The effect of residual craniofacial growth on implants placed in the anterior maxilla – A long-term cephalometric study

Background

The cessation of adolescent growth represents the earliest appropriate time for dental implant placement. This is in order to avoid subsequent submersion of implants relative to adjacent erupting teeth. Still, skeletal growth continues well into adulthood. While more moderate than adolescent growth, residual craniofacial growth can still have clinical relevance. Notably, it could lead to changes in implant axes. In turn, these could result in esthetic or prosthetic complications.

Aim/Hypothesis

To assess the effect of residual craniofacial growth on the orofacial axes of implants in the anterior maxilla.

Material and Methods

We conducted a long-term prospective cephalometric study on adult patients that received at least one dental implant in the anterior maxilla. Patients that underwent extensive orthodontic treatment and or orthognathic surgery were excluded from the study. Using one baseline cephalogram taken directly postoperatively and one taken at follow-up at least 5 years after, we determined differences in orofacial implant angles. The implant angle was defined as the plane angle enclosed by the Sella-Nasion line and the implant axis. The Sella-Nasion line was chosen for its stability as previously described by Wei and Sarhan. Cephalograms were measured by a researcher who had been calibrated by blindly evaluating a randomized training subset of 20 baseline cephalograms twice (ICC = 0.95).

Results

Preliminary data from the first 10 patients enrolled (mean age- 33.9 ± 9.2 years, 50% female) is herein presented. The data show a counterclockwise rotation in 80% of implants by an average of 2.0 ± 1.4 degrees as well as a clockwise rotation in 20% of implants by an average of 1.5 ± 0.7 degrees compared with the baseline. There is a tendency toward greater absolute differences in women (2.2 ± 1.8 degrees) than in men (1.6 ± 0.5 degrees). Further, patients under 30 show tend to show greater absolute differences (2.2 ± 1.6 degrees) than people at least 30 years old (1.6 ± 0.9 degrees). Consequently, the greatest absolute differences are found in women under 30 (2.3 ± 2.3 degrees).

Conclusion and Clinical Implications

Our initial findings point to a modest change in the orofacial axes of implants in the anterior maxilla over time, suggesting a possible effect of residual growth. If large enough, a counterclockwise tilt could present itself in a similar way to Angle's Class II division 1 malocclusion. Considering the esthetic importance of the anterior maxilla, the possible long-term effect of residual growth might be a factor during surgical planning, especially in younger women.