The problem with your existing query is you are using an INNER JOIN
between all of the tables. An INNER JOIN requires that the value of the column being joined on exists in both tables.
It seems to me that you want to use a LEFT JOIN
instead:
select MT.PK, MT.C1, MT.C2, T1.TC1, T2.TC2, T3.TC3, T4.TC4
from MT
left join T1 on MT.PK=T1.PK
left join T2 on MT.PK = T2.PK
left join T3 on MT.PK = T3.PK
left join T4 on MT.PK = T4.PK;
A LEFT JOIN will return all rows from the MT
table and then the data from the other tables if it exists when the PK
matches.