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Biomedical subjects

A P Jacobson

Publications and source records attributed to A P Jacobson.

At least 19 recordsLinked to original sources
PubMed1998

The influence of toothbrushing frequency and post-brushing rinsing on caries experience in a caries clinical trial.

OBJECTIVE: To examine the effect of reported toothbrushing frequency and method of rinsing after brushing on caries experience and increment. METHODS: Data are presented from 2621 adolescents (mean age 12.5 years at outset) participating in a 3-year double-blind caries clinical trial. At baseline, examiners questioned each participant about their toothbrushing habits, and at subsequent examinations, this information was obtained using a self-administered computer-based questionnaire. Participants used a fluoride-containing dentifrice throughout and clinical examinations were conducted using a mirror, CPITN probe and fibre-optic transillumination. RESULTS: The reported brushing frequency increased throughout the trial. Caries experience at baseline was inversely related to toothbrushing frequency with mean DMFS=9.66, 8.12 and 7.63 respectively for <1/day, 1/day and >1/day brushers (P<0.001). Mean 3-year DMFS increments of 8.90, 6.63 and 5.48 (P<0.01) were observed in those reporting to brush <1/day, 1/day or >1/day, on not less than two of the three clinical examinations during the trial. Caries increment was also significantly related to the claimed method used to rinse post-brushing. Overall frequency of brushing and rinsing method accounted for over 50% of the explained variance in the ANOVA model used to analyse the DMFS increments. CONCLUSIONS: Stated toothbrushing frequency and rinsing method after brushing were found to be strongly correlated with caries experience and caries increment. These factors should be reflected in the design of oral health education material and taken into account in the design and analysis of caries clinical trials.

Adolescent↗
PubMed1996

Incremental susceptibility of individual tooth surfaces to dental caries in Scottish adolescents.

This study reports on the caries susceptibility of tooth surfaces in 4294 adolescents (mean age 12.5 yr) during a 3-yr, double-blind clinical caries trial, conducted in Lanarkshire, Scotland, between 1988 and 1992. Children were selected on the grounds of dental maturity and past caries experience. Clinical examinations with mirror, CPITN probe and fibre optic trans-illumination were carried out on the permanent dentition, with the buccal pits of mandibular molars and palatal pits of maxillary molars being recorded as separate sites. At baseline 6061 surfaces were decayed (1.0% of 601 160 surfaces examined), 20 160 (3.4%) filled, and 10 909 (1.8%) missing due to caries. The number of surfaces recorded as sound at baseline in subjects completing the study was 454 663. Of these 8176 (1.8%) new surfaces were decayed, 14 832 (3.3%) filled and 4000 (0.9%) missing at the final examination. Molar occlusal surfaces showed greatest susceptibility to attack, 35.8%) of those at risk becoming carious in the course of the study. All buccal and lingual smooth surfaces showed a low susceptibility, but 8.8% of buccal and palatal pits developed caries. At the final clinical-only examination, pit and fissure caries accounted for 48%, interproximal surfaces for 39%, and smooth surfaces for 13% of caries prevalence. However, overall the contribution of these surfaces to 3-yr increments was, 40%, 47% and 13%, respectively.

Adolescent↗
PubMed1995

Prevalence of clinically apparent recurrent caries in Scottish adolescents, and the influence of oral hygiene practices.

The prevalence of recurrent caries was recorded at the annual examinations of a 3-year double-blind caries clinical trial involving 4,294 children age 12-13 years at baseline. Recurrent caries was defined as clinically apparent disease affecting the restoration margins. Examination of all surfaces of undried teeth was carried out using a CPITN-C probe. The proportion of children with recurrent caries was 7.5, 9.5, 6.3 and 8.0% at baseline, year 1, year 2, and year 3. The proportions of restorations with recurrent caries was 1.9, 1.8, 1.0 and 1.1%, respectively, at each examination. A number of oral hygiene parameters were collected via a computer questionnaire. Water rinsing after brushing proved to be associated with recurrent caries (p < 0.01), those using a beaker having more recurrent caries than those using less diluting methods. Subjects who brushed twice a day (at the final examination) had less recurrent caries than those reporting to brush less often (p < 0.01). Both these results are consistent with previous findings on the association between DMFS increments and oral hygiene practices.

Adolescent↗
PubMed1994

The prevalence and effectiveness of fissure sealants in Scottish adolescents.

