bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of Differentiation in Wiregrass (Aristida beyrichiana): Implications for Restoration Efforts
Authors: Gordon Doria R. , Rice Kevin J.
Published: August 2004

Aristida beyrichiana (wiregrass) is increasingly being planted in restoration projects across the southeastern coastal plain, with little focus on genetic differences among populations across the region. Local and regional population differentiation for establishment and growth traits were examined in common garden and reciprocal transplant experiments. Seeds from up to 20 plants from each of seven populations were collected in northern and central Florida sites that encompassed gradients of soils, hydrology, and temperature. Reciprocal seed transplants using three of the common garden populations were conducted in two consecutive years. In the common garden, significant population differences were seen in seed weight, seedling emergence and survival, tiller height, number of tillers, the relationship between tiller number and tiller height, and flowering. Variation among maternal families was seen in tiller number and in the relationship between tiller number and tiller height. The reciprocal transplant study did not detect either local adaptation to sites of origin or consistent superiority of one source population or planting site in seedling establishment. These results suggest that the probability of seedling establishment is primarily dependent on environmental conditions rather than genetic differences. Genetic variation for traits related to fitness (e.g., tiller number) may be retained within populations because phenotypically plastic growth responses of seedlings to environmental variation buffer genetic variation against the action of selection. But despite the lack of evidence for genetic influences on initial establishment in wiregrass, our common garden study suggests genetic differences among populations. This result, when combined with previous results indicating local adaptation in later life stages of wiregrass, suggests that restoration efforts involving this species should use local seed sources from sites with similar soil and hydrological conditions.
The Mycorrhizal Status of Selected Plant Species from Connecticut Wetlands and Transition Zones
Authors: Cooke John C. , Lefor Michael W.
Published: August 2004

Vesicular‐arbuscular mycorrhizal fungi were investigated in the roots of flowering plants and ferns obtained from a variety of Connecticut freshwater wetland habitats. We sampled 290 plants from 89 species of 75 genera disposed among 42 families of flowering plants. All species of mature plants as well as selected young plants on developing shorelines were colonized by mycorrhizal fungi, suggesting that this phenomenon is common in the development of vegetation associated with fluctuating water, nutrient, and oxygen conditions. The purpose of this report is to make soil conservationists, wetland agents, and others concerned with wetlands aware of this relationship as they select plants for use in restoration, and to point out the widespread nature of the endomycorrhizal phenomenon.
Annual and Perennial Grass Growth on Nitrogen‐Depleted Decomposed Granite
Authors: Claassen V. P. , Marler M.
Published: August 2004

Decomposed granite (DG) is often difficult to revegetate because of its low nitrogen (N) content and poor physical properties. Use of soluble fertilizers on DG sites increases plant‐available N but may encourage invasive annuals to grow rapidly and exclude perennial species. This study evaluates the effect of N availability on two potential DG revegetation species: an invasive, exotic annual grass (Bromus mollis) and a native perennial grass (Elymus glaucus). Plants in 10‐L pots filled with DG were irrigated with all essential elements except N, which was provided in treatments ranging from zero to 1000 μM NO3‐N. Shoot biomass and root distribution were measured in monocultures and in mixtures of annual and perennial plants, both when the two species were seeded simultaneously and when the perennials were seeded 50 days prior to the annuals. At the higher N treatments, growth of annuals exceeded that of perennials. At solution N concentrations lower then the 50–100 μM treatments, however, growth of the perennial grasses equaled or exceeded that of the annuals. When seeded simultaneously, both species showed reduced biomass in mixtures to an extent similar to that when each species grew alone. When the perennials were already established, the biomass of annuals was reduced proportionately more than that of perennials, even at the highest N treatment. At low and medium N treatments, root placement of the perennial was deeper than that of the annual. At high N treatments, however, root distribution of both species was similar, and the deep rooting characteristic of the perennial was no longer observed.
Floristic and Soil Organic Matter Changes after Five and Thirty‐Five Years of Native Tallgrass Prairie Restoration
Authors: Kindscher Kelly , Tieszen Larry L.
Published: August 2004

We studied two tallgrass prairies and adjacent restoration areas in northeast Kansas to analyze (1) the invasion of native tallgrass prairie species from native prairie source populations into replanted areas; (2) the establishment of planted prairie species five and 35 years after being sown; and (3) the effects of native prairie species on soil organic matter. For the majority of dominant species, composition differed statistically between sampled areas even though seed rain was available from the native tallgrass prairie remnants. Plant community differences were statistically different between each native prairie area and all respective restoration sites according to the Multiple Response Permutation Procedure. In addition, species richness was greatly reduced in replanted areas compared to adjacent native prairie remnants. Soil carbon isotope ratios indicated that the planting of warm‐season grasses resulted in substantial replacement of old soil organic matter by the newly replanted grasses but that it did not create substantial increases of soil organic matter beyond replacement. The lack of accumulation reflects a nutrient‐poor system (nitrogen‐poor in particular), and the relative absence of native or introduced nitrogen‐fixing plant species on the replanted areas may be a significant factor. It appears that restoration of the original highly diverse vegetation component of the tallgrass prairie ecosystem, even when aided by seeding and an adjacent prairie seed source, will occur on carbon‐ and nitrogen‐depleted soils only over very long periods of time (perhaps centuries), if at all.
Eradication of Nonnative Fish by Gill Netting from a Small Mountain Lake in California
Authors: Knapp Roland A. , Matthews Kathleen R.
Published: August 2004

