When restoring peg laterals and laterals that are undersized, great goals are to optimize the final aesthetics and not have to do any tooth preparation prior to adding restorative material. In this blog, I’d like to discuss where we should have the orthodontist optimally position the laterals prior to restoration.

True Peg Laterals

In the case of a true peg lateral, I think of the tooth like I would an implant abutment. In my mind’s eye, I visualize the tooth as a fixture with an abutment on it.

When I talk with the orthodontist, I communicate that I want a minimum of 1 mm and a maximum of 1.5 mm of space between the mesial on the lateral incisor and the distal on the central incisor.

If there is excess space, it is going to be on the distal. We always hide excess space or insufficient space on the distal side of an upper anterior tooth. We always want to perfect the effect on the mesial so we achieve a perfect emergence profile.

And then I communicate that I want the labial of that peg lateral to be positioned about 1 mm to the lingual of where the final facial of the tooth position will be so that I can add material–composite or ceramic, without having to prep the tooth. This position is going to ideally position the free gingival margin of the tooth exactly where I want it based on the free gingival margin of the canine and central incisor. The CEJ is going to be placed exactly where I want the CEJ.

Undersized Lateral Incisors

Often, we have lateral incisors that are not true peg laterals. They’re just undersized lateral incisors. In this case, we must do a thought process about how much restorative material will be added and calibrate how much forward dimension will be added to the tooth. If I’m going to have .5 mm of material on the labial, then I will have the orthodontist position the tooth .5 mm lingually.

If the emergence profile is perfect, then the orthodontist should make it touch the central and all the added material will go on the distal. If not, then a little material will be added to the mesial and to the distal.

Often, for me, the process is thinking, “Where do I want to add restorative material and how much material do I want to add?” Then, I think about where to position the tooth in the space so I will not need to remove any of the tooth structure.

Why Occlusal Appliance Therapy Is My First Step Prior to Ortho, Equilibration, or Restorative

Occlusal changes on an appliance are easy and reversible. An appliance can immediately reduce elevator muscle activity and give the patient relief. The patient also experiences what changes to their tooth contacts could provide for them long term. We can test the changes that would be made by ortho, equilibration, and/or restorative.

As reviewed in Part 2 of this series, our goals are to stabilize the joint anatomy and reduce the activity of the elevator muscles because those muscles are what overload the joints and teeth. We also want to slow down the rate of damage to the dentition and move that rate back to a more age-appropriate pace. We also may need to reorganize a patient’s occlusion to manage occlusal forces to ensure restorations that last.

Removing Posterior Contacts Does Not Work for Every Patient

Over my years of clinical practice, I have found that changing the occlusion does reduce functional risk for most patients. But we all have patients with perfect occlusion who present with TMD symptoms. We have some patients who continue to parafunction after we move them into immediate posterior disclusion.

Studies show that proprioception causes the elevator muscles to engage in only 80 to 85% of the population. This means that when the brain receives the signal that teeth are touching, the brain elevates the masseter muscles in 80 to 85% of people. Tooth contact is the trigger. Because this proprioception does not occur for 15 to 20% of the population, it is not the universal trigger for excessive loading.

Over my years in clinical practice, I have learned there is nothing I can do that is 100% dependable to stop a patient from para-functioning. Some of my patients continue to excessively load after posterior contacts are removed. Their functional risk does not diminish.

If we cannot reduce elevator force and redistribute force enough on an occlusal appliance to eliminate or at least relieve TMD symptoms, then occlusal therapy via ortho, equilibration, or restorative will not satisfactorily help the patient. We will need to turn to other forms of therapy.

Other modalities I use are BOTOX to deactivate muscles, massage therapy, and physical therapy. There are also systemic medications, cold lasers, and TENS therapy we can use to reduce the activity of the muscles or reduce inflammation in the muscles and joints. Sometimes one modality will alleviate symptoms for a while and when symptoms return, we can try it again or try another modality.

An Exercise to Identify the Patients Who May Not Benefit from Occlusal Therapy

You can do what I call a poor man’s EMG on yourself by placing your hands on your masseter muscles. Put your back teeth together, clench and release, clench and release, clench and release to see how much masseter activity you have. Then move your teeth into protrusive edge to edge and try to clench a little bit, making sure your back teeth do not touch. If you now have a posterior tooth touching in the edge-to-edge position, then put a pencil or pen between your front teeth to separate your back teeth.

With no back teeth touching and contact on the centrals, try to clench and release two or three times while feeling your masseters. Most of you will find your masseters do not move or move a lot less when no back teeth are touching. Some of you, even with your back teeth separated, can still clench in protrusive and can still increase the muscle activity almost the same amount as when your back teeth touch.

I do this exercise with my patients, but when they move into protrusive, I put a bite stop over their front teeth or have them bite on a Lucia jig we have lined for their bite registration. If you do this test with your patients, you can use an EMG or feel the muscle activity with your hands.

If the patient can still generate almost the same force or the same force with their back teeth separated, you have identified one of the around 15% of people who might not benefit significantly from occlusal therapy. You’ve also identified someone who might not do well on an anterior-only appliance because, if they can generate that same force on just two teeth, they are at risk for those teeth becoming sore and moving.

Interested in Learning More?

The Pankey Institute Essentials courses and multiple focus courses include hands-on exercises and over-the-shoulder training designed to help dentists develop mastery in reducing functional risk and treating TMD symptoms.