Fracture resistance of endodontically treated premolars with direct composite restorations

Suitability of Direct Resin Composites in Restoring Endodontically Treated Teeth (ETT)

(1) Background: The in vitro study aimed to investigate mechanical characteristics of resin composites and their suitability in direct restauration of endodontically treated teeth (ETT). (2) Methods: 38 endodontically treated premolars with occlusal access cavities were directly restored using the following resin composites and adhesives: Tetric Evo Ceram® + Syntac classic® (n = 10), Venus Diamond® + iBond Total-Etch® (n = 10), Grandio® + Solobond M® (n = 9), Estelite® Sigma Quick + Bond Force® (n = 9). After thermocycling, the elastic modulus, shear-bond-strength, fracture load (Fmax) and fracture mode distribution were evaluated. Statistical analysis: one-way ANOVA, t-test, Kruskal-Wallis test; p < 0.05. (3) Results: Grandio® showed the highest E-modulus (15,857.9 MPa) which was significant to Venus Diamond® (13,058.83 MPa), Tetric Evo Ceram® (8636.0 MPa) and Estelite® Sigma Quick (7004.58 MPa). The highest shear-bond-strength was observed for Solobond M® (17.28 MPa), followed by iBond® (16.61 MPa), Syntac classic® (16.41 MPa) and Bond Force® (8.37 MPa, p < 0.05). The highest fracture load (Fmax) was estimated for ETT restored with Venus Diamond® (1106.83 N), followed by Estelite® Sigma Quick (1030.1 N), Tetric Evo Ceram® (1029 N) and Grandio® (921 N). Fracture-mode distribution did not show any significant differences. (4) Conclusions: The observed resin composites and adhesives show reliable mechanical characteristics and seem to be suitable for direct restoration of endodontically treated teeth.

Current trend of restoration of endodontically treated teeth with extensive subgingival caries: A case series

Endodontically treated teeth (ETT) are structurally and esthetically compromised. Conventionally, after endodontic therapy, the tooth is restored with full-coverage crowns to improve their fracture resistance and ensure their long-term success rate. However, the tooth preparation required for these restorations can result in the significant loss of enamel and dentin. The periodontal health will be affected if the margin of prosthesis is extended subgingival. Restoring ETT using minimally invasive methods is an effective way to preserve the remaining tooth structure. This case series show cases restoration of four endodontically treated mandibular first molars with extensive subgingival caries restored with short fiber-reinforced composite resin (everX Posterior, GC Europe N.V. Interleuvenlaan, Leuven), with 2-year follow-up.

Effect of Conventional and Electronic Cigarettes Smoking on the Color Stability and Translucency of Tooth Colored Restorative Materials: An In Vitro Analysis

This in vitro study compared the effects of conventional and electronic cigarettes on the aesthetics (color stability and translucency) of two types of composite resins: micro and nano-hybrid. Methods: A total of 120 specimens from two different composite materials Filtek Z250 XT (Nano-hybrid, 3M) and Filtek Z250 (Micro-hybrid, 3M) were divided into four groups (n = 30); shade A2 was used. The samples were exposed to conventional and electronic cigarette smoke via a custom made chamber device. The color values and measurements were recorded using a spectrophotometer before and after the exposure. The color and translucency were evaluated using the three-dimensional CIE Lab. Results: There was a significant change in the color (ΔE) and the translucency parameter (TP) in all of the specimens exposed to electronic cigarettes and conventional cigarettes. The results showed that the highest ΔE mean is for the nano-hybrid composite exposed to conventional cigarettes with 1.74 ΔE while the same material is 0.64 under the electronic cigarettes and the difference is significant with (p < 0.05). The micro-hybrid composite data showed less changes in color under both exposures with 0.85 ΔE mean under the conventional cigarette smoke and 0.48 under the electronic cigarette smoke with (p < 0.004). Conclusions: The conventional cigarette smoke has more effect on the color stability of the composite resins than electronic cigarettes. From a clinical point of view, the effect of smoke exposure on the tested specimens’ color, for the time duration to which the specimens were exposed, were moderate (ΔE < 2). The micro-hybrid composites showed better color stability as compared to the nano-hybrid composites.

