Search

Composites with Nano fillers reinforced by polymer structures are gaining popularity in the field of prosthodontic. Composite materials are being developed to meet the needs of patients, such as heat cure acrylic resins, that used so much in the field of prosthodontic. To evaluate the flexure strength of heat-cure acrylic resin reinforcement with Nano aluminum oxide (Al2O3) after polishing with various abrasive materials. A total of seventy rectangular specimens of heat cure acrylic resin with dimensions (65 mm length x 10 mm diameter x 3 mm thickness) Samples were separated into main seven groups classifications based on the addition of Nano Al2O3 and surface's polishing with different abrasive materials. Each group have (10) specimens. The highest mean value of flexure strength was obtained in group (B) (87, while the lowest value was obtained in group (F) (56.9). It concluded that the flexure strength was decreased in groups (F and G) of heat-cured resin polished with diamond, while it was increased in groups (B and C) polished with pumice, followed by the control group(A), and then by groups (D and E) that polished with colloidal. [ABSTRACT FROM AUTHOR]

Introduction: Dental implants have emerged as the treatment of choice for restoring missing teeth in situations that require functional and aesthetic replacements. The aim of the study was to assess the dimensional accuracy of (1) the resultant casts made from different impression techniques for implants, (2) implant impressions using two types of splinting material for open tray technique, auto-polymerising acrylic resin and light-cure acrylic resin and impression techniques, including non-sectioning and sectioning and rejoining with the same splinting material. Materials and Methods: The present study was conducted to compare the accuracy of direct splinted implant impression techniques. There were four impression techniques selected: (1) direct impression technique with autopolymerising acrylic resin splint, (2) direct impression technique with autopolymerising acrylic resin splint sectioned 17 min after setting and welded with the same resin, (3) direct impression technique with light-cure acrylic resin splint and (4) direct impression technique with light-cure acrylic resin splint sectioned and welded with the same resin. Results: Comparison within the four impression groups with respect to distances X and Y with a master model by Tukey’s post‑hoc procedures shows a statistically significant difference only for Group 1, showing P < 0.05. Conclusion: There is a significant difference in the accuracy of the direct splinted implant impression technique with auto-polymerising acrylic resin without sectioning. Sectioning the auto-polymerising acrylic resin splint after 17 min and rejoining before impression making markedly increase the accuracy of implant impression. Splinting with light-cure acrylic resin shows a more accurate impression than the splint with auto-polymerising acrylic resin. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the influence of labial implant inclination on the retention and stability of different resilient stud attachments for mandibular implant overdentures. Materials and Methods: Four identical mandibular edentulous acrylic resin models were fabricated. For each model, two implants were inserted at the canine areas with different degrees of labial inclination: 0, 10, 20, and 30 degrees. Four experimental overdentures were fabricated over the models and fitted to the implants using resilient stud attachments. Regular retentive inserts (extra-light, light, and medium retention) were used for all implant inclinations, and extended-range inserts (extra-light and medium retention) were used for 30-degree inclination only. Vertical (retention) and oblique (stability) dislodging forces (lateral, anterior, and posterior) were evaluated initially (initial retention) and after overdenture insertion and removal (final retention). Results: After repeated insertions and removals, 30-degree inclination recorded the highest retention and lateral stability, and 0 degrees recorded the highest posterior stability; 20 degrees showed the lowest retention, and 30 degrees recorded the lowest posterior stability. The highest stability and retention values were recorded with light and medium regular inserts, and the lowest values were noted with extra-light regular inserts. Conclusion: Within the limits of this study, moderate labial implant inclination (10 degrees and 20 degrees) was shown to negatively affect retention and anterior/lateral stability, and excessive implant inclination (30 degrees) to negatively affect posterior stability. When implants are inclined labially, it is recommended to use light and medium regular stud attachments to obtain high levels of retention and stability for two-implant--retained overdentures. [ABSTRACT FROM AUTHOR]

Utilizing intraoral bite blocks can aid in stabilizing the mandible during radiation treatment (RT) and minimizing side effects to healthy tissues. This report describes a technique to fabricate a customized acrylic repositioning immobilization bite block that was integrated into the clinical workflow of radiation appointments with no delay in starting RT and with increased patient comfort. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to analyze the reliability of cone beam computed tomography (CBCT) in assessing the grayscale density (GSD) of bone by comparing it with microcomputed tomography (μ-CT) data. Materials and Methods: A total of 50 subjects with lost mandibular molars were included in the study. To assess the bone GSD, a previously fabricated template made of acrylic resin with a 2-mm-diameter metal rod was positioned, and CBCT was performed. The bone biopsies for μ-CT analysis were then obtained during implant surgery. The relationship between GSD assessed by CBCT and data from μ-CT analysis was studied using Spearman's rank correlation. Results: A total of 38 biopsies were available for μ-CT analysis. Positive correlations were identified between GSD and bone volumetric fraction (BV/TV) (r = 0.835, P < .001), bone volume (BV) (r = 0.353, P = .030), trabecular spacing (Tb.Sp) (r = -0.535, P = .001), and mean total volume (TV) (r = 0.470, P = .003). There was a clear positive linear correlation between normal values of GSD (< 700) and BV (r = 0.545). Conclusion: This study demonstrated the correlation between GSD assessed by CBCT and bone density assessed by μ-CT in the posterior mandible. For areas of typical bone density, there seems to be a positive linear correlation between GSD assessed by CBCT and bone density assessed by μ-CT. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the influence of several variables in the frequency of prosthetic teeth fractures in fixed full-arch implant-supported acrylic resin prostheses.Materials and Methods: The influence of each variable was determined after analyzing the results obtained from 161 prostheses after a mean follow-up period of 39.69 months. All patients were treated with standard Nobel Biocare and Biomet 3i implants, and followed a strict prosthodontic protocol.Results: A total of 155 fractures were recorded, all of which took place in 60 prostheses (40% of the total). Statistically significant differences were found among several variables: the arch the prosthesis was on, patient sex, opposing arch characteristics, length of the cantilevers, and whether the structure had mechanical retention. The prostheses that suffered a greater number of fractures were those that had been placed in men, opposing a natural arch, with cantilevers shorter than 10 mm and without mechanical retention. Patient age and presence or absence of a cantilever were not determinants.Conclusion: Tooth fractures in fixed full-arch implant-supported metal-acrylic prostheses are a common complication. Several factors are linked more directly with the need for mechanical maintenance. The design and indications of this type of prosthesis should be carefully considered. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of different surface treatments on luting CAD/CAM composite resin workpieces. Materials and Methods: One-hundred eight (108) composite CAD/CAM block sections (Lava Ultimate) 3 mm in thickness were polished up to 4000 grit and then randomly assigned to 6 experimental groups according to the applied surface treatment (no treatment, sodium bicarbonate [NaHCO3], glycine, alumina [Al2O3], CoJet, and SilJet). After standardized sandblasting procedures, 2 block sections from each group were randomly chosen for the qualitative SEM evaluation of the sandblasted surfaces. The remaining 96 CAD/CAM block sections were luted in pairs using a bonding agent (Single Bond) and a restorative composite resin (Filtek Ultimate). Specimens were aged for 2 weeks in 37°C water with 3000 thermal cycles (5°C/55°C), the microtensile test was performed (n = 30), and the values were statistically analyzed with ANOVA and Tukey's HSD post-hoc test (p = 0.05). Results: The qualitative SEM evaluation of the sandblasted surfaces showed that sodium bicarbonate and glycine had almost no conditioning effect on the CAD/CAM composite resin. In contrast, aluminum oxide, CoJet, and SilJet had a profound conditioning effect on the CAD/CAM composite resin. No treatment, sodium bicarbonate, and glycine specimens were debonded after thermal stressing (0 MPa), while aluminum oxide, CoJet, and SilJet showed high microtensile values (Al2O3: 104.45 ± 18.76 MPa; CoJet: 105.55 ± 11.88 MPa; SilJet: 105.02 ± 20.84 MPa), which were not statistically significantly different from each other. Conclusion: Aluminum oxide-based sandblasting powders are the best choice for the surface treatment of CAD/ CAM workpieces. [ABSTRACT FROM AUTHOR]

