March 2008, Volume 4, Issue 3
Published by AEGIS Communications
Pounding on the Occlusion Pulpit—Where in Lies All the Controversy?
Allison M. DiMatteo, BA, MPS
If clinicians are seeking out information about occlusion, they may find themselves confused. What’s more, when discussing the topic of occlusion among colleagues—even friends—they may become conflicted. In some circles, professing one’s technique for maintaining or re-establishing occlusal health is tantamount to defending one’s religion; things can get a little heated. Throughout the profession, the topic of occlusion has become quite controversial.
“I think most people view controversy to point out where other people may be wrong. My view is to point out why they may be correct,” says John Kois, DMD, MSD, founder and director of the Kois Center in Seattle, Washington. “The idea that we do have controversy makes us realize that we really do not have solid evidence-based science to help us make decisions.”
There are no double-blind studies that prove or disprove any of the occlusion theories, including those that were practiced 70 years ago, notes Sam Kherani, DDS, a clinical director at the Las Vegas Institute for Advanced Dental Studies. In the absence of double-blind studies, what happens is that when one technique works in the hands of certain people, they believe that is the ideal way to treat occlusion, whereas there may be another technique that works well in the hands of other individuals, he says.
Interestingly, the literature is replete with assertions that a stable occlusion is a prerequisite for durable dentistry—whether purely restorative or cosmetic in nature. A patient’s occlusal scheme has the potential to impact not only the longevity of the restorations that are placed, but also the long-term health of the patient’s oral environment when function and soft tissue factors are taken into consideration. Yet, according to an editorial in Angle Orthodontist, although a statement like “ideal occlusion is the primary basis of a healthy stomatognathic system” may sound like a bona fide scientific hypothesis, it’s rather vague and ambiguous.1 In fact, it is “so vague and imprecise that no substantial scientific evidence for or against this hypothesis has been produced since the days of Bonwill and Angle.”1
“Part of the confusion in dentists’ minds comes from a lack of solid research on occlusion. No matter which occlusion philosophy you look at—whether it’s centric relation or neuromuscular—the body of research is anecdotal and circumstantial,” explains Steve Ratcliff, DDS, chairman of the department of education of the Pankey Institute. “We have lots of studies about pieces and parts of occlusal theories; we don’t have sound studies that tie all those pieces together in a manner that says this ‘theory’ is right. We can’t do the kind of research in this country that’s needed to study occlusion because it involves doing it on live people, and it may involve allowing pathologic conditions to continue in the mouth without intervention. It also involves sophisticated instrumentation that is invasive. I think in large part that leads to people hanging on to their own occlusion theories because there is nothing out there to say whether it’s right or wrong.”
Ed McLaren, DDS, director of the UCLA Center for Esthetic Dentistry, offered a definition of occlusion in dentistry as force management; when managing occlusion, dentists are examining what overload of force would cause the breakdown of the system and then trying to prevent that. “Clinicians are trying to design the way the teeth come together so that we prevent some sort of breakdown, whether it’s of the teeth, the periodontium, the joints, etc,” McLaren says. “That’s really our goal in all of this.”
To accomplish that goal there are five or six philosophies or guiding thoughts regarding occlusion that may be taught in private institutes and/or dental schools across the country. It is beyond the scope of this article to clarify or outline the particulars of each philosophy, or to extol the virtues or vices of any of them. These are theories that focus on occlusion from the following perspectives2:
1. Musculoskeletal/centric relation (a muscle-braced position)
2. Most posterior retruded position (a ligamentous-braced position)
3. Anterior protrusive position (a muscle-braced position)
4. Neuromuscular position (a gravity-assisted position)
5. Intercuspal position (a tooth contact-determined position)
6. The 4/7 Radiographic Position (a radiographic-determined position)
Two points of similarity among different occlusion philosophies are that the teeth should fit evenly, with no one tooth hitting higher than another, and that the anterior teeth should take over and the posterior teeth should disclude when moving laterally, explains Glenn DuPont, DDS, an instructor at the Dawson Center for Advanced Dental Study. The one point that seems to be the most misunderstood or controversial is the treatment position of the jaw or the temporomandibular joint, he says.
