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Biomedical subjects

D L Singer

Publications and source records attributed to D L Singer.

At least 19 recordsLinked to original sources
PubMed1992

Clinical evaluation of a light energy conversion toothbrush.

A blind, two-way crossover clinical trial was carried out to compare the effectiveness of plaque removal between a new, light energy conversion toothbrush incorporated with a semiconductor of TiO2 (test) and a similar toothbrush without the semiconductor (control). The study was completed by 73 school children aged 13-15 years. Each toothbrush was used for a period of 3 weeks. The mean differences between baseline plaque scores and after subjects used the test and control brushes were analyzed by the paired t-test. The Soladey 2 toothbrush showed significantly more reduction of plaque on the buccal surfaces of all teeth than the control brush. There was no significant difference in the plaque removing ability of the two brushes on the lingual aspects of the mandible and on the lingual surfaces of the maxillary posterior sextant. As the buccal surfaces are more likely to allow light to reach the semiconductor during brushing than the lingual areas, it is possible that the reported photocatalytic property of the semiconductor may be involved in some way in the observed reduction of plaque.

Adolescent↗
PubMed1992

Evaluation of a new periodontal curet. An in vitro study.

Removal of plaque and calculus from subgingival root surfaces is a fundamental aspect of periodontal therapy. A new type of periodontal curet (Gracey Curvette Sub-0) has been designed to better adapt to the root surfaces that may be encountered in periodontal pockets of incisor teeth. The new curet (test) was compared to a Gracey curet 1/2 (conventional) in their ability to remove deposits from the subgingival root surfaces of incisor teeth in an in vitro model. A dentiform model mounted on a dental chair was used with artificial gingiva, 6 mm pocket depths and subgingival root surfaces covered with black enamel paint. 2 groups of 12 hygienists used, on a timed basis, either the test or conventional curet on 4 of the incisor teeth and then switched to the alternate instrument for the remaining four incisors. The extent of surface material removal was determined using a computerized video routine. The test curet removed significantly (p less than 0.001) more of the surface material from all subgingival incisor root surfaces than the conventional curet (60.7% versus 46.3%). Both instruments were most effective at labial surfaces. The test curet was least effective at proximal surfaces and the conventional curet least effective at lingual surfaces. The greatest statistical difference between instruments was apparent at lingual surfaces of maxillary incisors and the least at mesial surfaces of mandibular incisors.

Alveolar Bone Loss↗
PubMed1992

An imaging routine for assessing the efficacy of instruments used for scaling and root planing.

Deposits of dental plaque or calculus are typically quantified using planimetric techniques. However, error is introduced into a quantitative analysis of plaque deposits using these methods, since they require a significant amount of human intervention. The purpose of this study is to describe and validate a computerized imaging routine which has the potential to objectively identify material on dental roots and measure the area covered by these deposits. Dentiform teeth with simulated plaque were videorecorded. A computer routine was developed based on a flood-fill algorithm which analyzed images of the dentiform teeth and determined the amount of simulated plaque on their root surfaces. Results showed that the dentiform teeth and their simulated plaque patterns are duplicated by the imaging routine in a rapid and reliable fashion. The system shows a high degree of accuracy with an average error factor of only 0.58%. As well, the system enables precise reproducibility with an average error factor of only 0.71%.

Algorithms↗
PubMed1989

Tooth loss in a selected population in Saskatoon.

Tooth mortality in a population can provide information about the prevalence of dental disease, availability of dental care and attitudes about tooth extraction. The tooth mortality of patients presenting for treatment at the University Dental Clinic (Saskatoon, Canada) during the school terms 1981-1986 was determined to provide base-line data during a time when the dentist-to-population ratio has been increasing, and to compare the results with similar studies carried out in Britain and Greece. The data were analyzed according to the same quinquennial age groups as in the other studies. There were no statistically significant differences between the two time periods at all ages and therefore the data were pooled. Totally edentulous persons were excluded from the analysis for comparison purposes. The prevalence of tooth loss increased with age with a rapid period of tooth loss encompassing the mean ages of 34 to 47 years, a slowing of further loss up to the mean age of 62 and thereafter, a further increase. The initial rapid loss was most apparent for molar teeth and least apparent for mandibular incisor teeth. With the exception of first molars, more teeth were lost in the maxilla than in the mandible. The present data are similar to the findings reported in British and Greek studies.

Adolescent↗
PubMed1989

Periodontal surgery: what's new?

