Class II treatment with functional appliances: A meta-analysis of short-term treatment effects

Class II treatment with functional appliances: A meta-analysis of short-term treatment effects Nikhilesh R. Vaid, MDS, Viraj M. Doshi, MDS, and Meghna J. Vandekar, MDS The efficacy of functional appliances and changes produced by their application are still the subject of controversy. Functional appliances encompass a range of removable and fixed devices that are designed to create three-dimensional changes in the dentition and development of the jaws. This meta-analysis aims to analyze current literature up to January 2013 to provide evidence regarding the effects of functional appliances (removable FA and fixed FA). A literature survey of articles was initiated with meta-analysis using the random effect model (REM) along with heterogenesis and sensitivity analyses. Articles that met the inclusion criteria included 24 for RFA and 7 for FFA. The total number of subjects evaluated were 1469 (780 treated and 689 controls) for RFA and 353 (219 treated and 134 controls) for FFA. The results from the REM showed significant effects on mandibular skeletal (Co–Gn: 2.29 mm, p o 0.0005; SNB—1.431, p o 0.0005; and N Perp Pg—2.08 mm, p o 0.006) and dental changes (L incisor horizontal —1.34 mm, p o 0.0005). Significant maxillary dental changes (U molar horizontal—2.84 mm, p o 0.0005) were only observed for FFAs. Sensitivity and chi-square tests also confirmed these findings. The analysis of the effect of treatment by FFAs and RFAs versus untreated controls showed statistically significant short-term effects. (Semin Orthod 2014; 20:324–338.) & 2014 Elsevier Inc. All rights reserved.

Introduction lass II malocclusions form the majority of skeletal imbalances addressed in clinical orthodontics, and the most consistent finding for this malocclusion has been reported to be mandibular retrusion.1 Consensus on treatment protocols and effects of treatment of Class II malocclusion is still in a state of evolution; consequently, controversies still exist.2 Functional appliances encompass a range of devices (removable and fixed) that are designed with the intent to induce supplementary lengthening of mandible (both sagitally and vertically) and also alter mandibular position by stimulating growth at the condylar cartilage. This postulation has been subjected to different

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Department of Orthodontics, YMT Dental College & Hospital, Navi Mumbai, India. Address correspondence to Nikhilesh R Vaid, MDS, Ground Floor, New Blue Gardenia Hsg Society, Peddar Rd, Opp Jindal Mansion, Mumbai 400026, India. E-mail: [email protected] & 2014 Elsevier Inc. All rights reserved. 1073-8746/12/1801-$30.00/0 http://dx.doi.org/10.1053/j.sodo.2014.09.008

treatment protocols, sample sizes, and research designs that have led to some continued confusion. There have been more than a 100 different appliance designs that have been described in publications for Class II correction over more than 100 years. Despite their frequent use in treatment protocols throughout the world, it appears to many within our specialty that we do not have evidence to develop a consensus on their effects. Systematic reviews in the past have analyzed relevant literature (1995–2011). The results were inconclusive at large with limited clinical significance with respect to removable and fixed functional appliances.3 The difficulties with these studies, where RCTs were analyzed, related to inconsistencies in measuring treatment outcome variables due to non-standardized inclusion criteria and various cephalometric variables assessed by different authors. In addition, treatment durations varied, and treatment groups were subjected to comparisons with non-uniform control groups. Following a systematic review, data from individual studies may be pooled quantitatively and re-analyzed using the

Seminars in Orthodontics, Vol 20, No 4 (December), 2014: pp 324–338

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established statistical methods of a meta-analysis. The rationale for a meta-analysis is that, by combining the samples of individual studies, the overall sample size is increased; thereby, improving the statistical power of the analysis as well as the precision of the estimate values.4,5 Controversy specifically exists regarding mandibular changes resulting from functional appliances used for Class IIs. Some authors have reported increased mandibular length6–10 and changes in amount of condylar growth11–14 while others believe the altering mandibular growth cannot be achieved.15–17 It has also been stated that most corrections are due to dentoalveolar changes with small, but statistically significant amount of skeletal effects.18,19 Controversies concerning the effects on the maxilla also exist. Studies indicate inhibition of forward maxillary growth (the so-called headgear effect)17,20 while other authors disagree with this claim.21–23 These conflicting conclusions can be attributed to confounding study designs and lack of long-term data. The aim of this study was to use the highest level of evidence and research methodology to assess the skeletal and dental changes associated with removable and fixed functional appliances.

Materials and methods Meta-analysis Meta-analysis is a two-stage process. The first stage involves the calculation of a measure of treatment effect for individual studies with 95% confidence intervals (CI). The summary statistics from the meta-analysis are usually used to measure treatment effects, including odds ratio (OR), relative risks (RR), and risk differences. In the second stage of meta-analysis, an overall treatment effect is calculated as a weighted average of the individual summary statistics. Readers should note that data from the individual studies are not simply combined as if they were from a single study. Greater weightage is given to the results from studies that provide more information, because they are likely to be closer to the “true effect” we are trying to estimate. The weights are often the inverse of the variance (the square of the standard error) of the treatment effect, relating closely to sample size. The typical graph for displaying the results of a meta-analysis is called a “forest-plot.”

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Search strategies A survey of articles published up to January 2013, describing the effects of functional appliances on mandibular growth, was performed by using several electronic databases: Google Scholar, PubMed, Embase, and Cochrane Central register of controlled trials. The keywords used to identify the corresponding studies in the databases were Class II malocclusion and orthodontic functional appliances and randomized clinical trial. The reference lists included in the retrieved articles were also hand-searched to identify additional articles that might have been missed in the electronic bibliographic databases. No language restriction was applied during the identification process of published studies.

Selection criteria The inclusion and exclusion criteria of our study are given in Table 1. Articles were not selected if they did not meet the inclusion criteria, if they did not relate to this topic, or if they related but had a different aim. Abstracts, laboratory studies, descriptive studies, individual case reports, series of cases, reviews, studies of adult patients, controlled clinical trials, retrospective longitudinal studies, and previous meta-analysis (none present) were excluded. RCTs that included patients who had received previous or concomitant treatment for their Class II malocclusion were also excluded.

Data collection and quality analysis Data was collected based on the following items for the retrieved studies: year of publication, study design, materials (i.e., study sample, control sample, and type of functional appliance), age of patients at the start of treatment, methods of measurement, appliance wear, treatment/ observation duration, post-treatment observation, and authors' conclusions. A quality evaluation of the methodological soundness of each article was performed for RCTs, according to the methods described by Jadad et al.,5 with an extension of the quality appraisal to the CCTs. The following characteristics were used: study design, sample size and prior estimate of sample size, withdrawals (dropouts), method error analysis, blinding of measurements, and adequate statistics. The quality of the retrieved

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Table 1. Selection Criteria Inclusion Criteria

Exclusion Criteria

(1) Related human clinical trial (2) Randomized selection of samples (3) Concerned with functional appliances (removable of fixed) in therapy of Class II malocclusion (4) Had comparable untreated control group (5) Treatment effects not confounded by additional and concomitant treatment (headgears and fixed appliances) (6) Used cephalometric analysis at start and just after removal of functional appliance (7) Concerned with hard tissue changes (8) Concerned with soft tissue changes (9) Concerned with maxillary changes (10) Concerned with mandibular changes (11) Concerned with duration of treatment

studies was categorized as low, medium, or high. Two independent reviewers (V.M.D. and N.R.V.) assessed the articles, separately. The data were extracted from each article without any blinding to the authors, and intra-examiner conflicts were resolved by discussion of each article to reach a consensus.

Study characteristics Removable functional appliances Data was collected from publications featuring 1469 patients (780 treated versus 689 controls) with Class II malocclusion treated with removable functional appliances. The samples were heterogeneous for the number and ages of the participants. The number of treated subjects and controls ranged from 17 to 76 and from 17 to 74, respectively, and it was not possible to assess clinical sex heterogeneity. Every selected RCT analyzed a different type of removable functional appliance (e.g., Activator, Bionator, Twin block, Frankel 2, and Harvold Activator), but these devices appear to have similar mechanisms of action in protracting the mandible. Treatment or “observation” times ranged from 15 to 18 months.24,25 No article reported long-term results.

