A Practical Guide to Occlusal Management for the General Practitioner

The general dentist has a unique role as the gatekeeper of dental care. In this role, the generalist is called upon to be the primary diagnostician and is charged with the responsibility for triaging patients. Classification systems devised by many of the dental specialties are valuable tools for the diagnosis of diseases and conditions specific to the specialty, but no classifications have been directed to the general dentist. This paper describes a system being used at the University of California at San Francisco School of Dentistry that enables the general dentist to classify a patient’s stomatognathic system as either physiologic or nonphysiologic and then guides the clinician toward appropriate treatment decisions.

Notwithstanding years of research, the role of occlusion in a broad spectrum of diseases still seems to be an area of disagreement, confusion, and misunderstanding.^1-4 Although the give-and-take of experienced academics and clinicians is healthy and will in time lead to a meeting of the minds, in the real world of clinical dentistry, most general dentists would argue that occlusion is a significant consideration in their care of patients. For the clinician, this respect for the subject began in dental school, when, with his or her first placement of a cast occlusal restoration, a significant amount of clinical time was spent adjusting the occlusion to obtain the patient’s acceptance of the restoration.

A recent review of experimental occlusal interference studies by Clark and colleagues⁵ suggests a reason dental practitioners have a strong regard for the importance of occlusion. When Clark and colleagues assessed studies on the effects of experimentally induced occlusal interferences on the periodontal and pulpal tissues of affected teeth, they found a definite correlation between those interferences and deleterious tissue changes. This suggests that an induced occlusal prematurity will most likely lead to patient discomfort and tissue deterioration. But, they also found these traumatic and inflammatory changes to be transient. In other words, if a patient can tolerate an artificially induced occlusal prematurity, accommodation is likely to occur. The problem in dental practice is that most patients will not just "stand it," so clinical procedures must be planned to avoid creating an occlusal prematurity or, worse, creating a prematurity to which a patient’s stomatognathic system may not accommodate.

The general dentist is unique among dental professionals in his or her responsibility for seeing a diverse population of patients where the assessment of dental health is frequently done as a routine procedure, not associated with specific patient complaints. The chronic nature of the conditions and diseases treated by dentists is akin to beginning a comic strip in the middle, trying to hypothesize what came before, and then predicting the finish. What the general practitioner must do is evaluate signs and symptoms of chronic change of the stomatognathic system and ask the question: Is the stomatognathic system healthy (stable) or unhealthy (unstable). For example, a symptom-free 20-year-old patient with severe attrition of the occlusal surfaces should give more cause for concern than an 80-year-old patient with the same amount of occlusal wear, because a system suffering from premature destruction must be considered unhealthy. Following the discovery phase, the dentist must determine the appropriate care of the system and whether that care is within his or her capabilities. The purpose of this paper is to offer a useful classification system to support the general dentist’s evaluation and care of patients.

Existing Classifications

Although classifications have proven to be useful tools in the assessment and management of dental problems in a number of specialty areas, the literature offers little to guide the general practitioner in the assessment and management of occlusion. For example, the Lytle and Skurow classification⁶ uses the complexity of periodontal and restorative needs to identify four classes: operative dentistry, crown and bridge, occlusal reconstruction, and periodontal prosthesis. It allows the clinician to determine a restorative class and treatment protocol for the patient. However, differentiation between the classes is based upon the technical difficulty of the anticipated restorations, not on the diagnosis of existing occlusal abnormality.

The popular Angle classification of "malocclusions" is used extensively in orthodontics. This classification is based upon morphological differences between patients. However, when taken in context with other measures of dental health for a given individual, Angle’s classes may be found to be physiologically sound. At the University of California at San Francisco School of Dentistry, Angle’s classification is considered to be of morphologic variations not malocclusions.⁷

Another classification system, developed by Helkimo,⁸ classifies dysfunction of the temporomandibular joint in three types according to the scoring of a dysfunction index with five parameters. The parameters are impaired range of motion, impaired TMJ function, muscle pain, TMJ pain to palpation, and pain upon mandibular movement. This classification is a valuable tool for the assessment of TMD, but it does not address intraoral findings. None of the aforementioned classifications addresses the situation of the general dental practitioner.

