Effects of Palatal Plate Treatment Duration on Orofacial Functions of Children With Trisomy 21: Mapping the Evidence Through a Scoping Review

ABSTRACT

Aim

The aim of the present study was to synthesize the available evidence on the short‐ and long‐term effects of Palatal Memory Plate in children with Trisomy 21.

Methods

A scoping review was conducted, and followed the Preferred Reporting Items for Systematic Review and Meta‐Analysis with extension for scoping reviews. The review was registered in Open Science Framework, under registration number 10.17605/OSF.IO/ZDNCQ. Two independent reviewers conducted searches in PubMed, Embase, Web of Science, Scopus, Cochrane Library, and Google Scholar for gray literature, in April, 2026. The critical evaluation of the included studies was done with Oxford‐CEBM Levels of Evidence for intervention questions.

Results

Of the 191 potentially eligible articles for selection, 19 were included. In treatments lasting 4 months to 1 year, improvements were observed in lip sealing, tongue posture, and early speech, as well as an increase in orofacial muscle tone. From 3 to 4 years, results remained stable.

Conclusion

The evidence suggests potential improvements in orofacial functions at different follow‐up periods, with some studies reporting maintenance or progression over time. However, results should be interpreted with caution due to the lack of higher evidence level.

1. Introduction

Down syndrome (DS) is a genetic condition caused by a chromosomal alteration, characterized by the presence of an additional chromosome 21, either complete or fragmented, in the cells [1]. Children with Trisomy 21 (T21) present distinctive orofacial features that assist in clinical diagnosis, such as flat facial profile, brachycephaly, upward slanting palpebral fissures, and small ears often with malformations. In addition, some typical phenotypic traits of T21 are observed in the oral cavity, including hypotonia, relative macroglossia, fissured tongue, high‐arched palate, and impairment of oral motor functions. Such abnormalities and dysfunctions in children with DS may inhibit the development of the midface, while malocclusion can be triggered by the “open mouth” posture associated with mouth breathing. Difficulties in chewing, sucking, speech, and swallowing are also mentioned, mainly due to the inadequate projection of the tongue [2].

In 1970, Castillo‐Morales developed a method known as orofacial regulation therapy, which consisted of a manual stimulation program combined with the use of a palatal plate. The device, named Palatal Memory Plate (PMP), contains stimulators on both the lingual and vestibular surfaces, promoting proper tongue repositioning with observable responses also in the masticatory muscles and lips. Beneficial effects were noted after the use of the PMP in children with DS, such as the correct performance of sucking movements when compared to the period prior to its use [3]. Overall, previous systematic reviews have shown that orthodontic palatal plate therapy may be favorable regarding the alterations involving oral and facial structures in children with T21 under monitoring [1].

This therapy has been described as potentially beneficial intervention in the treatment of children with DS, providing significant benefits in speech development, articulation, and oral function. Particularly, the use of PMP is embedded within a multidisciplinary approach that includes speech therapy, physiotherapy, and family‐centered care, given that the effectiveness of the intervention depends not only on patient stimulation, but also on family adherence [4].

Despite the recognized positive effects of PMP therapy, considerable uncertainty persists regarding the optimal duration of use required to achieve sustained outcomes. While some studies report benefits following shorter intervention periods, others suggest that prolonged and continuous use may result in more durable gains [1, 4]. However, these findings are based predominantly on observational evidence and should therefore be interpreted cautiously. Previous systematic reviews have evaluated the effectiveness of PMP therapy in children with T21 [1, 4]; nevertheless, key aspects related to treatment duration, frequency of use, and the persistence of effects over time remain insufficiently explored and inconsistently reported.

In this context, the conduct of a scoping review is aligned with the methodological guidance of the PRISMA Extension for Scoping Reviews (PRISMA‐ScR) [5], which recommends this approach when the objective is to map key concepts, types of evidence, and knowledge gaps within heterogeneous bodies of literature. Given the variability in study designs, intervention protocols, and outcome measures, as well as the limited comparability across studies, a scoping review is particularly suitable to comprehensively examine the extent and nature of the available evidence. Furthermore, this approach enables the identification of methodological limitations and research gaps, thereby providing a foundation for future investigations and more focused systematic reviews.

Therefore, the aim of the present scoping review was to synthesize the available evidence on the short‐ and long‐term effects of PMP in children with T21.

2. Methods

The study was conducted following the PRISMA‐ScR, namely the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses Extension for Scoping Reviews [5].

The research question was: What is the current evidence of the short‐ and long‐term effects of using a stimulation palatal plate in children with Trisomy 21? The PCC acronym (Population, Concept, Context) was used to formulate the guiding question in this scoping review (Figure 1).

FIGURE 1.

PCC acronym.

2.1. Protocol and Registration

The protocol was registered in the Open Science Framework (OSF; Center for Open Science, Charlottesville, United States) [6] on March 20th, 2025, and last updated on May 4th, 2026. It is available online under registration number 10.17605/OSF.IO/ZDNCQ.

2.2. Eligibility Criteria

The present review considered the following inclusion criteria: primary research studies, including randomized clinical trials, non‐randomized clinical trials, and observational studies (cohort, cross‐sectional, descriptive and case‐control).

Secondary study designs, such as systematic, narrative and integrative reviews were also included to contextualize and map the available evidence, whereas primary studies remained the main source for synthesis of clinical findings.

To be included, these studies should have explored the short‐ and/or long‐term effects of using stimulation palatal plate of children with T21 regardless of sex. Outcomes of oral motor function, speech development, feeding abilities, palatal development and frequency of use were considered. Furthermore, the studies must have described the detection method of the reported outcome, whether by clinical examination, video and photo registration, or parental questionnaire. Restrictions on the language or publication date of the article were not applied.

