Studies that take into account differences linked to the genetics of both patients and potential pathogens are likely to give better insight into the aetiology of periodontal diseases.

Cross-sectional and longitudinal studies identify the JP2 clone of Aggregatibacter actinomycetemcomitans as an aetiological agent of aggressive periodontitis (AgP) in adolescents of northwest African descent. To gain information on why a significant part of Moroccan adolescents show clinical signs of periodontal disease in the absence of this pathogen we performed comprehensive mapping of the subgingival microbiota of eight young Moroccans, four of whom were diagnosed with clinical signs of AgP. The analysis was carried out by sequencing and phylogenetic analysis of a total of 2717 cloned polymerase chain reaction amplicons of the phylogenetically informative 16S ribosomal RNA gene. The analyses revealed a total of 173 bacterial taxa of which 39% were previously undetected. The JP2 clone constituted a minor proportion of the complex subgingival microbiota in patients with active disease. Rather than identifying alternative aetiologies to AgP, the recorded infection history of the subjects combined with remarkably high concentrations of antibodies against the A. actinomycetemcomitans leukotoxin suggest that disease activity was terminated in some patients with AgP as a result of elimination of the JP2 clone. This study provides information on the microbial context of the JP2 clone activity in a JP2-susceptible population and suggests that such individuals may develop immunity to AgP.

The goal of this research was to assess the impact of orthodontic root movement on gingival recessions. Methods: Twelve consecutive adult patients with a mandibular incisor presenting buccal or lingual gingival recession and with the root positioned outside the alveolar bone were enrolled. The roots were moved toward the center of the alveolar process with a goal oriented segmented appliance. The following variables were measured at baseline and after orthodontic treatment: (1) recession depth, (2) recession width, and (3) recession area. In addition, pocket probing depth, keratinized tissue height, and changes in Miller's classification were registered. Results: The depth, width, and area of the gingival recessions were reduced in all patients without increased pocket probing depth. On average, the recession depth decreased with 23%, the width with 38%, and the recession area with 63% of the baseline value. All patients improved in Miller's classification from Class III and IV to Class I or II. Conclusions: Orthodontic correction of the root toward the center of the alveolar envelope consistently reduced gingival recessions. The changes in Miller's classification indicated improved prognosis for full root coverage with mucogingival surgery.

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