Relationship between the unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity of the masticatory muscles: a retrospective study.

The purpose of this retrospective study was to investigate the relationship between the unilateral temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA), mandibular asymmetry and electromyographic (EMG) activity of the masticatory muscles. Twenty-two Japanese women (aged 23.2 +/- 5.4 years) and 10 Japanese men (aged 22.4 +/- 2.8 years) exhibiting unilateral TMJ OA were included in this study. Two angular and seven linear measurements were obtained for the analysis of the skeletal hard tissues. The cephalometric measurement values (CV) were normalized using the CV ratio for the evaluation of the degree of mandibular asymmetry. The EMG was recorded during maximal voluntary clenching efforts for 10 s in the intercuspal position. The average values of integral EMG (iEMG) of three trials were normalized using the iEMG ratio for the evaluation of the functional balance of the masticatory muscles. The mandibular midline was shifted to the TMJ OA side with a median value of 9.85 mm. The CV ratio of the ramus height of the TMJ OA side was significantly smaller than that of the non-OA side. For the masseter muscle, the iEMG ratio of the TMJ OA side was significantly larger than that of the non-OA side (P < 0.05). These results suggest that unilateral TMJ OA is related to the dentofacial morphology, thus resulting in a mandibular midline shift to the affected side and it is associated with a masticatory muscle imbalance.

Fabrication of macroporous carbonate apatite foam by hydrothermal conversion of alpha-tricalcium phosphate in carbonate solutions.

Bone consists of a mineral phase (carbonate apatite) and an organic phase (principally collagen). Cancellous bone is characterized by interconnecting porosity necessary for tissue ingrowth and nourishment of bone cells. The purpose of the present study was to fabricate macroporous carbonate apatite (CAP) blocks with interconnecting porosity as potential bone substitute biomaterials by hydrothermal conversion of alpha-TCP foam in carbonate solution. The fabrication of the macroporous CAP was accomplished in two steps: (1) preparation of alpha-TCP foams using polyurethane foams as templates, and (2) hydrothermal conversion at 200 degrees C of alpha-TCP foam in the presence of ammonium carbonate solutions of different concentrations. The maximum carbonate content of the resultant CAP foam was approximately 7.4 wt %. The mean porosity of the CAP foam was as high as 93 vol %. The macroporous CAP blocks or granules prepared in this manner has properties similar to that of bone in mineral composition and in having interconnecting macroporosity necessary for osteoconductivity and tissue ingrowth. On the basis of composition and interconnecting macroporosity, the CAP foam materials could be ideal biomaterials for bone repair and as scaffolds for tissue engineering.

Relationship of TMJ osteoarthritis / osteoarthrosis to head posture and dentofacial morphology.

OBJECTIVE: The purpose of this study was to test the hypothesis that there is a relationship between the temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA), head posture and dentofacial morphology. DESIGN: Case-control study. SUBJECTS AND METHODS: The subjects consisted of 34 Japanese females with TMJ OA (aged 24.7 +/- 6.1 years) and a control group of 25 healthy Japanese females (aged 23.6 +/- 1.3 years). Six cranio-cervical angular measurements were constructed for head posture analysis. Nine angular and three linear measurements were constructed for the skeletal hard tissue analysis. Five angular and one linear measurements were constructed for the dental hard tissue analysis. Unpaired t-tests were used to compare the mean differences of head posture measurements and dentofacial cephalometric measurements between the TMJ OA and the control group. RESULTS: The TMJ OA group had significantly larger cranio-cervical angles (p < 0.05) and had more posteriorly rotated mandibles (p < 0.0001) than those in the control group. They also had a significantly shorter posterior facial height (p < 0.0001). The TMJ OA group had more retroclined lower incisors (p < 0.05). CONCLUSION: These results suggest that an association may exist between TMJ OA, head posture and dentofacial morphology.

Influence of facial convexity on facial attractiveness in Japanese.

