髓腔通路设计的微创理念及其研究进展

牙髓病和根尖周病是临床常见的口腔疾病,根管治疗是治疗这类疾病最有效的手段.髓腔通路预备即开髓,是根管治疗的首要步骤,一个设计良好的髓腔通路对于根管治疗的成功至关重要.近年来随着微创牙髓治疗学概念的提出,学者们建议对传统髓腔通路设计进行微创改良,强调有目的性地保留部分髓室顶及颈周牙本质的精细开髓,以尽可能保存健康牙体组织...     

颈周牙本质对牙体抗折性能影响的研究进展

剩余牙体结构的完整性影响根管治疗术后患牙远期的保存效果。保留更多的牙体组织对提升患牙的抗折性能及远期修复效果有着重要意义。相关研究发现,颈周牙本质(peri-cervical dentin, PCD)这一结构的保留对剩余牙体的生物力学性能及远期修复保存有着重要作用。该文将就颈周牙本质的定义、作用、研究方法和目前研究中仍存在的问题,以及如何保留进行综述。     

直线通路微创开髓洞型对上颌第一前磨牙力学性能影响的有限元分析

目的通过有限元分析探讨直线通路微创开髓洞型对上颌第一前磨牙力学性能的影响。方法收集2018年6月至2020年6月于四川大学华西口腔医院口腔颌面外科就诊患者因正畸或牙周病拔除的上颌第一前磨牙,从中选取牙体完整、根尖孔发育完成的双根管牙20颗,对其显微CT(micro-CT)数据进行三维重建,在三维模型中模拟传统开髓洞型、桁架开髓洞型与直线通路微创开髓洞型的开髓与根管治疗(每组样本量均为20个)。建模完成后进行有限元分析,记录纵向及斜向负载模式下各组模型的牙颈部von Mises等效应力峰值(VM)并观测各组模型的应力分布模式。结果纵向负载模式下,3种开髓洞型牙颈部颊侧和腭侧VM分别为:桁架开髓洞型[(146.0±12.9)和(167.6±15.9)MPa],直线通路微创开髓洞型[(142.6±13.7)和(168.1±17.4)MPa],传统开髓洞型[(188.7±13.4)和(200.9±25.7)MPa]。与传统开髓洞型相比,桁架开髓洞型(t=9.01,P<0.001;t=4.59,P<0.001)和直线通路微创开髓洞型(t=9.64,P<0.001;t=3.76,P=0.004)均可有效降低根管治疗后上颌第一前磨牙颊侧和腭侧牙颈部VM,同时缓解应力在[牙合]面集中力加载区域、牙颈部及牙根的集中。在斜向负载模式下得到了相似的结果。在两种负载模式下,桁架开髓洞型与直线通路微创开髓洞型间颊腭侧牙颈部VM差异均无统计学意义(P>0.05)。结论直线通路微创开髓洞型可以有效保护根管治疗后上颌第一前磨牙的力学性能,具有一定的临床可行性。     

缓解牙体预备后活髓基牙牙本质敏感的方法研究进展

牙体预备后的活髓基牙常出现刺激性酸痛等牙本质敏感症状，虽然目前常用氧化锌丁香油水门汀粘固暂冠的方法安抚、保护牙髓，但其临床效果并不十分理想。因此，如何更有效地安抚、保护牙髓，缓解基牙牙本质敏感受到学者们的关注。本文就此作一综述。     

