This study aims to develop a fully automated method for tooth segmentation and root canal measurement based on cone beam computed tomography (CBCT) images, providing objective, efficient, and accurate measurement results to guide and assist clinicians in root canal diagnosis grading, instrument selection, and preoperative planning. The method utilized Attention U-Net to recognize tooth descriptors, cropped regions of interest (ROIs) based on the center of mass of these descriptors, and applied an integrated deep learning method for segmentation. The segmentation results were mapped back to the original coordinates and position-corrected, followed by automatic measurement and visualization of root canal lengths and angles. The results indicated that the Dice coefficient for segmentation was 96.42%, the Jaccard coefficient was 93.11%, the Hausdorff Distance was 2.07 mm, and the average surface distance was 0.23 mm, all of which surpassed existing methods. The relative error of the root canal working length measurement was 3.15% (< 5%), the curvature angle error was 2.85 °, and the correct classification rate of the treatment difficulty coefficient was 90.48%. The proposed methods all achieved favorable results, which can provide an important reference for clinical application.
Cone-Beam Computed Tomography/methods* ; Deep Learning ; Humans ; Dental Pulp Cavity/diagnostic imaging* ; Image Processing, Computer-Assisted/methods*

OBJECTIVE: To evaluate the filling quality of single cone obturation in root canal model with irregular structure (Hus&Kim Ⅴ, Yin Ⅱ-type isthmus) which established by 3D printing technology using slices and radiographic methods, in order to provide reference for clinical practice. METHODS: (1) Extracted fresh premolars with Hus&Kim Ⅴ and Yin-type Ⅱ isthmus were collected and scanned by cone-beam computed tomography (CBCT), then standard root canal models were designed and printed. Rhodamine B staining and bias fitting were used to verify the availability of the models. (2) 30 root canal models were randomly divided into 3 groups according to different filling methods (n=10). CONTROL GROUP: vertical compaction obturation; Experimental group 1: single cone obturation with 0.06-taper cone (30#); Experimental group 2: single cone obturation with 0.04-taper cone (35#), GuttaFlow 2 as canal sealers. Slices were taken at 2, 4, 6, and 8 mm from the root apex in the direction perpendicular to the long axis of the root and observed under a stereomicroscope to calculate the percentage of filling area (PAV), percentage of gutta-percha-filled area (PGFA), percentage of sealer filled area (PSFA). (3) On the basis of the above results, two groups (n=4) were selected to further analyze the filling quality by micro-computed tomography (Micro-CT), the filling volume of main root canal and the isthmus were obtained, and the percentage of filling volume (PFV) was calculated. Two-way ANOVA was used to evaluate the differences between the groups, and Tukey' s multiple comparison was used to compare the data between the groups and within the groups. RESULTS: (1) Rhodamine B staining solution could overflow the apical foramen, and the main root canal system and the isthmus area were stained, showed no remnants of support material. The 3D standard deviation of the printed model data was 0.03 mm, and the average fitting distance was 0.02 mm. (2) The PFA of the two experimental groups were both significantly lower than that of the control group (F=45.04, P < 0.01). There was no statistical difference of the PFA at apical 2 and 4 mm between the two experimental groups (P>0.01), but at the middle and coronal portions of the root canal (6, 8 mm), the PFA of the experimental group 1 was higher than that of the experimental group 2 (P < 0.01). PFA in the apical 2, 4 mm of the two experimental groups were both lower than that in the middle and coronal portions 6, 8 mm of the canal (P < 0.01). There was no difference in the PGFA and PSFA between the two experimental groups at the apical 2, 4 mm (F=2.383, P>0.01). (3) The results of Micro-CT showed that the PFV of the experimental group 1 was statistically different with the control group (F=47.33, P < 0.01). The PFV of the experimental group 1 was 54.33%±4.35% in the isthmus and 78.31%±4.21% in the main root canal, which were both lower than the PFV of the control group of 76.48%±4.89% (isthmus) and 86.90%±3.29% (main root canal, P < 0.01). The PFV of the main root canal in the experimental group 1 was higher than that in the isthmus (P < 0.01), while there was no difference between the isthmus and the main root canal in the control group (P>0.01). CONCLUSION In the irregular root canal structure with isthmus, using large-taper gutta-percha can improve the filling quality of the middle and upper part of the canal, but the percentage of filling volume in the isthmus is lower than that of the main canal, and more technical improvements are needed.
Humans ; Root Canal Obturation/methods* ; Cone-Beam Computed Tomography ; Root Canal Filling Materials ; Dental Pulp Cavity/diagnostic imaging* ; Printing, Three-Dimensional ; In Vitro Techniques ; Gutta-Percha ; Bicuspid

