The Root and Root Canal Morphology of the Human Mandibular First Premolar: A Literature Review
Blaine M. Cleghorn, DMD, MS, William H. Christie, DMD, MS, FRCD(C), Cecilia C.S. Dong, DMD, BSc, MS, FRCD(C)
The purpose of this study was to undertake a comprehensive literature review of the root and root canal morphology of the mandibular first premolar. Published studies citing the anatomy and morphology of mandibular premolars report data for over 6,700 teeth. These studies were divided into anatomical studies reporting number of roots, number of canals, and apical morphology. Variations because of sex and ethnic background have also been reported, along with case reports of anomalies.
Approximately 98% of the teeth in these studies were single-rooted. The incidence of two roots was 1.8%. Three roots when reported were found in 0.2% of the teeth studied. Four roots were rare and were found in less than 0.1% of the teeth studied.
Studies of the internal canal morphology revealed that a single canal was present in 75.8% of the teeth. Two or more canals were found in 24.2% of the teeth studied. A single apical foramen was found in 78.9% of the teeth, whereas 21.1% had two or more apical foramina.
The role of genetics and racial variation may result in differences of incidence of root number and canal number in human populations. The dental literature is not unique in studying ethnicity and sex variations. Higher incidences of teeth with additional canals and roots have been reported in Chinese, Australian, and sub-Sahara African populations. Physical anthropology studies seem to show the lowest incidence in Western Eurasian, Japanese and American Arctic populations.
The root and root canal morphology of this tooth can be complex and requires careful evaluation prior to root canal therapy.
The C-shaped Root Canal Configuration: A Review
Hamid Jafarzadeh, DDS, MSc, You-Nong Wu, DDS, PhD
Recognition of unusual variations in the canal configuration is critical because it has been established that the root with a single tapering canal and apical foramen is the exception rather than the rule. The early recognition of these configurations facilitates cleaning, shaping, and obturation of the root canal system. “C” configuration, which is an important anatomic variation, presents a thin fin connecting the root canals. Because of the importance of its true diagnosis and treatment, a comprehensive review of published information and investigations about it in addition to approaches for its treatment is necessary.
Vascular Endothelial Growth Factor and Its Relationship With the Dental PulpLeticia Grando Mattuella, DDS, MSc, Leticia Westphalen Bento, DDS, José Antonio Poli de Figueiredo, DDS, MSc, PhD, Jacques Eduardo Nör, DDS, MSc, PhD, Fernando Borba de Araujo, DDS, MSc, PhD, Anna Christina Medeiros Fossati, DDS, MSc, PhD
The dental pulp is a loose connective tissue located within rigid dentinal walls. Therefore, when subjected to a stimulus, the pulpal tissue has little expansion capacity. The defense mechanisms of this tissue include the formation of tertiary dentin as well as the production of signaling molecules that help in the repair. The dentin matrix is rich in growth factors (GFs) that, when diluted and diffused into the pulp tissue, aid the healing process of the dentinopulpar complex. The angiogenic GFs participate in this event. Vascular endothelial growth factor (VEGF), a potent mitogen for endothelial cells, promotes endothelial cell survival and angiogenesis. Among its receptors, VEGFR-2 seems to be the most intimately associated with mitogenic activities, cell migration, vascular permeability, and survival of endothelial cells. This literature review addresses the cell-signaling process that occurs in response to a pulp stimulus up to its transduction in the target cell, describing the VEGF, as well as its characteristics and receptors. The reported studies have correlated the expression of VEGF and its potential functions that may have an impact on several dental specialties, thus indicating that further clinical investigations should be conducted in order to translate the results obtained until this moment primarily in laboratory experiments.
Comparison of Electrical, Thermal, and Pulse Oximetry Methods for Assessing Pulp Vitality in Recently Traumatized Teeth
Velayutham Gopikrishna, MDS, Kush Tinagupta, MDS, Deivanayagam Kandaswamy, MDS
Pulse oximeter is a well-established and noninvasive method for measuring vascular health by evaluating oxygen saturation. This study compared the efficacy of a custom-made pulse oximeter dental probe with the electric pulp testing and thermal testing for measuring pulp vitality status of recently traumatized permanent teeth. Readings for pulp vitality for 17 recently traumatized maxillary incisors were taken with custom-made pulse oximeter dental probe (group 1), electrical pulp tester (group 2), and thermal testing (group 3) over a 6-month period. The proportion of recently traumatized teeth showing a positive responsiveness in thermal/electric pulp tests increased from no teeth showing responsiveness on day 0 to 29.4% teeth on the 28th day, 82.35% of teeth at 2 months, and 94.11% teeth at 3 months. However, pulse oximeter gave positive vitality readings that remained constant over the study period from day 0 to 6 months in all patients.
