Cheap toothpaste?

I can honestly say that supermarket own-brand toothpastes are now good enough. You DO NOT need to buy the name brands to get a decent product. I like to recommend the 'sensitive' toothpastes because they're less abrasive.

Plaque around the lower front teeth?

 You get more plaque buildup around the lower front teeth because...

...saliva around the lower front teeth has higher mineral concentration. This prevents[1] tooth decay but makes plaque harden more quickly. When the plaque is hard you can't brush it off. Catching the plaque more frequently helps slow/stop buildup.

[1]  Almost perfectly. Almost...

Mercury, toxic metal or planet closest to the Sun?

 Mercury?

Is the Mercury in our fillings (and I do mean 'our') slowly killing us?

One thing is certain, it's not quickly killing us. That means it is either (A) Not killing us at all, or (B) Killing us slowly.

Hmm, where to look for reliable evidence? Definitely not in internet blogs! A reliable source of factual data is the US Food and Drug administration. Check out this link : https://www.fda.gov/medical-devices/dental-devices/dental-amalgam-fillings

Electric toothbrushes, useless fad or genuine progress?

Definitely genuine progress, but get a decent one, I like the Braun/Oral B range. DON'T get a flashy model with BlueTooth and a back scrubber attachment. Here's the check list:

1. Easily available replacement heads.

2. Decent battery technology, Nickel Metal Hydride not NiCads.

3. Timer. Two minute timer to check you are going for long enough.

4.  Err. That's it.

Modern diet is rubbish, still...

 A practical approach to reducing sugar:

Reduce - taper off how much you add to food and drink. Taper, not cut out!

Replace - change to alternative sweeteners. I know they get a bad press, but I'm an advocate. 

Refuse - try saying no to sweet stuff. You never know, you might prefer less sweet stuff. 

Modern diet is rubbish...

 Like so much of modern life, modern diet is rubbish. Eat a pre-farming diet, leaves, shoots, nuts, berries, roots (insects!?), ideally raw and your whole body, including your teeth and gums benefit. Hunter-gatherers had better teeth and better health than modern people. You can too...

Flossing

 Only floss the teeth you like->
"It's too fiddly."
"It hurts."
"It makes my gums bleed."
"I don't have time."
"Eugh, it's gross."
Have I missed any? The reasons for not flossing go on and on.

Now here's the reason for regular flossing - You'll see less of the dentist.