title: Caffeine may enhance orthodontic tooth movement through increasing osteoclastogenesis induced by periodontal ligament cells under compression.
abstract: OBJECTIVE
  Caffeine is the kernel component of coffee and has multiple effects on bone metabolism. Here we aimed to investigate the effects of caffeine intake on orthodontic tooth movement (OTM).
  
  
  METHODS
  (1) In the in vivo study, two groups comprising 15 randomly assigned rats each underwent orthodontic treatment. One group ingested caffeine at 25mg/kg body weight per day and the other, plain water. After 3 weeks, the degree of tooth movement and effect on the periodontium were assessed. (2) In the in vitro study, we established a model mimicking the essential bioprocess of OTM, which contained a periodontal ligament tissue model (PDLtm), and a co-culture system of osteoblasts (OBs) and osteoclast precursors (pre-OCs). After being subjected to static compressive force with or without caffeine administration, the conditioned media from the PDLtm were used for the OB/pre-OC co-cultures to induce osteoclastogenesis.
  
  
  RESULTS
  (1) In vivo, the caffeine group displayed a significantly greater rate of tooth movement than the control. The alveolar bone mineral density and bone volume fraction were similar between the two groups; however, immunohistochemical staining showed that the caffeine group had significantly more TRAP(+) osteoclasts and higher RANKL expression in the compressed periodontium. (2) In vitro, caffeine at 0.01mM significantly enhanced the compression-induced expression of RANKL and COX-2, as well as prostaglandin E2 production in the PDLtm. Furthermore, the "caffeine+compression"-conditioned media induced significantly more TRAP(+) OC formation when compared with compression alone.
  
  
  CONCLUSIONS
  Daily intake of caffeine, at least at some specific dosage, may enhance OTM through increasing osteoclastogenesis.
authors.affiliation: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China School and Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Jianru
authors.initials: J
authors.lastname: Yi
authors.affiliation: Department of Orthodontics, School and Hospital of Stomatology, Peking University, Beijing, China.
authors.forename: Boxi
authors.initials: B
authors.lastname: Yan
authors.affiliation: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China School and Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Meile
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Orthodontics, Guanghua School and Hospital of Stomatology, Sun yat-sen University, Guangzhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Oral and Maxillofacial Surgery, State Key Laboratory of Oral Diseases, West China School and Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.affiliation: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China School and Hospital of Stomatology, Sichuan University, Chengdu, China. Electronic address: yuli@scu.edu.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China School and Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Zhihe
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D000818:Animals; D016723:Bone Remodeling / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000096:biosynthesis; D008297:Male; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects*; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects*; D010519:Periodontium / Q000187:drug effects; D011312:Pressure; D053245:RANK Ligand / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D014087:Tooth Movement Techniques / Q000379:methods*
chemical_list: D053245:RANK Ligand; D002110:Caffeine; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat; D015232:Dinoprostone
keywords: Bone remodeling; Caffeine; Orthodontic tooth movement; Osteoclastogenesis; Periodontal ligament