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Growth inhibitory activity of gutta-percha points containing root canal medications on common endodontic bacterial pathogens as determined by an optimized quantitative in vitro assay.

Gutta-percha points containing calcium hydroxide, zinc oxide (ZnO), a mixture of ZnO and chlorhexidine (ZnO/CHX), iodine-polyvinylpyrrolidone (ZnO/J-PVP), or a mixture of CHX and J-PVP and ZnO (ZnO/CHX/J-PVP) were tested for their ability to inhibit growth of pure cultures of bacterial species commonly involved in endodontic infections (Peptostreptococcus micros, Streptococcus intermedius, Enterococcus faecalis, and Porphyromonas gingivalis). To quantitate growth inhibition, an in vitro assay was established that controlled for important parameters of root canal infection. Approximately 10(7) bacteria per assay were suspended in diluted human serum and co-incubated with the gutta-percha points in an anaerobic atmosphere for up to 2 wk. Aliquots used for determination of colony counts were taken on days 0, 1, 2, 4, 7, and 14 of incubation. As judged by colony-forming unit reduction kinetics and final counts, calcium hydroxide had better growth inhibitory activity than ZnO/CHX, ZnO/J-PVP, and ZnO alone for all bacteria tested except Peptostreptococcus micros. The combination of CHX and J-PVP with ZnO did not render results different from those of ZnO/CHX or ZnO/J-PVP. The results of this study support the introduction of standardized assays for testing antibacterial properties of root canal medications under conditions that more closely resemble those encountered in endodontal infections.

Anti-Infective Agents, Local↗

Anaphylactic shock during endodontic treatment due to allergy to formaldehyde in a root canal sealant.

A 41-yr-old patient experienced an anaphylactic shock reaction caused by formaldehyde in a root canal sealant during endodontic treatment. The clinical events, positive skin tests, and a high level of immunoglobin E to formalin RAST (class 4) suggest the involvement of immunoglobin E-dependent mechanisms toward formaldehyde. This very infrequent observation in endodontic therapy focuses attention on the different pathological manifestations related to formalin, their mechanisms, and the prevention possibilities in dentistry.

Adult↗

Measurement of endodontic file lengths: a density profile plot analysis.

The purpose of this study was to evaluate measurements of endodontic files of known length and diameter using a density profile plot analysis of digital images. Ten single-rooted teeth with relatively straight roots in cadaver specimens were used. The crowns of the teeth were removed and a rectangular orthodontic wire, 5.13 mm in length, was placed horizontally on the occlusal surface to serve as a calibration reference point. The #8, #10, #15, and #20 FlexOFiles were measured to the nearest 0.5 mm and then placed to four working lengths that terminated within the apical third of each root. A GE X-ray unit and a Schick CDR #2 sensor were used to digitally acquire 160 images. The digital images were placed in random order and an independent, blinded investigator determined the file length using a density profile plot analysis. The measurements generated by the histogram analysis (experimental) were compared with the original clinical measurements. The paired t test, intraclass correlation coefficient, and the Bradley-Blackwood test were used to assess reliability. The results revealed that the means of the experimental measurements of all file sizes were within 0.5 mm of the known lengths and were always shorter than the known lengths. Also, the larger the file size the less deviation from the known lengths: #20, -0.16 mm (p = 0.0001); #15, -0.21 mm (p = 0.0001); #10, -0.34 mm (p = 0.0001); and #8, -0.45 mm (p = 0.0001). This study demonstrated that the density profile plot analysis might be a useful adjunct for the measurement of endodontic file lengths on a digital image.

Analysis of Variance↗

An evaluation of endodontically treated vertical root fractured teeth: impact of operative procedures.

