Skip to main content
Download PDF

Effect of access cavities on the biomechanics of mandibular molars: a finite element analysis

BMC Oral Health volume 23, Article number: 196 (2023) Cite this article

Abstract

Introduction

This study aimed to predict the fracture resistance of a mandibular first molar (MFM) with diverse endodontic cavities using finite element analysis (FEA).

Methods

Five experimental finite element models representing a natural tooth (NT) and 4 endodontically treated MFMs were generated. Treated MFM models were with a traditional endodontic cavity (TEC) and minimally invasive endodontic (MIE) cavities, including guided endodontic cavity (GEC), contracted endodontic cavity (CEC) and truss endodontic cavity (TREC). Three loads were applied, simulating a maximum bite force of 600 N (N) vertically and a normal masticatory force of 225 N vertically and laterally. The distributions of von Mises (VM) stress and maximum VM stress were calculated.

Results

The maximum VM stresses of the NT model were the lowest under normal masticatory forces. In endodontically treated models, the distribution of VM stress in GEC model was the most similar to NT model. The maximum VM stresses of the GEC and CEC models under different forces were lower than those of TREC and TEC models. Under vertical loads, the maximum VM stresses of the TREC model were the highest, while under the lateral load, the maximum VM stress of the TEC model was the highest.

Conclusion

The stress distribution of tooth with GEC was most like NT. Compared with TECs, GECs and CECs may better maintain fracture resistance, TRECs, however, may have a limited effect on maintenance of the tooth resistance.

Peer Review reports

Introduction

The primary goal of endodontic treatment is the long-term retention of functional teeth but increasing the long-term retention rate of endodontically treated teeth (ETT) is still a great challenge. For decades, dental practitioners have been looking for ways to enhance fracture resistance, because tooth fracture is considered one of the main reasons resulting in the extraction of ETT [1]. Benefitting from technological advances in optics, radiology, instrumentation, materials and computer systems over the last decades, the concept of minimally invasive endodontics (MIE) to preserve as much sound dentin as possible was proposed to enhance fracture resistance [2] .

Even 10 years after the first proposed application and the religious support from proponents and influencers in the field of endodontology, MIE is still controversial because many critical aspects still remain to be studied, and no clear evidence shows that MIE is better than traditional endodontics in fracture resistance [3,4,5]. Some important factors may affect the fracture strength of ETT, such as structural integrity [6], morphology [7], sizes of root canal preparations [8] and prosthetic reasons [9]. Among them, structural integrity, in which marginal ridge and pericervical dentin (PCD) matter, was thought to be a crucial aspect [10]. MIE cavities are applied to conserve structural integrity by using different cavity designs in building pathways to each root canal during endodontic treatment. Several designs of MIE cavities have been proposed, including contracted endodontic cavities (CECs)[5], which are also known as “ninja” or ultraconservative endodontic cavities [11], truss endodontic cavities (TRECs) [12], and computer-aided design guided endodontic cavities (GECs) [13] .

Finite element analysis (FEA) is a promising theoretical stress analysis method because the sample demand is small and the stress inside the model can be displayed, indicating the fracture risk areas intuitively [14]. Additionally, it allows for good control of variables in experiments, overcoming some drawbacks of in vivo studies, such as bias in sample selection [5, 15].

To study whether or which MIE cavity can better maintain the resistance of tooth fracture after endodontic treatment, different MIE cavity models of a mandibular first molar (MFM) were established using a three-dimensional finite element method. A 3-point vertical/lateral static force load simulating normal masticatory force and an 8-point vertical static force load simulating maximum bite force were applied on the occlusal surface of different models. The null hypothesis is that different endodontic cavities behavior similar on stress distribution for an MFM. The maximum von Mises (VM) stress and three cross sections of different models were evaluated.

Materials and methods

Subjects

With consent of the patient and approval by the ethics committee of the School of Stomatology of the fourth Military Medical University (IRB-REV-2,020,044), a fresh, intact, non-carious, lightly wear, mature human MFM with three canals was obtained and scanned with a micro–computed tomographic scanner (Y. Cheetah, Germany). The scanning parameters were as follows: 80 kV, 10 W, and 1.5 μm slice thickness. The image data were exported in digital imaging and communications in medical (DICOM) format. A MIMICS 16.0 interactive medical imaging system (Materialise; Belgium) was used to identify the different hard tissues and design different endodontic cavities. Three-dimensional (3D) objects (enamel and dentin) were automatically created in the form of masks and exported as STL files. These files were refined with reverse engineering software (Geomagic Studio 10, NC). The enamel and dentin were combined using 3-Matic Research 12.0 (Materialise; Belgium).