A more broadly based system directed toward the general dentist was initially published by Braly⁹ in 1972. Braly based his classification on patient data and the need to maintain, modify, or re-establish occlusal stability. The Braly classification system has since been modified, expanded, and incorporated into the teaching program at UCSF to be used as an aid in teaching comprehensive patient care to students of general dentistry. This paper will use a portion of the UCSF Braly-type classification and draw from the clinical experience of the authors in presenting a guide for assessing and managing occlusion in the daily care of general dental patients. It will be divided into three sections: diagnosis, treatment planning, and treatment procedures.

Diagnosis

As health care providers, dentists should all subscribe to the basic logic of patient care: Data acquisition through examination and history must necessarily precede a diagnosis, which in turn must necessarily precede treatment recommendations. Adherence to this simple scheme helps ensure that dentists develop the most appropriate treatment plans for their patients. Yet dentists often place more emphasis on their examination findings and treatment recommendations than on the diagnoses. For example, it is a rare dental chart that has a designated area for diagnoses. And, unlike physicians, dentists are not accustomed to determining and providing the appropriate diagnostic codes to insurance companies for reimbursement of completed procedures. Perhaps this is not surprising when one considers that the diagnoses dentists generally make are, for the most part, unproblematic. The findings that lead to a diagnosis of caries or periodontal disease are usually obvious and rarely suggest competing diagnoses that require careful differential analysis. Occlusion-associated, degenerative processes in the stomatognathic system, however, are not as straightforward. While dentists may all do a good job of examining the occlusion and recording their findings, it is the next step -- making the diagnosis -- that often proves troublesome.

Periodontal specialists have provided a good model to diagnose destructive processes and direct appropriate care.¹⁰ The now-standard case-type designations (I-IV) for periodontal disease aid the general dentist in arriving at a diagnosis and possible treatment. Bleeding on probing, increased pocket depth, attachment loss, and other findings now lead to a particular case-type designation based on accepted criteria. Treatment recommendations can then follow logically from a given diagnostic type (e.g., a diagnosis of gingivitis [Case Type I] necessarily excludes root planing from the list of treatment recommendations and necessarily includes oral hygiene instruction).

At the UCSF School of Dentistry, a modified Braly⁹ classification system is used to establish a "physiologic" or "nonphysiologic" designation for the stomatognathic system in a manner similar to the one used by periodontists. The system designates six Case Types (A-C and I-III) that allow for treatment decisions based upon a thorough evaluation of the stomatognathic system.

Case Types A-C are related to findings for which treatment will not involve the restoration of tooth structure. For example, a Case Type A patient might present with soft tissue pathology such as lichen planus, candida infection, or cancer. For this case type, no restorative procedure is necessary; and the goal of treatment should be to maintain an otherwise physiologic stomatognathic system. A Type B patient might present with occlusal discrepancies causing discomfort in individual teeth for which the treatment might include occlusal adjustment or extraction (such as an unopposed super-erupted third molar). Finally, a Type C patient might present with a severe retrognathic mandible and dysfunctional TMJs requiring complex multidisciplinary evaluation and care.

Case Types I-III are related to findings for which treatment will require dental restorations. Since, at present, general dentistry is primarily restoration-based, this paper’s focus has been limited to Case Types I-III.

For purposes of this article, the stomatognathic system is defined as the combination of structures involved in speech; receiving, mastication, and deglutition of food; and parafunctional actions.¹¹ Evaluation of this system involves both an examination of these structures and an examination of the functional relationship between them. Occlusion is defined as the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues.¹² To be designated physiologic, the stomatognathic system must be healthy, stable, and functioning within the expected norms, i.e., no detectable tissue degeneration nor pain in associated structures. To be designated nonphysiologic (unhealthy, unstable), the system must display evidence of past or present unexpected degenerative processes. Findings are the clinical evidence needed to support a diagnosis and, ultimately, treatment decisions.

The Table outlines the clinical findings, occlusal therapy and goals for Case Types I, II, and III. Case Type I by definition is a system that is functioning within the expected norms. Typical findings for this case type include healthy, uncompromised supporting tissues and structures; occlusal wear appropriate to the age of the patient; pain-free unimpeded movements of the mandible; and a "normal" retruded contact position (RCP) to maximum intercuspal position (ICP) shift.

