I played both codes of rugby when I was a growing up for nearly a decade. I was never injured in any way and was probably hurt only a few times. I never wore a gumshield and to be honest I don't think I ever gave it any thought. In my mind it was simply not needed and I cannot remember anything ever happening during a game where I would have been helped by wearing one.

In terms of cycling it was pretty much the same. I never really needed a helmet so wearing one would have been pointless. Even though I had a BMX bike I was never any good at any tricks so didn't need one. I do remember one spectacular case of going over my handlebars because my front wheel locked for some reason. But I think even in that case it wasn't my head that needed protecting, it was my hands, arms and knees.

When I played I always wore one. As a kid, the cheap molding type then as I got older I had them made for me through a dentist so that it fit exactly and never fell out. They are definitely worth it if you value your teeth. The cost of a well made gumshield or the cost of reconstructive dental work?

It all depends if you like to gamble...

I always found it difficult to speak clearly with a gum shield in, but as a prop communication was never really a key requirement so it didn't matter. Many moons ago I was playing in a game and I got stiff armed in the face, and I actually saw star bursts like I was a cartoon character who had been bashed over the head. After the game when I took my shield out I found my jaw ached like mad, I dread to think what it would have been like had I not been wearing one.

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.