A prevalence survey of cone-beam computed tomography use among endodontic practitioners / 北京大学学报(医学版)

OBJECTIVE@#To investigate the clinical application of cone-beam computed tomography (CBCT) among endodontic practitioners, and to analyze the indications and reasonability of CBCT in the diagnosis and treatment of pulpal and periapical diseases.@*METHODS@#The clinical data were collected from patients who visited the Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology and underwent CBCT examination from January to December, 2021. The data with their complete clinical information (including clinical records, radiology request forms/reports, two-dimensional and three-dimensional imaging data) were included. Those who underwent CBCT examination for orthodontic or prosthodontics were excluded. The experience and training background of the endodontic specialists, the number of patients treated in the whole year, the objective and region of interest (ROI) of CBCT examination, technical parameters, such as machine type, field of view (FoV) and radiographic reports were collected and analyzed to evaluate the impact on diagnosis. Wilcoxon and Mann-Whitney tests were used to compare the distribution of CBCT ROI. Chi-squared test and pairwise comparison were used to compare the application of CBCT by endodontic specialists with different clinical experience (senior, middle and junior).@*RESULTS@#In 2021, a total of 3 308 CBCT scans were prescribed by 61 endodontic specialists who treated 34 952 patients throughout the year. 3 218 patients (male ∶female about 1 ∶2) amounting for 10% of the patients treated in the whole year who received CBCT scans with an median age of 35 years (28, 49). Around 98% CBCT examinations were performed after clinical examination and two-dimensional periapical radiographs were taken. The FoV of CBCT scanning less than 10 cm×10 cm accounted for 96% of the total number of the images. Among the 3 308 CBCT scans, 83% of the ROI were in posterior teeth, with a higher number of anterior teeth (Z=-2.278, P < 0.05). Maxillary and mandibular first molars accounted for 35% of the examined teeth. The objectives of CBCT scanning included three aspects: clarifying clinical diagnosis, guiding surgical and non-surgical endodontic treatment (including management of endodontic complications), and outcome assessment, accounting for 1 111 (34%), 1 745 (54%), 311 (10%), respectively. and the others 2%. In the diagnosis process, CBCT was mainly used for the diagnosis of chronic periapical periodontitis, root fracture, root resorption and dental trauma. In the study, 353 CBCT were used in the diagnosis of root fracture, with a positive diagnosis rate of 35% (125/353). 846 CBCT used to reveal the anatomy of the root canal system, of which 297 cases were used to find missed/extra canals after treatment failure, and 58% (171/297) were used to confirm the missed/extra canals. In the management of complications or errors, CBCT was mainly used to assist the diagnosis of perforation and to locate the separated instruments. In the study, 311 CBCT scans were used for outcome assessment, including 240 cases related to non-surgical treatment and 71 cases related to surgical endodontic treatment for follow-up or presence of clinical symptoms, and persistent lesions on 2D films. Among the 61 endodontic specialists who used CBCT, 23 (45%) were with senior experience, 15 (30%) with middle experience, and 23 (25%) with junior experience. The proportion of senior or junior experience prescribing CBCT examination was 10%, higher than that of middle experience (8%, χ12=39.4, χ22=29.1, P < 0.001). The application rate of chief endodontists was 18%, which was higher than that of associate chief endodontists (9%, χ12=139.4, P < 0.001). 31% (1 109/3 308) cases of diagnosis or treatment plans were changed after CBCT was taken.@*CONCLUSION@#Use of CBCT in endodontic practice could provide more clinical information, which is helpful for diagnosis, accurate treatment and prognosis evaluation.

Cone-beam computed tomography digital for measuring the inclination angle to the long axis of healthy maxillary anterior teeth and morphologically characterizing their labial bone plates / 华西口腔医学杂志

