|Year : 2017 | Volume
| Issue : 2 | Page : 96-103
Fracture resistance of rehabilitated flared root canals with anatomically adjustable fiber post
Talat M Beltagy
Department of Pedodontics, Faculty of Dentistry, Kafr El-Sheikh University, Kafr El-Sheikh, Egypt
|Date of Submission||23-Mar-2017|
|Date of Acceptance||03-May-2017|
|Date of Web Publication||30-May-2017|
Talat M Beltagy
Department of Pedodontics, Faculty of Dentistry, Kafr El-Sheikh University, El-Geish Street, Kafr El-Sheikh 33511
Source of Support: None, Conflict of Interest: None
This study aimed to evaluate the fracture resistance of the rehabilitated overflared canals with anatomically adjustable everStick post.
Patients and methods:
Thirty extracted human maxillary central incisors with close similarity were selected. The specimens were coronally horizontally sectioned, endodontically treated and randomly divided into three groups (n = 10). Twenty of specimens were overflared, leaving 5 mm gutta percha seal. Group I: overflared specimens were rehabilitated with everStick post. Group II: overflared specimens were rehabilitated with EasyPost/composite. Group III (control group): specimens had normal unflared canals and were restored with EasyPost/core system. Composite resin was used to complete the core building-up for all groups. Fracture resistance of all specimens was measured using Instron testing machine. Statistical analyses were submitted to one-way analysis of variance and a post-hoc test. The level of significance was adopted atP value less than 0.05.
The results showed that the control group recorded the highest fracture resistance values, followed by everStick and EasyPost/composite group and the difference was significant among them (P < 0.05). Mode of failures showed 76.7% of specimens exhibited a repairable mode of failure while 23.3% displayed nonrepairable mode. Root fracture was recorded in one specimen of everStick group and in two specimens of EasyPost/composite group, however, four specimens in the control group displayed EasyPost fracture.
The use of anatomically adjustable everStick post in rehabilitation of compromised teeth with flared canals seems to be significantly effective, promising in the improvement of fracture resistance, and increase the favorable mode of failure.
Keywords: fiber post, fracture resistance, rehabilitated flared root canals
|How to cite this article:|
Beltagy TM. Fracture resistance of rehabilitated flared root canals with anatomically adjustable fiber post. Tanta Dent J 2017;14:96-103
|How to cite this URL:|
Beltagy TM. Fracture resistance of rehabilitated flared root canals with anatomically adjustable fiber post. Tanta Dent J [serial online] 2017 [cited 2017 Dec 16];14:96-103. Available from: http://www.tmj.eg.net/text.asp?2017/14/2/96/207303
| Introduction|| |
The restoration of endodontically treated teeth with extensive coronal destruction is still a great challenge to the dentist. These weekend teeth are more prone to fracture, especially at the cervical third. Therefore; there is a need to rehabilitate these teeth with techniques that will not compromise the integrity of their remaining thin-walled roots and the use of dowel-and-core systems to retain full and final crown restorations seems mandatory ,,,.
Custom or prefabricated metal posts were widely used and considered the gold standard for decades due to their superior mechanical properties. Conversely, metal posts showed several disadvantages as the high incidence of catastrophic root fracture , corrosion, inflammatory reaction, discoloration and shadowing on the periodontium in the anterior esthetic region ,. Also, they need temporization that added time-consuming and increases the incidence of the root canal contamination .
The restoration of compromised nonvital teeth with metal-free, biocompatible, and homogenous materials with improved their optical and physical properties have become a major objective in dentistry . The prefabricated fiber posts with favorable biomechanical properties were developed to overcome the disadvantages of the metallic posts. Their modulus of elasticity and dentin-like rigidity are almost similar to dentin that significantly reduces the incidence of root fracture and displayed long-term durability . They are less expensive, easier and faster to fabricate, and they can be simply and quickly removed from the root canals in the case of retrievability ,. Furthermore, the adhesive and micromechanical bonding characteristics of fiber posts to the resin cement, dentin, and composite core give a natural hue improving the esthetics without much compromising the material strength ,.
