Radiopacity of Endodontic Materials on Film and a Digital Sensor
Brian J. Rasimick, BS, Rinal P. Shah, BS, Barry Lee Musikant, DMD, Allan S. Deutsch, DMD
The purpose of this study was to compare the radiographic appearance of 12 endodontic materials as visualized on either Kodak Ultra-speed D speed film (Eastman Kodak Company, Rochester, NY) or a Gendex eHD digital sensor (Gendex Dental Systems, Milan, Italy). Ten discs of each material were radiographed alongside an aluminum alloy 1100 (Alcoa, Pittsburgh, PA) stepwedge that was used for reference. For every radiograph, the average grayscale value of the material was converted into absorbance notation and compared with that of the reference stepwedge in order to determine the equivalent radiopacity in terms of millimeters of Al 1100 per millimeter of material. Two-way repeated-measures analysis of variance testing detected significant differences with respect to imaging system, material, and the interaction of the two factors (p < 0.001). The difference in a material’s radiopacity as measured on the digital sensor compared with film was greater than 10% for 4 of the 12 materials and over 40% for InnoEndo (Heraus Kulzer, Armonk, NY). It was speculated that barium fillers cause this effect.
Effect of the Adhesive Application Mode and Fiber Post Translucency on the Push-out Bond Strength to Dentin
André Luís Faria e Silva, DDS, MS, Denise Sá Maia Casselli, DDS, PhD, Glaucia Maria Bovi Ambrosano, PhD, Luís Roberto Marcondes Martins, DDS, PhD
This study evaluated the effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin. Bovine roots were endodontically treated, and 10 roots were used for each adhesive application mode: PB (Prime&Bond 2.1), PB + SC (Self-cure activator), PB + SBM (Scotchbond Multi-purpose adhesive system), BB (Brush&Bond), BB + CAT (chemical catalyst), and BB + SBM. The translucent Light-Post and Aestheti-Post were cemented. The roots/cemented posts were transversally sectioned to originate three thirds (cervical, middle, and apical). The push-out test was performed, and the failure mode of fractured specimens was analyzed. There was no difference between the fiber posts. For PB and BB, the use of hydrophobic adhesive resin SBM increased post bond strength. The use of SC and CAT catalyst did not affect the push-out bond strength values. The apical third presented the lowest bond strengths.
Proroot Mineral Trioxide Aggregate Cement Used as a Retrograde Filling without Addition of Water: An In Vitro Evaluation of Its Microleakage
Gian Andrea Pelliccioni, MD, DDS, Carlo Paolo Vellani, DDS, Maria Rosaria A. Gatto, BS, Maria Giovanna Gandolfi, PhDCh, Claudio Marchetti, MD, DDS, Carlo Prati, MD, DDS, PhD
The aim of this in vitro study was to compare at different times the microleakage of roots filled with Proroot mineral trioxide aggregate (MTA) mixed with water as recommended by the manufacturer or filled only with powder without any previous hydration. Forty-four extracted single-rooted human teeth had their crown removed, and their roots were instrumented, filled with gutta-percha without cement, resected at 3 mm from the apex, and ultrasonically prepared with CK5 retrotips. The roots were randomly divided into 2 groups, group 1 (n = 20) and group 2 (n = 20) with 2 positive and 2 negative control roots. Teeth in group 1 were filled with white Proroot MTA prepared as suggested by the manufacturer, whereas in group 2, teeth were filled with white Proroot MTA by using only powder without any hydration. Microleakage of each root was measured at 24 hours and 1, 2, 4, and 12 weeks after filling with a fluid filtration device. No statistically significant difference (P > .05) in microleakage between groups 1 and 2 was detected at any time except the 1-week period. The lack of water addition during the preparation of the cement in this study did not affect the in vitro sealing ability of Proroot MTA.
