Search PubMed⌕ Search

Biomedical subjects

P J Milward

Publications and source records attributed to P J Milward.

11 recordsLinked to original sources
PubMed2003

Accuracy of adaptation of thermoformed poly(methyl methacrylate).

Thermoformed poly(methyl methacrylate) (PMMA) sheet is used to produce a number of different dental appliances such as stents, occlusal splints and baseplates for occlusal rims. The purpose of the present study was to measure the accuracy of adaptation of Perspex PMMA sheet and to determine the effect of annealing on the accuracy of the thermoformed specimens. The results of the study showed that PMMA can produce specimens that are accurately adapted to the cast. Immersion in water resulted in an increase in the space between the cast and the specimen for both thermoformed and thermoformed and annealed acrylic resin. Annealing of the thermoformed specimens had significantly less increase in space between the cast and the specimens when immersed in water over a period of 3 months.

Acrylic Resins↗
PubMed2001

The effect of disinfection and a wetting agent on the wettability of addition-polymerized silicone impression materials.

STATEMENT OF PROBLEM: The wettability of silicone impression materials is poor, which may lead to voids within casts. All impression materials should be disinfected before use, but disinfection may affect their wettability. PURPOSE: This study evaluated the effect of disinfection procedures and the use of a surface wetting agent on the wettability of 4 addition-polymerized silicone impression materials. MATERIAL AND METHODS: Testing specimens were made from 4 addition silicone materials (light-bodied President, light-bodied Extrude, medium-bodied Extrude, and Aquasil). Two disinfection solutions (Actichlor and Perform) and 1 wetting agent (Vacufilm) were used. The test conditions were as follows: (A) dry, (B) Vacufilm, (C) Actichlor (10-minute soak), (D) Actichlor (10-minute soak) and Vacufilm, (E) Perform (10 minute-soak), and (F) Perform (10-minute soak) and Vacufilm. A dynamic contact angle analyzer was used to measure the wettability of specimens. Mean results were compared with 1-way ANOVA, and multiple comparisons were made with the Bonferroni method. RESULTS: Treatments C, D, and F had no significant effect on the wettability of the materials. Treatment B significantly reduced the contact angle for light-bodied President (P< .01) and Aquasil (P< .05). Treatment E significantly increased the contact angle for light- and medium-bodied Extrude and Aquasil (P< .001). CONCLUSION: Disinfection with Actichlor is recommended in preference to Perform to maintain the wettability of impression materials. Treatment with Vacufilm after disinfection is recommended to improve the wettability of materials and thus reduce the likelihood of voids within casts.

Analysis of Variance↗
PubMed1997

Automatic identification of dental appliances.

AIM: To develop a reliable, machine-readable coding system for dental appliances. METHODS: Incorporation of two-dimensional bar codes and matrix codes into a range of dental appliances using printed thermal substrates and laser-etched ceramic discs. RESULTS: Problems including reaction of thermal substrates with methyl methacrylate monomer, loss of code clarity, limited areas available for bar codes, difficulty in scanning opaque pigmented acrylic resin and palatal and lingual surfaces were overcome using 4 mm2 data matrix codes etched onto ceramic discs. CONCLUSIONS: Reliable automatic identification of dental appliances was achieved using laser-etched matrix codes. Further development is necessary in relation to optimisation of code size, encryption, scanners and maintenance of code readability over time.

Dental Equipment↗
PubMed1997

A bimaxillary sports mouthguard: a modified technique.

The bimaxillary mouthguard provides enhanced protection for a participant in contact sports. This article describes the fabrication of a polyvinylacetate-polyethylene (PVAc-PE) bimaxillary mouthguard in which the connection of the maxillary and mandibular components is reinforced by pressure thermoforming a 2-mm PVAc-PE sheet over the labial and buccal portions of the mouthguard.

Athletic Injuries↗
PubMed1995

The bimaxillary mouthguard.

The bimaxillary mouthguard provides enhanced protection for the participation in contact sports. This article describes the bimaxillary mouthguard and outlines construction techniques.

Humans↗
PubMed1995

Heat-cured silicone bimaxillary mouthguard.

A laboratory procedure for the construction of a heat-cured, silicone, custom-made bimaxillary mouthguard for contact sports is described. Contours and vertical dimension are easier to control than with the conventional thermoformed product, and there is no danger of injury from contact between the maxillary and mandibular components.

Dental Prosthesis Design↗
PubMed1992

Computer aided technical instruction, (C.A.T.I.).

The article refers to the development of several computer programs designed to fulfil the role of teaching aids in relation to the technological aspects of dentistry. The hardware used was a BBC Master computer, this being a deliberate choice, to demonstrate that it is not necessary to have state of the art computer technology in order to produce very satisfactory computer aided technical instruction packages. All the programs were written in BBC Basic. Computer graphics illustrate and simplify dynamic concepts involved in dental technology. The programs having been developed in house proved to be inexpensive, in addition the program structure allows for easy upgrading. An extract from one of the procedures that serves to make up the modules is included to demonstrate the simplicity of the programming and the modular concept of program development.

Computer Simulation↗
PubMed1991

Effect of the curing cycle on acrylic denture base glass transition temperatures.

Glass transition temperature of a polymer is an important physical property which may have a major effect on the dimensional stability of denture base materials. Thermomechanical analysis has been used to determine the glass transition temperature of specimens of denture base materials which had been produced by various selected curing cycles. It was found that different curing cycles produced variations in glass transition temperature of up to 20 degrees C.

Acrylic Resins↗