However, the fiber posts require shaping of the canal walls to fit the dowels, leading to dentin loss and increase the incidence of root cracks and fractures . The use of a single fiber post in overflared canals may lead to poor adaptation, core instability, increase in cement thickness, and reduce the bonding and mechanical properties ,.
The use of accessory fiber posts still not significantly decrease the cement thickness, moreover they increase the interfaces between the reinforcing system and the dentin that compromise the adhesive effect of the technique ,.
Recently, the problems with the overflared canal reinforcement can be overcomed by a newly released novel, direct and anatomically adjustable glass–fiber reinforced everStick post. This post is a minimally invasive, soft, flexible, polymer of polymethyl methacrylate, and resin impregnated bisphenol A-glycidyl methacrylate uncured glass–fiber post. It can be customized and closely adapted to the morphology of the root canal giving the best choice for flared, oval and curved canal. Their flexural strength and elasticity are nearly similar to the dentin, thus an equal distribution of occlusal stresses along the root surface will evenly minimize the risk of root fracture .
Therefore, this study aimed to evaluate the fracture resistance of rehabilitated flared root canals using anatomically adjustable glass–fiber reinforced everStick post. The null hypothesis was that there are no differences among the fracture resistance of the different reinforcing systems.
| Materials and Methods|| |
Fracture resistance of rehabilitated flared canals
A total of 30 extracted human upper permanent central incisors for periodontal reasons with nearly similar sizes and shapes with a close range of age (40–50 years) were selected [Figure 1]a. Teeth with caries, microfractures, cracks, previous restorations, and curved roots were discarded. All patients are informed about the purpose of the study and using of their extracted teeth according to Ethics Committee of Faculty of Dentistry, Tanta University. Informed consents from the patients were taken for the use of their extracted teeth in this in-vitro study. Immediately after the extraction, the teeth were rinsed and sterilized using 2% formaldehyde solution at room temperature, and pH 7.0 for 30 days. The calculus and soft tissues were removed mechanically and the teeth were cleaned using a rubber cup with pumice mounted on low-speed handpiece for 15 s.
|Figure 1: Nearly similar sizes and shapes of extracted teeth (a).The crowns of specimens were sectioned perpendicular to the long axis of roots (b). Digital caliper was used to measure the specimen root length and dentine thickness (c and d). Specimens represent the three groups (e).|
Click here to view
Preparation of specimens
The anatomical crowns were sectioned perpendicular to the long axis of roots at 1 mm coronal to the cementoenamel junction of the proximal aspects using a diamond tip with ample water cooling, leaving 17 ± 1 mm root length [Figure 1]b and [Figure 1]c. Root canals of all specimens were instrumented according to the instruction of International Standardization Organization using K-file #55 apically. After irrigation with 2.5% sodium hypochlorite and 0.9% saline alternatively, the canals were dried and obturated with gutta-percha (Diadent, Korea) and eugenol-free root canal sealer (AH26; Dentsply Maillefer, Switzerland) using lateral condensation technique. The specimens were stored at 100% relative humidity and 37°C for 24 h.
Large tapered postspaces were uniformly prepared in 20 of the 30 specimens to a depth of 12 mm from the sectioned surface using a silicone stopper as a guide and leaving 5 mm intact apical seal. The post spaces of 20 specimens were overflared using different sizes of large tapered tungsten laboratory carbide burs (Zhejiang, China) that were mounted on special drilling machine under copious water cooling leaving about 1.5 mm dentin thickness labially as confirmed by a digital caliper (IOS, USA) [Figure 1]d The specimens of the three groups are represented in [Figure 1]e.
The smear layer was removed using 5 ml of 17% EDTA followed by 10 ml of sodium hypochlorite. The specimens were further irrigated with distilled water, dried, and then randomly divided according to the rehabilitating system used into two groups (n = 10). Group III: 10 specimens with normal unflared canals were selected and prepared.
