Clinical Performance of Posterior Restorations of Bulk Fill Resin Composite Without Preheating Versus Repeated Preheating for One, Five and Ten Times: A Randomized Controlled Clinical Trial
Phase: NA
Conditions: Dental Leakage
Sponsor: Cairo University

Clinical Performance of Posterior Restorations of Bulk Fill Resin Composite 
without Preheating Versus Repeated Preheating for One, Five and Ten times: A 
Randomized Controlled Clinical Trial 
 
 
 
 
 
Protocol 
Submitted to Conservative Dentistry Department, Faculty of Dentistry, Cairo University, in partial 
fulfillment of the requirement for a PhD Degree in Restorative and Esthetics Dentistry 
 
By 
Islam Ibrahim Mohammed 
B.D.S Mansoura University (2009)  
M.SC. Ain Shams University (2019) 
 
Supervisors 
 
Prof. Mona Ismail Riad 
Professor of Conservative Dentistry, Faculty of Dentistry Cairo University 
 
 Dr. Heba Helal Elsherbieny 
Lecturer of Conservative Dentistry, Faculty of Dentistry Cairo University 
 
 
 
 
 
 
 
 
 
 
Faculty of Dentistry 
Cairo University 
2022 
 
 
Approval Signature 
 
Supervisors 
1. 
2. 
Department Research plan and 
evidence based committee 
1. 
2. 
3. 
4. 

1 
 
I. Administrative information: 
1. Title: 
Clinical Performance of Posterior Restorations of Bulk Fill Resin Composite without Preheating 
Versus Repeated Preheating for One, Five And Ten times: A Randomized Controlled Clinical 
Trial 
2. Protocol Registration:  
  To be registered in www.clinicaltrials.gov 
3. Protocol version:  
  First version 
4. Funding:  
Self-funding 
5. Roles and responsibilities: 
5a) Names, Affiliations, and Roles of protocol contributions 
*Islam Ibrahim Mohammed (II): 
Operator, data entry & corresponding author; Assistant Lecturer, Operative Dentistry Department, 
Faculty of Dentistry, Delta university for science and technology. 
Postal address: 11 Saraya El Manial street Kasr El Einy. 
Phone: (002)01224235737, Email: islamibrahim@dentistry.cu.edu.eg 
*Prof. Mona Ismail Riad (MI) 
Main supervisor, data monitoring & auditing; Professor of Conservative Dentistry, Faculty of 
Dentistry, Cairo University 
Email:  monariad@dentistry.cu.edu.eg 
*Dr. Heba Helal Elsherbieny(HH) 
Co-supervisor, data monitoring and auditing; Lecturer of Conservative Dentistry,  Faculty of 
Dentistry,Cairo University 
 Email: heba.helal @dentistry.cu.edu.eg 
*Mohammed Sabry (MS) 
Sequence generation, allocation concealment. 
Assistant lecturer, Conservative Dentistry Department, Faculty of Dentistry, Cairo University  
m.sabry@ dentistry.cu.edu.eg 
 

2 
 
*Mostafa El-Ghazali (ME) 
Outcome assessor 
Assistant lecturer, Conservative Dentistry Department, Faculty of Dentistry, Misr University for 
science and technology 
Mostafa-gazaly@ dentistry.cu.edu.eg 
*Omar Abd elaziz (OA) 
Outcome assessor 
Assistant lecturer, Conservative Dentistry Department, Faculty of Dentistry, Delta University for 
science and technology 
omarabdaziz@ dentistry.cu.edu.eg 
*Dr. Khaled Keraa(KK) 
Biostatistician, sample size calculation. 
Misr International University (MIU) – Egypt 
khaledkeraa1970@gmail.com 
*Evidence Based Dentistry Committee (EBD) 
Evidence Based Dentistry Committee of Faculty of Dentistry, Cairo University; Give the 
acceptance that this protocol follows the SPIRIT guidelines. 
*Medical Biostatistics Unit (MBU) 
Medical Biostatistics Unit of Faculty of Dentistry, Cairo University, Responsible for reviewing 
sample size calculation for the trial 
*Research Ethics Committee (REC) 
Research Ethics Committee of Faculty of Dentistry, Cairo University; Reviewing this protocol to 
protect the ethical rights of the participants in the trial. 
*Research Plan Committee (RPC) 
Research Plan Committee of Conservative Dentistry Department, Faculty of Dentistry, Cairo 
University; Ensuring that this protocol considered within the Department research plan. 
 

