Interspecific competition between Diadegma semiclausum Hellen and Diadegma mollipla (Holmgren), parasitoids of the diamondback moth, Plutella xylostella (L), feeding on a new host plant.

Interspecific competition between an introduced parasitoid species aimed at controlling a herbivorous pest species and a native parasitoid parasitising the same host may influence the success of classical biological control programmes. In Kenya, interspecific competition between an introduced and a local parasitoid on two diamondback moth populations (DBM, Plutella xylostella) was investigated on two different host plants. We tested simultaneous and delayed competition of the local parasitoid Diadegma mollipla Holmgren and its exotic congenus D. semiclausum Hellen on a newly aquired DBM host plant (snowpea) in the laboratory. Under simultaneous competition, D. mollipla produced more progeny than D. semiclausum on snowpea. A head start of D. Mollipla, of four and eight hours before its congenus was introduced, resulted in a similar number of progeny of both species. In delayed competition (time intervals of 24 h, 48 h and 72 h), progeny production was similar for both parasitoids when the time interval was 24 h, irrespective of which species parasitized first. More progeny was produced by the species which attacked first, when the time interval was greater than 24 h, although it was only significant at 72 h. Competitive abilites of both parasitoids on the new host plant differed largely between laboratory and semi-field conditions. The influence of two host plants (snowpea and cabbage) on competition was studied in the greenhouse with different host and parasitoid densities. Parasitism levels of D. semiclausum were significantly higher than those of D. mollipla, regardless of host plant, host and parasitoid densities, but progeny production of D. mollipla on snowpea was still slightly higher than on cabbage. As compared to the confinement of parasitoids and larvae to small containers, D. mollipla parasitized very few larvae in the cages. Competitive ability of the two parasitoid species tested was influenced both by the density of the searching females and by parameters related to either the host plant and/or the herbivorous hosts.

Reproducibility of jaw movements in patients with craniomandibular disorders.

It has never been investigated, if mandibular movements of patients with craniomandibular disorders (CMD) result in a lower reproducibility of dynamic functional parameters which are used for the individual articulator setting. The aim of the present study was to compare the reproducibility of electronically registered functional parameters in patients with CMD and in a control group. Dynamic functional parameters were recorded in 30 patients and 30 volunteers with a computerized ultrasound system (ARCUSdigma). The whole registration was performed three times during one session and three times at a second session 1 week later. The horizontal condylar inclination in the patient group gave a standard deviation of 2.17 degrees +/- 0.95 degrees , indicating poorer reproducibility than in the volunteer group, for which the standard deviation was 1.37 degrees +/- 0.42 degrees . The reproducibility of measurements of the Bennett angle was also poorer in the patient group than in the volunteer group, with standard deviations of 1.70 degrees +/- 0.62 degrees and 1.22 degrees +/- 0.40 degrees , respectively. The standard deviations calculated for determination of incisal inclination during laterotrusion was 3.02 degrees +/- 1.49 degrees for patients and 2.30 degrees +/- 1.17 degrees for volunteers. The standard deviations for incisal inclination during protrusion was 2.02 degrees +/- 0.95 degrees for patients and 2.06 degrees +/- 1.82 degrees for volunteers. The reproducibility of measurement of horizontal condylar inclination, Bennett angle and incisal inclination during laterotrusion therefore showed significantly lower reproducibility in the patient group than in the volunteer group (P < 0.05). The overall reproducibility of the measurements was nevertheless good in both groups, with standard deviations under 3.1 degrees , so that an individual setting of an articulator seems useful even in patients with CMD.

Host shift to peas in the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) and response of its parasitoid Diadegma mollipla (Hymenoptera: Ichneumonidae).

Host shifts in herbivorous insects are thought to sometimes provide enemy-free space on the novel host plant. A population of the diamondback moth Plutella xylostella (Linnaeus), an oligophagous pest on crucifers, recently shifted to sugar snap- and snowpeas (Pisum sativum) in Kenya, resulting in heavy damage to these crops. The impact of this host shift on the interaction with Diadegma mollipla (Holmgren), one of the most frequent parasitoid species attacking P. xylostella in this area, was investigated. Parasitism rates and development of two strains of D. mollipla, one reared from a cabbage-feeding strain of P. xylostella and the second from the new pea-feeding strain, changed based on the host-plant that P. xylostella fed upon, with both parasitoid strains more effective on the novel host plant. Parasitism by the cabbage-D. mollipla strain on P. xylostella infesting peas was four times higher than on P. xylostella infesting cabbage when a single plant species was present. However, when both crops were offered together, the level of parasitism dropped to the level seen when cabbage was offered alone. Diadegma mollipla developed on both hosts, but cabbage-D. mollipla had a longer total development time. Pupae of cabbage-feeding P. xylostella were significantly heavier than pupae of pea-feeding P. xylostella and parasitism had no influence on these differences. Diadegma mollipla preferred to parasitize the pea-feeding P. xylostella. Thus, the host shift by P. xylostella to a novel host plant did not necessarily provide enemy-free space, with the parasitoid species tested. The implications of these findings for the host-parasitoid relationship are discussed.

Comparative prospective study on splint therapy of anterior disc displacement without reduction.