Detection and Eradication of Microorganisms in Root-filled Teeth Associated With Periradicular Lesions: An In Vivo Study
Jörg F. Schirrmeister, Dr. med. dent., Anna-Lisa Liebenow, Gabriele Braun, Annette Wittmer†, Elmar Hellwig, Dr. med. dent., Ali Al-Ahmad, Dr. rer. nat.
This study determined the presence of microorganisms by culture and polymerase chain reaction in asymptomatic root-filled teeth with periradicular lesions. Furthermore, a disinfecting regimen using sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine digluconate (CHX) irrigation, and calcium hydroxide (Ca(OH)2) dressing was assessed. After removal of the root-filling material, specimens of 20 cases undergoing retreatment were sampled. Moreover, the canals were sampled after each step of the disinfecting regimen. Prevalence of microorganisms was 60% by culture and 65% by polymerase chain reaction. In four of those samples (31%), DNA of Enterococcus faecalis was found. After further root canal preparation and irrigation using NaOCl and EDTA, microorganisms could be detected in none of the teeth. Thus, CHX and Ca(OH)2 could not show further disinfection. In contrast, microorganisms were found in two teeth after the interappointment dressing. It may be concluded that proper root canal preparation and irrigation using NaOCl and EDTA are sufficient for decontamination of the root canal system during endodontic retreatment.
Reduction in the Cultivable Bacterial Populations in Infected Root Canals by a Chlorhexidine-based Antimicrobial Protocol
José F. Siqueira Jr, DDS, MSc, PhD, Simone S.M. Paiva, DDS, Isabela N. Rôças, DDS, MSc, PhD
The present clinical study was conducted to assess the bacterial reduction after chemomechanical preparation using 0.12% chlorhexidine digluconate solution as an irrigant and the additive antibacterial effect of intracanal dressing with calcium hydroxide (Ca(OH)2) associated with 0.12% chlorhexidine digluconate gel. According to stringent inclusion/exclusion criteria, 13 teeth with primary intraradicular infections and chronic apical periodontitis were selected and followed in the study. Bacterial samples were taken at the baseline (before treatment) (S1), after chemomechanical preparation using chlorhexidine (CHX) as an irrigant (S2), and after a 7-day dressing with Ca(OH) 2/CHX paste (S3). Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of 16S ribosomal RNA gene sequencing analysis. At S1, all canals were positive for bacteria, with the mean number of 3.5 taxa per canal (range, 2–9). At S2, 7 cases (53.8%) still harbored cultivable bacteria, with a mean number of 1.7 taxon per canal (range, 1–4). At S3, only one case (7.7%) was positive for the presence of bacteria. The great majority of taxa found in posttreatment samples were gram-positive bacteria. A significantly high reduction in bacterial counts was observed between S1 and S2 and S1 and S3 (p < 0.001). Also, significant differences were observed for comparisons involving S2 and S3 samples with regard to both quantitative bacterial reduction (p = 0.014) and number of cases yielding negative cultures (p = 0.01). It was concluded that chemomechanical preparation with 0.12% CHX solution as an irrigant significantly reduced the number of intracanal bacteria but failed to render the canal free of cultivable bacteria in about one half of the cases. Application of a 7-day intracanal dressing with Ca(OH) 2/CHX paste further increased significantly the number of cases yielding negative cultures.
An Investigation Into Differential Diagnosis of Pulp and Periapical Pain: A PennEndo Database Study
Mian Iqbal, DMD, MS, Sara Kim, DMD, Frank Yoon, MA
Nine hundred fifty-one emergency and 997 nonemergency patients seeking endodontic treatment were the basis of this study. Variables of interest were 10 pain descriptors, percussion and palpation tests, causative factors, and paired pulpal and periapical diagnoses. A higher number of patients suffering from symptomatic pulpal conditions sought emergency care. Odds of caries being a causative factor were high in symptomatic pulps compared with asymptomatic pulpal and periapical conditions. Higher odds ratios were obtained for sharp pain in symptomatic pulps versus symptomatic periapical conditions. Conversely, odds ratios for dull pain were higher in symptomatic periapical conditions compared with asymptomatic periapical conditions. Percussion and palpation tests were significant in differentially diagnosing between pulpal and periapical conditions. In conclusion, caries was associated with painful pulpitis. The results confirm the differential diagnostic power of sharp and dull pain and percussion and palpation tests. Several symptoms previously believed to have differential diagnostic power were found insignificant.
