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P Moon

Publications and source records attributed to P Moon.

7 recordsLinked to original sources
PubMed2001

In vitro comparison of the fracture resistance and failure mode of fiber, ceramic, and conventional post systems at various stages of restoration.

PURPOSE: This in vitro study evaluated 6 post systems over 4 simulated clinical stages of tooth restoration to (1) determine quantitatively the fracture resistance strength at each stage when a static loading force is applied to cause failure; (2) determine the failure mode for each post system at each simulated clinical stage; and (3) determine the feasibility of removing failed post systems. MATERIALS AND METHODS: Ten post systems made with various materials and designs were tested at the following 4 stages of simulated clinical treatment: stage #1: posts only, loaded using a 3-point loading model to failure, to determine transverse strengths and failure modes for each post system; stage #2: posts alone, bonded into teeth; stage #3: posts bonded into teeth with core build up; stage #4: post and core build up and full veneer restoration. For stages #2 through #4, the coronal portion of 60 mandibular premolars was amputated at the cemento-enamel junction, the canals were treated endodontically, and the specimens were mounted in acrylic blocks. A testing force was applied to the posts at 90 degrees to the long axis of the tooth, 4 mm from the cemento-enamel junction. The O'Brien test for constant variance was performed over the treatment groups. For nonconstant variance, the Welsh analysis of variance was used to test for equalities of treatment means. The Tukey Kramer procedure determined which treatment procedures differed. RESULTS: The failure thresholds for each post system were significantly different at each stage of testing, but the order of test results by post type remained generally consistent from one stage to the next. ParaPosts (Coltene, Whaledent Int, New York, NY) and core build up resulted in significantly higher failure thresholds through all 4 stages of testing. This post system also consistently displayed a high number of nonfavorable tooth fractures. FibreKor post and cores (Jeneric Pentron Inc, Wallingford, CT) resulted in significantly lower failure threshold values in stages #2 through #4. This post system displayed no tooth fractures in stages #2 and #3 and a similar number of nonfavorable tooth fractures in stage #4 when compared with the other systems. C-Post (Bisco Dental Products, Schaumburg, IL), CosmoPost (Ivoclar Vivadent North America Inc, Amherst, NY), and AesthetiPost (Bisco Dental Products) grouped in descending order through stages #2 to #4. These systems displayed intermediate fracture resistance strengths, as well as a moderate number of nonfavorable tooth fractures. CosmoPost exhibited a significant number of brittle post fractures with fragments left in the root canal at all stages. The fracture resistance of the cast metal post varied from stage to stage. No teeth fractured at stage #2. At stage #3, 9 of 10 teeth fractured nonfavorably, and all teeth fractured nonfavorably in stage #4. CONCLUSIONS: The fiber posts evaluated provided an advantage over a conventional post that showed a higher number of irretrievable post and unrestorable root fractures. At the stage of final restoration insertion, there was no difference in force to failure for all but the FibreKor material, which continued to be weaker than all other tested materials. The fiber posts were readily retrievable after failure, whereas the remaining post systems tested were nonretrievable. J Prosthodont 2001;10:26-36.

Analysis of Variance↗
PubMed2000

Unilateral thalamic stroke does not decrease ipsilateral sleep spindles.

STUDY OBJECTIVES: To measure the sleep spindle characteristics in patients with unilateral thalamic stroke. DESIGN: A prospective study of patients with thalamic stroke and age-matched healthy controls. SETTING: Department of Neurology of a University Hospital. PARTICIPANTS: Thirteen patients (mean age: 67 years, SD: 13,44) with an isolated, unilateral acute thalamic stroke and 18 healthy age-matched volunteers. INTERVENTIONS: A polysomnogram recording from 14 scalp EEG electrodes performed during 2 consecutive nights, the second or third week after the stroke. Only the sleep of the second night was analyzed. MEASUREMENTS AND RESULTS: Sleep spindles were counted during two separate 10-minute epochs of stage II. Spindles appearing synchronously in both sides with similar amplitude were called "bilateral." Spindles with twice the amplitude in one side than the other were "right" or "left-side predominant". There were 8 patients with posterolateral, 3 with global and 2 with anterior lesions. Eight were right and 5 left-sided. The number of spindles was similar in patients (39.8 +/- 23.4 in 20 minutes) than controls (26.07 +/- 29.07; p=0.173). Spindles with a centroparietal (34%) and centroparieto-occipital localization (22%) were the most frequent. In controls approximately 66% of the spindles had a bilateral and symmetric distribution over the scalp, 23% of the spindles were predominantly left-sided and 5% were predominantly right-sided. In patients, bilateral spindles decreased (p<0.0001) but asymmetric spindles did not change. CONCLUSION: Unilateral acute thalamic stroke does not decrease sleep spindles ipsilaterally; rather, it seems to produce a bilateral diminution in their number.

Adult↗
PubMed1998

Use of a handheld device for analysis of blood electrolyte concentrations and blood gas partial pressures in dogs and horses.