Cavity designs

In this research, a natural tooth (NT) and 4 endodontically treated MFM models were investigated.

According to the volumes of removed coronal dentin and PCD, 4 cavity preparations were adopted, including the GEC [13], CEC [2], TREC [12] and traditional endodontic cavity (TEC) [14]. (Fig. 1A)

Fig. 1
figure 1

Schematic diagrams of different finite element models, components in one model and 3 force loading conditions

A. Representative schematic diagrams of different finite element models: NT (natural tooth), GEC (guided endodontic cavity), CEC (contracted endodontic cavity), TREC (truss endodontic cavity), and TEC (traditional endodontic cavity) models

B. Representative schematic diagram with different components in one finite element model

C. Representative schematic diagram of different force load patterns: vertical and lateral static force loads (three contact points, 225 N in total to simulate normal vertical mastication force load) were applied on the occlusal surface (C-1), and vertical static force loads (eight contact points, 600 N in total to simulate the maximum bite force load) were applied on the occlusal surface. (C-2)

Full size image

The pathways of the GEC model were three separating cylinders in the direction of the coronal 1/3 of every root canal so that the PCD could be preserved as much as possible. The CEC outline was determined with three cylinders straight into the root canal orifices meeting the occlusal surface. The outline of TREC was determined with three cylinders straight to the root canals and vertical to the partially overlapping occlusal surface.

Geometry acquisitions

With the appropriate modifications of the microcomputed tomographic data, 3-dimensional models of endodontically treated teeth were created based on the cavities described previously. Root canal therapy was simulated by computer according to a standardized procedure [16]. The distal root canal was enlarged to 0.40 mm/0.06 taper files based on the canal geometry. The mesial root canals were enlarged to 0.25 mm/0.04 taper. The working length was set at 0.5 mm coronal to the apical foramen. The enlarged root canals were filled with gutta-percha. From the root canal orifice to the pulp chamber roof, every cavity was restored with flowable bulk resin (3 M ESPE-Filtek Bulk-Fill Flowable, USA). The rest of the cavity was restored with bulk fill composite resin (3 M ESPE-Filtek Bulk-Fill Posterior Restorative, USA). The material properties were referenced from the literature and are listed in Table 1.

Table 1 Mechanical Properties of the Investigated Materials [39,40,41]
Full size table

The periodontal ligament was generated by creating a uniform 0.25 mm layer around the root [17]. Meanwhile, the alveolar bone was modelled as a 20-mm cube around the periodontal ligament. Overall, the finite element models were constituted by 7 fundamental parts (Fig. 1.B). The number of tetrahedral elements (4-tet) for the models ranged from 443,973 to 526,923. The volumes of dentin and enamel in each model were recorded.

Model generation

The FEM was performed using HyperMesh 14.0 (Altair, USA) to calculate VM stress in the enamel and dentin. The analysis was based on the following assumptions:

  1. (1)

    Each material was presumed to be homogeneous, isotropic and linearly elastic.

  2. (2)

    There was perfect bonding between each component.

  3. (3)

    There was no flaw in the initial model.

  4. (4)

    There were rigid constraints on the base and lateral surfaces of the alveolar bone.

Force loading processes

The force loading processes [18] were as follows:

Load A (3-point vertical force load): The models received a vertical static force load of 225 N (N) in total to simulate a normal vertical mastication force load. The force load was applied to the occlusal surface at 3 registered contact points (i.e., separately located at the mesiolingual cusp, mesiobuccal cusp and distal cusp) (Fig. 1. C-1, red arrow).

Load B (3-point lateral force load): A static force load of 225 N was applied laterally (45° to the tooth axis) at 3 registered contact points (i.e., separately located at the mesiolingual cusp, mesiobuccal cusp and distal cusp) to simulate the lateral mastication force load (Fig. 1. C-1, black arrow).

