Cavity Design (cavity + design)

Distribution by Scientific Domains
Medical Sciences71%
Engineering28%

Selected Abstracts

Anatomic Endodontic Technology (AET) , a crown-down root canal preparation technique: basic concepts, operative procedure and instruments

INTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2005
F. Riitano
Abstract Aim, To illustrate the conceptual basis and the operative procedure of the Anatomic Endodontic TechnologyTM (AET) technique and to illustrate the specific instruments used in each phase. Summary, The basic characteristics of the AETTM technique are reported. The instruments and procedure are described in three phases: coronal access, coronal-middle preparation and apical preparation. In the first phase, correct cavity design is described. In the coronal-middle phase, the use of four stainless steel shaping instruments, powered by a reciprocating handpiece is described, incorporating a brushing-milling action against canal walls. During the apical phase, dedicated apical stainless steel and NiTi hand instruments are used to complete the preparation. The stainless steel apical files are used with a 1/4 turn and withdrawal movement whilst the NiTi are used in 360° rotary motion. Key learning points ,,Most current canal shaping techniques do not prepare all the canal walls and can result in over-enlargement in some areas. ,,AETTM defines three regions of the canal: coronal (from the cavo-surface of the access cavity), coronal-middle, and apical. ,,Coronal-middle instrumentation is undertaken with four mechanically driven stainless steel shaping instrument used in brushing-milling action against canal walls. ,,Apical preparation is completed by hand and with the formation of a stop. [source]

Effect of access cavity location and design on degree and distribution of instrumented root canal surface in maxillary anterior teeth

INTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2001
G. Mannan
Abstract Aim The null hypothesis tested in this study was that in single-rooted anterior teeth with simple root canal anatomy, different access cavity designs (,lingual cingulum', ,lingual conventional', ,incisal straight-line') do not influence the ability of endodontic files to plane the walls of the root canals. Methodology, Thirty extracted human maxillary anterior teeth were divided randomly into three groups for each access cavity. The access cavities were prepared according to predefined criteria and the roots embedded in individual polyvinyl-siloxane putty matrices. The matrices allowed these teeth to be split into buccal and palatal halves and to be reassembled. The split teeth enabled removal of pulpal remnants from the root canal system and the walls to be stained with an even layer of permanent black ink. Once dried, the split roots were reassembled in the putty matrices and a step-back filing technique was used to prepare the canals with water irrigation. The canal walls were examined for residual ink staining and scored by three independent assessors using an index devised for the purpose. Results There was good agreement between the assessors. None of the access cavities allowed file contact with the entire root canal wall. The overall (palatal and buccal sections) scores showed significant differences (P < 0.01) between the access cavity groups in the extent to which the canal walls could be filed. The straight-line incisal access cavity had the greatest proportion of instrumented root canal surface. The lingual cingulum access cavity was the worst in this respect. The differences in residual ink scores between the access cavity types were significant for the buccal halves (P < 0.01) but not for the palatal halves (P > 0.05). Conclusions The null hypothesis was proven. Regardless of access cavity design, mechanical preparation did not allow instrumentation of the entire root canal wall. Straight-line access allowed the greatest proportion of the root canal wall to be instrumented and the lingual cingulum access the least. [source]

Experimental study on sulfur trioxide decomposition in a volumetric solar receiver,reactor

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2009
Adam Noglik
Abstract Process conditions for the direct solar decomposition of sulfur trioxide have been investigated and optimized by using a receiver,reactor in a solar furnace. This decomposition reaction is a key step to couple concentrated solar radiation or solar high-temperature heat into promising sulfur-based thermochemical cycles for solar production of hydrogen from water. After proof-of-principle a modified design of the reactor was applied. A separated chamber for the evaporation of the sulfuric acid, which is the precursor of sulfur trioxide in the mentioned thermochemical cycles, a higher mass flow of reactants, an independent control and optimization of the decomposition reactor were possible. Higher mass flows of the reactants improve the reactor efficiency because energy losses are almost independent of the mass flow due to the predominant contribution of re-radiation losses. The influence of absorber temperature, mass flow, reactant initial concentration, acid concentration, and residence time on sulfur trioxide conversion and reactor efficiency has been investigated systematically. The experimental investigation was accompanied by energy balancing of the reactor for typical operational points. The absorber temperature turned out to be the most important parameter with respect to both conversion and efficiency. When the reactor was applied for solar sulfur trioxide decomposition only, reactor efficiencies of up to 40% were achieved at average absorber temperature well below 1000°C. High conversions almost up to the maximum achievable conversion determined by thermodynamic equilibrium were achieved. As the re-radiation of the absorber is the main contribution to energy losses of the reactor, a cavity design is predicted to be the preferable way to further raise the efficiency. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Study of geometric degeneracies in electromagnetic characteristics of magnetron-type corrugated cavity

