Associations among Periodontitis, Calcified Carotid Artery Atheromas, and Risk of Myocardial Infarction.

Cardiovascular disease is a common cause of morbidity and premature mortality. Cardiovascular disease can be prevented when risk factors are identified early. Calcified carotid artery atheromas (CCAAs), detected in panoramic radiographs, and periodontitis have both been associated with increased risk of cardiovascular disease. This case-control study aimed to 1) investigate associations between periodontitis and CCAA detected in panoramic radiographs and 2) determine the risk of future myocardial infarctions due to CCAA combined with periodontitis. We evaluated 1,482 participants (738 cases and 744 controls) with periodontitis and CCAAs recruited from the PAROKRANK study (Periodontitis and Its Relation to Coronary Artery Disease). Participants were examined with panoramic radiographs, including the carotid regions. Associations between myocardial infarction and periodontitis combined with CCAA were evaluated in 696 cases and 696 age-, sex-, and residential area-matched controls. Periodontitis was evaluated radiographically (as degree of bone loss) and with a clinical periodontal disease index score (from clinical and radiographic assessments). We found associations between CCAA and clinical periodontal disease index score among cases (odds ratio [OR], 1.51; 95% CI, 1.09 to 2.10; P = 0.02) and controls (OR, 1.70; 95% CI, 1.22 to 2.38; P < 0.01), although not between CCAA and the degree of bone loss. In a multivariable model, myocardial infarction was associated with CCAA combined with periodontitis, as assessed by degree of bone loss (OR, 1.75; 95% CI, 1.11 to 2.74; P = 0.01). When the cohort was stratified by sex, only men showed a significant association between myocardial infarction and CCAA combined with periodontitis. Participants with clinically diagnosed periodontitis exhibited CCAA in panoramic radiographs more often than those without periodontitis, irrespective of the presence of a recent myocardial infarction. Participants with combined periodontitis and CCAA had a higher risk of having had myocardial infarction as compared with participants with either condition alone. These findings implied that patients in dental care might benefit from dentists assessing panoramic radiographs for CCAA-particularly, patients with periodontitis who have not received any preventive measures for cardiovascular disease.

The use of panoramic images for identification of edentulous persons.

The aim of this study was to determine if edentulous persons could be identified using panoramic images by: I) investigating the possibility of matching two panoramic radiographs of the same person obtained on two different occasions, II) determining what anatomical features are used as the base for matching, III) investigating if oral and maxillofacial radiologists (OMR) and dentists who were not oral and maxillofacial radiologists (NOMR) differed in their ability to match the images, and IV) determining if the time elapsed between the images affected the results or the confidence of the match. Panoramic image pairs from 19 patients obtained on two different occasions were included, plus 10 images from other edentulous patients. The time elapsed between the image pairs varied between 4 months and 6 years. Four OMR and four NOMR were asked to match the image pairs depicting the same patient. The participants marked each match as "certain", "likely", or "possible" and what anatomical structure they used for matching. The OMR group correctly matched 100% of the images and the NOMR group correctly matched 96%. The anatomy of the mandible was most often used for matching. The OMR group was more certain in their decisions than the NOMR group. The time elapsed between the examinations did not affect the result. In conclusion, panoramic images can be used to identify edentulous patients. Both OMR and NOMR could identify edentulous individuals when only panoramic radiographic images were available and the OMR were especially confident in the identification process.

The use of intraoral radiographs for identification of edentulous patients rehabilitated with implants.

The aims of this study were; i) to determine the accuracy by which two intra-oral radiographic examinations performed on patients with edentulous mandibles treated with dental implants can be matched. ii) to determine whether prosthodontic supra-construction is important for matching. iii) to investigate whether there is a difference between oral and maxilla-facial radiologists (OMR) and dental practitioners, not specialized in oral and maxillofacial radiology (NOMR), regarding their ability to match. The specific features of the radiographs used by the operators to acquire a match were also investigated. Intra-oral radiographic examinations from 59 patients were utilized. Radiographic examinations from 47 patients carried out at placement of the supra-construction and at subsequent follow-up examinations were used as "ante-mortem" and "post-mortem" records respectively. Examinations from 12 patients were added to the "post-mortem" records without "ante-mortem" records being available. The study was divided into two parts. In Part One all "ante"- and "post-mortem" records had the supra-construction masked and in Part Two it was visible. Seven dentists (4 OMR, 3 NOMR) were instructed to specify on what basis each matching was made on the confidence of a three-graded scale OMR had 93.2 % and 98.5 % accuracy in Parts One and Two respectively. NOMR had 63.8 % and 87.9 %. Bone anatomy was the most commonly used feature by OMR to obtain a match. For NOMR it was the appearance of the fixtures. OMR reported higher confidence in their ability to match the examinations. This study indicates that OMR could be a valuable resource in cases of identification where dental implants are a feature of the post-mortem dental records.

