The Comparison of Transversal Dental Effects Between Rapid Maxillary Expansion and Surgically Assisted Rapid Maxillary Expansion Using Hyrax Appliance: a Cone-Beam Computed Tomography Analysis

Janice Joseph

The Comparison of Transversal Dental Effects Between Rapid

Maxillary Expansion and Surgically Assisted Rapid Maxillary

Expansion Using Hyrax Appliance: a Cone-Beam Computed

Tomography Analysis

Kaunas 2021

LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY

FACULTY OF ODONTOLOGY CLINIC OF ORTHODONTICS

The Comparison of Transversal Dental Effects Between Rapid

Maxillary Expansion and Surgically Assisted Rapid Maxillary

Expansion Using Hyrax Appliance: a Cone-Beam Computed

Tomography Analysis

The thesis was done

by student ... Supervisor ... (signature) (signature)

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Kaunas 2021

EVALUATION TABLE OF THE MASTER’S THESIS

OF THE TYPE OF SYSTEMIC REVIEW OF SCIENTIFIC LITERATURE

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No. MT parts MT evaluation aspects

Compliance with MT requirements and evaluation Yes Partially No 1 Summary (0.5 point)

Is summary informative and in compliance with the

thesis content and requirements? 0.3 0.1 0

2 Are keywords in compliance with the thesis

essence? 0.2 0.1 0

3 Introduction, aim and

tasks (1 point)

Are the novelty, relevance and significance of the

work justified in the introduction of the thesis? 0.4 0.2 0

4 Are the problem, hypothesis, aim and tasks formed

clearly and properly? 0.4 0.2 0

5 Are the aim and tasks interrelated? 0.2 0.1 0

6 Selection criteria of the studies, search methods and strategy (3.4 points)

Is the protocol of systemic review present? 0.6 0.3 0

7

Were the eligibility criteria of articles for the selected protocol determined (e.g., year, language, publication condition, etc.)

0.4 0.2 0

8

Are all the information sources (databases with dates of coverage, contact with study authors to identify additional studies) described and is the last search day indicated?

0.2 0.1 0

9

Is the electronic search strategy described in such a way that it could be repeated (year of search, the last search day; keywords and their combinations; number of found and selected articles according to the combinations of keywords)?

0.4 0.1 0

10

Is the selection process of studies (screening, eligibility, included in systemic review or, if

applicable, included in the meta-analysis)

described?

0.4 0.2 0

11

Is the data extraction method from the articles (types of investigations, participants, interventions, analysed factors, indexes) described?

0.4 0.2 0

12

Are all the variables (for which data were sought and any assumptions and simplifications made) listed and defined?

0.4 0.2 0

13 Are the methods, which were used to evaluate the

information is to be used in data synthesis, described?

14 Were the principal summary measures (risk ratio,

difference in means) stated? 0.4 0.2 0

15 Systemiza-tion and analysis of data (2.2 points)

Is the number of studies screened: included upon assessment for eligibility and excluded upon giving the reasons in each stage of exclusion presented?

0.6 0.3 0

16

Are the characteristics of studies presented in the included articles, according to which the data were extracted (e.g., study size, follow-up period, type of respondents) presented?

0.6 0.3 0

17

Are the evaluations of beneficial or harmful outcomes for each study presented? (a) simple summary data for each intervention group; b) effect estimates and confidence intervals)

0.4 0.2 0

18

Are the extracted and systemized data from studies presented in the tables according to individual tasks?

0.6 0.3 0

19

Discussion (1.4 points)

Are the main findings summarized and is their

relevance indicated? 0.4 0.2 0

20 Are the limitations of the performed systemic

review discussed? 0.4 0.2 0

21 Does author present the interpretation of the

results? 0.4 0.2 0

22

Conclusions (0.5 points)

Do the conclusions reflect the topic, aim and tasks of

the Master’s thesis? 0.2 0.1 0

23 Are the conclusions based on the analysed material? 0.2 0.1 0

24 Are the conclusions clear and laconic? 0.1 0.1 0

25

References (1 point)

Is the references list formed according to the

requirements? 0.4 0.2 0

26

Are the links of the references to the text correct? Are the literature sources cited correctly and precisely?

