Dental Hypotheses

: 2017  |  Volume : 8  |  Issue : 4  |  Page : 118--119

Author's reply: Comment: Does absence or malformations of oral frenulae indicate orofacial developmental fields with dermatome abnormalities

Inger Kjaer 
 Institute of Odontology, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark

Correspondence Address:
Inger Kjaer
Institute of Odontology, Faculty of Health Sciences, University of Copenhagen, 20 Nørre Allé, DK-2200, Copenhagen N

How to cite this article:
Kjaer I. Author's reply: Comment: Does absence or malformations of oral frenulae indicate orofacial developmental fields with dermatome abnormalities.Dent Hypotheses 2017;8:118-119

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Kjaer I. Author's reply: Comment: Does absence or malformations of oral frenulae indicate orofacial developmental fields with dermatome abnormalities. Dent Hypotheses [serial online] 2017 [cited 2021 Sep 26 ];8:118-119
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The letter to the editor raises the following three important questions/comments on the paper:The embryological origin of the frenulae.Single median maxillary central incisor (SMMCI) as a condition, which is associated with specific clinical characteristics and craniofacial malformations. The condition is not limited to a simple dental anomaly. Furthermore, the genetic cause for the absence of frenulae is highlighted.The surgical treatment of atypical frenulae.

The author replies to these important questions/comments as follows:The overall purpose of the paper was to focus on dermatomes, which were defined in the paper with a reference. Attention to the dermatomes has seemingly not been given before in clinical/diagnostic odontology. The dermatomes develop during the early stages of embryogenesis. They develop close to the body axis and migrate anteriorly, before the intermaxillary and globular processes are visible (5–9 weeks). It is presumed that these processes arise from the dermatomes, and that the defect in SMMCI is a mid-axial defect, possibly genetic, as highlighted in the letter. The dermatomes have a close interrelationship with the nervous system (prosencephalon region). The dermatomes, therefore, express not only the importance for the tooth and craniofacial development, but also for the development of central and peripheral nervous systems. The interrelationship between hard tissue development and the development of the central and peripheral nervous systems is related to a scientific field named neuro-osteology. Examples were given in the paper, with a reference to brain malformation in SMMCI. It is very important that the authors of the letter to the editor highlight the importance and background of embryological development for the understanding of post-natal abnormalities seen in the clinic. In addition, foetal pathology can add information to the clinic.[1] A new textbook concerning these aspects in dental and craniofacial diagnostics has been published.[2] The paper was intended to present hypotheses-generating ideas for upcoming research.[3]The paper was printed in the journal under the section ‘Original Hypothesis’. The original hypothesis was regarding the involvement of dermatomes. In that context, SMMCI was mentioned only as a well-known example of a condition with absent mid-axial frenulum labii superioris. In the paper by Kjær there were references also to frenulae in other syndromic conditions (Refs 1 and 2 in the paper). The reference mentioned in the letter to the editor by Kumar and Anand (Ref 3 in the letter) was the same as Ref 1 mentioned by Kjær in the original paper.The surgical treatments for dental frenulae have not been mentioned in the paper because that was not the purpose of the report. Therefore, no comments to the important viewpoints on surgical treatments has been made.


If the dermatome hypothesis is proved in the future, the dentist should hopefully be able to connect the findings in the oral cavity with brain malformation[4] and neuro-psychiatric conditions.[5] The field combining development of nerve tissue and hard tissue, named neuro-osteology, require extensive research.

Discussions such as this, based on scientific experience and knowledge, are not only important, but essential, for progress in science. In this context, letters to the editor and replies from the authors are essential, highly valuable and deeply appreciated.

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Conflicts of interest

The author has editorial involvement with Dental Hypotheses.


1Kjær I, Keeling JW, Græm N. The midline craniofacial skeleton in holoprosencephalic fetuses. J Med Genet 1991;28:846-55.
2Kjær I. Etiology-Based Dental and Craniofacial Diagnostics. West Sussex, UK: John Wiley & Sons; 2017.
3Kjær I. Dental research needs a new way of thinking. Dent Hypotheses 2014;4:131-2.
4Kjær I, Wagner A, Thomsen LL, Holm K. Brain malformation in single median maxillary central incisor. Neuropediatrics 2010;40:280-3.
5Kenrad AB, Kjær I. The interrelationship between permanent maxillary incisors and neuropsychiatric conditions. J Neuropsychiatry 2016;2:1-3.