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 4 2002
Andriy E. Serebryannikov
Abstract A geometric degeneracy that can occur in natural frequencies and external Q factors of magnetron-type cavities is studied. We analyze the causes of its appearance and consider its feasibility to enhance the efficiency of the cavity design. Transcendental frequency-independent equations, the solutions of which can be easily obtained, and efficient estimates based on rigorous analysis are suggested to predict the existence of the degeneracy. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 320,331, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce.10030 [source]

The all-ceramic, inlay supported fixed partial denture.

AUSTRALIAN DENTAL JOURNAL, Issue 2 2010
Part 1.
Abstract The effect of cavity design is a controversial and underrated factor in the clinical success of ceramic inlays and inlay supported prosthesis. Many articles and studies have been conducted into the advantages and disadvantages of isolated aspects of preparation design, but lacking is a review of the most relevant papers which bring together a consensus on all the critical features. Hence, a review and analysis of cavity depth, width, preparation taper and internal line angles is warranted in our attempts to formulate preparation guidelines that will lead to clinically successful, all-ceramic inlay restorations and ceramic inlay supported prosthesis. [source]

Effect of access cavity location and design on degree and distribution of instrumented root canal surface in maxillary anterior teeth

INTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2001
G. Mannan
Abstract Aim The null hypothesis tested in this study was that in single-rooted anterior teeth with simple root canal anatomy, different access cavity designs (,lingual cingulum', ,lingual conventional', ,incisal straight-line') do not influence the ability of endodontic files to plane the walls of the root canals. Methodology, Thirty extracted human maxillary anterior teeth were divided randomly into three groups for each access cavity. The access cavities were prepared according to predefined criteria and the roots embedded in individual polyvinyl-siloxane putty matrices. The matrices allowed these teeth to be split into buccal and palatal halves and to be reassembled. The split teeth enabled removal of pulpal remnants from the root canal system and the walls to be stained with an even layer of permanent black ink. Once dried, the split roots were reassembled in the putty matrices and a step-back filing technique was used to prepare the canals with water irrigation. The canal walls were examined for residual ink staining and scored by three independent assessors using an index devised for the purpose. Results There was good agreement between the assessors. None of the access cavities allowed file contact with the entire root canal wall. The overall (palatal and buccal sections) scores showed significant differences (P < 0.01) between the access cavity groups in the extent to which the canal walls could be filed. The straight-line incisal access cavity had the greatest proportion of instrumented root canal surface. The lingual cingulum access cavity was the worst in this respect. The differences in residual ink scores between the access cavity types were significant for the buccal halves (P < 0.01) but not for the palatal halves (P > 0.05). Conclusions The null hypothesis was proven. Regardless of access cavity design, mechanical preparation did not allow instrumentation of the entire root canal wall. Straight-line access allowed the greatest proportion of the root canal wall to be instrumented and the lingual cingulum access the least. [source]

A new paradigm for operative dentistry

AUSTRALIAN DENTAL JOURNAL, Issue 4 2007
GJ Mount
Abstract It is over 100 years since GV Black gathered together most of the knowledge then current on the caries process and set clear parameters for the discipline of operative dentistry. His four-volume treatise set standards that were relevant for the times and, in fact, were so well described that they remained dominant in this discipline until quite recently. However, over the last 50 years there has been great progress in scientific method and in knowledge of the common diseases of the oral environment, including the caries process, so maybe it is time for change. The term "paradigm" describes a philosophy of science, a generally accepted model of how ideas relate to one another, forming a conceptual framework within which scientific research is carried out. Black defined the paradigm within which further research was to be conducted during the following years and the profession accepted his lead. However, it is not expected that the parameters of a profession should remain unchanged over a substantial period so it is suggested that the dental profession should, at this time, recognize a new paradigm. Improvements in scientific method have led to a better understanding of the oral environment, resulting in extensive changes for this profession. It is suggested that the standards set by Black should be now consigned to history and an entirely new paradigm adopted. First, the profession must recognize that dental caries is a bacterial disease and its primary efforts should be directed towards identification and elimination of the disease prior to initiating repair of the damage that it has caused. Preservation of natural tooth structure is then the next responsibility. There should be maximum use made of preventive strategies, including remineralization, followed by minimal intervention cavity designs and the use of bioactive restorative materials to restore the lesions. The profession should be prepared to move on. [source]