Effect of maleic acid and ethylenediaminetetraacetic acid on the shear bond strength of RealSeal SE sealer to root canal dentin.

Aim of this study was to evaluate the effect of 7% maleic acid and 17% ethylenediaminetetraacetic acid (EDTA) on the shear bond strength of RealSeal SE sealer to root canal dentin. Twenty incisors were split into coronal, middle and apical third and were treated in the following manner: Group 1: 5 ml of saline (1 minute). Group 2: 2.5% sodium hypochlorite (5 ml/min) followed by 79% maleic acid (5 ml/min). Group 3: 2.5% sodium hypochlorite (5 ml/min) followed by 17% EDTA (5 ml/min). Sealer was the placed on the root dentin and samples were subjected to bond strength measurement. There was no significant difference in bond strength between maleic acid and 17% EDTA in coronal & middle third. However, in apical third, 7% maleic acid showed higher bond strength. Least bond strength was observed with saline. Bond strength was maximum in apical third for both 7% maleic acid and 17% EDTA.

Searching for Archaea in infections of endodontic origin.

Archaea is a highly diverse group of prokaryotes, whose members have been traditionally recognized as extremophiles. Recently, some of these microorganisms have also been found to thrive in nonextreme environments, including the human body. Methanogenic archaea have been detected in samples from subgingival plaque associated with periodontal disease and a pathogenetic role is suspected. The purpose of this study was to survey samples taken from different types of endodontic infections for the presence of archaea. Samples were taken from untreated and treated root canals associated with asymptomatic chronic periradicular lesions as well as from cases diagnosed as acute periradicular abscesses. Overall, 96 samples were obtained. DNA from samples was extracted by using two different protocols and used as template for polymerase chain reaction amplification using oligonucleotide universal primers for the domains Archaea or Bacteria. Samples were also checked for the presence of spirochetes by making use of a group-specific primer. While bacteria were present in all samples, no case yielded archaeal DNA. Spirochetes occurred in a high number of cases. Our findings suggested that members of the Archaea domain are not members of the microbiota present in different types of endodontic infections and thereby may not be implicated in the etiology of apical periodontitis.

Efficacy of several concentrations of sodium hypochlorite for root canal irrigation.

Sodium hypochlorite (NaOCl) has been recommended for irrigation during root canal preparation. This investigation used scanning electron microscopy to examine instrumented and uninstrumented surfaces in the middle third of root canals following the use of several concentrations of NaOCl (5.25%, 2.5%, 1.0%, and 0.5%). NaOCl was delivered with either an endodontic irrigation needle or an ultrasonic device. All of the concentrations of NaOCl with either delivery system were very effective in flushing out loose debris from the root canals. A smear layer with some exposed dentinal tubules was seen on all instrumented surfaces regardless of concentration of NaOCl or irrigation device. NaOCl in concentrations of 5.25%, 2.5%, and 1% completely removed pulpal remnants and predentin from the uninstrumented surfaces. Although 0.5% NaOCl removed the majority of pulpal remnants and predentin from the uninstrumented surfaces, it left some fibrils on the surface.

The use of bone imaging to detect a periapical lesion of endodontic origin.

This article reports the detection of a lesion of dental origin in the mandible of a 41-yr-old male patient during a routine bone scan used as a follow-up to cancer therapy. Unfortunately, more than 1 yr passed before the patient's signs and symptoms became severe enough for a definitive diagnosis to be made. A comprehensive dental examination is indicated for patients with positive bone scans in the area of the oral cavity. The use of bone imaging can be recommended to complement the dental examination of high risk patients with suspected metastasis or when all routine dental diagnostic measures are inconclusive.

Detection of immunoglobulins from explant cultures of periapical lesions.

