Some individuals have a hard time noticing the sole of their shoes wearing out. The shoes seem fine until one day there is a hole that seems to come out of nowhere. The choice is to either pay to have the entire sole replaced or throw out the shoes. Patients seldom notice the wear on their teeth and fillings until the wear is severe or the tooth is broken. Costly repairs are then in order, since throwing out your teeth is not expedient or acceptable in our society.
There are several types of wear and tear that occur with our teeth and the surrounding tissues. These include cracking of individual teeth, wear cups on the biting surfaces of the back teeth, eroded notches in teeth along the gumline, flattening out of groups or all your teeth, bone breakdown, and joint wear.
Cracking of individual teeth
The chewing teeth, or molars, in the back of your mouth have points (cusps) and grooves or valleys (fossae). A cusp of an upper tooth will bite into the fossa between the cusps of the lower tooth, acting as a wedge. Likewise, cusps on the lower teeth will bite into the fossae between cusps on the upper teeth, also acting as a wedge. Our teeth are very strong, but after 40 or 50 years of chewing, weaker areas in the teeth may finally give way and entire sections or cusps of teeth may break off. Left unrepaired, this will allow shifting of the involved teeth and even stronger wedging forces on the remaining teeth in the area. A second fracture on one of the involved teeth is very common. Fractures on the teeth on the other side of the mouth are fairly predictable.
Fractures are even more frequent in teeth weakened by fillings. A very common phrase dentists hear from their patients is, “That was a great filling. It lasted 20 years.” In truth, the old amalgam fillings, made of silver and mercury, can exist in the mouth, but barely. Excessive drilling may be required to hold amalgam fillings in place. This drilling encourages the weakening process. Cracks in the tooth begin, at first at the outer and inner corners at the base of fillings that go in between your teeth. Amalgam fillings tend to wear down as you chew on them. This weakens the filling and can result in a crack in the filling itself, making the underlying tooth vulnerable to recurring decay. A worn down filling allows for a greater wedging effect from the opposing tooth that bites against the tooth holding the filling. Cracks then propagate through the tooth. These cracks sometimes are responsible for sensitivity, especially when chewing on thin food such as small seeds or lettuce. Cracks will propagate more rapidly if you chew ice or clench your teeth. If a cracked tooth can be saved, the appropriate treatment is a crown. In less fortunate circumstances a root canal or extraction may be required.
If your tooth can still hold a filling, be sure the filling is a bonded composite or inlay. The bonding will add strength to the tooth and can prevent cracks from propagating, thus making it much less likely that you will require crowns later. If you have amalgams in your mouth that have been there for 15 years or more, unless they are very small, ask your dentist if it would be a good idea to replace them to prevent future cracking of teeth. Your dentist should have enough experience to judge whether your teeth are likely to crack or not.
For the best results, dare to use one of the following killer statements:
“I want restorations that are the least likely to break down or leak in the next 20 years.” If you are bold, substitute “30”, for “20”, but realize that most dentists haven’t had 30 years experience watching restorations as they break down or leak.
“I am counting on your skills to help this work last until I die.” This statement has a flattery element that will encourage the dentist to do the best he or she could ever do.
Gumline notches and potholes on biting surfaces
Many patients develop notches in their teeth, along the gum line, right where the enamel ends and the root surface begins. The most common teeth to have these notches are the upper and lower bicuspids (halfway back on the side), but they may occur on every tooth in the mouth, including on the lingual (tongue side) of the teeth. On some patients these notches deepen rapidly and are quite sensitive. On other patients their progress is arrested.
Most patients believe these notches are from toothbrush abrasion. Hard brushers may develop deep, sharp notches. But these notches are also prevalent in patients who do minimal scrubbing. It is clear that other factors come into play. Two conditions almost always exist when notches are present. First the patient has lost bone or the bone is very thin over the root adjacent to the affected area, allowing exposure of the softer root surface. Second, the patient exhibits a strong side-to-side chewing motion on the affected teeth. If you are a hard chewer or grinder, then more teeth can be affected.
Here is how the process works. The portion of a tooth under the enamel, called dentin, has a slight flex. The enamel on the outside of the tooth provides a veneer effect, much like the way plate glass is layered, giving strength and rigidity. When you place sideways forces on your teeth, stresses under the enamel release themselves through the dentin at the junction where the enamel ends and the root begins near the gumline. This creates a weakening or softening of the dentin. Subsequent brushing can then more easily remove the softer tooth structure, creating a sensitive and notched tooth.
All but the most severe cases can effectively be treated with bonded composites to fill in the notches. This will reduce or eliminate future erosion of the tooth surface if you and your dentist take the other necessary actions.
