Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys

This paper aims to investigate if the dental restoration of nickel-chromium based alloy(Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine.Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination.Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry.Compared to the control group,the urinary level of Ni was significantly higher in the patient group of < 1 month of the restoration duration,among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain.Urinary levels of Cr were significantly higher in the three patient groups of <1,1 to <3 and 3 to <6 months,especially in those with a higher metal crown exposure index.Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups.Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration.Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

Insightful Understanding of the Role of the Mechanical Properties in Defining the Reliability of All-Ceramic Dental Restorations: A Review

Since the last two decades, restorative dentistry has been witnessing an increased acceptance of the use of the well-known all-ceramic materials for the fabrication of single dental restorations, such as inlays, onlays, crowns, anterior and posterior fixed partial dentures (PFPDs). These restorations certainly offer the potential for better biocompatibility coupled with superior aesthetic qualities, especially when compared with the conventional prostheses made from porcelain that is fused with metal ceramic restorations. However, brittleness and extreme sensitivity of all-ceramic materials to micro-like defects or cracks that are inherently present, or may grow, in their microstructure during different laboratory fabrication steps, during necessary clinical adjustments, or from post-placement chewing activity, remain major shortcomings of these dental restorations. In fact, many researchers are of the opinion that the improved mechanical properties can significantly improve the lifetime of all-ceramic restorations and result in enhanced reliability. Therefore, efforts of researchers, as well as manufacturers, have been directed towards the improvement of the mechanical properties in order to overcome such limitations. This article reviews the characterization of the most important mechanical properties that can delineate the behavior of all-ceramic dental materials upon loading. These include fracture mechanics, the brittle nature of ceramics, the relationship between microstructural features and fracture behavior, sources of cracks and flaws that may initiate a fracture and the effect of different fabrication procedures and/or clinical adjustments on the mechanical behavior of dental ceramics are also reviewed and discussed.

Periodontal Health among Type 2 Diabetes Patients Treated with Different Dental Restorations

Background: Diabetes increases periodontal disease risk and its complications, which are worsened with age or faulty restorations. Aim: Evaluate periodontal health among patients with diabetes treated with different dental restorations. Materials and Methods: This comparative cross-sectional study was conducted at the faculty of dentistry, Najran University, KSA, from March 2018 to February 2020. It included 260 diabetics, treated with different dental restorations, divided into four groups, each comprising 65 patients aged 45 - 60 years: Group 1 (G1), no restorations (control group);Group 2 (G2), Class II amalgam restorations;Group 3 (G3), Class II composite resin restorations;and Group 4 (G4), three-unit posterior metal ceramic prostheses. The Ages of all restorations ranged from 8 to 10 years. All groups were assessed for the Plaque Index (PI) and Gingival Index (GI), Overhangs Rate (OR), Alveolar Bone Loss (ABL) (the latter two using panoramic X-ray). HbA1c and duration of participants were also assessed and compared. Results: The mean HbA1c results of the groups ranged from 8.1% to 9.5%, and their mean diabetes durations ranged from 7.2 to 12 years. All the groups showed worse periodontal scores, ranging from 2.45 - 2.95 for PI and 2.25 - 2.8 for GI. G2 had higher scores than G1 and G3 (p < 0.001). G4 had the highest two recorded scores (p < 0.001). G2 had a higher rate of overhangs than G3 (p < 0.037). The mean ABL was 44% (SD 6.4) for G1, 56.0% (SD 6.7) for G2, 46.5% (SD 5.8) for G3, and 74.5% (SD 6.4) for G4. The lowest values were recorded in G1 and G3 (p = 0.987). The highest value was observed in G4, which was significantly higher than other groups (p < 0.001). Conclusion: The worse periodontal parameters among subjects treated with either three-unit metal ceramic or Class II amalgam restorations indicated severe periodontal destruction. Untreated subjects and subjects treated with Class II composite resin had relatively better periodontal status.

Mechanical and biocompatible properties of polymer-infiltrated-ceramic-network materials for dental restoration

Dental restorative materials with high mechanical properties and biocompatible performances are promising.In this work,polymer-infiltrated-ceramic-network materials(PICNs)were fabricated via infiltrating polymerizable monomers into porous ceramic networks and incorporated with hydroxyapatite nano-powders.Our results revealed that the flexural strength can be enhanced up to 157.32 MPa,and elastic modulus and Vickers hardness can be achieved up to 19.4 and 1.31 GPa,respectively,which are comparable with the commercial computer-aided design and computer-aided manufacturing(CAD/CAM)blocks.Additionally,the adhesion and spreading of rat bone marrow mesenchymal stem cells(r BMSCs)on the surface of such materials can be improved by adding hydroxyapatite,which results in good biocompatibility.Such PICNs are potential applicants for their application in the dental restoration.

