A study of 589 consecutive implants supporting complete fixed prostheses. Part I: Periodontal aspects.

Ninety-one consecutive edentulous patients who had been treated by means of fixed prostheses (n = 103) supported by Br?nemark implants (n = 589) were examined. Eighteen fixtures (3%) failed to integrate. After a mean loading time of 32 (range 6 to 80) and 38 months (range 5 to 83) for fixtures in the maxilla and mandible, respectively, an additional 12 fixtures lost integration. The cumulative failure rate for individual fixtures after 6 years was 8.4% and 5% for maxillae and mandibles, respectively. Only one patient had to revert to complete dentures. For fixtures in the maxillae, the mean marginal bone loss was 0.7, 0.1, and 0.2 mm for each of the first 3 years of loading, respectively; for fixtures in mandibles, the corresponding values were 0.7, 0.2, and 0.1 mm. The loss in marginal bone height was equal in both jaws and was not related to bleeding on probing or to the preoperative resorption anatomy.     

Prosthetic aspects of osseointegrated fixtures supporting overdentures. A 4-year report

Eighty-six consecutive patients, provided with 84 resilient and two nonresilient overdentures (six in the upper and 80 in the lower jaw), were examined. The overdentures were supported by a total of 173 osseointegrated titanium fixtures (the standard Branemark abutment), with a mean loading time of 19.1 months (range 4 to 48 months). In each jaw only two fixtures anchored the overdentures. No failures occurred during the observation period but two fixtures were lost before loading. The radiographic annual bone loss around fixtures in the lower jaw was -0.8 mm for the first year and less than -0.1 mm for the following years. The change in marginal bone height did not correlate with parameters such as the occlusion and articulation pattern, the presence or absence of a soft liner around the abutments, and the magnitude of the interabutment distance. The patients' reactions to overdenture treatment were, on the whole, positive concerning chewing function, phonetics, and comfort. The need for maintenance care of the clip-bar attachment was minimal.     

Effect of a mouthrinse containing calcium lactate on the formation and mineralization of dental plaque

In this study, a mouthrinse containing calcium lactate was tested for its effect on the accumulation of dental plaque and on the concentrations of calcium and phosphorus therein. Human volunteers rinsed four times per day with a calcium lactate (165 mmol/l) solution for 1 week. Plaque samples, collected 16 h after the last rinse, were analyzed chemically. Calcium lactate rinses had no effect on the plaque score, but resulted in approximately twofold increases of calcium and phosphorus in plaque. The incorporation of monofluorophosphate (5 mmol/l) into the rinsing solution failed to show any significant influence on calcium, phosphorus, and fluoride levels in plaque. Increased mineral deposition in the plaque may provide an explanation for the reduced caries development earlier observed in rats fed a diet containing calcium lactate.     

Detection of proximal caries in vitro using standard and task-specific enhanced images from a storage phosphor plate system

Eight dentists evaluated 72 proximal surfaces of premolars with respect to all caries lesions and to lesions into dentine in digital images from a storage phosphor plate system. The images were processed in four different ways: (1) the default algorithm of the standard imaging system (DF); (2) an algorithm correcting for attenuation and visual response (AV), and two proprietary caries-specific enhancement algorithms (3) K1, and (4) K2, respectively. The lesions were validated by histological examination. There were no significant differences in the areas under the receiver operating characteristic curves between differently processed radiographs for the categories of all caries lesions and caries into dentine.     

Substance use among Dutch dental students

OBJECTIVES: The objectives were to assess the prevalence of substance use among Dutch dental students and to determine their attitudes about substance use and its consequences. METHODS: In association with a national study of drug use among US dental students, a questionnaire was translated from English into Dutch and administered to dental students at two dental schools in The Netherlands. Students received an anonymous 115-item questionnaire in the fall of 1996. RESULTS: Alcohol was the students' drug of choice for lifetime (95%), past year (94%) and past month (88%) use. No significant correlations were found between alcohol use and gender, schools, and years in dental education. In the past month, 58% of students reported drinking on 5 or more days; 53% had 5 or more drinks on the same occasion, 20% had 5 or more drinks on the same occasion on 5 or more days; and 17% reported getting drunk at least monthly. Prevalence rates for past month use of tobacco was 24% and marijuana, 4%. Male students smoked twice as much as females, with significant differences found for all three periods of use (X2>19.00, P<0.01). When asked whether their schools offered policies and education programs on alcohol and other drugs, 52% of students reported that these were not available. CONCLUSIONS: Dental schools should develop effective programmes to educate students about responsible use of alcohol and other licit and illicit drugs. Schools should also inform students about their susceptibilities to substance abuse and dependency.     

