- Email: [email protected]
DENTIN GROWS MORE BRITTLE WITH AGE
N E W S
Taken together, these results suggest that QLIPS could measure Ro52 levels alone to lead to a diagnosis of primary Sjögren syndrome. The data also suggest that QLIPS, with its speed and automated ease, has great potential as a point-of-care diagnostic test for patients with Sjögren syndrome and other autoimmune disorders. This study was supported by the Division of Intramural Research, National Institute of Dental and Craniofacial Research, and in part by a Bench-to-Bedside award from the NIH Clinical Research Center and by NIH grant AR44731. Compiled by Janice Snider, senior editor.
DENTIN GROWS MORE BRITTLE WITH AGE
cientists have quantified the fracture toughness of coronal dentin for cracks that extended perpendicular to the tubules, according to an article published in the October issue of Journal of the Mechanical Behavior of Biomedical Materials. Researchers from University of Maryland, Baltimore, and Shanghai University performed an analysis using 14 third molars that had been extracted from patients between the ages of 18 and 83 years, which allowed them to compare and contrast the toughness of young, middle-aged and old dentin. The research team, led by Dwayne D. Arola, PhD, of the Department of Mechanical Engineering, University of Maryland, Baltimore County, Baltimore, found that the average fracture toughness of the old dentin was approximately 30 percent lower than that of the young dentin. They noted
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JADA, Vol. 140
http://jada.ada.org
that the reduction in fracture toughness seemed to depend on the number of lumens, which is important in determining the mineral-to-collagen ratio and the variation in the degree of age-related sclerosis, or embrittlement, throughout dentin. Researchers also found that the reduction in fracture toughness depended, regardless of age, on the spatial orientation of the tubules. As they explained in the article, the degree of toughening with crack extension is lowest for those that extend perpendicular to the tubules. Although the toughness of dentin decreases with age, the degree of anisotropy—having a different value when measured in a different direction—in resistance to fracture does not. “Many of the current practices in the field of restorative dentistry are based on knowledge of the tooth tissues,” the authors concluded. “However, they have not necessarily been developed to accommodate changes in the mechanical properties that are associated with aging. Results of this investigation have provided further evidence that aging results in significant changes in the mechanical behavior of dentin and a reduction in the ‘damage tolerance’ of the tissue. “With these findings in mind, the success of specific practices in the field of restorative dentistry may require special consideration in the treatment of seniors, or the development of age-sensitive methods of care.” The authors were supported by the National Institute of Dental and Craniofacial Research. Compiled by Amy E. Lund, senior editor.
CORRECTION
n the October issue of JADA, the names of Drs. Marvin and Stanton Canter were spelled incorrectly in the article “The Verb of Life Is to Try” (JADA 2009;140[10]:1297-1299).
I
MEETINGS
dThe National Association of Dental Laboratories will hold its annual meeting Jan. 21-23 in Las Vegas. For more information, visit “www.nadl.org”. dThe Colegio Cirujanos Dentistas de Puerto Rico will hold its annual meeting Feb. 36 in San Juan. For more information, call 1-787-764-1969 or visit “www.ccdpr.org”. dThe United Arab Emirates International Dental Conference & Arab Dental Exhibition will be held March 9-11 in Dubai. For more information, visit “www.aeedc.com/about_ aeedc.php”. dThe American Student Dental Association will hold its 40th annual meeting in Pittsburgh. For more information, contact Ms. Meghan Keelean by phone at 1-312-440-2845, by fax at 1-312-440-2820 or by e-mail at “[email protected]”. dThe American Society for Laser and Surgery will hold its 30th annual conference April 1418 in Phoenix. For more information, contact Ms. Nadine Tosk by phone at 1-847-920-9858 or by e-mail at “nadinepr@gmail. com” or visit “www.aslms.org”. APPOINTMENTS/ ELECTIONS/AWARDS
dDr. Joel Berg, Forest Hill, Md., has been named the chair of the pediatric dentistry department at the University of Washington School of Dentistry. dDr. James P. Birong,
December 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
Taken together, these results suggest that QLIPS could measure Ro52 levels alone to lead to a diagnosis of primary Sjögren syndrome. The data also suggest that QLIPS, with its speed and automated ease, has great potential as a point-of-care diagnostic test for patients with Sjögren syndrome and other autoimmune disorders. This study was supported by the Division of Intramural Research, National Institute of Dental and Craniofacial Research, and in part by a Bench-to-Bedside award from the NIH Clinical Research Center and by NIH grant AR44731. Compiled by Janice Snider, senior editor.
