Vestibular dysfunction in adult patients with osteogenesis imperfecta.

Progressive hearing loss is a major symptom in osteogenesis imperfecta (OI), a genetic brittle bone disease. Vertigo is frequently associated with otosclerosis in which the hearing loss clinically resembles that in OI. Vertigo is also common in basilar impression (BI) found in up to 25% of adult OI patients. In order to evaluate the cause, frequency, and characteristics of vertigo in OI, 42 patients were studied by interview, clinical examination, and audiological examination supplemented with electronystagmography (ENG) and lateral skull radiography. Audiometry showed hearing loss in 25 patients (59.5%). Nine patients (21%) displayed abnormal skull base anatomy in the forms of basilar impression, basilar invagination, or both, all designated here as BI. Twenty-two patients (52.4%) reported vertigo, mostly of floating or rotational sensation of short duration. Patients with hearing loss tended to have more vertigo than patients with normal hearing. Vertigo was not correlated with type of hearing loss or auditory brain-stem response (ABR) pathology. ENG was abnormal in 14 patients (33.3%). No dependency was found between vertigo and deviant ENG results. Patients with BI tended to have more vertigo than patients with normal skull base but the difference was not statistically significant. Neither ENG pathology, nor the presence or type of hearing loss showed correlation with BI. In conclusion, vertigo is common in patients with OI. In most cases, it may be secondary to inner ear pathology, and in only some patients does BI explain it. Since some OI patients without BI or hearing loss also suffer from vertigo, further clinical and neurological studies are needed to define the pathogenesis of vertigo in OI.

Craniofacial features in Cohen syndrome: an anthropometric and cephalometric analysis of 14 patients.

Cohen syndrome (Mendelian Inheritance in Man [MIM] no. 216550) is a rare, autosomal-recessive inherited disorder with mental retardation and a typical appearance. The condition is relatively common in Finland where 35 patients have been diagnosed. We studied 22 patients in detail, obtaining anthropometric measurements of the head and face, and cephalometric radiographs of 14 patients (14-57 years of age). Measurements of patients were compared to population norms and matched controls. Anthropometric analysis confirmed and quantified the previously described syndrome features: small head size [-4 standard deviations (SD)], with varying cephalic index. Width of the upper face was close to normal, but width of the lower face was small. Philtrum length was shorter than in healthy controls (p = 0.0039 in females and p = 0.0014 in males). The measurements from standardized radiographs revealed short cranial base dimensions (-2.2 and -2.6 SD), but normal cranial base angles. Prognathism of jaws was within normal limits. Reduced head size (microcephaly), short philtrum and small cranial base dimensions are essential features in Cohen syndrome. In addition, most patients had forward-inclined upper incisors and maxillary prognathia. We conclude that exact measurements mostly confirmed the Cohen syndrome description based previously on clinical impression.

In utero/lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure impairs molar tooth development in rats.

Developmental defects caused by dioxins are causing increasing concern since they occur at low dose levels and are usually permanent. In this study we examined the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at low in utero/lactational exposure levels on rat tooth development in three rat lines, denoted A, B, and C, that differ in their TCDD sensitivity and aryl hydrocarbon receptor structure. These rat lines are derived from TCDD-resistant Han/Wistar (Kuopio) and TCDD-sensitive Long-Evans (Turku/AB) rats by selective breeding. The main target teeth were the third molars, since their development spans from the perinatal period to about 6 weeks after birth. Pregnant dams were exposed to 0.03-1 microg/kg TCDD on gestation day 15. Pups exposed in utero and lactationally were euthanized at the age of 5 or 10 weeks and the jaws were examined. The eruption of the third molar was observed by stereomicroscopy and the jaws were further radiographed. TCDD at 1 microg/kg completely prevented the development of the third lower molars in 60% of males and 50% of females in the most sensitive rat line, C, while only 6% or less of the pups in the more resistant lines A and B were lacking this target tooth. TCDD exposure also dose-dependently diminished the proportion of third molars erupted at the age of 5 weeks. The size of molars was dose-dependently reduced in all rat lines. The third lower molars were most severely affected, and the reduction was significant already at 0.03 microg/kg in line A and at 0.1 microg/kg in lines B and C. The results indicate that impaired tooth development is one of the most sensitive endpoints of TCDD-induced toxicity.

Arrest of rat molar tooth development by lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The interference with tooth development by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was studied in dioxin-resistant Han/Wistar rats. Lactating dams were given a single dose of 50 or 1000 microg TCDD/kg body wt 1 day after delivery and the pup heads were analyzed radiographically or histologically at postnatal days 9 and/or 22. Of 19 animals studied histologically, 10 lacked one or more third molars, which were at the bud stage at the start of the experiment. A higher proportion of pups exposed to the higher dose (9/13) lacked third molars than those exposed to the lower dose (1/6) (27/52 and 2/24 teeth missing, respectively). Missing upper third molars (19/38) were more frequent than were lower (10/38). The development of the third molars present was retarded. The root tips of the more advanced first and second molars were prematurely closed and root formation was arrested, but eruption was not affected. Dentinogenesis of the continuously erupting lower incisor teeth was preeruptively arrested because of pulpal cell death. All the teeth of the control rat pups developed normally. In contrast to the control pups, none of the 11 experimental pups examined radiographically (6 exposed to the higher dose and 5 to the lower) showed mineralization of their third molar cusps. The results show that the effects of TCDD on rat tooth development depend on not only the dose but also the tooth type and developmental stage. Inasmuch as early tooth development is under the control of inductive interactions between the epithelium and the mesenchyme, the interference by TCDD with tooth morphogenesis with the consequent arrest of development is likely to involve epithelial-mesenchymal signaling.