3 
 
5b) Name and contact information for the trial sponsor 
Trial Sponsor: Faculty of Oral and Dental Medicine, Cairo University 
Address: 11 El-Saraya St. El Manial, Cairo, Egypt 
Tel: (+202) 23634965 - (+202) 2364293 
Fax: (+202) 23646375 
Official email: dentmail@dentistry.cu.edu.eg 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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II. Introduction: 
6 .a.Background and rationale: 
Research question: 
In restoring posterior teeth, is there difference in clinical performance when using no heated, one, 
five and ten time preheated bulk fill resin composite?  
Statement of the problem: 
   Dental resin composites are widely used for adhesive restorative procedures nowadays due to the 
significant improvement in their physical and mechanical properties. However, volumetric 
shrinkage is still an inherent drawback of the polymerization of the resin matrix (Erhardt et al., 
2020). 
  Preheating improves adaptation, polymerization shrinkage and degree of conversion without affect 
mechanical properties of resin composite restorations (Yang et al., 2019).  
  In clinical situation, composite resin syringe is repeatedly used for restoration of several cavities 
and if preheating is applied, this syringe will undergo several heating cycles so repeated preheating 
effect on composite resin should be tested (Oskoee et al., 2017). 
 
Rationale for conducting the research: 
     Up to present no randomized clinical trials were conducted to evaluate the effect of repeated 
preheating of conventional bulk-fill resin composite in posterior restorations. Thus the purpose of 
the current study is to assess the clinical performance of posterior restorations of bulk fill resin 
composite without preheating with repeated preheating for one ,five and ten times. The expected 
benefit is to decrease postoperative sensitivity (Oskoee et al., 2017) and evaluate clinical 
performance of posterior teeth restorations after one year (Thyab, 2020). 
 
Review of literature:  
  Preheating resin composite restorations before application is a new trend in the field of dentistry. 
Preheating increases, the flowability of the composite and reduces its viscosity, providing better 
adaptation to cavity walls, especially for high-viscosity materials. Preheating the resin composite 
reduces microleakage, thereby increasing the durability of the restoration. Preheating also increases 
the temperature of the composite because the higher thermal energy enhances the mobility of the 
radicals and monomers, resulting in a higher degree of monomer conversion and an improved 
polymerization rate (Elkaffas et al., 2019).   
 
D'amario et al. (2015)conducted an in vitro study to assess and compare the flexural strength, 
flexural elastic modulus and Vickers microhardness of three resin composites Enamel Plus HFO 
(Micerium),Opallis (FGM), and Ceram X Duo (Dentsply DeTrey).In which a total of 180 specimens  

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one group of specimens of each material was fabricated under ambient laboratory conditions (210C 
± 10C), whereas in the other groups the composites were cured after 1, 10, 20, 30, or 40 preheating 
cycles to a temperature of 390C in a commercially available preheating device (ENA HEAT 
composite heating conditioner). Vickers microhardness was assessed on 10 cylindrical specimens 
from each group. They found that regardless of the material, the number of heating cycles was not 
a significant factor and was unable to influence the three mechanical properties tested. However, a 
significant main effect of the employed material on the marginal means of the three dependent 
variables was detected. They concluded that the preheating procedure did not negatively influence 
the mechanical properties of the resin composites even when highly repeated. 
 
  Dionysopoulos et al. (2016)  conducted an in vitro study to evaluate the polymerization efficiency 
of bulk fill resin-based ,after preheating  Eight bulk fill RBCs were investigated, Four high-viscosity 
bulk fill RBCs (X-tra fil – XF, EverX Posterior – EXP, Tetric EvoCeram Bulk Fill – TEB and 
Beautifil Bulk Restorative – BBR) and four flowable bulk fill RBCs (X-tra base – XB, Beautifil 
Bulk Flowable – BBF, Filtek Bulk Fill – FB and Venus Bulk Fill – VB) and a conventional 
nanohybrid resin composite (Filtek Z550 – FZ) was used as a control . Five specimens for each 
material were prepared for Vickers hardness measurements. The results showed that as the depth 
increases microhardness values reduce. The Vickers hardness measurements 24 h after photo-
polymerization revealed higher values compared to those obtained immediately after photo-
polymerization. There was an increase in microhardness of the RBC materials when preheated at 
54°C in comparison with the room temperature specimens. They concluded that polymerization 
efficiency of bulk fill RBCs is affected by their composition and increases with temperature and 
post-irradiation polymerization. 
   