Fixed functional appliances Data was collected from publications featuring 353 patients (219 treated versus 134 controls) with Class II malocclusion treated with fixed functional appliances. These samples were

(1) Laboratory studies (2) Studies of adults (3) Studies performed using magnetic resonance imaging (4) Measurements of total mandibular length using point articulare (5) Treatment combined with extractions (6) Surgical treatment

heterogeneous for the number and ages of the participants. The number of treated subjects and controls ranged from 22 to 55 and from 20 to 30, respectively, and again it was not possible to assess clinical sex heterogeneity. Every selected RCT analyzed a different type of fixed functional appliance (e.g., Herbst and MARA), but these devices also have seemingly similar mechanisms of action in protracting the mandible. Treatment or observation times ranged from 6 to 12 months. Like the removable functional group, no article reported long-term results for fixed functionals. In our analysis, a distinction was made between statistically significant differences and clinically significant differences between treated and untreated groups for both removable and functional appliances.

Results Electronic searches for the effects of functional appliances for Class II patients identified the following items: 146 articles from PubMed, 45 from Cochrane Central Register of Controlled Trials, 29 from Ovid, and 1000 from Google Scholar. Articles that did not relate to our topic, related with a different aim, and those that were not RCTs, were excluded. Of the remaining potentially appropriate articles, 38 were duplicates, so 32 articles were identified as eligible articles to be included in the study. However, 29 of the 32 articles were withdrawn from consideration due to the following

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Table 2. List of Articles Selected for Removable Functional Appliances Author

Journal

Chen et al.26 Cozza et al.27 Marsico et al.3

AJODO 2002 AJODO 2006 AJODO 2011

exclusions: (1) lack of an untreated control group, (2) lack of random allocation of the untreated control group, (3) lack of cephalometric analysis, (4) cephalometric analysis that did not use anatomic condylion, (5) simultaneous use of additional treatments, (6) progress reports, (7) summary trials, or (8) related to this topic but with a different aim. Consequently, only three articles for removable functional appliances and two articles for fixed functional appliances met all eligibility criteria and were selected for the final analysis. In examining the three systematic reviews, each of the original articles evaluated in those reviews (i.e., original prospective studies) were then subjected to data analysis to get statistically comparable inferences. Hence, there were 24 original articles for RFAs and seven original for FFAs that were evaluated. These 31 articles were those included in the three systematic reviews and that also met our inclusion criteria; perhaps, making this one of the most exhaustive analyses on the topic. The analysis for the three articles that were selected for removable functional appliances (RFAs) are shown in Table 2 and those for fixed functional appliances (FFAs) are listed in Table 3. The selected articles were considered separately for removable and fixed functional appliances as they could not be compared directly as data had been analyzed with different statistics. Consequently, all 24 removable functional appliance articles and seven fixed functional articles that fulfilled the inclusion criteria are listed in Tables 4 and 5, respectively. The distribution of experimental

Table 4. List of Original Articles Statistically Evaluated in the Meta-Analysis for Treatment Effects With Removable Functional Appliances (RFAs) Author

Journal

Jakobsson and Paulin28 McNamara et al.22 McNamara et al.22 McNamara et al.29 Nelson et al.30 Nelson et al.30 Tulloch et al.24 Tümer et al.31 Tümer et al.31 Toth et al.10 Toth et al.10 Baccetti et al.20 Mills et al.32 Chadwick et al.33 Almeida et al.9 Almeida et al.9 Basciftci et al.21 Faltin et al.34 Janson et al.19 O’Brien et al.25 Cozza et al.35 Webster et al.36 O’Brien et al.25 Banks et al.37

EJO 1990 AJODO 1985 AJODO 1985 AJODO 1990 AJODO 1993 AJODO 1993 AJODO 1997 AJODO 1999 AJODO 1999 AJODO 1999 AJODO 1999 AJODO 2000 AJODO 2000 EJO 2001 AJODO 2002 AJODO 2002 EJO 2003 ANGLE 2003 EJO 2003 AJODO 2003 EJO 2004 AJODO 1996 AJODO 2003 AJODO 2004

subjects and types of appliances evaluated is provided in Table 6. The results of the analysis of changes exhibited by the early use of functional appliances are presented in Table 7.