“I think one of the problems with occlusion as an entity, as a topic, is that it developed historically in different parts of the country with very different beliefs about how it should be done and how occlusion education was conducted,” notes Frank Spear, DDS, MSD, director and founder of the Seattle Institute for Advanced Dental Education. “What people didn’t realize is that, in fact, each of the different disciplines and how they were doing occlusion was having a high level of success. What’s strange is that nobody seems to be taking into account that almost all of these different philosophies have far more successes than they have failures.”
When you look at the various “philosophies” of occlusion and the controversies that exist, Michael R. Sesemann, DDS, vice president and accredited fellow of the American Academy of Cosmetic Dentistry, suggests separating the science from the human interaction that causes the controversy. “The controversies arise when the student becomes the teacher and is subjected to the insidious effects of the ‘paradigm effect.’ In other words, once we hu-man beings find a comfortable paradigm for our own occlusal philosophy, we tend to subconsciously filter any further information in a selective manner,” Sesemann has observed. “We accentuate the information that reinforces our own paradigm and conversely, we tend to minimize or ignore information that challenges our beliefs. This sets up an environment of defensive posturing that creates the ‘controversies’.”
This month, Inside Dentistry examines what all the “pulpit pounding” is about when it comes to occlusion techniques and explores the similarities among the different theories. Regardless of which philosophy you ultimately subscribe to, advanced education and training will be key to skillfully applying it your cases. And attention to occlusion is adamantly warranted, our experts say, in this day and age of esthetic and elective dentistry. Further, the recommendation is offered to embrace a more universal appreciation for the individuality that unique patients’ occlusal schemes represent. Therein lies the reason to perhaps explore different occlusal treatment possibilities when necessary.
In The Beginning
Dental occlusion was first developed to address the needs of the fully edentulous denture patient. According to Noshir Mehta, DMS, MS, MDS, chairman, General Dentistry, and director of the Craniofacial Pain Center at Tufts University School of Dental Medicine, the concept of occlusion has developed over time through trial and error, mostly by departmental systems. Prosthodontists, orthodontists, gnathologists, and periodontists have had their own versions of occlusion. The unfortunate fact, he says, is that biologically there is only one format of the patient’s occlusion.
In order to construct teeth for people who didn’t have any, the only way to get the upper and lower jaws to coincide at any one point was to base the relationship on the temporomandibular joints, using them as a hinge and then building teeth to meet together, Mehta explains. However, that did not take into account biologic function; it only accounted for mechanical function.
“All the concepts of dental occlusion started with mechanics by people who were more interested in the mechanical aspects of teeth coming together, rather than the functional aspects, so our articulators today are still mechanically inclined,” Mehta says. “They are not biologically inclined because we haven’t developed a biologic solution to how upper and lower teeth fit together.”
Controversy & Commonalites Commenced
There are many underlying themes that relate to the various theories of occlusion, Kois explains, and they can be divided into three categories. First, the idea of where the jaw joint should be has undergone significant controversy. The second biggest area of controversy involves exactly how to establish the anterior guidance in the system (ie, how steep or how flat). Finally, many theories have attempted to devise a formula in order to develop occlusal relationships, but Kois doesn’t believe a formula can be applied to every individual.
“Our faces are different. Our muscle sizes are different. The craniofacial morphology is different,” Kois emphasizes. “Different ways of establishing occlusion may be successful in one individual and not in another; therefore, a universal formula or ‘cookbook’ is silly.”
Mehta looks historically at the differences and controversies. Arguments have arisen over whether patients should be built at centric relation or centric occlusion, and whether or not patients chew in centric relation or centric occlusion. There are schools of thought emphasizing the use of muscles to build the occlusion (ie, neuromuscular theories) and those that emphasize centric relation, he explains, noting that issues with centric relation date back to early days of building denture cases.
