What Does Sulcus Mean In Dentistry?

A sulcus is defined as a deep, narrow furrow in tissue or an organ, which in dentistry translates to the space between the tooth and the gum tissue, measuring from the edge of the gum (the gingiva, or gingival crest) to where it attaches to the tooth root (the periodontal ligament). See Figure 4.1.

sulcus mean dentistry

Figure 4.1. The Sulcus with Healthy Teeth and Oral Tissue

That space between the teeth and the gum tissue—the sulcus—is one that few people outside of dentistry give much thought to, but inside the profession, it is very important. As a practicing dentist, I frequently work in the sulci (plural of “sulcus”) and occasionally find myself agonizing over one sulcus. There is even a specialty in dentistry (periodontics) that is primarily concerned with the sulcus, and it is important to monitor what goes on in it because your appearance, your breath, your teeth, your health, even your life itself, can depend on what’s going on in all the sulci in your mouth.

For robust gum health and fresh breath, as well as the control of oral factors affecting systemic health, the battle is under the gums, in the sulci of each and every one of us fortunate enough to have teeth (the dentate). The edentulous (toothless) do not have gum disease since their teeth and associated sulci are gone. However, the edentulous frequently have residual systemic effects from the gum disease that was acquired when they did have teeth. To make this clear to you, let me take you on a tour, a dentist’s view of all kinds of sulci, so you will have a much better understanding of what goes on there and why the care of your sulci by you and your dental healthcare professionals is critical to your health. (In preparation for the tour, you may refer to Figure 4.1 for a blueprint of what a sulcus looks like.)

First, we will suit up with a mask and gloves, then reach for a probe (a sulcus-measuring device), and use a little mirror, mostly to keep things out of the way, such as the tongue and cheeks that hang over the sulci we are going to inspect. In order to get a really good view, I’ll lend you a pair of operating telescopes just like mine. You wear them like glasses, and everything you see will be magnified approximately four times. When we get into the examination room, we’ll plug your fiber-optic cable into your light source and bring it up to its highest intensity. That way, you’ll be able to see everything exceedingly well, without shadows, and with an excellent depth of field. You may also be interested to learn that we will actually be peering down into some sulci and looking around.

But before we start, there are a few dos and don’ts to observe on the tour. Prior to introducing our male patient, I must let you know that you are going to be seeing some things for the very first time while dealing with a live patient who has feelings and sensibilities we must respect, and who may be nervous. You may also notice that our probe releases some very unpleasant odors from the sulci. Our patient will never be uncomfortable, but he may not know this. So, while on tour, please don’t ask any questions. I’ll guide you through what we are seeing as our patient listens because it’s critically important to gently educate him about his condition while I am determining what can be done to improve his health. I may ask you to use your mirror to hold his tongue or cheeks back because, as we are inspecting the depths of his sulci, I will also be using an intraoral TV camera to help our patient see, about twenty times larger than life, what we are all seeing on the TV monitor that will be right in front of him. By the way, if any of this bothers you and you feel the need to leave the room, that’s perfectly understandable. Just be very careful when you get up; Michelle will unplug your fiberoptic cable and remove your telescopes. You don’t even want to know how much this cost, so we don’t want to break anything. Whether you stay or not, we’ll cover any questions you might have later, once the patient has gone. For now, let me give you a little background on the patient while Michelle seats him in Room 4.

Michelle has taken a full series of digital x-rays on our patient, and I have already reviewed them in my office, but we’ll pull them up on the monitor and go over them with the patient after we’ve completed the periodontal examination; you can see them then. It’s easy to demonstrate things on x-rays that are fifteen inches tall, as they will be on the monitor, so you will not have to squint to see the details as you might with little radiographic films. Additionally, thirty minutes ago, my other assistant Tracy gave our patient a measure of protection from the inflammation we will be inducing when we conduct our examination; she gave him three 500 mg chewable vitamin C tablets. This is actually a first-aid recommendation for symptoms of a heart attack; vitamin C is anti-inflammatory and has been shown to dilate blood vessels, so it seems prudent to use it as a preventive measure to help keep inflammation down during our periodontal examination. Michelle has also placed some very effective, eye-protective dark glasses on our patient to shield his eyes from our lights and keep out anything that might otherwise get into his eyes. It’s a comfortable and considerate precaution we always take.