Purpose: To compare the bonding performance of three new self-adhesive resin cements to human dentin after storage under two different conditions. Materials and Methods: Buccal, lingual, mesial, and distal dentin surfaces of 36 human molars were abraded to directly below the enamel with #600 SiC papers. The teeth were divided into two main test groups. In the first test group (FT), the cements were kept in a refrigerator (6 ± 2°C) for three months and then used for the test. The remainder of the cements was kept at a constant room temperature of 19 ± 2°C for an additional three months, and then used again for the second test group (ST). Each test group comprised 6 teeth and 24 dentin sections. The cements Clearfil SA (CSA), G-Cem (GC), and Bis-Cem (BC) were applied to the surfaces according to the manufacturers' recommendations. After application of the cements to the flat dentin surfaces and light curing, shear bond strengths were determined at a crosshead speed of 0.5 mm/min. Bond strengths were then calculated and expressed in MPa. Data were analyzed with Kruskal-Wallis and Wilcoxon Signed Rank tests. To investigate the cement/ dentin interfaces using SEM, the buccal surfaces of three additional teeth were used for each test group. Results: The bond strength values of cement groups were significantly different for the FT and ST groups (p < 0.01). GC showed the highest bond strength values of all materials. There was a difference between the bond strength values of the two testing periods for all materials (p < 0.01). Bond strengths significantly decreased after storage at room temperature. Conclusion: Storage temperatures considerably affect the shelf life of self-adhesive resin cements. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Patients who use removable dentures often contact dentists about restoration of a separation or fracture of their acrylic teeth. This causes great discomfort for the patient as well as huge labor and time-consuming procedures for dentists and dental technicians. OBJECTIVES: The purpose of this study was to evaluate the adhesion between self-curing acrylic material and teeth in distillate water and denture disinfection agent. MATERIAL AND METHODS: Five types of self-cure acrylic resin samples' groups were prepared for the study, and were combined with acrylic teeth. First group included teeth samples made without surface modification, second group consisted of teeth samples' surfaces activated with acetone, while in third group, retention holes were made. In fourth group of samples, their surfaces were increased by retention holes and washed twice with monomer, whereas in fifth group of teeth, cervical layers were grinded with a bur. One plate from each group was stored in distilled water (W) and another in Corega Tabs (CT) solution for 30 days at 37oC. Connection between acrylic resin-acrylic tooth was assessed using tensile strength instrument. RESULTS: The highest bonding force was achieved between Villacryl SP and Mifam teeth in the group with retention holes made and surface washed twice with monomer (W: 149.86 ± 5.42 N; CT: 146.38 ± 4.39 N), cohesive type. The lowest adhesion values were observed for tooth surfaces with no changed surface (W: 15.15 ± 3.44 N; CT: 13.49 ± 3.80 N), and with samples washed with acetone (W: 15.8 ± 3.22 N; CT: 12.0 ± 1.0 N). In these cases, the connection had adhesive character. CONCLUSIONS: A proper connection between acrylic teeth and surface of denture base is possible to achieve when both chemical and mechanical methods surface are combined, thus increased by retention elements. [ABSTRACT FROM AUTHOR]

Purpose: To study the relation between irretrievable abutment healing caps (AHCs), temperature, and the torque required to remove the AHCs from implants. Materials and Methods: Twenty implants, 13 mm long and 4.2 mm in diameter, were inserted into four acrylic boxes and covered with acrylic resin. An AHC was screwed into each implant, using a 30 N/cm torque. The acrylic blocks were placed in a 37°C water bath, and subsequently, a block was removed from the bath, the AHCs were cooled, and the torque needed to release each AHC from the implant was measured using a torque wrench. The cooling methods applied were contact with an ice cube for 10 or 25 seconds or spraying of endodontic refrigerant spray for 3 seconds. The control abutments were similarly tested, but without prior cooling. Results: The application of ice cubes for 10 seconds reduced the mean releasing torque from 29.60 ± 1.22 N/cm to 28.55 ± 1.96 N/cm (P = .01). Cooling the AHCs with ice cubes for 25 seconds reduced the mean required releasing torque from 29.6 N/cm to 27.85 ± 1.22 N/cm (P < .001). Cooling the same abutments using endodontic refrigerant spray for 3 seconds reduced the mean releasing torque to 27.74 ± 2.13 N/cm (P < .001). Conclusion: Within the limitations of this study, it is possible to conclude that cooling the AHC reduces the torque required for its release from the implant. This finding may also be relevant to the removal of prosthetic abutments with irretrievable screws. [ABSTRACT FROM AUTHOR]

Copyright of CES Odontología is the property of Universidad CES and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: To measure the vertical occlusal forces transmitted through crowns made of different restorative materials onto simulated peri-implant bone. Materials and Methods: The study was conducted using a masticatory robot that is able to reproduce the mandibular movements and forces exerted during mastication. During robot mastication, the forces transmitted onto the simulated peri-implant bone were recorded using nine different restorative materials for the simulated single crown: zirconia, two glass-ceramics, a gold alloy, three composite resins, and two acrylic resins. Three identical sample crowns for each material were used. Each crown was placed under 100 masticatory cycles, occluding with the flat upper surface of the robot to evaluate the vertical forces transmitted. Two-way analysis of variance was used. Alpha was set at .05. Results: The statistical evaluation of the force peaks recorded on the vertical z-axis showed mean values of 641.8 N for zirconia; 484.5 N and 344.5 N, respectively, for the two glass-ceramics; 344.8 N for gold alloy; 293.6 N, 236 N, and 187.4 N, respectively, for the three composite resins; and 39.3 N and 28.3 N, respectively, for the two acrylic resins. Significant differences were found between materials (P < .0001), except for the comparison between gold alloy and one of the glass-ceramics. Conclusion: Composite and above all acrylic resin crowns were more able to absorb shock from occlusal forces than crowns made of zirconia, ceramic material, or gold alloy. [ABSTRACT FROM AUTHOR]