Associations between thoracic kyphosis, head posture, and craniofacial morphology in young adults.

The aim of the present study was to investigate associations between thoracic hyper- and hypokyphosis, head posture, and craniofacial morphology in young adults. Using forward bending test and spinal pantographic measurements, 31 subjects, 16 with thoracic hyper- and 15 with hypokyphosis, were selected from a population-based cohort of 430 young adults. Lateral roentgen-cephalograms were taken in natural head posture and craniofacial and postural angular measurements were calculated. Any statistically significant differences between the groups thoracic hyperkyphosis and thoracic hypokyphosis--were analysed using Student's t test. Subjects with thoracic hyperkyphosis had a larger atlantocervical angle (At/ CVT, P < 0.01) than subjects with thoracic hypokyphosis. However, head position (NSL/VER) was similar in both groups, probably owing to the visual perception control of craniovertical relation. There was no statistically significant difference in craniofacial morphologyy between the groups.

The effect of violin playing on the bony facial structures in adolescents.

Holding a violin between shoulder and chin needs a special kind of muscle function. The purpose of this investigation was to determine whether this kind of muscular activity is a modifying factor for facial growth in adolescence. The bony facial dimensions of 24 adolescent violin students attending colleges of music with a playing history of 5-11 years were measured from lateral and posteroanterior cephalograms and panoramic tomograms of the jaws. The dimensions were compared with those of sex- and age-matched controls. Significant differences were found between violin players and controls. The players had higher faces, especially on the right side of the lower face and in the right mandibular ramus. The players also had more proclined upper and lower incisors than the controls. It is concluded that the overall greater facial height in violinists reflects the increased face muscle activity and the higher bony dimensions of the right side of the face are due to the muscular activity produced on that side to balance the load caused by the violin on the left. The greater proclination of the incisors is the result of an altered balance of muscular activity between tongue and lip, and the pressure of the violin to the chin.

The effect of professional violin and viola playing on the bony facial structures.

Professional violin and viola playing involves a particular kind of asymmetric face, neck and shoulder muscle activity. The aim of this study was to find out whether players' facial morphology is influenced by this occupational orofacial muscle activity. Lateral and posteroanterior cephalograms and panoramic tomograms of 26 adult professional violin and viola players were evaluated and compared with those of age, sex and dentition matched controls. Significant differences were found between the players and the controls. The players had smaller facial heights, more proclined maxillary incisors and greater mandibular lengths. Thus, intense long-term violin/viola playing has the effect of modifying facial morphology.

Transverse facial morphology in patients with diastrophic dysplasia.

Diastrophic dysplasia (DTD) is a well-characterized, recessively inherited osteochondrodysplasia. Thirty-seven patients were studied for transverse craniofacial characteristics. Of these patients, 10 had cleft palate and 11 had submucous cleft palate. A cephalometric analysis based on posteroanterior (PA) cephalograms was performed: 16 landmarks were identified and digitized into a computer. Seven linear and four angular variables were calculated and the values compared with those of a matched control population. DTD patients differed from controls only in cases with cleft palate where the mesio-orbital, bigonial, and antegonial widths were large compared with controls. The present findings indicate that although the development and growth of cartilaginous structures are disturbed in DTD, the intramembranously developing bones and the appositional growth pattern do not seem to be primarily affected.

Signs and symptoms of temporomandibular disorders in adolescent violin players.

Signs and symptoms of temporomandibular disorders (TMDs) and the frequency of radiologically observed abnormalities in the condyles of temporomandibular joints (TMJs) of adolescent violin players (VP group) were investigated in a group of 31 music students and in their age- and sex-matched controls (C group). All subjects underwent a routine clinical stomatognathic examination, a standardized interview, and radiography of the condyles. The VP group reported a higher frequency of the subjective symptoms: pain in the TMJ when chewing, a feeling of stiffness in the TMJ, and clenching of the teeth. Clinically, the VP group showed a greater range of maximal protrusion and of maximal laterotrusion to the right, and a greater frequency of deviation to the right on opening. They also showed more palpatory tenderness in the masticatory muscles and pain in the TMJ on maximal opening. The number of playing years and the number of weekly playing hours correlated with several signs and symptoms of TMDs. In terms of radiologic findings in the condyles of the TMJs there was no difference between the groups. It is concluded that intense violin playing may have a predisposing role in the etiology of TMDs in adolescence.

Signs and symptoms of temporomandibular disorders and radiologically observed abnormalities in the condyles of the temporomandibular joints of professional violin and viola players.

The frequency of temporomandibular disorders (TMDs) and radiologically observed abnormalities in the condyles of the temporomandibular joints (TMJs) of professional violin and viola players was investigated in 26 orchestra violinists/violists (VP group) and in their sex-, age-, and dentition-matched controls (C group). A routine clinical stomatognathic examination, a standardized interview, and radiography of the condyles were carried out for all subjects. The VP group showed a higher frequency of subjective symptoms and clinical signs of TMD, such as palpatory tenderness of masticatory muscles, TMJ clicking, painful mandibular movements, and deviation on opening or closing. There was no difference between the groups in terms of radiologic findings in the condyles. Weekly playing hours correlated positively with some signs of TMD. It is concluded that professional violin or viola playing might be a predisposing factor for TMD.

A sebaceous gland in the dorsal surface of the tongue.

The presence of a sebaceous gland in the dorsal surface of the tongue is described. Its features are compared with the 5 previously reported cases.

Degenerative temporomandibular joint disease in a young violinist.

A case is reported of degenerative joint disease in the right mandibular condyle of an 11-year-old boy, apparently due to violin playing.