Epithelioid cell granuloma with caseating necrosis possibly caused by periapical periodontitis: a case report.

BACKGROUND: Epithelioid cell granuloma with caseating necrosis is a typical pathological finding in tuberculosis. While specific inflammation, including that related to tuberculosis, can induce caseating granuloma formation, there have been very few reports on the induction of caseating granuloma by non-specific inflammation. Chronic periapical periodontitis is usually related to bacterial biofilm formation as well as fungal or viral infection in the periapical lesion. However, it is difficult to eliminate these extraradicular pathogenic microbes by normal endodontic therapy alone, and more invasive surgical removal is almost always required. CASE PRESENTATION: Here we describe the case of a 30-year-old Japanese woman who had suffered from dull pain related to periapical periodontitis for approximately 10 years. Although the causal tooth had been previously extracted at the Department of Oral Surgery of another hospital in 2015, inflammation of the surrounding tissue had not abated. She was referred to our hospital in May 2016 and underwent surgical debridement via an intra/extraoral approach under general anesthesia. A caseating granuloma accompanied by a small amount of fungi was histopathologically confirmed in the excised specimen. Her inflammation has not been exacerbated since the operation. CONCLUSIONS: This is the first report in which non-specific inflammation is shown to induce caseating granuloma arising in the jaw. Our report also highlights the importance of sufficient root canal treatment during the first stage of the procedure.

Comparison of the time required to create secondary fracture of separated file fragments by using ultrasonic vibration under various canal conditions.

INTRODUCTION: Nickel-titanium files often separate because of mechanical fatigue. The purpose of this study was to determine safe preparation techniques for separated file removal by using ultrasonics. METHODS: Fifty nickel-titanium file fragments were divided into 5 groups. An ultrasonic tip was activated on a file fragment positioned between dentin blocks simulating several canal conditions: Group 1 consisted of the fragment protruding from a pair of straight dentin blocks. For group 2, the fragment was also positioned between 2 straight dentin blocks except one block was positioned 1 mm more apically than the other block, simulating a troughed area that is often created during file removal attempts. For groups 3-5, the fragment was positioned similarly as group 2 but between blocks with 30°, 45°, and 60° curvatures, respectively. The time it took for secondary fracture to occur was recorded, and the data were statistically analyzed. RESULTS: Fragments with dentin wall supporting on the opposite side of ultrasonic activation site resisted fracture significantly longer than those without it. Fragments in 30° and 45° curved blocks took significantly longer to fracture than the other groups (Fisher protected least significant difference, P < .05). CONCLUSIONS: Secondary fracture of separated files appeared to be reduced when the ultrasonic tip was applied to the inner curvature of the canal.

Crack initiation on the apical root surface caused by three different nickel-titanium rotary files at different working lengths.

INTRODUCTION: The aim of this study was to compare the effects of three brands of nickel-titanium (NiTi) rotary files with different designs on the initiation of apical root cracks when working short, at, and beyond the apical foramen. METHODS: One-hundred eight teeth with straight single canals were selected and mounted on resin blocks with simulated periodontal ligaments, and the apex was exposed. The teeth were divided into 9 groups of 12 teeth according to the NiTi rotary file type used (Profile [Dentsply Maillefer, Ballaigues, Switzerland], K3 [SybronEndo, West Collins, CA], and EndoWave [FKG Dentaire, La-Chaux-de-Fonds, Switzerland]) and working length (at CL, 1 mm short of [CL - 1 mm], and 1 mm beyond [CL + 1 mm] the apical foramen). Digital images of the apical surface of every tooth were taken during the apical enlargement sequence at each file change. These images were compared with the baseline image, and the presence of a crack was noted. RESULTS: Significantly less cracks were observed in the CL - 1 mm group than in the CL and CL + 1 mm groups. No significant difference was found between the file types used. CONCLUSIONS: Working 1 mm short of the apical foramen caused less cracks on the apical surface. In addition, more cracks were observed when using larger file sizes. Instrumentation with NiTi rotary files could potentially cause cracks on the apical root surface.

Effects of new adhesive resin root canal filling materials on vertical root fractures.

