Application of Small Interfering RNA for Inhibition of Lipopolysaccharide-induced Osteoclast Formation and Cytokine Stimulation
Farshid S. Fahid, DDS, Jin Jiang, DDS, PhD, Qiang Zhu, DDS, PhD, Cuiping Zhang, Elizabeth Filbert, DMD, Kamran E. Safavi, DMD, MEd, Larz S.W. Spångberg, DDS, PhD
RNA interference (RNAi) is a unique and powerful tool used for the study of gene function by suppressing its expression. Nuclear factor of activated T cells (NFATc1) is the most strongly induced transcription factor mediated by receptor activator for nuclear factor kappa B ligand stimulation and has shown to be a key regulator of osteoclastogenesis. To determine the application of small interfering RNA (siRNA) for inhibition of lipopolysaccharide (LPS)-induced cytokine stimulation and osteoclast formation, murine monocyte, RAW 264.7 cells as well as differentiated osteoclasts were transfected with NFATc1-specific siRNA and then stimulated with 100 ng/mL LPS. By using real-time polymerase chain reaction analysis and enzyme-linked immunosorbent assay, we confirmed that monocytes whose NFATc1 protein expression was silenced by using RNAi produced lower levels of inflammatory cytokines, fewer numbers evolved into mature osteoclasts, and osteoclasts expressed lower levels of osteoclast-specific gene markers such as tartrate-resistant acid phosphatase and cathepsin K. These results suggested that RNAi could be used to modulate the effects of LPS stimulation.
Fraudulent Use of Digital Radiography: Methods To Detect and Protect Digital Radiographs
Filip L.G. Calberson, DDS, MMS, Geert M. Hommez, DDS, MMS, PhD, Roeland J. De Moor, DDS, MMS, PhD
Digital radiography has become an indispensable diagnostic tool in dentistry today. To improve vision and diagnosis, dental x-ray software allows image enhancement (eg, adjusting color, density, sharpness, brightness, or contrast). Exporting digital radiographs to a file format compatible with commercial graphic software increases chances that information can be altered, added, or removed in an unethical manner. Dental radiographs are easily duplicated, stored, or distributed in digital format. It is difficult to guarantee the authenticity of digital images, which is especially important in insurance or juridic cases. Image-enhancement features applied to digital radiographs allow mishandling or potential abuse. This has been illustrated by several recently published studies. A standard authentication procedure for digital radiographs is needed. A number of manipulated radiographic images are presented to show concerns about security, reliability, and the potential for fraud. Antitampering techniques and methods of detecting manipulations in digital medical images are discussed.
The Evaluation of Bond Strength of a Composite and a Compomer to White Mineral Trioxide Aggregate with Two Different Bonding Systems
Emine Şen Tunç, DDS, PhD, I.şıl Şaroğlu Sönmez, DDS, PhD, Şule Bayrak, DDS, PhD, Türkan Eğilmez, DDS
The purpose of this study was to evaluate the bond strength of a resin composite and a polyacid modified composite or “compomer” to white mineral trioxide aggregate (WMTA) with two different bonding systems (total-etch one bottle and self-etch one step). Forty specimens of WMTA were prepared and divided into four groups. In group one, Single Bond (3M/ESPE, St Paul, MN) and Z250 (3M/ESPE) were placed over WMTA. In group two, Prompt L-Pop (3M Dental Products, St Paul, MN) and Z250 were applied. In group three, Single Bond was applied with Dyract AP (Dentsply DeTrey, Konstanz, Germany), and, in group four, Prompt L-Pop was applied with Dyract AP. The shear bond strength was measured, and the fractured surfaces were examined. The results of the shear bond strength tests were analyzed by one-way analysis of variance test. The results of this study have suggested that the total-etch one-bottle adhesive system mediated a stronger bond to WMTA for both the resin composite and the compomer investigated. The placement of composite (Z250) and compomer materials (Dyract AP), used with total-etch one-bottle adhesive (Single Bond), over WMTA as final restoration may be appropriate.