Nearly all mountain lakes in the western United States were historically fishless, but most now contain introduced trout populations. As a result of the impacts of these introductions on ecosystem structure and function, there is increasing interest in restoring some lakes to a fishless condition. To date, however, the only effective method of fish eradication is the application of rotenone, a pesticide that is also toxic to nontarget native species. The objective of this study was to assess the effectiveness of intensive gill netting in eradicating the trout population from a small subalpine lake in the Sierra Nevada, California. We removed the resident trout population and a second trout population accidentally stocked into the study lake within 18 and 15 gill net sets, respectively. Adult trout were highly vulnerable to gill nets, but younger fish were not readily captured until they reached approximately 110 mm. To determine the utility of gill netting as a fish eradication technique in other Sierra Nevada lakes, we used morphometry data from 330 Sierra Nevada lakes to determine what proportion had characteristics similar to the study lake (i.e., small, isolated lakes with little spawning habitat). We estimated that gill netting would be a viable eradication method in 15–20% of the high mountain lakes in the Sierra Nevada. We conclude that although gill netting is likely to be more expensive and time consuming than rotenone application, it is a viable alternative under some conditions and should be the method of choice when sensitive native species are present.
Candida albicans colonization of surface‐sealed interim soft liners
Authors: Olan‐Rodriguez Luciano , Minah Glenn E. , Driscoll Carl F.
Published: August 2004

Purpose This in‐vivo investigation evaluated the effect of 2 denture sealer agents on the microbial colonization of a newly placed soft interim denture liner during a period of 14 days.

Materials and Methods An interim soft denture liner (Coe‐Soft; GC America, Alsip, IL) was coated with 2 different denture surface sealants (Palaseal [Heraeus Kulzer, Irvine, CA] and Mono‐Poly [Plastodent, New York, NY]). Three rectangular wells of 1 cm wide × 2 cm long × 2 mm deep were placed in the intaglio of 10 maxillary complete dentures and filled with the soft liner material. The soft liner surface was treated with Palaseal (first well) and Mono‐Poly (second well), and the unsealed (third well) was used as a control. These were exposed to the oral cavity for 14 days. The effect the sealant had in the prevention of Candidal colonization in vivo of the soft liner material was evaluated. Microbiological specimens were recovered from all samples and cultivated. Microbiological data from the control and 2‐test samples in each denture were tabulated, and statistical analyses were performed.

Results This investigation showed clear differences (p < .001) between the sealed and unsealed soft liners. The sealed material showed significantly less colonization by yeast and bacteria. Intercomparison of the surface denture sealers, Palaseal versus Mono‐Poly, showed no statistically significant differences (p < .005) in total yeast or bacterial colonization.

Conclusion Coating of Coe‐Soft denture liner with either Palaseal or Mono‐Poly significantly decreased yeast and bacterial colonization.
Tensile bond strength of resin‐modified glass‐ionomer cement to microabraded and silica‐coated or tin‐plated high noble ceramic alloy
Authors: Swartz Jeffrey M. , Davis Richard D. , Overton Johnnie D.
Published: August 2004

Purpose The purpose of this study was to evaluate the influence of alloy surface microabrasion, silica coating, or microabrasion plus tin plating on the tensile bond strengths between a resin‐modified glass‐ionomer luting cement and a high‐noble alloy. Bond strength between the microabraded alloy specimens and conventional glass‐ionomer cement or resin cement were included for comparison.

Materials and Methods One hundred twenty uniform size, disk‐shaped specimens were cast in a noble metal alloy and divided into 6 groups (n = 10 pairs/group). The metal surfaces of the specimens in each group were treated and cemented as follows. Group 1: No surface treatment (as cast, control), cemented with a resin‐modified glass‐ionomer cement. Group 2: Microabrasion with 50‐μm aluminum oxide particles, resin‐modified glass‐ionomer cement. Group 3: A laboratory microabrasion and silica coating system, resin‐modified glass‐ionomer cement. Group 4: Microabrasion and tin‐plating, resin‐modified glass‐ionomer cement. Group 5: Microabrasion only, conventional glass‐ionomer cement. Group 6: Microabrasion and tin‐plating, conventional resin cement. The uniaxial tensile bond strength for each specimen pair was determined using an Instron Universal Testing Machine (Instron Corp, Canton, MA). Results were analyzed using a one‐way analysis of variance (α= 0.05) and a Tukey post‐hoc analysis.

Results Mean bond strength: Group 1: 3.6 (±1.5) MPa. Group 2: 4.2 (±0.5) MPa. Group 3: 6.7 (±0.9) MPa. Group 4: 10.6 (±1.8) MPa. Group 5: 1.1 (±0.4) MPa. Group 6: 14.6 (±2.3) MPa. Group 6 was significantly stronger than Group 4. The bond strength of specimens cemented with the resin‐modified glass‐ionomer cement using microabrasion and tin‐plating (Group 4) was significantly stronger than all other groups except the resin cement with microabrasion and tin‐plating (Group 6).

