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PubMed2003

Composite indirect-direct method for fabricating multiple-unit provisional restorations.

This article describes a method for fabricating multiple-unit provisional restorations by use of the indirect-direct method without the need for abutment preparation on diagnostic casts. Composite is used with fiber reinforcement to create a provisional shell in a vinyl polysiloxane matrix. This method reduces chair time, as well as laboratory time required to fabricate provisional restorations. Control of restoration contours and incisal edge position is also enhanced.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2003

Simplifying single-stage solid abutments: Part 1. Impressions.

Restoration of single-stage implants with solid abutments traditionally requires the use of an impression index cap, an analog and a lab fee commensurate with a more complex restoration. A technique is discussed that utilizes standard crown and bridge techniques that simplifies the lab procedure and reduces the prosthetic costs involved with fabrication of implant borne crowns.

Dental Abutments↗
PubMed1982

Identifying the denture space.

In the absence of pre-extraction records, the positioning of teeth on complete dentures is a somewhat arbitrary procedure. The present study was designed to evaluate a number of different criteria for tooth placement. Miniature foil strain gauges were used to measure the forces brought to bear on complete dentures by the lingual and peri-oral musculature. Previous studies of the pattern of post-extraction resorption found that the vestige of the lingual gingival margins of the maxillary teeth could be identified on the cast and it was suggested that these biometric guides are reliable for the correct placement of the upper artificial teeth. The results reported confirmed the use of biometric guides to tooth placement as a reliable method of positioning the teeth in Class I edentulous cases.

Dental Impression Materials↗
PubMed1985

An experimental comparison of vertical tooth movement of 33 degrees and 0 degree teeth after denture processing procedures.

Movement of teeth during denture processing is an unsolved problem. This study investigates the amount of vertical tooth movement during controlled processing of acrylic, using 33 degrees and 0 degree teeth invested in specific mixes of plaster of Paris or dental stone. Forty sample set-ups each containing four posterior teeth were processed under strictly controlled laboratory conditions. Twenty of these samples carried 33 degrees teeth and the other twenty carried 0 degree teeth. Each group of twenty samples was randomly divided on a factorial design into batches of ten for investment in plaster of Paris or stone. The vertical movements were measured with a greater degree of accuracy than is required for clinical application. All results were analysed statistically. Significantly greater movement occurred with teeth invested in stone than those invested in plaster of Paris. Whereas, for teeth invested in stone, significantly greater movement occurred with 33 degrees than with 0 degree teeth, no such effect was found with teeth invested in plaster of Paris.

Calcium Sulfate↗
PubMed2004

Functional impression and jaw registration: a single session procedure for the construction of complete dentures.

The conventional fabrication of complete dentures involves two separate clinical sessions for functional impression making and jaw registration. The presented method combines both procedures in one session. The aim of this study was to survey the three-dimensional tooth positions in complete dentures with reference to the ridges to establish arbitrary guideline values that could be used for the manufacturing of tooth-position analogue plastic rims on functional impression trays. New complete dentures were fabricated by supervised undergraduate students in the conventional manner for 104 edentulous patients. The position of the maxillary teeth was surveyed in the horizontal plane using the Schmuth 'vizor-measuring plate'. The vertical dimension of occlusion, represented as the distance between opposing ridge areas of the dentures in maximum intercuspation, was measured at different sites by means of a Gutowski gauge. The tooth positions on the dentures varied widely, e.g. the horizontal distances between the incisive papilla and the maxillary incisors was 7.1 +/- 2.3 (3-14) mm. The vertical dimension of occlusion, which is most important in the jaw registration, varied equally with an anterior inter-alveolar distance between 12 and 33 (20.4 +/- 4.0) mm. Arbitrary moulding of the tooth position-analogue plastic rims does not seems to be an ideal method of pre-shaping functional impression trays, because the individual anatomical variation is considerable. Alternatively, the horizontal and vertical tooth positions of functionally and aesthetically pleasing dentures should be measured to pre-shape the rims of functional impression trays in the maxillary and the mandibular jaw. Such trays are a valuable tool for functional impressions and an immediate preliminary jaw registration in the fabrication of new complete dentures. This method allows a first try-in of the full set-up in the third clinical visit without loosing precision.

Adult↗
PubMed1980

The posterior palatal seal. A review.

The posterior palatal seal area is described and its anatomical borders are defined. The methods used to achieve a seal are (1) scraping the cast, (2) a selective loading impression technique, and (3) a physiological impression technique. Each method is described and its problems are discussed. It is believed by the authors that the physiological impression technique using wax requires the least amount of skill and experience to master competently.

Dental Impression Materials↗
PubMed2002

A comparison of stainless steel hand and rotary nickel-titanium instrumentation using a silicone impression technique.

BACKGROUND: Root canal preparation using rotary nickel-titanium instruments has been reported to be superior to hand instrumentation in terms of root canal shape, centring and frequency of procedural errors. The purpose of this study was to evaluate canal preparations using a sequential silicone impression technique to assess root canal morphology. METHODS: Pre-operative canal impressions were obtained from 24 extracted single-rooted premolars. Canals were randomly assigned to be firstly, instrumented with stainless steel K-type files or rotary nickel-titanium instruments (Profile), then further apically enlarged with rotary nickel-titanium instruments (Profile or Lightspeed). Post instrumentation impressions were taken and digitally photographed in a bucco-lingual and mesio-distal orientation at low-power magnification. Images were evaluated for procedural defects, changes in canal curvature, canal enlargement and canal rounding at 1, 3 and 7mm from the working length. RESULTS: Silicone impressions could accurately reproduce the detailed root canal morphology of single-canal premolars. Repeated impressions of each canal using a standardized procedure allowed a detailed comparison of instrumentation techniques at various stages. Hand instrumentation incurred more errors than rotary nickel-titanium instrumentation (Profile). Further apical enlargement using Lightspeed instruments incurred fewer errors than with Profile instruments. Differences among techniques were highly significant (p<0.005). All techniques resulted in slight canal straightening, as well as rounder and enlarged canals particularly in the apical third. CONCLUSIONS: Rotary nickel-titanium instrumentation, especially Lightspeed, may produce better canal shape by reducing procedural errors.

Analysis of Variance↗
PubMed2005

A clinical study comparing marginal and occlusal accuracy of crowns fabricated from double-arch and complete-arch impressions.

BACKGROUND: The double-arch impression technique is widely used in the provision of laboratory fabricated restorations. However, there is little clinical evidence to support or refute its use. The aim of this prospective clinical study was to evaluate the occlusion and marginal fit of posterior full crowns made from double-arch impressions, and to compare these to control crowns fabricated from conventional complete-arch impressions. METHODS: Ten patients requiring single posterior ceramo-metal full crowns had both double-arch and complete-arch impressions taken of the prepared tooth. Two crowns were fabricated for each tooth, using the casts made from both impression methods. Both crowns were tried in and the occlusion and margins evaluated. The results were composed using nonparametric statistical analysis with the probability level for significance at alpha=0.05. RESULTS: The crowns fabricated from the double-arch impression were found to be more accurate in closure to the intercuspal position and had fewer interferences in lateral excursions. There were no significant differences between the two crown groups regarding protrusive interferences and margin quality. CONCLUSIONS: Crowns fabricated from the double-arch impressions were equivalent in marginal accuracy and superior occlusally to crowns fabricated from the complete-arch impressions.

Crowns↗