Vertical root fractures of endodontically treated teeth are a frustrating complication that leads to extraction. The aim of the current survey was to evaluate the role of operative procedures in the etiology of this complication. A total of 154 endodontically treated vertical root fractured teeth were cleaned and washed after extraction and maintained in individual vials. Periapical radiographs before extraction, clinical findings and previous operative procedures were recorded. A post was observed in 95 teeth (61.7%), with 66 of these ending at the coronal third of the root. Most were screw posts of the Dentatus type (n = 64) and tapered cast posts (n = 14). A full crown was observed in 118 teeth, and 65 of these (55%) were extracted between 1 to 5 yr after final restoration. In 24 crowned teeth extraction was conducted within 1 yr after restoration and in 28 teeth after >5 years. It was concluded that post placement and root canal treatment are the major etiological factors for root fractures. Because signs and symptoms can appear years after the operative procedures in the root have been completed, coronal restorations would not interfere with the correct clinical diagnosis of vertical root fractures. Frequent recalls are recommended to diagnose vertical root fractures early, especially in susceptible teeth, such as premolars and mesial roots of mandibular molars.

Bicuspid↗

Effectiveness of three endodontic irrigants at various tubular depths in human dentin.

Bacteria from infected root canals can invade dentinal tubules, thus dentin disinfection is an important aspect of endodontic therapy. This study compares three endodontic irrigants for efficiency in killing bacteria established within human dentinal tubules. Root canals in extracted teeth were prepared and sterilized. Broth cultures of Enterococcus faecalis were allowed to grow within the canals to penetrate dentinal tubules. The infected canals were exposed individually to each of the irrigants for 1 min. Irrigants were 0.525% sodium hypochlorite, Tubulicid (0.2% EDTA), and 0.12% chlorhexidine (Peridex). Sterile water was the control. Viable bacteria were analyzed by drilling incrementally into dentin from the cementum toward the canal. Smaller diameter drills were used for each depth. Shavings were cultured at three depths, for each of three root levels: coronal, midroot, and apical. Although considerable variation occurred between roots, sodium hypochlorite seemed to be superior. Tubulicid and Peridex were better than water. More bacteria remained viable at greater distances from the pulp. These observations apparently apply to all levels in the canal.

Analysis of Variance↗

Analysis of arylsulfatases A and B, acid phosphatase, lactate dehydrogenase, and aspartate transaminase in chronic periapical lesions of endodontic origin.

Attempts were made to detect and measure the activities of arylsulfatases. A&B acid phosphatase, lactate dehydrogenase, and glutamate oxaloacetate transaminase (aspartate transaminase) enzymes in human chronic lesions of endodontic origin. Thirteen periapical lesions of endodontic origin and 11 noninflamed control periapical tissues were obtained. The specimens were carried to the laboratory on liquid nitrogen and kept at -70 degrees C. Samples were thawed, homogenized, and then assayed for enzyme activities. The specific activities of arylsulfatase A (nmol/hr/mg protein) were 55.0+/-10.7 (chronic lesions) vs. 3.4+/-2.2 (controls) (p < 0.01). Arylsulfatase B specific activities (nmol/hr/mg protein) were 50.3+/-6.4 (chronic lesions) vs 91.8+/-18.4 (controls). Total acid phosphatase activities (mU/mg protein) were 45.8+/-6.6 (chronic lesions) vs. 26.8+/-3.1 (controls). Lactate dehydrogenase activities (Berger-Broida units/mg protein) of the chronic periapical lesions were significantly higher than the control group (362+/-63.2) vs. (140+/-46.0) (p < 0.05). There was no significant difference between the specific activities of aspartate transaminase in chronic lesions and the control group (68.0+/-14.5) vs. (53.0+/-10.4) mU/mg protein).

Acid Phosphatase↗

Relationship between design features of endodontic instruments and their properties. Part 3. Resistance to bending and fracture.

Stainless-steel prototypes characterized by five different cross-sectional shapes (square, triangular, rhomboidal, "S"-shaped, and the cross-sectional design of H-type files) and three different number of flutes (16, 24, and 32) were used for investigation of the relationship between design features and the resistance to bending and fracture of root canal instruments. Both resistance to bending (bending moment) and resistance to fracture (angular deflection and torque) were determined in accordance to ISO 3630-1. Numbers 15, 25, and 35 prototypes were tested with a sample size of 10 instruments each. Whereas prototypes with the rhombus-shaped cross-sectional design displayed the lowest resistance to bending, those of the square cross-section showed the greatest. In general, S-shaped prototypes and those with the H-type cross-section achieved lower angular deflection than all other prototypes, whereas those with the triangular cross-sectional shape and 32 flutes reached the greatest angular deflection. Overall, rhombus-shaped prototypes showed lower torque values than all other prototypes. Results indicate that bending and torsional properties of endodontic instruments are mainly influenced by their cross-sectional design. Moreover, these properties are also affected by the number of flutes and the manufacturing process (twisted or milled) of endodontic instruments.

