Three-Dimensional Hard and Soft Tissue Healing at Implants With A Modified Neck Design: An In Vivo Preclinical Study

To evaluate the three-dimensional hard and soft tissue healing around a modified dental implant presenting a tissue level connection and a convergent transmucosal neck (test), compared with a conventional bone level implant (control).

Sixteen test and 16 control implants were placed in 8 experimental animals, following a random allocation sequence. Peri-implant bone volume and surface, 360° bone to implant contact (360-BIC), peri-implant soft tissue volume, and buccal and lingual peri-implant soft tissue thickness, were evaluated through Micro-CT and digital volumetric analysis at 4 and 12 weeks of healing.

In the most coronal mm of the implant surface apical to the implant platform, both at 4 and 12 weeks, 360-BIC was higher at test implants. At 4 weeks, it was approximately 4 times higher (+303.26%; ∆ = 39.83%; p = 0.05) and at 12 weeks, 2.50 times higher (+151.8%; ∆ = 43.23%; p = 0.03). In the same area of interest, a statistically non-significant trend towards a higher 360° peri-implant bone volume was also observed in the test group, both at 4 weeks (+ 272.72%; ∆ = 8.70 mm³; p = 0.07) and 12 weeks (+ 154.54%; ∆ = 8.32 mm³; p = 0.09), being statistically significant only for the lingual bone volume at 4 weeks (+246.47%; ∆ = 5.94 mm³; p = 0.02). No significant differences were observed when comparing the soft tissue volumes and thicknesses among the two groups.

Test implants demonstrate superior 360-BIC and bone volumes around the most coronal implant surface, below the implant platform, while no relevant differences in soft tissue volumes and thickness were observed.