The impact of malocclusion on the prevalence of pain-related temporomandibular disorders in children and adolescents: a systematic review

Background

The connection between occlusion and temporomandibular disorders (TMD) remains a topic of discussion, and current research does not provide a definitive answer. Pain-related TMD are the most common types of TMD. They include myalgia, arthralgia, and headaches attributed to TMD. This systematic review aims to synthesize the current scientific evidence regarding impact of malocclusion on the prevalence of pain-related TMD in individuals under 18 years.

Methods

The study was based on a searching of the PubMed, Scopus, Embase, and Web of Science databases. Selection was limited to studies that explored the link between malocclusion and pain-related TMD in young individuals. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the selected research. The certainty of evidence was assessed using the Grading Recommendations Assessment, Development and Evaluation (GRADE) approach. A visual representation of the screening and inclusion processes was created using a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) diagram. The information from the research was then summarized in a descriptive format.

Results

Out of 868 potentially relevant articles initially identified, 13 studies were selected based on the inclusion criteria. The majority of these studies were determined to be of moderate quality, according to the NOS assessment. The certainty of evidence was assessed as low, according to the GRADE approach. Most of the studies showed that malocclusion may be associated with TMD-pain signs/symptoms in children and adolescents. The most frequent relationship was found between the prevalence of pain-related TMD and posterior crossbite, Class II malocclusion, Class III malocclusion, and anterior open bite.

Conclusion

Certain types of malocclusion may have an impact on the prevalence of some TMD-pain signs and symptoms in young individuals. However, given the limited reliability of existing research and the inconsistencies observed across studies, additional well-structured, long-term investigations are necessary.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024570950.

Electromyographic Evaluation of Masticatory Muscle Activity in Individuals with and without Cleft Lip/Palate: A Systematic Review and Meta-analysis

OBJECTIVE

This study aims to systematically review and meta-analyze the electromyographic activity of masticatory muscles in cleft palate and non-cleft patients, and identify influencing factors.

DESIGN

Systematic Review and Meta-analysis.

PATIENTS AND EXPOSURES

Patients with cleft lip/ palate.

COMPARISON

Patients without CL/P.

MAIN OUTCOME MEASURES

Electrical activity of masseter and temporalis muscles at rest and during peak activation.

RESULTS

After a comprehensive search in MEDLINE, Web of Science, EMBASE, Scopus, and Cochrane's CENTRAL up to December 2022, without language or date restrictions. Eligible trials were selected based on the PECO question and assessed for bias using Cochrane's ROBINS-E tool. Eight clinical trials with 474 participants were included in the review. Then relevant data was extracted from included studies using customized forms. A random-effects meta-analysis was performed to combine the results of the studies, meta-analyses showed that CL/P patients have elevated electrical activity in the masseter (P = .01) and temporalis (P = <.01) muscles at rest compared to non-cleft control patients. During maximum bite force, cleft patients exhibited a statistically significant decrease in electrical activity in both the masseter (P = .03) and temporalis (P = <.01) muscles.

CONCLUSIONS

According to our meta-analysis, cleft patients exhibited increased resting muscle activity but decreased activity during maximum bite force, indicating reduced efficiency of masticatory muscles compared to non-cleft patients. These differences can be attributed to anatomical variations, compensatory mechanisms, and previous treatments.

Possible link between the preferential unilateral chewing side and eruptive guidance of the maxillary canine germ : Cross-sectional study on panoramic radiographs

AIM

To determine whether unilateral preferent chewing (UPC) affects the position and angulation of the permanent maxillary canine germ on the preferred side.

MATERIALS AND METHODS

In a retrospective cross-sectional study, medical records from children 7.91(± 0.8) years old with unilateral preferred chewing side and unilateral posterior crossbite were selected. The position of the maxillary canines was analysed by measuring the following angles and distances: the angles formed between the canine axis and the midline (PS; potential impact range > 15°), and that between the canine axis and the bicondylar line (W; potential impact range < 75°). In addition, the canine's position with respect to the lateral incisor (EK; potential impact range > II) and the distance between the canine cusp and the occlusal plane (CCOP potential impact range > 10 mm) were measured.

RESULTS

The final sample consisted of 106 radiographs; thus, a total of 212 maxillary canines were analysed. Tooth angulation on the preferred chewing side was higher for the angle PS with an average angle of 13.88° (± 7.56) and its position was more frequently found in sector II (49.1%), according to the EK analysis, compared to its contralateral that had an average of 11.75° (± 10.13) for the PS angle and a frequency of 67% in the sector I (p < 0.05 in both analyses). The data obtained for the angle W resulted in an average of 76.12° (± 9.09), while on the contralateral side it was 77.16° (± 12.56; p = 0.012). Lastly, according to the CCOP analysis, the preferred chewing side measured on average 15.3 mm (± 2.4), while on the nonpreferred side it was 15.19 mm (± 2.43; p = 0.143).

CONCLUSIONS

Based on this research, UPC seems to have a certain unfavourable influence on canine position and angulation. Thus, this is another factor to consider in decision-making regarding early treatment of this development disorder.

Masseter muscle thickness before and after the correction of unilateral functional posterior crossbite in growing individuals: a prospective controlled clinical trial

OBJECTIVES

To evaluate whether unilateral functional posterior crossbite in growing children creates an asymmetry in masseter muscle thickness and whether this asymmetry is normalized after crossbite correction.

MATERIALS AND METHODS

Two groups of growing individuals were studied prospectively: (i) a treatment group: children with unilateral functional posterior crossbite, undergoing crossbite correction with maxillary expansion; and (ii) a control group: children without transversal malocclusions and orthodontic treatment. The thickness of the masseter muscles was measured bilaterally using ultrasonographic recordings at three time points: pre-treatment (T0); 9 months after (T1); and 30 months after posterior crossbite correction (T2); and at equivalent time points in the control group. Differences within and between the groups were evaluated using paired and unpaired t-tests respectively.

RESULTS

It was found that the thickness of the masseter muscles in patients with unilateral functional posterior crossbite was significantly thinner on the crossbite side (P = .013) by 0.5 mm. At T1, the masseter muscle of the treated crossbite side was thicker than that of the previous normal side (0.3 mm difference; P = .046) while this difference disappeared at T2 (P > .05).

LIMITATIONS

The lack of the inclusion of an untreated posterior crossbite group, and the heterogeneity in appliances used are the principal limitations of this study.

CONCLUSIONS

The masseter muscles in untreated individuals with unilateral functional posterior crossbite are thinner in the crossbite side than in the contralateral non-crossbite side. This muscular asymmetry however is eliminated some time after successful treatment of this malocclusion, possibly due to the bilateral symmetrization of the activity of the elevator masticatory muscles.

Long-term effects of orthodontic interceptive expansion treatment : A retrospective study

PURPOSE

The aim of this retrospective cohort study was to evaluate the long-term effects of interceptive orthodontic treatment with a removable expansion plate, based on transversal, sagittal, and vertical parameters.

METHODS

A total of 90 patients needing interceptive treatment due to a crossbite or space deficiency were included. Records consisting of clinical photos, radiographs, and digital dental casts were collected for evaluation at two time points: the start of interceptive treatment (T0) and the start of comprehensive treatment (T1). Molar occlusion, overjet, overbite, presence and type of crossbite, mandibular shift, and transversal measurements were recorded for comparison.

RESULTS

After expansion with removable appliances, a significant increase in intermolar width was achieved and could be maintained over the observation period (p < 0.001). However, no significant changes regarding overjet, overbite, or molar sagittal occlusion were observed. Crossbite correction was successful in 86.9% of patients with unilateral crossbite and in 75.0% of patients with bilateral crossbite (p < 0.001).

CONCLUSION

Early expansion with a removable expansion plate is a successful method to correct crossbites and increase intermolar width in the early mixed dentition phase. Results remain stable until the start of comprehensive treatment in the permanent dentition.

