Int J Stomatol

Int J Stomatol ›› 2023, Vol. 50 ›› Issue (2): 186-194.doi: 10.7518/gjkq.2023035

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Research progress on fracture resistance of endodontically treated teeth with different endodontic access cavities

Wang Mudan(),Song Dongzhe,Huang Dingming.()   

  1. State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
  • Received:2022-09-16 Revised:2022-12-02 Online:2023-03-01 Published:2023-03-14
  • Contact: Dingming. Huang E-mail:1490600215@qq.com;dingminghuang@163.com
  • Supported by:
    National Natural Science Foundation of China(81771063);The Key Research and Deve-lopment Program of Sichuan Province(2021YFS0031)

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Abstract:

Root canal therapy is one of the most common and effective methods for treating pulp and periapical disea-ses. The loss of dental tissue during treatment may reduce the fracture resistance of endodontically treated teeth. The design of endodontic access cavities is closely related to the preservation of crown dental tissue. Performing minimally invasive access under the condition of ensuring the effect of root canal therapy to reduce the loss of dental tissue and improve the fracture resistance of endodontically treated teeth has become a research hotspot. Whether minimally invasive access, which is represented by conservative endodontic cavities, can enhance the fracture resistance of endodontically treated teeth compared with the traditional endodontic cavity with linear approach is controversial. This review intends to start with the design points of endodontic access cavities and the status of the research on the fracture resistance of endodontically treated teeth with different endodontic access cavities. We reviewed correlational studies to provide fresh ideas for the application of minimally invasive access in root canal therapy. Studies confirmed that minimally invasive access can reduce the loss of crown dental tissue and stress concentration. However, an excessively minimally invasive access cannot improve the fracture resistance of endodontically treated teeth likely because the minimally invasive design disrupts the linear approach. Designing a new minimally invasive access to account for the preservation of crown dental tissue and the establishment of linear approach may be a future research direction.

Key words: root canal therapy, endodontic access cavity, minimally invasive, fracture resistance

CLC Number: 

  • R 781.05

TrendMD: 

Tab 1

Endodontic access cavity (example based on the maxillary first molars teeth with three canals)"

开髓洞型示意图（远中面）示意图（??面）设计要点优势不足

传统开髓洞型（TEC/

TradAC/TRD）

揭尽髓室顶，建立器械进入根管的直线通路视野清晰，技术敏感性低，可操作性强，感染控制好，并发症少，临床效果确切，临床应用广泛牙体组织损失量大，折裂风险大

保守开髓洞型（CEC/

ConsAC/CON）

从中央窝开髓，必要时扩展洞型以探查根管口，保存部分髓室顶牙体组织损失量小操作视野小，技术敏感性高，可操作性差，感染控制效果不确切，能否提高抗折性存在争议
将根分叉水平的根管中心和髓室底水平的根管口中心连接并延伸到??面，包围形成的多面体
超保守/忍者开髓洞型（UEC/UltraAC/NEC）在中央窝磨出极小洞型，没有进一步扩展，仅满足器械能够进入根管的基本需求牙体组织损失量极小操作视野极小，技术敏感性极高，器械分离风险大，感染控制差，能否提高抗折性存在争议
根管口导向/桁架开髓洞型（DDC/TREC/TUS/TrecAC）磨除根管口到??面的投影通路的牙体组织，预备出器械进入根管的通路，在通路中间留下未改变结构的桁架牙体组织损失量极小操作视野极小，技术敏感性极高，器械分离风险大，感染控制差，能否提高抗折性存在争议
改良开髓洞型（MEC）在传统开髓洞型基础上保留了部分髓室顶牙体组织损失量小操作视野小，技术敏感性高，感染控制有待研究，能否提高抗折性存在争议

直线微创开髓洞型

（SMIAC）

从中央窝开髓，向根管口扩展洞型以探查根管口，保存部分髓室顶牙体组织损失量小，有限的直线入路（器械进入根管或根管冠段弯曲的部分直线入路）操作视野小，技术敏感性高，感染控制有待研究，临床技能要求高，能否提高抗折性有待研究
将根管最大弯曲点的根管中心和髓室底水平的根管口中心连接并延伸到??面，包围形成的多面体

Tab 2

Fracture resistance of endodontically treated teeth with different endodontic access cavities"

研究方法优势不足研究对象开髓洞型设计抗折性能结果c
理论力学a

有限元

分析

基线水平一致，可重复性好，不可控性小，结果误差小，指导临床研究不能完全模拟临床，未考虑应力疲劳，不能解决断裂问题上颌中切牙[26]TEC、MIAMIA>TEC
下颌第一磨牙[27]TEC、MIAMIA>TEC
下颌第一磨牙[28]TEC、MIAMIA>TEC
上颌第一磨牙[15]TEC、CECCEC>TEC
上颌第一前磨牙[8]

