Rimaz Abi Hussein
Fifth year, Group 14A comparison of the dentoskeletal changes with Twin-Block
versus Herbst functional appliance treatment in patients with
Class II malocclusion: A systematic review
Master thesis
Supervisor: Professor Arūnas Vasiliauskas
FINAL MASTER‘S THESIS IS CONDUCTED AT THE DEPARTMENT OF
ORTHODONTICS
STATEMENT OF THESIS ORIGINALITY
I confirm that the submitted Final Master‘s Thesis: “A comparison of the dentoskeletal changes with Twin-Block versus Herbst functional appliance treatment in patients with Class II malocclusion: A systematic review”
1. Is done by myself.
2. Has not been used at another university in Lithuania or abroad.
3. I did not use any additional sources that are not listed in the Thesis, and I provide a complete list of references.
I confirm by e-mail, and the work will be signed after the end of the quarantine and emergency situation due to the COVID-19 pandemic in the republic of Lithuania.
(date) (autthor‘s full name) (signature) 00-00-2020 Rimaz Abi Hussein
CONCLUSION OF FINAL MASTER‘S THESIS ACADEMIC SUPERVISOR
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(date) (author‘s full name) (signature) 00-00-2020 Rimaz Abi Hussein
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(date of approval) (name of the Department and full name of the Head of the Department) (signature) 00-00-2020 Department of Orthodontics
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LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY
FACULTY OF ODONTOLOGY CLINIC OF ORTHODONTICS
A comparison of the dentoskeletal changes with Twin-Block versus Herbst functional appliance treatment in patients with Class II malocclusion: A systematic review
Master thesis
The thesis was done
by student ……… Supervisor……… (Signature) (signature)
………. ……… (name, surname, year, group) (degree, name, surname)
EVALUATION TABLE OF THE MASTER’S THESIS
OF THE TYPE OF SYSTEMIC REVIEW OF SCIENTIFIC LITERATURE
Evaluation:... Reviewer: ...
(Scientific degree. Name, Surname)
Reviewing date: ... 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 Introduc-
tion, 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 are 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
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-analysispresented? +2 +1 0
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)
<15pages (-5points) 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
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Reviewer’s comments: ___________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ _____________________________________________________________________
Reviewer’s name and surname Reviewer’s signature _______________________________ _________________________
TABLE OF CONTENT
ABSTRACT ... 8 1. INTRODUCTION ... 9 1.1 Aim ... 10 1.2 Objectives: ... 10 1.3 Hypothesis: ... 10 ABBREVIATIONS ... 11CEPHALOMETRIC INDICES DESCRIPTION ... 12
2. SEARCH METHODS AND STRATETGY ... 15
2.1 Focus Question ... 15
2.2 Types of publications ... 15
2.3 Types of studies ... 15
2.4 Population ... 15
2.5 Data collection ... 16
2.6 Literature search and screening ... 16
2.7 Selection of studies ... 17
2.8 Inclusion and exclusion criteria ... 17
2.9 Assessment of risk of bias ... 19
2.10 Bioethics approval ... 19
3. RESULTS ... 20
3.1 Study Selection ... 20
3.2 Characteristics of studies and systemization of the data ... 20
3.3 Evaluation of data ... 22
3.4 Comparison of cephalometric indices ... 24
3.5 Individualization of results from each study ... 24
4. DISCUSSION ... 27
5. CONCLUSIONS ... 30
6. PRACTICAL RECOMMENDATIONS... 31
7. REFERENCES ... 32
8
A comparison of the dentoskeletal changes with Twin-Block versus Herbst functional appliance treatment in patients with Class II malocclusion.
A systematic review
ABSTRACT
Objectives: To evaluate which treatment option permits a more benefitial dental and skeletal changes among patients with Class II maloclussion treated with Twin-Block appliance and Herbst appliance.
Materials and methods: Articles were collected from PubMed/Medline, Cochrane library and EBSCO publishing databases. It included studies and humans and published in English language.
Results: At first, a total of 150 articles resulted from the electronic search. Then, after removing the duplicates and applying the inclusion and exclusion criteria, a total of seven articles were qualified for this systematic review. The comparison was performed according to the cephalometric indices. The dental changes showed no significant difference between the patients treated with Herbst appliance and Twin-Block appliance. Meanwhile, the skeletal changes were significantly different between functional treatment groups with the mandible showing more beneficial results with Twin-Block appliance then Herbst appliance.
Conclusion: Treatment with Twin-Block appliance gives a more beneficial skeletal change on patients with Class II malocclusion than treatment withHerbst appliance.
9
1. INTRODUCTION
The most basic occlusal conceptis when the teeth of the lower jaw comes in contact with those in the upper jaw in any functional relation. A malocclusion is a condition where there is a deflection from the normal relation from the teeth to other teeth: either in the same arch and/or to the teeth in the opposite arch.
Class II malocclusion is identified by an incorrect relationship of maxillary dental arch and mandibular dental arch antero-posteriorly which can be due to skeletal or dental abnormalities, or a combination of both. [1-3] It is considered to be one of the most common orthodontic malocclusions. [4] Many factors can lead to the development of Class II malocclusion: mandibular retrognathism has the highest frequency among these factors.
Class II treatment is available by many strategies. Most orthodontists tend to use an appliance that affects a specific part of the craniofacial skeleton as a treatment protocol. [5] Functional appliance therapy aim to encourage the growth of the mandible in a beneficial direction or to redirect it. The major difference between several orthopaedic appliances in the treatment effects are related to the wearing duration, fabrication technique and construction bites. Out of many fixed and removable functional appliances, Herbst and Twin-block are the most capable to correct a Class II malocclusion. [6]
Herbst appliance, originally made by Emil Herbst in the early 1900s, [7] later reintroduced in the late 1970s by Hans Panchez. [8] Twin-block appliance, created in the late 1970s by Willian Clark. [9,10] Twin-block is the most used appliance in UK [11] while Herbst is the most preferred appliance in USA. [12]
Twin-block treats Class II malocclusion by affecting the way of mandibular growth stimulation and it has a slight effect on the teeth and the alveolar bone. [13-17] Twin-block is a removable functional appliance and treatment success relies on patient’s extensive cooperation; the discontinuation rates range between 9% and 15%. [18-20] Herbst appliance is a solution for patient’s noncompliance: it’s a fixed functional appliance that guaranties a full-time wear. [21]
However, minimal studies have been carried out to compare the dentoskeletal effect of Twin-block and Herbst appliance and previous studies have not totally examined the effect of both functional appliances together in one review. The study aimed to find which appliance provides the patients with more profitable improvements.
10
1.1 Aim
The aim of this systematic review was to compare the dentoskeletal changes after orthopaedic treatment for correction of a Class II malocclusion performed with removable (Twin-Block) and fixed (Herbst) functional appliances.
1.2 Objectives:
▪ To evaluate treatment for correction of a Class II malocclusion with Twin-Block appliances and Herbst appliances and to estimate which treatment option permits a better dental changes according to the cephalometric indices.
▪ To evaluate treatment for correction of a Class II malocclusion with Twin-Block appliances and Herbst appliances and to estimate which treatment option permits a better skeletal changes according to the cephalometric indices.
1.3 Hypothesis:
The hypothesis of this systematic review is that patients treated for correction of a Class II malocclusion with Twin-Block appliances have better dental and skeletal changes than the ones that did undergo a treatment with Herbst appliances.
11
ABBREVIATIONS
TB-Twin-Block H-Herbst applianceC-Control group F-Forsus appliance DC-Data collection T-Time ii-Incision inferius is-Incision superius OL-Occlusal line
OLp-Occlusal line perpendicular
A-Most concave point on the anterior maxilla B-Most concave point on the mandibular symphysis S-Midpoint of the sella turcica
N-Most anterior point on the anterior the frontonasal suture Pg-Pogonion, most anterior part of the mandibular symphysis ms-Molar superius
12
CEPHALOMETRIC INDICES DESCRIPTION
Definition of the skeletal indices • Overjet: is/OLp minus ii/OLp
• Maxillary base: the projection of point A to the occlusal line perpendicular which is described as “A point/OLp”
• Mandibular base: the projection of point pogonion to the occlusal line perpendicular which is described as “pg/OLp”
• SNA: angle formed between the sella-nasion and point A • SNB: angle formed between the sella-naison and point B • ANB: angle formed between point A, nasion and point B Definition of the dental indices
• Maxillary incisor: Sagittal position of the maxillary central incisor within the maxilla which is calculated/described as “is/OLp minus A point/OLp”
• Mandibular incisor: Sagittal position of the mandibular central incisor within the mandible which is calculated/described as “ii/OLp minus pg/OLp”
• Maxillary molar: Sagittal position of the maxillary permanent first molar within the maxilla which is calculated/described as “ms/OLp minus A point/OLp”
• Mandibular molar:Sagittal position of the mandibular permanent first molar within the mandible which is calculated/described as “mi/OLp minus pg/OLp”
All landmarks are showed in Figure 1 and the measurement methods are presented in Figure 2.[22]
13
Figure 1. Explanation of the landmarks: Co, condylion; Ii, incision inferius; Is, incision superius; Mi, molar inferius; Ms, molar superius; pg, pogonion; A, point A; S, sella; OL, occlusal line; OLp, occlusal line perpendicular; me, menton; Gn, gnathion; Go, gonion.
14
Figure 2. Measurement methods: 1, total anterior face height (Na-Me); 2, lower anterior face height (ANS-Me); 3, lower posterior face height (S-Go); 4, ramus height (Co-Go); 5, corpus length (Go-Gn); 6, effective mandibular length (Co-Gn); 7, upper incisor to palatal plane (U1-PP); 8, upper molar to palatal plane (U6-(U1-PP); 9, lower incisor to mandibular plane (L1-MP); and 10, lower molar to mandibular plane (L6-MP).
15
2. SEARCH METHODS AND STRATETGY
2.1 Focus Question
The focus question was established and presented according to the PICOS framework in Table 1. [23]
Table 1. PICO table.
Population (P) Class II patients with retrognathic mandible. Intervention (I) Treatment with functional appliances.
Comparison (C) Comparison of treatment with Herbst appliances (fixed) and Twin block appliances (removable).
Outcome (O) Dental and skeletal changes during and after Class II malocclusion treatment.
Focus Question Does the type of the functional appliance (Twin-Block appliance or Herbst appliance) have different results in Class II malocclusion treatment?
2.2 Types of publications
The systematic review is based on studies on human and published in English language.
2.3 Types of studies
The systematic review included randomized controlled trials, controlled clinical studies and a prospective clinical study that described a comparison of the dentoskeletal changes of Class II patients treated with Herbst appliances and Twin-Block appliances.
2.4 Population
Class II patients who underwent a treatment with the functional appliances: Twin-Block or Herbst.
16
2.5 Data collection
Articles and information were collected from PubMed/Medline, Cochrane library and EBSCO publishing databases.
2.6 Literature search and screening
To find the studies, an electronic search was carried out through PubMed/Medline, Cochrane library and EBSCO publishing databases with a combination of the following keywords: (((class[All Fields] AND II [All Fields]) AND (("twins"[MeSH Terms] OR "twins" [All Fields] OR "twin"[All Fields]) AND block [All Fields] AND appliance [All Fields])) AND Dentoskeletal [All Fields] OR ((class [All Fields] AND II [All Fields]) AND ("orthodontic appliances, functional" [MeSH Terms]) AND ( ("orthodontic" [All Fields] AND "appliances" [All Fields] AND "functional" [All Fields]) OR "functional orthodontic appliances" [All Fields] OR ("herbst" [All Fields] AND "appliance" [All Fields]) OR "herbst appliance" [All Fields])) AND Dentoskeletal [All Fields] ) AND ((((Class [All Fields] AND II [All Fields]) AND (("twins" [MeSH Terms] OR "twins" [All Fields] OR "twin" [All Fields]) AND block [All Fields] AND appliance [All Fields])) AND ("orthodontic appliances, functional" [MeSH Terms] OR ("orthodontic" [All Fields] AND "appliances" [All Fields] AND "functional" [All Fields]) OR "functional orthodontic appliances" [All Fields] OR ("herbst" [All Fields] AND "appliance" [All Fields]) OR "herbst appliance" [All Fields])) AND Dentoskeletal [All Fields] ). (Table 2)
Table 2. Summary of the electronic search and the articles found
Search dates and search engine Keywords Results
18-3-2020 PubMed Class II, Twin block appliance and
Dentoskeletal
12
18-3-2020 PubMed Class II, Herbst appliance and
Dentoskeletal
65
18-3-2020 PubMed Class II, Twin block appliance,
Herbst appliance and Dentoskeletal 9
18-3-2020 Cochrane library Class II, Twin block appliance and
Dentoskeletal
11
18-3-2020 Cochrane library Class II, Herbst appliance and
Dentoskeletal
7
18-3-2020 Cochrane library Class II, Twin block appliance,
Herbst appliance and Dentoskeletal 0
17
18-3-2020 EBSCO publishing Class II, Twin block appliance and
Dentoskeletal
29
18-3-2020 EBSCO publishing Class II, Herbst appliance and
Dentoskeletal
13
18-3-2020 EBSCO publishing Class II, Twin block appliance,
Herbst appliance and Dentoskeletal 3
2.7 Selection of studies
The articles in this study have been classified in accordance to specific inclusion and exclusion criteria. The entire article selection process presented in Figure 3.
2.8 Inclusion and exclusion criteria Inclusion criteria for this study:
• Randomized controlled trials, controlled clinical studies and prospective clinical studies.
• Articles published in English language. • Humans trials
Exclusion criteria for this study: • Non-clinical study • Not relevant content
18
Figure 3. Prisma flow chart
Additional records identified through other sources
(n =1) • Records identified through
PubMed/Medline, Cochrane library & EBSCO publishing
• Key words used: “Class II’, “Twin block appliance”, “Herbst appliance”
and “Dentoskeletal” • Language: English
(n =149)
Full-text articles assessed for eligibility
(n =17) Records screened
(n =97)
Remove of duplication (n=53)
Records after duplicates removed (n = 97) Studies included in qualitative synthesis (n = 7)
In
clu
d
ed
E li gibil ityId
e
n
tific
ati
o
n
Sc
reen
in
g
Records excluded (n =80)• Not relevant title and abstracts • Systematic reviews • Not a clinical study
Full-text articles excluded, with reasons
(n = 10) • Not relevant
19
2.9 Assessment of risk of bias
The quality assessment tool for quantitative studies dictionary was used in this systematic review to evaluate bias. (Annex 1) (Table 3) [24]
Table 3. Risk of bias
References Selection Bias Study design Confounders Blinding Data collection method Withdraws and dropouts GIUNTINI et al.
[25] Fair Good Fair Poor Good Good
Latkauskienė et
al. [26] Fair Good Good Poor Good Good
BAYSAL et al.
[22] Fair Good Good Poor Good Good
Schaefer et al.
[27] Good Good Fair Poor Good Good
O’Brien et al.
[28] Good Good Fair Poor Good Good
Tarvade et al.
[29] Good Weak Fair Poor Good Good
Alvares et al.
[30] Good Good Fair Poor Good Good
2.10 Bioethics approval
20
3. RESULTS
3.1 Study Selection
The main search produced a total of 150 articles which 53 of it were duplicated. 17 articles from this search were chosen according to the inclusion and exclusion criteria: 80 were excluded. After reviewing the full-text articles, 7 articles were qualified and 10 others were excluded due to a not relevant content. The total sample size of included studies in this systematic review was 516 patients. [22,25-30] 196 patients underwent a treatment with Twin-Block appliance. 209 patients received a treatment with Herbst appliance. 65 patients served as a control group; they did not receive any orthodontic treatment. The rest 46 patients received a treatment with Forsus appliance. Control group and Forsus appliance group’s data were excluded from my comparison table.
3.2 Characteristics of studies and systemization of the data
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Table 4. Characteristics of studies and systemization of data
references Population Sample
Size Gender of the Population Country of Clinical Trial Age Group (Mean age ± SD)
Types of study Evaluation
methods
Follow up periods
Giuntini et al. [25] 28 TB
36 F 27 C
Total sample size 91
48 Females 13 Males Italy 12.4+ 1.0 TB 12.3 +1.2 F 12.2 +0.8 C controlled clinical study
Cephalometric Data was collected before the
treatment started and after 2 years of treatment.
Latkauskienė et al. [26] 40 H
+ 18 C
Total Sample Size= 58
27 Females 31 Males
Lithuania 13.6 ± 1.3 H prospective
clinical study
Cephalometric Data was collected before the
treatment started and after 12 months of treatment
Baysal et al. [22] 20 H
20 TB 20 C
Total sample size 60
30 Females 30 Males Turkey 12.74 ±1.43 H 13.0 ± 1.32 TB 12.17 ± 1.47 C randomized controlled trial
Cephalometric Data was collected before the
treatment started and at the end of it. (treatment period was not mentioned)
Schaefer et al. [27] 28 H
28 TB
Total sample size 56
42 Females 14 Males
Italy 12 ± 1.0 TB
12 ± 1.0 H
clinical trial Cephalometric Data was collected before the
treatment started and after 2 years of treatment.
O’Brien et al. [28] 110TB
105H
Total sample size 215
117 Females 98 Males
United Kingdom 11-14 randomized
controlled trial
Cephalometric Data was collected before the
treatment started and after 2 years
Tarvade et al. [29] 10 TB
10 F
Total sample size 20
-
India 13-17
-
Cephalometric Data was collected before the
treatment started and at the end of it. (treatment period was not mentioned)
Alvares et al. [30] 16 H
Total sample size 16 -
Canada Brazil
14,4-17.14
-
Cephalometric Data was collected before the
treatment started and after 2 and a half years of treatment.
*TB- twin-block appliance *H- Herbst appliance
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3.3 Evaluation of data
The qualified studies were collected and organized in order to compare it according to the cephalometric indices. (Table 5) (Table 6)
Table 5. Dental changes according cephalometric indices before and after treatment with functional appliances (mm) Indexes References Mandibular molars (Mean ± SD) (mm) Maxillary molars (Mean ± SD) (mm) Mandibular incisors (Mean ± SD) (mm) Maxillary incisors (Mean ± SD) (mm)
Before After Before After Before After Before After
Baysal et al. [22] H -25.55 ± 3.21 -24.33 ± 2.23 H -23.9 ± 2.05 -24.9 ±1.29 H 0.62 ± 3.41 2.39 ± 2.29 H 10.18 ± 2.37 9.23 ± 1.82 TB -26.62 ± 4.03 -26.27 ±1.79 TB -24.27 ± 2.25 -24.79 ± 1.57 TB -1.15 ± 4.56 -1.3 ± 3.00 TB 9.05 ± 1.82 8.6 ±1.81 O’Brien et al. [28] H -23.53 -22.46 H -21.80 -21.32 H -1.29 -0.35 H 8.50 6.07 TB -23.71 -22.25 TB -21.48 -21.08 TB -1.15 -0.59 TB 9.40 6.29
*H- Herbst appliance *TB- Twin-block appliance
*Mandibular molars- mi/OLp minus pg/OLp *Maxillary molars- ms/OLp minus A point/OLp
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Table 6. Skeletal changes according cephalometric indices before and after treatment with functional appliances
Indexes references Overjet (Mean ± SD) (mm) Maxillary base (Mean ± SD) (mm) Mandibular base (Mean ± SD) (mm) SNA (Mean ± SD) (degrees) SNB (Mean ± SD) (degrees) ANB (Mean ± SD) (degrees)
Before After Before After Before After Before After Before After Before After
Baysal et al. [22] H 8.68 ±2.84 3.6 ±2.73 H 80.95 ± 4.82 81.65 ±1.34 H 81.82 ± 4,85 84.25 ±2.25 H - - H - - H - - TB 8.42 ± 2.35 3.94 ±2.55 TB 81.55 ± 5.18 82 ±1.22 TB 83.32 ±6.69 87.94 ±3.09 TB - - TB - - TB - - O’Brien et al. [28] H 9.33 3.53 H 72.10 73.33 H 72.56 76.22 H - - H - - H - - TB 10.29 4.05 TB 71.46 73.31 TB 71.72 76.14 TB - - TB - - TB - - Schaefer et al. [27] H - - H - - H - - H 81.7 ±2.8 80.3 ±1.5 H 76.2 ±2.4 76.4 ±1.0 H 5.5 ±1.8 4.2 ±1.3 TB - - TB - - TB - - TB 82.0 ±3.3 81.0 ±1.2 TB 75.8 ±2.7 77.3 ±1.1 TB 6.2 ±1.7 3.7 ±1.2 Giuntini et al. [25] H - - H - - H - - H - - H - - H - - TB - - TB - - TB - - TB 81.6 ± 2.5 81.8 ± 1.3 TB 75.4 ± 2.9 77.9 ±1.2 TB 6.1 ± 1.8 3.5 ± 1.3 Latkauskienė et al. [26] H - - H - - H - - H 81.5 ± 2.9 81.2 ± 0.9 H 76.7 ± 2.4 77.5 ± 1.0 H 4.8 ± 1.9 3.7 ± 1.0 TB - - TB - - TB - - TB - - TB - - TB - - Tarvade et al. [29] H - - H - - H - - H - - H - - H - - TB - - TB - - TB - - TB 81.23 ± 2.20 82.5 ±2.68 TB 76.08 ±2.27 78.25 ±2.66 TB 5.75 ±0.96 4.25 ±0.62 Alvares et al. [30] H - - H - - H - - H 83.50 81.90 H 77.90 78.05 H 6.00 4.60 TB - - TB - - TB - - TB - - TB - - TB - -
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3.4 Comparison of cephalometric indices
The sagittal position of the mandibular central incisor within the mandible results showed difference between patients treated with Twin-Block appliance and Herbst appliance. While for the sagittal position of the mandibular permanent first molar within the mandible, sagittal position of the maxillary central incisor the maxilla and maxillary permanent first molar within the maxilla results showed no difference between patients treated with Twin-Block appliance and Herbst appliance.
SNA angle index results showed no significant difference between patients treated with Twin-Block appliance and Herbst appliance. Same for the overjet and the projection of point A to the occlusal line perpendicular. While SNB angle, ANB angle and the projection of point pogonion to the occlusal line perpendicular showed a difference between the patients treated with Twin-Block appliance and Herbst appliance.
The average treatment duration with functional appliances was 2 years. The range of the treatment duration in the qualified studies was not similar which made the comparison harder to evaluate.
3.5 Individualization of results from each study
Giuntini et al. [25] and Latkauskienė et al. [26] showed that the SNA, SNB and ANB values were almost similar at the beginning of the treatment in both treatment groups. SNB and ANB were the only values that showed a significant change during treatment with both appliances, though it was more noticeable for the sample treated with Twin-block appliance than for the group treated with Herbst appliance. SNA angle value at the end of treatment showed no significant difference in both groups.
Tarvade et al. [29] and Alvares et al. [30] showed a close similarity in the SNA, SNB and ANB values at the beginning of treatment in both treatment groups. SNA angle increased slightly in both treatment groups at the end of studies which made it not significant. SNB angle showed almost no change in the group treated with Herbst appliance, while in the sample treated with Twin-Block appliance, an advancement of 2.17 degrees the mandible was observed (p=0.002). ANB showed a similar decreased angle in both treatment groups. Patients in both groups received their treatment after the growth peak, which explains the results. It was
25
considered the patients in the Twin-Block study [29] that the patients are adolescents because of their age while in the article it was mentioned that the patients were growing.
Schaefer et al. [27] displayed an increase in the SNA angle in both groups, while this change showed no significant difference. Meanwhile in the SNB angle, patients who received a treatment with Twin-Block appliance manifested a mandibular advancement by1.5 degrees (p<0.01). Though this change was absent in the group who received a treatment with the Herbst appliance. Changes were seen in the ANB angle in both treatment groups. Although the improvement was more noticeable in the group that received an orthodontic treatment with the Twin-Block appliance.
A. Baysal et al. [22] showed a decreased overjet after treatment. Meanwhile it was not significantly different in both treatment groups. The same for the maxillary base: values manifested with a small change with no significant difference. Meanwhile in the mandibular base, an advancement of point pg was seen more in the Twin-Block appliance group (4.62 mm± 2.55mm) (p>0.05) than in the Herbst appliance group (2.42 mm± 2.6mm) (p>0.05). Both the sagittal position of the maxillary permanent first molar within the maxilla and the sagittal position of the mandibular permanent first molar within the mandible showed a change at the end of the treatment, but it was not significantly different in the comparison. Sagittal position of the mandibular central incisor within the mandible displayed a change in values in both groups, with the group treated with Twin-Block appliance showing lower values than the one treated with Herbst appliance. Sagittal position of the maxillary central incisor within the maxilla showed a slight change in this study in both treatment groups: both values showed no significant difference. While in the sagittal position of the mandibular central incisor within the mandible, patients who received a treatment with Herbst appliance (1.77 mm± 1.12mm) (p>0.05) showed a much better results than the one that received the treatment with Twin-Block appliance (0.15 mm±1.56 mm).
O’Brien et al. [28] showed an improvement in the overjet in both samples: Herbst appliance group had a decreased overjet by almost 6 millimetres(p>0.05), while in Twin-block appliance group the measured overjet was reduced by around the same value. These results showed no significant difference. The same for the projection of point A to the occlusal line perpendicular, there was a change after treatment but the values were not significant. Sagittal position of the maxillary permanent first molar within the maxilla showed a non-significant result in both treatment groups. The same for the sagittal position of the mandibular permanent first molar
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within the mandible and the Sagittal position of the mandibular central incisor within the mandible, results for both treatment group showed no significant difference. While in the sagittal position of the maxillary central incisor within the maxilla an improvement in the values were noticed in the treatment groups: more in the Twin-Block appliance sample than in the Herbst appliance group.
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4. DISCUSSION
The systematic review aimed to compare dental and skeletal potential benefits after orthopaedic treatment for correction of a Class II malocclusion with Twin-Block and Herbst functional appliances. The electronic search resulted only in 2 articles including the fixed and removable appliances in a same study where patients had the same base values at the beginning of the treatment within the similar age and that received the same treatment protocol.
The findings from these studies suggested that the Twin-Block appliance and the Herbst appliance provide almost the similar effects. While the removable functional appliance showed a better improvement/results then the fixed functional appliance. Therefore, by comparing all articles, there was no evidence of difference, between the orthodontic appliances, on the dental changes: both had a small dental effect. Herbst appliance had more effects on the mandibular incisors than the Twin-Block appliance. [22,28] Such result was approved by comparing it to another study made by Pancherz (1997) [31] where the authors described the effectiveness of the Herbst appliance by being able to move the upper teeth backward and the lower teeth forward. While during treatment with Twin-Block appliance, the lower incisors proclination occurred due to acrylic capping those teeth.[22] The explanation for such result is that the modification used on the Twin-Block appliance during the orthodontic treatment showed a significant difference. Other studies made by Mills et al. [32] and Toth et al. [33] showed a significant difference between a group treated with a Twin-Block appliance modified with a labial bow in order to control mandibular incisors proclination and a control group. [27,34] These studies proved that the removable functional appliance affected the lower incisors and the result received from Baysal et al. study [22] was due to the acrylic capping of mandibular incisors.
Baysal et al. [22] and O’Brien et al. [28] studies showed no significant difference in overjet reduction between both treatment groups: both appliances are effective in the treatment. The factor that does affect such result is the patient’s compliance.
Removable and fixed functional appliances apply a direct distal force on the upper jaw as the lower jaw reposition forward. Many studies proved that Herbst appliance and Twin-Block appliance do restrict the maxillary growth. [31,34] These studies explained the non-significant maxillary base changes.
Baysal et al. [22] and O’Brien et al. [28] revealed an increase in the mandibular length with both functional appliance: a greater result in the Twin-Block appliance group than in the Herbst
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appliance group. Schaefer et al. [27] showed a bigger increase in mandible’s forward position with Twin-Block appliance than with Herbst appliance group. Similar results where noticed in the three compared studies.
The included trials [25-27,29,30] showed no significant difference between the functional appliances on the maxillary growth. Such results are due to the maxillary growth restriction caused by the posterior forces mentioned before. Meanwhile in Tarvade al. [29] and Alvares et al. [30] the maxillary growth was restricted because the patients received the functional appliance treatment after growth peak. In other words, the SNA angle values were not significantly improved due to the limitation in the upper jaw’s growth. The mandibular advancement was more noticed in the Twin-Block appliance group than in the Herbst appliance group, which demonstrate the better improvement in SNB angle between the 2 treatment protocols. This explains the results of the studies regarding the different ANB angle value between the treatment groups.
O’Brien et al. [28] found some more characteristics to compare between the 2 functional appliances. Twin-Block appliancehas some advantages over Herbst. Regarding the fabrication price, the patients pays an average of 80 $ for Twin-Block appliance while for Herbst appliance it can cost him around 350 $. According to the emergency visits, the group treated with Herbst appliance registered almost 3 times more for maintenance and breakage repair than the group treated with Twin-Block appliance. Nevertheless, patient’s compliance has a major role in the treatment procedure. Twin-Block in this systematic review is used as a removable functional appliance. The non-compliance rates with it was twice bigger than the one with the Herbst appliance. Some studies had a dropout rate of 15% [27] and 50 % [36]. Patients are advised to wear the appliance 24 hours for the best prognosis, which include the time when they are eating and when they’re in public places. Herbst appliance has an advantage over Twin-Block appliance regarding the patient’s increased compliance.