As described by Stroud,¹³ shifts from RCP to ICP found in symptom-free patients are subject to considerable "normal variation" without evidence to suggest an etiology in temporomandibular joint dysfunction. For this classification, a normal shift is described as one for which a causal relationship with clinical findings cannot be found (tooth mobility, fracture, excessive occlusal wear, etc.). The goal for the Case Type I is to avoid affecting the stomatognathic system adversely by whatever restorative or preventive (sealants, etc.) procedure is required as a part of routine dental care. Some would argue this is technically the hardest of the case types to manage (Figures 1A and B).

Case Types II and III define a system that is not functioning within the expected norms and is, therefore, termed nonphysiologic (Figures 2A and B, 3A and B). Typical findings associated with a nonphysiologic system may include unrestored missing teeth; limited TMJ function; tissue inflammation; pain; tooth hypermobility; a loss or replacement of tooth structure beyond that expected for the age of the patient (e.g., a young patient with extensive caries, multiple root canals, crowns, fixed and removable partial dentures, and/or severe occlusal wear); and an "abnormal" RCP to ICP shift. An "abnormal" shift is defined as one in which a causal relationship with clinical findings such as mobile teeth, tooth fracture, and tooth wear is suspected. Case Type II is distinguished from Case Type III by the absence of TMD or other dysfunctional findings.

Treatment Planning Restorative Procedures

Treatment planning with the goal of maintaining or acquiring a physiologic system requires the perspective that there is not just one restorative material, technique, or procedure that is appropriate for every case type. Each case type must be addressed individually and the materials, techniques, and procedures tailored to the goal for that type.

Case Type I

As described above, the goal in treating the stomatognathic system of a patient diagnosed as a Case Type I is to render necessary care that will maintain a system found to be functioning in a physiologic fashion. Treatment planned for the Case Type I patient should not alter the physiologic health of the existing system, so the clinician must choose materials and techniques that are least likely to adversely affect the system. As clinicians, however, dentists frequently fail in this regard. For example, it is not uncommon to see as many as four or five different materials (porcelains, resins, alloys, and hybrid materials) used to restore occlusal surfaces and interspersed around a patient’s dentition.

One of the best materials for maintaining a physiologic occlusion is gold. Unfortunately, gold is not tooth-colored; and the result is that for the sake of esthetics many young dentitions have been started on the road to destruction with the placement of a highly abrasive feldspathic porcelain restoration.^14-17 Hopefully, the development of new, more physiologic materials with acceptable esthetic properties will result in less destruction.

Case Type II

Once a diagnosis of a nonphysiologic Case Type II has been made, appropriate treatment might include occlusal adjustment, orthodontics, restorations, or other procedures that directly address the causative element in the destructive process. Examples include adjustment of an occlusal prematurity to correct individual tooth mobility, an orthodontic procedure to correct tipping or drifting teeth, a fixed partial denture to stabilize the arches, placement and restoration of implants, or the use of various modalities (occlusal splints, nightguards, biofeedback therapy, etc.) to modify destructive-habit patterns.

The determination that a system is not or has not functioned physiologically must lead the clinician to a careful assessment of those factors contributing to the degenerative processes. In addition to the usual patient data, one of the most valuable tools for assessment of the Case Type II patient is an arcon articulator with casts mounted in RCP (a.k.a. centric relation). To hand-hold or mount casts in ICP (a.k.a. centric occlusion) for diagnostic purposes is much like looking out from the home plate of a baseball diamond and not realizing that a lot of the action in the game takes place behind you. The use of casts accurately mounted in RCP allows the diagnostician to evaluate the entire playing field from the backstop. From this perspective, articulated casts can be used to assess the relationship between the dentition and the supporting structures and determine the proper procedures required to correct any degenerative processes a clinician may suspect are associated with the occlusion.¹³

When the degenerative processes have been controlled or corrected, subsequent care of the Case Type II patient can proceed in a fashion similar to the Case Type I patient. The same careful selection of materials, techniques, and procedures is required to maintain the newly acquired relationship.

