New application of dynamic magnetic resonance imaging for the assessment of deglutitive tongue movement.

Background: Deglutitive motion of the tongue may function to maintain tooth position. However, the causation between abnormal patterns of orofacial muscle function and dental malocclusion remains unclear. To clarify the pathogenic mechanism of malocclusion, it is important to determine the relative positional relationship between the tongue tip and incisor edge or the dorsal tongue and palate during deglutition.

Influence of orthodontic appliance-derived artifacts on 3-T MRI movies.

Background: Magnetic resonance imaging (MRI) has been used to study configurations of speech organs in the resting state. However, MRI is sensitive to metals, and numerous types of metallic appliances, most of which have a large magnetic susceptibility, are used in orthodontic treatment and may cause severe artifacts on MRI. We have developed techniques for obtaining MRI movies of the oral region, to evaluate articulatory changes, especially movement of the tongue, palate, and teeth, pre- and post-orthodontic/orthognathic treatment.

Differences in Velopharyngeal Structure during Speech among Asians Revealed by 3-Tesla Magnetic Resonance Imaging Movie Mode.

Objective: Different bony structures can affect the function of the velopharyngeal muscles. Asian populations differ morphologically, including the morphologies of their bony structures. The purpose of this study was to compare the velopharyngeal structures during speech in two Asian populations: Japanese and Thai.

Use of an advanced 3-T MRI movie to investigate articulation.

Objective: To develop a magnetic resonance imaging (MRI) movie to reveal the dynamic movement of articulators and teeth.

Study Design: Five healthy females with normal occlusion participated in this study. Various concentrations of MRI contrast media (ferric ammonium citrate [FAC]) were tested for visualization of teeth, according to facial markers and with the use of a gel.

Effects of cortical activations on enhancement of handgrip force during teeth clenching: an fMRI study.

We assessed the effect of teeth clenching on handgrip force behaviorally, and investigated cortical activity during the occurrence of facilitatory effects using functional magnetic resonance imaging (fMRI). Twenty-three participants were assessed as to whether they had habitual teeth clenching during maximal voluntary contraction (MVC) exertion, and 21 of them were identified to have such a habit. For those participants, behavioral testing showed that MVC with clenching was greater compared with without clenching (approximately 108% greater on average).

Differential articulatory movements during Japanese /s/ and /t/ as revealed by MR image sequences with tooth visualization.

Objective: To evaluate the spatio-temporal relationships between articulators in the anterior oral cavity, during the production of Japanese fricative and plosive articulation using our proposed method for tooth visualization in MR image sequences.

Design: Ten healthy adults without malocclusion participated in the study. Customized maxillary and mandibular plates with space around the central incisors that was to be filled with MR-compatible contrast medium were made.

Preferred chewing side-dependent two-point discrimination and cortical activation pattern of tactile tongue sensation.

Although tactile feedback from the tongue should contribute to habitual chewing, it is unclear how the sensation of the tongue and its projection to the central nervous system differ with regard to the preferred chewing side (PCS). The purpose of this study was to investigate (1) whether the sensory threshold of the tongue differed according to the side and (2) whether the pattern of hemispheric cortical activation by tactile tongue stimulation differed, with special attention to the PCS. Twelve healthy adults participated in the study.

Motor coordination of articulators depends on the place of articulation.

Although the sounds/p/and/k/are both voiceless plosives, they have different places of articulation: bilabial and velar, respectively. The purpose of this study was to determine the relationship among articulators in plosives with reference to their place of articulation. Ten healthy subjects repeated bilabial and velar plosives in synchronization with magnetic resonance scanning.

Combined fMRI and MRI movie in the evaluation of articulation in subjects with and without cleft lip and palate.

Objective: This study was undertaken to explore the application of functional magnetic resonance imaging (fMRI) and MRI movies in the evaluation of articulatory function in subjects with and without cleft lip and palate (CLP).

Design: The authors examined brain activation and the dynamic movement of articulators during bilabial and velar plosives using fMRI and MRI movies.

Subjects: Two subjects, one with unilateral cleft lip and palate (UCLP) and one with bilateral cleft lip and palate (BCLP), and 12 non-CLP volunteers.

Changes in horizontal jaw position and intraoral pressure.

Objective: To determine the effect of an imbalance in buccolingual pressure that may be involved in molar dental compensation in the mandible and asymmetry of the dental arch in subjects with facial asymmetry.