The following exclusion criteria were: (1) Studies that did not mention/specify the detection method of reported outcome. (2) Studies that did not provide enough data on the short or long‐term effects. (3) Studies that focused on other syndromes and conditions, such as neurological or psychiatric comorbidities. (4) Letters, book chapters, conference abstracts, clinical guides, panels, articles describing techniques, opinion articles and case reports. (5) Full text not found for full reading or correspondence authors not responding to the attempt of contact (three in a 3‐week period).

2.3. Information Sources and Search Strategy

An electronic literature search strategy was carried out in PubMed, Embase (1974 to present), Web of Science, Scopus, Cochrane Library and Google Scholar in April, 2026. The search strategy employed in PubMed included indexed terms (MeSH) and their synonyms. Some adjustments were made to align the strategy with the specific requirements of each database. For further information, refer to Appendix 1. On Google Scholar database, only the first one hundred hits were considered.

The reference lists of included studies and relevant systematic reviews for further studies were also searched. Moreover, none of the included studies in this review were retracted due to error or fraud. All the references obtained in the search were imported to the web software Rayyan (Qatar Computing Research Institute, Doha, Qatar) [7] for duplicate removal, and then continued the selection phases in the same software.

2.4. Selection of Sources of Evidence and Data Charting Process

Three reviewers were involved in this process in order to minimize any potential selection bias. In the first phase, two reviewers (V.F.S.F and L.R.D.M) independently and blindly screened the titles and abstracts. The potential studies were coded as “included” for studies that fit in the inclusion criteria, “maybe” for potentially eligible/unclear records and “excluded”. The conflicts were solved by discussion. If it was not possible, a third review author (E.G.M) was consulted and reached a consensus. In the second phase, the same two review authors applied the eligibility criteria while reading the full text of the studies that had been previously included. Any conflicts were solved by discussion. When it was not possible, a third reviewer (E.G.M) was consulted, and the impasse was resolved through a consensus meeting among the reviewers.

The selection process was planned in sufficient detail to complete the PRISMA flow diagram according to the PRISMA 2021 reporting standards.

2.5. Data Items and Synthesis of Results

For included studies, two authors (C.L.P.R and L.R.D.M) managed to collect the data, and two other reviewers (V.F.S.F and N.C.R.C) cross‐checked it. The authors independently extracted the useful information and data from the full‐text articles on a customized data extraction sheet. To enhance methodological clarity and avoid redundancy, the included studies were categorized into two groups: (1) primary studies and (2) secondary studies (systematic, narrative, and integrative reviews), and data were extracted and presented separately in distinct tables.

The following data were extracted from each included primary study: study characteristics (authors, year, country of publication, and study design), characteristics of studied population (sample size and age range), treatment duration, age of initiation, frequency of use, effects, detection method of the reported outcome and main conclusion. For secondary studies, the following data were extracted: study characteristics (authors, year, country of publication, and study design), sample characteristics (number of included studies and databases searched), results and main conclusion.

Two independent reviewers conducted the selection, and in case of any bias, discussion and agreement were made. If any important data was unclear or missing, it was requested from the corresponding authors by e‐mail, enabling the retrieval of unpublished data. In case of non‐response, data that could not be retrieved were marked in the table as missing or not provided.

2.6. Critical Appraisal of Individual Sources of Evidence

The level of evidence was appraised using the Oxford‐CEBM Levels of Evidence for intervention questions [8], considering the strongest available evidence. Although critical appraisal is not a mandatory component of scoping reviews, this step was included, given the heterogeneity of studies assessing the PMP outcomes, and to enhance the interpretation of the mapped evidence. Similarly, Stefani et al. [9] have encompassed the proposed method earlier, showing possible reproducibility. This approach was defined and included in the protocol update.

Evidence was rated as Level 1 if a systematic review of randomized trials were available; Level 2 if randomized trials or observational studies with large effects were available; Level 3 if non‐randomized controlled cohorts or follow‐up studies were available; Level 4 if only case‐series, case‐control studies, or historically controlled studies were available; and Level 5 if mechanism‐based reasoning studies were available. The level of evidence was further downgraded based on the quality of the evidence [8].

Based on the highest level of evidence available, two reviewers (L.R.D.M and V.F.S.F) interpreted the findings as confirmed (Level 1), plausible (Levels 2–3), inconclusive (Levels 4–5), or inexistent. A third reviewer (N.C.R.C) compared the extracted data and resolved discrepancies. To ensure consistency across all reviewers, Cohen's kappa inter‐rater reliability score was calculated on a random sample of five studies retrieved from the included studies; this yielded a score of 0.902, indicating excellent agreement.

3. Results

3.1. Selection of Sources of Evidence

The first search strategy resulted in 305 (Figure 2). Following the removal of duplicate records, 191 articles underwent screening based on titles and abstracts (phase‐1). Following the initial selection process, 25 articles progressed to the phase‐2 of selection. Moreover, 3 records were included through citation searching. After the selection process, 19 articles were included, being 16 primary and 3 secondary studies.

FIGURE 2.

Flowchart depicting the process of search and selection of included studies. Reasons for exclusion: Reason 1. Not reporting or mentioning the detection method for the reported outcomes; Reason 2. Not enough data about the short or long‐term effects; Reason 3. Considering other syndromes or conditions; Reason 4. Wrong study design; Reason 5. Full text not found for full reading or correspondence authors not responding to the attempt of contact (three in a 3‐week period).