Load C (8-point vertical force load): A static force load of 600 N was applied vertically to 8 contact points registered (i.e., separately located at the mesiolingual cusp, the distolingual cusp, mesiobuccal cusp, the distobuccal cusp, and the distal cusp) on the occlusal surface to simulate the maximum bite force load (Fig. 1. C-2, red arrow).

The force load at each contact point was applied over a specified contact surface area. The maximum VM stress and VM stress in each model were computed and analyzed. The distribution of VM stress on the cross-sectional images at the level of the cemento-enamel junction (CEJ), the pulp chamber floor (PCF), and the apical foramen (AF) was investigated [14]. A convergence test was conducted to determine the size of elements in finite element modeling and the mesh was refined continuously until the FEA result did not change greatly. Mega pascal (MPa) was used as the unit of stress.

Results

All five three-dimensional finite element models were established successfully. The VM stress diagrams of all the models are listed in Fig. 2. The VM stress value increases gradually from blue to red. In all models, the sites around the force load points and cervical regions were red, indicating higher VM stress (Fig. 2). The VM stress on the occlusal surface was spread in an approximate pattern from the force load points. The part with higher VM stress in one model is the area more prone to cracking of the model. The maximum VM stress is the peek value of VM stress in each model under different loads. Under certain stress load, the model with the highest maximum VM stress was the one most prone to fracture in all models. The maximum VM stress in all models occurred at the sites around the force load points on the occlusive surface of the model, and the values of maximum VM stresses are listed in Fig. 3.

Fig. 2
figure 2

Diagrams of VM stress in different finite element models under three force loads

Full size image
Fig. 3
figure 3

The maximum von Mises stress values (MPa) in each model

Full size image

By calculating the difference in volume cavity preparation between ETT models and NT, the volumes of removed dentin in GEC, CEC, TREC, and TEC were 33.16 mm3, 23.17 mm3, 28.34 mm3 and 45.57 mm3.

Under the vertical 3-point force load, the maximum VM stresses in the NT, GEC, CEC, TREC and TEC models were 203.1 MPa, 208.5 MPa, 210.2 MPa, 229.6 MPa and 210.6 MPa, respectively (Fig. 3). The maximum VM stress of the NT model was the lowest in all models, while that of TREC was the highest. Both the maximum VM stresses of the GEC model and CEC model were lower than those of the TREC model and TEC model. Although the maximum VM stress of the TEC model was lower than that of the TREC model, the VM stress in the investigated sections and most part of the crown in the TEC model was higher than that in the TREC model (Fig. 2). The maximum VM stress of the CEC model was slightly higher than that of the GEC model. The VM stress of the CEC model in the CEJ and PCF sections was higher than that of the GEC model, while in most parts of the crown, it was lower (Fig. 2).

Under the lateral 3-point force load, the maximum VM stresses in the NT, GEC, CEC, TREC and TEC models were 340.2 MPa, 345.2 MPa, 353.9 MPa, 372.2 MPa and 452.3 MPa, respectively (Fig. 3). The maximum VM of the NT model was the lowest, while that of the TEC model was highest in all models. The maximum VM stress of the TREC model was higher than that of the CEC model and GEC model. The maximum VM stress of the CEC model was higher than that of the GEC model. In the investigated sections, the VM stresses of the GEC and CEC were similar, but in certain parts of the crown, the VM stress of the GEC was remarkably higher (Fig. 2).

Under the vertical 8-point force load, the maximum VM stresses in the NT, GEC, CEC, TREC and TEC models were 198.4 MPa, 195.5 MPa, 189.5 MPa, 232.2 MPa and 218.7 MPa, respectively (Fig. 3). The maximum VM stress of the NT model was slightly higher than that of the CEC model and GEC model. The maximum VM stress of the TEC model was slightly lower than that of the TREC model but remarkably higher than that of the GEC model and CEC model. The maximum VM stress of the TREC model was much higher than that of the other models, while that of the CEC was the lowest. The VM stress in the crown of the NT model was slightly higher than that in the GEC model and CEC model, but in the PCF and AF sections, it was lowest in the ETT models. Although the VM stress in the zones on the occlusive surface of the TEC model was lower than that in the TREC model, the VM stress in most parts of the TEC model was the highest (Fig. 2). In the investigated sections, the VM stresses of CECs and GECs were lower than those of TRECs and TECs. The VM stress in the CEJ and PCF sections of the CEC model was higher than that of the GEC, but in the crown, it was lower (Fig. 2).

