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Aggressive periodontitis is characterized by a rapid and severe periodontal destruction in young systemically healthy subjects. A greater prevalence is reported in Africans and African descendent groups than in Caucasians and Hispanics. We first fine mapped the interval 1q24.2 to 1q31.3 suggested as containing an aggressive periodontitis locus. Three hundred and eighty-nine subjects from 55 pedigrees were studied. Saliva samples were collected from all subjects, and DNA was extracted. Twenty-one single nucleotide polymorphisms were selected and analyzed by standard polymerase chain reaction using TaqMan chemistry. Non-parametric linkage and transmission distortion analyses were performed. Although linkage results were negative, statistically significant association between two markers, rs1935881 and rs1342913, in the FAM5C gene and aggressive periodontitis (p = 0.03) was found. Haplotype analysis showed an association between aggressive periodontitis and the haplotype A-G (rs1935881-rs1342913; p = 0.009). Sequence analysis of FAM5C coding regions did not disclose any mutations, but two variants in conserved intronic regions of FAM5C, rs57694932 and rs10494634, were found. However, these two variants are not associated with aggressive periodontitis. Secondly, we investigated the pattern of FAM5C expression in aggressive periodontitis lesions and its possible correlations with inflammatory/immunological factors and pathogens commonly associated with periodontal diseases. FAM5C mRNA expression was significantly higher in diseased versus healthy sites, and was found to be correlated to the IL-1beta, IL-17A, IL-4 and RANKL mRNA levels. No correlations were found between FAM5C levels and the presence and load of red complex periodontopathogens or Aggregatibacter actinomycetemcomitans. This study provides evidence that FAM5C contributes to aggressive periodontitis.

Abstract Background The combination of systemic metronidazole (MTZ) and amoxicillin (AMX) with scaling and root planing (SRP) has shown to be an effective periodontal treatment. However, some essential issues associated with the use of these antibiotics remain unanswered, such as the ideal time of administration during the course of periodontal treatment. Although these agents are often prescribed after the healing phase of the SRP procedure, there is biological plausibility to support its use in conjunction with the mechanical treatment. However, to date, no placebo controlled randomized clinical trial (RCT) has directly compared these two protocols. Therefore, the aim of this RCT is to compare the clinical, microbiological and immunological effects of the adjunctive systemic MTZ + AMX administered in different phases of the treatment of severe periodontitis. Methods Subjects with severe periodontitis (n = 180) are being randomly assigned into three groups (n = 60/group): (i) SRP-only (control group), SRP in combination with 400 mg MTZ + 500 mg AMX, starting (ii) at the first SRP session (active phase group), or (iii) after 3 months of its completion (healing phase group). All volunteers are receiving clinical and microbiological evaluation at baseline, 3, 6 and 12 months, and immunological assessment at baseline and 12 months post-therapy. Nine subgingival biofilm samples are being collected per subject and analyzed for counts and proportions of 40 bacterial species by checkerboard DNA-DNA hybridization, and six gingival crevicular fluid samples are being collected and analyzed for the levels of 20 chemokines by multiplex immunoassay. The primary outcome variable is the number of volunteers reaching the clinical endpoint for treatment (≤ 4 sites with probing depth ≥5 mm) at 1 year post-therapy. Differences in clinical, microbiological and immunological parameters among groups and over time will be evaluated using analysis of variance, analysis of covariance and the Chi-square and Tukey tests. Microbiological and immunological analyses will be performed using adjustments for multiple comparisons. Statistical significance will be set at 5%. Trial registration ClinicalTrials.gov, NCT02954393. Registered on 3 November 2016.