OBJECTIVE: The purpose of this study was to assess and determine the range of the top three most-favored facial profiles for each sex from a series of varying facial convexity, and to evaluate the clinically acceptable facial profiles for Japanese adults. DESIGN: Questionnaire-based study. SUBJECTS AND METHODS: Silhouettes of average male and female profiles were constructed from the profiles of 30 Japanese males and females with normal occlusions. Chin positions were protruded or retruded by 2 degrees , 4 degrees , 6 degrees , 8 degrees and 10 degrees , respectively, from the average profile. Forty-one orthodontists and 50 dental students were asked to select the three most-favored profiles for each sex, and they were also asked to indicate whether they would seek surgical orthodontic treatment if that image represented their own profile. RESULTS: For males, both the orthodontists and dental students chose the average profile as the most-favored profile. For females, both the orthodontists and dental students chose a slightly more retruded chin position as the most-favored profile. Japanese raters tended to choose class II profiles as more acceptable profiles than class III profiles for both males and females. CONCLUSIONS: These findings suggest that Japanese patients with class III profiles tend to seek surgical orthodontic treatment more often.

A comparison and validation of amorphous sensor condylar movement analysis to MRI diagnosis of anterior disc displacement.

This study compared temporomandibular joint condylar movements in a sample of six patients with clinically normal joints, with those of nine patients with joints diagnosed by magnetic resonance imaging (MRI) to have anterior disc displacement with reduction (ADD). The aim of this study was to compare and validate the use of the amorphous sensor to MRI diagnosis in condylar movement analysis. The measuring device consisted of an amorphous sensor and a small magnet. Condylar and jaw movements were recorded simultaneously over the course of 10 open-close cycles. Maximum velocity of condylar movement during the opening phase in the ADD joints was significantly higher than the normal joints. The degree of jaw opening at the turning point of condylar movement in the ADD joints was significantly larger than the normal joints. The diagnostic sensitivity and specificity of the maximum velocity of condylar movement during the opening phase was 75.0 and 75.0%, respectively, while those of the degree of jaw opening at the turning point of condylar movement were 91.7 and 91.7%, respectively. These results suggest that the analysis of condylar movement, employing the amorphous sensor may be a reliable method for diagnosis of ADD.

Dentin regeneration by dental pulp stem cell therapy with recombinant human bone morphogenetic protein 2.

Regenerative medicine is based on stem cells, signals, and scaffolds. Dental pulp tissue has the potential to regenerate dentin in response to noxious stimuli, such as caries. The progenitor/stem cells are responsible for this regeneration. Thus, stem cell therapy has considerable promise in dentin regeneration. Culture of porcine pulp cells, as a three-dimensional pellet, promoted odontoblast differentiation compared with monolayers. The expression of dentin sialophosphoprotein (Dspp) and enamelysin/matrix metalloproteinase 20 (MMP20) mRNA confirmed the differentiation of pulp cells into odontoblasts and was stimulated by the morphogenetic signal, bone morphogenetic protein 2 (BMP2). Based on the in vitro experiments, an in vivo evaluation of pulp progenitor/stem cells in the dog was performed. The autogenous transplantation of the BMP2-treated pellet culture onto the amputated pulp stimulated reparative dentin formation. In conclusion, BMP2 can direct pulp progenitor/stem cell differentiation into odontoblasts and result in dentin formation.

Effects of static magnetic fields on bone formation in rat osteoblast cultures.

Although the promotional effects on osteoblasts of pulsed electromagnetic fields have been well-demonstrated, the effects of static magnetic fields (SMF) remain unclear; nevertheless, magnets have been clinically used as a 'force source' in various orthodontic treatments. We undertook the present investigation to study the effects of SMF on osteoblastic differentiation, proliferation, and bone nodule formation using a rat calvaria cell culture. During a 20-day culture, the values of the total area and the number and average size of bone nodules showed high levels in the presence of SMF. In the matrix development and mineralization stages, the calcium content in the matrix and two markers of osteoblastic phenotype (alkaline phosphatase and osteocalcin) also showed a significant increase. Accordingly, these findings suggest that SMF stimulates bone formation by promoting osteoblastic differentiation and/or activation.