Group I (everStick group)
The dentinal wall of the overflared canal was etched with 37% phosphoric acid gel and bonded with an adhesive (Adper Single Bond Plus; 3M ESPE, USA) according to the manufacturer's recommendations. A premeasured length of the soft unpolymerized everStick (GC Europe NV, Finland) post 1.5 mm diameter with the silicone strip were cut together using a sharp scissor, leaving 4 mm of the post extending above the sectioned root surface. The post was inserted inside the root canal by a tweezer moisten with light-curing enamel bonding agent StickRESIN (GC Europe NV) shaped by condensing to the prepared post space, and initially light-cured for 20 s using Demetron LC unit (Kerr, USA). The polymerized post was then removed from the canal and further light-cured from all sides for 40 s.
Additional posts 0.9 and/or 0.5 mm sizes were gently pressed to closely fit the main post using an endodontic plugger. The post surface was activated using a thin layer of StickRESIN, light protected for 3–5 min using a light shield, and then light-cured for 10 s inside the root canal.
The post was removed gently from the canal and light protected before cementation. Self-adhesive dual-cure resin cement (RelyX Unicem; 3M ESPE) was applied according to manufacturer's instruction, then the post was immediately inserted slowly inside the canal using locking tweezer. The excess cement was removed using a small brush and the post was light-cured for 40 s [Figure 2].
Group II (EasyPost/composite group)
The etching and adhesive applications to the root dentinal surfaces of the overflared specimens were carried out as mentioned in group I. Nanofilled composite resin (Filtek Z350 XT; 3M ESPE) was injected into the root canal space using a delivery tip loaded in a compule tips gun. A Luminex vasolinized smooth light transilluminating plastic post #6 (Dentatus, USA) was centrally seated into the filled canal up to the apical root filling [Figure 3]a,[Figure 3]b. The composite was light-cured for 40 s and for additional 20 s following the Luminex post removal.
|Figure 3: A Luminex smooth post #6 used for intracanal polymerization (a and b). EasyPost #4 was used to complete the rehabilitation technique (c). EasyPost was cut leaving 4mm above the sectioned specimen (d).|
Click here to view
EasyPost #4 (Dentsply Maillefer) was prepared according to manufacturer's instruction for insertion into the canal space [Figure 3]c. All EasyPosts were cut outside at a distance of 4 mm from the roots sectioned surface using water cooled diamond bur to retain core build-up [Figure 3]d.
The post was cemented with RelyX Unicem, the excess cement was removed with a small brush, and then light-cured for 20 s.
Group III (control group)
The specimens without flaring were used in this group. After conventional root canals obturation, gutta percha filling were removed by Gates Glidden drills (Dentsply Maillefer) leaving 5 mm apical seal. The canal spaces were prepared using dentatus classic reamers to receive EasyPosts #4. The etching, adhesive application, and post cementation were carried out as mentioned before.
Standard polyester crown forms (Anger GA, Poland) 6 mm in height that snugly fit the neck of all specimens were used to complete the core build-up from Filtek Z350 XT [Figure 4].
|Figure 4: A standard polyester crown form was used for core building-up (a and b).|
Click here to view
All roots were individually checked by a radiograph [Figure 5] and were embedded vertically in a metallic mould filled with auto-cure acrylic resin (Acrostone, UK) leaving 3 mm of the natural root was exposed. The specimens were coded and thermocycled in distilled water for 500 cycles at 5–55°C with dwell time 30 s and transfer time 5 s, then stored at 100% relative humidity at 37°C for 72 h before testing . The coded specimens were randomly chosen and subjected to fracture resistance test.
|Figure 5: Pre and post rehabilitation radiographs of normal canal/easyPost group (a and b). Labial and proximal view of pre-rehabilitation radiograph of an overflared specimen (c and d). Post- rehabilitation radiographs of easyPost/composite group and everStick group (e and f) respectively.|
Click here to view
Fracture resistance (failure load) testing
All coded specimens were individually mounted in a 45° angulation custom-made jig that secured to the lower fixed compartment of Instron testing machine (Bucks HP12 3SY, UK) with a load cell of 5 kN at Faculty of Dentistry, Tanta University. The load was applied using a custom steel rod with round end 4 mm in diameter, placed palatally 3 mm below the incisal edge of the specimen , [Figure 6].