 Campbell et al. (2017)  conducted a randomized controlled trial of postoperative sensitivity with 
Warm and room temperature composite. One group had room temperature composite restorations 
placed and the second had composite preheated to 39°C. They found that there was no detectable 
difference in postoperative sensitivity between preheated and room temperature composite 
restorations. They concluded that there is no detectable difference in postoperative sensitivity 
between preheated and room temperature composite restorations for the restorations in this trial, 
when teeth are restored with resin composite. 
   
 Metalwala et al. (2018) conducted an in vitro study to assess the effect of preheating temperature 
on the rheological properties of four nanohybrid dental resin composites [Herculite Ultra 
(Kerr),Tetric EvoCeram (Ivoclar Vivadent), Filtek Supreme Ultra (3 M) and Grandio (Voco)]. 
Measurements were obtained at three different temperatures 25, 37 and 60 °C. Preheating the 
composite material resulted in enhanced flow and greater adaptability. They found that preheating 
the nanohybrid dental composites considerably improves their flowability and can improve clinical 
placement and adaptation. Finally they concluded that preheating the nanohybrid dental composites 
considerably improves their flowability, which provides increased mechanical characteristics and 
seal strength.  
 

6 
 
Karacan and Ozyurt (2019) measured the intra-pulpal temperature increase when placing room 
temperature or preheated  bulk-fill composite .Total number of 30 extracted human lower third 
molars were selected and class II (MOD) cavities in each tooth were prepared, resulting in a 
remaining dentin thickness of 1 mm. A K-type thermocouple was placed inside the pulp chamber.  
In first group bulk-fill composite (Filtek bulk-fill posterior [3M-ESPE], that was stored at room 
temperature. In the second group, the composites were preheated in an oven for 15 minutes at 54°C.  
In the third group, the composites were preheated in an oven for 15 minutes at 60°C. They found 
that preheating does not represent a significant problem in terms of intrapulpal temperature increase. 
Even if the preheating process results in increases with the increase of intrapulpal temperature, this 
temperature increase is not the critical factor that causes harm to the pulp. 
 
   Winarta et al. (2020)  conducted an in vitro study to analyze the effect of repeated preheating on 
the mechanical properties of a composite resin with different fillers. Microhybrid, nanohybrid, and 
nanofill composite resins were preheated (ten times, twenty times, and not heated as a control. The 
specimens were divided into two groups: Group 1 was immediately tested using a universal testing 
machine. Group 2 was soaked in 37°C artificial saliva for 24 h before testing. Each specimen was 
tested using the universal testing machine with the pressure side with a 1 mm/s crosshead speed. 
They found that nanohybrid composite resin had the most stable diametral tensile strength after 
repeated preheating, whereas nanofill composite had the weakest strength. They concluded that 
repeated preheating did not significantly affect the diametric tensile strength of composite resin. 
 
6.b.Explanation for choice of comparator:  
Bulk fill resin composite without preheating will be used as a control. The technique would be faster 
than placing numerous increments. Using of bulk fill reduce the technique sensitivity and shorting 
time of insertion   (Elmarakby, 2020).  
Preheating of bulk fill resin composite improve adaptation, polymerization shrinkage and degree of 
conversion  (Lempel et al., 2019) .  
 
 
7. Objectives: 
a.Aim of the study: 
Compare the clinical performance of bulk fill resin Composite without preheating with one, five and 
ten times preheating bulk fill resin composite in posterior teeth after one year. 
 
b.Hypothesis:  
 
The null hypothesis of this study is that there is no significant difference in clinical performance of 
the restoration during restoring posterior teeth when using bulk-fill without preheating and after 
repeated preheating for one , five and ten times in restoration of posterior teeth. 
 
