No abstract available.

There are various factors affecting the fracture of NiTi rotary files. This study was performed to evaluate the effect of cross sectional area, pecking motion and pecking distance on the cyclic fatigue fracture of different NiTi files. Five different NiTi files-Profile(R)(Maillefer, Ballaigue, Switzerland), ProTaper(TM) (Maillefer, Ballaigue, Switzerland), K3(R) (SybronEndo, Orange, CA), Hero 642(R) (Micro-mega, Besancon, France), Hero Shaper(R)(Micro-mega, Besancon, France)-were used. Each file was embedded in temporary resin, sectioned horizontally and observed with scanning electron microscope. The ratio of cross-sectional area to the circumscribed circle was calculated. Special device was fabricated to simulate the cyclic fatigue fracture of NiTi file in the curved canal,. On this device, NiTi files were rotated (300rpm) with different pecking distances (3 mm or 6 mm and with different motions (static motion or dynamic pecking motion). Time until fracture occurs was measured. The results demonstrated that cross-sectional area didn't have any effect on the time of file fracture. Among the files, Profile(R) took the longest time to be fractured. Between the pecking motions, dynamic motion took the longer time to be fractured than static motion. There was no significant difference between the pecking distances with dynamic motion, however with static motion, the longer time was taken at 3mm distance. In this study, we could suggest that dynamic pecking motion would lengthen the time for NiTi file to be fractured from cyclic fatigue.
Citrus sinensis ; Fatigue* ; Fractures, Stress

The purpose of this in vitro study was to evaluate the effect of surface defects and cross-sectional configuration of NiTi rotary files on the fatigue life under cyclic loading. Three NiTi rotary files (K3(TM), ProFile(R), and HERO 642(R)) with #30/.04 taper were evaluated. Each rotary file was divided into 2 subgroups: control (no surface defects) and experimental group (artificial surface defects). A total of six groups of each 10 were tested. The NiTi rotary files were rotated at 300rpm using the apparatus which simulated curved canal (40 degree of curvature) until they fracture. The number of cycles to fracture was calculated and the fractured surfaces were observed with a scanning electron microscope. The data were analyzed statistically. The results showed that experimental groups with surface defects had lower number of cycles to fracture than control group but there was only a statistical significance between control and experimental group in the K3(TM) (p<0.05). There was no strong correlation between the cross-sectional configuration area and fracture resistance under experimental conditions. Several of fractured files demonstrated characteristic patterns of brittle fracture consistent with the propagation of pre-existing cracks. This data indicate that surface defects of NiTi rotary files may significantly decrease fatigue life and it may be one possible factor for early fracture of NiTi rotary files in clinical practice.
Fatigue* ; Fractures, Stress*

The purpose of this in vitro study was to compare the effects of root canal debridement following rotary Ni-Ti instruments with positive versus negative rake angle. Seventy sound, extracted human anterior teeth & premolars were randomly divided into four groups. The used rotary instruments were Ni-Ti HERO 642(Micro-Mega in France, 20 specimen), Ni-Ti ProFile(Maillefer, Ballaigues, Switzerland, 20 specimen), stainless steel engine reamer(Mani, Matsutani Seisakusho Co.,Japan, 20 specimen) and negative control group(10 specimen) was only extirpated with barbed broach(Mani, Matsutani Seisakusho Co.,Japan) Group 1 & 2 teeth were prepared to a #40 at the apex followed by 1 mm using crown-down technique. Group 3 teeth were instrumented from a #15 to a #40 in sequential order. After preparation and final irrigation, the roots split longitudinally into a bucco-lingual direction. Root halves were cross-sectioned in apical third portion again. all root specimens were prepared for SEM investigation & photographed. Separate evaluations were undertaken for smear layer on prepared walls with a five score-index for each using reference photograph in root halves. the penetration depth of smear layer into dentinal tubules was also estimated in the other halves. the following results were obtained : 1. Smear layer was observed on all the prepared walls with three experimental groups except negative control group 2. Smear layer characteristics 1) HERO 642 groups showed snowy & dusty appearance & were observed only few some dentinal tubuli open on the prepared walls, and the penetration depth of it into dentinal tubules may be 1-2 microm thick. 2) ProFile groups showed shiny & burnished appearance & complete root canal wall covered by a homogenous smear layer with no open dentinal tubuli and penetration depth of it into dentinal tubules may be 1-2 microm thick. 3) Engine reamer groups showed obviously file's passed tracks on the prepared walls & were observed complete root canal wall covered by a homogenous smear layer with no open dentinal tubuli. The results revealed that a completely clean root canal could not be achieved regardless of positive & negative rake angle, which is in accordance with the majority of studies on root canal cleanliness. In conclusion, throughout irrigation with antibacterial solutions or chelating agents is recommended to remove the smear layer on prepared canal walls.
Bicuspid ; Chelating Agents ; Debridement ; Dental Pulp Cavity ; Dentin ; Electrons ; France ; Humans ; Nickel ; Smear Layer ; Stainless Steel ; Switzerland ; Titanium ; Tooth ; Track and Field

