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Journal of dentistry Abstract from this issue
Journal of Dentistry,
10, No. 3, 1982,
pp. 269-270
JOURNAL
OF DENTISTRY
Abstracts
from
this
Printed in Great Britain
issue
M. and WILSON A. D. Relationship between stress relaxation and viscoelastic properties of dental materials. J. Dent 10 (1982) 181-186. Recent published work has shown that the BRADEN
stress relaxation of a number of dental materials was substantially linear on a logarithmic time plot. It is shown mathematically, from linear viscoelestic theory and the use of Fourier Integrals, that such linear behaviour can in principle be related to viscoelastic properties obtained by oscillatory measurements. In particular, the rate of stress relaxation is related linearly with the mechanical loss tangent. Comparisons of experimental data with such predictions is reported. WILSON A. D., CRISPS. and LEWIS B. G. The aqueous erosion of silicophosphete cements.J. Dent. 10 (1982) 187-197. The aqueous erosion of silicophosphate cements is broadly similar to that of dental silicate cements. Initially, soluble reaction products--sodium, phosphatesandaluminofluorides--are the predominate species eluted. Ultimately, only small amounts of fluoride, sodium and silica are eluted. The amounts can differ considerably from cement to cement, which could affect cariostatic effectiveness and structural stability. DUMMER P.M. H. and GIDDEN J. A method for the repair of Rochette-typa adhesive bridges. J. Dent. 10 (1982) 198200. A method for the repair of a bonded porcelain pontic lost from a Rochette-type adhesive bridge is described. The technique relies on the preparation of pits in the pontic substructure to retain acrylic or composite facings. This simple and inexpensive technique, which does not involve the removal of the bridge, can be carried out either at the chairside or with the aid of laboratory facilities.
ROOD J. P. and PATEROMlCHElAKlS S. Local anaesthetic failures due to an increase in sensory nerve impulses from inflammatory sensitization. J. Dent. 10 (1982) 201-206.
Mechanisms have been suggested to explain the inadequacy of standard local anaesthetic infiltrations in inflammatory conditions. Evidence is provided to support the suggestion that failures are at least partly due to an increase in the number of sensory
impulses generated peripherally ducted in the nerve.
and con-
CRUICKSHANKS-BOYD D. W. Physical metallurgy of dental amalgams. 1. Particlesize analysis and phase content of amalgam alloys. J. Dent 10 (1982) 207216. The particle size, morphology, composition and phase content of conventional and highcopper amalgam alloys have been determined. Important differences between the alloys are highlighted. HENKING J. P. A. Overdentures. J. Dent 10 (1982) 217-225. The factors and procedures involved in the use of overdentures as a form of treatment are revised. ROBERTS B. J. Help for the dry mouth patient. J. Dent. 10 (1982) 226-234. The properties of saliva have been defined in an attempt to help patients with xerostomia (dry mouth) by producing an artificial saliva. Clinical trials, using various saliva substitutes, were carried out and it has been shown that polyethylene oxide could have a use in the future. ADENUBI J. 0. The acid-etch technique in children: an experience in Lagos. J. Dent. 10 (1982) 235-242. A clinical study of the acid-etch technique for temporary restorations in 32 Nigerian children is reported. The most frequent restoration was that of the fractured incisor. More acid-etch restorations were used on chronological hypoplasia than on tetracycline staining. The maximum period of follow up of the restorations so far is 24 months. Two cases of gingival inflammation developed due to irritation by a bulky labial facing in two children with
270
Journal of Dentistry Vol. lo/No. 3
chronological hypoplasia and tetraclycline staining. The technique was also used successfully to splint a traumatized and mobile lower central incisor. After a followup period of 12-24 months, results show that over 80 per cent of the acid-etch restorations are still intact. The acid-etch technique with the use of the composite resin Concise is therefore proving to be a suitable and successful semipermanent restoration to solve the problems of aesthetics in the young patient who presents with a fractured incisor, enamel hypoplasia or tetracycline staining of the anterior teeth. ROBERTS B. W. Bone induction in healing tooth sockets using piezo-electric foil. J. Dent. 10 (1982) 243-247. By placing Electret piezo sheet film in a healing tooth socket it was found that the resultant edentulous space was wider and higher than the corresponding control. Histologically osteoid was produced faster, especially at the socket rim, and the trabeculas were thicker and formed faster than in thecontrol. The resultant edentulous space was therefore considered superior to the control space. MARKITZIU A., GEDALIA I., STABHOLZ A. and SHUVAL J. Prevention of caries progress in xeroetomic patients by topical fluoride applications: a study in vivo and in vitro. J. Dent 10 (1982) 248-253.
