Caffeine induces alveolar bone loss in rats submitted to orthodontic movement via activation of receptor activator of nuclear factor Ò¡B, receptor activator of nuclear factor Ò¡B ligand, and osteoprotegerin pathway.

INTRODUCTION: Caffeine is a widely consumed substance with several effects on bone metabolism. This study aimed to investigate the effect of caffeine on the bone tissue of rats submitted to orthodontic movement. METHODS: Twenty-five male Wistar rats underwent orthodontic movement (21 days) of the first permanent maxillary molars on the left side. The experimental group (caffeine; n = 13) and control group (n = 12) received caffeine and water, respectively, by gavage. Microcomputed tomography was performed to analyze orthodontic movement. Histologic analysis of the inflammatory infiltrate and osteoclast count by tartrate-resistant acid phosphatase were conducted. Maxilla tissue was evaluated for receptor activator of nuclear factor Ò¡B (RANK), RANK ligand (RANKL), and osteoprotegerin by immunohistochemistry. RESULTS: Caffeine exhibited a lower bone volume/tissue volume ratio (78.09% ± 5.83%) than the control (86.84% ± 4.89%; P <0.05). Inflammatory infiltrate was increased in the caffeine group compared with the control group (P <0.05). A higher number of tartrate-resistant acid phosphatase-positive cells was observed in the caffeine (9.67 ± 1.73) than in the control group (2.66 ± 0.76; P <0.01). Immunoexpression of RANK and RANKL in the caffeine group was greater than the control (P <0.05). CONCLUSIONS: The use of caffeine thermogenic induces alveolar bone loss in rats submitted to orthodontic movement via activation of RANK, RANKL, and osteoprotegerin signaling pathways.

Caffeine Effect on Bone Metabolism in Rats: a Systematic Review

Abstract Caffeine is a highly-consumed substance around the world and can be found in various food sources and certain medications. The present systematic review aimed to evaluate the effect of caffeine on bone metabolism in rats. A systematic review was conducted in the PubMed, Medline, Scopus, Cocharane, Embase, and Clinical Trials.gov databases, and the Guidelines for Preferential Reporting for Systematic Reviews and Meta-Analyzes (PRISMA) were followed. In vivo experimental studies that presented caffeine as the study object were included, and studies which did not evaluate the bone metabolism and/or evaluated the caffeine in association with other substances were excluded. The quality evaluation of the selected studies was carried out following the guidelines of the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) and the Animal Research Reporting In Vivo Experiment (ARRIVE). Nine of the 472 initially identified articles met the inclusion criteria and were selected for qualitative evaluation. There was a variation between the included studies regarding the administered caffeine doses in each experimental group, as well as their frequency and duration of ingestion. Most studies show that caffeine can interfere with bone metabolism, be it in a negative way by accelerating bone loss and delaying bone repair, or in a beneficial way by activating osteogenesis and bone neoformation. There is a need for further studies to better understand the real effect of caffeine on bone metabolism.