There's a whole lot of sanding, planing and buffing going on in bathrooms coast to coast. The work isn't to improve the home, but the skin, through the magic of over-the-counter microdermabrasion kits.

At a cost of $10 to $200, the home kits can be considerably less expensive than the $100 to $200 you shell out for a single, in-office microdermabrasion session. And no appointment is necessary. But how do the kits compare with the real thing — and with each other?

When performed in a health facility or aesthetician's office, microdermabrasion involves scraping off the top layer of dead skin cells, known as the stratum corneum, with a wandlike device that either abrades the skin with a roughened surface or blasts abrasive crystals, such as aluminum oxide, onto the skin. A vacuum device sucks up the debris as the exfoliation goes along.

Professional microdermabrasion takes about 30 minutes and usually requires four to 12 sessions — spaced a few weeks apart — for best results.

"The medical-grade microdermabrasion procedure works by producing micro-trauma or gentle exfoliation to the outermost surface of the skin to remove surface debris," said Joseph Greco, a dermatologist at the University of California at Los Angeles Dermatologic Surgery and Laser Center. That debris includes oil, dust and dead cells that can clog pores and create roughness. In removing that top layer of skin, microdermabrasion can also reduce the appearance of brown spots, acne scars, fine wrinkles and large facial pores.

Home kits now offer an inexpensive, convenient and gentle alternative to a professional session. They don't penetrate as deeply into the skin surface as medical-grade microdermabrasion, and that's both a plus and a minus — almost no side effects but subtler results.

"With continued use, you can get an improvement in fine wrinkling, mottling and brown spots, and you can mildly affect acne scarring," said Dr. Justine Park, assistant professor of clinical dermatology at the University of Southern California.

The only real downside to the kits is that some people may tend to overuse them, scrubbing too much or using them too often, said Sonia Badreshia-Bansal, a San Francisco-area dermatologist in private practice. Fortunately, those who overdo generally figure it out pretty fast.

Said Park: "Typically, you start feeling pain."

The kits can also exacerbate skin conditions like acne, rosacea or eczema, and are not recommended for anyone with an active infection in the treatment area. Microdermabrasion can worsen or spread the infection.

Medically, there isn't a lot of difference between the cheaper kits and the expensive ones, Greco said. The more expensive ones tend to have nicer hand-held devices and more elegantly packaged creams and moisturizers.

We tested three kits against an office visit, and here are the results.

NOVA SKIN CARE SYSTEM

Review: Although the directions were easy to follow, this was the most complicated of the three at-home sessions, with several phases of treatment required. The applicator, which purrs with sonic ferocity, was a little wide to hold comfortably, was noticeably stronger than its at-home brethren and caused a slight stinging, even on a low setting. Without question, the Nova polished the skin more effectively than the Neutrogena and Dove systems.

Cost: $199.80. Includes a battery-operated, three-speed applicator; 20 reusable microfiber applicator pads; washable bag for laundering the pads; a cleanser; exfoliator gel; and moisturizer. The device vibrates at 1,000 to 2,000 cycles per second. That's a lot. www.novaskincare.com.

NEUTROGENA

Review: The device worked well and was easy to use. It wasn't overly harsh on either speed and left a smooth feel that can't be had with regular washing. But the crystals were gritty and hard to wash off. Unlike the Nova, the applicator lacked an automatic shut-off. The pad is reusable.

Cost: $39.79. Includes a battery-operated, two-speed applicator; two removable foam heads; and cream. The applicator vibrates at 70 to 86 revolutions per second. www.neutrogena.com/advancedsolutions/product_mda.asp.

DOVE SKINVITALIZER

Review: Great value for the price. The exfoliation was gentler but left the skin feeling less polished than the exfoliation provided by the Neutrogena and Nova systems.

The device was simple to use and lightweight. Good choice for someone who finds the more expensive dermabrasion products too harsh. The pads are designed for one-time use, which could hike the price over time.

Cost: $11.99. Includes a battery-operated applicator, six double-sided facial cleansing pillows — one side for cleaning and one for exfoliating. www.doveskinvitalizer.com.

PROFESSIONAL SESSION

Review: An in-office microdermabrasion session was not just a cut above the home sessions, it was a whole different ballgame. Using short, rapid strokes, an aesthetician operated a titanium-coated hand-piece that deposited microcrystals on the skin. A tube contained within the handpiece aspirated the crystals and skin debris. The effects were impressive. A 30-minute office session virtually eliminated all the skin irregularities noticeable under a bright light.

Cost: $125. Performed with ImageDerm Microdermabrasion System, which uses medical-grade aluminum oxide crystals. For general information, see www.health.howstuffworks.com/microdermabrasion.htm.