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A study on visible light-cured composite resins. The influence of long-term water immersion on physical and mechanical properties
184
J. Dent.
1987;
15: No. 4
photoelectron spectroscopy (ESCA) and reflection electron diffraction. Bonding to the as-polished surface is stronger than to oxidized surfaces. This is due to the absorption of a several molecule thick layer of H,O on to the CO,O, layer of the oxidized surfaces which lowers the bond strength. The as-polished surface which is an amorphous passive film develops a superior bond strength compared to oxidized surfaces which are composed mainly of CO,O,. (52 references) H. Hisamitsu The management of fractures of the mandible using Chacnpy’s plate osteosynthesis. A retrospective study. Janssen J. and Bossuyt M. (1986) Acta Stomato/. Be/g. 83, 11 l-120. A total of 40 patients with fractures of the mandible were reviewed in an attempt to clarify the role of the Champy miniature malleable screw plate in the treatment of these injuries. The technique uses intraoral reduction to achieve monocortical non-compressive osteosynthesis with the plate being cold-hammered from an alloy of chromium, nickel and molybdenum. Intermaxillary fixation (IMF) was used for six patients with condylar fractures accompanied by occlusal deformity, and for five with single fractures of the body of the mandible and minimal occlusal displacement. Intraoral wire fixation was employed for four patients with severely displaced fragments, including two with an additional alveolar fracture. The remaining 25 patients were treated by open reduction with five Nichrominox and 27 Champy plates. Ten patients with a fracture of the body of the mandible together with additional condylar or maxillary fractures, and six with severe displacement of the fragments also required a short period of IMF. No IMF was used for the remaining nine patients as in three partially or completely edentulous cases this was not possible and in six the Champy plate was used electively because of breathing difficulty, dubious consciousness, or patient objection to IMF. The incidence of postoperative complications with the Champy technique was comparable to other methods. This method has virtually universal application with considerably increased patient comfort. The technique is contraindicated in the presence of infection, in comminuted fractures, and in cases with bony defects. (20 references) M. J. Shapiro A study on visible light-cured composite resins. The influence of long-term water immersion on physical and mechanical properties. Zui S. and Arai K. (1986) Jap. J. Dent Mat. 5, 602-615. The physical and mechanical properties of three visible light-cured composite resins (Heliosit, Vivadent, Liechtenstein; Plurafil Super, Litema, FR Germany; Visio Dispers. Espe, FR Germany) were examined over a period of 3 years and compared with one conventional composite resin (Clearfil F II, Kuraray, Japan). In the examination of water sorption, the conventional composite resin demonstrated an increase in water uptake during a 3-year period. On the other hand, the three visible light-cured composite resins all showed a continuous decrease after about 3 or 6 months. Considering the temporal change, water sorption
readings after 7 days are not accurate for comparing the tendency of the four composite resins. No air bubbles were present within specimens of the three visible light-cured composite resins, as shown by SEM, whereas a number of air bubbles were found inside the specimen of the conventional composite resin. The three visible light-cured composite resins (microfilled resins) were more soluble than the conventional composite resin. The surface layer of all four resins showed signs of disintegration, being more marked in those with high solubility. Such disintegration occurred far inside the specimens. In respect of tensile strength, all four resins reached an equilibrium after 3 days and the values remained steady for 3 months or 6 months. After 1 year, however, they tended to decrease continuously. Similarly, the transverse strength of the four resins reached an equilibrium after 3 days, but remained steady for only 3 months. After about 6 months or 1 year, however, these also tended to decrease continuously. For all four composite resins, the rate of decrease of transverse strength was always much greater than that of tensile strength. H. Hisamitsu. Erhvervsbetingede hudproblemer pa henderne laboratorietandteknikere. (Occupational skin problems on the hands in dental technicians.) Blichman C. W. and Roed-Pedersen J. (1986) Tandlaegebladet. 90, 7 15-7 18.
hos
A questionnaire concerning occupational hand dermatitis was sent to all 7 19 registered Danish dental technicians. The response rate was 76 per cent. Fifty-seven per cent of technicians reported that they had suffered or suffered presently from skin problems on the hands. Out of 10 materials on which information was given, acrylic resin appeared to be the main cause of symptoms, causing skin irritation in 49 per cent of occupational users. Other substances reported to cause skin irritation by occupational users were epoxy adhesives (30 per cent), cyanoacrylate adhesives (27 per cent), benzoylperoxide (25 per cent) and Optosil (Bayer, Leverkusen, FR Germany) (16 per cent). No significant sex differences in prevalence of skin problems on the hands were demonstrated. However, in the group of technicians with reported skin irritation the prevalence of nickel and/or cobalt allergy was higher in female technicians (31 per cent) than in male (16 per cent). (12 references) Einar Berg Statistical analysis of cases of missing teeth. Li Nan de et al. (1986) Chin, J. Stomatol. 21, 176-l
79.