“I think what all of the different philosophies are trying to do is to create an occlusal result that has the lowest risk of future failure for the patient, because when occlusion is not working, it has the potential to affect the temporomandibular joint, create muscle pain, cause injury to the teeth, etc,” Spear says. “What people can’t agree on is how to best do that, and they’ll argue a lot about vertical dimension or anterior guidance.”
Sesemann says there are a number of commonalities that exist between his own personal occlusion philosophy and the various philosophies that are put forth. To create equilibrium of the masticatory system, there are objectives he wishes to achieve that are fairly common and universal, regardless of philosophy. These include:
Occlusal contacts on the posterior teeth (including cuspids) that are bilateral, simultaneous, and of equal intensity in their perpendicular vector of force; and
An anterior guidance system that provides neuromuscular release of the elevator muscles and disclusion of the posterior teeth upon lateral and anterior mandibular movement.
DuPont says that understanding occlusion is only one component of understanding the masticatory system. He approaches occlusion using an anatomically sound and physiologically harmonious position of the joints, as well as understanding how the muscles, periodontium, and teeth factor into the system.
Kherani, a proponent of the neuromuscular school of thought, says the difference among occlusion theories lies in where the bite is finalized for the patient. The neuromuscular philosophy, he says, considers the ideal point or area in space where the occlusion should be built to be where the muscles are most relaxed, whereas some other occlusion philosophies determine that area where the bite is created to be dependent on the seating of the condyle.
“Also of paramount importance in the neuromuscular philosophy of occlusion is the objective measurement of muscle activity and the position of the jaw in space,” Kherani elaborates. “As Bernard Jankelson, the founder of the neuromuscular philosophy said, ‘If it is measured, it is a fact; if it is not, it is just an opinion.’”
A theory that Mehta considers is a concept called the occlusal fence theory, whereby the upper teeth are the fence and, if it’s wide enough, the lower teeth will have sufficient room. If the upper arch isn’t wide enough, then the lower teeth become crowded, and when they cannot crowd anymore, then the lower jaw must shift to close.
“Basically the idea is that occlusion is no longer just a centric relation, centric occlusion position that is one-dimensional,” Mehta suggests. “Rather, occlusion has to do with three dimensions: how the lower jaw comes forward and back; how the lower jaw can settle naturally within the confines of the upper arch without shifting; and how one side and the other can function together so that the vertical heights of both are relatively even to support the temporomandibular joints.”
What’s Normal, What’s Not
Historically, normal occlusion is what dentistry calls class I occlusion based on Angle’s classification. However, most of our interviewees agree that if in an individual person the occlusion is functioning without pain, then really for that individual, his or her occlusion is normal. If it isn’t functioning, then even class I occlusion isn’t normal for that individual.
Mehta briefly and basically describes the three Angle’s classifications of occlusion, any one of which may be normal for an individual, yet all three may be considered abnormal for somebody else.
Class I: upper and lower teeth are fitting nicely and evenly (eg, considered normal)
Class II: the (Div2) lower jaw is retruded and over-closed (Div1) or it is anteriorly open (Div1)
Class III: the lower jaw extends outside of the upper jaw (eg, lower teeth in front of the upper teeth in a crossbite relationship)
However, McLaren points out that there are many patients who present with so many varying forms of occlusion or contacting of teeth that occur naturally and survive and function well. Conversely, a varied number of other patients will present with breakdown from different styles of occlusion.
“I think it’s one of those things that just applies directly back to the variation in human nature,” McLaren says. “It’s very difficult to say that one occlusion is perfectly correct for all individuals, and I don’t think we’ve identified an ideal occlusion for a specific person.”
For example, just because a patient’s occlusion can be considered “correct” doesn’t mean that he or she will be pain-free, or that if the occlusion isn’t correct that he or she will have pain, emphasizes Kherani. The human body can adapt to so much that the absence of pain does not mean that there is an absence of occlusal problems, he says.