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It is necessary to note the limitation faced while making this systematic review analysis. When it comes to treating Class II malocclusion patients, the first appliances that orthodontists prefer to use are twin-Block and Herbst because of their efficiency and effectiveness in this field. However, most of the studies included appeared to associate the previously described devices with the different ones that influenced the assessment of the results. Thus, further studies based on practical Twin-Block and Herbst appliances can be planned. Such distinctions between patients within the same age group and under the same skeletal growth patterns should be made. More randomized and prospective studies on these two functional appliances can help to achieve more productive results.
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5. CONCLUSIONS
• Class II patients treated with Twin-Block appliance had the same dental changes according the cephalometric indices in comparison with the patients treated with Herbst appliance.
• Class II patients treated with Twin-Block appliance manifested more favourable skeletal changes according the cephalometric indices in comparison with the patients treated with Herbst appliance.
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6. PRACTICAL RECOMMENDATIONS
Removable functional (Twin-block) appliance is a greater treatment of choice for a patient with Class II malocclusion. Doctors are supposed to explain to the patients the importance of the compliance and the procedures to maintain a good oral hygiene. Informing the general dentists and patient’s parents about the emergency management in case of incidents development, can reduce the inconvenience and ensure a comfortable treatment which will improve the efficiency and effectiveness of the functional appliances.
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7. REFERENCES
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2. Pfeiffer J, Grobety D. The Class II malocclusion: differential diagnosis and clinical application of activators, extraoral traction, and fixed appliances. Am J Orthod. 1975;68(5):499-544.
3. Sassouni V. A classification of skeletal facial types. Am J Orthod. 1969;55(2):109-23 4. Cozza P, Baccetti T, Franchi L, De Toffol L, McNamara JA. Mandibular changes
produced by functional appliances in Class II malocclusion: a systematic review. Am J Orthod Dentofacial Orthop. 2006;129(5): 599.e1-12.
5. Burkhardt DR, McNamara JA, Baccetti T. Maxillary molar distalization or mandibular enhancement: a cephalometric comparison of comprehensive orthodontic treatment including the pendulum and the Herbst appliances. Am J Orthod. Dentofacial Orthop. 2003;123(2):108-16
6. Firouz M, Zernik J, Nanda R. Dental and orthopedic effects of high-pull headgear in treatment of Class II, division 1 malocclusion. Am J Orthod Dentofacial Orthop 1992; 102:197-205
7. Herbst E. Atlas und Grundriss der Zahna¨rztlichen Orthopa¨die- Munich: JF Lehmann Verlag; 1910.
8. Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance. A cephalometric investigation. Am J Orthod 1979; 76:423-42
9. Clark WJ. The twin block traction technique. Eur J Orthod 1982; 4:129-38
10. Clark WJ. The twin block technique. A functional orthopaedic appliance system. Am J Orthod Dentofacial Orthop 1988; 93:1-18
11. O’Brien K. Is early treatment for Class II malocclusion effective? Results from a randomized controlled trial. Am J Orthod Dentofacial Orthop 2006;129(4): S64-S65. 12. Mahfouz M. Face Adaptation in Orthodontics. Open J Stomatol 2014;04(07):315-331. 13. Mills CM, McCulloch KJ. Treatment effects of the twin block appliance: a
cephalometric study. Am J Orthod Dentofacial Orthop. 1998; 114:15–24.
14. Toth LR, McNamara JA Jr. Treatment effects produced by the twin-block appliance and the FR-2 appliance of Fra¨ nkel compared with an untreated Class II sample. Am J Orthod Dentofacial Orthop. 1999; 116:597–609.
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15. Baccetti T, Franchi L, Toth LR, McNamara JA Jr. Treatment timing for Twin-block therapy. Am J Orthod Dentofacial Orthop. 2000; 118:159–170.
16. Singh S, Singh M, Saini A, Misra V, Sharma VP, Singh GK. Timing of myofunctional appliance therapy. J Clin Pediatr Dent. 2010; 35:233–240.
17. Brunharo IHVP, Quinta˜o CA, Almeida MAO, Motta A, Barreto SYN. Dentoskeletal changes in Class II malocclusion patients after treatment with the Twin Block functional appliance. Dental Press J Orthod. 2011; 16:40. e1–e8.
18. Illing HM, Morris DO, Lee RT. A prospective evaluation of Bass, bionator and Twin-block appliances. Part 1—the hard tissues. Eur J Orthod 1998; 20:501-16.
19. Lund I, Sandler PJ. The effects of Twin-Blocks: a prospective controlled study. Am J Orthod Dentofacial Orthop 1998;113: 104-10
20. Harradine NWT, Gale D. The effects of torque control spurs in twin-block appliances. Clin Orthod Res 2000; 3:202-9
21. Pancherz H. The mechanism of Class II correction in Herbst appliance treatment. Am J Orthod 1982; 82:104-13
22. Baysal A, Uysal T. Dentoskeletal effects of Twin Block and Herbst appliances in patients with Class II division 1 mandibular retrognathy. Eur J Orthod. 2014;36(2):164-72.