Case Type III

The most difficult to manage is the Case Type III. This case type has dysfunctional problems plus chronic disease processes that with current knowledge will probably only be managed and not cured. Exceptional diagnostic skills and clinical judgment must be used to determine the proper approach to treatment. Like the complex cancer patient, the Case Type III will likely be treated by a multidisciplinary team. For this reason, the Case Type III is NOT an appropriate patient for treatment in the average general practice and should be referred to an appropriately trained individual capable of managing the necessary multidisciplinary care. Proper treatment might include long-term TMD management, orthodontics and orthognathic surgery, periodontics, fixed or removable prosthodontics, or other complex procedures.

Treatment Procedures

Case Type I

Treating a stomatognathic system that is physiologic without the potential for destabilizing the existing stability is not easy. Direct restorative procedures must be carefully performed to avoid altering the occlusion. Occlusal restorations should be of minimal widths and designed around occlusal contacts. Areas of restored occlusion must be carefully adjusted to ensure simultaneous occlusal contacts that fit properly into the existing system.

Clinicians should use techniques that have the best chance of delivering an accurately fitting restoration. The use of some quadrant techniques and bite registration materials that deliver a restoration in hyper- or hypo-occlusion will allow teeth to drift, result in an altered functional relationship, and potentially destabilize a healthy system. Will the placement of a restoration that is in hyper-occlusion result in a nonphysiologic system? The answer, as cited by Clark and colleagues,⁵ is an emphatic "yes," but most systems eventually accommodate to the error. Similarly, a restoration in hypo-occlusion may result in uncontrolled hyper-eruption of opposing teeth and lead to an altered functional relationship.¹⁸

Indirect quadrant techniques that utilize ICP are best for the Case Type I. Recording an accurate jaw relationship, however, is one of the biggest challenges to indirect restorative techniques. Douglass¹⁹ described two variables that influence the clinician’s ability to accurately register interocclusal relationships. Those described were the movement of teeth within their periodontal ligaments that is necessary for any dentulous patient to achieve ICP²⁰ and the narrowing of the mandible that can occur when the mandible is opened beyond 25 percent of its maximum.^21-23

The "double-bite" (a.k.a. triple-tray) is an example of a closed-mouth quadrant technique that effectively addresses the variables described by Douglass. First, the teeth are impressed while the patient is closed in ICP, and second, the closed mouth impression decreases the distortion of the mandible that can occur during an open-mouth impression. The advantage of a closed-mouth impression technique is the accuracy of the ICP that can be achieved.

Quadrant techniques utilizing open-mouth impressions and closed-mouth occlusal registrations are subject to serious errors, due not only to the distortions of the casts but also to artifacts inherent in all casts (e.g., bubbles, tears). Numerous materials are available for registering interarch relationships. Among these are wax, acrylic, zinc oxide-eugenol pastes, and elastomeric materials. All materials used to register jaw relationships have problems unique to themselves, but any of these materials used to record a closed-jaw relationship will not accurately fit a cast made from an open-mouth impression. Regardless of how meticulous the technique may be, restorations made with direct or indirect techniques must always be carefully adjusted clinically to avoid creating an occlusal instability.

Case Type II

Treatment of the Case Type II, by definition, requires modification of an unhealthy stomatognathic system. The clinician, therefore, must have a goal toward which to work. McNeill²⁰ describes the objectives for occlusal treatment as:

* Maximum symmetric distribution of the centric contacts in the intercuspal position;

* Axial or near-axial loading of the teeth;

* Acceptable occlusal plane;

* Guidance contacts allowing for freedom in closing and excursive gliding mandibular movements without deflection; and

* Acceptable vertical dimension of occlusion and interocclusal resting range.

The more extensive procedures generally required in the treatment of diagnostic Case Types II will most likely force the clinician to utilize open-mouth impression, full-arch techniques. But a procedure that utilizes an open-mouth impression is subject to distortions in the casts as described above for quadrant techniques, and, therefore, to an inability to accurately place these casts into occlusal registrations made from teeth that moved while in the process of achieving an ICP.

To best address the limitations inherent in the use of full-arch casts, registrations should be restricted to the prepared teeth and carefully trimmed to limit interarch registrations to very small and strategic areas of the casts. The purpose of an occlusal registration is to stabilize the working cast horizontally and to accurately record the vertical dimension between the arches. Any material that can be trimmed and adjusted to best achieve this purpose for a specific case should be the choice of the clinician.