Discussion

Since different designs of the MIE cavity have been proposed, many practitioners have already begun to apply them in clinical practice [2, 19, 20]. Previous studies have reported conflicting results regarding the influence of cavities on the fracture resistance of ETT. Many studies have shown that there are no statistically significant differences in resistance to failure between MIE cavities and TECs [21,22,23]. However, some studies have shown that compared with TEC, TREC and CEC improved the fracture resistance [12, 24, 25]. The MFM is the first erupting permanent tooth, and as a result, it is susceptible to decay or caries; thus, in many cases, it requires endodontic treatment [26]. It also has the highest risk of tooth fracture and is extracted after endodontic treatment [1, 27]. Therefore, an MFM was selected as the object of the study.

The straight-line access is paramount to successful shaping, allowing for easier location of the root canal, more sufficient instrument preparation, and fewer preparation complications. [28] In previous MIE cavity designs, to pursue more reduction in the size of the cavity, prognosis of root canal treatment may be compromised. [4, 23] However, a recent study shows there was a negative correlation between the amount of dentin in the coronal region and the fracture resistance of the tooth.[29] In our study, the straight-line access of GEC was simulated using cylinders in the same orientation as coronal 1/3 of every root canal. The design of GEC retains both the advantage of reducing the loss of PCD and the straight-line access, balancing biomechanical properties and clinical convenience.

In this study, different MIE cavity models were established using the three-dimensional finite element method and were compared with NT and TEC. The MIE cavity designs could reserve more hard tissue, especially PCD, compared with TEC. Since all cavity models were computer-designed, the calculated hard tissue removal was ideal. From clinical perspectives, the root canal orifices of the teeth with CECs and TRECs could not be directly located, so it was almost certain to remove more hard tissue in the root canal detection than in the in vitro model. Thus, CECs and TRECs may increase the potential for deviations and/or instrument fracture [30]. However, in GEC, the volume of tooth hard tissue removal can be controlled within a certain range, and the difference between the long axis of the root canal under TEC and GEC is acceptable [31].

The null hypothesis of this study was rejected. Under the 3-point vertical and lateral force loads, the maximum VM stress and VM stress in all investigated sections of NT were the lowest. Therefore, NT may have the best fracture resistance under normal masticatory force loading. Under 8-point vertical load, the VM stress in the crown of the NT model was slightly higher than that in the CEC model and GEC model; however, in the root, it was the lowest in all models, which may indicate that under maximum bite force load, root fracture infrequently occurs in NT. However, the incidence of crown fracture in NT may be higher than ETT with CEC and GEC.

Consistent with previous studies [14, 15], the sites around force load points and the cervical region in each model had higher VM stress, indicating that apart from the sites of the force load, PCD is another stress concentration area. Compared to the GEC and CEC models, the VM stress of the TEC model were higher, while the thickness of PCD was smaller. Hence, it is predictive that ETT with TECs seems more prone to fracture than those with CECs and GECs, especially in the cervical regions. Özyürek et al. [32] found that there was no significant difference in the fracture strengths of teeth prepared using the TEC and CEC approaches. However, they found that teeth in the CEC group had more restorable fractures than teeth in the TEC group. In this respect, it is consistent with the existing study.

Some studies have demonstrated that no obvious difference was found between CEC and TEC in fracture resistance [30, 33, 34].However, the present study indicates that CECs may have better fracture resistance than TECs. The reason may be that in this experiment, all ETT cavities were computer-designed, and PCD and dentin in the pulp chamber roof were idealized to be preserved to the largest extent. In the clinic, most practitioners prepare CECs with a combination of dentists’ experience and the results of cone bone computed tomography scans. [20] It is inevitable that more PCD and dentin in the pulp chamber roof will be removed in CECs, which will weaken the fracture resistance of ETT with CECs.

