Aim To evaluate an additional mechanical approach, a titanium brush, in the implant surface decontamination performed during the regenerative surgical therapy of peri‐implantitis. Material and Methods A randomized double‐blinded clinical trial, with a 1‐year follow‐up, was carried out. After a hygienic phase, peri‐implantitis‐affected implants were randomly assigned to a control or to a test group. In the control group, implant surface was decontaminated both mechanically and chemically with 3% H2O2 and plastic ultrasonic scalers, respectively, while in the test group, a titanium brush was also applied. Intrabony defects in both groups were filled with an alloplastic material (β‐tricalcium phosphate and hydroxyapatite) and covered with a collagen membrane. The primary outcome was the reduction in probing pocket depth (PPD) at the deepest site. Results Thirty patients were included, 15 in each group. At 12 months, reduction in PPD was 4.87 (standard deviation [SD] 1.55) mm and 2.85 (SD: 1.91) mm, respectively (p = 0.009). The correspondent figures for residual PPD were 3.6 (SD: 0.91) and 4.92 (SD: 1.26) mm, respectively (p = 0.007). Conclusions The additional use of a titanium brush during regenerative treatment of peri‐implantitis resulted in statistically significant benefits in terms of PPD reduction after 12 months.

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Introduction: Antibiotic resistance is widely found even among bacterial populations not having been exposed to selective pressure by antibiotics, such as tetracycline. In this study we analyzed the tetracycline-resistant subgingival microbiota of healthy subjects and of patients with periodontitis, comparing the prevalence of tet genes and their multidrug resistance profiles. Methods: Samples from 259 volunteers were analyzed, obtaining 813 tetracycline-resistant isolates. The prevalence of 12 antibiotic resistance genes was assessed, and multidrug profiles were built. Each isolate was identified by 16S rRNA sequencing. Differences in qualitative data and quantitative data were evaluated using the chi-square test and the Mann-Whitney-U test, respectively. Results: tet(M) was the most frequently detected tet gene (52.03%). We observed significant differences between the prevalence of tet(M), tet(W), tet(O), tet(32) and tet(L) in both populations studied. Multidrug resistance was largely observed, with resistance to kanamycin being the most detected (83.64%). There were significant differences between the populations in the prevalence of kanamycin, chloramphenicol, and cefotaxime resistance. Resistant isolates showed significantly different prevalence between the two studied groups. Conclusion: The high prevalence of multidrug resistance and tetracycline resistance genes found in the subgingival microbiota, highlights the importance of performing wider and more in-depth analysis of antibiotic resistance in the oral microbiota.

Objectives To study oral Prevotella spp. isolated from patients with chronic periodontitis, to determine their susceptibility to azithromycin and erythromycin and to screen the presence of macrolide resistance genes therein. Material and Methods Isolates with a Prevotella‐like morphology were obtained from subgingival samples of 52 patients with chronic periodontitis. Each isolate was identified to the species level by sequencing of the 16S rRNA gene. In 100 Prevotella spp. isolates, azithromycin and erythromycin susceptibility was determined using the E test method, and the screening of erm(A), erm(B), erm(C), erm(F), erm(G), erm(Q) and mef(A) genes was done by PCR. Results Prevotella intermedia and Prevotella nigrescens were the most identified species (33% each). Minimum inhibitory concentrations (MICs) ranges for both antibiotics were 0.016/0.032 to >256 μg/ml. MIC50 values for azithromycin and erythromycin were 1.5 and 1 μg/ml, respectively, and MIC90 values were >256 μg/ml for both antibiotics. Nineteen per cent of the isolates carried erm(B), and 51% carried erm(F). Conclusions The MIC values found were high compared to previous studies. erm(F) was greatly prevalent, and we describe for the first time the erm(B) gene in Prevotella spp. The presence of either of the genes seems to be associated with a higher degree of resistance to azithromycin and erythromycin.

Tetracycline resistance can be achieved through tet genes, which code for efflux pumps, ribosomal protection proteins and inactivation enzymes. Some of these genes have only been described in either Gram-positive or Gram-negative bacteria. This is the case of tet (B), which codes for an efflux pump and, so far, had only been found in Gram-negative bacteria. In this study, tet (B) was detected in two clinical Streptococcus oralis strains isolated from the gingival sulci of two subjects. In both cases, the gene was completely sequenced, yielding 100% shared identity and coverage with other previously published sequences of tet (B). Moreover, we studied the expression of tet (B) using RT-qPCR in the isolates grown with and without tetracycline, detecting constitutive expression in only one of the isolates, with no signs of expression in the other one. This is the first time that the presence and expression of the tet (B) gene has been confirmed in Gram-positive bacteria, which highlights the potential of the genus Streptococcus to become a reservoir and a disseminator of antibiotic resistance genes in an environment so prone to horizontal gene transfer as is the oral biofilm.