Optimized sintering and mechanical properties of Y-TZP ceramics for dental restorations by adding lithium disilicate glass ceramics

The novel dental ceramics can be fabricated at lower temperatures when sol-gel derived lithium disilicate glass ceramics(LDGC)was used as an additive for yttria stabilized tetragonal zirconia polycrystalline(Y-TZP)ceramics.The effect of LDGC on the sintering,mechanical,and translucent properties of Y-TZP ceramics was investigated in the present study.The results showed that the LDGC additive effectively improved the densification of Y-TZP at 1100℃,which was much lower than the sintering temperature for pure Y-TZP.When sintered at 1100℃,the Y-TZP with 1 wt%LDGC reached a relative density of 95.45%,and prossessed a flexural strength of 482.4 MPa and a fracture toughness of 5.94 MPa-m12.Moreover,its translucency was also improved.While,the addition of LDGC could result in an escape of yttrium atoms from the grain lattice of zirconia,which induced the tetragonal-monoclinic transformation of zirconia and abnormal growth of monoclinic grains.The escaped yttrium atoms diffused into the intergranular glass phase.The results indicated that the novel Y-TZP-LDGC ceramics has a great potential to be used for all-ceramic restorations.

A dual-axis chewing simulator for in vitro wear test of dental restoration materials

The wear rate of dental restoration materials on fixed, removable, and implant prostheses is important in the maintenance of cuspate form, masticatory efficiency and occlusal stability. Many permanent restoration materials such as composite, amalgam, gold, or porcelain show enough resistance to wear, but the wear rates of newly developed materials are generally unknown. To evaluate the wear rate of these dental materials, in vivo (clinic) and in vitro methods can be used. Since in vivo investigations are expensive, time consuming, and difficult to standardize, various in vitro methods have been developed. The use of a chewing machine is considered the best method, because a variety of wear mechanisms, temperature changes, and chemical effects of food and drink can be simulated simultaneously. This paper describes a dual axis chewing simulator for in vitro wear test of dental restoration materials. It consists of 8 test chambers, two stepper motors and related mechanism, a hot and cool water circle system, and a control unit. In the chambers, samples and antagonists make chewing movements vertically and Albert Ludwigs University, School of dentistry, Freiburg, Germany (Lü XY, Kern M and Strub JR) horizontally driven by the stepper motors so that the gnashing and slippage of two teeth against each other is simulated. A weighted test object is programmed to collide with a sample under precise operator control. The antagonists strike against the samples at various speeds from a slow nudge to snapping. Sample holders are designed for installation of varying samples, from single teeth to complete dentures. Two baths, six valves, and a group of pipes are used for the thermocycling. The machine can simulate various chewing modes in the mouth, including fully programmable thermal water cycling between 5℃ and 60℃ The control unit consists of a computer system with a built in specific program. Important operations such as “Start”, “Zero point”, and “Stop” are carried out by pressing the function keys on the front board of the unit. During the programming process and the simulation, several test modes and relevant test parameters are shown on the monitor. The control unit is connected via a series of interfaces to different controlled parts of the machine, such as the stepper motors and the pumps of cool and warm water.

Advance in Functional Restoration of Injured Nerve with Low Level Laser and its Utilization in the Dental and Maxillofacial Region

The inferior alveolar nerve and facial nerve are the two most important nerves in the dental and maxillofacial region.The injury to them is one of the major postoperative complications after alveolar surgery and orthognathic surgery.However,recovering the nerve function after injury takes a long time and the recovery effect tends to be unsatisfactory.In recent years,an intensively investigated technique,low level laser which has been applying in assisting the recovery of nerve function,has been gradually proved to be effective in clinically treating postoperative nerve injury.In this article we review in terms of the mechanisms involved in low level laser-assisted functional restoration of nerve injury and its clinical application in the recovery of nerve function in the dental and maxillofacial area as well.

