Long-Term bacterial leakage along obturated roots restored with temporary and adhesive fillings

Methodologies used for testing the sealability of endodontic temporary fillings in vitro: A narrative review

Introduction

The ability of the temporary filling to seal endodontic access cavities may be crucial for the success of endodontic treatment. Numerous in vitro studies have investigated the sealability of the temporary fillings used in endodontic treatments. However, in vitro sealability studies have been criticized for their inconsistent results and questionable clinical relevance. Some journals have imposed moratoriums on publishing such studies to encourage researchers to test their validity and clinical relevance. Since the implementation of this moratorium, little progress has been made in this field. To further encourage researchers to investigate the reliability of these studies, this review presents an overview of the methodologies of studies that examine the ability of temporary filling materials to seal the endodontic access cavity in vitro and discusses the criticisms of these studies in detail.

Materials and Methods

PubMed, Scopus, and Embase electronic databases were searched to identify studies that tested in vitro the ability of temporary filling materials to seal endodontic access cavities. Only original articles published in English between 01/01/1970 and 28/02/2022 were included.

Results

The search yielded 551 results. After removing duplicates and excluding studies that did not meet the inclusion criteria, 94 studies were included in this review.

Conclusion

Although clinical studies may be the best way to test the performance of temporary fillings, the ethical importance of conducting preliminary in vitro studies is undeniable. It seems that questioning the reliability of in vitro sealability studies is not based on sufficient scientific evidence and that the inconsistencies in the results of these studies may be due to differences in the methodological and clinically relevant variables between them, rather than due to their unreliability.

Prevalence and nature of fungi in root canal infections: a systematic review and meta-analysis

The role of bacteria in causing apical periodontitis has been widely established, whilst the role of other microorganisms is studied less thoroughly. This systematic review and meta-analysis reviewed the literature for the prevalence and diversity of fungi in root canal infections. An extensive literature search was carried out in the Cochrane databases, EMBASE, MEDLINE, LILACS, SciELO and Web of Science. Additional studies were identified from six endodontic journals, four main endodontic textbooks and references of relevant papers. Selected clinical studies included sampling of necrotic pulps in permanent teeth and microbial analysis of these samples. Studies were critically appraised using the Joanna Briggs Institute Prevalence Critical Appraisal Checklist. Meta-analysis was performed using MetaXL. The screening of 1041 titles and abstracts and full-text reading yielded 54 studies. The overall prevalence of fungi in root canal infections was 7.5% (CI 95%: 3.6-11.8%) in the inverse variance fixed effect heterogeneity model. Candida albicans was the most frequently isolated species. Significant heterogeneity was observed (P < 0.001, I²  = 85.04%). Subgroup analyses based on geographical location, period of publication, type of infection, state of general health, communication with the oral cavity, type of sample and identification method revealed no factor influencing the prevalence. Better standardized techniques and a comprehensive analysis will reveal a more detailed and accurate representation of the prevalence and nature of fungi in root canal infections.

Bacterial microleakage of temporary filling materials used for endodontic access cavity sealing

Background/purpose

Providing a tight coronal seal is key for the success of endodontic treatment, therefore the study aimed to assess bacterial microleakage of materials used for short- and long-term temporization.

Materials and methods

One hundred and twenty-eight human upper-third molars were divided into six experimental groups (n = 20) and two control groups: negative (n = 4) and positive (n = 4). The standardized access cavities were prepared and filled with: (1) Cavit; (2) Fuji II LC; (3) Fuji IX; (4) Voco Clip; (5) AdheSE and Tetric EvoCeram; (6) Excite and Tetric EvoCeram. The crown of each tooth was sectioned to obtain 5.5-mm-high disks, which were assembled in a standard setup for bacterial microleakage studies using Streptococcus mutans. The monitoring lasted 90 days. Kaplan-Meier survival analysis was performed.

Results

The lowest amount of leaking samples was found in AdheSE and Tetric EvoCeram (31.3%), Cavit (33.3%), and Excite and Tetric EvoCeram groups (35.3%), followed by Fuji II LC (66.7%), Voco Clip (83.3%). and Fuji IX (88.2%) groups. According to the day of microleakage, materials could be classified in three groups with statistically significant differences (P < 0.05). In the first group were Cavit (70 days), AdheSE and Tetric EvoCeram (68 days), and Excite and Tetric EvoCeram (65 days), in the second group were Voco Clip (44 days) and Fuji II LC (43 days), and in the third group was Fuji IX (21 days).

