Three eusauropod teeth(SDUST-V1064,PMOL-AD00176,PMOL-ADt0005)are reported from the Lower Cretaceous Yixian Formation of Ningcheng,southeastern Inner Mongolia,China.Two of them(SDUST-V1064,PMOL-AD00176)are assigned to ...Three eusauropod teeth(SDUST-V1064,PMOL-AD00176,PMOL-ADt0005)are reported from the Lower Cretaceous Yixian Formation of Ningcheng,southeastern Inner Mongolia,China.Two of them(SDUST-V1064,PMOL-AD00176)are assigned to early-diverging titanosauriforms in having slightly mesiodistal expansion at the base of the tooth crown,a slenderness index value>2.0 and<4.0,and D-shaped cross section.Furthermore,SDUST-V1064 and PMOL-AD00176 are referred as an Euhelopus-like titanosauriform on the basis of having a sub-circular boss on the lingual surface and an asymmetrical crown-root margin which slants apically,respectively.CT scan data of SDUST-V1064 reveals new dental information of early-diverging titanosauriforms,for example,the enamel on the labial side thicker than that on the lingual side,an enamel/dentine ratio of 0.26 and a boss present on the lingual side of the dentine of the crown.展开更多
The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed...The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed from two aspects of reaction tooth arrangement and reaction tooth conical angle,and three groups of experimental models are optimized and designed.The model construction and numerical analysis of the shear wave vibroseis vibrator plate are carried out with ANSYS software.The motion law between the vibration plate and the earth at work was studied,the strain energy of the three experimental models in operation,the maximum displacement of particle at the same position and other reference indices were compared and ana-lyzed,with 28 conical reaction teeth were arranged on both sides.The coupling effect between the vibration plate and the earth was best when the tooth angle was 60°.Compared with the toothless vibration plate,the energy efficiency is improved by about 20%,and the coupling effect between the vibrator plate and the earth is effectively enhanced.It is found that the coupling effect is enhanced through increasing the number of reac-tion teeth of the vibration plate by increasing the coupling area between the vibration plate and the earth.展开更多
Objective:To explore the cure rate of bracketless invisible headgear orthodontic for opening deep occlusion of anterior teeth.Methods:10 cases with deep occlusion of anterior teeth were selected.All of the patients we...Objective:To explore the cure rate of bracketless invisible headgear orthodontic for opening deep occlusion of anterior teeth.Methods:10 cases with deep occlusion of anterior teeth were selected.All of the patients were admitted to our hospital from January 2017 to January 2020.All selected patients received bracketless invisible headgear orthodontic treatment.We took CBCT(cone beam CT)before and after orthodontics lateral cranial radiographs and curved tomographic radiographs to analyze the effect of orthodontic treatment in 10 patients.Results:The changes of 10 patients before and after the orthodontic treatment were not significant in Ul-SN,U6-SN,MP-FH(P>0.05);the Ul-PP of the patients all decreased by 3〜5mm.Compared with the effect before orthodontic treatment,the difference is significance(P<0.05);The tooth loosening didn't occur obviously in 10 patients.And 2 patients(20.00%)had mild root resorption in the anterior teeth.Conclusion:The effect of invisible headgear orthodontic treatment without brackets is significant in orthodontic treatment of patients with deep occlusion of anterior teeth.The pressure of the upper anterior teeth can reach as low as 3~5mm.The cure rate of deep occlusion of open anterior teeth is high.The orthodontic method is comfortable,with beautiful appearance,which is easier to be accepted by patients.展开更多
AIM: To investigate the effect of stem cells from human exfoliated deciduous teeth(SHED) transplanted for bone regeneration in the dog mandibular defect.METHODS: In this prospective comparative study, SHEDs had been i...AIM: To investigate the effect of stem cells from human exfoliated deciduous teeth(SHED) transplanted for bone regeneration in the dog mandibular defect.METHODS: In this prospective comparative study, SHEDs had been isolated 5 years ago from human exfoliated deciduous teeth. The undifferentiated stem cells were seeded into mandibular bone through-andthrough defects of 4 dogs. Similar defects in control group were filled with cell-free collagen scaffold. After 12 wk, biopsies were taken and morphometric analysis was performed. The percentage of new bone formation and foreign body reaction were measured in each case. The data were subject to statistical analysis using the Mann-Whitney U and Kruskalwalis statistical tests. Differences at P < 0.05 was considered as significant level.RESULTS: There were no significant differences between control and SHED-seeded groups in connective tissue(P = 0.248), woven bone(P = 0.248) and compact bone(P = 0.082). There were not any side effects in transplanted SHED group such as teratoma or malignancy and abnormalities in this period.CONCLUSION: SHEDs which had been isolated and characterized 5 years ago and stored with cryopreservation banking were capable of proliferation and osteogenesis after 5 years, and no immune response was observed after three months of seeded SHEDs.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