MTA与iRoot BP Plus行直接盖髓术治疗龋源性露髓恒磨牙临床疗效分析

目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4月-2019年10月就诊于笔者科室符合纳入标准的53例患者,共53颗患牙,随机分为M组和B组,分别使用MTA与iRoot BP Plus行直接盖髓术,术后定期复查,比较两组的临床疗效。结果:共计45例患者(45颗患牙)完成2年随访,总体成功率84.4%;M组和B组分别为85.7%、83.3%,两组比较差异无统计学意义(P>0.05)。性别、年龄、露髓孔大小等因素对疗效均无显著影响(P>0.05)。结论:成熟恒磨牙术中露髓时使用MTA或iRoot BP Plus行直接盖髓术均可获得良好疗效;相较于性别、年龄、露髓孔大小等因素,如何简单准确评判牙髓状态及避免龈下微渗漏更加值得关注。

基于审美分析的口腔美容修复分类诊疗方案(二):中式审美的内涵与分析方案

欧美国家提出的口腔美感指标(简称欧美审美)与我国口腔美感指标(简称中式审美)存在差异,这些不同在正式修复方案的设计与修复效果评价中对医—患—技三方存在或大或小的影响,处理不当将直接弱化三方的合作效能、拉低患者的满意度,严重时甚至可导致医疗纠纷。本文从做好我国口腔美容修复出发,介绍了口腔中式审美的内涵特征,讨论了口腔审美分析的诊疗价值,并进一步详细介绍了采用改良中式牙科审美社会心理影响量表、口腔美容修复期望值评估尺等进行审美分析评估的流程和方案。

口腔硬组织修复材料仿生设计制备和临床转化

口腔疾病几乎涉及到每个个体,严重影响人民健康和生活质量,已经成为制约国民经济发展和社会资源积累的重要问题。牙齿和颌骨是行使口腔功能和支撑外貌轮廓的重要结构基础。小范围牙齿缺损可能引发牙本质过敏症,大范围缺损则会导致牙齿形态和功能破坏,而牙齿缺失常造成牙槽骨吸收低平,不利于后续修复。临床上牙本质过敏症治疗手段非常有限,以牙本质小管封闭为主,其效果不佳且易复发;材料充填是牙体缺损治疗的主要手段,但现有材料与牙齿力学性能匹配差,界面结合不足,修复体寿命短;而牙槽骨低平的垂直骨增量则是世界性难题。究其原因,是缺乏对牙齿微观结构及其构效关系的深入解析,缺少对牙槽骨再生微环境的深入认识,导致材料设计忽视了从微观结构功能仿生到宏观效果实现的协同考量。因此,发展牙齿/颌骨结构与功能高度仿生的修复材料新技术与临床新策略是目前口腔医学研究的重要战略方向。

年轻恒牙牙髓疾病的临床治疗进展

年轻恒牙因萌出不久,形态结构未发育完全,表现为髓腔大、髓角高尖,根尖孔开放。龋病、牙发育异常或创伤可能导致牙髓受到损伤或感染,甚至进一步发生牙髓坏死,从而直接影响到牙根的正常发育。因此,年轻恒牙牙髓疾病的治疗在临床上是一大挑战。临床治疗的目标是尽量保存活髓,并促进患牙牙根继续发育,使根管壁增厚,根尖孔闭合。该文系统综述因牙髓暴露引起的可复性和不可复性牙髓炎患牙的治疗方案,旨在为年轻恒牙牙髓病变的治疗提供依据,重点为保留健康牙髓、促进牙髓的修复与再生提供参考。

互联网背景下“双微一课”在口腔修复学实验教学中的应用

目的:探讨“双微一课”教学方法在口腔修复学实验教学中的教学效果。方法:试验组(30人)采用“双微一课”教学方法,对照组(30人)采用传统教学方法,通过期末考试成绩和问卷调查评价教学效果。结果:试验组学生的实践技能考核成绩和总成绩均高于对照组,差异有统计学意义(P<0.05),问卷结果显示学生和教师对教学改革的满意率都达到90%以上。结论:“双微一课”教学方法能显著提高口腔修复学实验教学效果,值得进一步推广和应用。

长石质陶瓷磨损研究及有限元数值模拟

利用高速环-块摩擦磨损实验机在10、20、30、40 N载荷下对Sirona CEREC Blocks长石质瓷块进行3.5×105周次磨损实验,得到磨损质量、磨损速率等参数与载荷、磨损周次的变化关系,根据所得变化关系将长石质陶瓷的磨损过程分为3个阶段,观察了各阶段的磨损表面形貌。对Archard磨损模型进行修正改进并通过ABAQUS中UMESHMOTION子程序开展有限元仿真研究。在ALE(Arbitrary Lagrangian-Eulerian)自适应网格区域选取两种节点路径,于3.0×10^(5)周次磨损工况下对4种不同载荷下的磨损深度进行仿真分析,并与实验值对比验证,结果表明10 N载荷工况下磨损深度的最大误差为12.18%,30 N载荷工况下磨损深度的最小误差为8.64%。

