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The functional and esthetic deficit replaced with an acrylic resin gingival veneer.

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 for the fabrication of a gingival veneer.

Acrylic Resins↗

Processed acrylic resin provisional restoration with lingual cast metal framework.

Fixed provisional prostheses are fabricated to maintain, improve, and/or change oral function and esthetics for varying periods. It is important to know when to provide a provisional prostheses and how to make one so that it will meet the needs of the patient. This article describes a modification of the design of a cast metal reinforced processed acrylic resin provisional restoration for extensive, long-term reconstruction with implants, because some of the treatments rendered to patients require temporization for up to 2 years. This design has been used by the authors since 1991, and has resulted in fewer problems of fracture of the provisional restorations. In addition, removable partial dentures are rarely needed, even when large spans exist between remaining abutments in serial extractions. This procedure also permits performing guided bone regeneration for deficient ridges without the problem of transmucosal loading, while still maintaining the patient's esthetics and function after surgery.

Acrylic Resins↗

Subgingival metronidazole in acrylic resin vs. chlorhexidine irrigation in the control of chronic periodontitis.

After initial scaling, root planing and cleaning of subcontact areas, chronic periodontitis patients received oral hygiene instruction consisting of Bass toothbrushing using a sodium fluoride toothpaste, but without stress on interdental cleaning. They were then assigned to two groups, one of which self-administered 0.2% chlorhexidine solution subgingivally, once daily for 4 weeks, while the other was subjected to subgingival application of acrylic resin strips containing 40% metronidazole once weekly for 4 weeks. Plaque Index, Sulcus Bleeding Index, probeable pocket depth and gingival shrinkage were assessed for this treatment period and for a further 8 weeks. Highly significant improvements compared with baseline values were achieved and maintained to the end of the study. There were no significant differences between the groups at any time, except for Sulcus Bleeding Index which at Days 56 and 84 showed metronidazole to be superior. It was concluded that the regimens selected were equally effective in improving periodontal health over a 3-month period.

Acrylic Resins↗

Rat hindlimb joint immobilization with acrylic resin orthoses.

The objective of the present study was to propose an orthosis of light material that would be functional for the animal and that would maintain only the ankle joint immobilized. Male Wistar rats (3 to 4 months old, 250-300 g) were divided into 2 groups (N = 6): control and immobilized for 7 days. Rats were anesthetized with sodium pentobarbital (40 mg/kg weight) and the left hindlimb was immobilized with the orthoses composed of acrylic resin model, abdominal belt and lateral supports. The following analyses were performed: glycogen content of the soleus, extensor digitorum longus, white gastrocnemius, red gastrocnemius, and tibialis anterior muscles by the phenol sulfuric method, and the weight, fiber area and intramuscular connective tissue of the soleus by the planimetric system. Data were analyzed statistically by the Kolmogorov-Smirnov, Student t and Wilcoxon tests. Immobilization decreased glycogen in all muscles (P < 0.05; soleus: 31.6%, white gastrocnemius: 56.6%, red gastrocnemius: 39%, extensor digitorum longus: 41.7%, tibialis anterior: 45.2%) in addition to reducing soleus weight by 34% (P < 0.05). Furthermore, immobilization promoted reduction of the fiber area (43%, P < 0.05) and increased the connective tissue (200%, P < 0.05). The orthosis model was efficient comparing with another alternative immobilization model, like plaster casts, in promoting skeletal muscle alterations, indicating that it could be used as a new model in other studies related to muscle disuse.

Acrylic Resins↗

Effects of chemical disinfectants on the transverse strength of denture base acrylic resins.

The disinfection of dental prostheses by immersion in a chemical solution should be capable of rapid inactivation of pathogenic microorganisms, without causing any adverse effect on the denture base resins. This study evaluated the effect of disinfection immersion on the transverse strength of two heat-cured resins. The denture base resins (Lucitone 550 and QC 20) were polymerized according to the manufacturers' instructions. After polymerization, the specimens were polished, and then stored in water at 37 degrees C for 50 +/- 2 h prior immersion in one of the following solutions for 10 min: 4% chlorhexidine, 1% sodium hypochlorite and 3.78% sodium perborate. The specimens were submitted to disinfection twice, simulating when dentures come from the patient and before being returned to the patient. Ten specimens were made for each group. The transverse strength was evaluated by a 3-point bend test. The flexural strength of the two denture base acrylic resins evaluated remained unaffected after immersion in the three solutions evaluated. In general, the QC 20 resin specimens exhibited lower transverse strength than the Lucitone 550 resin specimens, regardless of immersion solutions.

Acrylic Resins↗

Effect of metal priming agents on bonding characteristics of an acrylic resin joined to SUS XM27 steel.