We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to be...We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.展开更多
Theoretical and the experimental researches executed in Uzbekistan and abroad explored some ways of a substantiation of a rational profile of a tooth of a saw and its fibre capturing ability. Despite that, untill now,...Theoretical and the experimental researches executed in Uzbekistan and abroad explored some ways of a substantiation of a rational profile of a tooth of a saw and its fibre capturing ability. Despite that, untill now, optimum parameters of a saw gin which provides high quality ginning without harming the quality of cotton fibre have not been found. Considering the stated above in the given job the influence of the changed form of saw teeth on fibre-capturing area is examined. The analytical formulas for the additional area promoting to double the fibre capture quantity by saw teeth are received.展开更多
BACKGROUND Autoimmune hepatitis is a serious autoimmune liver disease that threatens human health worldwide,which emphasizes the urgent need to identify novel treatments.Stem cells from human exfoliated deciduous teet...BACKGROUND Autoimmune hepatitis is a serious autoimmune liver disease that threatens human health worldwide,which emphasizes the urgent need to identify novel treatments.Stem cells from human exfoliated deciduous teeth(SHED),which are easy to obtain in a non-invasive manner,show pronounced proliferative and immunomodulatory capacities.AIM To investigate the protective effects of SHED on concanavalin A(ConA)-induced hepatitis in mice,and to elucidate the associated regulatory mechanisms.METHODS We used a ConA-induced acute hepatitis mouse model and an in vitro co-culture system to study the protective effects of SHED on ConA-induced autoimmune hepatitis,as well as the associated underlying mechanisms.RESULTS SHED infusion could prevent aberrant histopathological liver architecture caused by ConA-induced infiltration of CD3+,CD4+,tumor necrosis-alpha+,and interferon-gamma+inflammatory cells.Alanine aminotransferase and aspartate aminotransferase were significantly elevated in hepatitis mice.SHED infusion could therefore block ConA-induced alanine aminotransferase and aspartate aminotransferase elevations.Mechanistically,ConA upregulated tumor necrosisalpha and interferon-gamma expression,which was activated by the nuclear factor-kappa B pathway to induce hepatocyte apoptosis,resulting in acute liver injury.SHED administration protected hepatocytes from ConA-induced apoptosis.CONCLUSION SHED alleviates ConA-induced acute liver injury via inhibition of hepatocyte apoptosis mediated by the nuclear factor-kappa B pathway.Our findings could provide a potential treatment strategy for hepatitis.展开更多
BACKGROUND An extra tooth in the normal tooth sequence in any region of the dental arch is regarded as a supernumerary tooth(SNT).Due to the large variation in location and morphology,the extraction of impacted SNTs i...BACKGROUND An extra tooth in the normal tooth sequence in any region of the dental arch is regarded as a supernumerary tooth(SNT).Due to the large variation in location and morphology,the extraction of impacted SNTs is an extensive and complex procedure with high risks of several complications.This report presents a rare case of seven impacted SNTs in the bilateral upper and lower arch that were successfully extracted with the use of digital positioning guide plates.CASE SUMMARY In January 2022,a 21-year-old male was referred to our department with a chief complaint of pain in relation to tooth#36.Clinical examination showed a deep carious lesion with pulpal involvement in tooth#36 and lingual swelling of the bilateral mandibular posterior area.Radiographic examination revealed seven deeply impacted SNTs in the bilateral posterior area and bilateral impacted mandibular third molars.Based on these findings,the patient was diagnosed with bilateral,multiple impacted SNTs and tooth#36 chronic pulpitis.A root canal treatment and an all-ceramic crown restoration for tooth#36 were performed.An individualized digital positioning guide plate was designed by computer-aided design/computer-aided manufacturing technology and cone-beam computed tomography for extraction of the impacted SNTs.During the operation,the digital positioning guide plate allowed rapid positioning and exposure of the SNTs while avoiding adjacent important anatomical structures.At 3-month follow-up,regeneration of bone and soft tissues was visible.CONCLUSION The application of digital positioning guide plates is useful for the individualized and minimalized extraction of impacted supernumerary teeth.展开更多
