Search Article 
Advanced search 
Official publication of the American Biodontics Society and the Center for Research and Education in Technology
Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Contacts Login 

 Table of Contents  
Year : 2019  |  Volume : 10  |  Issue : 1  |  Page : 9-13

Effect of Furcation Perforation Size on Fracture Resistance of Mandibular First Molar

1 Department of Prosthodontics, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
2 Department of Endodontics, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran

Date of Web Publication18-Jun-2019

Correspondence Address:
Roohollah Sharifi
Department of Endodontics, Shariati street, Kemanshah province, Kermanshah
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/denthyp.denthyp_77_18

Rights and Permissions

Introduction: Which were weakening furcation area can reduce tooth strength against fracture. The present study assessed fracture resistance in the mandibular first molars perforated at furcation area and sealed with mineral trioxide aggregate (MTA). This study was aimed to investigate the effect of furcation perforation size on fracture resistance in first mandibular molar teeth. Material and Methods: The cervical region of 50 mandibular first molars were cut at cenentum enamel junction level. After root preparation and obturation, the samples were randomly classified into five groups: group 1:1 mm perforation, reconstructed with MTA; group 2:1 mm perforation, without repair, with wax filling; group 3:2 mm perforation, reconstructed with MTA; group 4:2 mm perforation, without repair, with wax filling; and group 5: without perforation. The compressive force breaking each sample was recorded. Data were subjected to SPSS-20 software to analyze by Kolmogorov–Smirnov test, two-way ANOVA, and independent samples t-test. Results: Furcation perforation and MTA had no significant effect on the force at the break point; no significant difference between 1 and 2 mm perforations either MTA restored or wax filled was registered. No significant difference in mean force at the break point between groups with or without perforation was observed. Conclusions: One and 2 mm furcation perforation does not reduce the fracture resistance. MTA in 1 or 2 mm perforations does not increase the fracture resistance.

Keywords: Furcation perforation, fracture resistance, MTA

How to cite this article:
Jamshidy L, Amirkhani Z, Sharifi R. Effect of Furcation Perforation Size on Fracture Resistance of Mandibular First Molar. Dent Hypotheses 2019;10:9-13

How to cite this URL:
Jamshidy L, Amirkhani Z, Sharifi R. Effect of Furcation Perforation Size on Fracture Resistance of Mandibular First Molar. Dent Hypotheses [serial online] 2019 [cited 2022 May 25];10:9-13. Available from:

  Introduction Top

Root canal perforation is defined as a communication between the root canal system and the surrounding periodontal tissues.[1] This communication can be caused by various reasons such as caries, resorption, or iatrogenic factors.[2] It has different prognoses depending on the location and size of perforation.[3] Perforation causes mechanical weakening of the root, direct impairment of the root structure, and periodontal trauma. It also creates a potential route for microorganisms to enter the root canal.[4] Furcation perforation has a higher risk for the loss of periodontal attachment and bone resorption due to closeness to gingival sulcus.[5],[6],[7] An ideal restorative material for perforation must provide an adequate sealing, be biocompatible, have stable dimensions, be insoluble and radiopaque, and be easily placed in the root canal.[8],[9] For example, the main compounds of mineral trioxide aggregate (MTA) that functions as a candidate for closing the communication between root canal and periodontal tissues[10],[11] include tricalcium silicate, tricalcium aluminate, dicalcium silicate, calcium sulfate dehydrate, and bismuth oxide; its pH after hardening is 12.5, which is the same as that of calcium hydroxide. Exclusive properties like high strength at the presence of humidity,[12] appropriate biocompatibility,[9] reduction of microleakage and bacterial penetration, low toxicity, induction of cement formation, and increased survival of treatment are some other benefits of this material.[10],[11],[12],[13],[14] The furcation area is considered as a strong region owing to being located in the connection center of two or three roots. Therefore, any weakening of this area, including furcation perforation, can exert a remarkable impact on the reduction of tooth strength against fracture during function.[15],[16] It has been shown that MTA has a weakening effect on dentin probably due to the fracture of structural proteins owing to their alkaline properties.[17] In clinical applications such as furcation perforation when MTA is under the influence of functional force, its strength can be a significant factor.[18]

This study aimed to investigate the effect of furcation perforation on the fracture strength of mandibular first molars. Our results provide clinical criteria for the clinicians to anticipate the reduced resistance against fracture.