The purpose of the current study was to evaluate the effect of functional monomers contained in the primers on adhesive bonding of a steel alloy. SUS XM27 steel was primed with one of the following materials; Alloy Primer, Estenia Opaque Primer, and V-Primer. The functional monomers in the primers were a phosphate (10-methacryloyloxydecyl dihydrogen phosphate; MDP) and a thione (6-(4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione, -dithiol tautomer; VTD) for Alloy Primer, MDP alone for Estenia, and VTD alone for V-Primer. The steel disks were bonded with an acrylic resin (Unifast Trad), and bond strength was determined. Of the three primers, both the Alloy Primer (33.3 MPa) and Estenia Opaque Primer (33.9 MPa) materials exhibited far better post-thermocycling bond strength than V-Primer (0 MPa). It can be concluded that the phosphate MDP is effective, whereas the thione VTD is ineffective for bonding SUS XM27 steel.

Acrylic Resins↗

Syncrystallization: a technique for temporization of immediately loaded implants with metal-reinforced acrylic resin restorations.

BACKGROUND: Rigid temporization has been recognized to have a significant impact on the peri-implant tissue response in immediate implant loading since it reduces the mechanical stress exerted on each implant. PURPOSE: A successful protocol for immediate loading of multiple implants depends on an adequate fixation and immobility of the implants to prevent the risk of micromovements in relation to the surrounding bone. The objective of this article was to evaluate a prosthetic concept for an accelerated rigid splinting of multiple implants for same-day immediate loading with metal-reinforced provisional restorations using a technique of welding temporary implant abutments with a prefabricated titanium bar directly in the oral cavity (syncrystallization). MATERIALS AND METHODS: Between June 2004 and January 2005, immediate loading of threaded implants with a metal- reinforced acrylic resin provisional restoration at stage 1 surgery was evaluated in 40 consecutive patients. A total of 192 implants were placed in selected edentulous or partially edentulous patients using the syncrystallization technique. Once the titanium bar was welded intraorally to the abutments, opaque was applied and the provisional restoration was relined and screw-retained the same day. In addition, a comparison of deformations and stress distributions in implant-supported, metal-reinforced and nonmetal-reinforced resin provisional restorations was analyzed in the edentulous mandible by a three-dimensional finite element model (FEM). RESULTS: All of the 192 rigidly temporized immediately loaded implants osseointegrated. An implant success rate of 100% was achieved over a period of 6 months postplacement. No fracture or luting cement failure of the provisional restoration occurred during the observation time. Compared to mere acrylic superstructures, a significant reduction of deformation and strain within metal-reinforced provisional restorations was detected by FEM analysis. CONCLUSION: The results of this study indicate that the syncrystallization technique allows an expedite and adequate rigid splinting of multiple immediately loaded implants. The advantages of the technique are: (1) reduction of treatment time for immediate temporization at stage 1 surgery; (2) predictable fixation and immobility of implants in the early stages of bone healing; and (3) less time for repairing provisional restorations as a result of no or rare fracture.

Acrylic Resins↗

Effect of 4-META adhesive on the bond strength of different metal framework designs and acrylic resins.

The effect of relining the 4-META adhesive resin onto metal alloy of a partial denture framework was tested. Seventy-two metal frameworks with three different retentive patterns were designed. Half of the specimens were treated with 4-META, the other group was left untreated. Thirty-six specimens were first divided into three groups in which 12 samples had different designs of retention, i.e. mesh, ring-shaped and flat plane. Then, each different retentive design was divided into two groups and in one group Lucitone 199 and the other QC acrylic resin were processed. Finally they were subjected to shear test. While samples with adhesive exhibited greater bond strength than the others, samples without adhesive may be ranked in the order mesh, ring-shaped and flat planes with regard to shear bond strength. In samples with adhesive, the flat plane ones displayed better results. Statistically significant differences were observed in the relationships between the groups.

Acrylic Resins↗

Residual monomer concentrations in denture-base acrylic resin after an additional, soft-liner, heat-cure cycle.

OBJECTIVES: To determine the effects on methylmethacrylate (MMA) monomer concentration of a second heat-cure cycle introduced for the purpose of processing a denture soft-liner. METHODS: Two denture-base resins (Lucitone199 and Trevalon; Dentsply International, York, PA, USA) were selected. Heat-cure cycles were S (73 degrees C/90 min + 100 degrees C/30 min); L (73 degrees C/9 h); SM (S + 100 degrees C/2 h); LM (L + 100 degrees C/2 h). Cycles SM and LM thus simulated the effect of a further, soft-liner, heat-cure cycle. Groups (n = 6) of the specimens of the denture-base were prepared in the form of thin polymer disks. Monomer was then obtained from the broken fragments of disks by acetone extraction. Concentrations of MMA monomer were determined by reversed-phase high performance liquid chromatography (HPLC). Two-way ANOVA and independent sample t-tests were used to compare the results. RESULTS: The cycle S, applied to Lucitone199, gave a mean concentration of 1.95 wt% MMA (SD 0.24). The cycle L gave the highest level of residual concentration of MMA monomer in both materials. Cycles SM and LM, applied to Trevalon and Lucitone199, gave significant reductions of residual concentration of MMA monomer (p < 0.05). SIGNIFICANCE: The HPLC method was suitable for determining the amount of residual monomer in the denture-base acrylic resin. A further (soft-liner) heat-cure cycle had a statistically significant effect on reducing residual monomer concentrations, and this may have an effect upon mechanical properties.

Acrylic Resins↗