Applying Two Major Classification Systems to Restorative Dentistry

Scott W. Cairns, DDS

January 2015 Issue - Expires January 31st, 2018

Inside Dentistry


Dentists who complete a thorough examination and history of a patient’s occlusion and jaw joint will benefit in two main ways. They will increase the value of the examination in the mind of patients and make strategic and better informed decisions regarding all levels of patients’ restorative care needs. Dentists can use five simple steps to gather information about the joints and help facilitate an occlusal diagnosis according to the Piper and Dawson classification systems. A determination of joint/occlusal status using these systems will enable dentists to decide which patients are safe to treat immediately and which will require additional therapy or diagnostics prior to simple or complex restorative treatments.

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In medicine, every procedural code has a corresponding diagnosis code. Requiring physicians to diagnose each case compels them to label the conditions they are treating. The practice of naming a condition based on the symptoms, history, and observation is also done routinely in dentistry. However, dental practitioners are not always diligent about diagnosing all of the conditions they encounter. One commonly overlooked and misdiagnosed pathology is the condition of the jaw joint and occlusion.

Completing and recording information gained during a slightly more thorough examination and history of a patient’s occlusion and jaw joint can greatly increase the value of the examination—both in the mind of patients and in the ability of dentists to make strategic and better informed decisions regarding all levels of restorative care needs, including single-tooth dentistry.

Five simple steps will be presented in this article to help enable the dentist to identify, classify, and diagnose joint and occlusal status. Two classification systems—one for the joint and one for occlusion with regard to the joint condition—will be explained, and the associated technique to determine the classification will be presented. Using this information, dentists can determine which patients are safe to treat and which will require additional therapy or diagnostics prior to simple or complex restorative treatments.


A great deal of confusion exists in the dental community regarding occlusion.1 Every restorative dentist influences occlusion on a daily basis and typically does so with enough knowledge not to cause immediate or noticeable damage to the masticatory system—or else patients simply adapt. Few dentists take the time to catalog their patients’ occlusion in terms of changes over time. So, although they know how to adjust restorations so that they do not cause the patient pain or immediately noticeable differences to the bite, few take the time to identify the condition of the bite or the joint in most examinations.

There are, however, many classification systems to catalog how patients’ teeth come together and the likely condition of the jaw joint. The two described below can help “wet glove” dentists notice changes occurring within the occlusal system and more predictably treat patients with single-tooth restorative needs, knowing that changes being made will not cause harm to the occlusal system or the doctor-patient relationship. One classification system is a joint classification (Piper); the other classification system is an occlusal classification (Dawson). Using these two systems together can quickly provide dentists with greater insight into their patients’ occlusion.

The Piper Classification System

An elegant classification system created by Mark Piper, DMD, MD, offers a presumptive diagnosis of the jaw joint.2 This method, which can be quickly learned, requires no expensive diagnostic aids and can be implemented quickly during a patient encounter. Eight separate categorizations are grouped as five stages, I to V, where I is normal and V is the most chronically diseased state, in which the entire disk has displaced and a chronic perforation of the retrodiscal tissue has occurred (Table 1).

The key to using the Piper Classification correctly is to combine patient history with palpation and auscultation information. While history and palpation do not require any equipment, auscultation is best determined with the use of a Doppler, which can be used as a co-discovery tool to allow the dentist and patient to hear displacements and perforations.4,5 If this tool is not available, a stethoscope will also work, but co-discovery will be limited.

Palpation Technique

The technique of palpation of the lateral joint is performed by placing the middle finger anterior and inferior to the tragus of the ear. The patient should be instructed to open slightly and close slightly while in a rotation. Next, they should open and close fully. It is helpful to notate when the displacement and reduction occurs—whether it is early or late on opening and closing. It is also helpful for the dentist to place a pinky finger into the auditory canal and ask the patient to open and close until it is possible to locate the posterior aspect of the condyle and press anteriorly and inferiorly to compress the tissues behind the canal. This will often prompt patients who have ligaments that do displace but have reduced back onto the condyle to displace during rotation or translation by the time they are seen again.

Information Gathering

While the gold standard for making a diagnosis of the condition of the disc would be to have an magnetic resonance imaging (MRI) interpretation,6 ordering an MRI for every dental patient as a screening tool is unnecessary. A presumptive diagnosis can be derived from a combination of observation and information gathered from the patient’s dental history. The history is augmented throughout the examination, as questions are asked of each patient relating to the dentist's clinical observations.

As part of a good occlusal history, it is recommended that the dentist ask questions such as the following to help determine the proper Piper classification: “Have you ever experienced any noise in front of your ear?” For clarification, the dentist may add, “Have you ever heard any clicking or popping in your jaw joint?” Another crucial question is, “Has your jaw ever become stuck or locked?” If the answer is yes, the dentist should find out when, how often, and the type of lock it was.

