Dyanmic SQl - Stupid/Easy problem

OK - I Have the below - which works fine:
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SELECT '<b>' + CAST(PRIME_CPT as varchar(30)) + '</b> - ' +  
case when p.CPT_DESC is null then case when p.LONG_DESC is null then p.HCPC_DESC else p.LONG_DESC end else p.CPT_DESC end AS PRIME_CPT,
'<b>' + CAST(SECOND_CPT as varchar(30)) + '</b> - ' +
case when s.CPT_DESC is null then case when s.LONG_DESC is null then s.HCPC_DESC else s.LONG_DESC end else s.CPT_DESC end AS SECOND_CPT,
EDIT_TYPE,
GB_MOD
FROM tblCCI140 c
INNER JOIN [vwhcpcs] p on PRIME_CPT = p.hcpc_code INNER JOIN [vwhcpcs] s on SECOND_CPT = s.hcpc_code
WHERE c.PRIME_CPT = @var0
AND c.SECOND_CPT = @var1
OR c.PRIME_CPT = @var1 AND c.SECOND_CPT = @var0
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But when I convert it to Dynamic SQL - I get a type conversion error in the where clause - any suggestions on the obviously stupid/easy thing I am missing:Start Free Trial

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DECLARE @SQL nvarchar(max)
 
SELECT @SQL = '
SELECT ''<b>'' + CAST(PRIME_CPT as varchar(30)) + ''</b> - '' +  
case when p.CPT_DESC is null then case when p.LONG_DESC is null then p.HCPC_DESC else p.LONG_DESC end else p.CPT_DESC end AS PRIME_CPT, 
''<b>'' + CAST(SECOND_CPT as varchar(30)) + ''</b> - '' +
case when s.CPT_DESC is null then case when s.LONG_DESC is null then s.HCPC_DESC else s.LONG_DESC end else s.CPT_DESC end AS SECOND_CPT, 
EDIT_TYPE, 
GB_MOD
FROM tblCCI140 c
INNER JOIN [vwhcpcs] p on PRIME_CPT = p.hcpc_code INNER JOIN [vwhcpcs] s on SECOND_CPT = s.hcpc_code 
WHERE c.PRIME_CPT = '+ @var0 +'
AND c.SECOND_CPT = '+ @var1 +' 
OR c.PRIME_CPT = '+ @var1 +' AND c.SECOND_CPT = '+ @var0 +''
 
	EXEC sp_executesql @SQL