Ingrid Guo - Academia.edu (original) (raw)

Papers by Ingrid Guo

Journal of Dental Research, Nov 1, 1994

For the past ten years, the amounts of mercury vapor released from dental amalgams and the possib... more For the past ten years, the amounts of mercury vapor released from dental amalgams and the possibility of side-effects caused by these amounts have been discussed. Although no adverse health effects have been substantiated from these minute amounts, besides rare cases of allergies, this release should be reduced. The aim of this study was to reduce the mercury evaporation from a high-copper amalgam during setting by triturating the alloy powder with binary Hg-In liquid alloys having various indium concentrations set at 0, 5, 10, 20, 30, 40, and 50 wt%. Specimens (n = 4) were made for each amalgam according to ANSI/ADA Specification #1 and placed into a measuring chamber kept at 36.5 +/- 0.5 degrees C, through which a continuous air flow of 0.75 L/min was pumped. The total mercury release was measured during the setting period, according to the method described by Ferracane et al. (1992). Four additional specimens were prepared from a modified 14% Indisperse amalgam powder for the purpose of comparison. The results showed that the release of mercury vapor decreased with increasing indium concentrations, and that the amalgams made with the Hg-In liquid alloy with 10% In or more released significantly less mercury than the modified 14% Indisperse. The method of mixing indium in mercury prior to trituration appeared to be another effective method for reducing mercury evaporation during setting. The reduced mercury release may be explained by a reduction of mercury concentration in the structure, a reduction of vapor pressure for the mercury in the matrix phases, or more efficient formation of a surface oxide layer.

PubMed, May 1, 1994

Tracking refers to regular, predictable growth behavior. Most definitions of the term are related... more Tracking refers to regular, predictable growth behavior. Most definitions of the term are related to the idea that tracking occurs to the extent that individuals' repeated measurements maintain their relative positions in the distribution of the measurement whose growth is being monitored as that distribution changes over time. In this paper we describe four indices of tracking, all due to McMahan (Biometrics, 37 (1981) 447-455), which may be used to measure the extent to which a given longitudinal sample exhibits this 'regular behavior,' and we provide a program, written in GAUSS386i, for performing the associated computations. An example is given, and the values of McMahan's indices are compared to several alternative measures of tracking.

Journal of the American Dental Association, Dec 1, 1998

The authors designed a pilot study to examine issues that affect women's oral health. They fo... more The authors designed a pilot study to examine issues that affect women's oral health. They found a substantial lack of awareness regarding important oral health issues, and that 44 percent of the participants reportedly did not have regular dental care. High perceived dental need was reported concurrently with low dental care attendance. Additionally, reported lack of dental insurance and self-perception of low income and of poor dental health were important explanatory factors for the women who reportedly did not have regular dental care.

Journal of Dentistry, Dec 1, 1993

The handling characteristics of a gallium alloy (Gallium Alloy GF) were compared to those of a sp... more The handling characteristics of a gallium alloy (Gallium Alloy GF) were compared to those of a spherical high-copper amalgam (Tytin). Ten dentists each restored four identical MO preparations in acrylic typodont teeth (no. 30), two with amalgam and two with gallium alloy. Each restoration was evaluated immediately following completion by the operator for six clinically relevant criteria. Each criterion was scored between 1 and 5, where 1 = very poor. 2 = poor, 3 = fair, 4 = good, and 5 = very good. Three two-sided Mann-Whitney tests were used to compare the median scores for significant differences (P < 0.05). The first test indicated no significant difference between scores for the first-and second-placed restorations, within criteria and within alloy type (n = 10). The second test indicated a significant difference between amalgam and gallium alloy, within criteria and within restoration sequence (n = 10). for each criterion except resistance to fracture during removal of the matrix band. The third test indicated a significant difference between amalgam and gallium alloy, within each criteria, combining scores for first-and second-placed restorations (n = 20). During simulated clinical placement, amalgam was rated significantly higher than gallium alloy in each handling characteristic evaluated.