3.2. Bibliometric Analysis and Characteristics of Sources of Evidence

The articles were conducted in seven countries across four continents (Figure 3). Most of them were conducted in Europe, being seven articles in Germany [3, 10, 11, 12, 13, 14, 15], six in Sweden [16, 17, 18, 19, 20, 21], one in Italy [22], and one in Poland [2]. South America accounted for two articles; being conducted in Brazil [23, 24]. North America was represented by one article in the United States of America [1]. Similarly, Africa had one contribution, conducted in Tunisia [4] (Figure 3B). No included study was performed on samples from Asia and Oceania. The publication years were: 1991 (n = 2), 1996 (n = 1), 1997 (n = 1), 1999 (n = 1), 2000 (n = 1), 2001 (n = 1), 2003 (n = 3), 2004 (n = 1), 2006 (n = 1), 2007 (n = 2), 2014 (n = 1), 2017 (n = 1), 2021 (n = 1), 2022 (= 1), and 2023 (n = 1). Regarding primary studies, the sample sizes varied between 12 and 106 participants, and individuals included ranged from 1 month to 12 years old. For further information, refer to Table 1.

FIGURE 3.

Bibliometric analysis on studies characteristics. (A) Worldwide distribution of the selected studies on the short‐ and long‐term effects on the continents of North and South America, Africa, and Europe (n = 19). (B) Prevalence of included publications distributed across countries (n = 19). (C) Prevalence of included publications distributed according to the study design (n = 19).

TABLE 1.

Summary of descriptive characteristics of included primary research articles (n = 16)

