Early-diverging Titanosauriform(Dinosauria,Sauropoda)Teeth from the Lower Cretaceous Yixian Formation of Southeastern Inner Mongolia,Northeast China

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.

Clinical efficacy,bone density,and follow-up in implant and orthodontic treatment for inclined adjacent teeth

BACKGROUND Tooth defects can cause elongation of occlusal teeth,leading to insufficient repair space.The combination of dental implant restoration and orthodontic treatment of oblique adjacent teeth has a significant therapeutic effect.AIM To explore clinical efficacy,bone density,and follow-up of implant and orthodontic treatment for patients with inclined adjacent teeth.METHODS In total,98 patients with oblique adjacent teeth were randomly assigned to implant restoration combined with orthodontic treatment(group A,n=49)or to receive implant restoration alone(group B,n=49).Changes in alveolar ridge bone density and apical bone density were observed before and after treatment in the two groups.Changes in chewing function and language function were compared between the two groups of patients.Follow-up lasted for 12 mo after repair to observe any adverse reactions in the oral cavity.RESULTS The clinical effective rates of group A and group B were 97.96%and 85.71%,respectively,with group A having a higher clinical effective rate than group B.After treatment,the bone density of the alveolar ridge and apical bone in both groups decreased compared to before treatment,while the chewing and language functions improved.The changes in various indicators in group A were more significant.After treatment,the satisfaction rate of group A(97.96%)was higher than that of group B(79.59%).The incidence of adverse reactions in group A(2.04%)was lower than that in group B(24.49%).CONCLUSION The amalgamation of implant restoration and orthodontic treatment for adjacent tilted teeth demonstrates notable clinical efficacy,diminishes alveolar bone resorption,and fosters patient functional rehabilitation while exhibiting negligible adverse reactions.

Evaluation of the Effectiveness and Safety of One-Time Endodontics in the Treatment of Chronic Apical Periodontitis with Sinus Tract in Pediatric Deciduous Teeth

Objective:To observe the effectiveness and safety of one-time endodontics in the treatment of chronic apical periodontitis with sinus tract in pediatric deciduous teeth.Methods:109 cases of children with chronic apical periodontitis with sinus tract in the deciduous teeth treated in our hospital from January 2022 to December 2023 were selected and grouped by the randomized numerical table method,with 54 cases in the experimental group and 55 cases in the control group.The experimental group was treated with one-time endodontics and the control group was treated with conventional endodontics.Results:After the treatment,the total effective rate of treatment was higher in the experimental group than in the control group(P<0.05);the incidence of adverse events was lower in the experimental group than in the control group(P<0.05);the satisfaction of the children's family members was higher in the experimental group than in the control group(P<0.05);the pain duration was lower in the experimental group than in the control group(P<0.05).Conclusion:In the experimental group,children with chronic apical periodontitis with sinus tract of the deciduous teeth were given one-time endodontic treatment,and the results of its implementation were relatively good.

渗透树脂联合美白技术修复微裂氟斑牙

背景:微研磨、家庭美白联合渗透树脂治疗氟斑牙具有良好的效果,但该方法对氟斑牙微裂纹的影响尚不清楚。目的:探究微研磨、家庭美白联合渗透树脂修复微裂氟斑牙的效果。方法:①临床研究:选择2020年7月至2021年3月就诊于天津医科大学口腔医院修复科的23例微裂氟斑牙患者,包括255颗微裂氟斑牙,均接受牙齿微研磨术、家庭美白与渗透树脂联合治疗,对比治疗前及治疗结束后1周、1个月的牙齿颜色、牙齿敏感程度和牙齿疼痛阈值。②体外实验:收集牙齿表面至少存在一条裂纹的氟斑牙60颗,随机分3组处理:对照组不进行任何处理,美白组进行微研磨与家庭美白处理,联合组进行微研磨、家庭美白和渗透树脂联合处理,每组20颗,测量处理后3组牙齿样本的显微硬度。结果与结论:①临床研究:治疗结束后6个月,255颗微裂氟斑牙中牙齿美白治疗显效207颗、有效48颗,总体治疗有效率为100%。随着治疗时间的延长,中、重度牙齿度敏感程度占比呈下降趋势,治疗结束后6个月,255颗氟斑牙中无重度敏感、15颗为中度敏感、125颗为轻度敏感、115颗无敏感,与治疗前的氟斑牙敏感程度相比差异有显著性意义(P<0.05)。治疗前与治疗结束后1周、6个月的牙齿疼痛阈值比较差异无显著性意义(P>0.05)。②体外实验:美白组牙齿显微硬度值低于对照组、联合组(P<0.05),对照组与联合组牙齿显微硬度值比较差异无显著性意义(P>0.05)。③结果表明,微研磨、家庭美白联合渗透树脂治疗微裂氟斑牙具有较好的疗效。