A constantly increasing loading force was applied at a crosshead speed of 2 mm/min until failure occurred due to post displacement, post or core fracture, root fracture, or debonding the cement . The load failure (in N) and the mode of failure were recorded [Figure 7].
The failure mode was observed using a magnifying lens. It was classified into repairable (would allow repair) and nonrepairable . Fractured of the post or the root or both were considered the nonrepairable mode of failure. All data were collected, tabulated, and statistically analysis using SPSS (version 19; IBM, Illinois, Chicago, USA) and submitted to one-way analysis of variance. Least significance test was used as a post hoc test for the significant result for the test of analysis of variance. The level of significant was adopted at P value is less than 0.05.
| Results|| |
The mean fracture resistance of the tested reinforcing systems is presented in [Table 1].
|Table 1: Comparison of mean fracture resistance of the tested reinforcing systems among studied groups (N )|
Click here to view
The results of load failure test revealed that the normal canal/EasyPost group recorded the highest values 388.0 N, followed by everStick group 308.8 N (P < 0.05). EasyPost/composite group displayed the lowest values 254.9 N and the difference was significant among them (P < 0.05).
[Table 2] showed that 23 (76.7%) specimens exhibited a repairable mode of failure while seven (23.3%) specimens showed nonrepairable mode. Root fractures were observed in one specimen of everStick group and in two specimens of EasyPost/composite group, however, four specimens in normal canal/EasyPost group displayed post fractures.
The repairable mode of failure was observed in six specimens of the normal canal/EasyPost group associated with a fracture of core build-up, dislodgment of EasyPost in two specimens of EasyPost/composite group, one specimen showed fracture of reinforcing system with post dislodgment, and five specimens showed a fracture of core build-up. EverStick group recorded dislodgment of two posts while seven specimens were observed with a fracture of core build-up [Figure 5].
| Discussion|| |
Rehabilitation of compromised flared teeth has been a challenge to maintain esthetic, function, and durability of the weakened teeth . Although the clinical study is more realistic, the in-vitro assessment can overcome clinical limitations as individual variations. By measuring the fracture resistance of reinforced compromised teeth, we may have an idea about the load bearing capacity of the reinforcing system and a base for in-vivo studies which are necessary for the cite definitive outcomes .
So, this in-vitro study was conducted to determine the fracture resistance and mode of failure of rehabilitated compromised flared permanent central incisors using the everStick post.
In this study, the natural human extracted teeth were preferred to simulate the clinical situations of rehabilitated teeth . As the permanent maxillary central incisors are more susceptible to traumatic fracture at an early age and therefore they were chosen to simulate the clinical condition .
To standardize the specimens, the teeth of similar shapes, sizes and of close range of age group were selected. According to the International Standardization Organization recommendation; the specimens were stored moist in distilled water throughout the study, as the bonding can adversely be affected by the dehydration of specimen's hard dental tissue, especially dentin ,.
The acrylic resin mould was used in this study as its modulus of elasticity is approximately similar to that of human bone  and the embedded specimens leave 3 mm of root exposed to simulate the level of healthy alveolar bone .
In this study, eugenol-free root canal sealer was used as eugenol interfere with the polymerization of resins, deteriorate the marginal seal, and had a significantly negative influence on bond strength and post retention .
StickRESIN light-cure was used for everStick post surface activation to form secondary interpenetrating polymer network IPN bonding and the post was light protected to prevent the activated resin from premature polymerization by the light .
