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Biomedical subjects

A Kingman

Publications and source records attributed to A Kingman.

At least 55 records · Page 3Linked to original sources
PubMed1993

Comparison of tooth surface-specific dental caries attack patterns in US schoolchildren from two national surveys.

The 1979-1980 and the 1986-1987 National Institute of Dental Research (NIDR) surveys of school-aged children revealed that virtually all tooth surfaces experienced a decrease in caries prevalence during the inter-survey period. Overall, there was a 28% decrease in the proportion of tooth surfaces attacked by caries for the primary dentition between the two surveys. The decrease for primary incisors was numerically small (5 surfaces per thousand surfaces at risk) and not statistically significant, whereas decreases in the canines and primary molars were considerably larger (23 surfaces per thousand) and statistically significant. For the permanent dentition, the overall decrease in the proportion of surfaces attacked was 35% during the 1979-87 period. Differences between the two surveys in the proportions of surfaces with caries were largest for pit and fissure surfaces (56 surfaces per thousand), followed by those for posterior approximal surfaces (14 surfaces per thousand) and all other smooth surfaces (5 surfaces per thousand). Almost all of these differences were statistically significant, except for some surfaces which experienced very few caries.

Adolescent↗
PubMed1992

Specific statistical considerations relevant to the design and analysis of gingivitis trials demonstrating product superiority or equivalence.

Simulation studies were conducted to address specific statistical issues which arise in the design and analysis of gingivitis studies whose principal aim is the demonstration of superiority or equivalence of one product to another. The effects of measurement scale, using differences or ratios of group means, particular statistical test produces and specific rules demonstrating superiority or equivalence were investigated. An alternative concept to equivalence--denoted "least as good"--was also defined and evaluated. For a wide class of possible distributions of gingivitis scores, characterized by specific gamma distributions, the student-t test applied to means of subject GI gingivitis scores proved to be the most powerful of the test produces considered, having statistical properties quite similar to the randomization or permutation test procedure. Transformations of subject GI mean gingivitis scores did not produce an advantage in demonstrating either superiority or equivalence, and in some cases made it more difficult. Little difference was observed in test results when using the difference in group means as compared with using the ratio of group means for demonstrating either equivalence or superiority. The clinically significant rule produced the lowest false-positive rates for products slightly better than the active control, and similar false-positive and -negative rates as the statistically significant rule for products clearly superior to the active control. Demonstration of product equivalence will require more subjects per group than demonstrating product superiority, the size of this difference being a function of the definition of superiority that is accepted. Showing that the 90% confidence interval for 100*R is completely contained within the [90%, 110%] interval is the preferred method of demonstrating equivalence today, although much more research needs to be done to improve methods for demonstrating product equivalence. The "least as good" alternative to "equivalence" makes it easier to demonstrate "equivalence" for products slightly better than the active control product, but both experience great difficulty in demonstrating equivalence for test products not quite as good as the active control.

Chlorhexidine↗
PubMed1992

Statistical vs clinical significance in product testing: can they be designed to satisfy equivalence?

Statistical issues associated with demonstrating significance between treatment groups (efficacy or superiority) and nonsignificance (equivalence) are presented and discussed. Methodologies for demonstrating efficacy of a product are proposed and contrasted, incorporating clinical and statistical criteria, with emphasis on situations in which placebo groups are precluded from the study design. Distinctions are drawn between study designs for demonstrating superiority and those for equivalence, including the determination of sample sizes needed for the different approaches. The "at least as good as" criterion is proposed as a reasonable alternative to that of equivalence in active control equivalence studies for demonstrating that dental product modifications or new products are efficacious.

Clinical Trials as Topic↗
PubMed1992

Interim report of the ad hoc committee for the consideration of statistical concerns related to the use of intra-oral models in submissions for product claims approval to the American Dental Association.

Subsequent to the American Dental Association Symposium on Intra-oral Studies, held in Chicago in September, 1990, the Council on Dental Therapeutics decided that further consideration should be given to statistical issues relating to intra-oral models. The authors accepted the request of Council staff to assist in the development of Guidelines concerning the validity, reliability, and combinability of data obtained from these models. The ensuing work in this area, which began in the fall of 1990 and has continued to date, has thus far focused on the tissue of validity. The purpose of the present paper is to provide the interested community at large with an update on the progress made thus far, and to provide some perspective as to where all of the work in this area may eventually be leading. It is anticipated that a more comprehensive and definitive report will be produced at the completion of this process.

