Evaluation of different fibers and biodentine as alternates to crown coverage for endodontically treated molars: An in vitro study

Comparative evaluation of marginal adaptation and fatigue resistance of endodontically treated premolars restored with direct and indirect coronal restorations: an in vitro study

BACKGROUND

An optimum restoration for reconstructing endodontically treated teeth should provide excellent marginal adaptation, high fracture resistance as well as maximum tooth structure conservation. The purpose of this study was to evaluate the marginal adaptation and fatigue resistance of different coronal restorations in endodontically treated premolars.

METHODS

Thirty sound maxillary first premolars were endodontically treated and received MOD cavities. Teeth were randomly allocated into three groups (n = 10) according to the type of coronal restoration: Group R: polyethylene fibers (ribbond), fibers-reinforced composite (everX posterior) and final layer of nano-hybrid composite. Group O: indirect lithium disilicate overlay and Group C: fiber-post, resin composite restoration, and lithium disilicate crown. Marginal gap assessment was performed before and after thermocycling (5000 cycles) using stereomicroscope. Samples were subjected to stepwise-stress loading starting at 200 N, and increased by 100 N in each step until failure occurred. Statistical analysis was done by One-way ANOVA followed Tukey`s Post Hoc test for multiple comparison. Paired t test was used to compare the marginal adaptation before and after thermocycling. Survival probability was evaluated by Life table survival analysis. Failure mode analysis was performed with Chi-square test.

RESULTS

Marginal gap was significantly the lowest in group R (37.49 ± 5.05) and (42.68 ± 2.38), while being the highest in group C (59.78 ± 5.67) and (71.52 ± 5.18) in before and after thermocycling respectively (P < 0.0001). Fatigue resistance was the highest for group O (1310.8 ± 196.7), and the lowest for group R (905.4 ± 170.51) with a significant difference between groups (P < 0.0001). Crown group had the highest percentage (80%) of catastrophic failure, while, overlay group exhibited the lowest (20%).

CONCLUSIONS

Direct restoration without cuspal coverage using ribbon fibers with short FRC provided better marginal adaptation than indirect overlays and crowns, but fatigue resistance wasn't significantly improved. Adhesive ceramic overlays showed the best fatigue performance and the least catastrophic failure rate compared to both direct fiber-reinforced composite and indirect ceramic full coverage restorations.

CLINICAL SIGNIFICANCE

Indirect adhesive overlays are a suitable, more conservative restorative option for endodontically treated teeth than full coverage restorations, especially when tooth structure is severely compromised.

Fracture Load of Mesio-Occluso-Distal Composite Restorations Performed with Different Reinforcement Techniques: An In Vitro Study

BACKGROUND

Mesio-occluso-distal (MOD) cavity preparations are often fragile due to the amount of tooth and carious structure removed. MOD cavities can often fracture if left unsupported.

AIM

The study investigated the maximum fracture load of mesi-occluso-distal cavities restored using direct composite resin restorations with various reinforcement techniques.

METHOD

Seventy-two freshly extracted, intact human posterior teeth were disinfected, checked, and prepared according to predetermined standards for mesio-occluso-distal cavity design (MOD). The teeth were assigned randomly into six groups. The first group was the control group restored conventionally with a nanohybrid composite resin (Group I). The other five groups were restored with a nanohybrid composite resin reinforced with different techniques: the ACTIVA BioACTIVE-Restorative and -Liner as a dentin substitute and layered with a nanohybrid composite (Group II); the everX Posterior composite resin layered with a nanohybrid composite (Group III); polyethylene fibers called "Ribbond" placed on both axial walls and the floor of the cavity, and layered with a nanohybrid composite (Group IV); polyethylene fibers placed on both axial walls and the floor of the cavity, and layered with the ACTIVA BioACTIVE-Restorative and -Liner as a dentin substitute and nanohybrid composite (Group V); and polyethylene fibers placed on both axial walls and the floor of the cavity and layered with the everX posterior composite resin and nanohybrid composite (Group VI). All teeth were subjected to thermocycling to simulate the oral environment. The maximum load was measured using a universal testing machine.

RESULTS

The highest maximum load was exhibited by Group III with the everX posterior composite resin, followed by Group IV, Group VI, Group I, Group II, and Group V. A statistically significant difference was demonstrated between groups (p = 0.0023). When adjusting for multiple comparisons, there were statistical differences specific to comparisons between Group III versus I, Group III versus II, Group IV versus II, and Group V versus III.

CONCLUSIONS

Within the limitations of the current study, it can be concluded that a higher maximum load resistance can be achieved (statistically significant) when reinforcing nanohybrid composite resin MOD restorations with everX Posterior.

Comparative Evaluation of Two Different Fiber-Reinforced Composite Materials in Class 1 Post-Endodontic Restorations in Molars-A Randomized Clinical Study

This study aimed to evaluate and compare two different fiber-reinforced composite materials in class I post-endodontic restoration in molars. A total of 50 patients were randomly assigned into two groups (n = 25 for each group); group A: everX Posterior (packable composite) with a top layer of solareX (nano-hybrid composite) and group B: everX Flow (flowable composite) with a top layer of G-aenial universal injectable (flowable composite). Patients were evaluated immediately after the procedure (baseline), at 6 months, and at 1 year time intervals based on the modified USPHS criteria. The statistical analysis using a chi-square test showed no statistically significant difference in the clinical performance of group A and group B. Clinical performance of the combination of everX Flow with overlying G-aenial universal injectable composite proved to be comparable with everX Posterior with overlying solareX composite as post-endodontic restorations in class I lesions in permanent molars.

