Keiseki Kaneyama

Congenital deformities and developmental abnormalities of the mandibular condyle in the temporomandibular joint

ABSTRACT  The temporomandibular joint (TMJ) consists of the mandibular condyle and the articular eminence of the temporal bone. The morphological development of the TMJ during prenatal life lags behind other joints in terms of both the timing of its appearance and its progress. At birth, the joint is still largely underdeveloped. There are many causes of the various growth disturbances and abnormalities of the mandibular condyle and related structures. Growth disturbances in the development of the mandibular condyle may occur in utero late in the first trimester and may result in disorders such as aplasia or hypoplasia of the mandibular condyle. Meanwhile, hyperplasia of the mandibular condyle is not visible at birth and seems to be gradually acquired during growth. In the present review article, the congenital abnormalities of the mandibular condyle are classified morphologically into three major groups and two subgroups from a clinical standpoint: (1) hypoplasia or aplasia of the mandibular condyle, including (i) primary condylar aplasia and hypoplasia, (ii) secondary condylar hypoplasia; (2) hyperplasia; and (3) bifidity. In addition, the molecular‐based etiology of anomalies of the mandibular condyle is also discussed.

Interleukin-6 family of cytokines as biochemical markers of osseous changes in the temporomandibular joint disorders

The aim of this study was to find out whether there was a correlationship between the concentrations of interleukin-6 (IL-6), IL-11, and IL-17 in synovial fluid and osseous changes in the condyle. The synovial fluid was obtained from 61 patients with temporomandibular joint disorders (TMD) and seven healthy volunteers (controls). The concentrations of IL-6, IL-11, and IL-17 were measured by enzyme-linked immunosorbent assay. IL-6 was detected in 43 of 59 (73%), IL-11 in 23 of 52 (44%) and IL-17 in 14 of 51 (27%) samples of synovial fluid. The concentrations of IL-6 and IL-11 in the joints with osseous changes in the condyle were significantly higher than in the joints without osseous changes (P < 0.05) and also higher than in the joints of the control group (P < 0.05). In addition, there was a correlation of concentrations between IL-6 and IL-11 (P < 0.05). These results suggest that IL-6 and IL-11 may participate in the pathogenesis of TMD and induce osseous changes in the condyle.

Increased Levels of Soluble Cytokine Receptors in the Synovial Fluid of Temporomandibular Joint Disorders in Relation to Joint Effusion on Magnetic Resonance Images

PURPOSE The purpose of this study is to clarify the significance of joint effusion (JE) on T2-weighted magnetic resonance images of the temporomandibular joint (TMJ) in comparison to various soluble cytokine receptors in the synovial fluid of patients with temporomandibular disorders (TMDs). PATIENTS AND METHODS Magnetic resonance imaging of 55 TMJs of 55 patients with TMD was performed, and synovial fluid samples were obtained on the same day. The grade of JE was evaluated on a scale from 0 to 3, with grade 0 indicating the absence of JE and grades 1 to 3 indicating the presence of JE. Correlations were measured between JE and the concentrations of soluble tumor necrosis factor receptors I and II, interleukin (IL) 6 soluble receptor, IL-1 soluble receptor type II, and IL-1 receptor antagonist and protein in the synovial fluid samples. RESULTS The mean concentrations of cytokine receptors in the synovial fluid were significantly higher in the 30 joints with JE than in the 25 joints without JE. There were no correlations between the JE grade and the level of any mediators. CONCLUSION Increased levels of cytokine receptors are likely to influence the expression of JE and may play important roles in the pathogenesis of TMD. These results also suggest that JE may reflect synovial inflammation of the TMJ.