The presence of immunoreactive cells in periapical inflammatory lesions suggests that immune responses participate in the disease process. The purpose of this study was to determine the presence and concentration of immunoglobulins in the supernatant fluids of explant cultures of periapical lesions. Ninety periapical lesions that had been contiguous with the apex of a root were removed and maintained in explant cultures for 96 h. Tissue culture medium was replenished at 24, 48, 72, and 96 h. Double diffusion in agarose assays demonstrated the presence of IgG in 100% of the 24-h supernatant fluids and IgA in 65% of the 24-h supernatant fluids. However, IgM was not detected. Radial immunodiffusion assays were used to detect and quantitate IgG, IgA, and IgM in samples of 24-h supernatant fluids from 90 explant cultures. IgG was the predominant immunoglobulin followed by IgA. A radioimmunosorbent test was used to detect and quantitate IgE in samples of 24-h supernatant fluids from 90 explant cultures. Forty of the 90 supernatant fluids contained measurable IgE. All detected immunoglobulins decreased in concentration in daily supernatant fluids with time (24, 48, 72, and 96 h) in the culture.

Biosynthesis of IgG in periapical lesion explant cultures.

The presence of immunoglobulins has been demonstrated in periapical inflammatory lesions associated with endodontic disease. The purpose of this study was to determine if IgG is synthesized in vitro in explant cultures of untreated periapical inflammatory lesions and to determine the level of IgG in isolated samples. Periapical lesions associated with infected root canals were removed from the roots and cultured in tissue culture medium containing tritiated amino acids. Supernatant fluids from the explant tissue cultures were passed through staphylococcal protein A affinity columns to isolate IgG. When the staphylococcal protein A eluents (24-h samples) from six periapical lesions were used in double diffusion in agarose assays, the presence of IgG was demonstrated in all the samples. Radial immunodiffusion assays to quantitate the IgG in staphylococcal protein A eluents showed that the levels of IgG detected in each successive daily supernatant fluid always decreased or else fell below the lower limits of detection. The in vitro biosynthesis of IgG in explant cultures of periapical lesions was demonstrated by the incorporation of tritiated amino acids into isolated IgG.

Reactivity of IgG from explant cultures of periapical lesions with implicated microorganisms.

The presence of IgG in periapical inflammatory lesions suggests that immune responses participate in the disease process. The purpose of this investigation was to study the reactivity of IgG from the supernatant fluids of explant cultures of periapical lesions with microorganisms implicated in infections of endodontic origin. Ninety periapical lesions that had been contiguous with the apex of a root were removed and maintained in explant cultures. A dot-enzyme-linked immunosorbent assay (dot-ELISA) was used to demonstrate the presence of IgG in the supernatant fluids of the explant cultures reactive with a panel of microorganisms associated with infections of endodontic origin. The percentages of reactivity by dot-ELISA follow: Bacteroides intermedius (84%), B. buccae (12%), Porphyromonas (Bacteroides) gingivalis (50%), P. endodontalis (58%), P. asaccharolyticus (17%), Peptostreptococcus micros (44%), P. anaerobius (26%), Eubacterium alactolyticum (34%), Fusobacterium nucleatum (14%), and Actinomyces israelii (6%). At least one of the three species of B. intermedius, P. gingivalis, or P. endodontalis tested gave a positive dot-ELISA with 89% of the supernatant fluids from explant cultures of periapical lesions. A lack of cross reactivity of IgG in supernatant fluids from explants of periapical lesions was demonstrated for the four strains of black-pigmented Bacteroides/Porphyromonas by dot-ELISA.

Bacteria in the apical 5 mm of infected root canals.

Ten freshly extracted teeth which had carious pulpal exposures and periapical lesions contiguous with the root apex were placed inside an anaerobic chamber and the apical 5 mm of the root canals cultured. In addition to anaerobic incubation, duplicate cultures were incubated aerobically. Fifty strains of bacteria from the 10 root canals were isolated and identified. The most prominent bacteria cultured from the 10 root canals were Actinomyces, Lactobacillus, black-pigmented Bacteroides, Peptostreptococcus, nonpigmented Bacteroides, Veillonella, Enterococcus faecalis, Fusobacterium nucleatum, and Streptococcus mutans. Of the 50 bacterial isolates, 34 (68%) were strict anaerobes. This study demonstrates the presence of predominantly anaerobic bacteria in the apical 5 mm of infected root canals in teeth with carious pulpal exposures and periapical lesions.