In Vivo Antibacterial Efficacy of Ultrasound after Hand and Rotary Instrumentation in Human Mandibular Molars
Keith Carver, DMD, MS, John Nusstein, DDS, MS, Al Reader, DDS, MS, Mike Beck, DDS, MA
The purpose of this prospective, randomized, single-blind study was to compare the in vivo antibacterial efficacy of a hand/rotary technique versus a hand/rotary/ultrasound technique in mesial root canals of necrotic mandibular molars. The hand/rotary group consisted of 16 mesial roots prepared with a hand/rotary technique. The hand/rotary/ultrasound group consisted of 15 mesial roots prepared similarly, followed by 1 minute of ultrasonic irrigation per canal with an ultrasonic needle in a MiniEndo unit and 15 mL/canal of 6.0% sodium hypochlorite. Canals were sampled before and after instrumentation and after 1 minute of ultrasonic irrigation. Samples were incubated anaerobically on reduced blood agar for 7 days at 37°C, and colony-forming units (CFUs) were counted. The addition of 1 minute of ultrasonic irrigation resulted in significant (p = .0006) reduction in CFU count and positive cultures (p = .0047). Logistic regression analysis indicated the addition of ultrasonic irrigation was 7 times more likely to yield a negative culture.
Correlation of Bone Defect Dimensions with Healing Outcome One Year after Apical Surgery
Thomas von Arx, PD Dr med dent, Stefan Hänni, Dr med dent, Simon Storgård Jensen, DDS
This clinical study prospectively evaluated the healing outcome 1 year after apical surgery in relation to bony crypt dimensions measured intraoperatively. The study cohort included 183 teeth in an equal number of patients. For statistical analysis, results were dichotomized (healed versus non-healed cases). The overall success rate was 83% (healed cases). Healing outcome was not significantly related to the level and height of the facial bone plate. In contrast, a significant difference was found for the mean size of the bony crypt when healed cases (395 mm3) were compared with non-healed cases (554 mm3). In addition, healed cases had a significantly shorter mean distance (4.30 mm) from the facial bone surface to the root canal (horizontal access) compared with non-healed cases (5.13 mm). With logistic regression, however, the only parameter found to be significantly related to healing outcome was the length of the access window to the bony crypt.
Histological Assessment of Pulp Condition after Apical Vital Root Transection in One Root of Multirooted Teeth in Dogs: A Preliminary Study
Massoud Yaghmaiee, DDS, MS, Amir Saeed Yavari, DDS, Fatemeh Mashhadiabbas, DDS, MS, Afshin Bahrami, DVM§, Pupak Farnia, DVM§, Davoud Sharifi, DVM§, Jalaledin Ghanavi, MD, Behnan Eslami, DDS, MS
One of the most important aspects in surgery is the healing process after the periapical surgery. Past studies have shown occasional encounters with vital root resection and have noted varying degrees of pulpal response after root resection in periodontal disease. The purpose of this investigation was to observe the pulpal and periapical responses to intentional apical vital root transection in one root of multirooted teeth of German-Canadian dogs over a 6-month postoperative period. This is an experimental study performed on left maxillary and mandibular quadrants of four adult German-Canadian dogs after a 3- and 6-month period. Four teeth were assessed in each interval. One of the roots of multirooted teeth in the left quadrant of both maxillary and mandibular jaws was surgically transected. Tissue blocks were prepared by routine histological methods after 12 and 24 weeks after the surgery. The results showed a disruption of the normal pulpal architecture, with initial pulpal degeneration and subsequent early replacement by the periodontal ligament tissue after 24 weeks. Hypercementosis was seen around the apical portion of the root in all specimens. Pulpal regeneration was seen in the both upper and lower molars (p = 0.03). Resorption took place only in two specimens (p = 0.46). The inflammation in the 12th week was more than the 24th week. The pulp of multirooted teeth remains vital after transection of the apical part of the root in dogs. Longer follow-up periods are recommended because root canal therapy or extraction is indicated if resorption, necrosis, or ankylosis is seen.