OBJECTIVE@#We aim to determine the thickness of the labial plate, the distance between the cement-enamel junction (CEJ) and alveolar crest, and the inclination angle of the long axis of healthy maxillary anterior teeth by using cone- beam computed tomography (CBCT).@*METHODS@#A total of 345 CBCT volumes obtained by Newtom VGI® CBCT were analyzed by using the NNT software. The digital measurements of the labial bone plate thickness at level 4 mm below the CEJ, the midpoint of tooth root and the radiological tooth apex, the distance between the CEJ and alveolar crest, and the angle between the long axis of the teeth and the long axis of alveolar process were obtained from the mid-sagittal planes of maxillary incisors and canines. Plate thickness 4 mm below the CEJ was measured, and values below ≥1 mm were recorded.@*RESULTS@#In the central incisor, 1) the angle between the long axis of the teeth and alveolar bone was 15.2°±6.2°, the distance between the CEJ and alveolar crest was (1.5±1.0) mm, labial bone plate thick-ness at 4 mm below the CEJ was (0.8±0.4) mm, the midpoint of tooth root was (0.6±0.4) mm, and the radiological tooth apex was (1.3±0.7) mm; in the lateral incisor, 16.2°±8.8°, (1.6±1.0) mm, (0.7±0.5) mm, (0.4±0.6) mm, and (1.1±0.7) mm, respectively; and in the canine, 19.0°±6.2°, (1.8±1.0) mm, (0.9±0.6) mm, (0.4±0.6) mm, and (1.2±0.7) mm, respectively. 2) The frequencies of plate thickness ≥1 mm were 28.3%, 25.8%, and 42.7% in the central incisor, lateral incisor, and canine, respectively. 3) The distance between the CEJ and alveolar crest was positively correlated with age. The correlation coefficients was 0.42 (P<0.01) in the central incisor, 0.50 (P<0.01) in the lateral incisor, and 0.62 (P<0.01) in the canine.@*CONCLUSIONS@#The thickness of labial bone plate is thin, the distance from CEJ to alveolar crest increases with age, and the long axis of the teeth is more inclined than the long axis of alveolar process. Knowledge of these special morphological characteristics can improve the safety and result for many dental procedures.

Effects of different methods on drying root canal by near-field microwave detection system / 北京大学学报(医学版)

OBJECTIVE@#To set up near-field microwave detection system, to evaluate the accuracy of measuring water and to compare the effects of different methods on drying root canal.@*METHODS@#Known and quantitative distilled water in Eppendorf tube and root canal was detected by near-field microwave detection system which was set up first. The microwave reflection coefficient was recorded so as to evaluate the accuracy of the measuring water. 12 single-rooted mandibular premolar teeth with apical matureness and a curvature less than 10° were decoronated, leaving roots 14 mm in length. After instrumentation to F3, the root canals were air-dried and injected with 10 μL distilled water each. Then all the root canals were assigned to 4 groups (n=12) according to different methods on root canal drying. Near-field microwave detection system was used to detect the change of water after air-drying and root canal drying so as to evaluate the effects of different root canal drying methods: (1) negative control group, the canals were injected with 10 μL distilled water and no root canal drying method was performed; (2) paper points drying experimental group, four #60 paper points were used to blot-dry the middle and upper part of the canal, followed by #40 paper points blot-drying the apical area. The above step was repeated with the tip of paper point that appeared with no water under microscope as finished; (3) 95% (volume fraction) ethanol drying experimental group, after the distilled water was removed with paper points (similar to paper points experimental group), 10 μL 95% ethanol was injected into the canal and was left in place for 10 s, then paper points were used to dry the canal; (4) 70% (volume fraction) isopropyl alcohol drying experimental group, after the distilled water was removed with paper points (similar to paper points experimental group), 10 μL 70% isopropyl alcohol was injected into the canal and was left in place for 10 s, then paper points were used to dry the canal. The linear correlation analysis was used to test the accuracy of the measuring water by near-field microwave detection method and physical measurement. The Pearson correlation coefficient was calculated based on the data. The effects of different methods on drying root canal were analyzed by Chi square test.@*RESULTS@#The R2 for the microwave reflection coefficient and the physical measurement of the water in Eppendorf tube and root canal were 0.991 and 0.970. The microwave reflection coefficient in all the experimental groups showed significant difference (P<0.05). After drying with paper points, the residual water was the most, and the microwave reflection coefficient was the highest: 0.023. While after 70% isopropyl alcohol drying root canal, the residual water was the least with the microwave reflection coefficient 0.006, showing that the effect of drying was the best.@*CONCLUSION@#Near-field microwave detection system could detect the change of water in root canal. The effect of root canal drying by 70% isopropyl alcohol was superior to 95% ethanol and paper points.

Relationship between periodontitis and osteoporosis in postmenopausal women / 北京大学学报(医学版)

