Calcium hydroxide(CH) is applied to improve disinfection of root canals in most root canal retreatment. This study aimed to analyze the CH removal efficacy using 7 different root preparing files(K file, pre-curved ...Calcium hydroxide(CH) is applied to improve disinfection of root canals in most root canal retreatment. This study aimed to analyze the CH removal efficacy using 7 different root preparing files(K file, pre-curved K file, EndoActivator, Ultrasonic file, pre-curved ultrasonic file, F file and needle irrigation alone) with apical transportation. Standardized models of curved canal with such apical transportation or not were set up before applying CH to root canal for 7 days. Seven techniques described above were used for its removal. Then the roots were disassembled and digital photos were taken. The ratio of residual CH in the overall canal surface was calculated using the image analyzer image pro plus 6.0. The data were analyzed using one-way ANOVA with post hoc Tukey test. Results revealed that CH was effectively removed(P〈0.05) by using all 6 mechanical methods except irrigation alone. In curved root canals with apical transportation, EndoActivator, pre-curved ultrasonic file and F file were found to be more effective in removing CH than the other four file(P〈0.001), while there was no significant difference among EndoActivator, pre-curved ultrasonic file and F file groups(P〉0.05). The percentage of residual CH in the canal with apical transportation was higher than that in the canal without apical transportation(P〈0.05). In conclusion, CH can be hardly removed completely. Canal with apical transportation will result in insufficient CH removal. EndoActivator, pre-curved ultrasonic file and F file are more effective in the curved root canal with apical transportation.展开更多
BACKGROUND The presence of dens invaginatus(DI)complicates treatment of any tooth,from diagnosis to access cavity and biomechanical preparation and obturation.Reports of successful non-surgical management of DI type I...BACKGROUND The presence of dens invaginatus(DI)complicates treatment of any tooth,from diagnosis to access cavity and biomechanical preparation and obturation.Reports of successful non-surgical management of DI type IIIB in maxillary lateral incisor are rare.Here,we report such a case,with three root canals and a long follow-up.CASE SUMMARY A 13-year-old female patient presented with mild pain in the maxillary right lateral incisor(#7)for 10-15 d.On examination,the tooth was slightly rotated,with slight tenderness on percussion and grade I mobility but with no caries,pockets or restorations and non-vital pulp(via vitality tests).Radiographic examination revealed unusual configuration of the tooth’s root canals,with an enamel-lined invagination extending to the apex,suggesting the possibility of DI Oehler’s type IIIB and a periapical radiolucency.Widening the access cavity lingually revealed one distinct buccal orifice and two distinct palatal orifices;under higher magnification of a dental operating microscope(DOM),the mesio palatal and disto-palatal orifices were observed as connected by a C-shaped groove.The root canals were prepared with hand K-files following a step-back technique,and obturated using a combination technique of lateral condensation and vertical compaction.At the 6-year follow-up,the patient was asymptomatic,and the periapical radiography displayed significant healing around the apical end of the root.CONCLUSION Proper knowledge of unusual root canal anatomy is required in treating DI.Conventional methods of root canal treatment can successfully resolve such complex cases,facilitated by DOM and cone-beam computed tomography.展开更多
This study was designed to compare the impact of post and core systems on resistance to fracture of endodontically treated anterior teeth with flared root canals and to assess their fracture pattern. Sixty central inc...This study was designed to compare the impact of post and core systems on resistance to fracture of endodontically treated anterior teeth with flared root canals and to assess their fracture pattern. Sixty central incisors were cut horizontally 2 mm coronal to the cementoenamel junction(CEJ). After root canal therapy, teeth were assigned into 6 groups(n = 10 each) based on a post system and used as follows: Group C, non-flared root received size #1 glass fiber posts(Control); Group AP, flared root restored with anatomical post; Group RC, flared root restored with size #1 fiber post and cemented with thick layer of resin cement; Group CR, flared root restored with size #1 and reinforced with composite resin; Group CM, cast post-core; Group CP, CAD/CAM polymer-infiltrated ceramic post and core.Following post cementation, core build-up and crown insertion, the specimens were thermo-cycled up to 10,000 cycles(5 C/55 C; 30 seconds dwell time, 6 seconds transition time) and then statically loaded at 1 mm/minute crosshead speed using a universal testing machine. One-way ANOVA and Tukey HSD post hoc test(α= 0.05) were used for data analysis. Group C recorded significantly higher resistance to fracture values [(826.9±39.1) N] followed by group CP [(793.8±55.6) N] while group RC yielded the lowest fracture resistance values [(586.7±51.4) N]. The resistance to fracture of wide root canals can be enhanced by using one-piece CAM/CAM post and core as an alternative to the use of either glass fiber post, relined with composite resin increasing the thickness of luting cement or the use of cast post and core system. However, this was an in vitro investigation and further in vivo studies are necessary.展开更多
BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with o...BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with only two root canals, which have been rarely reported. We also perform a literature review of maxillary first molar anatomy.CASE SUMMARY The two patients were referred to the hospital after 1) finding a cavity in their tooth with a color change and, 2) a toothache during mastication, respectively.Both of these cases were diagnosed as apical periodontitis by X-ray imaging and cone beam computed tomography(CBCT). Non-surgical endodontic therapy was performed with the assistance of a dental operating microscope(DOM). CBCT showed rare but accurate images of both patients, each with two root canals and two roots in their maxillary first molars. Both roots were located in the buccal in the palatal direction, and each root had only one clear root canal. In addition,each maxillary first molar in both patients was symmetrical to that on the opposing side with only two separate root canals. Non-surgical endodontic therapy was performed with the assistance of a DOM. Finally, the teeth were restored using composite resin and the patients were satisfied with the results.CONCLUSION Making full use of CBCT and DOM would contribute to helping dentists make correct diagnoses and successfully treat teeth with rare root canal morphologies.展开更多
Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the fi...Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing preand post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes (surface area, changes in curvature and transportation) during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files (P=0.226). During preparation there was failure of only one file (the protaper group). In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems.展开更多
We studied whether obturing canals and restoring endodontic occlusal access cavities on upper premolars could provide acceptable resistance and pattern to fracture.Eighteen upper premolars were divided equally into 3 ...We studied whether obturing canals and restoring endodontic occlusal access cavities on upper premolars could provide acceptable resistance and pattern to fracture.Eighteen upper premolars were divided equally into 3 groups.Group 1 consisted of intact controls;group 2 had access cavities and root canal preparations;group 3 as in group 2 but obturated with gutta-percha and AH26,and the access cavity restored with glass ionomer and composite.Specimens were submitted to compressive strength testing using the Hounsfield Universal H50KM testing machine with a load cell of 2000 Newtons and a crosshead speed set at 1.0 mm/min until fracture.The results from the compressive strength tests showed that intact controls (1105.83±90.93 MPa) and restored premolars (936.67±44.67 MPa) were significantly different from premolars with unrestored access cavities 568.33±105.49 MPa.There was no significant difference between intact controls and restored premolars.The predominant fracture pattern for intact teeth was an oblique fracture.For premolars that had endodontic access cavities,restored or unrestored,the most common fracture pattern was a vertical fracture.The restoration of occlusal access cavities with glass ionomer and composite provided fracture resistance close to that of intact controls,but when restored teeth fractured,they were predominantly non-restorable.展开更多
BACKGROUND Root canal retreatment is common after root canal therapy in clinical situations.Especially,completing the retreatment of variant root canals can be challenging.This is particularly true for the molars loca...BACKGROUND Root canal retreatment is common after root canal therapy in clinical situations.Especially,completing the retreatment of variant root canals can be challenging.This is particularly true for the molars located at the end of the dental arch.However,advancements in digital dental diagnosis and treatment techniques can solve these problems.Here,we describe a case of a maxillary second molar with a variant distobuccal root canal treated via a novel“inlay-guided endodontics”technique based on improved computer-generated programs.CASE SUMMARY A 63-year-old man complained of a defect in the maxillary left second molar.The tooth,diagnosed with post-treatment endodontic disease,was initially treated by conventional methods,which were ineffective.Our“inlay-guided endodontics”technique was subsequently adopted,with the establishment of a precise integrated three-dimensional(3D)plate model of cone-beam computed tomography data and a digital impression of the dentition.An optimal root canal approach was generated for the“virtual file”in the 3D model.The plate data were imported into a 3D printer and printed.With the help of the guide plate,the file was accurately placed into the cervical third of the distal root canal.The root canal and prosthodontic treatments successfully proceeded subsequently.CONCLUSION Our newly developed inlay guide plates may facilitate individualized and minimally invasive root canal treatment.展开更多
BACKGROUND The incidence rate of severely curved root canals in mandibular molars is low,and the root canal treatment of mandibular molars with this aberrant canal anatomy may be technically challenging.CASE SUMMARY A...BACKGROUND The incidence rate of severely curved root canals in mandibular molars is low,and the root canal treatment of mandibular molars with this aberrant canal anatomy may be technically challenging.CASE SUMMARY A 26-year-old Chinese female patient presented with intermittent and occlusal pain in the left mandibular second molar.The patient had undergone filling restoration for caries before endodontic consultation.With the aid of cone beam computed tomography(CBCT),a large periapical radiolucency was observed,and curved root canals in a mandibular second molar were confirmed,depicting a severe and curved distolingual root.Nonsurgical treatments,including novel individualized preparation skills and techniques and the use of bioceramic materials as an apical barrier,were performed,and complete healing of the periapical lesion and a satisfactory effect were achieved.CONCLUSION A case of severely curved root canals in a mandibular second molar was successfully treated and are reported herein.The complex anatomy of the tooth and the postoperative effect were also evaluated via the three-dimensional reconstruction of CBCT images,which accurately identified the aberrant canal morphology.New devices and biomaterial applications combined with novel synthesis techniques can increase the success rate of intractable endodontic treatment.展开更多
