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PubMedDate not supplied

[Accuracy of apposition achieved by mandibular osteosyntheses. Stereophotogrammetric study].

The accuracy of apposition achieved by wire and plate osteosyntheses is measured with the aid of close range stereophotogrammetry in the mandibles of dead bodies. Both osteosynthesis methods are characterized by an increase in the intercondylar distance which, on the average, is about 3.3 mm greater after plate osteosynthesis and about 1.9 mm after wiring. Moreover, osteosyntheses of the base of the mandible may involve a tendency of the condyle to become caudally dislocated.

Bone Plates↗
PubMed1989

A head-model reconstruction based upon photogrammetric data from Sri Lankan adult males relevant to the design of headgear.

Due to the large variability in heads and faces in one population, the standard anthropometric dimensions of the head, measured from anatomical landmarks alone, may not suffice for the design of fitting headgear, e.g., helmets. To provide adequate data of the shapes and contours of the head to the designer, appropriate head models sculptured using comprehensive head dimensions, must be developed. This paper describes (a) a procedure of collecting comprehensive anthropometric data of the head using a photogrammetric method and (b) a simple sculpturing technique to reconstruct a head model of the user population.

Adult↗
PubMedDate not supplied

Stereophotogrammetric evaluation of the dental interproximal contacting area with amalgam restorations. Use of matrices and matrix holders. Part II. Mandibular first molar.

The authors, as a sequence of a previous research, dealt with a morphological study, by means of level curves, of the lower first molar (mesial surface). This study based on dental amalgam reconstructions used two different types of interproximal cavity preparations; one type was related to the modern or conservative preparation and the other was related to the conventional cavity preparation. Two types of matrix holders were utilized as well as copper rings. In this project the contacting interproximal areas and adjacent structures were observed stereophotogrammetrically. As in the previous study, the models used were obtained from patients with good occlusal anatomical functional conditions and mounted in a semiadjustable articulator. The procedures for restorations followed the prescribed technique for these cases as far as the selection of the material, placement of the matrices, condensation pressure, etc, were concerned. The reconstruction of the serial slices, through level curves, were able to show the location of the contacting area for each matrix used, although it is necessary to stress that the original tooth contour has never been restored.

Dental Amalgam↗
PubMed1989

[Solvent action of sodium hypochlorite on fresh and formalin fixed tissue: a biochemical approach].

Debridement of the root canal system has long been recognized as the critical phase of success in endodontic therapy. Because of the morphological complexity of most root canals, complete removal of the pulp tissue during the mechanical preparation of these root canals is often impracticable. Sodium hypochlorite is thus currently favored by most endodontists as the routine irrigant on account of its antimicrobial action and its capacity to dissolve fresh tissue together with necrotic tissues. Formocresol is another common medicament for endodontic treatment and is usually used for pulpotomy, pulpectomy and intracanal medication. Nevertheless, it was empirically believed that formocresol may interrupt the action of sodium hypochlorite in the dissolution of residual tissue. Therefore, the present study was undertaken to testify whether formocresol can substantially retard the solvent action of sodium hypochlorite by comparing the effectiveness of 5% sodium hypochlorite on fresh and formalin-fixed tissues. Connective tissue from the abdominal wall of Sprague-Dawley rats was cut into pieces weighing 0.05 g and measuring about 2 x 10 x 10 mm. A total of 20 pieces of tissue were collected and divided into two groups: 10 pieces were used immediately as the fresh-tissue group; the other 10 pieces were fixed in 10% formalin for 7 days as the fixed-tissue group. Each group was then immersed in 5 ml of 5% sodium hypochlorite for 60 seconds, and 1 ml was aspirated from each for assay. Dialysis was performed using 2 liters of double distilled water for a period of 4 hours with the water changed hourly.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Roentgen stereophotogrammetry. A method for the study of the kinematics of the skeletal system.

I have developed a roentgen stereophotogrammetric method for determination of positions of radiopaque markers in an object. The space coordinates are determined in a laboratory coordinate system, which is defined by markers in a test "cage". The markers in the test cage function as calibration points, and are roentgenographed on the same film(s) as the object. Calibration markers and object markers are exposed from two roentgen foci. The cage markers, are in their function, of two kinds, of which one (fiducial marks) is used for projective transformations of the image points to the laboratory coordinate system, while the other (control points) is used for determining the roentgen foci positions in the same coordinate system. After these calculations have been performed, the three-dimensional coordinates of object indicators are determined by crossing of lines between the roentgen foci and the transformed image points. The mathematical principles for the reconstruction of the bundles of rays from the roentgen foci at the moment of exposure are discussed in Chapter 2. Three constructions of test cages, Models 1A and 1B, and Model 2 are also discussed there. In Test Cage Model 1, the two exposures of the object are obtained on one film, but in Model 2 we expose on two films that are perpendicular to each other. The three cage models are, in turn, intended for high-accuracy determinations of lengths (Model 1A), general determinations of space coordinates, especially in larger objects (Model 1B), and high-accuracy determinations of space coordinates in medium-sized objects (Model 1B), and high-accuracy determinations of space coordinates in medium-sized objects (Model 1B). Note, that if the positions of the roentgen foci and the film are not altered, we can roentgenograph the calibration points separately on a film, and then, after removal of the test cage, roentgenograph the object on the same film. The calibration of the test cages is discussed in Chapter 3. To determine coordinates of markers in a plane is easy, if a rectangular coordinatograph is accessible, and we use the same instrument as for the measurements of the films, a Wild Autograph A8. Determination of the position in space of the plate with control points in relation to the plate with fiducial marks requires more consideration. We describe how the degrees of freedom of the plate with control points (translations in x- and y-directions, rotation angle phi about a z-axis), which are difficult to control at construction of the test cages, can be determined by specific calibration procedures.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical Phenomena↗
PubMed1978

A rapid method of measuring the palatal surface area of cleft palate infants.

