Background Knowledge on peri‐implantitis bone defect characteristics and predictors is still limited. Purpose To describe peri‐implantitis bone defect characteristics and identify possible predictors. Methods Various parameters at patient‐ (age, gender, smoking, and supra‐structure), implant‐ (surface, type, connection, platform, and misfit), and site level (region, alveolar ridge position, defect characteristics, neighboring structure) were recorded retrospectively. Results Among 193 implants, the most prevalent defects were class Ic (25.4%), and Id (23.8%); a previously non‐described category “class Id with only one bone wall” was frequently observed (11.9%). Mean intrabony defect depth and width ranged from 4.5 to 6.2 mm and from 2.7 to 2.9 mm, respectively; mean dehiscence extent ranged from 2.8 to 7.0 mm. A total of 37.8% of the defects presented horizontal bone loss and an intrabony component; in 52.7% of the implants, total defect extent was >6 mm. Jaw region, implant position within the alveolar ridge, and implant/abutment misfit showed significant associations either to defect configuration and/or defect extent. Conclusion (a) Most common peri‐implantitis defects exhibited a combination of intrabony component and a buccal/oral dehiscence, while purely circumferential defects were relatively seldom; (b) implants with defects with bone dehiscence were placed more frequently closer to the lateral aspect of the ridge harboring the dehiscence; (c) implants placed in the lower anterior region had the highest risk for more severe peri‐implant bone loss; and (d) peri‐implant bone defects with only a single bone wall appropriate for regenerative procedure were relatively frequent.

The set of EMD-regulated genes identified in this study offers the opportunity to clarify mechanisms underlying the effects of EMD on epithelial cells. Reduced epithelial repopulation of the dental root upon periodontal surgery may be the consequence of reduced migration and cell growth, as well as epithelial-to-mesenchymal transition.

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Miller's is the most commonly used classification of gingival tissue recessions, defined as the displacement of the soft tissue margin apical to the cemento-enamel junction. However, data on the reliability of this classification are missing so far, although reliability, which reflects the consistency of repeated measurements, is regarded as a prerequisite for judging the utility of a classification. The aim of the present study was to evaluate inter- and intra-observer agreement on Miller's classification of gingival tissue recessions. Two hundred photographs (50 of each region: maxillary/mandibular anterior/posterior teeth) of gingival tissue recessions were evaluated twice by four observers with different degrees of experience in Miller's classification, gingival phenotype, tooth shape, and identifiability of the cemento-enamel junction. The following inter- and intra-observer agreements were found: Miller's classification, 0.72 and 0.73-0.95; gingival phenotype, 0.29 and 0.45-0.58; tooth shape, 0.39 and 0.44-0.59; and identifiability of the cemento-enamel junction, 0.21 and 0.30-0.59. A higher agreement was detected for anterior teeth. Further, gingival phenotype (thin-high scalloping) significantly correlated with tooth shape (long-narrow) (ρ = 0.662, p < 0.001). Miller's classification of gingival tissue recessions was evaluated by four examiners using 200 clinical photographs and yielded substantial to almost perfect agreement, with higher agreement for anterior teeth. Although limited to photographic assessment, the present study offers the so far missing proof on the sufficient inter- and intra-observer agreement of this classification.

Background and objectives: Enamel matrix derivative (EMD) is produced from developing porcine tooth buds and represents a complex of low-molecular-weight hydrophobic enamel proteins. EMD is widely applied in periodontal regeneration. Osteoclasts are multinuclear cells, which are responsible for bone resorption. The precursors of osteoclasts, hematopoietic cells, undergo in vivo the process of transendothelial migration before differentiation. EMD is known to affect the process of osteoclastogenesis, but its effect on human osteoclasts precursors after the interaction with activated endothelium was never studied. Materials and Methods: Human umbilical vein endothelial cells (HUVECs)s were seeded in transwell inserts with a pore size of 8 µm and pre-activated by TNF-α and IL-1β for 18 h. Peripheral blood mononuclear cells (PBMCs), freshly isolated from 16 periodontitis patients and 16 healthy individuals, were added to pre-activated HUVECs. Adherent, non-adherent and transmigrated cells were collected and differentiated to osteoclasts by the standard protocol in the presence or absence of EMD. The number of osteoclasts was determined by tartrate-resistant acid phosphatase staining. Results: PBMCs isolated from periodontitis patients have formed a significantly higher osteoclast number compared to PBMCs isolated from healthy individuals (p < 0.05). EMD induced concentration-dependent inhibition of osteoclast formation from PBMCs. This was true for the different PBMC fractions isolated from both healthy individuals and periodontitis patients. Conclusions: Our data show that EMD inhibits the formation and activity of osteoclasts differentiated from the progenitor cells after the interaction with activated endothelium. This might be associated with bone resorption inhibition and supporting bone regeneration in the frame of periodontal therapy.