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Biomedical subjects

J F Wolfaardt

Publications and source records attributed to J F Wolfaardt.

At least 19 recordsLinked to original sources
PubMed2000

Quantifying the adherence of fibroblasts to titanium and its enhancement by substrate-attached material.

Normal human skin fibroblasts were cultured on tissue culture polystyrene and on commercially pure titanium. In addition, substrate-attached material that remained on the surfaces after detachment of fibroblasts with a chelating agent was examined. The force required to detach 50% of the fibroblasts from each substrate was assessed by centrifugation. The results showed a time-dependent decrease in the force required to detach fibroblasts from titanium not seen on tissue culture polystyrene. Nearly all cells detached from the titanium surfaces at 7.85 x 10(x3) dynes/cell after 3 or 5 days in culture, whereas few cells detached from tissue culture polystyrene. Cells freshly seeded onto titanium substrates that had been coated with substrate-attached material by prior culture of fibroblasts for 3 or 5 days showed an approximately sixfold increased adherence. The results of immunofluorescence staining for fibronectin and its receptor suggest that the nature of the interaction between this extracellular matrix ligand and the substrate may be important in determining cellular stiffness at the cell-extracellular matrix interface.

Biocompatible Materials↗
PubMed1999

The influence of dentures on nasalance values in speech.

OBJECTIVE: The purpose of this study was to investigate the effects of maxillary dentures on nasalance values in normal elderly individuals. DESIGN: A three-factor within-subjects experimental design was employed to analyze the nasalance scores obtained. PARTICIPANTS: Twenty English-speaking women aged 61 to 81 years, who wore complete maxillary dentures, participated in the study. INTERVENTION: A Nasometer was used to collect nasalance data. Participants read three standard passages aloud, three times each, in two conditions: with and without their maxillary dentures. RESULTS: Results revealed that nasalance values were significantly lower with the maxillary dentures removed (p<.01), although the difference in nasalance between the two denture conditions averaged no more than 2%. Nasalance scores obtained both with and without maxillary dentures fell within one standard deviation of the mean for a reference group of comparably aged English-speaking women. CONCLUSIONS: The results suggest that the existing collection of normal reference data for nasalance may be safely used for elderly individuals regardless of their status with respect to natural or prosthetic maxillary dentition.

Aged↗
PubMed1996

An impression and cast construction technique for implant-retained auricular prostheses.

Implant-retained auricular prostheses present a challenge with regard to the esthetic placement of the margins of the prosthesis. A technique for the impression and master cast fabrication to produce an implant-retained auricular prosthesis is described. This technique allows control of the esthetic margin, fabrication of a durable master cast with planned blockout, and inclusion of a replica of the retentive bar, which allows processing duplicate prostheses without returning the retentive bar to the mold.

Ear, External↗
PubMed1996

Craniofacial osseointegration: technique for bar and acrylic resin substructure construction for auricular prostheses.

Retention of auricular prostheses with adhesives is frequently problematic. Craniofacial osseointegrated implants have become an accepted biotechnique used in auricular reconstruction. This article describes a procedure for bar and acrylic resin substructure construction that allows for the incorporation of desired features. The most common means of retaining auricular prostheses is with bar and clip systems. For auricular prostheses, two implants are placed with the bar designed to minimize torquing on the implants and to facilitate hygiene. Additionally, the bar should not have to be removed from the patient when new prostheses are to be constructed. The procedure provides for a more biomechanically effective bar construction and efficient means of constructing replicate acrylic resin substructures.

Acrylic Resins↗
PubMed1996

Autogenous soft-tissue procedures and osseointegrated alloplastic reconstruction: their role in the treatment of complex craniofacial defects.

Between 1990 and 1994, twenty-seven patients with extraoral craniofacial defects were treated at the Craniofacial Osseointegration and Maxillofacial Prosthetic Rehabilitation Unit in Edmonton. Fourteen patients required management by a combination of alloplastic and autogenous techniques to optimize their reconstructive result. Autogenous soft-tissue procedures were performed almost twice as often in patients whose deformity was the result of trauma. Autogenous soft-tissue procedures included soft-tissue expansion, static facial slings, free and pedicled vascularized bone grafts, eyebrow reconstruction, brow lifts, and scar revisions. These reconstructive procedures are illustrated in three cases.

Adult↗
PubMed1996

Removable partial denture design in Alberta dental practices.

