A clinical trial of two fluoride dentifrices in an area of low caries prevalence.

OBJECTIVE: The study was designed to test the hypothesis that a dentifrice with fluoride at the same concentration (1000ppm) from two sources, ie NaF and NaMFP, would provide a greater treatment effect than one with NaMFP alone. BASIC RESEARCH DESIGN: A double blind clinical trial with random assignment of children to one of two groups was carried out for three years. The two trial groups were similar at the outset in respect to those variables which might otherwise have affected the outcome, including age and gender, with means per subject of 98.4 sound surfaces and 2.2 decayed and filled surfaces in each group initially. CLINICAL SETTING: Secondary schools in the Isle of Wight, UK, an area of diminished caries experience. PARTICIPANTS: One thousand six hundred and thirty-three children aged initially 10-12 years. INTERVENTIONS: A test dentifrice containing 500ppm NaF plus 500ppm NaMFP, and a standard active control product containing 1000ppm NaMFP. Products were used in the home. OUTCOME MEASURES: Increment of DF teeth and surfaces measured over 36 months. RESULTS: After three years, mean approximal surface increments were 3.6 new DFS in the control group and 3.1 in the test group, a difference 13 per cent (P < 0.05). Thirty-four per cent of the subjects were caries free at the outset. In the 1075 subjects with caries at the outset, the total mean increment on all surfaces was 7.2 new DFS in the control group and 6.4 new DFS in the test group, a difference of 11 per cent (P < 0.05). However, those subjects with initial caries had approximal surface increments of 4.8 new DFS in the control group and 4.0 new DFS in the test group, a difference of 16 per cent (P < 0.01). Included separately along with the conventional rubric were enamel white spots on which no differential treatment effect was observed. CONCLUSIONS: Under the conditions of this study, the regular use of a dentifrice containing 1000ppm fluoride from two sources provided a significantly greater treatment effect than one with fluoride from a single source.

Xylitol-induced changes of enamel microhardness paralleled by microradiographic observations.

The study, aimed to analyze the feasibility of a prospective field study, was carried out in Polynesian children with rampant untreated caries. Slabs of bovine enamel were inserted for 8-12 days in cavities and subsequently replaced by permanent fillings. Before use, the surface of the slab was polished, and one half predemineralized and tested for microhardness. The follow-up in 30 subjects involved 54 slabs, 30 from negative controls with no added sweets and 24 from subjects receiving 20 g/day of xylitol in candy. The microhardness of the slabs was reassessed, and the difference between measurements calculated and tested for significance. The differences between the groups were highly significant, the predemineralized halves showing pronounced rehardening at exposure to xylitol. Parallel microradiographic observations conformed with the above findings. The results indicate that the use of a noncariogenic sweetener might be of value in high caries risk subjects.

Dental caries. Principal cause of tooth extraction in a sample of US male adults.

Comprehensive oral examinations carried out over a period of about 10 years on participants in the Veterans Administration Dental Longitudinal Study were evaluated to identify teeth extracted during this time and to ascertain the apparent reason for these extractions. The study population included 736 dentulous adult males, 49% of whom experienced 1,142 extractions. Caries was judged to be the primary cause of tooth loss, responsible for 33.3% of the teeth extracted. Extractions in preparation for a prosthesis (31.3%) and periodontal disease (18.7%) were the other major causes of tooth loss. Thus, dental caries was the prime cause of tooth extraction in this sample of US male adults, while a second major cause was preparation for a prosthesis which included the extraction of sound teeth and teeth with carious lesions which could have been restored. Periodontal disease was clearly not the major cause of tooth loss and was responsible for only 18.7% of the extractions in this population. The results of this study demonstrate that dental caries is a major problem in adults, leading to greater tooth loss than periodontal disease. A large percentage of the tooth loss in these individuals was clearly preventable. The same emphasis placed upon caries prevention in children should be applied to the adult population.

Metabolism of furan fatty acids in fish.

In vivo experiments on interconversions of furan fatty acids in fish are described. Administration of 2- or 3-14C-labelled furan fatty acids showed that the heterocycle does not interfere with conversions at the carboxyl group, such as shortening and elongating the chain, or its reduction to alcohol. There was no indication for desaturation of proximal chains, methylation or demethylation of the ring, or changes in the terminal chains. According to these restricted metabolic correlations, the furan fatty acids can be classified in specific structural families of bis-homologs. Distinct parent furan compounds are likely for each of these families. [1-14C]Acetate was incorporated by fish into furan fatty acids. Their chemical oxidation showed that only the resulting dicarboxylic fragments were labelled. They represent the proximal chain including alpha-C of the ring. Label was not found in the monocarboxylic acids which represent terminal chains with alpha'-C, and ring-methyl substituents with beta- and beta'-C. Accordingly, fish do not synthesize from acetate the terminal alkyl chain including the carbons in the cyclic portion of the furan fatty acids.

Subtotal colectomy for obstructing carcinoma of the left colon.

This retrospective review of seven patients with completely obstructing cancers of the left half of the colon, in addition to other reports in the literature, suggests that subtotal colectomy with primary ileal proctostomy may be the treatment of choice for those lesions that are technically resectable and located high enough to permit an intraperitoneal ileal proctostomy. The morbidity and mortality is less than that seen with the staged approach and the length of hospitalization is shorter. By eliminating a second or third hospitalization and a temporary colostomy, palliation is better in those patients who ultimately die from recurrent cancer. Furthermore, those patients resected for cure may have increased rates of long-term survival.