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Biomedical subjects

G L Polyzois

Publications and source records attributed to G L Polyzois.

At least 19 recordsLinked to original sources
PubMed1992

Adhesion properties of resilient lining materials bonded to light-cured denture resins.

This study compared the adhesive strength of three resilient denture lining materials with different chemical compositions when bonded to visible light-cured (VLC) denture base resin. Shear adhesive strength was evaluated using a simple overlap-joint model. Three different bonding agents were used and the effect of water on the bonding strength was evaluated by a series of samples tested after storage for 4 months. The findings showed that all of the lining materials were acceptable for clinical use but that water storage reduced their bond strength to VLC resin.

Acrylic Resins↗
PubMed1992

Light-cured combination obturator prosthesis.

A technique for the fabrication of an open combination (hard-resilient) obturator prosthesis with VLC materials for patients undergoing partially edentulous maxillectomy is described. VLC denture resins and resilient liners are an exciting innovation in prosthodontic treatment and offer the maxillofacial prosthodontist a wider choice of treatment modalities. The technique and the resultant obturator prosthesis have the following advantages: 1. The ease and rapidity of the technique saves time for both the patient and the maxillofacial prosthodontist by introducing the open obturator prosthesis at the earliest opportunity. 2. The combination open obturator prosthesis provides a stable record base for securing jaw relation records. 3. The thickness and resiliency of the obturator prosthesis can be managed more easily. Flexibility and resiliency can be modified by the thickness of the resilient liner or by adding a rigid scaffolding according to the clinical requirements. 4. Prostheses are easy to repair or modify by using increments of VLC hard or resilient materials. 5. The combination VLC obturator prosthesis provides stability, retention, and decreased weight and obduration of residual palatal defects. 6. The technique can be used for partially edentulous or edentulous patients after maxillary resection.

Acrylic Resins↗
PubMed1991

Cephalometrically predicted occlusal plane: implications in removable prosthodontics.

Although the determination of the occlusal plane is crucial in clinical removable prosthodontics, none of the existing methods gives sufficient guidelines for that purpose. The aim of this investigation was to check the hypothesis that the angulation of the occlusal plane is generally related to the skeletal base of the maxillae. Statistical analysis revealed (1) no strong linear correlation (p greater than 0.05) between the following variables: (a) the length of Cook's plane to Cook's occlusal plane angle, (b) the length of the maxillary plane to the maxillary occlusal plane angle, and (c) the Po Na ANS angle to the occlusal Frankfort plane angle; (2) no parallelism between the occlusal and HIP plane with a mean angle of 4.57 degrees, SD 2.57 degrees, and range of 0 to 9.5 degrees; and (3) no correlation between the predicted and clinically determined occlusal planes (r0.267, t1.797, p greater than 0.05).

Adult↗
PubMed1991

Boundary lubrication and maxillofacial prosthetic polydimethylsiloxanes.

Polydimethylsiloxanes exhibit hydrophobic behaviour and poor wettability. These features impose some problems with the clinical performance of the material when used for the construction of intraoral and extraoral facial prostheses. Surface active agents were added to modify the surface energy of the polydimethylsiloxane and contact angle measurements were carried out to observe wetting characteristics. Five siloxane-alkene oxide block copolymers, one organosilicon quaternary ammonium chloride and an epoxyalkyl silane ester were used as surfactants. The best surfactant in terms of permanency and contact angle lowering achieved a value of 24 degrees when added at 10% level compared with 57 degrees for the unmodified silicone. The fairly high viscosity, combined with a comb-like structure, together with the high hydroxyl number of 75 provided the correct balance of permanence and wetting characteristics.

Dimethylpolysiloxanes↗
PubMed1991

Repairs with visible light-curing denture base materials.

Visible light-curing interpenetrating networks are newly developed materials suitable for several dental applications. These materials have several advantages, including versatility and good physicomechanical properties, but also present some weaknesses, such as increased water sorption and poor adhesion to plastic teeth. The suitability of a visible light-curing resin as a repair material, ie, its bending strength, was examined. Results were compared to those obtained with a self-curing acrylic resin. The visible light-curing resin led to repairs with lower strength.