Conclusion Microabraded and tin‐plated alloy specimens luted with the resin‐modified glass‐ionomer cement resulted in the greatest mean tensile strengths for the resin‐modified glass‐ionomer cement groups. This strength was 73% of the mean tensile strength of microabraded specimens luted with resin cement.
Predictions of cement microfracture under crowns using 3D‐FEA
Authors: Kamposiora Phophi , Papavasiliou George , Bayne Stephen C. , Felton David A.
Published: August 2004

Purpose The objective of this research study was to test the effects of (1) crown margin type, (2) cement type, (3) cement thickness, (4) loading direction, and (5) loading magnitude on stress levels and distributions within luting cement that might lead to cement microfracture using three‐dimensional Finite Element Analysis techniques.

Materials and Methods Thirty‐two three‐dimensional computer models, as well as models for standards, were generated for a mandibular first premolar. Crown preparations exhibited shoulder or chamfer margin configurations, and zinc phosphate, zinc polycarboxylate, glass ionomer, and resin cements were used in thicknesses of 25 or 100 μm. Modeled crowns were loaded axially or obliquely at 10 and 100 MPa. Areas and levels of stress concentrations within the cement were determined.

Results Stresses in the cement were low for all situations except 100 MPa oblique stressing. Stresses at the margins of crowns with chamfer marginal configuration were higher than those with shoulder margins. Stresses under oblique stressing were 10 to 150 times higher than under axial stressing. Except for Zn phosphate cement, cement thickness minimally affected stress levels and distributions. Greater stresses were found in cements with the greater Young's modulus.

Conclusions Although the chamfer margin design could lead to greater stresses near the margins that places the cement at risk for microfracture and possible crown failure, glass‐ionomer and composite resin cements have more favorable mechanical properties for resisting microfracture.
The ocular impression: A review of the literature and presentation of an alternate technique
Authors: Mathews Mark F. , Smith Rick M. , Sutton Alan J. , Hudson Ron
Published: August 2004

Improved fit is one advantage of a custom ocular prosthesis. Numerous methods exist to gain intimate tissue adaptation. This article reviews the literature concerning such methods and presents an improved technique for fabrication of a custom ocular impression tray.
A prospective 5‐year study of fixed partial prostheses supported by implants with machined and TiO2‐blasted surface
Authors: Gotfredsen Klaus , Karlsson Ulf
Published: August 2004

Purpose The aim of the present study was to evaluate whether there was a difference between machined and TiO2‐blasted implants regarding survival rate and marginal bone loss during a 5‐year observation period.

Materials and Methods A total of 133 implants (Astra Tech Dental Implants; Astra Tech AB, Mölndal, Sweden) were placed in 50 patients at 6 centers in 4 Scandinavian countries. Forty‐eight implants were installed in the maxilla and 85 implants in the mandible. A randomization and a stratification were done, so that each fixed partial prosthesis was supported by at least 1 machined and 1 TiO2‐blasted implant. The implant‐supported fixed partial prostheses (ISFPP) were fabricated within 2 months after postoperative healing. A total of 52 ISFPP (17 maxillary, 35 mandibular) were inserted. The patients were clinically examined once a year for 5 years. At the annual follow‐up, biological as well as technical complications were recorded.

Results Of the 133 implants placed, 3 were reported as failed after 5 years of follow‐up, resulting in an overall cumulative survival rate of 97.6%. The cumulative implant survival rates were 100% for the TiO2‐blasted implants and 95.1% for the machined implants. No significant difference in survival was, however, found between the machined and TiO2‐blasted implants after 5 years. The mean marginal bone loss in the maxilla was 0.21 ± 0.83 mm (SD) for the machined implants and 0.51 ± 1.11 mm (SD) for the TiO2‐blasted implants during the 5‐year observation period. In the mandible, the mean marginal loss was 0.22 ± 1.13 mm for the machined implants and 0.52 ± 1.07 mm for the TiO2‐blasted implants from baseline to the 5‐year examination. No significant difference in marginal bone loss between the 2 surface groups was found during the 5‐year observation period.

Conclusions The present study shows good 5‐year results with small ISFPP in the mandible, as well as in the maxilla. No significant differences were found in failure rate and marginal bone loss around implants with a machined rather than a TiO2‐blasted surface.
Wear of enamel opposing low‐fusing and conventional ceramic restorative materials
Authors: Clelland Nancy L. , Agarwala Vaishali , Knobloch Lisa A. , Seghi Robert R.
Published: August 2004

Purpose This study evaluated the wear area of human enamel opposing 2 conventional and 2 low‐fusing dental porcelains, as well as abrasive wear, attrition, surface hardness, and fracture toughness for the 4 porcelain substrates.