Maxillary first molar usually exhibits a radicular anatomy of three roots and three or four canals. However, different anatomic variations like extra number of roots and canals are possible. For a successful treatment...Maxillary first molar usually exhibits a radicular anatomy of three roots and three or four canals. However, different anatomic variations like extra number of roots and canals are possible. For a successful treatment, clinicians must have well equipment and a thorough knowledge of the external and internal anatomy of teeth and its variation. Using of CBCT may help to locate extra canals by giving a chance to clinicians to see the root canal anatomy in 3-D view. The aim of this study was to present a case report about a diagnosis and treatment in maxillary first molar with three roots and five canals. It is concluded that the diagnosing and the treatment of unusual cases are key factors for successful endodontic treatment of these teeth.展开更多
Sixteen fresh extracted human teeth paired according to their anatomic locations,were divided into two groups at random.The root canais of the teeth in Group 1 were preparedwith an ultrasonic unit and those of Group 2...Sixteen fresh extracted human teeth paired according to their anatomic locations,were divided into two groups at random.The root canais of the teeth in Group 1 were preparedwith an ultrasonic unit and those of Group 2 with hand instruments.Then,the specimens wereobserved under a scanning electron microscope and their pnotographs were taken.Blindevaluation of cleanness was performed for each canal.Statistical dnalysis of the data indicatesthat the canal walls were cleaner in Group 1 than in Group 2 and that the ultrasonic preparationtook less time.展开更多
In the current study, 5-nydroxytryptamine (5-HT) and gastrin (GAS) cells in the digestive canals of Rana chensinensis tadpoles at different developmental stages were investigated by immunohistochemistry. Results s...In the current study, 5-nydroxytryptamine (5-HT) and gastrin (GAS) cells in the digestive canals of Rana chensinensis tadpoles at different developmental stages were investigated by immunohistochemistry. Results showed that the 5-HT cells were only detected in the duodenum before metamorphosis began, and were extensively distributed in the stomach, duodenum, small intestine, and rectum thereafter, with the highest counts found in the duodenum and rectum when metamorphosis was completed. The GAS cells were only distributed in the stomach and duodenum, and only rarely detected in the duodenum before metamorphosis began, but increased in the stomach during metamorphosis and showed zonal distribution in the gastric mucosa when metamorphosis was completed. Metamorphosis is a critical period for amphibians, during which structural and functional physiological adaptations are required to transition from aquatic to terrestrial environments. During metamorphosis, the differentiations of 5-HT cells in the gastrointestinal canals of tadpoles could facilitate mucus secretion regulation, improve digestive canal lubrication, and help water- shortage food digestion in terrestrial environments. Conversely, GAS cell differentiations during metamorphosis might contribute to the digestive and absorptive function transition from herbivore to omnivore.展开更多
BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of en...BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of endodontic treatment and prognosis.This article presents an endodontically managed left maxillary first molar with an unusual palatal root morphology.The available literature on the anatomic variation of maxillary first molars is also reviewed.CASE SUMMARY A 36-year-old man with no medical history presented to the Stomatology Department of Peking University Third Hospital complaining of a toothache during mastication in the maxillary left posterior region for approximately 3 mo.He had a spontaneous and intermittent toothache that had worsened,particularly at night.The diagnosis based on clinical examination,X-ray imaging,and cone beam computed tomography(CBCT)was symptomatic irreversible pulpitis.Nonsurgical endodontic therapy was performed for the left maxillary first molar.Five root canals revealed by CBCT included a special palatal root canal(1-2-1-shaped),two mesiobuccal root canals,and one distobuccal root canal.Evaluation of the CBCT images confirmed the root canal morphology and the clinician performed more effective cleaning,obturation,and therapy.Finally,the tooth was restored using composite resin,and the patient was satisfied with the result.CONCLUSION CBCT and a complete review of the literature may be beneficial for investigating the root canal system to achieve a biological and functional therapeutic effect.展开更多
