Light activation ups tooth sensitivity during bleaching

[drsushant]

 Light activation ups tooth sen

 Light activation ups tooth sensitivity during bleaching

Use of light activation increases the risk of tooth sensitivity during in-office bleaching and also may not improve the bleaching effect, according to a new systematic review and meta-analysis (Journal of Dentistry, August 2012, Vol. 40:8, pp. 644-653).

With the rising popularity of teeth whitening, new systems have been developed that use light — including halogen, curing lights, xenon-halogen lights, plasma arcs, light-emitting diodes (LEDs), lasers, and LED plus lasers — to speed up the whitening process while generating less heat, according to the study authors, from Sichuan University and Sichuan Center for Disease Control and Prevention in China.

While many manufacturers have claimed that light-activated bleaching systems can lighten tooth color by eight shades or more in just one visit and the media also has highlighted its benefits, the scientific literature remains divided, they noted.

And while some studies have shown positive effects of light activation, others have demonstrated little to no contribution to outcomes, and all the while there has been increasing focus on tooth sensitivity during light-activated bleaching.

While several reviews of light-activated bleaching are available in the literature, no one has conducted quantitative assessments of the original studies, and the volume of information makes it difficult to draw conclusions, according to the study authors.

The researchers conducted a literature search using Medline, Embase, and Cochrane Central up to September 2011 and considered all randomized controlled trials (RCTs) or quasi-RCTs comparing light-activated bleaching systems with nonactivation bleaching systems.

The meta-analysis ultimately included 11 studies: nine RCTs and two controlled clinical trials. All 11 compared bleaching efficacy, and seven compared tooth sensitivity.

The studies involved subjects age 18 years or older. Only in-office bleaching systems were included, and the light activation method could involve any kind of light.

The researchers found that a light-activated system produced better immediate bleaching effects than a nonlight system when lower concentrations of hydrogen peroxide (15% to 20% HP) were used. However, when high concentrations of HP (25% to 35%) were employed, they found no difference in the immediate or short-term bleaching effect between the light-activated system and the nonlight system.

The meta-analysis also demonstrated a significantly higher likelihood of tooth sensitivity with the light-activated system than with the nonlight system.

"Tooth sensitivity is the most frequently reported side effect after vital tooth bleaching," the authors wrote. "Our pooled analysis suggests that a light-activated system is likely to increase the occurrence or severity of tooth sensitivity."

Because light increases the risk of sensitivity during in-office bleaching, clinicians may need to reconsider the rational application of bleaching lamps, the authors noted. Also, when light activated bleaching procedures are conducted, dentists should follow the manufacturer’s instructions to limit the duration of light activation, especially to minimize undesired pulpal responses.

"Light increases the risk of tooth sensitivity during in-office bleaching, and light may not improve the bleaching effect when high concentrations of HP (25% to 35%) are employed," the authors concluded. "Therefore, dentists should use the light-activated system with great caution or avoid its use altogether."

A recent clinical study that looked at both bleaching effectiveness and sensitivity reached a similar conclusion (Operative Dentistry, May/June 2011, Vol. 36:3, pp. 251-257).

The study evaluated the effects of LED and laser activation during in-office bleaching where 30 caries-free patients were divided into two groups: light-activated and nonactivated groups.

"After two bleaching sessions, the use of LED/laser light activation did not improve bleaching speed," the study authors wrote. "Persistent tooth sensitivity and higher tooth sensitivity after 24 hours of bleaching were observed when light activation was used."

        

[drmithila]

Bleaching molecules penetrate into your teeth increasing blood flow and pressure in the tooth pulp causing mild pulpitis. Although diffusion into your teeth helps amplify whitening effects since chromophore molecules in your tooth dentin can be broken up by hydrogen peroxide, the increased pressure irritates the tooth nerve slightly and makes your teeth more sensitive to stimuli in general. Everyone responds differently and this mild pulpitis can last for about 2 weeks after whitening.

Increased tooth porosity and removal of the protective protein layer on the surface of your teeth. We talked about how maintaining the protein pellicle is important in keeping the pores in exposed dentin closed off from the oral environment. For better or worse, all whitening products must strip off this protein layer in order to dissolve surface stains. This will open up pores in exposed dentin and cause sensitivity.
How to Relieve Sensitive Teeth after Whitening

Brush your teeth before whitening not after whitening. Brushing right after whitening will further open pores on exposed dentin and create sensitivity. It can also damage your enamel since some bleaching agents are slightly acidic. Let your teeth recover afterwards.

 Use a Desensitizing Gel to calm your the nerves in your teeth prior to whitening. For the most relief, you should apply the gel to your teeth for 10 to 30 minutes before bleaching using the same bleaching trays you got from your dentist and rinse afterwards. Ideally, the gel should contain both 5% potassium nitrate and fluoride. Your dentist is able to prescribe specifically designed desensitizing gels like UltraEZ™, Desensitize!, and Relief™, but in a pinch you can also try using in the trays a desensitizing toothpaste that contains 5% potassium nitrate. Using toothpaste instead of the commercial gels may also be a more cost-friendly method. Some ingredients in the toothpaste though might irritate your gums a bit, and if that starts to happen stop and let your dentist know.

Whiten as directed.

Rinse out your mouth thoroughly after bleaching with water, or better still a pH re-balancing mouth rinse. Although bleaching companies try to make products that are pH balanced, many end up being slightly acidic. Getting your oral pH back to normal lets your teeth begin to recover.

Use your finger (or q-tip) to gently apply to your teeth one of the Calcium-Based Desensitizing pastes we discussed last week. Let the paste set for a few minutes and then spit thoroughly; do not rinse for at least 30 minutes following application. By gently coating your teeth with a product like MI Paste or Colgate’s Pro-Argin Toothpaste, you will plug up open pores on your teeth and reduce sensitivity. Additionally, the remineralizing effects of these pastes help to improve whitening.
Additional Tips to Prevent Tooth Sensitivity Caused by Whitening

Do not use higher concentrations of bleaching agents than you need for the whitening results you want. The amount of pulpitis caused by the diffusion of bleaching molecules into your teeth is a function of the concentration of the hydrogen peroxide or carbamide peroxide in the bleaching product, and how much is able to enter the tooth. It is also important to keep in mind when examining bleaching concentrations that carbamide peroxide is about ⅓ as strong as hydrogen peroxide.
You can opt to use Crest White Strips instead of Tray or In-Office bleaching if you don’t need additional whitening. Although Tray Bleaching and In-Office Bleaching offer many advantages, they allow more bleaching molecules to enter your teeth. Whitening Strips on the other hand, don’t allow many bleaching molecules to enter your teeth because of their design, and this means that you will have less sensitivity.
Do not leave in bleaching trays for longer than directed.
Modify your diet to limit acids during active whitening periods. If you do a one step in-office whitening this really only applies to the first day or two after whitening, but this is more important if you are in the middle of two weeks of using Crest White Strips. Bleaching therapies of all kinds lift the protein pellicle off your teeth making your teeth more vulnerable to acids during this time. With the pores on exposed dentin already more open to the oral cavity because of bleaching, you don’t want acid erosion from foods or drinks to make this worse.
Anti-inflammatories like Ibuprofen can be helpful for sensitivity if taken prior to whitening, but the effect doesn’t last more than a couple hours so you’ll have to take more. To work as they should, you should take 600mg of Advil (Ibuprofen) about an hour before bleaching. Consult your doctor before taking any medication.

 

 

        

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