Fracture Resistance of Primary Molars After Pulpotomy Procedure Using Mineral Trioxide Aggregate or Biodentine

doi:10.21203/rs.3.rs-2599421/v1

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Fracture Resistance of Primary Molars After Pulpotomy Procedure Using Mineral Trioxide Aggregate or Biodentine

https://doi.org/10.21203/rs.3.rs-2599421/v1

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Objectives

The aim of this study was to examine the effect of different tricalcium silicate materials on the fracture resistance of pulpotomized primary molar teeth with class II mesio-occluso-distal cavities.

Materials and Methods

Seventy-five extracted mandibular primary molars were used in this study. The teeth were randomly divided into 5 groups (n = 15 for each group). In group 1, the teeth were left unprepared and unfilled (negative control); in group 2, pulpotomy cavities were performed, but left unfilled (positive control); in Group 3, mineral trioxide aggregate (MTA) and glass ionomer cement (GIC) was applied; in Group 4, Biodentin and GIC; and in Group 5, zinc oxide eugenol paste and GIC was placed in the pulp chamber. Then, cavities were restored with composite filling material. The teeth in all groups were subjected to thermocycling for 5000 cycles at 5°C–55°C. Each specimen was then subjected to fracture testing using a universal testing machine. The force required to fracture each specimen was recorded, and the data were analyzed statistically.

Results

Fracture resistance values obtained were as follows: Group1 > Group 4 > Group 3 = Group 5 > Group 2, (p < 0.05). The most common type of fracture was restorable in all experimental groups (p < 0.05).

Conclusion

Biodentine can be used as a suitable base material against fracture in teeth undergoing pulpotomy.

Clinical Relevance

The type of the base material used during the pulpotomy procedure may affect the fracture resistance of primary molar teeth.

Biodentine

MTA

primary teeth

pulpotomy

Primary teeth, which act as space maintainer for permanent teeth, stimulate the vertical development of the jaws with chewing movements, and contribute to the nutrition, growth and development of the child, are also important in terms of phonation and aesthetics [1]. Early loss of primary teeth can cause undesirable conditions such as decreased chewing function, loss of space, malocclusion, speech disorders, psychological disorders, and atypical tongue habits. These problems can be prevented by treating the primary teeth and maintaining their functions in the dental arch until the permanent teeth erupt [2].

In deeply carious primary teeth, pulpotomy is one of the treatment options applied in cases where the pulp is exposed during the removing of the caries but the root pulp is healthy and maintains its healing capacity. It is the process of removing the crown pulp affected by caries and inflamation, and covering the remaining healthy root pulp with a capping agent that will protect the vitality of the pulp or ensure its fixation [3, 4]. An ideal pulpotomy agent should be bactericidal, biocompatible, aid in root pulp healing, and resorb at a rate similar to physiological root resorption. However, an ideal capping agent that fully meets these conditions has not yet been found. It has been shown that the success of treatment in primary tooth pulpotomy depends on the age of the child, the severity of the inflammation in the crown and root pulp, the degree of root resorption, the technique used and the quality of the pulpotomy material, the characteristics of temporary or permanent restorations, the observation period, and the experience of the physician [5, 6]. Improper restorations after pulpotomy treatment cause coronal microleakage, which is one of the factors that play a role in the failure of the treatment [7]. For this reason, it is recommended that the physical properties of the teeth be restored with a strong material in order to prevent the post-operative crown fractures and microleakage that may occur in primary teeth where increased fragility and excessive substance loss are observed after pulpotomy treatment [8, 9]. Recently, the use of various tricalcium silicate materials has become widespread for the pulpotomy procedure. Among these materials, mineral trioxide aggregagate (MTA) and Biodentine are frequently used in pulpotomy treatments due to their high clinical success [10–12].

The aim of this study was to evaluate the effect of using MTA and Biodentine as base materials on the fracture resistance of teeth after pulpotomy in primary molar teeth. The null hypothesis was that there was no difference between using MTA or Biodentine in terms of the fracture resistance of pulpotomized teeth.