Primary objective:  Clinical Evaluation of restoration (marginal integrity) using Modified US 
Public Health Service Criteria (USPHS) 

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Secondary objectives: Clinical Evaluation of restoration (Marginal discoloration, secondary caries 
and Postoperative Sensitivity) [Time Frame: 1 year] Modified US Public Health Service Criteria 
(USPHS) 
C.PICOTS 
P (Population): Carious molar teeth. 
I (Intervention): 
Intervention 1: restoration with one-time preheated conventional bulk-fill resin composite, X-tra 
fill (VOCO, GERMANY)  at 68◦C (Yang et al., 2020). 
Intervention 2: Restoration with five time preheated conventional bulk-fill resin composite, X-tra 
fill (VOCO, GERMANY) at 68◦C (Yang et al., 2020). 
Intervention 3: Restoration with ten time preheated conventional bulk-fill resin composite, X-tra 
fill (VOCO, GERMANY) at 68◦C (Yang et al., 2020). 
C (Control): Restoration with conventional no heated bulk-fill resin composite, X-tra fill (VOCO, 
GERMANY) 
O (Outcome):  
 
Primary outcome: marginal integrity 
Secondary outcomes:  
Clinical performance of the restoration by Modified US Public Health Service Criteria (USPHS). 
T :( Time) 
T1= 3 months 
T2=6 months 
T3=9 months 
T2= 12 months 
 

8 
 
 
Outcome 
Measuring device 
Measuring unit 
primary 
(marginal 
integrity) by 
Modified US 
Public Health 
Service 
Criteria 
(USPHS) 
Modified USPHS Ryge 
criteria(van Dijken et al., 2019) 
Scoring system 
(Ordinal) : 
-Alfa 
-Bravo 
-Charlie 
-Delta 
 
secondary 
Modified US 
Public Health 
Service 
Criteria 
(USPHS) 
Retention, 
color 
matching, 
marginal 
discoloration, 
secondary 
caries, surface 
texture, 
anatomic 
form and 
postoperative 
sensitivity 
Modified USPHS Ryge 
criteria(van Dijken et al., 
2019) 
Scoring system 
(Ordinal) : 
-Alfa 
-Bravo 
-Charlie 
-Delta 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
S: (study design): Randomized controlled clinical trial. 
 
 
8. Trial design: 
Type of trial: four parallel groups 
Allocation ratio:  1:1:1:1 
Framework: Superiority 
 
 
 
 

9 
 
III. Methods 
A) Participants, interventions & outcomes 
9. Study settings: 
Patient selection and the procedures will be carried in Conservative clinic at Faculty of Dentistry, 
Cairo University, Cairo, Egypt.  
 
10. Eligibility criteria: 
The participants will be chosen according to the following eligibility criteria: 
Inclusion Criteria 
Exclusion criteria 
 
a)Inclusion Criteria of participants 
1-Patient age between (18-60) years old. 
2-Patient is capable of informed consent. 
3-Patients with a high level of oral hygiene. 
 
 
 
 
 
 
 
 
 
 
a)Exclusion criteria of participants 
1-Participants with general systematic illness. 
2-Experience with allergic reactions against 
any component of used materials. 
3-Concomitant participation in another 
research study. 
4-Patients receiving Orthodontic treatment. 
5- Pregnant or lactating females. 
6-patient with heavy Bruxism habits. 
 
 
b)Inclusion Criteria of teeth: 
1- vital teeth 
2-Carious molar teeth. 
b)Exclusion criteria of the teeth 
1-The tooth to be filled is an abutment tooth for 
a removable prosthesis. 
2- The tooth to be filled is periodontally 
involved (grade 2 or grade 3 mobile). 
3-Endodontically treated tooth. 
4-tooth with previous restoration 
5-Exposed tooth. 
 
 
11. Interventions 
Medical and dental history will be obtained from all patients participating in this research. 
Clinical and radiographic evaluation for each tooth included in this study will be recorded 
(Appendix, B). 
Control group: 
Restoration with no heated bulk fill composite, , X-tra fill (VOCO, GERMANY) 

