Effect of protraction facemask on the temporomandibular joint: a systematic review

The effect of mentoplate application on the condyle

BACKGROUND

The aim of the study was to investigate the changes occurring in the mandibular condyle by using mentoplate together with rapid maxillary expansion (MP-RME) treatment in the correction of skeletal class III relationship, using fractal analysis (FA).

METHODS

The sample consisted of 30 individuals (8-11 years) diagnosed with skeletal Class III malocclusion who underwent MP-RME treatment. Archival records provided cone-beam computed tomography (CBCT) images taken at two intervals: before MP-RME treatment (T0) and after treatment (T1). The CBCT images were obtained using standardized settings to ensure consistency in image quality and resolution. The trabecular structures in the bilateral condyles at both T0 and T1 were analyzed using FA. The FA was performed on these condylar images using the Image J software. The region of interest (ROI) was carefully selected in the condyle to avoid overlapping with cortical bone, and the box-counting method was employed to calculate the fractal dimension (FD). Statistical analysis was conducted to compare the FD values between T0 and T1 and to evaluate gender differences. The statistical significance was determined using paired t-tests for intra-group comparisons and independent t-tests for inter-group comparisons, with a significance level set at p < 0.05.

RESULTS

The analysis revealed no statistically significant differences in the trabecular structures of the condyles between T0 and T1 (p > 0.05). However, a significant gender difference was observed in FA values, with males exhibiting higher FA values in the left condyle compared to females at both T0 and T1 (p < 0.05). Specifically, the FA values in the left condyle increased from a mean of 1.09 ± 0.09 at T0 to 1.13 ± 0.08 at T1 in males, whereas in females, the FA values remained relatively stable with a mean of 1 ± 0.09 at T0 and 1.03 ± 0.11 at T1.

CONCLUSION

The findings indicate that MP-RME therapy does not induce significant alterations in the trabecular structure of the mandibular condyle. These results suggest the treatment's safety concerning the structural integrity of the condyle, although the observed gender differences in FA values warrant further investigation.

Orthodontic treatment for prominent lower front teeth (Class III malocclusion) in children

BACKGROUND

Prominent lower front teeth (Class III malocclusion) may be due to jaw or tooth position or both. The upper jaw (maxilla) can be too far back or the lower jaw (mandible) too far forward; the upper front teeth (incisors) may be tipped back or the lower front teeth tipped forwards. Orthodontic treatment uses different types of braces (appliances) fitted inside or outside the mouth (or both) and fixed to the teeth. A facemask is the most commonly reported non-surgical intervention used to correct Class III malocclusion. The facemask rests on the forehead and chin, and is connected to the upper teeth via an expansion appliance (known as 'rapid maxillary expansion' (RME)). Using elastic bands placed by the wearer, a force is applied to the top teeth and jaw to pull them forwards and downward. Some orthodontic interventions involve a surgical component; these go through the gum into the bone (e.g. miniplates). In severe cases, or if orthodontic treatment is unsuccessful, people may need jaw (orthognathic) surgery as adults. This review updates one published in 2013.

OBJECTIVES

To assess the effects of orthodontic treatment for prominent lower front teeth in children and adolescents.

SEARCH METHODS

An information specialist searched four bibliographic databases and two trial registries up to 16 January 2023. Review authors screened reference lists.

SELECTION CRITERIA

We looked for randomised controlled trials (RCTs) involving children and adolescents (16 years of age or under) randomised to receive orthodontic treatment to correct prominent lower front teeth (Class III malocclusion), or no (or delayed) treatment.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcome was overjet (i.e. prominence of the lower front teeth); our secondary outcomes included ANB (A point, nasion, B point) angle (which measures the relative position of the maxilla to the mandible).

