Q. What causes extrinsic stain?
A. Extrinsic stains are dental stains primarily caused by substances sticking to the surfaces of the teeth. In most cases, extrinsic stains are caused by typical culprits like tobacco, coffee, and tea. Less common causes are red wine, blueberries, and other food stains. However, an individual dentition can be more susceptible to particular stains. For instance, some people can eat a bowl of blueberries and their teeth are fine, while others end up with their teeth stained dark blue. In addition, iron supplements, certain medications, and chlorhexidine mouthrinses can also produce extrinsic staining. Methamphetamine use is extremely destructive to the esthetics of the smile as well as general oral health. Dental hygienists need to investigate this possibility during the health history and ask leading questions without judgment. The role of the dental professional is to help patients and pointing out the detrimental effects of certain drugs or habits can be an important step in that direction.
Q. Are other factors involved in extrinsic staining?
A. Teeth can sustain tiny microcracks, which may also influence extrinsic staining since teeth with microcracks may not get the desired bleaching results. Teeth may have been injured or shattered due to an accident. They are visible only with an intraoral camera or when a bright light from the lingual surface transluces the enamel. In our practice, we have intraoral cameras installed in all our of our dental hygiene operatories. This is such an intense, bright light that the microcracks become detectable. If dental hygienists do not have access to an intraoral camera, they can get an intense light that transilluminates from the lingual, which will show if microcracks are present. Finding these cracks is important because, depending on the depth of the microcracks, bleaching can make these areas appear streaky. The bleaching agent can penetrate to the depth of the microcrack, making it appear even whiter than the remainder of the enamel surface.
Q. For patients with microcracks and extrinsic staining, are restorations the best avenue for a more esthetic result?
A. Usually not. For extrinsic stains the best treatment is prevention. Although restorations can possibly mask mild to moderate forms of tooth discoloration, it all depends on the underlying color of the tooth surface. After polishing these stains off, if the tooth color is good then no restorative solution is indicated. However, if the shade of the enamel is less than the patient would like and bleaching is not the best treatment option, then porcelain laminates might be the best answer. I do not recommend bonding with composite resin since the outer layer of the composite resin surface will collect more stain than a porcelain surface. If patients are not interested in restorations, a viable solution is monthly dental office visits for preventive polishing, which may keep extrinsic stains from penetrating too deep into the teeth. In addition, in-office power bleaching can be tried to minimize the presence of the stains. The best indication for thin veneers is teeth that could benefit from slight “building out.” For teeth that are protruded, a better alternative may be an all-ceramic crown, which can totally mask the tooth discoloration. In my opinion, dental hygienists should discuss all the available alternatives with the patient, discussing both the benefits and the disadvantages of each method, so the patient can decide which alternative best suits his or her situation.
Q. What is the basic treatment for extrinsic stain?
A. To treat extrinsic stains, coarse pumice should first be used to polish the stains off the surface of the teeth. An air abrasive polisher may be necessary. However, this should not be used on patients with porcelain or ceramic surfaces. I recommend having the hygienist photograph the stained tooth or teeth, polish the surface, finish the prophylaxis, and then take another picture so the office can have a baseline of what the tooth looks like without the stain, plus a timeline of how much the tooth stains within a given period. The tooth/teeth should then be monitored for approximately 4 weeks to see how fast and how much the stain returns. The hygienist may also want to suggest certain toothpastes that contain chemicals to remove surface stains, which help prevent surface staining.
Q. Do some people experience heavier stain than others, regardless of lifestyle factors like tobacco or coffee use?
A. Some people have a metabolism that increases their likelihood of extrinsic stains. For instance, some diseases and categories of drugs lead to a marked decrease in salivary flow. This in turn causes the translucent salivary pellicle layer to change its nature and pick up more extrinsic stain. Stains, which are normally not present when salivary flow is normal, attach to this altered pellicle layer. The salivary pellicle that picks up stains most of the time forms normally. In fact, after the hygienist cleans the teeth of the patient, the process—called adsorption—starts all over again as soon as the saliva touches the teeth and the protein pellicle layer is pulled from the saliva and almost seems to bond to the enamel. The best solution to this problem is to increase the saliva flow of the patient. The simplest way to accomplish this may be to prescribe sugarless gum. As little as three or four sticks a day can make a difference in the level of saliva flow. Another option is to change medications but this may not be as easy as increasing the patient’s natural salivary flow. Until this situation is under control, more frequent prophylaxis appointments can be scheduled.
Q. So for the patient who presents with an unknown cause of stain, do the whitening treatments have positive results?
A. In cases where the cause of the stains is unknown, the dental professional needs to play detective to determine what is originating the stains. This is crucial since the stain formation can be minimized by changing or eliminating the specific habit that is causing the stains. If neither the patient nor the dental professional can find the cause of the stains, then I recommend the patient schedule monthly professional prophylaxis to minimize the offending surface stains. In addition, the dental professional needs to polish the enamel more and, hopefully, this will help reduce the stains by having smoother enamel. However, frequent polishing with abrasives can roughen the enamel and make it more susceptible to stains depending on the consistency of the hydroxyapatite crystals in the enamel. Chances are abrasive pastes will not hurt since they are necessary to remove the stains. However, if an air abrasive is constantly used, the enamel can roughen up depending on the abrasive and the amount of compressed air being used.
Q. For these patients who experience heavy stain with no known etiology, are restorations recommended?
A. Porcelain veneers may be an aggressive technique to solve this condition because their application can be an invasive procedure. In my opinion, the use of veneers is justified if there are defects on the teeth, if the teeth also have other arch alignment problems, or if the patient refuses to undergo orthodontic treatment. In such cases, porcelain laminates can eliminate the stains, provide a satisfying tooth color, and align the teeth in a better position.
Stay tuned for parts two and three, which will cover intrinsic staining and treatment options, respectively.
From Dimensions of Dental Hygiene. March 2007;5(3): 30, 32.