10 
 
Intervention groups: 
Restoration with preheated  bulk fill composite preheated for one ,five and ten times  at 68°C using 
Therma flo (VISTA APEX,USA)(Yang et al., 2020). 
a-Procedures: 
1-Preoperative periapical x-ray will be taken for the tooth to be restored. 
2- The clinical diagnosis of vitality tests will be confirmed by cold and hot tests. 
3- Anaesthesia will be given. 
4-Isolation of the teeth by rubber dam application 
5-cavity preparation will be done with fissured bur with round end (880 Oekodental Germany) of 
6mm length and 1.4mm width to the DEJ. 
6-Partial caries removal will be done by excavator.  
7- Selective etch technique by applying 37% phosphoric acid Eco-etch(IvoclarVivadent) to enamel 
margins of the cavity for 15 seconds then rinse for 15 seconds. 
8- Applying Futura bond M+ (Voco ,Germany)  then light curing for 20 seconds using 3M Eliper 
curing unite. 
9-application of bulk fill composite Xtra fill  (VOCO ,GERMANY) 
In the control group: application of bulk fill resin composite without preheating. 
In the experimental groups:  application of preheated bulk fill resin composite  restoration with 
one-five and ten times according to the group number at 68◦C using Therma flo (VISTA 
APEX,USA) 
Intervention1: one-time preheated  
Intervention 2: five times preheated  
Intervention 3: ten times preheated  
10-checking the occlusion by using the articulating paper. 
11-finishing and polishing. 
12-Patient will be return for follow up after 3, 6, 9 and 12 months. 
B-Criteria for discontinuing:  
If very severe pain exists that can’t be relieved and patient can’t withstand, the tooth may be 
endodontically treated or extracted and the patient will be excluded from the study. 
C-Strategies to improve adherence:  
Phone calls to patients will be done to remember for follow up visits. 

11 
 
12. Outcomes: Modified USPHS Ryge criteria(van Dijken et al., 2019) 
 
 
 
 
 
 
 
 
 

12 
 
13.Participant timeline 
 
Procedure 
Staff 
Member 
Before 
1stvisit 
1st 
visit 
3months 
6months 
9months 
12months 
Enrolment 
MS 
 
 
 
 
 
 
Allocation 
MS 
 
 
 
 
 
 
Cavity 
preparation 
II 
 
 
 
 
 
 
Restoration 
placement 
II 
 
 
 
 
 
 
outcome 
assessment 
ME,OA 
 
 
 
 
 
 
 
14. Sample size: 
This power analysis used marginal integrity scores after 12 months as the primary outcome. The 
effect size w1 = (0.53) was calculated based upon the results of Tetric N Ceram Bulk fill publis hed 
by   (Alkurdi and Abboud, 2016). The effect sized w2 = (0.7), w3 = (0.8) and w4 = (0.9) were 
calculated based upon expert opinion estimating Alpha scores = 85%, 90%, 95% and Bravo scores 
= 15%, 10% and 5%, respectively.  Using alpha (α) level of (5%) and Beta (β) level of (20%) i.e. 
power = 80%; the minimum estimated sample size was a total of 68 subjects. Sample size was 
increased to 84 subjects (21 subjects per group) to compensate for a dropout rate of 25%. Sample 
size calculation was performed using G*Power Version 3.1.9.2   
 
 
15. Recruitment: 
Patients will be recruited by (MM) from the outpatient clinic of conservative dentistry department 
in Faculty of Dentistry, Cairo University, as there is a high and continuous patient flow from which 
the eligible participants could be chosen until reaching the target sample size. 
B) Assignment of interventions 
16. Allocation: 
16a. Randomization: 
Simple randomization will be made by generating random numbers using Random Sequence 
Generator, Randomness and Integrity Services Ltd (https://www.random.org/) by (MS).  
16b. Allocation concealment mechanism:  
Patients will choose between random numbers placed in an opaque sealed envelope that will be 
arranged by (MS), who will not be further involved in any of the phases of the clinical trial. Whether 
the intervention or the comparator treatment group would be chosen, it will be recorded on a 
computer by (II). And (HH). and all records will be kept with the main supervisor (MI) 
 
 
 

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16c. Implementation 
(MS) will generate the random allocation sequence. The researcher will enroll the patients, but (MS) 
will assign the intervention/Control identification procedures to respective teeth. 
 
 
17. Masking/blinding: 
- 
Participants will be blinded as they won’t be told which restoration technique will be used. 
 
- 
The outcome assessors (ME) (OA) will be blinded to the material used. This will be 
performed 
Therefore it is necessary that the assessors won’t be included in the preclinical 
assessment.will be only allowed to know the number of the participant. 
- 
Data analyst (KK) will be blinded, he will receive data excel sheets with symbols.  
 
 
C) Data collection, management, and analysis: 
18. Data collection methods 
 
18.a.i. Baseline data collection: 
For every patient, medical and dental history will be taken. Examination charts will 
be filled  
 
18.a.ii. Outcome data collection: 
Modified USPHS criteria for dental restoration will be evaluated by two assessors (ME& OA) at 
3,6,9 and 12months, if both assessors differ in score, they will discuss the outcome, if they did not 
agree, a third assessor will resolve the conflict. To achieve inter-examiners reliability, at the 
beginning of the study, the assessors will perform a profound assessment training program by 
performing repeated assessments of restorations using modified USHPS criteria. The main 
supervisor (MI) will supervise the training program to ensure that the assessors (ME& OA) will be 
calibrated before starting their evaluation. 
 