The aim of this study was to compare the fracture resistance of roots following root canal therapy using the RC Sealer system, the Epiphany system and the conventional system of gutta-percha and Sealapex. Fifty-six maxillary central incisors were divided into eight groups of seven teeth each, according to master apical file size and obturation systems. Obturation materials in the root canal were vertically loaded using a universal testing machine. Fracture loads were analysed by ANOVA and Tukey comparison, and fracture patterns were analysed with ordinal logistic regression. Master apical file size 80 had a significantly lower fracture load than size 40 (P < 0.05). The groups obturated using the Resilon Cone and the Epiphany Sealer had significantly lower fracture loads than the other groups (P < 0.05). There was no significant improvement in resistance to vertical root fractures using the examined adhesive resin root canal filling systems, compared with conventional gutta-percha and sealer.

The effect of root preparation technique and instrumentation length on the development of apical root cracks.

The purpose of this study was to compare the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Forty extracted mandibular premolars with straight roots were randomly selected and mounted on resin blocks with simulated periodontal ligaments, and the apex was exposed. The teeth were divided into four groups of 10 teeth each for different canal preparation techniques and instrumentation lengths: group A: step-back preparation (SB) with stainless steel files (SF) using root canal length (RCL) to guide instrumentation length; group B: SB using RCL - 1 mm; group C: crown-down preparation (CD) with Profile using RCL; and group D: CD with PF using RCL - 1 mm. Digital images of the instrumentation sequence were compared for each tooth. Statistical analysis revealed a significant effect of instrumentation length (p < 0.05) but no significant effect of preparation technique (p > 0.05) on the development of apical cracks.

Spreading of root canal irrigants on root dentine.

The purpose of this study was to evaluate the spreading of root canal irrigants on human root dentine. The spreading of various solutions on dentine surfaces was measured after pre-treatment with various conditional solutions. Seven experimental groups were set based on the combination of conditioning solution-test solution: none-distilled water; none-6% sodium hypochlorite (NaOCl); none-14.3% ethylenediaminetetraacetic acid containing surfactant 0.084% cetrimide (Morhonine); NaOCl-NaOCl; NaOCl-Morhonine; Morhonine-Morhonine and Morhonine-NaOCl. After application of 0.1 mL of conditioning solution for 60 s, 0.5 microL of test solution was placed on dentine surfaces. Spreading of test solution was measured for 480 s to examine the size of the contact area ratio. Those at 300 s were compared among groups using Fisher's Protected Least Significant Difference (P < 0.05). It was concluded that the contact area ratio of Morhonine-NaOCl increased the most significantly among all the experimental groups.

Sealing ability of new adhesive root canal filling materials measured by new dye penetration method.

The sealing ability of new adhesive root canal filling materials was evaluated using a new dye penetration method. Twenty-eight single-rooted mandibular premolars were randomly divided into four groups of seven teeth each and filled by lateral condensation using one of these combinations: Resilon point with Epiphany sealer (RE); gutta-percha point with Sealapex sealer (GS); gutta-percha point with dentin activator and Superbond sealer (GDS); or gutta-percha point with Accel primer, dentin activator, and Superbond sealer (GADS). Amount of 0.06% methylene blue dye solution (MB) that leaked from the coronal portion to the apical area was measured with a spectrophotometer at one, four, eight, 15, and 30 days in an accumulative manner. The total amount of leaked MB on day 30 was significantly higher for GDS than the other combinations (p < 0.05).

Evaluation of the efficiency of a new file removal system in comparison with two conventional systems.

A novel file-removal system (FRS) was designed to address weak points of conventional file-removal methods. The purpose of this study was to compare file-removal time and dentin removal rates among the FRS, the Masserann kit (Micro-Mega, Besancon, France), and an ultrasonic file-removal method. Ninety extracted mandibular incisors with separated nickel titanium files were divided into 3 groups of 30 teeth each. Groups 1, 2, and 3 had file-removal attempts made by using the Masserann kit, a CPR-7 titanium ultrasonic tip (Obtura-Spartan Corp., Fenton, MO), and the FRS, respectively. Each group had three operators removing the separated files. Pre-/postoperative digital radiographs were downloaded into image analyzing software that calculated the amount of dentin removed. The FRS needed less time and had less dentin loss than the others (p<0.05). There were statistical differences between the experienced operator and less experienced operators regarding the file-removal time and the dentin removal rates (p<0.05).

Effective factors including periodontal ligament on vertical root fractures.