Traditional and minimally invasive access cavities in endodontics: a literature review

The aim of this review was to evaluate the effects of different access cavity designs on endodontic treatment and tooth prognosis. Two independent reviewers conducted an unrestricted search of the relevant literature contained in the following electronic databases: PubMed, Science Direct, Scopus, Web of Science, and OpenGrey. The electronic search was supplemented by a manual search during the same time period. The reference lists of the articles that advanced to second-round screening were hand-searched to identify additional potential articles. Experts were also contacted in an effort to learn about possible unpublished or ongoing studies. The benefits of minimally invasive access (MIA) cavities are not yet fully supported by research data. There is no evidence that this approach can replace the traditional approach of straight-line access cavities. Guided endodontics is a new method for teeth with pulp canal calcification and apical infection, but there have been no cost-benefit investigations or time studies to verify these personal opinions. Although the purpose of MIA cavities is to reflect clinicians' interest in retaining a greater amount of the dental substance, traditional cavities are the safer method for effective instrument operation and the prevention of iatrogenic complications.

Fracture resistance and stress distribution of repairing endodontically treated maxillary first premolars with severe non-carious cervical lesions

This study was to compare the influence of glass fiber post placement and crown restoration on endodontically treated maxillary first premolars with severe NCCLs using three-dimensional finite element analysis and fracture resistance testing. G1, intact teeth. G2, teeth with artificial defect. G3, composite resin (CR). G4, CR and fiber post in buccal canal (FPB). G5, CR and fiber post in palatal canal (FPP). G6, CR and fiber posts in buccal and palatal canals (FPBP). G7, CR and crown (C). G8, CR, FPB, C. G9, CR, FPP, C. G10, CR, FPBP, C. Teeth in G2, G3, and G5 showed a similar stress concentration at the tip of the defect. The fracture resistance of G2 did not differ significantly from G3 and G5 (p>0.05) but differed significantly from that in other groups (p<0.05). The fractures in G4 were more favorable, and the difference of those in G1 from those in G7, G8, G9, and G10 was statistically significant (p<0.05). Restoration of root-filled maxillary premolars with severe NCCLs using fiber post in the buccal canal may be more efficacious than other restoration methods.

Microtensile bond strength of bulk-fill restorative composites to dentin

BACKGROUND

To facilitate the easier placement of direct resin composite in deeper cavities, bulk fill composites have been introduced. The Mechanical stability of fillings in stress bearing areas restored with bulk-fill resin composites is still open to question, since long term clinical studies are not available so far. Thus, the objective of the study was to evaluate and compare the microtensile bond strength of three bulk-fill restorative composites with a nanohybrid composite.

MATERIAL AND METHODS

Class I cavities were prepared on sixty extracted mandibular molars. Teeth were divided into 4 groups (n= 15 each) and in group I, the prepared cavities were restored with nanohybrid (Filtek Z250 XT) restorative composite in an incremental manner. In group II, III and IV, the bulk-fill composites (Filtek, Tetric EvoCeram, X-tra fil bulk-fill restoratives) were placed as a 4 mm single increment and light cured. The restored teeth were subjected to thermocycling and bond strength testing was done using instron testing machine. The mode of failure was assessed by scanning electron microscope (SEM). The bond strength values obtained in megapascals (MPa) were subjected to statistical analysis, using SPSS/PC version 20 software.One-way ANOVA was used for groupwise comparison of the bond strength. Tukey's Post Hoc test was used for pairwise comparisons among the groups.