Comparison of temporomandibular joint osseous components in unilateral and bilateral cleft lip and palate patients and normal controls: A CBCT study

OBJECTIVE

The objective of this study was to conduct a comparative analysis of the components of the temporomandibular joint in individuals with unilateral, bilateral cleft lip and palate (CLP), and in healthy individuals, utilizing cone beam computed tomography (CBCT) images.

METHOD AND MATERIAL

The present study employed a cross-sectional design and recruited participants aged 18 to 30 years. The participants were categorized into three groups: a control group consisting of 36 individuals without any cleft, a group of 35 patients with unilateral cleft lip and palate (UCLP), and a group of 15 patients with bilateral cleft lip and palate (BCLP). The analysis of CBCT images encompassed the examination of condylar height and angulation, glenoid fossa height and width, articular eminence inclination, as well as joint spaces across all three groups. The Kruskal-Wallis and Mann-Whitney tests were employed to ascertain the significant differences among the three groups.

RESULTS

The UCLP and BCLP groups demonstrated a statistically significant reduction in condylar height and articular eminence inclination in comparison to the control group. Furthermore, a significant difference in the width of the glenoid fossa was seen between the group with clefts and the control group.

CONCLUSION

The CBCT images showed significant differences in several aspects of the temporomandibular joint, including condylar height, articular eminence inclination, and glenoid fossa width, in individuals with cleft palate. These abnormalities can contribute to the development of temporomandibular joint diseases. Therefore, recognizing these distinctions can help prevent further deterioration and progression of temporomandibular disorders (TMD) in CLP patients.

Posterior crossbite corrections in the early mixed dentition with quad helix or rapid maxillary expander: a cost-effectiveness analysis of a randomized controlled trial

BACKGROUND

Unilateral posterior crossbite is a common malocclusion, and early treatment is recommended to enable normal growth. There are several possibilities regarding choice of appliances used for correcting this malocclusion; however, when treatment is financed by public funds the decision needs to be based not only on the effects but also on the effect in relation to the costs.

OBJECTIVES

The aim was to perform a cost-effectiveness analysis comparing quad helix (QH) and rapid maxillary expanders (RME; hyrax-type) in children in the early mixed dentition.

MATERIAL AND METHODS

Seventy-two patients were randomized to treatment with either QH or RME, at two different centres. Data were collected from the patient's medical records regarding success rate, number of visits, total treatment time, emergency visits, and so forth, together with answers from patient questionnaires concerning absence from school and use of analgesics. A cost-effectiveness analysis with both an intention-to-treat (ITT) and a per-protocol approach was performed, as well as a deterministic sensitivity analysis.

RESULTS

The success rate, one year after the completion of the expansion, was equal between groups according to the ITT approach. From a healthcare perspective, the mean cost difference between RME and QH was €32.05 in favour of QH (P = 0.583; NS). From a societal perspective, the mean cost difference was €32.61 in favour of QH (P = 0.742; NS). The total appliance cost alone was higher in the RME group €202.67 resp. €155.58 in the QH group (P = 0.001). The probability of RME having a higher cost was 71% from a healthcare perspective and 62.7% from a societal perspective. The total treatment time was 97 days longer in the QH group. In the deterministic sensitivity analysis, when using a higher valuation of the children's educational loss, the QH becomes €58 more costly than the RME. There was a statistically significant difference in chair time and visits between centres (P < 0.001).

CONCLUSION

The difference in costs between RME and QH is not statistically significant, however, there is a slightly higher probability that RME is more expensive than QH with a mean cost of an additional €32 per patient from a healthcare perspective. Different work procedures at different centres indicate that logistics around the patient's treatment is a more important aspect than appliance used to decrease the number of visits and save chair time and thereby also costs.

Soft tissue compensation evaluation in patients with facial asymmetry using cone-beam computed tomography combined with 3D facial photographs

Objectives

This study aimed to evaluate bilateral soft tissue, hard and soft-tissue thickness at various anatomical levels in patients with facial asymmetries. Moreover, we attempted to find out correlation between soft-tissue compensation and severity of asymmetry by using cone-beam computed tomography (CBCT) combined with 3D facial photographs.

Study design

Based on menton deviation (MD), twenty-four subjects were divided into: mild-asymmetry group (n=12) and moderate-to-severe-asymmetry group (n = 12). CBCT images were superimposed with 3D facial photographs. Distance from the midsagittal plane to the outermost point of soft-tissue and hard-tissue were measured and calculated soft-tissue thickness. Comparison of soft-tissue thickness between deviated and contralateral side at any anatomical levels were performed within group, and correlation between bilateral soft-tissue thickness subtractions (soft-tissue compensation) and MD values was evaluated.

Results

Within group, Soft- and hard-tissue distances were greater in deviated side than contralateral side at any levels. In moderate-to-severe group, significant differences were found at gonion and body of mandible level, whereas soft-tissue thickness was only found to be higher on deviated side at the level of mandibular ramus. Soft tissue compensation was negatively correlated with MD value at level of mandibular ramus (R = -0.5, P < 0.05).

Conclusions

Asymmetry was found to be larger in the lower third of the face and was notably remarkable in the moderate-to-severe group. Soft-tissue thickness was thicker on the deviated side of the mandibular ramus. Thus, the soft-tissue compensation seems to be minimized in patients with more severe asymmetry.

Mandibular Endochondral Growth Is Specifically Augmented by Nutritional Supplementation with Myo-Inositol Even in Rabbits

Mandibular retrognathism occurs by insufficient mandibular growth and causes several issues, such as respiratory difficulty and diminished masticatory function. At present, functional orthodontic appliances are used for stimulating mandibular growth in pediatric cases. However, the effectiveness of functional appliances is not always stable in daily practices. A more effective, reliable, and safer therapeutic method for mandibular growth promotion would be helpful for growing mandibular retrognathism patients. As we previously discovered that nutritional supplementation of myo-inositol in growing mice specifically increases mandibular endochondral growth, we performed preclinical animal experiments in rabbits in this study. Briefly, six-week-old male Japanese white rabbits were fed with or without myo-inositol supplementation in laboratory chow until 25 weeks old, and 3D image analysis using micro CT data and histological examinations was done. Myo-inositol had no systemic effect, such as femur length, though myo-inositol specifically augmented the mandibular growth. Myo-inositol increased the thickness of mandibular condylar cartilage. We discovered that the nutritional supplementation of myo-inositol during the growth period specifically augmented mandibular growth without any systemic influence, even in rabbits. Our results suggest the possibility of clinical use of myo-inositol for augmentation of the mandibular growth in growing mandibular retrognathism patients in the future.

Analysis of mandibular asymmetry in adolescent and adult patients with unilateral posterior crossbite on cone-beam computed tomography

INTRODUCTION

This study aimed to evaluate mandibular asymmetry in unilateral posterior crossbite (UPXB) patients and compare the asymmetry between adolescents and adults with UPXB.

METHODS

This study included and analyzed cone-beam computed tomography scans of 125 subjects. The subjects were divided into a UPXB group and a control group according to the presence or absence of UPXB, and each group included adolescent patients (aged 10-15 years) and adult patients (aged 20-40 years). Linear, angular, and volumetric measurements were obtained to evaluate the asymmetries of the mandibles.

RESULTS

Both adolescent and adult patients in the UPXB group presented asymmetries in condylar unit length, ramal height, body length, and mediolateral ramal inclination (P <0.05). Adult patients with UPXB showed greater asymmetries than adolescents. Differences with condylar unit length, condylar unit width, ramal height, condylar unit volume, and hemimandibular volume were significantly greater in adult UPXB patients than adolescent UPXB patients (P <0.05).

CONCLUSIONS

The worsening of mandibular asymmetries in UPXB adults suggests that asymmetry in UPXB patients may progress over time; therefore, early treatment should be considered for UPXB adolescent patients. Further studies are still needed to evaluate the effectiveness of early treatment.