Visual-spatial ability and interpretation of three-dimensional information in radiographs.

OBJECTIVES: To investigate whether skill in the interpretation of three-dimensional (3D) information in radiographs utilizing the parallax phenomenon is associated with visual-spatial ability and whether development of this skill is related to visual-spatial ability. METHODS: Eighty-six individuals with a median age of 25 years participated in the study. It was organized into three parts: (1) assessment before training, (2) training in object depth localization utilizing parallax and (3) assessment after training. Before training, visual-spatial ability was assessed with a mental rotation test, MRT-A; skill in interpreting 3D information was assessed with two specifically designed proficiency tests: a radiography test, which assessed the ability to interpret 3D information in radiographs utilizing motion parallax and a principle test which assessed understanding of the principles of motion parallax. After training, skill in interpreting 3D information was reassessed. Improvement was defined as the difference between test scores after training and before training. Multiple linear regression was used to analyse the effect of student and training characteristics on proficiency test results and improvement. RESULTS: Radiography test results after training and improvement of radiography test results were significantly associated with MRT-A scores (P<0.001 and P=0.020, respectively). Principle test results were high before training and did not improve after training. The test results were associated with MRT-A both before (P=0.009) and after training (P=0.003). CONCLUSIONS: Understanding of the parallax phenomenon is associated with visual-spatial ability. Development of the skill to interpret 3D information in radiographs utilizing parallax is facilitated for individuals with high visual-spatial ability.

Confirmed primary HHV-6 infection in children with suspected encephalitis.

HHV-6 infection has been associated with neurological symptoms in children. Two variants of human herpes virus 6, HHV-6A and HHV-6B, have been identified. Their role in neurological infections is poorly understood. We studied 53 children with suspected encephalitis for HHV-6A (strain GS) and HHV-6B (strain Z29) antibodies using an indirect immunofluorescence test. Primary infection was separated from past infection by an IgG-avidity test. The identified primary infections were studied for HHV-6 specific DNA by PCR. Forty-one children of 53 had IgG antibodies to HHV-6. Six children had low avidity of HHV-6 IgG antibodies indicating acute primary infection; four to type A, one to B, and one to both types. By serology, HHV-6 viral etiology was suggested in 6/53 (11.3%) of cases. One of the six patients with primary infection had HHV-6 DNA in serum and two in CSF. The children with primary HHV-6 infection were significantly younger than the whole series, 2.3 years vs. 6.4 years. We conclude that primary HHV-6 infection appears to be an important associated or causative agent in neurological infections of young children, and it can be confirmed from a single serum specimen using the IgG-avidity test.

The use of dental radiographs for identification of children with unrestored dentitions.

The success of dental identification is often dependent on the extent of previous dental care and the location of detailed dental records. However, several factors limit available comparable data among children. There are often no clinical indications for dental radiography before the age of five and many children and adolescents have no restorative care. This reduces the amount of individualizing information suitable for comparative identification. The aim of this study was to investigate matching of dental x-rays from children without fillings at different ages, and to see if radiographic expertise facilitated radiographic comparison. Five general dental practitioners (GDP) and five oral and maxillofacial radiologists (OMR) attempted to match bitewing examinations from 30 children. The results showed that dentists are likely to match bitewing radiographs in these conditions. This likelihood is further enhanced when oral and maxillofacial radiologists compare images. This suggests that manual comparison of bitewings from children allow sufficient concordant visible points for identification to occur.

Co-purification of soluble membrane cofactor protein (CD46) and human herpesvirus 6 variant A genome in serum from multiple sclerosis patients.

The association of human herpesvirus 6 (HHV-6) and multiple sclerosis (MS) has been supported by several immunological and molecular studies. Recently, membrane cofactor protein (CD46) has been identified as the cellular receptor for the A and B variants of HHV-6. Elevated levels of soluble CD46 (sCD46) have been reported in the serum and CSF of MS patients. The aim of this study was to investigate a possible correlation between elevated levels of soluble CD46 and the presence of serum HHV-6 DNA in MS patients. An immunoaffinity column comprised of immobilized monoclonal antibodies to CD46 was developed to isolate sCD46 from cell free body fluids of MS patients and controls. After immunoaffinity purification, DNA was extracted from anti-CD46 column eluates and subjected to PCR amplification. Of the 42 MS samples tested, 4 serum samples were HHV-6 positive, 3 of which were typed as HHV-6A. The co-purification of sCD46 and HHV-6 DNA from MS sera indicates that HHV-6 is tightly connected to its receptor, CD46, in the serum of MS patients.