BACKGROUND Dental fluorosis is caused by excessive fluoride ingestion during tooth formation.As a consequence,there is a higher porosity on the enamel surface,which causes an opaque look.AIM The aim of this study was ...BACKGROUND Dental fluorosis is caused by excessive fluoride ingestion during tooth formation.As a consequence,there is a higher porosity on the enamel surface,which causes an opaque look.AIM The aim of this study was to identify a dental intervention to improve the smile in patients with tooth fluorosis.Additional aims were to relate the stain size on fluorotic teeth with the effectiveness of stain removal,enamel loss and procedure time using a manual microabrasion technique with 16%hydrochloric acid(HCL).METHODS An experimental study was carried out on 84 fluorotic teeth in 57 adolescent patients,33 females and 24 males,with moderate to severe fluorosis.The means,standard deviations and percentages were analyzed using nonparametric statistics and ArchiCAD 15 software was used for the variables including stain size and effectiveness of stain removal.RESULTS The average enamel loss was 234μm and was significantly related to the procedure time categorized as 1-4 min and 4.01-6 min,resulting in a P>0.000.The microabrasion technique using 16%HCL was effective in 90.6%of patients and was applied manually on superficial stains in moderate and severe fluorosis.Procedure time was less than 6 min and enamel loss was within the acceptable range.CONCLUSION Microabrasion is a first-line treatment;however,the clinician should measure the average enamel loss to ensure that it is within the approximate range of 250μm in order to avoid restorative treatment.展开更多
BACKGROUND Vertical root fracture(VRF)is one of the most common reasons for tooth extraction,although various methods have been applied for saving teeth with VRF.CASE SUMMARY This case report describes a woman who had...BACKGROUND Vertical root fracture(VRF)is one of the most common reasons for tooth extraction,although various methods have been applied for saving teeth with VRF.CASE SUMMARY This case report describes a woman who had a sinus tract on the labial gingiva of the left maxillary central incisor for past two months.Periodontal probing revealed an 8–10 mm deep,narrow,isolated pocket on the palatal side of the tooth.Clinical and radiographic examination confirmed a longitudinal root fracture.A new approach using a combination of resin and iRoot BP Plus through intentional replantation was used for the treatment of the tooth.At one-year follow-up,the tooth remained asymptomatic with normal periodontal probing depth,and radiographic images showed almost normal bone and periodontal structures around the root.CONCLUSION This new approach may be developed as an effective method for saving teeth with VRF.展开更多
In this paper,a new auxiliary teeth structure is proposed for fault-tolerant permanent magnet(PM)generators,which can reduce the short-circuit currents.Firstly,the short-circuit current and the phase to phase isolatio...In this paper,a new auxiliary teeth structure is proposed for fault-tolerant permanent magnet(PM)generators,which can reduce the short-circuit currents.Firstly,the short-circuit current and the phase to phase isolation of the fault-tolerant generator are analyzed briefly.Secondly,the auxiliary teeth structure is optimized to improve fault-tolerant capability.Then,the PM generators with different stator structures are compared to evaluate the proposed auxiliary teeth structure.Four critical generator parameters are investigated,i.e.back-electromotive forces,short-circuit currents,stator magneto motive force(MMF)harmonics,and torque performances.The results show that the proposed structure has better fault-tolerant capability than the conventional two-layer windings.Moreover,the stator MMF harmonics can be suppressed.Furthermore,the cogging torque and torque ripple can be suppressed by adopting the proposed structure.Finally,the simulated results are given to validate the theoretical analysis.展开更多
Background: Many oral bacterial species forming the normal flora present as a biofilm in the oral cavity. Dental caries results when there is an imbalance of pathogenic bacteria within these biofilms. Aim: This study ...Background: Many oral bacterial species forming the normal flora present as a biofilm in the oral cavity. Dental caries results when there is an imbalance of pathogenic bacteria within these biofilms. Aim: This study sought to isolate and identify the bacterial species associated with extracted carious teeth and their susceptibility pattern towards commonly employed antimicrobial agents used at the Komfo Anokye Teaching Hospital (KATH). Methodology: A descriptive cross-sectional study carried out on thirty-three extracted carious teeth samples collected by convenient sampling from patients attending the Oral Health Directorate-KATH. All samples were collected from the 11th of March 2019 to the 6th of April 2019. Data was collected using 5 ml peptone water and a case study form. Analysis was done using SPSS version 25 and Microsoft Excel version 10. Results: Twenty (61%) samples were obtained from female patients and thirteen samples (39%) from male patients. Streptococcus spp had the highest occurrence (32.25%) with the least isolated being Pseudomonas and E. coli spp (6.45%). Antibiotic susceptibility test revealed Pseudomonas spp was resistant to all the eight antibiotics used in this study. All bacterial isolates were resistant to Cefuroxime and penicillin except Staphylococcus and Streptococcus spp. Conclusion: The commonest isolates associated with dental caries in KATH were Streptococcus, Bacillus and Staphylococcus spp. In this study most of the isolated species were resistant to common antibiotics employed in the Oral Health Directorate in KATH (amoxicillin/clavulanic, ampicillin and penicillin). From the current study the most effective antibiotic observed was meropenem (23%) with penicillin (3%) being least effective in treating infections of caries.展开更多