Achieving the objectives as described by McNeill requires that the clinician consider restoring to an RCP jaw relationship, for it is this relationship that will most predictably achieve the objectives for axial loading and nondeflective contacts.²³ This does not mean that all Case Type II patients should have their dentitions modified to close in an RCP maxillomandibular relationship if treatment goals can otherwise be achieved. As with the Case Type I, procedures must be followed carefully to avoid creating an occlusal prematurity and the potential for destabilizing the system.

Case Type III

The treatment goal for a patient diagnosed as a Case Type III is to re-establish the stability of a severely dysfunctional system. This can be an intimidating experience for an uninitiated clinician. Certainly, novice general practitioners would be well-advised to refer these patients to those with more experience and expertise. Developing the expertise, however, does not require formal graduate programs. Many general practitioners gain valuable experience and expertise through continuing education lectures and interactive study groups.

As the dentist from whom the majority of patients first seek dental care, the general dentist must have the skills to collect data and make a diagnosis and the wisdom to recognize his or her limitations. For the care of patients, and the well-being of the practitioner, it is important the general dentist be able to recognize Case Type III patients and the complexities associated with their care.

Conclusion

The vast majority of adult patients begin their care with a general dentist. As the primary diagnostician, the general practitioner has an enormous responsibility to the patient to properly assess, diagnose, and manage any chronic conditions and/or diseases. When it comes to diagnosing occlusion-related problems, however, few guidelines exist. This article has presented a classification system used at the University of California at San Francisco to assist the general dentist in the diagnosis, treatment planning, and management of problems associated with the stomatognathic system.

Author

Gordon D. Douglass, DDS, MS, is a clinical professor in the Department of Preventive and Restorative Dental Sciences at the University of California at San Francisco School of Dentistry.

Larry Jenson, DDS, is an assistant clinical professor in the Department of Preventive and Restorative Dental Sciences at UCSF.

Daniel Mendoza, DDS, is an assistant clinical professor in the Department of Preventive and Restorative Dental Sciences at UCSF.

References

1. Kao RT, Role of occlusion in periodontal disease. In, McNeill C, ed, Science and Practice of Occlusion. Quintessence Publishing, Chicago, 1997, pp 394-403.

2. Okeson JP, Management of Temporomandibular Disorders and Occlusion, 4th ed. Mosby-Year Book, St. Louis, 1998, pp 149-54.

3. Stohler CS, Clinical decision-making in occlusion: A paradigm shift. In, McNeill C, ed, Science and Practice of Occlusion. Quintessence Publishing, Chicago, 1997, p 298.

4. Roth RH, Gnathologic considerations for orthodontic therapy. In, McNeill, ed, Science and Practice of Occlusion. Quintessence Publishing, Chicago, 1997, p 503.

5. Clark GT, Tsukiyama Y, et al, Sixty-eight years of experimental occlusal interference studies: What have we learned? J Prosthet Dent 82(6):704-13, 1999.

6. Lytle JD and Skurow H, An interdisciplinary classification of restorative dentistry. Int J Perio Rest Dent 3:9-16, 1987.

7. Douglass G and DeVreugd R, The dynamics of occlusal relationships. In, McNeill C, ed, Science and Practice of Occlusion. Quintessence Publishing, Chicago, 1997, pp 69-78.

8. Mandibular function and dysfunction. In, Shaw E, ed, Orthodontics and Occlusal Management. Butterworth-Heinemann, Oxford, 1993, pp 259-60.

9. Braly BV, Occlusal analysis and treatment planning for restorative dentistry. J Prosthet Dent 27:168-71, 1972.

10. Academy of Periodontology, Dental Insurance Workshop: Reporting Periodontal Procedures to Third Parties. Scientific, Clinical and Educational Affairs Department, Academy of Periodontology: 18, 1992

11. The Academy of Prosthodontics, Glossary of Prosthodontic Terms. J Prosthet Dent 81:101, 1999.

12. The Academy of Prosthodontics, Glossary of Prosthodontic Terms. J Prosthet Dent 81:88, 1999.

13. Stroud L, Mounted study casts and cephalometric analysis. In, McNeill C, ed, Science and Practice of Occlusion. Quintessence Publishing, Chicago, 1997, pp 331-41.

