Pressure from the lips and the tongue in children with class III malocclusion

Correlation between oral muscle pressure and malocclusion in mixed dentition: a cross-sectional study

OBJECTIVE

To investigate the relationship between oral muscle pressure and malocclusion in the mixed dentition.

MATERIALS AND METHODS

Maximum tongue, lip and cheek pressure was measured using the Iowa Oral Performance Instrument (IOPI) in 3 patient cohorts: patients with (1) posterior crossbite, (2) class II relationship and (3) a control group of patients without malocclusion. Linear models were used to compare the mean differences in muscle pressure between groups, with correction for age and gender. The imbalance between lips and tongue and between lips and cheeks was calculated by the Delta z-scores of each group.

RESULTS

A total of 146 participants were included, 46 (mean age 8.71±0.85), 41 (mean age 11.74±1.17) and 35 (mean age 10.71±1.92) in groups 1, 2 and 3 respectively. Patients with malocclusion showed significantly higher lip and lower cheek pressure and imbalance favouring the lips over the tongue compared to controls. Class II,1 patients showed significantly higher tongue pressure than Class II,2. No differences were found in muscle pressure or imbalance between crossbite and Class II nor between crossbite types.

CONCLUSION AND CLINICAL RELEVANCE

These findings suggest that oral muscle pressure may be associated with malocclusion. This highlights the importance of functional diagnosis and its implications on the prevention and treatment of malocclusion, as well as on orthodontic stability.

Relation between Maximum Oral Muscle Pressure and Dentoalveolar Characteristics in Patients with Cleft Lip and/or Palate: A Prospective Comparative Study

BACKGROUND

Perioral muscle function, which influences maxillofacial growth and tooth position, can be affected in patients with oral clefts due to their inherent anatomical characteristics and the multiple surgical corrections performed. This research aims to (1) compare the maximum oral muscle pressure of subjects with and without isolated cleft palate (CP) or unilateral cleft lip and palate (UCLP), (2) investigate its influence on their dentoalveolar characteristics, and (3) investigate the influence of functional habits on the maximum oral muscle pressure in patients with and without cleft.

MATERIAL AND METHODS

Subjects with and without CP and UCLP seeking treatment at the Department of Orthodontics of University Hospitals Leuven between January 2021 and August 2022 were invited to participate. The Iowa Oral Performance Instrument (IOPI) was used to measure their maximum tongue, lip, and cheek pressure. An imbalance score was calculated to express the relationship between tongue and lip pressure. Upper and lower intercanine (ICD) and intermolar distance (IMD) were measured on 3D digital dental casts, and the presence of functional habits was reported by the patients. The data were analyzed with multivariable linear models, correcting for age and gender.

RESULTS

44 subjects with CP or UCLP (mean age: 12.00 years) and 104 non-affected patients (mean age: 11.13 years) were included. No significant differences in maximum oral muscle pressure or imbalance score were detected between controls and clefts or between cleft types. Significantly smaller upper ICDs and larger upper and lower IMDs were found in patients with clefts. A significant difference between controls and clefts was found in the relationship between oral muscle pressure and transversal jaw width. In cleft patients, the higher the maximum tongue pressure, the wider the upper and lower IMD, the higher the lip pressure, the smaller the upper and lower ICD and IMD, and the higher the imbalance score, the larger the upper and lower IMD and lower ICD. An imbalance favoring the tongue was found in cleft patients. The influence of functional habits on the maximum oral muscle pressure was not statistically different between clefts and controls.

CONCLUSION

Patients with CP or UCLP did not present reduced maximum oral muscle pressure compared with patients without a cleft. In cleft patients, tongue pressure was consistently greater than lip pressure, and those who presented a larger maxillary width presented systematically higher imbalance scores (favoring the tongue) than those with narrow maxillae. Therefore, the influence of slow maxillary expansion on maximum oral muscle pressure in cleft patients should not be underestimated.

