Introduction:
The Constitution of India is the supreme law of the country that lays down the framework for governance. The Preamble of the Indian Constitution outlines the ideals and objectives that the country seeks to achieve. It was adopted by the Constituent Assembly on 26th November 1949 and came into effect on 26th January 1950.

Explanation:
The Preamble of the Indian Constitution was amended only once through the Constitution (42nd Amendment) Act, 1976. This amendment was introduced during the period of the Emergency and brought about several changes in the Preamble. However, the word "Dignity" was not inserted through this amendment.

Constitution (42nd Amendment) Act, 1976:
The Constitution (42nd Amendment) Act, 1976 is one of the most controversial amendments in the history of the Indian Constitution. It was enacted during the period of the Emergency declared in 1975. The amendment was introduced with the aim of strengthening the power of the central government and curbing the authority of the judiciary.

Changes made through the 42nd Amendment:
The Constitution (42nd Amendment) Act, 1976 made several changes in the Preamble of the Indian Constitution. The key changes introduced through this amendment were:

1. Insertion of the word "Socialist": The word "Socialist" was added before the word "Secular" in the Preamble. This amendment emphasized the commitment of the Indian state towards achieving social and economic justice and reducing inequalities in society.

2. Insertion of the word "Secular": The word "Secular" was inserted to emphasize the secular nature of the Indian state. It signifies that the state does not promote any particular religion and treats all religions equally.

3. Insertion of the words "Unity and Integrity of the Nation": The words "Unity and Integrity of the Nation" were added to highlight the commitment of the Indian state towards maintaining the territorial integrity and unity of the country.

Conclusion:
In conclusion, the word "Dignity" was not inserted through the Constitution (42nd Amendment) Act, 1976. This amendment primarily introduced the words "Socialist" and "Secular" in the Preamble and emphasized the unity and integrity of the nation. The word "Dignity" has been a part of the Preamble since its adoption in 1949.