Background: Conventional heat cure polymerized acrylic resin(unmodified) is most acceptable denture base material in dentistry since decades. It has been modified with reinforcement of fillers and different processing techniques were introduced to enhance its mechanical and physical properties. The objective of this research is to determine and compare the effect of different processing techniques on flexural strength of modified and unmodified denture base acrylic resin. Air circulating oven is introduced for the first time in this study and its efficacy is also compared with other conventional processing techniques. Methods: In this study total number of 114 rectangular specimens were fabricated by conventional heat cured acrylic (Stellon QC 20, Dentsply) for Group A (n=57), and rubber reinforced acrylic resin (High impact, Meadway) for Group B (n=57). Three equipment including water bath, dry oven and air circulating oven were utilized for processing specimens individually. Each sub-group of processing techniques (n=19) were tested for flexural strength through a three-point bending test by a universal testing machine. The statistical analysis initiated with descriptive analysis followed by independent t test for mean comparison of flexural strength of all three processing techniques among both testing group. One-way ANOVA and 2-way ANOVA followed by Scheffe post hoc test were also applied. p-value of 0.05 or less was considered as significant. Results: Statically significant p-value <0.001 was found in response of flexural strength in all processing techniques (water bath, dry oven, air circulating oven) of both testing groups. Water bath processing demonstrated highest flexural strength values in both denture base material used in this study. The unit used for flexural strength was MPa. Conclusion: This study manifested highest flexural strength in conventional and rubber reinforced heat cure samples when processed through water bath. Air circulating oven also presented acceptable flexural strength in conventional heat cure acrylic resin specimens when compared with other techniques. [ABSTRACT FROM AUTHOR]

The aim of this study was to quantify the strain development of screw-retained three-unit implant-supported Procera Implant Bridge restorations. Two groups of screw-retained implant-supported restorations (n = 10) were fabricated by means of casting or computer-aided design/computer-assisted manufacture (CAD/CAM) to fit an in vitro cast situation with two implants. During fixation of the restorations, the emerging strains were recorded using strain gauges attached to the cast material mesially and distally adjacent to the implants. Absolute mean strain development ranged from 29.35 µm/m to 2,665.80 µm/m at the different strain gauge locations. Fabrication method had a significant effect on strain development (multivariate analysis of variance, P = .000), with the cast restorations showing significantly higher strain levels compared to the CAD/CAM-fabricated superstructures. CAD/CAM fabrication of screw-retained implant-supported restorations provides greater passivity of fit compared to conventional fabrication methods such as casting. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated how ribbed design features, including palatal rugae, may be used to significantly improve the structural performance of a maxillary denture under load. Materials and Methods: A computer-aided design model of a generic maxillary denture, incorporating various rib features, was created and imported into a finite element analysis program. The denture and ribbed features were assigned the material properties of standard denture acrylic resin, and load was applied in two different ways: the first simulating a three-point flexural bend of the posterior section and the second simulating loading of the entire palatal region. To investigate the combined use of ribbing and reinforcement, the same simulations were repeated with the ribbed features having a Young modulus two orders of magnitude greater than denture acrylic resin. For a prescribed load, total displacements of tracking nodes were compared to those of a control denture (without ribbing) to assess relative denture rigidity. Results: When subjected to flexural loading, an increase in rib depth was seen to result in a reduction of both the transverse displacement of the last molar and vertical displacement at the centerline. However, ribbed features assigned the material properties of denture acrylic resin require a depth that may impose on speech and bolus propulsion before significant improvements are observed. Conclusion: The use of ribbed features, when made from a significantly stiffer material (eg, fiber-reinforced polymer) and designed to mimic palatal rugae, offer an acceptable method of providing significant improvements in rigidity to a maxillary denture under flexural load. [ABSTRACT FROM AUTHOR]

To compare the depth of cure (DoC) of a colored polyacid-modified composite resin (PAM-C) with a traditional PAM-C and a fine hybrid composite resin using different light-curing units and different radiant energies. Method and Materials: The DoC of the PAM-C Twinky Star (Voco, all shades), the PAM-C Glasiosite (Voco), and the composite resin Z100 (3M ESPE) shades A2 and A4 was determined using a penetrometer test method. The materials were cured in bulk using a halogen-based unit (Elipar Trilight, E = 18 J/cm² and E = 32 J/cm²; 3M ESPE) and an LED curing unit (Elipar Freelight 2, E = 20 J/cm²; 3M ESPE) in split stainless steel molds. Immediately after curing, the height (mm) of the cured material was measured and taken as the DoC. Ranking of means was performed by Student-Newman-Keuls multiple comparison test, and statistically significant differences among mean values were detected with ANOVA. Results: Mean DoC for all materials and shades varied as follows: 4.705 to 8.870 mm (E = 32 J/cm²); 3.672 to 8.050 mm (E = 20 J/cm²); and 4.090 to 7.357 mm (E = 18 J/cm²). Two-way ANOVA revealed that the DoC depended significantly (P < .001) on the shade of the material and the curing device. Moreover, there was a significant interaction (P < .001) between the latter, indicating that the effect of the energy densities differed quantitatively among the shades. Conclusions: In this study, DoC differed significantly among the materials and the shades. Twinky Star shade blue showed the highest DoC compared to Glasiosite and Z100 shades A2 and A4. The curing device with the highest energy density exhibited the highest curing depths. [ABSTRACT FROM AUTHOR]

Objective: Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers. Method and Materials: A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and ΔE values were calculated against the preselected target color (A1). ΔE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. Results: The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured ΔE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match. Conclusion: Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the wear resistance of artificial denture teeth and their human enamel antagonists in a dual-axis chewing simulator. Method and Materials: Four artificial denture teeth—feldspathic ceramic, nanofilled composite resin, experimental acrylic resin with UDMA/PMMA, and interpenetrating polymer networks (IPN) acrylic resin teeth— were tested in this study. Human enamel cusps were used as antagonists. Wear resistance was analyzed by measuring the vertical substance loss and the volume loss of the denture teeth using a laser scanner after 300,000 chewing cycles. In addition, the vertical substance loss of the antagonists was evaluated using an optical macroscope. Data were statistically analyzed using ANOVA. For qualitative analysis of the wear areas, the teeth were sputter coated with gold and evaluated at magnifications of 50× and 1,000× using SEM. Results: The composite resin teeth exhibited wear that was significantly higher than that of feldspathic ceramic but lower than that of acrylic resin teeth (P < .05). Acrylic resin teeth caused no measurable wear on the enamel antagonists. The wear patterns of the feldspathic ceramic and composite resin teeth can be described as attritional, while a fatigue type of wear was observed in the acrylic resin teeth. Conclusion: The lowest total vertical substance loss was found for the combination composite resin-enamel. Based on the results of this study, composite resin teeth seem to be more suitable for dentures opposing natural teeth than ceramic or acrylic resin teeth in terms of wear resistance. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to compare the accuracy of casts obtained from nonsplinted and splinted direct impression techniques employing various splinting materials for multiple dental implants. Materials and Methods: A reference model with four Nobel Replace Select implant replicas in the anterior mandible was fabricated with denture base heat-curing acrylic resin. Impressions of the reference model were made using polyether impression material by direct nonsplinted and splinted techniques. Impressions were divided into four groups: group A: nonsplinted technique; group B: acrylic resin-splinted technique; group C: bite registration addition silicone-splinted technique; and group D: bite registration polyether-splinted technique. Four impressions were made for each group and casts were poured in type IV dental stone. Linear differences in interimplant distances in the x-, y-, and z-axes and differences in interimplant angulations in the z-axis were measured on the casts using a coordinate measuring machine. Results: The interimplant distance D1y showed significant variations in all four test groups (P = .043), while D3x values varied significantly between the acrylic resin-splinted and silicone-splinted groups. Casts obtained from the polyether-splinted group were the closest to the reference model in the x- and y-axes. In the z-axis, D2z values varied significantly among the three test groups (P = .009). Casts from the acrylic resin-splinted group were the closest to the reference model in the z-axis. Also, one of the three angles measured (angle 2) showed significant differences within three test groups (P = .009). Casts from the nonsplinted group exhibited the smallest angular differences. Conclusion: Casts obtained from all four impression techniques exhibited differences from the reference model. Casts obtained using the bite registration polyether-splinted technique were the most accurate versus the reference model, followed by those obtained via the acrylic resin-splinted, nonsplinted, and bite registration addition silicone-splinted techniques. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate and compare the retention strength of three cements commonly used in implant-supported prostheses before and after compressive cyclic loading.Materials and Methods: The working model consisted of five solid abutments, 7 mm in height and with a 6-degree taper, screw retained to five implant analogs secured in a rectangular block of self-curing acrylic. On the abutments, 30 metal Cr-Ni alloy copings were cemented using three luting agents: glass ionomer, resin urethane-based, and compomer cement (n = 10). Two tensile tests were conducted with a universal testing machine, before and after 100,000 cycles of 100 N and 0.72 Hz compressive cyclic loading in a humid environment.Results: Before applying the compressive load, the retention strength of the resin urethane-based cement was slightly higher than that of the compomer cement and 75% greater than the glass-ionomer cement. After compressive loading, the resin urethane-based cement showed the highest percentage of loss of retention (64.45%, compared with 50% for glass-ionomer and compomer cement). However, the glass-ionomer cement showed the lowest mean retentive strength with 50.35 N as opposed to 75.12 N for the compomer cement and 71.25 N for the resin urethane-based.Conclusions: Compressive cyclic loading significantly influences the retention strength of the luting agents tested. All three cements may favor the retrievability of the crowns. [ABSTRACT FROM AUTHOR]

