An extended method for separating and quantitating molecular species of phospholipids.

An improved and extended method for separating and quantitating molecular species of four phospholipid classes is presented. Crude lipid extract is first separated into phospholipid classes on a silica column. Each phospholipid class is then separated into molecular species without derivatization using high-performance liquid chromatography on columns packed with octadecyl silica. Quantitation of individual species is achieved by measuring absorbance at 205 nm. Factors for converting absorbancies to mol fractions have been determined. Quantitation by absorbance at 205 nm agrees well with quantitation by gas chromatography which is preferred to quantitation by phosphate analysis. One hundred phospholipid species have been identified. A table of relative retention times of molecular species is provided. Examples of quantitative analyses of species composition are presented.

The vertical dimensional change resulting from polishing or glazing porcelain.

Studies have shown that polishing porcelain can produce a smooth surface similar to that resulting from a natural glaze. It has been reported that glazing porcelain causes changes in the occlusal vertical dimension. This study evaluated the changes in vertical dimension after natural glazing and polishing procedures. Twenty uniform-size tricuspid porcelain-fused-to-metal crowns were constructed on a mandibular typodont tooth. A inch steel ball was cradled between the three cusps, and the occlusal vertical dimension was measured from the top of the steel ball to the base of the castings. Contact areas were marked and lightly removed. Ten crowns received natural glazing and the remaining 10 were polished with a Shofu polishing kit. Measurements of occlusal vertical dimension were repeated. All of the crowns showed a loss of occlusal vertical dimension. The mean loss for polished crowns was significantly higher than that recorded for the glazed crowns.

Effects of porcelain on occluding surfaces of restored teeth.

The potentially destructive nature of dental porcelain placed on the occluding surface of prosthodontic restorations is explored. Current restorative trends are addressed with presentation of multiple clinical examples. Emphasis is placed on working knowledge by the restorative dentist. First an indepth knowledge of physical properties of dental porcelains is a necessity. Comprehensive treatment planning that includes a total evaluation of the patient's occlusal function and dysfunction is critical. Finally, viable material and treatment options are presented along with methods to help control the effects of porcelain if its use is mandated. This article does not condemn or condone the use of porcelain on occluding surfaces, but graphically reveals its potentially destructive character and suggests possible options.

Correction of alveolar ridge deformities with titanium implants.

A technique for the correction of alveolar ridge defects with titanium implants has been described. Custom cast titanium implants enable the dentist to achieve precise, predictable, stable ridge augmentation previously unavailable with other techniques and materials. The extension of this technique for the correction of more complex alveolar defects is logical.

Parental pressure, self-esteem and adolescent reported deviance: bending the twig too far.

Questionnaire responses from upper-status junior and senior high school students show the importance of perceived parental pressure in understanding adolescent self-esteem and deviant behavior. Adolescents who feel unduly pressured to achieve and succeed in school also are likely to have low self-esteem, to report deviant activity, and to feel they are incapable of reaching the goals set for them by their families.