Search PubMed⌕ Search

Biomedical subjects

J M McIntyre

Publications and source records attributed to J M McIntyre.

At least 19 recordsLinked to original sources
PubMed2006

The effect of silver fluoride and potassium iodide on the bond strength of auto cure glass ionomer cement to dentine.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to reduce the incidence of caries in primary dentitions. The clinical application of this material has been limited by staining associated with both teeth and restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. There is a lack of information as to how the addition of AgF followed by KI may affect the bond strength to dentine. The purpose of this study was to compare the bond strengths of auto cure glass ionomer cement to dentine surfaces that had been treated with AgF and KI and without treatment. METHODS: Ten recently extracted human third molars were embedded into methyl methacrylate resin and sliced to form a square block of exposed dentine surfaces. Each of the four surfaces were treated by one of the following procedures: (a) etching with 37 per cent phosphoric acid; (b) applying GC dentine conditioner; (c) etching, followed by application of AgF/KI then washing off the precipitate and air drying; and (d) etching, applying AgF/KI and air drying the reaction products on the surface. Fuji VII auto cure glass ionomer cement was bonded onto each sample and fracture tested. RESULTS: The dentine samples treated with AgF/KI followed by washing away the precipitate and air drying had bond strengths (2.83 MPa) not significantly different from samples that had been conditioned (2.40 MPa). Samples where the AgF/KI precipitate had been air dried onto the dentine surface had significantly lower bond strengths (1.49 MPa) than the washed samples. Samples that were etched had significantly lower bond strengths (1.91MPa) than the conditioned samples. CONCLUSIONS: This study found that the application of AgF/KI to etched dentine samples followed by washing off the precipitate, created bond strengths that were not significantly different to conditioned samples. Leaving the AgF/KI precipitate on the dentine surface significantly reduced the bond strength of auto cured glass ionomer cement to dentine. Washing away the reaction products and air drying is recommended as the clinical protocol for using AgF and KI on dentine surfaces prior to application of an auto cure glass ionomer cement.

Acid Etching, Dental↗
PubMed2006

Bond strengths between composite resin and auto cure glass ionomer cement using the co-cure technique.

BACKGROUND: The clinical technique for sandwich restorations prescribes etching initially set auto cure glass ionomer cement (GIC) prior to placing a layer of resin bond to develop a weak mechanical bond between composite resin and GIC. Co-curing a resin modified glass ionomer cement (RMGIC) bond and composite resin to GIC may create a chemical bond and improve the bond strengths between these two materials. METHODS: A total of 48 specimens were prepared, 12 in each of four categories. Capsulated GIC was placed into a mould and allowed to set for four minutes, etched for five seconds followed by placement of a resin bond and photo cured for five seconds over which a composite resin was puddled onto the resin bond and photo cured for 10 seconds. Capsulated GIC was placed into a mould and allowed to set for four minutes after which a sample of RMGIC (Riva LC) was prepared using twice the liquid powder ratio and painted over the surface of the set GIC using a micro brush. An increment of composite resin was added over the RMGIC and both materials were photo co-cured for 10 seconds. Capsulated GIC was placed into a mould and RMGIC (Riva LC) that had been prepared using twice the liquid powder was brushed over the GIC (prior to initial set) followed by the placement of a layer of composite resin and photo co-cured for 10 seconds. Capsulated GIC was placed into a mould and RMGIC (Fuji II LC) that had been prepared using twice the liquid powder was brushed over the GIC (prior to initial set) followed by the placement of a layer of composite resin and photo co-cured for 10 seconds. Shear testing of each of the samples was carried out and specimens were examined to determine the nature of the fracture. Selected samples were prepared for SEM investigation to observe the interfaces between the GIC and composite resin. RESULTS: There were significantly lower bond strengths (P < 0.05) amongst samples that had been etched and bonded (2.42MPa) compared to the other samples that had been co-cure bonded with RMGIC (6.48-7.05MPa). There were no significant differences amongst the bond strengths of the samples co-cure bonded with RMGIC. Specimens prepared by the 'etch and bond' technique failed adhesively and co-cured specimens failed cohesively within the GIC. SEM investigation showed chemical bonds between RMGIC bond and GIC and composite resin. CONCLUSIONS: The co-cured RMGIC bonding system eliminates several placement steps and produces a significantly stronger chemical bond between GIC and composite resin than the 'etch and bond' technique. RMGIC bond and composite resin may be co-cured to GIC either before or after initial set has occurred.