Real-Time Continuous Monitoring of Oral Soft Tissue Pressure with a Wireless Mouthguard Device for Assessing Tongue Thrusting Habits

In orthodontics, understanding the pressure of oral soft tissues on teeth is important to elucidate the cause and establish treatment methods. We developed a small wireless mouthguard (MG)-type device that continuously and unrestrainedly measures pressure, which had previously been unachieved, and evaluated its feasibility in human subjects. First, the optimal device components were considered. Next, the devices were compared with wired-type systems. Subsequently, the devices were fabricated for human testing to measure tongue pressure during swallowing. The highest sensitivity (51-510 g/cm²) with minimum error (CV < 5%) was obtained using an MG device with polyethylene terephthalate glycol and ethylene vinyl acetate for the lower and upper layers, respectively, and with a 4 mm PMMA plate. A high correlation coefficient (0.969) was observed between the wired and wireless devices. In the measurements of tongue pressure on teeth during swallowing, 132.14 ± 21.37 g/cm² for normal and 201.17 ± 38.12 g/cm² for simulated tongue thrust were found to be significantly different using a t-test (n = 50, p = 6.2 × 10^-19), which is consistent with the results of a previous study. This device can contribute to assessing tongue thrusting habits. In the future, this device is expected to measure changes in the pressure exerted on teeth during daily life.

Tongue Pressure Declines Early on in Patients with Malocclusion

(1) Background: The tongue plays a key role in the stomatognathic system in carrying out oral functions. The aim of this study was to identify the association between tongue pressure and orthodontic parameters. (2) Methods: This study is a cross-sectional multicentered cohort study with IRB approval. During routine orthodontic initial examinations, the following data were recorded: age, sex, angle classification, overjet (OJ), overbite (OB), arch sizes, tongue width, and maximum tongue pressure (MTP). The association between MTP and orthodontic parameters was analyzed using Pearson’s correlation analysis and the Student’s t-test. (3) Results: There is a positive correlation between MTP and age between ages 10 and 20 (R = 0.47, p < 0.01). There is a negative correlation with MTP and age between 20 and 40 (R = −0.30, p < 0.05). There are negative correlations between MTP and OJ (R = −0.278, p < 0.01)) and OB (R = −0.374, p < 0.01). While there is no statistical significance between MTP and tongue width, there is a statistically significant difference between age and tongue width (R = 0.22482, p < 0.05). There is no statistical significance between MTP and sex, angle classification, arch length, intercanine width, and intermolar width. (4) Conclusion: An earlier decline in MTP is observed with patients with malocclusion. This implies that patients with malocclusion should seek early treatment for the malocclusion.

Differences in the factors associated with tongue pressure between children with class I and Class II malocclusions

Background

The relationship between tongue pressure and masticatory performance during the mixed dentition period in cases of Class II malocclusion has not been clarified. The aim of this study was to determine differences in tongue pressure-related factors, including maxillofacial morphology and masticatory performance, between Class I and Class II malocclusions during the mixed dentition period.

Methods

A total of 56 children with Class I malocclusion (12 boys, 16 girls) or Class II malocclusion (16 boys, 12 girls) with mixed dentition were included in the present study. Height, body weight, hand grip strength, maximum occlusal force, maximum tongue pressure, masticatory performance, and the number of decayed, missing, and filled teeth were measured in all participants. Their lateral cephalograms were also evaluated. The means of all measurements were compared between Class I and Class II malocclusions. Pearson’s correlation coefficients were used to determine associations between maximum tongue pressure and other variables for each type of malocclusion.

Results

The maximum tongue pressure, hand grip strength, and maximum occlusal force in the Class II malocclusion group were significantly lower than those in the Class I malocclusion group (all, p < 0.05). The maximum tongue pressure was significantly positively correlated with hand grip strength, maximum occlusal force, masticatory performance, and SNB (sella, nasion, B point) angle in the Class I group (all, p < 0.05), and with height, body weight, and labial inclination of the central incisors in the Class II group (all, p < 0.05).

Conclusions

The maxillofacial morphometric factors associated with tongue pressure were clearly different between cases of Class I and Class II malocclusion with mixed dentition. Masticatory performance and tongue pressure were significantly positively correlated in cases of Class I malocclusion, but not in cases of Class II malocclusion.

