EXPERIMENTAL STUDY OF EXOTERMIC EFFECTS INSIDE DENTAL PULP CHAMBER WHEN APPLYING DIRECT TECHNIQUE OF MANUFACTURING TEMPORARY CROWN

The aim of this study is to determine the optimal combination of self-curing resins and type of matrix that provides a minimal temperature increase in the pulp chamber during the fabrication of temporary crowns. Material and methods. We designed as experimental model of direct temporary crown fabrication for extracted and than prepared molars. Intrapulpal temperature rise was measured in vitro conditions during polymerization of Protemp II (3M), Protemp 4 (3M), Visalis Temp (Kettenbach), Structur (Voco) and Carbodent (Stoma). Output and peak temperature findings of self-curing resin polymerization were recorded and values ​​of temperature increase in the tooth chamber were calculated. Two types of materials were used to make external anatomical moulds: 1) silicone impression material Panasil Putty Soft of high and low viscosity and Panasil initial contact Light (Kettenbach) to make two-phase impression; 2) transparent thermoplastic polymer Erkodur (Erkodent), sheet of 1.0 mm thick, vacuum pressed. Results and Discussion. We obtained the following finding of the temperature rise inside the pulp chamber (polymer pattern / silicone matrix): Protemp IV (2,2˚C / 0,2˚C), VisalisTemp (3˚C / 0.3˚C), Protemp II (3,3˚C / 0,5˚C), Structur (3,4˚С/0,6˚С), Karbodent (6.7˚C / 3.0˚C). Conclusions. Exothermic effects during intra oral fabrication of temporary crowns can be minimized by polymerization of resins in the silicone mould as this material can absorb and dissipate heat.

Anatomy models using Silicone Moulds - An innovative meth

Introduction: Neuroanatomy specimens like cerebrum, cerebellum, brain stem, etc. when taken out of preservation solution dries up and becomes discoloured within a short span of time. These specimens are easily damaged when used repeatedly and become unfit for teaching. The models of these specimen made with silicone using silicone moulds are similar to the original specimens with excellent surface detailing.Using silicone moulds, models like vertebrae using resin also can be made. Materials and methods : The silicone material used in our study is Moldsil P. For making a silicone mould, an acrylic jar is made, which is little bigger than the specimen. Moldsil P is mixed with hardner and poured into the container so that it fills half the volume of the jar. The specimen is immersed into the silicone in such a way that only its upper half is exposed. After the silicone is hardened, the rest of the specimen is covered with the silicone mixture [Moldsil P+hardener] and allowed to dry. The specimen is taken out and the cavity of the impression is filled with silicone or resin to make a cast. Results & Conclusion: The silicone models of neuroanatomy specimens made using silicone moulds are soft, easy to handle and are exactly similar to the specimens. These are used as an alternative teaching aid. Silicone moulds can be used for taking resin cast of vertebra

Experimental Research on Vacuum Casting of Micro-Gears

This paper discusses the feasibility of vacuum casting of micro-gears by using silicone mould of micro-gears which was designed and manufactured by the author. Orthogonal experiment is adopted to explore the influence of temperatures of mould, resin and solidification and the time of vacuum deaeration upon the shape and size of micro-gears. The result of research shows that formed parts with high precision can be obtained by vacuum casting of micro-gears with silicone rubber mould, and the time of vacuum deaeration greatly affects the shape and size of formed parts of micro-gears

The Use of Rapid Prototyping to Fabricate Liver Tissue Engineering Scaffold

In this papers, the authors described a rapid prototyping method to produce vascularized tissue such liver scaffold for tissue engineering applications. A scaffold with interconnected channel was designed using CAD environment. The data were transferred to a Polyjet 3D Printing machine (Eden 250, Object, Israel) to generate the models. Based on the 3D Printing model, a PDMS (polydimethyl-silicone) mould was created which can be used to cast the biodegradable poly (L-lactic-co-glycolic acid) (PLGA )material. The advantages and limitations of Rapid Prototyping (RP) techniques as well as the future direction of RP development in tissue engineering scaffold fabrication were reviewed.

A Method to Fabricate Liver Tissue Engineering Scaffold

In this paper, the authors describe a rapid prototyping method to produce vascularized tissue such as liver scaffold for tissue engineering applications. A scaffold with an interconnected channel was designed using a CAD environment. The data were transferred to a Polyjet 3D Printing machine (Eden 250, Object, Israel) to generate the models. Based on the 3D Printing model, a PDMS (polydimethyl-silicone) mould was created which can be used to cast the biodegradable material. The advantages and limitations of Rapid Prototyping (RP) techniques as well as the future direction of RP development in tissue engineering scaffold fabrication were reviewed.

Optimization of Process Parameters for Vacuum Casting Micro-Gear

A silicone mould fabrication technique based on vacuum casting was developed and its reproducibility was demonstrated. Orthogonal DOE method was adopted to analyze the effects of vacuum casting process parameters, and the process parameters that had an influence on the quality of the micro-mould cavities were identified and optimized. Micro-casting experiments were carried out using the optimized process parameters and the replicated micro-gears were obtained, these silicone copies were subjected to thorough analysis for dimensional accuracy against the master pattern. The results showed that the fabricated micro-mould was capable of producing functional micro-parts that were able to replicate micro-features, and micro-gears were successfully transferred from the silicone rubber moulds into PU resin pieces under vacuum conditions.