Bland-Altman Analysis of Maxillary Obturator Bulb Accuracy in Class III Brown Classification Maxillectomy Defects
Phase: NA
Conditions: Maxillary Obturators
Sponsor: Badr University

 
 
 
 
 
 
Bland-Altman Analysis of Maxillary 
Obturator Bulb Accuracy in Class III 
Brown Classification Maxillectomy 
Defects  
 [NCT ID not yet assigned] 
Unique Protocol ID: 2024-1 
Document Date: 18/4/2024 
 
 
 
 
 
 
 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
2 
 
Authors 
 
Shady M. El Naggar 
Associate Professor of Removable Prosthodontics 
Faculty of Oral and Dental Medicine 
Badr University in Cairo 
 
 
Mohamed Adel Youssef 
Assistant Lecturer of Oral Radiology 
Faculty of Oral and Dental Medicine 
Badr University in Cairo 
 
 
 
Youssef M. Eissa 
Resident of Otolaryngology 
Faculty of Medicine 
Cairo University 
 
 
Sherihan M. Eissa 
Associate Professor of Removable Prosthodontics 
Fixed and Removable Prosthodontics Department 
Oral and Dental Research Institute 
National Research Centre 
 
 
 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
3 
 
Administrative information 
 
1. Title  
Accuracy of Maxillary Obturator Bulb in Maxillectomy Defects 
 
2. Funding 
This trial is self-funded by the authors. 
 
3. Roles and responsibilities 
 
a)  List of contributors: 
Shady M. El Naggar 
Associate Professor of Removable Prosthodontics 
Faculty of Oral and Dental Medicine 
Badr University in Cairo 
Role: Principal investigator and main researcher. 
Responsible for the study design. 
 
Mohamed Adel Youssef 
Assistant Lecturer of Oral Radiology, Faculty of Oral and Dental Medicine, Badr 
University in Cairo. 
Role: Co-author. 
Responsible for scanning, analysis, and interpretation of data. 
 
Youssef M. Eissa 
Resident of Otolaryngology, Faculty of Medicine, Cairo University. 
Role: Co-author. 
Responsible for cases selection, and patient management. 
 
Sherihan M. Eissa 
Associate Professor of Removable Prosthodontics, Fixed and Removable Prosthodontics 
Department, Oral and Dental Research Institute, National Research Centre. 
Role: Co-author. 
Responsible for the Statistical methodology and Data scanning interpretation. 
 
b) RCT Sponsor: 
 Faculty of   Oral and Dental Medicine, Badr University in Cairo.  
 Address: Entertainment Area, Badr City, Egypt. 
 Telephone: 02 28650400 
 Website address: https://buc.edu.eg/ 
 
c)Ethics committee 
Ethical approval for the protocol. 
 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
4 
 
Introduction 
Treatment of tumors in the paranasal region often necessitates either palatal maxillectomy 
or radical maxillectomy. Surgical and prosthetic interventions offer avenues to treat post-
maxillectomy patients, ensuring both functional and aesthetic outcomes. However, despite the 
advantages associated with surgical procedures, reconstructive surgery may not always be feasible 
due to the patient's overall health condition and the extent of the defect. In such cases, prosthetic 
reconstruction becomes imperative. (1) 
 
Temporary or permanent obturators serve as effective solutions in prosthetic 
reconstruction, aiming to separate the oral and sinonasal cavities, thus preventing issues like 
hypernasal speech and fluid leakage into the nasal cavity. These prosthetic devices also play a 
pivotal role in restoring functions such as chewing, swallowing, and speech, while providing 
support to the lips and cheeks, thereby aiding in the restoration of facial contour. Moreover, they 
contribute significantly to alleviating the social and psychological distress experienced by patients. 
(2) 
 
The emergence of rapid prototype production technology, also known as rapid prototyping 
(RP) or laser-layered manufacturing, has revolutionized the creation of three-dimensional solid 
models. This technique, which has seen global advancement since 1995, enables the layer-by-layer 
production of physical models directly from computer-aided designs in a single step. Unlike 
traditional computer-assisted design (CAD)-computer-aided manufacturing (CAM) systems that 
involve material removal, rapid prototype techniques employ technologies like lasers and 
numerical control to build models layer by layer, facilitating the creation of intricate internal details 
and smooth surfaces, even in complex structures. (3) 
 
Various rapid prototype techniques, including stereolithography (SLA), laminated object 
manufacturing, selective laser sintering, fused deposition modeling, and three-dimensional 
printing, offer diverse options for model production. These techniques, which utilize different 
materials and layering methods, can be combined to achieve desired outcomes. (4) 
 
Rapid prototype production techniques present a viable alternative to conventional 
methods for constructing facial prostheses. By utilizing computer-aided imaging techniques such 
as computed tomography (CT), magnetic resonance imaging (MRI), and laser surface scanners, 
highly accurate extraoral facial prostheses can be crafted using CAD–CAM and RP technologies, 
ensuring excellent contours and tissue adaptation. (5) 
 
While conventional gypsum models are typically used for prosthetic rehabilitation of 
intraoral deformities like maxillectomy defects, the integration of 3D CAD and RP technologies 
can significantly enhance outcomes. A crucial aspect of creating a functional and aesthetically 
pleasing prosthesis lies in obtaining an accurate impression. Factors such as the properties of the 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
5 
 
impression material, the size and nature of the defect, the presence of undercuts, and the condition 
of remaining teeth influence the accuracy of the impression. Challenges such as pain, tears, and 
deformations during impression removal, as well as bleeding and mucosal adhesion, further 
complicate the process. Additionally, limitations in mouth opening may hinder optimal insertion 
of the impression materials. (6) 
 
Aim of the Study 
 
Research Question 
In patients with maxillary defects, which type of denture base materials fulfill accuracy 
parameters regarding extent of the maxillary defect? 
 
