This paper describes the rationale behind the need for xenotransplantation and the physiological and immunological barriers associated with xenografting from pig to man. The scientific strategies developed for overcoming the immunological barriers associated with hyperacute rejection are described in detail as is the technology for producing transgenic pigs. Data on perfusion studies of transgenic pig hearts with human blood demonstrates the validity of this scientific approach.

Animals↗

PubMed1996

Tartar control: assessment of patient benefits and professional scaling advantages.

Explore the source record for details and available documents.

Dental Calculus↗

PubMed1996

Instruments and methods for the quantitative measurement of factors affecting hygienist/dentist efforts during scaling and root planing of the teeth.

Manual calculus debridement through scaling accounts for a significant proportion of hygienist efforts in dental and periodontal practices. Despite this, little is quantitatively known concerning the effects of instruments, technique and treatments on debridement (scaling) efficiency or efficacy. The total work effort expended by therapists in calculus debridement results from the sum of the efforts associated with each scaling stroke. Each scaling stroke, in turn, is affected by a variety of physical forces, including those in the control of the therapist and those intrinsic to the calculus substrate. The development of procedures and treatments to facilitate easier calculus removal requires consideration of the physical and technique-related factors which contribute to hygienist effort. Instruments have recently been developed which can quantitatively measure force dynamics associated with scaling procedures, including both therapist-applied forces and forces developed due to the extreme hardness and tenacity of supra- and subgingival calculus deposits. The scaling instrument developed to quantitatively record developed forces in scaling, the Quanticalc, can be used for the assessment of techniques and treatments which can soften calculus, facilitating easier debridement. The device can also be used to instruct therapists on factors contributing to surface roughness and tactile response to these factors. The scaling instrument developed to quantitatively measure therapist applied forces in scaling, the Zappa device, can be used for assessment of techniques which can increase the efficiency of calculus removal with minimal damage to sound root substance. In this paper, the force dynamics associated with manual scaling procedures of dental professionals are defined. These force dynamics account for the total work expended by hygienists and other professionals in the important task of calculus removal. Using this as a foundation, the design, use, calibration and clinical applications of these newly developed scaling-force measurement systems are described.

Algorithms↗

PubMed1996

Crest Tartar Control benefits assessed by Quanticalc: clinical method and three-month results.

In this paper, a method is described for applying the Quanticalc (QC) dental scaler to the clinical assessment of tartar control dentifrice effects on supragingival calculus formation and therapist efforts required in subsequent calculus debridement. In a 3-month, randomized cross-over study, subjects using Crest Tartar Control were observed to form 25% less calculus than they formed in a similar period using Crest Regular non-tartar control dentifrice as placebo. QC measurements likewise revealed 25% savings in the developed force used to scale the anterior lingual surfaces, coupled with a 27% reduction in the number of strokes required to clean these surfaces free of supragingival calculus in subjects using tartar control dentifrice. The quantitative savings in professional effort amounted to 3 kg (developed forces saved) per subject using tartar control dentifrice. White subjects using placebo dentifrice for 3 months developed less calculus than shown at baseline (29% less calculus), this was not complemented by decreases in total force and strokes used in cleaning. This supports the hypothesis that the surface area coverage of calculus (e.g., the planimetric "area" of supragingival calculus on the tooth) does not contribute alone to the amount of effort as forces and strokes required in subsequent debridement. These results demonstrate that: 1) the QC dental scaler can be effectively used in the clinical assessment of scaling forces/efforts associated with supragingival calculus debridement; and 2) a tartar control dentifrice containing soluble pyrophosphate is clinically effective in reducing both the surface coverage of calculus and the therapist effort required in subsequent calculus debridement.

Adult↗

PubMed1996

Quanticalc assessment of the clinical scaling benefits provided by pyrophosphate dentifrices with and without triclosan.

The Quanticalc (QC) dental scaler permits a quantitative assessment of the work used by professionals in calculus removal through the measurement of force dynamics and scaling strokes applied in calculus debridement. The purpose of this study was to use the QC to compare the clinical effects of two 5% pyrophosphate dentifrices on dental calculus in subjects following six-months' product use. Three-hundred forty-six subjects participated in a six-month, double-blind tartar control clinical trial involving traditional Volpe-Manhold Index (VMI) evaluations. Following the six-month VMI examinations, the subjects had a QC prophylaxis (scaling force measurements). The three dentifrice treatment groups included a control dentifrice (NaF only, Crest); NaF dentifrice containing 5.0% pyrophosphate (Crest Tartar Control); and NaF dentifrice containing 5.0% pyrophosphate plus 0.28% triclosan (antimicrobial). Subjects were balanced by baseline (pretest) VMI scores at the start of the trial. QC examinations revealed statistically significant reductions in total force and stroke number used by the therapist to scale the six anterior VMI teeth for subjects using the pyrophosphate tartar control dentifrices as compared to control dentifrice. The reduction in scaling effort amounted to almost 3 kg per scaling for subjects. QC results paralleled VMI reductions of calculus on the teeth and demonstrated that the use of 5% pyrophosphate dentifrices, with or without triclosan antimicrobial, results in significant reductions in the total (developed) force and strokes required by therapists in regular calculus debridement at a six-month interval. The clinical benefits of tartar control toothpastes may not only include reductions in cosmetically objectionable supragingival calculus, but in reducing professional effort in calculus debridement during regular prophylaxis.

Analysis of Variance↗

PubMed1996

Effects of a scaling gel on forces developed in debridement of supragingival calculus determined by means of a transducer-modified dental scaler: the Quanticalc.

The efficacy of a calculus scaling gel, SofScale (Dentsply, York, PA), has been examined in two protocols by the measurement of scaling forces developed in supragingival calculus debridement from the anterior dentition using hand scaling with a transducer-modified dental scaler, the Quanticalc. In one protocol, the effects of the scaling gel were compared to a placebo gel composed of conventional toothpaste in a double-blind, split-mouth design. In another protocol, the effects of the scaling gel were determined in comparison to non-treated calculus. Results demonstrated that the scaling gel had no apparent effects on the physical forces (work) involved in calculus removal. These results suggest that the application of the scaling gel provides no quantitative benefits in facilitating calculus debridement during manual tooth scaling.

Analysis of Variance↗