A Missouri court may grant visitation rights to grandparents in specific circumstances, as delineated in Missouri Revised Statutes chapters 452.402 and 452.403.
You'll find those statutes in the first two links below. The third link provides the table of contents for all Missouri laws.
Disclaimer: This post contains general legal information and should not be construed as legal advice to be applied to any specific factual situation. Each reader should consult a lawyer if you want a qualified professional’s assurance that this information, and your interpretation of it, is appropriate to your particular situation.