Abstract

Statement of problem: The most common mechanical complication reported regarding the implant abutment is screw loosening attributed to masticatory forces and insufficient preload torque.

Purpose: The purpose of this study is to evaluate the differences in reverse torque value between UCLA abutments with no casting performed, UCLA abutments cast using a conventional manner, and UCLA abutment cast using protection caps and pegs.

Material and methods: Thirty implants with a standard diameter (4.3 mm) conical connection (NobelReplace Tapered Groovy 4.3 × 13 mm; Nobel Biocare) and thirty premachined 4.3 mm gold UCLA abutments (Branemark System™ Nobel Biocare, Inc) were used in this study. Samples were divided into 3 groups (n=10 per group). Group A represented the control group with no casting of the abutments done, Group B abutments with no protection caps or pegs were cast and air particle abraded, and Group C abutments were cast and then air particle abraded using protection caps and pegs made of milled Zirconia (Zi). Twenty samples were cast in noble metal alloy using an induction casting machine. Samples in Groups (B and C) were cast and then air particle abraded with aluminum oxide 50 μm at 100 psi for 25 seconds. All samples were torqued at 35 Ncm using a digital torque device. After 10 minutes, all screws were retightened at 35 Ncm. After 3 hours, each screw was loosened and the value at which loosening occurred documented as the Reverse Torque Value (RTV).

Results: Among tested groups the mean value of the reverse torque ranged from 19.89 Ncm to 27.19 Ncm. Mean RTVs were 27.19 Ncm, 19.89 Ncm, and 24.24 Ncm for Groups A, B and C respectively. A significant difference was found in RTVs among the tested groups (P< .05).

Conclusion: Significant difference was found in RTVs among all tested groups. Among cast groups, Group C which used protection caps and pegs for casting revealed significantly lower loss of the torque value.

LLU Discipline

Prosthodontics

Department

Prosthodontics

School

School of Dentistry

First Advisor

Mathew T. Kattadiyil

Second Advisor

Chandur Wadhwani

Third Advisor

E. Ricardo Schwedhelm

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2022

Date (Title Page)

3-2022

Language

English

Library of Congress/MESH Subject Headings

Dental Implant-Abutment Design; Torque

Type

Thesis

Page Count

xi, 31 p.

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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