The Facial Characteristics of Individuals with Posterior Crossbite: A Cross-Sectional Study

Facial morphology is known to be influenced by genetic and environmental factors. Scientific evidence regarding facial parameters in patients with posterior crossbite is lacking. This study aimed to investigate the association between posterior crossbite and facial parameters. This cross-sectional study included 34 adolescents with and 34 adolescents without posterior crossbite in the age range from 13 to 15 years. Facial surface scans were acquired with a 3dMD imaging system, and landmark-based analysis was performed. Data were analyzed using the Mann-Whitney U test and Spearman's correlations. Individuals in the control group had lower face heights (females: p = 0.003, r = 0.45; males: p = 0.005, r = 0.57). The control group females presented with smaller intercanthal width (p = 0.04; r = 0.31) and anatomical nose width (p = 0.004; r = 0.43) compared with the crossbite group females. The males in the control group had wider nostrils. In the control group, significant correlations among different facial parameters were more common, including the correlations between eye width and other transversal face measurements. On the contrary, the facial width was correlated with nasal protrusion (r = 0.657; p < 0.01) and the morphological width of the nose (r = 0.505; p < 0.05) in the crossbite group alone. In both groups, the philtrum width was linked with the anatomical and morphological widths of the nose. Conclusions: Patients with posterior crossbites have increased face height and different patterns of facial proportions compared with individuals without crossbites.

Comparison of Mandibular Volume and Linear Measurements in Patients with Mandibular Asymmetry

In patients with mandibular asymmetry, the volume of the mandible divided by the mandibular median plane is significantly larger on the non-deviated (N-Dev) side than on the deviated (Dev) side. However, it has been reported that there is no significant difference between the volumes of the N-Dev and Dev sides when the mandibular ramus and body are divided. The purpose of this study was to investigate which region is responsible for the volume difference between the N-Dev and Dev sides. Cone Beam Computed Tomography (CBCT) images of patients with mandibular asymmetry were analyzed by measuring the volume, and linear analysis of the mandibular body, ramus, and condyle on the N-Dev and Dev side was performed. In this study, CBCT images of 37 patients (8 Japanese, 16 Korean, and 13 Egyptian) aged ≥ 18 years with mandibular asymmetry (men: 20, women: 17) were used to evaluate mandibular asymmetry. In patients with mandibular asymmetry, the N-Dev side showed significantly larger values than the Dev side for both volume and linear condyle, ramus, and mandibular body measurements. These results do not differ according to sex or ethnicity. Therefore, it is suggested that the N-Dev side of mandibular asymmetry is large without any regional specificity in pathophysiology.

A pilot investigation of condylar position and asymmetry in patients with unilateral posterior scissors-bite malocclusion based on three-dimensional reconstructive imaging technique

OBJECTIVE

Unilateral posterior scissors-bite (uPSB) malocclusion is common clinically. This study aimed to investigate the condylar morphological alterations and condyle-fossa relationship in patients with uPSB, through cone beam computed tomography (CBCT) and three-dimensional reconstructive imaging technique.

METHODS

A retrospective study was designed to comparatively analyze 95 patients with uPSB between July 2016 and December 2021. They were divided into three subgroups: 12 to 20, 21 to 30, and ≥ 31 years, according the age distribution. The morphological parameters regarding condyle, fossa, and joint space after three-dimensional reconstruction were measured and analyzed by a series of digital software. SPSS 26.0 software package was performed for statistical analysis on data sets, using paired t-test, one-way analysis of variance, Wilcoxon signed-rank sun test, Kruskal-Wallis H test, and Bonferroni correction.

RESULTS

The condylar volume (CV) of scissors-bite side was greater than that of the non-scissors-bite side (CV _A = 1740.68 ± 559.80 mm³ > CV _N = 1662.25 ± 524.88 mm³, P = 0.027). So was the condylar superficial area (CSA) (CSA _A = 818.71 ± 186.82 mm² > CSA _N = 792.63 ± 173.44 mm², P = 0.030), and the superior joint space (SJS) [SJS _A = 2.46 (1.61, 3.68) mm) > SJS _N = 2.01 (1.55, 2.87) mm), P = 0.018], and the anterior joint space (AJS) (AJS _A = 3.94 ± 1.46 mm > AJS _N = 3.57 ± 1.30 mm, P = 0.017). The constituent ratios of the different parts of the bilateral condyles were 23% on the posterior slope, 21% on the top, 20% on the anterior slope, 19% on the lateral slope and 17% on the medial slope, respectively.

CONCLUSION

Due to long-term abnormal occlusion of uPSB, the pathological bite force in temporomandibular joint would cause changes in the shape of the condyle. Among them, CV, CSA, SJS and AJS had significant changes in the scissors-bite status, which has the greatest damage to the posterior slope of the condyloid process.

Hard and Soft Tissue Asymmetry in Patients with Skeletal Class III Malocclusion: A Cone-Beam Computed Tomography Study

This study aims to investigate hard and soft tissue asymmetry in skeletal Class III patients to elucidate how soft tissue thickness alters overall asymmetry and whether menton deviation is correlated with bilateral differences in hard and soft tissue prominence and soft tissue thickness. The cone-beam computed tomography data of 50 skeletal Class III adults were divided based on menton deviation into symmetric (n = 25; deviation ≤ 2.0 mm) and asymmetric (n = 25; deviation > 2.0 mm) groups. Forty-four corresponding hard and soft tissue points were identified. Bilateral hard and soft tissue prominence and soft tissue thickness were compared using paired t-tests. The correlations between bilateral differences in these variables and menton deviation were examined using Pearson's correlation analysis. In the symmetric group, no significant bilateral differences in soft and hard tissue prominence and soft tissue thickness were observed. In the asymmetric group, both hard and soft tissue prominence were significantly greater on the deviated side than the non-deviated side at most of the points; however, no significant differences in soft tissue thickness were detected except at point 9 (ST9/ST'9, p = 0.011). The difference of hard and soft tissue prominence at point 8 (H8/H'8 and S8/S'8) was positively correlated with menton deviation, whereas the soft tissue thickness at point 5 (ST5/ST'5) and point 9 (ST9/ST'9) was negatively correlated with menton deviation (p = 0.05). Soft tissue thickness does not affect overall asymmetry in the presence of underlying hard tissue asymmetry. Soft tissue thickness at the centre of the ramus may be correlated with the degree of menton deviation in patients with asymmetry; however, this correlation needs to be confirmed by further studies.

Comprehensive Dental Treatment under General Anesthesia Improves Mastication Capability in Children with Early Childhood Caries-A One-Year Follow-Up Study

BACKGROUND

Using the granulometry of ready-to-swallow food boluses, this study investigated the evolution of masticatory capability of children with Early Childhood Caries (ECC) after comprehensive dental treatment under general anesthesia (GA).

METHODS

Sixteen children with ECC were assessed before and over one year after dental treatment under GA, in comparison with 12 children with a Healthy Oral State (HOS). Oral health criteria, quality of life, body mass index, and frequency of orofacial dysfunctions were recorded. Masticatory kinematic parameters and median food bolus particle size (D50) at swallowing were assessed while masticating raw carrot (CAR), cheese (CHS), and breakfast cereals (CER). The impact of posterior teeth extractions was analyzed.

RESULTS

Quality of life and orofacial functions improved after dental treatment. Chewing frequency for all three foods increased without reaching the values of children with HOS, while D50 values for CAR and CHS decreased. After one year, children with posterior teeth extractions exhibited higher D50 values for CAR and CHS than children with only conservative treatment. One third of children with ECC were overweight or obese.

CONCLUSIONS

Comprehensive dental treatment improved children's mastication, and their BMI subsequently increased. Links between mastication and nutrition should be investigated further in children.

Spontaneous correction and new development of posterior crossbite from the deciduous to the mixed dentition

AIM

To determine (a) the prevalence of spontaneous correction of posterior crossbites from the deciduous to the mixed dentition and (b) the development of new posterior crossbite cases during the eruption of the first permanent molars, in orthodontically untreated children.