Specific expression of interleukin-1β in temporomandibular joints with internal derangement: Correlation with clinical findings

OBJECTIVE Interleukin-1 beta appears to play an important role in the pathophysiology of joint diseases. The aim of this study was to analyze the expression of interleukin-1 beta in temporomandibular joint internal derangement. STUDY DESIGN Using an immunohistochemical technique with specific antibodies, we examined 20 human temporomandibular joint samples from patients with internal derangement of the temporomandibular joint: 5 extirpated disks and 15 biopsy specimens from the synovitic area of the temporomandibular joint upper compartment. We also examined 2 control specimens. The evaluation of interleukin-1 beta expression compared with clinical findings. RESULTS Interleukin-1 beta was predominantly localized in the synovial lining cells and endothelial cells of blood vessels. Statistically significant correlation was found between interleukin-1 beta expression and some clinical findings. CONCLUSIONS The results suggest that interleukin-1 beta may be involved in the pathogenesis of temporomandibular joint internal derangement and that the intensity of interleukin-1 beta expression may correlate with clinical findings, especially pain.

Bacterial diversity in synovial fluids of patients with TMD determined by cloning and sequencing analysis of the 16S ribosomal RNA gene

OBJECTIVE The purpose of this study was to examine the presence of bacteria in synovial fluids from patients with temporomandibular joint disorder (TMD) by polymerase chain reaction (PCR) targeting the 16S ribosomal RNA (rRNA) gene, followed by cloning and sequencing. STUDY DESIGN Universal bacterial primers were used to amplify 16S rRNA genes in 28 synovial fluid samples from 27 patients with TMD (TMD group) as well as control subjects: 5 patients with dislocation of TMJ (non-TMD group). Subsequently, PCR amplicons were purified and cloned. Partial 16S rRNA sequences of the cloned insert were used to determine the species identities or closest relative by comparison with known sequences using GeneBank. RESULTS Nineteen (67.86%) of 28 samples from patients in the TMD group were identified with the presence of bacterial DNA by PCR. The 5 control samples from the nonTMD group were all negative in this study. After cloning and sequencing, a total of 11 bacterial species was detected, including Granulicatella adiacen (6 samples), Pseudomonas sp. (6 samples), Methylobacterium sp. (5 samples), and Beta proteobacterium (4 samples). Other species, such as Acidovorax sp., Bradyrhizobium sp., Sphingomonas, Streptococcus, Leptothrix sp. oral clone, Thiobacillus denitrificans, and Comamonadaceae bacterium, were also identified. Eight patients were found with mixed bacteria, with 2-4 bacteria per sample. The patients with fastidious bacteria such as Granulicatella adiacen and mixed bacteria were more likely to be older than 45 years (P < .05). CONCLUSION A wide variety of bacteria, including some not previously reported associated with TMD, were identified in the synovial fluids from patients with TMD.

Relation between the expression of vascular endothelial growth factor in synovial tissues and the extent of joint effusion seen on magnetic resonance imaging in patients with internal derangement of the temporomandibular joint.

The aim of this study is to elucidate the relation between the expression of vascular endothelial growth factor (VEGF) in synovial tissues and the extent of joint effusion seen on magnetic resonance imaging (MRI) in patients with internal derangement of the temporomandibular joint (TMJ). Using an immunohistochemical technique, we examined specimens of synovial tissues from 41 joints in 40 patients with internal derangement. Specimens from 36 of the 41 joints stained for VEGF. There was a significant correlation between the percentage of the VEGF-stained cells and the grade of joint effusion seen on MRI (P=0.0002, r=0.62). The correlation between the two was also significant on multiple logistic regression analysis (P=0.003, odds ratio=1.75). These results suggest that VEGF may have an important role in the genesis of joint effusion.