0.2 0.1 0

27 Is the scientific level of references suitable for

Master’s thesis? 0.2 0.1 0

28

Do the cited sources not older than 10 years old form at least 70% of sources, and the not older than 5 years – at least 40%?

0.2 0.1 0

Additional sections, which may increase the collected number of points

29 Annexes Do the presented annexes help to understand the

analysed topic? +0.2 +0.1 0

30

Practical

recommen-dations

Are the practical recommendations suggested and

are they related to the received results? +0.4 +0.2 0

31

Were additional methods of data analysis and their results used and described (sensitivity analyses, meta-regression)?

+1 +0.5 0

32

Was meta-analysis applied? Are the selected statistical methods indicated? Are the results of each meta-analysis presented?

General requirements, non-compliance with which reduce the number of points

33

General

require-ments

Is the thesis volume sufficient (excluding annexes)?

15-20 pages (-2 points)

<15 pages (-5 points)

34 Is the thesis volume increased artificially? -2 points -1 point

35 Does the thesis structure satisfy the

requirements of Master’s thesis? -1 point -2 points

36 Is the thesis written in correct language,

scientifically, logically and laconically? -0.5 point -1 points

37 Are there any grammatical, style or

computer literacy-related mistakes? -2 points -1 points

38 Is text consistent, integral, and are the

volumes of its structural parts balanced? -0.2 point -0.5 points

39 Amount of plagiarism in the thesis. >20%

(not evaluated) 40

Is the content (names of sections and sub-sections and enumeration of pages) in compliance with the thesis structure and aims?

-0.2 point -0.5 points

41

Are the names of the thesis parts in compliance with the text? Are the titles of sections and sub-sections

distinguished logically and correctly?

-0.2 point -0.5 points

42 Are there explanations of the key terms

and abbreviations (if needed)? -0.2 point -0.5 points

43

Is the quality of the thesis typography (quality of printing, visual aids, binding) good?

-0.2 point -0.5 points

*In total (maximum 10 points):

*Remark: the amount of collected points may exceed 10 points.

Reviewer’s comments: ___________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ _______________________________________ ___________________________

TABLE OF CONTENTS

2. MATERIAL AND METHODS: ___________________________________________ 5-8

2.1 Literature search strategy: _____________________________________________ 5 2.2 Focus question: _______________________________________________________ 6 2.3 Types of publication: __________________________________________________ 6 2.4 Types of studies: ______________________________________________________ 6 2.5 Population: __________________________________________________________ 6 2.6 Data collection: _______________________________________________________ 7 2.7 Selection of studies: ___________________________________________________ 7 2.8 Eligibility criteria: ____________________________________________________ 9 2.9 Observational index: __________________________________________________ 9 2.10 Assessment risk of bias: _____________________________________________ 9

ABSTRACT

Objective: The aim of this systematic review was to compare transversal dental effects when using Hyrax appliance between rapid maxillary expanders and surgically assisted rapid maxillary

expanders for inter-molar, inter-premolar and inter-canine distances by a cone-bream computed tomography analysis.

Material and Methods: Electronic searches and screenings were done through these databases: PubMed, Science Direct, Google scholar, Oxford journals and Wiley online library on February 2021. According to the inclusion criteria, data was extracted from human studies, full-text articles from 2010 onwards and in the English language.

Results: There were 456 articles at the beginning but by rigorous screening through inclusion and exclusion criteria, 7 articles were chosen for this systematic review. A total of 124 patients were selected and the following comparative factors were used, inter-molar distance, inter-premolar distance, and inter-canine distance. Rapid maxillary expander had the most maxillary change in inter-molar distance while surgically assisted rapid maxillary expander had the highest change for inter-premolar and inter-canine distance.

Conclusion: Rapid maxillary expander was more effective for inter-molar distance and surgically assisted rapid maxillary expander was found to be more effective for inter-canine distance and inter-premolar. However, effectiveness for inter-premolar needs further studies conducted. Therefore, each case must be evaluated independently before deciding which treatment method.

1. INTRODUCTION

Currently rapid maxillary expansion is the mainstay in treating posterior crossbite. Maxillary constriction, which is the cause of most prevalent dental skeletal pathologies, is also treated with rapid maxillary expander (RME). Through the increased width and perimeter of the mouth as seen in Annex 1, RME increases volume in the nasal cavity to combat sleep apnea. [1] Posterior

crossbite occurs in 8-22% of patients requiring orthodontic treatment, and in up to 15% of patients of the general public. [2] Thus, combating this issue is one of the primary tasks for orthodontists, and the most conventional way is through the use of RME.

The RME method was first introduced in 1860 by Angell. This appliance on activation causes lowering of the palatal vault, fixing the nasal septum by dividing the outer walls of the nasal cavity. [3] Hyrax appliances are one type of RME commonly used in orthodontic treatment. [4] It is

described as a tooth-borne type (TB) appliance usually bonded to the premolars and molars. The Hyrax appliance requires daily activation and the adjustment of the four bands that keep the distractor attached. [5]

RME is usually used for growing patients because their facial skeleton is less resistant to expansion in comparison to mature adults. [3] Comparatively to other treatment options that impact the skeletal elements, RME generates a greater force which eventually leads to dental change and movement. [6] This movement occurs through the skeletal midpalate sutures of the maxillary opening. [7] Through further research it was determined that not only did RME cause dentofacial changes, but also craniofacial structural alterations. [8] This is because once fully activated, RME is considered an orthopedic force given that it exerts more than 7000 grams of force. [1]

stages of the patient’s life. SARME is commonly used in adulthood to overcome the hardening of ossified sutures that would be needed for maxilla expansion while RME is used in growing patients. [11]

Thus far there are few articles comparing the differences between RME and SARME. [12] Until the present moment, there are limited studies that the author has found after scouring literature articles comparing RME and SARME through CBCT examination. This is important since CBCT is approximately 60% more reliable in taking angular measurements. It is an equally important tool when examining pathologies of the crown, especially regarding maxillary transverse deficiency. [13] Thus the use of CBCT for comparison may enlighten us on how effective the Hyrax appliance is whilst comparing RME to SARME.

1.1 Aim:

The aim of this systematic review is to compare transversal dental effects when using Hyrax appliance between rapid maxillary expanders and surgically assisted rapid maxillary expanders for inter-molar, inter-premolar and inter-canine distances by a cone-bream computed tomography analysis.

1.2 Tasks:

• To compare transversal dental effects with a Hyrax appliance on whether rapid maxillary expander or surgically assisted rapid maxillary expander is more effective for inter-molar distance.

• To compare transversal dental effects with a Hyrax appliance on whether rapid maxillary expander or surgically assisted rapid maxillary expander is more effective for inter-premolar distance.

1.3 Hypothesis:

ABBREVIATIONS

RME - Rapid maxillary expander

SARME - Surgically assisted rapid maxillary expander

IMD - Inter molar distance

IPD - Inter premolar distance

ICD - Inter canine distance

SD - Standard Deviation

RCT - Randomised clinical trial

(mm) - Millimetres

1. MATERIAL AND METHODS

2.1 Literature search strategy

PRISMA guidelines [14] were used to determine the eligible studies for this systematic review. Studies collected were from the following databases: PubMed, Google Scholar, Science direct, Oxford journals and Wiley online library. The keywords and their different combinations used are seen in Table 1, along with the date accessed and the number of articles discovered. While using PubMed, a filter was active for articles between 2010-2021. There was only 1 researcher that conducted the selection process of the articles, and articles chosen were from the years 2012-2021, all in the English language and human studies.

Table 1. Keywords.

Data bases Keywords Search

date

Results

PubMed Search 1: (tooth borne SARME) OR (tooth borne SARME Hyrax) OR (SARME hyrax)

Search 2: (RME hyrax) OR (rapid maxillary expander hyrax) OR (hyrax CBCT) OR (tooth borne Hyrax) OR (tooth borne cone beam computed tomography) OR (tooth borne cone beam computed tomography Hyrax) Search 3: (RME SARME) OR (RME SARME HYRAX) OR (RME SARME CBCT) OR (Hyrax SARME cone beam computed tomography) OR (tooth borne)

24/2/21 28/2/21 1/3/21 158 Google Scholar

Search 1: (tooth borne SARME) OR (tooth borne SARME Hyrax) OR (SARME hyrax)

Search 2: (RME cbct) OR (RME hyrax) OR (tooth borne hyrax)

Search 3: (Hyrax SARME cone beam computed tomography) OR (SARME tooth borne) OR (SARME RME) 24/2/21 1/3/21 100 Science direct

Search 1: (Hyrax surgically assisted rapid maxillary expander) OR (surgically assisted rapid maxillary expander tooth borne) OR (SARME hyrax)

Search 2: (tooth borne cbct) OR (RME hyrax) OR (tooth borne Hyrax)

Search 3: (tooth borne SARME) OR (Hyrax SARME rapid maxillary expander) OR (RME SARME cbct)

27/2/21 1/3/21 108 Wiley online library

Search 1: (tooth borne SARME) OR (SARME hyrax) Search 2: (tooth borne RME) OR (Hyrax RME) OR (Hyrax tooth borne)

Search 3: (SARME RME) OR (SARME tooth borne) OR (SARME tooth borne Hyrax)

27/2/21 28/2/21

39

Oxford journals

Search 1: (SARME hyrax) OR (surgically assisted rapid maxillary expander tooth borne)

Search 2: (RME Hyrax) OR (tooth borne Hyrax) OR (rapid maxillary expander hyrax CBCT)

Search 3: (RME SARME) OR (SARME tooth borne) (SARME tooth borne hyrax)

28/2/21

2.2 Focus question

The following focus question was developed according to PICOS (population, intervention, comparison and outcome) of the study design as seen in Table 2.

Table 2. PICOS.

2.3 Types of publication

All studies that are used were found online as articles, in the English language as human studies.

2.4 Types of studies

The studies included were retrospective studies, a prospective clinical study, a prospective cohort study, a RCT, and a clinical study. All articles were published from 2012-2021. All these studies were human and either used Hyrax appliance for RME or SARME.

2.5 Population

Patients who needed Hyrax orthodontic appliances as part of their treatment plan. Description

Participants Patients with maxillary constricted arches/

deficiency

Interventions Treatment with Hyrax appliance

Comparisons Rapid maxillary expansions VS surgically

assisted rapid maxillary expansion

Outcomes First inter-molar distance, first inter-premolar

distance and inter-canine distance

Study Design Combination of retrospective studies,

prospective clinical study, prospective cohort study, RCT and clinical study

Focus question How effective Hyrax appliance is for transversal

2.6 Data collection

Information on articles were collected from: PubMed, Google Scholar, Science direct, Oxford journals and Wiley online library.

2.7 Selection of studies

After utilising the inclusion criteria, only the titles and abstracts of articles relevant were

2.8 Eligibility criteria

The inclusion criteria for assessment that was used:

• Articles were published within 10 years of starting this study (2010 onwards) • Hyrax expanders as tooth-borne type

• CBCT was the evaluation method in the study

• Comparison point on maxillary 1st _{molar must be between mesiobuccal cusps} • Comparison point on maxillary 1st _{premolar must be between buccal cusps} • Comparison point on maxillary canine must be between buccal cusps • Human studies

• Must be in the English language

• The measurement system is Millimetres (mm)

The exclusion criteria for assessment that was used: • Systematic reviews

• Meta-analysis

• Misleading title or abstract • In-vitro study

• Cephalometric analysis utilised as an investigatory method • Cast analysis as investigatory method

• Not full-text articles • Case analysis

2.9 Observational index

The main criteria that was investigated was the difference of IMD, IPD and ICD between RME and SARME through CBCT analysis. All data was checked at T1 (before the procedure) and T2 (after the procedure).

2.10 Assessment risk of bias

Table 3. Bias analysis results.

Here the modified Downs and Black checklist was utilised used to evaluate the methodological quality of randomized and non-randomized studies.