Acrylic Resins↗
PubMed2006

Ion uptake into demineralized dentine from glass ionomer cement following pretreatment with silver fluoride and potassium iodide.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to provide a pronounced antimicrobial action against caries. The clinical application of this material has been limited by the staining associated with both teeth and tooth coloured restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. The purpose of this study was to determine if a prior application of silver fluoride and potassium iodine to demineralized dentine affected the uptake of strontium and fluoride from a glass ionomer cement restoration. METHOD: Three cavities were prepared in each of five recently extracted human third molars. The cavities were demineralized and treated as follows. In each tooth, one cavity was left as a control, one cavity was restored with glass ionomer cement and one cavity was treated with 1.8M AgF and a saturated KI solution and then restored with glass ionomer cement. The penetration of the various elements into demineralized dentine was measured by their relative percentage weights using electron probe microanalysis (EPMA). RESULTS: Fluoride uptake was significantly higher in the AgF and KI treated samples compared to the other two samples and significantly higher in the glass ionomer restored sample compared to the control. The application of AgF and KI did not significantly interfere with the transfer of strontium from glass ionomer cement into dentine. Silver and iodine deposits were present in the demineralized dentine treated with AgF and KI. CONCLUSIONS: The application of AgF and KI onto dentine prior to the placement of glass ionomer cement did not significantly affect the strontium uptake into the subjacent demineralized dentine and the fluoride levels in this zone were significantly increased.

Anti-Infective Agents↗
PubMed2005

An in vitro model to measure the effect of a silver fluoride and potassium iodide treatment on the permeability of demineralized dentine to Streptococcus mutans.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been used to reduce the incidence of caries in primary dentitions but has been limited by the associated staining of both teeth and restorative materials. The application of potassium iodide (KI), following AgF prevents staining but its effects on the ability of AgF to reduce caries are not known. The aim of this study was to develop an in vitro model that would provide an indication of the permeability of demineralized dentine to Streptococcus mutans after treatment of the dentine with AgF followed by KI. METHODS: Forty dentine discs were bonded to the base of forty 5mL polycarbonate screw top vials (that had had their bases removed), filled with nutrient medium, sterilized and placed into a continuous culture of S. mutans. Samples were divided into four groups as follows: 10 samples of demineralized dentine as a control, 10 samples of demineralized dentine treated with AgF/KI, 10 samples of demineralized dentine treated with KI and 10 samples of demineralized dentine treated with AgF. After two weeks the optical density of the growth medium chambers was measured to determine bacterial penetration and growth. Cultures were plated out to determine migration through the discs by S. mutans. RESULTS: S. mutans migrated through all dentine discs. However, the samples treated with AgF and AgF/KI had significantly lower optical densities than the corresponding controls. The range of optical densities was least amongst demineralized samples treated with AgF/KI. CONCLUSIONS: Under the conditions of this study, treatment of demineralized dentine discs with AgF followed by KI allowed the penetration of S. mutans. Based on optical density measurements, the treatment resulted in significantly fewer microorganisms being present subjacent to the discs treated with AgF and KI than the control discs at the end of the experimental period.

Bacteriological Techniques↗
PubMed2005

The ability of 1.23% acidulated phosphate fluoride gel to inhibit simulated endogenous erosion in tooth roots.

