A laboratory study to detect simulated pulpal blood flow in extracted human teeth using ultrasound Doppler flowmetry.

AIM: To develop a laboratory-based tooth model of simulated blood flow in teeth and evaluate it using ultrasound Doppler flowmetry (UDF). METHODOLOGY: A laboratory-based tooth model for UDF was created based on a microfluidic experimental model proposed by Kim & Park (2016 a,b). Twenty-one maxillary or mandibular anterior human teeth within 1 month of extraction were used. Four holes were made in each tooth to fit 1.6-mm diameter polytetrafluoroethylene (PTFE) tubes: at the apical foramen, palatal surface in the centre of the crown, palatal surface apical to the cementoenamel junction (CEJ) and the root centre. Fluid mimicking pulsating blood was pumped (pressure range: 0-200 mbar, flow rate range: 0-80 µL min-1 ) into the apical foramen via the PTFE tubes, which exited the tooth through the palatal surface in the centre of the crown (control group), palatal surface below the CEJ (group 1) and the palatal surface at the mid-root level (group 2). An UDF transducer of 20 MHz was placed at a 60° angle to the labial surface of tooth and was used to measure the fluid flow velocity (Vs, Vas, Vm, Vam, Vd, Vad and Vakd). The flow velocity of the different groups was compared using the Wilcoxon signed-rank test, with a 95% confidence level. RESULTS: UDF facilitated the detection of the simulated pulpal blood flow in the control group and group 1, but not in group 2. The mean and standard deviations of Vas, Vam and Vakd were 0.921 ± 0.394, 0.479 ± 0.208 and 0.396 ± 0.220 cm s-1 , respectively, in the control group, and 0.865 ± 0.368, 0.424 ± 0.215 and 0.487 ± 0.279 cm s-1 , respectively, in group 1. The pulpal blood flow values of the control group and group 1 were not significantly different (p > 0.05). CONCLUSIONS: This laboratory study revealed that ultrasound Doppler flowmetry enabled the detection of simulated blood flow below the level of the CEJ but not at the mid-root level.

Role of transient receptor potential vanilloid type 1 in the trigeminal ganglion and brain stem following dental pulp inflammation.

AIM: To verify whether experimentally induced pulpitis activates the expression of transient receptor potential vanilloid type 1 (TRPV1) and c-Fos, both peripherally and centrally. METHODOLOGY: Acute pulpitis was induced in Sprague-Dawley rats via pulp exposure and application of complete Freund's adjuvant (CFA; n = 13). Saline-treated (n = 13) rats and rats that did not undergo tooth preparation (n = 13) served as control groups. Three days post-CFA or post-saline application, face grooming activity was recorded, and the rats were then euthanized to allow for immunohistochemical analysis of the trigeminal ganglion (TG) and spinal trigeminal nucleus. anova with Student's t-test for post-hoc analysis was used to quantify the differences in behavioural tests and immunohistochemical labelling (c-Fos and TRPV1) in TG amongst groups. Kruskal-Wallis test with Dunnett's test for post-hoc analysis was used to compare immunohistochemical labelling (c-Fos and TRPV1) in the brainstem amongst groups. RESULTS: Histological evidence of severe pulp inflammation was found, and there was a significant increase in pain-like behaviour (P < 0.05) in CFA-treated animals. C-Fos labelling and TRPV1 immunoreactivity in the TG were significantly higher (both P < 0.05) in the CFA group than in the control groups. In the spinal trigeminal nucleus, the immunoreactivity for c-Fos was absent in the intermediate region (trigeminal subnucleus interpolaris) in all animals, with comparable expression of TRPV1 amongst all groups. In contrast, neurons in the trigeminal subnucleus caudalis (TSC) exhibited significant c-Fos immunoreactivity in the CFA group (P = 0.0063). The expression of TRPV1 did not differ amongst the three groups, but the superficial laminae of the TSC exhibited significantly greater expression of TRPV1 than did the deep layers (P = 0.0014). CONCLUSIONS: Following acute pulp inflammation, the TRPV1 channel was significantly involved in nociceptive signal processing in the peripheral nervous system, but not in the CNS. Because pulpitis induced some neuronal activation at the brainstem levels, further studies are needed to identify additional transducers that mediate signal transmission from pulpal afferents to their central targets.

Nosocomial person-to-person transmission of severe fever with thrombocytopenia syndrome.