MAIN RESULTS

We identified 29 RCTs that randomised 1169 children (1102 analysed). The children were five to 13 years old at the start of treatment. Most studies measured outcomes directly after treatment; only one study provided long-term follow-up. All studies were at high risk of bias as participant and personnel blinding was not possible. Non-surgical orthodontic treatment versus untreated control We found moderate-certainty evidence that non-surgical orthodontic treatments provided a substantial improvement in overjet (mean difference (MD) 5.03 mm, 95% confidence interval (CI) 3.81 to 6.25; 4 studies, 184 participants) and ANB (MD 3.05°, 95% CI 2.40 to 3.71; 8 studies, 345 participants), compared to an untreated control group, when measured immediately after treatment. There was high heterogeneity in the analyses, but the effects were consistently in favour of the orthodontic treatment groups rather than the untreated control groups (studies tested facemask (with or without RME), chin cup, orthodontic removable traction appliance, tandem traction bow appliance, reverse Twin Block with lip pads and RME, Reverse Forsus and mandibular headgear). Longer-term outcomes were measured in only one study, which evaluated facemask. It presented low-certainty evidence that improvements in overjet and ANB were smaller at 3-year follow-up than just after treatment (overjet MD 2.5 mm, 95% CI 1.21 to 3.79; ANB MD 1.4°, 95% CI 0.43 to 2.37; 63 participants), and were not found at 6-year follow-up (overjet MD 1.30 mm, 95% CI -0.16 to 2.76; ANB MD 0.7°, 95% CI -0.74 to 2.14; 65 participants). In the same study, at the 6-year follow-up, clinicians made an assessment of whether surgical correction of participants' jaw position was likely to be needed in the future. A perceived need for surgical correction was observed more often in participants who had not received facemask treatment (odds ratio (OR) 3.34, 95% CI 1.21 to 9.24; 65 participants; low-certainty evidence). Surgical orthodontic treatment versus untreated control One study of 30 participants evaluated surgical miniplates, with facemask or Class III elastics, against no treatment, and found a substantial improvement in overjet (MD 7.96 mm, 95% CI 6.99 to 8.40) and ANB (MD 5.20°, 95% CI 4.48 to 5.92; 30 participants). However, the evidence was of low certainty, and there was no follow-up beyond the end of treatment. Facemask versus another non-surgical orthodontic treatment Eight studies compared facemask or modified facemask (with or without RME) to another non-surgical orthodontic treatment. Meta-analysis did not suggest that other treatments were superior; however, there was high heterogeneity, with mixed, uncertain findings (very low-certainty evidence). Facemask versus surgically-anchored appliance There may be no advantage of adding surgical anchorage to facemasks for ANB (MD -0.35, 95% CI -0.78 to 0.07; 4 studies, 143 participants; low-certainty evidence). The evidence for overjet was of very low certainty (MD -0.40 mm, 95% CI -1.30 to 0.50; 1 study, 43 participants). Facemask variations Adding RME to facemask treatment may have no additional benefit for ANB (MD -0.15°, 95% CI -0.94 to 0.64; 2 studies, 60 participants; low-certainty evidence). The evidence for overjet was of low certainty (MD 1.86 mm, 95% CI 0.39 to 3.33; 1 study, 31 participants). There may be no benefit in terms of effect on ANB of alternating rapid maxillary expansion and constriction compared to using expansion alone (MD -0.46°, 95% CI -1.03 to 0.10; 4 studies, 131 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Moderate-certainty evidence showed that non-surgical orthodontic treatments (which included facemask, reverse Twin Block, orthodontic removable traction appliance, chin cup, tandem traction bow appliance and mandibular headgear) improved the bite and jaw relationship immediately post-treatment. Low-certainty evidence showed surgical orthodontic treatments were also effective. One study measured longer-term outcomes and found that the benefit from facemask was reduced three years after treatment, and appeared to be lost by six years. However, participants receiving facemask treatment were judged by clinicians to be less likely to need jaw surgery in adulthood. We have low confidence in these findings and more studies are required to reach reliable conclusions. Orthodontic treatment for Class III malocclusion can be invasive, expensive and time-consuming, so future trials should include measurement of adverse effects and patient satisfaction, and should last long enough to evaluate whether orthodontic treatment in childhood avoids the need for jaw surgery in adulthood.

