Abstract
The theory, known as the “brain-bone axis” theory, involves the central nervous system in bone remodeling. The alteration of the nervous system could lead to abnormal bone remodeling. Melatonin produced by the pineal gland is a hormone that is characterized by its antioxidant properties. The aim of this meta-analysis was to examine the role of melatonin in the growth of new bone around titanium dental implants in vivo. A manual search of the PubMed and Web of Science databases was conducted to identify scientific studies published until November 2020. We included randomized clinical trials (RCTs) and animal studies where melatonin was used with titanium implants. Fourteen studies met the inclusion criteria. Quality was assessed using the Jadad scale and SYRCLE’s risk of bias tool. Our meta-analysis revealed that the use of melatonin during implant placement improves bone-to-implant contact percentages in animals (difference of means, random effects: 9.59 [95% CI: 5.53–13.65]), reducing crestal bone loss in humans (difference in means, random effects: −0.55 [95% CI: 1.10–0.00]). In animals, titanium implants using melatonin increase bone-to-implant contact surface 2–6 weeks after their placement and reduce crestal bone loss in humans following six months. The results of this meta-analysis should be taken with caution, due to the small samples and the large heterogeneity among studies.
Highlights
The first description of osseointegration was provided by Brånemark and colleagues [1]more than 50 years ago, and to date, this process still remains unexplored
It suggests the involvement of the sympathetic nervous system (SNS) in bone remodeling, claiming the need for the autonomic nervous system to be undamaged in order to contribute to the maintenance of healthy bone tissue, with its alteration leading to possible anomalies in bone remodeling [3,4]
It has been proven that the group of glucose-sensing neurons in the hypothalamic arcuate nucleus makes control of the skeleton by the brain possible [7], and that long-term use of certain central nervous depressant drugs causes a reduction in bone mass that results in osteoporosis, and in high rates of dental implant failure in patients under treatment with such drugs [8]
Summary
The first description of osseointegration was provided by Brånemark and colleagues [1]more than 50 years ago, and to date, this process still remains unexplored. One of the theories posed in recent years, referred to as the “brain-bone axis theory” by certain authors [2], has drawn particular interest It suggests the involvement of the sympathetic nervous system (SNS) in bone remodeling, claiming the need for the autonomic nervous system to be undamaged in order to contribute to the maintenance of healthy bone tissue, with its alteration leading to possible anomalies in bone remodeling [3,4]. This remodeling process would be mainly controlled by neurotransmitters (noradrenaline, serotonin and dopamine), and growth hormones secreted by the pituitary gland could stimulate osteoblast and osteoclast proliferation, which plays a crucial part in the bone formationdestruction balance [5,6].
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