Materials and Methods Two low‐fusing and 2 conventional metal‐ceramic porcelains were used to form 15‐mm‐diameter disks (n = 10), which were fired according to manufacturer's recommendations. Enamel cusps (n = 40) were formed from extracted third molars. All ceramic and enamel specimens were finished to a 1000‐grit silicon carbide surface. The Oregon Health Sciences University (Portland, OR) oral wear simulator was used to deliver a 20‐N load from the cusps to the ceramic substrates through a food‐like slurry. The sliding action of the cusps over an 8‐mm linear path produced abrasive wear. A static 70‐N load was applied at the end of the path to create attrition. This sequence was repeated at 1.0 Hz for 50,000 cycles. Ceramic wear was measured with a profilometer (±2 micrometers), and enamel wear was evaluated using optical scanning methods. After wear testing, the hardness and fracture toughness of the ceramic surfaces were determined, and scanning electron photomicrographs were made using representative ceramic and enamel specimens from each group. Enamel wear areas, abrasion and attrition depths, hardness, and fracture toughness values were subjected to analysis of variance and Tukey‐Kramer post hoc tests to determine significant differences.

Results Enamel wear was not significantly different for low‐fusing and conventional porcelains (p= .29). The wear of conventional and low‐fusing ceramic substrates was also not significantly different (p= .79). However, depth of porcelain wear caused by attrition was in general significantly greater than abrasive wear (p= .0004). Although no significant differences were found in the measured porcelain hardness values (p= .08), 1 conventional porcelain exhibited fracture toughness significantly greater than 1 low‐fusing porcelain (p < .01).

Conclusions No differences in wear patterns were noted among low‐fusing compared with conventional metal‐ceramic porcelains, but static loading resulted in significantly greater attrition compared with the observed sliding abrasive wear.
Effect of abutment tooth reinforcement techniques on the fracture resistance of removable partial denture master casts
Authors: Sato Yuuji , Takaki Naomi , Tsuga Kazuhiro , Hosokawa Ryuji
Published: August 2004

Purpose The purpose of this study was to compare the mean loads required to fracture an isolated stone abutment tooth when various reinforcement techniques were used: (A) no reinforcement, (B) surface hardening, (C) impression trimming, (D) dowel placement, and (E) impression trimming plus dowel placement.

Materials and Methods Die stone premolar specimens for each group (n = 4) were loaded perpendicular to the tooth long axis in 100‐g increments 25 hours after pouring the impression. Mean load to failure was determined for each group. Data were evaluated with a one‐way analysis of variance (α= 0.05) to determine differences among groups. Paired comparisons of factor level means were made with Tukey's q‐test.

Results The mean fracture load for Group E (7.6 kg) was significantly greater than Groups A (2.0 kg), B (2.1 kg), and C (3.4 kg). No significant difference was found between Groups D (6.0 kg) and E.

Conclusions Dowel reinforcement with impression trimming at the cervical portion of the abutment tooth resulted in significantly greater fracture resistance than the control, surface model hardener, or impression trimming alone.
Retention of cast posts cemented with zinc phosphate cement using different cementing techniques
Authors: Fakiha Zaki , Al‐Aujan Arwa , Al‐Shamrani Saleh
Published: August 2004

Purpose This study compares the effect of different cementation techniques on the retention of cast posts and cores.

Materials and Methods Twenty‐four extracted single rooted human teeth were used in this study. After routine preparation of the root canals, the canal space was enlarged with reamers. Direct post patterns were made with acrylic resin. Castings were fabricated using Ni‐Cr‐Mb alloy. Zinc phosphate cement was used as a luting agent using 4 different methods of cement introduction to the root canal space. This created 4 treatment groups consisting of 6 teeth in each group. In Group A, the cement was applied over the posts only. For the specimens in Group B, the cement was introduced into the root canals with a spiral filler and applied over the posts. In Group C, cement was injected into the root canals and then applied over the posts. Finally, for the specimens in Group D, cement was injected into the root canals and a spiral was used to spread it into the root canals, and cement was also applied over the posts. After cementation, teeth were stored in saline solution. The tensile retentive force of cast posts was evaluated using the Instron testing machine (Instron, Canton, MA).

Results The retention obtained by the 4 techniques differed significantly (p < .05). The highest tensile force to post dislodgment was observed in Group D, and the least was in Group A. Analysis of variance test revealed a highly significant difference between groups (p < .0001). According to the Fisher exact test, there was a significant increase in retention from Group A to Group D (p < .05).

Conclusions Under the conditions of this study, the injection of cement into a root canal space followed by the use of a spiral resulted in the highest level of post retention. Retention was reduced when cement was placed using a Lentulo spiral alone (Kerr/Sybron Corp, Romulus, MI), a Jiffy tube (Teledyne Water Pik, Allegheny Teledyne Co, Fort Collins, CO) alone, or by application to the post only.
The implant‐supported milled‐bar mandibular overdenture
Authors: Galindo Daniel F.
Published: August 2004