Studies published in the dental literature have found, all too frequently, that dentists do not pay adequate attention to the design of cast removable partial denture frameworks. This study investigated removable partial denture design in Alberta dental practices. The authors considered various issues related to surveying, partial denture design, and provider education, as well as the possible collaboration of clinical dentistry with denturism in removable partial denture treatment. Although the study found that a significant proportion of Alberta's dentists get involved in designing the cast framework, relatively few undertake surveying. Instead, surveying tends to be deferred to dental technicians. As was the case in other studies, no clear reason for this trend emerged, and it appeared to be unrelated to remuneration or time utilization issues. Responding dentists perceived that their undergraduate education was adequate for providing removable partial denture care. The study also identified a need for small, hands-on continuing education courses. About half of the respondents indicated that it is appropriate for dentists to collaborate with denturists on complete denture care. However, very few respondents considered it appropriate to refer to, or collaborate with, denturists in removable partial denture care.

Alberta↗
PubMed1994

Ribosomal RNA sequence phylogeny is not congruent with ascospore morphology among species in Ceratocystis sensu stricto.

The genus Ceratocystis sensu stricto includes important fungal pathogens of woody and herbaceous plants. This genus is distinguished from species in Ceratocystis sensu lato by the presence of Chalara anamorphs. Ascospore shape has been used extensively in delineating Ceratocystis taxa, which show a large variety of ascospore shapes. Sequence analysis of one region of he 18S ribosomal RNA subunit and two regions of the 28S ribosomal RNA subunit showed that there was a majority of multiple substitutions at nucleotide sites and that there was a low transition/transversion ratio, T = 0.72. Both of these results suggest that these are well established, old species. Ascospore morphology, for the most part, was not congruent with the molecular phylogeny, and the use of morphological characters may be misleading in the taxonomy of these species.

Ascomycota↗
PubMed1994

Osseointegrated alloplastic versus autogenous ear reconstruction: criteria for treatment selection.

Fifty-five patients with major ear deformities were reconstructed during the period 1982-1993 with autogenous tissue. Fourteen patients were reconstructed with osseointegrated auricular prostheses during the period 1989-1993. Both procedures were done at the same institution by the same surgeon. The advantages and disadvantages of each approach were considered, and our criteria for treatment selection were developed. Our main indications for autogenous reconstruction include classical microtia, relatively normal lower one-third of the ear, patient preference, and less compliant patients. The main indications for osseointegrated alloplastic reconstruction include following major cancer extirpation, poor local tissue, absence of the lower half of the ear, salvage following unsuccessful autogenous reconstruction, and poor operative risks. Because of their success, osseointegrated auricular reconstructions should be added to the armamentarium of the reconstructive surgeon.

Adolescent↗
PubMed1994

Craniofacial osseointegration.

Craniofacial osseointegration has been hailed as the most significant advance in maxillofacial prosthetic restoration over 25 years. It provides a particularly unfortunate group of patients, who previously may have had few treatment options, with new reconstructive opportunities. This paper outlines the surgical and prosthetic techniques of craniofacial osseointegration. Treatment outcomes in terms of individual implant success rates are described and the role of hyperbaric oxygen is considered. The need for future avenues of development are also discussed. Craniofacial implants have become an integral part of the treatment options available for head and neck reconstruction. It is important that this care is provided within a multidisciplinary clinical-research environment.

Ear↗
PubMed1993

A comparison of various removable partial denture clasp materials and fabrication procedure for placing clasps on canine and premolar teeth.

There is no established protocol for selection among the different retentive material-attachment combinations for clasps other than tradition or laboratory preference. Various wrought-wire, cast-metal, and thermoplastic materials were subjected to several fabrication procedures and tested in a custom-designed force displacement apparatus. The wrought wires included ADA Spec. No. 7 type I and type II alloys and other precious and nonprecious alloys. A graphic means was devised to allow the rational selection of wrought-wire clasp-arm combinations for placing clasps on canine and premolar teeth. Guidelines for using straight wire data for curved wire applications are indicated.

Acrylic Resins↗
PubMed1993

Effects of disinfecting irreversible hydrocolloid impressions on the resultant gypsum casts: Part I--Surface quality.