All posts in this study were cemented with resin cement as it is recommended for post cementation in thin-walled roots due to its potential to increase the fracture resistance of reinforced teeth . It increases the capacity of post adhesion, showed greater toughness and longevity, low solubility, and minimum microfiltration as compared to conventional cement ,.
In the current study, the core foundation was formed using the standard polyester crown to unify standard cores for all specimens. To simulate the aging of intraoral conditions, it was important to expose the specimens to thermocycling and thermal fatigue .
The contact angle of loading force on the specimen can strongly affect fracture resistance. The more parallel the orientation of loading force to the long axis of the specimen, the more the fracture resistance . Therefore, the loading force in this study was applied palatally at an angle of 135° to the horizontal to mimic as possible the clinical class I occlusion in the anterior region ,.
The results of the current study revealed that the fracture resistance and the failure mode were different among the tested groups, thus the null hypothesis is rejected. The results reported that the control group recorded the highest mean fracture resistance values among all groups and the difference was significant, while EasyPost/composite group recorded the lowest resistance and the difference was significant. This finding agrees with the opinion which stated that the fracture resistance of rehabilitated thin-walled roots is proportionally directed to the thickness of the remaining dentinal wall ,.
The everStick group showed high fracture resistance than EasyPost/composite group. This may be attributed to the close elastic modulus of the everStick post to dentin that flexes together under loading force. Also, the dentin-like behavior of the post facilitates better stress distribution and yielding high fracture strength values .
In addition, several factors might influence the mechanical properties of FRC posts as the type of polymer matrix and length, diameter, number, and fiber-orientation of embedded fibers . Thus, the presence of a high molecular weight polymethyl methacrylate chains in the everStick post act as stress-breaker via plasticize the stiffness of highly cross-linked bisphenol A-glycidyl methacrylate matrix, decrease stress concentration at the interface of fiber–matrix during deflection, and absorption of emerging stresses through the matrix .
Also, during manufacture of FRC posts, the rehabilitating effect of unidirectional impregnated fibers can be created. These impregnated fibers are soaked with resin matrix in a prestressed tension that released after curing causing fibers compression which can absorb the tensile stresses under flexural forces . Moreover, these fibers facilitate stress dissipation, supports the fillers of composite layers, and act as a crack stopper ,. The more increase of fibers in the matrix, the more increase of the post resistance to microcracking . The silanized fiber of everStick is another essential method for improving the fiber/matrix interface strength .
The everStick group exhibited 308.8 N, this finding disagrees with those of Kıvanç et al. and Bolay et al. who recorded 938.4 and 705.5 N, respectively, while Maccari et al. reported 136.3 N with the use of glass–fiber reinforced resin post. These conflicting results may be due to variations in methodology, sample sizes, the biochemical composition of human extracted teeth, canal morphology, and physical and chemical properties of the reinforcing materials used in this study .
Ferrario et al. reported that the maximum biting forces in healthy young adults ranging from 75 to 190 N in the anterior region. The minimum fracture resistance values obtained for all tested groups were 230, 285, and 328 N for EasyPost/composite, everStick, and control group respectively exceeding the maximum incisal biting forces.
Different failure patterns were reported in the tested groups of this study; fracture core build-up, fracture EasyPost, root fracture, everStick post displacement, fracture of the reinforcing system with EasyPost displacement, and complete displacement of the reinforcing system.
Post displacement of a specimen was shown in the everStick group. A possible explanation may be related to the low elastic modulus of the post resulting in higher bending under loading stresses, leading to debonding of the cement and complete displacement of the everStick post ,. Also this group showed no post or root fracture, this was probably due to the close similarity between the accepted range of elastic modulus of dentin ,,, GPa , and the everStick post ,,, GPa  resulted in a biomechanical homogeneity unit that dissipating the forces overall the root without root fracture, so, they might act as stresses absorbers ,.
