Objectives: To investigate and synthesize systematically the evidence from animal studies pertaining to the effect of pharmacological agents on tooth movement relapse following cessation of orthodontic force application. Materials and Methods: An electronic search was conducted in seven online databases (including gray sources) without restrictions until the third week of April 2019, followed by a hand search in the reference lists of eligible articles. Controlled animal studies investigating the effect of pharmacological agents on tooth movement relapse following orthodontic treatment were selected. Relevant data were extracted from eligible studies and the risk of bias assessment was done using SYRCLE's risk of bias tool. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool. Results: The search identified 2354 records, of which 7 studies were deemed eligible for inclusion in the qualitative synthesis, with the majority presenting an unclear risk of bias. Orthodontic relapse was shown to decrease with the administration of pamidronate disodium, atorvastatin, aspirin, and chemically modified tetracycline-3. Inconsistent effects on relapse were observed after the use of simvastatin. The overall quality of retrieved evidence was assessed as low at best.Conclusions: The available evidence shows that the investigated pharmacological agents may demonstrate variable effects on tooth movement relapse following cessation of orthodontic force. Additional evidence of higher quality is required to draw definitive conclusions on their effects and to make potential recommendations for clinical application. (Angle Orthod. 2020;90:598-606.) Although planned, analyses for small-study effects, publication bias, or exploratory subgroup analyses were not feasible because of the inadequate number of studies. The quality of evidence

Objective To evaluate the quantity of titanium dioxide nanoparticles released into the artificial salivary medium from orthodontic composite impregnated with 1% weight/weight (w/w) and 5% w/w titanium dioxide nanoparticles (TiO2 NPs) used for bonding metal brackets, thereby eventually comprehending the permissible levels. Materials and Method Eighty freshly extracted teeth for orthodontic treatment were divided into 2 groups of 40 teeth each and were bonded with brackets containing 1% w/w and 5% w/w composite containing titanium dioxide nanoparticles and placed in an artificial salivary medium. Quantification of 1% w/w and 5% w/w composite containing titanium nanoparticles was done using inductively coupled plasma mass spectroscopy for 4 timely periods 24 h, 2 months, 4 months, and 6 months. Results In the teeth that received 1% TiO2, the amount of titanium released was greatest in 2 months with no significant release at later intervals. In the second group that received 5%, there was a significant release of titanium at all intervals, with highest release at second month. On comparing the 2 concentrations at 4 different time intervals, the quantities were significantly greater in the 5% group at all time frames, thus implying a significant increase in titanium released with an increase in concentration from 1% to 5%. Conclusion Titanium release was higher in 5% w/w composite containing nanoparticles than 1% w/w composite containing nanoparticles, and 1% and 5% concentrations can be used safely and are within the permissible limits.