Effects of thread design on soft and hard tissue healing around implants in lipopolysaccharide-induced peri-implantitis-like lesions in rat maxillae

Abstract

Objectives

This study investigated the effects of thread design on the soft and hard tissues around implants in rat maxillary peri-implantitis-like lesions.

Methods

Fourteen, 9-week-old, female Wistar rats were used in this study. Two types of grade IV titanium tissue-level implants with a standard V-shape and buttress threads were prepared (control and test implants, respectively). The control and test implants were randomly placed into healed left or right sides four weeks after first molar extraction. Daily administration of lipopolysaccharide (LPS) into the peri-implant mucosal sulcus was performed in combination with Freund's incomplete and complete adjuvants. The maxillae were harvested 16 days after LPS administration for quantitative and qualitative analyses.

Results

LPS administration induced significant marginal bone loss, with increases in osteoclasts and polymorphonuclear cells around control implants. LPS administration did not change cell numbers around nor alter bone quality inside the buttress threads of the test implants, but resulted in a significant deterioration of bone quality, defined as the preferential alignment of collagen fibers inside the V-shaped threads of the control implant. LPS administration also significantly increased calprotectin production in the epithelium around the test implants and significantly increased calprotectin production in the connective tissue around both the control and test implants.

Conclusions

Buttress threads at specific angles provided resistance to LPS-induced inflammation in rats with LPS-induced peri-implantitis-like lesions. The upregulated production of calprotectin induced by LPS administration in the epithelium and connective tissues around the test implants may facilitate inflammation control around implants.