OBJECTIVES: This study is an epidemiologic investigation of nosocomial severe fever with thrombocytopenia syndrome virus (SFTSV) transmission among healthcare workers (HCWs) after contact with an index patient. The aim of this study was to determine whether exposure to blood or bloody respiratory secretion is associated with human-to-human transmission of SFTSV. METHODS: Eleven days after the index patient died, two HCWs who had close exposure to the patient presented with typical symptoms of SFTS. An epidemiological investigation was conducted on all 25 HCWs who had been in close contact with the index patient. Clinical and laboratory data were collected, and transmission rate before and after the index patient had haemorrhagic manifestations was analysed. RESULTS: Among 25 HCWs who had direct contact with the index patient, five HCWs were confirmed to have SFTS. All five HCWs had contact to blood or bloody respiratory secretions of the index patient without adequate use of personal protective equipment (PPE). No HCW with contact before haemorrhagic manifestations of the index patient contracted SFTS. Overall, the transmission rate was higher for HCWs who had contact after the index patient had haemorrhagic manifestations (33.3%, five of 15 HCWs, vs. 0%, zero of ten HCWs, p 0.041). CONCLUSIONS: In HCWs who are inadequately protected, person-to-person transmission of SFTSV may be associated with contact with blood or bloody respiratory secretions. Therefore, universal precaution and full PPE is highly recommended for protection against SFTSV when there are signs of bleeding.

Severe spasticity in lower extremities is associated with reduced adiposity and lower fasting plasma glucose level in persons with spinal cord injury.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To investigate the effects of severe lower extremity spasticity on anthropometric dimensions, body composition and metabolic profiles in persons with chronic motor complete spinal cord injury (SCI). SETTING: Outpatient clinic. METHODS: Fifty-five of the 61 participants were divided into two groups (no or mild spasticity group, 28; severe spasticity group, 27) based on the assessment of the extensor muscle spasticity according to the modified Ashworth scale. Anthropometric dimensions (waist circumference (WC), waist-to-height ratio (WtHR)), body composition (fat mass (FM), body fat percentage (BFP), fat-free mass (FFM), fat-free mass percentage (FFMP), bone mineral density (BMD)) and metabolic profiles (leptin, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c)) were compared between the two groups with different degree of spasticity. RESULTS: Spasticity of the extensor muscle group negatively correlated with BFP (r=-0.458, P<0.001). Patients with severe spasticity showed a lower WC and WtHR than those in the no or mild spasticity group (P=0.038, P=0.006, respectively). The FM, BFP, leptin and FPG of the severe spasticity group were significantly lower than those of the patients in the no or mild spasticity group (P=0.003, P<0.001, P<0.001 and P=0.037, respectively). However, no differences in BMD, total cholesterol, LDL, HDL, TG and HbA1c were observed between the groups. CONCLUSIONS: The results of this study suggest that severe spasticity in lower extremities is associated with reduced adiposity and lower FPG levels in persons with chronic motor complete SCI.

Factors affecting the success rate of buccal infiltration anaesthesia in the mandibular molar region.

AIM: To compare the anaesthetic efficacy of mandibular second premolar infiltration (SP) with that of mandibular first molar infiltration (FM) in inducing pulpal anaesthesia in the mandibular first molar. To further investigate the mechanisms of action that underlie mandibular infiltration, gender-related differences in the anaesthetic efficacy were also assessed. METHODOLOGY: A total of 29 adult subjects randomly received two sets of SP and FM injections using one cartridge (1.7 mL) of 4% articaine and 1 : 100 000 adrenaline at two separate appointments. The responses of the teeth were assessed using an electronic pulp tester over a 30-min period. A comparison of the anaesthetic success between the SP and FM infiltration routes was analysed using the McNemar's test. Gender-related differences in the anaesthetic success of infiltration routes were assessed using the Fisher's exact test. RESULTS: For the second premolar and the first and second molar teeth, the success rates of SP were 72.4%, 62.1% and 48.3%, whereas the success rates of FM were 75.9%, 51.7% and 55.1%, respectively. There were no significant differences between the success rates of SP and FM or between the rates obtained for each tooth. Significant gender-related differences were observed for the second premolar (P < 0.01) and the first molar (P < 0.05) using FM. However, a significant difference was observed only for the second premolar using SP (P < 0.05). CONCLUSIONS: The differences in the injection sites did not affect the anaesthetic success rates for the mandibular second premolar and molar teeth. However, articaine buccal infiltration produced a higher anaesthetic success rate in the second premolar and first molar teeth of Korean female patients.

Immunohistochemical analysis of pulpal regeneration by nestin expression in replanted teeth.

AIM: To investigate dental pulp healing after tooth replantation in rats using nestin as an odontoblastic marker for immunohistochemical analysis. METHODOLOGY: Twenty-five maxillary right first molars from 25 female Sprague-Dawley rats, aged 4 weeks post-natally, were extracted and immediately repositioned in the original socket within 5 s. Five rats each were later killed on days 3, 5 and weeks 1, 2 and 4. The maxillae were removed en bloc and the tissue samples containing the maxillary right first molars were decalcified, sectioned, mounted and stained with anti-nestin antibody to be observed under a light microscope. RESULTS: At 3 days after replantation, there was a localized inflammatory reaction, but pulp revascularization and healing had begun in the root area. At 5 days after replantation, odontoblast-like cells were observed. Reparative dentine deposition was observed beneath the pulp-dentine border from 1 week after replantation, and gradually increased until 2 weeks after replantation. The presence of odontoblast-like cells and the formation of reparative dentine continued from the first week throughout the experimental period. At week four, deposition of osteodentine and cementum-like tissues were observed. CONCLUSIONS: Pulpal mineralization after replantation initially occurred via the deposition of reparative dentine, followed by the deposition of osteodentine and cementum-like tissues in rat teeth.