Orthodontic appliances made of organic polymer used in the metal allergic patient can withstand orthognathic surgery.

We developed an orthodontic appliance completely made of organic polymer. The appliance was used for many years and proved very effective. It was used for the treatment of patients with metal allergy, and as a result, it is believed to be the best choice for treating metal allergies. In this report, we are presenting a surgical case with Class III malocclusion for a patient with metal allergy, and the concept of the appliance is briefly discussed.

Changes in tooth position in humans in relation to arterial blood pressure.

The three-dimensional physiological tooth movement synchronized with the heartbeat is called periodontal pulsation. This study utilized a computer-assisted amorphous sensor to evaluate the relation between tooth position and arterial blood pressure, and also between the amplitude of periodontal pulsation and arterial blood pressure. The measuring device consisted of a small magnet attached to the tooth and an amorphous sensor that was used to detect displacement of the tooth without actually contacting it. The sample consisted of the upper left central incisors of six healthy Japanese volunteers. The three measuring points for each tooth were on the labial surface. The cold-pressor test was used as an autonomic nerve stimulus that induces an increase in blood pressure and heart rate. Periodontal pulsation, electrocardiogram, blood pressure and heart rate were recorded simultaneously during a 1 min pre-test relaxation, a 2 min cold-pressor test and a 1 min recovery. The results showed significant correlations between tooth position and mean blood pressure in five of the six volunteers and between tooth position and pulse pressure in four. Moreover, it was confirmed that tooth position shifted in the labial direction in conjunction with an increase of the mean blood pressure induced by cold stimulation. Significant correlations were found between the amplitude of periodontal pulsation and pulse pressure in four of the volunteers. These findings suggest that in humans tooth position might be affected by the force of blood pressure transmitted through periodontal vessels and that the amplitude of periodontal pulsation tends to reflect changes of pulse pressure rather than changes in mean blood pressure.

Expression of cathepsin K mRNA and protein in odontoclasts after experimental tooth movement in the mouse maxilla by in situ hybridization and immunoelectron microscopy.

This study demonstrated the simultaneous expression of cathepsin K (CK) mRNA by in situ hybridization and CK protein by immunoelectron microscopy in odontoclasts in mouse maxillae after experimental tooth movement. On the pressure side (the area under pressure during tooth movement), CK mRNA was detected in odontoclasts in resorption lacunae in the tooth root, in osteoclasts in bone resorption lacuane, and in fibroblasts in the periodontal ligament. Using electron microscopy, CK protein was detected at the apex of odontoclasts, intracellularly in vesicles and granules, and extracellularly in irregularly shaped vacuoles (extracellular spaces), on the plasma membrane of the ruffled border, and on and between typical striated type I collagen fibrils in the lacunae. These vesicles and granules appeared to fuse with irregular vacuoles containing CK-positive fragmented fibril-like structures close to the ruffled border. In the basolateral portion of odontoclasts, small amounts of CK-positive rough endoplasmic reticulum (ER) were found. CK-positive intracellular vacuoles (not extracellular spaces) also appeared to fuse with the vesicles and granules. However, these fused organelles rarely contained fragmented fibril-like structures. They are probably endolysosomes. The distribution of CK in odontoclasts was similar to that previously seen in osteoclasts. Furthermore, CK-positive fibril-like structures were found in the vacuoles of fibroblasts. These results indicated that during tooth movement CK is synthesized in odontoclasts on the pressure side and secreted into the tooth resorption lacunae. Therefore, CK may take part in the degradation of the dentin matrix (type I collagen fibrils and non-collagenous protein) of the tooth root, and in the subsequent intracellular degradation of endocytosed fragmented fibril-like structures in endolysosomes.

Involvement of EF hand motifs in the Ca(2+)-dependent binding of the pleckstrin homology domain to phosphoinositides.

