In the blos­som­ing world of cos­met­ic den­tistry, teeth whiten­ing reigns supreme. Uni­ver­sal­ly val­ued by men and women alike, whiten­ing (or bleach­ing) treat­ments are avail­able to sat­is­fy every bud­get, time frame and tem­pera­ment.

Whether in the form of one-hour bleach­ing ses­sions at your den­tist's of­fice, or home-use bleach­ing kits pur­chased at your lo­cal drug­store, teeth whiten­ing so­lu­tions abound. The long and the short of it is that teeth whiten­ing works. Vir­tu­al­ly every­one who opts for this cos­met­ic treat­ment will see mod­er­ate to sub­stan­tial im­prove­ment in the bright­ness and white­ness of their smile.

Bleach­ing vs whiten­ing

Ac­cord­ing to the FDA, the term bleach­ing is per­mit­ted to be used on­ly when the teeth can be whitened be­yond their nat­ur­al colour. This ap­plies strict­ly to prod­ucts that con­tain bleach–typ­i­cal­ly hy­dro­gen per­ox­ide or car­bamide per­ox­ide. The term whiten­ing, on the oth­er hand, refers to restor­ing a tooth's sur­face colour by re­mov­ing dirt and de­bris.

So any prod­uct that cleans (like a tooth­paste) is con­sid­ered a whiten­er. Of course, the term whiten­ing sounds bet­ter than bleach­ing, so it is more fre­quent­ly used–even when de­scrib­ing prod­ucts that con­tain bleach.

Ex­am­in­ing enam­el

Most of us start out with sparkling white teeth, thanks to their porce­lain-like enam­el sur­face. Com­posed of mi­cro­scop­ic crys­talline rods, tooth enam­el is de­signed to pro­tect the teeth from the ef­fects of chew­ing, gnash­ing, trau­ma and acid at­tacks caused by sug­ar.

But over the years enam­el is worn down, be­com­ing more trans­par­ent and per­mit­ting the yel­low colour of dentin–the tooth's core ma­te­r­i­al–to show through. Dur­ing rou­tine chew­ing, dentin re­mains in­tact while mil­lions of mi­cro-cracks oc­cur in the enam­el. It is these cracks, as well as the spaces be­tween the crys­talline enam­el rods, that grad­u­al­ly fill up with stains and de­bris.

As a re­sult, the teeth even­tu­al­ly de­vel­op a dull, lack­lus­tre ap­pear­ance.

Teeth whiten­ing re­moves the stains and de­bris, leav­ing the enam­el cracks open and ex­posed. Some of the cracks are quick­ly re-min­er­alised by sali­va, while oth­ers are filled up again with or­gan­ic de­bris.

Tooth dis­col­oration

There are two cat­e­gories of stain­ing as it re­lates to the teeth: ex­trin­sic stain­ing and in­trin­sic stain­ing. Ex­trin­sic stains are those that ap­pear on the sur­face of the teeth as a re­sult of ex­po­sure to dark-coloured bev­er­ages, foods and to­bac­co, and rou­tine wear and tear. Su­per­fi­cial ex­trin­sic stains are mi­nor and can be re­moved with brush­ing and pro­phy­lac­tic den­tal clean­ing. Stub­born ex­trin­sic stains can be re­moved with more in­volved ef­forts, like teeth bleach­ing.

Per­sis­tent ex­trin­sic stains can pen­e­trate in­to the dentin and be­come in­grained if they are not dealt with ear­ly. In­trin­sic stains are those that form on the in­te­ri­or of teeth. In­trin­sic stains re­sult from trau­ma, age­ing, ex­po­sure to min­er­als (like tetra­cy­cline) dur­ing tooth for­ma­tion and/or ex­ces­sive in­ges­tion of flu­o­ride. In the past, it was thought that in­trin­sic stains were too re­sis­tant to be cor­rect­ed by bleach­ing.

To­day, cos­met­ic den­tistry ex­perts be­lieve that even deep-set in­trin­sic stains can be re­moved with su­per­vised take-home teeth whiten­ing that is main­tained over a mat­ter of months or even a year.

Whiten­ing op­tions

Three ma­jor teeth whiten­ing op­tions are avail­able to­day. All three re­ly on vary­ing con­cen­tra­tions of per­ox­ide and vary­ing ap­pli­ca­tion times.

In-of­fice whiten­ing

Sig­nif­i­cant colour change in a short pe­ri­od of time is the ma­jor ben­e­fit of in-of­fice whiten­ing. This pro­to­col in­volves the care­ful­ly con­trolled use of a rel­a­tive­ly high-con­cen­tra­tion per­ox­ide gel, ap­plied to the teeth by the den­tist or trained tech­ni­cian af­ter the gums have been pro­tect­ed with a paint-on rub­ber dam. Gen­er­al­ly, the per­ox­ide re­mains on the teeth for sev­er­al 15 to 20 minute in­ter­vals that add up to an hour (at most).