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Biomedical subjects

D W Lewis

Publications and source records attributed to D W Lewis.

At least 19 recordsLinked to original sources
PubMed1992

What was wrong with Tiny Tim?

One of the most endearing characters in English literature is Tiny Tim, the crippled son of Ebenezer Scrooge's clerk, Bob Cratchit. Yet the nature of Tiny Tim's multifaceted and implicitly reversible illness is a mystery and open to debate and speculation. From details of the original manuscript and the eight film versions, it is possible to construct a differential diagnosis for Tim's short stature, asymmetric crippling disorder, and curious intermittent weakness that would lead to his death, if untreated, within a period of 1 year. Following the ghostly visitations, Scrooge vows to assist the struggling Cratchit family financially, thereby making available the best medical care money could buy. From review of pediatrics texts from 1830 to 1850, a recommended treatment plan would have included (1) general measures such as country air and exercise, and fish oils such as cod and halibut (vitamin D), and (2) specific treatments of tonics (containing combinations of belladonna, opium, sodium bicarbonate, sodium citrate, and potassium chloride) emphasizing alkalis, and splinting and bracing the limbs. Such treatments with vitamin D and alkalinization with sodium bicarbonate and sodium citrate suggest the plausible speculation that Tiny Tim had renal tubular acidosis (type I), a disorder that is characterized by growth failure and, if left untreated, complicated by osteomalacia with pathologic fractures, hypokalemic muscle weakness and periodic paralysis, nephrocalcinosis leading to renal failure, and death. I propose that Tiny Tim had distal renal tubular acidosis (type I).

Acidosis, Renal Tubular↗
PubMed1992

Utilization in Alberta's universal dental plan for the elderly, 1974-91.

Since 1973 the government of Alberta, a Canadian province of 2.4 million people, has funded a dental care plan for all residents over 64 years old and their dependents. It is the only dental plan in North America that covers all seniors and their dependents residing in a state or province. Under this plan, just over 270,000 persons (in 1990-91) are eligible for comprehensive, premium-free dental services provided by dentists and denturists in private practice on a fee-for-service basis. The plan's design, administration, utilization, and costs are reviewed. Utilization increased from 27 percent of eligibles using the plan in 1974-75 to 44 percent in 1990-91, and the mean number of services per user rose from 4.9 to 6.9 during the same time period. Although the cost per eligible person has increased about 200 percent, from Canadian (C) $42 to C $131, these costs only began to exceed the rate of inflation in 1986-87. Even though just 12 percent of the two main providers participating in the plan are denturists, nearly 22 percent of plan patients attended denturists rather than dentists for their complete dentures. Fees paid to dentists by the plan have decreased over time relative to the standard fees for the various services listed annually in the Alberta Dental Association fee guide. The apparent growth of direct additional billing by dentists of plan users to recover the difference between their usual fees and those paid by the plan and the effects of greater plan utilization are discussed, as are future potential difficulties in the plan's administration.

Aged↗
PubMed1992

Dental implants and decision making.

Treatment choice and effectiveness in prosthodontics has largely depended on educated anecdote and asseveration. Still, this approach has to a very large extent enabled dentists to enrich the quality of their patients' lives. However, the trade-off between the need for prosthetic intervention per se and the biologic price inherent in certain therapeutic endeavors has demanded strict concerns regarding clinical decision making and treatment outcomes. The technique of implant prosthodontics is certainly one that has focussed such concerns, particularly since the concept of osseointegration was introduced to North American dentists at the 1982 Toronto Conference. Clinical research and opinion in this area have elicited both clinical euphoria and polarization vis-a-vis newer possibilities for resolving the predicaments of partial or complete edentulism. The past decade has witnessed clinical trials, as well as highly relevant exemplary reports, on the application of the osseointegration technique. It is now necessary to compare the merits of implant prosthodontics to traditional therapies, and to determine those criteria which comprise optimal functional and aesthetic restoration, with minimal risk of morbidity, along with cost concerns. This paper seeks to provide a systematic and rational basis for the identification of such criteria.

Contraindications↗
PubMed1991

A statistical assessment of orthodontic practices, product usage, and the development of skin lesions.

Recently there has been great interest in skin lesions on the hands of orthodontic personnel who are exposed to a wide variety of metals, bonding agents, and other materials. Thus this 1985 national survey of 448 Canadian orthodontists (response rate 49%) was undertaken to examine orthodontic practice activities, bonding agent and wire product use, and prevalence of skin lesions on the hands and their possible association with these products. About 13% of the 213 responding orthodontists and at least one other staff member in 18% of the orthodontic practices reported the occurrence of hand lesions (reactions) over the preceding 3 years typical of exposure to dental materials. In nearly one fourth of the offices, at least one person was affected. Regarding product use. Concise, Mono-Lok, and Endur bonding agents and stainless steel, Nitinol, and Elgiloy wires were used most often. The orthodontists reported frequent involvement in bonding activities and infrequent use of gloves. Of all the individual and combined materials and practice characteristics and activities tested singly and multivariately for statistical association with hand lesions, only the orthodontists' use of Mono-Lok, gloves, and the activity of frequently cleaning excess bonding agent were statistically related to the lesions. Multiple logistic regression suggested that the statistical effects of Mono-Lok use and removal of excess bonding agent were independent; thus removal of excess agent may have consequences for lesion development separate from Mono-Lok use.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1991

Comparison of self-instruction methods for teaching diagnostic testing.

In a randomized controlled trial, self-teaching booklets and computer media were evaluated for teaching diagnostic testing to dental students as a foundation for further development of clinical decision making skills. Effectiveness was assessed by pre- and post-tests. Reliability of these test instruments was examined by analyzing the pre- and post-test scores of 49 first year dental students who received no instruction. Forty-one second year dental students were exposed to clinical epidemiological principles applied to endodontic diagnosis through either self-teaching booklets or computer media. No statistically significant difference was found between the mean test scores of the students through self-teaching booklets and computer media. Although first and second year students showed a statistically significant improvement between the pre-test and post-test, the improvement in the second year class was greater. An addendum was later made to the main trial to compare the self-teaching booklet to the traditional lecture format in teaching endodontic diagnosis. Seventy-one third year dental students were exposed to these same materials through either a lecture or the self-teaching booklet and then similarly tested. There was no significant difference between the self-teaching booklet and traditional lecture for the third year students.

Computer-Assisted Instruction↗
PubMed1990

Retention and maintenance of fissure sealants over 10 years.

The long-term efficacy (retention and caries prevention) of fissure sealants is well documented. However, the effectiveness of contemporary sealants under sometimes less than ideal field conditions is not so well reported, nor are the clinical issues of the long-term extent of partial sealant loss, resealing needs and sealant replacement under such conditions. The results of a 10-year follow-up of 8,340 chemically-cured sealants placed between 1978 and 1985 in selected "high-risk", first permanent molars of children of moderate to severe decay susceptibility are presented. These children were annual participants in the Prince Edward Island Children's Dental Care Program. Complete sealant retention was 89 per cent after one year and 60 per cent after 7-9 years. One year after insertion, 6 per cent of sealants required maintenance resealing; thereafter it was 2 per cent to 4 per cent per year. Sealant removals because of MO amalgam placement or occlusal decay were very low, about 2 per cent and 1 per cent, respectively, in each of the first five years. The overall annual sealant success of 96 per cent after one year and 85 per cent after 8-10 years supports the careful application of chemically-cured sealants under field conditions and the use of annual recalls to allow minimal sealant maintenance.

Adolescent↗
PubMed1977

Epidemiology of dental caries in the premolar and second molar teeth of Scottish children in relation to pits and fissures.

To evaluate the potential benefits from elimination of dental caries in the fissures of teeth, surface patterns of decay were calculated for all surfaces of the premolar and second molar teeth of 98 children followed longitudinally for 5 years, between ages 11 and 15 years. Tooth eruption and susceptibility were also examined in relation to the administration of sealant programs. The children who were part of the control group of a fluoride dentifrice study on the Scottish Isle of Lewis, had low exposure to fluorides, high caries attack and very low restorative treatment levels; so true surface caries distribution was not masked. Variation in tooth eruption and susceptibility suggested that semiannual applications of preventive agents at each year age 10 through 15 might be required. Using hypothetical percentage reductions, the substantial potential benefits for caries control of the early use of completely retained occlusal, as well as buccal and lingual (molars), fissure sealants are conclusively demonstrated. However, improvements in the present technology of fissure sealants and their application are apparently required if these benefits are to be extended to large groups of children.

Adolescent↗
PubMed1976

Effect on caries of self-application of a zirconium silicate paste containing 9% stannous fluoride.

A 2-year clinical trial was conducted using an adolescent population from a low-fluoride area to evaluate the anticaries effect of self-applications of zirconium silicate paste containing 9% stannous fluoride. tthree study groups totaling 464 children, with an initial average of 12.8 years, completed the study. The control group brushed with a non-fluoride zirconium silicate paste (tzircate Prophylaxis Paste) once each year: the first experimental group brushed with zirconium silicate paste containing 9% stannous fluoride (Zircate Treatment Paste) once each year; and the second experimental group brushed every 6 months with Zircate Treatment Paste. After 2 year, the DMFT and DMFS increments were virtually identical for the control group and the group that received one application of fluoride paste per year. The group that received two applications of fluoride paste per year had a DMTF increment that was about 24% less than that of the control group; however, the DMFS increment was only 5% less. These differences were not statistically significant at the P=.05 level.

Adolescent↗
PubMed1976

The effect of external pressure on skin temperature distribution by thermography.

1) Serial thermograms were taken after the application of various intensities and durations of localized pressure on the medial surface of the human forearm. 2) Thermal response of the body surface to localized pressure was quantified. 3) It was found that usually a time period of between 1 to 3 minutes elapsed before the body surface attained a maximum elevation of temperature from the time the localized pressure is removed. 4) It was found that increased intensity of pressure (5 psi vs. 3 psi) and longer duration (20 minutes vs. 10 minutes) caused larger thermal responses. 5) It is suggested that high resolution medical thermography may eventually become a useful tool in the fitting of prosthetic and orthotic devices and for the prediction of pressure sores formation so prophylactic measures can be started immediately on immobilized patients.

Adult↗