An analysis of 3579 patients with missing teeth was made, the sample consisting of 2 107 males and 1472 females. Missing teeth were encountered more frequently in the maxilla than in the mandible, with anterior teeth most common (3 1.7 per cent of cases). Edentulousness in either one or both jaws was the second most frequent observation. An edentulous maxilla was more common than an edentulous mandible with 50.6 per cent of such cases being edentulous in both jaws. The first molar teeth were absent in over 10 per cent of cases and missing incisor teeth were more common in the maxilla than in the mandible. There was a relationship between the age of patients and teeth missing. (4 references) Liao Fang-gang and Wei Yi
J. Dent.
1987;
15: No. 4
photoelectron spectroscopy (ESCA) and reflection electron diffraction. Bonding to the as-polished surface is stronger than to oxidized surfaces. This is due to the absorption of a several molecule thick layer of H,O on to the CO,O, layer of the oxidized surfaces which lowers the bond strength. The as-polished surface which is an amorphous passive film develops a superior bond strength compared to oxidized surfaces which are composed mainly of CO,O,. (52 references) H. Hisamitsu The management of fractures of the mandible using Chacnpy’s plate osteosynthesis. A retrospective study. Janssen J. and Bossuyt M. (1986) Acta Stomato/. Be/g. 83, 11 l-120. A total of 40 patients with fractures of the mandible were reviewed in an attempt to clarify the role of the Champy miniature malleable screw plate in the treatment of these injuries. The technique uses intraoral reduction to achieve monocortical non-compressive osteosynthesis with the plate being cold-hammered from an alloy of chromium, nickel and molybdenum. Intermaxillary fixation (IMF) was used for six patients with condylar fractures accompanied by occlusal deformity, and for five with single fractures of the body of the mandible and minimal occlusal displacement. Intraoral wire fixation was employed for four patients with severely displaced fragments, including two with an additional alveolar fracture. The remaining 25 patients were treated by open reduction with five Nichrominox and 27 Champy plates. Ten patients with a fracture of the body of the mandible together with additional condylar or maxillary fractures, and six with severe displacement of the fragments also required a short period of IMF. No IMF was used for the remaining nine patients as in three partially or completely edentulous cases this was not possible and in six the Champy plate was used electively because of breathing difficulty, dubious consciousness, or patient objection to IMF. The incidence of postoperative complications with the Champy technique was comparable to other methods. This method has virtually universal application with considerably increased patient comfort. The technique is contraindicated in the presence of infection, in comminuted fractures, and in cases with bony defects. (20 references) M. J. Shapiro A study on visible light-cured composite resins. The influence of long-term water immersion on physical and mechanical properties. Zui S. and Arai K. (1986) Jap. J. Dent Mat. 5, 602-615. The physical and mechanical properties of three visible light-cured composite resins (Heliosit, Vivadent, Liechtenstein; Plurafil Super, Litema, FR Germany; Visio Dispers. Espe, FR Germany) were examined over a period of 3 years and compared with one conventional composite resin (Clearfil F II, Kuraray, Japan). In the examination of water sorption, the conventional composite resin demonstrated an increase in water uptake during a 3-year period. On the other hand, the three visible light-cured composite resins all showed a continuous decrease after about 3 or 6 months. Considering the temporal change, water sorption
readings after 7 days are not accurate for comparing the tendency of the four composite resins. No air bubbles were present within specimens of the three visible light-cured composite resins, as shown by SEM, whereas a number of air bubbles were found inside the specimen of the conventional composite resin. The three visible light-cured composite resins (microfilled resins) were more soluble than the conventional composite resin. The surface layer of all four resins showed signs of disintegration, being more marked in those with high solubility. Such disintegration occurred far inside the specimens. In respect of tensile strength, all four resins reached an equilibrium after 3 days and the values remained steady for 3 months or 6 months. After 1 year, however, they tended to decrease continuously. Similarly, the transverse strength of the four resins reached an equilibrium after 3 days, but remained steady for only 3 months. After about 6 months or 1 year, however, these also tended to decrease continuously. For all four composite resins, the rate of decrease of transverse strength was always much greater than that of tensile strength. H. Hisamitsu. Erhvervsbetingede hudproblemer pa henderne laboratorietandteknikere. (Occupational skin problems on the hands in dental technicians.) Blichman C. W. and Roed-Pedersen J. (1986) Tandlaegebladet. 90, 7 15-7 18.
hos
A questionnaire concerning occupational hand dermatitis was sent to all 7 19 registered Danish dental technicians. The response rate was 76 per cent. Fifty-seven per cent of technicians reported that they had suffered or suffered presently from skin problems on the hands. Out of 10 materials on which information was given, acrylic resin appeared to be the main cause of symptoms, causing skin irritation in 49 per cent of occupational users. Other substances reported to cause skin irritation by occupational users were epoxy adhesives (30 per cent), cyanoacrylate adhesives (27 per cent), benzoylperoxide (25 per cent) and Optosil (Bayer, Leverkusen, FR Germany) (16 per cent). No significant sex differences in prevalence of skin problems on the hands were demonstrated. However, in the group of technicians with reported skin irritation the prevalence of nickel and/or cobalt allergy was higher in female technicians (31 per cent) than in male (16 per cent). (12 references) Einar Berg Statistical analysis of cases of missing teeth. Li Nan de et al. (1986) Chin, J. Stomatol. 21, 176-l
79.
An analysis of 3579 patients with missing teeth was made, the sample consisting of 2 107 males and 1472 females. Missing teeth were encountered more frequently in the maxilla than in the mandible, with anterior teeth most common (3 1.7 per cent of cases). Edentulousness in either one or both jaws was the second most frequent observation. An edentulous maxilla was more common than an edentulous mandible with 50.6 per cent of such cases being edentulous in both jaws. The first molar teeth were absent in over 10 per cent of cases and missing incisor teeth were more common in the maxilla than in the mandible. There was a relationship between the age of patients and teeth missing. (4 references) Liao Fang-gang and Wei Yi