The Auscultation Examination

As noted above, the auscultation examination is best performed using a Doppler,7 but a stethoscope may be used if a Doppler is not available.8

If a Doppler is being used, the tip of the Doppler should first be prepped with 1/4 inch of lubricating gel. To start, the Doppler should be positioned slightly behind the lateral pole to listen to the superficial temporal artery before moving the tip forward until the sound of the artery is lost. The patient is then asked to open and close five to six times. Next the movement is isolated to a pure rotation movement, and the patient is asked to only open only one quarter of an inch five to six times. Next, the translation movement is tested by asking the patient to slowly open fully, again five to six times. The patient is then asked to go through an additional movement of lateral excursion to the opposite side five to six times. As patients hear normal and diseased states, those with disease will begin to understand that something is in need of attention.

If a stethoscope is used for auscultation, the same patient movements and instructions are followed as with the Doppler. Placing the face of the stethoscope over the lateral joint will allow the doctor to hear all noises. The disadvantage of the stethoscope method compared with the Doppler method is that the patient will not hear the difference between a healthy noise and a diseased sound, so more time is needed to explain the situation and more trust is required of the patient.

The Dawson Classification System

To gain a full picture of the patient’s occlusion, information beyond that needed to use the Piper Classification System is also required; the clinician needs to know how the teeth fit together in centric occlusion. For this, it is also helpful to also classify patients with the Dawson Classification System.

The Dawson Classification System is dependent upon identifying whether the patient’s maximum intercuspation (MIP) is in harmony with the patient’s arc of closure, or if the patient’s MIP requires the patient to move from their arc to get into MIP.9,10 In addition, one must determine if the patient’s joint is pain free on loading or if it is actively degenerating. Techniques for determining the arc of closure are described below.

Similar to the Piper Classification System, the Dawson Classification has general categories and subcategories, with a total of six separate groups (Table 2). The first two categories (I and II) describe a joint that is stable enough to relate the occlusion to the joint. Both are subdivided into the primary form of the classification or the subgrouping identified with “a,” depending on whether the patient has an unaltered centric relation (CR) or if he/she has an adapted centric posture (ACP). ACP is the manageably stable relationship of the mandible to the maxilla that is achieved when deformed temporomandibular joints have adapted to a degree that they can comfortably accept firm loading when completely seated at the most superior position against the eminentiae. Dawson groups III and IV describe a jaw joint that is painful to load, or unstable, making a distinction about a patient occlusion uncertain.

Arc of Closure Techniques

Multiple techniques exist to get patients into their arc of closure, although it can be a challenge to identify their CR with the existence of inflammation. Two techniques that can be learned relatively quickly and are simple to incorporate into the examination process are bilateral guidance and use of a leaf gauge.

The bilateral guidance/manipulation technique combines didactic knowledge of CR with tactile information from manipulating the patient’s mandible and observing the alignment and position of each condyle.11 Hands-on experience is required to master the technique and identify the sensation that occurs when it is performed correctly. Acquiring this skill requires a couple of hours of instruction—eg, via courses available from Pankey Institute, Dawson Academy, or Spear Education—and a little practice.12-14

Alternatively, use of a leaf gauge is a quick and easy way to locate CR—ie, the maxillo-mandibular relationship when the properly aligned condyle-disc assemblies are in the most superior position against the eminentiae, irrespective of tooth position or vertical dimension. To use the leaf gauge, the clinician should place 3 to 4 mm of plastic leaves between the maxillary central incisors and the mandibular central incisors, and ask the patient to slide his/her lower jaw forward, then slide back, and when back or retruded, to lightly squeeze. When asked if any teeth are touch, if the patient answers yes, leaves should be added and the process repeated until the patient verifies that no teeth are touching. At this point, the dentist should begin removing leaves and repeat the forward-back-squeeze technique until the point of first tooth contact.15

Five-Step Combined Classification Determination

Using the steps listed below, the clinician can determine a patient’s classification in both the Piper and Dawson systems. It may be helpful to have a check box with descriptions of all the different classifications on a piece of paper that can be quickly checked along with all the other data collected with regards to the patient’s occlusion. The five steps are:

1. Determine whether the patient has a history of locking joint.
2. Palpate the joint.
3. Listen to the joint.
4. Locate CR or ACP.
5. Load joint.

Using the Diagnosis for Treatment

While the majority of patients will be healthy or stable enough that they do not need to be classified prior to treatment, certain patients are risky to treat. It is therefore useful to have a system in place to quickly classify all patients to ensure that the changes in the occlusion that will be introduced through the restorative process will not cause the patient any harm.

