Optimum force magnitude for orthodontic tooth movement: a mathematic model.

The aim of this study was to develop a mathematic model to describe the relationship between magnitude of applied force and rate of orthodontic tooth movement. Initially, data were extracted from experimental studies in dogs (beagles), in which controlled, standardized forces were used to move mandibular second premolars distally. Curve-fitting by nonlinear regression analysis provided an equation describing the relationship between force magnitude and rate of tooth movement in beagles. A similar equation was subsequently used to analyze the limited available data from the literature on human canine retraction. The maximum rates of tooth movement in humans and dogs are very similar. A threshold for force magnitude that would switch on tooth movement could not be defined. The model showed that a wide range of forces can be identified, all of which lead to a maximum rate of tooth movement.     

Growth of oral and skin fibroblasts from patients with oral submucous fibrosis

The purpose of the investigation was to evaluate and compare the proliferation (growth) of mouth fibroblasts and skin fibroblasts from patients with oral submucous fibrosis (OSF). Material comprised fibroblasts from fibrous bands situated in the buccal mucosa and from the inner aspect of the forearm of 8 patients with classic features of OSF as well as fibroblasts from 6 buccal mucosa and 8 skin biopsy specimens from healthy non-areca nut chewing individuals. Cells were cultured for 8 days according to standard techniques. Their growth was monitored daily, under optimal conditions as well as exposure to concentrations of arecoline. The data were analyzed using regression analysis, analysis of variance and the Kruskal-Wallis test. We found no statistically significant differences between the proliferation patterns of oral and skin fibroblasts from patients or between those from patients and controls. The reaction of the cells exposed to concentrations of arecoline was similar; at low concentrations (0.1–10 μg/ml) normal growth was maintained, while 100 μg/ml inhibited growth. It is concluded that fibroblasts from mouths affected by OSF have proliferation patterns which fall within normal parameters, that the excessive collagen formation in established OSF is not due to increased fibroblast proliferation and that arecoline does not stimulate fibroblast proliferation.     

Antimicrobial effectiveness of an herbal mouthrinse compared with an essential oil and a chlorhexidine mouthrinse

BACKGROUND: The authors investigated mouthrinses' antimicrobial effectiveness against predominant oral bacteria, as determined by the minimum inhibitory concentration (MIC). Specifically, they evaluated an herbal mouthrinse, an essential oil rinse and a 0.12 percent chlorhexidine gluconate rinse. METHODS: The authors assessed the inhibitory effects of the three test agents against 40 oral bacteria at concentrations of 1, 2, 4, 8, 16, 32, 64, 128, 256 and 512 micrograms per millliter. They inoculated plates containing basal medium and the test agents with suspensions of the test species and incubated them anaerobically at 35 degrees C. The authors interpreted the MIC as the lowest concentration of the agent that completely inhibited the growth of the test species. RESULTS: The herbal mouthrinse inhibited the growth of most of the 40 test species. Compared with the essential oil mouthrinse, the herbal mouthrinse exhibited significantly lower MICs for Actinomyces species, periodontal pathogens Eubacterium nodatum, Tannerella forsythia and Prevotella species, as well as the cariogenic pathogen Streptococcus mutans. The chlorhexidine gluconate rinse had the lowest MICs compared with the essential oil rinse and the herbal rinse for all test species examined. CONCLUSIONS: Although less potent than the chlorhexidine gluconate rinse, the herbal rinse was more effective than the essential oil rinse in inhibiting the growth of oral bacteria in vitro. CLINICAL IMPLICATIONS: The data suggest that the herbal mouthrinse may provide oral health benefits by inhibiting the growth of periodontal and cariogenic pathogens. In vivo clinical testing is essential to confirm in vitro results.     

A preliminary report on patient acceptance of a novel intra-oral lubricating device for the management of radiotherapy-related xerostomia

Management of radiotherapy-related xerostomia is difficult. Saliva substitutes are helpful but the effects are short-lived. The purpose of the study was to develop a prototype intra-oral lubricating device for the management of radiotherapy-related xerostomia and to evaluate patient acceptance. An intra-oral lubricating device was fabricated that incorporated a reservoir in the palatal vault and permitted slow release of saliva substitute by the patient. Preliminary clinical testing was done in five patients with radiotherapy-related xerostomia. A measure incorporating seven questions was used to explore patient acceptance. The device was simple to fabricate using materials available in a technical laboratory. All patients were able to wear the device for at least 4 h per day throughout the test period. The device was considered easy to use and clean. Some impairment of speech and chewing was noted although this appeared to be related to the bulkiness of the reservoir. General oral comfort was improved due to the lubricating effect. The bulk of the reservoir was reduced as a consequence of patient feedback. The design addressed key problems associated with previous lubricating systems. Patient reports on oral functioning with the device in situ provided pivotal information on the devices utility.     

