3D finite element model and cervical lesion formation in normal occlusion and in malocclusion.

The aim of this study was to develop a three-dimensional (3D) finite element model (FEM) of the first maxillary premolar in order to compare the stress profiles in the buccal and palatal cervical regions. The 3D geometry of the tooth was reconstructed, the solid model was transferred into a finite element program where a 3D mesh was created, and the stress distribution analysis was performed. Two typical cases have been considered: the tooth under normal occlusion (case I) and the tooth under malocclusion (case II). In case I, larger compressive stresses were found in the cervical enamel and dentine. Tensile stresses were found in the fissure system, adjacent area, and at the vestibular surface of the buccal cusp. The peak values for the principal stress ranged from -259 to +2.25 MPa in the cervical areas. In the case II, larger compressive stresses were found in the palato-cervical enamel and dentine. Tensile stresses were found inside the enamel in the fissure system, adjacent area, at the vestibular surface of the buccal cusp, and in the bucco-cervical enamel. The peak values for the principal stress ranged from -501.947 MPa in palatal region to +82.4 MPa in the buccal region This study implies a role of occlusal forces in development of non-carious lesions. In the case of malocclusion, tensile stresses generated on the cervical areas were higher compared with the stresses generated in the case of normal occlusion and it is probably capable of producing non-carious cervical lesion.

Analysis of occlusal contacts in different types of prosthodontic appliances, Eichner classifications, presence RCP-ICP slide and the type of occlusion.

The aim of the study was to determine the number and the type of the occlusal contacts (strong, weak) with respect to the type of the prosthodontic appliance (fixed, removable, combined fixed-removable) and with respect to the Eichner classification in patients with their appliances being in a good function for a long time. The aim of the study was also to determine the number and the type of the occlusal contacts (strong, weak) with respect to the type of occlusion (canine guided, group function or balanced) and the presence of the RCP-ICP slide. A total of 440 patients with different types of prosthodontic appliances were examined for the antagonistic occlusal contacts using occlusal strips of 11 microm and 50 microm. The average number of occlusal contacts was 10.5 for the upper and 10.46 for the lower posterior teeth, approximately 5 on each side of the tooth arch. The results of the study suggest that the biggest number of occlusal contacts were recorded for the small span fixed appliances (2 on average), the greater span fixed and fixed-removable prosthodontic appliances exhibited 1.6 occlusal contacts, and the removable complete denture exhibited 1.2 contact per the tooth in the posterior region. The number of the hard occlusal contacts was significantly greater in fixed and fixed-removable prosthodontic appliances in comparison with the complete dentures (p < 0.05), while there was no significant difference between the prosthodontic appliances for the weak occlusal contacts (p > 0.05). The overall number of the occlusal contacts, as well as the number of the hard occlusal contacts was significantly greater in the Eichner class I cases (p < 0.05) in comparison with the Eichner classes II and III. The number of the weak occlusal contacts showed no significant differences with respect to the Eichner classification (p > 0.05). There was no significant difference in the number of occlusal contacts between the appliances with RCP-ICP slide and where ICP and RCP corresponded (p > 0.05).

Tooth loss and the condition of the prosthodontic appliances in a group of elderly home residents.

The study assessed the number of missing teeth, the state of the existing prosthodontic appliances and the need for their replacement. Dental status and anamnesis were taken on a group of 120 elderly home residents by trained examiners. Prosthodontic appliances were evaluated according to the Karlsson's index for the crowns and bridges, and according to the modified Nevalainen et al. index for the evaluation of the complete dentures, as well as the need for prosthetic treatment. The most persistent teeth in both jaws were lower canines, while the most commonly missing teeth were lower first molars. On average, the crowns were older and in poorer condition than the bridges. Lower complete dentures had better stability but were also less retentive in comparison with the upper complete dentures. More than 82% of the subjects were in need of either fixed, removable or combined prosthodontic treatment. The high prevalence of needs for prosthodontic treatment pointed to the requirement for frequent dental check ups within elderly home residents in order to better identify and meet their dental needs.

Introduction of protein or DNA delivered via recombinant Salmonella typhimurium into the major histocompatibility complex class I presentation pathway of macrophages.

Recombinant (r) Salmonella typhimurium aroA strains which display the hen egg ovalbumin OVA(257-264) peptide SIINFEKL in secreted form were constructed. In addition, attenuated rS. typhimurium pcDNA-OVA constructs harbouring a eukaryotic expression plasmid encoding complete OVA were used to introduce the immunodominant OVA(257-264) epitope into the major histocompatibility complex (MHC) class I presentation pathway. Both modes of antigen delivery (DNA and protein) by Salmonella vaccine carriers stimulated OVA(257-264)-specific CD8 T-cell hybridomas. An in vitro infection system was established that allowed both rSalmonella carrier devices to facilitate MHC class I delivery of OVA(257-264) by coexpression of listeriolysin (Hly) or by coinfection with rS. typhimurium Hlys (Hess J., Gentschev I., Miko D., Welzel M., Ladel C., Goebel W., Kaufmann S.H.E., Proc. Natl. Acad. Sci. USA 93 (1996) 1458-1463). Coexpression of Hly and coinfection with rS. typhimurium Hlys slightly improved MHC class I processing of OVA. Our data provide further evidence for the feasibility of attenuated, Hly-expressing rS. typhimurium carriers secreting heterologous antigens or harbouring heterologous DNA as effective vaccines for stimulating CD8 T cells in addition to CD4 T cells.