Author Reporting External

validity Internal Validity – bias Internal validity – confounding

Power Study type Total Rating

Toklu et al. (2015) 10 0 6 5 1 Prospective clinical study 22 Good Rinaldi et al. (2017) 11 0 5 5 0 Retrospective study 21 Good El et al. (2013) 10 0 4 4 0 Retrospective study 18 Fair Mosleh et al. (2015) 10 0 4 4 1 Clinical study 19 Good Nada et al. (2012) 10 0 5 5 0 Prospective cohort study 20 Good Kaylar et al. (2015) 11 0 5 5 0 RCT study 21 Good Sygouros et al. (2014) 10 2 5 4 0 Retrospective study 21 Good

The checklist has a total of 27 questions and is marked out of 28. [22] Quality of articles is then given a qualitative value from the following scoring intervals:

• 26-28 = Excellent • 20-25 = Good • 15-19 = Fair • <14 = Poor

All articles but one scored 0 for external validity, and only 2 articles had a Power score. However, as seen in table 3, all studies save one were rated ‘Good’ which was satisfactory for the purpose of this systematic review.

2. SYSTEMISATION AND ANALYSIS OF DATA

Data collection and analysis

Data collection was performed by a sole researcher and was managed by a supervisor to ensure that conflict of interest, or bias was not present. Each of the 7 articles included had to go through data extraction for the year of publication, number to patients, age, gender, intervention type with Hyrax appliance, its study type, the tooth used for measurement and duration as seen in Table 4.

Table 4. Systemization of data and characteristics.

The following table summarises the main characteristics of the studies utilised in this systematic review Author Year of

publication

Study Design Sample Size Mean Age (SD) Intervention Used Treatment Duration Tooth measurements Toklu et al. (2015) 2015 Prospective clinical study 13 of which: 8 females 5 males

14.3 (2.3) RME 3 months -Canine cusp to cusp, -1st _{premolar buccal cusp to} buccal cusp

-1st _{molar mesiobuccal cusp to} mesiobuccal cusp Rinaldi et al. (2017) 2017 Retrospective study 18 of which: 7 males 11 females

11.1 (1.25) RME 6 months -1st _{molar, mesiobuccal cusp to} mesiobuccal cusp El et al. (2013) 2014 Retrospective study 35 of which: 20 females 15 males Male = 14 (1.5) Female = 14.03 (1.46) RME Male = 27 months (3.4) Females = 24.7 months (3.89)

-Canine cusp to cusp -1st _{premolar buccal cusp to} buccal cusp

Mosleh et al. (2015)

2015 Clinical study 10 of which: 10 females

12 (0.6) RME 11-15 days -1st _{premolar buccal cusp to} buccal cusp

-1st _{molar mesiobuccal cusp to} mesiobuccal cusp Nada et al. (2012) 2012 Prospective cohort study 28 of which: 28 unspecified 24.5 (9) SARME 21.7 months (6.6)

-Canine cusp to cusp -1st _{premolar buccal cusp to} buccal cusp

-1st _{molar mesiobuccal cusp to} mesiobuccal cusp Kaylar et al. (2015) 2015 RCT study 10 of which: 6 males 4 females 19.3 (5.01) SARME End of active expansion phase

-1st _{premolar buccal cusp to} buccal cusp

-1st _{molar mesiobuccal cusp to} mesiobuccal cusp Sygouros et al. (2014) 2014 Retrospective study 10 of which: 10 unspecified

19.2 SARME 3-6 months -Canine cusp to cusp -1st _{premolar buccal cusp to} buccal cusp

3. RESULTS

7 studies were scientifically examined thoroughly for IMD, IPD and ICD differences before and after surgery with T1 being before surgery and T2 being after surgery. Four articles used were for RME while three were for SARME. They were measured in millimeters with standard deviation and in some cases, with inter-quartile range. P-values were also noted when relevant, when was p<0.05.