Polymerase Chain Reaction of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia in Primary Endodontic Infections
Brenda P.F.A. Gomes, PhD, MSc, DDS, Francisco Montagner, DDS, Rogério Castilho Jacinto, PhD, MSc, DDS, Alexandre A. Zaia, PhD, MSc, DDS, Caio Cezar Randi Ferraz, PhD, MSc, DDS, Francisco J. Souza-Filho, PhD, MSc, DDS
The aim of this study was to investigate the correlation between endodontic clinical signs and symptoms and the presence of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia or their association by nested polymerase chain reaction assay. Microbial samples were taken from 50 cases with necrotic pulp tissues in primary infections. DNA was extracted from the samples, which were analyzed for the presence of three endodontic pathogens by using species-specific primers. P gingivalis, T denticola, and T forsythia were detected in 46%, 38%, and 22% of the symptomatic cases, respectively. The bacterial complex composed by T forsythia, P gingivalis, and T denticola was found in 14% of the cases with spontaneous pain, tenderness to percussion, swelling, and pain on palpation. The high prevalence of P gingivalis, T denticola, and T forsythia in the samples examined suggests that these bacteria are related to the etiology of symptomatic periradicular diseases.
Microporous, Demineralized Collagen Matrices in Intact Radicular Dentin Created by Commonly Used Calcium-depleting Endodontic Irrigants
Franklin R. Tay, BDSc (Hons), PhD, James L. Gutmann, DDS, David H. Pashley, DMD, PhD
The use of calcium-depleting solutions in restorative dentistry results in demineralization of intact coronal dentin beneath smear layers. Likewise, application of calcium-depleting irrigants as final rinses might create demineralized collagen matrices in intact radicular dentin after removal of root canal wall smear layers created during canal shaping. These unsupported collagen matrices collapse on desiccation and might be difficult to detect in scanning electron microscopy dehydration techniques traditionally used in endodontic research. Demineralized collagen matrices were identified, by using a hexamethyldisilazane dehydration protocol, on the surface of smear layer–depleted radicular dentin when NaOCl was used as initial rinse, followed by the use of 17% ethylenediaminetetraacetic acid or BioPure MTAD as the final rinse. Compaction of conventional root filling materials over a demineralized collagen matrix in instrumented dentin is analogous to performing the same procedure against the predentin collagen network in the uninstrumented parts of root canals. The potential consequences of this process are, however, unknown.
The Root and Root Canal Morphology of the Human Mandibular Second Premolar: A Literature Review
Blaine M. Cleghorn, DMD, MS, William H. Christie, DMD, MS, Cecilia C.S. Dong, DMD, BSc, MS
The objective was to review thoroughly the literature of the root and root canal morphology of the human mandibular second premolar and compare the results with the mandibular first premolar. Published studies cite the anatomy and morphology of the mandibular second premolar tooth for more than 7700 teeth. These studies were divided into anatomic studies reporting the number of roots, number of canals, and apical anatomy. Differences caused by gender and ethnicity have also been reported. Individual case reports of anomalies were included to demonstrate the extreme range of variation. Almost all of the teeth in the anatomic studies were single-rooted (99.6%). The incidence of 2 roots (0.3%) and 3 roots (0.1%) was extremely rare. Anatomic studies of the internal canal morphology found that a single canal was present in 91.0% of the teeth. A single apical foramen was found in 91.8% of the teeth. The incidence of more than 1 root (0.4%), more than 1 canal system (9.9%), and more than 1 foramen (8.2%) is lower than that of the mandibular first premolar tooth (2.0%, 24.2%, and 21.1%, respectively). However, the root and root canal morphology of the mandibular second premolar can be extremely complex and requires careful assessment.
Ultrasonic Vibration: Temperature Rise on External Root Surface during Broken Instrument Removal
Ahmed Abdel Rahman Hashem, BDS, MSc, PhD
The effect of 2 ultrasonic tips and power settings on temperature rise of external root surface was investigated during ultrasonic vibration of intracanal broken instruments. Thirty maxillary human central incisors had lingual coronal access. The apical 5 mm of size 40 K-files was separated at apical region. Two thermocouples connected to digital thermometer were attached to external root surface to measure temperature rise. Central incisors were divided into 3 equal groups: group 1 in which Satelec ET 40 ultrasonic tip at power 1 was used, group 2 in which ET 40 at power 5 was used, and group 3 in which CPR 5 ultrasonic tip at power 1 was used. Ultrasonic vibration without coolant was activated for 2 minutes, and temperature rise was recorded at 1 and 2 minutes. At 1 minute, CPR 5 and ET 40 at power 1 showed statistically significant less temperature rise. CPR 5 demonstrated lower temperature rise compared with ET 40 when used for 2 minutes. ET 40 showed less temperature at power 1 compared with power 5. Significant increase in temperature from 1 minute to 2 minutes was observed in all groups.
