CC BY 4.0 · European Journal of General Dentistry 2022; 11(03): 166-172
DOI: 10.1055/s-0042-1749333
Original Article

Push-out Evaluation on Metal and Fiber Posts Using Two Different Types of Cement in a Hyper-Narrow Environment

Elanz Shafigh
1   Operative Dentistry Department, Faculty of Dentistry, AJA University of Medical Sciences, Tehran, Iran.
,
2   Periodontology Department, Faculty of Dentistry, AJA University of Medical Sciences, Tehran, Iran
,
1   Operative Dentistry Department, Faculty of Dentistry, AJA University of Medical Sciences, Tehran, Iran.
› Author Affiliations
 

Abstract

Objective Some teeth will be damaged due to caries, trauma, or previous improvement; posts are used to repair them. Underwater divers suffer from barodontalgia as a result of the tremendous amount of pressure they feel when diving. Meanwhile, barodontalgia instances involve teeth with defective restorations. Therefore, this study aimed to determine the push-out bond strength on metal and fiber posts using two different types of cement in a hyper-narrow environment.

Materials and methods In this study, 96 single-rooted teeth, including central and lateral maxillary teeth and mandibular premolars were provided and underwent endodontic treatment. Root canal treatment, including cleaning the root canal using the manual and rotary files was performed in f2 size with 6% tipper. For purification, washing was performed in two steps with 5.25% sodium hypochlorite and normal saline, respectively. The obtained data were evaluated using statistical methods such as one-way analysis of variance and the Levene and Tamhane additional tests.

Results The quantity of push-out strength was dramatically reduced in the metal posts and fibers groups due to increasing ambient pressure. The highest decrease rate was observed in the group of metal posts and resin cement. The highest bond strength in a typical environment was related to fiber posts, and among the fiber groups, those that had the highest bond strength were used as a combination of resin cement and fiber posts.

Conclusion The highest level of bond strength among the study groups, at standard pressure and in a hyper-narrow environment, was related to fiber posts and resin cement. Therefore, the best choice for treatments for divers in a hyper-narrow climate is a combination of fiber posts and resin cement.


#

Introduction

Root canal repair due to caries or trauma is part of clinical treatments in dentistry.[1] Posts are used to repair damaged and root canal therapy teeth.[1] [2] Because part of the forces applied to the restoration enters the root structure through the post, the improper post can increase the stresses applied to the tooth.[3] Various materials have been used to make dental posts.[2] The introduction of fiber posts as an alternative to cast and parapet posts for endodontically treated teeth is a significant advancement in restorative dentistry.[4] Cement has also been introduced in dentistry as a link between restoration and teeth, whose main task is to help a permanent connection and establish a strong bond between restoration and teeth.[5] Various cements have been introduced to increase the bond strength to the canal wall, especially for fiber posts.[6] Resin cements, compared with conventional adhesives, can maintain the upper post and increase the fracture resistance of the tooth after restoration.[7] There are various methods for measuring bond strength. Push-out testing is a practical method for evaluating the factors that affect the bond strength of fiber posts.[8] Exposure of teeth to abnormal air pressure conditions, such as excessive atmospheric pressures, can lead to ambiguous pain called barodontology in the oral environment,[9] [10] tooth fractures, restorative fractures, and denture prosthesis restraint,[11] which may last for a long time.[10] Therefore, barodontology pain is defined as a pressure-induced toothache that can occur at both high and low pressures.[12] This phenomenon is generally experienced in teeth with previous pathosis.[13] Barodonatalgia has been reported at depths of 10 m (pressure 10 kPa) or less, especially in divers.[14] Therefore, divers are among the people who constantly face such problems. In this phenomenon, the maxillary teeth are more involved than the mandibular teeth.[15] Clinical observations, especially in divers who are under excessive atmospheric pressure (hyper-narrow), have shown that the tendency of fracturing the restored teeth is higher than normal teeth, and this case in denervated teeth will be increased due to the weakened nature of the tooth. Thus, the purpose of this study was to determine the push-out bond strength on metal and fiber posts using two different types of cement in a hyper-narrow environment.