Fused teeth are usually formed by the partial or complete fusion of two normal tooth germs during the development process and belong to dental developmental abnormalities. Fused teeth are relatively rare clinically, and those occurring in the posterior tooth area are even rarer. This article reports a case of fused teeth between the first permanent molar and the second permanent molar in the right mandible. This fused tooth had a complex root canal anatomical structure (seven root canals). The number and location of the root canals were analyzed by cone beam computed tomography, and root canal treatment was successfully completed with the assistance of microscope.
Humans ; Molar/diagnostic imaging* ; Mandible ; Dental Pulp Cavity/abnormalities* ; Cone-Beam Computed Tomography ; Root Canal Therapy/methods* ; Fused Teeth/surgery*

OBJECTIVES: This study aimed to evaluate the filling effects of three biomaterial root canal sealers [iRoot SP, C-Root SP, and GuttaFlow Bioseal (GFB)] by using Micro-CT. METHODS: Sixty single-canal detached premolars were selected. After crown amputation, their uniform working length was set at 12 mm and prepared to a 06 taper 30# with M3 nickel-titanium file. The samples were randomly divided into six groups with different sealers and obturation techniques: iRoot SP+single-cone technique (SC), C-Root SP+SC, GFB+SC, iRoot SP+single cone-mediated ultrasonic technique (SU), C-Root SP+SU, and GFB+SU. Samples were scanned by Micro-CT, and the total and segmented filling rates were calculated with Mimics 22.0 software after 3D reconstruction. RESULTS: The overall filling rate of the three biomaterial root canal sealers was higher than 90%. The overall and coronal third and middle third segment filling rate of groups iRoot SP+SC, C-Root SP+SC was higher than that of group GFB+SC (P<0.01), with no significant difference between groups iRoot SP+SC and C-Root SP+SC (P>0.05). On the apical third, no significant difference was found among each group (P>0.05). The overall and segment filling rate of groups iRoot SP+SU and C-Root SP+SU was higher than that of GFB+SU (P<0.01), with no significant difference between groups iRoot SP+SU and C-Root SP+SU (P>0.05). The filling rate of the apical 1/3 of group C-Root+SC was lower than that of group C-Root+SU (P<0.01), and the filling rate of the coronal 1/3 of group GFB+SC was higher than that in the GFB+SU (P<0.01). Nevertheless, no significant difference was found in other filling rate of two obturation techniques (P>0.05). CONCLUSIONS The overall filling rate of the three biomaterial root canal sealers using SC and SU are satisfactory. iRoot SP and C-Root SP have similar filling rates, which are significantly higher than that of GFB. C-Root SP combined with SU technique can improve the filling quality of the root apical.
Root Canal Filling Materials ; X-Ray Microtomography ; Humans ; Root Canal Obturation/methods* ; Gutta-Percha ; Dimethylpolysiloxanes ; Drug Combinations ; Dental Pulp Cavity/diagnostic imaging* ; Bicuspid

OBJECTIVE: To construct a model of Enterococcus faecalis (E. faecalis) infection in dentinal tubules by gradient centrifugation and to evaluate the antibacterial effect of low-temperature plasma on E. faecalis in dentinal tubules. METHODS: Standard dentin blocks of 4 mm×4 mm×2 mm size were prepared from single root canal isolated teeth without caries, placed in the E. faecalis bacterial solution, centrifuged in gradient and incubated for 24 h to establish the model of dentinal tubule infection with E. faecalis. The twenty dentin blocks of were divided into five groups, low-temperature plasma jet treatment for 0, 5 and 10 min, calcium hydroxide paste sealing for 7 d and 2% chlorhexidine gel sealing for 7 d. Scanning electron microscopy and confocal laser scanning microscope were used to assess the infection in the dentinal tubules and the antibacterial effect of low-temperature plasma. RESULTS: The results of scanning electron microscopy and confocal laser scanning microscopy showed that after 24 h of incubation by gradient centrifugation, E. faecalis could fully enter the dentinal tubules to a depth of more than 600μm indicating that this method was time-saving and efficient and could successfully construct a model of E. faecalis infection in dentinal tubules. Low-temperature plasma could enter the dentinal tubules and play a role, the structure of E. faecalis was still intact after 5 min of low-temperature plasma treatment, with no obvious damage, and after 10 min of low-temperature plasma treatment, the surface morphology of E. faecalis was crumpled and deformed, the cell wall was seriously collapsed, and the normal physiological morphology was damaged indicating that the majority of E. faecalis was killed in the dentinal tubules. The antibacterial effect of low-temperature plasma treatment for 10 min exceeded that of the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d. These two chemicals had difficulty entering deep into the dentinal tubules, and therefore only had a few of antibacterial effect on the bacterial biofilm on the root canal wall, and there was also no significant damage to the E. faecalis bacterial structure. CONCLUSION Gradient centrifugation could establish the model of E. faecalis dentin infection successfully. Low-temperature plasma treatment for 10 min could kill E. faecalis in dentinal tubules effectively, which is superior to the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d.
Chlorhexidine/pharmacology* ; Calcium Hydroxide/pharmacology* ; Enterococcus faecalis/physiology* ; Temperature ; Dentin ; Biofilms ; Anti-Bacterial Agents/pharmacology* ; Root Canal Irrigants/pharmacology* ; Dental Pulp Cavity

