Individuals with congenitally missing permanent teeth, other than third molars, present smaller craniofacial configurations compared to normal controls. However, it is not known if agenesis of third molars is part of the same mechanism. Therefore, this study assessed individuals with and without isolated third molar agenesis and tested the relation of this condition to the size of their facial configurations, using geometric morphometric methods. We show that the absence of one or more third molars is associated with a smaller maxilla, smaller mandible and a smaller overall facial configuration. The effect was larger as the number of missing third molars increased. For example, the size of the mandibular centroids in five 16-year-old females with no, one, two, three or four missing third molars showed a size reduction of approximately 2.5 mm per missing third molar. In addition, in cases with third molar agenesis in one jaw only, the effect was also evident on the opposite jaw. Our findings suggest that isolated third molar agenesis is part of a developmental mechanism resulting also in craniofacial size reduction. This might be the effect of an evolutionary process observed in humans, leading to fewer and smaller teeth, as well as smaller facial structures.

The study investigated in vitro the effect of Porphyromonas gingivalis and its cysteine proteases (gingipains) on epithelial cell adhesion to titanium–zirconium alloy surfaces. Titanium–zirconium discs with a standard machined (M) or chemically modified hydrophilic surface (modM) were coated with lamin‐5 and incubated with telomerase‐inactivated gingival keratinocytes (TIGK). Three P. gingivalis strains or gingipains were either added simultaneously with TIGK or after TIGK cells were already attached to the disks. Adhered TIGK cells were counted at 24 h. All P. gingivalis strains clearly inhibited adhesion of TIGK cells to M and modM surfaces. Compared with bacteria/gingipain‐free TIGK cell cultures, the number of attached TIGK cells was reduced by about 80% and 60% when P. gingivalis was added simultaneously or after TIGK cells were already attached to the disks (each p < 0.01), respectively. Counts of attached cells were similarly reduced when only gingipains were used. Adhesion molecules of TIGK cells, in particular E‐cadherin, were cleaved by P. gingivalis. In conclusion, P. gingivalis and gingipains interfere with the adhesion of epithelial cells to titanium–zirconium alloy surfaces by cleaving adhesion molecules, while a chemically modified hydrophilic titanium–zirconium alloy surface did not yield any protection. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2549–2556, 2019.