Orthodontics and Temporomandibular Disorders: An Overview

The relationship between orthodontics and temporomandibular disorders (TMDs) constitutes a subject of paramount significance in dental and craniofacial health. This abstract embarks upon an in-depth examination of the intricate connection between orthodontic practices and TMD, primarily focusing on evaluating the impact of orthodontic treatment modalities on the health and functionality of the temporomandibular joint (TMJ). This exploration elucidates the multifaceted interplay between orthodontic interventions and TMD by traversing a landscape of scholarly research and empirical investigations. The review draws from a broad spectrum of studies to analyze the potential influence of orthodontic treatments, which encompass occlusal adjustments and alterations in jaw positioning, on the development and management of TMD symptoms. The inquiry delves into the diverse range of TMD conditions, considering the implications of orthodontic techniques on occlusal stability, condylar alignment, and overall TMJ function. Through a comprehensive synthesis of the available body of knowledge, this abstract aspires to equip dental practitioners, orthodontists, and researchers with a nuanced understanding of the complex dynamics that govern the relationship between orthodontics and TMD. This knowledge, in turn, offers a foundation for informed clinical decision-making and the formulation of effective treatment strategies for patients presenting with TMD symptoms. By shedding light on the intricate interactions between orthodontic procedures and TMJ health, this abstract contributes to the advancement of clinical practices, promoting improved patient outcomes and well-being in the context of both orthodontics and TMDs.

Assessment of influence of facemask treatment with skeletal anchorage on the temporomandibular joint using magnetic resonance imaging: a preliminary study

OBJECTIVE

The aim of the study was to investigate the influence of facemask treatment with skeletal anchorage on the temporomandibular joint (TMJ) using magnetic resonance imaging (MRI), in patients with Class III malocclusion, accompanied by maxillary retrusion.

METHODS

Fifteen patients with a mean age of 12.1±1.43 years were included in the study. All patients were treated using facemask with skeletal anchorage after eight weeks of Alternate Rapid Maxillary Expansion and Constriction (Alt-RAMEC) protocol. Magnetic resonance imaging was performed before and immediately after facemask treatment for TMJ evaluation. Disc position, condylar translation, degenerative changes of the condyles, and joint effusion were evaluated. To assess whether the alterations associated with the treatment were statistically significant, McNemar and marginal homogeneity tests were used.

RESULTS

After facemask treatment, a statistically significant change was observed in the disc position (an anterior disc displacement with/without reduction in five TMJs) (p<0.05). The alteration in the condylar translation was not statistically significant (p>0.05). This treatment did not cause degenerative changes of the condyles or effusion in any of the TMJs.

CONCLUSION

Facemask treatment with skeletal anchorage following the Alt-RAMEC protocol had a minimal influence on the TMJ, only by means of disc position, which was not negligible. Long-term results of such treatment are required for following up the changes observed in the TMJs.

Effect of Molar Distalization on Condyle-Glenoid Fossa Relationship

Objective

It is essential to be aware of the potential effects of orthodontic treatment on tissues and anatomical structures associated with the masticatory system, especially the temporomandibular joint (TMJ). Little information is available about the consequences of molar distalization on the TMJ. Therefore, this study is aimed at investigating the changes of the condyle-fossa relationship after molar distalization using the distal jet appliance.

Materials and Methods

The sample consisted of twenty-five patients (mean age 20.4 ± 2.6) who underwent molar distalization by the distal jet appliance. CBCT scans were taken before (T0) and after (T1) the completion of the molar distalization. Joint spaces (anterior, superior, and posterior) and cephalometric vertical angles (SN.GOME and Björk sum) were measured and compared at T0 and T1.

Results

Superior and posterior joint spaces increased significantly after molar distalization (PS 0.29 mm, P < 0.001, SS 0.06 mm, P < 0.5). Vertical cephalometric angles also increased after molar distalization by the distal jet appliance (SN.GOME 0.92°, Björk 1.11°).

Conclusion

There was a statistically significant increase in the superior and posterior joint spaces after molar distalization. However, this increase may not be of clinical importance. The vertical dimension has also increased.

Impacts of protective face masks on ocular surface symptoms among healthcare professionals during the COVID-19 pandemic

BACKGROUND

To assess the impacts of prolonged protective face masks (PFM) wear on ocular surface symptoms among healthcare professionals (HCPs), and how these symptoms affected PFM wear.

METHODS

Thirty-question survey forms were distributed via social media platform to 396 HCPs (110 doctors, 164 nurses, and 122 health technicians) between September 8 and 30, 2021. Participants who could not be reached via social media were given a face-to-face questionnaire. Aside from sociodemographic data, the questionnaire inquired about PFM wear, PFM types, ocular surface symptoms, and how PFM wear has changed during the COVID-19 pandemic.