Compared to CECs, GECs seem to be more operable and predictable, because GECs allow more predictable and expeditious location with significantly less substance loss [13]. Although there were some reports about the accuracy and dentin loss of a GEC [31, 35], few reports about the effect on fracture resistance of GEC were found. In this study, the maximum VM stress and the stress distribution of the GEC model under all force loads were most like NT model. It is reasonable to believe that the fracture resistance of teeth in the GEC group is most like that in the NT model. Under two vertical loads, the VM stress of a GEC in the crown was higher than that of a CEC, but in the root, it was similar or lower. Hence, compared with CECs, GECs may increase the probability of crown fracture but reduce the risk of root fracture. This is probably because pathways of root canals were in the different directions in the GEC, the transmission of the stress was dispersed. Less stress was transmitted to the PCD and the root of the tooth, and more stress concentrated in the crown may led to more restorable fracture in teeth with GECs than in those with CECs. In this respect, GECs may be superior to CECs for the long-term retention of MFMs. However, this still needs to be confirmed by further studies.

Compared to TECs, TRECs seem to have slight advantage in fracture resistance under lateral force loads, but under the vertical force load, the result seems to be the opposite. Compared to TECs, TRECs may have a limited effect on tooth resistance enhancement. Thus, the maximum VM stresses of TREC model under all forces were higher than those of GEC and CEC models. A recent study showed that teeth with TRECs have better fracture strengths than those with CECs [25]. However, the present study shows that more solid evidence is still needed to prove that TRECs have a positive effect on fracture resistance enhancement than TECs.

The result of an experimental stress analysis by Silva et al. [36] using a universal testing machine appears at first sight to contradict the present study. In fact, the load pattern in Silva’s experiment is more similar to the 8-point vertical loads in our study. In our present study, there were the other two representative loads were applied. The advantage of the MIE cavity over the TEC in terms of fracture resistance under vertical loads was also less obvious. (Fig. 3). However, under lateral load, GECs and CECs have a more obvious advantage over TECs. In this respect, the results of this experiment are in agreement with the results of the existing study.

Compared to experimental stress analysis (ESA) using extracted natural teeth, FEA allows for better control of variables and excludes bias due the experimental manipulation such as practitioner experience and variations between teeth. Therefore, the use of FEA rather than ESA has been advocated in the methodological design of studies on the effect of MIE cavity on the fracture resistance of ETT. [37]However, FEA still cannot fully simulate the real oral environment. Each occlusion cycle is characterized by complex transient loads.[38] Although different cavities were compared under the analytical conditions of the present study, only three representative loads were performed on the same tooth model in our study. [29] More appropriate loads and samples are still needed to make the experiment more convincing for further research, and more in vitro and clinical randomized controlled trials are still needed to verify the results of this study.

Conclusion

Within the limitations of this study, the cervical region was a stress concentration area in all models. The stress distribution of tooth with GEC was most like NT. Compared with TECs, GECs and CECs may better maintain fracture resistance, TRECs, however, may have a limited effect on maintenance of the tooth resistance. GECs may be superior to CECs for MFMs in that GECs may lead to more restorable fractures.

Data Availability

All data generated or analysed during this study are included in this published article.

Abbreviations

MFM:

Mandibular first molar

FEA:

Finite element analysis

ETT:

Endodontically treated teeth

NT:

Natural tooth

TEC:

Traditional endodontic cavity

MIE:

Minimally invasive endodontic

GEC:

Guided endodontic cavity

CEC:

Contracted endodontic cavity

TREC:

Truss endodontic cavity

PCD:

Pericervical dentin

VM:

Von Mises

ESA:

Experimental stress analysis

References

  1. Toure B, Faye B, Kane AW, Lo CM, Niang B, Boucher Y. Analysis of reasons for extraction of endodontically treated teeth: a prospective study. J Endod. 2011;37(11):1512–5.

    Article  PubMed  Google Scholar 

  2. Clark D, Khademi JA. Case studies in modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010;54(2):275–89.

    Article  PubMed  Google Scholar 

  3. Silva E, Pinto KP, Ferreira CM, Belladonna FG, De-Deus G, Dummer PMH, Versiani MA. Current status on minimal access cavity preparations: a critical analysis and a proposal for a universal nomenclature. Int Endod J. 2020;53(12):1618–35.

    Article  PubMed  Google Scholar 

  4. Barbosa AFA, Silva E, Coelho BP, Ferreira CMA, Lima CO, Sassone LM. The influence of endodontic access cavity design on the efficacy of canal instrumentation, microbial reduction, root canal filling and fracture resistance in mandibular molars. Int Endod J. 2020;53(12):1666–79.

