Evaluation of Implant Abutment Level Digitalization Techniques: A Clinical Methodological Study
Phase: NA
Conditions: Prosthesis User, Digitalism
Sponsor: Hacettepe University

 
 
 
 
 
 
 
 
 
 
 
 
 
 
STUDY PROTOCOL 
 
Evaluat2on of D2g2tal Impress2on Workﬂows for Cement-Reta2ned 
Implant Abutments:A Methodolog2cal Cl2n2cal Study NCT 
Number: 
Prepared by: 
Ezgi Ünal, DDS, Specialist in Prosthodontics 
Hacettepe University Faculty of Dentistry, Department of Prosthodontics 
 
Supervisor: 
Prof. Dr. Kıvanç Akça 
Hacettepe University Faculty of Dentistry, Department of Prosthodontics 
 
Date: January 28, 2025 

Introduction 
Advancements in digital technologies have significantly transformed diagnostic, 
planning, and treatment processes in dentistry. Digital workflows have redefined the 
procedures for impression-taking, design, and fabrication, offering enhanced 
predictability and clinical efficiency in prosthodontic treatments. Intraoral scanners 
(IOS), which acquire direct data from the oral cavity, have become central to this 
transformation by minimizing material- and operator-related errors commonly 
encountered in analog impression workflows. 
In Dmplant-supported fDxed prosthodontDcs, the accurate and repeatable dDgDtal transfer 
of the three-dDmensDonal (3D) Dmplant posDtDon Ds crDtDcal for clDnDcal success.(1, 2) DDgDtal 
workﬂows typDcally rely on scan bodDes (SBs), whDch serve as DntermedDarDes between the 
Dmplant and the dDgDtal desDgn software. (2)However, Dn clDnDcal scenarDos where the 
Dmplant brand Ds unknown or dDgDtal lDbrarDes are unavaDlable, usDng prefabrDcated cement-
retaDned abutments as dDrect scannDng references may be a necessary alternatDve. 
While multiple in vitro studies have examined the accuracy of various scan body designs 
and materials, clinical-level evidence comparing different digital workflows for scanning 
cement-retained abutments is still limited.(3) Moreover, methodological variables such 
as library dependency and software alignment algorithms may affect measurement 
accuracy.(4) 
In recent literature, direct intraoral scanning has been shown to offer improved efficiency 
and potentially better accuracy compared to indirect methods. (5, 6)Yet, the impact of 
scanning and alignment strategies on the clinical accuracy of digital impressions taken 
at the abutment level remains underexplored. Quantitative assessment of angular 
deviations between virtual implant axes using reverse engineering software provides an 
objective means to evaluate such workflows in clinical settings.(7, 8) 
Objective 
ThDs clDnDcal methodologDcal study aDms to evaluate the precDsDon of Dntraoral scannDng 
workﬂows used for the dDgDtalDzatDon of cement-retaDned Dmplant abutments. Three dDgDtal 
DmpressDon workﬂows were evaluated by comparDng the angular devDatDons between the 
vDrtual axes representDng Dmplant posDtDons, derDved from scan body and abutment scan 
data. 
The null hypothesDs of the study Ds that there Ds no statDstDcally sDgnDfDcant angular 
devDatDon between the datasets obtaDned from Dntraoral and extraoral scannDng of the 
abutments, alDgned vDa the best-fDt alDgnment protocol, and those obtaDned from Dntraoral 
scannDng alone. 
Study Design 
This prospective clinical methodological study was designed in accordance with the 
STARD (Standards for Reporting Diagnostic Accuracy Studies) guidelines to assess the 

precision of digital impression workflows for cement-retained implant abutments. The 
study was conducted at the Department of Prosthodontics, Hacettepe University Faculty 
of Dentistry, and approved by the university’s Ethics Committee (Protocol No: KA-24057). 
Twelve participants requiring two implant-supported fixed restorations in the posterior 
region were enrolled. All participants were adults with completed skeletal growth, and 
had no systemic or local contraindications for implant treatment. Bone-level implants 
(Straumann) were placed in accordance with the SAC classification as “straightforward” 
cases. 
Three different digital workflows were applied to each participant in a single clinical 
session: 
1. SB (Scan Body Group): Intraoral scan of original scan bodies screwed onto 
implants. 
2. IOS (Intraoral Scan Group): Direct intraoral scan of prefabricated cement-
retained abutments. 
3. BFA (Best-Fit Alignment Group): Superimposition of intraoral and extraoral scan 
data of the abutments using best-fit alignment protocol. 
Reverse engineering software was used to analyze angular deviations between the virtual 
axes derived from each workflow. 
Eligibility Criteria 
Inclusion Criteria: 
• 
Adult participants aged 18 years or older who have completed skeletal growth. 
• 
Signed informed consent after being informed about the study procedures. 
• 
Good general and oral health, with no signs of active periodontal disease. 
• 
Partially edentulous in the posterior region with indication for a two-implant-
supported fixed dental prosthesis (2–3 units). 
• 
Presence of fixed dentition in the opposing arch. 
• 
No need for vertical or horizontal prosthetic correction of the interarch 
relationship. 
• 
Presence of bone-level implants placed via straightforward surgery according to 
the SAC classification system, without any advanced surgical techniques. 
Exclusion Criteria: 
• 
Refusal to participate or failure to sign the informed consent form. 
• 
Conditions contraindicating implant therapy (e.g., history of radiation therapy in 
the head and neck region, bone malignancies, severe metabolic disorders). 
• 
Systemic risk factors for implant therapy (e.g., uncontrolled diabetes, 
immunological disorders, chronic steroid use, pregnancy). 
• 
Local risk factors for implant therapy (e.g., bruxism, poor oral hygiene, untreated 
periodontal disease). 