Ethical approval and sample size calculation

Based on the data of Ghajari et al. [13], the power calculation results revealed that the sample size for each group should be a minimum of 15 (power 0.90, effect size = 0.862, and significance level a = 0.05). A total of 75 teeth were used in the study.

Preparation of teeth

In this study, primary lower molars extracted due to periapical pathology and preventive orthodontic treatment were used. Teeth had belonged to children aged 4 to 6 years. Before the beginning of the study, the teeth to be used were examined under an operating microscope to detect the presence of any cracks or fractures. Teeth were stored in distilled water at room temperature until the start of the experiment. To ensure standardization by incorporating similar sized teeth into the study, the buccal and lingual dimensions of the crown (height and width) were measured by a digital caliper with 0.01 mm accuracy. Fifteen teeth served as the negative control group (Group 1) and received no treatment. The remaining 60 teeth were prepared using diamond fissure burs (Diatech, Coltene Whaledent, Altstatten, Switzerland) with 1-mm diameter and 4-mm height, and high-speed handpiece underwater and air spray. The pulp chamber roof was removed, and then a mesio-occluso-distal (MOD) cavity was prepared in such a way that the isthmus width of the occlusal cavity was two-thirds of the intercuspal distance, and the gingival floor in mesial and distal cavities was terminated at 1-mm distance from the cemento-enamel junction. Fifteen of these teeth were used in the positive control group (Group 2) and no restoration was made to these teeth. Then, 45 teeth were divided into three experimental groups, as described below.

Experimental groups

Group 3: In this group, white MTA (Angelus, Londrina, PR, Brazil) was placed up to the middle of the pulp chamber, and the remaining part of the pulp chamber was filled with glass ionomer cement (GIC). Restorations were completed using composite resin (Filtek Z550) as the final filling material.

Group 4: Biodentine (Septodont, Saint Maur des Fosse's, France) was placed on the teeth in this group up to the middle of the pulp chamber. GIC was placed in the remaining part of the pulp chamber and the restoration of the crown of the tooth was completed with composite resin restorative material (Filtek Z550; 3 M ESPE, St.Paul, MN, USA).

Group 5: Zinc oxide eugenol (ZOE) was placed up to the middle of the pulp chamber and the remaining part of the pulp chamber was filled with GIC. As in the other experimental groups, the processes were completed by using composite resin (Filtek Z550) as the final restorative material (Fig. 1).

After the photopolymerization processes of the composite resin filling material were completed, polishing processes were performed using soflex discs (3M ESPE, St. Paul, MN, USA) followed by polishing rubbers. In the next step, the teeth were mounted in autopolymerizing acrylic resin at 1-mm distance from their cemento-enamel-junction. Teeth were then stored in distilled water at 37°C for 24 h, after which thermo-cycling aging was conducted for 5000 cycles (5°C/55°C) with a dwell time of 30 s and a transfer time of 10 s. The teeth were then subjected to chewing simulation. A total of 250000 cycles were applied in an L-shaped direction of chewing simulation at 0.5 mm horizontal, 0.4 mm vertical, chewing frequency 1.6–1.7 Hz, and 50 N force. A universal testing machine (Instron Corp, Canton, MA, USA) was used for the fracture strength test. The samples were placed on the lower part of the test machine and a steel tip with a diameter of 4 mm was fixed on the upper moving part of the device. Fracture strength testing was carried out by applying a continuously increasing force at a speed of 0.5 mm/min parallel to the long axis of the tooth at the point corresponding to the central fossa of the teeth. When the fracture occurred, the teeth were removed from the testing machine and the fracture types were recorded as restorable or unrestorable. The fracture types were classified as “restorable” (Fig. 2A) when the failure was above the acrylic resin (simulated bone level) and “unrestorable” when the failure extended below the acrylic resin (simulated bone level) (Fig. 2B) [14].