Adult pulpal diagnosis. I. Evaluation of the positive and negative responses to cold and electrical pulp tests.

This study investigated the positive and negative responses of 1488 teeth in 60 patients to two electric pulp testers and a cold thermal pulp test. Three subgroups of known pulpless or pulpally diseased teeth (teeth receiving root canal therapy, teeth with root canal fillings, or teeth with confirmed associated apical radiolucencies) were identified and their responses evaluated separately. Testing was performed on two tooth surfaces, the facio-occlusal and faciocervical, and on all restorations. The gingival tissue of each patient also was tested using both electrical tests. The primary findings were: (a) teeth not responding to cold and either not responding or responding at readings greater than the tissue response to electrical had a high probability of being in the known pulpless or pulpally diseased subgroups; (b) the only false positive responses to cold in the three subgroups were in multirooted teeth with probable vital tissue remaining in at least one canal; and (c) in the three subgroups, if the false positive responses to electrical that responded at levels higher than the patient's tissue response were considered to be negative responses, the difference in false positives between cold and electrical became not statistically significant (p = 0.07).

Occurrence of Candida albicans in infections of endodontic origin.

Microorganisms are recognized as the etiological agent for the majority of pulpal and periradicular disease. Although bacteria have been the most studied, fungi have also been associated with infected root canals. The purpose of this study was to evaluate the contents of infected root canals and aspirates of cellulitis/abscesses of endodontic origin for the presence of Candida albicans using the polymerase chain reaction (PCR). PCR primers specific for the 18S ribosomal RNA gene of C. albicans were used to survey 24 samples taken from infected root canals and 19 aspirates from periradicular infections of endodontic origins. The presence of C. albicans was detected in 5 of 24 (21%) samples taken from root canals, but none was detected in the periradicular aspirates. The results indicate that PCR is an extremely sensitive molecular method that may be used to identify C. albicans directly in samples from infections of endodontic origin.

An analysis of canal centering using mechanical instrumentation techniques.

The purpose of this study was to compare canal transportation in moderately curved canals using mechanical instrumentation systems. Mesial roots of mandibular first or second molars were mounted in resin using a modified Bramante muffle system and divided into four groups. The roots were cross-sectioned 2 mm from the working length and at the height of root curvature. Tracings of the canal were made from preinstrumentation slides of the cross-sections. The canals were prepared using ProFile Series 29 rotary instruments, Quantec 2000 rotary instruments, Flex-R files in the Endo Gripper contra-angle handpiece, and Shaping Hedstrom files in the M4 contra-angle handpiece. Tracings of the prepared canals were made onto the originals from postinstrumentation slides. A canal centering ratio was calculated along the line of maximum transportation. Quantec 2000 rotary instruments yielded significantly greater transportation at the apical level when compared with the Profile Series 29 system. There were no other significant differences in transportation at either level. There were no differences in the direction of canal transportation between instrument systems, and the direction of canal transportation was not related to the direction of canal curvature. Canal preparation time was shortest with Profile Series 29 system followed by Flex-R files in the Endo Gripper, Quantec 2000, and Shaping Hedstrom files in the M4.

Geographical differences in bacteria detected in endodontic infections using polymerase chain reaction.

The polymerase chain reaction (PCR) is an innovative nucleic acid-based assay that has the highest sensitivity of any microbiological technique for the detection of bacteria. The purpose of this study was to use PCR to detect the presence of specific species of bacteria in samples collected from two geographical locations. Microbial samples from abscesses of endodontic origin were collected from patients in Portland, Oregon, and Rio de Janeiro, Brazil. PCRs with species-specific oligonucleotide primers for the 16S ribosomal RNA gene were used for detection of the bacteria after DNA extraction from each clinical sample. Statistical analysis revealed that there was a significant difference in detection of the bacteria between the two geographical locations for Prevotella intermedia, Prevotella nigrescens, Prevotella tannerae, Fusobacterium nucleatum, and Porphyromonas gingivalis, but not for Porphyromonas endodontalis, Fusobacterium necrophorum, and Enterococcus faecalis. These results suggest that differences in bacteria detected or cultured in studies can be associated with geographical location.