The presence of fissure sealants was recorded in 4294 adolescents during a 3-year, double-blind clinical caries trial, conducted in Lanarkshire, Scotland, between 1988 and 1992. Of 68,704 occlusal surfaces examined at baseline, sealants were detected on 7011 (10.2%) surfaces, in 1596 subjects. Of these, 17.4% were judged as incompletely sealed. At the final examination 24.3% of sealants originally recorded as complete were missing, with partial loss observed on a further 18.2% of surfaces. At that time, 21.4% of surfaces 'unsealed but sound' at baseline were recorded as decayed, filled or extracted due to caries, compared with 14.4% of surfaces on which an intact sealant had been recorded (P < 0.001). In contrast, of those surfaces on which the sealant was noted as deficient at the outset, 22.9% were judged to have been affected by caries. This study shows that sealants should be repaired when deficient if they are to be effective.

Adolescent↗
PubMed1994

Studies on plaque fluoride after use of F-containing dentifrices.

Increased fluoride levels in plaque and saliva have been associated with improved protection against dental caries for dentifrices which contained sodium monofluorophosphate (Duckworth et al., 1992). The main aim of the present work was to test whether oral fluoride retention depended on F source after use of dentifrices containing either NaF or Na2FPO3. In study 1, plaque samples were collected from 474 subjects who had been using one of six test dentifrices for two years, and analyzed by F extraction with water. The dentifrices contained 1000 or 1500 micrograms F/g as either NaF or Na2FPO3. Significantly more fluoride was found in plaque from subjects who were using the NaF dentifrices than in plaque from subjects who were using Na2FPO3 dentifrices of the same F content. Subsets of plaque samples were large enough to divide into two parts for extraction by both acid and water. No significant difference was found between mean fluoride contents, indicating that the majority of fluoride retained in plaque from these conventional dentifrices appears to be relatively labile. The results of two small-scale human enamel studies showed that NaF dentifrices gave elevated F concentrations in plaque and saliva, respectively, compared with Na2FPO3 dentifrices of equivalent F content, consistent with the main plaque study 1. These findings demonstrate that oral F retention from dentifrices is dependent on the source of ionic fluoride and support the view that NaF dentifrices may be more clinically effective than dentifrices which contain the same amount of F as Na2FPO3.

Adolescent↗
PubMed1994

The effect of NaF and SMFP toothpastes on three-year caries increments in adolescents.

A three-year double blind clinical caries trial was undertaken to compare the anticaries efficacy of three types of active agent, namely sodium fluoride (NaF), sodium monofluorophosphate (SMFP) and the combination of NaF plus sodium trimetaphosphate (TMP), using two fluoride levels (1000 ppm F and 1500 ppm F). The prime objective of the study was to determine whether there was any difference in the anticaries efficacy between NaF and SMFP. The second objective was to assess the effect on caries protection of the incorporation of TMP into a NaF dentifrice formulation. The study was carried out to FDI protocol and involved 4,294 children aged 11-12 years at outset. These participants had been selected from a pool of 6,212 potential subjects on the basis of caries experience and dental eruption pattern. They were stratified by sex, examiner, presence of calculus and caries, and allocated at random to one of the six toothpastes under study. Clinical examinations were carried out at baseline and thereafter annually for 3 years. Bitewing radiographs of a subset of children were taken at baseline and at the end of the study. The outcome measure for the study, DMFS increment, was defined as the increase in caries over three years, taking into account changes occurring on individual tooth surfaces. After three years, clinical-only data for 3,517 children were available for the calculation of caries indices. The mean three-year DMFS increment for subjects using a dentifrice containing NaF alone was 6.4 per cent lower than for those using a dentifrice containing SMFP. The difference between the NaF+TMP users and the SMFP users was 8.1 percent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

A graphical method of estimating fatal radiation-induced cancers using the BEIR V method.

A method is presented that permits health physicists to estimate the risks of radiation-induced cancers in populations of males or females exposed to whole-body external irradiation at any age. Graphics are presented that may be used for either acute or chronic exposures. There is good agreement for chronic exposures when the cancer estimates determined here are compared with those prescribed in BEIR V. There are differences between the two when considering some acute exposures. In such circumstances, the method given here generally gives conservative results.

