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Mental paresthesia and orthodontic treatment.

This article reports a case of mental paresthesia during orthodontic treatment. It also discusses which cases may be at risk for developing mental paresthesia and its prevention and management.

Adult↗

Factors influencing the removal of posts.

AIM: To determine whether metal type, cement type and the use of ultrasonic vibration influence the amount of tensile force required to remove parallel-sided, prefabricated, metal posts from tooth roots. METHODOLOGY: Ninety extracted canine teeth were sectioned horizontally 1-mm coronal to the labial cemento-enamel junction and embedded in acrylic blocks. Standardized post spaces were prepared with a ParaPost no. 5 (1.25 mm) drill to 10 mm and ParaPost XP no. 5 stainless steel and titanium posts were cemented using zinc phosphate, glass ionomer or composite resin cement. Sixty posts were subjected to 16 min of ultrasonic vibration whilst 30 stainless steel posts received no vibration. The force required for post removal was determined using a universal testing machine. Results were analysed using univariate anova. RESULTS: The univariate anova revealed no statistically significant differences between the groups at the P = 0.05 level. CONCLUSIONS: In this in vitro experiment, metal type, cement type and ultrasonic vibration did not influence the force required to remove posts.

Analysis of Variance↗

Multiple dental anomalies in a young patient: a case report.

This case illustrates the management of multiple dental anomalies in a young patient, which included anomalies of number and morphology. Although individually these anomalies are not uncommon, the combination is unusual and highlights the importance of careful clinical and radiographic examination of patients with dental anomalies.

Child↗

Compound odontoma associated with an unerupted and dilacerated maxillary primary central incisor in a young patient.

The occurrence of odontoma in the primary dentition is uncommon. There are very few reports of non-eruption of a dilacerated primary tooth in the literature. A rare case of compound odontoma in association with an unerupted dilacerated maxillary primary incisor in a young patient is reported. There was also a developing supernumerary tooth in the vicinity of the odontoma. The clinical features and management of these conditions are discussed. The relevant literature is reviewed. A possible causal relationship between odontoma and dilaceration is highlighted.

Child, Preschool↗

Remaining mandibular third molars in an adult population.

Although tooth loss with age has been extensively investigated, there appears to be no literature on the relationship of age to remaining mandibular third molars. The study showed that as age increases so does the frequency of absent vertically erupted mandibular third molars. However, no correlation was found between age and loss of mandibular impacted third molars in men of 71 years of age or older. The evidence presented here suggests that impacted mandibular third molars, which have not been infected, may be more likely to remain compared with other teeth at potential risk.

Adult↗

Stress analysis of an upper central incisor restored with different posts.

The effect of different anatomic shapes and materials of posts in the stress distribution on an endodontically treated incisor was evaluated in this work. This study compared three post shapes (tapered, cylindrical and two-stage cylindrical) made of three different materials (stainless steel, titanium and carbon fibre on Bisphenol A-Glycidyl Methacrylate (Bis-GMA) matrix). Two-dimensional stress analysis was performed using the Finite Element Method. A static load of 100N was applied at 45 degrees inclination with respect to the incisor's edge. The stress concentrations did not significantly affect the region adjacent to the alveolar bone crest at the palatine portion of the tooth, regardless of the post shape or material. However, stress concentrations on the post/dentin interface on the palatine side of the tooth root presented significant variations for different post shapes and materials. Post shapes had relatively small impact on the stress concentrations while post materials introduced higher variations on them. Stainless steel posts presented the highest level of stress concentration, followed by titanium and carbon/Bis-GMA posts.

Bisphenol A-Glycidyl Methacrylate↗

[Phylogeny, form and function of canine teeth in the horse].

The canine teeth of the horse developed phylogenically from the simple, pointed, short-rooted tooth form of the leaf eating, in pairs living, Eocene horse Hyracotherium and served up to the Oligocene as a means of defense (self preservation). In the Miocene the living conditions of the Merychippus changed and they took to eating grass and adopted as a new behavior the life in a herd. The canine teeth possibly played an important role in fights for social ranking; they changed from a crown form to knife-like shape. In the Pliohippus the canine tooth usually remained in male horses and since the Pliocene, it contributed to the fights between stallions, to ensure that the offspring only came from the strongest animals (preservation of the species). Form and construction of the canine tooth are described and discussed in detail under the above mentioned phylogenic and ethologic aspects.

Animals↗

Extranodal lymphoblastic lymphoma of suspected B-cell lineage in the gingiva of a racehorse, accompanied by mandibular osteolysis.

