Novel LQT-3 mutation affects Na+ channel activity through interactions between alpha- and beta1-subunits

This study describes mesial and distal enamel thickness of the permanent posterior mandibular dentition. The sample comprised 98 Caucasian adults (59 males, 39 females) 20 to 35 years old. Bitewing radiographs of the right permanent mandibular premolars and first and second molars were illuminated and transferred to a computer at a fixed magnification via a video camera. Enamel and dentin thicknesses were identified and digitized on the plane representing the maximum mesiodistal diameter of each tooth. The results showed that there were no significant sex differences in either mesial or distal enamel thickness. Enamel on the second molars was significantly thicker (0.3 to 0.4 mm) than enamel on the premolars. Distal enamel was significantly thicker than mesial enamel. There was approximately 10 mm of total enamel on the four teeth combined. Assuming 50% enamel reduction, the premolars and molars should provide 9.8 mm of additional space for realignment of mandibular teeth.     

Molar polymorphisms and the timing of dentition mineralization

The chronological age, skeletal age, and morphological age at the time of mineralization of 14 stages of the permanent teeth of 121 boys and 111 girls of the serial experimental sample of the Burlington Growth Centre were contrasted according to whether or not the children had 4- or 5-cusped mandibular permanent first molars, and whether or not they had agenesis of one or more third molars. In the boys with 4-cusped mandibular first molars, the mineralization of the teeth occurred at significantly earlier chronological and skeletal ages when they were significantly shorter in stature. Tooth mineralization was not consistently earlier in the girls with 4-cusped molars, but these girls tended to be taller and heavier than those with 5-cusped molars. In contrast, in both sexes with agenesis of third molars, the mineralization of the teeth was significantly delayed according to chronological, skeletal and morphological evaluation. The change in timing of mineralization was greatest for the second premolars and second molars, and least for the first molars.     

Histological, clinical, and digital subtraction radiographic evaluation of repair of periodontal defects resulting from mechanical perforation of the chamber floor using ePTFE membranes

The aim of this study was to test the hypothesis that a biocompatible membrane, when placed between the gingiva and cortical bone in teeth with periodontal defects that occurred following mechanical endodontic perforation, would facilitate greater regeneration than in control sites not treated with guided tissue regeneration. One beagle dog with a healthy periodontium was used in the study. The maxillary right first and second molars and the mandibular left first and second molars acted as the experimental group in which furcation perforations were treated by guided tissue regeneration. The maxillary left and mandibular right first and second molars served as the controls in which furcation perforation lesions were only treated by open flap debridement. Clinical, histological, and standardized radiographic evaluation showed significant differences between the test and control groups. In addition, digital subtraction radiography revealed a gain in alveolar bone height and increased density at all experimental sites, and a loss at all control sites. Histological evaluation showed extensive regeneration of both alveolar bone and connective tissue at experimental sites, but none at control sites. The results of this study suggest that the use of guided tissue regeneration in furcation lesions produced by endodontic perforations will result in significant new bone and connective tissue attachment.     

Monitoring of WT-1 gene expression in peripheral blood of patients with acute leukemia by semiquantitative RT-PCR; possible marker for detection of minimal residual leukemia

The effect of implanting autogenous and xenogenous (Bio-Oss) bone transplants into metabolically active sites within beagle dog mandibles during permanent premolar tooth eruption was examined. Ten 14-week-old beagles were used. Before commencing the radiographic experiments, metal bone markers were placed in the caudal margin of the mandible at the age of 10 weeks. The deciduous first and third molar teeth were extracted and their sockets over the permanent second and fourth premolars were implanted with autogenous particulate enchondral iliac crest bone, autogenous particulate membraneous mandibular body bone, xenogenous bovine anorganic bone mineral spongiosa granules (1-2mm3) (Bio-Oss, Geistlich Pharma, Switzerland) of left empty. The third premolar served as control site. Standardized oblique lateral radiographs were taken once a week. A number of coordinates of defined points and structures were determined by means of a coordinate digitizing system. Animals were killed 4, 10 and 16 weeks after bone transplantation for histological examination of the transplantation sites. All premolars showed no delay in eruption or disruption of crown and root development. On histology, the Bio-Oss particles were not resorbed or integrated in the alveolar bone but were pushed forward into the gingiva. We have demonstrated that there is on difference in the eruption curve of the permanent premolars in the four groups (ANOVA P > 0.5) and that bone transplantation has no inhibitory effect on eruption (ANOVA P > 0.3) and crown development of the underlying permanent premolar but that Bio-Oss does not have the same resorbable or integrating capability as autogenous bone grafts.     