PRO-TIPs: If you have notches along your gumline, by all means have them repaired, but also take these steps:
Some patients also develop pothole-like defects on the biting surfaces of their teeth. These occur most often on the first permanent molars, but can occur on any teeth. Their location is usually on the tips (cusps) of the teeth. Under magnification they look like little cups in your teeth. Their cause is from a combination of grinding that wears through the enamel, and clenching that causes stress and weakening of the exposed dentin. Acids, either naturally occurring in the saliva, from acid reflux or frequent vomiting, or from sodas and sweetened beverages hasten this wear process. This wear may occur in the late teens or early 20’s, with severe cases usually appearing in the fourth or fifth decade. Development of pothole type defects is frequently accompanied by the gradual wearing away of the cheek side or tongue side of the teeth. These lesions are precursors to severe tooth damage, therefore, they should be addressed when they first develop. Early detection and preventive treatment is critical to preventing extensive dental needs.
Severe wear comes from grinding or bruxing of the teeth. It may be accelerated by acidic conditions. Severe wear patterns may be concentrated on the front teeth, the back teeth or both front and back teeth. When the front teeth are affected it is easy to see that the teeth are shortened and worn, making the victim appear older than he or she actually is. Front teeth with flat edges can provide a vigorous “look” to an outdoors type man, but they definitely are not flattering to a woman’s smile.
For most patients who exhibit severe wear, facial height decreases. This means the nose and chin come closer together with aging, resulting in a thin, unsupported appearance of both upper and lower lips. When you see someone with this wear, you may mistakenly think they are wearing ill-fitting dentures. Correcting severe wear damage by building the teeth back up can provide a beautiful smile with fuller lips. Patients can look ten years younger!
Although grinding appears to be a disease of the teeth, dentists recognize a contribution of the muscles and nerves. Arguments may be made that grinding starts with a muscle problem, a nerve problem or a tooth position problem. It is not as important for patients to understand the cause as to know that eliminating any one contributing factor can reduce the grinding.
Knowing that skilled dentists can correct this malady is reassuring, but there is a downside. Because many teeth may require crowns, the cost is considerable. Restoring worn teeth can be difficult. In the most severe cases the teeth are so short that newly placed crowns do not easily hold to the short stumps that remain. Newer dental cements usually overcome this issue if treated by mid-stage. At late-stage, the teeth can be worn right down to the gum – a very difficult situation to restore. These patients practically live in the dental office, having crowns re-cemented.
Early recognition and treatment is key to the most successful treatment for grinders. Some of the warning signs were mentioned in the earlier section, but here is a more comprehensive list:
- Squared off edges of the front teeth
- Thinning and chipping of the upper or lower front teeth
- Notches along the gumline where the enamel meets the root
- Pitting (potholes) in the biting surface of the back teeth
- Hard bony growths (also called exostoses) on the on the cheek side of the upper jaw or the tongue or cheek side of the lower jaw – in some individuals, the bone responds to stress by growing more bone mass.
- Your partner complains about your grinding while you sleep
Initial treatment is diagnostic and preventive. Most dentists will provide an occlusal splint (night guard), which is made of hard or soft plastic. This splint fits over either your upper or lower teeth so you grind on the splint instead of your teeth. It opens your jaw to provide a more relaxed position for the muscles and removes dental stimuli that encourage grinding. Another type of appliance (NTI) fits over just a few front teeth and disengages the back teeth to break the stimulus for grinding. Some dentists may prescribe muscle relaxants, especially if you have muscle spasms and pain from your grinding habit.
A second step may be to study your bite to see if your teeth are meshing together properly. Removing small amounts of enamel that hit prematurely can actually reduce the tendency to grind.
Additional steps depend upon your age, the condition of the gums and bone around your teeth and the severity of wear. This may include muscle balance studies, orthodontics and/or reconstruction of your bite with crowns (caps).
The complete restoration of a debilitated bite is very personally rewarding to dentists. It is the most dramatic dentistry that we do. My strong recommendation is to treat your wear problems early and often. You shouldn’t have to have a worn out bite just to have it rejuvenated. Why not keep it youthful all the time!
Warning! Placing a crown on one or two worn down teeth does not treat the problem. A crown placed on a broken tooth will stop wear on that tooth, but will not slow the wear on other teeth. Left unchecked, the wear on those other teeth can necessitate the rebuilding of the bite on all of your top or bottom teeth (or both), including re-crowning of the previously treated tooth. All too often, patients are treated one crown at a time when the mouth should be treated for the disease that affects it as a whole.
Think of the person who wears the heel out of one shoe twice as fast as he wears the heel out of the other shoe. The ideal solution is to replace both heels at the same time, before either gets worn so much as to affect comfort or health.