The Incidence of Mechanical Allodynia in Patients With Irreversible Pulpitis
Christopher B. Owatz, DMD, Asma A. Khan, BDS, PhD, William G. Schindler, DDS, MS, Scott A. Schwartz, DDS, Karl Keiser, DDS, MS, Kenneth M. Hargreaves, DDS, PhD
The mechanisms of odontogenic pain are complex and incompletely understood. Cases of irreversible pulpitis are thought to represent a localized inflammatory response to bacterial challenge in dental pulp tissue. The presenting symptoms are classically defined by exaggerated painful episodes to thermal stimuli that may linger after cessation of the stimulus. However, the associated incidence of mechanical allodynia, defined as reduced mechanical pain threshold to masticatory forces, has not been characterized. This study evaluated pain intensity ratings and the presence of mechanical allodynia reported by 993 consecutive dental patients presenting for tooth extraction in a community health center. After clinical and radiographic examinations, the pulpal/periradicular diagnostic categories were normal pulp/normal periradicular (n = 792 patients), irreversible pulpitis/normal periradicular (n = 86), or irreversible pulpitis/acute periradicular periodontitis (n = 115). The rank order for the mean values of pain intensity ratings was irreversible pulpitis/acute periradicular periodontitis > irreversible pulpitis/normal periradicular > normal/normal (p < 0.05 for all comparisons). The incidence of mechanical allodynia in patients presenting with irreversible pulpitis was 57.2%, indicating that periradicular mechanical allodynia contributes to early stages of odontogenic pain because of inflammation of vital pulpal tissue.
In Vitro Activity of Amoxicillin, Clindamycin, Doxycycline, Metronidazole, and Moxifloxacin Against Oral Actinomyces
Demetrick W. LeCorn, DMD, Frank J. Vertucci, DMD, Maria F. Rojas, DMD, Ann Progulske-Fox, PhD, Myriam Bélanger, PhD
Actinomyces spp have been increasingly associated with endodontic infections. However, the antimicrobial susceptibility of this genus has not been studied extensively. The objective of this study was to determine the susceptibility of oral isolates of Actinomyces naeslundii, Actinomyces gerencseriae, Actinomyces israelii, Actinomyces viscosus, and Actinomyces odontolyticus to amoxicillin, clindamycin, doxycycline, metronidazole, and moxifloxacin using in vitro assays. The minimum inhibitory concentration (MIC) of each bacterial isolate was determined by using E-test strips (AB Biodisk, Solna, Sweden). The MIC90 was 0.19 μg/mL for amoxicillin, 0.25 μg/mL for doxycycline, 0.50 μg/mL for moxifloxacin, and 1.00 μg/mL for clindamycin. However, metronidazole was not active against any of the Actinomyces spp tested (MIC90 > 256 μg/mL).
The Influence of Root Canal Sealer on Extended Intracanal Survival of Enterococcus faecalis With and Without Gelatinase Production Ability in Obturated Root CanalsChristine M. Sedgley, PhD
Enterococcus faecalis can survive for extended periods in obturated root canals. In this study, the hypotheses tested were that long-term survival of E. faecalis is dependent on (1) the type of endodontic sealer and (2) the capacity for microbial gelatinase activity, a potential “virulence” trait identified previously in clinical isolates. Root canals of extracted human canines (n = 95) were inoculated with either E. faecalis OG1RF or its gelatinase-negative mutant E. faecalis TX5128. After 48 hours of incubation at 37°C, canals were obturated with gutta-percha and either the epoxy-resin-based AH-Plus (Dentsply, De Trey, Konstanz, Germany), the silicone-based RoekoSeal (Coltène/Whaledent, Langenau, Germany), or zinc oxide eugenol-based Roth’s sealer (Root Canal Cement Type 801; Roth International Ltd, Chicago, IL). Access cavities were sealed. After 8 months of incubation at 37°C, viable E. faecalis was recovered from more teeth sealed with RoekoSeal (95%) compared with AH-Plus (40%) (p = 0.0004, Fisher’s exact test) and Roth’s sealer (45%) (p = 0.0012, Fisher’s exact test). In the RoekoSeal groups, viable counts of E. faecalis OG1RF were higher than E. faecalis TX5128 (p = 0.03, Mann-Whitney U test) suggesting that gelatinase activity plays a role in long-term survival of E. faecalis in obturated root canals.