Discussion The quest for the highest level of evidence for solutions to Class II malocclusions in growing patients has seen increasing volumes of data and resulting interpretations published over the past four decades. To derive data from an RCT in orthodontics is extremely difficult because of the sensitive ethical issue of leaving a control group of patients untreated. Furthermore, Table 5. List of Original Articles Statistically Evaluated in the Meta-Analysis for Treatment Effects With Fixed Functional Appliances Author

Table 3. List of Articles Selected for Fixed Functional Appliances Author

Journal

Chen et al.26 Cozza et al.27

AJODO 2002 AJODO 2006

McNamara et al.29 Pancherz38 Windmiller39 Franchi et al.40 Pangrazio-Kulbersh et al.41 Pangrazio-Kulbersh et al.41 O’Brien et al.25

Journal AJODO AJODO AJODO AJODO AJODO AJODO AJODO

1990 1982 1993 1999 2003 2003 2003

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Table 6. Subject Distribution and Appliances Evaluated Removable Functional Appliances (Activator, Bionator, Twin Block, Frankel 2, and Harvold Activator) Subjects

Fixed Functional Appliances (Herbst and MARA)

Control

Subjects

Control

Sample size 780 (range: 17–76) 689 (range: 17–74) 219 (range: 22–55) 134 (range: 20–30) Average treatment time (months) 17.52 17.31 10.6 10.51 Average treatment initiation age (months) 10.53 10.33 12.01 11.42

several items required in quality reviews with respect to blinding, clearly do not apply to orthodontics.5,42 Another issue that complicates our understanding of clinical realities is that long-term effects of growth and aging are difficult to evaluate. Obviously, functional appliances have been used by clinicians worldwide for treatment of the so-called underdeveloped mandible for a century. This has led clinicians to discuss them solely on ability to “grow mandibles.” Few developers of functional appliance or proponents of this theory have ever claimed that functional appliances are fertilizers for the mandibular crop. As for the other “optimists,”

they have subjected the results of their efforts to peer-reviewed scrutiny.6–17 So the belief in “growing mandibles” warrants serious skepticism. Are there any studies (animal or human) that have claimed and proved that the effects of functional appliances are solely due to a change in the size of the mandible? Absolutely not.43 The correction of Class II malocclusion is the result of a combination of various effects including condylar growth, maxillary growth restriction, glenoid fossa remodeling, gonial angle changes, and dentoalveolar changes (noted both in the upper and lower dentition), both in the sagittal and the vertical planes. Johnston44 has stated that functional appliances

Table 7. Subject Distribution and Details Evaluated Removable Functional Appliances (Activator, Bionator, Twin Block, Frankel 2, and Harvold Activator) Parameters

Number Sample of Studies Size

Maxillary skeletal changes Co–ANS (mm) 8 SNA (deg) 16 N Perp A (mm) 9 Maxillary dental changes U6 Horizontal 13 (mm) U6 Vertical (mm) 11 U1 Horizontal 12 (mm)

Advantage Over Control –

Fixed Functional Appliances (Herbst and MARA)

Statistical Significance/Clinical Significance

Number of Studies

Sample Size

Advantage Over Control

Statistical Significance/Clinical Significance

467 967 722

0.36 0.65

N/N N/N Y/N

4 5 4

226 268 226

0.52 0.45 0.95

N/N N/N Y/N

853

1.07

Y/Y

6

354

2.84

Y/Y

N/N Y/Y

4 4

225 236

597 811

2.47

0.84 1.47

N/N Y/N

Mandibular skeletal changes Co–Gn (mm) 21 SNB (deg) 18 N Perp Pg (mm) 9 Go–Po (mm) 9

