Evaluation of Clinical Performance, Parent's Satisfaction, Gingival Health and Bacterial Effects of Bioflex Crowns & Endocrowns Compared to Ready-Made Zirconia Crowns on Pulpotomized Primary Molars: A Randomized Clinical Trial
Phase: NA
Conditions: Primary Teeth
Sponsor: Al-Azhar University

 
 
 
 
Evaluation of Clinical Performance, Parent’s Satisfaction, Gingival 
Health and Bacterial Effects of Bioflex Crowns & Endocrowns 
Compared to Ready-Made Zirconia Crowns on Pulpotomized 
Primary Molars: A Randomized Clinical Trial 
A Protocol submitted to the Faculty of Dental Medicine (Boys, Cairo), 
Al-Azhar University, in the partial fulfillment of the requirements of 
Doctor Degree in Pedodontic and Oral Health 
 
 
 
Department of Pedodontics and Oral Health, 
Faculty of Dental Medicine (Boys, Cairo), 
 Al-Azhar University 
1445 H- 2023 G 
 
 
Introduction 
Dental caries is the most prevalent disease, affecting 60–90% of 
children worldwide. If left untreated, tooth structure would be 
progressively damaged lead to pulpal inflammation which require pulpal 
therapy. Primary dentition commonly affected by caries because of 
improper oral hygiene and increased intake of sucrose. Nowadays, 
repairing and restoring primary teeth rather than extraction is receiving 
attention to maintain appropriate articulation and preserve the space 
required for the eruption of permanent teeth (1). 

Selecting a suitable final restoration for Pulpotomized primary 
molars is the key element that affects success of treatment. Stainless steel 
crowns (SCCs) are known to be the most protective, and durable 
restorations of the primary dentition with the advantages of maintaining 
morphologic form, superior clinical performance, effortless placement and 
time-efficient (2). Despite superior qualities of (SSCs), their use is not 
popular nowadays due to poor esthetic appearance, parents and child’s 
demanding more esthetic restoration. So, several treatment options have 
been developed for treatment of primary teeth such as strip crowns, pre-
veneered stainless-steel crowns and zirconia crown(3). 
Zirconia is being used successfully in general dentistry, due to its 
superior toughness and fracture resistance compared with other types of 
ceramics, it is a crystal-like dioxide of zirconium that possess a metal like 
mechanical properties and a tooth like color, that are available to use for 
primary teeth treatment. Pediatric zirconia crowns were introduced by EZ-
pedo and became commercially available in 2008(4). 
Pediatric zirconia crowns are preformed and made completely with 
ceramic materials (tetragonal zirconia). It have high ﬂexural strength, 
allowing them to resist crack propagation, high strength, toughness, higher 
resistance to chemicals, and superior erosion resistance, so it provided a 
more durable and esthetic alternative for the management of dental caries 
in primary molars (5). 
The clinical performance, gingival status and periodontal health of 
pediatric zirconia crowns versus stainless steel crowns were evaluated in 
several studies )6-9) ,and showed that zirconia crown had more clinical 
performance, gingival and periodontal health than that of stainless steel 
crowns, However, the amount of tooth reduction needed to receive zirconia 

crown (determinant factor for passive fitting) is more aggressive than that 
required for stainless steel crowns by approximately 20 to 30% So there 
are need for developing more flexible esthetic restorations (6). 
Bioflex crowns are available as aesthetic preformed pediatric crowns 
that are flexible, durable, and adaptable offering properties of both stainless 
steel and zirconia crowns. There is a lack of literary evidence for 
assessment of the properties of Bioflex crowns and their effect on clinical 
outcomes and parental satisfaction compared to traditionally available 
options (10). 
More conservative treatment modalities preserving natural tooth 
structure (minimal intervention dentistry) have been considered aided by 
simultaneous progress in biological research and development of adhesive 
materials. Endocrowns were ﬁrst described in 1999 by Bindl and Mörmann 
considered one of these strategies (11). Endocrowns are monolithic adhesive 
ceramic restorations give the opportunity of color matching, and shade 
selection that is not available in ZC (12). 
Endocrowns need a special preparation design with less 
circumferential tooth reduction including a butt joint preparation at the 
cervical margin that end supragingival so eliminates any possible 
discomfort or gingival trauma during tooth reduction offering healthier 
periodontal tissues, more peripheral enamel preservation, and an increase 
in the surface area for bonding. In contrast, the ﬁnishing line of ZC must 
extend for 1 to 2 mm subgingivally. But the occlusal surface reduction is 
similar for both restorations (4). Endocrown retention is gained macro-
mechanically by friction with the pulpal walls, and micromechanically 
through adhesive cementation (12). 