The nonrepairable root fractures observed in EasyPost/composite group may be due to the rigidity of Filtek Z350 XT composite with high micro-hardness and elastic modulus of 30.1 GPa  which will not deform under stresses. This may lead to stress concentration with the development of a slowly growing crack and catastrophic root fracture, especially with thin-walled roots. The more the filler content, the more the elastic modulus and the more the resistance to deformation ,.
Limitations of this study
- The manipulation of the everStick post used in this study was technically sensitive
- It was difficult to collect periodontally affected maxillary permanent central incisors at an early age.
| Conclusion|| |
The use of anatomically adjustable everStick fiber-reinforced composite post in the rehabilitation of compromised teeth with flared canals seems to be effective and promising in the improvement of fracture resistance, and increase the favorable mode of failure.
Further long-term clinical assessment of the everStick post is desirable and recommended to support these in-vitro results.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Michael MC, Husein A, Bakar Z, Sulaimanb E. Fracture resistance of endodontically treated teeth: an in vitro
study. Arch Orofac Sci 2010; 5:36–41.
Helfer R, Melnick S, Schilder H. Determination of the moisture content of vital and pulpless teeth. Oral Surg Oral Med Oral Pathol 1972; 34:661–670.
Goracci C, Sadek FT, Fabianelli A, Tay FR, Ferrari M. Evaluation of the adhesion of fiber posts to intraradicular dentin. Oper Dent 2005; 30:627–635.
Makade CS, Meshram GK, Warhadpande M, Patil PG. A comparative evaluation of fracture resistance of endodontically treated teeth restored with different post core systems-an in vitro
study. J Adv Prosthodont 2011; 3:90–95.
Sirimai S, Riis DN, Morgano SM. An in vitro
study of the fracture resistance and the incidence of vertical root fracture of pulpless teeth restored with post-and-core systems. J Prosthet Dent 1999; 81:262–269.
Anil P, Aparna A. Esthetic rehabilitation of a crown fracture with glass–fibre-reinforced posts: a case report. Int J Sci Res Publ 2012; 2: 2250–3153.
Kim JH, Park SH, Park JW, Jung Y. Influence of post types and sizes on fracture resistance in the immature tooth model. J Korean Acad Conserv Dent 2010; 35:257–267.
Schwartz RS, Jordan R. Restoration of Endodontically treated Teeth: The Endodontist's Perspective, Part 1. Endodontics: Colleagues for Excellence. AAE. 2004:1–6
Braga NM, Souza-Gabriel AE, Messias DC, Rached-Junior FJ, Oliveira CF, Silva RG, et al.
Flexural properties, morphology and bond strength of fiber-reinforced posts: influence of post pretreatment. Braz Dent J 2012; 23:679–685.
Fovet Y, Pourreyron L, Gal JY. Corrosion by galvanic coupling between carbon fiber posts and different alloys. Dent Mater 2000; 16:364–373.
Lide'n C, Norberg K. Nickel on the Swedish market. Follow-up after implementation of the nickel directive. Contact Dermatitis 2005; 52: 29–35.
Akkayan B, Gülmez T. Resistance to fracture of endodontically treated teeth restored with different post systems. J Prosthet Dent 2002; 87:431–437.
Strassler HE, Cloutier PC. A new fiber post for esthetic dentistry. Compend Contin Educ Dent 2003; 24:742–744; 746, 748 passim.
Makarewicz D, Ronnlof AM, Lassila LV, Vallittu PK. Effect of cementation technique of individually formed fiber-reinforced composite post on bond strength and microleakage. Open Dent J 2013; 7:68–75.
D'Arcangelo C, Cinelli M, De Angelis F, D'Amario M. The effect of resin cement film thickness on the pullout strength of a fiber-reinforced post system. J Prosthet Dent 2007; 98:193–198.
Ferrari M, Vichi A, Garcia-Godoy F. Clinical evaluation of fiber-reinforced epoxy resin posts and cast post and cores. Am J Dent 2000; 13:158–168.