DENTIN GROWS MORE BRITTLE WITH AGE
cientists have quantified the fracture toughness of coronal dentin for cracks that extended perpendicular to the tubules, according to an article published in the October issue of Journal of the Mechanical Behavior of Biomedical Materials. Researchers from University of Maryland, Baltimore, and Shanghai University performed an analysis using 14 third molars that had been extracted from patients between the ages of 18 and 83 years, which allowed them to compare and contrast the toughness of young, middle-aged and old dentin. The research team, led by Dwayne D. Arola, PhD, of the Department of Mechanical Engineering, University of Maryland, Baltimore County, Baltimore, found that the average fracture toughness of the old dentin was approximately 30 percent lower than that of the young dentin. They noted
S
1472
JADA, Vol. 140
http://jada.ada.org
that the reduction in fracture toughness seemed to depend on the number of lumens, which is important in determining the mineral-to-collagen ratio and the variation in the degree of age-related sclerosis, or embrittlement, throughout dentin. Researchers also found that the reduction in fracture toughness depended, regardless of age, on the spatial orientation of the tubules. As they explained in the article, the degree of toughening with crack extension is lowest for those that extend perpendicular to the tubules. Although the toughness of dentin decreases with age, the degree of anisotropy—having a different value when measured in a different direction—in resistance to fracture does not. “Many of the current practices in the field of restorative dentistry are based on knowledge of the tooth tissues,” the authors concluded. “However, they have not necessarily been developed to accommodate changes in the mechanical properties that are associated with aging. Results of this investigation have provided further evidence that aging results in significant changes in the mechanical behavior of dentin and a reduction in the ‘damage tolerance’ of the tissue. “With these findings in mind, the success of specific practices in the field of restorative dentistry may require special consideration in the treatment of seniors, or the development of age-sensitive methods of care.” The authors were supported by the National Institute of Dental and Craniofacial Research. Compiled by Amy E. Lund, senior editor.
CORRECTION
n the October issue of JADA, the names of Drs. Marvin and Stanton Canter were spelled incorrectly in the article “The Verb of Life Is to Try” (JADA 2009;140[10]:1297-1299).
I
MEETINGS
dThe National Association of Dental Laboratories will hold its annual meeting Jan. 21-23 in Las Vegas. For more information, visit “www.nadl.org”. dThe Colegio Cirujanos Dentistas de Puerto Rico will hold its annual meeting Feb. 36 in San Juan. For more information, call 1-787-764-1969 or visit “www.ccdpr.org”. dThe United Arab Emirates International Dental Conference & Arab Dental Exhibition will be held March 9-11 in Dubai. For more information, visit “www.aeedc.com/about_ aeedc.php”. dThe American Student Dental Association will hold its 40th annual meeting in Pittsburgh. For more information, contact Ms. Meghan Keelean by phone at 1-312-440-2845, by fax at 1-312-440-2820 or by e-mail at “[email protected]”. dThe American Society for Laser and Surgery will hold its 30th annual conference April 1418 in Phoenix. For more information, contact Ms. Nadine Tosk by phone at 1-847-920-9858 or by e-mail at “nadinepr@gmail. com” or visit “www.aslms.org”. APPOINTMENTS/ ELECTIONS/AWARDS
dDr. Joel Berg, Forest Hill, Md., has been named the chair of the pediatric dentistry department at the University of Washington School of Dentistry. dDr. James P. Birong,
December 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.