OBJECTIVE: To compare, for blood samples from dogs and horses, blood electrolyte concentrations, blood gas partial pressures, and Hct obtained using a handheld analyzer with those obtained using a standard chemistry analyzer and to compare results obtained with the handheld analyzer using warm versus cold test cartridges. DESIGN: Case series with analysis of split samples. SAMPLE POPULATION: Blood samples from 22 dogs and 17 horses. PROCEDURE: Sodium, potassium, ionized calcium, bicarbonate, and total CO2 concentrations, pH, PO2, PCO2, base excess, and Hct were determined by use of a handheld analyzer and test cartridges that had been allowed to warm to ambient temperature or had been recently removed from a refrigerator. Results were compared with those from a standard chemistry analyzer by use of linear regression. RESULTS: For canine samples, values obtained with the handheld analyzer and warm cartridges were highly correlated (r2 > or = 0.83) with values obtained with the standard chemistry analyzer, except for sodium concentration (r2 = 0.6). For equine samples, values obtained with the handheld analyzer and warm cartridges were highly correlated (r2 > or = 0.79) with values obtained with the standard chemistry analyzer, except for Hct (r2 = 0.38). For all samples, results obtained with cold and warm cartridges were moderately correlated (r2 > or = 0.69). CLINICAL IMPLICATIONS: Results obtained with the handheld analyzer were similar to those obtained from the standard chemistry analyzer, with the exception of sodium concentration for canine samples and Hct for equine samples. Results were not substantially affected by use of cold, rather than warm, test cartridges.

Acid-Base Equilibrium↗
PubMed1994

Investigation of a new light imaging technique to detect incipient caries in teeth.

At the present time dental X-rays are the best method to locate carious lesions, however, small lesions can be detected only with difficulty. Even though investigations in the past have shown that light imaging systems are more sensitive to small lesions than X-rays it is difficult to determine the characteristics of these lesions with any of these systems. We developed a new light imaging technique that makes it much easier to determine the size and depth of these lesions on most areas of the teeth even though modifications on the present setup will still be necessary to detect them as easily on occlusal surfaces. This technique is based on raster scans of the teeth with narrow collimated light beams. The results of this investigation show that the areas ( greater than 0.1 mm 2) of small incipient lesions can be measured and their depths estimated.

Dental Caries↗
PubMed1992

Development of monoclonal antibodies that identify Vibrio species commonly isolated from infections of humans, fish, and shellfish.

Monoclonal antibodies (MAbs) against Vibrio species that infect humans, fish, and shellfish were developed for application in rapid identifications. The pathogens included Vibrio alginolyticus, V. anguillarum, V. carchariae, V. cholerae, V. damsela, V. furnissii, V. harveyi, V. ordalii, V. parahaemolyticus, and V. vulnificus. Three types of MAbs were selected. The first important group included MAbs that reacted with only a single species. A second group comprised a number of MAbs that reacted with two, taxonomically closely related Vibrio species. For example, of 22 MAbs raised against V. alginolyticus, 6 recognized a 52-kDa flagellar H antigen common to both V. alginolyticus and V. parahaemolyticus; V. anguillarum and V. ordalii also shared antigens. A third group included three genus-specific MAbs that reacted with almost all Vibrio species but did not react with other members of the family Vibrionaceae (e.g., members of the Aeromonas, Photobacterium, and Plesiomonas genera) or a wide range of gram-negative bacteria representing many genera. This last group indicated the possible existence of an antigenic determinant common to Vibrio species. Two of these three genus-specific MAbs reacted with heat-stable antigenic determinants of Vibrio species as well as lipopolysaccharide extracted from Vibrio species. The use of the MAbs in blind tests and diagnosis of clinical isolates indicated that three different types of bacteria, viz., live, formalin-fixed, and sodium azide-killed bacteria, were detected consistently. Overall, it was found that the genus-specific MAbs were very useful for rapidly identifying vibrios in the screening of acute infections, while the species-specific MAbs and others were useful for completing the diagnosis.

Animals↗
PubMedDate not supplied

Retention of esthetic veneers on primary stainless steel crowns.

The purpose of this study was to ascertain the amount of shearing force necessary to fracture, dislodge or deform the esthetic veneer facings of four commercially available veneered primary incisor stainless steel crowns. The four types tested were: Cheng Crowns, [Peter Cheng Orthodontic Laboratory]; Whiter Biter Crown II, [White Bite Inc.]; Kinder Krowns, [Mayclin Dental Studio, Inc]; and NuSmile Primary Crowns, [Orthodontic Technologies, Inc]. The crowns (#4 right central incisor) from each manufacturer were obtained with the facings attached. The crowns were soaked for ninety days and thermocycled at 4 degrees C and 55 degrees C for 500 45-second cycles. The crowns were cemented to standardized chromium cobalt metal dies. Each die was placed in to a custom holder on the Instron Universal testing machine. A force was applied at the incisal edge of the veneer at 148 degrees, (the primary interincisal angle), with a crosshead speed of 0.05 inches/minute until the veneer either fractured, dislodged or deformed. The mean force (Ibs) required +/- SD to produce failure, in descending order, was as follows: Cheng (107.8 +/- 17.3); NuSmile (100.2 +/- 18.2); KinderKrown (91.3 +/- 27.4)d Whiter Biter (81.5 +/- 21.7). To test the hypothesis of no difference among the four manufacturers, an analysis of variance was performed using PROC GLM. The resultant F statistic was 2.79 (p < 0.0543), indicating a marginally statistically significant difference in the response variable "pressure" among the four groups. A posthoc test was then performed to ascertain where these differences occurred. These results, using Turkey's studentized range test for pairwise comparisons, suggested that the only difference was between the Cheng and Whiter Biter manufacturers.

Analysis of Variance↗