Our virtual patient is a thirty-eight-year-old man named Bif (although a fictitious character, he is representative of what is seen in dental offices frequently enough to be a realistic example for our tour). Bif works six days a week as sales manager for the busiest car dealership in town, a Job that stresses him to the max, he says. His wife made the appointment for him because his front teeth are dirty and he has a continuous problem with bad breath. Except for being fifty pounds overweight and having Joint pains in his hips and knees, Bif claims to have no significant health problems. He does not have a primary care physician and has not had a medical checkup or physical since Joining the Air Force as a teenager. Among other things, this leaves both Bif and me in the dark about several critical indicators of his health or any potentially lethal underlying conditions that would show up in blood and urine tests. Bif says he does not take any prescription drugs, but does smoke two packs of cigarettes a day, and admits to drinking “more alcohol than I should.” His temperature is slightly elevated at 99.0℉, compared to the norm of 98.6℉.

His last dental visit was ten years ago to have a wisdom tooth removed on the upper left, which “didn’t heal right,” he said. His oral healthcare efforts include using a hard toothbrush to brush twice a day sometimes, but usually just once, using a popular tartar-control toothpaste. He also carries an alcohol-based mouthwash with him and uses it about every thirty minutes to mask his bad breath. Bif’s dental complaints consist of having sore teeth once in a while, and his main concern is to have his teeth cleaned and get something done with his breath. His wife has declined his request to Join him in the room, and we are about to begin our tour. Ready?

With all of us in the room, including Blf, we introduce ourselves and briefly review Bif’s concerns about his teeth. We also briefly review his health history, not just to confirm what we already know, but perhaps to uncover other factors that could aid our efforts to improve his health. I also take a few moments to reconfirm that we are going to be gathering some information about his condition today, that it will be painless and that, with his permission, I’d like to describe my findings verbally as I go along (asking permission is critical, and since you’re in the room with us, you’d just be observing if I couldn’t describe things as we go). Bif understands that we will be exploring his sulci with a little measuring instrument marked in millimeters, and recording the numbers on a periodontal chart that can be seen on the monitor. He understands that any readings over 3, or any signs of bleeding, pus, or swelling are not good. He is also aware that healthy teeth should not be loose or covered in tartar, nor should the sulci be covered in plaque. Because of Bif’s health and habit history, we’re going to be particularly attentive in checking for all this, and more.

Bif has relaxed just a little bit, so we are going to begin our sulci (periodontal) assessment by probing first on the upper right, very gently, next to a molar that shows quite a bit of toothbrush abrasion and recession. On the monitor, Bif can see that his tissue color is fairly good (not red and swollen) on the cheek side of his upper right first molar, number three. When we measure it, he can also see that he has 4 mm of root exposed. Then when I gently slide the probe into the sulcus about mid-tooth, I can feel that the root is smooth, with no tartar deposits; my probing depth is only 1 mm (5 mm is recorded since 4 mm recession plus a 1 mm sulcus depth equals 5 mm). Unfortunately, I can also feel into the furcation, the space between the roots of multirooted teeth, which is not a good sign. The good news is, there’s no bleeding and no odor, but the tooth has become moderately mobile due to grinding (bruxism) and loss of supporting bone. Bif doesn’t know it, but his toothbrush is causing gum recession and root damage as he literally grinds the gum down with a toothbrush that is too hard, and his tooth-grinding isn’t helping matters since it overstresses an already weakened tooth.

The second sulcus we are going to explore, right behind the upper right front tooth in tooth number eight, looks very angry. We are going to probe all around the tongue side (the lingual or palatal surface), into the sulcus of this number eight tooth. On the monitor, Bif can see how red and swollen this tissue is. I gently insert the probe straight up under the gum tissue, and keep it right next to the tooth, right into its wide-open sulcus, and find almost no resistance from the very soft tissue. The probe goes past 5 mm under the gum margin, and the root feels very rough and irregular because the tip of the probe is contacting large chunks of subgingival calculus (tartar under the gums). I’m not even at the bottom of the sulcus, yet there’s little or no resistance to the probe and we already have considerable bleeding, with just a little pus. While it is painless, there is profuse bleeding. Michelle applies pressure to the area with gauze to control the bleeding, and we wait. Bif is watching this on the monitor as well. Finally, I measure this sulcus to be 8 mm deep, and we record this, as well as the pus and bleeding. It is evident that Bif packs food into this space, just as he does on all his upper front teeth. His upper front teeth have long since moved forward, so his lower front teeth actually bite on the gum margins right over the sulci, allowing the damaging process to accelerate. With a little finger pressure on this tooth, it moves in and out rather easily, perhaps as much as 1 mm each way.