Study characteristics		Sample characteristics		Outcomes characteristics					Other
Author, year (country)	Study design	Sample size (F:M)	Age	Treatment duration	Frequency of use	Detection method	Results	Main conclusion	LE and interpretation
Bäckman et al. (2003) [17] (Sweden)	Longitudinal study	Control group: 31 Children with DS using PMP: 42 children (F 18: 24 M) Children with DS not using PMP: 33 children	≤6 months to 18 months Palatal plate 1: 6 and 10 months of age Palatal plate 2: 10 and 14 months of age Palatal plate 3: 14 and 18 months of age	12 months	2–3 times a day for periods of 5–30 min	Clinical evaluation	Children with DS had less teeth erupted when comparing to children using PMP (p = 0·0001). Tongue hypotonia was observed in 12 of the children using PMP (30%) and in eight (24%) of the control children with DS, not using PMP. About overbite and overjet, not all the individuals were evaluated because they were so young, and the results must therefore be judged with caution. 42% of the children with DS and using PMP had a negative overjet, while 52% of the children with DS not using PMP had a negative overjet. Children with normal development performed the oral motor function and speech test on a more mature level than the two groups of children with DS. The DS children in using PMP performed on a more mature level than the DS children in the control group. Similarly, better motor prerequisites for articulation in children with DS using PMP was observed	Palatal plate therapy had a positive effect on oral motor performance and prerequisites for articulation. However, no differences were seen in other parameters, such as tooth eruption and tongue morphology and symptoms of hypotonia	Level 3 (plausible)c
Bäckman et al. (2007) [16] (Sweden)	Longitudinal study	Control group: 36 (15 F: 21 M) Children with DS using PMP: 36 children using PMP (17 F: 20 M) Children with DS not using PMP: 31 (13 F: 18 M)	3 and 33 months 4 children started therapy during their first year of life, 3 during their second year, and 2 during their third year	4 years	Twice a day, for approximately 1 h	Video registration and parents’ questionnaire	Regarding the results from the video registration, children with DS using PMP had significant improvements in orofacial function during the first year of treatment. Specifically, they spent more time with their mouths closed and less time with inactive tongue protrusion compared to the control group. These changes were most notable in the first year and stabilized over time. After 4 years, both groups showed reduced open‐mouth posture, but only the palatal plate group maintained lower levels of inactive muscle activity and higher levels of active function, especially during the early phase of treatment. About the parental questionnaire, eight of the nine parents reported positive effects, such as more activity in the face and a changed facial expression	Particularly, during the first year of treatment the PMP showed good results on oral motor functions. However, inactive muscle function was significantly reduced in the PMP group also after 4 years of treatment	Level 3 (plausible)b
Almeida et al. (2023) [23] (Brazil)	Cross‐sectional study	14 Sex distribution was not reported	3 to 20 months	4 months	Three times a day, for 30 min, along with orofacial exercises	Parents/guardians questionnaire	Closed lips while using PMP was observed in all children under 10 months old. The parents/guardians of children that started the treatment earlier were more satisfied. There was no statistical difference between the time of PMP use per day and the other effects	Indicate an association between age and lip posture, reported by the parents, during the use of PMP	Level 4 (inconclusive)c
Carlstedt et al. (2007) [21] (Sweden)	Longitudinal study	PMP group: 9 (3 F: 6 M) Control group: 11 (5 F: 6 M)	3 and 33 months 4 children started therapy during their first year of life, 3 during their second year, and 2 during their third year	4 years	Twice a day, for approximately 1 h	Video registration, and parents’ questionnaire	Regarding the results from the video registration, children with DS using PMP had significant improvements in orofacial function during the first year of treatment. Specifically, they spent more time with their mouths closed and less time with inactive tongue protrusion compared to the control group. These changes were most notable in the first year and stabilized over time. After 4 years, both groups showed reduced open‐mouth posture, but only the palatal plate group maintained lower levels of inactive muscle activity and higher levels of active function, especially during the early phase of treatment. About the parental questionnaire, eight of the nine parents reported positive effects, such as more activity in the face and a changed facial expression	Particularly, during the first year of treatment the PMP showed good results on oral motor functions. However, inactive muscle function was significantly reduced in the PMP group also after 4 years of treatment	Level 3 (plausible)b
Carlstedt et al. (1996) [19] (Sweden)	Longitudinal study	PMP group: 14 (4 F: 10 M) Control group: 15 (9 F: 6 M)	3 months to 5 years	1 year	Twice a day, for 30 min–1 h	Video registration	Children in the tested group showed significant improvements in oral posture. After 9 months, they had longer durations of closed‐mouth posture (p < 0.01) and shorter durations of inactive tongue protrusion (p < 0.01) compared to the control group. By 12 months, they also showed reduced active tongue protrusion (p < 0.05). Over time, only the test group demonstrated a continuous increase in closed‐mouth duration. Significant differences in inactive tongue protrusion appeared only after 9 months of therapy (p < 0.001), with no differences observed at 3 or 6 months	The use of PMP showed positive effects on oral motor functions. However, results should be interpreted with caution, because a 1‐year follow up may be too short for any definite conclusions	Level 3 (plausible)b
Carlstedt et al. (2001) [20] (Sweden)	Longitudinal study	PMP group: 9 (3 F: 6 M) Control group: 11 (5 F: 6 M)	3 to 33 months	4 years	Twice or three times a day, for 1 h	Clinical evaluation and video registration	Regarding the results from the clinical evaluation, the children in the PMP group showed rounding lips during speech more often than the control group. Video analysis revealed that these children spent a greater percentage of time in active orofacial movements (81.0% vs. 68.2%) and less time in inactive tongue protrusion. Over time, both groups showed reductions in this inactive behavior, but the improvement was more significant in the palatal plate group (p < 0.05). Furthermore, there were moderate correlations between the 1‐year and 4‐year results for closed‐mouth posture and inactive tongue protrusion in the palatal plate group	The use of PMP for a long‐term shows better result on oral motor functions	Level 3 (plausible)b
Carlstedt et al. (2003) [18] (Sweden)	Longitudinal study	PMP group: 9 (3 F: 6 M) Control group: 11 (5 F: 6 M)	3 and 33 months 4 children started therapy during their first year of life, 3 during their second year, and 2 during their third year	4 years	Twice a day, for 1 h	Clinical evaluation, articulation assessment and parental questionnaire	Oral Motor Function: Higher proportion of time with active muscle activity: 81% vs. 68% in the control group. Shorter time with inactive tongue protrusion: 3.9% vs. 8.8% in the control group. Greater lip rounding during speech (an indicator of active lip function). Articulation: Improved articulatory precision in children treated with PMP. Higher frequency of correctly produced sounds, especially bilabials. Communication Preferences: The treated group showed greater use of oral communication compared to the control group. Lower reliance on gestures and non‐verbal communication	After 4 years using PMP, orofacial functions had improved significantly in the treated children, specifically in terms of tongue position and lip activity	Level 3 (plausible)b
Glatz‐Noll and Berg (1991) [10] (Germany)	Longitudinal study	PMP group: 24 (12 F: 12 M) Control group: 19 (8 F: 11 M)	2 months to 12 years	4–11 months	Two or more times a day, for 1–2 h	Video registration	The duration of tongue protrusion decreased markedly. Tongue resting posture also improved, reaching the ideal position in 10 patients. The results appeared to be stable in five of the seven children who were followed for a period of 5 to 20 months after treatment	Video registration is useful to evaluate oral functions. The use of PMP had positive effects and results remained stable	Level 3 (plausible)c
Hohoff and Uhmer (1997) [11] (Germany)	Retrospective study	PMP group: 20 Control group: 18	PMP group: age not reported Average age on the control group: 47.4 months	10.8 months	Twice a day, 2 h	Clinical evaluation, parental questionnaires, and patient records	70% of the children using PMP could purse their lips compared to 55.6% in the control group. The controlled tongue movement was seen in 65% of the children using PMP, while just 22% in the control group. Regarding the speech development, the PMP group was 2 to 3 months faster compared to the control group	The use of PMP had positive impacts on the beginning of speech development. An early treatment and interdisciplinary approach are preferable	Level 3 (plausible)b
Hohoff and Uhmer (1999) [12] (Germany)	Longitudinal study	Pre‐treatment examination: 47 (24 F: 23 M) First follow‐up: 38 (20 F: 18 M) Second follow‐up: 18 (8 F: 10 M)	Pre‐treatment examination: average age 6.5 months	9.9 months	Not reported	Clinical evaluation, and parental questionnaires	A significant reduction in lip posture (open mouth) and tongue positioning (tongue projected beyond the lips) was observed. Moreover, the parents reported an improvement on mouth posture of 76.3% of the children at the first follow‐up examination. According to the parental questionnaires, only one child had mouth posture deteriorated, while 61.1% had remained stable, and 27.8% showed further improvement. 65.8% of the children showed stable treatment results, and 31.6% poorer results, when they were not wearing the PMP	Combining the use of PMP and supporting physiotherapy showed better results. It was observed as an effective adjuvant for improved mouth closure and a better tongue posture and function	Level 3 (plausible)c
Korbmacher et al. (2006) [13] (Germany)	Longitudinal study	27 Sex distribution was not reported	Mean age of 13 ± 4 months	Mean of 19 months ± 4 months	Not reported	Clinical evaluation, and parental questionnaire	With a mean follow‐up of 156 months ± 6 months, after the treatment, the overall improvement from first to the second examination was statistically highly significant (p = 0.000). The changes of the mouth posture observed during the use of PMP (first examination) were significant (p = 0.038), whereas the changes after completion of therapy to the follow up examination were not (p = 0.283). Regarding the habitual tongue position, the improvements were statistically significant during the overall observation period (p = 0.004). Taking the different tongue positions at baseline into account, the further development differentiated significantly (p = 0.018).	The orofacial status at baseline seems to be a predictive value for the success of long‐term improvement	Level 3 (plausible)b
Zavaglia et al. (2003) [22] (Italy)	Longitudinal study	12 Sex distribution was not reported	Average age: 15 months	3 years	1 h a day, and then for 1 h three times a day	Clinical evaluation	At the beginning of treatment, patients exhibited marked tongue protrusion beyond the lower lip (observed in 8 out of 12 children), open‐mouth posture with oral breathing (10 out of 12), sialorrhea (7 out of 12), and significant lip hypotonia (8 out of 12). By the end of the intervention, these conditions showed substantial improvement: tongue protrusion was no longer observed beyond the lower lip in 9 of the 12 children and occurred only occasionally in the remaining 3. Excessive salivation had decreased in 8 out of 12 patients	The results demonstrate the effectiveness of orofacial re‐equilibration and highlight the importance of addressing the muscular component from the very first months of life in children with DS. Moreover, an interdisciplinary approach is preferable	Level 3 (plausible)b
Korbmacher et al. (2004) [14] (Germany)	Prospective longitudinal study	20 Sex distribution was not reported	At the time of the last follow‐up the mean age was 14 years and 1 month. However, before insertion of the PMP, the youngest child was 1 month old, and the oldest 60 months	Mean of 11.5 months ± 4 months	1 h, three times a day	Clinical evaluation, and parental questionnaire	After a follow‐up of 12 months, 75% of the children showed improvement at the end of therapy, when concerning lip posture; 55% maintained this improvement and 40% remained unchanged, while only 5% showed deterioration. Children who presented with more severe orofacial dysfunction (grade III) at baseline showed the most significant and lasting improvements: 100% improved, with 37.5% advancing by three levels, 37.5% by two, and 25% by one. In terms of tongue position, 75% of the children showed improvement over time, and no child experienced deterioration. Among those with an extraoral tongue position (grade III) at the start, 81.8% improved 54.4% by two degrees and 27.2% by one. Among those with a less severe interdental tongue position (grade II), 66.7% showed some improvement. Parental feedback indicated that 65% were satisfied or very satisfied with their child's social integration, although this was not directly correlated with the orofacial improvements	PMP should be prioritized for children with severe orofacial dysfunction and high treatment compliance. For those with initially moderate symptoms, emphasis should instead be placed on complementary therapies	Level 3 (plausible)b
Limbrock et al. (1991) [3] (Germany)	Prospective longitudinal study	67 (34 F: 33 M)	Average: 13.9 months	Average of 12.1 months	1 h, three or four times a day	Clinical evaluation	Tongue position improved by at least two grades in 33 children and by one grade in nine. The greatest improvements were seen in those with the most prominent initial tongue protrusion; milder cases showed less change. Lower lip position also improved: in 26 of 39 cases, a previously protruding lower lip became normal. Similar trends were observed for open‐mouth posture, with the most significant improvements in children who had the most severe dysfunctions at baseline. Out of 53 children with moderate to severe drooling, 36 (68%) showed improvement. Specifically, 19 of 24 children with severe drooling and 17 of 29 with moderate drooling improved following treatment	The positive impact of the palatal plate is highlighted by the immediate improvements observed after its insertion and by the fact that interruptions in therapy, such as waiting for a new plate, often led to temporary deterioration in oral motor functions	Level 3 (plausible)b
Schuster and Giese (2001) [15] (Germany)	Retrospective study	PMP group: 33 Control group: 13 Sex distribution was not reported	PMP group: 8 (± 5) months old Control group: 7 (± 4) months old	2 years	Half an hour, four times a day	Clinical evaluation, parental questionnaire, and intraoral photos	A significant improvement in tongue position was observed in the treated group: in 55% of the children, the previously protruded tongue rested intraorally or on the dentition after therapy. Most parents (65%) whose children were treated with PMP reported an improvement in facial profile directly associated with mouth closure. Acceptance of the plate decreased from the original 80% to 50% during the 2‐year treatment period. During tooth eruption 30% of the children were not willing to wear their plate	Early stimulation plate therapy appears to reduce or even normalize the initially more severe orofacial dysfunctions in the treated group compared to controls	Level 3 (plausible)b
Matthews‐Brzozowska et al. (2014) [2] (Poland)	Prospective longitudinal study	50 (28 F: 22 M)	3 months–2 years old	2 years	Not reported	Clinical evaluation, and parental questionnaire	86% of children with DS using PMP there was a significant improvement as regards tongue position and lip closure and a resultant improvement in facial expression	The involvement of the orthodontist and an early use of the plate play a crucial role in these patients' rehabilitation	Level 3 (plausible)b