An In Vitro Comparison of the Antimicrobial Effects of Various Endodontic Medicaments on Enterococcus faecalis
Joshua M. Davis, DDS, James Maki, PhD, James K. Bahcall, DDS, MS
The purpose of this in vitro study was to investigate the antimicrobial action of Dermacyn (Oculus Innovative Sciences, Petaluma, CA), BioPure MTAD (Dentsply Tulsa Dental, Johnson City, TN), 2% chlorhexidine (CHX; Ultradent, West Jordan, UT), and 5.25% sodium hypochlorite (NaOCl) against Enterococcus faecalis (American Type Culture Collection 4082). Eighteen Petri dishes of BHI agar were inoculated with E faecalis. Each Petri dish had five saturated paper disks placed. Four of the disks were saturated with a different test solution, and the last paper disk served as the control and was saturated with sterile distilled water. The plates were randomly distributed into two groups. Group one (n = 9) was incubated aerobically and group 2 (n = 9) was incubated anaerobically for 48 hours at 37°C. The largest diameter of the zones of microbial inhibition was measured in millimeters and recorded. Statistical analysis was performed with repeated-measures analysis of variance. BioPure MTAD showed significantly (p < 0.05) more zones of microbial inhibition than 5.25% NaOCl, 2% CHX, and Dermacyn. Sodium hypochlorite and CHX showed significantly (p < 0.05) more zones of microbial inhibition than Dermacyn. The zone of inhibition between NaOCl and CHX was not significant (p > 0.05). The control group showed no microbial inhibition.
Effect of Propolis on Survival of Periodontal Ligament Cells: New Storage Media for Avulsed Teeth
Fatih Özan, DDS, PhD, Zübeyde Akin Polat, PhD, Kürsat Er, DDS, PhD, Ülkü Özan, DDS, Orhan Değer, MD, PhD
Propolis is a multifunctional material used by bees in the construction and maintenance of their hives. Propolis possesses several biologic activities such as anti-inflammatory, antibacterial, antioxidant, antifungal, antiviral, and tissue regenerative, among others. The purpose of this study was to determine the ability of propolis to serve as a temporary storage medium for the maintenance of periodontal ligament (PDL) cell viability of avulsed teeth. PDL cells were obtained from healthy third molars and cultured in Dulbecco’s Modified Eagles Medium (DMEM). Cultures were subjected to 10% propolis solution, 20% propolis solution, long-shelf life light milk with lower fat content (milk), Hank’s Balanced Salt Solution, tap water as the negative control, and DMEM as the positive control. Tissue culture plates were incubated with experimental media at 37°C for 1, 3, 6, 12, or 24 hours. PDL cell viability was assessed by trypan blue exclusion. Statistical analysis of the data was accomplished by using one-way analysis of variance complemented by the Tukey test. The level of significance was 5% (p < 0.05). The results showed that 10% propolis was a more effective storage medium than other groups. In conclusion, propolis can be recommended as a suitable transport medium for avulsed teeth.
Performance of Ultrasonic Retrograde Systems
Phillip L.M. Tomson, BDS, MFDS, RCS(Edin), MFDS, RCS(Eng), Simon C. Lea, MSc, PhD, CSci, CPhys, MInstP, Philip J. Lumley, BDS, MDentSci, PhD, FDSRCPS, A. Damien Walmsley, BDS, MSc, PhD, FDSRCPS
The aim of this study was to evaluate variations in power output of different Piezon-Master 400 (Electro Medical Systems, Nyon, Switzerland) ultrasonically driven generators and analytic handpieces at a range of power settings. A scanning laser vibrometer was used to measure the maximum vibration displacement amplitude of a KiS 2D tip. Ten repeat scans were made of the unloaded tip oscillation at six power settings. Data were acquired from four different generators and handpieces. Linear trend lines fitted to all tip data showed that none of the generator/handpiece combinations produced a linear increase in tip displacement amplitude with increasing power setting. A univariate analysis of variance (general linear model) showed that generator, handpiece, and power were all significant variables (p < 0.0001). This study showed that there is significant variability in the power output between generators, and not all Analytic handpieces performed consistently when compared with each other.