“This adds to the controversy,” Kherani says, “because at the end of the day, as long as the patient is comfortable, one would say that we’re successful in whatever we’re doing.”
Maurice Salama, DMD, views occlusion in two ways: an occlusion that is physiological (ie, balanced) and an occlusion that is pathological (ie, symptomatic). In a physiological occlusion, he explains, the patient is functioning and not in pain; the joints are functioning without any remodel of the bone; and the disks are not involved. Pathological occlusions, on the other hand, lead to such symptoms and conditions as discomfort, an inability to chew, temporomandibular disorder, headaches, and chronic pain syndrome, among others.
“Many physiological occlusions are not by definition ideal occlusal schemes if we look at them orthodontically,” Salama admits. “They may not be class I. The midlines may not be coincident with one an-other. They may not have perfect function in occlusal movements.”
However, for that particular individual, symptoms do not appear. If they are absent of symptoms and the patient has adapted to his or her occlusion—what Salama calls “adaptable occlusion”—then the occlusal scheme can in fact be physiological.
It’s understandable that clinicians would be confused when trying to determine for themselves which occlusion theory to practice in a profession that has been traditionally dogmatic. Kois says that the reason is partially because the different concepts of occlusion are so varied, with varying degrees of success.
McLaren estimates that any one of the occlusion philosophies could probably be applied to 80% or 90% of patients and because of human adaptability, they’d probably adapt and function with it. The problem—or confusion and controversy—arises when the 10% or 20% of patients don’t fall into a specific category.
“I believe the key is proper diagnosis first,” Kois says. “Once we have all the diagnosis, then the concept of occlusion that fits the diagnosis would be the most appropriate. When the treatment is consistent with a proper diagnosis, the success rate goes up.”
Contributing to the occlusion confusion is the basis on which dentistry has attempted to create its understanding. Kois suggests that in addition to the confusion, dentists’ ability to apply their understanding clinically is not easy to implement. He alludes to articulating paper, shim stock, and also to digital palpation, as crude, which is why the profession is moving more toward electronic instrumentation. “Today, there are more refined metrics to guide our evaluation and enable us to establish a better relationship between the teeth which is less hit or miss,” he says.
However, Spear notes that it’s very hard in four years of dental school to teach people how to properly diagnose and treatment plan occlusion because it’s not a procedure. Rather, he says, “it’s learning the art of determining the condition of the temporomandibular joint, the condition of the muscles, and learning the finer points of tooth wear, mobility or fractures, as well as how to evaluate those areas to decide if the occlusion should be changed or not.”
According to Ratcliff, while dentists may wish that there were an easy, five-step process to follow to figure out an individual’s bite and the way it functions and looks best, no matter what occlusion philosophy clinicians choose to follow, they still have to figure it out one patient at a time. Therefore, he suggests there are two components to determining occlusion: a technical piece that focuses on what is actually taking place in the mouth (eg, well-organized occlusion that is comfortable, attractive, stress-free) and a behavioral piece (eg, the patient’s circumstances and what he or she does with their teeth).
Salama suggests that what may happen to clinicians is that they’ve been trained to look at tooth/jaw position, which may in fact fool them when trying to properly diagnose and address the patient’s condition. “You could be looking at an ideal occlusal scheme, with the tooth and jaw position within the range of normal, but the patient still exhibiting symptoms displaying a pathological occlusion. Yet, the practitioner may think that everything’s ok,” he says. “On the other hand, a patient can come in and look like they have an occlusion that is pathological and not ideal, but he or she may function quite normally, with no history of symptoms, be they periodontal disease, jaw pain, headaches, etc.”
Occlusion: It Does Matter
Kois says that most of what practitioners do in practice is typically conformative occlusion or managing the occlusion (ie, keeping the occlusion relatively the same as when the patient presented). It is not easy to assess that the occlusion may be subtly breaking down, he says. However, more than ever before—at a time when clinicians have the ability to change so many things about the way a patient looks through esthetics—restorative dentistry may necessitate significant changes in occlusion (eg, opening the vertical, orthodontics, orthognathic surgery).
