Introduction: The frenulum labii superioros do not receive specific attention in the odontological clinic and in odontological research. Actual papers on oral frenulae focus on the morphology of the frenulae and the frenulae in syndromic conditions. The etiology behind the development of frenulae has seemingly never been revealed. The Hypothesis: The hypothesis is that the frenulum labii reveal normal and abnormal location of the dermatomes within the orofacial developmental fields. Evaluation of the Hypothesis: This hypothesis is difficult to prove as long as the dermatomes in the oral cavity have never been localized. In the present new hypothesis, it could be suggested that the oral frenulae labii are structures bordering the oral dermatomes. This is illustrated by two examples, however, more examples are needed for the complete understanding of the etiology behind frenulae labii, which at present need to receive attention in the dental clinic.