Dental root surface structure as an indicator of age

The purpose of this investigation was to examine the relationship between the root surface structure of human teeth and the age of the individual and also to evaluate whatever contribution this relationship might give to multiple regression methods for age estimation. The material, consisting of 1000 permanent teeth, excluding molars, was examined by means of a new scoring system (Surface Roughness Scores, SRS) for surface roughness, in addition to the scoring systems of Gustafson (RG) and Johanson (RJ) for root resorption. Statistical analyses using the SPSS package indicated a symmetric left/right distribution of root surface structure. The Pearson correlation between age and RJ varied from -0.02 for maxillary central incisors to 0.54 for mandibular central incisors and was approximately the same for RG. These two scoring systems seem to be of little value in methods for age estimation. Correlations between age and the new scoring systems SRS were significant for all teeth and varied from 0.44 for maxillary second premolars to 0.68 for mandibular first premolars. There was no detectable influence of gender or reason for extraction. However, the SRS could not be assessed with sufficient reproducibility, and the estimates were therefore too subjective to be used as the sole criterion for age estimation. This scoring system could, however contribute positively to a multiple regression method.     

A morphometric analysis of the furcation region of mandibular molars

This study examined furcation dimensions and morphology in first and second mandibular molar teeth. One hundred thirty-four extracted human mandibular molars with divergent roots were selected. Teeth were viewed at 7X magnification on a dissecting microscope interfaced with a computer equipped with a state-of-the-art histomorphometry software program. Various aspects of furcation anatomy were measured and recorded. Data were examined by using analysis of variance for all paired comparisons. For nonparametric data, the Kruskal Wallis test was used. Results indicated that 61.94% of buccal and 50.75% of lingual molar surfaces presented with cervical enamel projections (CEPs), with the highest frequency noted in second molars. CEPs ranged from 0.98 mm to 1.33 mm, whereas root trunk heights varied between 2.23 mm and 2.93 mm. Generally, lingual molar surfaces had longer root trunks when compared to buccal surfaces. Root separation increased by approximately 0.5 mm at each 1-mm increment apical to the furcal roof. This study provides new information regarding the furcal anatomy of mandibular molar teeth and supplements previous reports that suggest the CEP is a common problem which must be addressed by clinicians when treating molar teeth.     

Quantitative and somatotopic mapping of neurones in the trigeminal mesencephalic nucleus and ganglion innervating teeth in monkey and baboon

Neurones of the trigeminal mesencephalic nucleus (Mes V) and ganglion innervating the periodontium of incisor, canine and molar teeth in 10 monkeys and 10 baboons were counted and mapped using the horseradish peroxidase (Hrp), retrograde axonal transport method. Periodontal afferent neurones of all these teeth were well represented in the Mes V, although the incisors had a significantly higher number of labelled neurones than the canines or molars. The primary cell bodies of the periodontal afferents were located mainly in the caudal part of the ipsilateral Mes V from the level of the inferior colliculus to the floor of the fourth ventricle in the pons. The caudal periodontal Mes V neurones may be favourably located to make collateral connections with the trigeminal motor nucleus for jaw reflexes. Incisors and canines had a large and predominantly ipsilateral representation of Hrp-labelled neurones in the ganglion. In contrast, molar representation in the ganglion was sparse and all labelled neurones supplied ipsilateral teeth. The maxillary and mandibular teeth had a somatotopic distribution within the respective maxillary (middle) and mandibular (posterolateral) compartments of the trigeminal ganglion. It is suggested that the anterior teeth with greater connections to the Mes V and the ganglion may impart greater sensory perception and be involved in jaw reflexes to ensure a good occlusal relation during mastication, while the afferent connections of the molars may initiate complex jaw reflexes during the occlusal phase of mastication.     