A method to solve the elastic conjugate surfaces in multi-teeth meshing is presented. In mechanicalmanufacturing and design, there exist a lot of problems relating to conjugate surfaces, such as three-dimensionalengag...A method to solve the elastic conjugate surfaces in multi-teeth meshing is presented. In mechanicalmanufacturing and design, there exist a lot of problems relating to conjugate surfaces, such as three-dimensionalengagement, steel rolling and workpiece machining, which cause great effects on the quality of machining andperformances of transmission. This method describes relation between conjugate motion and elastic deformation in theprocess of mesh-in and mesh-out, and can be used to determine the profile of gear tooth by a certain given load sharing.展开更多
<strong>Objective:</strong> To compare the congenital tooth deficiencies seen in permanent dentition in individuals with unilateral cleft lip and palate (UCLP) to non-cleft individuals with Angle Class I m...<strong>Objective:</strong> To compare the congenital tooth deficiencies seen in permanent dentition in individuals with unilateral cleft lip and palate (UCLP) to non-cleft individuals with Angle Class I malocclusion. <strong>Method:</strong> The study was performed on orthopantomograph films of 50 individuals with UCLP aged between 12 - 16 years and 50 individuals with Angle Class I malocclusion individuals aged between 13 - 15 years. Individuals with UCLP;32 clefts were on the left side and 18 clefts were on the right side. Permanent third molar teeth deficiency was excluded from the study. <strong>Results: </strong>In 50 individuals with UCLP;35 (70%) upper lateral incisors were congenitally deficient in the cleft area, while 15 (30%) missing lateral teeth were found in the non-cleft side. In control group, 12 (24%) of 50 patients had congenital lateral incisor deficiency. Congenital deficiency of upper lateral incisor in UCLP;the cleft area was higher than the non-cleft side (p < 0.01). The difference was statistically important when compared with the control group (p < 0.001). In 50 individuals with UCLP;while 27 (54%) of second premolar teeth were congenitally deficient in cleft side, 23 (46%) were missing in non-cleft side. In control group, 18 (36%) congenital second premolar deficiency was detected. However, second premolar congenital deficiency was higher in UCLP group when compared to control group (p < 0.01). <strong>Conclusion:</strong> The deficiency of the lateral incisors in the cleft side is more often congenitally deficient than upper second premolar teeth and this should be considered in the treatment planning from an early age.展开更多
By means of finite element analysis methods calculated the stress, strainand displacement of the belt teeth and analysisied the factors such as load distribution,specific property coefficient of material and temperatu...By means of finite element analysis methods calculated the stress, strainand displacement of the belt teeth and analysisied the factors such as load distribution,specific property coefficient of material and temperature variation, which influence the fatigue strength of the belt teeth..展开更多
Adult pharyngeal teeth in Mylopharyngodon piceus are molariform. Based on SEM observations ofthe developing teeth, this paper describes the morphological diversification of pharyngeal teeth in M.piceus. The larval and...Adult pharyngeal teeth in Mylopharyngodon piceus are molariform. Based on SEM observations ofthe developing teeth, this paper describes the morphological diversification of pharyngeal teeth in M.piceus. The larval and juvenile teeth are changed from conical to adult molariform teeth through sevenstages. Comparisons are made between each stage and corresponding types in some species of differentsubfamilies in Cyprinidae. It is considered that the ontogenetic resemblances of the pharyngeal teehbear relationship to the phylogeny of cyprinids.展开更多
In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a ...In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a magnitude of 100 grams and a moment of 550 g·mm in a du-ration of 3 to 56 days.Then sections were prepared for histological examination.The findings re-vealed that,due to tooth rotation,neighboring teeth were drifted and rotated(82%),and therewere disarrangement and hyalinization of the periodontal ligament(88%),remodeling of the pe-riodontium(86%)and root resorption(32%)were also observed.These results demonstratethat tooth rotation may exert marked effects on neighboring teeth and periodontal tissues,whichmay be of important clinical significance.展开更多
基金supported by the Scientific Research Foundation of Shenyang Normal University(Grant No.BS202207)Program for Innovative Research Team of Excellent Talents in University of Shandong Province(Grant No.2019KJH004)+3 种基金Taishan Scholar Program of Shandong Province(Grant No.tsqn201812070)Educational Department of Liaoning Province(Grant No.JYTQN2023422)Shandong Provincial Natural Science Foundation(Grant No.ZR2017MD031)the National Natural Science Foundation of China(Grant Nos.41972025,41688103,42161134003).
