You can use the ASCII codes for the specific type of dash you would like to display in the call to the TEXT function. For example,
plot(1:10); % This will draw a hyphen
h1 = text(2,2,['Test-example']); % This will draw an en dash
h1 = text(2,4,['Test' char(8211) 'example']); % This will draw an em dash
h1 = text(2,6,['Test' char(8212) 'example']);
Please refer to the following page to see numeric codes for the common dashes: