Dento-skeletal Effects of Quadhelix Versus Mini-hyrax Expanders in Patients With Cleft Lip and Palate at the Mixed Dentition Stage: A Randomized Clinical Trial
Phase: NA
Conditions: Maxillary Expansion in Cleft Lip and Palate Patients, Dentoskeletal Effects After Expansion Using Two Different Expanders
Sponsor: Cairo University

 
 
27-05-2025 

 
 

 
 

 
I.   Administrative information: 
1.   Title:  
Dento-skeletal Effects of Quad-helix versus Mini-hyrax Expanders in Patients with Cleft Lip and 
Palate at the Mixed Dentition Stage: A Randomized Clinical Trial. 
2. Protocol Registration:  
……………………………………………………………………………………………………… 
3. Protocol version:  
October 2024, First Version 
4. Funding:  
Self-funding 
5. Roles and responsibilities: 
5.i. Prof. Hoda Mohammed Abd-EL-Aziz Attia, BDS, MSC, PhD (H.M.) (Main supervisor): 
Helped in formulating the final research point. Will provide statistical expertise in clinical trial 
design.  Will help in interpretation of results and drawing the conclusion of the study. 
 
5.ii. Dr. Mohammed Abd-El-Ghafour, BDS, MSC, PhD (M.A.) (Co-supervisor):  
Suggested the idea of the research. Will aid with patient follow-up and appliance construction. 
Will generate the random sequence. Will help in sample size calculation. Will assist in the digital 
model analysis and measurements. 
 
5.iii. Dr. Mahmoud Sherif Abd-El-Rahman, BDS (M.S.) (Principal investigator):  
Helped in formulating the final research point. Will be responsible for clinical examination, and 
the clinical section of the study, recruitment of sample, follow up of patients, writing the thesis, 
data management, interpretation of results and drawing conclusion. 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
II.  Introduction: 
6. Background and rationale: 
Research question: 
P:  Patients with cleft lip and palate at the mixed dentition stage. 
I:   Quad-helix Appliance 
C:  Mini-hyrax Appliance 
O:  Dentoskeletal effects 
 
What is the difference between Quad-helix and Mini-hyrax expanders in terms of dentoskeletal 
effects in patients with cleft lip and palate at the mixed dentition stage? 
 
Statement of the problem:  
Cleft lip and palate (CLP) is the most prevalent among all craniofacial anomalies, affecting one in 
every 700 births (1)  and disturbing the quality of life of more than 7 million people around the 
world.(2) Cleft lip and palate are defined as malformations characterized by the non-union of the 
upper lip and/or palate, either separately or in conjunction with another syndrome.(3) Its etiology 
is rather complex and definitely multifactorial, where complex interplay between genetic and 
environmental factors play a significant role in the incidence and cause of clefting.(3) Cleft lips 
can be unilateral or bilateral, and may involve the alveolus or palate.(3) Unilateral cleft lip shows 
a 2:1 left predominance.(3) 
 
Lip and palate surgical repairs are performed in the first months and years of life 
,respectively.(3)As a consequence, the growth and development of the maxillary segments are 
compromised by scar tissues, presenting a significant maxillary transverse deficiency with 
medially collapsed cleft segments accompanied with anterior crossbite or both anterior and 
posterior crossbites.(4) Most CLP patients present a narrower anterior than posterior maxillary 
arch frequently showing a crossbite in both canine and premolar areas and a normal occlusal 
transverse molar relationship.(4)  
 
Maxillary expansion is usually performed before the secondary alveolar bone grafting procedure. 
Expansion improves the maxillary arch morphology and causes the segmental alignment creating 
appropriate conditions for bone grafting surgery as well as correcting the posterior crossbites. An 
important treatment objective in cleft cases is to achieve greater anterior than posterior maxillary 
expansion since there is a greater anterior than posterior maxillary constriction in most of those 
patients. (5) Variable appliances have been used for maxillary arch expansion in cleft patients.  
- 
Hyrax expanders exert parallel forces to the alveolar bones and the maxillary complex, 
generating similar amounts of anterior as well as posterior expansion and might be 
indicated for patients with overall maxillary transverse deficiency. While with patients of 
greater anterior constriction, Hyrax expander must be frequently interrupted before the full 

 
correction of the anterior transverse deficiency in order to avoid the occurrence of a 
posterior buccal crossbite. (5) 
                                  
- 
Fan-shape expanders and mini-hyrax (supported on the first premolars and associated to a 
transpalatal arch cemented to the first molars) enhanced expansion in the maxillary 
anterior region and restricted posterior expansion. (6) 
 
- 
Mini-hyrax (supported on the first permanent molars) can expand anteriorly as well as 
posteriorly and was found comparable to hyrax. (7) 
 
Rationale for conducting the research: 
Regarding expansion in cleft lip and palate patients, very few clinical trials were found after 
searching literature and fewer randomized trials. This means that no enough evidence in literature 
is tackling expansion in cleft lip and palate patients. 
To the best of our knowledge, this study will represent the first RCT to compare the 
dentoskeletal effects of mini-hyrax vs quadhelix. Since cleft cases usually need greater anterior 
than posterior expansion, (5) both appliances are capable of anterior expansion (7)(8). 
Nevertheless, no other study compared how much anterior expansion could be accomplished by 
either appliance. 
Considering the expansion rhythm, a systematic review conducted by Luyten, Jonathan et al in 
2023 (9) concluded that SME and RME promote equal posterior expansion in cleft patients, but 
with SME, the anterior differential expansion is larger. (9) SME rhythm will be used in this study 
for more anterior expansion. 
Anteroposterior and vertical outcomes of maxillary expansion are also relevant for selecting the 
expander type. (10) No previous study, however, compared the anteroposterior and vertical 
cephalometric effects of RME and SME in patients with complete cleft lip and palate except 
Gregório L et al. in 2019 (10). In this study it was mentioned that no anteroposterior and vertical 
differences were observed between the effects of RME and SME in patients with bilateral cleft lip 
and palate.  
That’s why this study will be conducted following a randomized clinical trial design, investigating 
the effect of two maxillary expansion appliances in cleft lip and palate patients following a SME 
protocol. Also, anteroposterior and vertical skeletal effects will be explored. 
 
 
 
 
 
 
 
 

 
Review of literature:  
Expansion in unilateral cleft lip and palate patients 
Studies about expansion in unilateral cleft lip and palate patients began in 2012 by Aizenbud et al 
(11) who conducted a retrospective study about a reverse quad helix (Figure 1) appliance aiming 
at differential anterior maxillary expansion of the cleft area before bone grafting. The reverse quad 
helix incorporated 4 helical loops forming an inverse W-arch design. The spring is positioned 
posterior to the banded teeth; thus, the expansion effect is focused in the anterior maxillary region. 
The mean anterior occlusal expansion achieved by the reverse quad-helix is statistically 
significantly larger than that achieved in the posterior region, thus he concluded that the reverse 
quad helix is an efficient appliance for differential expansion of the anterior maxillary region as a 
preparatory stage for secondary bone graft procedures in unilateral cleft lip and palate-affected 
patients. 
 
Figure 1: Reverse quadhelix 
 
In 2014, Figueiredo DSF et al (6) conducted a CBCT study on unilateral cleft lip and palate patients 
to see the effect of 3 expanders: hyrax, fan-type, and inverted mini-hyrax supported on the first 
premolars (figure 2). He found that the hyrax expander showed better results for cleft patients 
requiring anterior and posterior maxillary expansion. The inverted mini-hyrax most effectively 
restricted posterior expansion, optimizing anterior expansion without causing as much buccal 
tipping of the supporting teeth as did the fan-type. 
 
Figure 2: Hyrax (a), Fan-shape expander (b), Inverted mini-hyrax (c) 
 

 
In 2014, Anna Júlia et al (12) evaluated the transverse effects of Hyrax and Haas appliances (figure 
3) and concluded that they increased the transverse dimensions of the upper dental arch in patients 
with cleft palate significantly, with no significant differences between them. 
 
 
Figure 3: Haas (a) and Hyrax Expanders (b)  
 
In 2016, Priscila Vaz Ayub et al (13) made a clinical trial to analyze the maxillary dental arch after 
rapid maxillary expansion in patients with unilateral complete cleft lip and palate and concluded 
that rapid maxillary expansion by Haas appliance produced similar changes in the patients with 
unilateral complete cleft lip and palate compared with the noncleft patients except for arch length 
and palatal depth that decreased after expansion in the children with oral clefts. 
 
Again in 2016, after his study in 2014 (6), Figueiredo DSF et al. (14) conducted a randomized 
clinical trial to test the effect of modified hyrax and inverted mini-hyrax without TPA (figure 4) 
in unilateral cleft lip and palate patients. The appliances tested were effective in the transverse 
expansion of the maxilla. However, these appliances should be better indicated to cleft cases also 
presenting posterior transverse discrepancy, since there was greater expansion in the posterior 
maxillary region than in the anterior one. 
 
Figure 4 : Modified Hyrax (a) and Inverted mini-hyrax without TPA (b) 
 
 
 

 
In 2016, Priscila Vaz Ayub et al (15) conducted an inter-center study to compare the occlusal 
changes of rapid maxillary expansion (RME) and slow maxillary expansion (SME) in patients 
with unilateral complete cleft lip and palate, by means of digital dental models. 
RME and SME produced similar dentoalveolar outcomes, with greater amount of expansion on 
RME group considering arch perimeter and arch distances at the region of permanent premolar 
and molars. 
 
Explanation for choice of comparators:  
Group 1: Quad-helix appliance:  
Quad-helix is one of the most commonly used appliances for slow maxillary expansion. The main 
advantage is that it does not depend on patient compliance. It is considered cost effective compared 
to other appliances. It provides versatility in achieving anterior or posterior maxillary arch 
expansion or both. (7) 
 
Group 2: Mini-hyrax appliance (supported on the first permanent molars):  
It’s a tooth –borne expander. The main advantage of this expander is that it does not irritate the 
palatal mucosa and is easy to keep clean that’s why it’s called HYRAX (Hygienic Rapid Expander. 
It can provide sutural separation of 11 mm. Each activation of the screw produces approximately 
0.2 mm of lateral expansion, and it is activated from front to back.). (16) 
It is stated that this design presents a greater anterior than posterior expansion, but a noteworthy 
expansion also occur at the molar region. (17) 
 
 

 
7. Objectives: 
Aim of the study: To compare the dentoskeletal effects of Quad-helix and Mini-hyrax in cleft lip 
and palate patients during mixed dentition. 
Hypothesis:  
Null hypothesis: There is no difference between Quad-helix and Mini-hyrax appliances in terms 
of dento-skeletal effects during maxillary expansion in cleft lip and palate patients at the mixed 
dentition stage 
 
8. Trial design: 
It is a randomized clinical two arm trial with 1:1 allocation ratio. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
III. Methods 
A) Participants, interventions & outcomes 
9. Study settings: 
This clinical study will be held in the orthodontic clinic, Faculty of Dentistry, Cairo University, 
Egypt. 
 
10. Eligibility criteria: 
Inclusion criteria: 
(1) Mixed dentition.  
(2) Both males and females.  
(3) Unilateral cleft lip and palate 
(4) Presence of maxillary constriction that needs maxillary expansion prior to secondary alveolar 
bone grafting. 
(5) Erupted first permanent maxillary molars. 
(6) Good periodontal health. 
(7) No previous orthodontic treatment. 
 
Exclusion criteria: 
 (1) Syndromic cleft lip and palate patients. 
 (2) Previous secondary alveolar bone grafting. 
 (3) Taking medications that influence growth. 
 (4) Absence of teeth to support the expansion appliance 
 
11. Interventions: 
After taking history, making clinical examination extra-orally and intra-orally and making sure 
that the patient is fulfilling the inclusion criteria, full records are taken including impressions 
(which will be used to make digital models after scanning), extra-oral and intra-oral photos, full 
skull CBCT. 
Bands selection is done for maxillary first molars. Impression is taken with the bands pinned to fix 
the bands in the alginate impression to provide a laboratory model for appliance fabrication by 
M.S. with the help of M.A. 
Group 1: Quad-helix group 
Quad-helix will be constructed using 0.036-inch stainless-steel wire soldered to bands on maxillary 
first molars and extending on palatal surfaces of upper teeth till the upper canines. 
The anterior crossbite will be measured as the distance from the cusp tip of upper canine to cusp 
tip of lower canine then the needed time for expansion will be calculated considering that the 
amount of activation for each appointment will be 6 mm (3mm per side) at a 1-month interval 
(8). Activations will be performed extra orally where the anterior extensions of the appliance will 
be activated against the premolar and canine palatal surfaces by using the helical loops of the QH 
appliance (8). 

 
This regimen is the applied in almost all conducted previous studies mentioned in the review part. 
When the time calculated for correction ends, we will stop activation and take impressions for 
digital models to see if real expansion occurred or not and so testing the efficiency of the two 
appliances. 
After that, if anterior crossbite correction was not yet achieved or a posterior crossbite still exists, 
activation of the appliance will continue till 2mm overcorrection at the canine region and at the 
molar region with the palatal cusp tip of the maxillary posterior teeth contacting the buccal cusp 
tip of the mandibular posterior teeth. We will then leave the appliance in situ for retention purposes 
for 3 months. 
After 3 months from the first CBCT we will take a second CBCT to see any bony changes. 
Group 2: Mini-hyrax group 
Mini-hyrax will be constructed with the wire extending along the palatal surfaces of upper canines 
and premolars then soldered to bands on maxillary first molars. 
The anterior crossbite will be measured as the distance from the cusp tip of upper canine to cusp 
tip of lower canine then the needed time for expansion will be calculated considering that the 
activation regimen is two turns per week (about 0.5 mm/week).  
When the time calculated for correction ends, we will stop activation and take impressions for 
digital models to see if real expansion occurred or not and so testing the efficiency of the two 
appliances. 
After that, if anterior crossbite correction was not yet achieved or a posterior crossbite still exists, 
activation of the appliance will continue till 2mm overcorrection at the canine region and at the 
molar region with the palatal cusp tip of the maxillary posterior teeth contacting the buccal cusp 
tip of the mandibular posterior teeth. We will then leave the appliance in situ for retention purposes 
for 3 months. 
After 3 months from the first CBCT we will take a second CBCT to see any bony changes. 
 
-Strategies used to improve adherence to activation regimen will be a sheet with a calendar from 
the day of appliance delivery for the patient to tick activation times daily. 
 
12. Outcomes: 
Primary outcome: 
Anterior transverse dento-skeletal changes for correction of anterior crossbite and gaining space 
for the secondary bone grafting. 
Secondary objectives 
1- Maxillary and mandibular anteroposterior measurements 
2- Vertical skeletal measurements 
 
 
 
 

 
Prioritization of Outcome 
Outcome 
Method of Measurement 
Unit of Measurement 
Primary outcome 
Anterior transverse     
dento-skeletal effects 
Digital models & CBCT 
Numerical 
Secondary outcomes 
1- Maxillary and 
mandibular anteroposterior 
measurements 
2- Vertical skeletal 
measurements 
Digital models & CBCT 
 
 
CBCT 
Numerical 
 
The method of aggregation of outcomes: Mean and standard deviation. 
13. Participant timeline: 
 
Study period 
Timepoint 
-t1 
0 
T1 
(After calculated treatment time) 
T2 
(3 months after first CBCT) 
Enrolment 
 
Eligibility screen 
 
Informed consent 
 
Allocation 
 
Initial records 
Bands selection 
 
Appliances delivery 
 
Impressions for digital models 
for primary outcome 
measurements 
 
 
Second CBCT for primary and 
secondary outcome 
measurements 
√ 
 
√ 
 
√ 
 
 
 
 
 
 
√ 
 
√ 
√ 
 
√ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
√ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
√ 
 
 
 

 
14. Sample size: 
Sample size will be calculated based on the relevant papers that is currently available. 
15. Recruitment: 
M.S. will recruit the patients from the outpatient clinic of Orthodontic dentistry department in         
Faculty of Dentistry, Cairo University by examining any mixed dentition cleft lip and palate patient 
to see whether the patient is eligible or not. 
 
B) Assignment of interventions 
16. Allocation: 
16a. Randomization: 
Sequence generation: 
A random sequence table will be generated by computer by M.A. in a 1:1 allocation ratio where the 
total number of patients will be divided on two groups before the study started. Each group will have 
numbers denoting the patients in the group for example: Group 1 has numbers 1,4,5…. 
16b. Allocation concealment mechanism: 
As patients enrolment started and fulfilling the inclusion criteria, each patient will be given a well-
sealed opaque envelope containing numbers from one to the total number of the sample size. The 
envelope contains the number according to which the patient will be allocated to her/his group.  
16c. Implementation 
As previously mentioned, the allocation sequence will be generated by M.A.  
According to the number in the well-sealed envelope, M.A will be contacted to implement the 
allocation. 
 
17. Blinding: 
Due to the nature of the study, the operator and the patients could not be blinded. The outcome assessors 
and the data analyst were totally blinded from the nature of the clinical trial. 
 
C) Data collection, management, and analysis: 
18. Data collection methods: 
M.S. will collect the baseline data through a diagnostic chart for every patient. M.S. will be blinded to 
results. M.A will make outcome measurements at baseline, T1 and T2  from the digital casts and the 
CBCT. 
A 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: 
Data entry will be carried out by M.S. and revised by co-supervisor. All data will be stored on 
a computer and will be encrypted using a password. This will be done to allow accurate data entry 
through revision and protect data from being incorrectly used. Data will be packed up on another 
storage device to prevent it from being lost. 
 
20. Statistical methods: 
The significance level will be set at P ≤ 0.05. Statistical analysis will be performed with IBM® 
SPSS® Statistics Version 20 for Windows. Handling of data will be done using Microsoft Excel 
software.  
Inter-class Correlation Coefficients (ICC) will be calculated to detect the intra and inter observer 
reliability of the measurements in the study.  
Data will be explored for normality using Kolmogorov-Smirnov and ShapiroWilk tests. According to 
the behavior of the data (either parametric or nonparametric), the suitable statistical test will be 
selected.  
 
D) Data monitoring: 
21. Monitoring 
Co-supervisor will monitor this study. 
 
22. Harms 
M.S. should inform participants about the possible harms, if present (ex: soft tissue inflammation or 
lacerations). Participants are allowed to contact the operator at any moment through telephone. The 
data will be reported. 
 
23. Audit 
In the present trial, auditing will be done by the main and co-supervisor to assure quality of the 
research methods, and interventions. 
 
 
 
 
 
 
 
 
 

 
IV. Ethics and dissemination 
24. Research ethics approval 
Application forms for carrying out the clinical trial, checklist, and informed consent of Research 
Ethics Committee (CREC) Faculty of Dentistry, Cairo University will be retrieved and filled, then will 
be delivered for (CREC) committee for approval, this is done to prevent any ethical problems during 
the study or any harm for any of the participants. 
 
25. Protocol amendments 
If a new protocol will be used a protocol amendment will be submitted, containing a new copy of 
the new protocol and brief explanation about the differences between it and the previous protocols. 
If there is a change in the existing protocol that affect safety of subjects, investigation scope or 
scientific quality of the trial, an amendment containing a brief explanation about the change will 
be submitted. If a new author will be added to accomplish the study, an amendment including the 
investigator’s data and qualifications to conduct the investigation will be submitted to prevent 
ghost authorship. 
 
26. Informed consent 
M.S. is responsible for admitting and signing the informed consents during the enrolment day. 
 
27. Confidentiality 
Name and personal data of the participants will not appear on the protocol form and will be 
maintained secured for 10 years after the trial. This is done for the protection of participants’ privacy 
and civil rights. 
 
28. Declaration of interest 
There is no conflict of interest, no funding or material supply from any parties. 
 
29. Access to data 
Access to final data will be allowed to the operator, main supervisor and co-supervisor of the 
study who are not involved in assessment of the outcome. 
 
30. Post-trial care 
Patients will be followed up 3 months after treatment. 
 
31. Dissemination policy 
A full protocol will be published online in Clinicaltrials.gov to avoid repetition and to keep the 
integrity of the research work. Thesis will be discussed in front of the judgment committee. The study 
will be published to report the results of this clinical trial 

 
V. Appendices 
32. Informed consent 
A model of informed consent by (CREC) Research Ethics Committee, Faculty of Dentistry, Cairo 
University will be used in this study.  
 
VI. Statement of originality 
33. Statement of originality 
To the best of our knowledge, this study is the first randomized clinical trial to evaluate the 
dentoskeletal effects of quad-helix and mini-hyrax using SME protocol and determining their efficiency 
by measuring transverse changes on digital casts after the calculated correction time and evaluating 
whether true correction have occurred or not. Also this study will use both CBCT and digital casts for 
accurate analysis. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
VI. References 
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inequalities: challenges in the prevention and management of orofacial clefts and 
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2. IPDTOC Working Group. Prevalence at birth of cleft lip with or without cleft palate: data 
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3. Mahdi A. Shkoukani, Michael Chen AV. Cleft Lip – A Comprehensive Review. Front 
Pediatr 2013:1: 53. 
4. Silva Filho OG, Ramos AL, Abdo RC. The influence of unilateral cleft lip and palate on 
maxillary dental arch morphology. Angle Orthod 1992;62:283-90. 
5. Townend PI. Technique of rapid expansion in patients with cleft lip and palate. Br J 
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