This study aimed to (1) devise a standardized method of polishing and finishing acrylic resins, (2) eliminate the variable linked to the single operator, and (3) guarantee the reproducibility of the conditions in which smoothness surface values are obtained for comparative purposes. Twenty acrylic resin samples were fabricated (Lucitone, Dentsply). Samples in group 1 were manually polished by a single experienced operator, while samples in group 2 were polished using an isoparallelometer. Surface roughness was measured for both groups with a ± 0.01-μm resolution profilometer (Mahr, GD25). Data analysis showed that mechanical polishing results in a more uniform surface quality. This preliminary investigation underscores the merits of a standardized method for polishing dental acrylic resins. This approach can eliminate the effect of human factors, thereby making it possible to assess and compare the inherent features of each polished dental material. [ABSTRACT FROM AUTHOR]

Purpose: Self-etching adhesives partly remove or dissolve the dentin smear layer, causing incomplete resin tag formation or low resin tag density. The quantitative contribution of properly formed resin tags to dentin adhesion was evaluated. Materials and Methods: We assessed how the presence or absence of resin tags affects tubules of human deepcoronal dentin. G-Bond was used to bond Gradia resin composite. To ensure deep tubule penetration, we used a vacuum exsiccator. For eliminating tag formation, dentin tubules were presealed with adhesive and reverse bonded after finishing. Microtensile bond strength (μTBS) was measured on flat specimens and on Class I cavity floors. Thermocyclic loading was used to estimate the influence of resin tags on long-term behavior. Confocal laser scanning microscopy was used to evaluate adhesive interface dimensions. Results: Hybrid layer thickness, tag length, and tag diameter increased under vacuum treatment. Presealing dentin tubules led to a residual tag area of 3.1% with a tag length of 10.8 μm. Under vacuum, 24.7% of the total dentin surface was covered with tags of 87.8 μm. Low C-factor preparations produced superior μTBS (71.8 to 92.7 MPa) compared with high C-factor Class I cavities (47.0 to 67.6 MPa). Thermocyclic fatigue differed from low to high C-factor situations. In Class I cavities, μTBS significantly decreased after thermocycling. On flat specimens, vacuum infiltration led to reduced μTBS after thermocyclic loading. Conclusion: Initially, resin tag formation did not influence the μTBS in either type of C-factor preparation. After thermocyclic loading, μTBS decreased with or without resin tags. Adhesive fracture patterns occurred at the hybrid layer/dentin interface. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the phase separation, extent of dentin demineralization, and curing efficiency of one-step self-etching adhesives placed on dentin and on inert substrate. Materials and Methods: The adhesives tested were G-Bond (GB), iBond (IB) and Clearfil S3 Bond (SB). Two groups (2 × 3) of dentin and inert (gold) specimens were prepared for each product. The films formed on inert surfaces were subjected to mild (1st group) or strong air drying (2nd group) and examined with near- and mid-FTIR microspectroscopy. On dentin (1st group), the extent of demineralization (%DM) was evaluated before and after adhesive treatment plus rinsing with water and acetone by mid-FTIR microspectroscopy. The films formed after strong air drying (2nd group) and 20 s of light curing were rinsed with acetone, and the degree of cure (%DC) was measured by micro-multiple internal reflection FTIR spectroscopy. ANOVA was used to assess the statistically significant differences in %DM and %DC (α = 0.05). Results: In GB and IB, mild air drying produced more water droplets and monomer separation than strong air drying. SB demonstrated the least separation. IB induced the highest %DM. All the adhesives demonstrated the greatest %DC on dentin. On both substrates SB showed the highest %DC values. Conclusion: Phase separation including water and/or monomers was found in all the adhesives. The extent of dentin demineralization and degree of cure varied among the products tested. The degree of cure was higher on dentin than on the inert substrate. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effect of oral moisturizing agents, denture adhesives, and surface treatments on the retention of an acrylic resin test base dislodged from the maxillary alveolar ridges of xerostomic radiotherapy patients. Acrylic resin test bases prepared for 10 edentulous xerostomia patients were subjected to 8 surface treatment methods: method 1 = untreated dry surface; method 2 = use of Biotène oral moisturizer; method 3 = use of Protefix denture adhesive; method 4 = combination of Biotène and Protefix; method 5 = sandblasting of test bases; method 6 = use of Biotène on sandblasted surface; method 7 = use of Protefix on sandblasted surface; method 8 = combination of Protefix and Biotène on sandblasted surface. After each treatment, a tensile testing apparatus was used to dislodge the inserted test bases, and force values (N) were recorded. A significant difference in retentive force was observed between the 4 Protefix groups and those that did not use denture adhesive (P < .001). There were no differences among the 4 combinations of denture adhesive treatments (P > .05). Sandblasting the denture surfaces did not increase retentive forces alone or in combination with any other treatments. Biotène oral moisturizing agent was used in 4 treatment methods, but only had a significant effect on increasing retentive force when used with a nonsandblasted surface (P < .05). Biotène had no effect on retentive force compared to a nonsandblasted surface without moisturizer or when it was used in combination with any other methods. Protefix denture adhesive offered the greatest improvement in retentive force. Sandblasting the intaglio surface did not improve retentive force. Biotène was reported to improve patient comfort but had minimal effect on retentive force; however, Biotène can be assumed to be a more advantageous method of increasing retention compared to sandblasting (P < .05). [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were to assess the treatment outcome of immediately loaded full-arch screw-retained prostheses with distal extensions supported by both upright and tilted implants for the rehabilitation of edentulous jaws and to compare the outcomes of upright versus tilted implants. Materials and Methods: At 4 study centers, 342 Osseotite NT implants were consecutively placed in 65 patients (96 implants were placed in 24 mandibles and 246 implants in 41 maxillae). The 2 distal implants were tilted by 25 to 35 degrees. Provisional full-arch restorations made of a titanium framework and acrylic resin teeth were delivered within 48 hours of surgery and immediately loaded. The final prosthesis was delivered after 3 months of healing. Results: Three implants failed during the first year and another 2 within 18 months of loading in the maxilla. The cumulative implant survival rate for the maxilla was 97.59% for up to 40 months of follow-up. No implant failure was recorded for the mandible. The prosthetic success rate was 100%. Marginal bone loss around upright and tilted implants was similar. Patients were satisfied of their esthetics, phonetics, and function. Conclusion: The preliminary results of this study suggest that immediate rehabilitation of the edentulous maxilla and mandible by a hybrid prosthesis supported by 6 or 4 implants, respectively, may represent a viable treatment alternative with respect to more demanding surgical procedures. The clinical results indicate that immediately loaded tilted implants may achieve the same outcome as upright implants in both jaws. [ABSTRACT FROM AUTHOR]

This report describes the rehabilitation of a patient who was completely edentulous in the mandible with a removable prosthesis supported by implants on four Straumann Wide-Neck implants placed in the positions of the canines and second molars. The Cagliari modified conometry technique was developed to improve and simplify anchorage systems based on conical copings in a removable prosthesis supported by implants. The connection of the removable prosthesis to the implants is obtained by primary conical copings, which are screwed to the implants, coupled to secondary copings equipped with plastic friction devices (Arch-Friction-Soft, Dental Konos). After the secondary copings are positioned on the primary copings, the secondary copings are fixed with acrylic resin to the removable prosthesis in the mouth, with the goal of passive fit. The prosthesis produced with this method is not a classic implant-supported overdenture but is a removable prosthesis completely supported by implants that is shaped like a fixed prosthesis. This type of prosthesis is extremely stable and has modular retention (plastic friction), creating ideal conditions for oral hygiene. The stability of this type of prosthesis results in psychologic comfort and masticatory performance similar to that of a fixed prosthesis but with the hygiene, esthetics, and lower expense of an overdenture. [ABSTRACT FROM AUTHOR]

Correct occlusal relationships are part of the successful prosthetic treatment of edentulous patients. Occlusal checking should be performed via a remount procedure because denture base materials and fabrication procedures cannot provide dimensionally accurate complete dentures. Occlusal errors caused by the adjustment of denture bases to the denture foundation after a certain period of wearing can also be corrected by means of remounting. The following remount procedures for complete dentures are described: fabrication of transfer casts, transfer of a maxillary denture with a facebow, centric relation record, and mounting of dentures with transfer casts in an articulator with a dental stone. Deflective occlusal contacts of denture teeth in centric occlusion can be eliminated by selective grinding and by tooth-guided excursive movements. In complete denture treatment, priority is given to anterior/canine-guided occlusion. [ABSTRACT FROM AUTHOR]

Computer-driven implant dentistry uses the latest technology to coordinate every aspect of implant treatment. It provides a means with which to control the placement of implants with a high degree of accuracy. This is important, since accuracy has a direct bearing on the safety, esthetics, invasiveness, and cost of implant treatment. Computer-driven implant dentistry must be conceived as a chain in which every link is related to the others. Within this chain, there are elements that can be employed to maximize the benefits realized by computer-guided implant dentistry. A scan template is a radiologic template that permits visualization of the prosthetic plan prior to treatment and determines the course of implant treatment from the perspective of esthetics. The SimPlant software program (Materialise) allows implants to be planned in two and three dimensions using data received from a computerized tomographic scan. The resulting implant plan can be transferred to the mouth and implemented by means of a stereolithographic surgical guide (SurgiGuide, Materialise). Finally, the SAFE System (Materialise) is used for guided implant placement. It is associated with dedicated drilling devices and can be used in combination with SurgiGuides or with traditional acrylic resin guides manufactured by the dental lab on a synthetic plaster cast. [ABSTRACT FROM AUTHOR]

Purpose: To determine the optimal thickness of protective oral radiation shields composed of an acrylic resin stent and a lead shield, which are used in head and neck radiotherapy to minimize undesired normal tissue radiomorbidity. Materials and Methods: Intraoral acrylic resin stents and lead shields of different thicknesses were inserted into a specially designed human mandible phantom with thermoluminescent lithium fluoride dosimeter chips (TLD-100) placed on the buccal and lingual sites and exposed to irradiation of different energies. Fifty-cGy irradiation was performed and TLD-100 dose measurements were obtained for each irradiation type, acrylic resin stent thickness, and lead shield thickness. Results: Acrylic resin stents with a 2-mm lead shield reduced 20% and 15% of the normal tissue dose for Co-60 and 6 MV X photon radiations, respectively, whereas the stents with a 4-mm lead shield achieved a higher reduction of the normal tissue dose (30% and 23% for Co-60 and 6 MV X photons, respectively). Conclusion: In protective oral radiation shields, acrylic resin stent thickness has little effect on the reduction of normal tissue dose, but lead shield thickness significantly effects the reduction of normal tissue dose. [ABSTRACT FROM AUTHOR]

The replacement of incisors with an unfavorable hard and soft tissue environment in the maxilla can be a challenging procedure in terms of esthetic outcome. The present report describes the replacement of two hopeless central incisors by newly developed titanium implants (TE Implant, Straumann) for immediate placement. This type of implant was chosen to compensate for the natural esthetics, which became compromised because of periodontitis and an unusual root anatomy. Both incisors presented with an atypical enamel paraplasia characterized by a circumferential enamel projection in apical direction. The consequence was a markedly reduced surface for periodontal attachment. Two weeks after implant placement, two acrylic resin crowns were cemented onto the new temporary titanium abutments. Five months later, the definitive prosthetic restoration was processed by porcelain pressed onto galvanic-cap crowns, which were cemented to standard wide-neck abutments. Control radiographs showed uneventful healing. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the influence of hard and resilient polymerized acrylic resin base materials on the blood flow of the supporting underlying mucosa of mandibular denture wearers during different denture-wearing periods. Materials and Methods: Measurements were carried out on 20 complete denture wearers, 10 with hard bases and 10 with soft ones. The mucosal blood flow underlying the dentures was measured bilaterally in the canine and molar regions using a laser Doppler flowmeter. Baseline measurements were performed before denture wearing and after the dentures were worn for 1 week, 1 month, 3 months, and 6 months. Results: Mean blood flow to the mucosa after 1 week was significantly lower in the measured regions than that obtained before the dentures were worn. Blood flow in the canine region returned to almost normal levels 6 months after beginning to wear complete dentures. However, blood flow in the molar region of the denture wearers in the hard base group increased after 6 months, whereas blood flow values did not return to the levels recorded before denture insertion in the soft lining group. Conclusion: It appears that wearing dentures hinders blood flow to denture-supporting tissues, even when soft liners are used. [ABSTRACT FROM AUTHOR]