Abbreviations: DS, down syndrome; LE, level of evidence; PMP, palatal memory plate.

^aSome limitations, showing minor methodological concerns that do not substantially affect the confidence in the results.

^bImportant limitations, showing relevant methodological concerns that reduce the overall confidence in the results.

^cSerious limitations, showing major methodological concerns that severely compromise the validity of the results.

3.3. Results of Individual Sources of Evidence and Critical Appraisal

From the primary research articles, ten were longitudinal studies [10, 12, 13, 16, 17, 18, 19, 20, 22], three were prospective longitudinal studies [2, 3, 14], two were retrospective studies [11, 15], and one cross‐sectional study [23]. To contextualize and map the evidence, two systematic reviews [1, 4] and one integrative review were identified [24] (Figure 3C).

All primary studies used convenience samples and evaluated the effects of PMP on orofacial function in children with DS, through clinical evaluations, video registrations, parental questionnaires, and speech assessments. Treatment durations ranged from 4 to 48 months, with frequencies varying from 2 to 4 times daily and sessions lasting between 5 min to 2 h.

Apart from Almeida et al. [23], all studies were classified as Level 3 of evidence, which had plausible findings. The wide heterogeneity among the included studies—particularly regarding participants’ age, intervention protocols, duration of treatment, and outcome assessment methods—are pointed as major limitations that affect comparability and results synthesis. A detailed description of the individual study characteristics is provided in Table 1.