Research Hypotheses 
There is no difference between different denture base materials of maxillary obturator 
regarding bulb accuracy over the extent of maxillary defect. 
 
Outcomes 
1. Accuracy, measuring device: metrology software (Geomagic Control X 20, 3D 
Systems, Rock Hill, SC, USA). 
2. Patient satisfaction using Obturator Functional Scale (OFS). 
 
Materials and Methods 
 
Study Settings 
Randomized controlled study. Patients will be selected and diagnosed by the investigators 
to be enrolled in the trial from the outpatient clinic of faculty of Oral and Dental Medicine, Badr 
University in Cairo. 
 
Eligibility Criteria 
Inclusion Criteria 
• The study included participants of both male and female genders. 
• The patients had defects or abnormalities in both the hard and soft portions of their palate. 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
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• The surgical wound or site had to be fully healed. 
• The upper jaw (maxilla) had partial tooth loss or missing teeth in the defect. 
• Cooperative patients who could follow instructions were selected for the study. 
Exclusion Criteria 
• Temporomandibular disorders 
• Uncontrolled diabetes 
• Bleeding disorders or anticoagulant therapy   
• Flabby tissues or sharp mandibular residual ridge.  
• Heavy smokers.  
• Patient’s with neuromuscular disorders 
• Severe psychiatric disorders 
• Children were not included in the study; only adult participants were considered. 
Justifying Exclusion Criteria 
Temporomandibular disorders (TMD) that could affect the direction of force applied on 
the dentures were exclusion criteria, as TMD symptoms may mask or influence the expected 
improvement and patient satisfaction with the overdentures. 
Patients with severe systemic diseases like uncontrolled diabetes, bleeding disorders, 
neuromuscular disorders, psychiatric conditions, or those undergoing chemotherapy or 
radiotherapy were excluded. Management of their conditions requires special considerations like 
adjusted medication doses, shorter appointment times preferably in the morning, and they have a 
higher risk of dropping out during the trial follow-up period. 
Patients presenting with flabby tissues or sharp/undercut mandibular residual ridges were 
excluded as they require modified impression techniques like sectional trays and plaster materials 
for flabby tissues. Frequent tissue conditioning is also necessary throughout follow-up, which 
could confound the trial results. 
Heavy smokers were excluded as smoking can compromise the physical retention of 
complete dentures, which relies on surface tension and a thin salivary film between the denture 
and tissues for capillary attraction. Smoking decreases salivary flow causing dry mouth 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
7 
 
(xerostomia), which jeopardizes denture retention. Additionally, smoking may affect the long-term 
success of implant osteointegration. 
Interventions 
A perforated stock tray underwent modifications including reduction, bending, or addition 
of modeling wax to accurately capture the entire defect. Undesirable undercuts in the defect were 
blocked using vaselinized gauze. Preliminary impressions were taken with irreversible 
hydrocolloid material, extending into the surgical cavity to replicate undercuts as closely as 
possible. Mandibular impressions were also made with alginate. After verifying details, 
impressions were poured to obtain diagnostic casts. These casts were surveyed to identify survey 
lines, guiding planes, and undercut depths, informing path of insertion selection. Mouth 
preparation followed, with guiding planes prepared on abutment distal surfaces and palatal tooth 
surfaces modified for proper reciprocal clasp positioning. Final impressions were taken using a 
special tray, with modeling wax border molding at the surgical site. After setting, impressions were 
boxed and poured to create master casts. Refractory casts and wax patterns were crafted for 
obturator framework planning, ensuring retention, stability, support, and reciprocation. Metal 
framework try-in was conducted to confirm accuracy before proceeding with acrylic resin 
application. Jaw relation registration was performed using the wax wafer technique. 
 
Groups Design: 
Group I: received maxillary obturators constructed with hard acrylic applied on the 
posterior part of the obturator. 
Group II: received maxillary obturators constructed with injection-molded PMMA resin. 
 
Sample Size Calculation and Statistical Analysis 
Based on Abdelfattah Mohamed A, kothayer Marwa 2020, we are planning a study of 
independent cases and controls with 1 control(s) per case.  Prior data indicate that the probability 
of exposure among controls is 0.2.  If the true probability of exposure among cases is 0.6, we will 
need to study 22 cases in each group to be able to reject the null hypothesis that the exposure rates 
for case and controls are equal with probability (power) 0.8.   The Type I error probability 
associated with this test of this null hypothesis is 0.05.  We will use an uncorrected chi-squared 
statistic to evaluate this null hypothesis. Data will be analysed using IBM SPSS advanced statistics 

 Accuracy of Maxillary Obturator Bulb in Maxillectomy 
Defects (Ex vivo study) 
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(Statistical Package for Social Sciences), version 21 (SPSS Inc., Chicago, IL). Numerical data will 
be described as mean and standard deviation or median and range. Data will be explored for 
normality using Kolmogrov-Smirnov test and Shapiro-Wilk test. Comparisons between 3 groups 
for normally distributed numeric variables will be done using the ANOVA while for non-normally 
distributed numeric variables will be done by Kruskal Wallis test. A P-value less than or equal to 
0.05 will be considered statistically significant. All tests will be two tailed. 
Categorical data will be described as numbers and percentages and comparisons will be 
done by chi square test or fisher exact as appropriate. 
 
References 
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