Analysis of Variance↗

Detoxification of endotoxin by endodontic irrigants and calcium hydroxide.

The effects of endodontic irrigants and calcium hydroxide on lipopolysaccharide (LPS; endotoxin) were analyzed using the highly selective technique of mass spectrometry/gas chromatography with selected ion monitoring. An aqueous solution of LPS was mixed with one of a variety of endodontic irrigants for 30 min. Because it is a commonly used interappointment dressing, calcium hydroxide was also applied to LPS for 1, 2, or 5 days. LPS inactivation was measured by quantitation of free fatty acid release. Water, EDTA, ethanol, 0.12% chlorhexidine, chlorhexidine + sodium hypochlorite, and sodium hypochlorite alone showed little breakdown of LPS. Long-term calcium hydroxide--as well as 30-min exposure to an alkaline mixture of chlorhexidine, ethanol, and sodium hypochlorite--did detoxify LPS molecules by hydrolysis of ester bonds in the fatty acid chains of the lipid A moiety.

Bacteriological Techniques↗

Effects of chlorhexidine gluconate as an endodontic irrigant on the apical seal: short-term results.

The aim of this study was to ascertain whether chlorhexidine gluconate (0.12%), used as an endodontic irrigating solution would affect the apical seal obtained when using three different root canal cements. One hundred extracted human single-canal teeth were divided into 9 experimental groups of 10 teeth each and a positive and negative group of 5 teeth each. The teeth were decoronated at the level of the cementoenamel junction, then accessed, instrumented to a Master Apical File #50, irrigated with either sterile saline, 5.25% NaOCl or 0.12% chlorhexidine gluconate, and dried using paper points. Obturation was accomplished using lateral condensation and 1 of 3 endodontic sealers: Roth's 811, AH26, or Sealapex. At 90 and 180 days after obturation apical leakage was measured using the fluid filtration method. Using the ANOVA test the results showed no significant difference in seal related to the irrigant at both the 90- and 180-day observation periods.

Analysis of Variance↗

Effects of root canal sealers on vertical root fracture resistance of endodontically treated teeth.

The aim of this study was to compare vertical forces at fracture of endodontically treated mandibular incisors obturated with different types of root canal sealer. Four groups of 10 teeth each were tested; group 1 served as positive and negative controls (five teeth each), and groups 2, 3, and 4 were obturated by lateral condensation with gutta-percha and AH Plus, Tubliseal, or Ketac-Endo, respectively. All teeth were loaded vertically using a plugger tip inserted into the canal space until fracture occurred; the load at fracture and the pattern of fracture were recorded. Statistical analysis was performed using a one-way analysis of variance and post hoc Scheffé test at the 95% level of confidence. Force at fracture of roots obturated with Ketac-Endo was significantly higher than those obturated with AH Plus and Tubliseal. Most fracture lines were in a buccolingual direction. The results suggested that Ketac-Endo strengthens endodontically treated roots and may be used for weak roots, which are likely to be susceptible to vertical root fracture.

Analysis of Variance↗

Measurement of adhesion of endodontic sealers to dentin.

The bond strength of root canal sealers to dentin seems to be an important property for maintaining the integrity of the seal of root-canal fillings. In the few studies published, various assessment methods were used so quantitative comparison is not possible. The purpose of this study was to develop an effective and easily reproducible model and to test it with nine contemporary, commercially available endodontic sealers. After slicing off the coronal 2 mm of extracted third molars, the exposed dentin served as test surfaces. The teeth were fixed with plaster in 1-inch phenolic rings. Five-mm long sections of polyethylene tubing, filled with freshly mixed sealer, were placed on the dentin and tested for shearing bond strength after setting. A custom-made holder allowed the rings to be attached to an Instron machine, activated at a cross-arm speed of 0.5 mm/min. The mean bond strength, ranged from 0 to 4.9 MPa. The sealers were ranked and those that did not differ statistically in their bond strength were grouped together. This model provides a simple and reproducible means for measuring the in vitro bond strength of endodontic sealers.

