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Biomedical subjects

A R Grieve

Publications and source records attributed to A R Grieve.

At least 19 recordsLinked to original sources
PubMed1996

Bacterial leakage in endodontics: an improved method for quantification.

A new method for studying leakage of root fillings using the bacterium Pseudomonas fluorescens ATCC 13525 is described. The presence of the microorganism is detected by fluorimetry and can thus be used to measure the depth of penetration from the root apex toward the crown of the tooth. This system, applied to a number of methods of root canal filling, showed that procedures involving compaction of the gutta-percha gave a more effective seal than the use of a paste sealer with uncondensed gutta-percha. There was no statistically significant difference between the leakage results from the lateral, vertical, and thermomechanical condensed techniques.

Dental Leakage↗
PubMed1995

Release of fluoride from glass polyalkenoate (ionomer) cement subjected to radiant heat.

OBJECTIVES: This study was designed to examine the effect of the application of radiant heat on the fluoride release from the surface of a glass polyalkenoate cement. METHODS: The radiant heat was applied at different intensities and for different time intervals using a high-intensity fibreoptic quartz halogen light source. A standard technique was used to measure the amount of fluoride released from one surface of a cement specimen into deionized water. Fluoride release was measured for a time period of over 2 years. RESULTS: Results showed that fluoride was still being released 2 years after placement. The application of radiant heat did not have a statistically significant effect on the release of fluoride from the surface of this material. CONCLUSIONS: There appeared to be a trend suggesting that the greater the amount of heat applied, the less fluoride was released from the surface of the cement. A considerable inter- and intrabatch variation was noted in the amount of fluoride released from the cement.

Fiber Optic Technology↗
PubMed1995

An in vivo recording of variations in oral temperature during meals: a pilot study.

Thermocycling is often used in the in vitro evaluation of marginal leakage of dental restorations. The in vivo temperatures occurring during meals were recorded at different surfaces of restored teeth, to compare the variations in temperature with laboratory thermocycling. Temperatures were recorded with thermocouples at three different sites: (1) on the facial surface of a silver amalgam restoration, (2) at the base of a silver amalgam restoration and (3) within the root canal. The maximal temperature differences between upper and lower extremes were 29.6 degrees C at the base of a coronal restoration, 27.1 degrees C at the facial surface, and 11.8 degrees C within the root canal. A practical regimen for these experiments is suggested in the light of these ranges because many thermocycling regimens in in vitro studies appear extreme or unrealistic.

Beverages↗
PubMed1993

A radiographic study of post-retained crowns in patients attending a dental hospital.

A total of 327 post-retained crowns were examined radiographically and a number of features were assessed including the length of post, length of remaining root filling, periapical condition, fit and angulation of the post and quality of root filling. The post length was equal to or greater than that of the crown in only 34% of cases. Although the majority of posts fitted well laterally, 43% did not extend longitudinally as far as the end of the prepared post hole. Some 20% deviated from the line of the root canal but the number of actual lateral perforations was small. A total of 47% of the teeth had areas of radiolucency around the root apices. A majority of root fillings were judged to be unsatisfactory and there was no radiographic evidence of any root filling at all in nearly 10% of cases.

Adolescent↗
PubMed1993

The effects of dentine bonding agents on marginal leakage of composite restorations--long-term studies.

The aim of this study was to compare the effects upon marginal leakage of a number of dentine bonding agents when used with a posterior composite resin, Occlusin, after storage for periods of up to 2 years. The bonding agents used were Gluma, Scotchbond, Topaz and an experimental material. The results were compared with a glass ionomer, Chemfil II. Class V cavities with or without a bevelled cavo-surface margin were prepared in the buccal surfaces of extracted premolar teeth. Following restoration, the teeth were stored for periods of up to 2 years and then thermally cycled. Marginal leakage was subsequently demonstrated using a radioactive isotope containing 45Ca, and an auto-radiographic technique. Image analysis was used to determine the total amount of linear leakage for each specimen. The results showed that some leakage occurred for all materials at each time interval. The bevelled design of cavity allowed significantly less leakage than the unbevelled cavity. Overall, there was little difference between the various dentine bonding agents. The glass ionomer restorations showed significantly less leakage than the composite resin and dentine bonding agent combinations in unbevelled cavities.