文摘Three eusauropod teeth(SDUST-V1064,PMOL-AD00176,PMOL-ADt0005)are reported from the Lower Cretaceous Yixian Formation of Ningcheng,southeastern Inner Mongolia,China.Two of them(SDUST-V1064,PMOL-AD00176)are assigned to early-diverging titanosauriforms in having slightly mesiodistal expansion at the base of the tooth crown,a slenderness index value>2.0 and<4.0,and D-shaped cross section.Furthermore,SDUST-V1064 and PMOL-AD00176 are referred as an Euhelopus-like titanosauriform on the basis of having a sub-circular boss on the lingual surface and an asymmetrical crown-root margin which slants apically,respectively.CT scan data of SDUST-V1064 reveals new dental information of early-diverging titanosauriforms,for example,the enamel on the labial side thicker than that on the lingual side,an enamel/dentine ratio of 0.26 and a boss present on the lingual side of the dentine of the crown.
基金Supported by National Key Research and Development Program(No.20220101172JC).
文摘The vibrator plate is the link between the vibroseis vehicle and the earth,as well as the core com-ponent of the vibrator vehicle.In this paper,the coupling effect between the vibrator plate and the earth is an-alyzed from two aspects of reaction tooth arrangement and reaction tooth conical angle,and three groups of experimental models are optimized and designed.The model construction and numerical analysis of the shear wave vibroseis vibrator plate are carried out with ANSYS software.The motion law between the vibration plate and the earth at work was studied,the strain energy of the three experimental models in operation,the maximum displacement of particle at the same position and other reference indices were compared and ana-lyzed,with 28 conical reaction teeth were arranged on both sides.The coupling effect between the vibration plate and the earth was best when the tooth angle was 60°.Compared with the toothless vibration plate,the energy efficiency is improved by about 20%,and the coupling effect between the vibrator plate and the earth is effectively enhanced.It is found that the coupling effect is enhanced through increasing the number of reac-tion teeth of the vibration plate by increasing the coupling area between the vibration plate and the earth.
文摘Objective:To explore the cure rate of bracketless invisible headgear orthodontic for opening deep occlusion of anterior teeth.Methods:10 cases with deep occlusion of anterior teeth were selected.All of the patients were admitted to our hospital from January 2017 to January 2020.All selected patients received bracketless invisible headgear orthodontic treatment.We took CBCT(cone beam CT)before and after orthodontics lateral cranial radiographs and curved tomographic radiographs to analyze the effect of orthodontic treatment in 10 patients.Results:The changes of 10 patients before and after the orthodontic treatment were not significant in Ul-SN,U6-SN,MP-FH(P>0.05);the Ul-PP of the patients all decreased by 3〜5mm.Compared with the effect before orthodontic treatment,the difference is significance(P<0.05);The tooth loosening didn't occur obviously in 10 patients.And 2 patients(20.00%)had mild root resorption in the anterior teeth.Conclusion:The effect of invisible headgear orthodontic treatment without brackets is significant in orthodontic treatment of patients with deep occlusion of anterior teeth.The pressure of the upper anterior teeth can reach as low as 3~5mm.The cure rate of deep occlusion of open anterior teeth is high.The orthodontic method is comfortable,with beautiful appearance,which is easier to be accepted by patients.