3.4. Synthesis of Results

The included reports were predominantly longitudinal studies. Across these studies, the primary outcomes assessed were related to oral motor function, tongue posture, lip activity, facial expression, and speech articulation. Most studies reported patterns suggestive of a reduction in inactive tongue protrusion, greater time spent with closed‐mouth posture, and improved lip rounding during speech. Improvements in articulatory precision, and better orofacial motor coordination were also frequently described as observed outcomes.

Various evaluation methods have been employed. The use of video recordings and intraoral photographs was described as useful for assessing the improvements achieved with the use of the PMP. Additionally, parental questionnaires provided insights into perceived satisfaction with the treatment. Parents or caregivers observed improvements in the children's lip closure, tongue control, communication, and overall facial expressiveness. Additionally, in long‐term studies, observations suggested a possible maintenance or progression of these outcomes over time. However, some studies pointed out the declining acceptance and adherence during long‐term, particularly during periods of tooth eruption. Furthermore, a long‐term use of PMP (up to 4 years) was associated with apparent sustained patterns in orofacial muscle tone and functional speech outcomes. Additional details regarding individual study characteristics and findings are presented in Table 1.

The secondary studies included in this scoping review highlighted the importance of a multidisciplinary approach, such as physiotherapy and speech therapy. Moreover, it emphasized the importance of early intervention, before 3 months old. Further information on the descriptive characteristics of included secondary studies is provided in Table 2.

TABLE 2.

Summary of descriptive characteristics of included secondary research articles (n = 3).

Study characteristics		Sample characteristics		Outcomes characteristics		Other
Author, year (country)	Study design	Included studies	Databases searched	Results	Main conclusion	LE and interpretation
Javed et al. (2017) [1] (United States of America)	Systematic review	8 longitudinal studies	MEDLINE, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register	Five of studies had moderate risk of bias, while three had high risk of bias. A significantly longer period of “closed mouth” (p <  .001) and significantly shorter “inactive protrusion of the tongue” (p <  .001) was seen in children using PMP. The percentage of “inactive tongue protrusion” of total time decreased compared with the 1‐year follow‐up	The positive outcomes of the PMP are associated with multidisciplinary approaches such as physiotherapy, speech therapy, and orofacial control. Standard evaluation methods are required along the studies to evaluate the improvement of orofacial motor functions	Level 3 (plausible) a
Chouchene et al. (2021) [4] (Tunisia)	Systematic review	6 prospectives longitudinal studies	MEDLINE, Cochrane Library, and Scopus	Four studies had moderate risk of bias, while two had high risk of bias. The evaluated outcomes included orofacial criteria, motor function, facial mimicry, tongue position, and speech function. The analysis confirmed that the palatal plate improved orofacial deformities in children with Down syndrome. An additional improvement observed was that children in the palatal plate group exhibited noticeably more rounded lips during speech. Enhancements were also noted in facial muscle tone, lip sealing, and tongue protrusion control	The use of PMP has been shown to be effective when used before the age of 3 months for several minutes per day in addition to speech therapy exercises	Level 3 (plausible)a
Furlan et al. (2022) [23] (Brazil)	Integrative review	10 studies	MEDLINE, LILACS, CINAHL, Embase, Scopus, Web of Science, and Cochrane Library	In some cases, the use of PMP was combined with orofacial muscle stimulation. The children's tongue and lip posture improved in most pieces of research	Use of PMP and orofacial stimulation improve tongue posture and lip closure	Level 3 (plausible)a

Abbreviations: DS, down syndrome; LE, level of evidence; PMP, palatal memory plate.

^aSome limitations, showing minor methodological concerns that do not substantially affect the confidence in the results.

^bImportant limitations, showing relevant methodological concerns that reduce the overall confidence in the results.

^cSerious limitations, showing major methodological concerns that severely compromise the validity of the results.

4. Discussion

The present study examined the existing evidence related to the short‐ and long‐term effects of the PMP use in children with DS. Previous other reviews had been published, and reported promising results [1, 4, 24]. However, these reviews did not analyse short‐ and long‐term outcomes as isolated effects, nor did they address aspects such as treatment adherence or the influence of age at initiation and duration of therapy on clinical results. To address these gaps and provide a broader and detailed understanding of the topic, this scoping review mapped the existing literature, examined the methodological approaches used in this field, identified areas where evidence remains limited, and outlined directions for future research.

Short‐term outcomes were the most consistently effect reported across studies, particularly in relation to symptoms of hypotonia, tongue morphology, lips closure, and speech. Several investigations highlighted suggestive improvements, such as longer time with a closed‐mouth posture and shorter durations of inactive tongue protrusion. However, in the early stages of treatment, the included studies reported improvements exclusively in lip closure, findings that should be interpreted with caution given their reliance on Level 4 evidence and inconclusive results. In contrast, Carlstedt et al. [19] observed significant improvements in lip closure and active tongue protrusion only after 9 months of treatment, with no significant differences between 3 and 6 months. Similarly, with an average treatment duration of 9.9 and 10.8 months, children showed a reduction in hypotonia symptoms and greater parental satisfaction [11, 12]. Although Hohoff and Ehmer [12] reported deterioration in open‐mouth posture in one child, results were based on questionnaires, and presented serious limitations. Nevertheless, these authors have found that 76.3% of the children showed evident improvements, and 61.1% had remained stable after the follow‐up. Concerning the speech, the children using PMP achieved a faster development, compared to those not using it, which may be associated with the functional benefits gained from the treatment.

Evidence concerning the medium‐term outcomes, typically assessed between 2 and 3 years of therapy, suggests maintenance and expansion of gains, such as coordinated facial expression, reduced crossbite and less open bite. Additionally, the included studies reported little to no tongue protrusion beyond the lower lip [2, 15, 22]. When concerning the long‐term effects, the literature appears to show a more homogenous pattern. Although a potential improvement of the orofacial functions is clearly described in the included studies, the literature lacks evidence regarding optimal duration, frequency or dose‐response effects, and these parameters should not be interpreted as prescriptive recommendations.