“As dentists get involved in more comprehensive or interdisciplinary treatment plans, the knowledge of occlusion that is necessary to manage those cases is much more significant,” Kois says. “With the advent of adhesive technology—especially for veneers and bonded onlays that have a much shorter turnaround time—the concept of working out occlusion in provisionals is no longer applicable, so a whole different approach to occlusion is required compared to what’s been done before.”
When restorations are needed for esthetic or reparative reasons and the occlusal relationship that the patient walked in with is going to change, it becomes essential for clinicians to remain absolutely cognizant of how those teeth will come together, McLaren emphasizes. They have to truly engineer how those teeth will function and ensure that the stresses on the teeth are on the long axis as much as possible, he says.
“We want to keep our restorative material under as much compression as possible and minimize tensile and sheer stresses,” McLaren explains. “Ceramics and even composites do not do well with a lot of sheer and tensile stresses.”
Kherani recalls that it wasn’t that long ago that few people were getting involved in occlusion at the advanced level that they are today, instead leaving it mainly to specialists. There wasn’t much of a need to really get involved in occlusion, he says, because metal-based dentistry was being placed everywhere.
“When you start relying on porcelain and bonding, you need to understand what the forces are that are at play, because metal is not going to bail you out,” Kherani cautions.
If occlusion isn’t considered appropriately during treatment planning or corrected properly, the consequences range from the catastrophic and costly to the painful and persistent. There are incisal edge fractures and porcelain fractures; cement fatigue and washout of the bonding agents, which could lead to recurrent decay. Entire restorations could break off at the gumline. The patient could develop other symptoms that are joint-related, muscle-related, or tooth-related. These could include:
Temporomandibular joint disorder
McLaren notes that although today’s materials are better than they used to be, they’re still ceramic and they’re still brittle. While the cores might be stronger, the porcelains can still chip, break, and abrade the opposing dentition. If clinicians have not thoroughly thought about or taken into account the occlusion, function, and possible parafunction, the potential for early failure of their restorative dentistry could be high.
“We have to address dental occlusion as more than just the teeth,” Mehta emphasizes. “Historically, to dentists, the definition of dental occlusion is the upper and lower teeth coming together. Now we know that much more is involved—including the brain, nerves, the muscles, the joints, the periodontal structures. Occlusion can affect chewing function, affects head and neck function, and it affects the human being as a whole, too, because a poor occlusion can also affect their quality of life and their psyche.”
Sesemann explains that if a dentist is practicing single-tooth dentistry, providing all of their dentistry conformatively into existing occlusal schemes, failures may be low in number. However, if they’re trying to help the patients in their practice that have complex restorative needs, even if it is quadrant dentistry, they should spend a significant amount of time in the study of the masticatory system.
“There’s just no way around it,” Sesemann emphasizes. “To not do so invites trouble and stress into the daily life of the practice and potentially places your patient’s oral health in jeopardy.”
Universally speaking, Salama notes that how clinicians categorize the occlusion they’re observing can really lead them toward different therapeutic options, but that all too often they may be overly dedicated to one school of thought and, as a result, treat something that doesn’t need to be treated. Or, they could treat something in a way that they were taught, rather than the best option for that particular individual.
When it comes to occlusion, McLaren encourages dentists to think about what the patient needs versus applying a specific technique to every patient. He recommends looking at the specific case and then choosing the technique or occlusion philosophy that will best suit that clinical situation.
When restorations are needed, John C. Cranham, DDS, reminds clinicians to adopt a complete-care approach that includes protocol to address all functional and esthetic parameters. “The great thing about dentistry today is that we have wonderful materials and techniques to change smiles and change lives,” Cranham explains. “Unless we’re building these restorations on functional parameters that work, often we can create bigger issues for the patient.”