The final preparation (MAF) size in infected root canals is still controversial. Nonetheless, recent studies demonstrated that larger apical preparation sizes produces a greater reduction in remaining bacteria and dentinal debris as compared to smaller apical preparation sizes. Therefore, clinicians should be practiced with treatment strategies guided by evidence-based information, especially in infected/failed root canals.
Bacteria ; Dental Pulp Cavity ; Dentin ; Tooth Apex

OBJECTIVES: The purpose of this retrospective study was to evaluate the success rate of intentionally replanted mandibular second molar with C-shaped canal configurations and to access the impact of preoperative periapical lesion on the success of intentional replantation procedure. MATERIALS AND METHODS: This retrospective chart review study evaluated 52 intentionally replanted mandibular second molar teeth treated at Seoul National University Dental Hospital Department of Conservative Dentistry from January 2005 to December 2007. Seventeen teeth were lost for the follow-up, and another 6 teeth did not meet inclusion criteria of C-shaped root canal configurations. Healing outcome such as success, uncertain healing, and failure after follow-up was evaluated by clinical criteria and radiographs. RESULTS: The overall success rate was 72.4% for the 29 intentionally replanted C-shaped mandibular second molars. The success rate of replanted teeth with preoperative periapical lesions was similar to that of replanted teeth which have no periapical lesions. CONCLUSIONS: Therefore, root canal treatment failure on C-shaped mandibular second molar can be predictably treated by intentional replantation regardless of the presence of periapical lesion.
Dental Pulp Cavity ; Dentistry ; Follow-Up Studies ; Hospital Departments ; Intention ; Molar ; Replantation ; Retrospective Studies ; Tooth ; Treatment Failure

The purposes of this study were firstly to identify the microbial species on gutta-percha (GP) cones exposed at clinics using polymerase chain reaction, and secondly to evaluate the short-term sterilization effect of three chemical disinfectants. It also evaluated the alteration of surface texture and physical properties of GP cones after 5-min soaking into three chemical disinfectants. 150 GP cones from two endodontic departments were randomly selected for microbial detection using PCR assay with universal primer. After inoculation on the sterilized GP cones with the same microorganism identified by PCR assay, they were soaked in three chemical disinfectants: 5% NaOCl, 2% Chlorhexidine, and ChloraPrep for 1, 5, 10, and 30 minutes. The sterilization effect was evaluated by turbidity and subculture. The change of surface textures using a scanning electron microscope and the tensile strength and elongation rate of the GP cones were measured using an Instron 5500 (Canton). Statistical analysis was performed. Four bacterial species were detected in 29 GP cones (19.4%), and all the species belonged to the genus Staphylococcus. All chemical disinfectants were effective in sterilization with just 1 minute soaking. On the SEM picture of NaOCl-soaked GP cone, a cluster of cuboidal crystals was seen on the cone surface. The tensile strength of NaOCl-soaked group was significantly higher than the other groups (p < 0.05). Also, all disinfectants significantly increased the elongation rate of GP cones compared to the fresh GP cone (p < 0.05). Present data demonstrate that three chemical disinfectants are useful for rapid sterilization of GP cone just before obturation.
Chlorhexidine ; Disinfectants ; Disinfection* ; Gutta-Percha* ; Polymerase Chain Reaction ; Staphylococcus ; Sterilization* ; Tensile Strength