An evaluation of the incisive nerve block and combination inferior alveolar and incisive nerve blocks in mandibular anesthesia

The purpose of this study was to measure the degree of anesthesia obtained with the incisive nerve block, the inferior alveolar nerve block and a combination of both injections in mandibular teeth. Using a repeated measures design, 40 subjects randomly received an incisive nerve block, a conventional inferior alveolar nerve block, or a combination inferior alveolar nerve block plus an incisive nerve block using either lidocaine or saline (control), at four successive appointments. The mandibular teeth and contralateral canine (+/- controls) were blindly tested with an Analytic Technology pulp tester at 4-min cycles for 60 min. An 80 reading indicated complete pulpal anesthesia. The incisive nerve block alone did not result in successful pulpal anesthesia in the central, lateral, first, and second molars. It was successful in the first and second premolars but the duration was approximately 30 min. The combination inferior alveolar nerve block plus incisive nerve block was successful in the first and second premolars, and enhanced anesthesia for the laterals and first molars.     

Parental awareness of dental caries in toddlers

Endodontic endosseous implants stabilize teeth that have crown-root ratios compromised by periodontal disease, trauma, or apical resorption. By increasing the crown-root ratio, the implant improves the prognosis of the tooth, thus increasing its longevity. The purpose of this study was to evaluate, in vivo, the healing response to a newly introduced titanium endodontic implant. Eight implants were placed in the maxillary incisors and mandibular premolars of two adult beagle dogs after completion of root canal and osseous preparation. Peri-implant tissues were examined radiographically and histologically at 6 months postinsertion. Radiographically, the periapical area and tissue surrounding the implants seemed normal. Histologically, fibrous connective tissue and healthy bone intimately surrounded the implant. Epithelium or chronic inflammatory cells were not observed along the length of the implant. These findings suggest that titanium is a biocompatible metal when used as an endodontic endosseous implant.     

Effectiveness of caries removal by the partial tunnel preparation method

The tunnel preparation method is designed to remove approximal caries through a channel from the occlusal surface while preserving the marginal ridge. This method entails reduced access to the caries lesion and thereby uncertainty as to the complete removal of caries. The purpose of the present investigation was to study the effectiveness of caries removal in 60 extracted premolars and molars by the partial tunnel preparation method. The glass polyalkenoat (ionomer) filling and the distance to the pulp were also examined. Examination of the sectioned teeth showed residual caries in the axial wall of two teeth and in dentin close to the enamel lesion in 10 teeth. Very few porosities were found within the glass polyalkenoat material and at the interface between the filling and the cavity walls.     

Dental caries in the deciduous teeth of the children from Gulbarga, Karnataka

A cross-sectional dental examination of 1,560 randomly selected unrelated children of Gulbarga, Karnataka has shown about 30% of the children with deciduous teeth suffering from one or more carious teeth. The proportion of male children with df teeth was larger than female ones; the difference between the two being statistically significant (chi 12 = 8.0387). Its incidence was higher in children of low income group. Muslims (36.2%) were found to be affected more than Hindus (29.6%) and Christians (27.8%). An increase in the frequency of carious children was observed with the increasing age excepting the children aged 12 years and above who have shown a decreasing trend. In both the sexes mandibular teeth were found more susceptible than maxillary ones. No side difference was found in either jaw. Lower second molars were affected more, followed by lower first and upper second molars. Toothwise prevalence of caries by age showed no consistent trend either in maxilla or mandible.     

Cholesterol 7 alpha-hydroxylase activity in hypothyroidism and hyperthyroidism in humans

The effects of three root-end filling materials on healing following endodontic surgery were assessed radiologically and correlated with histological findings reported elsewhere. The materials compared were a light-cured glass ionomer cement (Vitrebond), a reinforced zinc oxide-eugenol cement (Kalzinol) and amalgam. The root canals of 27 two-rooted mandibular premolar teeth of six beagle dogs were inoculated with endodontic pathogenic bacteria to induce periradicular lesions. The roots were apicected and root-end cavities filled with the tested filling materials. The teeth and surrounding jaw were removed after 4 weeks (30 roots) or 8 weeks (24 roots). Radiographs were taken of each jaw section and subjected to image analysis. Healing was evaluated based on measurements of the size of the periradicular radiolucent areas. ANOVA disclosed no statistically significant differences in the size of the periradicular areas either between time periods or between materials. These results did not correlate with the tissue responses in the same material as assessed histologically and previously reported. The use of radiographs alone to assess healing after endodontic surgery in the dog mandible is unsatisfactory, and should not be regarded as a substitute for histological examination for the determination of healing.     