OBJECTIVE@#To explore the relationships of periodontal parameters, cortical width on mental foramen and osteoporotic condition in postmenopausal women.@*METHODS@#Ninetyeight postmenopausal women between 50 to 65 years old were recruited. General conditions, such as age, menopausal age, duration of menopause, and body mass index (BMI) were recorded. Periodontal parameters were examined, including oral hygiene index simplified (OHI-S), probing depth (PD), clinical attachment loss (CAL), gingival recession (GR) and bleeding on probing (BOP). Panoramic radiograph was taken and the cortical width (CW) of mental foramen was measured on images. The examiner was celebrated. Bone mass density (BMD) of left hip and lumbar spine was assessed using standardized dual energy X-ray absorptiometry. According to World Health Organization, based on the T-score of BMD (difference of the measured BMD and the mean value of young white women in terms of standard deviations), the subjects were divided into osteoporotic group (T-score<-2.5) and non-osteoporotic group (T-score≥-2.5). These parameters were compared between the groups.@*RESULTS@#The number of osteoporotic group was 47 (47.96%). Ages and duration of menopause were significantly different between the groups. Osteoporotic group presented older ages [(59.64±4.58) years vs. (56.94 ± 4.26) years, P<0.05], and longer duration of menopause [(10.17± 5.37) years vs. (6.02 ±4.48) years, P<0.05]. There was no significant difference in menopausal age and BMI between the groups. BOP% was statistically significantly higher in osteoporotic group (29.43±21.12) than in non-osteoporotic group (21.43±17.09), with a P-value of 0.046. The other periodontal parameters, including OHI-S, PD, CAL, and GR were not statistically significantly different in the groups. The CWs were statistically significantly lower in osteoporotic group compared with non-osteoporotic group, with a P-value of 0.001. The mean values of CWs were (3.61±1.04) mm (osteoporotic group) and (4.25±0.77) mm (non-osteoporotic group), respectively.@*CONCLUSION@#The study demonstrated absence of a significant association between periodontal parameters and BMD. However, the CWs were found to be related with the BMD, which may be used to detect BMD abnormal in maxillofacial imaging. The dentists should pay attention not only to the oral health, but also to the general bone mass density, which may be detected on panoramic images.

Construction of swept source optical coherence tomography imaging system for root canal endoscopy and application in diagnosis of root fractures / 北京大学学报(医学版)

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．.

A prognostic model for assessment of outcome of root canal treatment in teeth with pulpitis or apical periodontitis / 北京大学学报(医学版)

OBJECTIVE@#To present a prognostic model for evaluating the outcome of root canal treatment in teeth with pulpitis or apical periodontitis 2 years after treatment.@*METHODS@#The implementation of this study was based on a retrospective study on the 2-year outcome of root canal treatment. A cohort of 360 teeth, which received treatment and review, were chosen to build up the total sample size. In the study, 143 teeth with vital pulp and 217 teeth with apical periodontitis were included. About 67% of the samples were selected randomly to derive a training date set for modeling, and the others were used as validating date set for testing. Logistic regression models were used to produce the prognostic models. The dependent variable was defined as absence of periapical lesion or reduction of periapical lesion. The predictability of the models was evaluated by the area under the receiver-operating characteristic (ROC) curve (AUC).@*RESULTS@#Four predictors were included in model one (absence of apical lesion): pre-operative periapical radiolucency, canal curvature, density and apical extent of root fillings. The AUC was 0.802 (95%CI: 0.744-0.859). And the AUC of the testing date was 0.688. Only the density and apical extent of root fillings were included to present model two (reduction of apical lesion). The AUC of training dates and testing dates were 0.734 (95%CI: 0.612-0.856) and 0.681, respectively. As predicted by model one, the probability of absence of periapical lesion 2 years after endodontic treatment was 90% in pulpitis teeth with sever root-canal curvature and adequate root canal fillings, but 51% in teeth with apical periodontitis. When using prognostic model two for prediction, in teeth with apical periodontitis, the probability of detecting lesion reduction with adequate or inadequate root fillings was 95% and 39% 2 years after treatment.@*CONCLUSION@#The pre-operative periapical status, canal curvature and quality of root canal treatment could be used to predict the 2-year outcome of root canal treatment.