Purpose: The precision of a computer-aided design/manufacturing (CAD/CAM) system to manufacture zirconium dioxide copings with a predetermined internal space was investigated. Materials and Methods: Two master models were produced in acrylic resin. One was directly scanned by the Decim Reader. The Decim Producer then manufactured 10 copings from prefabricated zirconium dioxide blocks. Five copings were prepared, aiming for an internal space to the master of 45 µm. The other five copings were prepared for an internal space of 90 µm. The second test model was used to try in the copings produced. The obtained internal space of the ceramic copings was evaluated by separate measurements of the master models and inner surfaces of the copings. The master models were measured at predetermined points with an optical instrument. The zirconium dioxide copings were measured with a contact instrument at the corresponding sites measured in the masters. Results: The first group of copings had a mean internal space to the scanned master of 41 µm and of 53 µm to the try-in master. In general, the internal space along the axial walls of the masters was smaller than that along the occlusal walls. The second group had a mean internal space of 82 µm to the scanned master and of 90 µm to the try-in master. Conclusion: The aimed-for internal space of the copings was achieved by the manufacturer. The CAD/CAM technique tested provided high precision in the manufacture of zirconium dioxide copings. [ABSTRACT FROM AUTHOR]

Purpose: Occlusal transducer foils using piezoelectricity or pressure-dependent electric resistance are potential candidates for a measurement system for both absolute levels and changes in bite force. This preliminary in vitro study evaluated the possible usefulness of such transducer foils in the assessment of occlusal forces in centric occlusion. Materials and Methods: Piezoelectric force transducer foils 33 µm thick were placed between pairs of teeth with the dentition in centric occlusion. Occlusal forces were recorded in five patients, who were instructed to bite as hard as possible for about 1 second. Acrylic resin casts of each pair of antagonistic teeth were aligned with the help of interocclusal records. The casts were mounted in a jig, where a defined load could be applied. The ratio of applied force and measured sensor signal permitted a set of calibration factors. Results: A correction factor for each pair of teeth helped determine the ratio by which measured occlusal force exceeded actual tooth load. Differences in occlusal morphology gave rise to a wide span of correction factors (1.01 to 2.80). Steep cusp angles resulted in a wedge action that gave rise to a strong increase in occlusal forces, which were about twice as high as actual tooth load, with wide variation. Conclusion: This method of bite force measurement eliminated the influence of occlusal morphology by individual correction for each pair of opposing teeth. To measure the absolute load of antagonistic teeth with thin film transducer foils, one must take into account individual occlusal morphology. Forces measured with the films are a function of both actual tooth load and occlusal morphology. [ABSTRACT FROM AUTHOR]

Objectives: Laboratory tests confirmed superior physical properties of fiber-reinforced resin composites; however, clinical failures continue to be observed. This in vitro study introduces a new method to measure strain and fracture resistance in glass fiber-reinforced pontics. Method and materials: Thirty standardized pontics in five groups were fabricated. Pontics were reinforced with: glass fiber (group 1); glass-fiber bundle surrounded by glass-fiber mesh (group 2); glass fiber with glass-fiber mesh parallel to the pontic's occlusal surface (group 3); or glass-fiber mesh parallel to glass-fiber bundle (group 4). Unreinforced resin composite pontics served as controls (group 5). A laser interferometer measured inner strains (urn/mm) in sectioned pontics, occlusally loaded with 250 N and 450 N, with a universal testing machine. Inner strains were measured on three levels (1, 2, and 3). Specimens were then loaded to crack onset, and loads were recorded. Comparisons were made using analysis of variance. Kruskal-Wallis and Fisher's exact tests were used, respectively, for nonparametric and categorical data. Results: Group 3 showed significantly lower mean strain values than controls. No significant differences in maximal inner strain values or crack onset loads were recorded. The framework of Group 3 inhibited crack propagation significantly better than that in groups 2 and 5. Conclusion: Within the limitations of this study, speckle interferometry proved to be a promising method for analyzing strains of pontics under load. The tested framework designs in this study had only limited influence on load-to-crack onset. When strategically placed, a glass-fiber mesh prevented crack propagation. (Quintessence Int 2004:35:668-675) [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this case report is to demonstrate the benefits and applicability of appropriate maxillofacial prosthetic rehabilitation following surgical resection of ameloblastoma of the maxilla in Kenya. Materials and Methods: Five patients presenting with ameloblastoma of the maxilla over 3 years were studied with respect to histologic type, site of tumor, resultant surgical defect, and form of definitive obturator prosthesis. Impressions were taken using irreversible hydrocolloid and poured with dental stone. Immediate surgical obturators were fabricated from casts using clear autopolymerizing acrylic resin. One patient had bilateral partial maxillectomy, whereas the rest had unilateral partial maxillectomy. Immediate surgical obturators were fitted intraoperatively and held in place using Adams clasps on the remaining natural dentition for all patients, except the one who had undergone bilateral partial maxillectomy, whose surgical obturator was held loosely using circumzygomatic wires. After 6 to 8 weeks, surgical obturators and packing were withdrawn, and new impressions were taken to fabricate definitive obturators. Patients were reviewed every 2 weeks for 3 months, then once every 3 months per year for 3 years, and thereafter once per year. Results: The immediate surgical obturators facilitated retention of the surgical packing, promoting healing with minimal postsurgical infection and scar contracture formation. This ensured the restoration of acceptable esthetics and maintenance of oral function at a reasonable level during the initial postoperative period. Definitive obturators restored esthetics, oral function, and ability to handle secretions to a satisfactory level. Conclusion: Satisfactory functional and esthetic results are achievable in patients with extensive acquired maxillary defects by means of obturator prostheses fabricated using readily available materials. [ABSTRACT FROM AUTHOR]

