In a recent "Just Ask" session, Dr. Nicole Winitsky, a periodontist and prosthodontist, shared her insightful research on the phenomenon of infraposition in single anterior implants. The session, hosted by Stefan, covered various facets of this issue, including its causes, implications, and possible predictive factors.
Nicole, who recently completed her PhD, presented a case study of a patient, Johanna, who received single anterior implants after losing her upper laterals. Over time, Johanna's implants showed signs of infraposition—where the implant becomes positioned lower than the adjacent teeth. This common issue arises because while teeth continue to erupt as facial growth progresses, implants, anchored in bone, lack the mobility to adapt in the same way, leading to positioning changes.
Through her 17-year follow-up study on 42 patients, Nicole found that all implants eventually show some degree of infraposition. The most significant changes occurred in the lower anterior region of the maxilla, with lateral and canine implants exhibiting more pronounced movement compared to central incisors. Despite these changes, many patients rated the aesthetics of their implants highly, showing that infraposition, though noticeable in some cases, often does not concern patients as much as it does practitioners.
Nicole’s research suggests that while infraposition is inevitable in most cases, predicting the extent of this shift remains challenging. Factors like facial type, the vertical height of the anterior face, and age seem to influence the degree of movement, but current knowledge is not sufficient to predict individual outcomes with high accuracy. Her study revealed that less tooth movement occurred in patients with lower anterior facial height, highlighting the importance of this measurement for predicting infraposition risks.
In conclusion, Nicole emphasized the importance of informing patients about the potential for long-term changes in implant position, particularly for younger patients. While future research may provide more definitive predictive tools, the current recommendation is to use screw-retained crowns for easier adjustments in the future. Despite the inevitable infraposition, single anterior implants continue to show high survival rates, making them a reliable treatment option for young adults.