    Article  PubMed  Google Scholar 

  5. Silva E, Pinto KP, Ajuz NC, Sassone LM. Ten years of minimally invasive access cavities in endodontics: a bibliometric analysis of the 25 most-cited studies. Restor Dent Endod. 2021;46(3):e42.

    Article  PubMed  PubMed Central  Google Scholar 

  6. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. J Endod. 1989;15(11):512–6.

    Article  PubMed  Google Scholar 

  7. Pilo R, Metzger Z, Brosh T. Effect of root morphology on the susceptibility of endodontically treated teeth to vertical root fracture: an ex-vivo model. J Mech Behav Biomed Mater. 2017;69:267–74.

    Article  PubMed  Google Scholar 

  8. Munari LS, Bowles WR, Fok ASL. Relationship between Canal Enlargement and Fracture load of Root dentin sections. Dent Mater. 2019;35(5):818–24.

    Article  PubMed  Google Scholar 

  9. Aslan TSB, Er Ö, Ustun Y, Cinar F. Evaluation of fracture resistance in root canal-treated teeth restored using different techniques. Niger J Clin Pract. 2018;21(6):795–800.

    Article  PubMed  Google Scholar 

  10. Clark D, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010;54(2):249–73.

    Article  PubMed  Google Scholar 

  11. Silva E, Versiani MA, Souza EM, De-Deus G. Minimally invasive access cavities: does size really matter? Int Endod J. 2021;54(2):153–5.

    Article  PubMed  Google Scholar 

  12. Abou-Elnaga MY, Alkhawas MAM, Kim HC, Refai AS. Effect of Truss Access and Artificial Truss Restoration on the fracture resistance of endodontically treated Mandibular First Molars. J Endod. 2019;45(6):813–7.

    Article  PubMed  Google Scholar 

  13. Connert T, Krug R, Eggmann F, Emsermann I, ElAyouti A, Weiger R, Kuhl S, Krastl G. Guided Endodontics versus Conventional Access Cavity Preparation: a comparative study on substance loss using 3-dimensional-printed Teeth. J Endod. 2019;45(3):327–31.

    Article  PubMed  Google Scholar 

  14. Jiang Q, Huang Y, Tu X, Li Z, He Y, Yang X. Biomechanical Properties of First Maxillary Molars with different endodontic cavities: a finite element analysis. J Endod. 2018;44(8):1283–8.

    Article  PubMed  Google Scholar 

  15. Saber SM, Hayaty DM, Nawar NN, Kim HC. The Effect of Access cavity designs and sizes of Root Canal Preparations on the Biomechanical Behavior of an endodontically treated Mandibular First Molar: a finite element analysis. J Endod. 2020;46(11):1675–81.

    Article  PubMed  Google Scholar 

  16. Luo B, Sun X, He L, Zhao L, Liu X, Jiang Q. Impact of different axial wall designs on the fracture strength and stress distribution of ceramic restorations in mandibular first molar. BMC Oral Health. 2022;22(1):549.

    Article  PubMed  PubMed Central  Google Scholar 

  17. Wu J, Liu Y, Li B, Wang D, Dong X, Sun Q, Chen G. Numerical simulation of optimal range of rotational moment for the mandibular lateral incisor, canine and first premolar based on biomechanical responses of periodontal ligaments: a case study. Clin Oral Investig. 2021;25(3):1569–77.

    Article  PubMed  Google Scholar 

  18. D’Souza KM, Aras MA. Three-dimensional finite element analysis of the stress distribution pattern in a mandibular first molar tooth restored with five different restorative materials. J Indian Prosthodont Soc. 2017;17(1):53–60.

    Article  PubMed  PubMed Central  Google Scholar 

  19. Lara-Mendes STO, Barbosa CFM, Santa-Rosa CC, Machado VC. Guided Endodontic Access in Maxillary Molars using cone-beam computed tomography and computer-aided Design/Computer-aided Manufacturing System: a Case Report. J Endod. 2018;44(5):875–9.

    Article  PubMed  Google Scholar 

  20. Tsotsis P, Dunlap C, Scott R, Arias A, Peters OA. A survey of current trends in root canal treatment: access cavity design and cleaning and shaping practices. Aust Endod J. 2021;47(1):27–33.