Of course a dentist who is recreating an occlusion by restoring the majority of occlusal surfaces within an entire arch of teeth needs to know as much about the patient’s joint health as possible and have obtained a level of familiarity of locating a patient’s CR arc of closure. However, this information also helps dentists who are primarily concerned with treating single teeth and segmental sections of occlusion.

Any patient in Dawson III or IV is risky to treat with restorative dentistry because of the instability of the joint. It may be possible to treat these patients, but the larger the segment of teeth that are being restored or the more critical to the patient’s occlusion the tooth being treated is, the riskier treatment becomes. Treating patients with Piper “a” (acute) classifications can also be risky.

The vast majority of the time, working on a single tooth is safe and uneventful regardless of a patient’s Piper or Dawson classification, and perhaps this is why we do not make a habit of recording the information. However, some notable exceptions to the rule are when the tooth to be restored is the primary contact in centric occlusion, when a few other teeth are in occlusion in the quadrant, and when a person has recently been experiencing changes with how their teeth come together outside of any dental treatment (active degenerative joint.)

Tracking the Diagnosis Over Time

Classifying patients and revisiting the classification will open up deeper and more meaningful conversations with the patient and allow for the management of long-term chronic conditions that typically are not painful and do not present immediate motivation toward treatment.

Using both classification systems is also advantageous in observing and initiating efforts to halt the progression of ligament laxity and attempt to prevent its conversion into a more advanced stage. This can be achieved using appliance therapy to help align the disc to a more stable position over the medial pole; it cannot be used to tighten the ligament to eliminate joint noise. The classification systems can also be used to provide a more objective assessment of the efficacy of appliance therapy.


Dentists today would never treat periodontal disease without objective measurements—and with these two systems, restorative dentistry can rely on data as well. Drs. Dawson and Piper have provided dentists with classifications that enable them to provide their patients with the same objective measures of disease progression of occlusion. Making a habit of performing the necessary five steps to catalog their occlusion is not difficult. Dentists who become comfortable routinely using the five steps will find the classifications will be less and less cumbersome to use. Treating occlusion with the same respect accorded periodontal disease will ultimately help dentists to better serve the patients who have entrusted their oral health to a dentist’s professional care, skill, and knowledge.


1. Davies SJ, Gray RM, Smith PW. Good occlusal practice in simple restorative dentistry. Br Dent J. 2001;191(7):365-368, 371-374, 377-381.

2. Piper classification of TMJ disorders. Accessed November 6, 2014.

3. Kalaykova S, Lobbezoo F, Naeije M. Two-year natural course of anterior disc displacement with reduction. J Orofac Pain. 2010;24(4):373-378.

4. Barkley RF. Successful Preventive Dental Practice. Macomb, IL: Preventive Dentistry Press; 1972.

5. Carlisle LD. Motivational Interviewing in Dentistry. Adjuvant New Media; 2014.

6. Takaku S, Sano T, Yoshida M, Toyoda T. A comparison between magnetic resonance imaging and pathologic findings in patients with disc displacement. J Oral Maxillofac Surg. 1998;56(2):171-176.
7. Davidson SL. Doppler auscultation: an aid in temporomandibular joint diagnosis. J Craniomandib Disord. 1988;2(3):128-132.

8. Tyson KW. The role of occlusal auscultation in assessing dental occlusions. Br Dent J. 1996;180(8):307-310.

9. Dawson PE. A classification system for occlusions that relates maximal intercuspation to the position and condition of the temporomandibular joints. J Prosthet Dent. 1996;75(1):60-66.

10. Deng X, Wan Z, He SS, et al. [The centric relation-maximum intercuspation discrepancy in adult angle’s class II pretreatment patients.][Article in Chinese] Hua Xi Kou Qiang Yi Xue Za Zhi. 2011;29(1):48-52.

11. Dawson PE. Functional Occlusion: From TMJ to Smile Design. St. Louis, MO: Mosby; 2006.

12. Spear FM. The business of occlusion. J Am Dent Assoc. 2006;137(5):666-667.

13. Paixão F, Silva WA, Silva FA, et al. Evaluation of the reproducibility of two techniques used to determine and record centric relation in angle’s class I patients. J Appl Oral Sci. 2007;15(4):275-279.

14. Zoidis P, Troulis A, Polyzois G. The use of an anterior deprogrammer in a removable prosthodontic case: the key to accurate and predictable centric relation records. Gen Dent. 2014;62(5):60-63.

15. Fleigel JD III, Sutton AJ. Reliable and repeatable centric relation adjustment of the maxillary occlusal device. J Prosthodont. 2013;22(3):233-236.

Table 1

Table 2

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SOURCE: Inside Dentistry | January 2015

Learning Objectives:

  • Discuss the benefits of performing an examination that includes assessment of the joint and occlusion.
  • Describe the five-step method presented to provide valuable information about the joint and occlusion.
  • Explain the two different classification systems presented.