1. Make sure the company is a dentist or a dental lab that actually does work for dentist .
2. Make sure the bleaching gel is a pure blended gel with no fillers.
3. Make sure that the gel is a Hi-Intensity Competitive Strength Gel
   (finest quality and required by top models, actors and professionals)
4. Make sure that the gel order provides a metal syringe tip.
   (this is secret in the gel industry, syringes with a metal syringe tip last up to 3 times longer with no waste)

Most professional whitening /bleaching gels use 1 of 2 chemicals to whiten teeth: 
Carbamide peroxide (used 1 to 4 hours/overnight), or
Hydrogen peroxide (used 1/2 hour twice a day). Teeth Whitening Express bleaches thousand of people's teeth each year - compared to the 12 or 20 done in the average dental practice - and has sold the majority of professional bleaches dentist sell: Opalescence, Nite-White, Nupro-Gold, Day-White, Rembrandt and Perfecta. Although all professional bleaches use the same whitening chemicals, each vary in their success of whitening teeth and in degree of sensitivity.

  Nothing has proven to work better or achieve more dramatic results than our Hi-Intensity Gels.

Products like Nite-White, Day-White, Nupro-Gold, Opalescence, and Rembrandt  are what is called a blended gel  which use a mixture of other chemicals as a filler to make a larger syringe and appear to have a greater value. Some lower quality whitening gels can dry out the pulp of your teeth and cause a degree of sensitivity in the tooth (This sensitivity is only temporary and ceases when product use is discontinued.). Some companies use fluoride to re-mineralize the teeth caused by the glycerin, and potassium nitrate to soothe the nerves. This use of Fluoride slows down the whitening process. 
From our experience we have learned that a Pure Blend, Hi-Intensity Competitive Strength Gels are the finest quality overall that whiten best while causing the least amount of sensitivity. 

Rembrandt Extra Comfort
Whitening Chemical: Urea Peroxide
Sensitivity Chemical: Fluoride.
Base: Glycerin Base.
Wear Time: 4 plus hours/overnight
Customer/Our Review: Customers complained of sensitivity and the effectiveness of the whitener varied from customer to customer. Uses glycerin, potassium nitrate (see above) and fluoride (which slows down the whitening process).

Nupro Gold
Whitening Chemical: 10% , Competitive Strength & Hi -Intensity Competitive Strength Carbamide peroxide.
Sensitivity Chemical: Fluoride.
Base: Glycerin Base.
Wear Time: 4 plus hours/Overnight.
Customer/Our Review: Nupro-Gold whitens the same as the other products but causes less sensitivity than others but is still outdone by the Teeth Whitening Express gel. Nupro-Gold uses glycerin , potassium nitrate (see above) and fluoride (which slows down the whitening process).

Perfecta Ultra 6 / Perfecta 3/15
Whitening Chemical:6 Hydrogen Peroxide, no Fluoride, no Potassium Nitrate.
Sensitivity Chemical: None
Base: Glycol and Glycerin
Wear Time: 1/2 hour twice a day.
Customer/Our Review: Perfecta Ultra 6 is the same as Perfecta 3/15 except it is stronger. Although you have to only wear this solution 1/2 hour twice a day, it does require twice the solution to get your teeth white. Perfecta Competitive Strength
Whitening Chemical: Competitive Strength & Hi -Intensity Competitive Strength Carbamide Peroxide
Sensitivity Chemical: None
Base: Glycol and Glycerin
Wear Time: 4 plus hours/over night use.
Customer/Our Review: Customers have complained of irritation to the gums while using this product. We sell this in a tube, which is the same as receiving 19 syringes of Perfecta Competitive Strength.

Opalescence
Whitening Chemical: Competitive Strength & Hi -Intensity Competitive Strength Carbamide Peroxide
Sensitivity Chemical: Fluoride, Potassium Nitrate.
Base: Glycerin Base & others.
Wear Time: 4 plus hours/over night
Customer/Our Review: A Dentist pays around $24 for 10 syringes of Opalescence, while they pay $44.00 for a 10 syringes of Hi-Intensity Gels. Thus, making it one of the cheapest teeth whitening gel that dentists buy. It whitens well but customers have stated that it burns/irritates the gums more than our Hi-Intensity Strength Gels. 

Nite-White
Whitening Chemical: Competitive Strength & Hi -Intensity Competitive Strength Carbamide Peroxide.
Sensitivity Chemical: Fluoride, Potassium Nitrate
Base: Glycerin Base.
Wear Time: 4 plus hours/over night.
Customer/Our Review: The majority of dentists that sell Nite-White sell the older Nite-White Classic. This product whitens well but can cause a lot of sensitivity. Nite-White uses glycerin , potassium nitrate and fluoride (which slows down the whitening process).

Day-White
Whitening Chemical: 4.5% Hydrogen Peroxide
Sensitivity Chemical: Fluoride, Potassium Nitrate.
Base: Glycerin Base.
Wear Time: 1/2 hour, twice a day.
Customer/Our Review: Day-White whitens good but cause the most sensitivity of the hydrogen peroxide solutions due to the glycerin that it uses as its base. Day-White uses glycerin, potassium nitrate and fluoride (which slows down the whitening process).

Teeth Whitening Express is so confident that you will be happy with our Hi-intensity Competitive Strength Gel that we guarantee (100% money back guarantee):

• Your teeth will lighten up to 7 to 10 shades or more. We sell/sold identical name brands (Opalescence, Nupro Gold, Nite-White, Rembrandt, Perfecta, Contrast P.M.), strengths ( Competitive Strength to Hi -Intensity Competitive Strength Carbamide Peroxide), products and procedures that dentist sell Our prices are 1/3 the cost of dentist.
• Our Gel Is Rated # 1 In a blind survey