Aim: the aim of this study was to investigate the shaping ability of thermomechanically treated files manufactured by twisting(Twisted files)and compare it to conventional rotary system (K3, Sybron Endo, Orange, CA) i...Aim: the aim of this study was to investigate the shaping ability of thermomechanically treated files manufactured by twisting(Twisted files)and compare it to conventional rotary system (K3, Sybron Endo, Orange, CA) in S-shaped canals, including formation of ledges, zipping, elbow, outer widening, danger zone, perforation and file deformation. Materials & Methods: Forty S-Shaped canals in resin blocks were randomly divided into 2 groups of 20 each. Pre-instrumentation images of the canals were taken via a digital camera and superimposed on images taken after preparation with TF and K3 systems to apical size of 25/06 and 30/06. Canal aberrations were measured from the superimposed image at five levels using AutoCAD system. Fisher exact test and Mann Whitney test were used for analysis of the data. Results: the incidence of zipping, elbow and apical transportation was significantly lower in the TF group (P = 0.04). Generally the incidence of aberration increased when the apical size increased to 30/0.06 regardless of the file system. Significant file deformation was evident in the TF after single use (P ? 0.001). Conclusion: Under the conditions of this study, TF manufactured by new technique performed better than K3 systems when used up to size 25/06 in simulated S-shaped canals. Clinical significance: The flexibility of thermomechanically treated files is beneficial in canals with multiple curvatures;however, attention should be paid to the instrument taper and final apical size of the preparation.展开更多
Every year, a number of breach failures occur in Irrigation Canals in Sindh. Those failures cause displacement of thousands of people, destruction of properties, land, and damage to costly crops that worth millions Ru...Every year, a number of breach failures occur in Irrigation Canals in Sindh. Those failures cause displacement of thousands of people, destruction of properties, land, and damage to costly crops that worth millions Rupees. In addition to that, breach failures also can cause water shortages when the failure occurs during the peak demand period. There are various causes of embankment failures which include overtopping, internal erosion, structural defects and piping. State of art for breach failures is presented in this paper and suggestions for prediction of breaches in context to canals in Sindh are discussed. Seepage and slope stability analyses are recommended for a long-term breach predictions.展开更多
Tropical peat comprises decomposed dead plant material and acts like a sponge to absorb water,making it fully saturated.However,drought periods dry it readily and increases its vulnerability to fire.Peat fires emit gr...Tropical peat comprises decomposed dead plant material and acts like a sponge to absorb water,making it fully saturated.However,drought periods dry it readily and increases its vulnerability to fire.Peat fires emit greenhouse gases and particles contributing to haze,and prevention by constructing fire-break canals to reduce fire spread into forest reserves is crucial.This paper aims to determine peat physical and chemical properties near a fire-break canal at different fire frequency areas.Peat sampling was conducted at two forest reserves in Malaysia which represent low fire frequency and high fire frequency areas.The results show that peat properties were not affected by the construction of a fire-break canal,however lignin and cellulose content increased significantly from the distance of the canal in both areas.The study concluded that fire frequency did not significantly influence peat properties except for porosity.The higher fibre content in the high frequency area did not influence moisture content nor the ability to regain moisture.Thus,fire frequency might contribute differently to changes in physical and chemical properties,hence management efforts to construct fire-break canals and restoration efforts should protect peatlands from further degradation.These findings will benefit future management and planning for forest reserves.展开更多
BACKGROUND Primary intraspinal malignant melanoma is a very rare tumor that most often occurs in the cervical,thoracic,or thoracolumbar segment.CASE SUMMARY A rare case of primary thoracolumbar malignant melanoma is d...BACKGROUND Primary intraspinal malignant melanoma is a very rare tumor that most often occurs in the cervical,thoracic,or thoracolumbar segment.CASE SUMMARY A rare case of primary thoracolumbar malignant melanoma is described.A 45-year-old female patient complained of low back pain with numbness and fatigue in both lower limbs.MR revealed an intradural space-occupying lesion at the thoracic 12 to lumbar 1 level.The tumor was partially excised,and a malignant melanoma was confirmed by histopathology.CONCLUSION Primary intraspinal malignant melanoma has rarely been reported,and surgical resection and related characteristics and diagnoses have been discussed.展开更多
BACKGROUND We report a rare case of cervical spinal canal penetrating trauma and review the relevant literatures.CASE SUMMARY A 58-year-old male patient was admitted to the emergency department with a steel bar penetr...BACKGROUND We report a rare case of cervical spinal canal penetrating trauma and review the relevant literatures.CASE SUMMARY A 58-year-old male patient was admitted to the emergency department with a steel bar penetrating the neck,without signs of neurological deficit.Computed tomography(CT)demonstrated that the steel bar had penetrated the cervical spinal canal at the C6–7 level,causing C6 and C7 vertebral body fracture,C6 left lamina fracture,left facet joint fracture,and penetration of the cervical spinal cord.The steel bar was successfully removed through an open surgical procedure by a multidisciplinary team.During the surgery,we found that the cervical vertebra,cervical spinal canal and cervical spinal cord were all severely injured.Postoperative CT demonstrated severe penetration of the cervical spinal canal but the patient returned to a fully functional level without any neurological deficits.CONCLUSION Even with a serious cervical spinal canal penetrating trauma,the patient could resume normal work and life after appropriate treatment.展开更多
