Treatment of Super-Eruption Secondary to Anterior Wear
Considerations for crown lengthening versus orthodontic intrusion
Salvatore Lotardo, DDS, AAACD
With the prevalence of bruxism and erosion, management of super-eruption secondary to anterior wear has become a more common challenge. As demand grows for comprehensive and cosmetic solutions for these cases, clinicians are faced with complex treatment decisions. It is often the esthetic issues that drive the patient to seek care, making esthetics essential for the success of the case.
A successful outcome is predicated on identifying the etiology of the current condition and understanding the factors influencing the long-term predictability of treatment. A comprehensive approach and sound occlusal strategy are paramount. Once the clinician has determined a course of treatment, a plan for handling the esthetic challenges in the smile zone, including short teeth, excessive gingival display, and uneven gingival margins, must be developed.
The diagnosis of super-eruption secondary to anterior wear needs to be established, ruling out other conditions such as altered passive eruption, which could have different treatment modalities. There are several options in cases where the occlusion and posterior teeth have been addressed, or when the clinician is treating anterior teeth in an otherwise functional, low-risk occlusion and not substantially changing the present occlusion via increasing vertical dimension or anteroposterior relations. These options include crown lengthening, orthodontic intrusion, or a combination of both—each of which may also include various restorative combination procedures as well.
When upper anterior teeth are worn, any of the following may occur: (1) upper teeth super-erupt; (2) lower teeth super-erupt; (3) both upper and lower teeth super-erupt; or (4) something—tongue thrust or habit—prevents the worn teeth from erupting. When the upper teeth super-erupt, the worn teeth and the periodontium move incisally together, creating a lower gingival margin for those teeth.1 The initial goal is to first determine the desired incisal edge position, followed by the incisal length. This is accomplished following principles of smile design, many of which use the maxillary incisal edge position as the starting point. Once incisal edge position and central incisor length are determined, the corrected gingival margin follows suit, as set by the latter. To clinically establish the corrected gingival height, there are factors to consider that will allow for the least invasive and most effective treatment.
Considerations for Treatment Selection
The following are the findings and their implications for treatment. Each finding tends to favor either crown lengthening or orthodontic intrusion. Consideration of these factors will help to formulate the best treatment plan decision.
Presence of Misaligned Teeth or General Malocclusions
Correction of other orthodontic issues as an additional benefit to the treatment of super-erupted teeth will improve overall outcomes and be an additional motivational factor for patient acceptance. In restorative cases, orthodontic correction leads to more conservative preparations. Therefore, in these cases, intrusion is favored over crown lengthening. Of note is the risk of black triangles after orthodontic treatment, especially on rotated or crossed anterior teeth in adult patients.2 Patients need to be made aware of this risk, and the need for additional treatment should be a factor. If the plan is to intrude crossed incisors, the starting position of the papilla—and hence the new contact point—may need to be adjusted to eliminate the black triangle.
Crown-to-root ratios of less than 1:1 are considered by some to be a contraindication for use in crown-and-bridge treatment.3,4 If similar guidelines are used and less favorable crown-to-root ratios preclude crown lengthening, orthodontic intrusion may be the only option for repositioning gingival margins.
Restorative Treatment Needs
If restorations are needed for esthetic, caries, or structural purposes, the next decision will be the type of restorations required. For porcelain veneers, crown lengthening may mean cervical margins don’t end on enamel, resulting in a higher prevalence of marginal leakage and poorer bond strengths, whereas intrusion moves the cementoenamel junction (CEJ) apically and preserves the porcelain-to-enamel bond cervically.5,6 Full-coverage restorations, if planned, may require circumferential osseous crown lengthening, which is a more invasive procedure than that required for facial gingival repositioning only. If the remaining amount of tooth structure left after intrusion will be insufficient to retain a restoration, crown lengthening would be indicated.
Elimination of pockets and establishment of gingival health with periodontal therapy alone may result in the desired marginal position, negating the need for crown lengthening. Periodontal surgery to normalize the pocket and obtain optimal health prior to restorative treatment also allows for more predictable gingival margin stability after restorative insertion.7 Orthodontic treatment should not be started on patients with active periodontal disease. Once the periodontal health is established, orthodontic treatment can be done if gingival discrepancies persist beyond the periodontal therapy.8