Jianing He

Cyclic Fatigue Analysis of a New Generation of Nickel Titanium Rotary Instruments

Recently, a new generation of nickel-titanium (NiTi) rotary instruments including the Twisted File (TF; Sybron Dental Specialties, Orange, CA) and ProFile GT Series X (GTX; Denstply, Tulsa Dental Specialties, Tulsa, OK) was introduced to the market. The purpose of this study was to determine if these new NiTi instruments were more resistant to cyclic fatigue compared with traditionally ground NiTi rotary instruments such as EndoSequence (ES; Brasseler, Savannah, GA) and ProFile (PF; Dentsply, Tulsa Dental Specialties). Size #25 TF, ES, and PF and size #20 GTX with .04 and .06 tapers were tested in a simulated canal with 60 degrees angle of curvature and a 3-mm radius. The number of rotations until fracture was recorded for each instrument. Among both .04 and .06 tapered files, #20 GTX files performed significantly better than all other files tested with tip sizes of #25 (p < 0.001); this may be because of the increased flexibility in the #20 files compared with #25 files. TF was significantly more resistant to cyclic fatigue than ES (p < 0.05) but not different from PF (p > 0.05) with the same tip size. The new manufacturing processes appeared to offer greater resistance to cyclic fatigue in a simulated canal model.

Evaluation of Photodynamic Therapy Using a Light- emitting Diode Lamp against Enterococcus faecalis in Extracted Human Teeth

INTRODUCTION Photodynamic therapy (PDT) with high-power lasers as the light source has been proven to be effective in disinfecting root canals. The aim of this study was to evaluate the antimicrobial effect of PDT using toluidine blue O (TBO) and a low-energy light-emitting diode (LED) lamp after the conventional disinfection protocol of 6% NaOCl. METHODS Single-rooted extracted teeth were cleaned, shaped, and sealed at the apex before incubation with Enterococcus faecalis for 2 weeks. Roots were randomly assigned to five experimental groups and three control groups. Dentin shavings were collected from the root canals of all groups with a #50/.06 rotary file, colony-forming units were determined, and the bacterial survival rate was calculated for each treatment. RESULTS The bacterial survival rate of the NaOCl/TBO/light group (0.1%) was significantly lower (P < .005) than the NaOCl (0.66%) and TBO/light groups (2.9%). CONCLUSIONS PDT using TBO and a LED lamp has the potential to be used as an adjunctive antimicrobial procedure in conventional endodontic therapy.

Comparative Assessment of ActiV GP/Glass Ionomer Sealer, Resilon/Epiphany, and Gutta-Percha/AH Plus Obturation: A Bacterial Leakage Study

The objective of this study was to compare the sealing ability of ActiV GP/glass ionomer (GI) sealer (Brasseler USA, Savannah, GA), Resilon/Epiphany (Pentron Clinical Technologies, Wallingford, CT), and gutta-percha (GP)/AH Plus (Dentsply Maillefer, Tulsa, OK). Seventy-three human single-rooted teeth were randomly divided into three test groups (20 canals each) and two control groups (5 positive and 8 negative). Using Enterococcus faecalis, a split-chamber bacterial leakage model was developed to evaluate the sealing ability of the three obturation systems. Samples were monitored every 24 hours for 65 days. Thirteen teeth leaked in both the Resilon/Epiphany and GP/AH Plus groups, whereas 17 teeth leaked in the ActiV GP/GI group at the end of the observation period. There were no statistically significant differences in the resistance to leakage between the three obturation systems (p > 0.05).

Comparison of Vibringe, EndoActivator, and Needle Irrigation on Sealer Penetration in Extracted Human Teeth

