Deep overbites are a common condition in patients with lingual wear of their maxillary incisors and facial wear of the mandibular incisors. The deep overbite can occur from three different etiologies.
First, as the teeth wear, the maxillary anteriors may erupt, deepening the overbite with no change in vertical dimension.
Second, the mandibular anteriors may erupt with the same outcome.
Third, the patient may have had minimal eruption of the anterior teeth but a loss of vertical dimension as the tooth wear progressed; however, this patient must show wear on the posterior teeth or loss of the posterior teeth for the vertical dimension to have changed.
Patients who display this pattern of wear and a deep overbite from any of the three causes will also have extremely thin teeth that are still in occlusion. This makes restoration next to impossible because any tooth preparation to create space results in the removal of almost all the tooth structure. If this condition isn’t corrected, the teeth will undoubtedly keep wearing away.
In order to deliver the most effective and conservative treatment, you must evaluate whether the maxillary or mandibular incisors may have erupted secondary to the wear. In this case, orthodontic intrusion or crown lengthening should be performed, which will create the space to restore the teeth.
If it appears the anterior position is correct, then opening the vertical dimension may be necessary to gain the needed space.
So, how do you know which correction needs to be performed? Follow these steps:
Step 1: Upper incisal edge position
When examining a patient, look at the teeth relative to their face – this will tell you if the incisal edge needs to be lengthened or shortened. This position is the starting point for the treatment plan.
Step 2: Upper incisor inclination
Often in this type of wear patient with a deep overbite, the maxillary anterior teeth are retroclined and will need to be orthodontically proclined, not just intruded. If the teeth are retroclined, intrusion is almost always a better choice than crown lengthening to correct any secondary eruption.
Step 3: Gingival levels
Want to know how much the teeth have erupted? Looking at the patient's gingiva is a great guide to how much eruption has occurred.
From your ideal incisal edge position, calculate where the gingiva should be to give you a pleasing tooth length and compare it to where the gingiva is. If the position is the same, minimal (if any) eruption probably occurred. If the correct tooth length from your incisal edge position requires the gingiva be moved several millimeters apically, then eruption has likely occurred.
Step 4: Lower incisor position
Evaluate the incisal edge position of the lower incisors relative to the face and the posterior occlusal plane. If the incisal edge position looks good, or is too far coronal, but the overall tooth length is short, the lower incisors have likely erupted. This step is essential in establishing whether the lower anterior teeth will need to be intruded or crown lengthened to solve the restorative dilemma.
Frank Spear, D.D.S., M.S.D., is co-founder of Spear Education and a member of Spear Resident Faculty.