DENTAL CARE: HOW TO CLEAN YOUR DOG'S TEETH

• Apply the toothpaste to the brush and then push it down into the bristles
• Choose a time when your dog is settled. Sit him down quietly, either on the floor or for a small dog, on your lap.
• Place your left hand across the bridge of the nose or muzzle, with a finger or thumb under the chin to keep the mouth closed. Gently lift the top lip and insert the toothbrush inside the cheek. The most important place to brush is at the gum line.
• The goal is to brush the outside surfaces of all the teeth in a systematic way. Initially your dog may not co-operate for long enough; if so, start brushing at a different position in his mouth each time.
• Start by cleaning the back teeth, particularly the upper ones and then the canine teeth. Once the dog is happy to accept this, progress to the front teeth. 
• Brushing the inner surfaces of the teeth can prove to be difficult. If you are unable to do this, do not despair. Providing the rest of the teeth are reasonably clean and healthy, the tongue will do quite a good job of this.
• Move the brush in gentle circular motions. DO NOT scrub the teeth. 
• Toothbrushing should be carried out daily. 
• If your pet has very inflamed gums (gingivitis), your vet may advise that you use a dental gel or solution containing chlorhexidine to improve the gums. Chlorhexidine works best when combined with daily toothbrushing to remove the debris.
• Remember, there is no point wrestling with your dog. Try to make it an enjoyable experience. If your dog behaves well, reward him with a small healthy treat.

Source Link- http://www.dogstrust.org.uk/az/d/dentalcare/howtocleanyourdogsteeth09.aspx#.UDNn1aogfpA