Purpose: This study compared the effect of two postpolymerization heat treatments on the cytotoxicity of three denture base resins on L929 cells using 3H-thymidine incorporation and MTT assays. Materials and Methods: Sample disks of Lucitone 550, QC 20, and Acron MC resins were fabricated under aseptic conditions and stored in distilled water at 37°C for 48 hours. Specimens were then divided into three groups: (1) heat treated in microwave oven for 3 minutes at 500 W; (2)heat treated in water bath at 55°C for 60 minutes; and (3)no heat treatment. Eluates were prepared by placing three disks into a sterile glass vial with 9 mL of Eagle's medium and incubating at 37°C for 24 hours. The cytotoxic effect from the eluates was evaluated using the 3H-thymidine incorporation and MTT assays, which reflect DNA synthesis levels and cell metabolism, respectively. Results: The components leached from the resins were cytotoxic to L929 cells when 3H-thymidine incorporation assay was employed. In contrast, eluates from all resins revealed noncytotoxic effects as measured by MTT assay. For both MTT assay and 3H-thymidine incorporation, the heat treatments did not decrease the cytotoxicity of the materials tested. Conclusion: Resins were graded by 3H-thymidine incorporation assay as slightly cytotoxic and by MTT assay as noncytotoxic. Cytotoxicity of the denture base materials was not influenced by microwave or water bath heat treatment. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study evaluated the effects of surface treatments and thermocycling on the bonding of autopolymerizing silicone soft denture liner (Sofreliner) to denture base resin. Materials and Methods: The bonding surfaces of denture base cylinders were polished with 600-grit silicon carbide paper and pretreated with applications of Sofreliner Primer, Sofreliner Primer after air abrasion, Reline Primer, or Reline Primer after air abrasion. Failure loads and elongation at failure were measured after subjecting specimens to 0, 10,000, 20,000, and 30,000 thermocycles. Failure modes were assessed for all specimens. Seven specimens were fabricated for each of 16 groups, including four pretreatments and four thermocycle groups. Results: Failure loads of the Sofreliner Primer group were significantly higher than those of the air-abrasion group up to 20,000 thermocycles; both groups showed cohesive failures of the soft denture liner. Failure loads of the Reline Primer group were significantly higher than with Reline Primer after air abrasion up to 10,000 thermocycles. Failure mode after 10,000 thermocycles was cohesive for the Reline Primer group and mixed cohesive/adhesive for Reline Primer after air abrasion. Failure loads of the Sofreliner Primer group were significantly higher than those of the Reline Primer group at each thermocycling interval. Elongation values decreased after 10,000 thermocycles for all groups. Conclusion: Air abrasion on the denture base resin surface was not effective in enhancing failure load. Cyclic thermal stress is one factor degrading the bond between soft denture liner and acrylic resin denture base. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to use wear simulation to develop wear rates far two modern composite systems and then compare these rates with clinical studies on the same materials. Method and materials: A spring-loaded piston wear simulator was used to generate localized wear rates for P50 and Z100 at 100,000, 200,000, 300,000, and 400,000 cycles. Clinical studies on P50 and Z100 conducted at Creighton University and the Catholic University of Leuven were used for comparison of clinical wear to the laboratory values. Regression analysis was employed to define the wear rates. Results: The laboratory wear rates determined with simulation for P50 and Z100 were similar. Clinical occlusal contact area (OCA) wear for P50 and Z100 had small differences and were pooled to provide comparison with laboratory data. Wear rates determined from linear regression analysis provided equivalency factors between laboratory localized wear and clinical OCA wear that could be used for future studies. Further regression analysis comparing OCA and generalized clinical wear allowed a conversion factor of 4.5 to be determined. Conclusion: Localized wear from laboratory simulation may be a useful predictor of localized clinical wear and also clinical generalized wear using a conversion factor. (Quintessence Int 2004:35: 269-274) [ABSTRACT FROM AUTHOR]

This patient report describes the treatment of a 42-year-old woman with cleidocranial dysplasia. Endosseous implants were used to restore the mandibular and maxillary arches with fixed prostheses. Six implants were placed in the mandible and immediately loaded with an acrylic resin fixed prosthesis. In the maxillary arch, 10 implants were submerged for 4 months prior to functional loading. A transitional denture was relined and placed in the maxilla 10 days after implant placement. Three months later, a definitive mandibular prosthesis was fabricated. The definitive maxillary restoration was delivered 6 months after surgery. The most recent follow-up, 6 months after delivery, confirmed a satisfactory treatment result to date. [ABSTRACT FROM AUTHOR]

Purpose: The present study was undertaken to determine the feasibility of using primary stability as a predictor of implant success in patients whose implants were immediately loaded. Materials and Methods: The study included 40 patients, in whom a total of 190 implants were placed, 102 in maxillary sites and 88 in mandibular sites. All were loaded within 72 hours of placement. Sixteen patients were completely edentulous in the mandible and/or the maxilla. The remaining 24, who were partially edentulous, received fixed partial dentures or single-implant restorations. All of the definitive implant restorations were screw retained. The criterion for loading was clinical judgment of primary stability, verified by a "screw test." Impressions were made after implant placement to facilitate the fabrication of a laboratory-made heat-processed provisional restoration from acrylic resin. Following a 4-month period for osseointegration and soft tissue healing, definitive fixed prostheses were fabricated. Results: There were no surgical complications. After 1 to 2 years, all 190 implants had survived and were considered 100% successful, as determined by independent testing of mobility and radiographic evidence of osseointegration. In 4 patients, fracture of the provisional restoration occurred during the healing period. Discussion: Clinical research has shown that immediate loading is a viable treatment modality. The favorable success rate reported in this study for rough-surfaced implants suggests that adherence to a protocol, an important parameter of which is primary stability above 32 Ncm, can lead to osseointegration. Conclusion: The results of this limited investigation suggest that patients who are partially or completely edentulous may be immediately restored with implants and fixed provisional restorations, provided that the dental implants are adequately stable immediately after their surgical placement. This alternative therapeutic approach did not appear to affect the up-to-2-year survival of the implants in this patient population. [ABSTRACT FROM AUTHOR]

The Hallermann-Streiff syndrome (HSS) is a rare congenital disorder characterized by dyscephaly, birdlike facies, hypoplastic mandible, congenital cataracts, microphthalmia, hypotrichosis, skin atrophy, proportionate short stature, and dental anomalies. A case of a 29-year-old man with atypical HSS with neither cataracts, hair and skin alterations, nor short stature is reported, with special consideration to oral findings and dental management. Dental extractions, scaling, restorations, and endodontics were performed under local anesthesia. Later, orthodontic rehabilitation with fixed brackets was carried out. Finally, a removable partial denture for the maxillary arch was designed using transparent acrylic, and this also served as a retention splint. Young patients with HSS and other similar syndromes must be involved in personalized oral health prevention programs as early as possible. Despite numerous systemic anomalies, some of these patients may undergo conventional dental procedures under local anesthesia in the dental office. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess the reliability of the planning software of an image-guided implant placement system based on a mechanical device coupled with a template stabilized on soft tissue during surgery. Materials and Methods: Thirty consecutive partially or completely edentulous patients were treated with the image-guided system. For each patient, a study prosthesis was fabricated and duplicated in acrylic resin and served as a scanning template. Axial images were obtained from a computerized tomographic scan and transferred to planning software that provides real 3-dimensional information to plan implant position. Once the final position of the implant was defined, preoperative data such as the size of implants and anatomic complications were recorded using the planning software. The scanning template was then drilled in that exact position by a drilling machine. During surgery, the drilled template was used as a drill guide. After implant placement, intraoperative data were recorded and statistically compared with the preoperative data using the Kendall correlation coefficient for qualitative data and the Kappa concordance coefficient for quantitative data. Results: Agreement between the preoperative and intraoperative data was high for both implant size and anatomic complications. The Kendall correlation coefficient was 0.8 for the diameter and 0.82 for the length. The Kappa concordance coefficient was 0.87 for both dehiscence and bone graft, 0.88 for osteotomy, and 1.0 for fenestration. Discussion: In the few instances where planning was not perfect, implant placement was completed in a clinically acceptable manner. Conclusion: The results suggest that the image-guided system presented is reliable for the preoperative assessment of implant size and anatomic complications. It may also be reliable for flapless surgery. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the effects of thermocycling on the retention of glass-fiber and resin posts. Method and materials: Forty premolar and canine tooth roots were embedded in acrylic blocks shaped to fit into a retention device. The roots were randomly assigned to two groups of 20 to receive either Lightposts or Luscent Anchors which were cemented into 9-mm-deep post spaces, with Panavia F resin cement. Each group was randomly divided into two equal subgroups: one for thermocycling, and the other to serve as a control. The thermocycled specimens were cycled 3,000 times between water baths at 5ºC and 55ºC, with a dwell time of 60 seconds in each. Control specimens were stored at 37ºC. The tensile force required lo dislodge each post from its root was recorded and the data analyzed using Student's t tests. Results: There were no significant differences in the forces required to cause post-retention failure between the control and tnermocycled specimens. Lightposts were significantly more retentive than Luscent Anchors without thermocycling. but this distinction was not apparent in the thermocycled groups. Conclusion: Glass-fiber and resin posts cemented with resin cement offer acceptable levels of retention and are not susceptible to reduced retention from thermocycling Thermocycling should be given less emphasis in tests tor the retention of root canal posts cemented with resin cements. (Quintessence Int 2003;34:366-369) [ABSTRACT FROM AUTHOR]

