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P N Hirschmann

Publications and source records attributed to P N Hirschmann.

At least 19 recordsLinked to original sources
PubMed1990

Dose reduction in dental radiography.

All exposures to ionizing radiation for medical and dental purposes carry risks to both the patient and staff. It is now accepted practice that all exposures should be kept as low as reasonably practicable to minimize these risks. The various methods currently available for dose limitation in intraoral and panoramic radiography and their effects on image quality are considered. In intraoral radiography the use of fast (E-speed) film and rectangular collimation offer dose reductions of approximately 50 per cent and 60 per cent respectively. Constant potential X-ray units, longer focus-to-skin distances and rare-earth filtration will permit further dose reductions. In panoramic radiography the radiation dose to the patients can be reduced by up to one-eighth by combining the use of constant potential X-ray units, rare-earth intensifying screens and rare-earth filtration.

Humans↗
PubMed1989

Diagnostic and counselling difficulties using a fully comprehensive screening protocol for families at risk for tuberous sclerosis.

Tuberous sclerosis (TS) results from an autosomal dominant gene which exhibits variable expression and reduced penetrance. Although there are well established diagnostic criteria for TS, examination of first degree relatives can cause diagnostic criteria for TS, examination of first degree relatives can cause diagnostic problems with consequent difficulties in genetic counselling. Using an extensive, non-invasive protocol consisting of skin examination with Wood's lamp, cranial CT scan, specialist ophthalmological and dental examination, skeletal survey, and echocardiography, we have examined 56 first degree relatives of persons with TS. These consisted of 40 parents and seven sibs from 25 sporadically affected families and nine persons from seven multigeneration families. In seven of the apparently sporadically affected families, three mothers had echocardiographical findings consistent with one or more rhabdomyoma. In another, the mother's renal ultrasound showed evidence of single cysts in both kidneys. In a fifth family, the father had suggestive but not diagnostic features of TS on the cranial CT scan and skeletal survey. In the sixth family, the mother was found to have atypical calcification on CT scan. In a seventh instance a sib from a two generation family had echocardiographical evidence of a rhabdomyoma. Even though the proband in three of the sporadically affected families presented with fits, developmental delay, and depigmented patches, and therefore did not strictly fulfil the diagnostic criteria for TS, two mothers were found to have evidence of rhabdomyomata on echocardiography and the brother of the third had typical depigmented patches. Although the presently accepted diagnostic criteria for TS may not allow one to make a definitive diagnosis of TS in these relatives, we recommend that an extensive screening protocol be used to examine first degree relatives and that caution be used in counselling apparently unaffected members of families at risk for TS.

Bone and Bones↗
PubMed1988

Symptomatic residual radicular cysts.

The clinical, radiological and histological characteristics of 31 symptomatic residual radicular cysts are compared and contrasted with 39 asymptomatic residual cysts. Differences in size and site incidence are demonstrated along with an inversely proportional relationship between radiographic cortication and degree of acute inflammation in the cyst wall. A number of possible aetiological factors, to account for initiation of active inflammation in deeply placed residual cysts have been examined and excluded, but explanation, in most cases, remains paradoxical.

Epithelium↗
PubMed1987

Radiographic interpretation of chronic periodontitis.

There has recently been a substantial change in our concept of periodontal disease and particular attention is now focused on that small proportion of the population who appear susceptible to its more aggressive forms rather than the majority in whom bone loss progresses very slowly. It is also apparent that the presently available clinical parameters are of little value in predicting future destructive activity. Under these circumstances, the aim of this paper is to review the contribution of radiography to the diagnosis of chronic periodontitis as traditionally perceived and then reassess its status in the light of these newer concepts. Panoramic radiography, followed by the appropriate periapical radiographs (taken with the paralleling technique), is proposed as an alternative to complete mouth intra-oral surveys on grounds of both diagnostic yield and radiation thrift. The five areas to which radiography, despite its limitations, can make a significant contribution are in the assessment of bone loss, mobility, occlusal trauma, calculus and marginal overhangs and crown-root ratio. The validity of the three criteria that have been proposed for the radiographic assessment of early periodontitis, loss of crestal bone height, marginal widening of the periodontal ligament and crestal irregularity, is evaluated in detail and it is concluded that only the first is of any diagnostic worth, providing at least two sequential radiographs are available. While there is an urgent need to develop techniques of greater sensitivity for the early identification of periodontal bone loss, there must be some doubt as to the value of any bone imaging technique in predicting the susceptible patient. Follow-up radiography should be limited to these sites showing clinical evidence of further disease activity.

Bone Resorption↗
PubMed1987

The current status of panoramic radiography.

The current status of dental panoramic tomography (rotational panoramic radiography) is reviewed. This technique is based on a combination of tomography and slit-beam radiography to provide an image of both jaws on a single film. There is a greater degree of image degradation when compared with conventional radiographic techniques due to tomographic blurring, magnification and distortion, secondary images and burn-out. Meticulous patient position is essential to accommodate their jaws to the image layer determined by the manufacturers. The absorbed doses from panoramic radiography are of a similar order to that from bitewing radiography and lower than those from a full-mouth periapical series. The individual risk of 1.3 X 10(-6) is compared with that from other radiographic examinations and smoking. The collective risk, 1.04 deaths in the UK in 1981, is relatively insignificant as is the genetic dose. The risk to the dentist and his staff is also low compared to other risks. The methods of dose limitation currently available are reviewed. The clinical indications are considered in relation to the guidelines of the American Dental Association and the Dental Estimates Board in the UK. The problems associated with attempts to measure diagnostic yield are considered. In view of the world-wide public concern at the potential dangers of ionising radiation, dentists are urged to maximize the diagnostic yield from their panoramic radiography by taking such radiographs only when clinically necessary, ensuring meticulous positioning and processing, followed by scrupulous assessment of the radiography for any sign of pathological change.

Humans↗
PubMed1986

Age changes in residual radicular cysts.

Histological and radiographic study of 33 uninfected residual radicular cysts has shown that there is a slow increase in mineralised deposits within the cyst lumen with time. This becomes prominent histochemically in those cysts more than 8 years old and radiographically 6 years later. It would appear that mineralisation in these elderly cysts is due to dystrophic calcification of degenerate cellular material within the cyst lumen. Inflammation in all cysts, apart from mild granulomatous reactions related to cholesterol within cyst walls, was minimal. Overall reduction of cyst size with increasing epithelial atrophy and loss of hyaline bodies and mucous cells, has been shown to occur with increasing cyst age. It is suggested that the majority of radicular cysts heal spontaneously following extraction of the associated tooth. Furthermore, lesions that persist as residual radicular cysts will also undergo slow resolution if inflammation is not a prominent feature.

Calcinosis↗