MATERIALS AND METHODS

A cohort of pupils aged 4-12 years participated in annual dental screenings, from 2001 to 2019. Data were collected prospectively but examined retrospectively. Children were selected who had been initially screened in their deciduous dentition and on at least one consecutive year, presenting with a posterior crossbite in the deciduous or mixed dentition. Those with a posterior crossbite in the deciduous dentition were evaluated to see whether the crossbite persisted in the mixed dentition, and vice versa.

RESULTS

Of the 2571 children participating in the annual dental screenings, 1076 children were in the deciduous dentition at their first screening appointment, with 693 having attended at least two screening appointments. Of these 693 children, 70 had a posterior crossbite in the deciduous dentition (10.1%). The crossbite persisted in the mixed dentition in only 16 out of these 70 children. Twenty-six out of the 623 children who did not have a posterior crossbite in the deciduous dentition developed one in the mixed dentition.

LIMITATIONS

The retrospective data collection, multiple examiners carrying out the dental screenings, and the absence of data on para-functions and oral habits were some of the limitations of the present study.

CONCLUSIONS

In the present sample, 1 in 10 children have a posterior crossbite in the deciduous dentition, which is however autocorrected in about three-quarters of cases. On the other hand, 4% of children developed a new crossbite in the mixed dentition. It may thus be reasonable in cases with posterior crossbite in the deciduous dentition to wait for the first permanent molars to erupt before initiating treatment.

A New Approach to Diagnosis to Posterior Cross Bite: Intraoral Photography and Wala Ridge

A posterior crossbite is an occlusion disorder that occurs in the transverse plane. It occurs when the buccal cusps of the upper premolars and molars engage lingually with the buccal cusps of the lower teeth. It can be unilateral or bilateral (involving one or more teeth) in the primary, mixed, or permanent dentition. A crossbite may appear in early dentition stages and it can be dental or functional. It can lead to skeletal crossbite in mixed dentition. Therefore, early diagnosis and treatment are crucial. Material and methods: The selected sample included 204 patients in growing stage divided into two groups: a study group of 102 patients with posterior crossbite and a control group of 102 patients without malocclusion. To analyze the pathology, intraoral frontal photographs and study models were taken, in which the bone component was measured from the Wala Ridge. Results: The use of the photographs to study the Wala Ridge was confirmed. The mean maxillary width was 57.8 mm (SD 1.7) and mandibular width was 56.4 mm (SD 1.7) for the control group, with a maxillomandibular difference of 1.4 mm (SD 0.7); and 52.7 mm (SD 3.7) and 55.5 mm (SD 3.6), respectively, with a maxillomandibular difference of −2.8 mm (SD 1.4) for the study group. A higher maxillomandibular discrepancy was observed in patients with a posterior crossbite that involved more than one tooth in addition to the permanent first molar. It was also higher in patients with bilateral posterior crossbite. Conclusions: Intraoral frontal photography can be used as a diagnostic method to measure the maxillomandibular difference using the Wala Ridge.

Comparison of the bite force and occlusal contact area of the deviated and non-deviated sides after intraoral vertical ramus osteotomy in skeletal Class III patients with mandibular asymmetry: Two-year follow-up

Objective

The objectives of this study were to compare the time-dependent changes in occlusal contact area (OCA) and bite force (BF) of the deviated and non-deviated sides in mandibular prognathic patients with mandibular asymmetry before and after orthognathic surgery and investigate the factors associated with the changes in OCA and BF on each side.

Methods

The sample consisted of 67 patients (33 men and 34 women; age range 15-36 years) with facial asymmetry who underwent 2-jaw orthognathic surgery. OCA and BF were taken before presurgical orthodontic treatment, within 1 month before surgery, and 1 month, 3 months, 6 months, 1 year, and 2 years after surgery. OCA and BF were measured using the Dental Prescale System.

Results

The OCA and BF decreased gradually before surgery and increased after surgery on both sides. The OCA and BF were significantly greater on the deviated side than on the non-deviated side before surgery, and there was no difference after surgery. According to the linear mixed-effect model, only the changes in the mandibular plane angle had a significant effect on BF (p < 0.05).

Conclusions

There was a difference in the amount of the OCA and BF between the deviated and non-deviated sides before surgery. The change in mandibular plane angle affects the change, especially on the non-deviated side, during the observation period.

Evaluation of Electromyographic Activity of Masticatory Muscles in Adults with Posterior Crossbite

Introduction

There is evidence that patients with posterior crossbite (PXB) have neuromuscular changes in the masticatory muscles. However, up to the present time, the relationship among these changes on the electromyographic activity of the masticatory muscles is still unclear.

Objective

To systematic review the available literature on the electromyographic activity of masticatory muscles in adults with PXB.

Methods

Between August 22 and September 9, 2020, we searched the following seven electronic databases: PubMed, EMBASE, Web of Science, Cochrane Library, SciELO, LILACS, and Scopus. No restrictions were applied regarding the language and year of publication. This systematic review was registered in the Prospective Register of Systematic Reviews (PROSPERO - CRD42020205057) database and conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. After data selection and extraction, the methodological quality of the selected studies was conducted independently by two reviewers, using two different evaluation tools.

Results

6957 records were initially located after the search process. In the end, eight papers were selected. Most studies were classified as having average to low methodological quality and moderate to high risk of bias. Based on the available evidence, adult patients with PXB have electromyographic activity changes in the masticatory muscles when compared with individuals without PXB. Moreover, adult patients with unilateral posterior crossbite (UPXB) have asymmetrical electromyographic activity when the crossbite side is compared with the noncrossbite side.

Conclusion

Despite the lack of studies with high methodological quality, electromyographic evaluation of masticatory muscles should be considered in the diagnosis and in the orthodontic treatment plan of patients with PXB. Prospective studies with a higher sample size and follow-up time, conducted using a rigorous scientific methodology, are necessary to reach a more reliable conclusion.

Craniofacial characteristics and cosmetic satisfaction of patients with sagittal and metopic synostosis: a case-control study using 3D photogrammetric imaging

PURPOSE

The aim of this study was to investigate the craniofacial and aesthetic characteristics of adult metopic and sagittal craniosynostosis patients operated on in early childhood compared to controls. The goal was to find objective measurements that would correlate with the patient's subjective self-evaluation of their own cosmetic appearance.

METHODS

The study population consisted of 49 patients from whom 41 had premature fusion of the sagittal and in 8 of metopic suture. There were 65 age and gender matching controls from The Finish National Register. The 3D photogrammetric models were created from all patients and controls. The images were analysed using Rapidform 2006. Facial landmarks were set by the standard Farkas points. Facial symmetry parameters were calculated by using the landmarks and the mirror shell of the face. Aesthetic evaluation was done from standard photographs using panels. Subjective satisfaction with one's own appearance was evaluated using questionnaires.

RESULTS

Patients had the greatest asymmetry in the forehead area when compared to controls (symmetry percentage 59% versus 66%, p = 0.013). In the control group, the gap between the eyes was smaller than in the case group, resulting in an absolute 2 mm difference (p = 0.003). The area of the chin and the landmarks were more located on the left side in the patient group, resulting in up to a 1.1 mm difference between the groups (p = 0.003). Only a weak association was found between craniofacial symmetry and appearance evaluations.

CONCLUSION

Patients operated on because of sagittal and metopic synostoses were found to have facial asymmetry at long follow-up. However, the differences were < 3 mm and not clinically important. The long-term aesthetical outcome of the surgery performed because of sagittal or metopic craniosynostosis based on the 3D image evaluation was good.

Orthodontic treatment for posterior crossbites

BACKGROUND

A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. The prevalence of posterior crossbite is around 4% and 17% of children and adolescents in Europe and America, respectively. Several treatments have been recommended to correct this problem, which is related to such dental issues as tooth attrition, abnormal development of the jaws, joint problems, and imbalanced facial appearance. Treatments involve expanding the upper jaw with an orthodontic appliance, which can be fixed (e.g. quad-helix) or removable (e.g. expansion plate). This is the third update of a Cochrane review first published in 2001.

OBJECTIVES

To assess the effects of different orthodontic treatments for posterior crossbites.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 8 April 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of orthodontic treatment for posterior crossbites in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, screened the results of the electronic searches, extracted data, and assessed the risk of bias of the included studies. A third review author participated to resolve disagreements. We used risk ratios (RR) and 95% confidence intervals (CIs) to summarise dichotomous data (event), unless there were zero values in trial arms, in which case we used odds ratios (ORs). We used mean differences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-effect models. We used the GRADE approach to assess the certainty of the evidence for the main outcomes.

MAIN RESULTS

We included 31 studies that randomised approximately 1410 participants. Eight studies were at low risk of bias, 15 were at high risk of bias, and eight were unclear. Intervention versus observation For children (age 7 to 11 years), quad-helix was beneficial for posterior crossbite correction compared to observation (OR 50.59, 95% CI 26.77 to 95.60; 3 studies, 149 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 4.71 mm, 95% CI 4.31 to 5.10; 3 studies, 146 participants; moderate-certainty evidence). For children, expansion plates were also beneficial for posterior crossbite correction compared to observation (OR 25.26, 95% CI 13.08 to 48.77; 3 studies, 148 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 3.30 mm, 95% CI 2.88 to 3.73; 3 studies, 145 participants, 3 studies; moderate-certainty evidence). In addition, expansion plates resulted in higher inter-canine distances (MD 2.59 mm, 95% CI 2.18 to 3.01; 3 studies, 145 participants; moderate-certainty evidence). The use of Hyrax is probably effective for correcting posterior crossbite compared to observation (OR 48.02, 95% CI 21.58 to 106.87; 93 participants, 3 studies; moderate-certainty evidence). Two of the studies focused on adolescents (age 12 to 16 years) and found that Hyrax increased the inter-molar distance compared with observation (MD 5.80, 95% CI 5.15 to 6.45; 2 studies, 72 participants; moderate-certainty evidence). Intervention A versus intervention B When comparing quad-helix with expansion plates in children, quad-helix was more effective for posterior crossbite correction (RR 1.29, 95% CI 1.13 to 1.46; 3 studies, 151 participants; moderate-certainty evidence), final inter-molar distance (MD 1.48 mm, 95% CI 0.91 mm to 2.04 mm; 3 studies, 151 participants; high-certainty evidence), inter-canine distance (0.59 mm higher (95% CI 0.09 mm  to 1.08 mm; 3 studies, 151 participants; low-certainty evidence) and length of treatment (MD -3.15 months, 95% CI -4.04 to -2.25; 3 studies, 148 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and Haas for posterior crossbite correction (RR 1.05, 95% CI 0.94 to 1.18; 3 studies, 83 participants; moderate-certainty evidence) or inter-molar distance (MD -0.15 mm, 95% CI -0.86 mm to 0.56 mm; 2 studies of adolescents, 46 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and tooth-bone-borne expansion for crossbite correction (RR 1.02, 95% CI 0.92 to 1.12; I² = 0%; 3 studies, 120 participants; low-certainty evidence) or inter-molar distance (MD -0.66 mm, 95% CI -1.36 mm to 0.04 mm; I² = 0%; 2 studies, 65 participants; low-certainty evidence).  There was no evidence of a difference between Hyrax with bone-borne expansion for posterior crossbite correction (RR 1.00, 95% CI 0.94 to 1.07; I² = 0%; 2 studies of adolescents, 81 participants; low-certainty evidence) or inter-molar distance (MD -0.14 mm, 95% CI -0.85 mm to 0.57 mm; I² = 0%; 2 studies, 81 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: For children in the early mixed dentition stage (age 7 to 11 years old), quad-helix and expansion plates are more beneficial than no treatment for correcting posterior crossbites. Expansion plates also increase the inter-canine distance. Quad-helix is more effective than expansion plates for correcting posterior crossbite and increasing inter-molar distance. Treatment duration is shorter with quad-helix than expansion plates. For adolescents in permanent dentition (age 12 to 16 years old), Hyrax and Haas are similar for posterior crossbite correction and increasing the inter-molar distance. The remaining evidence was insufficient to draw any robust conclusions for the efficacy of posterior crossbite correction.

Posterior crossbite with mandibular asymmetry treated with lingual appliances, maxillary skeletal expanders, and alveolar bone miniscrews

Posterior crossbite and mandibular asymmetry affect esthetics and function. We report treatment of 3 patients with posterior crossbite with mandibular asymmetry but different anteroposterior and vertical characteristics. Treatment methods included maxillary skeletal expander, miniscrews, and lingual appliances. The results show that by using these appliances, ideal transverse, anteroposterior, and vertical control is possible in patients who have concerns about the esthetics of buccal appliances. Lingual appliances can provide satisfying results when combined with a maxillary skeletal expander and miniscrews in complex patients.

Mandibular asymmetry in young adult patients with unilateral posterior crossbite: A controlled retrospective CBCT study

OBJECTIVE

This study aimed to evaluate the mandibular skeletal asymmetry in pre-orthodontic patients with the unilateral posterior dental crossbite (UPCB).

MATERIALS AND METHODS

Using a retrospective design, 30 pre-orthodontic patients with a UPCB, (16 on the right side, 14 on the left side), 18 females and 12 males were selected (mean age: 21.2±4.92 years), along with 30 controls matched by age and sex with cl I occlusal relationship (mean age: 21.9±4.80 years). The patients were from an Orthodontic Department of Dental Faculty of Hamadan University of Medical Sciences and a private office from 2009 to 2013. In the UPCB group, at least one molar tooth was in the crossbite position. All the patients had initial CBCT¹ and pre-orthodontic study models. 10 linear and 3 angular measurements were performed to evaluate the mandibular skeletal asymmetry. repeated measure-ANCOVA² by controlling the effect of age and sex, T-test and paired-samples t-test were used for comparisons. Measurement's reliability was measured with ICC³ test.

RESULTS

There was a positional deviation of mandible to the crossbite side 95% CI⁴ (0.166 - 1.087). The intergroup analysis showed that Corpus Length (P≤0.014), Ramus Angle in frontal view (P≤0.046), and Condylar-Width in axial view (P≤0.029) in the crossbite side of the case group were significantly smaller than the control group. In the subjects with UPCB, mandibular condylar width was smaller in the crossbite side (17.31±2.50) relative to the non-crossbite side (18.06±2.18).

CONCLUSIONS

The adults with dental UPCB, in addition to deviation to crossbite side, may show smaller condylar head and Corpus length in crossbite side relative to the control group.

Evaluation of mandibular changes after rapid maxillary expansion: a CBCT study in youngsters with unilateral posterior crossbite using a surface-to-surface matching technique

OBJECTIVES

The purpose of this study was to evaluate mandibular asymmetry in youngsters with posterior unilateral crossbite (PUXB), through cone-beam computed tomography and reverse engineering technique, before and after rapid maxillary expansion (RME) treatment.

MATERIALS AND METHODS

Forty cone-beam computed tomography (CBCT) images were obtained from all patients at two time points, namely T0 acquired before the placement of a Hyrax expander and T1 after appliance removal. The CBCT scans were segmented and volume rendered into a surface there-dimensional (3D) mesh model. Thereafter, mandibular models were digitally registered by using a "best-fit" algorithm. Surface and volumetric changes, between T0 and T1, were compared by using Student's t tests.

RESULTS

A slight increase of 0.45 cm3 of the total mandibular volume was found at T1 when compared with T0 (p < 0.001). The mandibular hemi-volume on the crossbite side (CB) was slightly smaller than the non-crossbite side both at T0 and T1. However, the mean differences of hemi-volume from the CB (crossbite) and non-CB side between T0 and T1 show a decrease of 0.26 cm3 (p < 0.001). Findings for the surface-to-surface deviation analysis demonstrated a fine percentage of matching at T0 which slightly improved at T1 (p < 0.001).

CONCLUSIONS

Youngsters affected by PUXB showed a very slight and not statistically significant volumetric and morphological asymmetry between CB side and non-CB side at T0. However, the change in mean differences of 0.26 cm cannot be considered clinically relevant.