Radicular temperatures associated with thermoplasticized gutta-percha.

Thermoplasticized gutta-percha has been used to obturate root canals. The continuous wave of condensation technique uses the System B Heat Source with the choice of different-sized pluggers. The purpose of this study was to measure the temperatures within the root canal and on the root surface at different radicular levels while using the System B Heat Source. Fine, Fine-Medium, and Medium pluggers were evaluated at temperature settings of 200 degrees C, 250 degrees C, and 300 degrees C. The Obtura II gutta-percha delivery system following the manufacturer's instructions and ultrasonically thermoplasticized gutta-percha were used for comparative purposes. The highest mean temperature change on the internal root surface was 74.19 degrees C with the system B at the 6 mm level (6 mm coronal to working length) when the Fine-Medium plugger was set at 300 degrees C. The lowest mean temperature change on the internal root surface was 2.09 degrees C at the 0 mm level (at working length) when the F plugger was set at 200 degrees C. With the Obtura II, the lowest mean internal temperature change was 5.22 degrees C at the 0 mm level, whereas the highest mean internal temperature change was 26.63 degrees C at the 6 mm level. With ultrasonic lateral compaction the lowest mean internal temperature change was 5.01 degrees C at the 0 mm level, whereas the highest mean internal temperature change was 28.95 degrees C at the 6 mm level. At no time did the System B, the Obtura II, or ultrasonic delivery of warm gutta-percha exceed an increase of 10 degrees C at any thermocouple level on the external root surface.

Evaluation of root thickness in curved canals after flaring.

Root thickness in the mesial canals of lower first and second molars was compared before and after flaring by using a muffle system. Gates Glidden burs or M-Series Canal Openers were used with either a straight up-and-down motion or with an anticurvature motion. It was found that Gates Glidden burs used straight up and down removed statistically more dentin at the level of the furcation than Canal Openers used straight up and down or in an anticurvature fashion. At a level 2 mm apical to the furcation, Gates Glidden burs used in an anticurvature fashion removed statistically more dentin than any other method tested.

Effects of a carbon dioxide laser on human root dentin.

The effects of the Luxar LX-20 CO2 dental laser on resected apical root dentin were examined using stereomicroscopy and scanning electron microscopy. The surfaces of 2-mm-thick sections of dentin from freshly extracted human teeth were exposed to CO2 laser radiation. Fluences used ranged from 2.1 to 625.0 J/cm2. The effects of the laser energy on the dentin ranged from no visible effects, to charring, cracking, cratering, and glazing. The most dramatic effect was cracking. Cracking was evident on all specimens having any visible modification of the dentin. A prototype-curved laser tip was used and compared with a standard straight tip. The curved tip did not deliver laser energy to the dentin as efficiently as a straight tip. CO2 laser radiation did not consistently obliterate dentin tubules.

Practical application of infection control in endodontics.

The transmission of infections in an endodontic practice is a significant concern for both patients and dental health care providers. This article offers a review and practical application of infection control methods in the practice of endodontics.

Comparison of ultrasonic and high-speed-bur root-end preparations using bilaterally matched teeth.

