The problem with the cycle helmet example is that it isn't taking any other factors in to consideration.
If having helmets makes it safer on the roads, there will be a bigger population cycling, therefore a bigger population of injuries, even though many may have been saved injury
Same with the push to get people cycling from councils
More cars on the road
Faster bikes
Cycling in teh Olympics making it more popular
etc etc

To say that helmets may not be as safe as first thought, because the injuries have increased, is not showing the complete picture.
My son will not be cycling without one.

I hate wearing a cycle helmet but I wear one to set a good example to my kids. Plus if you come across some of the drivers I have you'd wear one too.

How do you know that it saved your life? Common sense or actual facts? Because the facts bear out that the helmet gave you little if any protection and probably increased the dangers both beforehand and at the actual point of impact.
The point being that the design perameter of a cycle helmet is only up to 12mph, beyond that it is next to useless, at the speed you were going the helmet offers no crush protection and indeed can amplify the forces involved, as well as the risk of twisting forces to the neck and increased brain rotation injuries, you have no way of knowing what would have happened if you weren't wearing a helmet.
Many cyclists claim a 'helmet saved their lives' without any shred of evidence to support their stance and while they can/do offer protection against abrasions/cuts and brusies at low speeds, your incident was in extremis and the statistics show that your helmet just didn't save your life at all.

Similarly to your gumshield incident, there's no way of proving one way or the other what would have happened if you weren't wearing one but data sets (as in cycling, boxing, NFL) show that so called safety aids actually don't give the protection that common sense would dictate they do and overall can/do make matters worse than commpared with no safety aid at all.

That you quote every day settings on the road as being most dangerous is interesting but in stark contrast the safest countries in the world for cycling (& have the highest rates of cycling) are the Netherlands and Denmark where the rate of helmet wearing is extremely low/virtually non existant, yet their rates of incidents/head injuries is far far lower than ours. You rarely see any kids with helmets even from very young ages.

Whilst cycling isn't RL of course, that safety equipment and the covering of heads to protect from a previous head injury & the use of gumshields to protect teeth/mouth/jaw/concussions 'seem' like the common sense thing to do, it is my belief that actually they make matters worse when looking at it from a large number POV, although I admit that from singular/anecdotal evidence there may well be [isome[/i increase in protection, it just isn't overall and especially when you see the infrequency of the injuries compared to other injuries in the sport which pretty much disproves the 'common sense' theory completely.

Get a gum shield that fits properly (from your dentist) and wear it and for cycling, its an absolute no brainer.
Until your head hits the road, its an inconvenience but, they can and do save lives.

The gum shield wont save your life, only your teeth.

I know because at its thinnest point the helmet compressed to around a quarter of its original thickness in the crash and I still sustained a fractured skull. No helmet = massive fracture.

So the helmet failed then to stop you from a fractured skull? You do realise that the amount of forces that the helmet 'possibly' stopped were miniscule compared to the absolute total forces?
Ergo it was your skull that took the majoirty brunt of the impact NOT the helmet, that the helmet probably amplified the impact made the forcs involved even worse counter acting any lessening from the crushing of the foam..
As I said, the facts bear out that helmets just do not work but people still believe that they saved their lives, I'm glad you're ok in any event.

I wear one, more to prevent being knocked out or concussed over losing my teeth but at the same time, who really wants to lose their teeth?

I never wore one because I always felt I was above getting hurt, never mind getting injured. I got hurt maybe a few times in all the time I played. I think if getting hurt and getting injured was something I thought was going to happen, I might have stopped playing a long time before I did.

The same with cycling. I personally feel that the roads are unsafe for cyclists and have no issue whatsoever with cyclists breaking the law and riding on the pavement. If I'd been through the windscreen of a car then I wouldn't be an advocate of helmets, I'd be an advocate of not cycling.

I know people who have lost teeth WEARING a mouthguard!
Are they a guarantee that you won't lose teeth or are they just there to 'assist in protecting'?

Would the fact there is an object between the glass and the skull not distribute at least some force away from said skull? As the first point of impact it seems to me some force would be sent round the helmet rather then directly into the skull. I also suspect a helmet would provide better protection from lacerations from the broken glass than bare flesh and bone. We could always test it. You have a pane of reinforced glass smashed over your bare head and I'll wear a helmet. I suspect I'll come off better.