TEC、TREC、

SMIAC

SMIAC=TREC>TEC
下颌第一磨牙[22]TradAC、ConsAC、SMIACSMIAC=ConsAC>TradAC
下颌第一磨牙[14]TRD、CON、TUS随着开髓洞型减小，颈部应力增大而根部应力减小

扩展有

限元分

析

基线水平一致，可重复性好，不可控性小，结果误差小，指导临床研究，允许裂纹自动产生和扩展不能完全模拟临床，未考虑应力疲劳上颌第一磨牙[16]TEC、CEC、MECCEC>MEC>TEC
下颌第一前磨牙（严重弯曲“h”形根管）[21]

TEC、CEC、

MCEC

MCEC=CEC>TEC

威布尔

分析

基线水平一致，可重复性好，不可控性小，结果误差小，指导临床研究，预测给定压力下的累积失效率（应力疲劳）和折裂概率不能完全模拟临床上颌第一磨牙[7]TEC、CECCEC>TEC
实验力学b接近临床真实情况样本量较小，基线一致性差，可重复性差，不可控性大，结果误差大上颌切牙、下颌前磨牙、下颌磨牙[36]TEC、CECCEC>TEC
下颌磨牙[30]TEC、CECCEC>TEC
上下颌前磨牙、上下颌磨牙[13]TEC、CEC、NECNEC=CEC>TEC
下颌第一磨牙、下颌第二磨牙[9]TradAC、ConsAC、TrecACTrecAC=ConsAC>TradAC
上颌前磨牙[34]TEC、UECUEC=TEC
第一前磨牙[35]TEC、CECCEC=TEC
上颌第一磨牙[33]TEC、CECCEC=TEC
上颌第一磨牙、上颌第二磨牙[17]TAC、CACCAC=TAC
上颌磨牙[32]TEC、CECCEC=TEC
下颌第一磨牙[10]TradAC、UltraACUltraAC=TradAC
下颌第一磨牙、下颌第二磨牙[20]TEC、CEC、TRECTREC=CEC=TEC
下颌磨牙[18]TEC、UECUEC=TEC

Tab 3

The load approach of endodontically treated teeth"

研究方法研究对象载荷方式示意图
理论力学a上颌中切牙与牙体长轴呈45°，将100 N载荷施加到舌侧切1/3与中1/3交界处[26]
下颌中切牙缺乏相关实验
上颌第一前磨牙

模拟垂直咀嚼力：沿牙体长轴将250 N载荷施加到中央窝[8]；

模拟倾斜咀嚼力：与牙体长轴成45°，将250 N荷载施加到腭尖的颊平面上[8]

下颌第一前磨牙600 N载荷施加到颊尖和远中窝颊侧[21]
上颌第一磨牙模拟最大咀嚼力：800 N载荷施加到颌面4个区域[7,16]

模拟正常咀嚼力：250 N载荷施加到中央窝[15]；

模拟最大咀嚼力：800 N载荷施加到??面5个区域[15]；

模拟侧向咀嚼力：与牙体长轴呈45°，将225 N载荷施加到2个区域[15]

下颌第一磨牙分布式载荷：100 N载荷施加到整个咬合面[28]

模拟垂直咀嚼力：250 N载荷施加于中央窝[14,27]；

模拟侧向咀嚼力：与牙体长轴呈45°，将250 N载荷施加于颊尖舌斜面[14,27]

模拟正常咀嚼力：250 N载荷施加到中央窝[22]；

模拟最大咀嚼力：800 N载荷施加到颌面5个区域（中央窝、近中边缘嵴、远中边缘嵴、近颊尖颊斜面及远颊尖颊斜面）[22]；

模拟侧向咀嚼力：与牙体长轴呈45°，将225 N载荷施加到2个区域（近颊尖颊斜面与远颊尖颊斜面）[22]

实验力学b切牙、前磨牙、磨牙[9-10,13,17-18,20,30,32-36]

载荷器械：球型不锈钢头（直径2~6 mm）；

载荷区域：腭沟（中切牙）或中央窝（前磨牙或磨牙）；

载荷方向：与牙体长轴成一定的角度的斜向载荷（中切牙135°、前磨牙30°、磨牙30°）；

载荷速度：0.5~1 mm·min-1；

载荷性质：静态压缩力，逐步下降25%；

载荷结果：离体牙发生断裂

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