Table 1.

Minimum period of stability in different studies

Author	Year	Period of stability
Das SS, Pasricha JS[12]	1992	4 months
Boersma BR, Westerhof W[13]	1995	6 months
Jha AK, Pandey SS, Shukla V K[14]	1992	1 year
Savant SS[15]	1992	2 years
Falabella R[16]	2003	2 years
Falabella R[17]	1995	2 years
Falabella R[18]	1992	3 years