This study organized the current status of tangible cultural heritage along the Tonghui River.The spaces along the Tonghui River were classified according to the farmland,suburban areas,urban residential areas,and urb...This study organized the current status of tangible cultural heritage along the Tonghui River.The spaces along the Tonghui River were classified according to the farmland,suburban areas,urban residential areas,and urban center areas.Spatial analysis of the current situation was conducted through Baidu Street View images,with a focus on evaluating the spatial environment around the tangible cultural heritage.Negative factors affecting the reuse of cultural heritage were analyzed,such as poor appearance of buildings and low accessibility of transportation along the Tonghui River.展开更多
基金supported by the National Natural Science Foundation of China(No.81200781)
文摘Calcium hydroxide(CH) is applied to improve disinfection of root canals in most root canal retreatment. This study aimed to analyze the CH removal efficacy using 7 different root preparing files(K file, pre-curved K file, EndoActivator, Ultrasonic file, pre-curved ultrasonic file, F file and needle irrigation alone) with apical transportation. Standardized models of curved canal with such apical transportation or not were set up before applying CH to root canal for 7 days. Seven techniques described above were used for its removal. Then the roots were disassembled and digital photos were taken. The ratio of residual CH in the overall canal surface was calculated using the image analyzer image pro plus 6.0. The data were analyzed using one-way ANOVA with post hoc Tukey test. Results revealed that CH was effectively removed(P〈0.05) by using all 6 mechanical methods except irrigation alone. In curved root canals with apical transportation, EndoActivator, pre-curved ultrasonic file and F file were found to be more effective in removing CH than the other four file(P〈0.001), while there was no significant difference among EndoActivator, pre-curved ultrasonic file and F file groups(P〉0.05). The percentage of residual CH in the canal with apical transportation was higher than that in the canal without apical transportation(P〈0.05). In conclusion, CH can be hardly removed completely. Canal with apical transportation will result in insufficient CH removal. EndoActivator, pre-curved ultrasonic file and F file are more effective in the curved root canal with apical transportation.
基金Supported by Deanship of Scientific Research at King Khalid University,Abha,Saudi Arabia through the Small Groups Project,No. RGP. 1/351/43
文摘BACKGROUND The presence of dens invaginatus(DI)complicates treatment of any tooth,from diagnosis to access cavity and biomechanical preparation and obturation.Reports of successful non-surgical management of DI type IIIB in maxillary lateral incisor are rare.Here,we report such a case,with three root canals and a long follow-up.CASE SUMMARY A 13-year-old female patient presented with mild pain in the maxillary right lateral incisor(#7)for 10-15 d.On examination,the tooth was slightly rotated,with slight tenderness on percussion and grade I mobility but with no caries,pockets or restorations and non-vital pulp(via vitality tests).Radiographic examination revealed unusual configuration of the tooth’s root canals,with an enamel-lined invagination extending to the apex,suggesting the possibility of DI Oehler’s type IIIB and a periapical radiolucency.Widening the access cavity lingually revealed one distinct buccal orifice and two distinct palatal orifices;under higher magnification of a dental operating microscope(DOM),the mesio palatal and disto-palatal orifices were observed as connected by a C-shaped groove.The root canals were prepared with hand K-files following a step-back technique,and obturated using a combination technique of lateral condensation and vertical compaction.At the 6-year follow-up,the patient was asymptomatic,and the periapical radiography displayed significant healing around the apical end of the root.CONCLUSION Proper knowledge of unusual root canal anatomy is required in treating DI.Conventional methods of root canal treatment can successfully resolve such complex cases,facilitated by DOM and cone-beam computed tomography.
文摘This study was designed to compare the impact of post and core systems on resistance to fracture of endodontically treated anterior teeth with flared root canals and to assess their fracture pattern. Sixty central incisors were cut horizontally 2 mm coronal to the cementoenamel junction(CEJ). After root canal therapy, teeth were assigned into 6 groups(n = 10 each) based on a post system and used as follows: Group C, non-flared root received size #1 glass fiber posts(Control); Group AP, flared root restored with anatomical post; Group RC, flared root restored with size #1 fiber post and cemented with thick layer of resin cement; Group CR, flared root restored with size #1 and reinforced with composite resin; Group CM, cast post-core; Group CP, CAD/CAM polymer-infiltrated ceramic post and core.Following post cementation, core build-up and crown insertion, the specimens were thermo-cycled up to 10,000 cycles(5 C/55 C; 30 seconds dwell time, 6 seconds transition time) and then statically loaded at 1 mm/minute crosshead speed using a universal testing machine. One-way ANOVA and Tukey HSD post hoc test(α= 0.05) were used for data analysis. Group C recorded significantly higher resistance to fracture values [(826.9±39.1) N] followed by group CP [(793.8±55.6) N] while group RC yielded the lowest fracture resistance values [(586.7±51.4) N]. The resistance to fracture of wide root canals can be enhanced by using one-piece CAM/CAM post and core as an alternative to the use of either glass fiber post, relined with composite resin increasing the thickness of luting cement or the use of cast post and core system. However, this was an in vitro investigation and further in vivo studies are necessary.