RESULTS

A total of 74.5% of HCPs reported wearing PFMs, mostly surgical ones (76.8%), for half a day at work but not at home, with redness (29.3%) being the most frequently encountered ocular surface symptom, followed by burning (15.7%), pain (14.1%), tingling (10.9%), and rash (6.6%). The presence of associated restrictions in conjunction with PFM-related ocular symptoms was more likely in dry and hot environments. There was no significant relationship between PFM type, PFM-wearing duration, and HCPs' daily activities (p > 0.05). Despite the lack of a significant relationship between PFM types and ocular surface symptoms (p > 0.05), there was a significant relationship between PFM-wearing duration and ocular pain (p < 0.05).

CONCLUSIONS

PFM-related ocular surface symptoms can be alleviated by properly wearing PFMs, reducing wear time, and using long-acting topical lubricants. This could improve PFM wear compliance, prevent disease transmission, and ultimately help with COVID-19 protection.

Impact of COVID-19 pandemic on the ocular surface

BACKGROUND

There have been increased reports of dry eyes in the coronavirus disease 2019 (COVID-19) pandemic era.

AIM

To analyze the differences in tear film properties from pre- and post-pandemic of the COVID-19 era.

METHODS

It was a retrospective comparative study. Patients were divided into three groups according to the data of multimodal ocular surface evaluation: (1) Group 1 if it was before Portugal lockdown decision (from August 2019 to March 2020); (2) Group 2 if it was after Portugal lockdown decision but without mask mandate (from April 2020 to October 2020); and (3) Group 3 if it was after Portugal lockdown but with mask mandate in health public highway (from November 2020 to April 2021). The following variables were analyzed: Lipid layer thickness, blink rate, Schirmer test, tear meniscus height, tear osmolarity, non-invasive break-up time, and loss area of the meibomian glands.

RESULTS

The study included 548 eyes of 274 patients, aged 18 years to 89 years, with a mean age of 66.15 ± 13.40 years at the time of multimodal ocular surface evaluation. Compared to group 1: (1) Mean lipid layer thickness was better in group 2 (P = 0.001) and group 3 (P < 0.001); (2) Schirmer test was similar in group 2 (P = 0.576) and better in group 3 (P = 0.002); (3) Tear osmolarity and loss area of the meibomian glands were worse in group 2 (P = 0.031 and P < 0.001, respectively) and in group 3 (both with P < 0.001); (4) Blink rate and tear meniscus height were similar in group 2 (P = 0.821 and P = 0.370, respectively) and worse in group 3 (P < 0.001 and P = 0.038, respectively); and (5) Non-invasive break-up time was worse in group 2 (P = 0.030) and similar in group 3 (P = 0.263).

CONCLUSION

Our study demonstrated that differences existed in tear film properties comparing data from the pre- and post-pandemic of the COVID-19 era.

Three-Dimensional Assessment of the Temporomandibular Joint Changes Following Reversed Twin Block Therapy of Patients With Skeletal Class III Malocclusion in Conjunction With the Photobiomodulation Therapy: A Randomized Controlled Clinical Trial

Background: Despite the positive effect of the photobiomodulation therapy (PBMT) application on animals, the primary role of this technique on the human condyle is still unclear. Several experimental reports have shown the efficacy of PBMT in inducing cellular changes in the temporomandibular joint (TMJ) region during functional treatment of patients with skeletal deformities. Still, the lack of information about its effects on human condyles requires further studies.

Objectives: This study aimed to evaluate the effect of PBMT on the TMJ components following Class III treatment with the reversed twin block (RTB) appliance in growing patients. 

Materials and Method: Forty children (12 females, 28 males) between the age of nine and eleven years with skeletal Class III were assigned randomly to the RTB group with photobiomodulation (RTB+PBMT) or the control group (RTB). The PBMT was applied to the TMJ region using an 808-nm wavelength Ga-Al-As semiconductor laser device with 5 Joules/cm² energydensity on days 1, 3, 7, and 14 of the first month. Afterwards, the irradiation was conducted every 15 days until the end of the treatment. Cone-beam computerized tomography (CBCT) images were taken before (T1) treatment and following the end of treatment (T2) to assess TMJ and skeletal changes.

Results: Condylar volume was significantly increased in the RTB group only by a mean of 287.97 mm³ (p<0.001). The significantly backward and upward condylar movement was observed in the RTB and RTB+PBMT groups (superior joint space (SJS): 0.26 mm, 0.15 mm; posterior joint space (PJS): 0.42mm, 0.11mm, respectively). The RTB group showed the most remarkable changes. Significant improvement of the sagittal maxilla-mandibular relationship was greater in the RTB+PBMT group compared to the RTB group (p=0.02).

Conclusion: There were no considerable differences in the condylar position after Class III treatment between the RTB and the RTB+PBMT groups. But a difference in the condylar volume was noticed between the two group.

Piezo1 and IFT88 synergistically regulate mandibular condylar chondrocyte differentiation under cyclic tensile strain

OBJECTIVE(S)

Mandibular condyle chondrocytes (MCCs) are exposed to various mechanical environments. Primary cilia, as a carrier for ion channels, can sense mechanical signals. Intraflagellar transport protein 88 (IFT88) is crucial for the assembly and function of primary cilia. Piezo1 is a mechanically activated ion channel that mediates mechanical signal transduction. This study aimed to identify the possible synergistic effect between Piezo1 and IFT88 in MCC differentiation during mechanical conduction.

MATERIALS AND METHODS

Confocal immunofluorescence staining was used to reveal the Piezo1 localization. Small interfering RNA (siRNA) technology was used to knock down the expression levels of Piezo1 and IFT88. The chondrogenic differentiation ability of MCCs was evaluated by Alcian blue staining, and the early differentiation ability was evaluated by Western blot of SOX9 and COL2A1.

RESULTS

Confocal immunofluorescence results showed that Piezo1 localized in the root of primary cilia. Without cyclic tensile strain (CTS) stimuli, Alcian blue staining showed that Piezo1 knockdown had a marginal effect on the chondrogenic differentiation of MCCs, while IFT88 knockdown inhibited the chondrogenic differentiation. The protein levels of SOX9 and COL2A1 decreased significantly with CTS stimuli. However, these protein levels were restored when Piezo1 was knocked down. In addition, IFT88 knockdown decreased the protein level of Piezo1 with or without CTS.

CONCLUSION

Piezo1 and IFT88 might play a synergistic role in regulating MCC differentiation under CTS stimuli.

Effects of reverse headgear therapy on mandibular trabecular structure: A fractal analysis study

OBJECTIVES

The aim of this study was to assess the effects of reverse headgear (RHG) treatment combined with rapid maxillary expansion (RME) on the trabecular structure of the mandibula using fractal dimension (FD) analysis.

METHODS

Forty-four individuals with skeletal Class III malocclusion were selected from the archives and divided into two groups as patients who underwent treatment with RME + RHG (RHG-G, 22 patients) and untreated control group (C-G, 22 patients). The before (T0) and after (T1) treatment lateral cephalometric and panoramic radiographs were collected in the RHG-G and in the control group, radiographs obtained with similar time intervals were grouped as T0 and T1. Cephalometric and FD analysis was conducted on T0 and T1 lateral cephalometric and panoramic radiographs. The intragroup comparison of cephalometric and FD data was performed using paired t test and Wilcoxon Signed Ranks test, while independent t test and Mann-Whitney U test were used for intergroup comparison.

RESULTS

C-G had higher FD values in the right mandibular corpus and left mandibular ramus values at T0 (P < .05). The only significant difference in the intragroup comparisons was detected in the FD values of the right mandibular corpus in the C-G (P < .05). No significant differences were found in the FD between the groups in any of the areas measured (P > .05).

CONCLUSIONS

RME + RHG therapy did not cause any significant trabecular changes in the mandibula when compared to the control group.

Face Mask-Related Ocular Surface Modifications During COVID-19 Pandemic: A Clinical, In Vivo Confocal Microscopy, and Immune-Cytology Study

Purpose

The purpose of this study was to describe the face mask (FM)-related ocular surface changes using clinical tests, in vivo confocal microscopy (IVCM) and impression cytology (IC), and to investigate the Dry Eye-related Quality of life Score (DEQS).