Comparative Analysis of the Differences in Dentofacial Morphology According to the Tongue and Lip Pressure

The aim of this study was to evaluate the effects of the tongue and lip pressure on dentofacial morphology. The subjects comprised 194 patients with malocclusion. Anterior and posterior tongue elevation and lip pressures were evaluated using the Iowa Oral Performance Instrument (IOPI) device. The lateral cephalograms of each subject were traced and digitized to perform the analysis. Statistical analysis was used to investigate the relationship between perioral muscle force and the cephalometric variables. Anterior and posterior tongue pressure was both higher in males than in females. No sex difference in lip pressure was observed. The group with a low posterior tongue pressure showed a short ramus height, short posterior facial height, and clockwise-rotated mandible. On the other hand, lip pressure had a significant influence on maxillary incisor angulation. Skeletal pattern was not found to be significantly related with lip pressure. The anterior tongue pressure appeared as a mixed pattern of the two results. Tongue pressure was related to skeletal measurements, such as short posterior facial height, and lip pressure was related to the angulation of the anterior teeth. This study suggests that there may be differences in dentofacial morphology according to the differences in perioral muscle force.

Low-Magnitude Forces for Bone Modeling and Remodeling in Dentofacial Orthopedics

PURPOSE OF REVIEW

To examine the evidence in support of light continuous forces for enhancing bone adaptation (modeling and remodeling) in orthodontics and dentofacial orthopedics.

RECENT FINDINGS

Clinical evidence suggests that light continuous orthodontic force can achieve physiologic expansion of the maxillary arch, but the long-term stability and the biological effects of the procedure are unclear. Compared to conventional orthodontic appliances that deliver heavy interrupted forces for tooth movement, the application of low-magnitude forces in animal models leads to anabolic modeling and remodeling of the alveolar bone in the path of orthodontic tooth movement. This results in dental translation and expansion of the alveolar process. Light continuous forces are preferable to heavy forces for more physiologic dentofacial orthopedics. The interaction of low-magnitude loads with soft tissue posture achieves therapeutic adaptation of the craniofacial skeleton. The increasing emphasis on genomic medicine and personalized treatment planning should focus on low-magnitude loads in orthodontics and dentofacial orthopedics.

Relationship between perception of tongue position and measures of tongue force on the teeth

Purpose

To verify whether there are differences of tongue force on the teeth at rest and during swallowing between individuals who report appropriate tongue position and those who report tongue thrust.

Methods

Tongue forces on the teeth were evaluated in 28 participants aged 19 to 31 years. To this end, a Flexiforce® resistive sensor was fixed to the palatal surface of the maxillary right central incisor (tooth 8) and was connected to an amplifier circuit, a data acquisition board, and a computer. Measurements were taken at rest and during saliva swallowing. Participants were asked about their habitual tongue position and where the apex of tongue touched when they swallowed. The Mann Whitney test was used for statistical analysis at 5% significance level.

Results

At habitual position, tongue force on the teeth was 0.00 N both for participants that reported tongue touch and for those who did not. At directed swallowing, tongue force was 0.34 N for the group of individuals whose tongues touch the teeth and 0.08 N for the group of individuals whose tongues do not touch the teeth. This difference was significant.

Conclusion

No significant difference was found between the tongue forces of participants of both groups at habitual position. However, participants with tongue thrust during directed swallowing presented greater force than those whose tongues do not touch the teeth during this task.

Evaluation of the force applied by the tongue and lip on the maxillary central incisor tooth

PURPOSE

To describe the development and testing of a system that measures forces exerted by the tongue and upper lip on a tooth during rest and during swallowing.

METHODS

Twenty-eight subjects, aged 19-31 years (mean: 23.2 years) were submitted to measurement of forces exerted by the upper lip and tongue on the maxillary right central incisor tooth. Flexiforce resistive sensors were fixed on the labial and lingual surfaces of the tooth. They were connected to an amplifier circuit and a data acquisition board for processing and transmitting information to a computer.

RESULTS

At rest, the tongue force on the tooth was 0.00±0.00 N and the lip force on tooth was 0.02±0.02 N. The difference between them was significant. During swallowing, the values were 0.31±0.38 N and 0.15±0.14 N, for the tongue and lip, respectively. This difference was not significant.

CONCLUSION

At rest, the lip exerts a larger force than the tongue on the maxillary right central incisor tooth. During swallowing, there was no difference between lip and tongue force on the tooth.

Lip closing force of Class III patients with mandibular prognathism: a case control study

INTRODUCTION

To compare the lip closing force of patients with mandibular prognathism to that of patients without dentofacial anomalies.

