Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

Department

College of Dental Medicine

First Advisor

Joshi Ratnakar Niranjan

Date of original Performance / Presentation

January 2023

Publication Date / Copyright Date

1-1-2023

Abstract

Objective: The objective of this retrospective study was to compare straight versus angled screw channel systems using CBCT scans taken in PG clinics at Nova Southeastern University from 2017-2023. The study will determine the prevalence of a screw-retained restoration when planning immediate implants following established guidelines by tooth type in the anterior maxilla. Background: Immediate implant placement in the esthetic zone is technique-sensitive and requires careful assessment of factors such as surgical technique, anatomic considerations, and prosthetic planning. This is critical to ensure immediate implant placement in the correct three-dimensional (3D) position with an intact facial bone wall to obtain ideal, predictable, and stable esthetic outcomes. The use of cone beam computed tomography (CBCT) is the gold standard for providing three dimensional (3D) images for planning dental implants. The aim of the study is to assess the possibility of screw-retained implant restoration comparing straight versus angled screw channel systems in the anterior maxilla while planning immediate implant using CBCT scans on an implant planning software. Methods: The CBCT scans of patients who were treated at the Postgraduate dental clinics at Nova Southeastern University from 2017-2023 were selected upon IRB (Institutional Review Board) approval, and CBCT scans were imported in implant planning software for planning Astra EV implants in the anterior maxilla using straight access and angled screw channel abutments. This was done using a template (Figure.1) on the implant planning software to measure the angulation needed to achieve a screw- retained restoration for each tooth type. The angulation was incrementally increased from 5 degrees to 25 degrees until the access channel exited palatally and with 2 mm distance from the incisal edge. All the abutments planned within this range were deemed restorable with an angled screw channel. If a 25-degree angled abutment is still exiting facial to the incisal edge or not 2 mm palatal to it, then they will be deemed restorable with a cement retained restoration. The prevalence of each restoration type was then compared among the tooth types with straight and angle abutments by using Fishers’ Exact test. Results of Fisher’s Exact test showed statistical significance by angulation and tooth type. Results: A total of 100 CBCT scans were evaluated that involved 295 sites in the anterior maxilla. The average age was 56.4 (+/- 12.9) and 57.6% (N = 170) were female in the sample. The results demonstrated that the greatest percentage of screw-retained restorations with straight abutments were found at canine sites (51%) and the least percentage at lateral sites (5.1%). There was a significant increase in screw retained restorations on using angled screw channel systems (p<0.01) for each tooth type. The lateral incisor was the tooth that required the most significant angle correction among the anterior teeth. The most frequently required angle abutment was 10 degrees that allowed a significant increase (p<0.01) in screw-retained restorations (18.6%) within the sample. Conclusion: The study showed that the angled screw channel systems significantly (p<0.01) increased the prevalence of a screw retained restorations in the anterior maxilla. Lateral incisors required the greatest amount of angle correction within the group (75.5%).

Disciplines

Dentistry

Keywords

Angled Screw Channel; CBCT; Cement-retained; Immediate implant; Maxilla; Screw-retained

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