Furthermore, the frequency of use appeared to play a crucial role in shaping the reported outcomes, as protocols varied widely across studies. Since the PMP relies on stimulation, children should not become accustomed to the plate. The findings of the present scoping review are consistent with those of systematic review by Chouchene and colleagues [4]. Accordingly, the literature describes usage patterns in which children use the plate at least twice a day for a minimum of 30 min, not exceeding four times a day and 2 h; however, these parameters should be interpreted as reported practices rather than high‐quality evidence‐based recommendations, given the lack of robust data on optimal duration and dose‐response effects.

In addition, although the use of PMP demonstrates improvements in outcomes, the variability in frequency of use and treatment duration contributes to the lack of consensus. Standardized protocols, combined with appropriate follow‐up and a multiprofessional approach, tend to yield better results compared to the isolated use of PMP. Parental and guardians’ adherence, for instance, is a key factor in the therapeutic process and may influence the observed outcomes and sustainability of the treatment, particularly as acceptance of the plate may decrease over time with prolonged use [4, 15]. Moreover, the child's adaptation to the device can be challenging, mainly due to developmental changes such as tooth eruption. Emotional and behavioral factors also influence the acceptance of the plate, which requires close monitoring by the multidisciplinary team [16]. The PMP should be regarded as part of a broader therapeutic plan that considers the needs of both the child and the family.

Some limitations of the present review should be acknowledged. First, most of the studies were conducted in a single country, which restricts the generalizability of the evidence to the global population. In addition, all studies were classified as Levels 3–4, providing only plausible or inconclusive evidence, and showed important or serious methodological limitations, such as small sample sizes, lack of reporting on loss to follow‐up, and baseline differences between groups. Moreover, a substantial proportion of the included studies are relatively old, which may compromise the applicability of the findings to current clinical practices. There is also a potential risk of publication bias, given all studies report positive outcomes. Furthermore, there is a notable absence of patient‐centered outcomes, such as quality‐of‐life measures and caregiver burden, which limits a more comprehensive understanding of the intervention. Therefore, further research with representative samples and robust methodologies is needed. New investigations should not only include multicenter longitudinal comparative studies, but also explore the psychosocial impact and quality of life of children using PMP.

It is important to highlight that the present study represents the first synthesis article encompassing both short‐ and long‐term effects of using PMP in children with DS. On top of that, the thorough literature search on the proposed topic, spanning various databases and including gray literature, the transparent and meticulous implementation of the scoping review method, the establishment of inclusion criteria that facilitated the incorporation of primary studies and previously published reviews on the subject, and also, the critical evaluation of the included studies are evident strengths of this literature review.

The completion of this scoping review holds important implications for both clinical practice and the scientific community, as it provided a comprehensive overview of the short‐ and long‐term effects of PMP use DS children and highlighted substantial gaps in the current body of evidence. The available studies suggested that PMP therapy may yield promising short and long‐term outcomes‐ particularly in supporting orofacial development, improving functional patterns, and guiding early oral motor stimulation in this population. Although the available studies suggest potential benefits related to orofacial development and functional outcomes, the heterogeneity in methodologies, follow‐up periods, and outcome measures limits the strength of the conclusions that can be drawn. This process underscored the need for more rigorous, longitudinal research to clarify the clinical relevance, durability, and safety of PMP therapy in this population. Ultimately, the present review reinforced the importance of developing standardized protocols and high‐quality longitudinal studies to better inform clinical decision‐making and optimize care for children with DS.

5. Conclusion

Considering the exploratory and descriptive nature of the available evidence, the findings suggest possible immediate improvements in orofacial functions with the use of PMP, with gains likely maintained or even expanded until 4 years of use. However, these findings should be interpreted as indicative of observed patterns rather than definitive effects. While early initiation and specific usage regimens have been described in the literature, such as considerations should be interpreted cautiously, and clinical decisions should be individualized and integrated within a multidisciplinary care context. Furthermore, the literature lacks a higher level of evidence, and the current evidence is insufficient to guide clinical decisions on duration of therapy.

Author Contributions

Valder Ferreira da Silva Filho: conceptualization, data curation, formal analysis, methodology, writing – original draft and writing – review & editing. Letícia Rocha Dias da Motta: conceptualization, data curation, formal analysis, methodology and writing – original draft. Clarice Luiza de Paula Ribeiro: conceptualization, data curation and writing – original draft. André Luiz da Cunha Dias: data curation and writing – review & editing. Érica Guilhen Mario: conceptualization, data curation, formal analysis, supervision, visualization and methodology. Natália Cristina Ruy Carneiro: conceptualization, data curation, formal analysis, supervision, visualization, methodology and writing – review & editing.

Conflicts of Interest

The authors declare no conflicts of interest.

Appendix 1.

1.1.

