Howard M. Proskin

Comparison of the Iodide Permeability Test, the Surface Microhardness Test, and Mineral Dissolution of Bovine Enamel following Acid Challenge

The relationship among the iodide permeability (Ip) test, the surface microhardness (SMH) test, and enamel demineralization chemically analyzed as mineral loss was investigated using bovine enamel blocks. Demineralization periods of 0 (control) and 5, 15, 30, and 45 min using 0.05 mol/l lactate (pH 4.75) were chosen to approximate the acid challenge occurring during the intraoral enamel demineralization test. Mineral loss (Ca and PO4) was found to be directly proportional to dissolution time (r = 0.95). Changes (delta) in Ip and SMH each increased linearly over time (r = 0.58 and 0.64, respectively) and were similarly related to mineral loss (r = 0.60 and 0.65, respectively). The correlation between delta Ip and delta SMH was 0.55. When longer demineralization periods (60, 120, and 240 min) were included, the correlation between delta Ip and delta SMH was 0.68. We conclude that both the Ip test and the SMH test can be used as measures of the early stages of enamel dissolution.

Caries Risk Assessment in a Longitudinal Discrimination Study

Our objective was to develop and perfect a model for the assessment of risk of dental caries onset in children. Even though dental caries prevalence in children is continuing to decline, there is still a significant minority for whom it is a problem. In this study, we sought to ascertain whether a set of variables selected in a previous cross-sectional study could be used to differentiate between caries-free six-year-olds who would or would not subsequently present with clinically-detectable caries. A total of 472 caries-free six-year-olds—286 from a fluoridated community and 186 from a fluoride-deficient community-was selected. Clinical examinations for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride, calcium, and phosphate concentrations. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of linear discriminant analyses, it was possible to predict correctly which children would develop caries within six to 12 months (sensitivity) in 82.8% of cases and which children would not develop caries during that period (specificity) in 82.4% of cases.

Effect of Chewing Xylitol Chewing Gum on Salivary Flow Rate and the Acidogenic Potential of Dental Plaque

Ten adults participated in the study which consisted of four experimental periods each lasting 2 weeks, during each of which subjects were assigned to one of four gum-chewing regimens: no gum, sucrose gum, sorbitol gum and xylitol gum. At the start and end of each test period unstimulated and stimulated salivary flow rates were determined. At the end of each test period the acidogenic potential of 48-hour dental plaque was measured using a Beetrode pH microelectrode. No statistically significant (p < 0.05) effect on salivary flow rate was observed. The xylitol chewing gum regimen resulted in significantly higher plaque pH than no gum, sucrose gum and sorbitol gum at 2, 10, 20, 30 and 60 min following a 10% sucrose rinse. In addition, xylitol gum regimen exhibited a significantly higher minimum pH and smaller area of the curve below pH 6. The results suggest that the regular use of xylitol-sweetened gum may serve to reduce the acidogenic potential of dental plaque.

Randomized Clinical Trial of the Effect of Prenatal Fluoride Supplements in Preventing Dental Caries

This randomized, double-blind study tested the caries-preventive efficacy of prenatal fluoride supplementation in 798 children followed until age 5. Initially, 1,400 women in the first trimester of pregnancy residing in communities served by fluoride-deficient drinking water were randomly assigned to one of two groups. During the last 6 months of pregnancy the treatment group received 1 mg fluoride daily in the form of a tablet and the control group received a placebo. Both treatment and control subjects were encouraged to use postnatal dietary fluoride supplements. Caries was measured in children at age 3 and 5 while fluorosis was assessed at age 5. Caries activity was very low in both study groups: 92% of children remained caries-free in the treatment group and 91% remained caries-free in the placebo group. Fluorosis was observed in 26 subjects, all classified as very mild. Overall, there were no statistically significant differences in the study groups with respect to caries and fluorosis in deciduous teeth. The study had sufficient power to detect an absolute risk reduction of 5.1% while only a 1.5% reduction was observed. These findings do not support the hypothesis that prenatal fluoride has a strong caries-preventive effect.

Caries Risk Assessment by a Cross-sectional Discrimination Model

Although the prevalence of dental caries is continuing to decline, it still affects a majority of the US population and can be a serious problem for those afflicted. The objective of this project was to develop and perfect a model for assessment of risk of dental caries onset in children. In the first study, reported herein, a set of clinical, microbiological, biochemical, and socio-demographic variables was identified that distinguished, with an acceptable level of sensitivity and specificity, between children who had no previous caries experience and children who had high caries levels. A total of 313 children-age 12-15 years, 140 from a fluoridated community and 173 from a fluoride-deficient community-was selected on the basis of previous caries experience, either zero DMFS or high DMFS (> 6 in the fluoridated or ≥ 8 in the fluoride-deficient community). Clinical exams for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride concentration. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of discriminant analyses, with use of seven key clinical and laboratory variables, it was possible for zero-DMFS subjects to e classified correctly (specificity) in 77.6% of cases in the fluoridated community and in 86.1% of cases in the fluoride-deficient community. High-caries subjects were classified as such (sensitivity) in 79.3% and 88.1% of cases, respectively.