10-year follow-up of onlay bone grafts and implants in severely resorbed maxillae.

Thirty patients with extremely resorbed maxillae had reconstructive bone grafts from the ala iliaca and endosseous implants in a one-stage procedure. The first ten patients constituted a development group and the following 20 patients a routine group. The marginal bone level and implants success rate was evaluated in a prospective long-term follow-up for a minimum of 10 years (10-13 years). Clinical and radiographic examinations were performed at 6 months and then annually up to 5 years. The final examinations were performed at the 10-year follow-up. The bridges were removed at every clinical examination. Marginal bone loss was seen up to the 3-year examination, where it averaged 4.6 mm in the routine group. Between the 3- and 10-year follow-up no significant change was registered. The initial bone loss was probably due to the design of the 3.6 mm conical unthreaded marginal part of the implant. The implant success rate was 83.1% in the routine group. Failures mostly occurred during the first 2 years (14 out of 20). A substantial amount of bone can be gained in patients with extremely resorbed maxillae, when treated with bone graft according to the procedure described in this study.

Virtual reality for simulation of radiographic projections: validation of projection geometry.

OBJECTIVE: To develop a software for virtual reality (VR) simulation of X-ray images based on perspective projections through a patient model derived from data from a CT examination and to evaluate the accuracy in the projection geometry obtained by the software. METHODS: A VR software was developed on a personal computer, with models of a patient, an X-ray machine and a detector. The model of the patient was derived from data from a CT examination of a dry skull. Simulated radiographic images of the patient model could be rendered as perspective projections based on the relative positions between the models. The projection geometry of the software was validated by developing an artificial CT data set containing high attenuation points as objects to be imaged. The accuracy in projection geometry was evaluated in a systematic way. The distances between two dots, representing the projected test points in the simulated radiographic images, were measured. They were compared with theoretical calculations of the corresponding distances using traditional mathematical tools. RESULTS: The difference between the simulated and calculated projected distances never exceeded 0.5 mm. The error in simulated projected distances was in most cases within 1%. No systematic errors were revealed. CONCLUSION: The software, developed for personal computers, can produce simulated X-ray images with high geometric accuracy based on perspective projections through a CT data set. The software can be used for simulation of radiographic examinations.

Bone graft remodelling and implant success rate in the treatment of the severely resorbed maxilla: a 5-year longitudinal study.

A total of 30 patients, 10 in a developmental group and 20 in a routine group, with extremely resorbed maxillae were treated with bone grafting from the hip and implant placement in a one-stage procedure. All patients were followed for a minimum of 5 years and were examined regarding the long-term success rate of the implants and marginal bone level. The implant success rate was 74.6% for the whole patient group and 85.8% for the routine group, after 5 years. The marginal bone along the implant surface decreased continuously, up to 3 years and thereafter the bone level stabilized. In the routine group, changes in bone graft dimensions over time were also evaluated by computerized tomography. The mean height of the bone graft postoperatively at all implant sites was 8.3 mm. The total mean bone height, including bone graft and residual alveolar crest, was 12.4 mm. After 5 years the total bone height had decreased to a mean of 10 mm. The mean width of the bone graft was 12 mm postoperatively and 8.7 mm at the 5-year examination. A substantial amount of bone can be gained in patients with extremely resorbed maxillae, when treated with bone graft according to the procedure described in this study.

Atherosclerosis, and Newton, Poiseuille, Reynolds and Prandtl.

Atherosclerotic fibrous plaques typically manifest at inlets of branches and in expansions etc. of large elastic arteries. A resting man with a surface area of 1.78 m(2)produces energy at a rate of 100 W (86 kcal/h), mainly by core organs. Core blood heat is convected to arterial walls and conducted through tissues to be lost from body surfaces. High losses are compensated by an increase in the basal metabolic rate, and vice versa. In laminar flow, the fluid-tube wall heat transfer coefficient is higher close to tube inlets than downstream. Unless lipoprotein etc. suspects are exceptions from the rule that an increase in temperature speeds up chemical reactions, transfer of core heat may contribute to plaque localization. In laminar flow, heat transfer is little influenced by viscosity. Hence correlations between blood viscosity and cardiovascular disease (CVD) may reside in other mechanisms: viscosity limits flow relatively more in small than in large arteries, and viscosity-linked thixotropic properties of blood increase resistance to flow in capillaries and postcapillary venules (exchange vessels). The exchange vessels of large arteries belong to the vasa vasorum, in which reduction of flow induces diffuse parent artery wall changes found also in plaques. Correlations between blood viscosity and peripheral symptoms of CVD may be explained by reduced flow in vascular loops of symptomatic organs, even if maximum flow is limited by upstream plaques. Physiological differences in the type of blood flow and in blood-tissue exchange between vessels of different size may shed light on apparent paradoxes in research on CVD.