18.b. Patient retention: 
A record of patient’s phone number will be included in every patient’s chart. Phone call will be 
diverted to each patient in order to remind him/her for the time of his/her visit. If the patient did not 
reply for any reason, another visit will be scheduled within a week. 
 
19. Data management: 
Participant files are to be electronical stored in numerical order and stored in a secure and accessible 
place and manner with (IM). Participant files will be maintained in storage till completion of the 
study 
 

14 
 
20. Statistical methods: 
Data will be analyzed using IBM SPSS advanced statistics (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. Categorical data will be described as numbers and percentages. Data 
will be explored for normality using Kolmogrov-Smirnov test and Shapiro-Wilk test. Comparisons 
between two groups for normally distributed numeric variables will be done using the Student’s t-
test while for non-normally distributed numeric variables will be done by Mann-Whitney test. 
Comparisons between categorical variables will be performed using the chi square test. Pain over 
time will be assessed by Friedman test. A p-value less than or equal to 0.05 will be considered 
statistically significant. All tests will be two tailed. 
 
D) Data monitoring: 
 
21. Monitoring 
The main and co-supervisors (MI, HH) will monitor this study to prevent any risk of bias from trial 
members also to ensure blinding of the assessors and maintain patient safety and rights 
22. Harms 
Adverse reaction is low and rarely occurs. Pain will be relieved by analgesics and if very severe pain 
exists that can’t be relieved and patient can’t withstand, the tooth may be endodontically treated or 
extracted. 
 
23. Audit 
Auditing will be performed by the evidence based committee, Faculty of dentistry, Cairo University 
at the beginning and half of the study to confirm that the coordinators are skillful in data entry, the 
overall quality and completeness of the data. Furthermore, auditing is important to review data that 
is related to participant enrolment, consent, eligibility and allocation to study groups to confirm that 
the data is accurate. 
 
 
 
 
 
 
 
 
 
 
 
 
 

15 
 
IV. Ethics and dissemination 
24. Research ethics approval 
This protocol has the template of informed consent forms with two languages (Arabic and English) 
with explanation for the steps of treatment that will be done and harms (Appendix A). This template 
will be approved by ECs (Ethical Committees) before starting the trial. 
 
25. Protocol amendments 
      If there are any modifications or adjustments in the protocol, ethical committees will be informed 
of that and will be reported in the study. Intention to treat analysis will be followed as all patients 
that are eligible for the trial and have been allocated in the randomization sequence will be treated 
normally and statistically analyzed. Such amendment will be agreed upon by the council of the 
department of Evidence Based Dentistry, Faculty of Dentistry, Cairo University. 
 
26. Informed consent 
The research operator(II) will introduce the template of informed consent with Arabic language to 
every patient with detailed explanation about aim, steps, advantage and side effect of the treatment, 
so every patient will receive information sheets of the trial with Arabic language (Appendix A). The 
operator will take signed consent from patients who will participate in this trial. 
 
27. Confidentiality 
All personal information about participants will be acquired during taking patient history (personal, 
medical and dental), eligibility screening, and data collection. All information will be stored securely 
in locked file cabinets in areas with limited access.  
 
28. Declaration of interest 
There is no conflict of interest. 
29. Access to data 
       The results of the interventional trial can be verified only by the Project Chief Investigators, 
who will have direct full access to their own site’s complete final data sets. 
30. Post-trial care 
Patients will be followed up after the restorative work to maintain the oral hygiene measures. When 
there is any evidence of restoration failure, patients will be treated by immediate restoration 
replacement by different restorative option to the tooth. 
31. Dissemination policy 
Patients will be informed after the trial which technique is better than the other. Colleagues in 
conservative dentistry department Cairo University will be informed of results of the study.  
Full protocol will be published online in www.clinicaltrials.gov to keep the integrity of the 
research methods and to avoid repetition. 
 Thesis will be discussed and defended in front of a professional judgment committee. 
 The results of this clinical trial will be internationally published. 
 