INTRODUCTION Vibringe is a new device that allows continuous sonic irrigation of the canal system during endodontic treatment. The aim of this study was to compare the effect of different irrigation systems on sealer penetration into dentinal tubules of extracted single-rooted teeth. METHODS Fifty single-rooted human teeth were instrumented and randomly divided into 4 groups: group 1 (control), saline; group 2 (conventional irrigation), 17% EDTA followed by 6% NaOCl; group 3 (EndoActivator), same irrigants as group 2; group 4 (Vibringe), same irrigants as group 2. Obturation of all teeth was done with gutta-percha and SimpliSeal labeled with fluorescent dye. Transverse sections at 1 mm and 5 mm from the root apex were examined by using confocal laser scanning microscopy. Percentage and maximum depth of sealer penetration were measured by using NIS-Elements Br 3.0 imaging software. RESULTS Groups 3 and 4 had a significantly greater percentage of the canal wall penetrated by sealer at the 5-mm level than group 1 (P < .0125), but not group 2. No other differences were found between the groups at either section level for both the percentage of sealer penetration and maximum depth. The 5-mm sections in each experimental group had a significantly higher percentage and maximum depth of sealer penetration than did the 1-mm sections (P < .0125). CONCLUSIONS The use of sonic activation with either the EndoActivator or Vibringe did not significantly improve the sealer penetration when compared with conventional irrigation.

Retreatability of a bioceramic root canal sealing material.

INTRODUCTION The efficacy of retreatment techniques for BC Sealer (BCS) (Brasseler USA, Savannah, GA) removal has not yet been assessed. The purpose of this study was to evaluate the efficacy of solvent and rotary instrumentation in the removal of BCS when used in combination with gutta-percha (GP) as compared with AH Plus sealer (Dentsply, Tulsa, OK). METHODS The mesiobuccal canals of 40 mandibular molars were instrumented and obturated with either GP/AH Plus with warm vertical compaction or GP/BCS using a single cone. The groups were subdivided into samples with the master GP cone placed to the working length (WL) or intentionally 2 mm short of the WL. Canals were then retreated using heat, chloroform, rotary instruments, and hand files. The ability to regain the WL and patency were evaluated as well as the time required to remove obturation material. Representative samples were also analyzed via scanning electron microscopy. RESULTS The WL was not regained in 70% of samples with BCS/master cone short of the WL. Patency was not re-established in 20% of samples with BCS/master cone to the WL or in 70% of samples with BCS/master cone short of the WL. CONCLUSIONS Conventional retreatment techniques are not able to fully remove BCS.

The Efficacy of IntraFlow Intraosseous Injection as a Primary Anesthesia Technique

The purpose of this study was to compare the efficacy of intraosseous injection and inferior alveolar (IA) nerve block in anesthetizing mandibular posterior teeth with irreversible pulpitis. Thirty human subjects were randomly assigned to receive either intraosseous injection using the IntraFlow system (Pro-Dex Inc, Santa Ana, CA) or IA block as the primary anesthesia method. Pulpal anesthesia was evaluated via electric pulp testing at 4-minute intervals for 20 minutes. Two consecutive 80/80 readings were considered successful pulpal anesthesia. Anesthesia success or failure was recorded and groups compared. Intraosseous injection provided successful anesthesia in 13 of 15 subjects (87%). The IA block provided successful anesthesia in 9 of 15 subjects (60%). Although this difference was not statistically significant (p = 0.2148), the results of this preliminary study indicate that the IntraFlow system can be used as the primary anesthesia method in teeth with irreversible pulpitis to achieve predictable pulpal anesthesia.

A Prospective, Randomized, Double-blind Comparison of the Injection Pain and Anesthetic Onset of 2% Lidocaine with 1:100,000 Epinephrine Buffered with 5% and 10% Sodium Bicarbonate in Maxillary Infiltrations

INTRODUCTION Local anesthetics can be buffered to a physiological pH before injection to decrease the time of onset and reduce injection pain. METHODS Thirty subjects with intact maxillary canines were included. The subjects randomly received, in a double-blind manner, 1 of the 3 maxillary infiltration injections of 1.8 mL 2% lidocaine with 1:100,000 epinephrine and 2% lidocaine with 1:100,000 epinephrine buffered at 5% and 10% with sodium bicarbonate by volume at 3 separate appointments. Pain on needle penetration and deposition of anesthetic solution was recorded by using a Heft-Parker visual analogue scale. Anesthetic onset was determined by 2 consecutive negative responses to electronic pulp test. RESULTS The mean anesthetic onset for nonbuffered anesthetics was 119 seconds, 116 seconds for the 5% buffered solutions, and 121 seconds for the 10% buffered solutions. There was no significant difference between the 3 groups. There was also no significant difference in pain on needle penetration or anesthetic deposition between the 3 anesthetic solutions tested. CONCLUSIONS Two percent lidocaine with 1:100,000 epinephrine buffered with 5% or 10% sodium bicarbonate did not differ from nonbuffered solutions in anesthetic onset or injection pain in maxillary infiltrations of canines with healthy pulps.