Enlarging Characteristics of Four Nickel-Titanium Rotary Instrument Systems under Standardized Conditions of Operator-related Variables
Özgür Uzun, DDS, PhD, Özgür Topuz, DDS, PhD, Cumhur Aydýn, DDS, PhD, Tayfun Alaçam, DDS, PhD⁎, Bülent Aslan, PhD
We aimed to describe a computer-controlled testing device and evaluate the amount of material removed by using 4 Ni-Ti systems in simulated root canals. Eighty resin blocks were used. Hero 642, Hero Shaper, ProFile, and ProTaper rotary instruments were used to prepare the canals. Operator-related variables were standardized with the aforementioned device. Preoperative/postoperative photographic images of canals were measured at 11 levels from the apical tip. Statistical analyses were done with one-way analysis of variance, Tukey honestly significant difference, and Bonferroni tests. Significantly more material was removed by the ProTaper at 9 levels, ProFile at 6, and Hero 642 at 2 levels (P < .05); no significant difference was determined at 5 levels. Our results showed that ProTaper and ProFile removed significantly more material than Hero 642 and Hero Shaper at different levels of the curved root canals under controlled conditions of operator-related variables.
Quantitative Evaluation of Debris Extruded Apically by Using ProTaper Universal Tulsa Rotary System in Endodontic Retreatment
Xiangya Huang, MS, Junqi Ling, PhD, Xi Wei, MS, MDS, Lisha Gu, MS
This study evaluated the amount of apical debris during endodontic retreatment by using the ProTaper Universal Tulsa rotary files. Forty-five extracted human anterior teeth were root filled before randomly assigned to 3 groups. In group A, gutta-percha was removed by using the ProTaper Universal Tulsa retreatment system, and canals were re-prepared with ProTaper rotary files. In group B, gutta-percha was removed by using Hedström files with chloroform, and canals were reshaped with ProTaper rotary files. In group C, the same method as that in group B was used for gutta-percha removal, and canals were reshaped with K-flex files. Apical debris was collected and compared among 3 groups. Although all retreatment techniques resulted in apical extrusion, the ProTaper Universal Tulsa rotary technique in group A produced significantly less amount of apical extrusion than other 2 methods (P < .001). The ProTaper Universal Tulsa rotary technique proves to be a viable alternative method in endodontic retreatment.
Penetration of 38% Hydrogen Peroxide into the Pulp Chamber in Bovine and Human Teeth Submitted to Office Bleach Technique
Samira Esteves Afonso Camargo, MSc, Marcia Carneiro Valera, MSc, PhD, Carlos Henrique Ribeiro Camargo, MSc, PhD, Maria Nadir Gasparoto Mancini, MSc, PhD, Marcia Maciel Menezes, MSc, PhD
This study evaluated the pulp chamber penetration of peroxide bleaching agent in human and bovine teeth after office bleach technique. All the teeth were sectioned 3 mm apical of the cement-enamel junction and were divided into 2 groups, A (70 third human molars) and B (70 bovine lateral incisors), that were subdivided into A1 and B1 restored by using composite resin, A2 and B2 by using glass ionomer cement, and A3 and B3 by using resin-modified glass ionomer cement; A4, A5, B4, and B5 were not restored. Acetate buffer was placed in the pulp chamber, and the bleaching agent was applied for 40 minutes as follows: A1–A4 and B1–B4, 38% hydrogen peroxide exposure and A5 and B5, immersion into distilled water. The buffer solution was transferred to a glass tube in which leuco crystal violet and horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to analysis of variance and Dunnett, Kruskal-Wallis, and Tukey tests (5%). A higher level of hydrogen peroxide penetrated into the pulp chamber in resin-modified glass ionomer cements in bovine (0.79 ± 0.61 μg) and human (2.27 ± 0.41 μg) groups. The bleaching agent penetration into the pulp chamber was higher in human teeth for any experimental situation. The penetration of the hydrogen peroxide depends on restorative materials, and under the conditions of this study human teeth are more susceptible to penetration of bleaching agent into the pulp chamber than bovine teeth.