CLINICAL RELEVANCE

Mandibles in young PUXB patients exhibit only a very mild mandibular asymmetry. Although the statistically significant mean change found right after RME removal cannot be considered clinically relevant, a more consistent sample and a longer follow-up could be of interest in explaining the short-term findings.

Genetic factors contributing to skeletal class III malocclusion: a systematic review and meta-analysis

OBJECTIVES

The present systematic review aims to report and critically assess the findings of the available scientific evidence from genetic association studies examining the genetic variants underlying skeletal class III malocclusion and its sub-phenotypes.

MATERIAL AND METHODS

A pre-piloted protocol was registered and followed. The PubMed, Scopus, WOS, Cochrane Library, Gray Open literature, and CADTH databases were explored for genetic association studies following PICOS-based selection criteria. The research was reported in accordance with PRISMA statement and HuGE guidelines. The Q-genie tool was applied to assess the quality of genetic studies. Meta-analysis of genetic association studies was done by means of Meta-Genyo tool.

RESULTS

A total of 8258 articles were retrieved, of which 22 were selected for in-depth analysis. Most of the studies did not differentiate between sub-phenotypes, and the cohorts were heterogeneous regarding ethnicity. Four to five principal components of class III malocclusion explained the phenotypic variation, and gene variants at MYO1H(rs10850110), BMP3(rs1390319), GHR (rs2973015,rs6184, rs2973015), FGF7(rs372127537), FGF10(rs593307), and SNAI3(rs4287555) (p < .05) explained most of the variation across the studies, associated to vertical, horizontal, or combined skeletal discrepancies. Meta-analysis results identified a statistically significant association between risk of class III malocclusion of A allele of the FBN3 rs7351083 [OR 2.13; 95% CI 1.1-4.1; p 0.02; recessive model].

CONCLUSION

Skeletal class III is a polygenic trait substantially modulated by ethnicity. A multicentric approach should be considered in future studies to increase sample sizes, applying multivariate analysis such as PCA and cluster analysis to characterize existing sub-phenotypes warranting a deeper analysis of genetic variants contributing to skeletal class III craniofacial disharmony.

CLINICAL RELEVANCE

Grasping the underlying mechanisms of this pathology is critical for a fuller understanding of its etiology, allowing generation of preventive strategies, new individualized therapeutic approaches and more accurate treatment planification strategies.

Effect of Photobiomodulation on Relapse in an Experimental Rapid Maxillary Expansion Model in Rat

Rapid maxillary expansion (RME) is performed on transversely deficient maxilla. As all orthodontic treatments, retention is important in maintaining therapeutic outcomes. Fixed /removable retainers are used post-RME causing hygiene and compliance problems. Given photobiomodulation's positive effects on the quantity and quality of bone regeneration, its effect on post-RME relapse was studied. Thirty Sprague Dawley rats were randomly divided into group R, non-irradiated RME-treated (n = 12), group P, irradiated RME-treated (n = 12) and group C, non-RME non-irradiated (n = 6). A 1.5 mm metal ring inserted between maxillary incisors at days 0 and 15 was expanded until 1.5 mm space was obtained at day 30. In group P, Ga-Al-As diode laser (810 nm, 100 mW, 4J/cm² , 30 secs) was applied on days 0, 2, 4, 6, 8, 10, 12 and 14 as predictor variable. The relapse was measured as the space lost between incisors for 30 days after appliance removal (primary outcome variable) and compared with t-test. In week 2, space loss in group P was significantly lower (P < 0.05) than all other groups. The relapse during weeks 2 and 3 was significantly lower in group P than group R. However, no significant difference in relapse amount was found between groups during first and fourth week. There was a significant difference (P < 0.05) between groups in relapse rates (secondary outcome variable) but not in total relapse after 4 weeks. Photobiomodulation proved beneficial in resisting relapse in our study, and it is suggested to be continued until the end of expansion.

Buccal Bone Changes Around First Permanent Molars and Second Primary Molars after Maxillary Expansion with a Low Compliance Ni-Ti Leaf Spring Expander

Background: Vestibular bone thickness changes and dento-alveolar buccal tipping of second primary molars and of first molars after maxillary expansion performed with a slow maxillary expansion protocol was investigated. Methods: Twenty patients (mean age 7.3 ± 0.9 years old; 9 male and 11 female) were treated according to the Leaf Expander protocol. Buccal alveolar bone thickness (BT), buccal alveolar bone height (BH), inter-dental angle (TIP), and inter-molar width (IW) regarding first molars and second primary molars were calculated before and after expansion on cone beam computed tomography (CBCT) images. Descriptive statistics and paired t-tests were used to assess changes between the pre-treatment and post-treatment measurements. Results: Bone thickness vestibular to second primary molars and intermolar width of both teeth were the only variables that showed statistically significant changes. Conclusions: It appears that buccal bone thickness vestibular to first molars was not significantly reduced after maxillary expansion with the Leaf Expander. The clinical use of a slow maxillary expander with Ni-Ti springs appears efficient and safe in in the correction of maxillary hypoplasia during mixed dentition.

Evaluation of mandibular symmetry and morphology in adult patients with unilateral posterior crossbite: a CBCT study using a surface-to-surface matching technique

OBJECTIVES

To investigate mandibular morphology in adults affected by posterior unilateral crossbite (PUXB) and to evaluate the hemi mandibular volumes from the crossbite (CB) and non-CB sides of the same patients.

METHODS

Thirty-eight cone beam computed tomography (CBCT) images were consecutively recruited and the Digital Imaging and Communications in Medicine (DICOM)-formatted scans were volume rendered into a surface three-dimensional (3D) mesh model and volumes to obtain the 3D model of the mandibular bone. To achieve the surface point-to-point analysis of the mandibular models, a reverse engineering software was used. The same procedure was performed for an age-matched control group (19 CBCT images).

RESULTS

Total mandibular volume showed a difference of 2.46 cm3 between patients and controls, which was not statistically significant. A mean difference of 1.53 cm3 was found comparing the hemi mandibular volumes from the CB and non-CB sides of PUXB patients, this difference was statistically significant (P ≤ 0.01). Findings for the surface-to-surface deviation analysis, demonstrated a higher percentage of mismatch in patients PUXB, over 10% at 0.5 mm tolerance level.

LIMITATIONS

Limitations are related to the intrinsic surfaces matching methodology, that make difficult to evaluate discrepancies among different mandibular anatomical units.

CONCLUSION

Adult patients affected by PUXB show a greater mandibular structural asymmetry compared to controls because of a lower matching percentage obtained from the surface-to-surface matching technique.

IMPLICATIONS

Treatment of adult patients affected by PUXB should take into consideration the possibility of a mild mandibular asymmetry mainly localized at the condyle and gonial angle levels.

Impact of post-orthodontic dental occlusion on masticatory performance and chewing efficiency

BACKGROUND

Whether precise orthodontic detailing of occlusion impacts masticatory function is unknown. In this study, we aimed to assess the impact of post-orthodontic dental occlusion on masticatory performance and chewing efficiency.

MATERIALS AND METHODS

Fifty-four adults who completed orthodontic treatment were categorized into two groups using the American Board of Orthodontics (ABO) model grading system: one meeting ABO standards (ABO, N = 29), the other failing to meet them (non-ABO, N = 25). The electromyographic (EMG) signals of the anterior temporalis (AT) and superficial masseter muscles were recorded bilaterally during static (clenching) and dynamic (gum chewing) tests. Chewing efficiency was measured by calculating the median particle size (MPS) and broadness of particle distribution (BPD) after five chewing trials of experimental silicone food at a standardized chewing rate.

RESULTS

Participants of the ABO group had a slightly more symmetric activation of the AT muscles during clenching (P = 0.016) and chewed a gum at a slower rate (P = 0.030). During the standardized chewing test with silicone food, ABO subjects had slightly greater EMG potentials at all muscle locations than non-ABO individuals (all P < 0.05). MPS and BDP did not differ significantly between groups (all P > 0.05).

LIMITATIONS

The severity of the initial malocclusion of the study participants was not in the statistical model as a potential confounder on the outcome measures.