Acrylic Resins↗
PubMed1990

[Two part siloxane, acrylic obturators for edentulous patients].

Patients who have undergone extensive maxillary resection due to malignant tumors, suffer from severe limitation of speech, deglutition and mastication. Loss of structure in the oral cavity not only causes a loss of function but can cause a great psychological and aesthetic change. One of the most difficult prosthodontic procedures is to construct a functional obturator prosthesis. This paper describes a method for the construction of prostheses which incorporates a removable flexible obturator. This technique overcomes the anatomical problems which limit conventional restoration and provides dentures which are retentive and stable in function and comfortable for the patient to wear.

Acrylic Resins↗
PubMed1990

Improving the adaptation of denture bases by anchorage to the casts: a comparative study.

The purpose of this study was to investigate the adaptation of complete maxillary dentures to stone casts processed by the conventional, and two anchoring, methods. The anchoring methods used holes drilled on the cast and a special flange extended onto the posterior aspect of the maxillary cast. Both anchoring methods improved the adaptation of denture bases by minimizing the discrepancy between the denture base and cast. The greatest discrepancies observed in all methods were at the central portion of the posterior border.

Denture Bases↗
PubMed1987

Dimensional stability of dentures processed in boilable acrylic resins: a comparative study.

An investigation was conducted to evaluate and compare the dimensional stability of three fast boilable denture resins with a conventional and a high-impact denture resin processed with a long-curing cycle. Although the boilable denture resins have been introduced to the dental profession and offer merits such as faster processing, saving time for the dentist, patient, and technician, reduction of energy costs, and dramatic increase in denture laboratory production without adding personnel or purchasing new equipment, the relevant dental literature is sparse. The results of this investigation indicate that all five denture resins produced dentures that shrink. Also measurements between certain teeth showed shrinkages. Linear shrinkages of denture bases and teeth distances were less than 1%. Flange-to-flange and molar-to-molar changes were less than 0.5 mm and 0.2 mm respectively. Maxillary complete dentures processed in boilable resins presented less distortion in the midpalatal area across the posterior section than dentures processed in the conventional heat-cured resin. Although linear changes reported in this investigation were thought to be clinically insignificant, clinical studies should be conducted to establish correlation with laboratory findings.

Acrylic Resins↗
PubMed1987

A study of the occlusal plane orientation in complete denture construction.

A cephalometric study was conducted on eighteen dentulous subjects and fifty-six complete denture wearers to determine the location of the natural and artificial occlusal planes as related to Camper's plane. The results indicated that both the natural and artificial occlusal planes were not parallel to Camper's plane. However, the final anteroposterior inclination of the artificial occlusal plane in complete dentures was almost the same as the inclination of the natural occlusal plane.

Cephalometry↗
PubMed1986

Dimensional accuracy of duplicate dentures prepared by different methods.

The production of a duplicate denture demands a high degree of perfection to maintain dimensional accuracy of the duplicate denture. Duplicate dentures were made by four methods in order to investigate the dimensional accuracy in relation to a master denture. Replicas made from modeling wax (all-wax replica or acrylic resin base-wax teeth replica) demonstrated better dimensional accuracy compared with the all-acrylic resin replicas. It is well known that modeling wax used alone as a temporary denture base is an unsatisfactory material. The inherent shortcomings of the material may be overcome if dentists and patients make their assessment of the duplicate as quickly as possible in the mouth. The other alternative may be the production of a duplicate denture with an acrylic resin base and modeling wax teeth.

Acrylic Resins↗
PubMed1985

Stability of some soluble alginate solutions.

The stability of some water alginates against bacterial degradation was studied. The study was based on viscosity and pH measurements of some typical alginate solutions, containing suitable additives during an extended time period (222 days).

Alginates↗
PubMedDate not supplied

The effect of bonding agents on the bond strengths of facial silicone elastomers to a visible light-activated resin.

Three bonding agents were evaluated to determine their effect on the strength of the bond when Silskin II and Cosmesil SM4 silicone facial elastomers were polymerized to a light-activated denture resin. A silane bonding agent proved to be superior, whereas a light-activated bonding agent had inferior bonding characteristics. Intensive heat aging had no significant effect on bond strength.

Acrylic Resins↗