Osseointegrated dental implants have been proven successful in the treatment of edentulism. The predictability of the implant‐supported prosthesis has also been established. Several techniques have been described for the successful restoration of the edentulous mandible: fixed‐detachable prostheses with either the original Brånemark hybrid prosthesis design or conventional implant‐supported fixed partial dentures, implant‐retained overdentures, and implant‐supported overdentures. However, in cases of advanced ridge resorption in which facial tissue support is needed from the flanges of the prosthesis or when a removable type of prosthesis is preferred by the patient, an implant‐supported prosthesis is indicated. Electric discharge machining is often used in the fabrication of the bar for an implant‐supported overdenture. This procedure is very costly and technique sensitive. An alternative procedure to fabricate a milled‐bar implant‐supported overdenture is described. This procedure is simple and uses inexpensive equipment and materials. The milled‐bar minimizes lateral and rotational displacement. The overdenture incorporates attachments that provide retention, minimizing possible movement along the path of insertion. This type of prosthesis is available to a broad patient population, especially those with advanced ridge resorption, providing an excellent result at a reduced cost.
Factors influencing optical 3D scanning of vinyl polysiloxane impression materials
Authors: DeLong Ralph , Pintado Maria R. , Ko Ching‐Chang , Hodges James S. , Douglas William H.
Published: August 2004

Purpose Future growth in dental practice lies in digital imaging enhancing many chairside procedures and functions. This revolution requires the fast, accurate, and 3D digitizing of clinical records. One such clinical record is the chairside impression. This study investigated how surface angle and surface roughness affect the digitizing of vinyl polysiloxane impression materials.

Materials and Methods Seventeen vinyl polysiloxane impression materials were digitized with a white light optical digitizing system. Each sample was digitized at 3 different angles: 0°, 22.5°, and 45°, and 2 digitizer camera f‐stops. The digitized images were rendered on a computer monitor using custom software developed under NIH/NIDCR grant DE12225. All the 3D images were rotated to the 0° position, cropped using Corel Photo‐Paint 8 (Corel Corp, Ottawa, Ontario, Canada), then saved in the TIFF file format. The impression material area that was successfully digitized was calculated as a percentage of the total sample area, using Optimas 5.22 image processing software (Media Cybernetics, LP, Silver Spring, MD). The dependent variable was a Performance Value calculated for each material by averaging the percentage of area that digitized over the 3 angles. New samples with smooth and rough surfaces were made using the 7 impression materials with the largest Performance Values. These samples were tested as before, but with the additional angle of 60°. Silky‐Rock die stone (Whip Mix Corp, Louisville, KY) was used as a control.

Results The Performance Values for the 17 impression materials ranged from 0% to 100%. The Performance Values for the 7 best materials were equivalent to the control at f/11 out to a surface angle of 45°; however, only Examix impression material (GC America Inc, Alsip, IL) was equivalent to the control at f/11^16. At the 60° surface angle with f/11^16, the Performance Values were 0% for all the impression materials, whereas that for the control was 90%. The difference in the Performance Values for the smooth and rough surface textures was 7%, which was not significant.

Conclusions The digitizing performance of vinyl polysiloxane impression materials is highly material and surface angle‐dependent and is significantly lower than the die stone control when angles to 60° are included. It is affected to a lesser extent by surface texture.
Development of a nondestructive compliance test for resilient denture liners
Authors: Pesun Igor J. , Villar Anamaria , Hodges James S. , DeLong Ralph , Lai Juey H. , Schneider Donald
Published: August 2004

Purpose Resilient denture liners are prescribed for patients who cannot adjust to hard‐based dentures because of a thin mucosa or severe alveolar ridge resorption. A nondestructive test to evaluate compliance of new soft liner materials will be useful in clinical trials. The purpose of this study was to evaluate a nondestructive compliance testing technique designed to characterize long‐term, silicone‐based resilient denture liner materials.

Materials and Methods Samples of thicknesses of 1.1, 2.2, 3.3, and 4.4 mm of 2 materials (MPDS‐SL [Lai Laboratories, Inc, Burnsville, MN] and Molloplast‐B [Buffalo Dental, New York, NY]) were assessed for compliance using a closed‐loop servohydraulic testing system, applying a 3 lb force following a squarewave pattern; force and position values were recorded using a storage oscilloscope. The oscilloscope values were analyzed using computer software to determine compliance values. The effect of material thickness was examined by testing wedges of the 2 materials.

Results The testing technique used showed that differing thicknesses had significantly different compliance values (p < .0001). In the materials used to evaluate the technique, MPDS‐SL behaved more elastically than did Molloplast‐B (p < .0001). Material thicknesses beyond 2.2 mm did not increase compliance, although MPDS‐SL had a steeper thickness‐compliance curve than Molloplast‐B.

Conclusions The method used to test compliance proved to be sufficiently sensitive to distinguish between 2 materials and between varying thicknesses. The sensitivity and nondestructive nature of this test show its suitability for clinical evaluation of resilient denture liners.
A nontraditional technique for obtaining optimal esthetics for an immediate denture: A clinical report
Authors: Bouma Lars O. , Mansueto Michael A. , Koeppen Raymond G.
Published: August 2004

Bimaxillary protrusion and severe labioversion of anterior teeth complicate impression procedures and increase the difficulty in making esthetic predictions for the immediate complete denture patient. The presented technique, performed in reverse order of traditional methods, is accomplished in stages in which the anterior and nonessential posterior teeth are extracted and interim removable partial dentures placed. An opportunity is thus created to evaluate esthetics, phonetics, and anterior tooth function before extraction of the remaining dentition and delivery of immediate complete dentures. This technique facilitated the determination of the need for alveoplasty of the anterior maxilla.
A clinical report about an unusual occurrence of post‐anesthetic tongue swelling
Authors: Tan Winston Kwong‐Shen , Liu Eugene Hern‐Choon , Thean Hilary Pik‐Yen
Published: August 2004