The aim of this in vitro study was to evaluate the suitability of using chitosan, poly (lactide-co-glycolide) (PLGA), and polymethyl methacrylate (PMMA) to control the release of chlorhexidine digluconate (CHX) from a prototype of controlled release drug device (CRD) for root canal disinfection. Four different prototypes with different formulations were prepared. Group A (n = 12); The device (absorbent paper point) was loaded with CHX as control. Group B (n = 12); same as group A, but the device was coated with chitosan. In Groups C and D, the device was treated in the same way as group A and then coated three times with 5% PMMA (Group C, n = 12), or coated three times with 3% PLGA (Group D, n = 12). The devices were randomly allocated to experimental groups of 12 each. All CRD prototypes were soaked in 3 mL distilled water. The concentrations of CHX were determined using a UV spectrophotometer. The surface characteristics of each prototype were observed using a scanning electron microscope. The result showed that release rate of CHX was the greatest in the non-coated group, followed by the chitosan-coated group, the PLGA-coated group, and the PMMA-coated group (P < 0.05). Pores were observed on the surface of the prototypes that were coated with PLGA and PMMA. When the pore size was smaller, the release rate was lower. This data indicate that polymer coating can control the release rate of CHX from the CRD prototypes.
Chitosan ; Chlorhexidine* ; Dental Pulp Cavity* ; Disinfection* ; Polymers* ; Polymethyl Methacrylate ; Water

Peri-implantitis is the most common reason for a late failure and can occur even after years of successful osseointegration. The role of microbial plaque accumulation in the development of peri-implantitis has been well documented. On the other hand, the ideal method of implant surface decontamination to re-establish the health of peri-implant tissue remains to be determined. Removal of bacterial deposits is essential in the treatment of peri-implant infections, and various therapeutic approaches have been described in the literature, including mechanical debridement, disinfection with chemotherapeutic agents, and laser therapy. Recently, there has been a plenitude of scientific data regarding the use of laser irradiation to achieve titanium surface decontamination. Thus, research is focusing on lasers' potential use in the treatment of peri-implantitis. The aim of this literature review is to analyze and evaluate the efficacy of laser therapy for the treatment of peri-implantitis.
Debridement ; Decontamination ; Dental Implants ; Disinfection ; Hand ; Laser Therapy* ; Osseointegration ; Peri-Implantitis* ; Titanium

The aim of this in vitro study was to evaluate the cleaning efficacy of various irrigation methods in the mandibular mesial roots. The forty five mesial root canals were shaped by Profile .06 instruments to apical size #30 and irrigated with 5 ml of 3.5% NaOCl. The teeth were divided into 3 groups and irrigated finally for 1 minute; Group 1: syringe irrigation, Group 2: ultrasonic irrigation, Group 3: RinsEndo irrigation. After histological processing, the cross sections of apical 1, 3, and 5 mm level were examined with an optical microscope. The cleanliness values of canals and isthmuses were calculated and analyzed by Mann-Whitney U test. 1. There were no significant differences in both canal and isthmus cleanliness between syringe irrigation and ultrasonic irrigation except 5 mm level of isthmus. 2. RinsEndo irrigation had significantly higher canal cleanliness values than syringe irrigation at 1 mm and 3 mm levels (p < 0.05). Also, RinsEndo irrigation had significantly higher isthmus cleanliness values than syringe irrigation at all levels evaluated (p < 0.05). 3. There were no statistical differences in both canal and isthmus cleanliness between ultrasonic irrigation and RinsEndo irrigation except 3 mm level of canal. From this study, RinsEndo irrigation can be useful as an additional irrigation procedure.
Dental Pulp Cavity ; Molar ; Syringes ; Tooth ; Ultrasonics