Biomechanical behavior of weakened roots restored with custom-made post-and-cores of glass fiber and polyetheretherketone

PURPOSE

To evaluate the influence of post type and mechanical aging on compression force resistance, fracture pattern, and stress distribution in weakened roots.

MATERIALS AND METHODS

Bovine roots were endodontically treated and widened-and randomly divided into 8 groups (n = 10) according to post type (prefabricated glass fiber post and customized anatomic glass fiber post, milled glass fiber post-and-core, and milled polyetheretherketone post-and-core) and mechanical aging (without and with mechanical aging). Three hundred thousand cycles of mechanical fatigue were performed and compression force resistance (N) was analyzed by two-way ANOVA and Tukey test (α = 0.05). Fracture patterns were reported and stress distribution was analyzed by finite elements analysis.

RESULTS

There was a significant effect of post type (p = 0.032) and mechanical aging (p = 0.009), but no double interaction (p = 0.879). Higher values were recorded in the milled glass fiber and polyetheretherketone post-and-core groups compared to the prefabricated glass fiber post groups, and no significant difference was found among anatomic glass fiber post groups and other groups. Reparable fractures were predominant in the milled glass fiber and polyetheretherketone post-and-core groups. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.

CONCLUSIONS

Post type and mechanical aging influence the compression force resistance and fracture pattern of weakened roots. Milled glass fiber and polyetheretherketone post-and-cores exhibited higher compression force resistance and more reparable fractures compared to prefabricated glass fiber posts. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.

Quantitative analysis of culturable bacteria, levels of endotoxins, inflammatory mediators, and substance P in teeth with symptomatic irreversible pulpitis and in teeth with vital normal pulp tissues

AIM

To comparatively analyse the levels of culturable bacteria, endotoxins (LPS), tumour necrosis factor-alpha (TNF-α), interleukin-1 beta IL-1β and substance P in teeth with symptomatic irreversible pulpitis (SIP) and vital normal pulp (VNP) tissues.

METHODOLOGY

Thirty-two patients were included (20 teeth with SIP and 12 teeth with VNP tissues) in this cross-sectional study. Samples were collected from the full length of the root canals (microbial analysis) and periapical tissues (2 mm beyond the apex for immunological analysis), using sterile absorbent paper points. The levels of culturable bacteria (culture method), endotoxins (LAL Pyrogent 5000), TNF-α, IL-1β and substance P (ELISA) were assessed. The Mann-Whitney test was used for comparisons between the levels of CFU/mL, LPS, TNF-α, IL-1β and substance P in the SIP and VNP groups. The statistical analysis was performed with the significance level set at 5%.

RESULTS

Culturable bacteria were recovered from all teeth with SIP. On the other hand, no positive cultures were observed in the VNP tissues group (P > 0.05). The levels of LPS were approximately 4 times higher in teeth with SIP than in teeth with VNP tissues (P < 0.05). Higher levels of TNF-α and substance P were detected in teeth with SIP (P < 0.05). On the other hand, no difference in the levels of IL-1β was detected between the two groups (P > 0.05).

CONCLUSION

Teeth with symptomatic irreversible pulpitis present higher levels of culturable bacteria, endotoxins, TNF-α and substance P than those with vital normal pulp tissues. On the other hand, the levels of IL-1β were similar in teeth from both groups suggesting reduced implications of this inflammatory mediator in the early stages of infection.

Chemomechanical preparation influences the microbial community and the levels of LPS, LTA and cytokines in combined endodontic-periodontal lesions: A clinical study

BACKGROUND

This study was conducted to compare the microbiomes, the levels of lipopolysaccharides (LPS), lipoteichoic acid (LTA), and cytokines (interleukin [IL]-1β and tumor necrosis factor-alpha [TNF-α]), before and after chemomechanical preparation (CMP) of the root canals (RC) and their associated periodontal pockets (PP) in teeth with combined EPL.

MATERIALS

Samples were taken from 10 RC and PP, before and after CMP. The microbiomes (next-generation sequencing, V3-V4 hypervariable region of the 16S rRNA gene), microbiome diversity (bioinformatics analyses), LPS (limulus amebocyte lysate), LTA, IL-1β, and TNF-α (ELISA) were evaluated. A statistical analysis was performed with significance level set at 5%.

RESULTS

The most abundant phyla in both sites were Firmicutes and Proteobacteria. Comparative studies of bacterial genera species revealed that some increased and others decreased after CMP at both sites. A 3% reduction in Gram-negative bacteria (RC) and a 4% increase in Gram-positive bacteria (PP) were detected. LPS levels were 4.4 times higher in PP than in the RC. LTA was detected in all samples investigated. Higher levels of IL-1β and TNF-α were detected in both sites at baseline. After CMP, LPS, LTA, IL-1β and TNF-α were reduced in both sites.

CONCLUSION

The microbial community in the RC and PP in teeth with combined EPL indicated a similarity between both sites. CMP effectively reduced the microbial load and the LPS levels from teeth with EPL, and consequently diminished the cytokine levels. The reduction in LTA levels in the RC and PP proved challenging.