CONCLUSIONS

Meeting ABO standards contributes to a slightly more balanced activation of the temporalis muscles during clenching and more efficient muscle recruitment during chewing but does not improve chewing efficiency.

Effect of functional lateral shift of the mandible on hyaluronic acid metabolism related to lubrication of temporomandibular joint in growing rats

BACKGROUND

Hyaluronic acid (HA) is a major molecular component of the articular cartilage of the temporomandibular joint (TMJ) influencing joint lubrication. Functional lateral shift of the mandible (FLSM) can lead to malocclusion. This study investigated the effects of FLSM on HA metabolism and lubrication of the TMJ in growing rats.

METHODS

Thirty 5-week-old male Wistar rats were divided into shift, recovery, and control groups. Rats in the shift and recovery groups were fitted with guiding plates to produce a 2-mm FLSM which were removed from the rats in the recovery group 14 days later. Animals were sacrificed at 14 and 28 days after the appliances were attached. Immunohistochemistry of HA-binding protein (HABP), hyaluronan synthase (HAS), and hyaluronoglucosaminidases (HYALs) was examined.

RESULTS

The thickness of HABP-positively stained areas in the lateral regions in the bilateral condyle was reduced during the experimental period in the shift group compared with that in the control group. The proportion of HAS2-stained areas was bilaterally decreased in different regions of condylar cartilage during the experimental period in the shift group. The reduction of the HYAL2-stained area proportion in the condylar cartilage was more significant than that of HYAL1 at 14 days after appliance attachment in the shift group. HAS2 staining was not recovered in the recovery group.

LIMITATIONS

This research was based on animal experiments with a limited experimental period.

CONCLUSION

FLSM altered lubrication related HA metabolism in the articular cartilage of the TMJ in growing rats.

The intensity of awake bruxism episodes is increased in individuals with high trait anxiety

OBJECTIVES

Trait anxiety is associated with an increased occurrence of awake bruxism episodes, a behavior characterized by clenching of the teeth contributing to temporomandibular disorders in some individuals. Here we measured the activity of the masseter and the intensity and duration of spontaneous wake-time tooth clenching episodes in healthy individuals with different levels of trait anxiety (TA).

MATERIALS AND METHODS

Two hundred fifty-five individuals completed a web survey. Using their TA scores, we allocated them in low (< 20^th percentile of the TA score distribution), intermediate (between 20^th and 80^th ), and high (> 80^th) TA groups. We analyzed the electromyographic (EMG) activity of the right masseter during a 15-min silent reading task in forty-three individuals with low (n = 12), intermediate (n = 17), and high TA (n = 14). We tested between-group differences in EMG activity of the masseter, as well as postural activity-the muscular activity that maintains mandibular posture, and amplitude and duration of spontaneous tooth clenching episodes.

RESULTS

The activity of the masseter (mean ± SEM %maximum voluntary contraction/MVC) was greater in the high TA (10.23 ± 0.16%MVC) than the intermediate (8.49 ± 0.16%MVC) and low (7.97 ± 0.22%MVC) TA groups (all p < 0.001). Postural activity did not differ between groups (all p > 0.05). The EMG amplitude of tooth clenching episodes was greater in the high TA (19.97 ± 0.21 %MVC) than the intermediate (16.40 ± 0.24%MVC) and low (15.48 ± 0.38 %MVC) TA groups (all p < 0.05). The cumulative duration of clenching episodes was not different between groups (p = 0.390).

CONCLUSIONS

Increased TA is associated with both increased masseter muscle activity and intensity of wake-time tooth clenching episodes.

CLINICAL RELEVANCE

TA may contribute significantly to masticatory muscle overload.

Condyle modeling stability, craniofacial asymmetry and ACTN3 genotypes: Contribution to TMD prevalence in a cohort of dentofacial deformities

Craniofacial asymmetry, mandibular condylar modeling and temporomandibular joint disorders are common comorbidities of skeletally disproportionate malocclusions, but etiology of occurrence together is poorly understood. We compared asymmetry, condyle modeling stability and temporomandibular health in a cohort of 128 patients having orthodontics and orthognathic surgery to correct dentofacial deformity malocclusions. We also compared ACTN3 and ENPP1 genotypes for association to clinical conditions. Pre-surgical posterior-anterior cephalometric and panometric radiographic analyses; jaw pain and function questionnaire and clinical examination of TMD; and SNP-genotype analysis from saliva samples were compared to assess interrelationships. Almost half had asymmetries in need of surgical correction, which could be subdivided into four distinct morphological patterns. Asymmetric condyle modeling between sides was significantly greater in craniofacial asymmetry, but most commonly had an unanticipated pattern. Often, longer or larger condyles occurred on the shorter mandibular ramus side. Subjects with longer ramus but dimensionally smaller condyles were more likely to have self-reported TMD symptoms (p = 0.023) and significantly greater clinical diagnosis of TMD (p = 0 .000001), with masticatory myalgia most prominent. Genotyping found two significant genotype associations for ACTN3 rs1671064 (Q523R missense) p = 0.02; rs678397 (intronic SNP) p = 0.04 and one significant allele association rs1815739 (R577X nonsense) p = 0.00. Skeletal asymmetry, unusual condyle modeling and TMD are common and interrelated components of many dentofacial deformities. Imbalanced musculoskeletal functional adaptations and genetic or epigenetic influences contribute to the etiology, and require further investigation.

Three-Dimensional Evaluation of Slow Maxillary Expansion with Leaf Expander vs. Rapid Maxillary Expansion in a Sample of Growing Patients: Direct Effects on Maxillary Arch and Spontaneous Mandibular Response

The aim is to evaluate the effects of slow maxillary expansion on maxillary and mandibular arch, using a slow maxillary expander (SME-Leaf Expander) banded on primary second molar. Ninety patients with transverse maxillary deficiency and posterior crossbite were selected. Sixty-nine patients (33 males/36 females; 7.6 ± 1.7 years old) who underwent SME and 21 patients (10 males/11 females; 7.4 ± 1.2 years old) who were treated with rapid maxillary expander (RME). Digital models obtained pre- and post-treatment at appliance removal (9 to 11 months) were processed by means of a 3D scanner (Trios 3, 3Shape D250 laser, Copenhagen, Denmark). Interdental width in both maxilla and mandible were measured with 3 SHAPE Ortho Analyzer. Four Maxillary and four mandibular interdental width were traced and evaluated. The adequate Student’s t-test (dependent or independent) was used to compare intra and intergroups interdental width differences (p < 0.05). The efficacy of the SME was confirmed both on maxillary and mandibular arch. All the maxillary and mandibular interdental widths increased significantly (p < 0.001). The comparison with the RME group showed significant statistical differences between the two treatments with a greater increase in primary first and second intermolar and canine width for the test group (p < 0.001). SME with Leaf Expander produced statistically significant effects for the correction of transverse maxillary deficiencies with a significant indirect effect on the mandibular arch.

Three-dimensional assessment of mandibular asymmetry in skeletal Class I and unilateral crossbite malocclusion in 3 different age groups

INTRODUCTION

This study aimed to evaluate the morphologic and positional features of the mandible in children, adolescents, and adults with skeletal Class I and unilateral posterior crossbite.

METHODS

The sample included cone-beam computerized tomography images of 76 subjects, divided in 3 groups: (1) children (aged 6.77 ± 1.5 years; n = 25), (2) adolescents (aged 14.3 ± 1.7 years; n = 26), and (3) adults (aged 32.66 ± 13.4 years; n = 25) with unilateral posterior crossbite. Condylar and mandibular linear distances and angles were performed using a mirrored 3-dimensional overlapped model. Intragroup asymmetries were determined by a comparison between crossbite and no crossbite sides. The differences between both sides of all measurements were compared among groups and correlated to mandibular horizontal rotation (yaw) and age.