This study evaluated the effects of disinfection time (10, 30, and 60 minutes) on the surface quality of stone casts poured against an alginate impression material (Jeltrate). Five antimicrobial agents were tested: Sporicidin spray, sodium hypochlorite, and iodophor for spray; and Sporicidin cold sterilization solution and Cidexplus glutaraldehyde solution for immersion. Impressions, flushed with water and stored for 0, 10, 30, and 60 minutes before pouring, served as untreated controls. On completion of the disinfection treatments, the impressions were rinsed and poured in Velmix stone. The effects on cast surface were evaluated under a stereomicroscope by three experienced raters. A 1-to-4 scoring system was developed to rate the surface quality in terms of smoothness and detail reproduction. Both immersion disinfectants proved to be unacceptable for treating alginate impressions. The mean scores of other disinfectant-time combinations were compared with the use of the Tukey-Kramer method with a 95% confidence interval. The results indicated that treatment time had statistically significant effects on the quality of cast surface in Sporicidin spray, sodium hypochlorite, and untreated control groups but not in the iodophor spray group.

Analysis of Variance↗
PubMed1993

An appliance based approach to the management of palatopharyngeal incompetency: a clinical pilot project.

The palatal lift appliance has been described in the dental literature for more than 30 years, yet its efficacy remains controversial in the management of palatopharyngeal incompetency during speech. A pilot project was undertaken to develop a clinical research protocol. In the pilot project, 32 patients had palatopharyngeal incompetency managed with a palatal lift appliance. The results of the treatment were that 21 of the 32 patients experienced reduction programs but, of these, seven still required surgery. Before firm conclusions on the use of the palatal lift appliance can be made, objective, measurable assessment of speech through well-designed clinical protocols is required.

Acrylic Resins↗
PubMed1993

Effects of disinfecting irreversible hydrocolloid impressions on the resultant gypsum casts: Part III--Dimensional changes.

This study evaluated the effect of disinfection time (10, 30 and 60 minutes) on the dimensional changes of stone casts poured against an irreversible hydrocolloid impression material (Jeltrate). Impressions were made of a stainless steel analog of a maxillary arch. The impressions were sprayed with bleach, iodophor, phenol, and water and were stored for designated times before poured in a type IV stone (Vel-mix). The arch width, length, and depth of the vault of the resultant casts were measured by use of a contact measuring device (MicroVal) capable of measuring to 0.0001 mm. Data were analyzed with two-way analysis of variance at the 95% confidence level. Results indicated that disinfection treatment of alginate impressions with surface disinfectants did not cause significant dimensional changes in the resultant stone casts from statistical and clinical points of view.

Analysis of Variance↗
PubMed1993

Craniofacial osseointegration: the Canadian experience.

A survey was undertaken to determine the number of centers in Canada with an active involvement in extraoral osseointegration. It was found that six centers had placed 222 implants in 91 patients in Canada. The individual implant success rates for the Canadian experience were compared with the published Swedish and United States' experience. The Canadian experience is combined with the Swedish and United States' experience to provide retrospective multinational multicenter data. The data given should be viewed as providing trends only and not as definitive expectations of predictable success rates. The success rates are considered likely to change with time as the number of patients treated increases and the duration of follow-up is extended. The mastoid region in nonradiated patients is considered to provide a high degree of predictable individual implant success. The success rates in radiated patients yield far lower success rates, which vary with anatomic location. The criteria for success in using craniofacial implants need to be defined and should reflect the differences between extraoral and intraoral implants.

Canada↗
PubMed1992

Biocompatibility testing of a silicone maxillofacial prosthetic elastomer: soft tissue study in primates.

Little information exists on the biocompatibility of maxillofacial prosthetic materials. Cosmesil material is a purpose-designed facial prosthetic elastomer that has an established clinical profile in humans but results of biocompatibility testing have not been published. Cosmesil, acrylic resin (positive control), black surgical gutta-percha (negative control), and Silastic 382 material (Dow Corning, Midland, Mich.) (reference control) were processed as custom-designed implants. The implants were inserted into five chacma baboons for a 12-week period in intraosseous, subperiosteal, submucosal, and intramuscular sites. The histologic assessment was based on a modified form of the FDI-ISO Technical Report 7405 for subcutaneous implants. An evaluation was made of capsule formation and inflammatory response. The statistical analysis involved a three-way ANOVA and a Tukey-Kramer Student range test. The critical level of statistical significance chosen was p less than 0.05. The study found that gutta-percha provoked a statistically significantly thicker capsule and a severe inflammatory response. Acrylic resin, Cosmesil material, and Silastic 382 material produced capsule formations and an inflammatory response that did not differ significantly. Cosmesil material is not manufactured as an implant material, but from the present findings it is considered acceptably biocompatible for its intended use where there may be contact with internal tissue spaces that are contiguous to external surfaces.

Acrylic Resins↗