Statistical analysis

The Kolmogorov-Smirnov statistical test for normality revealed a normal data distribution. Data were statistically analyzed using one-way analysis of variance (ANOVA) followed by Tukey post-hoc test for multiple comparisons. Chi-square test was applied to analyze the fracture types. All statistical analyzes were performed with SPSS version 20.0 for Windows (SPSS Inc., Chicago, IL, USA), and the significance level was set at P < 0.05.

Means and standard deviations of the fracture resistance values of the groups are shown in Table 1. The highest fracture resistance was observed in Group 1, which comprised teeth without any preparation (p < 0.05). Group 2 (positive control) had the lowest fracture resistance values (p < 0.05). The fracture resistance values among the other groups were as follows: Group 3 = Group 5 < Group 4 (p < 0.05). When the fracture types of the groups 3, 4 and 5 were examined, it was observed that the most frequent failure type was restorable (Table 1). Moreover, there was statistically significant difference between the fracture types of the groups (p < 0.05).

Table 1

Mean fracture resistance values and fracture types of the groups
Groups (n = 15 for each group)	Mean ± SD (newton)	Fracture type
		Restorable	Unrestorable
Negative control	624.13 ± 142.3 ^A
Positive control	179.26 ± 45.2 ^B
ZOE + GIC + Composite	312.50 ± 84.7 ^C	8^a	7
MTA + GIC + Composite	334.17 ± 71.4 ^C	13^b	2
Biodentine + GIC + Composite	496.36 ± 125.1 ^D	12^b	3
ZOE = zinc oxide eugenol, GIC: glass ionomer cement
The same superscript letters indicate no significant differences (p > 0.05).

Following pulpotomy, teeth are more susceptible to fracture (compared to healthy pulp). The reason for this is the presence of extended caries and the removal of extensive tooth structure during pulpotomy cavity preparation [15]. This increases cusp deflection and the risk of cusp fracture during chewing function [16]. Therefore, it is essential to use restorative materials that support the remaining tooth structure after the pulpotomy procedure.

Reviewing the pediatric dentistry literature, it is clear there are few studies evaluating the fracture resistance of pulpotomy teeth [13, 17, 18]. Moreover, there is no study evaluating the effect of base (intraorifice barrier) materials on the fracture resistance of pulpotomized teeth. Roghanizad and Jones [19] introduced the concept of an intracoronal barrier to prevent coronal leakage in endodontically treated teeth. Nagas et al. [20], also stated that intraorifice barriers can be used under final restorations to provide resistance against forces that cause vertical fractures in teeth. An intraorifice barrier material such as MTA or Biodentine is also used in pulpotomized teeth. Placement of the intraorifice barrier material is important in terms of protecting the health of the pulp tissue in the root, preventing microleakage, and supporting the teeth against fracture.

Removal of the roof of the pulp chamber during pulpotomy procedure considerably reduces the support for these teeth against chewing forces. Therefore, it is important that the materials to be placed both in the pulp chamber (as intraorifice material) and in the crown cavity are of a type that will protect the teeth against fracture [21–23]. In the present study, we evaluated the effect on the fracture resistance of primary teeth of two different tricalcium silicate materials used an intraorifice barrier material during pulpotomy.

For the present study, Class II MOD cavities were used to simulate the clinical situation during pulpotomy treatment. Lower primary molars were selected. Two types of materials (including MTA and Biodentine) were used for the pulpotomy treatment. In addition, an experimental group containing zinc oxide eugenol, another frequently preferred clinical material, was included in the study.

In studies investigating the effect of dental materials on the fracture resistance of teeth, the occlusal loading method during the test is important as it may affect the results. In many studies testing the fracture resistance of teeth, fracture resistance was tested by applying a vertical force to the center of the occlusal surface [24, 25]. In the present study, the fracture test was likewise performed by applying a vertical force. Nonetheless, because teeth will also be exposed to horizontal forces in the oral environment [22], this should be considered as a limitation of studies testing fracture resistance. In the present study, the effect of temperature changes and continuous chewing in the mouth was also simulated by exposing the teeth to the chewing simulator and thermo-cycler device.