Methods

Sixty-six patients with dry eye disease (DED) and 62 healthy subjects (group 2) using FM were enrolled. Groups were divided into: groups 1A and 2A: < 3 hours of FM wear; groups 1B and 2B: 3 to 6 hours; and groups 1C and 2C: > 6 hours. Patients underwent DEQS questionnaire, break-up time (BUT), Schirmer test I (STI), fluorescein and lissamine staining (FS and LS), IVCM to determine corneal dendritic cell density (DCD) and goblet cell density (GCD), and IC to measure HLA-DR, at baseline and after 3 months.

Results

FM use duration before enrollment was 27 ± 2.3 and 30 ± 4.1 (days ± SD) for groups 1 and 2 (P > 0.05). After 3 months, DEQS worsened in groups 1B and 1C, STI in groups 1A to 1C, FS and LS in group 1C (P < 0.05); in controls, BUT and FS worsened only in group 2C (P < 0.05). DCD significantly increased in groups 1A to 1C and HLA-DR in groups 1B and 1C (P < 0.05), whereas GCD did not significantly change. DCD and HLA-DR increased only in group 2C (P < 0.05). DEQS significantly correlated with DCD (P = 0.05, r = 0.698; P < 0.001, r = 0.832) and HLA-DR (P = 0.043, r = -0.687; P < 0.001, r = 0.861) at baseline and 3 months.

Conclusions

Use of FM increases ocular surface inflammation and negatively impacts the quality of life in patients with DED.

Translational Relevance

The study of the prolonged use of FM effects may be relevant to managing DED.

Study of changes in rat mandibular condyle under intermittent cyclic and continuous compressive stress

OBJECTIVES

This study aimed to investigate the effects of intermittent and continuous compressive stress on rat mandibular condyles.

DESIGN

Ninety rats were randomly divided into 5 groups: non-loading control groups and 1-day intermittent cyclic loading, 3-day intermittent cyclic loading, 7-day intermittent cyclic loading, continuous loading groups. In the loading groups, compressive mechanical stresses were loaded onto the condyles. The rats were euthanized after one, two, or four weeks. Histomorphometric and immunochemical staining of the cartilage and the micro-CT scanning of subchondral bone were investigated.

RESULTS

Under continuous loading following the first week, cartilage thickness, numbers of chondrocytes, extracellular matrix (Type-II collagen) and proliferation decreased significantly, and there was no apparent repair response after the second and fourth weeks. The cartilage of 1-day and 3-day intermittent cyclic loading groups showed similar pathological changes but better proliferative activity compared with the continuous loading group. The 7-day intermittent loading group had significant recovery after 2 weeks, including the increase of cartilage thickness and the number of chondrocytes, cell swelling and rearranging. However, the remodeling of subchondral bone showed no significant difference between the intermittent and continuous loading stress compared to the control group.

CONCLUSIONS

Under moderate mechanical stress, the condylar cartilage actively remodeled, whereas the subchondral bone, as supportive rigid structure, was less sensitive to mechanical pressure. The intermittent compressive stress protects the condylar cartilage from excessive damage, which is different from continuous compressive stress. With longer intervals, the cartilage has the potential capability for recovery as the initial state.

A New Appliance for Class III Treatment in Growing Patients: Pushing Splints 3

Several orthopedic procedures have been used in early treatment to reduce the need for orthognathic surgery in skeletal Class III. The most used treatment is Rapid Maxillary Expansion and Facemask. This procedure also determines a clockwise rotation of the mandible, increasing the vertical dimensions of the lower third of the face. Therefore, the control of vertical dimension appears to be a key objective in Class III hyperdivergent patients. This article shows two skeletal Class III patients treated with a new appliance (Pushing Splints 3), that is able to correct sagittal discrepancy with a good control of the vertical growth. In both cases, Class I relationship with a proper Overjet and Overbite was achieved with improvement of profile. The final cephalometric values demonstrated a stable sagittal relationship and a good control of the vertical growth. The specific biomechanic features of the PS3 appliance permit the improvement of the sagittal jaw relationship, delivering at the same time vertical vectors that are able to control the alveolar and skeletal components of the vertical growth. This could be useful in the treatment of Class III hyperdivergent patients.