa with the indirect technique. The use of the indirect bonding protocol with an acrylic point to compensate for polymerization stresses appears to be a viable means for optimizing bond strengths of endodontic filling materials to radicular dentin.
Ledge Formation: Review of a Great Challenge in Endodontics
Hamid Jafarzadeh, DDS, MSc, Paul V. Abbott, BDSc, MDS, FRACDS (Endo)
Failure to grasp the rationale behind cleaning and shaping concepts can increase the occurrence of needless complications, such as ledges. A ledge is created when the working length can no longer be negotiated and the original pathway of the canal has been lost. Extension of the access cavity to provide unobstructed access to the root canals, precurving and not forcing instruments, using NiTi files, using passive step-back and balanced force techniques, and instrumenting the canal to its full length will all help to prevent ledge formation. Initial negotiation and bypassing the ledge can be achieved using a small file with a distinct curve at the tip, whereas a slight rotation motion of the file combined with a ″picking″ motion can often help advance the instrument. A review of the literature and a discussion of the options for prevention, recognition and managing the ledge are presented.
Effects of Lipopolysaccharide on Newly Established Rat Dental Pulp–derived Cell Line with Odontoblastic Properties
Kimiko Nomiyama, DDS, Chiaki Kitamura, DDS, PhD, Toshiyuki Tsujisawa, DDS, PhD, Masato Nagayoshi, DDS, PhD, Takahiko Morotomi, DDS, PhD, Masmichi Terashita, DDS, PhD, Tatsuji Nishihara, DDS, PhD
To clarify mechanisms of pulp wound healing and regeneration, it is important to establish continuous odontoblast-lineage cell lines. In this study, we established the proliferating pulp progenitor cell lines from dental papilla cells of rat incisor. These cell lines showed high levels of alkaline phosphatase (ALP) activity, expression of Runx2 and dentin sialophosphoprotein (DSPP), and extracellular formation of mineralized nodules. By using the cell line with high expression level of DSPP and the prominent mineral deposition, we examined whether bacterial lipopolysaccharide (LPS) had effects on its odontoblastic properties and found that ALP activity, expression of DSPP and Runx2, and the formation of mineralized nodules were suppressed in LPS dose-dependent manner. These results indicate that our established pulp progenitor cell line exhibits odontoblastic properties, which were suppressed by LPS, suggesting that gram-negative bacterial infection might downregulate the odontoblast function.
Chemical Modification of ProRoot MTA to Improve Handling Characteristics and Decrease Setting Time
Benjamin S. Ber, DDS, MS, John F. Hatton, DMD, Gregory P. Stewart, PhD
Mineral trioxide aggregate (MTA) fulfills many of the ideal properties of a root-end filling material. However, the composition of this material often makes MTA difficult to use, a direct result of its granular consistency, slow setting time, and initial looseness. Additives used by the Portland cement (PC) industry to increase PC’s plasticity and decrease its setting time were added first to PC and then to gray MTA in an attempt to improve MTA’s handling characteristics, with the combination providing the best handling characteristics tested for its effect on compressive strength (for changes in the original material’s properties) and decrease in setting time. An admix of 1% methylcellulose and 2% calcium chloride resulted in a mix of chemically modified MTA that, when compared with unmodified MTA, (1) handled similarly to a reinforced zinc oxide–eugenol cement, (2) gave an approximately equal compressive strength, and (3) set one third faster (57 ± 3 minutes).
An Investigation of the Heat Induced during Ultrasonic Post Removal
Christopher A. Ettrich, DDS, MSD, Paul E. Labossière, MS, PhD, David L. Pitts, DDS, MSD, James D. Johnson, DDS, MS
The purpose of this study was to investigate the potential for temperature increase along the external root surface during ultrasonic post removal in a simulated clinical environment. Thirty-seven extracted teeth were decoronated, instrumented, and then obturated with gutta-percha and sealer. Post spaces were prepared, followed by cementation of stainless steel posts. A simulated clinical environment was created by using a polymethylmethacrylate sheet with holes custom fitted for the extracted teeth and then suspended over a heated water bath. Two thermocouples were attached at 6 and 12 mm from the top of the post along the external root surface. Teeth were divided into 3 test groups, no coolant, air-cooled, and water-cooled. Temperature changes were recorded by using a Vishay 5000 Strain Smart system. Results demonstrated that a significant difference existed in the average heat rates between the upper and lower thermocouples for no coolant and water-cooled groups at the medium setting and the air-cooled group at the high setting. The average heat rates were significantly different between the 2 thermocouples for all 3 groups when comparing the 2 ultrasonic power settings. Results indicated that the average heat rate was less for the water-cooled group when using a medium power setting.