Table 5 shows Toklu et al. concluding that there was an increase of 8.51 mm between T1 and T2, but the p-value displays that it was not significant. Rinaldi et al. discovered also an growth of IMD for RME and the p-value was 0.00. The third study of El et al, it had the lowest difference before and after Hyrax treatment for IMD in either the RME or SARME group, with 2.9 mm. The result for this was also found to be important with a p-value of 0.00. For Nada et al. there was an increase in IMD, but it is the second lowest T2-T1, and their p result was not significant. Kaylar et al. states that in SARME there was definitely IMD expansion with results being noteworthy (p-value of 0.001). Whereas Sygouros et al. found there was also expansion when using the Hyrax appliance, but their results were not significant. Finally, Mosleh et al. had the most IMD expansion of 9.7 mm in both the RME and SARME groups, with its results being significant.

In the RME group, El et al. had the lowest change of 2.9 mm and the highest was Mosleh et al. with 9.7 mm. But in the SARME group, the smallest difference was 5.36 mm from Nada et al. and the peak change was 7.12 mm from Kaylar et al. So, although RME had the highest IMD difference, it also had the lowest. RME has the range of 2.9 mm–9.7 mm while SARME has a range between 5.36 mm–6.09 mm, a much smaller interval.

Table 5. Inter-molar distance results.

Here IMD results were extracted from the studies. T1 is before surgery and T2 is after surgery. This table contains the mean (mm) and SD/ IQR (mm) in the studies in the brackets.

Study Intervention T1 (mean(SD))

Mosleh et al. (2015) RME 39.8 (9.1) 49.5 (5.7) 9.7 (6.9) Nada et al. (2012) SARME 46.78 (3.5) 52.15 (3.2) 5.36 (2.6) Kaylar et al. (2015) SARME 45.78 (3.18) 52.91 (2.65) 7.12 (1.75) Sygouros et al. (2014) SARME 50.40 (2.25) 56.49 (3.62) 6.09 (2.39)

As seen below in Table 6, Toklu et al. had the greatest difference between RME and SARME for IPD of 7.48 mm with its value being significant. El et al. had the lowest change of 4 mm with p-vaule of 0.00. In addition, Nada et al. also shows no statistical difference even though there was an increase in IPD. Kaylar et al. on the other hand did have a p-value of 0.001 and had a similar amount of IPD increase as Nada et al. Sygouros et al. has no p-value significance but has similar expansion to Mosleh et al, though it had a statistically significant p-value of 0.046.

Throughout the studies, RME had the greatest change of IPD from T2-T1 of 7.48 mm with Toklu et al, and the least change of 4 mm from EL et al. On the other hand, SARME had the highest T2-T1 of 6.68 mm from Sygouros et al and the lowest of 5.9 mm from Nada et al. RME has a range between 4 mm-7.48 mm while SARME has 5.9 mm-6.68 mm. Demonstrating again, that SARME had the smallest range when compared to RME.

Table 6. Inter-premolar distance results.

Here IPD results were extracted from the studies. T1 is before surgery and T2 is after surgery. This table contains the mean (mm) and SD (mm) in the brackets.

Study Intervention T1 (mean(SD))

Finally, as seen in Table 7, Toklu et al. was one of the two studies for ICD that had statistically significant results. The other, El et al. had the lowest ICD change on 2.4 mm with a p-value of 0.00 whereas Nada et al. had the most expansion of 4.09 mm, closely followed by Sygouros et al. who had a difference on 3.95 mm.

When comparing RME to SARME, it is very clear that RME had the least amount of ICD change whereas SARME has nearly double the amount. RME has a range of 2.4 mm-2.47 mm while SARME has an interval of 3.95 mm-4.09 mm. Therefore, RME had the smaller range, though SARME’s was also small.

Table 7. Inter-canine distance results.

Here ICD results were extracted from the studies. T1 is before surgery and T2 is after surgery. This table contains the mean (mm) and SD (mm) in the brackets.

