The Effects of the Nd:YAG Laser on in Vitro Fibroblast Attachment to Endotoxin‐Treated Root Surfaces

The purpose of this studywas to evaluate the effects of the NdrYAG laser on in vitro fibroblast attachment to endotoxin‐treated root surfaces and to describe any laser‐induced cementum surface alterations. Thirty 4 mm × 4 mm cementum segments were obtained from unerupted third molars. The treatment groups were as follows: 1) control, healthy root segment; 2) non‐lased, endotoxin treated; and 3) lased, endotoxin treated. The endotoxin treated roots were soaked in E. coli055:B5 lipopolysaccharide (556 EU/ml) for 72 hours. The lased, endotoxin‐treated root segments were treated with a Nd:YAG laser using a 320 μm contact optic fiber handpiece with an energy setting of 80 mJ at 10 pulses per second for one minute. The root segments were subsequently placed in fibroblast culture dishes for 40 hours and then prepared for scanning electron microscopy (SEM) observation. SEM examination revealed two different types of attachment: flat and round. Flat cells represented firmly attached cells due to well‐defined points of attachment and numerous lamellapodia. Round cells possessed few attachment processes and were, therefore, considered poorly attached. The lased, endotoxin‐treated root segments had significantly decreased numbers of flat fibroblasts versus the control and nonlased, endotoxin‐treated root segments. The absence of flat fibroblasts in the laser treated root segments was a consistent finding. The non‐lased, endotoxin‐treated root segments had significantly increased numbers of round fibroblasts versus the control and lased, endotoxin treated groups. The lased root segments exhibited surface alterations which included charring, crater formation, cementum meltdown, and tracking. The organic matrix appeared to have been burned off leaving behind a resolidified substance with a lava‐like appearance. The results of this in vitro study suggest that the laser alters the biocompatibility of the cementum surface so as to make it unfavorable for fibroblast attachment. Healing studies are necessary to determine if these effects observed in vitro are of clinical importance. J Periodontol 1992; 63:626–632.