RESULTS

The crossbite side showed shorter distances in the condyle and mandibular regions. Asymmetries were slightly but significantly greater in adults, as expressed by the lateromedial condylar distance, total ramus height, and mandibular length with an average 0.7 mm, 2.0 mm, and 1.5 mm, respectively. The mandibular yaw rotation was not correlated to age but moderately associated (r = 0.467) to asymmetry in mandibular length and total ramus height.

CONCLUSIONS

Patients with skeletal Class I and unilateral crossbite showed small mandibular asymmetries and these conditions were slightly greater in adults, specifically in lateromedial condylar distances and mandibular body and length.

Three-dimensional assessment of craniofacial asymmetry in children with transverse maxillary deficiency after rapid maxillary expansion: A prospective study

OBJECTIVE

The aim of this study was to evaluate craniofacial asymmetry in children with transverse maxillary deficiency, with or without functional unilateral posterior crossbite (UPC), before and after rapid maxillary expansion (RME).

SETTING AND SAMPLE POPULATION

A sample of 51 children with cone beam computed tomography scans obtained before RME (T1) and a year after RME (T2).

MATERIAL AND METHODS

This prospective study consisted of 2 groups: 25 children with functional UPC (6.77 ± 1.5 years) and 26 children without UPC (7.41 ± 1.31 years). Linear and angular measurements were obtained from zygomatic, maxilla, glenoid fossa and mandible, using original and mirrored 3D overlapped models. All right and left side comparisons in both groups and intergroups asymmetries were compared using MANOVA and t test for independent samples, respectively, statistically significant at P < .05.

RESULTS

The UPC group showed no side differences, but mandibular horizontal rotation at T1, and this asymmetry was improved in T2. The non-UPC group showed at baseline significant lateral asymmetry in orbitale, position of palatine foramen, respectively, in average 2.95 mm and 1.16 mm, and 0.49 mm of average asymmetry in condylar height. The glenoid fossa was symmetric in both groups at T1 and T2.

CONCLUSIONS

Children with transverse maxillary deficiency showed slight morphological asymmetry, located in the mandible position in cases of UPC, and in the orbital and maxillary regions in cases without UPC. One year after RME, patients improved their craniofacial asymmetry, with significant changes in the mandible and correction of the mandibular rotation in patients who presented UPC.

Three-dimensional evaluation of forced unilateral posterior crossbite correction in the mixed dentition: a randomized controlled trial

Objectives

The objectives of this study were to assess the three-dimensional (3D) treatment changes (palatal surface area and volume) of forced unilateral posterior crossbite correction using either quad-helix or removable expansion plate appliances in the mixed dentition, and to compare the treatment changes with the three-dimensional changes occurring in age-matched untreated unilateral posterior crossbite patients as well as in subjects with normal occlusion and with no or mild orthodontic treatment need.

Trial design

Six-arm parallel group multicentre randomized controlled trial.

Materials and methods

One-hundred and thirty-five patients with unilateral posterior crossbite with functional shift were recruited. The patients were randomized by an independent person not involved in the trial. The randomization used blocks of 25, and the patients were randomized into the following five groups: quad-helix treatments in specialist orthodontic clinics (QHS), quad-helix treatments in general dentistry (QHG), removable expansion plate treatments in specialist orthodontic clinics (EPS), removable expansion plate treatments in general dentistry (EPG), and untreated crossbite (UC). Twenty-five patients with normal occlusion who served as normal controls were also included in the trial. Blinding of the outcome assessor and data analyst was accomplished. Data on all children were evaluated on an intention-to-treat basis, regarding 3D palatal surface area, palatal projection area, and palatal shell volume; two-dimensional linear measurements were registered at the same time.

Results

After treatment, the surface and projection area and shell volume increased in the four treatment groups (QHS, QHG, EPS, and EPG). QHS increased significantly more than EPG for the surface and projection area. The QHS and EPS had significantly higher mean difference for shell volume.

Limitations

The trial considers a short-term evaluation.

Conclusion

After treatment, there were no significant differences between the four treatment groups and the normal group, which implies that the surface and projection area together with the shell volume for the four treatment groups and the normal group were equivalent.

Trial registration

The trial was registered with https://www.researchweb.org/is/sverige, registration number: 220751.

Orthodontic treatment needs of children with high caries using Index for Preventive and Interceptive Orthodontic Needs (IPION)

AIM

This study aimed to use the Index for Preventive and Interceptive Orthodontic Treatment Needs (IPION) in high caries children and to investigate the IPION components that differentiate level of preventive and interceptive orthodontic treatment need (P&I Tx need).

METHODS

A sample of 202 children (8-9 years of age) was randomly selected from the schools in urban and rural areas in Songkhla Province, Southern Thailand. Dental models, intra-oral photographs, and the examination of oral function were collected and the P&I Tx need was determined according to IPION. Chi-square or Fisher's exact test were performed to test the difference in proportions of each component of IPION among levels of P&I Tx need.

RESULTS

Almost all children (96.0%) needed preventive and interceptive orthodontic treatment. The characteristics that were significantly different among P&I Tx need groups were primary molar proximal caries, anterior crossbite, lower permanent molar tipping, and abnormal molar relationship (p < 0.05). The major part of the IPION scores in the definite treatment need group came from caries, early loss, and crossbite.

CONCLUSIONS

The P&I Tx need in this group of children was very high. Primary molar proximal caries, anterior crossbite, lower permanent molar tipping, and abnormal molar relationship were the dominant factors that indicated P&I Tx need in these children.

Three-dimensional analysis of mandibular functional units in adult patients with unilateral posterior crossbite: A cone beam study with the use of mirroring and surface-to-surface matching techniques

OBJECTIVES

To use three-dimensional (3D) mirroring and surface-to-surface techniques to determine any differences in mandibular functional unit shape and morphology between the crossbite side and non-crossbite side in adult patients with posterior unilateral crossbite who had not received any corrective treatment for malocclusion.

MATERIALS AND METHODS

Cone-beam computed tomography (CBCT) records from 24 consecutive adult white patients (mean age, 27.5 years; range 22.6-39.7 years; 14 women and 10 men) seeking treatment for maxillary transverse deficiency were assessed in this study. The control group comprised CBCT scans from age- and sex-matched patients. Segmentation masks were generated to obtain 3D surface mesh models of the mandibles and analyze the six skeletal functional units, which were further analyzed with reverse engineering software.

RESULTS

Statistically significant differences in the mean surface distance when comparing the study sample and the control sample were found at the condylar process, mandibular ramus, angular process (P ≤ .0001), and alveolar process (P ≤ .01); no statistically significant differences were found for the coronoid process, the chin, and the mandibular body (P ≥ .5).

CONCLUSIONS

The condylar, angular, and alveolar processes plus the mandibular ramus appear to play a more dominant role than did the body, the coronoid, and the chin units in the asymmetry of the mandible in patients with unilateral crossbite.

Early anterior crossbite correction through posterior bite opening: a 3D superimposition prospective cohort study

Objectives

To assess the effectiveness, clinical performance, and potential adverse effects of early anterior crossbite correction through opening of the bite.

Subjects and methods

The sample consisted of 16 consecutive patients (8.0 ± 0.9, range: 6.2-9.3 years) with dental anterior crossbite in the mixed dentition who were treated through posterior bite opening. Patients were prospectively followed until a minimum of 6 months post-treatment and there were no drop-outs.

Results

In 14 patients (87.5 per cent), the anterior crossbite was corrected. Results remained stable without any retention regime. Active treatment of the successfully treated cases lasted 2.5 months (range: 0.6-8.9). Crossbite correction of central incisors was achieved by a 2.05 mm (range: 0.97-5.45) forward movement and 9.25° (range: 2.32-14.52°) buccal inclination of the crowns (P < 0.05). The antagonists showed spontaneous adaptation of their position in the opposite direction (P < 0.05). No important adverse effects were recorded.

Limitations

This was a non-comparative controlled study, on a limited sample.

Conclusions

Bite opening is a promising, simple, and non-compliance approach for early dental anterior crossbite correction. The technique of 3D superimposition and analysis of digital models used here, allowed precise evaluation of single tooth movement in all three planes of space.