Clinical and Radiographic Evaluation of One- and Two-visit Endodontic Treatment of Asymptomatic Necrotic Teeth with Apical Periodontitis: A Randomized Clinical Trial
Anders Molander, DDS, PhD, Johan Warfvinge, DDS, PhD, Claes Reit, DDS, PhD, Thomas Kvist, DDS, PhD
The present investigation recorded the 2-year clinical and radiographic outcome of one- and two visit endodontic treatment and studied the significance of the bacteriologic sampling results on the outcome. A randomization procedure allocated 53 teeth to one-visit treatment and 48 teeth to two-visit treatment. At the end of the study period, 32 teeth (65%) in the one-visit group and 30 teeth (75%) in the two-visit group were classified as healed. The statistical analysis of the healing results did not show any significant difference between the groups (p=0.75). Forty-nine (80%) of the 61 teeth that were obturated after a negative micobiologic sample were classified as healed. Teeth sealed after positive samples healed in 44%. The present study gave evidence that similar healing results might be obtained through one- and two-visit antimicrobial treatment.
Eugenol Modulates Cyclooxygenase-2 Expression Through the Activation of Nuclear Factor Kappa B in Human Osteoblasts
Ya-Yun Lee, DDS, Shue-Fen Yang, DDS, MS, Weng-Hang Ho, BS, Yuan-Ho Lee, PhD, Shan-Ling Hung, PhD
Because eugenol is a major component of root canal sealers and retrograde filling materials, its effects on periapical bone healing are therefore of concern. In this study, the effects of eugenol on the activation of nuclear factor kappa B (NF-κB) and the expression of cyclooxygenase-2 (COX-2) in human osteoblasts were investigated. The results showed that eugenol activated the nuclear translocation of NF-κB. In addition, COX-2 protein expression in osteoblasts was induced by eugenol in a dose-dependent manner. Furthermore, the eugenol-modulated COX-2 expression was inhibited by an NF-κB inhibitor, N-acetylcysteine. Taken together, eugenol might induce COX-2 expression through the activation of NF-κB in human osteoblasts. These results suggest that eugenol might be involved in periapical healing by impairing the functions of osteoblasts.
Experimental Model: Dye Penetration of Extensive Interim Restorations Used during Endodontic Treatment while under Load in a Multiple Axis Chewing Simulator
Arna-Lee Jensen, BDSc (Hons), MDSc, Paul V. Abbott, BDSc, MDS, FRACDS (Endo)
The purpose of this study was to design an experimental model that allowed extensive endodontic interim restorations to be tested for dye penetration while under simulated masticatory load. Extracted premolar teeth had standardized mesio-occluso-distal cavities prepared, and the root canals were instrumented. A cotton wool pellet was placed in the pulp chamber, and the cavities were restored with Cavit, IRM, Ketac-Fil Plus, Ketac-Silver, or composite resin (Z100). They were subjected to the equivalent of 3 months of clinical load while exposed to methylene blue dye. Results of this study could not support IRM as a suitable interim endodontic restorative material to use in extensive cavities. The dye penetration in the Ketac-Fil Plus and Ketac-Silver specimens was not predictable, and the results suggested Cavit and Z100 composite resin require further investigations as potentially useful materials for this purpose.
Prevalence of Three-rooted Mandibular First Molars among Taiwanese Individuals
Ming-Gene Tu, DDS, MSc, Chi-Cheng Tsai, DDS, PhD, Ming-Jia Jou, PhD, Wil-Lie Chen, PhD, Yu-Fang Chang, DDS, San-Yue Chen, DDS, PhD, Hui-Wen Cheng, DDS
The purpose of this study was to evaluate the prevalence of mandibular first molars featuring a distolingual root among a Taiwanese population. A total of 731 patients’ periapical radiographs were screened and examined to obtain 166 samples for this study. The gender, symmetry, and frequencies of occurrence of three-rooted mandibular first molars were recorded. The prevalence of three-rooted mandibular first molars was 21.09%. The bilateral incidence of a symmetrical distribution was 68.57%. There was a significantly greater incidence of three-rooted teeth on the right side of the mandible than on the left, but gender did not show a significant relationship with this variant prevalence. Clinicians should be aware of the high racial prevalence of the distolingual root in mandibular first molars among the Taiwanese (Chinese) population before initiating endodontic treatment.