A mass developed in the mandibular gingiva of a thoroughbred racehorse. When the horse could no longer eat unassisted, it was killed and immediately autopsied. Macroscopically, the mandible exhibited extensive osteolysis, with only a small amount of bone remaining around the tooth roots. The cut surface of the mass around the mandible consisted of neoplastic medullary tissue, in which osteogenesis was observed. The medullary tissue was composed of pleomorphic medium-sized to large cells, interlaced by collagen bundles. These cells had large, pale, round or ovoid, sometimes cleaved nuclei, with one or two prominent nucleoli. Mitoses were numerous. Electron microscopy showed that the cells in the medullary tissues were similar in shape to undifferentiated lymphocytes. Immunohistochemically, these cells were positive for B-cell associated antigen in the pre-B-cell stage. Our findings suggest that the horse had extranodal lymphoblastic lymphoma of suspected B-cell lineage, possibly originating from the lymphatic system of the gingiva. We consider that the osteolysis resulted from activation of osteoclasts by proliferation of the tumour cells.

Animals↗

[Experimental results of stepped titanium shafts for hip endoprostheses].

Among the materials which can be used for hip prostheses to be implanted without bone cement, ceramics and titanium possess the best overall properties for insuring long-term stability in the light of present knowledge. However, considered separately, the two materials are most suitable for different special requirements. Results of long-term animal experiments conducted by different working groups on functionally stressed hip and tooth-root implants made of bio-inert Al2O3 ceramic and titanium have furnished knowledge of the possibilities and limitations of the adaptation reaction of the bone tissue. The present authors investigated whether, by combining Al2O3 ceramic and titanium, a cement-free total hip replacement can be adapted to specific local stresses, taking biomechanical rules and anatomical factors into account. In recent experimental series it proved possible to limit the problems which had occurred in previous series, reported elsewhere. Positive results in dogs led to a human implant which has so far been used 15 times, with Al2O3 (FRIALIT) acetabula and heads, which have been implanted successfully for a number of years, in combination with the new stepped titanium shaft. In addition to a short review of follow-up findings thus far, the results of the experimental investigations are presented.

Animals↗

Otodental syndrome: a case report and genetic considerations.

A 5-year-old boy presented with otodental syndrome. His maxillary and mandibular incisors were within normal limits. The premolar/molar areas in all quadrants were occupied by markedly macrodontic teeth showing globular shape. The canines had a similar rounded shape. Two canines and 1 of the other abnormal teeth demonstrated areas of yellow hypoplastic enamel. Radiographs revealed that some of the abnormal teeth had bifurcated pulp chambers and pulp stones. Premolar tooth germs were absent. Audiometry demonstrated that the child had a marked bilateral sensorineural hearing loss for frequencies above 1000 Hz. No other members of the immediate family were clinically affected. The parents of the child were not aware of any similarly affected relatives. Suggestions with respect to possible genetic mechanisms and gene participation in the etiology of this syndrome are offered.

Bicuspid↗

The receptor activator of nuclear factor-kappa B ligand-mediated osteoclastogenic pathway is elevated in amelogenin-null mice.

Amelogenins, major components of developing enamel, are predominantly involved in the formation of tooth enamel. Although amelogenins are also implicated in cementogenesis, their precise spatial expression pattern and molecular role are not clearly understood. Here, we report for the first time the expression of two alternate splice forms of amelogenins, M180 and the leucine-rich amelogenin peptide (LRAP), in the periodontal region of mouse tooth roots. Lack of M180 and LRAP mRNA expression correlated with cementum defects observed in the amelogenin-null mice. The cementum defects were characterized by an increased presence of multinucleated cells, osteoclasts, and cementicles. These defects were associated with an increased expression of the receptor activator of the nuclear factor-kappa B ligand (RANKL), a critical regulator of osteoclastogenesis. These findings indicate that the amelogenin splice variants, M180 and LRAP, are critical in preventing abnormal resorption of cementum.

Alternative Splicing↗

Treatment time of traumatic dental injuries in a cohort of 16-year-olds in northern Sweden.

The aim of the present study was to account for treatment time and number of visits required for treatment of traumatic dental injuries in a cohort of 16-year-olds, born in 1975, and residing in the county of Västerbotten, Sweden, and to analyze the correlation between total treatment time and background factors. The study material comprised 1012 dental records from the Public Dental Health Service containing information on dental injuries to primary and/or permanent incisors or canines. The mean total treatment time per individual was 1.3 h, with a range of 0.1 to 27.5 h. For injuries to the primary dentition, the mean number of visits per individual was 2.2. One visit was sufficient in 21% of the trauma episodes. In the permanent dentition, each trauma episode required a mean of 3.4 visits, and 90% of the patients had to return for follow-up visits. The correlation between explanatory variables and total treatment time was described and analyzed by linear multiple regression analyses. Degree of severity and number of injured teeth were two parameters of major significance to treatment time. Treatment by a specialist had an impact on time in the permanent but not in the primary dentition. In the permanent dentition, the treatment time increased if the dental injury occurred before the age of 11 years. Treatment time was not dependent on where the clinic was located or on gender of the injured child. Different diagnoses could explain 33% of the variation in treatment time in the permanent dentition.