Adhesiveness↗

Failure mechanism of Hedstroem endodontic files in vivo.

Intracanal fracture of endodontic Hedstroem files (H-files) jeopardizes the outcome of endodontic therapy. The aim of this study was to evaluate the fracture mechanism of H-files after multiple in vivo uses. Five each of size #20 and #25 ISO H-files fractured during clinical use were collected from different dental clinics. Four fractured files of each size and three unused files of each corresponding size were embedded in a resin along their longitudinal axis and after metallographic grinding and polishing studied under an incident light microscope. One specimen in the fractured group was investigated under a scanning electron microscope. Light microscopy results showed that unused files were free of structural defects (cracks, pores, etc.), whereas fractured files demonstrated the presence of many cracks mostly located at the flute depth region. Secondary cracks were identified beyond the fracture plane of fractured files both with a light microscope and a scanning electron microscope. Experimental results demonstrated that fatigue is closely associated with the fracture mechanism of H-files (#20, #25) under clinical conditions.

Dental Instruments↗

The effect of an apex locator on exposure to radiation during endodontic therapy.

The objective of this study was to investigate whether the use of an electronic apex locator results in a reduction in X-ray exposure during endodontic therapy. Fifty, sound, extracted, single-rooted canine and incisor teeth were selected and randomly divided into two groups (A and B) of 25 teeth. The working length was determined radiographically with (group B) and without (group A) adjunctive use of an apex locator by one operator. After working length determination, the teeth were sectioned and the actual working length measured for comparison. For group A, 14 retake radiographs were required to determine the working length, whereas group B required no retake radiographs; this difference was highly significant (p < 0.001). The electronic apex locator was extremely accurate in locating the apical foramen with all teeth tested within 0.5 mm of the anatomical apex and 11 (44%) teeth at the apical foramen. In contrast, 15 (60%) teeth tested using radiographs alone were within 0.5 mm of the anatomical apex and only 4 (16%) teeth were actually at the anatomical apex. It was concluded that using an electronic apex locator as an aid to endodontic therapy could potentially reduce the number of diagnostic radiographs required for working length determination. Location of the apical foramen using a combination of an electronic apex locator and radiographs to determine working length is more accurate than using radiographs alone.

Chi-Square Distribution↗

Effect of drainage upon access on postoperative endodontic pain and swelling in symptomatic necrotic teeth.

The purpose of this retrospective study was to determine the effect of drainage upon access on postoperative endodontic pain and swelling in symptomatic necrotic teeth. One hundred twenty-four emergency patients participated and each had a clinical diagnosis of a symptomatic necrotic tooth with an associated periapical radiolucency. The occurrence of drainage upon access was timed and recorded. After endodontic treatment, patients received ibuprofen, acetaminophen with codeine (30 mg), and a 6-day diary to record pain, percussion pain, swelling, and number and type of pain medication taken. The majority of patients with symptomatic necrotic teeth had significant postoperative pain and required analgesic medication to manage this pain. Obtaining short-term drainage upon access (average of 1.85 min) did not significantly (p > 0.05) reduce pain, percussion pain, swelling, or the number of analgesic medications taken for symptomatic necrotic teeth with periapical radiolucencies.

Acetaminophen↗

Adhesion of endodontic sealers to dentin and gutta-percha.

