Biomedical subjects

A Lith

Publications and source records attributed to A Lith.

10 recordsLinked to original sources

PubMed2004

Effective and organ doses from scanography and zonography: a comparison with periapical radiography.

OBJECTIVES: To compare absorbed and effective doses from scanographic and zonographic examinations performed in the Scanora unit with intraoral periapical radiography. METHODS: Absorbed dose measurements were made on an anthropomorphic phantom head with LiF thermoluminescent dosemeters in the regions of the pituitary gland, eye lenses, parotid glands, submandibular glands, thyroid gland and skin. Energy imparted was calculated from the measurements of air collision kerma and effective doses by using the quotient 24 mSv J-1 between energy imparted and effective dose. The upper and lower third molar region was examined with intraoral radiographs and with ramus scanograms, dental scanograms and dental zonograms. Radiation dose measurements were also performed for Scanora panoramic radiography (jaw and dental). RESULTS: The effective doses for the ramus and dental scanograms were 0.01 mSv, similar or lower than for intraoral radiography. Zonography yielded the highest effective dose (0.03 mSv). Except for the skin doses, the salivary glands received the highest doses. Salivary gland doses were slightly higher from narrow beam than from intraoral radiography. CONCLUSIONS: Detail narrow beam radiography with the Scanora is an alternative to periapical radiography and is preferred, from a radiation dose point of view, over zonography.

Humans↗

PubMed2002

Caries development in a young population managed by a restrictive attitude to radiography and operative intervention: II. A study at the surface level.

OBJECTIVES: To longitudinally assess the distribution of fillings and carious lesions in permanent posterior tooth surfaces, caries states fillings were made, and survival time of proximal lesions in different states in a young population managed by minimal operative treatment and a restrictive attitude to radiography. METHODS: Bitewing radiographs from age 6-20 in 285 patients were analysed. Proximal and occlusal surfaces were coded for caries depth and fillings. Start and end dates for different caries states in proximal surfaces were assigned and survival times in these states calculated by means of survival statistics. RESULTS: The frequency of carious/filled occlusal surfaces in the population increased from 6 to 19% and that of proximal surfaces from 1 to 26%. At age 19, 86% of the occlusal and 7% of the proximal surfaces affected by caries were filled. An overwhelming majority of unfilled carious proximal surfaces had enamel lesions only. Of all fillings, 81% were placed in surfaces with dentine lesions. The occlusal and proximal surfaces of the first molar and the distal surface of the second premolar accounted for most lesions and fillings among the 19-year-olds. The average survival time of lesions in the enamel was 8.0 years and in the outer half of the dentine 3.4 years when right-censored data were taken into account. CONCLUSION: In a young population exposed to optimal levels of fluoride with a caries preventive programme, a restrictive attitude towards operative treatment can be combined with longer average intervals between radiographic examinations than those prescribed by current guidelines.

Adolescent↗

PubMed2002

Caries development in a young population managed by a restrictive attitude to radiography and operative intervention: I. A study at the patient level.

OBJECTIVES: To assess, in a young population (age 6-19) managed by a restrictive attitude to radiography and operative intervention, prevalence of patients with posterior caries and/or fillings, probabilities of new proximal dentine lesions given different caries experience, correlation between radiographic intervals and caries experience, and prevalence of endodontic treatment. METHODS: Bitewing radiographs, taken between age 6 through 19 in 285 patients, were analysed in succession. Occlusal and proximal surfaces were coded for caries depth (0-4) and presence of fillings (5). Simple regression analysis was used to determine relations between radiographic intervals and caries experience. Significance testings of probability estimates were made with chi(2)- and t-tests, when applicable adjusted by the Bonferroni-Holm correction for mass-significance. RESULTS: The prevalence of patients with >/ or =1 fillings/dentine lesions in occlusal surfaces increased from 6-78% and in proximal ones from 1-38%. The probability of developing new proximal dentine lesions/fillings over different time periods was significantly lower among caries-free patients than among those with enamel or dentine lesions. There was a poor correlation between radiographic intervals (mean=16 months, range=6-33) and accumulated caries experience. Endodontic treatment had been made in a total of six teeth in six patients. CONCLUSIONS: A restrictive attitude both to the frequency with which radiographs are taken and to operative treatment of proximal caries seems to be possible in young populations with low caries prevalence.