BACKGROUND: Endogenous dental erosion is that produced by contact of gastric acids with tooth structure. It may affect exposed root cementum/dentine as well as coronal enamel, causing marked loss of mineral. The aim of this study was to determine whether 1.23 per cent acidulated phosphate fluoride gel, if applied to the surface cementum at certain intervals during an erosive acid challenge, could provide any protection against demineralization. MATERIALS AND METHODS: Roots of preserved extracted human teeth were painted with a water and acid resistant varnish, leaving two windows (3x1mm) of exposed dentine. These were placed in a solution containing 0.06MHCl and 2.2mMCaHPO4, which has been shown to simulate gastric acid when it meets the tooth surface. The roots were placed in the erosive solution unprotected (controls), or subject to APF application for four minutes prior to and every 10, 30 or 120 minutes during the erosive challenge. Roots were removed at either 6 or 12 hours, washed thoroughly and cut into 120microm thick sections. Depths of demineralization were measured using an optical graticule under polarized light microscopy. RESULTS: A high level of protection was provided when the roots were coated with APF gel every 10 or 30 minutes. CONCLUSIONS: APF gel will partially inhibit endogenous erosion of roots for up to 30 minutes if applied, for example, the night before a morning reflux episode. This should be considered along with other erosion control or reduction procedures for patients suffering from the effects of endogenous erosion.

Acidulated Phosphate Fluoride↗
PubMed2000

Studies of dental root surface caries. 1: Comparison of natural and artificial root caries lesions.

Qualitative polarized light microscopy and cross-sectional microhardness testing profiles were used to compare artificial root caries lesions with those naturally present in extracted human teeth. The artificial lesions were produced by immersion of roots with exposed windows in chemical buffers of acetate and lactate with no added enzymes or bacteria. The three buffer systems used produced lesions with the range of histological characteristics of natural lesions. These included a 'body' or 'surface' zone of the lesion when viewed in water, and a 'frontal' zone of reverse birefringence when viewed in quinoline. The 'frontal' zone was noted to first develop after three days of immersion in acetate buffer. Advanced natural lesions exhibited a wide, diffuse, advancing front, which was similar to that produced by 28-60 day lesions in acetate. Microhardness profiles of natural lesions could all be matched by one or more of the artificial lesions. The demineralizing process was seen to reduce mineral content across the lesion from 45 per cent in normal dentine to between 15 and 25 per cent.

Acetic Acid↗
PubMed2000

Studies of dental root surface caries. 2: The role of cementum in root surface caries.

Artificial caries lesions were produced in roots of teeth using an acetate buffer system, when the layer of cementum was either normal in thickness, excessively thickened by hypercementosis, or had been removed completely. The rates of lesion progression were measured in each case using polarized light microscopy to measure lesion depth. Analysis of calcium (Ca) and phosphorus (P) loss during the demineralizing process was carried out. The removal of cementum was found to significantly increase the initial rate of penetration of the lesion into the root, although this rate progressively reduced to a level consistent with that found in normal roots after seven days of demineralization. The overall depth remained consistently greater than that observed in normal roots, or when lesions were produced entirely within hyperplastic cementum. Chemical analysis also showed removal of cementum resulted in an initial doubling of the Ca and P lost from the root surface. Prior direct exposure of segments of normal roots to the oral environment was found not to significantly alter the rate of artificial lesion progression, in comparison with that in the originally protected segment of the root surface. It was concluded that an intact cementum layer has the intrinsic ability to protect the underlying dentine of exposed tooth roots against acidic demineralization and that prior exposure to the oral environment does not significantly alter this ability.

Calcium↗
PubMed1995

Giant synovial cyst of the shoulder presenting as a chest wall mass.

Synovial cysts are most frequently found about the knee. Less commonly they have been described at the shoulder, elbow, ankle, and hip joints. Synovial cysts of the shoulder are associated with rheumatoid arthritis, osteoarthritis, chronic steroid use, Charcot joint disease, and long-standing rotator cuff tears. Although often asymptomatic, patients may present complaining of pain, loss of joint motion, or presence of an unexplained mass. The authors present the case of an elderly man with a very large synovial cyst presenting as an anterior chest wall mass.

Aged↗
PubMed1992

Erosion.

With the current substantial decline in dental caries in adults, and increasing retention of teeth into old age, dental erosion is now being recognised as a major cause of tooth damage. It is easily recognised in its more advanced form, though more difficult to detect in its initial stages. Its mechanisms of action is generally not well understood. In this paper, current concepts of the chemistry of demineralisation of the mineral components of teeth are examined, with view to their providing a better understanding of some of the clinical characteristics of dental erosion of enamel. Categories and properties of potential erosive substances are reviewed. Speculation as to the potential effects of erosive substances on exposed root surfaces leads to consideration of the possible relationship between erosion and rapid caries development. The more commonly recommended mechanisms of control or prevention of erosion are described, and the rationale of their use analysed.