The pleckstrin homology (PH) domains of phospholipase C (PLC)-delta1 and a related catalytically inactive protein, p130, both bind inositol phosphates and inositol lipids. The binding to phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] by PLC-delta1 is proposed to be the critical interaction required for membrane localization to where the substrate resides; it is also required for the Ca(2+)-dependent activation of PLC-delta1 observed in the permeabilized cells. In the proximity of the PH domain, both PLC-delta1 and p130 possess the EF-hand domain, containing classical motifs implicated in calcium binding. Therefore, in the present study we examined whether the binding of the PH domain to PtdIns(4,5)P2 is regulated by changes in free Ca2+ concentration within the physiological range. A Ca2+ dependent increase in the binding to PtdIns(4,5)P2 was observed with a full-length PLC-delta1, while the isolated PH domain did not show any Ca2+ dependence. However, the connection of the EF-hand motifs to the PH domain restored the Ca2+ dependent increase in binding, even in the absence of the C2 domain. The p130 protein showed similar properties to PLC-delta1, and the EF-hand motifs were again required for the PH domain to exhibit a Ca2+ dependent increase in the binding to PtdIns(4,5)P2. The isolated PH domains from several other proteins which have been demonstrated to bind PtdIns(4,5)P2 showed no Ca2+ dependent enhancement of binding. However, when present within a chimera also containing PLC-delta1 EF-hand motifs, the Ca2+ dependent binding was again observed. These results suggest that the binding of Ca2+ to the EF-hand motifs can modulate binding to PtdIns(4,5)P2 mediated by the PH domain.

Induction of abundant osteoclast-like multinucleated giant cells in adjuvant arthritic rats with accompanying disordered high bone turnover.

The development of an in vivo system for investigating osteoclast differentiation is important because molecular events occurring in vivo can be observed during the differentiation of the authentic osteoclasts. In adjuvant arthritic rats, an experimental model of human rheumatoid arthritis, extensive bone resorption is observed in the distal diaphysis of the tibia. In the area of extensive bone resorption, it is always accompanied with clusters of numerous multinucleated giant cells (MGCs) as well as bone-resorbing osteoclasts. Here we characterized the morphological properties of these MGCs with the use of enzymehistochemical and immunohistochemical techniques. Extensive destruction but also a marked formation of the inner and outer bone surfaces were the predominant features in the tibiae of such arthritic rats 4 weeks after the adjuvant injection. Numerous MGCs were frequently clustered in the bone marrow spaces located apart from the bone matrices. Although the MGCs lacked ruffled borders, these cells were rich in mitochondria and vacuoles. These multinucleated cells revealed a positive reaction for tartrate-resistant acid phosphatase but a negative reaction for non-specific esterase staining. Most of these MGCs expressed the Kat 1-antigen, an immunological marker specifically expressed on the cell surface of rat osteoclasts. In a dentin resorption experiment using a cluster of MGCs excised from the bone marrow tissues of the tibial distal diaphyses of rats with adjuvant arthritis, many resorption lacunae were formed on dentin slices after a 3-day culture. These results suggest that the majority of the MGCs are osteoclasts but not macrophage polykaryons.

A study to evaluate the parent-offspring similarity in the maxillofacial profile using fingerprints in Japanese families.

An attempt was made to investigate the parent-offspring similarity in the maxillofacial profile by a quantitative analysis of fingerprints. Lateral roentgenographic cephalograms and ten fingerprints were obtained from 98 Japanese patients (44 males and 54 females) and their parents. Analysis showed a significant parent-offspring correlation for both maxillofacial profile and fingerprints. The relatively low father-son correlation for both features suggests a major influence of X-linked genes. The genetic correlation between the maxillofacial profile and fingerprints was significant for parent-son but not for parent-daughter pairings. The parent-offspring correlation in the maxillofacial profile was evaluated in two groups showing differences (distant group) or similarities (near group) in the fingerprint patterns between the father and mother. In the distant group, a greater parent-offspring similarity was observed in the maxillofacial profile. The same finding was also obtained on using only digit II of the parents. Therefore, from a morphogenetical point of view, parental fingerprints appear helpful in clinical applications designed to predict maxillofacial growth in offspring.