Antibiotic Resistance Gene Transfer between Streptococcus gordonii and Enterococcus faecalis in Root Canals of Teeth Ex Vivo
Christine M. Sedgley, MDSc, MDS, PhD, Esther H. Lee, BS, Matthew J. Martin, BA, Susan E. Flannagan, MA
Multiple bacterial species coexisting in infected root canals might interact, but evidence for interspecies gene transfer is lacking. This study tested the hypothesis that horizontal exchange of antibiotic resistance can occur between different bacterial species in root canals. Transfer of the conjugative plasmid pAM81 carrying erythromycin resistance between 2 endodontic infection-associated species, Streptococcus gordonii and Enterococcus faecalis, was investigated in an ex vivo tooth model. Equal numbers of each species (one with pAM81 and the other plasmid-free) were combined in prepared root canals of sterilized teeth and incubated at 37°C. At 24 and 72 hours, bidirectional interspecies antibiotic resistance gene transfer was evident in microorganisms recovered from teeth; average transfer frequencies from S. gordonii to E. faecalis were 10−3 transconjugants per donor and from E. faecalis to S. gordonii were 10−6 and 10−7 transconjugants per donor at 24 and 72 hours, respectively. Microbial accumulations were observed on root canal walls with scanning electron microscopy. Horizontal genetic exchange in endodontic infections might facilitate adoption of an optimal genetic profile for survival.
Comparison of Periapical Radiography and Limited Cone-Beam Tomography in Posterior Maxillary Teeth Referred for Apical Surgery
Kenneth M.T. Low, BDS, Karl Dula, PD DMD, Walter Bürgin, MS, BE, Thomas von Arx, PD DMD
This study compared periapical (PA) radiography and cone-beam tomography (CBT) for preoperative diagnosis in posterior maxillary teeth of consecutive patients referred for possible apical surgery. Images were concurrently analyzed by an oral radiologist and an endodontist to reach consensus in interpretation of the radiographic findings. The final material included 37 premolars and 37 molars with a total of 156 roots. CBT showed significantly more lesions (34%, p < 0.001) than PA radiography. Detecting lesions with PA radiography alone was most difficult in second molars or in roots in close proximity to the maxillary sinus floor. Additional findings were seen significantly more frequently in CBT compared with PA radiography including expansion of lesions into the maxillary sinus (p < 0.001), sinus membrane thickening (p < 0.001), and missed canals (p < 0.05). The present study highlights the advantages of using CBT for preoperative treatment planning in maxillary posterior teeth with apical pathology.
Microbial Analysis of Canals of Root-filled Teeth with Periapical Lesions Using Polymerase Chain Reaction
Brenda P.F.A. Gomes, PhD, MSc, BDS, Ericka T. Pinheiro, PhD, MSc, BDS, Rogério C. Jacinto, PhD, MSc, BDS, Alexandre A. Zaia, PhD, MSc, BDS, Caio C.R. Ferraz, PhD, MSc, BDS, Francisco J. Souza-Filho, PhD, MSc, BDS
The objective of the present study was to investigate the presence of nine bacterial species in root-filled teeth associated with periapical lesions using a polymerase chain reaction analysis and to correlate these species with clinical features of the cases. DNA was extracted from 45 canal samples of root-filled teeth with periapical lesions. A PCR assay using species-specific primers of 16S rDNA and the downstream intergenic spacer region was used for microbial detection. Enterococcus faecalis was the most prevalent species, detected in 77.8% of the study teeth, followed by Peptostreptococcus micros, detected in 51.1%. Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, and Prevotella nigrescens were detected in 35.6%, 22.2%, 11.1%, and 11.1% of the sampled teeth, respectively. Moreover, PCR detected Filifactor alocis in 26.7%, Treponema denticola in 24.4%, and Tannerella forsythia in 4.4% of the samples. T. denticola and P. micros were statistically associated with tenderness to percussion (p < 0.05). P. nigrescens was associated with the presence of spontaneous pain and abscess (p < 0.05). P. endodontalis and P. nigrescens were associated with purulent exudates (p < 0.05). Synergistic relationship was also observed between some species. The results of this study indicated that E. faecalis was the most frequently identified test species by PCR in teeth with failing endodontic treatment.
Comparison of Coconut Water, Propolis, HBSS, and Milk on PDL Cell Survival
Velayutham Gopikrishna, MDS, Parvinder Singh Baweja, BDS, Nagendrababu Venkateshbabu, BDS, Toby Thomas, MDS, Deivanayagam Kandaswamy, MDS
Coconut water is biologically pure and sterile, with a rich presence of amino acids, proteins, vitamins, and minerals. The purpose of this study was to use a collagenase-dispase assay to investigate the potential of a new storage medium, coconut water, in comparison with propolis, Hank's balanced salt solution (HBSS), and milk in maintaining viable periodontal ligament (PDL) cells on simulated avulsed teeth. Seventy freshly extracted human teeth were divided into 4 experimental groups and 2 control groups. The positive and negative controls corresponded to 0-minute and 8-hour dry times, respectively. The experimental teeth were stored dry for 30 minutes and then immersed in 1 of the 4 media (coconut water, propolis, HBSS, and milk). The teeth were then treated with dispase grade II and collagenase for 30 minutes. The number of viable PDL cells was counted with a hemocytometer and analyzed. Statistical analysis showed that coconut water kept significantly more PDL cells viable compared with propolis, HBSS, or milk. Coconut water can be used as a superior transport medium for avulsed teeth.
