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Free D-amino acids (D-AAs) are one of the most striking features of the peptidoglycan composition in bacteria and play a key role in regulating and disassembling bacterial biofilms. Previous studies have indicated that the antimicrobial peptide nisin can inhibit the growth of the cariogenic bacteria Streptococcus mutans. The present study investigated the effect of free amino acids either alone or in combination with nisin on biofilm and on planktonic S. mutans bacteria. The results of the MIC and MBC analyses showed that D-cysteine (Cys), D- or L-aspartic acid (Asp), and D- or L-glutamic acid (Glu) significantly improve the antibacterial activity of nisin against S. mutans and that the mixture of D-Cys, D-Asp, and D-Glu (3D-AAs) and the mixture of L-Cys, L-Asp, and L-Glu (3L-AAs) at a concentration of 40 mM can prevent S. mutans growth. Crystal violet staining showed that the D- or L-enantiomers of Cys, Asp, and Glu at a concentration of 40 mM can inhibit the formation of S. mutans biofilms, and their mixture generated a stronger inhibition than the components alone. Furthermore, the mixture of the three D-AAs or L-AAs may improve the antibacterial activity of nisin against S. mutans biofilms. This study underscores the potential of free amino acids for the enhancement of the antibacterial activity of nisin and the inhibition of the cariogenic bacteria S. mutans and biofilms. [ABSTRACT FROM AUTHOR]

Free D-amino acids (D-AAs) are one of the most striking features of the peptidoglycan composition in bacteria and play a key role in regulating and disassembling bacterial biofilms. Previous studies have indicated that the antimicrobial peptide nisin can inhibit the growth of the cariogenic bacteria Streptococcus mutans. The present study investigated the effect of free amino acids either alone or in combination with nisin on biofilm and on planktonic S. mutans bacteria. The results of the MIC and MBC analyses showed that D-cysteine (Cys), D- or L-aspartic acid (Asp), and D- or L-glutamic acid (Glu) significantly improve the antibacterial activity of nisin against S. mutans and that the mixture of D-Cys, D-Asp, and D-Glu (3D-AAs) and the mixture of L-Cys, L-Asp, and L-Glu (3L-AAs) at a concentration of 40 mM can prevent S. mutans growth. Crystal violet staining showed that the D- or L-enantiomers of Cys, Asp, and Glu at a concentration of 40 mM can inhibit the formation of S. mutans biofilms, and their mixture generated a stronger inhibition than the components alone. Furthermore, the mixture of the three D-AAs or L-AAs may improve the antibacterial activity of nisin against S. mutans biofilms. This study underscores the potential of free amino acids for the enhancement of the antibacterial activity of nisin and the inhibition of the cariogenic bacteria S. mutans and biofilms. [ABSTRACT FROM AUTHOR]

Objectives: This review was undertaken to answer a controversial clinical question with high-quality evidence: When severely damaged teeth are restored, which type of post (metal or fiber) demonstrates superior clinical performance?, Data Sources: The meta-analysis was conducted according to the guidelines in the Cochrane handbook. Electronic databases (MEDLINE, EMBASE, CENTRAL) and gray literatures were screened up to January 2018. Only randomized controlled trials (RCTs) with follow-up of at least 3 years were included. The quality of included studies was assessed by the Cochrane Collaboration's tool. Meta-analysis compared survival, success, post debonding, and root fracture incidence of teeth restored with fiber and metal posts. The GRADE system (Grading of Recommendations, Assessment, Development and Evaluations) was used to assess the strength of the evidence. Of 1,511 records, 14 full texts were obtained. Only four RCTs with follow-up times of 3 to 7 years met the selection criteria. The methodologic quality of included RCTs was low risk of bias. Fiber posts presented significantly higher survival rates than did metal posts (RR 0.57, 95% CI: 0.33 to 0.97, P = .04), while no difference was observed in success rates, post debonding rates, or root fracture rates. The GRADE assessment indicated a high quality of evidence for survival rates and a moderate quality for success rates., Conclusion: It was concluded that fiber posts displayed higher medium-term (3 to 7 years) overall survival rates than did metal posts when used in the restoration of endodontically treated teeth with no more than two coronal walls remaining.

Objective: To evaluate the effect of core ceramic surface treatment on the failure behaviors of two bilayered all- ceramic structures., Methods: Lithium disilicate glass-ceramic (LDG, IPS e.max Press) and Zirconia(Cercon) specimens were divided into 4 groups(n=12) according to the following surface treatment methods: ground successively to 1 000(group A), 600(group B) and 320(group C) grit silicon carbide(SiC) papers and sandblasted with 110 µm aluminum oxide particle(group D, as control). Surface roughness was measured using a profilometer. After veneer sintering, the flexural strength σ was measured with biaxial flexure test and the reliability of strength was analyzed with Weibull distribution. Failure modes and fractographic patterns were analyzed by optical stereo and scanning electron microscopy (SEM)., Results: For LDG, no significant difference was found for the flexural strength values among groups (F=0.406, P=0.750). No significant difference was found in Weibull modulus among groups(the confidence bounds overlapped with each other). SEM and optical stereo observation results showed that all the bilayered LDG specimens failed cohesively. For zirconia, Mean flexural strength values were (541 ± 75), (533 ± 73), (529 ± 78) and (640 ± 95) MPa for groups A, B, C and D, respectively, and group D demonstrated a significantly higher flexural strength compared to the other three groups(P<0.05). No significant difference were found among groups(the confidence bounds overlapped with each other). Specimens in all groups failed mainly adhesively, while those in group D presented lower percentage of adhesive failure., Conclusions: Core ceramic surface treatment has no influence on the failure behaviors of LDG based bilayered structures. Sandblasting can increase the flexural strength of bilayered zirconia structures by reducing the incidence of delamination.