#

Materials and Methods

The present study was performed by a laboratory method for 18 months (October 20, 2018–March 21, 2019) in the Dental Materials Research Center of Isfahan University of Medical Sciences (Iran). For this purpose, 96 single-rooted teeth, including central, lateral maxillary, and mandibular premolars, were provided, which were almost intact, without caries, and close to each other in terms of crown size and root length, which were extracted for orthodontic and periodontal purposes, and all patients underwent endodontic treatment. Root canal treatment, including cleaning the root canal by helping the manual file and rotary file (Denco Super files Denco Medical co, Shenzhen, China), was performed in f2 size with 6% tipper. For purification, the washing operation was conducted in two stages with 5.25% sodium hypochlorite and normal saline, respectively. The canals were dried entirely using a paper cone and gutta-percha with a 2% tipper (Meta-Biomed Co, Korea) and AH26 sealer (Dentsply, Tulsa, Oklahoma, USA). Then dental watering was performed using a lateral compaction technique. The samples were divided into eight groups of 12 ([Table 1]). The parametric approach of one-way analysis of variance (one-way ANOVA) was employed with the SPSS version 16 software to evaluate statistical differences between unrelated groups. Due to the failure of the null hypothesis and the lack of an equation of variance (equal variances were not assumed), the Tamhane supplemental test was employed to identify the groups responsible for the variance difference. In groups that needed prefabricated metal posts, size L1 metal posts (Directa Dental, Upplands Vasby, Sweden) with an approximate diameter of 1.05 mm were used. The metal posts are made of stainless steel with brass coating and fiber posts are also fiberglass composite and high strength epoxy resin. FGM white post (FGM Dental, Brazil) size 1 with an approximate diameter of 1 mm was used in groups that needed fiber posts. The GI cement used in the design was Fuji IX luting cement (GC Corp., Tokyo, Japan), and the resin cement was Meta-Cem (Meta-Biomed, Korea). To insert the post into the canal, all canals were first emptied using a 9 mm long piezo remover size 3. According to the manufacturer's instructions, the canals were washed and dried. In groups 1, 2, 3, 4, the powder and cement liquid were mixed in a specific ratio and placed in the canal by Lentulo. Then, the cement was spread into the canal using a periodontal probe. However, the post was impregnated with cement and placed inside the canal. After about a minute, the cement additives were removed from around the post. In 5, 6, 7, 8 groups, the canal was emptied, then washed and dried. Diaetch acid with a concentration of 37% (UltraEtch, UltraDent) was placed inside the canals, and then the canal was washed after 15 seconds and then dried after 10 seconds. The Ambar Universal bond (FGM Co, Brazil) was placed in the canal, spread with air pressure for 5 seconds, and cured for 2 seconds. Then, the resin cement was mixed on the slab using a special syringe. The inside of the canal and the surface of the post were impregnated with cement, and after placing the post in the canal for 20 seconds, it was cured. All samples were etched for 20 seconds with 37% Diaetch acid after placing the posts and dried with air for 20 seconds. The Ambar Universal bond was set on the surface and around the post using a micro brush, and then the bond was dried for 5 seconds and cured for 20 seconds. Finally, they were built up using the P60 composite (3M, St. Paul, Minnesota, USA). All samples were mounted vertically in a three-component resin (consisting of 3 separate components) to facilitate the work and subsequent steps. The entire length of the root was inside the resin and the crown was out.

Table 1

Cement used in the study and their combination with different posts in normal conditions and hyper-narrow environment

Group

Composition

Manufacturers

Batch number of posts

GI cement

Fuji IX

GC Corporation, Tokyo, Japan

Prefabricated fiber post at normal air pressure[1]

Prefabricated fiber post at air pressure over atmospheric[2]

Prefabricated metal post at normal air pressure[3]

Prefabricated metal post at air pressure over atmospheric[2]

Resin cement

Meta-Cem

Meta-Biomed, Korea

Prefabricated fiber post at normal air pressure[4]

Prefabricated fiber post at air pressure over atmospheric[5]

Prefabricated metal post at normal air pressure[6]

Prefabricated metal post at air pressure over atmospheric[7]

The samples were then placed in an incubator (01154, Behdad, Tehran, Iran) for 24 hours. In the last stage, before cutting, half of the samples were placed in a special compression chamber and were pressed twice (equal to a 20-m underwater penetration depth) for 14 days and 45 minutes every day. The crowns of the teeth were cut at ∼2 mm CEJ (cementoenamel junction) by a CNC cutting section machine (3Axes full automatic, Nemo Fanavaran Pars, Mashhad, Iran) into 1 mm thick sections. Units that were closer to each other in terms of area and diameter were selected for use in the Micro Push-out test device from each of the samples. Finally, the sections for push-out testing were placed in the Electromechanical Universal Testing Machine (K-21046, Walter + bai, Switzerland) ([Fig. 1]), and the test results were recorded. All teeth used in this project were selected with the individual's consent, and no action was taken to extract and use the individual's teeth to carry out this research. The middle sections were also examined for the mode of failure using a stereomicroscope (Trinocular zoom stereo microscope, SPM-300, HP, USA) at 30× magnification. Adhesive in dentin, sticky in the post, and cohesive in cement where the failure modes were identified ([Fig. 2]).