    Article  PubMed  Google Scholar 

  21. Moore B, Verdelis K, Kishen A, Dao T, Friedman S. Impacts of contracted endodontic cavities on instrumentation efficacy and biomechanical responses in Maxillary Molars. J Endod. 2016;42(12):1779–83.

    Article  PubMed  Google Scholar 

  22. Marchesan MA, James CM, Lloyd A, Morrow BR, Garcia-Godoy F. Effect of access design on intracoronal bleaching of endodontically treated teeth: an ex vivo study. J Esthet Restor Dent. 2018;30(2):E61–7.

    Article  PubMed  Google Scholar 

  23. Neelakantan P, Khan K, Hei Ng GP, Yip CY, Zhang C, Pan Cheung GS. Does the orifice-directed dentin conservation Access Design Debride Pulp Chamber and Mesial Root Canal Systems of Mandibular Molars similar to a traditional Access. Design? J Endod. 2018;44(2):274–9.

    Article  PubMed  Google Scholar 

  24. Plotino G, Grande NM, Isufi A, Ioppolo P, Pedulla E, Bedini R, Gambarini G, Testarelli L. Fracture strength of endodontically treated teeth with different Access cavity designs. J Endod. 2017;43(6):995–1000.

    Article  PubMed  Google Scholar 

  25. Santosh SS, Ballal S, Natanasabapathy V. Influence of minimally invasive Access cavity designs on the fracture resistance of endodontically treated mandibular Molars subjected to Thermocycling and dynamic loading. J Endod. 2021;47(9):1496–500.

    Article  PubMed  Google Scholar 

  26. Madani ZS, Mehraban N, Moudi E, Bijani A. Root and Canal morphology of Mandibular Molars in a selected iranian Population using Cone-Beam Computed Tomography. Iran Endod J. 2017;12(2):143–8.

    PubMed  PubMed Central  Google Scholar 

  27. Zadik Y, Sandler V, Bechor R, Salehrabi R. Analysis of factors related to extraction of endodontically treated teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106(5):e31–35.

    Article  PubMed  Google Scholar 

  28. Berman LHHK. Cohen’s pathways of the pulp. 12th ed. edn. St Louis: Elsevier Health Sciences; 2020.

    Google Scholar 

  29. Fu Y, Zhang L, Gao Y, Huang D. A comparison of volume of tissue removed and biomechanical analysis of different Access cavity designs in 2-rooted Mandibular First Molars: a multisample 3-dimensional finite element analysis. J Endod. 2022;48(3):362–9.

    Article  PubMed  Google Scholar 

  30. Silva E, Rover G, Belladonna FG, De-Deus G, da Silveira Teixeira C, da Silva Fidalgo TK. Impact of contracted endodontic cavities on fracture resistance of endodontically treated teeth: a systematic review of in vitro studies. Clin Oral Investig. 2018;22(1):109–18.

    Article  PubMed  Google Scholar 

  31. Nayak A, Jain PK, Kankar PK, Jain N. Computer-aided design-based guided endodontic: a novel approach for root canal access cavity preparation. Proc Inst Mech Eng H. 2018;232(8):787–95.

    Article  PubMed  Google Scholar 

  32. Ozyurek T, Ulker O, Demiryurek EO, Yilmaz F. The Effects of Endodontic Access Cavity Preparation Design on the fracture strength of endodontically treated Teeth: traditional Versus Conservative Preparation. J Endod. 2018;44(5):800–5.

    Article  PubMed  Google Scholar 

  33. Chlup ZŽR, Kania J, Přibyl M. Fracture behaviour of teeth with conventional and mini-invasive access cavity designs. J Eur Ceram Soc. 2017;37(14):4423–9.

    Article  Google Scholar 

  34. Sabeti M, Kazem M, Dianat O, Bahrololumi N, Beglou A, Rahimipour K, Dehnavi F. Impact of Access Cavity Design and Root Canal Taper on Fracture Resistance of Endodontically treated Teeth: an Ex vivo investigation. J Endod. 2018;44(9):1402–6.