American Dental Association↗
PubMed1991

Errors in measuring parameters associated with periodontal health and disease.

The intra-examiner reliability for the Plaque Index (PII), Calculus Index (CI), Gingival Index (GI), and periodontal loss of attachment (LA) was evaluated in 2 different physical and clinical environments. Examiner reliability for each index was consistently better when clinical evaluations were performed in an office setting on subjects who had low levels of periodontal disease than under more difficult field conditions evaluating subjects with higher disease levels. In an office environment intra-examiner reliabilities were very good for subject-based averages (intraclass r's were 0.85, 0.83, 0.81, and 0.78 for GI, PII, LA, and CI, respectively); they were moderate to good for site-based scores (kappas were 0.63, 0.54, and 0.47 for CI, GI, and PII). Under field conditions reliabilities ranged from excellent to fair for subject-based averages (intraclass r's of 0.98, 0.86, 0.76, and 0.33 for LA, CI, GI, and PII, respectively); for site-based scores they ranged from moderate to fair (kappas of 0.50, 0.49, and 0.21 for GI, CI, and PII, respectively). Small but significant systematic errors were detected under field conditions for the PII and CI, and for the PII in the office environment as well. The results observed suggest that the examination process can affect the clinical status of the surface or site when replicate assessments of plaque and calculus are conducted within a 24-hour period. Our results also confirm that measurement error standard deviation for loss of attachment evaluated with a periodontal probe can be maintained at 0.13 mm for whole-mouth means and 0.54 mm for individual sites, even when examining subjects with substantial periodontal disease under field conditions.

Analysis of Variance↗
PubMed1989

Bacteriological comparison of ultrasonic and hand instrumentation of root canals in dogs.

This study compared the effectiveness of hand and ultrasonic instrumentation for removing a standardized inoculum of pigmented Serratia marcescens from the root canal system of premolars in dogs. Forty-four premolars from nine beagle dogs were divided into two experimental groups of 20 and 24 teeth, respectively. The experimental teeth were inoculated with approximately 10 colony-forming units of S. marcescens. After the bacterial were allowed to colonize for 1 wk, the experimental teeth were instrumented with either hand instruments or the Cavi-Endo device. The teeth were extracted, crushed, and assayed for recoverable colony-forming units of S. marcescens. Statistical comparisons of the ratio of inoculated to recovered colony-forming untis were made. The results indicated that the difference between the positive controls and the experimental groups was significant. There was no significant difference between the two instrumentation groups.

Animals↗
PubMed1988

Salivary levels of Streptococcus mutans and lactobacilli and dental caries experiences in a US adolescent population.

Dental caries exams and saliva samples were obtained from 541 adolescents, aged 10-15, initially and after 17 months as part of a 3-yr longitudinal study investigating the relationships of dietary intakes, specific microorganisms in saliva, and the prevalence and incidence of dental caries. The mean DMFS score detected in these subjects initially was 4.61, and they developed an average of 1.38 new DMFS during the first 17-month period. Initially, S. mutans and lactobacilli were detected in 64% and 56% of these subjects, respectively. Subjects with low levels of S. mutans and lactobacilli had significantly lower initial DMFS scores and developed significantly fewer new DMFS than subjects with high counts. The predictive values of a positive result for S. mutans or lactobacilli assays were low (31% and 39%), but those for a negative result were high (81% and 84%).

Adolescent↗
PubMed1988

Effects of rinses with an acidic calcium phosphate solution on fluoride uptake, caries, and in situ plaque pH in rats.

The effects of oral rinses on enamel fluoride uptake, caries, and plaque pH in rats were investigated by use of (1) an acidic calcium phosphate solution (CPS) saturated with dicalcium phosphate dihydrate (DCPD) and (2) a 1% fluoride solution. Osborne-Mendel rats, 19 days of age, were randomly assigned to one of four mouth-rinse treatment groups, with the two consecutively administered rinses being: H2O-H2O; H2O-F; CPS-H2O; and CPS-F. The treatments were administered on days 1 through 4, and the animals were provided with a cariogenic challenge throughout the study. The groups treated with F exhibited significantly higher mean levels of enamel-bound F than did the non-F groups. Furthermore, CPS significantly increased uptake of F by enamel when used as an adjunct to the F treatment. The caries scores of the CPS-F and H2O-F groups were not statistically different; however, a strong negative correlation was observed between enamel F content and caries scores, indicating that as more F was incorporated into the teeth, less caries formation occurred. Despite the significant differences in enamel F and caries scores among some of the treatment groups, post mortem in situ plaque pH drop in response to a sucrose rinse showed no differences among these groups.