Influences of audio-visual environments on feelings of deliciousness during having sweet foods: An electroencephalogram frequency analysis study

Abstract Feelings of deliciousness during having foods are mainly produced by perceptions of sensory information extracted from foods themselves, such as taste and olfaction. However, environmental factors might modify the feeling of deliciousness. In the present study, we investigated how the condition of audio-visual environments affects the feeling of deliciousness during having sweet foods. Electroencephalograms (EEGs) were recorded from the frontal region of the scalp of healthy participants under virtual scenes of tearoom and construction work, respectively. The participants were asked to rate deliciousness after the recordings. Frequency analyses were performed from the EEGs. During having the foods, occupancy rates of beta frequency band between tearoom scenes and construction work scenes were markedly different, but not in other frequency bands. During having no food, in contrast, there was no difference of occupancy rates in respective frequency bands between the two different scenes. With regard to deliciousness during having sweet foods, all participants rated high scores under the scenes of tearoom than those under the scenes of construction work. Interestingly, there is a positive correlation between occupancy rates of beta frequency band and scores of deliciousness. These findings suggest that comfortable audio-visual environments play an important role in increasing the feeling of deliciousness during having sweet foods, in which beta frequency rhythms may be concerned with producing comprehensive feelings of deliciousness.

Opening of shortcut circuits between visual and retrosplenial granular cortices of rats.

Traveling neural signals may try to find suitable paths of propagation in cortical circuits. We examined the behavior of electrically evoked signals from primary visual cortex (Oc1) to granular retrosplenial cortex (RSG) in rat brain slices under caffeine application. With continued electrical stimulation, evoked signals propagated from Oc1 to RSG along the upper layer of the secondary visual cortex (Oc2) and agranular retrosplenial cortex (RSA), but on further continuation of stimulation, a new shortcut pathway along the deep layer between Oc2 and RSG was opened. Circuitry changes reduced the signal traveling time by about 40 ms. Cortical neural circuits between Oc1 and RSG may thus have the ability to open a shortcut circuit in a use-dependent manner.

Multiple tooth-losses during development suppress age-dependent emergence of oscillatory neural activities in the oral somatosensory cortex

Tooth and tooth-related organs play important roles in not only mastication, but also sensory perception in the oral region. In general, sensory neural inputs during the developmental period are required for the maturation of functions in the sensory cortex. However, whether maturations of oral somatosensory cortex (OSC) require certain levels of sensory input from oral regions has been unclear. The present study investigated the influence of multiple tooth-losses during the developmental period on age-dependent emergence of rhythmic activities of population neurons in the OSC. Low-frequency electrical stimulation was delivered to layer IV and field potentials were recorded from layer II/III in the OSC of rat brain slices. In control rats, N-methyl-d-aspartate (NMDA) receptor-dependent oscillation at 8-10 Hz appeared during postnatal weeks 2-3. In rats with extraction of multiple teeth at 17-18 days old, oscillation did not appear even at maturity, whereas in rats with multiple teeth extracted at 37-38 days old, oscillation appearances were maintained in maturity. Thus, emergence of oscillation in the OSC was suppressed by multiple tooth-losses during postnatal 2-3 weeks. These results suggest that sufficient neural inputs from the teeth and tooth-related organs during developmental periods are essential for maturation of neural functions in the OSC.

Expression of osteoprotegerin in synovial tissue and degradation of articular cartilage: Comparison with arthroscopic findings of temporomandibular joint disorders ☆

OBJECTIVE The aim of this study was to investigate the correlations among the expression of osteoprotegerin (OPG) in synovial tissue and the degree of synovitis, the degeneration of articular cartilage, and the adhesions in patients with internal derangement and osteoarthritis of the temporomandibular joint (TMJ). Study design The expression of OPG, which was detected immunohistochemically, and the degree of arthroscopy of 31 patients with internal derangement and osteoarthritis of the TMJ were assessed and the correlations between them were analyzed statistically. RESULTS OPG was expressed in the cytoplasm of the endothelial cells, synovial lining cells, and fibroblast cells. TMJs with osteoarthritis had a higher degree of articular cartilage degeneration than did TMJs with internal derangement. There was a correlation between the expression of OPG in the endothelial cells and the degree of the articular cartilage degeneration (P <.01). CONCLUSION The expression of OPG might be associated with the development of degenerative changes of articular cartilage.