Dentures are routinely removed from the oral cavity before general anesthetic procedures. They are only reinserted much later when the patient returns to the room. This clinical report describes an edentulous patient who developed acute tongue swelling from venous congestion as a result of tongue recovery from general anesthesia. Her complete dentures were used to separate the residual ridges during the recovery period and relieved the congestion. Denture insertion increased the height and volume of the oral cavity, which reduced pressure on the tongue, preventing a cycle of tongue compression, congestion, and swelling. This unusual complication suggests that it may be prudent for the edentulous patient to be accompanied by their dentures in the perioperative period.
Effect of light source and time on the polymerization of resin cement through ceramic veneers
Authors: Rasetto Flavio H. , Driscoll Carl F. , von Fraunhofer Joseph A.
Published: August 2004

Purpose The purpose of this study was to evaluate the efficiency of 3 different light sources to polymerize a light curing resin cement beneath 3 types of porcelain veneer materials.

Materials and Methods A conventional halogen light, a plasma arc light, and a high intensity halogen light were used to polymerize resin cement (Variolink II; Ivoclar North America Inc, Amherst, NY) through disks of veneer materials. Equal diameter and thickness disks of feldspathic porcelain (Ceramco II; Ceramco Inc, Burlington, NJ), pressable ceramic (IPS Empress; Ivoclar North America Inc), and aluminous porcelain (Vitadur Alpha; Vident Inc, Brea, CA) were used as an interface between the curing light tips and the light polymerized resin cement. The resin cement/veneer combinations were exposed to 4 different photopolymerization time protocols of 5 seconds, 10 seconds, 15 seconds, and 20 seconds for high intensity light units (Apollo 95E [Dental Medical Diagnostic Systems Inc, Westlake Village, CA] and Kreativ 2000 [Kreativ Inc, San Diego, CA]), and 20 seconds, 40 seconds, 60 seconds, and 80 seconds for conventional halogen light (Optilux; Demetron Research Inc, Danbury, CT). A surface hardness test (Knoop indenter) was used to determine the level of photopolymerization of the resin through the ceramic materials with each of the light sources. The data were analyzed by one‐way analysis of variance and a post‐hoc Scheffe test (p < .05).

Results The data indicates that the Variolink II Knoop Hardness Number values vary with the light source, the veneer material, and the polymerization time. For a given light and veneer material, Knoop Hardness Number increases with longer polymerization times. The Kreativ light showed statistically significant differences (p < .05) between all test polymerization times. Use of this light required a polymerization time of greater than 20 seconds to reach maximum resin cement hardness. For samples polymerized with the Apollo light, there were statistically significant (p < .05) differences in surface hardness between samples polymerized at all times, except for the 15‐second and 20‐second times. Samples polymerized with the halogen light showed no statistically significant (p < .05) differences in hardness between polymerization times of 60 seconds and 80 seconds.

Conclusions High intensity curing lights achieve adequate polymerization of resin cements through veneers in a markedly shorter time period than the conventional halogen light. However, the data in this report indicate that a minimum exposure time of 15 seconds with the Kreativ light and 10 seconds with the Apollo 95E light should be used to polymerize the Variolink II resin, regardless of the composition of the veneer. Conventional halogen lights required a correspondingly greater polymerization time of 60 seconds.
A comparison of palatal adaptation in acrylic resin denture bases using conventional and anchored polymerization techniques
Authors: Laughlin Gayle A. , Eick J. David , Glaros Alan G. , Young Leslie , Moore Dorsey J.
Published: August 2004

Purpose The study investigated the effects of palatal depth and a resin anchoring system on the adaptation of denture base resin to the master cast after compression molding and heat polymerization.

Materials and Methods Forty‐eight virtually identical polymethyl methacrylate dentures were fabricated on master casts with either a deep or shallow palatal vault. One half of the master casts of each palate type were altered by the addition of anchoring holes along the posterior land area, as well as perpendicularly in the midsaggital area. Anchoring holes were made with a #8 round bur to a depth of 5 mm. Twenty‐four hours after polymerization, the bases on their casts were sectioned at the posterior border and evaluated for degree of adaptation using a traveling microscope. Maladaptation at the interface of the denture base and master cast was measured at predetermined mediolateral locations. A split‐plot analysis of variance (α= 0.05) was performed followed by a post‐hoc Dunn Multiple Comparison Test.

Results In general, depth of the palatal vault did not significantly influence denture palatal discrepancy (p= .0780), but the use of the anchoring system significantly reduced mean gap distances (p= .000). At lateral and midpalate locations, gap distances between the denture bases and their casts were reduced from approximately 0.3 mm to approximately 0.1 mm when the anchoring system was used.

Conclusion Mean gap distances for steep palate dentures were significantly less than shallow palate dentures at vestibule and lateral palate locations, and anchoring holes placed in an edentulous master cast along the posterior land area and at the midline significantly improved the adaptation of denture bases.
Color stability of provisional restorative materials after accelerated aging
Authors: Doray Pamela G. , Li Dongfang , Powers John M.
Published: August 2004

Purpose Color of 11 provisional restorative materials (4 acrylic resins and 7 resin composites) was evaluated by reflection spectrophotometry immediately after fabrication, after aging for 15 kJ/m2, and after aging for 60 kJ/m2 to determine relative color stability under experimental aging conditions.