  Materials and Methods Top

Fifty mandibular first molars were considered (10 teeth in five group)

α = 0.05, and 1- β = 90% (power) [19]

The samples were randomly chosen through convenience sampling. Examination of all the teeth using a stereomicroscope (SZM-2, OPTIKA, Ponteranica, Italy) at 4× magnification confirmed that all the teeth have separate tools, no caries and previous restoration, and were without crack and fracture at furcation area. Immersing the samples in 5.25% sodium hypochlorite for 1 h removed the soft tissue and debridements; then they were kept in 0.9% physiologic serum at room temperature.[20]

At the next stage, access cavity was prepared for each tooth, and the cervical margin at CEJ was cut perpendicular to dental longitudinal axis by a diamond bur (Diamond discs 22 mm, Zogear, Shanghai, China) under coolant.[21] The samples were prepared by manual files no. 8, no. 10, and no. 15 (VDW-dental, München, Germany). Then, the teeth were cleaned by Mtwo rotary file (VDW-dental, München, Germany) and files no. 15 (5% taper), no. 2 (6% taper), and no. 52 (6% taper). The samples were filled with gutta-percha (Gapadent, TianJin, P.R. China), and the sealer (AH26, silverfree, Dentsply, Detrey, Germany) was obturated by lateral obturation method. Using a carbide rotary bur, two perforations, one with 1 mm diameter (Teeskavan, Iran, 012.801) and other with 2 mm diameter (Teeskavan, Iran, 016.801), were created in the midpoint of the mesial and distal furcations perpendicular to the longitudinal axis of the teeth in groups 1 to 4. The area under the furcation between the mesial and distal roots was sealed with acryl. Then, the tooth surroundings were covered with a thin layer of 1.5 to 2-mm-thick wax and fixed in 20 × 20 × 25 acrylic blocks parallel to the longitudinal axis,[22] so that a distance of 2 mm was maintained between the CEJ and resin block surface.[23]

The samples were randomly divided into five groups (each group with 10 samples):
  • Group 1. Teeth with 1 mm perforation and repaired with MTA
  • Group 2. Teeth with 1 mm perforation without repair
  • Group 3. Teeth with 2 mm perforation and repaired with MTA
  • Group 4. Teeth with 2 mm perforation without repair
  • Group 5. Teeth without perforation

According to Salehimehr et al.,[24] the perforations at groups 1 and 3 were repaired with MTA Angelus (MTA ANGELUS, Londrina, PR, Brazil), covered with wet cotton, and dressed with Cavit (Cavisol, Golchadent, Tehran, Iran). The perforations of groups 2 and 4 were filled with wax and dressed with Cavit. The access cavity of group 5 was filled with Cavit up to the CEJ surface. After preparation, the samples were kept in normal saline at room temperature.[25] After 2 months, they were placed in a Universal Testing Machine (STM-20, Santam, Iran) under a compressive force of 1 mm/min.[26] The vertical force was applied by a cylindrical stainless steel bar with a circular cross-section and 10 mm diameter. The cross-section of the bar covered the access cavity surroundings at the cervical margin, and force was consistently applied by the machine until fracture occurred. The force required for the fracture of each sample was recorded in Newton and the obtained values were subjected to statistical analysis.

Data were analyzed by SPSS-20 software (SPSS Inc., Chicago, IL, USA) using descriptive and inferential statistics. For inferential statisics, normality of data was determined by Kolmogorov–Smirnov test. Given the normality of the data, two-way ANOVA was run to analyze the effect of MTA and furcation perforation on the amount of force. Also, independent samples t-test was used for pair comparisons. P < 0.05 was considered significant.

  Results Top

The mean thickness of the cross-section was 73.1 mm in group 1, 72.8 mm in group 2, 72.9 mm in group 3, 82.8 mm in group 4, and 69.5 mm in group 5. The mean length of the samples was 14.9 mm in group 1, 15.3 mm in group 2, 14.3 mm in group 3, 15.3 mm in group 4, and 14.7 mm in group 5. The mean force at the break and peak points in the groups followed a normal distribution (P > 0.6).

