牙科自动去冠器的研制与应用

目的:针对传统牙科去冠器拆除牙冠时存在的不足,研制一种发力恒定且发力大小可调的牙科自动去冠器.方法:该去冠器由壳体、冠钩、传导机构、发力机构、击发机构5个部分组成.利用弹簧蓄力实现冠头在瞬间产生爆发力,破坏冠内黏固剂的黏结力,使全冠松动,继而脱落.结果:该去冠器可安全有效地拆除牙冠,并能解放出一只手来进行基牙和黏膜的保护.结论:该自动去冠器结构简单、操作使用方便,是一种可有效拆除固定修复体的器械,值得临床推广.     

正畸联合修复疗法治疗牙列缺损伴牙颌畸形的效果观察

目的观察正畸联合修复疗法治疗牙列缺损伴牙颌畸形的临床效果。方法选择广东省河源市源城区人民医院口腔科2017年9月-2018年9月收治的牙列缺损伴牙颌畸形患者76例,根据治疗方法不同分为研究组和对照组各38例。其中对照组实施常规修复,研究组采取正畸联合修复疗法。观察2组患者治疗效果、功能改善与美观评分、不良反应。结果研究组临床总有效率为92.11%高于对照组的71.05%(χ~2=14.758,P<0.01)。治疗后研究组咀嚼、吞咽、口语表达及牙齿排列整齐评分均高于对照组(P均<0.01)。研究组不良反应发生率为5.26%低于对照组的18.42%(χ~2=8.296,P<0.01)。结论正畸联合修复疗法治疗牙列缺损伴牙颌畸形疗效显著,可有效改善患者牙齿美观情况,不良反应较少,值得应用。     

A prospective,multi-center,practice-based cohort study on all-ceramic crowns

ObjectivesThe aim of this prospective, multi-center, practice-based cohort study was to analyze factors associated with the success of all-ceramic crowns.MethodsAll-ceramic crowns placed in a practice-based research network ([Ceramic Success Analysis, AG Keramik) were analyzed. Data from 1254 patients with (mostly in-office CAD/CAM) all-ceramic crowns placed by 101 dentists being followed up for more than 5 years were evaluated. At the last follow-up visit crowns were considered as successful (not failed) if they were sufficient, whereas crowns were considered as survived (not lost) if they were still in function. Multi-level Cox proportional hazards models were used to evaluate the association between a range of predictors and time of success or survival.ResultsWithin a mean follow-up period (SD) of 7.2(2)years [maximum:15years] 776 crowns were considered successful (annual failure rate[AFR]:8.4%) and 1041 crowns survived (AFR:4.9%). The presence of a post in endodontically treated teeth resulted in a risk for failure 2.7 times lower than that of restorations without a post (95%CI:1.4–5.0;p = 0.002). Regarding the restorative material and adhesive technique, hybrid composite ceramics and single-step adhesives showed a 3.4 and 2.2 times higher failure rate than feldspathic porcelain and multi-step adhesives, respectively (p < 0.001). Use of an oxygen-blocking gel as well as an EVA instrument resulted in a 1.5–1.8 times higher failure rate than their non-use (p ≤ 0.001).SignificanceAfter up to 15years AFR were rather high for all-ceramic crowns. Operative factors, but no patient- or tooth-level factors were significantly associated with failure.The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00020271).     

Wear of 3D printed and CAD/CAM milled interim resin materials after chewing simulation

PURPOSEThe purpose of this in vitro study was to investigate the wear resistance and surface roughness of three interim resin materials, which were subjected to chewing simulation.MATERIALS AND METHODSThree interim resin materials were evaluated: (1) three-dimensional (3D) printed (digital light processing type), (2) computer-aided design and computer-aided manufacturing (CAD/CAM) milled, and (3) conventional polymethyl methacrylate interim resin materials. A total of 48 substrate specimens were prepared. The specimens were divided into two subgroups and subjected to 30,000 or 60,000 cycles of chewing simulation (n = 8). The wear volume loss and surface roughness of the materials were compared. Statistical analysis was performed using one-way analysis of variance and Tukey''s post-hoc test (α=.05).RESULTSThe mean ± standard deviation values of wear volume loss (in mm³) against the metal abrader after 60,000 cycles were 0.10 ± 0.01 for the 3D printed resin, 0.21 ± 0.02 for the milled resin, and 0.44 ± 0.01 for the conventional resin. Statistically significant differences among volume losses were found in the order of 3D printed, milled, and conventional interim materials (P<.001). After 60,000 cycles of simulated chewing, the mean surface roughness (Ra; μm) values for 3D printed, milled, and conventional materials were 0.59 ± 0.06, 1.27 ± 0.49, and 1.64 ± 0.44, respectively. A significant difference was found in the Ra value between 3D printed and conventional materials (P=.01).CONCLUSIONThe interim restorative materials for additive and subtractive manufacturing digital technologies exhibited less wear volume loss than the conventional interim resin. The 3D printed interim restorative material showed a smoother surface than the conventional interim material after simulated chewing.     