23. Moher D, Liberati A, Tetzlaff J, Altman DG, PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. PLoS Med 2009;6:(7): e1000097
24. Effective Public Healthcare Panacea Project. 2020. Quality Assessment Tool for Quantitative Studies.Available at:<https://www.ephpp.ca/quality-assessment-tool-for-quantitative-studies/>
25. Giuntini V, Vangelisti A, Masucci C, Defraia E, McNamara Jr J, Franchi L. Treatment effects produced by the Twin-block appliance vs the Forsus Fatigue Resistant Device in growing Class II patients. Angle Orthod. 2015;85(5):784-789.
26. Latkauskiene D, Jakobsone G. Immediate post-treatment crowned Herbst effects in growing patients. Stomatologija. 2012;14(3):89-92.
27. Schaefer A, McNamara J, Franchi L, Baccetti T. A cephalometric comparison of treatment with the Twin-block and stainless steel crown Herbst appliances followed by fixed appliance therapy. Am J Orthod Dentofacial Orthop. 2004;126(1):7-15.
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28. O’Brien K, Wright J, Conboy F, Sanjie Y, Mandall N, Chadwick S et al. Effectiveness of treatment for class II malocclusion with the herbst or twin-block appliances: a randomized, controlled trial. Am J Orthod Dentofacial Orthop. 2003;124(2):128-37. 29. Tarvade SM, Chaudhari CV, Daokar SG, Biday SS, Ramkrishna S, Handa AS.
Dentoskeletal Comparison of Changes Seen in Class II Cases Treated by Twin Block and Forsus. J Int Oral Health. 2014;6(3):27-31.
30. Alvares J, Cançado R, Valarelli F, Freitas K, Angheben C. Class II malocclusion treatment with the Herbst appliance in patients after the growth peak. Dental Press J Orthod. 2013;18(5):38-45.
31. Pancherz H. The effects, limitations, and long-termdentofacial adaptations to treatment with the herbst appliance. Semin Orthod. 1997;3(4):232-43.
32. Mills C, McCulloch K. Treatment effects of the twin block appliance: A cephalometric study. Am J Orthod Dentofacial Orthop. 1998 ;114(1):15-24.
33. Toth L, McNamara J. Treatment effects produced by the Twin-block appliance and the FR-2 appliance of Fränkel compared with an untreated Class II sample.Am J Orthod Dentofacial Orthop. 1999;116(6):597-609.
34. Trenouth M. Cephalometric evaluation of the Twin-block appliance in the treatment of Class II Division 1 malocclusion with matched normative growth data. Am J Orthod Dentofacial Orthop. 2000;117(1):54-9.
35. Illing H. A prospective evaluation of bass, bionator and twin block appliances. Part I - the hard tissues. Eur J Orthod. 1998;20(5):501-16.
36. Baton S, Cook PA. Predicting functional appliance treatment outcome in Class II malocclusions—a review. Am J Orthod Dentofacial Orthop 1997; 112:282-6.
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8. ANNEXES
Annex 1 Quality assessment tool for quantitative studies dictionary (QATQSD). 1. SELECTION BIAS
a. Good: The selected individuals are very likely to be representative of the target population and there is greater than 80% participation.
b. Fair: The selected individuals are at least somewhat likely to be representative of the target population; and there is 60 - 79% participation.
c. Poor: The selected individuals are not likely to be representative of the target population or there is less than 60% participation or selection is not described; and the level of participation is not described.
2. DESIGN
a. Good: will be assigned to those articles that described RCTs and CCTs.
b. Fair: will be assigned to those that described a cohort analytic study, a case control study, a cohort design, or an interrupted time series.
c. Weak: will be assigned to those that used any other method or did not state the method used.
3. CONFOUNDERS
a. Good: The data collection tools have been shown to be valid; and the data collection tools have been shown to be reliable.
b. Fair: The data collection tools have been shown to be valid; and the data collection tools have not been shown to be reliable or reliability is not described. c. Poor: The data collection tools have not been shown to be valid or both
reliability and validity are not described. 4. BLINDING
a. Good: The outcome assessor is not aware of the intervention status of participants; and the study participants are not aware of the research question. b. Fair: The outcome assessor is not aware of the intervention status of
participants; or the study participants are not aware of the research question. c. Poor: The outcome assessor is aware of the intervention status of participants;
and the study participants are aware of the research question.
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a. Good: The data collection tools have been shown to be valid; and the data collection tools have been shown to be reliable.
b. Fair: The data collection tools have been shown to be valid; and the data collection tools have not been shown to be reliable or reliability is not described. c. Poor: The data collection tools have not been shown to be valid or both
reliability and validity are not described. 6. WITHDRAWALS AND DROP-OUTS - a rating of:
a. Good: will be assigned when the follow-up rate is 80% or greater. b. Fair: will be assigned when the follow-up rate is 60 – 79%.
c. Poor: will be assigned when a follow-up rate is less than 60% or if the withdrawals and drop-outs were not described.