Diagnosis of infra-alveolar bony lesions in the dentate alveolar process with high-resolution computed tomography. Experimental results

RATIONALE AND OBJECTIVES: Conventional intraoral radiography was compared with axial computed tomography (CT) scans for identification and classification of bony pockets in dentate jaw segments. METHODS: Fifty-five artificial bone defects were produced in six dentate jaw segments. The jaws were examined radiographically using a dental x-ray unit and by contiguous axial CT scans. Identification, classification, and vertical depth of the bony defects were compared among the specimens, radiographs, and CT scans. RESULTS: On the intraoral radiographs, 38 (69%) bony lesions were identified, and the vertical depth was underestimated by a mean of 2.2 mm, compared with the objective measurements on the jaws. In contrast, all artificial bony lesions (100%) were identified and classified on the axial CT scans and the vertical depth was underestimated by a mean of 0.5 mm. CONCLUSIONS: High-resolution CT improves the identification and metric assessment of the vertical dimension of infra-alveolar bony lesions compared with conventional intraoral x-ray films and allows these defects to be classified according to the number of existing walls into one-walled, two-walled, and three-walled bony pockets. In patients with apically extended metallic restorations, the image quality could be limited by artifacts.     

Relationship between prostaglandin E2 concentrations in periapical exudates from root canals and clinical findings of periapical periodontitis

In this study the relationship of prostaglandin E2 (PGE2) concentrations in periapical exudates with clinical findings of teeth with periapical periodontitis is discussed. Periapical exudate samples were obtained from root canals of 77 endodontically involved teeth during routine root canal treatment by the quantitative sampling method using paper points. PGE2 concentrations in periapical exudates (PE-PGE2) were determined by radioimmunoassay. Significantly higher levels of PGE2 were found in periapical exudates from teeth with radiolucent areas than from teeth without radiolucent areas (236.8 +/- 521.3 pg/microliter vs. 14.9 +/- 23.1 pg/microliter, respectively). The elevated PE-PGE2 levels were associated with the presence of clinical symptoms that reflected an acute inflammation in the periapical lesion. In contrast, a significantly negative association of decreased PE-PGE2 levels with increasing size of radiolucent areas was demonstrated. These results suggested that PGE2 was produced locally in periapical lesions and that the PGE2 concentration in periapical exudate could reflect the state of the disease activity in periapical periodontitis.     

Peer approaches for increasing HIV awareness on a college campus

PURPOSE: To compare the accuracy of clinical examination performed with bitewing radiographs or clinical examination using tooth separation to identify carious lesion activity. MATERIALS AND METHODS: 320 surfaces from 40 bitewing radiographs were examined for approximal caries on the maxillary and mandibular primary molars of 20 patients 3-10 years old. The patients were divided into three groups: (1) Absence of the permanent first molar; (2) Partial eruption of the permanent first molar; and (3) Full eruption of the permanent first molar. Two examiners evaluated the radiographs using a megascope, a magnifying glass (x2), and an amplifying image screen. Approximal radiolucencies were identified on 72 surfaces. Following the radiographic examinations, the two examiners performed conventional clinical inspection using a No. 4 dental mirror, a No. 5 dental explorer, and an air-water syringe, with artificial light and relative isolation. The separation method was performed with elastic bands, which were removed after 24 hours, and the clinical examination conducted as in the non-separation group. RESULTS: The correlation between the extension of interproximal radiolucent lesions in primary dentition and their clinical diagnoses following separation of the teeth, was similar to findings on literature evaluating the permanent dentition. On radiographic findings for enamel lesions, white spots predominated both in the inner (100%) and in the outer (94%) half of enamel upon clinical examination with separation of teeth. For radiolucent lesions in dentin, on the other hand, cavities predominated over white spot lesions (84%). In Groups 1 and 2 (young primary), white spots occurred in cases where the radiolucent lesions reached the dentin (15% and 25%), similar to findings for young permanent teeth. Clinical diagnosis performed with the mechanical separation of teeth cannot be considered conclusive for the primary dentition.     