1297 1089 722 479

1.61 0.85 0.32 0.52

Y/N Y/N N/N Y/N

6 5 4 5

353 268 226 311

2.29 1.34 2.08 1.33

Y/Y Y/N Y/Y N/N

Mandibular dental changes L6 Horizontal (mm) 14 L 6 Vertical (mm) 13 L1 Horizontal (mm) 11

856 656 755

– 1.5 0.56

N/N Y/N N/N

6 4 6

353 225 353

0.52 0.66 1.34

N/N Y/N Y/Y

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produce an instant forward shift of the mandible and, hopefully, a subsequent interdigitation of the occlusion will lock the position of the occlusion in Class I as mandibular growth occurs in the background to make permanent that “shift.” Hence, during the post-functional phase, it is postulated that growth of maxilla modulates mandibular displacement unless the dental compensative mechanism is again interrupted. Pancherz and Hansen45 and Franchi and Baccetti46 attempted to predict individual mandibular changes induced by functional jaw orthopedics in order to select parameters that would indicate that a particular type of patient may respond better to functional jaw orthopedics.46 They concluded that a Class II patient, at the peak of skeletal maturation, with a pretreatment Co–Go–Gn angle less than 125.51 may be expected to respond more favorably to functional jaw orthopedics. In the present study, we chose cephalometric values that have been analyzed in clinical trials and quantified across most of the studies selected. The effects of fixed and removable functional appliances, derived from these values, were subjected to statistical analysis. We elected to eliminate studies based on their lack of methodological soundness in a manner similar to Cozza et al.27 Therefore, we only included studies that reported anatomical condylion. All selected cephalometric values were standardized to a uniform scale that could be reliably compared and then subjected them to statistical analysis. The results obtained were categorized into four parameters: (a) maxillary skeletal changes, (b) maxillary dental changes, (c) mandibular skeletal changes, and (d) mandibular dental changes (Table 7). The clinical significance and statistical significance of the data in this meta-analysis was differentiated on the basis of the threshold value for a “clinically significant” change as reported by Cozza et al.27 A statistically significant linear change reported in a study had to be greater than 2 mm to be regarded as clinically significant.

Maxillary skeletal changes Maxillary skeletal changes are noted in Table 7 for three specific measurements: Co–ANS, SNA, and N perpendicular A. All selected studies concluded that functional treatment had either

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little or no effect on maxillary skeletal structures. In addition, there were also no statistically or clinically significant changes in maxillary length with the exception of reports by Tümer and Gültan31 on RFAs and McNamara et al.,29 describing FFAs (i.e., slight increases in Co–ANS).

Maxillary dental changes Maxillary dental changes are reported in Table 7 for three measurements: U6 Horizontal, U6 Vertical, and U1 Horizontal. All selected studies described functional jaw orthopedics as having a “headgear effect” on the upper posterior teeth. Distalization of the upper first molars was reported to be clinical significant, but statistically insignificant (average 1.07 mm for RFAs and 2.84 mm for FFAs). These studies also pointed out clinically and statistically significant lingual tipping of upper incisors (except for a report by Mills and McCulloch32). Upper incisor horizontal changes were both clinically and statistically for RFAs (2.47 mm) and statistically significant for FFAs (1.47 mm).

Mandibular skeletal changes Mandibular skeletal changes were reported for four measurements: Co–Gn (Man. length), SNB, N perpendicular Pg, and Go–Po (Table 7). An average increase of 1.61 mm in mandibular length was derived from among the selected samples. This change was statistically significant, but not a clinically significant change for RFAs. On the other hand, a change of 2.29 mm was both clinically and statistically significant for FFAs. All studies on FFAs also observed a change in corpus length and an increase in N perpendicular to Pg of 2.08 mm, both statistically and clinically significant. The exceptions to the general findings in the RFAs group were seen in a study by Janson et al.19 The mandibular values are influenced by skeletal maturity at the time of initiating treatment. It has previously been demonstrated that the effectiveness of functional treatment of mandibular growth deficiencies strongly depends on the biological responsiveness of the condylar cartilage, which in turn depends on the growth rate of the mandible (expressed as prepeak, peak, and postpeak growth rates with regard to the pubertal growth spurt).

