Biomedical subjects
B R Gillings
Publications and source records attributed to B R Gillings.
Dye-assisted diode laser ablation of carious enamel and dentine.
Carious dentine and enamel from extracted human teeth were ablated using a semiconductor diode laser in conjunction with an applied dye, indocyanine green. This technique offers selective ablation with minimal risk of thermal damage to surrounding dental tissues because uptake of the dye and its irradiation by the laser together control the ablation. In this study, various laser powers and dye concentrations were used to ablate previously extracted human teeth with moderate caries. The mass of material ablated and the temperature rise in the pulp and at the surface were recorded, and the ablated surface was examined by microscopy. The ablation was efficient and the rise in the pulp temperature slight. Ablation efficiency and surface temperature were both found to increase with laser irradiance and with dye concentration. No surface cracks or fissures were seen in electron microscope examination and the hardness of the laser-treated surfaces was comparable to that of healthy tissue. The dye-assisted laser ablation technique offers considerable potential for clinical caries removal and dentine, enamel and pulp sterilization, whilst leaving healthy tissue intact. The diode laser can deliver its energy via simple optical fibre and is cheaper and much smaller than the conventional high power lasers used in other studies.
Lead exchange in teeth and bone--a pilot study using stable lead isotopes.
Stable lead isotopes and lead concentrations were measured in the enamel and dentine of permanent (n = 37) and deciduous teeth (n = 14) from 47 European immigrants to Australia to determine whether lead exchange occurs in teeth and how it relates to lead exchange in bone. Enamel exhibits no exchange of its European-origin lead with lead from the Australian environment. In contrast, dentine lead exchanges with Australian lead to the extent of approximately 1% per year. In one subject, trabecular bone from the tooth socket exchanged almost all its European lead with Australian lead over a a 15-year period (turnover of approximately 6% per year), similar to the approximately 8% per year proposed for lead turnover in trabecular bone. The repository characteristics of intact circumpulpal dentine were investigated by analyses of four sets of contiguous slices from six teeth: 1) a set consisting of slices with intact circumpulpal dentine and cementum; 2) a set in which these areas were removed; 3) another set consisting of slices with intact circumpulpal dentine and cementum; and 4) a set without cementum. These analyses show relatively small differences in isotopic composition between contiguous slices except that circumpulpal dentine appears to be the dominant control on lead concentration. There is a significant correlation (R2 = 0.19, p = 0.01, n = 34) of dentine lead concentration and rate of exchange with residence time from the country of origin and Australian lead, but there is no such correlation with enamel lead concentration. Analyses of permanent and deciduous teeth of subjects from other countries who have resided in Australia for varying lengths of time should resolve some of the questions arising from this pilot study.
Stable lead isotopes in teeth as indicators of past domicile--a potential new tool in forensic science?
A pilot study using stable lead isotope analyses has shown that permanent and deciduous teeth from Eastern and Southern European subjects have completely different lead isotopic compositions to those of Australian subjects. There are statistically significant differences between groups of teeth from subjects from the former Soviet Union (CIS), the former Yugoslavia, United Kingdom, and Lebanon. The isotopic analyses confirm the stability of lead in enamel but suggest that there is exchange of European lead with Australian lead in dentine amounting to about 1% per year. The isotopic differences in, and exchange of, European lead and Australian lead offer an exciting and powerful tool for forensic identification.
Lasers--panacea or paradox?.
The first lasers were quite unsuitable for dental use, but the last 30 years have seen the development of a variety of lasers which allow dentists to cut soft tissue without bleeding, remove caries, cut cavities in teeth (usually without pain), cure composite resins rapidly, weld metals with precision, desensitize teeth, sterilize exposed pulps and tissue surfaces and treat skin lesions. Future research may explain why 'soft' lasers appear to promote healing and alleviate joint and muscle pain. There are now many published reports in refereed dental journals covering the various aspects of laser dentistry. Dentists interested in lasers, or who are considering purchasing one should read the relevant literature and consult their Association and colleagues before making a purchase.
Cleansing and surface modifying agents on implants: fixation and related aspects of aesthetics.
With the prognosis of dental implant replacement of missing teeth becoming better each year, practitioners are focusing their attention on the aesthetic aspects of implantology. However, improvement in aesthetics is only possible with the improvement in implant technology, surgical techniques and prosthodontic procedures. This study aimed at evaluating the effects of various physical and chemical agents on the implant surface; with the view of obtaining increased surface area and biocompatibility. The study found that the treatment of air-aluminum oxide blasted implants using a mixture of 30% HNO3-5% HF acids produced a surface which meets the consideration of aesthetics for implants placed in the anterior maxillary region.
The captive screw retained sectional denture.
