Cortical representation of experimental periodontal pain: a functional magnetic resonance imaging study.

The aim of this study was to investigate central pain representations during loading of the periodontium induced by orthodontic and occlusal stress. Nineteen healthy male volunteers (25.7 ± 2.8 years) were tested on two consecutive days: after phenotyping (questionnaires) and determination of warmth (WPT) and heat (HPT) pain thresholds, functional magnetic resonance imaging was performed as event-related paradigm including 36 tooth clenchings of 3 s duration, alternating with rest periods varying between 20-30 s. The task was performed in absence (T1) and 24 h after placement of an elastic separator between the second bicuspid and the first molar on the right side of the lower jaw (T2). No significant changes in WPT and HPT were observed but pain ratings were significantly elevated at T2. Significantly elevated activation at T2, as compared to T1, was found in bilateral sensorimotor cortex, bilateral secondary sensory cortex, supplementary motor area, right rolandic operculum, and bilateral insula. Our data show for the first time in humans that periodontal stimulation, as tested by tooth clenching in the presence of an elastic separator, goes along with specific expressions of pain at behavioral and neuronal network levels. Findings supplement the existing neuroimaging literature on odontogenic pain.

Predicting vertical growth of the mandibular ramus via hand-wrist radiographs.

AIM: The purpose of this study was to investigate whether growth increments of the mandibular ramus in the vertical direction can be predicted using cephalometric variables in combination with a hand-wrist radiograph. PATIENTS AND METHODS: Our data comprised cephalograms taken at the beginning (T1) and end (T2) of orthodontic treatment, and hand-wrist radiographs taken at T1 of 49 adolescent patients with a Class I malocclusion. Cephalograms were scanned and analyzed with the aid of a computer. Relative growth increments (in %) of body height and different cephalometric variables during the observation period were recorded. Growth changes were compared statistically to each other and to the growth prediction assessed with the hand-wrist radiograph according to Greulich and Pyle (GPP). Stepwise linear regression (SPSS®) was used to statistically analyze the impact of gender, age, body height, growth prediction as assessed with a hand-wrist radiograph, and cephalometric variables at T1 on changes in the increase in the height of the mandibular ramus. RESULTS: Growth prediction assessed via hand-wrist radiographs at the beginning of treatment did not enable a reliable prediction of the remaining vertical growth of the mandibular ramus. Only the patient's gender and height of the mandibular ramus at the beginning of treatment had a statistical impact on growth changes in the ramus height that occurred during the observation period. CONCLUSION: Our results suggest that the vertical growth potential of the mandibular ramus cannot be predicted by analyzing hand-wrist radiographs or by evaluating cephalometric variables other than the initial mandibular ramus height.

Reliability of growth prediction with hand-wrist radiographs.

The aim of this study was to investigate the validity of hand-wrist radiographic analysis in estimating the amount of remaining craniofacial growth. The material compromised cephalograms of 22 males and 27 females with a Class I malocclusion. The median age of the females at the beginning (T1) was 11 years 10 months and of the males 12 years 6 months and at the end (T2) of treatment 14 years 7 months and 15 years 3 months, respectively. Statural height was measured and a lateral cephalogram was obtained for every patient at T1 and T2. A hand-wrist radiograph was taken only at T1. The cephalograms were scanned and analyzed. Relative dimensional growth changes in statural height as well as of the length of the cranial base (N-S), the maxilla (Ptm-A), and the dimensions of the mandible (Co-Gn, Go-Gn, and Co-Gn) from T1 to T2 were determined and statistically compared (Pearson's correlation coefficients) with the growth prediction assessed with the help of hand-wrist radiographs according to Greulich and Pyle. The results showed a highly significant correlation between statural growth increases and growth prediction assessed from the hand-wrist radiographs (females: r = 0.68; males: r = 0.7). Concerning craniofacial structures, the increase in mandibular corpus showed the highest correlation with growth prediction (females: r = 0.21; males: r = 0.52), but this association would not allow a reliable growth prediction. There was no significant correlation between growth increases of the cranial base, the maxilla, the ramus, and the effective length of the mandible and growth prediction assessed with the help of hand-wrist radiographs. As each patient has an individual growth pattern and different craniofacial structures show individual growth potential, it is questionable if quantitative craniofacial growth prediction with the help of hand-wrist radiographs is reliable. However, in an individual case for the assessment of the timing of the growth process, a hand-wrist radiograph can contribute to treatment planning.

Quantitative histological and ultrastructural features of opercula of normally erupting human teeth.

Tooth eruption across the mucosa in humans has been studied rarely, although there are disturbances of eruption that are attributed specifically to failure of the supraosseous eruptive migration. The aim of this study was to analyze the soft tissues covering normally erupting teeth so as to get an insight into the supraosseous phase of tooth eruption and to provide the basis for comparison with cases of eruption disturbances. Six opercula covering normally erupting permanent molars (primary opercula) and six of succedaneous teeth (secondary opercula) were surgically removed from 10 patients aged 7.5-17.5 years. Specimens were examined light and electron microscopically and analyzed morphometrically. All opercula contained strands and islands of odontogenic epithelium, prominent numbers of high endothelial venules, nerves, and mast cells. Nerves comprised normally structured, 1.5-3.5 microm thick myelinated (Adelta) and thinner unmyelinated (C) fibers. In primary opercula, the proportions of blood vessels and nerves were three- and sevenfold higher than the respective values for the secondary opercula. Furthermore, primary opercula contained multinucleated, fibroblast-like giant cells that were not observed in secondary opercula. As all teeth under investigation were erupting normally, neither the presence of the giant cells nor the atypical proportions of blood vessels and nerves appeared to be decisive in the eruption process. These conspicuous tissue components of opercula seem merely to accompany the eruptive tooth movement.