American Journal of Public Health, 1994

International Journal Of Medical Informatics, Jul 1, 1994

Two stand-alone, menu-driven PC programs, written in GA USS386i, which compare groups of growth c... more Two stand-alone, menu-driven PC programs, written in GA USS386i, which compare groups of growth curves in a completely randomized design using either (a) exact or (b) approximate randomization tests, are described, illustrated, and made available to interested readers. The programs accomodate missing data in the context of studies planned to have common times of measurement, but where some of the measurement sequences are incomplete. The measurement whose growth is being monitored need not have a Gaussian distribution. We consider the hypothesis that the mean growth curves in G groups are the same; and either compute the exact P value (exact test), or estimate, and provide a confidence interval for, the P value (approximate test).

Journal of Dental Research, 1994

International Journal of Bio-Medical Computing, 1994

We consider the problem of growth prediction in the context of the two-stage (or random coefficie... more We consider the problem of growth prediction in the context of the two-stage (or random coefficients) one-sample polynomial growth curve model and provide a PC program, written in GAUSS386i, to perform the associated computations. The problem considered is that of estimating the value of the measurement under consideration for a 'new' individual at the Tth time point given measurements on that individual at T-1 previous points in time and the values of the measurement on N 'similar' individuals at all T time points. The times of measurement t,, t2,. .. , t, need not be equally spaced, but we assume that each of the N individuals comprising the normative sample were measured at these times. The method and the program are illustrated using the data set previously considered (Schneiderman and Kowalski, Am J Phys Anthrop, 67 (1985) 323-333) consisting of mandibular ramus height measurements (in mm) for 12 male rhesus monkeys at T= 5 yearly intervals (coded 1, 2, 3, 4, and 5). Results are compared with those obtained under a less restrictive set of assumptions concerning the covariance matrix of the observations than is made in the context of the twostage model. It is seen that the accuracies of prediction of the two methods, for this and other data sets, are quite close, suggesting that the less restrictive model may be preferred in many situations.

American journal of dentistry, 1997

To assess the handling characteristics of a gallium alloy triturated with one drop (10 microL) of... more To assess the handling characteristics of a gallium alloy triturated with one drop (10 microL) of ethyl alcohol and compare them to those of a high-copper amalgam. A commercial gallium alloy (Gallium Alloy GFII) and a high-copper amalgam (Tytin) were used. Ten dentists each restored four identical MO preparations in acrylic typodont teeth (two for each material). Each restoration was immediately evaluated by the operator for placement, condensation, proximal contact, carving, and resistance to fracture during matrix removal and overall quality according to a method used previously. The rating scale for each criterion ranged from 1 (very poor) to 5 (very good). Scores for each criterion for the amalgam and gallium alloy restorations were statistically compared. The gallium alloy tested was still rated significantly worse (P < or = 0.05) than amalgam for placement, condensation and carving but there were no significant differences in scores for other criteria. The dentists judged t...

International journal of bio-medical computing, 1994

A PC program, written in GAUSS386i, implementing Zerbe's (Growth, 43 (1979) 263-272) procedur... more A PC program, written in GAUSS386i, implementing Zerbe's (Growth, 43 (1979) 263-272) procedure for diagnosis on the basis of longitudinal data is described, illustrated and made available to interested readers. Given longitudinal observations on N normal individuals, this technique can be used to characterize normal growth, velocity and acceleration, and to determine whether or not a new individual can be considered normal with respect to any or all of these parameters. Missing data are allowed, and there is no requirement that the variable whose growth is being monitored has a normal distribution. The method and program are illustrated using a data set with a substantial amount of missing data. Information on obtaining a copy of the program and hardware requirements are given in the Appendix.