 
 

16 
 
V. Appendices 
 
32. Informed consent 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

17 
 
Appendix A: Informed Consent Model of (REC) Faculty of Dentistry, Cairo University will be 
used in this study 
                                                                                            
 
 
Application Form 
Human Subjects 
Clinical Performance of Posterior Restorations of Bulk Fill Resin Composite without Preheating 
Versus Repeated Preheating for One, Five And Ten times: A Randomized Control Clinical Trial 
Master [ ] PHD/D [√ ] others [ ] 
Full name of the researcher(s): Islam Ibrahim Mohammed 
Research objective: This study will be conducted to compare the clinical performance of bulk fill 
resin Composite without preheating with one, five and ten times preheating bulk fill resin 
composite in posterior teeth after one year. 
 
Procedure in brief: 
*Preoperative steps: The patients will be subjected to full examination and diagnosis using 
dental charts. 
*Operative steps: 
1-Preoperative periapical x-ray will be taken for the tooth to be restored. 
2- The clinical diagnosis of vitality tests will be confirmed by cold and hot tests. 
3- Anaesthesia will be given. 
4-Isolation of the teeth by rubber dam application 
5-cavity preparation will be done with fissured bur with round end (880 Oekodental Germany) of 
6mm length and 1.4mm width to the DEJ. 
6-Partial caries removal will be done by excavator.  
7- Selective etch technique by applying 37% phosphoric acid Eco-etch(IvoclarVivadent) to enamel 
margins of the cavity for 15 seconds then rinse for 15 seconds. 
8- Applying Futura bond M+ (Voco ,Germany)  then light curing for 20 seconds using 3M Eliper 
curing unite. 
9-application of bulk fill composite Xtra fill  (VOCO ,GERMANY) 
In the control group: application of bulk fill resin composite without preheating. 
In the experimental groups:  application of preheated bulk fill resin composite  restoration with 
one-five and ten times according to the group number at 68◦C using Therma flo (VISTA 
APEX,USA) 
Intervention1: one-time preheated  
Intervention 2: five times preheated  
Intervention 3: ten times preheated  
 
 

18 
 
 
 
 
10-checking the occlusion by using the articulating paper. 
11-finishing and polishing. 
12-Patient will be return for follow up after 3, 6, 9 and 12 months. 
 
Number of visits & follow up period: restoration will be evaluated at 3,6,9 and 12 months 
 Direct benefit of the research to the human volunteer :Decrease the postoperative sensitivity of  resin 
composite restorations 
Scientific value and social benefits: assess the clinical performance of posterior restorations of bulk 
fill resin composite without preheating with repeated preheating for one ,five and ten times. The 
expected benefit is to decrease postoperative sensitivity and evaluate clinical performance of 
posterior teeth restorations after one year. 
 
Expected risk to the human subjects: the ordinary side effects associated with any restorative 
treatment and no of the study variable has side effect on the patient and in case of any side effect 
due to the restorative treatment, the participant will directly contact the operator. 
 
 
 
 
 
Signature: Islam Ibarhim Mohammed 
 
 
 
 
 
 
20 
3 
22 
 
 
 
 
 
 
 
 

19 
 
Appendix B : Diagnostic form to be completed for each patient 
 
 
 
 
 
 
 
 
 

20 
 
 
33.Statement of originality 
Up to present no randomized clinical trials were conducted to evaluate the effect of repeated 
preheating of conventional bulk-fill resin composite in posterior restorations. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

21 
 
 
VI. References 
Alkurdi, R. M. and Abboud, S. A. (2016) 'Clinical evaluation of class II composite: Resin 
restorations placed by two different bulk-fill techniques', Journal of Orofacial Sciences, 8(1), 
pp. 34. 
Campbell, I., Kang, J. and Hyde, T. (2017) 'Randomized Controlled Trial of Postoperative 
Sensitivity with Warm and Room Temperature Composite', JDR Clinical & Translational 
Research, 2(3), pp. 295-303. 
D'amario, M., De Angelis, F., Vadini, M., Marchili, N., Mummolo, S. and D'Arcangelo, C. (2015) 
'Influence of a repeated preheating procedure on mechanical properties of three resin 
composites', Operative Dentistry, 40(2), pp. 181-189. 
Dionysopoulos, D., Tolidis, K. and Gerasimou, P. (2016) 'The effect of composition, temperature 
and post-irradiation curing of bulk fill resin composites on polymerization efficiency', 
Materials Research, 19(2), pp. 466-473. 
Elkaffas, A. A., Eltoukhy, R. I., Elnegoly, S. A. and Mahmoud, S. H. (2019) 'The effect of preheating 
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