Aspects of masticatory form and function in common tree shrews, Tupaia glis

Tree shrews have relatively primitive tribosphenic molars that are apparently similar to those of basal eutherians; thus, these animals have been used as a model to describe mastication in early mammals. In this study the gross morphology of the bony skull, joints, dentition, and muscles of mastication are related to potential jaw movements and cuspal relationships. Potential for complex mandibular movements is indicated by a mobile mandibular symphysis, shallow mandibular fossa that is large compared to its resident condyle, and relatively loose temporomandibular joint ligaments. Abrasive tooth wear is noticeable, and is most marked at the first molars and buccal aspects of the upper cheek teeth distal to P2. Muscle morphology is basically similar to that previously described for Tupaia minor and Ptilocercus lowii. However, in T. glis, an intraorbital part of deep temporalis has the potential for inducing lingual translation of its dentary, and the large medial pterygoid has extended its origin anteriorly to the floor of the orbit, which would enhance protrusion. The importance of the tongue and hyoid muscles during mastication is suggested by broadly expanded anterior bellies of digastrics, which may assist mylohyoids in tensing the floor of the mouth during forceful tongue actions, and by preliminary electromyography, which suggests that masticatory muscles alone cannot fully account for jaw movements in this species.     

Appendiceal ultrasonography performed by nonradiologists: does it help in the diagnostic process?

OBJECTIVE: In this study, the effects of pulsed Nd:YAG laser irradiation during root canal treatment of infected teeth were investigated histopathologically in dogs. SUMMARY BACKGROUND DATA: Effects of Nd:YAG laser on infected root canal treatment have not been reported in vivo. METHODS: One hundred thirty-five teeth with a single root, including incisors and premolars, in 15 healthy adult beagle-strain dogs were used in this study. After inducing infection in the teeth, each root canal was shaped with at least a # 40 K-file, then the canal was irradiated using the following parameters: 1 W, 30 pps for 1 and 2 sec; 2 W, 30 pps for 1 and 2 sec. Efficacy of debris removal and evaporation on the root canal walls at 2 weeks, and the degree of inflammation of the periapical region at 2, 4, and 8 weeks after laser irradiation were examined histopathologically by light microscopy. RESULTS: Effective debris removal was observed in all cases of the laser-treated groups. No evaporation was observed except at the conditions of 2 W for 2 sec. Inflammation of periapical region in the laser-treated groups was similar in the control group at 2 weeks, but was significantly less than that in the control group at 8 weeks (p < 0.05). CONCLUSION: These results suggest that pulsed Nd:YAG laser is useful for one-visit root canal treatment of infected teeth in dogs, if appropriate parameters are selected, and this is a potential therapy for human apical lesions of teeth.     

Effect of zinc supplementation on cell-mediated immunity and lymphocyte subsets in preschool children

The pattern and distribution of periodontitis were investigated in 162 randomly selected dogs available for necropsy in veterinary practice. There were 82 males and 80 females of 50 different breeds (150 dogs were pure-bred and 12 were mongrels, aged between 7 months and 14 yr. Presence of periodontitis was determined by assessment of alveolar bone loss on radiographs of the skulls and jaws. Periodontitis occurred frequently with increasing age, although the prevalence varied markedly among and within different breeds. Of the breeds most represented in the sample, periodontitis was most frequently seen in poodles and dachshunds but was rarely recognized in German shepherd dogs. Regardless of age, the vast majority of the dogs displayed either one or both of two different radiographic patterns of alveolar bone loss. One pattern was characterized by slight, horizontal alveolar bone loss involving interradicular and interdental areas. The other pattern was one of predominantly crater-like, or narrow, vertical bone defects which, when advanced, often extended around a single root or tooth to surround the root apices. The two types of patterns did not seem to be breed-dependent. The posterior maxillary and mandibular premolars and molars were the most frequently affected teeth. Alveolar bone loss was most severe in the maxilla, while corresponding bone loss in the mandible was more often related to increasing age.     

Inflammatory myofibroblastic tumour of the spinal cord: case report and review of the literature

Inflammatory myofibroblastic tumours (IMT), also called inflammatory pseudotumours, nodular lymphoid hyperplasia, plasma-cell granuloma and fibrous xanthoma, are rare soft-tissue lesions characterised by inflammatory cells and a fibrous stroma. Clinically and radiologically, they may look like malignant tumours. They rarely affect the central nervous system and are very rare in the spinal cord. We report an IMT of the spinal cord in a 22-year-old woman presenting with spinal cord compression and a cauda equina syndrome. MRI showed a lesion at T9 with extramedullary and intramedullary components giving low signal on T2-weighted images and enhancing homogeneously. Pial lesions on the lumbar enlargement and thoracic spinal were present 11 months after surgery, when the lesion recurred. We present the radiological, operative and pathological findings and review the literature.