Dental Caries↗
PubMed1988

A case-control study of congenital malformations and occupational exposure to low-level ionizing radiation.

In a case-control study, the authors investigated the association of parental occupational exposure to low-level external whole-body penetrating ionizing radiation and risk of congenital malformations in their offspring. Cases and controls were ascertained from births in two counties in southeastern Washington State, where the Hanford Site has been a major employer. A unique feature of this study was the linking of quantitative individual measurement of external whole-body penetrating ionizing radiation exposure of employees at the Hanford Site, using personal dosimeters, and the disease outcome, congenital malformations. The study population included 672 malformation cases and 977 matched controls from births occurring from 1957 through 1980. Twelve specific malformation types were analyzed for evidence of association with employment of the parents at Hanford and with occupational exposure to ionizing radiation. Two defects, congenital dislocation of the hip and tracheoesophageal fistula, showed statistically significant associations with employment of the parents at Hanford, but not with parental radiation exposure. Neural tube defects showed a significant association with parental preconception exposure, on the basis of a small number of cases. Eleven other defects, including Down syndrome, for which an association with radiation was considered most likely, showed no evidence of such an association. When all malformations were analyzed as a group, there was no evidence of an association with employment of the parents at Hanford, but the relation of parental exposure to radiation before conception was in the positive direction (one-tailed p value between 0.05 and 0.10). Given the number of statistical tests conducted, some or all of the observed positive correlations are likely to represent false positive findings. In view of strong contradictory evidence, based on no demonstrated effects in genetic studies of atomic bomb survivors in Hiroshima and Nagasaki, it is unlikely that these correlations result from a cause and effect association with parental radiation exposure.

Abnormalities, Radiation-Induced↗
PubMed1988

The prevalence at birth of congenital malformations in communities near the Hanford site.

The authors examined the prevalence of congenital malformations among births in Benton and Franklin counties, in southeastern Washington State, from 1968 through 1980. The Hanford Site is in this area and serves as a major employer. In addition, various agriculturally and chemically related activities are in the area. Hospital and vital records were used to identify 454 malformation cases among 23,319 births; this yielded a malformation rate of 19.6 per 1,000 births, a rate similar to those reported in other studies. The rates of specific malformations ascertained during the first year of life were compared with combined rates from the states of Washington, Oregon, and Idaho from the Birth Defects Monitoring Program. Among defects that would be expected to be comparably ascertained, a statistically significant elevated rate of neural tube defects was observed (1.72 per 1,000 births vs. 0.99 per 1,000). Rates of cleft lip were significantly lower in Benton and Franklin counties than in the Birth Defects Monitoring Program (0.59 per 1,000 vs. 1.17 per 1,000). For congenital heart defects, pyloric stenosis, and Down syndrome, which are often not diagnosed in the newborn period, Birth Defects Monitoring Program data did not offer appropriate comparisons. The rates of these defects did not appear to be elevated in relation to rates found in other relevant populations. When rates of neural tube defects were compared with those in populations other than the Birth Defects Monitoring Program, the Benton and Franklin county rates were still considered to be elevated. The increased bicounty rate cannot be explained by employment of the parents at Hanford or by the impact of plant emissions on the local population.

Congenital Abnormalities↗
PubMed1982

The establishment of a course to train dental hygienists in South Australia: an evaluation after three years.

South Australia was the first State to legislate for the introduction of dental hygienists in Australia. A training course was established in 1975, and accepted ten trainees each year until 1980. The course was one year full-time, and it's content was based initially on recommendations by the General Dental Council of Great Britain for the training of hygienists. This was augmented with increased content in the behavioural science area and a topic approach to programming. The nature of the programme, selection, and assessment of students is discussed. Indications are that the course is well accepted by the majority of hygienists and their employing dentists from both the public and private sector.

Australia↗