METHODS

The subject group included 62 female patients of Class III relationship with mandibular prognathism. The control group been comprised of 71 patients of Class I relationships without skeletal deformities. Maximum lip closing force and average lip closing force were measured using a Y-meter. Student's t-test was carried out to analyse the differences between the groups. Correlation and stepwise multiple linear regression analyses were performed to analyse the relationship between lip closing force and craniofacial morphology.

RESULTS

The lower lip closing force of subjects with mandibular prognathism was significantly greater than that of patients in the control group (P < 0.001), while the upper lip closing force showed no difference (P > 0.05). The lower lip closing force of patients with mandibular prognathism was strongly correlated with IMPA (Lower Incisor - Mandibular Plane angle, P < 0.001) and FMA (Frankfort Plane-Mandibular Plane angle, P < 0.001). Multiple regression equations: (MaxLL) = 12.192 - 0.125 * (IMPA) + 0.082 (FMA); (AveLL) = 9.112 - 0.091 * (IMPA) + 0.054 (FMA).

CONCLUSIONS

The lower lip closing force was markedly increased in Class III patients with mandibular prognathism and was strongly correlated with lower incisor position and mandibular plane angle.

Evaluation of recovery in lip closing pressure and occlusal force and contact area after orthognathic surgery

PURPOSE

The purpose of this study was to evaluate the relationship between lip closing force, occlusal contact area and occlusal force after orthognathic surgery in skeletal Class III patients.

SUBJECTS AND METHODS

The subjects consisted of 54 patients (28 female and 26 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces, occlusal contact area and occlusal force were measured pre-operatively, 6 months and 1 year post-operative.

RESULTS

Maximum and minimum lip closing forces, occlusal contact area and occlusal force increased with time after surgery, however a significant increase was not found in the occlusal contact area in women. In increased ratio (6 months/pre-operative and 1 year/pre-operative), the maximum lip closing force was significantly correlated with the occlusal contact area (P < 0.0001).

CONCLUSIONS

This study suggested that orthognathic surgery could improve the occlusal force, contact area and lip closing force, and an increase ratio in maximum lip closing force was associated with an increased ratio in occlusal contact area.

Factors related to the formation of buccal mucosa ridging in university students

OBJECTIVE

Buccal mucosa ridging (BMR) is known as a clinical sign of clenching, which is one of the major manifestations of bruxism. However, there are few reports about the formation of BMR and no data regarding the association between BMR and factors such as malocclusion. The purpose of the current study was to investigate the relationship between BMR and factors such as the number of teeth present, gender, body mass index (BMI), occlusion and clenching habit in university students.

MATERIALS AND METHODS

A total of 2101 students (1164 males, 937 females), aged 18-29 years old, were included in the study. BMR and the number of teeth present were recorded and malocclusion was defined using a modified version of the Index of Orthodontic Treatment Need. Additional information regarding gender, clenching habit and BMI was collected via a questionnaire.

RESULTS

Forty-six per cent of the subjects had BMR and the prevalence of BMR in females was significantly higher than that of males (chi square test, p < 0.001). According to logistic regression analysis, the probability of BMR was significantly associated with female gender (OR = 1.501, 95% CI = 1.259-1.790, p < 0.001), crowding (OR = 2.102, 95% CI = 1.706-2.590, p < 0.001) and overjet (OR = 0.585, 95% CI = 0.418-0.818, p = 0.002). On the other hand, BMR was not associated with awareness of clenching habit and BMI.

CONCLUSIONS

Gender, crowding and overjet were related to the formation of BMR in university students. When evaluating BMR as a clinical sign of clenching, one might have to take factors such as gender and crowding into consideration.

Recent advances in sensing oropharyngeal swallowing function in Japan

Dysphagia (difficulty in swallowing) is an important issue in the elderly because it causes aspiration pneumonia, which is the second largest cause of death in this group. It also causes decline in activities of daily living and quality of life. The oral phase of swallowing has been neglected, despite its importance in the evaluation of dysphagia, because adequate protocols and measuring devices are unavailable. However, recent advances in sensor technology have enabled straightforward, non-invasive measurement of the movement of important swallowing-related organs such as the lips and tongue, as well as the larynx. In this article, we report the present state and possibility of clinical application of such systems developed in Japan.