A Retrospective Clinical and Radiographic Study on Healing of Periradicular Lesions in Patients Taking Oral Bisphosphonates

INTRODUCTION Bisphosphonates have been related to impaired bone remodeling. The impact of oral bisphosphonates on periradicular healing has not been studied. The purpose of this study was to evaluate the healing of periradicular lesions in patients taking oral bisphosphonates after root canal therapy. METHODS Thirty-four teeth with preoperative periradicular radiolucencies were identified in patients undergoing oral bisphosphonate therapy. These cases were examined clinically and radiographically to determine treatment outcome. Thirty-eight control teeth were selected from a pool of patients not taking bisphosphonates. Nonsurgical root canal treatment and retreatment was performed by endodontic residents and undergraduate dental students at Baylor College of Dentistry using nonstandardized protocols. RESULTS In the bisphosphonate group, 73.5% of the lesions healed, whereas the control cases had a healing rate of 81.6%. There was no statistically significant difference between the groups (p > 0.05). CONCLUSION The results of this preliminary short-term study suggest that patients taking long-term oral bisphosphonates can expect a satisfactory outcome with evidence of periradicular healing after conventional root canal treatment. Thus, root canal treatment may be considered a safe and realistic alternative to extraction in patients on bisphosphonate therapy.

Biocompatibility and Osteogenic Potential of New Generation Endodontic Materials Established by Using Primary Osteoblasts

INTRODUCTION Generex A and Generex B (calcium silicate based), Capasio (calcium-phospho-alumino silicate based) along with Ceramicrete-D (magnesium phosphate based) are being introduced as a new generation of endodontic materials with the potential to facilitate bone healing. The aim of this study was to evaluate the biocompatibility and osteogenic potential of these new materials by using primary osteoblasts. METHODS Primary osteoblasts were prepared from rat calvaria and exposed to mineral trioxide aggregate (MTA), Generex A, Generex B, Capasio, and Ceramicrete-D prepared to standardized size and shape (n = 5). Trypan blue staining was used to evaluate cell viability from 1-6 days. Mineralization potential was evaluated by scanning electron microscopy for the presence of mineralized nodules. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. RESULTS Only Generex A and MTA allowed cell growth and proliferation throughout the experiment. There were statistically significant differences between groups throughout the experiment beginning on day 1. The greatest amount of cell growth was consistently observed with Generex A and MTA. There was no difference in mineralized nodule formation between any test materials. CONCLUSIONS Generex A was the only new generation endodontic material that supported primary osteoblast growth; no material besides MTA facilitated nodule formation.

Clinical Outcome of Endodontic Microsurgery That Uses EndoSequence BC Root Repair Material as the Root-end Filling Material

INTRODUCTION The purpose of this retrospective study was to determine the clinical and radiographic outcome of root-end surgery when EndoSequence BC Root Repair (ES-BCRR) was used as the root-end filling material and to identify any possible prognostic factors that may have affected the healing outcome. METHODS Clinical records and periapical radiographs were collected from patients who had undergone endodontic microsurgery between 2009 and 2013 in a private endodontic office and had a minimum 1-year follow-up. All surgical procedures were performed by a single endodontist. ES-BCRR was used as the root-end filling material in all cases. Outcome was categorized into healed, healing, and non-healing on the basis of clinical and radiographic findings. The healed and healing cases were pooled and considered as success, and non-healing cases were considered failure. For statistical analysis of the prognostic factors, the dependent variable was the dichotomous outcome (ie, success versus failure). RESULTS Ninety-four patients with 113 teeth met the inclusion criteria and were included in the study. The overall success rate was 92.0%. None of the prognostic factors, including age, sex, tooth position, size of periapical radiolucency, presence of a sinus tract, preoperative symptoms, and retreatment previous to surgery, appeared to have any significant effects on the outcome (P > .05). CONCLUSIONS This current study suggests that ES-BCRR is a suitable root-end filling material to be used in endodontic surgery.