Conclusion

None of the tested materials were able to completely prevent bacterial microleakage. Adhesively bonded composites and Cavit offer better sealing compared with glass ionomer cements, resin modified glass ionomer cements, and composites without the use of an adhesive system.

Clinical applications of glass ionomers in endodontics: a review

Glass ionomer cements (GICs) are biocompatible and have capacities to release fluoride and to bond to dentine, and thus are appropriate for use in endodontics. This paper reviews the composition and properties of different GICs, including their biocompatibility and antibacterial activity, their applications as intraorifice barriers and root canal sealers, and their use in the repair of root perforations, root-end fillings and temporary coronal restorations.

Microbial biofilm proliferation within sealer-root dentin interfaces is affected by sealer type and aging period

INTRODUCTION

Root canal fillings are intended to prevent microbial proliferation over time in the canal after treatment. The objective of this study was to assess biofilm proliferation within the sealer-dentin interfaces of 2 methacrylate resin-based systems, self-etch (SE) and total-etch (TE), and an epoxy resin-based sealer (EP), aged for up to 6 months.

METHODS

Standardized specimens (n = 45) comprising the coronal 5 mm of human roots were filled with the test materials and gutta-percha. Specimens were either not preincubated (control, n = 9) or were incubated in sterile saline for 1 week, 1 month, 3 months, or 6 months (n = 3/group). Monospecies biofilms of Enterococcus faecalis were grown on the specimens for 7 days in a chemostat-based biofilm fermentor mimicking pathogenic oral conditions. The extent of E. faecalis proliferation within the sealer-dentin interface for each material and incubation period group was assessed by using fluorescence microscopy of dihydroethidium-stained specimens.

RESULTS

TE had less biofilm proliferation than both EP and SE (P < .01). Deeper biofilm proliferation was detected in SE and EP specimens aged for 1 and 3 months than those aged for 1 week or 6 months (P < .05). Maximum depth of biofilm penetration was recorded for SE at 1 month (P < .05).

CONCLUSIONS

Within the test model used, the SE and EP sealers were more susceptible to interfacial biofilm proliferation than the TE restorative material. This susceptibility diminished after aging the materials' interfaces for 6 months.

Deproteinization technique stabilizes the adhesion of the fiberglass post relined with resin composite to root canal

To evaluate the effects of pretreatment of root dentin by 5.25% sodium hypochlorite (NaOCl) alone, associated with 2% chlorhexidine in gel base (CHX) and/or ethanol (EtOH), and the air-drying technique (Air) on the bond strength and adhesive durability of fiberglass post relined with resin composite to root dentin. A total of 100 bovine incisor roots were divided into 10 groups: G1 (control), irrigation with physiologic solution; G2, Air; G3, NaOCl; G4, NaOCl + Air; G5, NaOCl + EtOH; G6, NaOCl + EtOH + Air; G7, NaOCl + CHX; G8, NaOCl + CHX + Air; G9, NaOCl + CHX + EtOH; G10, NaOCl + CHX + EtOH + Air. Fiberglass post relined with resin composite was cemented and each group was randomly divided into two subgroups: 24 h of water storage and 12 months of water storage. The push-out test was performed and bond strength values were analyzed by ANOVA and Tukey's test. The use of NaOCl alone or associated with CHX had the highest values of bond strength with or without Air in the immediate and stored groups, being statistically similar to the immediate control group (p > 0.05). The groups using EtOH or Air alone had lower bond strength in the immediate and stored groups (p < 0.05). A significant decrease with the time of the bond strength in the control group was observed after 12 months of storage (p > 0.05). The use of NaOCl or NaOCl associated with CHX preserved the bond strength immediate and for 12 months. The air-drying technique and the other associations decreased the immediate bond strength values.

Is endodontic re-treatment mandatory for every relatively old temporary restoration? A narrative review

OBJECTIVES AND BACKGROUND

In this review, the authors examine whether there is any decisive evidence to support the revision of root fillings that have been exposed to the oral environment for more than three months, undertaken solely because of suspicions of microleakage. Researchers in numerous endodontic studies have addressed the evaluation of coronal microleakage by using different tracers and techniques. The need to achieve a tight, permanent coronal seal as soon as possible after the completion of endodontic treatment is obvious. However, the clinical importance of microleakage studies recently has been questioned because of their wide range and even contradictory results, and findings from only a few clinical investigations have demonstrated a clear relationship between the endodontic success rate and failure rate owed to coronal microleakage in cases involving high-quality endodontic therapy.