The similarity between parents and offspring in facial soft tissue: a frontal-view study.

Similarities between parents and their offspring in facial soft tissue features were investigated. Fifty boys and fifty girls aged 9-10 years, excluding those with congenital anomalies, were selected. Frontal photographs of the family (father, mother and offspring) were taken and twenty-nine landmarks located on each enlarged tracing made from a photograph. Each landmark was digitised into (x, y) co-ordinate values from which the area and linear ratio dimensions were calculated and statistically evaluated. Results indicated that: (1) The nose was the feature that was most significantly correlated between parents and offspring. (2) The similarities between parents and offspring were closer for the relative positions of other features to the eyes than for individual features of the face. In general, the correlations between 'midparents' (the mean value of both parents) and offspring were higher than those between one parent and offspring. (3) The correlations between parents and offspring for size were higher than those for shape. (4) The similarities between mothers and offspring were closer than those between fathers and offspring. Furthermore: among four pairs of father/son, father/daughter, mother/son and mother/daughter, the mother/daughter pair had the highest correlation and the father/son pair had the lowest, which appears to be related to X-chromosome inheritance.

Quantitative evaluation of correlation of skull morphology in families in an attempt to predict growth change.

The purpose of the present study was to obtain quantitative values for human skull structures in a cross-sectional analysis of offspring and their parents. The offspring were classified into three groups according to age. For each of 11 maxillo-facial and nine dento-alveolar structural angular measurements, the mean and SD were calculated for each set of paternal, maternal, midparent and offspring. The standard deviation unit (SDU) values were calculated from the disparity between the measured value in a given individual, i.e. father, mother, midparent, offspring, and their corresponding group mean value. Three disparity values (D.v.), expressed by the difference between the SDU values in each pair (father-offspring, mother-offspring and midparent-offspring), were developed to evaluate the degree of familial resemblance for each of 20 morphometric measurements, and the differences among these values in three age groups were then investigated. The similarity ratio (S.r.), expressing the degree of correlation to the father and mother, was derived by processing the D.v. The relationship between the maxillo-facial S.r. and the dento-alveolar S.r. was analysed in each age group. There were significant differences between the D.v. in families and those in unrelated control groups. Consistency between the S.r. for maxillo-facial and that for dento-alveolar measurements was found in the older age groups. It is concluded that individual growth of skull morphology might be more predictable using the present method.

Expression of the type I collagen gene in rat periodontal ligament during tooth movement as revealed by in situ hybridization.

The in situ hybridization technique used digoxigenin-labelled oligodeoxynucleotide. In untreated molars, cells expressing a positive signal for type I collagen mRNA were distributed uniformly in the periodontal ligament space. After experimental tooth movement, the density of cells expressing a positive signal appeared to be much greater in the tension side than the pressure side. In both sides the distribution of the positively hybridizing cells was uniform along the principal fibres of the ligament. This characteristic distribution appeared at 12 h after the initiation of tooth movement, reached a maximum at 1-3 days, and persisted for about 14 days during the treatment. These results indicate that the remodelling of collagen fibres in periodontal ligament occurs in an orderly manner throughout the principal fibres, mainly on the tension side, and that the recovery of gene expression for type I collagen occurs within the first 14 days in response to experimental tooth movement.

Growth-related changes in familial resemblance of maxillofacial morphology.

We investigated changes in resemblance between Japanese parents and their growing children with regard to maxillofacial morphology. Lateral roentgenographic cephalograms taken from 963 children (336 male and 627 female) over 6 years of age and their parents were used as samples. Based on the age of the children, there were six groups--I: 6-7 years of age; II: 8-9; III: 10-11; IV: 12-13; V: 14-15; and VI: over 16. Parent-offspring heritabilities (h2) were computed for 35 variables representing maxillofacial and dentoalveolar traits, and group comparisons were also made. The following results were obtained: (1) there were more significant heritabilities for maxillofacial variables than those for dentoalveolar ones; (2) in general, additive genetic effects were more prominent in controlling maxillofacial and dentoalveolar structure of on-growing children, with increasing age.