The highest mean ± standard error fracture force (2814.21 ± 21N) was found for group 5 (without furcation perforation), and the lowest one (2048.48 ± 1113.23N) was reported for group 4 (2 mm perforation filled with wax). The mean ± standard deviation (SD) fracture forces of the groups 1, 2, and 3 were 2426.11 ± 1214.83N, 2233.34 ± 1252.05N, and 2236.19 ± 1102.3N, respectively [Table 1].
Table 1 Mean and standard deviation of fracture force (N) at the break point for MTA and furcation perforation

Click here to view

The findings showed that furcation perforation and MTA had no significant effect on the fracture force at break point (two-way ANOVA, P > 0.05).

The highest mean ± SD peak force (2858.87 ± 2225.71N) before fracture was observed in group 5 and the lowest level (2060.83 ± 1129.98N) was found in group 4. The mean ± SD peak forces of the groups 1, 2, and 3 were 2464.86 ± 1271.74N, 2244.53 ± 1256.44N, and 2244.82 ± 1103.44N, respectively [Table 2].
Table 2 Mean and standard deviation of fracture force (N) at peak point for MTA and furcation perforation

Click here to view

The mean forces (N) at break point with perforation (2236.03) and without perforation (2814.21) are presented in [Table 3]. No significant difference was between the mean forces at break point with and without perforation (independent sample t-test, P > 0.05).
Table 3 Comparison of the amount of fracture force at break point with and without perforation

Click here to view

The mean forces (N) at peak point with perforation (2253.76) and without perforation (2858.87) are shown in [Table 4], indicating no significant difference between the mean forces at peak point with and without perforation (independent sample t-test, P > 0.05).
Table 4 Comparison of the amount of force at peak point with and without perforation

Click here to view

  Discussion Top

Furcation area is a significant site involved in the strength of tooth, and furcation perforation plays an important role in resistance against fracture during function.[27],[28],[29],[30],[31] The restorative materials used for sealing the furcation area have to fulfill the functional requirements of the teeth, including mechanical forces applied on the perforation area.[21],[30] Accordingly, the present study was designed to compare the amount of force required for fracturing perforated and imperforated teeth at furcation area. Although the healthy teeth needed approximately 600N more fracture force than the perforated teeth,[13] no significant difference was observed between the perforated and unperforated teeth in mean forces at break point. The perforation size is among the factors that affects successful perforation repairment. Small perforations promote the direct and immediate restorations,[32] reducing the chance of periodontal failure and epithelial proliferation at perforation area.[33] In a situation that the restorative material contacts largely with periodontium, the perforation prognosis becomes unclear because of probable inflammatory stimulation that can propagate into the adjacent tissues. Also, marginal adaptation is reduced with increase of the defective area.[34] The effect of furcation perforation size on the efficacy of restorative material is still undetermined. Some studies argued that tooth size in relation to perforation size directly affects the prognosis,[31],[33],[35] whereas some others reported no association between the two variables.[36]

Analysis of dental materials has shown that the materials with same elasticity as dentin can reinforce the weak roots.[37] On the contrary, the samples obturated with gutta-percha, MTA, and calcium phosphate have a higher fracture strength than unobturated samples.[38] Although MTA is the material of choice for furcation perforation repairment,[14] some studies have indicated that MTA weakens the dentin.[17]

The studies conducted on the effect of MTA on the fracture strength have reported contradictory results. Bortoluzzi et al.[39] showed that use of MTA and metal post significantly increased fracture resistant in bovine immature teeth. Compared to our study, the difference may be attributable to simultaneous use of metal post and MTA, obturation of root canal length with MTA (unlike our study in which only furcation perforation was filled with MTA), and cutting the 12-mm apical root as close to the CEJ. However, the root was untouched up to apical region in our study. Milani et al.[40] reported a higher fracture strength in MTA obturation group. Comparatively, using immature maxillary incisors and a different method, in which all the root length was filled with MTA and the root was cut 9 mm lower than CEJ, may be presumptive causes of the difference; the roots were healthy in our study.In the terms of causality of strength change, White et al.[17] argued that the reduction may be related to the structural proteins created by the alkaline properties of restorative materials like MTA. However, Sahebi et al.[41] believed that fracture of structural proteins causes the root strength to decrease.