RESULTS

The highest mean bond strength was achieved with Filtek bulk-fill restorative showing statistically significant difference with Tetric EvoCeram bulk-fill (p< 0.003) and X-tra fil bulk-fill (p<0.001) composites. Adhesive failures are mostly observed with X-tra fil bulk fill composites, whereas mixed failures are more common with other bulk fill composites.

CONCLUSIONS

Bulk-fill composites exhibited adequate bond strength to dentin and can be considered as restorative material of choice in posterior stress bearing areas. Key words:Bond strength, Bulk-fill restoratives, Configuration factor, Polymerization shrinkage.

Comparison of fracture resistance of endodontically treated teeth restored with nanohybrid, silorane, and fiber reinforced composite: An in vitro study

BACKGROUND

The present study was undertaken to evaluate the most suitable restorative for badly mutilated endodontically treated teeth.

AIMS

To evaluate and compare the fracture resistance of endodontically treated premolars restored with conventional nanohybrid, silorane composite with glass fibers and newer fiber-reinforced composite in mesio-occluso-distal (MOD) cavities.

MATERIALS AND METHODS

Sixty extracted human maxillary premolars were selected. Fifteen intact teeth served as positive controls (Group 1). Endodontic therapy was done in the remaining 45 teeth. MOD cavities were prepared in all the teeth with standardized dimensions and were randomly divided into three groups (Group 2 - nanohybrid + glass fibers, Group 3 - silorane + glass fibers, and Group 4 - fiber-reinforced composite). Restorations were done for all groups. Fracture resistance was measured by Instron universal testing machine.

STATISTICAL ANALYSIS USED

One-way anova test and Tukey's post hoc test.

RESULTS

Highest fracture resistance was shown by intact teeth group followed by fiber-reinforced composite, nanohybrid, and silorane, respectively. Statistically Significant difference was revealed by anova test (P < 0.0001) and Tukey's post hoc test (P < 0.0001).

CONCLUSIONS

Among the experimental groups, fiber-reinforced composite showed the highest fracture resistance. Statistically significant difference was observed for all the groups.

Stability of endodontically treated teeth with differently invasive restorations: Adhesive vs. non-adhesive cusp stabilization

OBJECTIVES

Aim of the present study was to evaluate fracture strength of endodontically treated molars with different preparations/restorations after thermomechanical loading in vitro.

METHODS

264 extracted human third molars were used. Beside the control group, 256 teeth in 32 test groups (n=8) received root canal treatment (MTwo #40/.6) and root canal obturation with AH Plus and Guttapercha. After postendodontic sealing and build-up (Syntac, SDR), specimens were additionally prepared MO or MOD. Postendodontic restorations were: Direct restorations (Tetric EvoCeram Bulk Fill bonded with Syntac; as filling or direct partial crown (PC) after reducing the cusps 3mm; amalgam as filling or direct pin-retained partial crown (PC)), vs. indirect adhesive restorations (I: Inlay vs. PC; IPS Empress I/PC; Celtra Duo I/PC; e.max CAD I/PC; Lava Ultimate I/PC; Enamic I/PC - all inserted with Syntac/Variolink) vs. cemented cast gold I/PC. After 300,000 thermocycles (5/55°C) and 1.2 Mio. 100N load cycles, specimens were loaded until fracture.

RESULTS

Whereas IPS Empress showed no difference between I and PC (p>0.05), in all other groups PC were significantly more stable than fillings/inlays (p<0.05), this effect was more pronounced after MOD preparations. Cast gold PC exhibited the highest fracture strengths (p<0.05), inlays the lowest (p<0.05). IPS Empress was generally inferior to the other bonded materials under investigation (p<0.05) which as PC almost reached the level of control specimens. Amalgam fillings showed the worst outcome (p<0.05).

SIGNIFICANCES

Less invasive preparation designs were not beneficial for the stability of postendodontic restorations. Except for IPS Empress, PC were generally more successful in restabilization of weakened cusps after endodontic treatment and preparation. Cast gold PC remain the ultimate stabilization tool for ETT in terms of fracture resistance.