The results of this study showed that the fracture resistance of the pulpotomized teeth was lower than that of the intact teeth. This may be associated with loss of tooth structure in pulpotomized teeth. This result is in line with previous studies which demonstrated that the fracture resistance of the teeth decreased after cavity preparation [15, 26]. Moreover, according to the results of the present study, the type of material used as intracoronal barrier material during pulpotomy procedure affected the fracture resistance of the teeth. In the present study, the increased force required to fracture teeth in Biodentine group relative to the other experimental groups could be explained by the smaller particle size and uniform components of Biodentine, which affects the adhesion of material into dentinal tubules [27]. Another possibility for this result may be that the compressive strength of Biodentine is higher than MTA and ZOE [28, 29]. It has been stated that compressive strength is an indicator of strength of the material [30]. Furthermore, compressive strength of the material is important when used in clinical situations, such as vital pulp therapy and coronal barriers [31].

Clinically, stainless steel crown, amalgam, and resin composite materials are frequently used as final restorative materials following pulpotomy treatment. In an in vitro study, it has been reported that amalgam restorations do not support or strengthen dental tissue in pulpotomized primary molars [18]. It has also been reported that in stainless steel crowns (another treatment option), plaque accumulation, formation of gingival problems, and changes in sulcus measurements may be encountered. Among the factors at the source of these problems are incorrect placement or excessive contouring of the stainless steel crowns [32]. As a result of these, it has been stated that oral hygiene may be difficult to provide, and plaque accumulation and disease in the gingival tissue may ocur [33]. In addition, the fact that neither amalgam nor stainless steel crowns are aesthetic materials increases the questionability of their use [34]. In the current study, composite resin restorative material was used in all experimental groups as the final restoration material in pulpotomized teeth. Considering the recent developments in the physical and chemical properties of composite materials, the use of composite resin as a restorative material in teeth undergoing pulpotomy has come to the fore. Resin composites can protect tooth structure and increase tooth strength against fracture [35]. It also has benefits such as maintaining the normal contact area between the teeth, avoiding trauma to the gingiva during the placement of a crown, and having an aesthetically pleasing appearance. El-Kalla and Garcia-Godoy [18] showed that the use of composite resin as final restorative material after pulpotomy increased the fracture resistance of teeth.

Based on this study’s results, the following conclusions can be made:

The fracture resistance of primary molar teeth can differ according to the base material used for the pulpotomy procedure.
Many further studies are needed to evaluate the effect of different variables on the fracture resistance of pulpotomized teeth.

Author contributions Gamze Topçuoğlu performed investigation, formal analysis, data curation, writing—original draft, and project administration. Gamze Topçuoğlu performed formal analysis and data curation. Gamze Topçuoğlu contributed to conceptualization, methodology, and writing—review and editing. Hüseyin Sinan Topçuoğlu performed writing—review and editing. Hüseyin Sinan Topçuoğlu contributed to conceptualization, methodology, and funding acquisition.

Funding No funding was obtained for this study.

Ethics approval The study protocol was approved by the Ethics Committee of University (approval number: 2022/780).

Consent to participate N/A

Conflict of interest The authors declare no competing interests.

Acknowledgments The authors deny any conflicts of interests related to this study.

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No competing interests reported.

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Version 1

posted

You are reading this latest preprint version

Fracture Resistance of Primary Molars After Pulpotomy Procedure Using Mineral Trioxide Aggregate or Biodentine

Status:

Version 1

Abstract

Objectives

Materials and Methods

Results

Conclusion

Clinical Relevance

Figures

Introduction

Materials And Methods

Ethical approval and sample size calculation

Preparation of teeth

Experimental groups

Statistical analysis

Results

Discussion

Conclusions

Declarations

References

Additional Declarations

Status:

Version 1