Magnetic resonance imaging findings in asymptomatic volunteers and symptomatic patients with temporomandibular disorders

Internal derangement has been suggested to be a cause of temporomandibular disorders. This study compared magnetic resonance imaging findings in 82 asymptomatic volunteers and 263 symptomatic patients. Disk displacement was observed in 33% of the asymptomatic volunteers and 84% of the symptomatic patients. The prevalence of trauma, headache, and other joint problems was more common in symptomatic patients. A history of general anesthesia and orthodontic treatment was not increased in the symptomatic population compared with asymptomatic volunteers. This study suggests that disk displacement is more common in symptomatic subjects.

Correlations between Numbers of Microf lora in Plaque and Saliva

An epidemiologic investigation to reliably identify caries-susceptible subjects by microbiological and chemical assessment of plaque and saliva is currently in progress. As part of that study, the numerical relationships of mutans streptococci, lactobacilli and total viable microflora in plaque and saliva among 12- to 15-year-old children in a fluoridated community were determined. Paraffin-stimulated whole saliva and pooled dental plaque were collected. Each sample was suspended in reduced transport fluid, chilled on ice, and assayed. The bivariate normal distribution was found to be a suitable model for the distribution of the pairs [numbers of bacteria in plaque (log10), numbers of bacteria in saliva (log10)]. Statistically significant positive correlations were found between numbers of mutans streptococci in plaque and saliva, and between lactobacilli in plaque and saliva.

Dimensional accuracy of denture resin cured by microwave energy.

Microwave processing has several time-saving advantages over conventional processing of denture base resins. Little is known about the adaptation of bases processed by microwave radiation to the cast and the mouth. Comparisons were made in five regions of the palate and ridge. The microwave-processed denture bases had equal or better dimensional accuracy than conventionally processed bases.

MR fat suppression technique in the evaluation of normal structures of the knee.

The chopper fat suppression (CFS) pulse sequence, which is a phase sensitive implementation of the Dixon fat suppression method and the spin echo (SE) pulse sequence, was used in the evaluation of anatomic structures of the normal knee using 48 sets of imaging sequences in six volunteers using a repetition time/echo time combination of 1,500/30, 60 ms. A demonstration of the CFS technique in 10 patients with suspected knee pathology is also presented. A semiquantitative grading scale was established to rate anatomic visualization and used to compare CFS and SE pulse sequence techniques. The results in normal subjects demonstrate that hyaline cartilage is significantly better visualized by fat suppression pulse sequence than by conventional SE pulse sequence in the coronal and sagittal planes of imaging (p < 0.001). The preliminary results from patient studies suggest that CFS imaging may be useful in the evaluation of meniscal tears, in the differentiation of hyaline cartilage from joint fluid, and in the detection of both soft tissue and bone injuries.

Effectiveness of a calcium sodium phosphosilicate containing prophylaxis paste in reducing dentine hypersensitivity immediately and 4 weeks after a single application: a double‐blind randomized controlled trial

Aims The aim of this single-site, randomized, controlled, double-blind, 3-arm parallel study was to determine the effectiveness of a prophylaxis paste containing 15% calcium sodium phosphosilicate (CSPS; NovaMin®) with and without fluoride in reducing dentine hypersensitivity immediately after a single application and 28 days following dental scaling and root planing. Materials & Methods Overall, 151 subjects were enrolled in this study. All subjects received a scaling and root planing procedure followed by a final prophylaxis step using one of three different prophylaxis pastes: Test-A (15% NovaMin® and NaF), Test-B (15% NovaMin®) and a control. Dentine hypersensitivity was assessed by tactile stimulus (Yeaple Probe®) and by air blast (Schiff scale) at baseline, immediately after and 28 days after a prophylaxis procedure. One hundred and forty-nine subjects completed the study. Results Subjects having received the test prophylaxis pastes showed statistically lower (anova, p < 0.05) dentine hypersensitivity compared with the control group immediately after the prophylaxis procedure (Yeaple Probe®: Test-A = 20.9 ± 12.6, Test-B = 22.7 ± 12.9, Control=11.2 ± 3.1; Schiff score: Test-A = 1.1 ± 0.6, Test-B = 1.1 ± 0.6, Control = 2.0 ± 0.7) and after 28 days (Yeaple probe: Test-A = 21.5 ± 11.9, Test-B = 20.6 ± 11.3, Control = 11.8 ± 6.0; Schiff score: Test-A = 1.0 ± 0.6, Test-B = 1.0 ± 0.6, Control = 2.0 ± 0.7). Conclusions In conclusion, the single application of both fluoridated and non-fluoridated prophylaxis pastes containing 15% CSPS (NovaMin®) provided a significant reduction of dentine hypersensitivity up to at least 28 days.