A method is described for rapidly measuring the surface area of the palate by adapting a piece of soft plastic to a model of the upper jaw using a vacuum moulding technique. Tests with a hemisphere of known surface area showed the method to be consistent and to have a low degree of systematic error. When measuring models with unrepaired cleft palates, the error was found to be 2.1 per cent (compared with 3 per cent using stereophotogrammetry) but 7.1 percent when measuring intact palates. Because of the consistency of the method, the true palatal area could be calculated from the measured area by the use of a multiplying factor. These findings are described, and the application of the technique to the pretreatment assessment of cleft cases is illustrated by showing that, in a series of 30 cleft palate and 30 normal infants, a tissue deficiency of 16.8 per cent existed in the cleft subjects at birth.

Cleft Palate↗
PubMedDate not supplied

[Stereocephalometric diagnosis of penetrating unilateral cleft palate].

The issues concerning precise information useful to clarify morphological characteristics of maxillofacial disorders in children are discussed. In children with congenital facial pathology this approach allowed to single out the syndrome of opened unilateral palate cleft.

Adolescent↗
PubMed1989

An air photo analysis of an airplane crash.

Crash patterns-such as cut and damaged vegetation, gouges, debris scatter, burn areas, etc.,-and their spatial relations can be very effectively evaluated by the analysis of stereo aerial photographs. Results from the Canadian Aviation Safety Board's use of aerial photography in the Gander, Nfld., crash of Dec. 12, 1985, show that the technique can lend direct support to an investigation in several ways. It provides an overall perspective view of the regional relations of the crash patterns. It helps direct ground activities. In three-covered areas, it can help establish aircraft attitude and orientation. When combined with debris plots and attitude determinations, it can help establish the breakup sequence. And, when coupled to photogrammetric procedures, it can assign dimensional values to attitude, descent path, areas, lengths, etc.

Accidents, Aviation↗
PubMed1989

[EEG background activity in patients with dementia of the Alzheimer type--with special reference to analysis by t-statistic significance probability mapping (SPM) in Alzheimer's disease and senile dementia].

EEG power amplitude and power ratio data obtained from 15 (3 men and 12 women) patients with Alzheimer's disease (AD) and 8 (2 men and 6 women) with senile dementia of Alzheimer type (SDAT) were compared with similar data from 40 age- and sex-matched normal controls. Compared with the healthy controls, both patient groups demonstrated increased EEG background slowing, and it indicated more slower in AD than in SDAT. Moreover, both groups showed characteristic findings respectively on EEG topography and t-statistic significance probability mapping (SPM). The differences between AD and their controls indicated high slowing with reductions in alpha 2, beta 1 and beta 2 activity. The SPMs of power ratio in theta and alpha 2 bands showed most prominent significance in the right posterior-temporal region and delta and beta bands did in the frontal region. Severe AD indicated only frontal delta slowing compared to mild AD. The differences between SDAT and their controls indicated only mild slowing in delta and theta bands. The SPM of power amplitude showed occipital slowing, whereas the SPM of power ratio showed the slowing in the frontal region. Judging from both topographic findings, these were considered to denote diffuse slow tendency. In summary, these results presumed that in AD, cortical damages followed by EEG slowing with reductions of alpha 2 and beta bands originated rapidly and thereafter developed subcortical (non-specific area in thalamus) changes with frontal delta activity on SPM. On the other hand, in SDAT, diffuse cortico-subcortical damages with diffuse slowing on EEG topography were caused gradually.

Adult↗
PubMed1978

[Photogrammetric studies on the degree of swelling in the inflamed gingiva].

A photographic method was described with which changes in the swelling of the gingiva can be objectively determined. During exposure of the film, the flash device projects vertical lines on the teeth and gingiva. These lines are photographed with a compact camera which the subject holds with his teeth over a separate occlusion template. Increased swelling of the gingiva was demonstrated in eight subjects during an observation period of 21 days in which no oral hygiene was carried out.

Gingivitis↗
PubMed1978

[Experimental gingivitis--a photogrammetric comparative study].

Inflammation of the gingiva was induced in 29 subjects ranging in age from 20 to 29 by discontinuing all forms of oral hygiene for three weeks. The course of the inflammation was followed during the developmental period and the following therapy phase with the PMA index, the plaque index, and monophotogrammetry. The results tend to indicate that gingival swelling develops more gradually and recedes more rapidly after treatment has been instituted than could be assumed from the current standard periodontal indexes.

Adult↗
PubMed1979

[Comparative phorogrammetric studies on a periodontal index].

Reproducibile results are difficult to obtain with subjectively recorded periodontal indexes. The information acquired via such indexes therefore may be called into question. Inflammation of the gingiva was induced in 15 subjects. The degree of gingival swelling was determined via monophotogrammetry; the degree of inflammation, with the PMA index which emphasizes the symptom "swelling". The results were compared and discussed. It is highly probable that the PMA index is subjectively overrated.

Female↗