Animals↗
PubMed1988

Periodontal disease in adolescents: some clinical and microbiologic correlates of attachment loss.

The influence of several clinical and microbiological variables on the site-specific risk of attachment loss was studied in Navajo Indian adolescents aged 14-19. Diagnoses were made at mesio-buccal sites of the four first permanent molars. Case-control analytical methods were used, with A. actinomycetemcomitans, B. gingivalis, and B. intermedius considered the "risk" variables, and with calculus, gingival bleeding, age, and gender treated as possible confounders. The presence of B. intermedius significantly increased the likelihood that attachment loss would be diagnosed at a site (odds ratio = 2.86). However, this association was confounded by calculus and gingival bleeding; when either or both were present, the effect of B. intermedius was markedly weaker. Step-wise multiple logistic regression analyses showed that, of the variables considered, the combination of calculus, gingival bleeding, and B. intermedius gave the most parsimonious explanation of the presence of attachment loss. The chance that attachment loss would be diagnosed was increased five times when calculus was present, 16.5 times in the presence of both calculus and gingival bleeding, and 37 times when these variables plus B. intermedius were observed at a particular site.

Actinobacillus↗
PubMed1988

Systematic errors in estimating prevalence and severity of periodontal disease.

Partial-mouth scores are often used in epidemiologic studies to estimate the prevalence and severity of periodontal disease. Such estimates systematically underestimate the prevalence of disease, but the bias can be in either direction for disease severity. Three large data sets containing full-mouth examinations (mesiobuccal, midbuccal, distobuccal, and midlingual (MBDL) sites per tooth) for either attachment loss or probing pocket depths were used to investigate the magnitudes of systemic error that occur by employing four specific partial-mouth scores (M, MB, MBD, and MBDL sites per tooth), which are based on the random half-mouth technique. For prevalence of disease the sensitivity of a partial score was a function of the disease level in the population. All four partial scores were sensitive enough to adequately portray true prevalence using the 2-mm demarcation value, the MBD and MBDL scores might still be considered adequate for the 4-mm value, but none of these partial scores were adequate for the 7-mm value. For disease severity the MBDL score produced unbiased estimates, the others were biased. The relative biases for the MB and MBD scores were all under 10% (in absolute value), but the M score produced severe relative biases, 24% for probing pocket depths and -12% for attachment loss.

Cross-Sectional Studies↗
PubMed1988

Regulation of enzyme levels in the blood. Influence of environmental and genetic factors on enzyme clearance.

Since its discovery, lactic dehydrogenase virus (LDV) has remained unique as a model of long-term enzyme elevation due to impairment of enzyme clearance. The present study shows that mice inoculated with silica develop an increase in plasma lactate dehydrogenase (LDH) lasting for at least 6 months and that the enzyme elevation is due, at least in part, to impairment of clearance. The extent of the enzyme elevation is dependent on both the dose and route of silica administration and mice that had received both silica and LDV showed a more profound impairment of LDH clearance than mice that had received silica or LDV alone. Examination of the factors that regulate circulating enzyme levels in normal mice revealed that whereas there was no difference in resting enzyme levels among several inbred strains of mice (BALB/cAnN, NZBWF1/J,B10.D2/nSnN, and A/J mice), when mice were stressed by the administration of an enzyme load, certain inbred strains (BALB/cAnN) cleared the enzyme rapidly and others (B10.D2/nSnN) cleared the enzyme slowly. Moreover, in B10.D2/nSnN mice, enzyme clearance was age-related. When different strains of mice were infected with LDV, LDH levels were substantially higher in the circulation of slow enzyme clearers as compared to rapid enzyme clearers. It is concluded that both environmental and genetic factors influence the clearance of LDH and that impairment of enzyme clearance may be a more important factor than previously suspected in regulating enzyme levels in disease states.

Animals↗
PubMed1987

Rest seat designs for inclined posterior abutments: a photoelastic comparison.

