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At least 91 records · Page 5Linked to original sources
PubMed1975

Variability of the craniofacial skeleton. III. Radiographic cephalometry of juvenile Macaca mulatta.

The variability of the craniofacial skeleton of the juvenile Macaca mulatta was studied from lateral radiographic cephalograms of twenty-three animals, using a previously described method based on fourteen lines depicting certain anatomic features. The findings, when compared to corresponding human data, revealed that a number of angular relationships are similar in this monkey and in human childrena and adults. The same is true regarding the variability of individual lines. These similarities suggest that biologic similarities exist in the cranio-facial skeletal architecture in these species. Specifically, the findings in the Macaca mulatta were in agreement with previous findings in human children and adults as regards the parallelism between the anterior parts of the neurovascular canals of the upper and lower jaws and the apparently adaptive role of the ramus and the condyle.

Age Factors↗
PubMed1978

Landmark identification accuracy in xeroradiographic cephalometry.

Identification accuracy of fourteen cephalometric landmarks was compared between xeroradiographic cephalograms and conventional cephalograms. Four landmarks--point A, upper incisor tip, infradentale, and menton--were more accurately determined on the xeroradiograph, while two landmarks--point B and condylion--were more accurately determined on the conventional cephalogram. Although not conclusively demonstrated in this study, the xeroradiograph does appear to offer more clarity and detail than the conventional cephalogram. Further investigation of this new diagnostic medium will be necessary before its true significance to dentistry can be evaluated.

Cephalometry↗
PubMed1979

Interobserver reliability in xeroradiographic cephalometry.

Observer agreement on cephalometric landmarks was compared between xeroradiographs and conventional radiographs of twenty-nine patients. Of fourteen landmarks evaluated, four (condylion, infradentale, Ptm, and ANS) demonstrated clinical significance in favor of the xeroradiograph. In addition, six other landmarks favored the xeroradiograph but not to the degree of statistical significance.

Adolescent↗
PubMed1983

Analysis of craniofacial asymmetry by multiplane cephalometry.

A three-dimensional, multiplane cephalometric analysis is presented. This analysis permits visualization of skeletal midlines at selected depths of the craniofacial complex. When the midlines and associated anatomic structures are studied sequentially, the individual midlines may be combined conceptually into a warped midsagittal "plane." This localizes craniofacial asymmetry in the posteroanterior and basilar views. The study of structures in various coronal and transverse planes makes it possible to measure and record the three-dimensional relationships of anatomic structures to one another. A case of hemicraniofacial microsomia in which this analysis was used is presented.

Cephalometry↗
PubMed1992

Dosimetry of absorbed radiation in radiographic cephalometry.

Absorbed radiation was measured in various craniofacial tissues on an adult phantom (Alderson Rando) when conventional cephalometric radiographic techniques were used. The views examined were lateral, 45 degrees oblique, posteroanterior, lateral temporomandibular joint tomograph, and basilar (submental-vertex). Absorbed radiation was expressed in micrograys for the individual views and for combinations of views as customarily used in orthodontics and oral surgery. These data are compared with findings of contemporary investigators and the magnitude of the doses is compared with those in the literature for periapical and panoramic surveys.

Absorption↗
PubMed1993

Radiation-induced cancer risk in radiographic cephalometry.

The carcinogenic risks associated with the cephalometric x-ray techniques customarily used in orthodontics and oral surgery have been estimated. Lateral, posteroanterior, 45 degrees oblique, lateral temporomandibular joint tomography, basilar techniques, and commonly-used combinations were examined. Data reported in a previous article on doses absorbed by pituitary (brain), salivary, and thyroid glands were used to calculate increased risk over normal incidence using the BEIR V model. The findings are expressed in a number of graphs. Tables list the estimated percentage increase in carcinomas for several of the most often used cephalometric procedures, and compare these with the more common complete mouth (periapical) and panoramic surveys. The overall conclusion is that responsible use of cephalometric radiology adds very little to the person's carcinogenic burden.

Absorption↗
PubMed1989

Research on predictability in cephalometry of the relationship of chin symphysis and nose-chin balance.

A sample of 120 untreated Caucasian adults was selected. All subjects were dental and skeletal Class I. The approach calls for the use of an original cephalometric method that is applied to the cutaneous profile by an esthetic curve extending from the nose to the chin. Statistical study of the sample confirms the existence of this cutaneous profile, regardless of facial type. This approach is proposed in combination with Sassouni's analysis to specify pogonion in the vertical and anteroposterior planes from which the vertical position of the chin (menton) may be deduced.

Adult↗
PubMed1989

Computer-assisted location of reference points in three dimensions for radiographic cephalometry.

A major obstacle to the derivation of three-dimensional data from lateral and coronal radiographs of the head has been the lack of precision in locating the same landmarks on each of the biplanar images. The method described herein uses radiographic equations based on the geometry of a biplanar system to predict the location of a reference point on one film from its location on the other. This technique, which differs from previously described systems, allows a pair of cephalometric films to be digitized by an on-line procedure controlled by a personal computer. Three-dimensional coordinates of reference points are calculated and stored for subsequent retrieval when they can be used for metric analysis or for the display of simple wire-frame models of the skull. Computing algorithms are provided to aid software development.

Algorithms↗
PubMed2005

Direct digital lateral cephalometry: the effects of JPEG compression on image quality.

OBJECTIVES: This study used an aluminium test object to assess the effect of the Joint Photographics Expert Group (JPEG) compression algorithm, on direct digital cephalometric image quality. METHODS: The aluminium block of 15 steps, with 20 holes in each step was radiographed in a Planmeca Proline 2002 digital cephalometric machine with Dimaxis2 software. Six different JPEG compression ratios were used to capture the cephalometric images. These ratios were 60%, 70%, 80%, 90%, TOP QUALITY JPEG (TQJPEG 98%) and TIFF (uncompressed). The images were taken at 68 kV and 12 mA with a 7 s exposure. Six experienced observers viewed the monitor displayed images, which were presented randomly. This was repeated one month later. The number of holes detected by each observer was plotted against each compression ratio. Intra-observer and inter-observer reproducibility was calculated using the Mann-Whitney U-test. Differences between the compression ratios were assessed using a Kruskal-Wallis one-way analysis of variance. RESULTS: When comparing intra-observer reproducibility, it was found that there were only four of 36 comparisons that showed a statistically significant difference (Observer 1: 60% (P=0.004), TQJPEG (P=0.019); Observer 2: TIFF (P=0.005); Observer 3: 90% (P=0.007)). Statistically, there was no significant difference with inter-observer reproducibility. There was no statistically significant difference between the image quality obtained from each compression ratio. CONCLUSIONS: The results showed that JPEG compression does not have any effect on the perceptibility of landmarks in the aluminium test object used in this study.

Algorithms↗