We’ve checked just two sulci so far (I should explain that sulcus depths can vary from shallow to deep on the same tooth), but it becomes obvious that other measurements around Bif’s front teeth would most likely reveal probing depths of perhaps 3-4 mm on the facial (lip) side, with deeper readings between the teeth and on the tongue side. Bif’s front teeth are very stained from cigarette smoke, and the gum tissue in front of these teeth has a dull, lifeless appearance, most probably due to the toxic effects of his smoking and his constant use of alcoholic mouthwash. (His gum tissue is subjected to a smoke stream about forty times a day—two packs—and it never has a chance to completely rid itself of the residual surface toxins adhering to it.) Alcohol, especially the 40- to 60-proof mouthwashes commonly available, exert damage to soft tissue in direct proportion to the strength of the mouthwash and the time it is in contact with oral tissues. So the twenty-plus times per day that Bif swishes with his mouthwash could be a total of ten or fifteen minutes of contact daily. This is obviously not conducive to improving his gum tissue health, although it does mask his mouth odor with an even stronger odor.

Bif’s examination has barely begun, and it is already apparent that his mouth and his overall health are in serious trouble. Let’s check tooth number fifteen, Bif’s upper left second molar. As we observe the gum tissue covering the bone on the cheek side of this tooth, which extends toward the front of his mouth about halfway over the root of the tooth in front of number fifteen, we can see a glistening bump about half the size of a small grape (this area would usually be hard and smooth, and any pressure here would be comfortable for the patient). The shiny distended tissue feels just like a small water balloon, and too much pressure would be painful, so we’re gentle in our examination of this pus-filled mass.

We are most likely observing either an abscess created by Bif’s gum disease and bone loss or an infection resulting from a dead nerve in one or both of the upper left molars. Either way, I am not going to probe in an area of acute infection, as it is too dangerous for the patient. Remember that acute infection can elevate normal clot-inducing C-reactive-protein levels a thousandfold, and probing could further increase CRP levels, as well as spread infection; so when I see a situation similar to the one affecting Bif on the upper left, it generally means look but don’t touch. The x-ray of this periapical area (around the root tips), shows virtually no bone around the root of tooth number fifteen, and this bone loss extends back to one of the roots of the three-rooted molar, number fourteen, which also has no bone around it. Gentle finger pressure on number fifteen shows it to be very mobile, confirming the lack of bone support, which the x-ray revealed. Number fifteen is depressible as well, going down when pushed, and back up when the pressure is released. Bif is in serious trouble, and we’ve only screened a few of the upper sulci for signs of disease. While it should be obvious that tooth number fifteen can’t be saved, my sense is that he has more serious health considerations to pay attention to.

We put Bif in a more upright position to facilitate our examination of his teeth and gums on the lower arch, and proceed to slide our probe through the thick layer of plaque obscuring the sulcus on the cheek side (buccal surface) of number nineteen, a lower left first (six-year) molar. This molar is two-rooted, one in front and one in the back that are of approximately equal length. When a tooth has two or more roots, the space between the roots where they Join the tooth is called “furcation.” In a periodontally healthy state, the bone will normally cover all of the roots as well as completely fill the space between them. But in Bif’s case, the probe goes clear into, and under, the furcation and clear through to the tongue side of the tooth. The probe also created an escape route for approximately ½cc of very odorous pus. Since it’s raining anyway, I put a little finger pressure over the area in an attempt to get out gently as much pus as possible while I’m examining this area, which should make it feel better for Bif.

While Bif has a through-and-through “furcation involvement,” the periapical x-ray of the area shows that at least three-quarters of each root is covered in bone. Bif needs some good news; while not great, the prognosis for the lower left teeth and the possibility of achieving healthy sulci is certainly better than for the upper left, where extraction of number fifteen is the only option. Probing a diseased sulcus such as this one reveals a wide space that’s spongy or “boggy” as it is sometimes described. (As a reminder, healthy sulci are firm, shallow, and tight, and there’s no bleeding when probed.)

