As an avid contact wearer, I use saline solution to rinse my contacts daily before each use. Recently, a friend told me that many commercial saline solutions contain preservatives, which could affect the overall health of my eye. Is this something I should be concerned about? The saline I use has always felt comfortable so I never thought it could pose a problem.

1) I'm considering getting my tongue pierced. Is there anything I ought to know before I get it done? What should I look for in a piercing place? Does the piercing ever have negative effects — I don't know, tongue paralysis or something? Thanks!

2) If and when I decide to take my tongue ring out, I worry that there will be scarring tissue or an ugly hole in the middle of my tongue. Is this the case?

I read that disposable contact lenses are actually worse for your eyes than the normal one-year ones because they allow less oxygen to go to your eyes, and the only advantage is that there are less cleansing problems. Also, it is claimed that inadequate oxygen to your eyes (possibly caused by prolonged wearing of contact lenses) leads to a condition when extra blood vessels sprout around the iris, which leads to sight problems at old age. Is that true?

I am very concerned because I normally wear (one-year) contact lenses from 8am to 8pm, and maybe to 12am during reading periods. I don't feel very comfortable with glasses because they give distorted visions and fatigue. I thought switching to disposable contact lenses would do my eyes good. My current lenses contain 38 percent water. Is this good enough?

1) I often have a bad taste in my mouth, and bad breath as well, I assume. This doesn't stem from poor hygiene: I brush my teeth at least three times a day, and usually more. I'm wondering if there is anything I can do about this. Could this be a symptom of some sort of nutritional deficiency? I think my diet is pretty bad, although I'm working pretty hard on getting more protein and eating less fat. I've also been nauseous a lot lately, and vomiting some. Could that be related?

2) Like many people, I often have an embarrassing bad breath. Listerine and other mouthwashes won't be of any help for this chronic problem. There are lots of products available to get rid of "volatile sulfur compounds (VSC)" - that supposedly cause this — and I just don't know which one I should try. Also, what's your opinion on tongue-brushing?

1) Which is better for you, tap or bottled water?

2) How bad is the water here in New York City? Do you recommend drinking filtered water, or does it really make a difference?

What is the significant difference between a product that is antiseptic and one that is antibacterial? All of the antiseptic mouthwashes I find have a great amount of alcohol in them. This can be very irritating to the mouth. I have found one that is alcohol free, but it says it is antibacterial.

Thanks for your help.

So far I have been extremely impressed by your service. I trust you with a question which I know many people share: Are whitening toothpastes detrimental to the longevity of one's teeth?

I was told by my dentist that my teeth eroded, due to consumption of too much acidic food. I would like to know what kind of food causes tooth erosion. Do you have a list of these foods?

Do you know anything about the safety of eyelash extensions?

I was having a conversation with my roommates about pop and coffee and we were wondering which is worse for your teeth, the pop or the coffee? And what do they do to your teeth when you drink them?

For the last year or so, I haven't been able to cry anymore. And when I do, absolutely no tears come out. My eyes just water up, but there are no tears. Is this normal? Should I be worried?

What causes fever blisters on lips and how should they be treated? Also, what is the difference between fever blisters and shingles?

I just came here this fall. Since then, my nose has been bleeding occasionally without any injury. My friend told me it was because of the dry air of U.S. Is he right? How can I prevent this situation? I also have a problem when I brush my teeth. My gums are always bleeding and not just a little!! What should I do? Thanks.

My eyes feel dry and swollen after hours of staring at the computer monitor. Is there any long range harm caused by spending both work and play time in front of the computer? I work out, and eat a healthy, low-fat diet. I don't have any other vices except perhaps a higher than normal caffeine intake.

This week I'm getting my tonsils and adenoids taken out. I've never had surgery before and I don't know what to expect. Can you explain please?!?

My question is regarding eye exercises. I am short sighted and wear my glasses constantly. Recently I came across some eye exercises which claim that they can help you restore your vision. Their reasons seem convincing. But if this were true, why do the majority of people with poor vision still wear glasses. I just want to know if it's possible to restore your vision by doing these exercises? If not, is there any other way to restore vision without undergoing surgery? Finally, is there any way to ensure that my eye sight does not get any worse?

When both of you have braces, and you do happen to get stuck together, is there any way to unhook without help from anyone other than you and him?

1) What is TMJ? What kind of doctor handles this problem?

2) I have a rather odd problem. For the past several years, I have noticed that when I open my mouth wide to yawn or take a bite out of a sandwich, the right condyle of my jawbone slips laterally from the temporomandibular joint, making it difficult, and at times, painful, to close my mouth. I basically have to slip the condyle back into the socket; otherwise, it slips in by itself, which is what causes the pain.

Other than being inconvenient, this has not adversely affected me in any way that I can tell, except that I am now careful not to open my mouth completely when I yawn. I am reluctant to see a doctor about this because I cannot reproduce the situation at will, and don't know if the problem can be diagnosed or detected unless the doctor actually sees the condyle slip out.

Also, any time I have gone to Health Services, it seems that whatever the problem, they just send me home with a jar full of ibuprofen. What do you think is wrong? Is this problem serious? Does it deserve immediate attention? What type of doctor would I need to see and could I get a referral from Health Services?

Dear Alice,

Is it dangerous to sleep in your soft disposable contact lenses for one night if you can't get them out?

My eyes are light-brown, and when I've been crying or when it's bright outside they look greenish. I want my eyes to be that greenish all the time. I heard that putting honey in your eyes will lighten them. Are there any side effects? Is it bad for my eyes?

I find it relaxing, along with rubbing my face, to rub my eyeballs (with my eyelids closed, of course). It feels good to massage the muscles and squeeze out the air that builds up back there. Is this safe? Do I risk deforming my eyeballs and changing my vision?

I recently saw a health show on TV that said you should wear darker sunglasses because they filter more light. Previously, I had heard that darker sunglasses cause the pupil to open wider and make the eyes more vulnerable to harmful light; ergo, you should wear lighter sunglasses with good UV protection. I have very light colored eyes, so my eyes are especially vulnerable to harmful light anyway, which is why I really want to get this right. Can you give me a definitive answer on this one?

Here's a question I have been debating with a friend for a while, and seeing as how I'm not scheduled to go to the dentist again for a while, I thought you could shed some light on the issue: when brushing one's teeth, should one also brush one's tongue? I would think yes, because what's the point of brushing germs off teeth if the tongue still has them there, and will transfer them to the teeth as soon as you're done brushing. My friend thinks it makes absolutely no difference. So does it matter? We have an ice cream wagered on this one! I hope I'm right!