复合树脂与PMMA类树脂人工牙的粘接性能研究

目的:评估复合树脂与聚甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)类树脂牙之间的粘接效果。方法:共有320颗PMMA类树脂牙试件,经过研磨和清洗后,其中160颗试件表面进行了50μm Al 2O 3颗粒喷砂处理20 s。研磨和喷砂处理后的试件分别与PMMA类自凝树脂材料直接粘接作为对照组(A组),通过3种树脂粘接剂(Single Bond Universal、Clearfil SE ONE、Palfique Universal Bond)与复合树脂材料进行粘接,作为3个实验组(B、C、D组)。每组粘接试件分为两个亚组(n=20),分别经过0次和10000次冷热循环后,测量其剪切粘接强度。采用多因素方差分析及LSD-t检验对数据进行统计学处理。结果:喷砂处理能够显著增加所有实验组的初期粘接强度,但冷热循环后,其作用效果降低。冷热循环后,喷砂A组的粘接强度[(12.12±2.95)MPa]显著高于喷砂B、C、D组的,喷砂B组[(8.48±2.34)MPa]和喷砂D组[(8.90±2.51)MPa],均显著高于喷砂C组[(4.64±2.09)MPa]。结论:PMMA类树脂牙表面喷砂处理后,通过合适的树脂粘接剂能够与复合树脂产生符合ISO 10477:2020要求的粘接性能。

青少年恒牙牙体缺损的修复难点及过渡修复的方式选择

根据世界卫生组织界定,青少年所涵盖的年龄是10~19岁[1]。青少年时期是人类生命发展的一个独特阶段,是生理和心理发生迅猛成长的关键时期。当前,世界上青少年的数量总计高达12亿,占全球总人口的六分之一[1],因此,青少年的口腔健康受到了愈发广泛的关注。青少年口腔情况复杂,且处于发育阶段。恒牙作为继乳牙脱落后的第二副牙列,一般在牙根形成2/3左右时开始萌出,但此时恒牙牙根尚未发育完成,这些虽已萌出,但未达到[牙合]平面的恒牙被称为年轻恒牙[2]。根尖部完全形成后的被动萌出导致恒牙在整个青少年时期持续存在临床冠长度的增加[3]。故而,青少年恒牙包括牙根未发育完成的年轻恒牙与牙根发育完成但龈缘位置仍未稳定的恒牙。

Decline and fall of aging astrocytes:the human perspective

“Last scene of all that ends this strange,eventful history,is second childishness and mere oblivion.I am sans teeth,sans eyes,sans taste,sans everything.”William Shakespeare‘As You Like It'Act 2,Sc.7,l.139Aging of the human brain is characterized by a progressive decline of its functional capacity;this decline however varies widely,and cognitive longevity differs substantially between individuals.

三维有限元法应用于乳牙牙体修复的研究进展

三维有限元法是一种数值类、工程领域的创新型分析方法。其原理为运用现代计算机技术对物体的力学性能进行数值转换,建立直观、省时并能得出确切结论的研究模型,分析不同部位的应力应变情况,进而展开力学理论研究。迄今有限元法已广泛应用于工程技术、材料力学、生物力学领域,且应用范围已涉及口腔医学的各个领域。在口腔医学的力学研究方面极具优势,为深入探讨牙体修复治疗提供生物力学依据。近年来,在儿童口腔医学领域应用三维有限元法的力学研究成为热点。本文就三维有限元法用于乳牙牙体修复的应用现况及研究前景作一综述。

振动作用下高效铣刀瞬时切削位姿偏置特性

受铣削振动影响,铣刀及刀齿瞬时切削位姿复杂多变,导致铣刀与工件的瞬时接触关系不断改变,使得加工过渡表面形成过程具有多变性和不确定性。利用振动作用下的铣刀及刀齿瞬时切削位姿解算模型,揭示铣刀瞬时切削位姿偏置对加工过渡表面形成过程的影响特性;基于切削刃瞬时切削位姿与加工过渡表面的映射关系,利用表面形貌检测结果,获取铣刀瞬时位置偏置与角度偏置的变化特性;提出铣刀瞬时切削位姿偏置特性识别方法,利用铣刀瞬时切削位姿偏置的响应分析和表面形貌解算进行试验验证。结果表明,采用上述模型与方法,可有效识别出振动作用下铣刀瞬时切削位姿的偏置特性。

乳牙融合牙及其继承恒牙的临床研究

目的应用全口牙位曲面体层片技术研究乳牙融合牙的特点及其继承恒牙的表现类型。方法收集2023年1月—2024年7月苏州口腔医院影像数据库中3~6岁乳牙列期儿童的全口牙位曲面体层片,共纳入14404张,观察记录乳牙融合牙的发生情况,同时记录其继承恒牙的表现类型。应用SPSS 24.0统计软件分析所得的数据。结果乳牙融合牙的发生率为3.06%(441/14404),好发牙位从高到低的顺序为:下颌乳侧切牙和乳尖牙融合(58.18%)>下颌乳中切牙和侧切牙融合(30.91%)>上颌乳中切牙和侧切牙融合(8.89%)>乳切牙和多生牙融合(2.02%)。乳牙融合牙发生于男孩226例,女孩215例,性别间差异无统计学意义(P>0.05)。患者发生1对乳牙融合牙有387例,2对乳牙融合牙有54例。乳牙融合牙发生于右侧有287对,左侧有208对,两者差异有统计学意义(P<0.01)。患者发生下颌乳牙融合牙有443对,上颌有54对,两者差异有统计学意义(P<0.01)。患者发生单侧乳牙融合牙有387例,双侧有54例,两者差异有统计学意义(P<0.01)。乳牙融合牙其继承恒牙有3种表现类型:1)继承恒牙缺失占49.49%(245/495);2)继承恒牙不缺失占46.67%(231/495);3)继承恒牙融合牙占3.84%(19/495)。结论乳牙融合牙发生率为3.06%,好发于下前牙区,无性别差异,融合牙1对多发,右侧多于左侧,下颌多于上颌,单侧多于双侧,乳牙融合牙对继承恒牙有一定影响,儿童口腔医生应重视并密切追踪观察恒牙列是否存在异常,早期发现预防乳牙融合牙产生的危害。

夹层砂岩中斧形齿的破岩优势分析

在中国众多的油气藏中都存在大量的夹层砂岩,且层间构成复杂,使用普通平面齿PDC钻头破碎夹层砂岩时,很容易产生各种不良工况,如弹跳、回转等,给破岩带来了极大困扰。为此,采用一种特殊的PDC斧形齿钻头,并通过ABAQUS有限元仿真分析方法对比斧形齿与平面齿在夹层砂岩中的破岩效果。结果表明:斧形齿特殊的三维结构在破岩时使剪切应力更加集中,并使其在嵌入岩石时产生更大的破坏力,更容易切入岩石,破岩能力显著提升。

正畸牵引时机对上颌埋伏阻生尖牙牙根影响的临床研究

目的:探讨上颌埋伏阻生尖牙最佳正畸牵引时机。方法:选取需行外科联合正畸牵引的20颗上颌埋伏阻生尖牙,分为牙根发育完全组和牙根未发育完全组。通过CBCT及临床检查测量记录牵引前、后两组埋伏牙牙根相关指标的变化,比较两组埋伏牙牵引到位后牙根的差异。结果:两组埋伏牙均能牵引到位。牙根未发育完全的埋伏牙牵引后的牙根长度长于牵引前的牙根长度,但短于对照牙,牵引过程中不会形成新的牙根弯曲。牙根发育完全的埋伏牙牵引后的牙根长度短于自身牵引前、牙根未发育完全组牵引后以及对照牙的牙根长度,且牵引时间长于牙根未发育完全的埋伏牙。两组埋伏牙根管壁厚度、牙髓活力均正常。结论:正畸牵引治疗中,牙根未发育完全的埋伏阻生尖牙具有牙周组织改建速度快,正畸牵引时间短、牙根吸收程度轻的优点,其总体疗效优于牙根发育完全的埋伏牙。