不同全瓷材料和厚度的种植牙冠应力分布有限元分析

目的通过有限元方法比较不同全瓷材料和厚度在种植牙冠修复的应力分布情况,为临床冠部修复材料的选择和设计提供参考。方法建立下颌第一磨牙种植牙冠修复有限元模型,并进行6种冠厚度和4种不同冠修复材料,即树脂基陶瓷(Lava Ultimate和Vita Enamic)、二硅酸锂玻璃陶瓷(IPS e.max CAD)和氧化锆陶瓷(Cercon)进行组合。在下颌第一磨牙面加载600 N,使用有限元软件ANSYS 10.0分析应力分布。结果冠部应力分析显示,4 mm?Cercon组156.05 MPa最高,1 mm?Lava Ultimate组18.85 MPa最低。树脂水门汀应力分析显示,4 mm?Lava Ultimate组62.52 MPa最高,1 mm?IPS e.max CAD组16.74 MPa最低。使用成品基台时,Lava Ultimate组在冠修复体、树脂水门汀中的应力集中较相同冠厚度的个性化基台高。结论随着冠厚度增加,冠修复体和树脂水门汀中的最大主应力集中呈现上升趋势;树脂基陶瓷使用个性化基台更有利于减少应力集中。     

牙冠延长术后桩核修复在牙体缺损至龈下残根残冠患者中的应用观察

目的观察牙冠延长术后桩核修复在牙体缺损至龈下残根残冠患者中的应用效果。方法选取我院2016年10月~2019年11月期间接收的牙体缺损至龈下残根残冠患者140例,根据随机数字表法分成研究组(70例)与对照组(70例),其中对照组接受直接桩核冠修复治疗,研究组接受牙冠延长术后桩核修复治疗。比较两组临床疗效、美观满意度、治疗前与治疗后龈沟液中炎性因子[一氧化氮(NO)、白细胞介素-1β(IL-1β)、前列腺素E2(PGE2)]水平以及治疗前、治疗6周、3个月牙周状况[探诊深度(PD)、龈沟出血指数(SBI)]。结果研究组总有效率97.14%(68/70),较对照组80.00%(56/70)高(P<0.05);治疗6周、3个月研究组PD浅于对照组,SBI少于对照组(P<0.05);治疗3 d,研究组NO、PGE2、IL-1β水平低于对照组(P<0.05);与对照组88.57%(62/70)对比,研究组美观满意度98.57%(69/70)明显较高(P<0.05)。结论牙冠延长术后桩核修复应用于牙体缺损至龈下残根残冠患者中,可增强治疗效果,改善牙周恢复状况,减轻龈沟液中炎性因子,并提高美观度。     

Influence of the coronal restoration on the outcome of endodontically treated teeth

Abstract

Objective: The tooth weakens due to removal of hard tissue during an endodontic procedure. Many dentists find it difficult to choose between different coronal restorations after root canal treatment (RCT). Studies show that the coronal restoration may affect the endodontic prognosis. This student-based study had three aims. (1) Examine the choice of coronal restoration of endodontically treated teeth at a Scandinavian dental school, (2) examine the survival of these restorations and (3) evaluate the influence of the coronal restoration on the outcome of the RCT.

Material and methods: Radiographic and clinical examination was performed on 127 posterior teeth. The quality of the root canal treatment and the periapical status (PAI-index) were evaluated.

Results: 43.8% of the teeth were restored with an indirect coronal restoration and 47.2% with a direct coronal restoration. The period from finished root canal treatment until placement of a permanent coronal restoration was significantly longer for an indirect restoration than a direct restoration. The teeth treated with a PAI score of 1 and 2 following pulpectomy, necrotic pulp treatment and endodontic retreatment was 93.8%, 82.6% and 69.4%, respectively.

Conclusion: There was no significant association between choice of coronal restoration and PAI-score.     

Effect of different composite modulation protocols on the conversion and polymerization stress profile of bulk-filled resin restorations

ObjectiveThe aim of this in vitro study was to test the effect of different composite modulation protocols (pre-heating, light-curing time and oligomer addition) for bulk filling techniques on resin polymerization stress, intra-pulpal temperature change and degree of conversion.MethodsClass I cavities (4 mm depth × 5 mm diameter) were prepared in 48 extracted third molars and divided in 6 groups. Restorations were completed with a single increment, according to the following groups: (1) Filtek Z250XT (room temperature – activated for 20 s); (2) Filtek Z250XT (at room temperature – activated for 40 s); (3) Filtek Z250XT (pre-heated at 68 °C – activated for 20 s); (4) Filtek Z250XT (pre-heated at 68 °C – activated for 40 s); (5) Filtek BulkFill (at room temperature – activated for 20 s); (6) Filtek Z250XT (modified by the addition of a thio-urethane oligomer at room temperature – activated for 40 s). Acoustic emission test was used as a real-time polymerization stress (PS) assessment. The intra-pulpal temperature change was recorded with a thermocouple and bottom/top degree of conversion (DC) measured by Raman spectroscopy. Data were analyzed with one-way ANOVA/Tukey's test (α = 5%).ResultsPre-heating the resin composite did not influence the intra-pulpal temperature (p = 0.077). The thio-urethane-containing composite exhibited significantly less PS, due to a lower number of acoustic events. Groups with pre-heated composites did not result in significantly different PS. Filtek BulkFill and the thio-urethane experimental composite presented significantly higher DC.SignificanceResin composite pre-heating was not able to reduce polymerization stress in direct restorations. However, thio-urethane addition to a resin composite could reduce the polymerization stress while improving the DC.