Further, when it comes to any treatment, Spear notes that the most appropriate treatment is always the least amount that accomplishes what’s needed. “What I think people don’t realize is that there are certain philosophies of occlusion that may be successful, but they also may dictate that a tremendous amount of restorative dentistry needs to be done to create their occlusal scheme,” he cautions. “No restoration we do is ever as good as if the tooth didn’t need to be restored.”
Who’s Teaching What & Where
Most dental schools do teach occlusion. However, with the limited time faculty have to teach it, coupled with the amount of material they’ve got to present during dental school, an almost four-year, intensive program on occlusion after graduation is necessary, explains Gerard Kugel, DMD, MS, PhD.
“It’s hard for dentists today to accept that there could be multiple right ways of addressing occlusion because that’s not part of our educational process. Our educational process is very dogmatic and very dictatorial: this is the right way to do occlusion and this is the wrong way to do it,” observes Frank Spear, DDS, MSD. “So, what’s contributed to so much confusion is that dentists were taught that their particular idea or educational belief is the right way to do occlusion.”
What postdoctoral education can and does accomplish, Spear says, is create a much more refined skill set for evaluation, diagnosis, and treatment planning of occlusion. He believes there is a significant need among young dentists for postdoctoral education in topics such as occlusion.
“I think we get classes on occlusion in dental school, but I’m not sure we’re ready to hear it yet,” recalls John C. Cranham, DDS. “If we come out of dental school with an understanding of how to do restorative dentistry and put teeth right back where they were to begin with—and to do one, two, or three teeth at a time—that’s pretty much it for what we’ve covered in dental school.”
Kugel suggests that today’s dental institutes and private learning facilities may have an advantage over dental schools when it comes to teaching a technique for developing occlusion: they’re teaching individuals who have some training and experience. During dental school, the complicated concept of occlusion—although not incomprehensible—is difficult for inexperienced students to fathom. They haven’t seen the problems; they haven’t witnessed the variety of clinical cases and symptoms of occlusal discrepancies. But because the concept of occlusion is so complicated, it is far easier to grasp and emphasize one approach—as may be taught at a given institute—than to practice and acknowledge that more than one technique may have validity and relevance.
“Some schools are doing better jobs than others at teaching occlusion, so I don’t want to suggest otherwise,” says Kugel. “However, the way the dental curriculums are set up, it’s tough to be able to teach occlusion in dental schools today.”
After all, the science is changing considerably, suggests John Kois, DMD, MSD, and the information on the topic is growing very rapidly. Yet for some reason, he says, many people may even believe that the concepts of occlusion haven’t really changed. What’s more, the content of the occlusion coursework may be biased by the individual person who has assumed the role of teaching occlusion for the dental school. That person’s background or experience may limit what can be taught at the dental school, Kois says. Further, the time allotted for allowing students to understand occlusion doesn’t even come close to what’s necessary for understanding what is important when out in actual practice, he adds.
“Once we’ve graduated and we start doing more complicated dentistry, that’s when we start to realize that we have a void in occlusion skills, and that’s when we start seeking out mentors and teachers in this area,” Cranham says. “We just have to put the same amount of effort into the study of occlusion as we do learning about cosmetic dentistry and its related procedures and materials.”
Noshir Mehta, DMS, MS, MDS, says that dental students or attendees at private institutes are being taught whatever concepts the most influential person at that institution believes. For the most part, most schools teach complete reconstructions in centric relation because, at the moment, there is no other way of building teeth other than using articulators. Although articulators are still mechanical monsters and do not take into account the ability of a person to have biologic function, they do serve the purpose of facilitating reconstructions, he says. Different locations may advocate a neuromuscular approach whereby the muscles are relaxed, the jaw is placed into position, and then the teeth are built to that jaw position, Mehta explains.
Considerations for When & How to Address Occlusion During Case Management
In today’s practice, less is more, and clinicians are striving to perform the least amount of dentistry to satisfy the restorative and esthetic goals that they and their patients have. But subscribing to this principle may mean basing the approach to occlusion on the individual, not the philosophy, suggests Ed McLaren, DDS.