The purpose of the present study was to analyze effective factors including periodontal ligament on vertical root fractures (VRFs). Eighty maxillary central incisors were assigned to eight groups, depending on master apical file (MAF) size, loading point and existence of a simulated periodontal ligament (PDL). The gutta-percha in the root canal was vertically pressed with a Co-Cr rod using a universal testing machine. An ordinal logistic analysis was employed to determine significant factors. VRFs were observed in 88.8% of the specimens but no horizontal fractures were found. There were three types of VRFs: partial fracture not involving the apex (PF, 41.3%), partial fracture involving the apex (AF, 40.0%), and complete fracture (CF, 7.5%). MAF size significantly affected VRFs (p < 0.05); large MAF size exhibited more partial fractures involving the apex. Loading point and existence of PDL did not affect VRFs.

Quality of gutta-percha root canal fillings using differently tapered gutta-percha master points.

The aim of this study was to evaluate the quality and adaptability of gutta-percha root canal fillings to the root canal walls when two different tapered gutta-percha master points (GPMP) were used to fill a split-tooth model. A maxillary central incisor was prepared for the split-tooth model and 10 fillings for group A (ISO .02 GPMP) and group B (ISO .10 GPMP) were carried out. The System B and the Obtura II were used to fill the split-tooth model and replication of round artificial depressions, voids within the gutta-percha (GP) and spaces between the GP and the root canal walls were evaluated and scored. Individual scores of each parameter evaluated were compared between the two groups and statistically analyzed using the Mann-Whitney U test. Group A showed statistically significant better scores (p < 0.05) for the replication of the artificial round depressions and spaces between the GP and the root canal walls. No statistically significant differences were found between the two groups for internal voids. It is concluded that the location of the GPMP binding point and the greater mass of the .10-Tapered GPMP may affect the quality and adaptation of the root canal filling in the important apical part of the canal.

Frequency of transverse anastomoses with and without apical communication in Japanese population teeth.

The aim of this study was to describe and measure the frequency of transverse anastomoses with and without an apical communication in Japanese population teeth. One hundred and twenty-three extracted teeth from Japanese people were used in this study. The sample consisted of: 63 mandibular first molars, 30 maxillary first molars and 30 maxillary first premolars. Access openings were made through the crowns to the pulp chamber and India ink was injected into the coronal pulp space and vacuumed from the apical end. The teeth were cleaned and digital micrographs taken from several angles to identify transverse anastomoses. Fourteen teeth had only one canal and 81 teeth out of 109 (74%) had transverse anastomoses including 6 teeth (5.5%) that had an apical communication. Most of the anastomoses (50) were located in the middle portion of the canal and 22 (20%) teeth showed multiple anastomoses. Special attention must be taken after resection of roots with apparent multiple canals. The potentially exposed exits and/or isthmuses should be taken into consideration during surgical endodontic treatment.

Three-step versus single-step use of system B: evaluation of gutta-percha root canal fillings and their adaptation to the canal walls.

This study aimed to evaluate the quality of gutta-percha (GP) root canal fillings and their adaptation to the root canal walls, when the System B was used in three steps and a single step to fill three different split-tooth models. Each model was filled 10 times in two different ways. Group A: the System B plugger was used to fill the apical 3 mm of the canal in three steps, and then the Obtura II was used to backfill the rest of the canal. Group B: the System B plugger was inserted just once to a distance 3 mm short of the working length and then backfilled as in Group A. Replication of artificial depressions, presence of voids within the GP mass, and presence of spaces between the GP mass and the root canal walls were evaluated and scored. The individual scores of each parameter evaluated were compared between the two groups and statistically analyzed by use of the Mann-Whitney U test. Group A showed statistically significant (p < 0.05) better scores than Group B concerning the replication of artificial depressions and spaces between the GP mass and the canal walls. It was concluded that better adaptation of the GP mass to the canal walls in the apical third was obtained when the System B plugger was used in three steps.

Radiographic evaluation of root canal multiplicity in mandibular first premolars.

The purpose of this study was to examine the accuracy of radiographic evaluation of root canal multiplicity in mandibular first premolars in vitro. One hundred thirty-nine extracted human mandibular premolars were used. Buccolingual radiographs were taken, and the number of canals in each tooth was determined on radiographs by four dentists using a view box. A sudden narrowing of the main canal was interpreted as a sign of multiple canals. After the radiographic evaluation, the tooth crown was removed. India ink was injected into the root canal system, and the root was cleared to observe the canal morphology. There was no statistically significant difference among the four dentists with respect to the coincidence rate (93%-96%) of the canal number evaluated on radiographs with that identified by cleared teeth observation (p > 0.05, one-way analysis of variance). A sudden narrowing of the main canal on the radiograph was a good criterion to judge root canal multiplicity.