Zoom Image
Fig. 1 Electromechanical Universal Testing Machine (TN0101, Walterbai, CH. 8224, Lohningen, Switzerland).
Zoom Image
Fig. 2 Adhesive failure in the root canal.

#

Results

The one-way ANOVA and Tamhane supplemental test findings show a statistically significant difference between the eight groups of samples (p = 0.001) ([Table 2]). Due to the rise in ambient pressure, the push-out strength of the metal and fiber posts in conjunction with both GI and resin cements was dramatically decreased ([Table 3]). Although this drop was significant in all groups, the pace at which it occurred varied (p = 0.001) ([Fig. 3]). The group with metal posts and resin cement had the greatest reduction in “push-out,” which reduced from 51.88 to 11.52. The maximum bond strength was attained in a typical environment by employing fiber posts. The fibers with a mix of resin cement (Meta-cem) and fiberglass post had the strongest binding strength among the fiber groups ([Table 3]). [Table 4] shows the failure of the samples on metal and fiber posts using two kinds of cement in normal and hyperbaric conditions. Examining the failure type of the samples yielded the following findings. Except for groups[1] (fiber + GC + normal) and[2] (fiber + meta + normal), the other 10 groups had adhesive failures in both types of cement. In group 1 (fiber + GC + normal), 50% of failures were cohesive and 50% were adhesive. Furthermore, in group 2 (fiber + meta + normal), 91.66% of failures were adhesive, whereas 8.33% were cohesive.

Table 2

Tamhane test results

Group

Group

Sig.

1

2

<0.001

3

<0.001

4

<0.001

5

<0.001

6

0.986

7

1

8

<0.001

2

3

0.921

4

0.649

5

<0.001

6

0.003

7

0.304

8

0.007

3

4

<0.001

5

<0.001

6

0.015

7

0.804

8

<0.001

4

5

<0.001

6

<0.001

7

0.035

8

0.02

5

6

0.015

7

0.248

8

<0.001

6

7

1

8

<0.001

7

8

0.005

Table 3

Results of one-way analysis variance

Number

Mean

Std. deviation

Lower bound

Upper bound

Minimum

Maximum

1

12

55.8800

7.04958

51.4010

60.3591

44.54

71.15

2

12

29.0159

11.69992

21.5822

36.4497

15.38

50.57

3

12

35.9045

5.84705

32.1894

39.6195

29.24

52.17

4

12

20.2866

6.40580

16.2166

24.3567

6.51

30.57

5

12

78.5340

20.29408

65.6397

91.4282

55.13

117.32

6

12

50.3673

10.31129

43.8158

56.9188

41.75

72.32

7

12

51.8790

25.60486

35.6104

68.1475

14.43

98.92

8

12

11.5191

3.76661

9.1259

13.9123

7.26

18.38

Total

12

41.6733

24.18193

36.7736

46.5730

6.51

117.32

Table 4

Type of failure for all samples

Post type

Type of cement

Pressure

Type of failure

Post type

Type of cement

Pressure

Type of failure

Post type

Type of cement

Pressure

Type of failure

Fiber

GC

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Fiber

Meta

Normal

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Fiber

Meta

Normal

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Cohesive

Fiber

Meta

Normal

Adhesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Fiber

Meta

Normal

Cohesive

Metal

Meta

Hyper

Adhesive

Fiber

GC

Normal

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Normal

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Normal

Cohesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Normal

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Normal

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Fiber

GC

Hyper

Adhesive

Fiber

Meta

Hyper

Adhesive

Metal

GC

Normal

Adhesive

Fiber

Meta

Hyper

Adhesive

Metal

GC

Normal

Adhesive

Fiber

Meta

Hyper

Adhesive

Metal

GC

Normal

Adhesive

Fiber

Meta

Hyper

Adhesive

Metal

GC

Normal

Adhesive

Fiber

Meta

Hyper

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Normal

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Normal

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Metal

GC

Hyper

Adhesive

Metal

Meta

Hyper

Adhesive

Zoom Image
Fig. 3 Average of bond strength based on the type of variables.