Adolescent↗

PubMed2001

Frequency of radiographic caries examinations and development of dental caries.

The general aim of this thesis was to evaluate whether a change in the threshold for surgical intervention in the caries process can be consistent with a stricter attitude towards the use of radiographic caries diagnosis. Bitewing radiographs of 3 groups of patients were retrospectively studied. Two groups comprised 229 patients, 18 years old at the end of the study in 1984. 102 had lived in an area with 1.2 ppm water-fluoride content (F84-group) and 127 in an area with 0.02 ppm fluoride content (O84-group). In the 3rd group 285 patients, 19 years old at the end of the study in 1993, lived in an area with 1.2 ppm water-fluoride content (F93-group). The latter patients were managed according to a restrictive attitude to surgical intervention and radiographic diagnosis of caries. The prevalence of patients and the frequency of tooth surfaces with caries was significantly lower in the fluoride groups than in the non-fluoride group. The correlation between patients' accumulated number of posterior proximal lesions and fillings at the last examination and the mean interval between their bitewing examinations was weak in all groups. The mean interval between examinations was significantly longer in the F93-group than in the other 2 groups. By applying an algorithm for individualisation of examination intervals these could be prolonged depending on the accepted risk for the development of inner dentin lesions. Future development of proximal dentin lesions was rather well predicted by means of past caries experience as demonstrated by ROC-analysis. The proportion of inner dentin lesions that were operatively treated was significantly higher in patients from the F93-group than in those from the other 2 groups in which a less strict attitude towards operative treatment was used. In the F93-group the average survival time of enamel and outer dentin lesions was 8.0 and 3.4 years, respectively, when right censored data were taken into account. In populations with low caries prevalence a strict threshold for operative treatment of proximal lesions can be consistent with prolonged intervals between radiographic examinations without an increased risk of pulp involvement. A skewed distribution of the patients with regard to caries experience was found in all 3 groups. Thus, even in low prevalence populations the intervals between radiographic examinations must be individually determined and coupled with individualised preventive care.

Adolescent↗

PubMed1996

Speech and velopharyngeal function in children with an open residual cleft in the hard palate, and the influence of temporary covering.

The influence of an open residual cleft in the hard palate on speech was studied in nine children with cleft lip and palate at about 7 years of age. The subjects were treated by early repair of the velum (before 12 months of age), whereas the repair of the cleft in the hard palate was postponed until about 8 years of age. Speech and velopharyngeal function were assessed systematically with the residual cleft open and temporarily covered with an oral bandage. Listeners' judgments, the Nasal Oral RAtio Meter (NORAM), videofluoroscopy, and cephalometrics were used for the analyses. Four patients were also examined with a pressure-flow technique. Nasality registered by NORAM, nasal escape, and weak pressure consonants judged by listeners were common but decreased appreciably when the residual cleft was covered. Retracted articulation was found in four patients (44%) and glottal compensations in one (11%), with no improvement after covering.

Age Factors↗

PubMed1995

Radiographic study of approximal restorative treatment in children and adolescents in two Swedish communities differing in caries prevalence.

