'When discussing the articulation points of the sin, zai, sad and tha, dhal, Dha you mentioned plates of the teeth..

Assalam  'alaikum waa rahmatullahi wa barakatuh,

'When discussing the articulation points of the sin, zai, sad and tha, dhal, Dha you mentioned plates of the teeth and you explained that to be the long axis of the tooth, and in this case, the long axis that is on the internal side, rather than the external side of the teeth. Regrettably, I fail to understand due to my lack of knowledge. Therefore, would you be kind enough
to explain to me what are the plates of the teeth in detail, as well as the difference between the plates of the teeth and the edges of the teeth?
wassalamua 'alaikum wa rahmatullahi wa barakatuh.

Answer

Wa alaikum assalaam wa rahmatullahi wa barakatuh.

The plates are the front and back part of the tooth that is visible, i.e., the front and back of the tooth itself that is sticking out of the gum. 

The edges of the teeth are the ends of the teeth that are furthest from the gums.  Please refer to the black arrows in the picture below, and ignore the extra plain lines that can be seen. 

 Insha’ Allah this helps you.

Wa assalaam alaikum wa rahmatullahi wa barakatuh.