Environmental Exposure↗
PubMed1991

Analysis of repeated-measure multicycle unilateral mastication in children.

This study examined systematic and random errors associated with repeated-measure, multiple-cycle unilateral mastication in children during single recording sessions with the Replicator system. Twenty-six recording sessions with 17 children (10 boys, 7 girls) were examined. Nine of these children had a functional-shift unilateral crossbite malocclusion and were recorded before and after crossbite correction. Repeated recordings (trials) of mandibular movement during each session were made of right-side chewing of similar-sized pieces of cheese. The following variables were computed for each chewing cycle (stroke): time closed, maximum closure velocity, maximum opening velocity, chewing rate, vertical opening, and lateral deviation. From the multiple cycles of each trial, two pattern descriptors--the average and standard deviation--were determined for each variable. In addition, the mean and variance of these pattern descriptors were determined from the multiple trials of each recording session and were the dependent variables in a stepwise multiple regression analysis, with treatment status, sex, age, dentition stage, crossbite presence, and right side status the independent variables. The results disclosed bias in repeated measures of human chewing in response to adaptation to the recording session; this was evident in the average response but not in the variability of the measures. Sex and functional status of the subjects were associated with the mean and variance of measures describing the chewing pattern.

Adolescent↗
PubMed1982

Health effect of occupational exposure to steady magnetic fields.

An observational cross sectional study was conducted to determine if long term exposure to steady magnetic fields of up to 200 Oersteds could be related, on a dose-response basis, to findings of medical examinations. Health data were obtained for 320 workers who spent a major portion of their workday in the magnetic fields produced by the direct current through large electrolytic cells. These data were compared to those for a control group of 186 workers. The vertical and horizontal components of the magnetic fields were measured in each cell room and the time weighted average exposure to magnetic fields was calculated for each job classification. The leukocyte count and the monocyte percent were found to decrease, while the lymphocyte percent was found to increase with increased exposure to the horizontal component of the magnetic field. A slight tendency of both the systolic and diastolic blood pressures to increase with increasing exposure to the vertical component of the magnetic field was found in the black workers in the study. No such effect was found in the other racial groups. No other signs or symptoms were found to depend on magnetic field exposure.

Analysis of Variance↗
PubMed1981

Chewing patterns in normal children.

Chewing patterns are precisely plotted in deciduous, mixed and permanent dentitions. These show a progression from a large component in the opening movement with a more medial closing path in the deciduous dentition, to a more vertical overall pattern with the closing path lateral to the opening path in the early permanent dentition.

Adolescent↗
PubMed1978

Contamination of the home environment by patients treated with Iodine-131: initial results.

We have employed twin sodium iodide radiation detectors to analyze iodine-131 transfer from thyroid patients to their families. Unlike previous studies of this problem, we measured thyroid radioiodine activity directly and are able to detect as little as 92 pCi of iodine 131 in adult thyroids. As in previous studies, we have also measured direct radiation exposures of family members with wristband thermoluminescent dosimeters. Thus far, we have studied seven families with 17 persons. Eleven of these are children under age 16. Direct radiation exposure of family persons from proximity of these radioactive patients ranged from 0.17 to 126 mR per day (natural background radiation amounts to approximately 0.35 mR per day). The maximum activity of iodine-131 in family thyroids ranged from less than 92 pCi to as high as 110,000 pCi and resulted in thyroid dose equivalents of 4 to 1330 mrem. Based on recent estimates of thyroid cancer, the latter dose equivalent could possibly double the risk of thyroid malignancy in children over what is expected normally. Such a risk implies the addition of 10 induced cases to the 10 naturally occurring cases per million people per year.

Adolescent↗
PubMed1977

Radioresistance of mongolian gerbils. Fast neutrons.

Seventy-six 8 week old Mongolian gerbils were exposed to acute, whole-body fast neutrons produced by The University of Michigan 83-in. cyclotron. Groups of seven or eigth gerbils were given doses between 485 and 881 rad at 25 rad per minute. The LD 50/30 determined by probit analysis was 750 rad, with 95 per cent fiducial limits of 733 and 776. For the 50 per cent mortality level, an r.b.e. of fast neutrons compared with cobalt-60 of 1-45 was determined. For the same end-point, the r.b.e. for fast neutrons compared with X-rays is 1-33. Mortality data, body-weight and microhaematocrit changes are discussed.

Animals↗