文摘AIM: To investigate the effect of stem cells from human exfoliated deciduous teeth(SHED) transplanted for bone regeneration in the dog mandibular defect.METHODS: In this prospective comparative study, SHEDs had been isolated 5 years ago from human exfoliated deciduous teeth. The undifferentiated stem cells were seeded into mandibular bone through-andthrough defects of 4 dogs. Similar defects in control group were filled with cell-free collagen scaffold. After 12 wk, biopsies were taken and morphometric analysis was performed. The percentage of new bone formation and foreign body reaction were measured in each case. The data were subject to statistical analysis using the Mann-Whitney U and Kruskalwalis statistical tests. Differences at P < 0.05 was considered as significant level.RESULTS: There were no significant differences between control and SHED-seeded groups in connective tissue(P = 0.248), woven bone(P = 0.248) and compact bone(P = 0.082). There were not any side effects in transplanted SHED group such as teratoma or malignancy and abnormalities in this period.CONCLUSION: SHEDs which had been isolated and characterized 5 years ago and stored with cryopreservation banking were capable of proliferation and osteogenesis after 5 years, and no immune response was observed after three months of seeded SHEDs.
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We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.
文摘Theoretical and the experimental researches executed in Uzbekistan and abroad explored some ways of a substantiation of a rational profile of a tooth of a saw and its fibre capturing ability. Despite that, untill now, optimum parameters of a saw gin which provides high quality ginning without harming the quality of cotton fibre have not been found. Considering the stated above in the given job the influence of the changed form of saw teeth on fibre-capturing area is examined. The analytical formulas for the additional area promoting to double the fibre capture quantity by saw teeth are received.
基金Supported by The National Natural Science Foundation of China,No.81970940 and No.81600865Beijing Natural Science Foundation,No.7182182and the National Science and Technology Major Project of the Ministry of Science and Technology of China,No.2018ZX10302207.
文摘BACKGROUND Autoimmune hepatitis is a serious autoimmune liver disease that threatens human health worldwide,which emphasizes the urgent need to identify novel treatments.Stem cells from human exfoliated deciduous teeth(SHED),which are easy to obtain in a non-invasive manner,show pronounced proliferative and immunomodulatory capacities.AIM To investigate the protective effects of SHED on concanavalin A(ConA)-induced hepatitis in mice,and to elucidate the associated regulatory mechanisms.METHODS We used a ConA-induced acute hepatitis mouse model and an in vitro co-culture system to study the protective effects of SHED on ConA-induced autoimmune hepatitis,as well as the associated underlying mechanisms.RESULTS SHED infusion could prevent aberrant histopathological liver architecture caused by ConA-induced infiltration of CD3+,CD4+,tumor necrosis-alpha+,and interferon-gamma+inflammatory cells.Alanine aminotransferase and aspartate aminotransferase were significantly elevated in hepatitis mice.SHED infusion could therefore block ConA-induced alanine aminotransferase and aspartate aminotransferase elevations.Mechanistically,ConA upregulated tumor necrosisalpha and interferon-gamma expression,which was activated by the nuclear factor-kappa B pathway to induce hepatocyte apoptosis,resulting in acute liver injury.SHED administration protected hepatocytes from ConA-induced apoptosis.CONCLUSION SHED alleviates ConA-induced acute liver injury via inhibition of hepatocyte apoptosis mediated by the nuclear factor-kappa B pathway.Our findings could provide a potential treatment strategy for hepatitis.
基金Supported by National Natural Science Foundation of China,No.81970972Applied Basic Research Projects of the 920th Hospital of Joint Logistics Support Force,No.2020YGB06。
文摘BACKGROUND An extra tooth in the normal tooth sequence in any region of the dental arch is regarded as a supernumerary tooth(SNT).Due to the large variation in location and morphology,the extraction of impacted SNTs is an extensive and complex procedure with high risks of several complications.This report presents a rare case of seven impacted SNTs in the bilateral upper and lower arch that were successfully extracted with the use of digital positioning guide plates.CASE SUMMARY In January 2022,a 21-year-old male was referred to our department with a chief complaint of pain in relation to tooth#36.Clinical examination showed a deep carious lesion with pulpal involvement in tooth#36 and lingual swelling of the bilateral mandibular posterior area.Radiographic examination revealed seven deeply impacted SNTs in the bilateral posterior area and bilateral impacted mandibular third molars.Based on these findings,the patient was diagnosed with bilateral,multiple impacted SNTs and tooth#36 chronic pulpitis.A root canal treatment and an all-ceramic crown restoration for tooth#36 were performed.An individualized digital positioning guide plate was designed by computer-aided design/computer-aided manufacturing technology and cone-beam computed tomography for extraction of the impacted SNTs.During the operation,the digital positioning guide plate allowed rapid positioning and exposure of the SNTs while avoiding adjacent important anatomical structures.At 3-month follow-up,regeneration of bone and soft tissues was visible.CONCLUSION The application of digital positioning guide plates is useful for the individualized and minimalized extraction of impacted supernumerary teeth.
