title: Fractal analysis of the PDL-bone interface and implications for orthodontic tooth movement.
abstract: BACKGROUND
  The periodontal ligament (PDL) is a soft tissue interposed between the tooth and the alveolar bone. It is responsible for transmission of forces in vivo; this promotes bone remodeling. The purpose our study was to use fractal analysis to quantify the complex morphology of the PDL-bone interface.
  
  
  METHODS
  We used Scion Image (Scion Corp, Frederick, Md) and Benoit fractal analysis (Tru Soft International, St. Petersburg, Fla) programs to calculate the fractal dimension of the PDL-bone interface in rats via the box-counting method. Rats in the experimental groups received an initial force of 0.1N or 0.5N with customized springs for 6 hours.
  
  
  RESULTS
  Our studies showed an increase in normal fractal dimension at the root apices of the rats' maxillary molars. We also found evidence that the fractal dimension varies along the entire root length from the apex to the cementoenamel junction.
  
  
  CONCLUSIONS
  Mechanical loading might lead to an increase in fractal dimension at the PDL-bone interface apart from mechanisms of bone cell directed remodeling. These changes in fractal dimension are proportional to loading and could provide a new parameter for force determination in orthodontic tooth movement.
authors.affiliation: Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, GA 30912-1129, USA.
authors.forename: Namita
authors.initials: N
authors.lastname: Wagle
authors.forename: Nha Nam
authors.initials: NN
authors.lastname: Do
authors.forename: Jack
authors.initials: J
authors.lastname: Yu
authors.forename: James L
authors.initials: JL
authors.lastname: Borke
mesh_terms: D000539:Alveolar Process / Q000033:anatomy & histology*; D000704:Analysis of Variance; D000818:Animals; D003799:Dental Stress Analysis / Q000379:methods*; D005260:Female; D017709:Fractals; D007150:Immunohistochemistry; D015675:Osteocalcin / Q000032:analysis; D010513:Periodontal Ligament / Q000033:anatomy & histology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014087:Tooth Movement Techniques
chemical_list: D015675:Osteocalcin