Why Does Dental Work Sometimes Cause A tooth To Hurt After It Is Done?

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I often meet my patients for the first time because they are seeking relief from a painful tooth. As a matter of fact, hardly a day goes by when I don’t   provide emergency relief to at least one patient.  In most cases, I can induce immediate and lasting comfort. Patients are generally grateful for my services in this scenario. I am not the only dentist that can do this. Most dentists are capable of this feat. It is so common, patients generally expect immediate relief. After 30 years of practice, I am still amazed by the fact that I can do this. I often wonder if any other medical professional disciplines have this expectation. With a sprain, broken bone, an infection etcetera, I don’t believe most individuals seeking treatment expect immediate relief. Sadly, there are many instances when I can’t provide relief and it is frustrating for me and my patients. The reasons vary, but most often prolonged pain is due to inflammation. Inflammation most often comes with infection and injury. Inflammation is just the body’s way of healing. Without inflammation, you can’t have repair, and repairing an injury or infection takes time.

Teeth contain a soft core within them comprised of mainly capillaries, nerve tissue, specialized cells called odontoblasts and odontoclasts, and connective tissue. The inner soft core is called “the pulp”. The nerve tissue in the pulp is extremely delicate. The outer layer of our teeth is called enamel and it has no ability to sense pain because it almost 100% mineral in nature. It protects the underlying tooth structures from feeling very much, just like our outer layer of skin which is devoid of nerves.  Most of the tooth is composed of dentin, which is hard, but contains soft organic structures. The dentin has microtubules that travel into the pulp. The mechanism is poorly understood even to this day, but the tubules can transmit stimulus to the nerve. The catch is that the nerve only contains neurons that sense pain and damage, not pressure, not hot or cold, not touch, just pain. There a two different kinds of nerve fibers in teeth. The first kind are called A fibers and sense acute stimulus and are the most sensitive. These fibers are further classed into A-delta and A-beta fibers. The second set of fibers are called C fibers, and sense only more intense stimulus and heat. Once these nerve fibers are activated, it is a sign of prolonged inflammation, or infection which can foretell the nerve’s potential demise.

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 Most of us have experienced intense shooting pain in our teeth, usually in response to extreme cold foods like ice cream. This is because when the enamel cools too much, the coldness is sensed by the nerve and sends a signal of pain to the brain. Luckily, the pain is usually very brief.  Some unfortunate people have experienced pain from tooth damage via decay or trauma. The reason that damaged teeth are sensitive is that the dentin can become exposed which makes pain transmission to the pulp hundreds of times easier. In most instances, the damaged tooth structure is replaced by a filling or a crown, which are commonly called “restorations”. Once the exposed dentin is covered by the restoration, the pain usually goes away immediately. Think of a bandage over a cut. Once the sensitive underlying skin is covered, most of the pain vanishes due to the exposed nerve endings being covered.

No one expects to have surgery and not have to heal. Minor surgeries like removing a small cyst just under the skin are minimally invasive and only require small superficial incisions and a few stitches. These types of procedures are not expected to cause much postoperative pain and heal within a week or two. More invasive surgeries are expected to cause more postoperative pain and take weeks to months to heal. This is exactly the case when the dentist works on your teeth. The decay is cut out using the drill (dental professionals call it a handpiece). Because the tooth is alive and the dentist is cutting your tooth, you are experiencing surgery whenever the dentist restores your tooth. “Operative dentistry” is the technical term for restoring teeth because just like surgery, we are cutting a living part of the body, so think of it as a mini operation.

If you have a small cavity, it may not even penetrate through the enamel. In this case, you can have the work done without getting numb and expect no postoperative sensitivity. If the damage or decay is into the dentin, you will most likely want to get numb, as the exposed dentin is usually highly sensitive. The removal of tooth structure is injurious just like a surgical incision. Luckily the inflammation that is generated is so minor, no postoperative pain is experienced. The closer to the nerve the dentist must go, more inflammation and postoperative is expected.

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Postoperative pain due to dentistry has varying levels, from minor to severe. The most common symptoms are transient sensitivity to cold and/or biting of varying degrees. These symptoms are due to the A fibers and usually go away after a few days. Constant aching is associated with deeper fillings and wears off slowly over the course of weeks. This type of pain is associated with chronic nerve inflammation and the C fibers. If the symptoms don’t go away, or progress to lingering sensitivity to heat and touching and tapping the teeth, this is a sign that the nerve is not going to recover, and either the nerve needs to be completely removed from the tooth (this is a root canal), or the tooth needs to be removed.

Most often, I can assess the level of decay from radiographs, but not always. When I think a cavity is deeper, I inform the patient that postoperative symptoms may occur. There are a few other factors that can exacerbate symptoms. Grinding, clenching and gum chewing can lead to inflamed nerves. The process of filling a tooth can push to tooth over the threshold of inflammation where pain can ensue. Younger patients have larger nerves; therefore, fillings will naturally be closer to the nerves. Older patients have smaller nerves and can usually tolerate much deeper fillings without consequence and can often skip local anesthesia.  

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If the pain is mild, ignore it. If the pain is a bit more than that, chew on the other side of your mouth. If the pain is beyond that, take an over the counter anti-inflammatory. If that does not help, call the office for a prescription pain reliever. If the symptoms do not respond, or are indicative of permanent nerve damage, further treatment will be needed. Luckily my office offers 24-hour emergency care in such cases.

Often, patients can be frustrated that they were in no pain prior to the dental work and have regret that they ever did anything. There is a flaw to this logic, as untreated tooth decay always leads to pain in the end. When recommending treatment, I am trying to maximize the odds of saving the tooth without complications. This is not always in my power. The progression of recommendations goes something like this: prevention is the first line of action. If the tooth looks like it is progressing towards decay, a sealant is indicated. If there is decay, I will recommend a filling to avoid having to crown the tooth later. We crown a tooth to preserve its integrity and hopefully avoid the dreaded root canal. A root canal is commonly done to avoid removal of the tooth. Put another way; a stitch in time saves nine. I would like to add that sometimes the filling has a flaw and needs to be redone. I know of no dentist who has not placed a filling that has a void or some other flaw that was not seen at the time of placement. This is not generally considered malpractice. Not acknowledging that a better restoration is needed is. Unfortunately, there are many sub-par practiononers out there.

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If you are having tooth pain, it is best not to wait, as timely intervention by a qualified dentist can help you avoid costlier fixes that usually come with poorer prognoses and greater odds of postoperative pain.