Comparison of Passive Ultrasonic Debridement Between Fluted and Nonfluted Instruments in Root Canals
Patrick J. Munley, DMD, MS, Gary G. Goodell, DDS, MS, MA
The purpose of this study was to determine if passive ultrasonic irrigation using finger spreaders was more effective than standard files in removing debris after root canal instrumentation. Eighty-five straight canals were instrumented and then passively ultrasonically irrigated with either fluted files or nonfluted finger spreaders for 3 minutes or 1 minute. Images of split canal lumens were imported into Adobe Photoshop CS2 (Adobe Systems, San Jose, CA), and percentage of debris remaining was calculated. Analysis of variance and Student Newman-Keuls post hoc tests (p < 0.05) showed that when comparing the entire canal, 3 minutes of activation with a file had significantly less debris remaining than 1 minute of activation with a spreader. There was a trend for 1 minute of activation with a file to have less debris than either 3 minutes or 1 minute of activation with a spreader. When comparing apical, middle, or coronal thirds between groups, no significant differences were found. The use of a nonfluted spreader did not improve debris removal.
Calcium Loss From Root Canal Dentin Following EDTA, EGTA, EDTAC, and Tetracycline-HCl Treatment With or Without Subsequent NaOCl Irrigation
T. Cem Sayin, DDS, PhD, Ahmet Serper, DDS, PhD, Zafer C. Cehreli, DDS, PhD, Sukru Kalayci, PhD
The aim of this study was to determine the extent of calcium removal on root canal dentin after 17% EDTA, 17% EGTA, 15% EDTAC, and 1% tetracycline-HCl treatment; with or without subsequent use of 2.5% NaOCl. Extracted single-rooted human teeth were bisected longitudinally and the root halves (n = 100) were isolated with nail varnish, leaving the root canal exposed. The samples were immersed in the test solutions for 1 and 5 minutes, after which the amount of calcium ion (Ca2+) release into the solutions was determined by flame photometry. Regardless of treatment time, all single (treatment solution only) and combined (treatment solution with subsequent NaOCl application) irrigation regimens removed significantly more Ca2+ than control treatment (distilled water). Compared with other groups, treatment with 17% EDTA and 17% EDTA + 2.5% NaOCl resulted in the maximum amount of Ca2+ removal from root canal dentin (p < 0.05). All combined-treatment groups except 17% EGTA + 2.5% NaOCl removed significantly more Ca2+ than their single-treatment versions (p < 0.05). Within each test group, extending the treatment time to 5 minutes resulted in significantly more Ca2+ removal (p < 0.05).
Evaluation of the Efficiency of a New File Removal System in Comparison With Two Conventional Systems
Yoshitsugu Terauchi, DDS⁎, Le O’Leary, DDS†, Izumi Kikuchi, DDS, PhD⁎, Mami Asanagi, DDS⁎, Takatomo Yoshioka, DDS, PhD, Chihiro Kobayashi, DDS, PhD, Hideaki Suda, DDS, PhD
A novel file-removal system (FRS) was designed to address weak points of conventional file-removal methods. The purpose of this study was to compare file-removal time and dentin removal rates among the FRS, the Masserann kit (Micro-Mega, Besancon, France), and an ultrasonic file-removal method. Ninety extracted mandibular incisors with separated nickel titanium files were divided into 3 groups of 30 teeth each. Groups 1, 2, and 3 had file-removal attempts made by using the Masserann kit, a CPR-7 titanium ultrasonic tip (Obtura-Spartan Corp., Fenton, MO), and the FRS, respectively. Each group had three operators removing the separated files. Pre-/postoperative digital radiographs were downloaded into image analyzing software that calculated the amount of dentin removed. The FRS needed less time and had less dentin loss than the others (p < 0.05). There were statistical differences between the experienced operator and less experienced operators regarding the file-removal time and the dentin removal rates (p < 0.05).