Database	Search (March 20th, 2025) updated in April, 2026
PubMed	#1 ‘Down Syndrome’ OR ‘Down's Syndrome’ OR ‘Trisomy 21’ OR ‘T21’ OR ‘Partial trisomy 21’ OR ‘Trisomy G’ OR ‘Meiotic nondisjunction’ OR ‘Mitotic nondisjunction’ #2 ‘Stimulating palatal plate’ OR ‘Stimulation palatal plate’ OR ‘Palatal stimulation plate’ OR ‘Palatal stimulator’ OR ‘Oral stimulation plate’ OR ‘Palatal orthopedic appliance’ OR ‘Orthodontic appliance’ OR ‘Palatal plate’ OR ‘Dental appliance’ OR ‘Castillo‐Morales plate’ OR ‘Castillo‐Moraes concept’ #3 ‘Short‐term effects’ OR ‘Long‐term effects’ OR ‘Treatment’ OR ‘Duration of therapy’ OR ‘Therapy duration’ OR ‘Treatment duration’ OR ‘Treatment outcomes’ OR ‘Outcomes’ OR ‘Clinical effectiveness’ OR ‘Treatment efficacy’ OR ‘Patient relevant outcome’ Search #1 AND #2 AND #3	72 No duplicate
EMBASE	#1 ‘down syndrome’/exp OR ‘down syndrome’ OR ‘trisomy 21’/exp OR ‘trisomy 21’ OR ‘partial trisomy 21’/exp OR ‘partial trisomy 21’ #2 ‘oral stimulation’/exp OR ‘oral stimulation’ OR ‘orthodontic device’/exp OR ‘orthodontic device’ #3‘short term effect’/exp OR ‘short term effect’ OR ‘long term effect’/exp OR ‘long term effect’ OR ‘treatment outcome’/exp OR ‘treatment outcome’ OR ‘treatment’/exp OR ‘treatment’ OR ‘treatment duration’/exp OR ‘treatment duration’ OR ‘outcome’/exp OR ‘outcome’ OR ‘clinical effectiveness’/exp OR ‘clinical effectiveness’ OR ‘therapy’/exp OR ‘therapy’ Search #1 AND #2 AND #3	42 After first duplicate: 13
Scopus	(TITLE‐ABS‐KEY(“Down Syndrome” OR “Down's Syndrome” OR “Trisomy 21” OR “T21” OR “Partial trisomy 21” OR “Trisomy G” OR “Meiotic nondisjunction” OR “Mitotic nondisjunction”)) AND (TITLE‐ABS‐KEY(“Stimulating palatal plate” OR “Stimulation palatal plate” OR “Palatal stimulation plate” OR “Palatal stimulator” OR “Oral stimulation plate” OR “Palatal orthopedic appliance” OR “Orthodontic appliance” OR “Palatal plate” OR “Dental appliance” OR “Castillo‐Morales plate” OR “Castillo‐Moraes concept”)) AND (TITLE‐ABS‐KEY(“Short‐term effects” OR “Long‐term effects” OR “Treatment” OR “Duration of therapy” OR “Therapy duration” OR “Treatment duration” OR “Treatment outcomes” OR “Outcomes” OR “Clinical effectiveness” OR “Treatment efficacy” OR “Patient relevant outcome”))	40 After first duplicate: 7
Web of Science	#1 ‘Down Syndrome’ OR ‘Down's Syndrome’ OR ‘Trisomy 21’ OR ‘T21’ OR ‘Partial trisomy 21’ OR ‘Trisomy G’ OR ‘Meiotic nondisjunction’ OR ‘Mitotic nondisjunction’ #2 ‘Stimulating palatal plate’ OR ‘Stimulation palatal plate’ OR ‘Palatal stimulation plate’ OR ‘Palatal stimulator’ OR ‘Oral stimulation plate’ OR ‘Palatal orthopedic appliance’ OR ‘Orthodontic appliance’ OR ‘Palatal plate’ OR ‘Dental appliance’ OR ‘Castillo‐Morales plate’ OR ‘Castillo‐Moraes concept’ #3 ‘Short‐term effects’ OR ‘Long‐term effects’ OR ‘Treatment’ OR ‘Duration of therapy’ OR ‘Therapy duration’ OR ‘Treatment duration’ OR ‘Treatment outcomes’ OR ‘Outcomes’ OR ‘Clinical effectiveness’ OR ‘Treatment efficacy’ OR ‘Patient relevant outcome’ Search #1 AND #2 AND #3	41 After first duplicate: 12
Cochrane Library	‘Down Syndrome’ OR ‘Down's Syndrome’ OR ‘Trisomy 21’ OR ‘T21’ OR ‘Partial trisomy 21’ OR ‘Trisomy G’ OR ‘Meiotic nondisjunction’ OR ‘Mitotic nondisjunction’ in Title Abstract Keyword AND ‘Stimulating palatal plate’ OR ‘Stimulation palatal plate’ OR ‘Palatal stimulation plate’ OR ‘Palatal stimulator’ OR ‘Oral stimulation plate’ OR ‘Palatal orthopedic appliance’ OR ‘Orthodontic appliance’ OR ‘Palatal plate’ OR ‘Dental appliance’ OR ‘Castillo‐Morales plate’ OR ‘Castillo‐Moraes concept’ in Title Abstract Keyword AND ‘Short‐term effects’ OR ‘Long‐term effects’ OR ‘Treatment’ OR ‘Duration of therapy’ OR ‘Therapy duration’ OR ‘Treatment duration’ OR ‘Treatment outcomes’ OR ‘Outcomes’ OR ‘Clinical effectiveness’ OR ‘Treatment efficacy’ OR ‘Patient relevant outcome’ in Title Abstract Keyword	8 After first duplicate: 3
Google Scholar	(“Down Syndrome” OR “Down's Syndrome” OR “Trisomy 21” OR “T21” OR “Partial trisomy 21” OR “Trisomy G” OR “Meiotic nondisjunction” OR “Mitotic nondisjunction”) AND (“Stimulating palatal plate” OR “Stimulation palatal plate” OR “Palatal stimulation plate” OR “Palatal stimulator” OR “Oral stimulation plate” OR “Palatal orthopedic appliance” OR “Orthodontic appliance” OR “Palatal plate” OR “Dental appliance” OR “Castillo‐Morales plate” OR “Castillo‐Moraes concept”) AND (“Short‐term effects” OR “Long‐term effects” OR “Treatment” OR “Duration of therapy” OR “Therapy duration” OR “Treatment duration” OR “Treatment outcomes” OR “Outcomes” OR “Clinical effectiveness” OR “Treatment efficacy” OR “Patient relevant outcome”)	Last 100 published between 2015–2025 After first duplicate: 85