文摘BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with only two root canals, which have been rarely reported. We also perform a literature review of maxillary first molar anatomy.CASE SUMMARY The two patients were referred to the hospital after 1) finding a cavity in their tooth with a color change and, 2) a toothache during mastication, respectively.Both of these cases were diagnosed as apical periodontitis by X-ray imaging and cone beam computed tomography(CBCT). Non-surgical endodontic therapy was performed with the assistance of a dental operating microscope(DOM). CBCT showed rare but accurate images of both patients, each with two root canals and two roots in their maxillary first molars. Both roots were located in the buccal in the palatal direction, and each root had only one clear root canal. In addition,each maxillary first molar in both patients was symmetrical to that on the opposing side with only two separate root canals. Non-surgical endodontic therapy was performed with the assistance of a DOM. Finally, the teeth were restored using composite resin and the patients were satisfied with the results.CONCLUSION Making full use of CBCT and DOM would contribute to helping dentists make correct diagnoses and successfully treat teeth with rare root canal morphologies.
文摘Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing preand post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes (surface area, changes in curvature and transportation) during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files (P=0.226). During preparation there was failure of only one file (the protaper group). In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems.
文摘We studied whether obturing canals and restoring endodontic occlusal access cavities on upper premolars could provide acceptable resistance and pattern to fracture.Eighteen upper premolars were divided equally into 3 groups.Group 1 consisted of intact controls;group 2 had access cavities and root canal preparations;group 3 as in group 2 but obturated with gutta-percha and AH26,and the access cavity restored with glass ionomer and composite.Specimens were submitted to compressive strength testing using the Hounsfield Universal H50KM testing machine with a load cell of 2000 Newtons and a crosshead speed set at 1.0 mm/min until fracture.The results from the compressive strength tests showed that intact controls (1105.83±90.93 MPa) and restored premolars (936.67±44.67 MPa) were significantly different from premolars with unrestored access cavities 568.33±105.49 MPa.There was no significant difference between intact controls and restored premolars.The predominant fracture pattern for intact teeth was an oblique fracture.For premolars that had endodontic access cavities,restored or unrestored,the most common fracture pattern was a vertical fracture.The restoration of occlusal access cavities with glass ionomer and composite provided fracture resistance close to that of intact controls,but when restored teeth fractured,they were predominantly non-restorable.
基金the Youth Development Project of Army Military Medical University,No.2018XQN014the Clinical Innovation Project of Army Military Medical University,No.2019XLC2014the Science and Technology Foundation of Chongqing,China,No.cstc2014jcyjA10092.
文摘BACKGROUND Root canal retreatment is common after root canal therapy in clinical situations.Especially,completing the retreatment of variant root canals can be challenging.This is particularly true for the molars located at the end of the dental arch.However,advancements in digital dental diagnosis and treatment techniques can solve these problems.Here,we describe a case of a maxillary second molar with a variant distobuccal root canal treated via a novel“inlay-guided endodontics”technique based on improved computer-generated programs.CASE SUMMARY A 63-year-old man complained of a defect in the maxillary left second molar.The tooth,diagnosed with post-treatment endodontic disease,was initially treated by conventional methods,which were ineffective.Our“inlay-guided endodontics”technique was subsequently adopted,with the establishment of a precise integrated three-dimensional(3D)plate model of cone-beam computed tomography data and a digital impression of the dentition.An optimal root canal approach was generated for the“virtual file”in the 3D model.The plate data were imported into a 3D printer and printed.With the help of the guide plate,the file was accurately placed into the cervical third of the distal root canal.The root canal and prosthodontic treatments successfully proceeded subsequently.CONCLUSION Our newly developed inlay guide plates may facilitate individualized and minimally invasive root canal treatment.
基金Supported by Natural Science Foundation of Hunan Province,No.S2021JJQNJJ1682Changsha Municipal Natural Science Foundation,No.kq 2014215.