Sectional dentures, where retention is gained, not by flexible metal arms engaging "desirable" undercuts, have occasionally been described in the dental literature. The captive screw retained sectional denture described here is an effective replacement for one or two missing teeth in selected patients. It consists of separate labial and lingual sections, which, when assembled, provide an aesthetic appearance, functional occlusion and excellent retention, with a minimum of abutment tooth preparation and at low cost. The two sections are connected by a captive screw, which allows the sections to be separated for denture insertion, but which is tightened to join the two sections. Portions of each section then engage tooth undercuts to provide retention. The screw is loosened and tightened by means of a torque-limiting screwdriver. These dentures have a high level of patient acceptability, and do not appear to promote dental caries or gingival irritation.
Magnet overdentures.
Magnets were first used for overdenture retention in 1977. A novelty then, they are now an accepted alternative to conventional attachments, and available commercially from a number of manufacturers. Nearly all of them use a "closed field" magnet configuration, which provides optimum retention and eliminates any possibility of magnetic field effects on tissues. Initial corrosion problems are now being eliminated by improved designs. Clinical experience has shown that overdentures preserve alveolar bone and that magnetic retention can be used effectively on tooth roots which would have a poor prognosis with conventional attachments. Magnets can also be used to retain overdentures against implants as an inexpensive alternative to conventional implant dentures.
Overdentures with magnetic attachments.
Magnets were used only occasionally for dental purposes several decades ago. Since the advent of rare earth magnet alloys, however, intraoral magnets are shaping the course of aesthetics and retention for both complete and removable partial overdentures. Their benefits include simplicity, low cost, self-adjustment, inherent stress breaking, automatic reseating after denture displacement, comparative freedom of lateral denture movement, a low potential for trauma to the retained roots, and elimination of the need for adjustment in service. The clinical procedures involved in their application do not require any special skills, and the options offered by the various manufacturers give the dentist a wide variety of choices in selecting an appropriate treatment plan. Clinical experience has shown that magnetic retention offers an economical alternative for teeth that would otherwise require expensive or extensive restorative treatment, and can be used as an effective and often superior replacement for failed bridgework. Finally, it is clear that overdenture treatment per se is a valuable option for the dentist, and the use of magnets expands this option to the retention of tooth roots that might otherwise be scheduled for extraction. The natural tooth root, even if periodontally involved, can serve as a useful aid in denture support and retention, and should be regarded as at least as good as, and in most cases superior to, an implant. It is also much less expensive.
Magnetic denture retention systems: inexpensive and efficient.
A magnetic retention system has been used in more than 6000 complete and partial overdentures, sectional dentures and implant overdentures, with excellent clinical results and patient acceptability. For the overdenture application, decoronated, root-treated teeth are fitted with preformed or cast magnetisable alloy root elements, or 'keepers'. Following conventional denture construction, paired cobalt/samarium magnets in a special configuration are cured into the denture base so that with the denture inserted, the magnets grip the root elements with a retentive force of approximately 300 g per root. The paired magnet arrangement eliminates any external magnetic field and doubles the available retention. Magnetic retention has few of the problems encountered with other retention devices. It offers simplicity, low cost, self-adjustment, inherent stress-breaking, automatic repositioning after denture displacement, comparative freedom of lateral denture movement, reduces trauma to retained roots and eliminates the need for adjustment in service. For the sectional denture application, undesirable undercuts on the abutment teeth are used to provide passive, positive retention. The separate buccal and lingual sections are joined together by parallel pins fitting into matching tubes, assembly being maintained by magnetic attraction between a retention element in one section and a keeper in the other. Insertion and removal are more difficult than with a conventional denture but soft tissue coverage is minimal. There are no visible retainer arms and food traps are eliminated. Abutment tooth preparation is negligible, the laboratory procedures simple, and the treatment inexpensive and reversible. A clinical trial of magnetic overdenture retention in conjunction with osseointegrated titanium implants is now in progress. After 21 months acceptable clinical results have been obtained. An improved implant with an alumina core and a sintered hydroxyapatite coating is at present undergoing animal trials. Chemical bonding at the bone/implant interface is anticipated.
Magnetic retention for overdentures. Part II.
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Magnetic retention for complete and partial overdentures. Part I.
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Recent developments in dental plaque disclosants.
The use of erythrosin and fluorescein for disclosing dental plaque in 81 children aged 11-14 years and in 17 young men is reported. Erythrosin stained all plaque. When fluroescein was used, plaque, whether mature or recently exposed to sugars was disclosed under ultra-violet light. In the children, the erythrosin stained approximately twice as extensively as fluorescein.
The use of closed circuit television in the teaching of dental technology.
A low cost, single-operator, four-camera, closed-circuit television system was developed to teach dental technology to large classes (120) of second and third year (pre-clinical) undergraduates. Its use permits demonstrations to be conducted, recorded and played back, with no electronic knowledge, little training, and a minimum of preparation and assistance. The field of view is from above the demonstration table, and is selected by pushing button in the size range, 30 cm x 20 cm down to 3cm x 2cm. The system has many advantages, few disadvantages, is reliable in operation, and is acceptable to students.
Letter: Jaw movements in young adult men during speech.
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Assessment of a preventive dentistry programme in private practice.
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Jaw movements in young adult men during speech.
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Jaw movements in young adult men during chewing.
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