Location of the hinge axis and the kinematic centre in asymptomatic and clicking temporomandibular joints.

The study aimed to compare the locations of the hinge axis and the kinematic centre in both clicking and non-clicking TMJs. The six degrees of freedom optoelectronic jaw movement recording system OKAS-3D was used to record open/close movements in 10 asymptomatic subjects and 30 subjects with a clicking joint. Movement paths of the hinge axis and the kinematic axis were calculated. A t-test was used in the analysis of the locations of the two condylar movement reference points. Variances between the values of the hinge and the kinematic axes were compared with the F-test. Locations of the hinge axis and the kinematic centre on the average did not differ significantly for the asymptomatic subjects at the group level (P>0. 05), while individually the locations differed 4.96 mm on the average. The difference between the hinge axis and the kinematic axis was significant for the group of subjects with clicking joints (P<0.01), with the average individual level difference of 9 mm. Variances differed significantly between the coordinates of the hinge and the kinematic axes between the two groups of subjects (P<0. 01). The study shows the importance of the choice of a condylar movement reference point for the study of condylar movements and suggests the use of the kinematic centre in such studies.

Evaluation of the precision of dimensional measurements of the mandible on panoramic radiographs.

The purpose of this study was to evaluate the precision of dimensional measurements of the mandible on orthopantomographic images and thus to evaluate their dimensional reliability. Different distances denoted by metal markers were measured on 25 dry mandibles. The same mandibles were then positioned in an orthopantomographic machine, and radiographic images of them were made. Measurements of the same distances were made on the panoramic images and then compared with the results of the measurements on the dry mandibles. All results were statistically analyzed. The results showed significant difference between the magnification factor listed by the manufacturer and calculated magnification factors, the latter being closer to 1.00. The study also showed that linear measurements made on only one side of the panoramic image of a mandible were very close to the actual dimensions of the dry mandible, whereas measurements that extended across the midline of the mandible were greatly enlarged because of large magnification factors; therefore, such measurements should not be made.

Mycobacterium bovis Bacille Calmette-Guérin strains secreting listeriolysin of Listeria monocytogenes.

Recombinant (r) Mycobacterium bovis strains were constructed that secrete biologically active listeriolysin (Hly) fusion protein of Listeria monocytogenes. The r-BCG strains pAT261:Hly or pMV306:Hly expressed plasmid multicopies or chromosomal single copies of the hly gene, respectively. Human and murine macrophage-like cell lines were infected with r-BCG pAT261:Hly and pMV306:Hly strains. Interestingly, intracellular persistence of both r-BCG strains was reduced in macrophages as compared with the parental BCG strain. By immunogold labeling Hly was detected in membrane structures and within the phagosomal space of macrophages. In addition, Hly was localized within cytoplasmic vacuoles outside the mycobacteria-containing phagosome of host cells infected with r-BCG pAT261:Hly or r-BCG pMV306:Hly. Hly fusions consistently colocalized with a lysosome-associated membrane glycoprotein, suggesting that membrane-attack conformation of Hly was not altered. Although r-BCG pAT261:Hly and r-BCG pMV306:Hly microorganims apparently did not egress into the cytoplasmic compartment of host cells, they both improved major histocompatibility complex class I presentation of cophagocytosed soluble protein as compared with wild-type BCG microbes. These data suggest that Hly secretion endows BCG with an improved capacity to stimulate CD8 T cells. Because CD8 T cells play a major role in protection against tuberculosis such Hly secreting r-BCG constructs are antituberculosis vaccine candidates.

Delivery of antigen-encoding plasmid DNA into the cytosol of macrophages by attenuated suicide Listeria monocytogenes.

Eukaryotic expression vectors can be delivered to macrophages using attenuated self-destructing Listeria monocytogenes. L. monocytogenes cells are preferentially lysed in the host cell macrophage cytosol by the production of a PactA-dependent Listeria-specific phage lysin. Efficient expression of the cloned reporter genes by the macrophages and subsequent antigen presentation were achieved after the delivery of eukaryotic expression vectors by the attenuated suicide L. monocytogenes strain. After delivery by L. monocytogenes plasmid DNAs were found to integrate into the macrophage cell's genome at a frequency of about 10(-7).

Dimensional measurements on the human dental panoramic radiographs.

The objective of this study was to evaluate the precision of the horizontal and vertical linear dimensional measurements on orthopantomographic images. Different horizontal and vertical distances denoted by metal markers were measured on 25 dry mandibles. The same mandibles were then positioned in an orthopantomographic machine and their radiographic images were made. Measurements of the same distances were repeated on the panoramic images and compared to the results of the measurements on the dry mandibles. All results were statistically analyzed. The results showed significant difference between the magnification factor listed by the manufacturer and the calculated magnification factors, the latter being closer to 1.00. The study also showed that linear measurements made only on one side of panoramic images of mandibles were close to actual dimensions of dry mandibles, while the measurements which extended across the midline of mandibles were greatly enlarged due to large magnification factors.