The article discusses the fabrication of a full-arch acrylic resin diagnostic provisional from a diagnostic waxup which eliminates uncertainty from dental restorations. A sample case involving a 65-year-old male patient is presented which illustrates the technique for achieving predictable restorative outcomes using a diagnostic provisional. Several photographic images related to the restoration process are presented, including preoperative full facial view and preoperative maxillary view. A set of diagnostic casts is also described.

The purpose of this study was to compare the effectiveness of three methods using calcium sulfate as a graft/barrier for the treatment of Class II mandibular furcation defects. Thirty-six defects in 17 patients were treated with a graft/barrier of pure calcium sulfate, calcium sulfate plus doxycycline, or demineralized freeze-dried bone allograft (DFDBA) in a 2:1 ratio by volume. Defects were randomly selected for treatment, and all measurement parameters were standardized to a light-cured acrylic resin stent at baseline and 6, 9, and 12 months. Linear regression, ANOVA, and chi-squared analysis revealed that all three groups showed significant bone fill (P < .05), vertical and horizontal probing depth reduction, defect volume reduction, and a gain in vertical clinical attachment. Furthermore, the addition of either doxycycline or DFDBA to calcium sulfate significantly enhanced the clinical outcome more than did the calcium sulfate alone, and the addition of DFDBA was more effective in the treatment of Class II mandibular furcation defects than doxycycline. [ABSTRACT FROM AUTHOR]

Purpose: To determine the depth of cure resulting from three different curing devices in a photoactivated microhybrid composite through high-performance liquid chromatography (HPLC) analysis of leachable monomers. Materials and Methods: Three different curing units, a halogen lamp (Heliolux, Vivadent), a xenon lamp (Kreative Kuring, Allyn Welch), and a plasma-arc lamp (Apollo 95, DMDS) were investigated using a universal microhybrid composite (P 60, 3M) as the test material. To assess the effect of curing device variation, a flexural strength test was performed. In addition, samples of composite were prepared and cured "in contact" (0 mm between the sample surface and light-guide tip) and through a specific thickness of composite (1, 2, or 3 mm). The monomers (bis-GMA and UDMA) eluted from the samples were detected by HPLC. Results: No significant differences were found in the mechanical properties of composite cured with different light sources. In contrast, the concentration of eluted monomers (bis-GMA, UDMA) at a depth of 2 mm and more was significantly higher for the specimens cured with the high-power curing devices than those cured with the traditional halogen lamp. Conclusion: Under these experimental conditions, high-power curing devices were shown to be inferior in the deep polymerization of resin composite when compared to a traditional halogen lamp. [ABSTRACT FROM AUTHOR]

Periodontal attachment loss in the maxillary anterior region can often lead to esthetic and functional clinical problems including disproportional and elongated clinical crowns, visible interdental embrasures, and altered linguoalveolar-labiodental consonant production. Assuming fixed prosthetic reconstructions will be chosen to treat these areas, it becomes a hygienic compromise to fill these areas in with porcelain. In the presence of these problems, an acrylic resin gingival veneer is an easily constructed, inexpensive, and practical device to optimize the esthetic and functional outcome in these special situations while permitting cleansibility of the prosthesis and supporting tissues. This article presents a step-by-step technique tor the fabrication of a gingival veneer. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated stress distribution in metal frameworks constructed on implants under masticatory forces using computer simulations. Materials and Methods: Three-dimensional finite element analysis was used to study four different veneering materials--metal framework combinations using Calcitek implants. The veneering materials used in the study were porcelain, heat-polymerized poly(methyl methacrylate) resin, microfilled composite resin, and glass-modified composite resin. All computations were conducted for different levels on the buccal and lingual sides. Results: Changing the veneering material on the prosthesis produced significant effects on stress levels and stress distribution on the metal frameworks. Stresses were concentrated along the marginal area of the prosthesis. Acrylic resin showed greater displacement than porcelain, probably because of its lower modulus of elasticity. Conclusion: In comparison to porcelain, more stress is borne by the acrylic resin--veneered metal framework under static loading. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate clinical usefulness and durability of continuous glass-fiber reinforcement in repair of acrylic resin removable dentures. Materials and Methods: Fractured removable dentures without reinforcement, with conventional metal-wire reinforcement, or with mesh reinforcement were collected from two dental schools in Finland. The total number of dentures was 51 and the number of patients was 48. During the repair, the dentures were reinforced with a polymer-preimpregnated E-glass fiber at the region of the fracture. The fibers were used as partial fiber reinforcement, ie, only the weakest part of the denture was reinforced. Follow-up time varied from 4 months to 4.1 years. After the follow-up period, possible fractures and discoloring were visually inspected. Possible irritation of oral mucosa by glass fibers and the general shape of the denture were also evaluated. Results: In 88 % of the cases, there was no need for adjustment at the region of partial fiber reinforcement, and the clinical condition of the dentures was good. Glass fibers did not irritate the oral mucosa. In the case of refracture or hairline fracture, positioning of the partial fiber reinforcement was incorrect or the reinforcement had been used incorrectly (the wetting of the reinforcement with denture base resin was inadequate). Conclusion: Polymer-preimpregnated partial fiber reinforcement seems to be useful in eliminating fractures of acrylic resin removable dentures. However, this study emphasizes the importance of correct positioning and accurate laboratory technique when partial fiber reinforcement is used. [ABSTRACT FROM AUTHOR]

The aim of the present study of single-tooth implants was to compare the success rate and marginal bone resorption of a narrow-diameter self-tapping implant placed in less available bone volume with the standard-diameter self-tapping implant placed in a well-dimensioned alveolar process. A new abutment technique and a different permanent abutment design were also evaluated. Fifty-five patients were included in the study; 27 patients received 28 standard-diameter (3.75-mm) implants, and 28 patients received 32 narrow-diameter (3.25-mm) implants replacing either a central or a lateral incisor in the maxilla. In an attempt to create an ideal emergence profile and to regenerate papillae, individual acrylic resin tooth-shaped temporary abutments were fabricated, based on impressions made immediately following implant placement, and connected to the implant after 6 months. A minimum of 2 months were then allowed before definitive restorative procedures were performed. Impressions were always made at the implant level. Follow-up examinations were performed at 6 months after loading and 1, 2, and 3 years after loading. Two narrow-diameter implants were lost after 6 months, but no other failures were subsequently observed in any of the groups after that. In both groups, marginal bone loss followed the same pattern and was recorded radiographically to be a mean of 0.4 mm from the first to the last examination. [ABSTRACT FROM AUTHOR]