title: The influence of altered functional loading and posterior bite-blocks on the periodontal ligament space and alveolar bone thickness in rats.
abstract: OBJECTIVE
  Posterior bite-blocks are resin-based structures elevating the occlusion and creating intrusive force on the posterior teeth. Bite-blocks were applied to the molars of growing rats and a hard and soft diet was used to create altered functional masticatory forces. The aim of the present investigation was to study the effect of this appliance on the periodontal ligament space and alveolar bone thickness when combined with altered masticatory forces.
  
  
  METHODS
  Fifty-two four-week-old rats were divided into two groups, hard and soft diet. Two weeks later, half of them received a bite-block appliance, creating four groups: control hard (CH), control soft (CS), bite-block hard (BH) and bite-block soft (BS). All were sacrificed at age of 10 weeks. Their heads were scanned by micro-CT and periodontal ligament space (PDL) width, cross-sectional alveolar socket surface and alveolar bone thickness were measured. Analysis of variance (ANOVA) was used to compare the groups.
  
  
  RESULTS
  The PDL was 9.2% thinner in the CS group (p < 0.001) and 20.7% in the bite-block groups (p  < 0.001) compared to the CH group. Within each of the four groups, the mesiodistal PDL space was larger than the palatobuccal. The alveolar bone was thinner by 5.8% (p = 0.018) in the CS group, 10.7% in the BH group (p < 0.001) and 16.7% in the BS group (p < 0.001) compared to the CH group.
  
  
  CONCLUSIONS
  Young rats wearing posterior bite-blocks have narrower PDL space and thinner alveolar bone compared to controls. When fed a soft diet, the alveolar bone is even thinner but the PDL showed no difference.
authors.affiliation: a Department of Orthodontics, Section of Dental Medicine, Faculty of Medicine , University of Geneva , Geneva , Switzerland.
authors.forename: Balazs Jozsef
authors.initials: BJ
authors.lastname: Denes
authors.affiliation: b Specialist Clinic of Orthodontics, University Clinics , Public Dental Service Region Västra Götaland , Göteborg , Sweden.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bresin
authors.affiliation: a Department of Orthodontics, Section of Dental Medicine, Faculty of Medicine , University of Geneva , Geneva , Switzerland.
authors.forename: Stavros
authors.initials: S
authors.lastname: Kiliaridis
mesh_terms: D000539:Alveolar Process / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D019412:Anatomy, Cross-Sectional; D000818:Animals; D001732:Bite Force; D002508:Cephalometry / Q000379:methods; D004032:Diet; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009811:Odontometry / Q000379:methods; D016382:Orthodontic Appliance Design; D017289:Orthodontic Appliances, Functional; D010513:Periodontal Ligament / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D020390:Tooth Socket / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography / Q000379:methods
keywords: Occlusal splint; alveolar process; bone adaptation; masticatory forces; soft diet