Our results showed that the fracture strength of the samples with 1 mm perforation in MTA perforation group was about 200N higher than that of 1 mm perforation group obturated with wax. However, furcation perforation and MTA had no significant effect on the force at break point (P > 0.05). Moreover, despite 200N difference in 2-mm perforation groups, there was no significant difference between the MTA group and the wax group (P > 0.05). This insignificant difference might be due to the low sample size, patients’ age, type of occlusion in the teeth once present in the jaw arch, and diet of these samples as type of occlusion and age affect the dentinogenesis and calcification and consequently the tooth strength.[42] Moreover, MTA Angelus did not increase the tooth strength in 1 or 2 mm perforations. As the roots were not cut and root treatment stages and perforation repair were reconstructed similar to the clinical conditions, the strength is probably closer to in vivo conditions.

Gathering healthy first mandibular molar teeth of same forms and sizes was the great challenge of our study. Nonetheless, further studies would be recommended to include a relatively large healthy group with no endodontic treatment. Also, it is needed to assess the variability trend of the fracture resistance at different times in a larger sample size.

The present study leads us to the conclusion that furcation perforation did not decrease the tooth strength and repairing the perforations with MTA Angelus did not increase the tooth strength.

Financial support and sponsorship

The current research was supported and ethically approved by the Research Council of the Kermanshah University of Medical Sciences, Kermanshah, Iran (96361).Conflicts of interest

There are no conflicts of interest.