Comparison of the Efficacy of Three Chelating Agents in Smear Layer Removal
Sedigheh Khedmat, DDS, MSc, Noushin Shokouhinejad, DDS, MSc
The purpose of this study was to compare the efficacy of SmearClear (Sybron Endo, Orange, CA), 17% EDTA, and 10% citric acid in smear layer removal. Forty-eight extracted single-rooted human teeth were randomly divided into 4 groups (n = 12) and instrumented using Mtwo nickel-titanium rotary instruments. Each canal was subsequently irrigated with one of the following solutions: 5.25% NaOCl (control), SmearClear, 17% EDTA, or 10% citric acid. After that, all the specimens were subjected to irrigation with 5.25% NaOCl. The teeth were then processed for scanning electron microscopy (SEM), and the removal of the smear layer was examined in the coronal, middle, and apical thirds. The results showed that there were no significant differences in the efficacy of three chelating agents at all levels of the root canals. The comparison of three one thirds in each group showed no significant difference in the SmearClear and EDTA groups. However, the efficacy of citric acid was significantly less in the apical third compared with the coronal and middle thirds of the canals. In conclusion, the protocol used in this study was not efficient to completely remove the smear layer especially in the apical third of the canal.
Repair of a Large Furcation Perforation: A Four-Year Follow-Up
Jose L. Ibarrola, DDS, MS, Stephen G. Biggs, DDS, Thomas J. Beeson, DDS
This case report describes the management of a large furcation perforation in a maxillary first molar. Although the majority of the pulpal floor was destroyed and the mesiobuccal root was damaged, an attempt was made to repair the defect and restore the tooth. An absorbable gelatin sponge matrix was placed, and the defect was repaired with gray ProRoot mineral trioxide aggregate. Subsequently the endodontic treatment was completed; the tooth was restored and was later used as a fixed partial denture abutment. A 55-month recall showed no evidence of periodontal breakdown, no symptoms, and complete healing of all periradicular lesions.
A Microbiological Profile of Symptomatic Teeth with Primary Endodontic Infections
Luciana M. Sassone, DDs, MSc, PhD, Rivail A. Fidel, DDs, MSc, PhD, Marcelo Faveri, DDs, MS, PhD, Rafael Guerra, DDS, Luciene Figueiredo, DDs, MSc, PhD, Sandra R. Fidel, DDs, MSc, PhD⁎, Magda Feres, DDs, MSc, PhD
The aim of this study was to evaluate the composition of the microbiota of primary endodontic infections associated with symptomatic teeth. Samples were collected by means of a #15 H-type file and 2 sterile paper points from 60 symptomatic (n = 30) or asymptomatic (n = 30) single-rooted teeth with necrotic pulp. The presence of 40 bacterial species was determined by the checkerboard DNA-DNA hybridization method. The species found in higher counts (×105) in symptomatic cases were Fusobacterium nucleatum ssp. vincentii, Veillonella parvula, Treponema socranskii, Enterococcus faecalis, and Campylobacter gracilis and in asymptomatic cases were F. nucleatum ssp. vincentii, Fusobacterium nucleatum ssp. nucleatum, E. faecalis, Eubacterium saburreum, and Neisseria mucosa. Total bacterial counts and counts of Tannerella forsythia were significant higher in symptomatic cases (p < 0.05), whereas levels of Propionibacterium acnes were reduced in this group of teeth. The data of the present investigation suggested.