Fluoride uptake by the surface enamel of teeth was studied in vivo and in vitro in xerostomic patients and in extracted human teeth respectively, following various topical fluoride applications (Duraphat varnish, 2.26 per cent F; APF gel, 1.23 per cent F; Elmex gelee, 0.4 per cent F). Fluoride increments known to be effective for inhibition of caries in xerostomic patients were achieved in vivo and in vitro from all preparations. Arrest of caries was observed only in patients who were cooperative in the preventive fluoride programme. It was concluded, on the basis that the fluoride incorporation found in the experiments in virro was not stable, that topical fluoride application in xerostomic patients had to be used frequently to ensure a prophylactic success. DAVY K. W. M. and CAUSTON B. E. Radio-opaque denture base: a new acrylic co-polymer. J:Denr. 10, (1982) 254-264. The aim of the study was to find a denturebase acrylic polymer that is radioopaque, in order to enable easy recovery of lost fragments from patients. A polymer was needed that gelled with methyl methacrylate and also contained a chemically bonded X-ray opacifying atom; the resulting copolymer also needed to retain good mechnical properties to act as a denture base. A co-polymer containing 36110 per cent poly(2, Bdibromopropyl methacrylate) was found to possess all the above properties.
10, No. 3, 1982,
pp. 269-270
JOURNAL
OF DENTISTRY
Abstracts
from
this
Printed in Great Britain
issue
M. and WILSON A. D. Relationship between stress relaxation and viscoelastic properties of dental materials. J. Dent 10 (1982) 181-186. Recent published work has shown that the BRADEN
stress relaxation of a number of dental materials was substantially linear on a logarithmic time plot. It is shown mathematically, from linear viscoelestic theory and the use of Fourier Integrals, that such linear behaviour can in principle be related to viscoelastic properties obtained by oscillatory measurements. In particular, the rate of stress relaxation is related linearly with the mechanical loss tangent. Comparisons of experimental data with such predictions is reported. WILSON A. D., CRISPS. and LEWIS B. G. The aqueous erosion of silicophosphete cements.J. Dent. 10 (1982) 187-197. The aqueous erosion of silicophosphate cements is broadly similar to that of dental silicate cements. Initially, soluble reaction products--sodium, phosphatesandaluminofluorides--are the predominate species eluted. Ultimately, only small amounts of fluoride, sodium and silica are eluted. The amounts can differ considerably from cement to cement, which could affect cariostatic effectiveness and structural stability. DUMMER P.M. H. and GIDDEN J. A method for the repair of Rochette-typa adhesive bridges. J. Dent. 10 (1982) 198200. A method for the repair of a bonded porcelain pontic lost from a Rochette-type adhesive bridge is described. The technique relies on the preparation of pits in the pontic substructure to retain acrylic or composite facings. This simple and inexpensive technique, which does not involve the removal of the bridge, can be carried out either at the chairside or with the aid of laboratory facilities.
ROOD J. P. and PATEROMlCHElAKlS S. Local anaesthetic failures due to an increase in sensory nerve impulses from inflammatory sensitization. J. Dent. 10 (1982) 201-206.