Cleaning efficacy of different solvents on sealer-contaminated dentin surface / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the influence of an epoxy resin-based sealer on the bond strength of adhesive resins to dentin and the cleaning efficacy of different solvents in removing sealer residues.@*METHODS@#The occlusal enamel of 25 freshly extracted human third molars without caries were removed to expose flat surfaces of dentin. The teeth were randomly divided into five groups according to the treatment received: For negative control group, the dentin surfaces were not contaminated with AH-Plus; For the other 4 experimental groups, the samples were contaminated with AH-Plus for 5 min and different measures were taken: For positive control group, the sealer were wiped with dry cotton pellets; For solvents experimental groups: cotton pellets saturated with 95% (volume fraction) ethanol, 99.5% (volume fraction) acetone or 99% (volume fraction) amyl acetate were used to wipe the sealer until the surface appeared clean when viewed through a stereomicroscope under ×10 magnification, then rinsed with de-ionized water for 3 s. After sealer removal, a self-etching adhesive system was applied on the surfaces with resin composite. The samples were sectioned into 1.0 mm×1.0 mm stick specimens (n=45) for microtensile test. Failure modes at the dentin-resin interface were observed using a stereomicroscope. The samples were sectioned into 1.0 mm piece specimens (n=4) for scanning electron microscope observation. The microtensile bond strength data were analyzed by one-way ANOVA. Chi-square test were used to analyse the failure modes between the groups.@*RESULTS@#There was significant difference among the five groups (P<0.001). For dry cotton pellet group (38.69±8.60) MPa and the ethanol group (37.14±12.01) MPa, the microtensile bond strength significantly declined when compared with negative control group (43.86±7.99) MPa (P<0.05). No significant difference of bond strength was found between the dry cotton pellet group and the ethanol group (P=0.426). There was no statistical significant difference among acetone group, amyl acetate group and negative control group (P>0.05). The bond strength of acetone group and amyl acetate group were (45.94±10.37) MPa and (43.99±7.01) MPa, respectively. The ethanol group exhibited lower bond strength than that of acetone group and amyl acetate group (P<0.05). Scanning electronic microscope observation revealed that in dry cotton pellet group and ethanol group, the resin tags were short and loose. Moreover, sealer residues were identified in the interface in the ethanol group samples, while the resin tags in the acetone and amyl acetate group were as dense and uniform as in negative control group. The distribution of failure modes showed no significant difference in the five groups (P=0.086).@*CONCLUSION@#The microtensile bond strength of dentin to composite resin was lower after exposure to sealer. Compared with ethanol and dry cotton pellets, the cleaning effect of acetone and amyl acetate on sealer-contaminated dentin surface were better.

Computer aided design and three-dimensional printing for apicoectomy guide template / 北京大学学报(医学版)

OBJECTIVE@#To establish an apicoectomy guide template design and manufacturing method, based on multi-source data fusion, computer aided design (CAD) and fused deposition modeling (FDM). The feasibility of the guide template was preliminary evaluated by the in vitro model experiment.@*METHODS@#An extracted upper anterior tooth, after root canal treatment, was optical scanned, after which the extracted upper anterior tooth was poured in an apicoectomy plaster model. Cone-beam computed tomography (CBCT) scanning of the apicoectomy plaster model was performed, after which optical scanning of the plaster model for apical resection surgery was carried out. All of the relevant CBCT and optical scanning data of the extracted upper anterior tooth and the apicoectomy plaster model were introduced into the Geomagic Studio 2012 software. The multi-source data fusion technology was used to virtually simulate the three-dimensional positional relationship of the extracted tooth, the dentition, the alveolar bone and the gingival, based on which, the three-dimensional design of the apicoectomy guide template was completed in the Geomagic Studio 2012 software. With the technology of fused deposition modeling, the apical resection surgical guide template was three-dimensionally printed with the material of polylactic acid (PLA). Under the guidance of the surgical guide template, the root apical resection was performed on the plaster model. After the apicoectomy, the extracted upper anterior tooth was taken off from the apicoectomy plaster model and then was given the optical scanning. The apical resection length and angle were calculated by the function of distance measurement and angle measurement, and the results were compared with the preset values.@*RESULTS@#The length of the apical resection was 2.88 mm along the direction of the long axis of the tooth, which was 0.12 mm lower than the preset 3 mm. The included angle between the apical resection plane and the long axis of the tooth was 77.9°, 12.1° lower than the preset 90°.@*CONCLUSION@#This study successfully established a digital design and production method of apicoectomy guide template by combing the multi-source data fusion, CAD and FDM technology. The design route and the production method are feasible. The study will provide a technology and methodology reference for the development of domestic special software for the digital design of apicoectomy guide template.

Detection of root cracks after root canal preparation using rotary NiTi systems by optical coherence tomography (OCT) scan / 北京大学学报(医学版)

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.

Clinical effects of calcium hydroxide-based sealer on chronic apical periodontitis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the results of calcium hydroxide-based sealer Sealapex in the treatment of chronic apical periodontitis.</p><p><b>METHODS</b>A total of 100 cases with chronic apical periodontitis were included and divided into two groups, calcium hydroxide sealer (Sealapex) group and ZOE sealer group, and Sealapex and ZOE sealer were respectively used. All cases were followed up for two years after treatment and the clinical results compared between the two groups. The evaluation was based on clinical examination and radiographic assessment using periapical index (PAI) and digital subtraction radiography (DSR) technique.</p><p><b>RESULTS</b>There was no significant difference between the ZOE group and Sealapex group in overall healing rates and mean quantitative analysis at 3 months and 2 years after treatment (P = 0.206, 0.776). A correlation was found between PAI and DSR (P < 0.01, gamma = 0.58).</p><p><b>CONCLUSIONS</b>Sealapex sealer could obtain satisfactory effects for the treatment of chronic apical periodontitis. The combination of DSR and PAI methods was able to monitor the radiographic bone changes of periapical disease.</p>