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Biomedical subjects

N G Schaaf

Publications and source records attributed to N G Schaaf.

At least 19 recordsLinked to original sources
PubMed1992

Trends in prosthodontic treatment of cleft palate patients at one institution: a twenty-one year review.

This 21-year retrospective study evaluated the trends observed in the prosthodontic treatment of 269 patients. The patients were divided into three groups. The speech aid group consisted of 203 patients and showed a significant decrease in numbers over time. The maxillary obturator group consisted of 24 patients and did not show a significant change. The infant feeding prosthesis group consisted of 42 patients and showed a significant increase in numbers. Possible reasons for the trends observed are discussed.

Adolescent↗
PubMed1992

Visualization and initial characterization of the titanium boundary of the bone-implant interface of osseointegrated implants.

A simple procedure has allowed consistent visualization of the titanium boundary of the bone-implant interface of osseointegrated titanium implants at the electron microscope level. This was accomplished by embedding the intact bone-implant specimen block with low-viscosity resin prior to removal of the device in preparation for sectioning. The titanium boundary consisted of either a thin, compact amorphous electron dense layer, a broad layer of dense amorphous granules, or both. This material was removed by decalcification in formic acid (prior to embedding) and did not diffract electrons (ie, was noncrystalline). Scanning-transmission electron microscopy-EDX analysis indicated the presence of titanium, calcium, and phosphorus in the electron dense material. Field emission scanning electron microscopy-EDX dot-mapping analysis confirmed the presence of these elements and mapped them to the same locations at the implant-interface boundary.

Animals↗
PubMed1991

Microscopic observations of the bone/implant interface of surface-treated titanium implants.

Light microscopy, and transmission and scanning electron microscopy were used to evaluate osseointegration of extraoral titanium implant surfaces treated by either autoclaving, exposure to ultraviolet light (UV), or radiofrequency glow discharge (RFGD). Ultraviolet and RFGD-treated implants showed faster healing in the initial 5-week to 3-month period. By 6 months of healing, no structural differences were found at the bone/implant interface among the different treatments. It was concluded that UV or RFGD surface treatment of titanium implants may shorten the time interval between placement and loading.

Animals↗
PubMed1990

Dynamic ultraviolet sterilization of different implant types.

This paper investigates the use of the dynamic ultraviolet sterilization process with various dental implants, stainless steel orthopedic cortical bone screws, and polysulfone polymer healing caps. These biomaterials were inoculated with the spores of Bacillus subtilis and Bacillus stearothermophilus. They were then exposed to dynamic ultraviolet radiation in the chamber of a BUD Ultraviolet Device. Samples were incubated in trypticase soy broth at 37 degrees C and 56 degrees C, and they were subcultured onto an enriched agar medium. Results indicate that 16 seconds of dynamic ultraviolet radiation is effective in sterilizing these materials. This is significantly less time than other sterilization techniques presently used.

Bacillus subtilis↗
PubMed1989

Comparison of weight reduction in different designs of solid and hollow obturator prostheses.

Seven types of the partially edentulous maxillectomy arches based on Aramany's classification were designed to evaluate the weight reduction of hollow obturator prostheses. Six obturator prostheses were made for each type of maxillary defect, three of the solid type and three of the hollow type. The weight of each of the 42 obturator prostheses was measured and all of the data were collected and statistically analyzed. The results showed that the hollow obturator prostheses had significantly increased weight reduction, from 6.55% to 33.06% depending on the size of the defect.

Maxilla↗
PubMed1989

Effects of pretreatment sterilization and cleaning methods on materials properties and osseoinductivity of a threaded implant.

A new endosseous titanium implant has been designed to replace skin adhesives as a method of retention of maxillofacial prostheses. The effects of various methods of preimplantation preparation on surface characteristics of the implant were analyzed with electron spectroscopy for chemical analysis. Having undergone one of several pretreatment protocols, fixtures were implanted in the crania of Yucatan miniature hairless swine. Both argon radiofrequency glow discharge and ultraviolet chamber treated implants were associated with the rapid ingrowth and maturation of new bone around the fixture. Conventional steam sterilization was associated with a paucity of neo-osteogenesis accompanied by the production of thick collagen slings at the interface. Apparently, the bulk material, fixture design, and method of surface preparation all contribute to the ultimate clinical fate of an implant.

Animals↗
PubMed1989

Dynamic sterilization of titanium implants with ultraviolet light.

All implantable devices must be sterile. However, autoclaves produce poor surface properties that jeopardize the integration process. The application of a modified ultraviolet light source has proven to enhance bioreactivity by controlling surface properties, but it lacks validation of its sterilization capabilities. Forty-eight titanium implants were contaminated with spores of the biological indicator Bacillus stearothermophilus and subjected to "dynamic sterilization" by ultraviolet light. Forty-seven of the implants were successfully sterilized, as indicated by not producing turbidity in a suitable growth medium. This sterilization technique only requires a 20-second exposure to achieve sterility.

Dental Implantation, Endosseous↗
PubMed1978

An evaluation of facial prostheses.

A survey was conducted to evaluate patient reactions to facial prostheses that were provided to 143 patients in the past 7 years at Roswell Park Memorial Institute. Of the 76 patients who responded, 38 patients were wearing their prostheses and 38 patients were not wearing their prostheses. Reasons cited by the patients for not using their prosthesis included lack of retention, additional surgery, discomfort, and irritation. Most of the prostheses were prepared in silicone rubber with color characterization accomplished by the tattooing method. More than 69% of the prostheses were remade within a year because of rapid changes in the defect, prosthesis material, or prosthesis color. The study revealed the need for improvement in materials, adhesive techniques, and the psychological orientation of the patient. This project was conducted at a teaching and research institute. No fees for the patients were required. Therefore our data might differ from that collected from a private practice or clinic.

Adult↗
PubMed1977

Obturators on complete dentures.

A philosophy and technique for the preparation of removable silicone rubber obturators on complete dentures have been presented. Either of two methods for construction is used depending on whether the defect is large or small. Advantages of the silicone rubber obturator-denture combination were elaborated.

Denture Design↗
PubMed1976

Oral reconstruction for edentulous patients after partial mandibulectomies.

The prosthodontic reconstruction of the patient who has had a partial mandibulectomy is a formidable challenge. A realistic view of the positive and negative factors must be maintained so that unrealistic promises are not made by the prosthodontist and no unfulfilled hopes are left for the patient. Because of the instability of the mandibular denture, the patient's relaxed central position is used as the jaw relationship for setting posterior teeth with flat occlusal surfaces to allow for lateral freedom of mandibular movements.

Denture, Complete↗