The lower front teeth will be examined next and, since gum disease and the recession has exposed at least 4—5 mm of the roots of his four lower front teeth, considerable supporting bone has been lost. The two middle teeth are very mobile, but those adjacent to them are slightly firmer. A gentle probing of the sulcus in the front and middle of number twenty-five, the lower right central incisor, reveals a reading of 4 mm, and I am not forcing the probe to go deeper. The left central, number twenty-four, probes similarly. Both teeth reveal slow but definite bleeding. The gum tissue in front of these teeth is dull in appearance. While the gum tissue at the sulcus is not dull, it is slightly pulled away from the teeth, and there appears to be a bluish-greenish color down in the sulcus, next to the tooth.

Any attempt to probe either sulcus on the tongue side of these lower front teeth would be impossible. Bif has such extensive brownish black tartar (calculus) deposits on the tongue side of all six of his lower front teeth that the gums are literally covered up, with no sulci visible (dentists call this a calculus bridge). A review of the periapical x-ray of the lower anterior region shows a very large semicircle of bone loss involving the lower six front teeth, with the root tips (apices) of the two middle ones appearing to sit on top of the bone. There is no bone holding these two teeth in, only gum tissue, and the hard deposits encasing them on the tongue side are probably all that has kept these teeth from falling out. The bone loss and hard-deposit pattern seen here is consistent with what is frequently observed in smokers. Tobacco smoke is very toxic to gum tissue, and Bif will be strongly counseled concerning this habit when we discuss his treatment and home-care programs. Whether my patients want to stop tobacco habits or not, I’m with them all the way, but it is a great feeling to be able to help someone successfully kick the tobacco habit.

The last sulci we’re going to evaluate by probing are on the lower right. Normally, I would check the two bicuspids (numbers twenty-eight and twenty-nine), but they are missing, and apparently have been for quite some time. The gum tissue over the ridge, all that remains in this toothless area, is atrophied and thin, except directly in the front of the next tooth back, the lower right first molar (number thirty). With both bicuspids gone, all three molars in this quadrant have been allowed to tip toward the front of the mouth, resembling the slanted brick patterns I’ve seen outlining flowerbeds and sidewalks; they are at about a thirty-degree angle off vertical. This mesial tipping has pushed Bif’s gum tissue up the front of the first molar, creating a rounded gum margin at the sulcus, which is under the overhanging tooth and covered in plaque and debris. Feeling our way into the sulcus with the probe reveals a 9 mm probing depth with considerable bleeding and a little pus, as well as rough, hard deposits on the root.

Lower molars almost always have two root canals in the front root, one on the tongue side, and the other on the cheek side. With this tooth, number thirty, it’s easy to detect that the groove on the front of the root is quite deep. (Cut in half horizontally, the root would have the same shape as the number eight.) Probing at the furcation on the cheek side of number thirty reveals a distinct furcation involvement since the probe goes all the way to where the roots divide, but it is not a through-and-through situation as it was on the other side. There is, not surprisingly, bleeding at this site as well. This is recorded, and the probing depth of 6 mm is noted as well.

While Bif’s gum-health exam isn’t over quite yet—we still need to let him know he was a really great patient and arrange to see him soon to discuss our findings and recommendations—I want to make sure you’re doing all right at this point. I don’t want to assume that you understand just how seriously ill this gentleman is, nor do I want you to get the impression that all we need to be concerned about is getting his mouth cleaned up and his oral home care tuned up, like getting him to brush better and floss effectively. While Bif is purely a fictitious character made up for demonstration purposes, his health history and his serious periodontal disease depict a distressingly common situation that presents quite a number of problems.

It is apparent that Bif is very much at risk for cardiovascular disease, at a minimum. He obviously has the severe periodontal disease, in addition to other factors that predispose him to cardiovascular disease—including his two-pack-a-day smoking habit, his being fifty pounds overweight, his high-stress, six-day-a-week Job, and his age.

After learning what you have about the correlation between mouth disease and systemic disease, then taking this tour, does periodontal disease look like it’s a problem that affects only the mouth? Or is it now appears that with perhaps twenty-five teeth exposed to as many as 400 different types of oral microorganisms, there’s every chance Bif has a serious systemic infection that can possibly threaten several organ systems in his body, and even cause death? If you can see that a seriously diseased mouth is potentially affecting the whole body—the brain, heart, joints, lungs, and more—then you’re beginning to see why I am so concerned about this serious health issue.