Adhesion of endodontic sealers to dentin and gutta-percha offers clues into their interaction with the wall of the root canal and the filling material. In this in vitro study, four classes of endodontic sealers (Kerr, a ZOE-based sealer; Sealapex, a calcium hydroxide-based sealer; AH 26, an epoxy resin-based system; and Ketac-Endo, a glass-ionomer based sealer) were compared for their ability to bond to dentin or gutta-percha. Flat coronal dentin or gutta-percha surfaces were created by using a diamond-impregnated saw blade. Aluminum cylinders (ca. 5-mm diameter) were stabilized on the substrates with small amounts of wax and then filled with one of the sealers. After setting in 100% humidity for 24 h, their tensile bond strengths were measured. Controls were the unfilled cylinders stabilized with wax. The bond strengths and modes of failure were measured. The results were statistically analyzed by using a two-way ANOVA (materials versus substrates) and Student-Newman-Keuls test at alpha = 0.05. The results indicated that sealant bond strengths to dentin (from lowest to highest mean +/- SD, n = 10) were: Kerr 0.13 +/- 0.02; Sealapex 0.30 +/- 0.08; Ketac-Endo 0.80 +/- 0.24; AH 26 2.06 +/- 0.53 MPa. The latter two were significantly different (p < 0.05) from the first two sealers and from themselves. The sealant bond strength to gutta-percha (from lowest to highest mean +/- SD, n = 10) were: Ketac-Endo 0.19 +/- 0.01; Sealapex 0.22 +/- 0.01; Kerr 1.07 +/- 0.19; AH 26 2.93 +/- 0.29 MPa. AH 26 gave the significantly highest bonds to gutta-percha.

Adhesiveness↗

Endodontic treatment in cases of allergic reaction to rubber dam.

The prevalence and severity of latex allergies have rapidly increased recently. This article presents two cases of patients with rubber latex allergy. The patient in case A was unaware of her sensitivity to latex and presented symptoms of contact dermatitis-stomatitis during endodontic treatment. The patient in case B reported latex allergy before the initiation of the treatment and a different approach was followed. Certain aspects of latex allergy related to the endodontic treatment are discussed. Moreover, a protocol is proposed for treatment of patients with latex hypersensitivity with safety.

Aged↗

Contemporary endodontic retreatments: an analysis based on clinical treatment findings.

A prospective in vivo investigation was conducted to determine radiographic and clinical factors associated with contemporary nonsurgical endodontic retreatments. Approximately 1,100 failing endodontically treated teeth were screened to determine an appropriate treatment plan. Using magnification, 337 consecutive retreatment cases were evaluated and treated. The vast majority of the retreated cases involved multiple factors. Eighty-five percent of the cases presented with periradicular radiolucencies. Sixty-five percent of the cases demonstrated poor radiographic obturation quality. Associated pain was noted 51% of the time. Forty-two percent of the teeth had untreated canal space. It was statistically significant (Chi-square, p < or = 0.05) that additional canal space was located and treated in 89% of the cases that had previous radiographic asymmetrical obturations. Evidence of coronal leakage was noted in 13% of the retreated teeth. Tooth number, obturation materials, overfills, and previous surgical retrofillings were also recorded. Recommendations were made that might improve the rate of clinical success.

Dental Leakage↗

The effect of chlorhexidine gluconate as an endodontic irrigant on the apical seal: long-term results.

The purpose of this study was to determine whether chlorhexidine gluconate (0.12%), used as an endodontic irrigating solution, would affect the apical seal of three root canal cements. One hundred, extracted, human, single-canal teeth were divided into 9 experimental groups of 10 teeth each, in addition to a positive and negative control group of 5 teeth each. The teeth were decoronated at the level of the CEJ, accessed, instrumented to a Master apical file #50, irrigated with either sterile saline, 5.25% NaOCl, or 0.12% chlorhexidine gluconate, and dried using paper points. Obturation was accomplished using lateral condensation and one of three endodontic sealers: Roth's 811, AH 26, or Sealapex. Postobturation apical leakage was measured at 270- and 360-day observation periods using the fluid filtration method. Using the mixed-model repeated-measures ANOVA test with Tukey's honest significance difference multiple comparison procedure, the results showed the saline-Sealapex combination had significantly more leakage (p < 0.05) than either the Peridex-Sealapex or saline-Roth's combinations at 270 days. No other significant differences were noted between any sealer-irrigant combination at 270 days. The saline-Sealapex combination had significantly more leakage than the saline-Roth's combination at 360 days. No other significant differences were noted at 360 days. Under the conditions of this study, chlorhexidine gluconate irrigant did not adversely affect the apical seal of three root canal cements at 270 and 360 days.

Analysis of Variance↗