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Title: Strain-guided mineralization in the bone–PDL–cementum complex of a rat periodontium

Objective: The objective of this study was to investigate the effect of mechanical strain by mapping physicochemical properties at periodontal ligament (PDL)–bone and PDL–cementum attachment sites and within the tissues per se. Design: Accentuated mechanical strain was induced by applying a unidirectional force of 0.06 N for 14 days on molars in a rat model. The associated changes in functional space between the tooth and bone, mineral forming and resorbing events at the PDL–bone and PDL–cementum attachment sites were identified by using micro-X-ray computed tomography (micro-XCT), atomic force microscopy (AFM), dynamic histomorphometry, Raman microspectroscopy, and AFM-based nanoindentation technique. Results from these analytical techniques were correlated with histochemical strains specific to low and high molecular weight GAGs, including biglycan, and osteoclast distribution through tartrate resistant acid phosphatase (TRAP) staining. Results: Unique chemical and mechanical qualities including heterogeneous bony fingers with hygroscopic Sharpey's fibers contributing to a higher organic (amide III — 1240 cm⁻¹) to inorganic (phosphate — 960 cm⁻¹) ratio, with lower average elastic modulus of 8 GPa versus 12 GPa in unadapted regions were identified. Furthermore, an increased presence of elemental Zn in cement lines and mineralizing fronts of PDL–bone was observed. Adapted regions containing bony fingers exhibited woven bone-likemore » architecture and these regions rich in biglycan (BGN) and bone sialoprotein (BSP) also contained high-molecular weight polysaccharides predominantly at the site of polarized bone growth. Conclusions: From a fundamental science perspective the shift in local properties due to strain amplification at the soft–hard tissue attachment sites is governed by semiautonomous cellular events at the PDL–bone and PDL–cementum sites. Over time, these strain-mediated events can alter the physicochemical properties of tissues per se, and consequently the overall biomechanics of the bone–PDL–tooth complex. From a clinical perspective, the shifts in magnitude and duration of forces on the periodontal ligament can prompt a shift in physiologic mineral apposition in cementum and alveolar bone albeit of an adapted quality owing to the rapid mechanical translation of the tooth.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [1]
  1. Univ. of California, San Francisco, CA (United States). Division of Biomaterials and Bioengineering
  2. Univ. of California, San Francisco, CA (United States). Division of Orthodontics
  3. Univ. of California, San Francisco, CA (United States). Division of Periodontics
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. SLAC National Accelerator Laboratory, Menlo Park, CA (United States)
  6. Univ. of Akron, OH (United States). Dept. of Polymer Science
Publication Date:
OSTI Identifier:
1251867
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231
Type:
Published Article
Journal Name:
Bone Reports
Additional Journal Information:
Journal Volume: 3; Journal Issue: C; Journal ID: ISSN 2352-1872
Publisher:
Elsevier
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; mineralization; adaptations; bone–periodontal ligament–tooth complex; mechanical strain; interfaces; attachment sites