2-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 expe riment was performed in 75 growing cats assigned to 5 groups. In 31 ca ts, a midline defect was made, and bipedicled flaps were raised at the age of 8 weeks (simulated Langenbeck operation) in order to create pa latal scars. At the age of 14 weeks, custom-made tissue expanders were inserted palatally in 61 animals. Tissue expansion was performed by w eekly inflation in 33 cats (16 without and 17 with scars) for an 8-wee k period. The remaining 28 cats (14 without and 14 with scars) served as sham groups. A control group was formed by 14 animals (without scar s and without tissue expanders). Soft-tissue gain and its effects on m axillofacial growth and development were measured in the midsagittal p lane on tracings from standardized lateral radiographs. The effects of the experimental interventions were evaluated for 8 weeks after remov al of the tissue expanders. Not all the cats yielded results at all ti me periods. This study showed that soft-tissue expansion of palatal mu coperiosteum is feasible. The surgically induced scars did not cause s ignificant differences between the different groups in the midsagittal plane, and the data from both expansion and sham groups could be pool ed. Significant soft-tissue gain was achieved by the tissue-expansion technique. Iatrogenic side effects were significant anteroposterior gr owth retardation at the level of the bony palate and an increase in ve rtical growth of the anterior nasomaxillary height and the posterior s kull height during active tissue expansion. After removal of the tissu e 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-ti ssue expansion is possible in growing cats. This technique, however, i mpaired maxillofacial growth and development.