  References Top

Farzaneh M, Abitbol S, Friedman S. Treatment outcome in endodontics: the Toronto study. Phases I and II: Orthograde retreatment. J Endod 2004;30:627-33.  Back to cited text no. 1
Bargholz C. Perforation repair with mineral trioxide aggregate: a modified matrix concept. Int Endod J 2005;38:59-69.  Back to cited text no. 2
Nazari KM, Aghili H, Rashed AM, Zahedpasha S, Moghadamnia A. A comparative study on sealing ability of mineral trioxide aggregate, calcium enriched cement and bone cement in furcation perforations. Minerva Stomatol 2014;63:203-10.  Back to cited text no. 3
Saed SM, Ashley MP, Darcey J. Root perforations: aetiology, management strategies and outcomes. The hole truth. B, r Dent J 2016;220:171-80.  Back to cited text no. 4
Setzer FC, Boyer KR, Jeppson JR, Karabucak B, Kim S. Long-term prognosis of endodontically treated teeth: a retrospective analysis of preoperative factors in molars. J Endod 2011;37:21-5.  Back to cited text no. 5
Alhavaz A, Jamshidy L. Comparison of the marginal gap of zirconia-fabricated copings generated by CAD/CAM and Copy-Milling methods. Dent Hypo 2015;6:23-6.  Back to cited text no. 6
Jamshidy L, Mozaffari HR, Faraji P, Sharifi R. Accuracy of the one stage and two stage impression technique: a comparative analysis. Int J Dent 2016;2:1-5.  Back to cited text no. 7
Fuss Z, Trope M. Root perforations: classification and treatment choices based on prognostic factors. Dent Traumatol 1996;12:255-64.  Back to cited text no. 8
Holland R, Otoboni Filho JA, de Souza V, Nery MJ, Bernabé PFE, Junior ED. Mineral trioxide aggregate repair of lateral root perforations. J Endod 2001;27:281-4.  Back to cited text no. 9
Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review—part III: clinical applications, drawbacks, and mechanism of action. J Endod 2010;36:400-13.  Back to cited text no. 10
Wälivaara DÅ, Abrahamsson P, Isaksson S, Salata LA, Sennerby L, Dahlin C. Periapical tissue response after use of intermediate restorative material, gutta-percha, reinforced zinc oxide cement, and mineral trioxide aggregate as retrograde root-end filling materials: a histologic study in dogs. J Oral Maxillofac Surg 2012;70:2041-7.  Back to cited text no. 11
Torabinejad M, Higa RK, McKendry DJ, Ford TRP. Dye leakage of four root end filling materials: effects of blood contamination. J Endod 1994;20:159-63.  Back to cited text no. 12
Schmitter M, Schweiger M, Mueller D, Rues S. Effect on in vitro fracture resistance of the technique used to attach lithium disilicate ceramic veneer to zirconia frameworks. Dent Mater 2014;30:122-30.  Back to cited text no. 13
Main C, Mirzayan N, Shabahang S, Torabinejad M. Repair of root perforations using mineral trioxide aggregate: a long-term study. J Endod 2004;30:80-3.  Back to cited text no. 14
Bhat S, Hegde S, Rao A, Mohammed AS. Evaluation of resistance of teeth subjected to fracture after endodontic treatment using different root canal sealers: an in vitro study. J Indian Soc Pedod Prev Dent 2012;30:305-9.  Back to cited text no. 15
[PUBMED]  [Full text]  
Fernandes AS, Dessai GS. Factors affecting the fracture resistance of post-core reconstructed teeth: a review. Int J Prosthodont 2001;14:355-63.  Back to cited text no. 16
White JD, Lacefield WR, Chavers L, Eleazer PD. The effect of three commonly used endodontic materials on the strength and hardness of root dentin. J Endod 2002;28:828-30.  Back to cited text no. 17
Anusavice KJ, Shen C, Rawls HR. Phillips’ Science of Dental Materials. St. Louis, MO: Mosby 2013.  Back to cited text no. 18
Forster A, Sáry T, Braunitzer G, Fráter M. In vitro fracture resistance of endodontically treated premolar teeth restored with a direct layered fiber-reinforced composite post and core. J Adhesion Sci Technol 2017;31:1454-66.  Back to cited text no. 19
Cobankara F, Unlu N, Cetin A, Ozkan H. The effect of different restoration techniques on the fracture resistance of endodontically-treated molars. Oper Dent 2008;33:526-33.  Back to cited text no. 20
Sluyk S, Moon P, Hartwell G. Evaluation of setting properties and retention characteristics of mineral trioxide aggregate when used as a furcation perforation repair material. J Endod 1998;24:768-71.  Back to cited text no. 21
Franco ÉB, do Valle AL, de Almeida ALPF, Rubo JH, Pereira JR. Fracture resistance of endodontically treated teeth restored with glass fiber posts of different lengths. J Prosth Dent 2014;111:30-4.  Back to cited text no. 22
Seow LL, Toh CG, Wilson NH. Strain measurements and fracture resistance of endodontically treated premolars restored with all-ceramic restorations. J Dent 2015;43:126-32.  Back to cited text no. 23
Salehimehr G, Nobahar S, Hosseini-Zijoud SM, Yari S. Comparison of physical & chemical properties of Angelus MTA and new endodontic restorative material. J Appl Pharma Sci 2014;4:105-9.  Back to cited text no. 24