Materials And Methods: We performed simultaneous measurement of the buccolingual pressure on the mandibular right first molar when subjects without facial asymmetry experimentally shifted the mandible laterally. Buccolingual pressures in the rest position (RP), right-shifted position (RS), and left-shifted position (LS) were compared.

Characteristics of movement of the lips, tongue and velum during a bilabial plosive: a noninvasive study using a magnetic resonance imaging movie.

Objective: To obtain dynamic images of articulators using a magnetic resonance imaging (MRI) movie and to clarify the relationships among the articulators.

Materials And Methods: The subjects consisted of 10 volunteers. Custom-made circuitry was connected to an MRI apparatus to enable an external trigger pulse to control the timing of the scanning sequence and to provide an auditory cue for synchronization of the subject's utterance.

Mandibular distraction osteogenesis in a skeletal Class II patient with obstructive sleep apnea.

We report the orthodontic treatment of a 31-year-old man with severe skeletal Class II malocclusion and documented obstructive sleep apnea (OSA). He had a retrognathic profile with an overbite of 4 mm and an overjet of 14 mm. Mandibular distraction osteogenesis was performed to lengthen the small, retruded mandible by 18 mm and improve the symptoms of OSA.

Distinctive cortical articulatory representation in cleft lip and palate: a preliminary functional magnetic resonance imaging study.

Objective: To investigate cortical representation of articulation of the bilabial plosive in patients with cleft lip and palate.

Design: We examined cortical representation for /pa/-articulation in cleft lip and palate patients using blood oxygenation level-dependent functional magnetic resonance imaging.

Subjects: Data from four postsurgical adult cleft lip and palate patients were compared with those from six healthy volunteers.

[Changes in shape of upper airway during titrated mandibular advancement: a magnetic resonance imaging study].

Objective: To examine adaptive changes in the shape of the upper airway during titrated mandibular advancement. Furthermore, to understand the mechanism of mandible-adjustable therapy to improve the ventilation.

Methods: Fourteen non-apnea participated in the study.

Radiopacity of experimental composite resins containing radiopaque materials.

This study aimed to investigate the relationship between the radiopacity of an experimental light-cured composite resin and the amount and type of its radiopaque material: Ti, SrCO3, ZrO2, BaSO4, or Bi2O3. Radiopacity of each material was evaluated in terms of aluminum equivalent thickness using an aluminum step wedge. Then, the half-value layer thickness of the experimental composite resin, which had an aluminium equivalent thickness of 1 mm, was evaluated.

Effects of mandibular advancement on brain activation during inspiratory loading in healthy subjects: a functional magnetic resonance imaging study.

Oral appliances have been a popular treatment option for subjects with obstructive sleep apnea. However, little information is available on how brain activation induced by respiratory challenge is modulated by mandibular advancement with these appliances. We hypothesized that the brain activation caused by respiratory stress may be alleviated by mandibular advancement.

Dynamic analysis of articulatory movement using magnetic resonance imaging movies: methods and implications in cleft lip and palate.

Objectives: To visualize articulatory movement using a magnetic resonance imaging (MRI) movie of a subject with cleft lip and palate (clp) and to demonstrate the usefulness of this method for studying oropharyngeal function.

Material And Methods: Dynamic changes in oropharyngeal structures were assessed with an MRI movie of a man with cleft lip and palate and in a normal adult male volunteer during the articulation of /pa/, /ta/, and /ka/.

Results And Conclusions: Different movement patterns were observed during articulation in the subject with CLP compared with the normal volunteer.

Comparison of fMRI data analysis by SPM99 on different operating systems.

The hardware chosen for fMRI data analysis may depend on the platform already present in the laboratory or the supporting software. In this study, we ran SPM99 software on multiple platforms to examine whether we could analyze fMRI data by SPM99, and to compare their differences and limitations in processing fMRI data, which can be attributed to hardware capabilities. Six normal right-handed volunteers participated in a study of hand-grasping to obtain fMRI data.

Effect of titrated mandibular advancement and jaw opening on the upper airway in nonapneic men: a magnetic resonance imaging and cephalometric study.

The aim of this study was to examine adaptive changes in the cross-sectional area of the upper airway during mandibular advancement and jaw opening and to explore whether these changes are directly related to morphologic features of the mandible. Fourteen nonapneic men participated in this study. A custom-made oral device was used to keep the mandible at 0% (F(0)V(0)), 50% (F(50)V(0)), 75% (F(75)V(0)), or 100% (F(100)V(0)) of maximum advancement, and at 50% (F(75)V(50)), 75% (F(75)V(75)), or 100% (F(75)V(100)) of maximum gape at F(75)V(0).