    Article  PubMed  Google Scholar 

  35. Zehnder MS, Connert T, Weiger R, Krastl G, Kuhl S. Guided endodontics: accuracy of a novel method for guided access cavity preparation and root canal location. Int Endod J. 2016;49(10):966–72.

    Article  PubMed  Google Scholar 

  36. Silva E, Lima CO, Barbosa AFA, Augusto CM, Souza EM, Lopes RT, De-Deus G, Versiani MA. Preserving dentine in minimally invasive access cavities does not strength fracture resistance of restored mandibular molars. Int Endod J. 2021;54(6):966–74.

    Article  PubMed  Google Scholar 

  37. Chan MYC, Cheung V, Lee AHC, Zhang C. A literature review of minimally invasive Endodontic Access Cavities - Past, Present and Future. Eur Endod J. 2022;7(1):1–10.

    PubMed  Google Scholar 

  38. Katona TR, Eckert GJ. The mechanics of dental occlusion and disclusion. Clin Biomech (Bristol Avon). 2017;50:84–91.

    Article  PubMed  Google Scholar 

  39. Ausiello P, Ciaramella S, Fabianelli A, Gloria A, Martorelli M, Lanzotti A, Watts DC. Mechanical behavior of bulk direct composite versus block composite and lithium disilicate indirect class II restorations by CAD-FEM modeling. Dent Mater. 2017;33(6):690–701.

    Article  PubMed  Google Scholar 

  40. Correia AMO, Tribst JPM, Matos FS, Platt JA, Caneppele TMF, Borges ALS. Polymerization shrinkage stresses in different restorative techniques for non-carious cervical lesions. J Dent. 2018;76:68–74.

    Article  PubMed  Google Scholar 

  41. Eskitascioglu G, Belli S, Kalkan M. Evaluation of two post core systems using two different methods (fracture strength test and a finite elemental stress analysis). J Endod. 2002;28(9):629–33.

    Article  PubMed  Google Scholar 

Download references

Acknowledgements

Not applicable.

Funding

This work was supported by the Science and Technology Projects of Shannxi Province (No. 2019ZDLSF01-08), the Key Research and Development Program of Shaanxi Province (No. 2021KW-61), the New Technology and New Business Stomatological Hospital of the Fourth Military Medical University in 2020 (No. LX2020-318). The authors deny any conflicts of interest related to this study.

Author information

Author notes

  1. Xiao Wang and Dan Wang are co-first authors to this article.

    Xiao Wang, Dan Wang contributed equally to this work.

Authors and Affiliations

  1. Department of Endodontics, School of Stomatology, State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Clinical Research Center for Oral Diseases, The Fourth Military Medical University, 710032, Xi’an, China

    Xiao Wang, Dan Wang, Yi-rong Wang, Xiao-gang Cheng, Long-xing Ni, Wei Wang & Yu Tian

Authors
  1. Xiao Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Dan Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Yi-rong Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Xiao-gang Cheng
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Long-xing Ni
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Wei Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Yu Tian
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Xiao Wang and Dan Wang performed the experiment, analyzed the data and wrote the manuscript. Yi-rong Wang contributed significantly to the analysis and manuscript preparation. Xiao-gang Cheng and Long-xing Ni participated in the design of the MIE cavity and establishment of the three-dimensional finite element model; Yu Tian and Wei Wang were the main supervisor and initiator of this study. All authors reviewed, revised, and finalized the paper.

Corresponding authors

Correspondence to Wei Wang or Yu Tian.

Ethics declarations

Competing interests

The authors declare that they have no competing interests.

Ethics approval and consent to participate

All procedures performed in this study, were carried out in accordance with relevant guidelines and regulations of Helsinki Declarations. All the experimental protocols were approved by the ethics committee of the School of Stomatology of the fourth Military Medical University (IRB-REV-2020044). Teeth extracted for therapeutic reasons unrelated to the study were collected, with prior informed consent from healthy individuals who were seeking dental care at the Department of Endodontics, School of Stomatology, The Fourth Military Medical University.

Consent for publication

Not applicable.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wang, X., Wang, D., Wang, Yr. et al. Effect of access cavities on the biomechanics of mandibular molars: a finite element analysis. BMC Oral Health 23, 196 (2023). https://doi.org/10.1186/s12903-023-02878-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s12903-023-02878-3

Keywords

BMC Oral Health

ISSN: 1472-6831

Contact us