文摘BACKGROUND Dental fluorosis is caused by excessive fluoride ingestion during tooth formation.As a consequence,there is a higher porosity on the enamel surface,which causes an opaque look.AIM The aim of this study was to identify a dental intervention to improve the smile in patients with tooth fluorosis.Additional aims were to relate the stain size on fluorotic teeth with the effectiveness of stain removal,enamel loss and procedure time using a manual microabrasion technique with 16%hydrochloric acid(HCL).METHODS An experimental study was carried out on 84 fluorotic teeth in 57 adolescent patients,33 females and 24 males,with moderate to severe fluorosis.The means,standard deviations and percentages were analyzed using nonparametric statistics and ArchiCAD 15 software was used for the variables including stain size and effectiveness of stain removal.RESULTS The average enamel loss was 234μm and was significantly related to the procedure time categorized as 1-4 min and 4.01-6 min,resulting in a P>0.000.The microabrasion technique using 16%HCL was effective in 90.6%of patients and was applied manually on superficial stains in moderate and severe fluorosis.Procedure time was less than 6 min and enamel loss was within the acceptable range.CONCLUSION Microabrasion is a first-line treatment;however,the clinician should measure the average enamel loss to ensure that it is within the approximate range of 250μm in order to avoid restorative treatment.
文摘BACKGROUND Vertical root fracture(VRF)is one of the most common reasons for tooth extraction,although various methods have been applied for saving teeth with VRF.CASE SUMMARY This case report describes a woman who had a sinus tract on the labial gingiva of the left maxillary central incisor for past two months.Periodontal probing revealed an 8–10 mm deep,narrow,isolated pocket on the palatal side of the tooth.Clinical and radiographic examination confirmed a longitudinal root fracture.A new approach using a combination of resin and iRoot BP Plus through intentional replantation was used for the treatment of the tooth.At one-year follow-up,the tooth remained asymptomatic with normal periodontal probing depth,and radiographic images showed almost normal bone and periodontal structures around the root.CONCLUSION This new approach may be developed as an effective method for saving teeth with VRF.
基金supported by the Key Research and Development Program of Jiangsu Province(BE2018107)by the Natural Science Foundation of Jiangsu Province(BK20191225).
文摘In this paper,a new auxiliary teeth structure is proposed for fault-tolerant permanent magnet(PM)generators,which can reduce the short-circuit currents.Firstly,the short-circuit current and the phase to phase isolation of the fault-tolerant generator are analyzed briefly.Secondly,the auxiliary teeth structure is optimized to improve fault-tolerant capability.Then,the PM generators with different stator structures are compared to evaluate the proposed auxiliary teeth structure.Four critical generator parameters are investigated,i.e.back-electromotive forces,short-circuit currents,stator magneto motive force(MMF)harmonics,and torque performances.The results show that the proposed structure has better fault-tolerant capability than the conventional two-layer windings.Moreover,the stator MMF harmonics can be suppressed.Furthermore,the cogging torque and torque ripple can be suppressed by adopting the proposed structure.Finally,the simulated results are given to validate the theoretical analysis.