铈及铈基材料在口腔疾病领域中的应用

背景:铈(cerium,Ce)是含量最丰富的镧系元素,主要以氧化铈的形式存在。Ce^(3+)和Ce^(4+)两种价态之间快速转化使铈兼具氧化剂和还原剂的作用,具有抗菌、抗炎、促进组织再生和抗肿瘤等多种生物学活性,在口腔医学领域具有广泛的应用。目的:概述铈在抗菌、抗炎、促进组织再生及抗肿瘤中的作用和机制,综述近年来铈和铈基材料在口腔材料改性和口腔疾病诊疗中的研究现状和应用前景。方法:以“cerium,ceria,prosthodontics,prosthesis,restorative dentistry,denture,dental implant,caries,endodontics,pulpitis,periodontitis,periodontal diseases,oral cancer”为英文检索词,以“铈,氧化铈,修复,种植,龋齿,龋病,牙髓,牙周炎,牙周疾病,口腔癌”为中文检索词,分别在Web of Science、PubMed、中国知网及万方数据库进行文献检索,检索时限为各数据库建库至2023年。通过分析和阅读文献进行筛选,按照排除筛选标准纳入文献,最终纳入73篇文献进行综述。结果与结论:①铈主要通过直接接触细菌、氧化应激和破坏细菌生物膜发挥抗菌作用,同时依赖氧化还原酶模拟活性清除活性氧而发挥抗炎功能,铈的成骨和成血管活性涉及ERK和Wnt等一系列信号通路。②铈的抗菌、抗炎、成骨和成血管活性使其在治疗口腔感染性疾病和促进口腔软硬组织再生中具有广阔的应用前景,但铈的抗肿瘤特性在口腔领域的应用仍存在一定空白。③作为口腔陶瓷材料,氧化铈稳定的氧化锆具有优异的机械物理性能,但透光性较低,适用于制作基底瓷、义齿支架和种植体。④依托铈的生物学活性,铈基材料能够有效促进种植体骨和软组织整合,抑制牙齿脱矿和致龋菌生长,促进牙本质牙髓复合体再生,减轻牙周炎炎症反应并促进牙周组织再生,在种植体表面改性、龋病预防、牙髓炎、牙周疾病和口腔癌的诊疗中均有较大的应用潜力。⑤铈在高浓度和长时间给药的情况下存在潜在的毒性,为进一步扩大铈在口腔临床实际中的应用,铈的生物安全性以及铈基材料适应口腔环境的优化在未来仍需更详尽的研究。

1990—2019年中国龋病的疾病负担现状及变化趋势研究

背景龋病是常见的非传染性疾病之一,影响着全球三分之一以上的人口,分析其疾病负担现状及变化趋势能够为龋病的防治策略提供一定的参考价值。目的分析中国龋病的发病、患病和伤残损失寿命年(YLD)现状及变化趋势,为我国制订龋病防治策略提供参考依据。方法提取2019年全球疾病负担(GBD)研究中1990—2019年中国乳牙龋病和恒牙龋病的发病、患病和YLD数据,计算1990—2019年中国乳牙龋病和恒牙龋病的发病人次、患病人数和YLD人年数的变化百分比,并应用Joinpoint回归模型分析1990—2019年中国乳牙龋病和恒牙龋病的年龄标准化发病率、患病率和YLD率的年度变化百分比(APC)与平均年度变化百分比(AAPC)。结果与1990年相比,2019年中国乳牙龋病的发病人次、患病人数和YLD人年数分别减少了25.69%、28.74%和28.63%;恒牙龋病的发病人次、患病人数和YLD人年数分别增加了17.41%、15.84%和15.07%。2019年,在各年龄组中,5~9岁儿童乳牙龋病发病率(118.96%)最高,1~4岁儿童乳牙龋病患病率(53.08%)和YLD率(20.40/10万)最高;20~24岁成年人恒牙龋病的发病率(62.30%)、患病率(32.19%)和YLD率(32.41/10万)均最高。Joinpoint回归模型结果显示:1990—2019年,中国乳牙龋病的年龄标准化发病率(AAPC=0.21%,95%CI=0.19%~0.22%)、患病率(AAPC=0.03%,95%CI=0.01%~0.05%)和YLD率(AAPC=0.03%,95%CI=0.01%~0.05%)整体呈上升趋势;恒牙龋病的年龄标准化发病率(AAPC=-0.05%,95%CI=-0.05%~-0.04%)、患病率(AAPC=-0.23%,95%CI=-0.32%~-0.14%)和YLD率(AAPC=-0.22%,95%CI=-0.31%~-0.13%)整体呈下降趋势。结论中国1990—2019年乳牙龋病疾病负担呈现出加重趋势,尽管恒牙龋病的疾病负担有所下降但依旧严峻,预防龋病不能仅局限于儿童,而应该包括所有年龄段人群。