An experimental study on the vasoconstriction effect of calcium hydroxide using rat mesentery.

Calcium hyroxide has been used for eliminating persistent intracanal exudation. In order to address the mechanism behind this action, we investigated whether calcium hydroxide solutions cause the constriction of microvessels in the mesenteric microcirculation bed of rats. The exteriorised mesentery from anaesthetised rats was spread in a chamber, and arterioles, venules and capillaries were viewed under a digital microscope. Various concentrations of calcium hydroxide solutions were applied for 10 sec, and the diameter of the microvessels was recorded. In arterioles, calcium hydroxide solutions caused rapid and transient constriction. A statistically significant difference versus original diameter was detected 1 min after the application of 4.0 x 10(-3) mol/l and 1.0 x 10(-2) mol/l solutions (p < 0.05, one-way analysis of variance and Tukey-Kramer test). No statistically significant constriction occurred in capillaries and venules. It was concluded that the arteriolar constriction might be an explanation for the exudation-controlling effect of intracanal calcium hyroxide dressings.

An observation of the healing process of periapical lesions by digital subtraction radiography.

The purpose of this study was to evaluate the efficacy of digital subtraction radiography using a direct digital imaging system in the follow-up study of endodontically treated teeth. The RVG-S was used as a direct digital imaging system. The intraimage variation of the original RVG-S image caused by dark current and sensitivity variations among pixels was corrected by pixel-to-pixel. The interimage variation was further corrected using a copper step-wedge attached to the sensor. Standardized images were obtained from the same geometrical setup during the follow-up. Pixel values at the regions of interest positioned on the periapical lesion increased after the endodontic treatment, and this change continued during the observation period up to 545 days. The subtraction method with direct digital radiography will be a useful tool to evaluate the healing process in endodontic treatments.

Obturation of accessory canals after four different final irrigation regimes.

The aim of this study was to evaluate accessory canal obturation after four different final irrigation regimes. Sixty-four extracted human lower premolars were instrumented, divided randomly into four groups, and finally irrigated as follows: no irrigation (NO), distilled water (WA), sodium hypochlorite ([SH] 6%, 20 ml for 15 min), and EDTA (15%, 8 ml for 3 min) combined with the SH regimen (ES). The System B and the Obtura II were used to fill the canals. The teeth were cleared and observed under a digital microscope. Obturation material penetration rates in length into the accessory canals were measured and the following values were obtained: 22.3% in group NO, 21.8% in group WA, 53.5% and 68.1% in groups SH and ES, respectively. Statistically significant differences were found when comparing each of the first two groups (NO and WA) with SH and ES groups (p < 0.05). The use of sodium hypochlorite alone or in combination with EDTA in final irrigation flushes may enhance a better obturation material penetration into the accessory canals.

Detection rate of root canal orifices with a microscope.

The purpose of this study was to compare the detection rate of root canal orifices by three different methods: naked eye, with surgical loupes, and under a microscope. Two undergraduate dental students located the orifices of 260 teeth by using the above-mentioned methods. Then, India ink was injected into the pulp chamber and all teeth were cleared to determine the actual number of the orifices. There was a significant difference in the detection rate among the three methods (p < 0.01, chi-square test); the microscopic method could more accurately detect orifices than the others could. Surgical loupes were relatively ineffective compared with the microscopic method for detecting orifices.

Electronic detection of root canal constrictions.

The aim of this study was to investigate the possibility of detecting root canal constrictions by using an apex locator. Seventy impenetrable canals in extracted human teeth were used. Based on contact microradiographic findings, they were divided into three groups: group A (constricted within 3 mm of the radiographic apex, 23 canals), group B (nonconstricted within 3 mm of the radiographic apex, 28 canals), and group C (constricted more than 3-mm short of the radiographic apex, 19 canals). Electrical impedances at two different frequencies (8 kHz and 0.4 kHz), as well as the meter values of the Root ZX were recorded at the position where a file tip could reach. The impedance ratios (Z8kHZ:Z0.4kHz) and the meter values of the Root ZX showed a statistically significant difference between groups A and B. It was suggested that the Root ZX might be useful for detecting root canal constrictions.