Two-dimensional cephalometric analysis of the effects of subperiosteal palatal soft-tissue expansion in growing cats.

The feasibility and possible effects of palatal soft-tissue expansion in palatal repair were studied. A prospective longitudinal animal experiment was performed in 75 growing cats assigned to 5 groups. In 31 cats, a midline defect was made, and bipediced flaps were raised at the age of 8 weeks (stimulated Langenbeck operation) in order to create palatal scars. At the age of 14 weeks, custom-made tissue expanders were inserted palatally in 61 animals. Tissue expansion was performed by weekly inflation in 33 cats (16 without and 17 with scars) for an 8-week period. The remaining 28 cats (14 without and 14 with scars) served as sham groups. A control group was formed by 14 animals (without scars and without tissue expanders). Soft-tissue gain and its effects on maxillofacial growth and development were measured in the midsagittal plane on tracings from standardized lateral radiographs. The effects of the experimental interventions were evaluated for 8 weeks after removal of the tissue expanders. Not all the cats yielded results at all time periods. This study showed that soft-tissue expansion of palatal mucoperiosteum is feasible. The surgically induced scars did not cause significant differences between the different groups in the midsagittal plane, and the data from both expansion and sham groups could be pooled. Significant soft-tissue gain was achieved by the tissue-expansion technique. Iatrogenic side effects were significant anteroposterior growth retardation at the level of the bony palate and an increase in vertical growth of the anterior nasomaxillary height and the posterior skull height during active tissue expansion. After removal of the tissue expanders, some accelerated growth was found in the tissue expansion in the scarred tissue group, with initial correction of the abnormal growth at the cranial base level. It is concluded that palatal soft-tissue expansion is possible in growing cats. This technique, however, impaired maxillofacial growth and development.