Biomedical subjects
Publications and source records attributed to M D Russell.
This case was first reported by one of the authors in 1987, subsequent to the patient being treated using a combination of a hinge and split pin sectional denture. The same patient attended for review some 14 years later for assessment of this denture at which stage a replacement was made.
Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4-6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given.
It has been observed that teeth become lighter when they are dried. The present study was designed to quantify these changes and the time taken for tooth colour to return to normal. The colour of an upper central incisor in each of seven subjects was measured using a reflectance spectrophotometer before and after application of a rubber dam and, in another seven subjects before and after taking a polyvinylsiloxane impression. There were statistically significant changes in the L*, a* and b* values following rubber dam application and in the L* value following impression taking. The results demonstrate that teeth become brighter and less colour saturated after rubber dam application and brighter after impression taking. The original values were regained after 30 min.
OBJECTIVES: Glass-ionomer luting cements are supplied in two forms, as loose powder and liquid to be hand-mixed (HM) or pre-proportioned in a capsule to be mechanically mixed (MM). This study was to determine if post retention in pull-out tests was affected by the method of mixing the cement. METHODS: Two hundred stainless steel posts of diameter 1.75 mm were cemented within post-channels prepared in stainless steel cylinders using two hand-mixed cements FJL and KCL (Fuji I Luting Cement and Ketac-Cem Luting Cement) and two capsulated cements FJC and KCM (Fuji Cap I and Ketac-Cem Maxicap). Three groups of test specimens were prepared. In Group I each cement was mixed as recommended by the manufacturer, Group II cements were placed within a capsule and mechanically mixed and in Group III cements were removed from the capsule and mixed by hand. Specimens were stored for 1 h at 37 degrees C and 100% humidity prior to post pull-out tests at a crosshead speed of 10 mm min-1. The maximum loads at failure were subjected to Weibull analysis and Mann-Whitney tests to determine probabilities of survival and significant differences between the groups. RESULTS: Significant differences (P < 0.05) were found between all pairs of cements tested except KCM(MM) vs FJL(HM), FJL(MM) vs KCL(HM), KCL(MM), vs KCL(HM), FJC(HM) vs FJC(MM), KCL(MM) vs FJL(MM). CONCLUSIONS: The capsulated cements as supplied by the manufacturers are preferable to the equivalent hand-mixed formulations, as they give higher probabilities of survival when subjected to a given load. Both capsulated and hand-mixed formulations of Fuji had higher probabilities of survival compared to the corresponding Ketac cements. The probability of post survival can be altered by the method of mixing the cement.
This study was designed to investigate the effect of retaining coronal tooth substance on the performance of post-retained core materials, and to compare the fracture resistance of the system with an intact tooth prepared to similar dimensions. Ten teeth restored with post-retained silver amalgam, and 10 teeth restored with silver-glass cermet, all with a retained single wall of coronal tooth substance, were compared with 10 unrestored teeth prepared to similar dimensions when subjected to a shearing load. The results showed no statistically significant difference between the unrestored teeth and those restored with a silver-glass cermet. Whilst the teeth restored with silver amalgam had a significantly higher fracture resistance (P > 0.01) there was greater tendency to root fracture.
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Three case reports are presented to illustrate some problems associated with restoration of dentitions following orthodontic treatment using anterior tooth space. These include the projecting premaxilla, conversion of lateral incisors to resemble central incisors and excess residual space.
The dimensional inaccuracies that might be introduced during a wash impression technique within a heat-cured acrylic resin tray lined with a silicone resilient denture base material were investigated with the use of an electronic digitizer. Casts were poured from impressions of a machined metal die using a light- and heavy-bodied addition silicone in the soft-lined tray and compared with casts poured from impressions made in a hard-based tray and with the master die itself. The dimensions of the casts poured from the heavy-bodied impression in the soft-lined trays were significantly different from those poured from impressions in the hard-based tray when compared with the metal die. Those produced from the light-bodied material showed no statistically significant dimensional difference.
