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Impact of Laser Modified Abutment Topography on the Junctional Epithelium Integration

thesis
posted on 01.08.2021, 00:00 by Tyler G Haradon
Purpose: To compare, by gene profiling analysis, the molecular changes in peri-implant mucosa which forms adjacent to an implant with the standard healing abutment versus peri-implant mucosa adjacent to an implant with the Laser-Lok® microchannel abutment at 4week and 8 weeks (healed) timepoints. Materials and Methods: A total of 22 implants in 11 healthy subjects requiring 2 single tooth implants in two separate quadrants of the mouth were enrolled in an IRB approved clinical study. Implants were placed according to the manufacturer’s guided surgery protocol. Peri-implant mucosa was biopsied at abutments at 4 weeks (n =7) and 8 weeks (n=4). One participant dropped out prior to biopsy. A thin 0.25 mm circumferential cuff of mucosa with depth of 2 – 4 mm (in accordance with subject’s mucosal thickness) adjacent to the implant abutment was removed,cut in half, where one half was placed in 4% paraformaldehyde for histologic analysis and the other half placed into RNAlaterTM for molecular analysis by Reverse Transcription polymerase chain reaction. Following biopsy, new healing abutments were placed and connected, matching the same topography and dimension of the abutment removed for biopsy. Real time PCR measurement of Laminin-5, ODAM, FDCSP, and Col1 expression in excised tissues adjacent to healing abutments was compared between machined and Laser-Lok® surface abutments. Laminin-5 protein expression was determined by western blotting of protein extracts from tissues used for PCR analysis. H&E staining of paraffin embedded tissue sections was used demonstrate the anatomy of the biopsied peri-implant mucosa, while the expression of ODAM and FSC-SP were evaluated in the biopsied human peri-implant mucosa through immunohistochemistry at machined and Laser-Lok® abutments. Results: The expression of mRNAs encoding ODAM, FDC-SP and Laminin-5 were further shown to be increased in peri-implant tissues formed adjacent to Laser-Lok® versus machined abutments. Real time PCR measurement of Laminin-5, ODAM, FDCSP, and Col1 expression from 4-week biopsies demonstrated the elevated abundance of laminin-5, ODAM, and FDCSP mRNA levels in 4 of 6 participants. The tissues from healed (8 week) biopsies demonstrated a reduction in these mRNAs in 3 of 4 participants. Collagen I expression was similar at both machined ant Laser-Lok® abutments. ODAM and FDC-SP proteins were identified by immunohistochemistry in the peri-implant mucosa and junctional epithelium at implant abutments in humans. Overall Laminin-5 protein expression was greater in the peri-implant tissues formed adjacent to Laser-Lok® versus machined abutments. Histological evaluation indicated tearing of the sulcular epithelium at Laser-Lok® abutment sections, suggesting greater attachment at these abutments prior to biopsy. Conclusion: The alteration of junctional epithelium protein expression is associated with altered implant abutment topography. At both the machined and Laser-Lok® abutments, the formation of the junctional epithelium involves the mRNA and protein expression of proteins to junctional epithelium-specific proteins, ODAM and FDC-SP. We speculate this may be linked to barrier function. The role of the epithelial components of the biologic width at implants requires further investigation with respect to the maintenance of implant health

History

Advisor

Cooper, Lyndon

Chair

Cooper, Lyndon

Department

Periodontics

Degree Grantor

University of Illinois at Chicago

Degree Level

Masters

Degree name

MS, Master of Science

Committee Member

Thalji, Ghadeer Luan, Kevin

Submitted date

August 2021

Thesis type

application/pdf

Language

en