As for gumshields, I've always worn one since having a tooth kicked out in a game (accidentally). I'm fairly certain they've saved teeth on a few occasions but I'm sure you'll disagree despite not being witness to my personal experience.

You've clearly made your mind up despite personal testimony from several people to the contrary. I'm not even sure why you've asked the question seeing as you clearly know better. So let's see some of these facts you keep citing as, well, fact.

As someone else said, in my opinion not wearing one is simply stupid. It's very easy to take a stray elbow, head or knee in the mouth and I know I'd sooner put my trust in a gumshield. It's simply a barrier to absorb and redistribute the force of an impact, and to separate the soft tissue of the lips from the teeth.

How many of the Tour de France riders didn't wear a helmet?

As for gumshields, I always wore one playing League bar the odd game as I got older. It certainly didn't make me any more likely to suffer injury. I played exactly the same way as I did without a gumshield.
I didn't use one in Union, but far fewer tackles and a more mature atmosphere meant I was far less likely to take a hit above the neck anyway.

The UCi brought them in as a compulsion (in 2003) for two reasons..one money, second there had being a death.
However they did it on a knee jerk basis (which is what the UCI do anyway for pretty much anything) WITHOUT any reference to the statistics & efficacy of helmets
Deaths in pro cycling
1950s 8, 60s..4, 70s..4, 80s..5, 90s...3, then up to 2003 before the helmet law there were 2, following the law there were 8 more deaths in the remaining 7 year period of the 2000s..Even with massively advanced technology in medical science, air ambulances, medics with all the latest kit on the scene within minutes the death toll went up when helmet compulsion was brought in.
Pro cyclists take far more risks than they ever did, they go beyond their own abilities far too often and the amount of crashes exceeds by huge amounts than what used to happen..lucklily the majority of incidents end up with arm/shoulder injuries, in fact many hits to the head would be avoided altogether if the rider hadn't being wearing a lid that increased their head size..I've seen this hundreds of times were the head would not have hit anything at all except for the fact the rider had a helmet on.
Safety aids such as these make people more reckless, they give a false sense of increased safety (risk compensation) but only recently have some professional bodies taken the stance of looking at the actual FACTS and making a decision which whilst not popular DOES save greater injury and indeed the frequency of such.

This is the same in RL IMO, it should be an area that the RFL spend some serious money on as especially in the junior game were schools are pretty much insistant that kids wear gumshields.
In the East Riding back in 2004 there was a case of a £30,000 payout because of a serious mouth injury in a hockey game at a school. However it was the lack of highlighting use of gumshields by the LEA that led to the 'negligence' aspect, that a gumshield would certainly not have given the protection offered in such a severe case failed to be highlighted at all. That at school level basic level moutguards offer very little protection anyway..but that is another matter altogether.

Basically it was falsely taken as a given that the gumshield would have saved the individual from a hockey stick swipe that did quite a nasty injury..In my belief and from other quarters it simply wouldn't.

Except in 2 stages of the Tour de France helmets weren't compulsory yet I didn't see many, if any, not wearing one.
Therefore they must see a benefit to wearing one.

I disagree on the issue of helmets. It might make some people cycle in a more dangerous manner but that's the same with any safety equipment. It's down to the individual to make that choice and to have the maturity and responsibility to deal with that choice. In the same way as you wouldn't take airbags out of an 18 year olds car.

As for RL, you are way, way off. Gumshields do not make people play in a different way. If you're going to get hit in the mouth then you're going to get hit in the mouth irrelevant of whether you wear a gumshield. And it certainly does not make kids more reckless. If anything it reminds of the fact they're doing something that's more dangerous than usual.

As Cronus said, it appears as if you've just made your mind up and will ignore any evidence to the contrary.

This.

I always wore a mouth guard. I started off with a cheap mould it yourself version which was crap. It didn't fit properly. I doubt it would give much protection.

I got one fitted by the dentist. It was much better. It's saved me from umpteen elbows in the mouth, stray knees and boots.

Getting teeth fixed is a long expensive and painful process. I'd always recommend getting a proper dentist fitted mouth guard.