Effect of Immersion in Sodium Hypochlorite on Torque and Fatigue Resistance of Nickel-Titanium Instruments
Ove A. Peters, PD, Dr. med dent MS, Jan O. Roehlike, Dr. med dent, Michael A. Baumann, Prof. Dr. med dent
This study investigated the effect of immersion in sodium hypochlorite (NaOCl) on torque and fatigue resistance of two nickel-titanium files. Size 25 .04 ProFile and RaCe files were immersed in 5.25% NaOCl for 1 or 2 hours at temperatures of 21°C and 60°C. Torque and angle at failure were measured according to ISO 3630-1. Resistance to cyclic fatigue was determined by counting rotations to breakage in a 90° curve with a 5-mm radius. Data were analyzed by 2-way analysis of variance. Torsional resistance of both rotaries was not significantly affected by immersion in NaOCl, except after 2 hours of immersion at 60°C. Resistance to cyclic fatigue decreased significantly for ProFile and RaCe instruments after immersion in NaOCl. Spontaneous fractures occurred in 28 of 160 files during immersion in NaOCl. In conclusion, nickel-titanium rotaries have reduced resistance to cyclic fatigue after contact with heated NaOCl and may then be considered single-use instruments.
Effects of Short-term Chemical Disinfection of Gutta-Percha Cones: Identification of Affected Microbes and Alterations in Surface Texture and Physical Properties
Nan-Shim Pang, DDS, MSD, Il-Young Jung, DDS, PhD, Kwang-Shik Bae, DDS, PhD, Seung-Ho Baek, DDS, PhD, Woo-Cheol Lee, DDS, PhD, Kee-Yeon Kum, DDS, MSD, PhD
The aims of this study were to identify microorganisms on the surface of gutta-percha (GP) cones using a polymerase chain reaction (PCR) and to evaluate the sterilization effect of 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), and ChloraPrep on these bacteria. Alterations of the surface texture and physical properties of GP cone after chemical sterilization were compared. A total of 150 GP cones were randomly selected in endodontic clinics, and a PCR assay was performed to identify the contaminating microorganisms. After inoculation with the same microorganisms followed by drying for 1 day, the GP cones were immersed in the three chemical disinfectants. The sterilization effects were assessed by measuring the turbidity and through subculturing. The changes in surface texture were observed by scanning electron microscopy, and Instron 5500 (Instron Corp, Canton, MA) was used to measure the tensile strength and elongation rate of the GP cones after chemical sterilization. Statistical analysis was performed. Results indicate that 19.4% of GP cones from the clinic were contaminated, and all the species belonged to the genus Staphylococcus. Three chemical disinfectants were all effective in the rapid disinfection of GP cones against Staphylococcus spp, and 1-minute immersion of the GP cones was adequate for disinfection. Microphotographs of the NaOCl-soaked cone showed a cluster of cuboidal crystals. The tensile strength between the NaOCl- and CHX-soaked groups was significantly different (p < 0.05), but there was no significant difference between the NaOCl- and ChloraPrep-soaked groups (p > 0.05). All disinfectants significantly increased the elongation rate of the GP cones compared with fresh GP cones (p < 0.05), especially in the ChloraPrep (Medi-flex, Leawood, KS). These results show that the three chemical disinfectants are effective agents for the rapid sterilization of GP cones. However, further research will be needed to determine the clinical relevance of the changes in physical properties.
Advanced Noninvasive Light-activated Disinfection: Assessment of Cytotoxicity on Fibroblast Versus Antimicrobial Activity Against Enterococcus faecalis
Saji George, BSc, MSc, Anil Kishen, BDS, MDS, PhD
Recent interest in light-activated disinfection demands insight on the selectivity towards bacterial cells compared with mammalian cells. This study was aimed to evaluate the cytotoxicity and selectivity of an advanced noninvasive light-activated disinfection (ANILAD) developed in our laboratory. The extent of cytotoxic effect of methylene blue activated by visible light of wavelength 664 nm was tested and compared with sodium hypochlorite (NaOCl) under in vitro and ex vivo conditions on fibroblast L929 cells. Simultaneous evaluation of cytotoxicity and antibacterial effect was also conducted to study the specificity of light-activated therapy (LAT) toward prokaryotic cells (Enterococcus faecalis). The cytotoxicity was evaluated by 3-(4, 5-dimethylthiazol-2- yl)-2, 5-diphenyltetrazolium bromide assay and trypan blue viability test, whereas colony-forming units were determined to evaluate bacterial viability. Data from both in vitro and ex vivo experiments showed that cytotoxicity was significantly less in LAT compared with NaOCl (p < 0.001). E faecalis cells were killed at a faster rate than fibroblasts. An irradiation dose producing 97.7% bacterial killing showed only 30% fibroblast dysfunction. This study indicated that ANILAD produced an insignificant effect on mammalian cells.