Prospective Clinical Study Evaluating Endodontic Microsurgery Outcomes for Cases with Lesions of Endodontic Origin Compared with Cases with Lesions of Combined Periodontal–Endodontic Origin
Euiseong Kim, DDS, MSD, PhD, Jin-Seon Song, BDS, MS, FRACDS, Il-Young Jung, DDS, MSD, PhD, Seung-Jong Lee, DDS, MSD, PhD, Syngcuk Kim, DDS, PhD
The aim of this study was to evaluate the outcomes of endodontic microsurgery by comparing the healing success of cases having a lesion of endodontic origin compared with cases having a lesion of combined endodontic-periodontal origin. Data were collected from patients in the Department of Conservative Dentistry, Dental College, Yonsei University, Seoul, Korea between March 2001 and June 2005. A total number of 263 teeth from 227 patients requiring periradicular surgery were included in this study. Patients were recalled every 6 months for 2 years and every year thereafter to assess clinical and radiographic signs of healing. A recall rate of 73% (192 of 263 patients) was obtained. The successful outcome for isolated endodontic lesions was 95.2%. In endodontic-periodontal combined lesions, successful outcome was 77.5%, suggesting that lesion type (ABC vs DEF) had a strong effect on tissue and bone healing.
Dentin Phosphophoryn Promotes Cellular Migration of Human Dental Pulp Cells
Yoshiyuki Yasuda, DDS, PhD, Masanobu Izumikawa, DDS, PhD, Kuniaki Okamoto, DDS, PhD, Takayuki Tsukuba, DDS, PhD, Takashi Saito, DDS, PhD
Dentin phosphophoryn (DPP) is a dentin sialophosphoprotein gene product that has an RGD motif and repeat sequences of aspartic acid and phosphoserine. To date, the function of DPP in the early stage of reparative dentin formation still remains unclear. The objective of this study was to evaluate the effects of DPP on pulp cell migration and proliferation. DPP promoted cell migration in a concentration-dependent manner, thus increasing it by about 3-fold at 1000 ng/mL compared with the control, but it had no effect on cell proliferation. Dephosphorylated DPP also promoted cell migration, similarly to DPP. However, cell migration was significantly suppressed by the addition of αvβ3 integrin antibody to the medium. Furthermore, porcine DPP-derived RGD peptide, but not its mutant RAD peptide, significantly promoted cell migration. These results indicated that the RGD motif of DPP plays an important role in the migration of human dental pulp cells.
Gender Differences in Analgesia for Endodontic Pain
Jeffrey L. Ryan, DDS, MS, Badri Jureidini, DDS, MS, James S. Hodges, PhD, Michael Baisden, DDS, James Q. Swift, DDS, Walter R. Bowles, DDS, MS
The purpose of this prospective clinical trial was to investigate the analgesic efficacy of three oral medication groups on postoperative endodontic pain in male and female dental patients, with an emphasis on analgesic differences between the sexes. Forty-three patients were administered ibuprofen 600 mg, placebo, or pentazocine 50 mg/0.5 mg naloxone in a randomized, double-blinded manner. Beginning immediately after endodontic treatment, patients took the assigned medication every 6 hours for 24 hours and recorded their degree of discomfort on a 100-mm visual analog scale. Statistical analysis of the data showed that ibuprofen 600 mg provided statistically significantly greater analgesia than placebo at 6 and 12 hours (P = 0.0014 and 0.0024), and pentazocine/naloxone provided statistically significantly greater analgesia than placebo at 12 hours (P = 0.0084). Sex-dependent differences were noted within the pentazocine/naloxone group, which showed significantly greater analgesia in females compared with males (P = 0.007).
Regenerative Treatment of an Immature, Traumatized Tooth With Apical Periodontitis: Report of a Case
Elisabetta Cotti, DDS, MS, Manuela Mereu, DDS, Daniela Lusso, DDS
This case report describes the treatment of a necrotic immature permanent central incisor with complete crown fracture, suspected root fracture, and sinus tract, which was not treated with conventional apexification techniques. Instead, a regenerative approach based on the trauma literature's methods for revascularization was provided. The root canal was gently debrided of necrotic tissue with a sharp spoon excavator and irrigated for only one third of its length with NaOCl and then medicated with calcium hydroxide. After 15 days the sinus tract had healed, and the tooth was asymptomatic. The tooth was accessed, calcium hydroxide was removed, bleeding was stimulated to form an intracanal blood clot, and mineral trioxide aggregate was placed coronally to the blood clot. After 8 months, a coronal calcified barrier was radiographically evident and accompanied with progressive thickening of the root wall and apical closure. Two and a half years after treatment was initiated, the tooth remained asymptomatic, and the sinus tract had not reappeared. The progressive increase in the thickness of the dentinal walls and subsequent apical development suggest that appropriate biologic responses can occur with this type of treatment of the necrotic immature permanent tooth with sinus tract.