Materials and Methods Specimens of provisional restorative materials were polymerized according to manufacturers' instructions and aged in an artificial aging chamber with exposure to a total ultraviolet irradiation of 60 kJ/m2 in increments of 15 kJ/m2. Color was measured by CIE L*a*b* on a reflection spectrophotometer before and after aging. Color change (ΔE*) was calculated and analyzed statistically by analysis of variance with repeated measures after 15 and 60 kJ/m2 intervals of aging.

Results Statistically significant changes in color were observed after accelerated aging at both the initial and final aging intervals. Five of the 11 provisional materials tested showed perceptible color change (ΔE* from 3.6 to 9.3) after accelerated aging of 15 kJ/m2. Seven of the 11 provisional materials tested showed perceptible color change (ΔE* from 3.4 to 9.4) after accelerated aging of 60 kJ/m2.

Conclusion Clinically perceptible color changes (ΔE*Δ 3.3) can be expected in some acrylic resin and composite resin provisional materials after accelerated aging.
Analyzing the etiology of an extremely worn dentition
Authors: Verrett Ronald G.
Published: August 2004

Patients requiring extensive restorative care frequently exhibit significant loss of tooth structure. Specific clinical findings in an extremely worn dentition may vary widely and are often confusing. Severe wear can result from a mechanical cause, a chemical cause, or a combination of causes. The location of the wear, the accompanying symptoms and signs, and information gained from the patient interview are essential components in determining the etiology. A diagnostic decision tree facilitates a systematic analysis and diagnosis of dental wear.
A new device to improve cast articulation procedures
Authors: Gunderson Ronald Bruce , Siegel Sharon Crane
Published: August 2004

Achieving accurate cast articulation is a challenge for dentists and dental technicians. To ensure accuracy, a convenient, efficient, and predictable technique is needed to stabilize dental casts together, even when the casts are wet. The purpose of this article is to describe the use of a device specifically designed to secure casts together during the articulation process.
The use of biomechanical orthodontic treatment concepts for removable appliances in maxillofacial prosthodontics. Part I: Review of prosthesis design principles
Authors: van Putten Meade C.
Published: August 2004

Maxillary cuspids are commonly included in ablative block resections in maxillectomy patients. Although the remaining incisors are poor abutments for interim or definitive obturators, they must be used if adequate retention and support is to be achieved. Orthodontic biomechanical concepts for removable appliances offer solutions for the treatment of these patients. The proper application of these concepts can improve retention, support, and force distribution to the anterior teeth and is particularly useful in younger patients when long‐term maintenance of teeth is critical. The purpose of this article is to describe the rationale for this approach and its application to interim and definitive Aramany Class I and II obturators.
Effect of dowel space preparation and composite cement thickness on retention of a prefabricated dowel
Authors: Hagge Mark S. , Wong Ralan D. M. , Lindemuth James S.
Published: August 2004

Purpose This investigation examined what effect cement thickness had on retention of prefabricated endodontic dowels luted with a composite resin cement (Panavia 21 OP; J Morita, Irvine, CA) into canals previously obturated with gutta percha and a eugenol‐based sealer.

Materials and Methods Sixty‐four single‐rooted teeth were decoronated, filed, cleaned, and sequentially shaped with sizes 2–5 Gates Glidden drills (Dentsply/Maillefer, Tulsa, OK) and 0.12 taper rotary instrumentation. Teeth were then divided into 4 groups of 16 specimens each. All specimens were obturated with gutta percha and a eugenol‐based sealer. Dowel space preparation and dowel cementation were completed 1 week after obturation. Ten‐millimeter‐deep dowel spaces were prepared using dowel drills with 4 different diameters: size 5 Parapost drill (Group 1; Coltene/Whaledent, Mahwah, NJ); size 5.5 Parapost drill (Group 2; Coltene/Whaledent); size 6 Gates Glidden drill (Group 3; Dentsply/Maillefer); size 6 Parapost drill (Group 4; Coltene/Whaledent). Size 5 Paraposts were then cemented with Panavia 21 OP. After 48 hours of storage, specimens were mounted in polyvinyl chloride (PVC) pipe with acrylic, and the dowels were removed in tensile mode using a universal testing machine at 1 mm/min, with data recorded in kilograms.

Results (all values in kilograms) Group 1 (Parapost 5) mean = 15.07, 95% confidence interval (CI) =±6.11; Group 2 (Parapost 5.5) mean = 25.60, 95% CI =±7.39; Group 3 (Gates‐Glidden 6) mean = 43.15, 95% CI =±7.81; Group 4 (Parapost 6) mean = 37.75, 95% CI =±6.35. Analysis of variance and Bonferroni tests revealed that Group 3 had significantly greater mean retention strength values than Group 1 and Group 2 (p < .05), and that Group 4 had significantly greater mean retention strength values than Group 1 (p < .05).

