Sensory issues are common amongst children on the autistic spectrum and one of the most obvious places is in the mouth. Some children need extra sensation there while others have a very low tolerance.
Either way, it causes problems.
The Need for Extra Sensation
My youngest son was always putting objects into his mouth as a baby. In fact, it's something that he still does most of the time now, aged six. It wasn't just food that interested him, it was wallpaper - which he ate at night from the walls nearest his cot. It was toys and stones and bits of fluff too. My wife used to have to watch him closely all the time becuase he'd often start choking and have to be rescued. The sensory needs were so overwhelming though that no sooner had he spat out the object he was choking on then he would start eating it all over again.
On the first Christmas we had after he could sit up, we had to unplug the lights on the Christmas tree because he kept trying to mouth them. Later on, after I discovered a christmas light bulb in his nappy (yes, it had made it all the way through) we moved the tree entirely out of reach.
Our pediatrician wasn't much help either. He first suggested that children with low iron sometimes suck rocks and other objects to get the vitamins and minerals they need. We tested our son but his iron levels were fine. When we complained to the pediatrician about our son eating lead pencils, he simply said smiling, "he probably just wanted to put lead in his pencil". I think that was when we realised that we needed to change pediatricians.
These days, we recognize it as a sensory need and tolerate it accordingly. I say tolerate instead of "approve" because he still does a huge amount of damage to clothing and furniture with those teeth. There are sensory tools that you can get for kids to chew on but somehow we always figured that he'd prefer to seek out his own sensations.
One thing's for sure, the need for extra sensation is at least partially to blame for my son's huge appetite.
Too Much Sensation
Then there's the other side of the coin. Over-sensitive mouth tissue. This has always been a problem that I have, and it seems that my eldest son suffers from it as well.
Just the sensation of my tongue on the top of my mouth can sometimes have me itching or trying to calm down my mouth for hours. When I'm sick, an inflamed throat or an ulcer feels gigantic and has great impact because I can't stand for it to come in contact with other parts of my mouth.
The biggest impact however is in the region of food. I do have some taste issues; for example, I can't handle carrots too well and I seriously can't even look at sultanas. The thing is, that I think these issues didn't start out as taste problems. I think they started life as sensory issues.
These days, I'm grown up and I can eat carrots provided that none (or at least minimal) chewing is done. It's not so much that chewing releases the flavour but rather that it brings my mouth in contact with the texture of carrot. I can also clearly remember that my first issues with sultanas began as texture issues.
When my eldest son was just a baby, it was quite common for the feeder (usually my wife) to be covered in muck (spat out food). She used to get quite mad about it and feel that my son was mocking her. Of course, back then we didn't know about autism and we had no idea that it was texture issues.
Today, my son still eats very little. I'm not worried. I was nicknamed "sparrow" by my best friend's mother because I ate almost nothing. I survived. There were always things I could eat, eventually.
Again, there are things you can do to get around the problem, one of the most obvious being to change the texture. Try orange juice instead of oranges. Try teaching your child to use a knife to cut corn kernels from a cob instead of biting them off (I have texture issues with the cob but not with the corn). Try using a blender to puree foods, try freezing them. Try anything and everything...
...but don't panic.
As far as I know, no child has ever starved themselves to death - or even into a state of illness, for texture reasons when food was readily available. As I used to say to my wife when our son wouldn't eat. It takes about 25 days for a child to starve themselves to death - call me on day 20 if he still hasn't eaten anything.