It depends on how you define "dissolve". In some ways it had ceased to be before 476; in others there is a direct line of continuity until the present day. The best I can do is to give an impressionistic sketch.

Certain things stayed the same for a very long time. "Barbarian" invasions tended to take over the Roman administrative system; it was a fantastic way to get tax money, and the new rulers themselves wanted to be seen as Roman. The new ruling class took Roman titles. Vir inluster, a title which accompanies every Merovingian charter, is the 4th century title for a Roman senator. Islands of people speaking proto-Romance persisted late enough in otherwise Germanic-speaking regions that there is still evidence of this in modern dialects.

Certain things changed, but did not cease. Trade did not stop, it slowed. Long range connections like trade routes were not abandoned, but were used less frequently. The road network decayed but remained in use. The centers of learning shifted from the Roman school system to the monastery.

Certain things changed drastically. The high level of monitization in the western economy ended, metal became scarce, and coinage switched from gold to silver. The papacy became the real temporal ruler of the city of Rome. Industrial-scale mining and other forms of production ceased. The annona - the annual shipments of grain to Rome which fed the city - ceased. There is a transition in the legal use of a written document from something which merely records a right or agreement to the actual physical manifestation of the right or agreement. There is no longer a western Emperor.

There are many, many books on this subject, but the best ones are massive, in German, or both. A short list:

• McCormick, Michael. Origins of the European Economy: Communications and Commerce A.D. 300-900. Cambridge: Cambridge University Press, 2001.

• Classen, Peter. Kaiserreskript und Königsurkunde: diplomatische Studien zum Problem der Kontinuität zwischen Altertum und Mittelalter. Vyzantina keimena kai meletai 15. Thessalonikē: Kentron Vyzantinōn Ereunōn, 1977.

• Davis, Jennifer R., Michael McCormick, Angeliki E. Laiou, Jan M. Ziolkowski, and Herbert L. Kessler, eds. The Long Morning of Medieval Europe: New Directions in Early Medieval Studies. Aldershot: Ashgate, 2008.