Study Intervention T1 (mean(SD))

4. DISCUSSION

The aim of this systematic review was to identify whether RME or SARME was more effective when using the Hyrax appliance treatment. The comparative factors used were transversal dental movement through IMD, IPD and ICD. They were compared using (mm) and CBCT as the investigatory method as it has been proven to be consistent in taking angular measurement. All 7 scientific pieces of research have shown that there is an increase in IMP, IPD and ICD when using the Hyrax appliance with both RME and SARME. Although there was not an even number for comparison, there was significant evidence to draw a reasonable conclusion. All articles were found with ‘good’ bias evaluation according to Hooper et al. [22] except El et al which was found to be ‘fair’. Fair is considered satisfactory and reliable for the purpose of this systematic review. Additionally, all included articles had a minimum of 10 participants. This establishes more comparable and reliable results as with a larger sample size, anomalies are more easily distinguishable.

According to this systematic review, for IMD, RME had the range T2-T1 of 2.9 mm–9.7 mm while SARME had an interval of 5.36 mm–6.09 mm. From this, we can understand that the SARME data collected was more consistent as the range is less variable than RME. However, RME can be stated to be the most effective in combination with the Hyrax appliance since it had the most amount of change from T1-T2. Gungor et al. also discovered similar results, with RME producing more transversal change than SARME however, they concluded there were no significant differences. [23] D'Souza also concluded the same, but it was stated that the SARME group was more likely to relapse [24] which alludes to SARME patients needing more overtreatment in the future. Thus overall, RME seems to be the most effective when using Hyrax appliances for IMD.

For IPD, RME has the range of 4 mm-7.48 mm but in this case, only 3 articles were used for both comparisons. The interval for SARME was 5.9 mm-6.68 mm. Again, SARME had the smallest range, demonstrating that its results could be more reliable since there would be a lower chance of anomalies. Nevertheless, like IMD, RME seems to be the most effective when using Hyrax

chance that the forces applied are similar for RME compared to SARME. However, Kurt et al. found for RME the mean was 5.86 mm (SD 1.69 mm) and for SARME the mean was 7.55 mm (SD 2.51 mm), clearly presenting SARME as being more effective with the Hyrax appliance for IPD. This could be because more correction was needed in the adult patients than the growing patients as the SAMRE group began with the lowest trans-arch measurements. [25] Hence for IPD, there needs to be more studies evaluated in order to have a concrete result concluding if RME or SARME is more effective using the Hyrax appliance, but it can be stated that SARME is more successful once cross-referencing with other studies was referred to.

For ICD, there were only 2 articles included for RME and SARME. So, the results can’t be as conclusive as IMD for example, where in total 7 articles were included. RME had the range of 2.4 mm-2.47 mm and SARME had a range between 3.95 mm-4.09 mm. This depicts that, unlike IMD, the Hyrax appliance is more effective with SARME as the highest number was 4.09 mm. This was concurred by Gungor et al. who also stated that SARME had nearly twice the amount of expansion for canines than RME, which reflects the findings of this systematic reviews. It was stated that it could be due to the separation of the maxilla in surgery which allowed for more expansion in the canine region. [23]

One of the main limitations of this systematic review is that the articles do not have a consistent duration between T1 and T2. This can be difficult to conclusively compare them with one another. However, all but one had a duration of minimum of 3 months. Mosleh et al has a time period of 11-15 days is a short duration time. The article was done in such a different way because they felt that the variable growth factor should not be included, [18] thus it still carries importance as a research article. Therefore, it is still a credible source of data since it is still measuring the effectiveness of the Hyrax appliance. Another limitation is Kaylar et al, [20] which had no specific time given for the duration of the study. However, we can deduce that it should be a minimum of 3 months, since the study stated that it started in December 2012 and ended in January 2014. The main concern is there is no official duration time, consequently making it hard to compare the results, as it only states there is an ‘active expansion phase’.

