Histological Study on the Change of Grafted Bone and Sinus Membrane after Sinus Lift Procedure with Dental Implant in Frontal Sinus of Dog

Abstract

Purpose: Oral implant therapy is very useful for the reconstruction of occlusal function. Especially, sinus lift is an important and standard surgical procedure for proper implant installation in cases of insufficient vertical ridge bone dimension, such in posterior edentulous maxilla. The aim of this study was to investigate the change of grafted bone tissue surrounding placed implants in frontal sinuses of adult dogs.
Materials and Methods: Four adult male dogs were used for this experiment. Autogenous bone blocks from the iliac crest were used as grafting materials, and then filled in 8 sides of the frontal sinuses in 4 dogs. Implants were placed immediately or four weeks after bone grafting.
The selected observation periods were 2, 4, 8, and 12 weeks after installation, whereupon the animals were sacrificed. The animals were divided into immediate installation models and delayed installation models,and we conducted a serial comparative study. All surgical procedures were carried out by the same surgeon.
Results: New bone formation was observed in the border between basal bone and grafted bone under the sinus membrane at 2 weeks after bone grafting. Serial grafted bone volumes were gradually reduced in the sinuses. The amounts of bone resorption surrounding placed implants in immediate installation models were greater than those in delayed installation models.
Early after sinus lift, tissue atrophy was observed in the sinus membranes and goblet cells ware lacking, however, the membranes gradually recovered until 8 weeks.
Conclusion: The results indicated that delayed installation yielded greater implant stability than immediate installation. The sinus membrane atrophied due to the surgical stimulation until 4 weeks, but gradually recovered in histological observation.