Endocrowns are considered as effective restorations for molars that 
have undergone endodontic treatment offering better fracture resistance 
and stress distribution, offer excellent strength for cuspal overlays, it can 
be used as a final restoration for primary molars preserve tooth structure, 
and maintain periodontal health(13). 
     Up to our knowledge, there is no study evaluate the clinical 
performance, bacterial adherence, assessment of dental plaque and gingival 
status of  endocrowns and Bioflex crowns as a new restorative modality in 
Pulpotomized primary molars compared with prefabricated ZCs, and the 
parental satisfaction toward the three restorations at the end of the12 month 
follow-up  
 
 
 
 
 
 
 
 
 
Aim of the study 
This study will be conducted to evaluate clinical performance, 
parent’s satisfaction, gingival health and bacterial effects of Bioflex 
crowns &Endocrowns compared to ready-made zirconia Crowns on 
Pulpotomized primary molars 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Patients and Methods 
Study Design: 
This study will be designed as a randomized clinical trial 
Sample Size calculation: (7,13) 
This study will be conducted to evaluate Clinical performance, bacterial 
adherence, assessment of gingival health and patient satisfaction of LS2 
endocrowns and Bioflex crowns compared with prefabricated zirconia 

crowns as a restoration of Pulpotomized primary molars. Assuming there 
is no difference between groups (equivalence trial), if there is truly no 
difference between the standard and experimental treatments, then 22 
patients in each group are required to be 80% sure that the limits of a two-
sided 95% confidence interval will exclude a difference in means of more 
than 0.6. This number is to be increased to 24 in each group to compensate 
for possible losses during follow up. Sample size was calculated by sealed 
envelope power calculator. 
Study Setting and Population: 
This study will involve children with 72 primary molars who require 
Pulptomy treatment at the Pedodontics and Oral Health Department, 
Faculty of Dental Medicine (Boys, Cairo), Al-Azhar University. 
Subject grouping: 
The involved primary molars (n= 72) will be divided randomly into 3 
groups (n=24) according to the type of the final restoration for 
Pulpotomized molars as the following 
 
 Group A: will be restored with endocrown (study group) 
 Group B: will be restored with prefabricated Bioflex crown (study 
group). 
 Group C: will be restored with prefabricated zirconia crown (control 
group). 
Eligibility criteria for the study: 
Inclusion criteria: (12)  
 Parents' and patients’ acceptance and cooperation (franklel scale 
+ve.++ve ) 

 Apparently Healthy children. 
 Child’s age ranging from 4 to 8 years old. 
 Primary 2nd molars  with deep carious lesion indicated for vital  
Pulptomy  
  No periapical pathological lesion  
  No root resorption exceeding more than 2/3 of root length.  
 
 

 
 
Exclusion criteria (12) 
 Medically compromised children (bleeding disorders, cardiac patient 
and any systemic diseases could affect oral and gingival health. 
 Presence of para-functional habits. Such bruxism. 
 Non-restorable tooth. 
 Teeth with non-vital pulp 
Ethical Consideration: 
 This study will be carried out after approval of the Ethical 
Committee, Faculty of Dental Medicine (Boys, Cairo), AL-Azhar 
University. 
 All children's parents/ guardians will be informed in a verbal and 
written manner about the aim of these research. A written informed 
consent will be signed by the parents before starting the study  
Intervention: 
Pulptomy Procedures (12) 
 The tooth will be anaesthetized. Then, it will be isolated using a rubber 
dam. 
  Caries will be removed with a sterile non-end cutting bur # 558 to 
complete the removal of the pulp chamber roof under copious water 
coolant spray. Coronal pulp tissue remnants will be removed with a 
sharp, sterile excavator. A piece of cotton soaked with formocresol will 
be inserted into the pulp chamber for 5 minutes. 

 
 
 After removing the formocresol pellet, a thick mix of zinc-
oxide/eugenol paste will be packed into the pulp chamber to seal the 
oriﬁces. 
Restoration of the tooth: 
According to the groups restoration will be as the following: 
Group A: Endocrowns tooth preparation, scanning, cementation: 
For the endocrowns (12, 13) 
 A layer of light -cured glass ionomer cement ° of 1 mm thickness will 
be applied over the ZOE- to isolate it from the successive resin based 
restorations and adhesives- leaving a minimum of 3 mm of the pulp 
chamber to provide an adequate thickness for the endocrown core. 
 Round-end tapered stone will be used to achieve depth cuts of 1.5 mm 
for occlusal clearance  
 A wheel stone will complete the occlusal reduction and making butt 
joint ﬁnish line. 
 Tapered stone of 8-degree angle will be used to prepare axial wall 
ﬂared, the pulp chamber walls to a standard degree of divergence.  
 Abrasive rubber tip will be used to smoothening and rounding the 
internal angles giving a polished and smoothed preparation. 
 Endocrown will be manufactured using CAD/CAM technology  
 internal wall of crown will be treated with etchant material, rinsed, 
dried then silane coupling agent  