Glenn DuPont, DDS, advocates examining the occlusion—the dentition—at the initial examination, along with the whole system: periodontium, temporomandibular joint, occlusion, etc. If there is wear, there is a reason. If teeth are breaking or there is a history of breakage, root canals, or tooth sensitivity, there are causes for those conditions, and he emphasizes a need to look for the causes of the signs and symptoms of problems. Then, if necessary, correcting the stability of the temporomandibular joint is addressed very early in the sequence of a case, he says.
“The way the teeth hit affects the other teeth, the periodontium, and the muscles and joints, so my goal is stability and predictability and managing the occlusion early in the timing of the case,” DuPont says of his approach.
To be comprehensive, Steve Ratcliff, DDS, examines the entire stomatognathic system from the very beginning, because how the teeth meet and rub together is very important. If patients spend very little time with their teeth rubbing together other than when they’re chewing, occlusion may not be a hugely important variable in what they do with their teeth. On the other hand, if patients do spend time rubbing their teeth together and the entire stomatognathic and occlusal part of the system isn’t attended to, the clinician could see a failed case, broken teeth, non-carious lesions, and breakdown of the condyle-disk assembly, among other sequelae, he explains.
If a new occlusion is to be created, chances are the goals are to control the load applied to the temporomandibular joints; control the load applied to the teeth and periodontium; and provide muscle comfort and function—according to Frank Spear, DDS, MSD. The occlusal therapy provided by the clinician in order to realize those objectives changes how, when, and where the teeth contact each other.
“Obviously there is a huge appearance or esthetic aspect of what we do today, and esthetics, function, and biology must all integrate successfully in our treatments,” McLaren explains. “Determining the least invasive way to treat the patient ivolves looking at the signs and symptoms of overload and breakdown. Then, start with the completely reversible approaches to resolve the problems first. Do the least invasive treatment to get people through the most acute periods of time.”
Ratcliff says that when it’s time to intervene occlusally for a patient, he believes the best place to start is from centric relation because that provides a repeatable condylar position. He adds that this technique contributes to muscles that are “quiet and unstrained,” and clinicians can determine how the teeth will meet in that particular position. From there they can make determinations about how to reshape, reposition, restore, or otherwise modify teeth so that they are in harmony with that centric relation position.
According to John C. Cranham, DDS, any examination that forms the basis of a treatment plan will include full series of radiographs and photographs and models mounted on an articulator with a facebow. Because dentists should always look at what is going to be the least amount of dentistry for the patient to fulfill their occlusal requirements and, of course, any elective changes the patient wants to make for cosmetic purposes, he suggests four treatment options could be possible, from conservative to more aggressive:
1. Reshaping of the teeth (ie, occlusal equilibration or bite adjustment). Some patients may require a bite splint prior to tooth reshaping, he says.
2. Orthodontics (ie, repositioning the teeth).
3. Restorative procedures. If a patient would require reparative treatment anyway (eg, crowns, fillings, etc), the occlusal requirements can sometimes be fulfilled through restorative procedures, Cranham notes. However, he echoes others by commenting that if things are going to change, then dentists need to ensure the functional stability of the results, as well as perform the least amount of dentistry necessary to achieve the desired and necessary outcome.
4. Orthognathic surgery (ie, repositioning the jaw). In patients demonstrating extreme cases of occlusal problems, surgery may be required, he says.
Cranham observes that in many instances a combination of two of the three treatment options may be necessary to achieve the desired result. Collecting sufficient data and studying the case will help the dentist identify signs or issues with the occlusion.
Maurice A. Salama, DMD, says diagnosis of what type of occlusion is operating in the patient’s mouth—physiological or pathological—is imperative. If it’s physiological, it may not require any treatment. If it’s pathological, three subsequent considerations are necessary:
1. Despite some minor radiographic changes or tooth wear patterns, is the patient functioning pain-free? Salama also notes that it’s important to differentiate between muscular pain and joint pain. Can long-term appliance therapy be provided to evaluate and diagnose the occlusion as the definitive causative factor?
