Most Silky's don't really need their teeth scaled until between one and two years old. You can spray sensitive gums with Chloraseptic spray or you can use teething gel to numb them. This works particularly well for older dogs. Squirt this over the tarter buildup and let set for a couple of minutes. The Plax help to loosen the tarter to make scaling easier.
Most doggy vendors carry a variety of scalers.
It's nice to have two or three with different edges for the best tarter removal. Start at the gum line and gently but firmly scrape the tarter away from the gum and off the tooth. Wipe the scaler clean as needed. I also wipe the tooth with a Q-tip. This helps to clear the area so you can see if you got everything off the tooth surface.