早期遗址化石ESR测年等效剂量拟合函数的选择

在动物牙齿化石样品电子自旋共振测年(Electron Spin Resonance Dating,ESR)中辐照剂量点拟合函数的选择对等效剂量D_(E)的确定至关重要。目前,早期遗址老化石(>1 Ma)的D_(E)拟合常采用双饱和指数(Double Saturation Exponential,DSE)函数,使用该函数时一般需要15个以上剂量点和大于20 kGy的最大辐照剂量(D_(max))才能保证D_(E)值的拟合精度。但在实际应用中存在部分老化石的样品量较少,且缺乏大剂量辐照的准确标定情况,导致无法满足上述DSE函数的适用条件。本研究对涵盖晚中新世至早更新世的化石样品进行了不同拟合函数的对比分析,着重探讨单饱和指数(Single Saturation Exponential,SSE)函数在老化石样品D_(E)拟合中的适用性。研究表明:对11~15个剂量点进行拟合时,对于2000 GyE<4500 Gy和D_(E)>4500 Gy的样品,分别在1.9×D_(E)max<3.5×D_(E)和D_(max)≥6.5×D_(E)条件下采用SSE函数拟合,可以获得与使用DSE函数基本一致的D_(E)结果。

微创拔牙术治疗下颌复杂阻生牙的疗效及安全性分析

目的评估微创拔牙术在处理下颌复杂阻生牙时的临床效果和安全性。方法选择2023年3月至2024年3月孟州复兴医院收治的90例下颌复杂阻生牙患者进行分析,根据随机分为对照组与观察组,各45例,对照组接受常规传统拔牙术,观察组接受微创拔牙术,就两组患者手术相关指标、治疗效果、术后疼痛及并发症风险进行组间比较。结果观察组患者手术用时、术中出血量、张口受限程度、面部肿胀及术后疼痛均低于对照组,差异有统计学意义(P<0.05);观察组治疗有效率(95.56%)高于对照组(82.22%),差异有统计学意义(P<0.05);观察组患者术后颞下颌关节脱位、干槽症发生率均低于对照组,差异有统计学意义(P<0.05),两组牙根折断、张口受限发生率比较,差异无统计学意义(P>0.05)。结论相对于传统拔牙术,微创拔牙术处理下颌复杂阻生牙可提升治疗效果,有效控制术后疼痛,减少并发症发生风险。

生物导向性牙体预备技术修复外伤前牙缺损2例报道及文献回顾

目的 探讨生物导向性预备技术(biologically oriented preparation technique,BOPT)在美学区外伤牙修复中的应用效果,为临床提供参考。方法 本研究获得患者知情同意。报道2例应用BOPT技术修复美学区外伤后牙体组织缺损达龈下的外伤牙病例。2例病例均因右上前牙外伤致缺损1个月余前来就诊。通过口内检查及美学分析发现。病例1,男,67岁。患者诉右上前牙一个月前因外伤致缺损露髓,于牙体牙髓科行根管治疗术,术后无不适,因影响咀嚼和美观,要求修复。口内检查:11残根,唇侧断端最深处呈V字型,位于龈下2 mm,近远中断端位于龈下1~2 mm,腭侧断端位于龈上2~3 mm,剩余牙体组织少,根管口可见充填物,近远中径小,牙根偏腭侧,叩(-),未见明显松动度,11近远中龈乳头缺如;21牙冠近中倾斜;厚龈生物型;牙石(+),探诊深度(probing depth,PD):2~4 mm;附着丧失(attachment loss,AL):1~2 mm;牙龈退缩(gingival recession,GR):0~1 mm;出血指数(bleeding index,BI):1~2,诊断:11残根;慢性牙周炎。病例2,男,34岁。患者诉右上前牙1个月前因外伤致缺损露髓,于牙体牙髓科行根管治疗术,术后无不适,因影响咀嚼和美观,要求修复。口内检查:12、13大面积缺损,唇侧壁缺损达龈下约1 mm,断端可见充填物,近远中断端位于龈上约2~4 mm,腭侧断端位于龈上约3~4 mm,叩(-),未见明显松动度,唇侧牙龈稍红肿;厚龈生物型;牙石(++~+++);PD:3~5 mm;AL:1~3 mm;GR:0~2mm;BI:2~3,诊断:12、13牙体缺损;慢性牙周炎。治疗方案:2例病例均拟进行牙周基础治疗后,应用BOPT技术,行垂直型牙体预备,通过临时修复体塑形软组织,选用高透单一氧化锆全瓷冠,结合计算机辅助设计/计算机辅助制造(computer aided design/computer aided manufacturing,CAD/CAM)技术精准复制临时修复体的穿龈轮廓,从而重建红白美学。结果 BOPT技术实现了美学区外伤牙牙体缺损的修复以及软组织塑形。病例1,治疗前腭侧倾斜的11实现了唇向牙龈塑形,与21达到协调一致。病例2,治疗前12、13形态不佳的龈缘得到了显著改善。通过应用BOPT技术。2例病例均形成了健康的软组织袖口,取得了良好的红白美学修复效果。术后1年随访结果显示:病例1中11,病例2中12、13牙龈边缘均稳定,红白美学效果维持良好。文献回顾结果表明:相较于水平型牙体预备,BOPT技术结合完整的数字化工作流程,可以更加微创地进行牙体组织预备,利用临时修复体重建基牙的釉牙骨质界轮廓,重塑软组织轮廓,增加软组织厚度,稳定牙龈边缘,但其长期修复效果,仍需临床随访观察。结论 BOPT技术在美学区的合理应用可以获得良好的美学修复效果,是针对美学区外伤牙有效的修复解决方案。