Difference in root canal length between Asians and Caucasians.

AIM: To investigate whether there is a racial difference in canal length between the Asians and Caucasians. METHODOLOGY: Five hundred and fifteen Asian patients who had received root canal treatment at the Yonsei University Hospital, Korea between 1995 and May 2001 and 324 Caucasoid patients who had received root canal treatment at the Graduate Endodontic Clinic at the University of Pennsylvania, US were selected. The clinical endodontic procedures at both clinics were similar. An electronic apex locator (Root-ZX; J. Morita Co., Kyoto, Japan) was used to measure the initial working lengths and this was verified by conventional radiography. The measurements from both Asian and Caucasian teeth were compared using a Student's t-test and a Mann-Whitney test. RESULTS: The mean difference in canal length of pooled teeth between the Asian and Caucasian teeth was 1.2 mm, with a range from 0 to 2.5 mm. The greatest difference was in the distobuccal canal (2.5 mm) of maxillary first molar teeth followed by the mesiolingual canal (2.3 mm) of mandibular second molar, the buccal canal (2.1 mm) of the maxillary second premolar, the maxillary first molar and the mandibular second molar. CONCLUSION: Tooth lengths in Asians were shorter than Caucasians.

Identification of oral spirochetes at the species level and their association with other bacteria in endodontic infections.

OBJECTIVES: Recent molecular approaches have revealed that fastidious organisms such as Bacteroides forsythus and oral treponemes were frequently found in root canals with apical periodontitis. The purpose of this study was to identify the isolates of oral spirochetes at the species level in endodontic infections and to determine their association with B forsythus and Porphyromonas gingivalis. STUDY DESIGN: Seventy-nine teeth with apical periodontitis were selected for this study. After sampling from the root canals aseptically, polymerase chain reaction amplification for the 16S rRNA gene was performed with eubacterial universal primers. Subsequently, dot-blot hybridization was performed with 8 species-specific oligonucleotide probes. The microbial associations were analyzed by using the odds ratio. RESULTS: The most frequently found species was P gingivalis (27.4%), followed by Treponema maltophilum (26%), B forsythus (16.4%), and Treponema socranskii (2.7%). Other treponemes, including Treponema denticola, were not detected in our samples. Significant microbial associations were identified between T maltophilum, B forsythus, and P gingivalis by performing analysis with the odds ratio. CONCLUSION: Our results indicate that T maltophilum should be included in etiologic studies of endodontic diseases.

Clinical application of computer-aided rapid prototyping for tooth transplantation.

The maintenance of healthy periodontal ligament cells in the donor tooth is one of the most important factors for successful tooth transplantation. This is achieved by minimizing the extraoral time during the surgical procedure. If a duplicate form of donor tooth could be obtained before extraction, it would be possible to precontour the recipient alveolar bone compatible with the donor tooth, and thereby reduce the extra-oral time of the donor tooth. We obtained a three-dimensional image with the real dimensions of the donor tooth from a CT Highspeed Advantage, allowing a life-sized resin model of the tooth to be fabricated. From 22 clinical cases, we achieved an average total transplantation time of 7.7 min. The average distance between the transplanted root surface and the alveolar bone from 12 available cases was 0.87 mm at the mesial cervix, 0.91 mm at the mesial apex, 0.98 mm at the distal cervix and 1.16 mm at the distal apex on the postoperative radiographs. Clinical data indicate that computer-aided rapid prototyping may be of value in minimizing the extra-oral time and possible injury to transplanted tooth during the process of autotransplantation.

Molecular epidemiology and association of putative pathogens in root canal infection.

The purpose of this study was to investigate the epidemiology of putative pathogens in root canals with apical periodontitis and to determine the associations among the putative pathogens. Eighteen symptomatic and 20 asymptomatic teeth from 36 subjects were studied. This research was performed with polymerase chain reaction and hybridization using rRNA-based oligonucleotide probes. The most frequently found species was Fusobacterium sp. (68.4%), followed by Peptostreptococcus micros (44.7%) and Porphyromonas gingivalis (26.3%). Sixteen teeth (42.1%) contained one or more species of the selected black-pigmented bacteria. Bacteroides forsythus and Treponema sp. were detected in 8 teeth and 6 teeth, respectively. Among the analyzed bacteria, significant relationships were shown in the combination of B. forsythus/P. gingivalis and Treponema sp./P. gingivalis. There was no significant association between any bacteria and any symptoms.