Solubility and Dimensional Change after Setting of Root Canal Sealers: A Proposal for Smaller Dimensions of Test Samples
Jacy R. Carvalho-Junior, DDS, PhD, Lourenço Correr-Sobrinho, DDS, PhD, Américo B. Correr, DDS, Mário A.C. Sinhoreti, DDS, PhD, Simonides Consani, DDS, PhD, Manoel D. Sousa-Neto, DDS, PhD
This study proposed smaller dimensions for samples used in solubility and dimensional change tests of root filling materials on the basis of American National Standard Institute/American Dental Association (ANSI/ADA) Specification No. 57. The volume, mass, and density of the test samples were determined, and 6 different samples of smaller dimensions were proposed for each test. Endofill and AH Plus sealers were used in the tests. For the solubility test, 2 samples were weighted, stored in distilled and dionized water for 24 hours, dried, and weighed again. Solubility was calculated by using samples’ weight loss (%). For dimensional change analysis, the samples’ heights were measured before and after immersion in dionized water for 30 days. For both tests, correlation between data of the different groups was observed. Kruskal-Wallis test showed that Endofill sealer presented higher solubility values than AH Plus (P < .05). The Endofill sealer presented 0.56% of shrinkage and AH Plus 0.62% expansion. Smaller dimensions for test samples used in solubility and dimensional change tests are a viable alternative, decreasing the amount of filling material necessary for executing these tests.
A Prospective, Randomized, Double-blind Comparison of Bupivacaine and Lidocaine for Maxillary Infiltrations
Renie Gross, DDS, MS, Melissa McCartney, DDS, MS, Al Reader, DDS, MS, Mike Beck, DDS, MA
The purpose of this prospective, randomized, double-blind study was to evaluate the anesthetic efficacy of 1.8 mL 0.5% bupivacaine with 1:200,000 epinephrine and 1.8 mL of 2% lidocaine with 1:100,000 epinephrine in maxillary lateral incisors and first molars. Sixty-five subjects randomly received, in a double-blind manner, two infiltrations at two separate appointments, in a crossover design. The injections consisted of maxillary lateral incisor and first molar infiltrations of 1.8 mL 0.5% bupivacaine with 1:200,000 epinephrine and 1.8 mL 2% lidocaine with 1:100,000 epinephrine. In maxillary lateral incisors, bupivacaine exhibited a significantly lower anesthetic success rate (obtaining two consecutive 80 readings with the pulp tester within 10 minutes) of 78% when compared with a 97% success rate with lidocaine. In maxillary first molars, bupivacaine’s onset of pulpal anesthesia (7.7 minutes) was significantly slower than lidocaine (4.3 minutes). Bupivacaine had a lower success rate than lidocaine (64% versus 82%) but there was no significant difference between the two solutions. Neither solution provided pulpal anesthesia for 1 hour.
Different Roles of Dexamethasone on Transforming Growth Factor-β1–induced Fibronectin and Nerve Growth Factor Expression in Dental Pulp Cells
Sirivimol Srisawasdi, DDS, MS, PhD, Prasit Pavasant, DDS, PhD
During pulp injury, it has been hypothesized that transforming growth factor-β1 (TGF-β1) is released from dentin into pulp tissue and promotes pulp tissue healing. Dexamethasone is a glucocorticoid that has been used to treat pulp injury and shown to induce differentiation of hard tissue forming cells. However, the interaction between dexamethasone and TGF-β1 is still unknown. This study aimed to examine the effects of dexamethasone on human pulp cells in the presence of TGF-β1. TGF-β1 increased expression and synthesis of both fibronectin and nerve growth factor (NGF), whereas dexamethasone stimulated fibronectin synthesis but inhibited NGF expression. The application of both TGF-β1 and dexamethasone resulted in an additional effect on fibronectin; however, dexamethasone inhibited the TGF-β1-induced NGF expression. Dexamethasone promotes fibronectin synthesis and suppresses NGF secretion, suggesting that this reagent could be used clinically to reduce pain and promote dental pulp tissue healing.