• 
Presence 
of 
temporomandibular 
joint 
disorders 
affecting 
mandibular 
movements. 
Interventions 
InterventionType: Other 
Name: Evaluation of three digital impression workflows for cement-retained implant 
abutments 
Description: 
Each participant underwent three different digital impression workflows for the 
digitalization of cement-retained implant abutments in a single clinical session: 
1. SB (Scan Body Group): Intraoral scanning of original scan bodies (CARES Mono 
Scanbody; Straumann Holding AG) attached to the implants. 
2. IOS (Intraoral Scan Group): Direct intraoral scanning of prefabricated cement-
retained abutments (Bone Level RC/NC Cementable Abutment; Straumann 
Holding AG). 
3. BFA (Best-Fit Alignment Group): Best-fit alignment of intraoral and extraoral 
scan data of the same prefabricated abutments. Extraoral scanning was 
performed by attaching the abutments to implant analogs using a positioning 
holder and scanning them on a stable platform. 
All impressions were acquired using an intraoral scanner (TRIOS 5; 3Shape A/S) with 
image stitching algorithm. Reverse engineering software (Geomagic Design X; 3D 
Systems Inc.) was used to calculate angular deviations between the virtual axes derived 
from each workflow. 
Primary Outcome Measures 
Outcome 
Name: 
Mean angular deviation between digital workflows 
Description: 
The primary outcome is the comparison of mean angular deviations between the virtual 
axes derived from three different digital impression workflows used for the digitalization 
of cement-retained implant abutments. Reverse engineering software (Geomagic Design 
X; 3D Systems Inc.) was used to calculate angular differences between the datasets. The 
scanbody-based intraoral scan (SB group) was defined as the reference dataset for 
alignment and deviation analysis. 
Time 
Frame: 
Following the completion of all digital impressions and their alignment in the reverse 
engineering software. 
Data Collection and Analysis 

Intraoral scans were performed using a wireless scanner (TRIOS 5; 3Shape A/S, 
Copenhagen, Denmark) with confocal microscopy technology. All scans were conducted 
in a controlled clinical environment, and surface data were saved in Standard 
Tessellation Language (STL) format. 
Three different digital workflows were performed on each participant in a single session: 
• 
SB Group: Scan bodies (CARES Mono Scanbody; Straumann Holding AG) were 
screwed onto the implants and scanned intraorally. 
• 
IOS Group: Prefabricated cement-retained abutments (RC/NC Cementable 
Abutment; Straumann Holding AG) were screwed intraorally and scanned directly. 
• 
BFA Group: Extraoral scans of the abutments were obtained by combining them 
with implant analogs. These scans were later aligned with intraoral scans using a 
best-fit alignment protocol in CAD software (exocad DentalCAD; exocad GmbH). 
The datasets were processed and analyzed using reverse engineering software 
(Geomagic Design X, version 2016.1.0; 3D Systems Inc., Rock Hill, SC, USA). For each 
group, the 3D positions of the implants were represented by central axes generated from 
cylindrical or conical geometries of the scanned components. 
Statistical Analysis 
Statistical analysis was performed using IBM SPSS Statistics 26.0. For each digital 
workflow (SB, IOS, BFA), the mean and standard deviation of angular deviations 
measured at different implant positions (mesial/distal) and arch locations 
(maxilla/mandible) were calculated. 
The normality of the data distribution was assessed based on skewness and kurtosis 
values, with a reference range of ±1.96. As the data met the assumption of normal 
distribution, repeated measures ANOVA was used to evaluate differences between 
workflows with respect to jaw location and implant position. To identify which specific 
workflows differed significantly from each other, pairwise comparisons were conducted 
using the Least Significant Difference (LSD) test. 
Additionally, to compare the performance of each workflow between the maxillary and 
mandibular regions, independent samples t-tests were performed. A significance level of 
p<0.05 was set for all statistical tests. Results were reported as mean ± standard 
deviation (mean ± SD), and findings were presented both in tables and visualized using 
heat maps and radar charts. This analysis allowed for the statistical comparison of the 
accuracy and consistency of each digital workflow across different implant positions. 
 
 
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