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Figure 1. Maxillary skeletal and dental parameters evaluated.

Figure 2. Mandibular skeletal and dental parameters evaluated.

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Figure 3. Maxillary skeletal changes. (A) Co–ANS changes with removable functional appliances. (B) SNA changes with removable functional appliances. (C) N perpendicular A changes with removable functional appliances. (D) Co–ANS changes with fixed functional appliances. (E) SNB changes with fixed functional appliances. (F) N perpendicular A changes with fixed functional appliances.

Rabie et al.47 examined the association of SOX9 (a regulator of chondrocyte differentiation on type II collagen gene) related to forward positioning of the condyle in an animal model. The mandible was postured forward constantly (like that seen with fixed functional

appliances), and the number of replicating mesenchymal cells was seen to greatly influence the growth potential of the condyle and glenoid fossa. However, there were great variations noted, and the results of animal experiments cannot be directly applied to humans.

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Figure 4. Maxillary dental changes: (A) upper molar horizontal changes with removable functional appliances, (B) upper molar vertical changes with removable functional appliances, (C) upper incisor horizontal changes with removable functional appliances, (D) upper molar horizontal changes with fixed functional appliances, (E) upper molar vertical changes with fixed functional appliances, and (F) upper incisor horizontal changes with fixed functional appliances

Mandibular dental changes Mandibular dental changes for three measurements are noted in Table 7: L6 Horizontal, L6

Vertical, and L1 Horizontal. The only statistically significant mandibular dental changes noted were labial displacement of the lower incisors, specifically for FFAs (1.34 mm).

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Figure 5. Mandibular skeletal changes: (A) Co–Gn changes with removable functional appliances, (B) SNB changes with removable functional appliances, (C) N perpendicular Pg changes with removable functional appliances, (D). Go–Po/Pg changes with removable functional appliances, (E) Co–Gn changes with fixed functional appliances, (F) SNB changes with fixed functional appliances, (G) N perpendicular Pg changes with fixed functional appliances, and (H) Go–Po/Pg changes with fixed functional appliances.

Lower incisor proclination with FFAs is a commonly observed clinical phenomenon, and the results of the meta-analysis corroborate that finding.

Implications for clinicians This meta-analysis demonstrated that there were primarily dental changes associated with

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Figure 5. (continued)

functional appliances. In fact, the only significant skeletal finding was an increase in Co–Gn, but curiously only with fixed functional appliances, not removables. Additionally, FFAs also created flaring of lower incisors, so there appears to be a price to be paid (lost lower anchorage) for that minimal mandibular length increase. In contrast, a significant amount of upper molar distalization was noted with both RFAs and FFAs. The results from the present study also augment current evidence of the effects of one-phase versus twophase approaches.48–50

Implications for researchers The RCTs, suggested by O'Brien51 and Darendeliler,43 only showcase the average effect of an intervention on an average patient with an average condition. This might be useful information for a clinician treating an “average patient” and, averages are certainly useful to help practitioners from wandering too far off the path; however, caution is warranted in treating individual patients. Statistical and clinical readings are different, and dramatic changes that occur within some treated samples cannot be ignored. Most of the RCTs had inclusion criteria that had many variables between subjects. For example, in some studies, samples were chosen with a particular amount of overjet without considering the skeletal biotypes and growth patterns. For instance, a vertical grower will not respond in the same manner as a horizontal grower when wearing a standard functional appliance; thereby, confounding the statistics in the larger picture.

