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Where has all the arch length gone?
EDITORIAL
Where has all the arch length gone? David L. Turpin, DDS, MSD, Editor-in-Chief Seattle, Wash
O
ne can never claim that orthodontic educators and researchers spend too much time trying to prove that a better life is just around the corner. However, I’ve got a list of great topics that will prompt most clinicians to believe in a real “fantasy island.” For starters, how about a pill that speeds up the metabolic activity of alveolar bone, allowing orthodontic treatment to take as little as 6 months to complete? Then, of course, the antidote during retention would eliminate a majority of all relapse. I’ll bet no one is working on that project for their master’s degree. But give researchers a new digital caliper and they’re bound to use it with religious fervor to prove something bad for us all. In fact, some researchers at the University of Iowa have done just that. They have shown that dental arch length in the primary dentition is less than what it was 50 years ago. Now, isn’t that tidy little fact great news? It seems that over the past several years most clinicians have been working to increase arch length with an astonishing array of both fixed and removable appliances, all in an attempt to treat patients without removing permanent teeth. At Iowa, Drs Warren and Bishara wondered if clinicians are indeed having to work harder than ever to achieve the needed arch space. In their article “Comparison of dental arch measurements in the primary dentition between contemporary and historic samples,” which appears in this issue of the Journal, the
Am J Orthod Dentofacial Orthop 2001;119:201 Copyright © 2001 by the American Association of Orthodontists 0889-5406/2001/$35.00 + 0 8/1/114410 doi:10.1067/mod.2001.114410
authors compare arch lengths in 2 samples of children who were born nearly 50 years apart, but who were otherwise similar in terms of geographic location, racial and ethnic background, and socioeconomic status. The children were between 4.5 and 5 years of age and were excluded if any permanent teeth had erupted. I think you will find the results very interesting. Maxillary and mandibular arch lengths, for both sexes, were significantly shorter in the contemporary sample (born between 1992 and 1995) than in the earlier group (born between 1946 and 1948). All arch widths were significantly smaller in contemporary boys, although not in girls. According to the authors, these findings suggest that average arch dimensions may be smaller in contemporary children than in past generations. The next step in this line of research will consist of determining whether smaller arch dimensions are associated with more crowding in the primary, mixed, and permanent dentitions. The case report in this issue, by Kenworthy (p. 202), also deals with arch length, in that the clinicians decided to retain a deciduous second molar instead of replacing a congenitally missing second premolar. How wise was this choice, given that it usually creates an arch length problem and the tooth will probably be lost eventually anyway? I hope you will take time to study this case report and challenge your own diagnostic skills to come up with a better solution. I like the way these authors describe their decision-making process and then critically evaluate the treatment result. I hope to bring more of these case reports to you in future issues.
201
Where has all the arch length gone? David L. Turpin, DDS, MSD, Editor-in-Chief Seattle, Wash
O
ne can never claim that orthodontic educators and researchers spend too much time trying to prove that a better life is just around the corner. However, I’ve got a list of great topics that will prompt most clinicians to believe in a real “fantasy island.” For starters, how about a pill that speeds up the metabolic activity of alveolar bone, allowing orthodontic treatment to take as little as 6 months to complete? Then, of course, the antidote during retention would eliminate a majority of all relapse. I’ll bet no one is working on that project for their master’s degree. But give researchers a new digital caliper and they’re bound to use it with religious fervor to prove something bad for us all. In fact, some researchers at the University of Iowa have done just that. They have shown that dental arch length in the primary dentition is less than what it was 50 years ago. Now, isn’t that tidy little fact great news? It seems that over the past several years most clinicians have been working to increase arch length with an astonishing array of both fixed and removable appliances, all in an attempt to treat patients without removing permanent teeth. At Iowa, Drs Warren and Bishara wondered if clinicians are indeed having to work harder than ever to achieve the needed arch space. In their article “Comparison of dental arch measurements in the primary dentition between contemporary and historic samples,” which appears in this issue of the Journal, the
Am J Orthod Dentofacial Orthop 2001;119:201 Copyright © 2001 by the American Association of Orthodontists 0889-5406/2001/$35.00 + 0 8/1/114410 doi:10.1067/mod.2001.114410
authors compare arch lengths in 2 samples of children who were born nearly 50 years apart, but who were otherwise similar in terms of geographic location, racial and ethnic background, and socioeconomic status. The children were between 4.5 and 5 years of age and were excluded if any permanent teeth had erupted. I think you will find the results very interesting. Maxillary and mandibular arch lengths, for both sexes, were significantly shorter in the contemporary sample (born between 1992 and 1995) than in the earlier group (born between 1946 and 1948). All arch widths were significantly smaller in contemporary boys, although not in girls. According to the authors, these findings suggest that average arch dimensions may be smaller in contemporary children than in past generations. The next step in this line of research will consist of determining whether smaller arch dimensions are associated with more crowding in the primary, mixed, and permanent dentitions. The case report in this issue, by Kenworthy (p. 202), also deals with arch length, in that the clinicians decided to retain a deciduous second molar instead of replacing a congenitally missing second premolar. How wise was this choice, given that it usually creates an arch length problem and the tooth will probably be lost eventually anyway? I hope you will take time to study this case report and challenge your own diagnostic skills to come up with a better solution. I like the way these authors describe their decision-making process and then critically evaluate the treatment result. I hope to bring more of these case reports to you in future issues.
201