A prospective randomized study was carried out to compare the therapeutic success of two different types of splint in patients with painful anterior disc displacement of the temporomandibular joint. The patients in Group I (n = 20) received stabilization splint therapy and the patients in Group II (n = 20) pivot splint therapy. Clinical investigation of the craniomandibular system was performed before and 1, 2 and 3 months after therapy and this was accompanied by subjective evaluation by the patients of their symptoms, using a validated questionnaire with visual analogue scales (VAS). There was a significant increase in maximum jaw opening and a significant reduction in subjective pain in both groups during the course of therapy (Wilcoxon test, P < 0.05). Active jaw opening increased by a mean of 8.05 mm in the group of patients treated with a stabilization splint (Group I). The comparable figure with pivot splint therapy (Group II) was 8.26 mm. The VAS scale value in Group I was reduced by 30.54 units and in Group II by 39.36 scale units. However, neither of these differences between the groups was statistically significant (Mann-WhitneyU-test, P > 0.05). It can be concluded that both types of splint provided effective therapy in patients with anterior disc displacement.

Acidic solubility of luting cements.

OBJECTIVES: Chemical disintegration of luting cements can adversely affect their long term success. The aim of the present study was to assess the susceptibility of zinc phosphate cement, glass ionomer cement and resin cement to erosion at various pH values. METHODS: Zinc phosphate and glass ionomer cement samples were eroded in 0.3% citric acid adjusted to pH 3.0, 4.0, 5.0, 6.0 and 7.0 at a temperature of 35 degrees C. A control group was stored in saline. Profilometric readings were performed after 30 min and 1h erosion time. Resin cement samples were eroded at pH 3.0 with measurements after 30 min, 6h, 24h and 7 days. A saline control group was measured after 7 days. RESULTS: Erosion of zinc phosphate cement was significantly higher at all pH values than erosion of glass ionomer cement with erosion depth increasing with decreasing citric acid pH. No erosion was seen in the control groups. The resin cement did not show any change in surface profile after the 7 day erosion period compared to the control group. Comparison to dental tissues revealed that erosion of glass ionomer cement in vitro was slightly lower than erosion of enamel and dentine. In contrast, erosion of zinc phosphate cement was much higher.

Computer-assisted milling of dental restorations using a new CAD/CAM data acquisition system.

BACKGROUND: Recent technologic innovations have created possibilities for restorative dentistry, such as computer-aided design and computer-aided manufacturing (CAD/CAM). PURPOSE: This article presents a new CAD/CAM process that has been developed for the fabrication of dental restorations. METHODS: This process uses an improved imaging technique, successfully applied in other industries. Imaging is accomplished with 2-dimensional line grids projected onto an object, which allows for a mathematical reproduction of prepared and unprepared tooth surfaces, including those that are outside the direct line of light. The relative position of the sensor to the surface of the object is controlled automatically. CONCLUSIONS: This system, which is undergoing clinical testing, allows the generation of various types of highly accurate dental restorations (inlays, onlays, crown, and fixed partial dentures) from a number of different materials. Acquired digitized data points are directly translated from the sensor to the electronic controls of the milling machine to provide various manufacturing possibilities, including copy milling and accurate reproduction of occlusal tooth surfaces in various materials.

[The problem of the reproducibility of occlusal contacts]. / Untersuchungen zur Frage der Reproduzierbarkeit okklusaler Kontakte.

To perform target orientated therapy simulators of condyle movements (CPS) have been introduced recently. It is believed to improve analysis of jaw by computer aided registration and evaluation systems (i.e. transformation of the true axis and jaw movements for use in articulators). Although the electronic evaluation systems helped to improve our understanding of the movements of the jaw, up to now the reproduction of physiological and pathological movements and their therapeutic changes have not been solved satisfactorily. The reason is sometimes miscorrection of system inherent projection errors. Additionally, numerical analysis and changes of the registered pathological movements are restricted to certain limits within the articulators for therapeutical purpose.

[Examinations of the temporal and spatial course of the reciprocal TMJ click]. / Untersuchungen zum zeitlichen und räumlichen Verlauf des reziproken Kiefergelenkknackens.

A new computerized system for jaw movement registration allows a finer diagnosis of TMJ clicks. We recorded jaw movements in patients where we detected reciprocal clicks during clinical examination. We found two different types of derangements: an anterior displacement of the disk (as described by Farrar and a posterior displacement of the disk (similar to description of Klett).

[Conservative treatment of perforated disks]. / Zur konservativen Therapie bei der Diskusperforation.

Stereognathographic recordings were taken of the mandibular movements of 11 patients who had undergone conservative treatment for unilateral disk perforation. The results showed a significant decrease in the condylar inclination angle of the affected joints. Based on these values the condylar inclinations were increased in a condyle positioning simulator (CPS). This allowed production of individually correct occlusal splints. In all cases studied this splinting therapy eliminated pain and crepitus.

[Three-dimensional dynamic imaging of TMJ movements using stereognathography]. / Dreidimensionale, dynamische Darstellung der Kiefergelenkbewegungen mit Hilfe der Stereognathographie.

Conventional imaging methods showing only one joint side are insufficient diagnostic tools for analyzing pathologic condyle paths. Although they demonstrate the effects of internal joint derangement, they fail to reveal the pathologic causes. Superior results are obtained by means of computer-assisted evaluation programs which allow simultaneous imaging of both joints in perspective.