#

Discussion

This study aimed to select the most appropriate treatment to repair the treated root and anterior teeth of divers. In both groups of metal and fiber posts, with both types of GI and resin cements, the amount of push-out strength was significantly reduced due to the increase in ambient pressure. This can be considered to be the effect of environmental stress in reducing the cohesive strength of used cements and reducing the adhesive force between cement and post or cement and dentin. Jagger et al[16] investigated the prevalence of pain linked with changes in air pressure among divers, finding that roughly 1% of these individuals experience such discomfort after being exposed to pressures higher in the atmosphere. [Fig. 3] shows the changes in push-out strength over time. All groups saw a significant drop in push-out strength (p = 0.001), but the amount of drop was different for each group. In agreement with these results, a study conducted by Panah et al[17] to investigate the effect of pressure on bond strength between fiber posts and different resin cements, which results showed that Unicem cement has higher bond strength than other cements and all groups under the influence of pressure cycles had a decrease in bond strength. The highest decrease was observed in the group of metal posts and resin cement, which decreased from 51.88 to 11.52. This reduction is equivalent to 80% of the push-out strength and can have a devastating effect on restored teeth in divers. The reason for this can be explained by the fact that Meta-cem cement is a self-adhesive resin cement whose purpose is to connect with tooth tissue on one side and dental posts on the other side. No bond was probably made between the post and cement because in this group, the metal posts were used, or that existing bond was so weak that it was destroyed with the slightest impact of environmental factors. In contrast, in GC + metal groups, we see the connection of metal post bond and GC cement, in which 2 points are essential[1]: Push-out strength in a typical environment is the lowest compared with other groups (35.90),[2] the rate of reduction is less than other groups by increasing the pressure, which indicates that GC cement with a metal post does not establish a strong bond, and in contrast, is not strongly influenced by environmental factors, which means that although the metal bond with GC cement is weak, it is solid and environmental factors do not affect it. The study by Kececi et al[18] to investigate the push-out strength between four types of FRC posts and two types of resin cements showed that the amount of force is affected by the kind of post and the type of cement. The highest bond strength in a typical environment is related to fiber posts. Among the fiber groups, those who have used a combination of resin cement (meta-cem) and fiber post have the highest bond strength (78.53). This indicates the success of the fiber post bond made of glass and resin self-adhesive cements. In contrast, the bond strength in these groups after increasing the air pressure (despite a decrease of ∼30%) is higher than the bond strength after increasing the air pressure in other groups. Compared with the metal post and resin cement groups at normal pressure, these groups form a stronger bond, which together indicates the possibility of high confidence in the combination of fiber posts and self-adhesive resin cements. In agreement with these results, Pest et al[19] conducted a study to evaluate the push-out strength in fiber posts and resin cements as well as microscopically examined for the degree of cohesion between the canal wall and these materials and stated that the clinical use of these materials cause to increase the strength of the remaining tooth tissue and prevents from breaking. Pereira et al[20] noted that laboratory studies demonstrate that adhesive resin cements provide good results in the push-out test. Diving pressure cycles have adverse impacts on the fracture resistance values of composite restorations and amalgam groups, according to the findings of Shafiq et al[21]. Despite this, composite restorations outperformed amalgam restorations in terms of fracture resistance. Mitov et al[22] in a study investigated the effect of diving simulator environments on microleakage and post forceps in endodontically treated teeth and concluded that the use of a combination of fiber posts and resin cements for endodontically treated teeth in people who are constantly under high air pressure is more suitable than other treatments. Wang et al, [23] while examining the push-out strength of two types of fiber posts and two types of resin cements, concluded that quartz-reinforced posts have higher strength than carbon-reinforced posts. Shafigh et al[24] investigated the effect of pressure changes on fracture resistance of three types of composite restorations during diving, they stated that the use of composite resins is recommended in divers because in comparison with resin, nano and micro-hybrid composites show higher fracture toughness. The average bond strength of fiber posts with GC cement is 55.88, which causes a 30% decrease by increasing the pressure (average bond strength reaches 29.02). The lapse rate is the same with both types of cement, but the bond strength of the combination of resin self-adhesive cement and fiber post with GC cement is much higher. According to the most recent studies, self-adhesive cements provide higher bond strength.[25]


#

Conclusion

Divers typically participate in scuba diving that entails more than 2 bars of pressure for at least 40 minutes, increasing the tension and strain on their teeth. As a result, the attachment of the post to the root dentin is crucial in the process of repairing the anterior teeth of divers. According to the findings of this study, and the constraints of in-vivo to in-vitro simulation environments, a combination of fiber post and self-adhesive resin cement is the best and the most appropriate solution for endodontically anterior tooth repair in divers. This compound, in contrast, has a greater starting strength and its strength decrease with rising ambient pressure is insignificant.


#
#

Conflict of Interest

None declared.


Address for correspondence

Mohammad Mehdi Bahrani
DDS, AJA University of Medical Sciences
Misagh Complex, Eastern 13th Street, Ajoudanieh, Tehran
Iran   

Publication History

Article published online:
21 July 2022

© 2022. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India


Zoom Image
Fig. 1 Electromechanical Universal Testing Machine (TN0101, Walterbai, CH. 8224, Lohningen, Switzerland).
Zoom Image
Fig. 2 Adhesive failure in the root canal.
Zoom Image
Fig. 3 Average of bond strength based on the type of variables.