Mechanisms have been suggested to explain the inadequacy of standard local anaesthetic infiltrations in inflammatory conditions. Evidence is provided to support the suggestion that failures are at least partly due to an increase in the number of sensory
impulses generated peripherally ducted in the nerve.
and con-
CRUICKSHANKS-BOYD D. W. Physical metallurgy of dental amalgams. 1. Particlesize analysis and phase content of amalgam alloys. J. Dent 10 (1982) 207216. The particle size, morphology, composition and phase content of conventional and highcopper amalgam alloys have been determined. Important differences between the alloys are highlighted. HENKING J. P. A. Overdentures. J. Dent 10 (1982) 217-225. The factors and procedures involved in the use of overdentures as a form of treatment are revised. ROBERTS B. J. Help for the dry mouth patient. J. Dent. 10 (1982) 226-234. The properties of saliva have been defined in an attempt to help patients with xerostomia (dry mouth) by producing an artificial saliva. Clinical trials, using various saliva substitutes, were carried out and it has been shown that polyethylene oxide could have a use in the future. ADENUBI J. 0. The acid-etch technique in children: an experience in Lagos. J. Dent. 10 (1982) 235-242. A clinical study of the acid-etch technique for temporary restorations in 32 Nigerian children is reported. The most frequent restoration was that of the fractured incisor. More acid-etch restorations were used on chronological hypoplasia than on tetracycline staining. The maximum period of follow up of the restorations so far is 24 months. Two cases of gingival inflammation developed due to irritation by a bulky labial facing in two children with
270
Journal of Dentistry Vol. lo/No. 3
chronological hypoplasia and tetraclycline staining. The technique was also used successfully to splint a traumatized and mobile lower central incisor. After a followup period of 12-24 months, results show that over 80 per cent of the acid-etch restorations are still intact. The acid-etch technique with the use of the composite resin Concise is therefore proving to be a suitable and successful semipermanent restoration to solve the problems of aesthetics in the young patient who presents with a fractured incisor, enamel hypoplasia or tetracycline staining of the anterior teeth. ROBERTS B. W. Bone induction in healing tooth sockets using piezo-electric foil. J. Dent. 10 (1982) 243-247. By placing Electret piezo sheet film in a healing tooth socket it was found that the resultant edentulous space was wider and higher than the corresponding control. Histologically osteoid was produced faster, especially at the socket rim, and the trabeculas were thicker and formed faster than in thecontrol. The resultant edentulous space was therefore considered superior to the control space. MARKITZIU A., GEDALIA I., STABHOLZ A. and SHUVAL J. Prevention of caries progress in xeroetomic patients by topical fluoride applications: a study in vivo and in vitro. J. Dent 10 (1982) 248-253.
Fluoride uptake by the surface enamel of teeth was studied in vivo and in vitro in xerostomic patients and in extracted human teeth respectively, following various topical fluoride applications (Duraphat varnish, 2.26 per cent F; APF gel, 1.23 per cent F; Elmex gelee, 0.4 per cent F). Fluoride increments known to be effective for inhibition of caries in xerostomic patients were achieved in vivo and in vitro from all preparations. Arrest of caries was observed only in patients who were cooperative in the preventive fluoride programme. It was concluded, on the basis that the fluoride incorporation found in the experiments in virro was not stable, that topical fluoride application in xerostomic patients had to be used frequently to ensure a prophylactic success. DAVY K. W. M. and CAUSTON B. E. Radio-opaque denture base: a new acrylic co-polymer. J:Denr. 10, (1982) 254-264. The aim of the study was to find a denturebase acrylic polymer that is radioopaque, in order to enable easy recovery of lost fragments from patients. A polymer was needed that gelled with methyl methacrylate and also contained a chemically bonded X-ray opacifying atom; the resulting copolymer also needed to retain good mechnical properties to act as a denture base. A co-polymer containing 36110 per cent poly(2, Bdibromopropyl methacrylate) was found to possess all the above properties.