Conclusions Paraposts cemented with Panavia 21 OP showed significantly greater retention in oversized dowel spaces compared with dowel spaces prepared with the manufacturers' matched dowel‐drill set.
In vitro evaluation of the retention of composite fiber and stainless steel posts
Authors: Gallo John R. , Miller Troy , Xu Xiaoming , Burgess John O.
Published: August 2004

Purpose This study compared the tensile retentive strength of composite fiber‐reinforced dowels luted with a resin cement to stainless steel dowels luted with zinc phosphate cement.

Materials and Methods The crowns of 40 extracted human mandibular premolars were removed with a separating disc 1‐mm coronal to the cementoenamel junction. The teeth were randomly divided into 4 groups (n = 10). A post space was prepared in each specimen to a depth of 9 mm, using the drill supplied by the respective manufacturer. For the stainless steel post group, 1.25‐mm‐diameter posts were cemented with zinc phosphate cement. For the composite fiber reinforced groups, posts with diameters of 1.00, 1.25, and 1.50 mm were luted with a Bisphenol A‐Glycidyl Methacrylate (BIS‐GMA) resin bonding system (Jeneric/Pentron, Wallingford, CT) according to manufacturer specifications. The specimens were stored in a sealed container with a moist environment for 24 hours, placed in a fixture in an 801 Materials Test Systems (MTS) machine (MTS Systems Corp, Minneapolis, MN), and loaded in tension at a rate of 5.0 mm/min until failure. Differences among the 4 groups were determined using a one‐way analysis of variance and Tukey‐B post‐hoc tests (α= 0.05).

Results The mean loads to failure ranged from 43.9 ± 10.4 kg for the stainless steel dowel group to 19.9 ± 5.7 kg for the composite fiber–reinforced 1.00‐mm‐diameter group. The stainless steel post luted with zinc phosphate cement provided significantly greater tensile resistance than all composite fiber dowel groups. The retention of the 1.00‐mm composite fiber–reinforced post was significantly less than the remaining groups.

Conclusions Under the conditions of this study, the stainless steel dowel luted with zinc phosphate cement provided significantly greater retention.
Finite element analysis on dental implant–supported prostheses without passive fit
Authors: Kunavisarut Chatchai , Lang Lisa A. , Stoner Brian R. , Felton David A.
Published: August 2004

PurposeThe purpose of this study is to use finite element analysis to investigate the effect of misfit prostheses, cantilever prostheses, and various occlusal forces on the stress distribution in the prostheses, implant components, and surrounding bone.

Materials and MethodsTwo 3‐dimensional finite element models were constructed: (1) a 2‐implant–supported, 2‐unit fixed partial denture and (2) a 2‐implant–supported, 2‐unit fixed partial denture with a distal cantilever. Variations of the standard finite element models were made by placing a 111‐μm gap between the gold cylinder on either the mesial or distal implant. The effects of load of 100 N were tested on all models. Subsequently, loads of 50 N, 200 N, and 300 N were evaluated on the cantilever model.

ResultsWhen the gap was positioned near to the applied force, the stress in both models increased significantly in the implant components and surrounding bone. The stress increase in each component ranged from 8% to 64% in the non‐cantilever models and 43% to 85% in the cantilever models. The greatest stress was found in the distal gold screw. The effect of the gap was clearly shown by the pattern of stress distribution in both models. Additionally, the presence of a cantilever and excessive occlusal force amplified the effect of prosthesis misfit.

ConclusionsProsthesis misfit influenced the pattern and magnitude of stress distribution in the prosthesis, implant components, and surrounding bone, and the presence of the cantilever or greater occlusal force amplified the effect of misfit.
A maxillary implant overdenture that utilizes angle‐correcting abutments
Authors: Dario Lawrence J.
Published: August 2004

Placement of dental implants to enhance complete denture stability and retention is a well‐accepted treatment modality. Most implant overdenture abutments and related components require parallelism within approximately 10 degrees to function properly. Non‐parallel implant placement as a result of flared maxillary bone may preclude the use of conventional implant overdenture abutments, requiring the use of costly custom abutments or bar prostheses. A case report is presented that illustrates the use of a new, 2‐piece, angled overdenture abutment to accommodate non‐parallel implant placement.
A provisional fixed partial denture that simulates gingival tissue at the pontic‐site defect
Authors: Haj‐Ali Reem , Walker Mary P.
Published: August 2004

A technique is presented for the fabrication of an esthetic, provisional fixed partial denture that compensates for a pontic‐site ridge defect. This provisional restoration enables both the dentist and the patient to evaluate whether this prosthetic approach will adequately camouflage the pontic‐site defect or whether surgical correction of the pontic site should also be considered.
Installing magnetic keepers using laser welding
Authors: Ishikawa Masatoshi , Kashiwabara Toshiya , Ishida Osamu , Ichikawa Tetsuo
Published: August 2004

Magnetic overdenture attachments can provide useful denture retention. A technique is proposed that involves installing the magnetic keeper in the overdenture abutment coping using laser welding. Compared with the conventional cast‐to technique, the new technique provides a suitable contour to the abutment coping with the magnetic keeper and ensures proper mounting in the abutment coping, installing the magnetic keeper easily and effectively.