Mortazavi V, Fathi M, Katiraei N, Shahnaseri S, Badrian H, Khalighinejad N. Fracture resistance of structurally compromised and normal endodontically treated teeth restored with different post systems: an in vitro study. Dent Res J 2012;9:185.  Back to cited text no. 25
Alhavaz A, Jamshidy L, Baghery MA, Ramezani R, Ahangar Darabi M. Comparision of fracture toughness of zirconia fabricated copings which is generated in two methods: CAD/CAM and copy milling methods. J Basic Appl Sci Res 2013;3:222-7.  Back to cited text no. 26
Adl A, Sobhnamayan F, Kazemi O. Comparison of push-out bond strength of mineral trioxide aggregate and calcium enriched mixture cement as root end filling materials. Dent Res J 2014;11:564-7.  Back to cited text no. 27
Jeevani E, Jayaprakash T, Bolla N, Vemuri S, Sunil CR, Kalluru RS. Evaluation of sealing ability of MM-MTA, endosequence, and biodentine as furcation repair materials: UV spectrophotometric analysis. J Conserv Dent 2014;17:340-3.  Back to cited text no. 28
[PUBMED]  [Full text]  
Yildirim G, Dalci K. Treatment of lateral root perforation with mineral trioxide aggregate: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endodontol 2006;102:e55–8.  Back to cited text no. 29
VanderWeele RA, Schwartz SA, Beeson TJ. Effect of blood contamination on retention characteristics of MTA when mixed with different liquids. J Endod 2006;32:421-4.  Back to cited text no. 30
Alhadainy HA, Himel VT, Lee WB, Elbaghdady YM. Use of a hydroxylapatite-based material and calcium sulfate as artificial floors to repair furcation perforations. Oral Surg Oral Med Oral Pathol Oral Radiol Endodontol 1998;86:723-9.  Back to cited text no. 31
Parveen S, Hossain M, Sheikh MA, Abdin MJ. Repair of iatrogenic furcation perforation with glass ionomer cement. Bangabandhu Sheikh Mujib Med Univ J 2018;11:70-4.  Back to cited text no. 32
Mente J, Leo M, Panagidis D, Saure D, Pfefferle T. Treatment outcome of mineral trioxide aggregate: repair of root perforations—long-term results. J Endod 2014;40:790-6.  Back to cited text no. 33
Moncada G, Fernández E, Martin J, Arancibia C, Mjör I, Gordan VV. Increasing the longevity of restorations by minimal intervention: a two-year clinical trial. Oper Dent 2008;33:258-64.  Back to cited text no. 34
Adamo H, Buruiana R, Schertzer L, Boylan R. A comparison of MTA, Super‐EBA, composite and amalgam as root‐end filling materials using a bacterial microleakage model. Int Endod J 1999;32:197-203.  Back to cited text no. 35
Salman M, Quinn F, Dermody J, Hussey D, Claffey N. Histological evaluation of repair using a bioresorbable membrane beneath a resin-modified glass ionomer after mechanical furcation perforation in dogs’ teeth. J Endod 1999;25:181-6.  Back to cited text no. 36
Li L-L, Wang Z-Y, Bai Z-C, Mao Y, Gao B, Xin H-T et al. Three-dimensional finite element analysis of weakened roots restored with different cements in combination with titanium alloy posts. Chin Med J 2006;119:305-11.  Back to cited text no. 37
Cauwels RG, Pieters IY, Martens LC, Verbeeck RM. Fracture resistance and reinforcement of immature roots with gutta percha, mineral trioxide aggregate and calcium phosphate bone cement: a standardized in vitro model. Dent Traumatol 2010;26:137-42.  Back to cited text no. 38
Bortoluzzi E, Souza E, Reis J, Esberard R, Tanomaru‐Filho M. Fracture strength of bovine incisors after intra‐radicular treatment with MTA in an experimental immature tooth model. Int Endod J 2007;40:684-91.  Back to cited text no. 39
Milani AS, Rahimi S, Borna Z, Jafarabadi MA, Bahari M, Deljavan AS. Fracture resistance of immature teeth filled with mineral trioxide aggregate or calcium-enriched mixture cement: an ex vivo study. Dent Res J 2012;9:299-304.  Back to cited text no. 40
Sahebi S, Nabavizadeh M, Dolatkhah V, Jamshidi D. Short term effect of calcium hydroxide, mineral trioxide aggregate and calcium-enriched mixture cement on the strength of bovine root dentin. Iran Endod J 2012;7:68-73.  Back to cited text no. 41
Morse DR. Age-related changes of the dental pulp complex and their relationship to systemic aging. Oral Surg Oral Med Oral Pathol 1991;72:721-45.  Back to cited text no. 42


  [Table 1], [Table 2], [Table 3], [Table 4]

This article has been cited by
1 Clinical Properties and Efficacy of MTA VS Biodentine VS GIC in Repairing Root Perforations
Hatem Mansoor Abualhasan, Badr Soliman Alhussain
Archives Of Pharmacy Practice. 2022; 13(1): 53
[Pubmed] | [DOI]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

  In this article
Materials and Me...
Article Tables

 Article Access Statistics
    PDF Downloaded404    
    Comments [Add]    
    Cited by others 1    

Recommend this journal