A few patients undergoing pelvic irradiation present with a prosthetic hip. The presence of this metal object often interferes with the lateral treatment fields if a four-field box irradiation technique is used. Measurements of the effect such a prosthesis may have on the dose delivered to the pelvis for beams of 60Co gamma rays and 10 MV and 25 MV X-rays, as a function of field size and depth have been made. The results show a strong variation in the dose behind the prosthesis depending on the position of the measurement, with little or no increase through the center of the head or ball, but a sharp drop either around its circumference or along the stem of the prosthesis. Measurements made with ionization chambers through the head of the prosthesis indicate an average dose decrease of approximately 2% for 25 MV X rays and average increases of approximately 2% for 10 MV X rays and 5% for 60Co. There is little variation with field size and depth except close to the prosthesis, at 25 MV. Measurements also indicate an increase in dose close to the upstream surface of the prosthesis at all energies, but in the downstream direction, only the data at 25 MV shows an increase.
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The fragmentary condition of the Krapina Neandertal remains has been offered as one line of evidence for the hypothesis that these hominids were the victims of cannibals seeking marrow and brains. Two other hypotheses regarding the causes of the framentation have been raised: a substantial portion of the breakage in the Krapina collection is attributable to excavation damage; and the rest of the breakage is attributable to sedimentary pressure and to natural rock falls that occurred during the site's prehistory. The purpose of this paper is report on tests of these three hypotheses concerning the cause of breakage in the Krapina material. Microscopic inspection of all Krapina hominid specimens showed that 23% of the material was inadvertantly broken during excavation or during quarrying that took place at the end of the last century. The morphology of the prehistoric breakage is inconsistent with the cannibalism hypothesis and supports the hypothesis that prehistoric breakage was caused by sedimentary pressure and/or roof falls.
It has often been reported that the Krapina Neandertal remains bear incised linear striations which appear to be cutmarks. Here, the plausibility of the striations as cutmarks is tested by comparing them to Mousterian butchery marks on large fauna and to cutmarks on modern human skeletons known to have been defleshed with stone tools. The anatomical location, gross appearance, and frequency of occurrence of the striations on the Krapina material do not resemble Mousterian butchery marks on reindeer. The Krapina striations do closely match authenticated cutmarks on 22 modern human skeletons defleshed with stone tools after partial decomposition, preparatory to secondary burial. Data are presented supporting the hypothesis that the striations on the Krapina Neandertal remains are consistent with postmortem processing of corpses with stone tools, probably in preparation for burial of cleaned bones.
Gross and microscopic examination of the Krapina Neanderthal dental remains reveals the presence of artificial grooves along the cemento-enamel junction of 14 teeth representing ten different individuals. The grooves display distinct morphological features including their consistent location (primarily on the mesial and/or distal root walls), their troughlike appearance, striations and/or polishing in the channel, and the ridges of reactive cementum bordering the groove. These grooves occur only on erupted, permanent teeth, and except for a single occurrence on a lower I2, all are located on mandibular or maxillary P4-M3. The morphological nature of the grooves is distinct and has been used to distinguish these grooves from root caries and other pathological or natural causes. Based on the close resemblance between artificial grooves at Krapina and those which have been attributed to toothpick use in other fossil and recent populations, we argue the Krapina Neanderthals were habitually probing the interproximal dental spaces with tools.
This study was conducted to determine the frequency of abuse and neglect among infants and preschool children seen in the emergency department of a large children's hospital. A case-finding system was introduced using a checklist (Accident-SCAN) to remind the attending nurse and physician to consider the possibility of maltreatment in the etiology of each apparent accident. Thirty-nine of 2,211 accident patients were evaluated systematically during an 18-week study period and referred to a child protection team for investigation. Twenty-eight (1.3%) were presumed to be victims of abuse or neglect. This figure differs substantially from the widely quoted estimate of 10%. The marked discrepancy between this result and previous findings suggests that either important variations exist in the rates of abuse and neglect in different populations or that the earlier figures are overestimates.
Orthodeoxia--arterial desaturation accentuated by the upright position and improved by recumbency--has been described earlier with true pulmonary vascular shunts and intracardiac shunts. This phenomenon has been described in some parenchymal lung diseases, but has not been reported with interstitial fibrosis. We describe 2 patients with predominantly basal interstitial fibrosis, disabling dyspnea, and severe hypoxemia who demonstrated this positional oxygenation change. Large or surgically correctable arteriovenous malformations (AVM), or intracardiac shunts, were not demonstrated in either patient. This finding has important implications for oxygen prescription and the explanation of positional dyspnea.
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An examination of the surface morphology of the juvenile Neandertal calvaria, Engis 2, has resulted in the discovery of several series of incised striations. The purpose of this paper is to describe and discuss these striations. A preliminary interpretation of at least some of the striations as cutmarks, made at or near the time of the child's death, is offered.