Continuing cariogenic bacterial growth demineralizing dentine beneath a composite filling is the most common cause of tooth restoration failure. Novel composites with antibacterial polylysine (PLS) (0, 4, 6, or 8 wt%) in its filler phase were therefore produced. Remineralising monocalcium phosphate was also included at double the PLS weight. Antibacterial studies involved set composite disc placement in 1% sucrose-supplemented broth containing Streptococcus mutans (UA159). Relative surface bacterial biofilm mass (n = 4) after 24 h was determined by crystal violet-binding. Live/dead bacteria and biofilm thickness (n = 3) were assessed using confocal laser scanning microscopy (CLSM). To understand results and model possible in vivo benefits, cumulative PLS release from discs into water (n = 3) was determined by a ninhydrin assay. Results showed biofilm mass and thickness decreased linearly by 28% and 33%, respectively, upon increasing PLS from 0% to 8%. With 4, 6, and 8 wt% PLS, respectively, biofilm dead bacterial percentages and PLS release at 24 h were 20%, 60%, and 80% and 85, 163, and 241 μg/disc. Furthermore, initial PLS release was proportional to the square root of time and levelled after 1, 2, and 3 months at 13%, 28%, and 42%. This suggested diffusion controlled release from water-exposed composite surface layers of 65, 140, and 210 μm thickness, respectively. In conclusion, increasing PLS release initially in any gaps under the restoration to kill residual bacteria or longer-term following composite/tooth interface damage might help prevent recurrent caries.

Objective Evaluate the effects of typical clinical concentration (1,000 mg/mL), low concentration (1 mg/mL) triple antibiotic pastes (TAP), and double antibiotic pastes (DAP) on the bond strength between various root cements and radicular dentin. Materials and Methods Intact single-rooted human teeth (n = 144) were horizontally decoronated and canals instrumented. The roots were treated for 4 weeks with Ca(OH)2, 1,000 mg/mL of TAP or DAP, and 1 mg/mL of TAP or DAP. Untreated roots served as a control. After treatment, the medicaments were irrigated and each group was divided into three subgroups receiving MTA, Biodentine, or Endosequence putty cement. After 2 weeks, coronal and middle root cylinders were obtained from each root. Push-out bond strength test and failure analysis were performed for all root cylinders. Statistical Analysis  Three-way ANOVA, pairwise comparisons and logistic regression were used for statistical analyses. A significance level of 5% was used. Results  For MTA applied in the coronal part of the roots, 1 mg/mL DAP and TAP and Ca(OH)2 demonstrated significantly higher bond strength compared with the typical clinical concentration and the control groups. For Biodentine applied coronally in the roots, 1 mg/mL of DAP resulted in significantly higher bond strength than all other groups. For Endosequence putty cement applied coronally in the roots, 1 mg/mL of DAP offered significantly higher bond strength than all groups except for Ca(OH)2. Conclusion The use of 1 mg/mL DAP resulted in significantly higher push-out bond strength compared with the typical clinical concentration of TAP and DAP regardless of the type of the root cement used.

Objectives Matrix metalloproteinase (MMP) enzymes participate in collagen matrix degradation, including in dentine, potentially compromising bond strength. Therefore, MMP inhibitors have been hypothesized to improve restoration bond strength and stability. This systematic review aimed to evaluate the influence of different MMP inhibitors applied as dentine surface pretreatments on the immediate (24 hours) and longer term (months) bond strength of direct coronal composite restorations. Materials and Methods This systematic literature review followed the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) statement. A systematic literature search of three databases (Ovid MEDLINE, Ovid Embase, and Google Scholar) was conducted independently by two reviewers from inception to April 2022. An adapted quality assessment tool was independently applied by two reviewers for risk of bias assessment. Statistical Analysis RevMan v5.4 software was used for meta-analyses. A random-effects model was used to generate mean differences with 95% confidence intervals for treatment and control comparisons. The Q-test and I2 -test were used to test for heterogeneity. The proportion of total variance across studies attributable to heterogeneity rather than chance was calculated. Overall effects were tested using the Z-test, while subgroup differences were tested using Chi-squared tests. Results Of 934 studies, 64 studies were included in the systematic review and 42 in the meta-analysis. Thirty-one MMP inhibitors were reported, three of which were included in the meta-analysis: 2% chlorhexidine (CHX), 0.3 M carbodiimide (EDC), and 0.1% riboflavin (RIBO). Pretreatment with 2% CHX for 30 and 60 seconds did not significantly improve bond strength compared with controls either immediately or after long-term ageing. However, pretreatment with 0.3 M EDC and 0.1% RIBO (but not CHX) significantly improved bond strength compared with control groups both immediately and over time. Most studies showed a medium risk of bias. Conclusions These in vitro findings pave the way for rationale clinical trialing of dentine surface pretreatment with MMP inhibitors to improve clinical outcomes.