Treatment of a patient with trans-canine placement of a dental implant

Drs. Douglas D. Wright and William T. Goodwin II treat a patient with multiple restorative challenges

The use of dental implants to replace missing teeth is causing a revolution in dental care. A dental student or dental resident in the 1970s learned about “new” techniques such as transmandibular staple-type implants¹ or subperiosteal implants² to support a removable overdenture (Figures 13A and 13B). These were invasive treatments that were confined to specialist’s practice. These early implant patients only enjoyed a moderate increase in comfort and function. This was a poor outcome for the time and expense involved.

These early techniques have been replaced by conventional periosteal implants or even mini dental implants. The more modern techniques can be provided by general dentists after some additional training. The reduction in cost and inconvenience opens dental implant treatment to an increasing number of patients.

A look at current trends provides additional insight. The American College of Prosthodontics website states 36 million Americans are completely edentulous; 120 million Americans are missing a single tooth, and 2.3 million single implant/tooth restorations were provided in 2019.¹

Steady improvements in the science of implant dentistry have led to increased predictability of treatment with less invasive techniques. Improvements in implant dentistry, with the concurrent simplification in treatment techniques, have led to an explosion in the number of patients who desire restorations supported by dental implants. With this expectation of care from a growing number of qualified patients, some unique restorative challenges are being faced by dental professionals.

Some of the challenges a clinician faces can be studied in isolation on a case-by-case basis. For example, the decision whether to place a dental implant immediately after dental extraction or to wait until the extraction site heals is a narrow question that is relatively easy to study in a controlled clinical trial.

However in the day-to-day clinical practice, providers are often faced with multiple challenges in the same patient.

This is the presentation of the restoration of a 78-year-old male with multiple complicating factors.

Mr. Z has a skeletal Class III malocclusion. He has never received orthodontic treatment. The CBCT shows tooth No. 6 is present but horizontally impacted (Figure 4).

Based on age of patient, health history, and presence of the impacted canine, the patient was sent to an oral surgeon for evaluation. The initial consultation asked the surgeon to consider removal of impacted tooth No. 6 and placement of bone graft as a prelude to restoring site 2-7 with an implant-supported fixed bridge (Figures 5 and 6).

Close inspection of the CBCT shows tooth No. 6 is ankylosed. The oral surgeon indicated extraction of tooth No. 6 would require block resection of bone with the tooth. The resulting defect would have required extensive bone grafting and added time and cost to this case.

Maxillary canines are the second most common tooth to be impacted in the oral cavity. Some studies indicate 4 patients in 1,000 have impacted canines.

Orthodontic care often includes managing impacted canines with the help of an oral surgeon and guided eruption.⁴

Unfortunately, not all impacted canines are treated using modern orthodontic techniques. Many patients with impacted canine teeth go through life without having the canines removed or moved into the dental arch. Over several decades, impacted canines can become ankylosed thus becoming extremely difficult teeth to extract.

When the need for a dental implant in the anterior maxilla arises, these impacted/ankylosed canines pose a unique challenge. In this case, removal of the ankylosed and impacted canine with a block resection leads to removal of bone where it is most needed.

Recent reports indicate dental implants can be placed directly through the impacted canine, eliminating the need for block resection and bone grafting.^4,5

Histologically, trans-canine placement of a dental implant has similarities with the socket shield technique for preserving buccal contour when placing a dental implant in an area of limited buccal bone. Miltiadis demonstrated buccal bone growth 5 years after a dental implant was placed using the socket shield technique.⁶ In a recent review of this technique Ogawa⁷ presents over 283 cases of successful socket shield technique from the dental literature.

On the day of surgery, the patient had MegaGen AnyRidge^® implants placed at the following sites under local anesthesia:

• Tooth No. 7: trans-canine placement of 4.0 mm x 13 mm
• Tooth No. 3: 5.0 mm x 7.0 mm with small crestal approach sinus graft
• Tooth No. 13: 4.0 mm x 10.0 mm implant

Retaining tooth No. 6 and placing the dental implant through the impacted and ankylosed tooth provided a new set of challenges. Keeping the ankylosed canine in place reduced the need for additional surgery; however, with the retention of the canine, insufficient interarch space would be available for a zirconia or resin-composite restoration. Because the interarch space was limited, a porcelain-fused-to-metal restoration was used to complete the case.

To prevent isolated forces being placed on the new implant-retained fixed bridge, modified anterior and “canine” guidance was achieved by allowing the already established guidance between tooth Nos. 9 and 22 when the mandible moved to the patient’s right. The new bridge had occlusal forces balanced to the guidance provided by the contact in function between tooth Nos. 9 and 22 (Figure 1).

Restorative dentists often come up against multiple restorative challenges in a single patient. There are few reports of treating cases such as this with multiple challenges. Each individual restorative challenge can be reviewed in dental literature. Creative solutions can be offered to the patient based on clinical research, case reports, and well-established clinical practices (Figures 2, 3, 7, and 8).

In the 1970s and early 1980s, the surgery was extensive, painful, and the failure of these modalities was catastrophic for the patient. Photos like Figures 13A and 13B remind us how far the science and technology of implant treatment has come in a brief period. The best we can do for our patients is to put their interests first, offer clear choices, and provide evidence-based dental treatment (Figure 14).