文摘BACKGROUND The incidence rate of severely curved root canals in mandibular molars is low,and the root canal treatment of mandibular molars with this aberrant canal anatomy may be technically challenging.CASE SUMMARY A 26-year-old Chinese female patient presented with intermittent and occlusal pain in the left mandibular second molar.The patient had undergone filling restoration for caries before endodontic consultation.With the aid of cone beam computed tomography(CBCT),a large periapical radiolucency was observed,and curved root canals in a mandibular second molar were confirmed,depicting a severe and curved distolingual root.Nonsurgical treatments,including novel individualized preparation skills and techniques and the use of bioceramic materials as an apical barrier,were performed,and complete healing of the periapical lesion and a satisfactory effect were achieved.CONCLUSION A case of severely curved root canals in a mandibular second molar was successfully treated and are reported herein.The complex anatomy of the tooth and the postoperative effect were also evaluated via the three-dimensional reconstruction of CBCT images,which accurately identified the aberrant canal morphology.New devices and biomaterial applications combined with novel synthesis techniques can increase the success rate of intractable endodontic treatment.
文摘Maxillary first molar usually exhibits a radicular anatomy of three roots and three or four canals. However, different anatomic variations like extra number of roots and canals are possible. For a successful treatment, clinicians must have well equipment and a thorough knowledge of the external and internal anatomy of teeth and its variation. Using of CBCT may help to locate extra canals by giving a chance to clinicians to see the root canal anatomy in 3-D view. The aim of this study was to present a case report about a diagnosis and treatment in maxillary first molar with three roots and five canals. It is concluded that the diagnosing and the treatment of unusual cases are key factors for successful endodontic treatment of these teeth.
文摘Sixteen fresh extracted human teeth paired according to their anatomic locations,were divided into two groups at random.The root canais of the teeth in Group 1 were preparedwith an ultrasonic unit and those of Group 2 with hand instruments.Then,the specimens wereobserved under a scanning electron microscope and their pnotographs were taken.Blindevaluation of cleanness was performed for each canal.Statistical dnalysis of the data indicatesthat the canal walls were cleaner in Group 1 than in Group 2 and that the ultrasonic preparationtook less time.
基金This study was supported by the Natural Science Foundation of Shaanxi Province (SJ08C101) and the Fundamental Research Funds for the Central Universities (GK200902039).
文摘In the current study, 5-nydroxytryptamine (5-HT) and gastrin (GAS) cells in the digestive canals of Rana chensinensis tadpoles at different developmental stages were investigated by immunohistochemistry. Results showed that the 5-HT cells were only detected in the duodenum before metamorphosis began, and were extensively distributed in the stomach, duodenum, small intestine, and rectum thereafter, with the highest counts found in the duodenum and rectum when metamorphosis was completed. The GAS cells were only distributed in the stomach and duodenum, and only rarely detected in the duodenum before metamorphosis began, but increased in the stomach during metamorphosis and showed zonal distribution in the gastric mucosa when metamorphosis was completed. Metamorphosis is a critical period for amphibians, during which structural and functional physiological adaptations are required to transition from aquatic to terrestrial environments. During metamorphosis, the differentiations of 5-HT cells in the gastrointestinal canals of tadpoles could facilitate mucus secretion regulation, improve digestive canal lubrication, and help water- shortage food digestion in terrestrial environments. Conversely, GAS cell differentiations during metamorphosis might contribute to the digestive and absorptive function transition from herbivore to omnivore.
基金Supported by the National Natural Science Foundation of China,No.81800983Beijing Natural Science Foundation,No.7164310.
文摘BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of endodontic treatment and prognosis.This article presents an endodontically managed left maxillary first molar with an unusual palatal root morphology.The available literature on the anatomic variation of maxillary first molars is also reviewed.CASE SUMMARY A 36-year-old man with no medical history presented to the Stomatology Department of Peking University Third Hospital complaining of a toothache during mastication in the maxillary left posterior region for approximately 3 mo.He had a spontaneous and intermittent toothache that had worsened,particularly at night.The diagnosis based on clinical examination,X-ray imaging,and cone beam computed tomography(CBCT)was symptomatic irreversible pulpitis.Nonsurgical endodontic therapy was performed for the left maxillary first molar.Five root canals revealed by CBCT included a special palatal root canal(1-2-1-shaped),two mesiobuccal root canals,and one distobuccal root canal.Evaluation of the CBCT images confirmed the root canal morphology and the clinician performed more effective cleaning,obturation,and therapy.Finally,the tooth was restored using composite resin,and the patient was satisfied with the result.CONCLUSION CBCT and a complete review of the literature may be beneficial for investigating the root canal system to achieve a biological and functional therapeutic effect.