An overview of newer periodontal surgical techniques is provided. Procedures which are being used to replace or regenerate periodontal attachment tissues or to restore the normal surface appearance of the periodontium are briefly described.

Alveoloplasty↗
PubMed1989

The student survey of problems in the academic environment in Canadian dental faculties.

A survey of problems related to stress encountered by 1,255 Canadian dental students was conducted. Substantial experience with problems was reported infrequently, although most students were affected negatively by at least one problem. Most difficulties concerned students' doubts about harnessing their efforts and abilities to master large amounts of material, which, of necessity, reduced their opportunity to pursue other interests. Few demographic features predicted the level of students' problems, although there was an indication that those who perceived themselves above average academically reported fewer problems.

Adult↗
PubMed1983

A comparison of the acid-base metabolisms of pooled human dental plaque and salivary sediment.

The acid-base metabolisms of the mixed bacteria in pooled dental plaque and salivary sediment sampled from the same subjects were compared in vitro. Plaque at a suspension concentration of 8.3 per cent (v/v) was found to produce pH responses like those of sediment at 16.7 per cent (v/v) with all substrates and under all incubation conditions tested. The substrates examined included several carbohydrates (glucose, sucrose and starch) and several nitrogenous substrates (urea, arginine and the arginine peptide glycyl-glycyl-lysyl-arginine also called sialin). Also examined were the effects of endogenous substrates and of salivary supernatant and fluoride. A difference in suspension concentration was necessary to achieve similarity in pH response which was attributed to the presence of more non-viable epithelial cells in sediment than in plaque. Under these conditions, salivary sediment showed a slightly greater buffering capacity than plaque, a difference that was not evident if salivary supernatant was present. It was clear from this study that salivary sediment and pooled dental plaque from the same subjects have similar acid-base metabolisms and that the more abundant and readily available sediment could be used to study such metabolism in dental plaque.

Arginine↗
PubMed1983

The free amino acids in human dental plaque.

Analysis of plaques from maxillary and mandibular incisors for free amino acids showed that the dicarboxylic amino acids, glutamic and aspartic, were present in largest amounts, with glutamic acid comprising at least 50 per cent of the total pool. Other amino acids in decreasing order of prominence included proline, ornithine, alanine, lysine, glycine, threonine and serine. This pattern was basically the same in the plaques from the different incisor sites but was clearly different from those of hydrolysates of either the plaque bacteria or the plaque matrix. The results were consistent with the most prominent plaque-free amino acids being associated mainly with the intermediary metabolism of the plaque bacteria. Urea and glucose were then applied to plaque in vivo in the form of rinses to determine if during their metabolism any of the plaque amino acids are affected. Glutamic- and aspartic-acid concentrations both rose after plaque exposure to urea accompanied by a small rise in alanine. After glucose exposure, aspartic- and glutamic-acid concentrations both showed large decreases and alanine showed a small increase. With glucose plus urea, glutamic acid rose and fell, aspartic acid decreased slightly and alanine increased several fold. In each case, the other free amino acids showed little or no change. Thus glutamic and aspartic acids are major components of the intra-cellular pool of amino acids and probably play an important role in alanine synthesis, presumably by facilitating transamination of pyruvate.

Adult↗
PubMed1983

Quantitative assessment of urea, glucose and ammonia changes in human dental plaque and saliva following rinsing with urea and glucose.

The rates of three processes associated with the rise and fall in plaque pH, that normally occur following a urea rinse, were determined: (i) disappearance of urea from plaque, (ii) disappearance of urea from saliva and (iii) formation and disappearance from plaque of the ammonia produced by the plaque bacteria from the urea. Also examined were two processes associated with the fall and rise in pH following a glucose rinse: the disappearance of glucose from plaque and from saliva. Entry into plaque of either urea or glucose during rinsing was immediate; the subsequent disappearance of both from the plaque was slow and followed first-order kinetics. The ammonia formation and urea-disappearance results suggested that clearance of urea from the plaque occurred mainly by bacterial degradation and not by diffusion out of the plaque. The rate constants for ammonia formation and for its subsequent disappearance from the plaque made it clear why a rapid rise and a slow subsequent fall in the pH occurs after urea rinsing. The rate constants enabled calculation of the ammonia produced as a percentage of the urea utilized. Only 16-26 per cent of the urea was recovered as ammonia and the remainder of the urea-N was stored probably as NH2 moieties of certain amino acids. Such storage may enable the plaque bacteria to maintain the pH at an elevated level for an extended period of time by bacterial production of ammonia from these stored compounds after the urea ceases to be available as a source of substrate.

Ammonia↗