CONTENTS

Editor’s Choice

David L. Turpin, Editor-in-Chief

Botulinum toxin type A (Botox) forthe neuromuscular correction ofexcessive gingival display on smilingMario Polo

I always thought that maxillary impaction was anobvious choice for someone bothered by an exces-sively gummy smile, unless the patient was opposedto all surgery. Then I was quick to explain that, as aperson matures, the upper lip lengthens and tends tominimize the original problem. But is there anothersolution? Is there a treatment procedure that is lessinvasive than surgery and less expensive, and canprovide the desired change in lip length until theaging process catches up?

Recently, Botox has been identified as a consis-tent, minimally invasive alternative for the correc-tion of gummy smiles caused by hyperfunctionalupper lip elevator muscles. Hyperfunctional or hy-pertonic muscles are excessively active with greaterthan normal contraction potential. In this study, 30patients received Botox injections to reduce exces-sive gingival display. Progress was evaluated at 2, 4,8, 12, 16, 20, and 24 weeks postinjection, withchanges in smile esthetics documented by photo-graphs and videos. Lip drop at 2 weeks averaged 5.1mm for these patients. From that time on, gingivaldisplay gradually increased, with the baseline aver-age reached at 30 to 32 weeks postinjection. Al-though the effect of Botox is transitory, the authorbelieves that it is effective for some patients.

Long-term changes of the upper lipposition relative to the incisal edgePiotr Fudalej

The Botox treatment decision leads to anotherquestion: what should the final vertical position ofthe maxillary incisors be in relation to the upper lipto achieve optimal esthetics and stability? Piotr

Am J Orthod Dentofacial Orthop 2008;133:13A-14A0889-5406/$34.00Copyright © 2008 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2007.12.016

Fudalej recognized the lack of data for long-termchanges of the upper lip relative to the incisal edgesof the anterior teeth. His sample of 54 subjects wasfollowed longitudinally well into their third andfourth decades of life, an average of 22 yearspostretention. The results show that upper lip elon-gation is a continuous process. From the ages of 16to 31, postadolescent growth of the craniofacialskeleton balances the increase in the lip length. In thethird and fourth decades of life, elongation of theupper lip exceeds vertical growth of the face, de-creasing the exposure of the maxillary incisors.

For a patient treated with Botox for a gummy smileat 18, the transitory effect of this approach might be agodsend when she turns 36.

Comparison of the effects of invisibleremovable thermoplastic applianceswith light and heavy orthodonticforces on premolar cementumLaura J. Barbagallo, Allan S. Jones, Peter Petocz,and M. Ali Darendeliler

As the use of sequential removable aligners gains inpopularity, can we look forward to the elimination ofroot resorption in orthodontic patients? In this prospec-tive randomized clinical trial, a research team in Syd-ney, Australia, used x-ray microtomography to quantifyresorption generated by treatment with ClearSmileappliances and compared the effects with those ofheavy and light conventional orthodontic forces and noforce (the control group).

The findings are lengthy and complex but sur-prising; you’ll want to read them all. The ClearSmilepatients had similar but slightly more resorptivecavities than those having light forces, and approxi-mately 6 times more than the control teeth. The teethreceiving heavy forces had the most resorptive cav-ities, or about 9 times more than the controls. Clearremovable appliances have similar effects on rootcementum as light fixed orthodontic forces. Thefindings of this 3-dimensional study of root resorp-tion are promising for those who use newer appli-

ances with light forces to move teeth.

13A

American Journal of Orthodontics and Dentofacial OrthopedicsFebruary 2008

14A Editor’s choice

Radiation doses to the head and neckfrom an episode of orthodontic carePhilippe Hujoel, Lars Hollender, Anne-Marie Bollen,John D. Young, Molly McGee, and Alex Grosso

As clinicians search for tangible benefits of im-proved treatment decisions from increased use ofCBCT radiography, it is time to ask about the risk ofthis ionizing radiation. According to these authors, theevidence of harm of low-dose ionizing radiation isincreasingly convincing. This survey of radiographic

lished estimates to provide organ-specific radiationdoses. Collective organ doses were estimated from the1999 US Nationwide Evaluation of X-ray Trends andOrthodontic Utilization Surveys.

The strengths of this study are the estimates ofdoses associated with an episode of orthodontic care.Weaknesses include the limited scope of the sample.The authors concluded that orthodontic care, partlybecause of its high prevalence, can contribute signif-icantly to the diagnostic radiation burden in thoseless than 19 years old in the United States. Addi-tional verification of these strong conclusions is

records from an institution was combined with pub- needed.