[Construction of swept source optical coherence tomography imaging system for root canal endoscopy and application in diagnosis of root fractures].

OBJECTIVE: To construct swept source optical coherence tomography (SS-OCT) imaging system for root canal endoscopy, and to evaluate the accuracy of diagnosing artificial root fractures. METHODS: An ultra-high-speed (40 kHz) swept laser source was developed based on the piezoelectric tuning filter and the Fourier domain mode locking (FDML) swept laser technology (patent number: 200620135940.2). Ultra-miniature gradient index lens technology (patent number: 201320241218.7) was used to create a thin endoscopic probe with a diameter of 0.86 mm for real-time image transmission. The SS-OCT light source had a wavelength of 1 310 nm and a bandwidth of 100 nm. The axial and transverse image resolutions were 15 µm and 25 µm, respectively. Artificial fractures were created on human mandibular premolars with single root and the premolar roots were prepared to 41 horizontal sections (1 mm thick). 27 root sections with fractures (width: 52-284 µm) and 14 the sections without fractures were observed under an optical stereomicroscope with a cold light source as the gold standard. The horizontal root sections were scanned by self-developed SS-OCT imaging system for root canal endoscopy with a central wavelength of 1 310 nm and bandwidth of 100 nm. The data were reconstructed with 30 µm thick slices at an interval of 30 µm. Two observers, a radiologist and an endodontist, were trained and independently evaluated all the reconstructed images blindly. The diagnostic performance of SS-OCT imaging system was calculated, and statistical analysis was performed. RESULTS: SS-OCT root canal endoscopic imaging system composed of high-speed swept laser source, fiber coupler, endoscopic probe, reference arm and differential detector. Root sections could be scanned by SS-OCT and imaged in realtime at a depth of 1 to 2 mm. The kappa value for interobserver agreement was 0.792, and the intraobserver agreement was 1.000 and 0.709 for two observers respectively. All of 27 fractured root sections and 12 of 14 root sections without fractures were accurately diagnosed while 2 unfractured root sections were misdiagnosed. The sensitivity was 1.000 and the specificity was 0.857 for diagnosis of artificial root fractures by SS-OCT. The positive predictive value (PPV), negative predictive value (NPV) and the overall accuracy rate were 0.931, 1.000 and 0.951 respectively. CONCLUSION: The swept source optical coherence tomography imaging system for root canal endoscopy is a promising imaging method for observing root fractures．.

[Detection of root cracks after root canal preparation using rotary NiTi systems by optical coherence tomography (OCT) scan].

OBJECTIVE: To evaluate the accuracy of optical coherence tomography (OCT) in detecting root cracks after root canal instrumentation using histological gold standard. METHODS: Twenty complete extracted human mandibular incisors that were free of caries, calculus, and root treatment were chosen and accessed coronally with a diamond bur, then mounted in resin blocks with alginate impression material using simulated periodontal ligaments, and the apex was exposed 3 mm. The teeth were stored in water at room temperature. Then the teeth were then instrumented to the major apical foramen (AF) at #30/0.09 using ProTaper Universal rotary nickel titanium system (Dentsply Maillefer, Ballaigues, Switzerland), irrigation with 1% sodium hypochlorite (NaOCl) by using a 26-gauge needle followed after each instrument. The apical root was scanned with 360° of rotation by Swept-Source Optical Coherence Tomography (SS-OCT) (wavelength: 1 310 nm, scan rate: 20 kHz, axial resolution: 16 µm) with driving device (stepper motor and lifting platform). The reconstruction images of axial planes 1, 2 and 3 mm from the apex were examined and the root cracks were blindly diagnosed by two observers. The horizontal section was performed at 1, 2 and 3 mm from the apex using low speed disc saw (Leica SP1600, Wetzlar, Germany). The presence of cracks was noted under an optical stereomicroscope (ZOOM-630E) with a cold light source using as gold standard to evaluate the accuracy of OCT in detecting root cracks after root canal instrumentation. RESULTS: After canals instrumentation with ProTaper Universal rotary nickel titanium system to #30/0.09, root cracks were detected in 9 of 20 teeth by histological examination. Crack lines were observed on 13 of 60 horizontal sections and cracks on 12 of the 13 sections were detected by OCT. No cracks were observed in the other 47 of the 60 horizontal sections,none of which was misdiagnosed by OCT. The overall accuracy rate for detection of root cracks with OCT was 0.983, the sensitivity was 0.923, the specificity was 1.000, the positive predictive value (PPV) was 1.000 and the negative predictive value (NPV) was 0.979. CONCLUSION: OCT may be a promising nondestructive imaging method for diagnosing root canal cracks after canal instrumentation.

[Current status of registered drug and vaccine pediatric clinical trials in China].