METHODS

The authors analyzed commonly cited articles regarding the clinical relevance of microleakage studies and the success rate of teeth with compromised restorations.

CONCLUSIONS

In a review of the literature, the authors found no clear evidence to support immediate replacement of well-obturated endodontic treatment that has lasted more than three months solely because of suspicions of microleakage. It may be prudent in such cases to make a new coronal restoration immediately and to observe the tooth for at least three months before placing the permanent crown.

Potential systematic error in laboratory experiments on microbial leakage through filled root canals: review of published articles

AIM

To systematically evaluate whether published studies on microbial leakage through filled root canals in human teeth embedded in a two-chamber system were properly controlled. Specifically, the control for the assumption that leakage should occur through the root canal rather than other routes was investigated.

METHODOLOGY

A systematic search was conducted using Medline, Biosis, Cochrane, Embase, and Web of Science databases. In addition, the reference lists of review articles pertaining to the topic were searched. No language restriction was applied. Two independent reviewers screened titles and abstracts. All articles deemed appropriate by either reviewer were included in the full-text evaluation. In case of disagreement, a referee arbitrated between the reviewers.

RESULTS

With 93.8% agreement prior to discussion and arbitration, 67 articles were included. On average, the size of the negative control group was 30% (mean) of the n in the experimental groups (minimum=0.0%, maximum=100%, SD=27%). The majority of studies (57 of 67) used inadequate negative controls. The whole root was covered with the sealing material in these specimens, whilst the root tip was left uncovered in the experimental groups. Consequently, leakage between outer root surface and sealing material was not controlled for. The authors of the remaining 10 communications did not state clearly how negative control assessments were performed.

CONCLUSIONS

Experimental investigations should be performed to assess the routes of microbial leakage in two-chamber models.

In vitro study to compare the coronal microleakage of Tempit UltraF, Tempit, IRM, and Cavit by using the fluid transport model

An adequate coronal seal is critical for the success of root canal therapy. The purpose of this study was to assess and compare the coronal microleakage of 4 temporary filling materials used to seal the access cavity in root canal treated teeth. Standardized access cavities were prepared in 55 extracted human, single canal teeth. They were instrumented by using a crown-down method to a size 45 file. The smear layer was removed with a 1-minute soak with 17% ethylenediaminetetraacetic acid followed by a 10-minute soak with 5.25% NaOCl and dried with paper points. All roots were obturated with gutta-percha and AH Plus sealer by using the continuous wave of condensation technique. The teeth were randomly divided into 4 groups of 10 teeth, with the remaining teeth serving as positive and negative controls. The access openings of the teeth in the experimental groups were filled with 4 mm of Cavit, IRM, Tempit, or Tempit-Ultra-F. All teeth were stored in 100% humidity at 37 degrees for 10 days, allowing sealer to set before testing. After thermocycling for 500 cycles (5 degrees C-55 degrees C), microleakage was measured by using the fluid transport model at 10 psi. All materials tested leaked. Kruskal-Wallis and Mann-Whitney U analysis indicated significantly less leakage (P < .05) with Tempit UltraF compared with Cavit and IRM. There were no statistically significant differences between Tempit Ultra-F and Tempit or between Cavit, IRM, and Tempit.

Bacterial microleakage of barrier materials in obturated root canals

The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarboxylate cement, resin modified glass ionomer cement, and flowable composite resin) used as a base over obturated root canals were evaluated during a 5-month period. Sixty single-rooted mandibular premolars were obturated with cold lateral compaction of gutta-percha. The teeth were randomly divided into five groups of 10 teeth each and positive and negative control groups of five. The access openings were filled with one of the tested barrier materials in four groups. In group 5, no barrier material was placed. Samples were incorporated in a model system using Staphylococcus epidermidis as a microbial marker. Results were analyzed with Kaplan-Meier survival analysis (p = 0.05). The sealing ability of all tested materials was better when compared with group 5 (no barrier material) (p < 0.05). Within the limitations of this study, the glass ionomer cement leaked significantly less when compared with the flowable composite resin (p < 0.05).