Although SARME has only one study, the results show nearly double the increase of nasal width when compared to RME. Altug-Atac et al. supported this by confirming nasal width having a greater change in SARME than RME. This was also concurred by their same department, who conducted a separate study and confirmed soft tissue nasal width also expanded more in SARME. They theorized that due to movement of the maxilla, there is triangular expansion due to rotation. It could also be less resistant because of surgical changes from the nasomaxillary and

pterygomaxillary structures. [26] However, it was found that when using RME to expand the maxilla, the nasal cavity also expands with it accordingly for another two years, so typically RME can also be used for patients who have trouble breathing. But SARME does not continue to expand, so they concluded that RME was more effective than SARME. [3] Gungor et al also found RME has a significant difference in upper nasal cavity width. It was indicated that it could be due to surgical intervention in SARME that affected the maxillary and nasal bone contacts. [23] Although the material collected in the studies indicates SARME had the greatest expansion, by

cross-referencing it is clearly implicated that RME will lead to greater nasal width expansion through Hyrax appliance, especially after two years, which wasn’t taken into much consideration in the SARME studies.

5. CONCLUSION

1) Non-surgical rapid maxillary expansion with a Hyrax appliance creates the most posterior expansion for inter-molar distance compared with surgically assisted rapid maxillary expansion with a Hyrax appliance.

2) Surgically assisted rapid maxillary expansion with a Hyrax appliance was more favourable for inter-premolar distance compared with non-surgical rapid maxillary expansion with a Hyrax appliance.

6. PRACTICAL RECOMMENDATION

Through this systematic review, it was discovered that the earlier you are able to identify maxillary deficiency the better. The Hyrax appliance treatment is more applicable in younger patients where the procedure is rapid maxillary expansion because IMD was achieved the most with it. This is due to rapid maxillary expansion patients being in their growth spurt, so the maxilla is able to adapt to the Hyrax appliance efficiently and have more transversal changes. Rapid maxillary expansion also has the added benefit of not being an invasive surgery as surgically assisted rapid maxillary

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28. Figure. 1: Hyrax appliance bonded to first molars and first premolars. Available from: https://www.researchgate.net/figure/Hyrax-appliance-bonded-to-first-molars-and-first-premolars_fig1_316466580

ANNEX 1

Procedure of rapid maxillary expansion [27]:

1. First, need to choose a type of expander, in this case Hyrax appliance as seen in Fig. 1.

2. Need to warn the patient before procedure that a diastema will occur – a gap between the anterior incisors. This is normal and to be expected for a successful treatment.

3. Also inform the patient that the diastema should naturally close during the retention period. 4. After fitting the Hyrax and checking for any strong discomfort, patient needs to be

instructed on how to activate the appliance very day. For Hyrax appliance, it is usually activated from front to back.

5. Normally, activate it twice a day (morning and night). The Dentist should show how to activate it. A small amount of discomfort is normal.

6. The patient should be checked on weekly.

7. Activation should last 2-3weeks and a retention period should be followed after for 3 months or more.

ANNEX 2

Procedure of surgically assisted rapid maxillary expansion [29]:

1. A two-layer horizontal incision is cut from the canine to the mesial side of the first molar, through the mucoperiosteum at the buccal vestibule. The first incision cuts through the epithelium and periosteum while the second incision cuts through the periosteum 6-8 mm under the first cut. This helps for a more secure healing of the wound.

2. Then from the lateral nasal wall, the nasal mucosa must be lifted. The bleeding can be controlled by nasal tampons.

3. On the lateral wall of the maxilla, a horizontal osteotomy is done of 5-6 mm above the apices of the teeth with round burs.

4. Then a device is used to make the bone cuts e.g, osteotome or microsaw. Retractors should be used to protect the infraorbital nerves. The cuts should extend from under the pyriform rim posteriorly to the maxillary tuberosity junction and pterygoid plate.

5. With the use of curved osteotome, the maxilla is separated from the pterygoid plate. That region to have moist gauzes to stop unnecessary blood loss until suturing is needed.

Fig. 2. Marking osteotomy route with bur

6. Also, sagittal palatal osteotomy is done. It goes from the midline of the alveolar bone to the posterior nasal spine. This is carried out by an incision in the labial frenulum, where a osteotome is places between the central incisors to get mobility of the anterior maxilla.

7. Release the anterior nasal spine and lateral nasal walls on both sides with osteotomes. Fig. 4. Separation with curved osteotome

8. Before osteotomies, the Hyrax appliance should be active to get palatal separation. The diastema should be seen after osteotomies are done intraoperatively.