Composite Resins↗
PubMed1993

The use of intermediary resins when bonding glass polyalkenoate (ionomer) cement to composite resin.

This study was designed to examine the effects of three different types of glass polyalkenoate lining cement combined with three different types of bonding resin and varying surface treatments on the seal between the lining cement and the composite resin as used in the so called 'laminate' technique. The seal was assessed using a radioisotope and autoradiographic technique. Results showed that all the cements behaved in a manner specific to them. The seal of all systems examined could be improved, or at least, not compromised, by modification of the surface of the cement prior to attachment of the resin. Only one type of intermediate resin gave a reliable seal when applied to an unmodified surface of any of the cements under investigation. It is concluded that all the glass polyalkenoate cements tested behave differently when used beneath composite resin. Recommendations about the laminate restoration technique must be related to the specific combinations of materials used.

Composite Resins↗
PubMed1991

The effects on the dental pulp of a composite resin and two dentine bonding agents and associated bacterial microleakage.

The pulpal reaction associated with a composite resin alone and composite resin used in conjunction with two dentine bonding agents was studied. Class V cavities were prepared on the labial surfaces of the canine teeth of 18 male ferrets. After acid etching of the enamel margins, the cavities were restored with either a composite resin alone or in combination with one of two dentine bonding agents, Scotchbond and Gluma. One cavity in each animal was filled with Kalzinol as a control. The animals were killed after 7, 14 and 28 days. After histological processing, the pulpal changes were assessed qualitatively and quantitatively according to standard criteria. There were variations in the pulpal response at all time intervals. The responses to the two dentine bonding agents were similar to those found with composite resin alone. No pulpal inflammation was observed in the control teeth. Gram-positive micro-organisms were identified at the interface of restoration and cavity wall, or within the dentinal tubules in virtually all cases in which pulpal inflammation was observed.

Animals↗
PubMed1991

An evaluation of three methods of polishing porcelain by comparison of surface topography with the original glaze.

The value of a procedure for polishing porcelain restorations that would avoid the necessity of glazing in a furnace following minor chairside adjustments is discussed. The efficacy of three polishing systems--a diamond paste, a pumice and water slurry followed by whiting, and a proprietary method--were tested in the laboratory using surface profile recording. The results showed that both the diamond paste and the pumice/whiting gave surface finishes similar to the original glazed surface. The smoothest surface was produced by the diamond paste. The proprietary porcelain finishing kit created the least smooth surface.

Analysis of Variance↗
PubMed1990

The effects of dentine bonding agents on marginal leakage of composite restorations.

The aim of this study was to compare the effects upon marginal leakage of a number of dentine bonding agents: Gluma, Scotchbond, Topaz and an experimental material when used with a posterior composite resin, Occlusin. The results were also compared with composite used without a dentine bonding agent and with a glass ionomer, Chemfil II. Class V cavities with or without a bevelled cavo-surface margin were prepared in the buccal surfaces of extracted premolar teeth. Following restoration, the teeth were stored for periods of up to 3 months and then thermally cycled. Marginal leakage was subsequently determined using a radioactive isotope containing 45Ca, and an autoradiographic technique. Image analysis was used to determine the total amount of linear leakage for each specimen. The results showed that some leakage occurred for all materials at each time interval. The bevelled design of cavity allowed significantly less leakage than the non-bevelled type. The use of dentine bonding agents did not improve the marginal seal of the composite restorations, and the glass ionomer restorations showed significantly less leakage than the composite resin and dentine bonding agent combinations.

Adhesives↗
PubMed1980

An in vitro study of marginal leakage associated with composite restorations using an acidified agar technique.

The marginal leakage associated with a composite restorative material was examined using an in vitro method for the production of secondary caries-like lesions after the restorations had been subjected to thermal cycling. The fillings were placed in cavities with a 90 degrees cavo-surface angle with and without etching of the walls with phosphoric acid and in cavities with a bevelled margin which were also acid etched. Some degree of leakage was demonstrated in 95% of the unetched cavities while approximately half of the restorations in etched unbevelled cavities showed leakage. With the bevelled and etched group virtually no leakage occurred.

Acids↗