- Email: [email protected]
Effect of bevelling on the occurrence of fractures in the enamel surrounding composite resin fillings
Journal of Dentistry,
6, No. 2, 1978,
pp. 182-186.
Printed in Great Britain
QuurterlyDentulReview Abstracts
DENTAL
from current
international
MATERIALS
GROSS M. D. and MOSER
J. B. A calorimetric study of coffee and tea staining of four composite resins, J. Oral
Rehabil. 4 (1977) 311-322.
’
Batches of specimens of four commercially available composite resin restoratives were prepared with abraded and unfinished (Mylar matrix) surfaces. Calorimetric observations were made before and after 12 of different specimen days’ immersion groups in distilled water, an aqueous solution of instant coffee and a dilute aqueous infusion of tea. Subjective visual assessment of colour changes was also undertaken by 10 observers. Coffee and tea produced significantly greater colour changes than distilled water. Coffee produced more discoloration than tea in the majority of cases. General agreement was observed between subjective and calorimetric data. However, instances demonstrated the unseveral predictability of visual evaluation. Differences in surface finish affected staining by tea more than by coffee and significant differences were observed between results for different brands of material in both solutions. D. J. Setchell 0lLO G. and J0RGENSEN K. D. Effect of bevelling on the occurrence of fractures in the enamel surrounding composite resin fillings, .I. Oral Rehabil. 4
(1977) 305-309. Acid etch composite resin restorations were placed in 105 single surface cavities in extracted human teeth. Three cavosurface margin designs (90” butt joint, type I; 0.25-0.50 mm wide bevel, type II; 0.5O-
literature
1.0 mm bevel, type I II) were tested using three brands of commercial restorative. Excess material was ground away 10 minutes after the commencement of mixing. Fracture zones caused by resisted thermal and polymerization shrinkage occurred in enamel surrounding some cavities of all designs and were disclosed by methylene blue dye before examination in a stereo microscope. Fractures occurred most frequently in type I and least frequently in type III situations. Marked differences in other instances were observed between materials. Since the large bevels required to minimize such enamel fractures are undesirable in many clinical situations, the authors suggest avoiding the polishing of acid etch restorations until water absorption by the resin has relieved the stresses of inhibited contraction 24 hours after placement. D. J. Setchell
ENDODONTICS RAM 2. , Effectiveness of root canal Surg. 44 (1977) 306-312.
irrigation,
ora/
Irrigation is an important adjunct to the mechanical preparation of the pulp canal during root canal therapy. Carried out intermittently during the enlargement of the canal, irrigation lubricates the action of the instruments, flushes debris from the canal and, depending on the irrigant, may aid its disinfection. This study was designed to assess the effectiveness of this procedure and to determine the conditions that must be met to achieve success, in particular the minimum diameter of the canal required to allow irrigation to reach the apex.
6, No. 2, 1978,
pp. 182-186.
Printed in Great Britain
QuurterlyDentulReview Abstracts
DENTAL
from current
international
MATERIALS
GROSS M. D. and MOSER
J. B. A calorimetric study of coffee and tea staining of four composite resins, J. Oral
Rehabil. 4 (1977) 311-322.
’
Batches of specimens of four commercially available composite resin restoratives were prepared with abraded and unfinished (Mylar matrix) surfaces. Calorimetric observations were made before and after 12 of different specimen days’ immersion groups in distilled water, an aqueous solution of instant coffee and a dilute aqueous infusion of tea. Subjective visual assessment of colour changes was also undertaken by 10 observers. Coffee and tea produced significantly greater colour changes than distilled water. Coffee produced more discoloration than tea in the majority of cases. General agreement was observed between subjective and calorimetric data. However, instances demonstrated the unseveral predictability of visual evaluation. Differences in surface finish affected staining by tea more than by coffee and significant differences were observed between results for different brands of material in both solutions. D. J. Setchell 0lLO G. and J0RGENSEN K. D. Effect of bevelling on the occurrence of fractures in the enamel surrounding composite resin fillings, .I. Oral Rehabil. 4
(1977) 305-309. Acid etch composite resin restorations were placed in 105 single surface cavities in extracted human teeth. Three cavosurface margin designs (90” butt joint, type I; 0.25-0.50 mm wide bevel, type II; 0.5O-
literature
1.0 mm bevel, type I II) were tested using three brands of commercial restorative. Excess material was ground away 10 minutes after the commencement of mixing. Fracture zones caused by resisted thermal and polymerization shrinkage occurred in enamel surrounding some cavities of all designs and were disclosed by methylene blue dye before examination in a stereo microscope. Fractures occurred most frequently in type I and least frequently in type III situations. Marked differences in other instances were observed between materials. Since the large bevels required to minimize such enamel fractures are undesirable in many clinical situations, the authors suggest avoiding the polishing of acid etch restorations until water absorption by the resin has relieved the stresses of inhibited contraction 24 hours after placement. D. J. Setchell
ENDODONTICS RAM 2. , Effectiveness of root canal Surg. 44 (1977) 306-312.
irrigation,
ora/
Irrigation is an important adjunct to the mechanical preparation of the pulp canal during root canal therapy. Carried out intermittently during the enlargement of the canal, irrigation lubricates the action of the instruments, flushes debris from the canal and, depending on the irrigant, may aid its disinfection. This study was designed to assess the effectiveness of this procedure and to determine the conditions that must be met to achieve success, in particular the minimum diameter of the canal required to allow irrigation to reach the apex.