2. Is a temporomandibular disorder (eg, temporomandibular joint disease, osteoarthritis, disk displacement) involved that may have caused changes to the jaw structure?
3. Is the pathology neuromuscular in origin and perhaps created by patient habit? Salama feels it’s essential to know if the problem is something that isn’t occurring anatomically. If there isn’t a problem of osteoarthritis, the bones aren’t changing shape, and the disk is in the correct position, then neuromuscular and behavioral therapy is all that may be required.
These considerations are important, Salama says, because clinicians can cause occlusal discrepancies to exist if they don’t first properly diagnose the patient’s existing condition. “We can actually take a normal bite or a physiological occlusion with no symptoms and, by poor treatment—a single crown or restoration being too high—cause a pathological entity,” he cautions. “Therefore, from the initial phase of treatment, through diagnosis and temporization, and then on to the final phase, we should continue to re-evaluate whether or not the occlusal scheme continues to be maintained in physiological balance.”
Similarly, Michael R. Sesemann, DDS, follows a strategy of evaluating the occlusion at the beginning, middle, and end of the treatment sequence, he says, because occlusion is involved in every step of the treatment in his office. His initial new patient examination includes a clinical screening evaluation of the temporomandibular joints combined with an occlusal evaluation that identifies occlusal disharmonies, signs of dental instability, and functional pathologies, such as a constricted chewing pattern.
“The knowledge I gain from the examination determines what I need in the way of further data collection for proper treatment planning,” Sesemann says. “If the patient has certain issues that make further study mandatory for diagnosis and treatment planning, we schedule the patient for a ‘data collection appointment.’ For patients with occlusal or functional issues, we triage them for impressions and jaw relationship records to provide mounted models for study and possible laboratory equilibration.”
1 Ackerman JL, Ackerman MB, Kean MR. A Philadelphia fable: how ideal occlusion became the philosopher’s stone of orthodontics. Angle Orthod. 2007; 77(1):192-194.
2 Okeson JP. Occlusion, Condylar Position and TMD: Where is the controversy? Where is the evidence. Lecture. 148th American Dental Association Annual Session; September 28, 2007: San Francisco, CA.
The Inside Look From
Issue after issue, the feature presentations in Inside Dentistry deliver coverage of the relevant and thought-provoking topics specifically affecting the dental profession, as well as oral healthcare in general. The publishers and staff could not bring the underlying concerns surrounding these timely issues to the forefront without the insights shared by our knowledgeable and well-respected interviewees. For their collective generosity of time and perspectives, we extend our sincere gratitude.
John C. Cranham, DDS
Director of Education & Instructor
Dawson Center for Advanced Dental Studies
Glenn DuPont, DDS
Dawson Center for Advanced Dental Study
Shamshudin (Sam) Kherani, DDS
Las Vegas Institute for Advanced Dental Studies
John Kois, DMD, MSD
Founder & Director, Kois Center, LLC
Affiliate Professor, University of Washington
Tacoma and Seattle, WA
Gerard Kugel, DMD, MS, PhD
Associate Dean for Research
Tufts University School of Dental Medicine
Ed McLaren, DDS
UCLA Center for Esthetic Dentistry
Noshir Mehta, DMS, MS, MDS
Professor and Chairman, General Dentistry
Assistant Dean, International Relations
Director, Craniofacial Pain Center
Tufts University School of Dental Medicine
Steve Ratcliff, DDS
Chairman, Department of Education
The Pankey Institute
Maurice A. Salama, DMD
Michael R. Sesemann, DDS
Vice President and Accredited Fellow
American Academy of Cosmetic Dentistry
Frank Spear, DDS, MSD
Director and Founder
Seattle Institute for Advanced Dental Education