Wetting effects of surface treatments on inlay wax-investment combinations

Gypsum-bonded and phosphate-bonded investments were applied to wax surfaces which were untreated, treated by buffing with cotton moistened with a die lubricant containing organic solvent, or treatment with a wax pattern cleaner. Contact angles between the investment material and wax surfaces were measured and compared. The treatment of a wax pattern with a surface tension reducing agent significantly increases the degree of wetting by both gypsum- and phosphate-bonded investments.     

Influence of preparation features on retention and resistance. Part II: three-quarter crowns

Four three-quarter crown variations were tested for retention and resistance and compared with results of a previous study.¹⁵ Preparations with boxes or four grooves are the most retentive of the three-quarter crown designs used in the study. Lingual placement of proximal grooves enhanced the retention. Three-quarter crowns with V-shaped grooves are the least resistant of the preparation designs with retention/resistance features.     

Articulator selection for restorative dentistry

There are many types of articulators that can be used for making fixed restorations. While unquestionably the most accurate, the fully adjustable instrument is not feasible or necessary for many forms of simple occlusal treatment.The effects of tooth-hinge axis radius, intercondylar distance, and condylar inclination on occlusal morphology have been discussed. Guidelines have been proposed for matching the type of articulator with the extent of treatment anticipated. The use of small, nonadjustable hinge articulators is not recommended.     

Preparation design and margin distortion in porcelain-fused-to-metal restorations

The relationship between preparation finish line configurations and marginal stability of porcelain-fused-to-metal restorations during the firing cycle was studied. Four labial finish lines presently in use were examined. The shoulder finish lines, with and without a bevel, were found to produce significantly less distortion in labial margins of porcelain-fused-to-metal restorations than do chamfer finish lines with and without a bevel.