On further evaluation of these samples, the most successfully treated patients (25% top change category) demonstrated 41–51 of ANB change while the least 25% of successfully treated patients demonstrated only a 0.81–0.91 change.43 For 50% of the subjects, a 21 change in ANB holds minimal significance. To conclude, evidence and averages are a very important part of the picture, but not the total picture. In trying to describe the efficacy of an appliance, it should be noted that the nature of Class II malocclusions can be attributed to various three-dimensional permutations and combinations. A blending of such factors does tend to over-simplify the values derived from research publications. Studies that differentiate different divergence and rotation patterns perhaps will provide more useful information for the clinician. Another factor that may result in more homogenous results is a consensus on a composite cephalometric analysis to be used in trials to improve interpretations across studies.52 Simplistically speaking, we all know today that with the advent of 3D imaging, volumetric changes in all dimensions also need critical evaluation, data that 2D cephalometrics cannot provide. Finally, the CONSORT guidelines, if used uniformly to report all trials, will improve the database, potentially improving our clinical decisions.

Conclusions This meta-analysis evaluated the cephalometric values that signified the short-term effects of functional appliance therapy. Unfortunately, no

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Figure 6. Mandibular dental changes: (A) lower molar horizontal changes with removable functional appliances, (B). lower molar vertical changes with removable functional appliances, (C) lower incisor horizontal changes with removable functional appliances, (D) lower incisor vertical changes with removable functional appliances, (E) lower molar horizontal changes with fixed functional appliances, (F) lower molar vertical changes with fixed functional appliances, (G) lower incisor horizontal changes with fixed functional appliances, and (H) lower incisor vertical changes with fixed functional appliances.

published long-term results fit our selection criteria. Removable functional appliances (RFAs) did not demonstrate any clinically significant skeletal changes; however, clinically significant dental changes included distal movement of

upper molars and upper incisors, along with vertical movement of lower molars. In contrast, fixed functional appliances (FFAs) showed no significant maxillary skeletal effects, but in contrast, an increase in Co–Gn

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Figure 6. (continued)

(mandibular length) and N perpendicular to Pog was observed. The dental changes noted were distal movement of maxillary molars and incisors, accompanied by lower incisor proclination. In other words, only FFAs seemed to have any effect on mandibular length but at the cost of lost anterior anchorage. The primary effects of both types of functionals are on the midface and by interrupting dentoalveolar compensation (Figs. 1–6). This investigation validates information that can be readily gleaned from the literature regarding the effects of functional appliances. Despite the significant amount of data, there still seems to be an ongoing debate about the efficacy of functional appliances as they are still widely accepted and used by clinicians. If the vast number of patients across the world who benefitted from the effects of these appliances were to have been subjected to findings of just the RCTs, we would probably be writing new chapters in the annals of

orthodontic bureaucracy. The method used to study growth modification in Class II malocclusion can have concurrent impact on the conclusive treatment changes.53 Probably yes, or if we assumed that the averages can bring about X amount of change. For instance, without quantifying diagnostic parameters, we may well have been treating the wrong patients with the right appliance and when things turned out poorly, we blamed the appliance (or vice versa). This might be a cynical perspective, but it is true that statisticians do not treat patients, only interpret data, often with many confounding variables involved. The refined RCT designs for future should at least differentiate the Class II patient on the basis of their individual vertical or horizontal growth pattern, maxillary excess, or mandibular retrusion, so that the gold standard or preferred treatment modality for each type of problem is selected. Without differentiating the diagnostic variables and by simply studying appliance effects or therapeutic efficacy, then we

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are contributing to a cookbook culture with little hope for improvement. The discerning clinician of the 21st century has to be astute in knowing that significant variation exists between individual patients and that this needs to be considered, deliberated in detail with patients and their parents, before a treatment plan incorporating the best evidence is finalized. Finally, future research in growth and genetics along with evaluation of three-dimensional treatment effects of perhaps bone-anchored functional appliance designs may be useful in developing more effective and efficient functional appliance therapy.

Acknowledgment We would like to thank Dr Vidya Wadadekar, our Biostatistician, and the Faculty and Residents, Department of Orthodontics and Dentofacial Orthopedics, YMT Dental College and Hospital, India for their assistance in this project.

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