Special Care in Dentistry, 1997

Journal of the American Dental Association, 1995

Journal of Public Health Dentistry, 1998

Objective: This paper describes trends in oral and pharyngeal (O/P) cancer diagnoses in Departmen... more Objective: This paper describes trends in oral and pharyngeal (O/P) cancer diagnoses in Department of Veterans Affairs (VA) hospitals from 1983 to 1993 and compares these trends to those of laryngeal and lung cancers. Methods: The VA patient treatment file was used to identify unique hospital discharges from 1983 to 1993 having ICD‐9‐CM codes for O/P, laryngeal, and lung cancers. Descriptive statistics were tabulated to determine prevalence and distribution. Trends of change over time were analyzed using regression analyses of the percent rate on year. Results: Between 1983 and 1993 the annual number of O/P cases among users of VA hospitals decreased from 4,983 to 3,298. Despite overall declines in O/P cancer discharges in VA, cancer of the pharynx, tongue, and salivary gland continues to increase. O/P cancer in younger persons also continues to increase in VA. Overall, laryngeal cancers significantly increased, while no significant change was associated with lung cancer. Conclusion...

Computers in Biology and Medicine, 1994

Dawson et al. (Am. 1. Med. Genet. 7, 529-536, 1980) developed a procedure for constructing confid... more Dawson et al. (Am. 1. Med. Genet. 7, 529-536, 1980) developed a procedure for constructing confidence bands for both average and individual growth curves which may be of considerable value in the study of growth and development. This paper describes their method for constructing, and provides a menu-driven GAUSS386i program for computing these confidence bands. It is demonstrated how these bands are useful for both the diagnosis and prognostication of growth patterns with known levels of confidence. It is assumed that the study is planned so that individuals will be measured at the same times, but missing data are allowed.

The Journal of the American Dental Association, 1998

Women's health issues have been central to the national health agenda during the 1990s. 1-5 With ... more Women's health issues have been central to the national health agenda during the 1990s. 1-5 With one of its primary goals being facilitating the transfer of practical information to help women preserve their health, the National Institutes of Health, or NIH, formed the Office of Research on Women's Health in 1990. 1-3 Throughout the decade, several conferences focused on women's health, including one on women's oral health research sponsored in 1993 by the International Association for Dental Research. Oral health care professionals, who strive to improve and preserve the oral health of all patients, can benefit from the issues brought forward as part of these initiatives. In a comparison of data from the National Survey of Oral Health in U.S. Employed Adults and Seniors, 1985-86, on conditions such as tooth loss, caries and periodontal diseases, neither men nor women were found to have better overall oral health. 6 Meanwhile, although U.S. women report engaging in good oral health practices more often than do men, 7 surprisingly, we are not seeing a marked improvement of women's oral health when compared with that of men. 8 Certain conditions can cause an increase in the incidence and severity of oral diseases in women. For example, changes in the periodontium appear to be more exaggerated in women, a fact that could be attributed to hormonal differences between women and men and also could be the result of exaggerated responses to oral bacteria in women. 9 Additionally, women are more likely to be diagnosed with diseases such as Sjögren's syndrome, burning mouth syndrome, temporomandibular disorder, myofascial pain and eating disorders. 5,8,10 Of concern is the increasing number of young women who smoke. Currently, 26 percent of women aged 12 to 21 years smoke. 11 Women are more likely than men to begin smoking and less likely to quit. 12 This information has led to a prediction that in a few years, there will be more female than male smokers in the United States. 8 Although it has been suggested that the slight increase in the incidence of oral cancer among women 12 is not statistically significant at this time, 13 the death rates due to all smoking illnesses are rising rapidly among women. 14

International journal of …, 1995

Potthoff and Roy (Biometrika, 51 (1964) 313326) generalized the multivariate analysis of varianc... more Potthoff and Roy (Biometrika, 51 (1964) 313326) generalized the multivariate analysis of variance model into a form that is especially useful for the study of longitudinal growth curve data. Applications of this method have, however, been limited by the requirement that each case in the ...