 
 
 Dual-cure resin cement will be applied on the crown fitting surface for 
endocrown cementation. 
Group B: Preformed Bioflex crowns (10) 
      According to manufacturer instruction the preparation will be as the 
follow: 
 Light -cured glass ionomer filling of adequate thickness will be 
applied over the ZOE to seal the cavity before preparation  
 A digital caliper will be used to measure a mesio-distal dimension of 
tooth then suitable sized preformed crown will be selected.   
 Tooth preparation will be carried out with a tapered diamond bur for 
occlusal reduction by 1–1.5 mm, including the central groove. 
 The proximal preparation will be around 0.5 mm to clear the contact 
area 
 Placement of the crown will be achieved by a snug fit followed by 
contouring using a Hover’s plier. 
 Crown cementation will be carried out using glass ionomer cement 
and removal of excess cement using floss or explorer. 
Group C: performed zirconia crowns (10, 12, 13) 
 Light -cured glass ionomer filling of adequate thickness will be 
applied over the ZOE to seal the cavity before preparation. 
 A digital caliper will be used to measure a mesio-distal dimension of 
tooth then suitable sized preformed crown will be selected. 

 
 
 A diamond bur will reduce the occlusal surface by 1.5–2 mm 
 Interproximal contacts will be prepared with a tapered fissure bur. 
About 1–2 mm sub gingival preparation will be performed 
 The selected crown will be placed and checked. 
 The passive fit of the crown will be assessed and will be luted with 
glass ionomer cement.  
 Consistent firm finger pressure will be applied during cementation. 
Observations: 
Clinical Performance Assessment (10,12) 
 Retention, marginal adaption, fracture of the restoration were scored 
using a modified United States Public Health Service (USPHS) 
criterion. 
 Dental plaque accumulation and gingival condition were assessed 
using plaque index (PI) and GI. 
 Preparation time and cementation assessment using stop watch to 
record 
time 
from 
preparation 
start 
till 
final 
restoration 
cementation.(15)  
 Clinical performance and oral status will be assessed at follow-up 
periods of 3 (T1), 6 (T2), and 12 (T3) months. At the end of the 
follow-up (T3), parent’s satisfaction analysis toward the color, shape, 
and size of three restorations will be adopted to directly evaluate their 
satisfaction toward their children’s restorations. Parents’ responses 
were rated on a 5-point Likert-type scale. 

 
 
Microbiological analysis: (9) 
 The swabs will be collected before preparation of crowns, 3 months, 
6 months and 12 months after cementation. 
 The number of Streptococcus Mutans, lactobacillus will be digitally 
counted. 
 Swabs will be taken from occlusal surface by means of the tips of 
sterile cotton 
 All specimens were transported immediately to microbiological lab. 
 Swabs will be taken from occlusal surface by means of the tips of 
sterile cotton. 
 Samples will be preserved in a transporting medium tube containing 
9ml thioglycolate broth medium.  
 The number of Streptococcus Mutans, lactobacillus will be digitally 
counted. 

 
 
Data Management and Analysis 
Data will be analyzed using IBM SPSS advanced statistics (Statistical 
Package for Social Sciences), version 27 (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. An equivalence limit will be checked in the difference between 
groups. Categorical data will be described as numbers and percentages and 
comparisons will be done by chi square test or fisher exact as appropriate. 
A p-value less than or equal to 0.05 will be considered statistically 
significant. All tests will be two tailed. 
 
 
 
 
 
 
 
 

 
 