Dilaceration: Review of an Endodontic Challenge
Hamid Jafarzadeh, DDS, MSc, Paul V. Abbott, BDSc, MDS, FRACDS (Endo)
Dilaceration is the result of a developmental anomaly in which there has been an abrupt change in the axial inclination between the crown and the root of a tooth, but the criteria in the literature for recognizing root dilaceration vary. Two possible causes of dilaceration are trauma and developmental disturbances, and it has also been proposed that it might be associated with some developmental syndromes. Dilaceration can be seen in both the permanent and deciduous dentitions, and it is more commonly found in posterior teeth and in the maxilla. Periapical radiographs are the most appropriate way to diagnose the presence of root dilacerations. Diagnosis, endodontic access cavity preparation, root canal preparation and filling, and other related treatments might be complicated by the presence of a dilaceration. A review of the literature and a discussion of the options for managing this condition are presented.
Solubility of Root-end–Filling Materials: A Comparative Study
Claudio Poggio, DMD, Marco Lombardini, DDS, PhD, Conti Alessandro, DDS, Rindi Simonetta
This study tested solubility of 3 root-end filling materials (IRM, Pro Root, and Superseal) and an endodontic sealer (Argoseal) used as positive control. The test was performed according to the International Standards Organization 6876 standard and the American Dental Association specification #30. Six specimens of each material were prepared and immersed in water. Solubility was determined after 24 hours and 2 months and analyzed statistically with a one-way analysis of variance test. All retrograde filling materials were of low solubility. Under the conditions of the present study, IRM, Superseal, and Pro Root are virtually insoluble; this is an adequate physical property for use as root-end filling materials.
Endodontic Applications of Cone-Beam Volumetric Tomography
Taylor P. Cotton, DDS, Todd M. Geisler, DDS, David T. Holden, DMD, Scott A. Schwartz, DDS, William G. Schindler, DDS, MS
The ability to assess an area of interest in 3 dimensions might benefit both novice and experienced clinicians alike. High-resolution limited cone-beam volumetric tomography (CBVT) has been designed for dental applications. As opposed to sliced-image data of conventional computed tomography (CT) imaging, CBVT captures a cylindrical volume of data in one acquisition and thus offers distinct advantages over conventional medical CT. These advantages include increased accuracy, higher resolution, scan-time reduction, and dose reduction. Specific endodontic applications of CBVT are being identified as the technology becomes more prevalent. CBVT has great potential to become a valuable tool in the modern endodontic practice. The objectives of this article are to briefly review cone-beam technology and its advantages over medical CT and conventional radiography, to illustrate current and future clinical applications of cone-beam technology in endodontic practice, and to discuss medicolegal considerations pertaining to the acquisition and interpretation of 3-dimensional data.
Obturation of Root Canal System Treated by Cr, Er: YSGG Laser Irradiation
Claudio Herdy Varella, DDS, MS, Roberta Pileggi, DDS, MS
The purpose of this study was to evaluate the number of canals and isthmuses obturated after Cr, Er: YSGG laser treatment. Fifty-two canals were instrumented to a size 40 Profile 0.06 file combined with RC-Prep and sodium hypochlorite, or sterile water. The teeth were divided into 3 groups: (I) canals were flooded with 17% ethylenediaminetetraacetic acid for 3 minutes, (II) canals treated with the laser for 40 seconds, and (III) received no further treatment. Obturation was done with System B and Obtura III and AH Plus sealer. The specimens were rendered transparent and evaluated for the number of canals/isthmuses obturated. The data were analyzed by Kruskal-Wallis test. The means ± standard deviations for the groups were 17% ethylenediaminetetraacetic acid (1.14 ± 0.8), laser (2.14 ± 0.7), and control (0.4 ± 0.8). Under the conditions of this study, Cr, Er: YSGG treatment resulted in a statistically significant greater number of canals/isthmuses obturated (P < .001).