The purpose of this study was to compare ultrasonic and high-speed-bur root-end preparations. Seventy-six roots from 29 bilaterally matched pairs of human teeth in cadavers were used in this study. In group 1 ultrasonic preparations were made in 38 roots and filled with amalgam. In group 2 high-speed bur preparations were made in 38 roots and filled with amalgam. The size of the bony crypt was measured and the teeth were extracted and radiographed mesial-distally and buccal-lingually. None of the root-end preparations resulted in root perforation. The mean mesial-distal minimum depth of ultrasonic and high-speed bur preparations were 2.11 mm and 1.39 mm, respectively. The mean buccal-lingual minimum depth of preparation was 2.51 mm for the ultrasonic and 2.05 mm for the high-speed bur preparations. The depth of the ultrasonic preparations was significantly greater for both measurements. A significantly greater bevel angle was associated with the bur preparations, 35.1 degrees versus 16.0 degrees for the ultrasonic preparations. The incidence of ultrasonic root-end preparations deviating from the uninstrumented canal spaces was found to be 2.6%. All bur root-end preparations were at an acute angle to the long axis of the root. The bony crypt size for bur preparations was significantly greater than that for ultrasonic preparations.

Comparison of dentinal crack incidence and of post removal time resulting from post removal by ultrasonic or mechanical force.

The purpose of this study was to compare the frequency of canal and intradentin cracks after intraradicular post removal using ultrasonic instrumentation or the Gonan post removal system. Sixty cadaver teeth were divided into 4 groups of 15 teeth each: group 1, ultrasonic removal; group 2, Gonan post removal system; group 3, cemented posts not removed; and group 4, no posts. Groups 1 and 2 were contralateral matched pairs. Para Posts were placed in groups 1, 2, and 3 to 7 mm apical to the cementoenamel junction and luted with ZnPO4 cement. The time required for post removal in groups 1 and 2 was recorded. The teeth were extracted, sectioned, and examined. Canal and intradentin cracks were mapped, and their frequency was recorded at each level. There were statistically more cracks present in the ultrasonic group than the no post group. There were no other differences that reached statistical significance. It took significantly longer for post removal using the ultrasonic tip versus the Gonan system.

A comparison of canal centering ability of four instrumentation techniques.

The purpose of this study was to compare three engine driven (nickel-titanium) NiTi instrument systems with hand files for their effect on canal transportation. Mesial roots of mature lower first molars with separate canals were paired on the basis of curvature and morphology. Canal lengths were standardized to 11 mm from orifice to apical foramen. Profile, Lightspeed, McXIM, and Flex-R hand filing techniques respectively were randomly assigned to one of the four canals of each tooth pair. The roots were mounted and sectioned at 1 mm, 3 mm, and 5 mm from working length using a modified Bramante technique. All sections were video imaged preoperatively after instrumentation to size #30 and after final instrumentation to size #40. The images were computer analyzed for changes in canal area and centering at each stage of instrumentation. Preparation time was also recorded. Data were analyzed using ANOVA. The NiTi systems remained better centered in the canal than stainless steel hand files. There were no significant differences among the NiTi systems at any level. The difference between hand filing and the NiTi techniques was more pronounced at size #40 than at size #30. The NiTi systems were all significantly faster than hand filing. No significant differences in preparation were found between the NiTi systems when canals were instrumented to the size nearest #40.

Development of an anaerobic bacterial leakage model.

The majority of bacteria associated with infections of endodontic origin are strict anaerobes. The purpose of this study was to develop an endodontic microleakage model using strict anaerobic bacteria in a two-chamber system. Nine species of anaerobic bacteria were tested for viability and detection by either turbidity or color change of the broth. A survey of pH chromogenic substrates revealed that bromcresol purple (pH 5.2 = yellow, pH 6.8 = purple) could be used as a chromogenic indicator to detect the growth of anaerobic bacteria. Peptone-yeast extract-glucose broth (PYG) and brain heart infusion broth (BHI) were each used alone and with bromcresol purple (bpPYG, bpBHI) in this study. Fusobacterium nucleatum and F. necrophorum were viable in all four media for > 2 wk and produced both turbidity and a color change after only 1 day of incubation. Veillonella parvula in either bpBHI or BHI and Peptostreptococcus anaerobius in either bpPYG or BHI were viable for > 2 wk and showed a color change or turbidity after 1 or 2 days. The results indicate that leakage of strict anaerobes may be evaluated in a two-chamber system.