结构参数对篦齿封严流动特性与最佳封严齿数影响研究

为获得有限安装空间内最佳封严性能的篦齿结构,在固定封严长度下,建立不同封严间隙、齿高、齿数等结构参数的直通篦齿模型,通过数值方法分析不同进出口压比条件下,间隙等结构参数对泄漏特性与最佳封严齿数影响的敏感程度。结果表明,在固定封严长度下,换算流量随压比和封严间隙的增大而增大,随着齿数的增大呈现先减小后增大的趋势,齿高对泄漏特性影响较小。封严间隙对换算流量与最佳封严齿数的影响最大,当封严间隙为2 mm时,齿数为3时换算流量最小,当齿数增加到13时,换算流量增加了8.11%;当封严间隙为0.5 mm时,齿数为9时换算流量最小,但此时随着齿数的进一步增加,换算流量基本不变。拟合得到固定封严长度下篦齿封严最佳封严齿数经验关系式,拟合公式计算结果与数值模拟结果吻合较好,可用于篦齿的工程设计计算。

Influence of masticatory fatigue on the fracture resistance of the pulpless teeth restored with quartz-fiber post-core and crown

To investigate whether masticatory fatigue affects the fracture resistance and pattern of lower premolars restored with quartz-fiber post-core and full crown, 44 single rooted lower premolars recently extracted from orthodontic patients were divided into two groups of 22 each. The crowns of all teeth were removed and endodontically treated and then restored with quartz-fiber post-core and full crown. Twenty-two teeth in one group were selected randomly and circularly loaded at 45° to the long axis of the teeth of 127.4 N at a 6 Hz frequency, and the other group was not delivered to cyclic loading and considered as control. Subsequently, all teeth in two groups were continually loaded to fail at 45° to the long axis of the teeth at a crosshead speed of 1 mm.min-1. The mean destructive force values were （733.88±254.99） and （869.14±280.26） N for the experimental and the control group, respectively, and no statistically significant differences were found between two groups （P〉O.05）. Bevel fracture and horizontal fracture in the neck of root were the major fracture mode of the specimens. Under the circumstances of this study, it seems that cyclic loading does not affect the fracture strength and pattern of the quartz-fiber post-core-crown complex.

Transplantation of stem cells from human exfoliated deciduous teeth for bone regeneration in the dog mandibular defect

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.

Effect of restoration technique on resistance to fracture of endodontically treated anterior teeth with flared root canals

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.

新型定子永磁游标电机的设计与分析

提出了一种在定子结构上的新型外转子永磁游标电机拓扑结构,在电机定子上引入了有对磁场调制作用的调制齿,通过对调制齿进行设计改动,实现了对磁场的充分利用,使得电机具备较低的齿槽转矩和稳定的电磁转矩。详细阐述了新型定子外转子永磁游标电机的工作原理,提供了具体的二维结构示意图以及设计参数,针对其电磁性能、气隙磁密、空载反电动势和谐波分布进行了分析说明。研究结果说明,这种新型定子外转子永磁游标电机具有有效的谐波调制作用,同时齿槽转矩有明显的降低,并能实现较平稳转矩输出。