General dentists' evaluation of anesthesia sedation education in U.S. dental schools

To assess the quality and quantity of sedation education in U.S. dental schools, a prospective, questionnaire-based survey was administered to general dental practitioners who graduated in 2003. Questionnaires were sent via facsimile to recent dental graduates using a list obtained through the American Dental Association. The response rate was 54 percent; 718 of the 1,328 nine-question surveys were returned. The response to the questionnaires indicates a perceived need for sedation care by the majority of recent graduates and low overall satisfaction with the quality of sedation education in U.S. dental schools. The general consensus of most 2003 dental school graduates is that they have gained little or no hands-on experience in sedation techniques and would have supported an increase in tuition and fees if an institution were to offer more efficient sedation training. With increased popularity and high patient demand for sedation techniques, the new dentist feels a need for sedation education before graduation.     

Effects of diagnostic threshold and overlapped approximal surfaces on reported caries status

The aims of this study were to examine the influence upon reported caries status of: 1) employing different diagnostic thresholds and 2) using differing conventions for treating approximal surfaces which appeared overlapped on posterior bitewing radiographs. Caries prevalence data from a group of 211 Scottish schoolchildren aged 5-15 yr studied during a trial of elective temporary tooth separation in general dental practice in Scotland were used. In this "moderate" caries group, values for dmft/DMFT rose significantly (P less than 0.001) when the D1 diagnostic threshold (all grades of lesion accepted) was applied in comparison with the D3 threshold (only caries into dentine recognised); dmft increasing from 3.9 to 5.4 and DMFT increasing from 1.7 to 4.7. This demonstrated that an over-optimistic impression of overall caries levels may be given when only the D3 threshold is used uncritically. In this study the status of approximal surfaces which were overlapped on bitewing radiographs was assessed by direct clinical examination using the temporary elective tooth separation technique. The investigation showed that, for this juvenile population, most (81.8% mesial, 93.1% distal) overlapped approximal surfaces were sound. Significantly more mesial than distal surfaces were found to be overlapped.     

Craniectomy and noggin application in an infant model.

INTRODUCTION: Noggin is an antagonist of bone morphogenetic proteins (BMP)-2, -4 and -7. Little data are available regarding its clinical utility. Two hypotheses were put forward: firstly, that spontaneous regeneration of calvarial defects with noggin protein would result in diminished bone volume when compared with calvarial defects not so treated. Secondly, that centrifugal cranial expansion would remain undisturbed whether noggin was applied or not. MATERIAL AND METHODS: A unilateral defect of the frontal and parietal bones (2x4cm) was generated by excising the right coronal suture in 2-month-old minipigs (n=10) and in group 1 (n=5) no further intervention was undertaken. In the second group (n=5), a collagen type I tissue fleece and noggin protein (1.05mg/ml) were applied. After 4 months the coronal suture regions of frontal sides were examined in each animal by computed tomography and non-decalcified histology. RESULTS: Bony gaps of equivalent size remained in animals of both groups. The differences in bone volumes of the experimental sides of group 1 were not statistically significantly different (p=0.117) when compared with those of group 2. A significant difference in the bone volumes of the experimental versus control (unoperated) sides was found in both group 1 (p=0.043) and group 2 (p=0.043). Internal skull diameters increased by 16.4% in both groups but the physiological centrifugal cranial expansion remained undisturbed. Bone densities of the experimental and control sides of groups 1 and 2 were not statistically significantly different (both p>0.05). CONCLUSIONS: The first hypothesis was contradicted: the quantity and quality of spontaneous bone regenerates was not altered by application of noggin protein. The second hypothesis was confirmed: no disruption of subsequent cranial development was seen. It may be that a single application of noggin protein in this study was insufficient. However, it may well be suggested that the continuous supplementation of noggin, for example by adenoviral noggin gene transfer may significantly reduce the quantity of spontaneous bone regeneration in a similar experiment.     

Fungal load and candidiasis in Sjögren's syndrome

OBJECTIVE: We sought to investigate the prevalence of Candida carriage and the relationships between salivary flow rates and oral Candida load in patients with Sj?gren's syndrome (SS). METHODS: The oral Candida load of patients with SS was evaluated by culturing oral rinse (swish and spit) samples. Culture, Gram stain, and wet-mount test results were reported. RESULTS: One hundred three patients (96 women) met European criteria for SS (91 with primary SS and 12 with secondary SS). The mean age (95% confidence interval) was 55 years (range, 51-57 years). Oral rinse cultures were positive in 77% of subjects. The total stimulated salivary flow rate was inversely correlated with oral Candida load (r = -0.47; P 相似文献