In two groups of patients, differing in caries prevalence, the restorative treatment of posterior approximal surfaces in permanent teeth was studied in radiographs obtained as part of the dental care provided from age 6 up to and including age 18. The study determined at what age, at which lesion depth and in which surfaces restorative treatment was performed. Furthermore, the conditions of nonrestored dentin lesions were evaluated over time. Nearly 50% of the restorations were placed in the mesial surface of the first molars. In both groups more than 2/3 of the restorations were placed in surfaces with dentin lesions. In the group with the highest caries prevalence 50% of the lesions in the outer half of the dentin were restored when first detected in contrast to 20% in the groups with the lower prevalence. For the superficial dentin lesions not immediately restored, average time between their detection and restoration, the end of the study or, detection in the inner half of the dentin was practically the same in both groups (19.3 and 20.4 months). The variation in this average time was only to a limited degree explained by the variation in the caries experience of the patients.

Adolescent↗

PubMed1992

Approximal caries and frequency of bitewing examinations in Swedish children and adolescents.

The aim of this study was to assess the number of, and time intervals between, bitewing examinations performed on a group of Swedish patients between 3 up to and including 18 yr of age and to relate them to the accumulated posterior approximal caries experience of the patients as found in the last bitewing examination before age 19. The patients showed a marked variability in approximal caries experience. 25% accounted for about 1% of the total number of carious lesions and restorations accumulated up to age 19 while 25% accounted for 60%. From age 9 up to age 18 more than 75% of the patients were subjected to at least one bitewing examination annually. Between 10 and 15 yr of age more than 90% received annual radiographic examinations. Mean number of bitewing examinations was 10.4 and the average time interval between bitewing examinations was 11.5 months. 11% of the variation in the number of bitewing examinations and 8% of the variation in average time intervals between bitewing examinations could be explained by the number of lesions and restorations in the approximal surfaces of the patients accumulated up to age 19.

Adolescent↗

PubMed1992

Predicting development of approximal dentin lesions by means of past caries experience.

The aim of this study was to assess the accuracy in predicting future development of approximal dentin lesions using radiographically observed numbers of restored and carious surfaces at age 13 as diagnostic criteria. ROC curve technique was applied employing the development of at least one new dentin lesion from age 13 to age 15 and 18 respectively, as validating criterion. Two groups of patients were considered, residing in communities with water fluoride content of 0.2 ppm and 1.2 ppm, respectively. Results showed that the development of dentin lesions could be predicted with an accuracy similar to that of many other dental radiographic procedures. This implies that it ought to be possible to use previous caries experience as a means of individualizing the scheduling of future radiographic procedures.

Adolescent↗

PubMed1992

Intervals between bitewing examinations in young patients when applying a radiologic algorithm.

Every prescription of a radiograph should be based on an evaluation of the individual patient benefit. An algorithm developed to make it possible to individualize the frequency of bitewing radiographs was applied on a group of young patients in order to evaluate if its application could increase the time intervals between bitewing examinations. The time intervals between bitewing examinations actually performed on 221 patients from exfoliation of all primary teeth up to and including 18 yr of age were determined. The number of surfaces with carious lesions as well as restorations in the posterior approximal surfaces were diagnosed from the radiographs. The intervals between bitewing examinations according to the algorithm were estimated and compared to the actual ones. For most patients the time intervals between examinations increased when the algorithm was applied, without a concomitant risk of missing lesions developing into the deeper parts of the dentin. The results render support to an individualized scheduling of bitewing radiographs based on number of and extent of approximal lesions in baseline radiographs.

Adolescent↗

PubMed1991

Orofacial functions in patients with congenital and acquired maxillary defects: a fluoroscopic study.

By means of videofluoroscopic recordings, chewing, swallowing and speech were monitored in nine patients with congenital and acquired maxillary defects. All of them were rehabilitated with a maxillary obturator prosthesis. The defective region was seldom used for chewing. No leakage between the obturator and surrounding tissue was observed, either for solids or for liquids. All of the prosthetic reconstructions were surprisingly stable during function. In the phonetic analysis, speech production was judged to be restored almost to normal. Videofluoroscopy may be valuable as a complement to other functional diagnostic procedures, and for the evaluation and improvement of rehabilitation with an obturator prosthesis.

Adult↗