Dens invaginatus is a rare developmental anomaly of the teeth that is caused by the infolding of enamel organs or the penetration of their proliferations into dental papillae before calcification has occurred. The presence of double dens invaginatus is extremely rare. This paper describes the use of cone beam computed tomography in the evaluation of a maxillary lateral incisor with double dens invaginatus and periapical periodontitis. The tooth was treated through microscopic root canal therapy. The tooth was free of clinical symptoms, and the periradicular lesion narrowed during the follow-up period of 1 year.
Humans ; Dental Pulp Cavity/abnormalities* ; Dens in Dente/pathology* ; Incisor/pathology* ; Root Canal Therapy ; Periapical Periodontitis/pathology*

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.
Humans ; Dental Pulp Cavity/diagnostic imaging* ; Bicuspid/anatomy & histology* ; Mandible ; Tooth Root/anatomy & histology* ; Root Canal Therapy

When the use of root canal retreatment and apical surgery experiences difficulty in treating endodontic diseases, intentional replantation is an optional clinical technique used to retain the tooth. A 28-year-old female complained of chewing discomfort at the mandibular second molar after undergoing root canal treatment 3 month ago. History record and radiographic examination revealed that a C-shaped root canal system was filled with gutta-percha in the mandibular second molar. A radiolucency area existed at the root furcal area with a thin canal wall in the distal and mesial roots. Intentional replantation was used to treat this tooth. The clinical and radiographic results showed that intentional replantation and nano-biomaterial application facilitated infection control, tooth retention, and periodontal tissue regeneration.
Female ; Humans ; Adult ; Tooth Replantation ; Root Canal Therapy ; Dental Pulp Cavity ; Gutta-Percha/therapeutic use* ; Tooth Root ; Molar/surgery* ; Retreatment

OBJECTIVES: This study aimed to compare the effectiveness of ultrasound and acoustic and laser cleaning of curved root canals. METHODS: A total of 92 molars with independent root canals with a curvature of 20°-40° were prepared and standardized at 04 25# and stained with gentian violet solution for 72 h. Among them, 52 were randomly divi-ded into four groups for final rinsing (n=13): NI group, PUI group, EDDY group, and PIPS group. Ten samples in each group were cut horizontally along the long axis perpendicular to the root and divided into curved upper, curved, and apical segments. Images were taken with a stereomicroscope and Image J measurements were taken to calculate the depth of rinse penetration. The remaining three samples from each group were split along the long axis of the dentin, photographed by scanning electron microscope to record the dentin tubule exposure and staining layer, and scored for staining layer by double-blind method. SPSS 26.0 software was used to perform statistical analysis and select the best flushing method. An extra 40 samples were randomly divided into four groups for detection of flushing fluid penetration depth (n=10): 10, 20, 30, and 40 s. RESULTS: In the upper part, the mean depth of infiltration was not significantly different between the experimental and control groups (P>0.05). The PIPS group had a significantly lower smear layer score than the control group and the EDDY group (P<0.01). In the curved segment, the mean depth of infiltration was significantly greater in the PUI group than in the control group (P<0.05); the tarnish layer score was lower in each experimental group than in the control group. At the top, the mean depth of infiltration was greater in the PUI and PIPS groups than in the control group (P<0.05), and the smear layer score was lower in the PIPS group than in the other groups (P<0.05). After the time was changed, the depth of infiltration of PUI increased only in the apical segment as the flushing time increased. CONCLUSIONS The PUI and PIPS methods facilitate the penetration of irrigation solution into the dentin canal in curved root canals, especially in the apical segment. The PIPS technique is effective in removing the smear layer in curved root canals.
Humans ; Dental Pulp Cavity ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; Root Canal Preparation/methods* ; Smear Layer ; Sodium Hypochlorite ; Therapeutic Irrigation/methods* ; Double-Blind Method

Humans ; Dental Pulp Cavity ; Molar ; Root Canal Therapy