One recently published study in the Journal of Periodontology (September 2001) clearly established that periodontal infections contribute to elevated systemic CRP levels. In this study, elevated levels of CRP were evident in patients with infection from subgingival periodontal pathogens (microorganisms that can cause disease), while elevated CRP was not a significant factor in the healthy controls. The study noted not only the positive correlation between periodontal disease and elevated CRP levels but also considered that periodontal disease was a possible underlying pathway between periodontal disease and the observed higher risk for cardiovascular disease in these patients.

In another, even more, recent study, the participants had blood tests done before and after chewing gum lightly, fifty times on each side, to determine if just chewing gum could elevate circulating levels of proinflammatory components such as endotoxins (toxins of internal origin—harmful bacteria, for example—found in microorganisms). Blood tests were done on the test subjects before and after chewing gum. In those with periodontal disease, such as Bif had, it was found that the blood levels of endotoxins were significantly higher in those after chewing gum than they were before. Before chewing, these levels showed an incidence of positive endotoxemia to be 6 percent, while after chewing gum it rose to 24 percent. The conclusion was that “gentle mastication is able to induce the release of bacterial endotoxins from oral origin into the bloodstream, especially when patients have the severe periodontal disease. This finding suggests that a diseased periodontium can be a major and underestimated source of chronic or even permanent release of bacterial pro-inflammatory components into the bloodstream.”

The real challenge here is that patients like Bif do have an extremely serious, even life-threatening, illness, but they have the perception that it’s just bleeding gums or something on a par with having a cold. From our tour, it is obvious that Bif has the severe periodontal disease; it is exceedingly likely that he has highly elevated CRP levels, positive endotoxemia; and as suggested by the two studies mentioned above, he is in a category that puts him at a greater risk for cardiovascular disease. Bif is in trouble, and his situation is, unfortunately, seen in a distressingly high percentage of adult patients.

Everything considered, even if the Bif’s out there go ahead and have treatment, such as scaling and root planning, or required surgical procedures, once their treatment is completed, they assume they are cured. Since we’ve already talked about gum disease being a systemic infection and not just a problem that is somehow compartmentalized in the mouth, it is imperative for dentists and patients alike to begin viewing this disease as the serious infection it is. We must also begin taking a serious look at different methods, materials, and techniques that are used effectively to combat what is essentially an inflammatory, infectious process. The relatively recent proliferation of studies and articles about the periodontal-systemic disease connection appearing in our professional Journals gives me hope that this serious health issue is finally going to become recognized for what it is. And from that, I’m hopeful that much more will be forthcoming about what patients need to do to become far healthier.

In the meantime, there are still a considerable number of problems that must be examined, and changed, before any meaningful improvement in the periodontal-systemic disease situation can be addressed by the public and the dental profession. Ironically, it was physicians, not dentists, who originally initiated my research into CRP, and it is physicians and other non-dental health professionals who have authored a number of books with chapters on periodontal disease, outlining safe, effective methods to combat this serious situation. Why then are so many dentists and physicians dragging their feet about this critical health issue? Maybe they will begin to Jump on the bandwagon now that CRP is in the news as a major cause of heart attacks and strokes, as well as other serious health issues; now that there are articles about how its reduction and control figure so prominently in maintaining a strong, healthy mouth and better overall health. That dentistry has begun to scrutinize this situation more intensely bodes well, but so far, dentistry and oral care haven’t resulted in robust oral health or robust systemic health. If you just look at the incidence of periodontal disease, heart attacks, and strokes, you get a sense of the magnitude of this public health failure. We are losing the war and we need to look elsewhere. Fortunately, much of what we need for better results are already known and available, and is presented here for your consideration and potential benefit, should you decide you need or want to make changes in your own health program.

What about the dental procedures Bif needs to have done in the office? We’re going to leave that alone because the focus of this blog is on what he (or you) needs to do for himself, not what a dentist needs to do for him once there is a problem. But my experience tells me that, without taking advantage of any of the information in this blog, Bif has an extraordinarily grim prognosis. Do you think he’ll make the changes necessary to live a lot longer? Let’s recommend that he see a knowledgeable physician for a complete history and physical, all necessary lab tests, including a high-sensitivity CRP analysis. Then we’ll be better able to help Bif address his serious health issues. He’s at a fork in the road. Dead ahead lies continued illness, or he can make a turn toward a much healthier life. Hopefully, we have given him the information he needs to make a good decision. You were there with us, and I certainly hope you enjoyed the tour.