线上TBL与传统教学法在口腔修复理论教学中的比较

目的:研究以团队为基础教学法(team-basedlearning,TBL)的线上教学效果。方法:以浙江大学2015级本科口腔医学生为对照组,2016级本科口腔医学生为试验组,分别采用传统教学和线上TBL进行口腔修复学Ⅱ的理论学习,比较两者的教学效果。结论:对照组和试验组学生期末成绩没有显著性差异(P=0.73),但试验组形成性评价调查问卷显示学生学习的积极性和满意度极高。结论:线上TBL教学对于提高学生综合素质效果显著。

Root Canal Treatment Outcome and Restorative Condition of Teeth Treated by Undergraduates—A Clinical and Radiographic Evaluation

Background: The aim was to evaluate the nonsurgical Root Canal Treatment (nRCT) outcome, the restorative condition and the relationship between the coronal restoration quality and the outcome of teeth endodontic treated by undergraduates at the University of Caxias do Sul School of Dentistry (UCS-SD), Brazil, between 2019 and 2021. Materials and Methods: Data from the endodontically treated cases were retrieved, and the patients were recalled for a follow-up appointment at the university. The endodontic diagnosis, radiographs, and the presence of definitive restorations were analyzed in the clinical records. During the follow-up appointment, endodontically treated teeth were classified as present or absent. The nRCT was classified as successful (complete or incomplete healing) or failure (uncertain or unsatisfactory healing). Coronal restoration was classified as absent or present. When it was present, it was classified as permanent or temporary, and its quality as adequate or inadequate restoration. The results were presented as percentages. Results: A total of 257 teeth were endodontically treated. The most prevalent diagnosis was Chronic Apical Periodontitis (33.33%) and the most commonly treated teeth were premolars (46.15%). A total of 52 (21%) treated teeth were clinically and radiographically reexamined. The success rate for the nRCT was 98.08%. About 61.54% of this sample had a definitive composite resin restoration. Conclusion: The nRCT success rate was high. Special attention should be given to the presence and quality of the definitive restoration. Clinical Implications: There was no statistically significant impact between the coronal restoration and the nRCT success (P > 0.05).

左上中切牙种植修复后低咬合1例

讨论上前牙缺失患者种植修复后出现低咬合(infraocclusion)现象,分析和讨论此类并发症的原因及临床处理方法。患者左上中切牙外伤致冠根折断至龈下而无法保留,微创拔除患牙后进行不翻瓣即刻种植即刻修复。术后7个月后完成氧化锆饰瓷冠修复,CBCT和根尖X线片检查显示种植体骨结合良好,唇侧骨板厚度充足,边缘骨水平稳定。术后5年随访发现21种植体下沉,呈现低咬合情况。

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.

氢氧化钙髓腔封药治疗年轻恒牙牙髓感染的效果

目的分析氢氧化钙髓腔封药治疗方案对年轻恒牙牙髓感染牙体修复的促进价值。方法选取2018年2月至2021年3月收治的60例年轻恒牙牙髓感染患者为研究对象,依据编号的奇偶性将其分为对照组和观察组,各30例。对照组行三联抗生素髓腔封药治疗,观察组在对照组基础上加氢氧化钙治疗。比较两组的治疗效果。结果观察组的治疗总有效率略高于对照组,但差异无统计学意义(P>0.05)。治疗后,两组的根管壁厚度与牙根长度均增加,根尖孔直径与菌斑指数(PLI)评分均降低,且观察组优于对照组(P<0.05)。治疗后,两组的牙周咬合力与牙齿咀嚼功能均升高,牙龈指数(GI)与牙龈出血指数(BI)评分均降低,且观察组优于对照组(P<0.05)。观察组的不良反应总发生率略低于对照组,但差异无统计学意义(P>0.05)。结论氢氧化钙髓腔封药治疗年轻恒牙牙髓感染的效果优于三联抗生素髓腔封药治疗,但两者均有助于改善患者的恒牙牙体修复质量,提升口腔功能恢复效果,值得推广。