Influence of the Endodontic Treatment on Mechanical Properties of Root Dentin
Carlos José Soares, PhD, Fernanda R. Santana, DDS, Natércia R. Silva, DDS, MS, Janaína C. Preira, DDS, MS, Cristina A. Pereira, DDS
This study evaluated the effect of endodontic treatment and storage time on the flexural and ultimate tensile strength of root dentin. Eighty bovine teeth were divided into endodontically treated (ET) and endodontically untreated (NT) teeth. The ET canals were instrumented and irrigated with sodium hypochlorite 1.0%. Roots were filled with gutta-percha and zinc-oxide/eugenol cement by the lateral condensation technique. Tests were performed as follows: t1, immediately; t2, 7days; t3, 15days; and t4, 30 days after extraction for NT groups or after extraction and endodontic treatment for ET groups (n = 10). Roots were axially cut into two halves, one half was used to obtain bars for performing the four-bending flexural test and the other half to obtain slices that were trimmed resulting in hourglass-shaped specimens for microtensile testing. Samples were submitted to the tests, and the data were statistically analyzed. Results indicated that endodontic treatment potentiated by time elapsed after endodontic treatment can affect the physical properties of dentin.
Micromorphology of Enamel Surface After Vital Tooth Bleaching
Ljubisa Markovic, DDS, Rainer Andreas Jordan, DDS, Nebojsa Lakota†, Peter Gaengler, PhD, DDS
The aim of the present study was to assess microroughness changes of enamel surfaces after bleaching procedures with 10% and 16% concentrations of carbamide peroxide by confocal laser scanning microscopy. Twenty caries-free incisors, extracted for periodontitis reasons, were sectioned into two halves of experimental and control specimens. The teeth were divided into two groups, and the experimental specimens were exposed to either 10% or 16% carbamide peroxide for 4 hours per 7 days. Measurements were made at three randomly selected 140 × 100 μm areas of 10 experimental and control specimens per group at the same crown level. Microroughness was measured in “total roughness” (Rt) and “average roughness” (Ra) descriptor values. The statistical analysis showed significantly higher microroughness according to Rt values and Ra values for both groups of carbamide peroxide exposed enamel surfaces.
Comparison of the EndoVac System to Needle Irrigation of Root Canals
Benjamin A. Nielsen, DMD, J. Craig Baumgartner, DDS, PhD
Past studies have shown that current irrigation methods are effective at cleaning root canals coronally but less effective apically. To be effective, endodontic irrigants should ideally be delivered near working length. The purpose of this study was to compare the efficacy of the EndoVac irrigation system and needle irrigation to debride root canals at 1 and 3 mm from working length. One tooth of each matched pair was instrumented and irrigated by using the EndoVac, which uses negative pressure to deliver irrigating solutions to working length. The other tooth of the matched pair was instrumented and irrigated with a 30-gauge ProRinse irrigating needle. All teeth were irrigated with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) for a predetermined amount of time, and total volume of irrigant used was recorded. After instrumentation and irrigation, the teeth were fixed, decalcified, and sectioned at 1 mm and 3 mm from working length. Serial sections were made and digitally photographed. The amount of remaining debris was determined as a percentage of the area of the canal lumen. Remaining debris and total irrigant were analyzed by using the Wilcoxon signed rank test at the 5% confidence level. At the 1-mm level, significantly less debris was found in the EndoVac group (p = 0.0347). At the 3-mm level, there was no significant difference between groups. Significantly more irrigant was delivered with the EndoVac (p < 0001). This study showed significantly better debridement at 1 mm from working length by using the EndoVac compared with needle irrigation.
An FTIR Study of the Setting Reaction of Various Endodontic Sealers
Emmanuel Mazinis, DDS, George Eliades, DDS, Theodore Lambrianides, DDS
The aim of the present study was to investigate the correlation between setting time and setting conversion in endodontic sealers. The sealers tested were Roth’s 811, Endion, Sealapex, and AH-26 Silverfree. The setting time was recorded according to International Standardization Organization 6876 specification, whereas the setting conversion was monitored by micro-multiple internal reflection Fourier transform infrared spectroscopy immediately after mixing, before the setting time, at the setting time, and after the setting time. In Roth’s 811, which showed the longest setting time, all free eugenol was consumed at the setting time. The setting conversion of Endion, Sealapex, and AH-26 Silverfree continued after the setting time. No correlation was found between setting time and setting conversion because of the different setting mechanisms involved in the materials tested.