Submucosal implantation of soft tissue expanders does not affect microcirculation.

Aim: To investigate the effect of submucosal implantation of self-filling osmotic tissue expanders on mucosal microcirculation. Material and methods: In ten beagle dogs, all premolars were extracted on both sides of the mandible. Tooth-supporting bone and excess soft tissue were removed to mimic a severely resorbed edentulous ridge. Six weeks later, tissue expanders with 0.7 ml final volume were implanted into a submucosal pouch at randomly selected test sites, while contralateral sites served as untreated controls. Microcirculation was assessed in perfusion units (PU) before surgery, after local anaesthesia, directly after surgery, and after 1 and 3 days, using Laser Doppler flowmetry. Results: Local anaesthesia caused a significant decrease of blood flow from baseline (zero) to 6.4 PU (median; Q1 10.5; Q3 0.9; P = 0.006); however, no additional significant decrease was recorded after completion of surgery. Blood flow showed significant increases to 3.6 PU (median; Q1 11.3, Q3 2.1; P = 0.02) and 4.0 PU (median; Q1 9.2, Q3 1.1; P = 0.013) after 1 and 3 days, respectively, when compared to the measurements obtained after application of local anaesthesia and completion of surgery. Blood flow had returned to unimpaired baseline levels 1 day after surgery (P > 0.05). Conclusions: Submucosal implantation of self-filling osmotic tissue expanders results in only momentary disturbance of microcirculation. The minor impairment of perfusion may explain the consistently good outcomes of submucosal implantation of these tissue expanders. Application of local anaesthesia and elevation of a mucoperiosteal flap disturb perfusion and induce ischaemia of the operated tissue (McLean et al. 1995). Reduction in blood supply and ischaemia–reperfusion injury at the subsequent hyperaemic vascular response may affect the operated tissue and may cause complications such as necrosis of the flap, while the severity of tissue damage relates to the duration and the extent of ischaemia (Morris et al. 1993; Carroll & Esclamado 2000). These effects from surgical trauma may impair wound healing after implantation of biomaterials or grafts and have been considered as common reasons for