Objective: To evaluate the current status of the registered pediatric drug or vaccine clinical trials in China for the purpose of providing a reference for the development of pediatric clinical trials in China. Methods: We collected the data about registered pediatric clinical trials that were conducted from September 6, 2013(Mandatory registration start date) to September 6, 2019 (Cut-off date) at Chinadrugtrials.org.cn platform. The survey items included trial name and number, drug classification, sponsor's information, current trial status, completion status, etc. The clinical trials were categorized by drug group (includes chemical medicine, traditional Chinese medicine and natural medicine, biological products) and by vaccine group. Results: During the six years 349 pediatric clinical trials were registered on the platform, including 162 pediatric drug trials and 187 vaccine trials. The numbers of chemical drugs and biological products registered in 2018 were 23 and 11, respectively, the highest in the history. The number of pediatric clinical trials of traditional Chinese medicine and natural medicine was 11 in 2014, but from 2015 to 2018 only 2 to 4 trials were registered each year. The overall completion rates of the registered drug and vaccine clinical trials were 22.8% (37/162) and 41.7%(78/187), respectively. Only 42 international multicenter pediatric clinical trial projects were registered on the platform. The numbers of drug and vaccine phase Ⅰ clinical trials were 4 and 46, respectively. Thirty-six pediatric endocrine system agent clinical trials were carried out, with the largest number of all the drug categories registered on the platform. Conclusions: In recent years the number of registered pediatric drug and vaccine clinical trials increased in China. However, the number is still very limited. It is urgent to further promote the development of pediatric clinical trials.

[A survey of knowledge regarding pediatric clinical trial among children at 8-18 years of age].

Objective: To investigate the knowledge regarding clinical research among children at 8-18 years of age. The survey results will form the basis for developing public education program for this population. Methods: The survey was conducted among children at 8-18 years of age using WeChat and spot investigation between January 2016 and January 2017. According to different developmental stages, the survey population was divided into four groups: age 8-10, 11-13, 14-15 and 16-18 years. The level of knowledge regarding clinical research was analyzed. Results: Totally 1 329 questionnaires were issued and 1 233 effective questionnaires were returned with a recovery rate of 92.8%. The overall awareness rate regarding clinical research was 32.8% (405/1 233) . It revealed that 282 (22.9%) individuals thought that clinical research was to treat people like experimental rats. When asked "who have the final decision on research participation", the percentages of those who chose oneself, parents or guardian and doctor were 44.6% (550/1 233), 74.2% (915/1 233) and 36.8% (454/1 233) respectively. When asked "If you want to participate a study, but your parents or guardian do not agree, what would you do?", 33.9% (418/1 233) of individuals will "give up". As to "If you do not want to participate a study, but your parents or guardian think you should, what would you do?", 51.3% (632/1 233) chose "listen to parents" and 28.8% (355/1 233) chose "refuse the suggestions of parents or guardian". As to "what are your greatest concerns of participating an investigation?" , 68.1% (840/1 233) chose "worry about added pain or discomfort". but 58.0% (715/1 233) thought if "doctors and nurses take good care of me" their "concerns will reduce" or "feel better to participate in the research?". 55.6% (686/1 233) and 49.3% (608/1 233) individuals responded that they will "participate in an research?" when they "know that other people also participate the research" and when they "know the details regarding what will happen after the enrollment". Conclusions: The knowledge level of clinical research among children aged 8-18 years were not high. It is very necessary to promote the public education of clinical research for this population and also very necessary to address their concern regarding the research.

Cortical and subcortical localization of response to pain in man using positron emission tomography.

A quantitative study of the regional cerebral responses to non-painful and painful thermal stimuli in six normal volunteers has been done by monitoring serial measurements of regional blood flow measured by positron emission tomography (PET). In comparison to a baseline of warm stimulation no statistically significant changes in blood flow were seen in relation to increasing non-painful heat. However, highly significant increases in blood flow were seen in response to painful heat in comparison to non-painful heat. These changes were in the contralateral cingulate cortex, thalamus and lenticular nucleus. These findings are discussed in relation to previous physiological observations of responses to nociceptive stimuli in man and primates.

In vivo distribution of opioid receptors in man in relation to the cortical projections of the medial and lateral pain systems measured with positron emission tomography.

In vivo opioid receptor binding in the cortical projections of the medial (cingulate and prefrontal cortex) and lateral pain system (primary somatosensory cortex) in male volunteers has been quantitated using [11C]diprenorphine and positron emission tomography. High levels of opioid receptor binding were seen in the cortical projections of the medial pain system in the cingulate and prefrontal cortex as has previously been observed in post-mortem studies. However, a focal reduction of opioid receptor binding was observed and quantitated in the primary motor/sensory strip when compared to surrounding parietal cortex. This new finding suggests that the medial pain system is likely to be more susceptible to exogenous and endogenous opioid neuromodulation than the so-called lateral pain system.