The Effect of Estrogen Deficiency on Receptor Activator of Nuclear Factor Kappa B Ligand and Osteoprotegerin Synthesis in Periapical Lesions Induced in Rats
Xiaolei Zhang, DDS, PhD, Bin Peng, DDS, PhD, Mingwen Fan, DDS, PhD, Zhuan Bian, DDS, PhD, Zhi Chen, DDS, PhD
The aim of this research was to study the effects of estrogen deficiency on the receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) synthesis in the periapical lesions that were induced in ovariectomized (OVX) and sham-ovariectomized (Sham) rats. After mandibles were collected, the enzyme histochemical test for tartrate-resistant acid phosphatase and immunohistochemical examination for RANKL and OPG were performed. On days 0, 7, and 28, the numbers of osteoclasts in the periapical areas of the OVX rats were significantly more than those of the Sham group. The data had statistical differences on days 7, 21, and 28 for RANKL-positive cells between the 2 groups. The number of OPG-positive cells of the OVX rats was more than that of the Sham group at the early stage of estrogen deficiency (day 7). Estrogen deficiency–induced severe periapical bone resorption might be mediated by overexpression of RANKL. At the early stage of estrogen deficiency, the osteoblastogenesis was also accelerated, which was shown as a kind of reactive protective response.
In Vitro Comparison of the Biocompatibility of Mineral Trioxide Aggregate, 4META/MMA-TBB Resin, and Intermediate Restorative Material as Root-end–Filling Materials
Yoshito Yoshimine, DDS, PhD, Makiko Ono, DDS, Akifumi Akamine, DDS, PhD
This study compared the effects of three root-end–filling materials: mineral trioxide aggregate (MTA), 4-META/MMA-TBB resin (Super-bond), and intermediate restorative material (IRM) on osteoblast adhesion, proliferation, and matrix formation. MC3T3-E1 cells were inoculated on set material specimens, and the number of cells adhered to each material was assessed at 6 hours and at 3 days of incubation by using Hoechst 33258 staining under a fluorescence microscope. Furthermore, on day 21 of culture, areas in contact with each material surface were observed at light and electron microscopic levels. Cultured cells that adhered to MTA and Super-bond proliferated significantly between 6 hours and 3 days of culture. In addition, on day 21, they produced a thick matrix layer directly on the material surfaces. In contrast, the number of cells that adhered to IRM significantly decreased with time. These cells appeared round in shape, and no matrix formation was found. These results suggest that MTA and Super-bond have good biocompatibility and allow hard-tissue forming cells to create a matrix layer, which might enhance apical tissue regeneration.
Association of Odor from Infected Root Canal Analyzed by an Electronic Nose with Isolated Bacteria
Yoko Yamada, DDS, PhD, Yukihiro Takahashi, DDS, PhD, Kiyoshi Konishi, PhD, Ichiroh Katsuumi, DDS, PhD
Infected root canals usually cause foul odor. On sensory testing, objective evaluation of the odor is difficult because of the subjectivity of the examiner. In this study, the odor of the canal content was analyzed by an electronic nose. Moreover, association of the odor with culturable bacteria isolated from the root canal was examined. The median of the odor index (indicating odor quantity) in nonvital teeth group was significantly higher than that in vital teeth. When Prevotella, Porphyromonas, Fusobacterium, or Bacteroides was detected, the value of the odor index and the strength of smell representation (indicating odor quality) for hydrogen sulfide and ammonia were higher than when these bacteria were not present. Relationship between odor analysis data, clinical symptoms, and isolated bacterial species was seen, thus suggesting that the electronic nose is useful for objective evaluation of root canal odor.