Grandini S, Goracci C, Monticelli F, Borracchini A, Ferrari M. SEM evaluation of the cement layer thickness after luting two different posts. J Adhes Dent 2005; 7:235–240.
Gomes GM, Gomes OM, Gomes JC, Loguercio AD, Calixto AL, Reis A. Evaluation of different restorative techniques for filling flared root canals: fracture resistance and bond strength after mechanical fatigue. J Adhes Dent 2014; 16:267–276.
Chakmakchi M, Rasheed R, Suliman R. In vitro
comparative assessment of fracture resistance of roots restored with everstick fiber reinforced composite post. J Oral Dent Res 2015; 1:43–50.
da Silva NR, Raposo LH, Versluis A, Fernandes-Neto AJ, Soares CJ. The effect of post, core, crown type, and ferrule presence on the biomechanical behavior of endodontically treated bovine anterior teeth. J Prosthet Dent 2010; 104:306–317.
Zogheib LV, Pereira JR, do Valle AL, de Oliveira JA, Pegoraro LF. Fracture resistance of weakened roots restored with composite resin and glass–fiber post. Braz Dent J 2008; 19:329–333.
Santos-Filho PC, Castro CG, Silva GR, Campos RE, Soares CJ. Effects of post system and length on the strain and fracture resistance of root filled bovine teeth. Int Endod J 2008; 41:493–501.
Mortazavi V, Fathi MH, 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 (Isfahan) 2012; 9:185–191.
Aquaviva S, Gauri S. Factors affecting the fracture resistance of post-core reconstructed teeth: a review. Int J Prosthodont 2001; 14:355–363.
Newman MP, Yaman P, Dennison J, Rafter M, Billy E. Fracture resistance of endodontically treated teeth restored with composite posts. J Prosthet Dent 2003; 89:360–367.
Zhi-Yue I, Yu-Xing Z. Effect of post-core design and ferrule on fracture resistance of endodontically treated maxillary central incisors. J Prosthet Dent 2003; 89:368–373.
Naumann M, Metzdorf G, Fokkinga W, Watzke R, Sterzenbach G, Bayne S, et al.
Influence of test parameters on in vitro
fracture resistance of post-endodontic restorations: a structured review. J Oral Rehabil 2009; 36:299–312.
Abo El-Ela OA, Atta OA, El-Mowafy O. Fracture resistance of anterior teeth restored with a novel nonmetallic post. J Can Dent Assoc 2008; 74:441.
Burstein A, Wright T. Fundamentals of orthopedic biomechanics
ed. Baltimore: Williams and Wilkins; 1994. pp. 215–216.
Berkovite Z, Holland G, Moxham B. Oral anatomy, embryology and histology
ed. St Louis: Mosby; 2002.
Alfredo E, de Souza ES, Marchesan MA, Paulino SM, Gariba-Silva R, Sousa-Neto MD. Effect of eugenol-based endodontic cement on the adhesion of intraradicular posts. Braz Dent J 2006; 17:130–133.
Katebzadeh N, Dalton BC, Trope M. Strengthening immature teeth during and after apexification. J Endod 1998; 24:256–259.
Sorensen JA, Martinoff JT. Clinically significant factors in dowel design. J Prosthet Dent 1984; 52:28–35.
Arora C, Aras M, Chitre V. Evaluation and comparison of retention of different esthetic posts. J Indian Prosthodont Soc 2006; 6:82–89. [Full text]
Gale MS, Darvel BW. Thermal cycling procedures for laboratory testing of dental restorations. Review. J Dent 1999; 27:89–99.
Dikbas I, Tanalp J, Ozel E, Koksal T, Ersoy M. Evaluation of the effect of different ferrule designs on the fracture resistance of endodontically treated maxillary central incisors incorporating fiber posts, composite cores and crown restorations. J Contemp Dent Pract 2007; 8:62–69.
Guzy GE, Nichols JI. In vitro
comparison of intact endodontically treated teeth with and without endo-post reinforcement. J Prosthet Dent 1979; 42:39–44.