文摘Background: Many oral bacterial species forming the normal flora present as a biofilm in the oral cavity. Dental caries results when there is an imbalance of pathogenic bacteria within these biofilms. Aim: This study sought to isolate and identify the bacterial species associated with extracted carious teeth and their susceptibility pattern towards commonly employed antimicrobial agents used at the Komfo Anokye Teaching Hospital (KATH). Methodology: A descriptive cross-sectional study carried out on thirty-three extracted carious teeth samples collected by convenient sampling from patients attending the Oral Health Directorate-KATH. All samples were collected from the 11th of March 2019 to the 6th of April 2019. Data was collected using 5 ml peptone water and a case study form. Analysis was done using SPSS version 25 and Microsoft Excel version 10. Results: Twenty (61%) samples were obtained from female patients and thirteen samples (39%) from male patients. Streptococcus spp had the highest occurrence (32.25%) with the least isolated being Pseudomonas and E. coli spp (6.45%). Antibiotic susceptibility test revealed Pseudomonas spp was resistant to all the eight antibiotics used in this study. All bacterial isolates were resistant to Cefuroxime and penicillin except Staphylococcus and Streptococcus spp. Conclusion: The commonest isolates associated with dental caries in KATH were Streptococcus, Bacillus and Staphylococcus spp. In this study most of the isolated species were resistant to common antibiotics employed in the Oral Health Directorate in KATH (amoxicillin/clavulanic, ampicillin and penicillin). From the current study the most effective antibiotic observed was meropenem (23%) with penicillin (3%) being least effective in treating infections of caries.
基金This project is supported by National Key Project of China (No. PD9521903) , National Natural Science Foundation of China (No. 50075031) and National Key Laboratory of Mechanical Transmission of China.
文摘A method to solve the elastic conjugate surfaces in multi-teeth meshing is presented. In mechanicalmanufacturing and design, there exist a lot of problems relating to conjugate surfaces, such as three-dimensionalengagement, steel rolling and workpiece machining, which cause great effects on the quality of machining andperformances of transmission. This method describes relation between conjugate motion and elastic deformation in theprocess of mesh-in and mesh-out, and can be used to determine the profile of gear tooth by a certain given load sharing.
文摘<strong>Objective:</strong> To compare the congenital tooth deficiencies seen in permanent dentition in individuals with unilateral cleft lip and palate (UCLP) to non-cleft individuals with Angle Class I malocclusion. <strong>Method:</strong> The study was performed on orthopantomograph films of 50 individuals with UCLP aged between 12 - 16 years and 50 individuals with Angle Class I malocclusion individuals aged between 13 - 15 years. Individuals with UCLP;32 clefts were on the left side and 18 clefts were on the right side. Permanent third molar teeth deficiency was excluded from the study. <strong>Results: </strong>In 50 individuals with UCLP;35 (70%) upper lateral incisors were congenitally deficient in the cleft area, while 15 (30%) missing lateral teeth were found in the non-cleft side. In control group, 12 (24%) of 50 patients had congenital lateral incisor deficiency. Congenital deficiency of upper lateral incisor in UCLP;the cleft area was higher than the non-cleft side (p < 0.01). The difference was statistically important when compared with the control group (p < 0.001). In 50 individuals with UCLP;while 27 (54%) of second premolar teeth were congenitally deficient in cleft side, 23 (46%) were missing in non-cleft side. In control group, 18 (36%) congenital second premolar deficiency was detected. However, second premolar congenital deficiency was higher in UCLP group when compared to control group (p < 0.01). <strong>Conclusion:</strong> The deficiency of the lateral incisors in the cleft side is more often congenitally deficient than upper second premolar teeth and this should be considered in the treatment planning from an early age.
文摘By means of finite element analysis methods calculated the stress, strainand displacement of the belt teeth and analysisied the factors such as load distribution,specific property coefficient of material and temperature variation, which influence the fatigue strength of the belt teeth..
基金This project was funded by the interstional Cooperation of Japan-China and the National Natural Science foundation of China.
文摘Adult pharyngeal teeth in Mylopharyngodon piceus are molariform. Based on SEM observations ofthe developing teeth, this paper describes the morphological diversification of pharyngeal teeth in M.piceus. The larval and juvenile teeth are changed from conical to adult molariform teeth through sevenstages. Comparisons are made between each stage and corresponding types in some species of differentsubfamilies in Cyprinidae. It is considered that the ontogenetic resemblances of the pharyngeal teehbear relationship to the phylogeny of cyprinids.
文摘In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a magnitude of 100 grams and a moment of 550 g·mm in a du-ration of 3 to 56 days.Then sections were prepared for histological examination.The findings re-vealed that,due to tooth rotation,neighboring teeth were drifted and rotated(82%),and therewere disarrangement and hyalinization of the periodontal ligament(88%),remodeling of the pe-riodontium(86%)and root resorption(32%)were also observed.These results demonstratethat tooth rotation may exert marked effects on neighboring teeth and periodontal tissues,whichmay be of important clinical significance.