Swelling of synovial joints - An anatomical, physiological and energy metabolical approach.

The direction and part of the rate of fluid filtration between synovial capillary (subscript capill) plasma and joint (subscript j) cavity fluid depends on the hydrostatic (P(capill)-P(j)) and colloid osmotic (COP(plasma)-COP(j)) pressure differences and on the osmotic efficiency (coefficient sigma) of 'colloids' across the barrier between plasma and synovial fluid. The rate of filtration also depends on capillary endothelial hydraulic conductance (L(p)) and surface area (A). Synovial fluid protein is removed by lymphatics, or split to be resorbed or used up by cells. Physiologists put together as equations the above, as well as other terms, all of these influenced by numerous factors. The equations offer a frame for a multifactorial approach to diseases associated with joint swelling and suggest, among others, that in the presence of weak generalized exsudation, synovial joints are loci minores resistentiae to swelling. The influence of joint cartilage energy demands on synovial blood flow may have been underrated. There are many accepted clinical, laboratory and morphological findings that fit this physiological frame that merits further clinical research.

Validity of computed tomography in imaging thin walls of the temporal bone.

OBJECTIVES: To evaluate the validity of computed tomography (CT) for reproduction of the bone margins of the temporomandibular joint (TMJ). METHODS: Seven TMJ specimens were examined with a CT and then cryosectioned. The bone separating the TMJ from the middle cranial fossa, middle ear and external auditory canal was measured as the full width at half maximum (FWHM). Measurements were compared with the true thickness of the bone wall. RESULTS: There was good agreement when the bone walls were thicker than 1 mm: accuracy was influenced only by the angle of the bone wall to the scanning plane. Conversely, bone walls thinner than 1 mm were reproduced with a magnification that increased with decreasing bone thickness. The difference increased further as the inclination of the bone wall became greater. CONCLUSION: Measurements performed at FWHM are reliable within +/- 10% for bone walls more than approximately 1 mm thick which form an angle of less than 35 degrees to the perpendicular of the scanning plane. For bone walls thinner than 1 mm and for those thicker than 1 mm with an inclination exceeding approximately 35 degrees, partial volume effects result in a progressively increasing magnification of bone thickness.

Bone demarcation of the temporomandibular joint. Validity of clinical assessment of bone thickness by means of CT.

PURPOSE: To study the CT depiction of bone demarcations in the temporomandibular joint, using conventional window level and window width; and to evaluate observer performance in estimating bone thickness in these images. MATERIAL AND METHODS: Seven joint specimens were imaged by CT and then cryosectioned. The measurements of bone wall thickness in the images were compared to the true bone thickness at each cutting level. In addition, 4 experienced radiologists estimated the thickness of the bone walls in the images. RESULTS: The relative difference between the CT reproduction and the true bone thickness was small for bone walls thicker than 2 mm. This difference increased with the decrease in bone thickness and the increase in the inclination of the bone wall from the perpendicular to the image plane. Bone walls thinner than 1 mm were reproduced as considerably thicker than their true thickness. This resulted in a clinical overestimation of bone thickness. CONCLUSION: Both the CT representation and the interpretation of bone demarcation in the temporomandibular joint may constitute a problem. Partial volume averaging effects can result in an overestimation of bone dimensions amounting to 200% for thin bones. The central white zone in images of thin bone walls obtained with the parameters described here could serve as an indicator that could help to reduce the risk of overestimating bone thickness.

Joint fluid hydrostatic pressures that empty synovial capillaries of red cells have a wide range and correlate with pressures emptying arterioles.

OBJECTIVE: To study if, as predicted by calculations based on 3 Starling pressures, the fourth one, capillary pressure, may increase enough to contribute to joint swelling. METHODS: At magnifying arthroscopy, red cells mostly flow separated from each other in capillaries and precapillary vessels (arterioles). These are emptied of erythrocytes at intraarticular injection of saline to "tamponade" pressures. Patients sent for arthroscopy of the knee joint for mechanical or other lesions, or "internal derangement" (n = 30) or osteoarthritis (n = 26) were studied. RESULTS: The range of capillary (including postcapillary venular) tamponade pressure was 9-70 mm Hg. It correlated (r = 0.536, p < 0.001) with arteriolar tamponade pressure (range 20-100 mm Hg). CONCLUSION: If intravascular hydrostatic pressure is the main determinant of tamponade pressure, then increase of capillary pressure, possibly due to arteriolar dilatation induced precapillary pressure increase, may be a key mechanism in enhanced formation of synovial fluid.