文摘Aim: the aim of this study was to investigate the shaping ability of thermomechanically treated files manufactured by twisting(Twisted files)and compare it to conventional rotary system (K3, Sybron Endo, Orange, CA) in S-shaped canals, including formation of ledges, zipping, elbow, outer widening, danger zone, perforation and file deformation. Materials & Methods: Forty S-Shaped canals in resin blocks were randomly divided into 2 groups of 20 each. Pre-instrumentation images of the canals were taken via a digital camera and superimposed on images taken after preparation with TF and K3 systems to apical size of 25/06 and 30/06. Canal aberrations were measured from the superimposed image at five levels using AutoCAD system. Fisher exact test and Mann Whitney test were used for analysis of the data. Results: the incidence of zipping, elbow and apical transportation was significantly lower in the TF group (P = 0.04). Generally the incidence of aberration increased when the apical size increased to 30/0.06 regardless of the file system. Significant file deformation was evident in the TF after single use (P ? 0.001). Conclusion: Under the conditions of this study, TF manufactured by new technique performed better than K3 systems when used up to size 25/06 in simulated S-shaped canals. Clinical significance: The flexibility of thermomechanically treated files is beneficial in canals with multiple curvatures;however, attention should be paid to the instrument taper and final apical size of the preparation.
文摘Every year, a number of breach failures occur in Irrigation Canals in Sindh. Those failures cause displacement of thousands of people, destruction of properties, land, and damage to costly crops that worth millions Rupees. In addition to that, breach failures also can cause water shortages when the failure occurs during the peak demand period. There are various causes of embankment failures which include overtopping, internal erosion, structural defects and piping. State of art for breach failures is presented in this paper and suggestions for prediction of breaches in context to canals in Sindh are discussed. Seepage and slope stability analyses are recommended for a long-term breach predictions.
基金This research was funded by the Ministry of Higher Education Malaysia via the Fundamental Research Grant Scheme(FRGS/1/2020/WAB03/UPM/02/1)。
文摘Tropical peat comprises decomposed dead plant material and acts like a sponge to absorb water,making it fully saturated.However,drought periods dry it readily and increases its vulnerability to fire.Peat fires emit greenhouse gases and particles contributing to haze,and prevention by constructing fire-break canals to reduce fire spread into forest reserves is crucial.This paper aims to determine peat physical and chemical properties near a fire-break canal at different fire frequency areas.Peat sampling was conducted at two forest reserves in Malaysia which represent low fire frequency and high fire frequency areas.The results show that peat properties were not affected by the construction of a fire-break canal,however lignin and cellulose content increased significantly from the distance of the canal in both areas.The study concluded that fire frequency did not significantly influence peat properties except for porosity.The higher fibre content in the high frequency area did not influence moisture content nor the ability to regain moisture.Thus,fire frequency might contribute differently to changes in physical and chemical properties,hence management efforts to construct fire-break canals and restoration efforts should protect peatlands from further degradation.These findings will benefit future management and planning for forest reserves.
文摘BACKGROUND Primary intraspinal malignant melanoma is a very rare tumor that most often occurs in the cervical,thoracic,or thoracolumbar segment.CASE SUMMARY A rare case of primary thoracolumbar malignant melanoma is described.A 45-year-old female patient complained of low back pain with numbness and fatigue in both lower limbs.MR revealed an intradural space-occupying lesion at the thoracic 12 to lumbar 1 level.The tumor was partially excised,and a malignant melanoma was confirmed by histopathology.CONCLUSION Primary intraspinal malignant melanoma has rarely been reported,and surgical resection and related characteristics and diagnoses have been discussed.
文摘BACKGROUND We report a rare case of cervical spinal canal penetrating trauma and review the relevant literatures.CASE SUMMARY A 58-year-old male patient was admitted to the emergency department with a steel bar penetrating the neck,without signs of neurological deficit.Computed tomography(CT)demonstrated that the steel bar had penetrated the cervical spinal canal at the C6–7 level,causing C6 and C7 vertebral body fracture,C6 left lamina fracture,left facet joint fracture,and penetration of the cervical spinal cord.The steel bar was successfully removed through an open surgical procedure by a multidisciplinary team.During the surgery,we found that the cervical vertebra,cervical spinal canal and cervical spinal cord were all severely injured.Postoperative CT demonstrated severe penetration of the cervical spinal canal but the patient returned to a fully functional level without any neurological deficits.CONCLUSION Even with a serious cervical spinal canal penetrating trauma,the patient could resume normal work and life after appropriate treatment.
基金Innovation and Entrepreneurship Training Program for College Students.
文摘This study organized the current status of tangible cultural heritage along the Tonghui River.The spaces along the Tonghui River were classified according to the farmland,suburban areas,urban residential areas,and urban center areas.Spatial analysis of the current situation was conducted through Baidu Street View images,with a focus on evaluating the spatial environment around the tangible cultural heritage.Negative factors affecting the reuse of cultural heritage were analyzed,such as poor appearance of buildings and low accessibility of transportation along the Tonghui River.