Three-dimensional Analysis of Cutting Behavior of Nickel-Titanium Rotary Instruments by Microcomputed Tomography
Ya Shen, DDS, PhD, Markus Haapasalo, DDS, PhD
The cutting behavior of nickel-titanium rotary instruments with and without irrigation was evaluated in a bovine bone model. Six brands of NiTi rotary instruments were constrained into a curved trench. The tips of the instruments were bent to create a 1-mm long initial contact with the floor of the trench. After a series of 100, 200, 300, 400, and 500 (1,500 total) push-pull strokes on each rotating instrument, the grooves were scanned by microcomputed tomography. The volume of removed material and the maximum depth of the cut groove were measured. Irrigation increased the cutting efficiency of the instruments significantly, except for Liberator (Li). There was a significant correlation between the extracted volume and the maximum depth. The volume removal rate was highest with K3 and Li (dry) and with K3 and FlexMaster (FM) (irrigation group). The maximum cutting depth was highest with FM and K3 in both dry and irrigation groups. The cutting behavior of NiTi rotary instruments depends both on experimental setup, instrument design, and cutting condition.
The Effect of Setting Accelerator on Properties of Mineral Trioxide Aggregate
Tsui-Hsien Huang, DDS, PhD, Ming-You Shie, MS, Chia-Tze Kao, DDS, PhD, Shinn-Jyh Ding, PhD
The purpose of this study was to investigate the effect of a sodium phosphate dibasic (Na2HPO4) setting accelerator on the properties of white-colored mineral trioxide aggregate (WMTA). Setting times were measured by using a Gilmore needle. Changes in the pH value, diametral tensile strength, and phase composition of WMTA were evaluated. By using a 15% Na2HPO4 solution as a liquid phase mixed with WMTA, the setting time was significantly reduced to 26 minutes rather than the usual 3 hours. The 15% Na2HPO4 promoted WMTA to achieve a maximum diametral tensile strength of 4.9 MPa at an initial 6-hour aging time and 1 MPa for the cement mixed with water. The pH value of the 15% Na2HPO4-mixed cement was changed from an initial 11.0 to a high of 13.2, which was similar to the results using water. The results suggest that the Na2HPO4 solution may be an effective setting accelerator for WMTA.
The Root Canal Bonding of Chemical-cured Total-etch Resin Cements
Mikako Hayashi, DDS, PhD, Kenji Okamura, DDS, Hongxia Wu, DDS, Yutaka Takahashi, DDS, PhD, Evgeni V. Koytchev, DDS, PhD, Satoshi Imazato, DDS, PhD, Shigeyuki Ebisu, DDS, PhD
Discovering a durable restorative method to reconstruct and reinforce pulpless teeth is a vital key to help prevent root fractures. Complete and firm adhesion of resin cement in root canal dentin using a post is critical to achieve it. The null hypothesis in the present study was that the bond strength of dual-cured and chemical-cured adhesive resin cements to root canal dentin is not affected by their vertical locations in the root canal. In the experiments, extracted human incisors restored with fiber-reinforced posts and adhesive resin cements were subjected to microtensile bond strength testing. Then, the failure modes and the dentin-bonding interfaces were observed. Self-etch and self-adhesive dual-cured resin cements showed frequent pretesting failure despite using a silane coupling agent. Chemical-cured total-etch adhesive material showed stable bonding performances throughout the entire post space and thus has an advantage in post-core restorations.
Impact of Growth Conditions on Susceptibility of Five Microbial Species to Alkaline Stress
Nathalie Brändle, DMD, Matthias Zehnder, DMD, PhD, Roland Weiger, DMD, Tuomas Waltimo, DDS, PhD
The effects of different growth conditions on the susceptibility of five taxa to alkaline stress were investigated. Enterococcus faecalis ATCC 29212, Streptococcus sobrinus OMZ 176, Candida albicans ATCC 90028, Actinomyces naeslundii ATCC 12104, and Fusobacterium nucleatum ATCC 10953 were grown as planktonic cells, allowed to adhere to dentin for 24 hours, grown as monospecies or multispecies biofilms on dentin under anaerobic conditions with a serum-enriched nutrient supply at 37°C for 5 days. In addition, suspended biofilm microorganisms and 5-day old planktonic multispecies cultures were used. Microbial recovery upon direct exposure to saturated calcium hydroxide solution (pH 12.5) for 10 and 100 minutes was compared with control exposure to physiologic saline. Planktonic microorganisms were most susceptible; only E. faecalis and C. albicans survived in saturated solution for 10 minutes, the latter also for 100 minutes. Dentin adhesion was the major factor in improving the resistance of E. faecalis and A. naeslundii to calcium hydroxide, whereas the multispecies context in a biofilm was the major factor in promoting resistance of S. sobrinus to the disinfectant. In contrast, the C. albicans response to calcium hydroxide was not influenced by the growth condition. Adherence to dentin and interspecies interactions in a biofilm appear to differentially affect the sensitivity of microbial species to calcium hydroxide.