The multiple roles of major histocompatibility complex class-I-like molecules in mucosal immune function

The human major histocompatibility complex (MHC) on chromosome 6 encodes three classical class-I genes: human leukocyte antigens (HLA) A, B, and C. These polymorphic genes encode a 43- to 45-kDa cell surface glycoprotein that, in association with the 12-kDa beta2-microglobulin molecule, functions in the presentation of nine amino acid peptides to the T-cell receptor of CD8-bearing T lymphocytes and killer inhibitory receptors on natural killer cells. In addition to these ubiquitously expressed, polymorphic proteins, the human genome also encodes several nonclassical MHC class-I-like, or class Ib, genes that, in general, encode nonpolymorphic molecules involved in various specific immunological functions. Many of these genes, including CD1, the neonatal Fc receptor for IgG, HLA-G, HLA-E, the MHC class-I chain-related gene A, and Hfe, are prominently displayed on epithelial cells, suggesting an important role in epithelial cell biology.     

Evaluation of a technique for recording temporomandibular joint sounds.

Analysis of temporomandibular joints sounds may contribute to the differential diagnosis of temporomandibular joint disorders. In this article an advanced system for the recording of joint sounds is presented. The method proved to be reliable. The problem of filtering out artifacts has been solved to a great extent but not completely. Temporomandibular joint sounds measured with this technique vary considerably in energy, frequency spectrum, and peak-to-peak amplitude over 3 months, as well as within 1 day. These differences seem to reflect natural variations in joint sounds caused by the physical impossibility of performing identical jaw movements. The results indicate that joint sound characteristics do not yet offer a solid basis for inferences concerning the development of temporomandibular joint abnormalities in the clinical setting.     

Amalgam use and mercury emission in the Netherlands

An overview is presented of the emission of mercury to the environment by restoring teeth with amalgam, extraction, replacement of amalgam, and the final phase of teeth. Important input data were the trade figures of amalgam. The emission of mercury from amalgam fillings are characterized by diffuse spreading. Many small sources are together a substantial source of the leakage of mercury to the environment. Amalgam adhering to cotton-wool and in extracted teeth deliver a relevant contribution to the mercury load in municipal waste. The total mercury emission from dental amalgam to the environment in the Netherlands is at the estimate 500 kg a year, with a worst case maximum of 935 kg.     

Oral microbiota in smokers and non-smokers in natural and experimentally-induced gingivitis

Abstract. The present study primarily aimed at investigating the oral microbiota in smokers and non-smokers with established gingivitis and monitoring its composition during experimental gingivitis. Secondly, it aimed at examining whether the composition of the microbiota is associated with different levels of gingival inflammation during this experimental gingivitis trial. For this purpose, 25 non-dental university students with gingivitis were recruited. 11 subjects were smokers and 14 were non-smokers. After achieving gingival health, they entered a 14-day experimental gingivitis trial. Plaque and bleeding were assessed before entering into the study (intake), at day 0. day 5 and at day 14 of the experiment. Microbiological samples from mucosal sites and dental plaque (taken at intake, day 0, and day 14) were analysed for the presence of Actinomyces species. Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, Fusobacterium nucleatum, Peptostreptococcus micros. Porphyromonas gingivalis, Prevotella intermedia and Streptococcus species. At day 14 of the experimental period, the level of plaque formation was not different between smokers and nonsmokers, but bleeding scores were lower in smokers than in non-smokers (15% and 30%) respectively, p= 0.01). The change from natural gingivitis to a state of gingival health and a subsequent change from gingival health to experimentally induced gingivitis was accompanied by quantitative alterations in the cultivable microbiota in both groups. Changes were most prominent in the transition from gingival health to experimental gingivitis and were found in dental plaque for Actinomyces species, C. rectus, F. nucleatum, and P. intermedia. Within the group of non-smokers, a distinction was made between subjects with a‘weak’or 'strong’inflammatory response. No relationship with a single bacterial species could be established which would likely explain the differences in levels of inflammation. It is concluded that differences in response to experimental gingivitis are not caused by major differences in the composition of the oral microbiota.