Evaluation of titanium mesh and fibers in reinforcing endodontically treated molars: An in vitro study

Aim/Objective:

We aimed to evaluate the fracture resistance of titanium mesh and fibers that could aid as a substitute for crown coverage.

Materials and Methodology:

Forty extracted human mandibular molar teeth were selected for this study and were divided into four groups (n = 10). Access cavity preparation was done in all experimental teeth (Groups 2–4) maintaining 1.2–1.5 mm diameter of tooth structure around the circumference to mimic the structural loss of teeth due to the extent of dental caries. Group 1 consisted of intact teeth which were assigned as control. Group 2 was reinforced with titanium mesh. Group 3 was reinforced with glass fiber. Group 4 was reinforced with polyethylene fiber. The access cavities in all the experimental teeth were later filled with nanohybrid composite and were subjected to fracture resistance using a universal testing machine.

Results:

The results of the study were evaluated statistically using the Kruskal–Wallis test. There was no statistically significant difference among the experimental and control groups.

Conclusion:

Within the constraint of this in vitro study, an inference can be given that fiber-reinforced composite and titanium mesh could rule out the mandatory procedure of crown placement for endodontically treated molars.

Effect of Fiber Reinforcement Type on the Performance of Large Posterior Restorations: A Review of In Vitro Studies

To reinforce extensively prepared cavities, different types of fiber reinforcement are utilized. Polyethylene and glass fibers are the most commonly used fibers in that purpose; each type has its own advantages over the other type. Therefore, the aim of this study is to review the literature to evaluate and compare the influence of different fiber reinforcement types on the performance of posterior large composite restorations. Two independent authors performed a comprehensive literature search using MEDLINE/PubMed, Google Scholar, and a manual search for cross references until July 2021. Authors selected only studies that contain comparisons between glass (continuous or short) and polyethylene (woven) fiber-reinforced composites (FRCs) in posterior cavities of human teeth, and that report the effect of fiber inclusion on fracture resistance, microleakage, and marginal adaptation of restorations. A number of 2711 potentially relevant articles were obtained from the electronic search. After extensive assessment, 2696 articles were ineligible to be included in the review, and only 15 articles met the inclusion criteria. Four out of nine studies, which tested the fracture resistance of FRC restorations, revealed similar performance of the glass and polyethylene fibers. The rest of the studies (n = 5) revealed statistically significant differences between the two types of fiber reinforcement, with the majority showed superior reinforcement of glass fiber. Moreover, the reviewed studies revealed that, using fibers within the composite restorations would reduce the microleakage and improve the marginal adaptation of the restoration regardless of the fiber type. FRCs tend to strengthen the restorations of structurally compromised teeth and improve their performance compared to plain composite restorations.

Effect of Smart Dentin Replacement, Biodentine, and Its Combination for Dentin Replacement as Alternatives to Full-crown Coverage for Endodontically Treated Molars: An In Vitro Study

Aim:

The aim of this in vitro study was to assess newer dentin replacement restorative materials that could substitute full-crown coverage restoration.

Materials and Methods:

Twenty freshly extracted maxillary and mandibular molars were selected for this in vitro study and were randomly divided into four groups of five teeth each. All the teeth in the experimental groups (Groups 2–4) were subjected to access cavity preparation, mimicking class 1 deep dentinal caries without involving marginal ridges, and with approximately 1.5 mm of tooth structure remaining throughout its circumference. Group 1: sound molar teeth, which will serve as a control group. Group 2: endodontically treated molars restored with smart dentin replacement (SDR) as post-endodontic restoration. Group 3: endodontically treated molars restored with Biodentine as post-endodontic restoration. Group 4: endodontically treated molars restored with the combination of SDR and Biodentine as the post-endodontic restoration. Fracture resistance of all the teeth was then evaluated using a universal testing machine.

Statistical Analysis:

The results of this in vitro study were calculated statistically using one-way analysis of variance and post hoc tests such as Tukey’s, Scheffe’s, Bonferroni, and Holm tests for intragroup comparison.

Results:

Statistically significant results were observed among all groups, except Group 2 (SDR) and Group 4 (combination of SDR and Biodentine). The highest and lowest values were noted with Groups 2 and 3, respectively, (P = 0.05).

Conclusion:

SDR alone or the combination of SDR with Biodentine can be considered as a substitute for full-crown coverage restoration for endodontically treated molars.

Gingival-derived mesenchymal stem cells: An endless resource for regenerative dentistry

The gingiva, the masticatory portion of the oral mucosa, is excised and discarded frequently during routine dental treatments and following tooth extraction, dental crown lengthening, gingivectomy and periodontal surgeries. Subsequent to excision, healing eventually happens in a short time period after gingival surgery. Clinically, the gingival tissue can be collected very easily and, in the laboratory, it is also very easy to isolate gingival-derived mesenchymal stem cells (GMSCs) from this discarded gingival tissue. GMSCs, a stem cell population within the lamina propria of the gingival tissue, can be isolated from attached and free gingiva, inflamed gingival tissues, and from hyperplastic gingiva. Comparatively, they constitute more attractive alternatives to other dental-derived mesenchymal stem cells due to the availability and accessibility of gingival tissues. They have unique immunomodulatory functions and well-documented self-renewal and multipotent differentiation properties. They display positive signals for Stro-1, Oct-4 and SSEA-4 pluripotency-associated markers, with some co-expressing Oct4/Stro-1 or Oct-4/SSEA-4. They should be considered as the best stem cell source for cell-based therapies and regenerative dentistry. The clinical use of GMSCs for regenerative dentistry represents an attractive therapeutic modality. However, numerous biological and technical challenges need to be addressed prior to considering transplantation approaches of GMSCs as clinically realistic therapies for humans.