Sorensen JA, Martinoff JT. Intracoronal reinforcement and coronal coverage. A study of endodontically treated teeth. J Prosthet Dent 1984; 51:780–784.
Tjan AH, Whang SB. Resistance to root fracture of dowel channels with various thicknesses of buccal dentin walls. J Prosthet Dent 1985; 53:496–500.
Cormier CJ, Burns DR, Moon P. In vitro
comparison of the fracture resistance and failure mode of fiber, ceramic and conventional post systems at various stages of restoration. J Prosthodont 2001; 10:26–36
Callister WD. Materials science and engineering: an introduction composites
. Chapter 17. 3rd
ed. New York: Wiley; 1997. pp. 513–541.
Lassila LV, Tanner J, Le Bell AM, Narva K, Vallittu PK. Flexural properties of fiber reinforced root canal posts. Dent Mater 2004; 20:29–36.
Seefeld F, Wenz HJ, Ludwig K, Kern M. Resistance to fracture and structural characteristics of different fiber reinforced post systems. Dent Mater 2007; 23:265–271.
Garoushi S, Tanner J, Vallittu P, Lassila L. Preliminary clinical evaluation of short fiber-reinforced composite resin in posterior teeth: 12-months report. Open Dent J 2012; 6:41–45.
Sorensen JA, Ahn SG, Berge HX, Edelhoff D. Selection criteria for post and core materials in the restoration of endodontically treated teeth. Acad Dent Mater 2001; 15:67–84.
Gu W. Interfacial adhesion evaluation of uniaxial fiber-reinforced–polymer composites by vibration damping of cantilever beam [PhD thesis]. Virginia Polytechnic Institute and State University: Virginia; 1997. p. 89.
Kıvanç BH, Alaçam T, Ulusoy ÖA, Genç Ö, Görgül G. Fracture resistance of thin-walled roots restored with different post systems. Int Endod J 2009; 42:997–1003.
Bolay S, Öztürk E, Tuncel B. Fracture resistance of endodontically treated teeth restored with or without post systems. J Dent Sci 2012; 7:148–153
Maccari PC, Cosme DC, Oshima HM, Burnett LH, Shinkai RS. Fracture strength of endodontically treated teeth with flared root canals and restored with different post systems. J Esthet Restor Dent 2007; 19:30–36.
Fernandes AS, Dessai GS. Factors affecting the fracture resistance of post-core reconstructed teeth: a review. Int J Prosthodont 2001;14:355–363.
Ferrario VF, Sforza C, Serrao G, Dellavia C, Tartaglia GM. Single tooth bite forces in healthy young adults. J Oral Rehabil 2004; 31:18–22.
Giovani A, Vansan L, Neto M, Maria S. In vitro
fracture resistance of glass–fiber and cast metal posts with different lengths. J Prosthet Dent 2009; 101:183–188.
Kinney JH, Marshall SJ, Marshall GW. The mechanical properties of human dentin: a critical review and re-evaluation of the dental literature. Crit Rev Oral Biol Med 2003; 14:13–29.
Sano H, Ciucchi B, Matthews WG, Pashley DH. Tensile properties of mineralized and demineralized human and bovine dentin. J Dent Res 1994; 73:1205–1211.
Eskandarizadeh A, Elm-Amooz N, Rahimi F, Baharlooyi K, Naeimi-Jamal MR. The effect of aging on nano-hardness and modulus of elasticity of four types of composites: an in-vitro study. J Dent Mater Tech 2016; 5:162–171.
Braem M, Finger W, Van Doren VE, Lambrechts P, Vanherle G. Mechanical properties and filler fraction of dental composites. Dent Mater 1989; 5:346–349.
Monteiro GQ, Montes MR. Evaluation of linear polymerization shrinkage, flexural strength and modulus of elasticity of dental composites. Mater Res 2010; 13:51–55.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
[Table 1], [Table 2]