Forty-five photoelastic stress analyses were conducted with two-dimensional models of one side of a mandibular Kennedy class III removable partial denture. Fifteen separate rest seat configurations were tested for each of three varied inclinations of the distal second molar abutment. The data indicate that: Rest seat placement on an abutment tooth primarily affects stress concentration of that tooth. There is no direct relationship between rest seat design on one abutment and resultant stress on another. Inclined abutments demonstrate greater resultant bending of interradicular bone than vertical abutments, and the greater the inclination, the greater the bending (as the result of tipping force). Mesial rests on inclined molar abutments demonstrate maximum tipping forces. Channel rests on inclined molar abutments demonstrate the least amount of tipping force.

Bicuspid↗
PubMed1986

A procedure for evaluating the reliability of a gingivitis index.

A methodology is presented for assessing the reliability of an ordinarily-scaled index and is illustrated by using data from a clinical trial in which gingival inflammation was assessed with the PMGI index, independently, by 5 examiners. One of the examiners was an experienced examiner, the others newly trained. All subjects were evaluated by each examiner initially and at the end of the study period. The reliability of the average score per subject, maximum score per subject, and the % of affected sites per person are estimated by the intraclass correlation coefficient. Procedures are presented that utilize various forms of the weighted kappa statistic for dissecting patterns in examiner agreement for specific sites, types of site, all sites, and for the individual components and categories of the index. It is shown how these procedures can be useful for training and calibrating multiple examiners, who will be using such an index in a clinical study, so that adequate reliability levels can be realized.

Analysis of Variance↗
PubMed1986

The extent and severity index: a simple method for use in epidemiologic studies of periodontal disease.

Periodontal indices such as the PI, PDI and CPITN ignore a substantial amount of the information ordinarily available in epidemiologic studies of periodontal disease. The extent and severity index (ESI) is an attempt to preserve the maximum amount of information from a clinical examination consistent with the need to achieve a reasonable degree of data reduction. The ESI uses estimates of attachment level from probing measurements of 14 sites in one maxillary quadrant and 14 in the contralateral mandibular quadrant. The index is calculated to summarize jointly the extent and the average severity of disease within the group being studied. Application of this bi-variate statistic to a set of epidemiologic data was carried out to illustrate its use. This analysis suggested that disease extent and disease severity are not highly redundant measures and thus provide independently meaningful information. The ESI is a simple, reproducible method which appears to yield an informative description of the periodontal disease status of a population. Use of the index requires only minimal training of examiners. The index is intended to permit direct comparisons among epidemiologic studies of different populations and by different investigators.

Adolescent↗
PubMed1986

Prevalence of dental caries and dental fluorosis in areas with negligible, optimal, and above-optimal fluoride concentrations in drinking water.

The prevalence of dental caries and dental fluorosis was assessed in 1,123 children aged 8 to 16 years who were lifelong residents of areas with negligible, optimal, and above-optimal concentrations of natural fluoride in drinking water. Caries prevalence in the optimal fluoride area was 38.1% lower than it was in the negligible fluoride area, and, in the higher-than-optimal fluoride areas, even greater caries protection was evident. Caries protection was compromised in children with severe fluorosis. Findings do not support the contention that definite increases in the prevalence of fluorosis are occurring in communities with negligible and optimal water-fluoride concentrations because of increased total fluoride consumption from various sources.

Adolescent↗
PubMed1986

Three methods compared for determination of pancreatic and salivary amylase activity in serum of cystic fibrosis patients.

We evaluated three methods for serum amylase (EC 3.2.1.1) isoenzymes to determine whether they are interchangeable and to test their ability to discriminate between cystic fibrosis patients with and without pancreatic insufficiency. One method involved salivary amylase inhibitor (O), and two were polyacrylamide gel electrophoresis separations differing in method of detection--either direct zymogram (G) or gel slicing followed by activity estimates per slice (W). Results for percentage pancreatic amylase differed significantly. Reproducibility for percentage pancreatic amylase was high, moderate, and low (r = 0.95, 0.53, and 0.02) for methods G, O, and W, respectively; moderate (r = 0.60) among the three methods; and moderate between pairs. Therefore, this result for a subject must be considered relative to the method used in its determination. The clinical diagnosis of pancreatic insufficiency was verified by 77.8%, 83.3%, and 94.4% correct classification rates for methods O, W, and G, respectively. Evidently, method G is the most efficient and may be the method of choice for measuring serum amylase isoenzymes in cystic fibrosis.

Adolescent↗