开髓方式与全冠修复对上颌中切牙应力分布影响的三维有限元分析

目的 采用三维有限元分析法分析不同开髓方式及全冠修复对上颌中切牙牙体组织应力分布的影响。方法 采用锥形束CT扫描上颌中切牙构建上颌中切牙三维实体模型,根据开髓方式的不同及是否行全瓷冠修复建立4组实验模型：传统开髓树脂充填（A）组、传统开髓后全瓷冠修复（B）组、微创开髓树脂充填（C）组和微创开髓后全瓷冠修复（D）组。于舌侧切1/3与中1/3交界处施加大小为100 N、与牙体长轴呈45°方向的力,对所建立的牙体组织有限元模型中最大主应力、von Mises应力和改良von Mises应力进行分析。结果 1）应力峰值：A组的最大主应力、von Mises应力和改良von Mises应力的应力峰值均表现为最大,除了D组的von Mises应力峰值略低于C组外,C组的最大主应力及改良von Mises应力的应力峰值均表现为最低,D组的最大主应力及改良von Mises应力的应力峰值均低于A组和B组。2）应力分布：相比于A组,C组牙颈部区域的应力集中程度较低,且应力集中的区域较小;在牙根牙本质处,C组的应力分布与A组相比更为均匀,应力分散至根尖更多区域;冠修复后,B组和D组在牙根区域的应力分布未见明显差异;B组应力分布状态与A组相比未见明显改变;D组相比于C组应力分布状态未见明显改变。结论 从生物力学角度考虑,上颌中切牙开髓尽量采取微创开髓方式;传统开髓后建议行冠修复,微创开髓后冠修复未见明显优势。     

开髓方式与全冠修复对上颌中切牙应力分布影响的三维有限元分析

目的 采用三维有限元分析法分析不同开髓方式及全冠修复对上颌中切牙牙体组织应力分布的影响。方法 采用锥形束CT扫描上颌中切牙构建上颌中切牙三维实体模型,根据开髓方式的不同及是否行全瓷冠修复建立4组实验模型：传统开髓树脂充填（A）组、传统开髓后全瓷冠修复（B）组、微创开髓树脂充填（C）组和微创开髓后全瓷冠修复（D）组。于舌侧切1/3与中1/3交界处施加大小为100 N、与牙体长轴呈45°方向的力,对所建立的牙体组织有限元模型中最大主应力、von Mises应力和改良von Mises应力进行分析。结果 1）应力峰值：A组的最大主应力、von Mises应力和改良von Mises应力的应力峰值均表现为最大,除了D组的von Mises应力峰值略低于C组外,C组的最大主应力及改良von Mises应力的应力峰值均表现为最低,D组的最大主应力及改良von Mises应力的应力峰值均低于A组和B组。2）应力分布：相比于A组,C组牙颈部区域的应力集中程度较低,且应力集中的区域较小;在牙根牙本质处,C组的应力分布与A组相比更为均匀,应力分散至根尖更多区域;冠修复后,B组和D组在牙根区域的应力分布未见明显差异;B组应力分布状态与A组相比未见明显改变;D组相比于C组应力分布状态未见明显改变。结论 从生物力学角度考虑,上颌中切牙开髓尽量采取微创开髓方式;传统开髓后建议行冠修复,微创开髓后冠修复未见明显优势。     

牙修复后折裂的原因及预防

本文从窝洞制备、牙髓病治疗及修复材料等各个环节对牙齿折裂的影响进行分析,并提出了相应的预防措施,以延长修复后牙体的寿命。     

直线通路微创开髓洞型对上颌第一前磨牙力学性能影响的有限元分析

目的通过有限元分析探讨直线通路微创开髓洞型对上颌第一前磨牙力学性能的影响。方法收集2018年6月至2020年6月于四川大学华西口腔医院口腔颌面外科就诊患者因正畸或牙周病拔除的上颌第一前磨牙, 从中选取牙体完整、根尖孔发育完成的双根管牙20颗, 对其显微CT(micro-CT)数据进行三维重建, 在三维模型中模拟传统开髓洞型、桁架开髓洞型与直线通路微创开髓洞型的开髓与根管治疗(每组样本量均为20个)。建模完成后进行有限元分析, 记录纵向及斜向负载模式下各组模型的牙颈部von Mises等效应力峰值(VM)并观测各组模型的应力分布模式。结果纵向负载模式下, 3种开髓洞型牙颈部颊侧和腭侧VM分别为:桁架开髓洞型[(146.0±12.9)和(167.6±15.9)MPa], 直线通路微创开髓洞型[(142.6±13.7)和(168.1±17.4)MPa], 传统开髓洞型[(188.7±13.4)和(200.9±25.7)MPa]。与传统开髓洞型相比, 桁架开髓洞型(t=9.01, P<0.001;t=4.59, P<0.001)和直线通路微创开髓洞型(t=9.64, P<0....     

