Outi Kovero

Developmental dental aberrations after the dioxin accident in Seveso.

Children’s developing teeth may be sensitive to environmental dioxins, and in animal studies developing teeth are one of the most sensitive targets of toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Twenty-five years after the dioxin accident in Seveso, Italy, 48 subjects from the contaminated areas (zones A and B) and in patches lightly contaminated (zone R) were recruited for the examination of dental and oral aberrations. Subjects were randomly invited from those exposed in their childhood and for whom frozen serum samples were available. The subjects were frequency matched with 65 subjects from the surrounding non-ABR zone for age, sex, and education. Concentrations of TCDD in previously analyzed plasma samples (zone ABR subjects only) ranged from 23 to 26,000 ng/kg in serum lipid. Ninety-three percent (25 of 27) of the subjects who had developmental enamel defects had been < 5 years of age at the time of the accident. The prevalence of defects in this age group was 42% (15 of 36) in zone ABR subjects and 26% (10 of 39) in zone non-ABR subjects, correlating with serum TCDD levels (p = 0.016). Hypodontia was seen in 12.5% (6 of 48) and 4.6% (3 of 65) of the zone ABR and non-ABR subjects, respectively, also correlating with serum TCDD level (p = 0.05). In conclusion, developmental dental aberrations were associated with childhood exposure to TCDD. In contrast, dental caries and periodontal disease, both infectious in nature, and oral pigmentation and salivary flow rate were not related to the exposure. The results support our hypothesis that dioxins can interfere with human organogenesis.

Maximal bite force and its association with signs and symptoms of TMD, occlusion, and body mass index in a cohort of young adults.

ABSTRACT The purpose of this population-based cohort was to measure maximal bite force (MBF) in the molar and incisal regions and to examine whether MBF was associated with TMD, gender, occlusion (in terms of overjet, overbite, and total number of occluding contacts), and body mass index (BMI). MBF in the molar and incisal regions was measured using a calibrated method in 384 (196 males, 188 females) and 357 (181 males, 176 females) subjects, respectively. Two attempts in each region (right molar, left molar, and incisal) were made in random order. The subjects completed a multiple-choice questionnaire including subjective symptoms of TMD and were subsequently clinically examined. Helkimos clinical dysfunction index and BMI were calculated. The mean MBF value in the molar region was significantly higher in males (878 N, SD 194) than in females (690 N, SD 175) (p<0.001). The incisal forces were 283 N (SD 95) and 226 N (SD 86) (p<0.001), respectively. According to multiple linear regression, TMJ discomfort was significantly negatively associated with MBF in the molar region (p<0.05) and overjet was significantly negatively associated with maximal incisal bite force (p<0.05). No significant associations between MBFs and body mass were found. The results demonstrate that in a population-based cohort of young adults signs, and symptoms of TMD and studied occlusal factors, unlike body mass, associate independently with MBF.

Craniofacial features in osteogenesis imperfecta: a cephalometric study.

Osteogenesis imperfecta (OI) is a heterogeneous group of connective tissue diseases that mainly manifest as bone fragility and skeletal deformity. In most families it segregates as a dominant trait and results from mutations in type I collagen genes. In this study we analyzed the size and form of the bony structures in heads of 59 consecutive patients with OI types I, III, or IV (Sillence classification), using lateral radiographs. Paired controls were matched for gender and age. The purpose was to obtain baseline information of craniofacial development in OI patients that have not received bisphosphonate treatment. In OI type I we found smaller than normal linear measurements, indicating a general growth deficiency, but no remarkable craniofacial deformity. In OI types III and IV, the growth impairment was pronounced, and the craniofacial form was altered as a result of differential growth deficiency and bending of the skeletal head structures. We found strong support both for an abnormally ventral position of the sella region due to bending of the cranial base, and for a closing mandibular growth rotation. Vertical underdevelopment of the dentoalveolar structures and the condylar process were identified as the main reasons for the relative mandibular prognathism in OI. Despite of the widespread intervention with bisphosphonates, the facial growth impairment will probably remain characteristic for many OI patients, and their orthodontic treatment should be further developed.

Maximal bite force and its associations with spinal posture and craniofacial morphology in young adults

Maximal bite force (MBF) and its associations with craniofacial morphology and spinal posture were studied in a group of young adults (46 M and 38 F) aged 21 to 23 years. MBF was recorded in molar and incisal regions. Sagittal spinal posture was measured by spinal pantography and trunk asymmetry at thoracic and lumbar levels by a forward-bending test. Craniofacial variables and posture of the cervical spine were examined from lateral cephalograms taken in a natural head position. No statistically significant correlations existed between MBF and spinal posture, but significant correlations did exist between MBF and craniofacial variables, especially in women.

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.

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 Students 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 morphology between the groups.

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.

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.

Trunk asymmetry and facial symmetry in young adults.

The aim of the present study was to detect possible associations between trunk and cervical asymmetry and facial symmetry. Frontal cephalograms prepared in the natural head position, representing 79 subjects (40 males, 39 females) with mild to moderate trunk asymmetry, were analyzed separately for thoracic humps, lumbar prominences, and cervical inclination by discriminating two groups: right-sided-dominant and left-sided-dominant. The differences between the groups were analyzed using an unpaired 2-group t test. The results showed that location of the thoracic humps and inclination of the cervical spine was predominantly right-sided, while the location of lumbar prominence was predominantly left-sided. Craniofacial morphological variables of the head and face were nearly equal for right-sided and left-sided thoracic humps and lumbar prominences, showing that moderate trunk asymmetry does not affect facial symmetry. Further, it was found that frontal head position in relation to the true vertical (VER/ORB) is stable in that the angle between the supraorbital and vertical lines is constantly maintained close to 90 degrees regardless of moderate trunk asymmetry, indicating that visual perception control is most important in orienting the head in frontal plane. Maintenance of the head position takes place by cervical spine adaptation.