Every clinician has experienced the frustration of the gingival tissues retracting or changing shape. Meritorious work has been done to cope with these changes and to promote a healthy periodontium and normal papillae. But, so far, there is no explanation for why these changes occur. In this paper, a theory is presented that may clarify the process. The inner vacuum in the mouth, present at each act of swallowing, applies the soft tissues of the tongue, lips, and cheeks against the hard tissues of the bones and teeth. This action molds the soft tissues, adapting them in accordance to the architecture of teeth and embrasures; therefore, the oral vacuum has the capability to adapt, enhance, or impede gingival tissue growth. Keywords: gingival esthetics, gingival growth, modeling, negative pressure, suction, vacuum