Influence of minimally invasive access cavities on load capacity of root-canal-treated teeth: A systematic review and meta-analysis

This systematic review (PROSPERO-CRD42020147333) aimed to compare the effects of conservative, ultraconservative and truss access cavities with traditional access cavities on the load capacity of root-canal-treated teeth. Online databases were searched until December 2021, and 25 ex vivo studies in which the effects of different access cavities on load capacity of permanent teeth had been investigated were included. Quality assessment was completed using a modified risk of bias tool for in vitro studies adapted from previous studies. Meta-analysis was performed using the maximum-likelihood-based random-effects model with similar groups. Conservative access cavities significantly improved the load capacity of maxillary premolars (p < 0.01 [−1.32, −0.028]) and molars (p < 0.05 [−0.89, −0.02]) compared to traditional access cavities. Additionally, truss access cavities significantly improved the load capacity of mandibular molars with (p < 0.05, [−1.18, −0.02]) mesio-occluso-distal cavity preparations. Higher levels of evidence are needed to determine the long-term implications of minimal preparations for treatment outcomes.     

Influence of access cavity design on fracture strength of endodontically treated lower molars

To assess whether access cavity design influences the fracture strength of endodontically treated and restored molars. Fifty human lower molars with standard crown dimensions were selected and assigned to the following groups: S – positive control (healthy tooth), ET – negative control (conventional endodontic access (CEA) and no restoration), NI – negative control (minimally invasive endodontic access (MEA) and no restoration), ETR (CEA + restoration with Bulkfill flow) and NIR (MEA + restoration with Bulkfill flow). The specimens were subjected to a compression test. The teeth were inspected for the site of fracture: either pulp floor or cusp. ANOVA, followed by Tukey’s multiple comparison test (α = 5%), was used for statistical analysis. The type of access cavity preparation did not increase the fracture strength of endodontically treated teeth. Even with the restoration, all teeth with endodontic access performed had a higher incidence of fractures at the pulp chamber floor level.     

Impact of Contracted Endodontic Cavities on Root Canal Disinfection and Shaping

IntroductionThe impact of minimally invasive endodontic procedures on root canal disinfection has not been determined. This ex vivo study compared root canal disinfection and shaping in teeth with contracted or conventional endodontic cavities.MethodsMandibular incisors with oval-shaped canals were selected and anatomically matched based on micro–computed tomographic (micro-CT) analysis and distributed into 2 groups. Conservative and conventional access cavities were prepared, and the canals were contaminated with a pure culture of Enterococcus faecalis for 30 days. Root canal preparation in both groups was performed using the XP-endo Shaper instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and 2.5% sodium hypochlorite irrigation. Intracanal bacteriologic samples were taken before and after preparation, and DNA was extracted and subjected to quantitative polymerase chain reaction. Micro-CT scans taken before and after preparation were used for shaping evaluation. Bacteriologic data were analyzed by the Poisson regression model and the chi-square test with Yates correction. Micro-CT data were analyzed by the Wilcoxon, Mann-Whitney, and Student t tests with the significance level set at 5%.ResultsAll initial samples were positive for E. faecalis. After preparation, the number of bacteria-positive samples was significantly higher in the contracted cavity group (25/29, 86%) than in the conventional cavity group (14/28, 50%) (P < .01). Intergroup quantitative comparison showed that the reduction in bacterial counts was also significantly higher in the group of conventional cavities (P < .01). Micro-CT data revealed no significant difference in the amount of unprepared areas between groups.ConclusionsOur findings showed that although shaping using an adjustable instrument was similar between groups, disinfection was significantly compromised after root canal preparation of teeth with contracted endodontic cavities.