Effect of Orifice Plugs on Periapical Inflammation in Dogs

Gutta-percha (G) and sealer do not resist coronal leakage. In this study, the effect of orifice plugs using dentin-bonding/composite resin(C) or IRM on coronal leakage was evaluated in vivo. Sixty-one premolar roots in three beagle dogs were instrumented and filled with G and AH 26(S), or G alone. The coronal 2 mm was replaced with C or IRM, or left untreated. The access cavities were kept open for 8 months, the dogs were killed and the periapical regions of the roots were histologically examined. Periapical inflammation was observed in 89% of the group without plugs, but in those with plugs, the occurrence was decreased to 39% (C + G + S), 38% (IRM + G + S) and 58% (C + G), respectively. Furthermore, severe inflammation was observed in 50% of the former group but only 0 to 17% of the latter. The substantial reduction in apical periodontitis by the use of coronal plug underscores the clinical importance of providing an additional barrier to coronal leakage in comparison to that provided by gutta-percha and sealer alone.

Preference of temporary restorations and spacers: a survey of Diplomates of the American Board of Endodontists

The purpose of this investigation was to survey Diplomates of the American Board of Endodontists to determine their preferences in temporary restorations used during and following endodontic therapy and if cotton pellets are used as spacers. The survey asked which primary temporary material was used in anterior and posterior teeth to close access openings. Also, the endodontists were asked if they preferred a double seal and if they used cotton pellets as spacers. Eighty percent (507 of 603) of the surveys were returned. Cavit was the temporary restoration of choice for both anterior and posterior teeth, 48% and 54%, respectively. The majority of Diplomates, 83%, placed a cotton pellet beneath the temporary restorations.

Does Hybridization of Intraradicular Dentin Really Improve Fiber Post Retention in Endodontically Treated Teeth?

This study tested the hypothesis that hybridization of intraradicular dentin eliminates interfacial gaps, thereby improving the coronal seal and retention of teeth restored with fiber posts. Post spaces were bonded with two types of fiber posts, using the corresponding etch-and-rinse adhesives and dual-cured resin cements. Longitudinal sections of the interfaces were examined for dentin hybridization in the coronal- and middle-thirds of the root canals. Resin replicas of these sections were evaluated for interfacial gap formation. Although intraradicular dentin hybridization was not compromised irrespective of whether the adhesives were light-cured before cementation, the universal occurrence of interfacial gaps along the hybrid layer surface or the post-cement interface reflects the challenge in bonding to post spaces with low compliance and high C-factors. The clinical success associated with bonded fiber posts is probably due predominantly to frictional retention.

Bacterial Leakage with Mineral Trioxide Aggregate or a Resin-Modified Glass Ionomer Used as a Coronal Barrier

The purpose of this study was to evaluate gray mineral trioxide aggregate (MTA), white MTA, and Fuji II LC cement as coronal barriers to bacterial leakage. Seventy-eight, matched, human teeth were obturated with gutta-percha. In group I, 18 pairs received a 3-mm barrier of gray or white MTA. In group II, 18 pairs received a 3-mm barrier of gray MTA or Fuji cement. Three pairs were used as positive (obturated without barrier) and negative (covered with epoxy resin) controls. A dual-chamber leakage model utilizing salivary microbes was used for the evaluation. Leakage was recorded when turbidity was observed. All controls behaved as expected. In group I, three gray MTA and three white MTA samples leaked. In group II, one gray MTA and three Fuji samples leaked. There was no statistically significant difference in leakage between gray and white MTA or gray MTA and Fuji at 30, 60, or 90 days. Gray and white MTA or Fuji II can be recommended as a coronal barrier for up to 3 months.

The use of glass ionomer cements in both conventional and surgical endodontics

The capacity to bond to dental tissues, especially to dentine, their long-term fluoride release and their biocompatibility make glass ionomer cements (GICs) advantageous for use in endodontics, as well as in restorative dentistry. This review provides information on the basic properties of GICs, such as adhesion, antimicrobial effects and biocompatibility, particularly as they relate to use in endodontics. Indications for the use of GICs in endodontics are orthograde root canal sealing, root-end filling, repair of perforations and root resorption defects, treatment of vertical fractures and maintenance of the coronal seal. The paper includes a review on each of these indications. It is concluded that in spite of the critical handling characteristics and the inconclusive findings regarding sealing ability and antimicrobial activity, there is substantial evidence to confirm their satisfactory clinical performance. Both soft tissue and bone compatibility make them suitable for use during endodontic surgery.