                                             References 
1. Ramakrishnan M, Banu S, Ningthoujam S, Samuel VA. Evaluation of 
knowledge and attitude of parents about the importance of maintaining primary 
dentition - A cross-sectional study. J Family Med Prim Care. 2019;8(2):414-8. 
2. Seale NS, Randall R. The use of stainless steel crowns: a systematic literature 
review. Pediatr Dent. 2015;37(2):145-60. 
3. Salami A, Walia T, Bashiri R. Comparison of Parental Satisfaction with Three 
Tooth-Colored Full-Coronal Restorations in Primary Maxillary Incisors. J Clin 
Pediatr Dent. 2015;39(5):423-8. 
4. Alzanbaqi SD, Alogaiel RM, Alasmari MA, Al Essa AM, Khogeer           LN, 
Alanazi BS, et al. Zirconia Crowns for Primary Teeth: A Systematic Review and 
Meta-Analyses. Int J Environ Res Public Health. 2022;19(5). 
5. Planells del Pozo P, Fuks AB. Zirconia crowns--an esthetic and resistant 
restorative alternative for ECC affected primary teeth. J Clin Pediatr Dent. 
2014;38(3):193-5. 
6. Agrawal R, Khanduja R, Singhal M, Gupta S, Kaushik M. Clinical Evaluation 
of Stainless Steel Crown versus Zirconia Crown in Primary Molars: An In Vivo 
Study. Int J Clin Pediatr Dent. 2022;15(1):15-9. 
7. Salama, Ahmed Adel. Zirconia crowns versus pre-veneered stainless steel 
crowns in primary anterior teeth A retrospective study of clinical performance 
and parental satisfaction. Egypt Dent J, 2018, 64.4-October (Orthodontics, 
Pediatric & Preventive Dentistry): 3075-3084. 

 
 
8. Lopez-Cazaux S, Aiem E, Velly AM, Muller-Bolla M. Preformed pediatric 
zirconia crown versus preformed pediatric metal crown: study protocol for a 
randomized clinical trial. Trials. 2019;20(1):530. 
9. Wakwak MA, El Bayoumy SY, Barakat IF, Tawfik AM. Assessment of microbial 
adhesion to zirconia and stainless-steel crowns in primary molars. Al-Azhar J of 
Dent Sci. 2019;22(2-165):169. 
10. Rahate I, Fulzele P, Thosar N. Comparative evaluation of clinical performance, 
child and parental satisfaction of Bioflex, zirconia and stainless steel crowns in 
pediatric patients. F1000Research. 2023;12:756. 
11. Bindl, Andreas; Mormann , Werner H. Clinical evaluation of adhesively placed 
Cerec endo-crowns after 2 years-preliminary results. Journal of Adhesive 
Dentistry, 1999, 1: 255-266. 
12. Khattab NMA, Makawi Y, Elheeny AAH. Clinical Evaluation of CAD/CAM  
Ceramic  Endocrown  Versus  Prefabricated  Zirconia Crown in the Restoration 
of Pulpotomized Primary Molars: A Two- Year  Spilt-Mouth  Randomized  
Controlled  Trial.  Eur  J  Dent. 2022;16(3):627-36. 
13. Mansour, Ammar Mohamed, et al. Fracture Resistance of Endocrowns Versus 
Prefabricated Zirconia Crowns in Endodontically Treated Primary Second 
Molar Teeth: An in vitro study. Al-Azhar J of Dent Sci, 2023, 26.2: 247-253 
14. Julious SA. Sample sizes for clinical trials with Normal data. Statist. 
Med. 2004; 23:1921-1986. 

 
 
15. Hadwa , Shimaa M., et al. Assessment of clinical and radiographic efficiency of 
manual and pediatric rotary file systems in primary root canal preparation: a 
randomized controlled clinical trial. BMC Oral Health, 2023, 23.1: 687 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 تقييم األداء السري رى ,ورضا األبوين ,وصحة ال
لثة,والتأثيرات البكتيرية لتيجان 
 البيوفلكس والتيجان اللبية
مقارنة ب تيجان الزيركونيا سابقة التجهيز فى االضراس اللبنية
المعالجة لبيا : دراسة سريرية عشوائية 
خطة بحث مقدمة الى كلية طب األسنان- بنين القاهرة، جامعة األزهر، 
 كجزء من مقومات الحصول على
درجة الدكتوراه فى تخصص طب أسنان األطفال 
 
 
 مقدمة من الطبيب 
 كريم رجب عبدهللا الحصرى 
بكالوريوس طب الفم واألسنان،
2012
 م، كلية طب االسنان، جامعة طنطا 
     ماجستير طب أسنان األطفال،
2022م، كلية طب االسنان، 
 جامعة طنطا 
    ضابط طبيب أسنان بالقوات المسلحة  
   
لجنة األشراف 
د/ حمدى محمود بدر الدين 
, مدرس
قسم طب أسنان األطفال وصحة الفم 
كلية طب األسنان- 
 بنين–القاهرة-جامعة األزهر 
أ.د/ عالء الدين عبدهللا محمد اسماعيل 
 ,أستاذ
قسم طب أسنان األطفال وصحة الفم 
كلية طب األسنان- 
 بنين–القاهرة- جامعة االزهر 
 
قسم طب أسنان األطفال و صحة الفم 
كلية طب األسنان-بنين-القاهرة 
جامعة األزهر 
 م2023
   
- هـ 
1444