14. Kelley JR, Nishimura I, Campbell SD, Ceramics in dentistry: historical roots and current perspectives. J Prosthet Dent 75(1):18-32, 1996

15. Hacker CH, Wagner WC and Razzoog ME, An in vitro investigation of the wear of enamel on porcelain and gold in saliva. J Prosthet Dent 75(1):14-7, 1996.

16. Ramp MH, Suzuki S, et al, Evaluation of wear: enamel opposing three ceramic materials and a gold alloy. J Prosthet Dent 77(5):523-30, 1997.

17. Hudson JD, Goldstein GR, Georgescu M, Enamel wear caused by three different restorative materials. J Prosthet Dent 74(6):647-54, 1995.

18. Okeson JP, Management of temporomandibular disorders and occlusion, 4th ed. Mosby-Year Book, St. Louis, 1998, p 578.

19. Douglass G, The cast restoration -- Why is it high? J Prosthet Dent 34(5):491-5, 1975.

20. Goto T, An experimental study on the physiologic mobility of a tooth. Shikwa Gakuho 71:1415-44, 1971.

21. McDowell JA and Regli CP, A quantitative analysis of the decrease in width of the mandibular arch during forced movements of the mandible. J Dent Res 40:1183-5, 1961.

22. Regli CP and Kelly E K, The phenomenon of decreased mandibular arch width in opening movements. J Prosthet Dent 17:49-53, 1967.

23. McNeill C, Selective tooth grinding and equilibration. In, McNeill C, Science and Practice of Occlusion. Quintessence Publishing, Chicago, 1997, pp 404-15.

To request a printed copy of this article, please contact: Gordon D. Douglass, DDS, MS, UCSF School of Dentistry, San Francisco, CA 94143-0758 or at gordond@itsa.ucsf.edu.

Legends

Figure 1A. A Case Type I patient: This 35-year-old patient presents with a complaint of poor anterior bridge esthetics. Clinical evaluation reveals the stomatognathic system to be physiologic. Treatment procedures should, therefore, be directed toward techniques and materials that will maintain the healthy function of the existing system.

Figure 1B. A Case Type I patient: This 42-year-old patient presents with a complaint of pain upon chewing on the left side. Clinical evaluation reveals a fracture of the distolingual cusp of the lower left first molar due to an extensive undermining restoration. Other than this finding, the stomatognathic system is physiologic. Treatment procedures in this case should be directed toward the selection and use of a restorative material that will not compromise the normal physiology of the existing system.

Figure 2A. A Case Type II patient: This 38-year-old patient presents with a complaint of an inability to chew efficiently. Clinical evaluation reveals extensive loss of teeth, loss of alveolar support, large restorations, and an ill-fitting removable partial denture, but no evidence of a dysfunctional craniomandibular relationship. The severity of the oral conditions, however, suggests a nonphysiologic stomatognathic system. Treatment procedures should, therefore, be directed toward modifying the factors contributing to the destructive process.

Figure 2B. A Case Type II patient: This 42-year-old patient presents with a complaint of worn teeth and anterior esthetics. Clinical evaluation reveals heavy attrition and chipping of the anterior teeth, but no evidence of craniofacial pain, TMD, nor other dysfunctional relationship. Treatment procedures should, therefore, be directed toward modifying the factors contributing to the destructive process prior to initiating restorative care.

Figure 3A. A Case Type III patient: This 52-year-old patient presents with a complaint of pain on chewing. Clinical evaluation reveals extensive loss of teeth, drifting and super-eruption of the remaining teeth, deep anterior vertical overlap, and TMJ pain. This patient is diagnosed as having a nonphysiologic dysfunctional stomatognathic system. Treatment must, therefore, be directed toward re-establishing a functional stomatognathic system.

Figure 3B. A Case Type III patient: This 50-year-old patient complains of tipping teeth and an inability to incise. Clinical evaluation reveals a need for multiple restorations but healthy gingival tissues. The lower right posterior teeth are flaring facially, and the posterior bite is opening. Further analysis reveals a severely deviated swallow, suggesting a nonphysiologic dysfunctional stomatognathic system. Treatment for this patient must be directed toward correcting the dysfunctional relationships before restorative procedures can be undertaken.

Table. Clinical Findings, Occlusal Therapy and Goals for Case Types I, II, and III