Background Tissue expansion of oral mucosa prior to ridge augmentation promises to reduce the soft tissue exposure and improve the final intraoral bone graft density and volume. This study explored a novel, shapeable hydrogel tissue expander (HTE) in intraoral sites that had undergone previous expansion and surgery.

Methods Nine beagle dogs had all premolar teeth extracted with alveolar bone reduction. At least 3 months healing followed before placing the hydrogels at 4 sites for each dog: maxilla and mandible, right and left. After 6 weeks of expansion, the expanded hydrogels were removed and measured for volume expansion and hydrogel condition. Punch biopsies were taken of the expanded oral mucosa. After healing of 3 months a second insertion of hydrogels was done at the same sites. Again, volume and hydrogel condition were recorded. Three dogs received ultrasound imaging of the expanding hydrogels upon the second insertion. Necropsy specimens were taken of both expanded and non‐expanded oral mucosa.

Results Blood flow returned to that observed before insertion within two weeks after HTE insertion in both first and second insertions. First insertion resulted in linear gain of 8.13 mm, and second insertion showed a linear gain of 6.44 mm of oral mucosa. First and second insertion erupted at approximately 3% and 4% of the sites, respectively. There was no directional migration of the expanding hydrogels. Histology indicated little inflammatory reaction to any hydrogel implant.

Conclusion Oral mucosa can be consistently and successfully expanded prior to bone graft for ridge augmentation even at sites with a history of prior surgeries.