Articaine Infiltration for Anesthesia of Mandibular First Molars
Ian P. Corbett, PhD, Mohammad D. Kanaa, MPhil, John M. Whitworth, PhD, John G. Meechan, PhD
A randomized, controlled trial of 31 healthy volunteers compared 4% articaine with 1:100,000 epinephrine buccal infiltration to buccal plus lingual infiltration of the same dose of drug in achieving pulpal anesthesia of mandibular first molar teeth. Data were compared with efficacy of an inferior alveolar nerve block using 2% lidocaine 1:80,000 epinephrine in a cohort of 27 of the volunteers. Anesthesia was determined using electronic pulp testing. Buccal and buccal plus lingual infiltrations of articaine with epinephrine did not differ in efficacy in obtaining pulpal anesthesia for mandibular permanent first molars (p = 0.17). Efficacy of 4% articaine with epinephrine infiltrations for first molar pulp anesthesia was similar to that of an IANB using lidocaine with epinephrine over a 30-minute study period (96 and 80 episodes of no response to maximal stimulation respectively, p = 0.097). Subjective tooth numbness was more common after IANB than buccal infiltration (p = 0.005). The discomfort of buccal infiltration with articaine was volume dependent (p = 0.017) and similar to that of an IANB.
A Review of Factors Influencing Treatment Planning Decisions of Single-tooth Implants versus Preserving Natural Teeth with Nonsurgical Endodontic Therapy
Mian K. Iqbal, BDS, DMD, MS, Syngcuk Kim, DDS, PhD
One of the major issues confronting the contemporary dental clinician is the treatment decision between extracting a tooth with placement of a dental implant or preserving the natural tooth by root canal treatment. The factors that dictate the correct selection of one procedure over the other for each particular case are not yet established by randomized controlled studies. The aim of this review is to evaluate key factors allowing the clinician to make clinical decisions on the basis of the best evidence and in the patient's best interests. General considerations are discussed that will help the reader analyze clinical studies focused on this problem. Importantly, the major studies published to date indicate that there is no difference in long-term prognosis between single-tooth implants and restored root canal–treated teeth. Therefore, the decision to treat a tooth endodontically or to place a single-tooth implant should be based on other criteria such as prosthetic restorability of the tooth, quality of bone, esthetic demands, cost-benefit ratio, systematic factors, potential for adverse effects, and patient preferences. It can be concluded that endodontic treatment of teeth represents a feasible, practical, and economical way to preserve function in a vast array of cases and that dental implants serve as a good alternative in selected indications in which prognosis is poor.
A Novel Polyurethane-based Root Canal–obturation Material and Urethane-Acrylate–based Root Canal Sealer—Part 2: Evaluation of Push-out Bond Strengths
Bor-Shiunn Lee, DDS, MS, PhD, Eddie Hsiang-Hua Lai, DDS, MS, Ken-Hsuan Liao, BS, MS, Chung-Yi Lee, DDS, MS, Kuo-Huang Hsieh, BS, MS, PhD†, Chun-Pin Lin, DDS, MS, PhD
We have developed a visible-light curable urethane-acrylate/tripropylene glycol diacrylate (UA/TPGDA) oligomer to serve as a root canal sealer and a zinc oxide/thermoplastic polyurethane (ZnO/TPU) composite to serve as a root canal obturation material. The purpose of this study was to compare the push-out bond strengths of the following 8 groups of materials: (1) Tubliseal + gutta-percha (TB/GP); (2) Tubliseal + Resilon (TB/R); (3) Epiphany + gutta-percha (EP/GP); (4) Epiphany + Resilon (EP/R); (5) EndoREZ sealer + EndoREZ cone (ES/EC); (6) EndoREZ sealer + ZnO/TPU (ES/PU); (7) UA/TPGDA + EndoREZ cone (UA/EC); and (8) UA/TPGDA + ZnO/TPU (UA/PU). Eighty 1-mm-thick root slices prepared from extracted human permanent molars were randomly divided into 8 groups with 10 specimens in each group. Root slices were filled with the above obturation materials, and then push-out test was performed with a universal testing machine. The results showed that the UA/EC and UA/PU groups had significantly higher bond strengths than the other groups.