Adolescent↗

Assessment of dysplastic dentin in osteogenesis imperfecta and dentinogenesis imperfecta.

Two semiquantitative scoring systems, Clinical Radiographic Score (CRS) and Dysplastic Dentin Score (DDS), were introduced for analyzing degree of dysplastic manifestations in dentin. The utility of both systems was demonstrated in a large material of teeth from patients with dentinogenesis imperfecta (DI) and osteogenesis imperfecta (OI). Twenty teeth from healthy controls, 81 teeth from 40 patients with OI, and 18 teeth with DI without OI (DI type II) were examined. The degree of dysplasia was correlated with type and form of OI and type of DI. The median DDS did not differ between DI associated with OI (DI type I) and DI type II. DDS in OI patients without clinical signs of DI was above that of control teeth. Both circumpulpal and mantle dentin showed increased DDS, although circumpulpal dentin was more severely affected. The median DDS was highest for the most severe type of non-lethal OI (type III). DDS increased significantly with form (severity) of OI. A significant association between DDS and CRS was found, although diagnosis of DI in less severe cases was not possible based on radiographic or clinical signs alone. Thus, the DDS system proved valuable when the CRS system based on radiographic/clinical manifestations failed, the most significant finding being subclinical histological manifestations of DI in patients with OI but without clinical or radiographic signs of DI. These subtle dysplastic changes are most likely an expression of genetic disturbances associated with OI and should not be diagnosed as DI, but rather be termed histologic manifestations of dysplastic dentin associated with OI.

Adult↗

Erosion of the non-occlusal surfaces of sheeps' deciduous teeth.

Major erosion of the labial or lingual surfaces was seen in histological sections of deciduous teeth from three of 208 sheep from two farms. In one, the erosion extended through both the enamel and the dentine and thus exposed the pulp cavity which had developed pulpitis. In the other cases the erosion affected the cementum and dentine of the tooth root, and did not penetrate as far as the pulp cavity. Dentine proliferation occurred on the adjacent pulpal surface, however, although pulpitis was not evident.

Journal Article↗

A micromechanically-based, three-dimensional interface finite element for the modelling of the periodontal ligament.

Some ideas are presented for the implementation of an interface finite element capable to model in 3-dimensions several mechanical features of the periodontal ligament. Such an element is based on a simple 2-cable micromechanical model, able to reproduce the periodontal ligament stiffness and strength under any loading condition, including the pure torsion of a tooth. A single cable represents a sufficiently populated sample of collagen fibres, each with an initially crimped geometry; a single collagen fibre can provide a mechanical response, in tension, only when it is completely uncoiled. The macroscopic interface behaviour is obtained by statistical integrations over the uncoiled length of each collagen fibre, up to the fibre failure. Such a model can reproduce the periodontal ligament anisotropy due to the variable fibre orientation along the tooth root, its different behaviour in tension/compression/shear, its different behaviour for extrusive/intrusive loading, and so forth. Some numerical examples illustrate the potentialities of this interface element, quite simple in essence but rather complete from an engineering viewpoint.

Algorithms↗

The effect of tooth position on the image of unerupted canines on panoramic radiographs.

The purpose of this study was to evaluate whether panoramic tomograms, which are routinely used in orthodontic practice, can provide adequate information to localize an impacted canine. The effect of changes in position and inclination of an impacted canine on orthopantomograms was investigated in an experimental set-up. An upper canine was removed from a human skull and replaced in a positioning system, enabling simulated positional variations in impactions. In comparison with the image of a contralateral well-aligned canine, the length of the impacted tooth always decreased or remained unchanged, whereas the tooth width increased or remained unchanged. The angulation of the image was unaffected by varying the position of the impacted canine, but altered when the inclination of the tooth in a sagittal or frontal direction was changed. If there was any transversal shift of the impacted canine on the orthopantomogram, it was always towards the mid-sagittal plane. The curvature of the tooth increased after dorsal inclination and decreased after ventral inclination (in comparison with the contralateral well-aligned canine).

Cephalometry↗