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Biomedical subjects

G Oilo

Publications and source records attributed to G Oilo.

At least 37 records · Page 2Linked to original sources
PubMed1989

The suitability of a new index for the evaluation of dental wear.

The suitability of a new index for rating dental wear by different observers was tested. Four dentists, who were first calibrated using the scoring system and then subjected to an inter-examiner agreement test before and after a field study, rated 167 individuals in total in their private dental practices. The incisal/occlusal state of the teeth with regard to restorations and dental wear was recorded. The inter-examiner agreement test proved satisfactory when rating main groups of wear but not so good when rating subcategories. However, a marked improvement in agreement developed between the first and the second test. The individuals composing the field study group are probably not representative of Scandinavian populations in general. Relatively few teeth were missing, and the teeth were well restored. Only the highest age group (80-89 years) displayed the most severe degree of wear to any extent. However, wear into the dentin was observed in 20% of the teeth already in the youngest age group (20-29 years). These teeth were solely incisors and canines of both jaws. In conclusion, we found that the index should be well suited for the evaluation of dental wear in large groups of people by different investigators after adequate training in use of the system has been provided and that tooth wear may be a relatively small problem in urban Scandinavian populations with regular dental care.

Adult↗
PubMed1989

Abrasives in snuff?

The purpose of this study was to determine and calculate the inorganic contents of four brands of snuff. Visual inspection of wet snuff showed fairly large, yellow crystal-like particles. Scanning electron microscopy and X-ray dispersive (EDX) analyses were used to study both wet snuff and ashes of snuff, whereas light emission spectrography was used to determine elements in the ashes. The crystal-like particles did not dissolve in distilled water or in ethanol heated to 60 degrees C. EDX analyses showed that most elements remained in the particles after washing. The total weight percentage of inorganic material in snuff was calculated after burning dried snuff until constant weight was obtained. The ashes of snuff did not contain any crystal-like particles but consisted of a small-grained amorphous mass. The following elements were detected: Ag, Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, P, Pb, Si, Sr, Ti, Va, and Zr. Other elements such as rare earths were not searched for. The weight percentage of inorganic elements ranged between 12.35 +/- 0.69 and 20.95 +/- 0.81. Provided snuff is used in the same manner as chewing tobacco, and some people admit to doing so, there is a risk that its relatively high contents of inorganic material and heavily soluble salts may be conducive to excessive abrasion of teeth and restorations.

Calcium↗
PubMed1988

Occlusal contact wear of prosthodontic materials. An in vivo study.

The wear of gold, porcelain, and heat- and light-cured resins in occlusal contact with resin and porcelain teeth has been studied in vivo. Both weighing of removable segments of fixed partial prostheses and a replica technique allowing scanning electron microscope observations of the worn surfaces were used. The results showed that all materials had the greatest loss of substance when the opposing teeth were of porcelain. The heat-cured, unfilled resin was the least wear-resistant material, followed by light-cured resin, porcelain, and gold. The heat-cured resin showed a combined tribochemical and fatigue type of wear. The light-cured resin and porcelain showed mainly a fatigue type of wear, whereas gold showed a combined abrasive and fatigue type of wear.

Bruxism↗
PubMed1988

Flexural strength and internal defects of some dental porcelains.

The flexural strength, number (n), size, and form of pores in seven different dental porcelains were examined. The flexural strength was approximately 100 MPa for the core materials for metal bonding, 116 MPa for traditional alumina porcelains (NBK 1000, Vitadur N), 150 MPa for two new high-alumina porcelains (Vita Hi Ceram, Cerestore), and 240 MPa for a castable glass (Dicor). The mean pore diameter was approximately 10 microns in all porcelains except Dicor, but with a large and varying range. Dicor showed a mean pore size of 1 micron. The pore density varied from 36.5/mm2 in one of the porcelains for metal bonding to 4367/mm2 in Cerestore. The mean cross-sectional area occupied by pores was below 10% for most porcelains except Vitadur N and Cerestore, showing 17.5% and 32.5%, respectively. No correlation was found between flexural strength and frequency or cross-sectional area of pores of the various products.

Aluminum Oxide↗
PubMed1987

An index for evaluating wear of teeth.

An index for evaluation of dental wear based on Ryge's system comprising three satisfactory and two not acceptable categories was tested in two different age groups of individuals with brain damage. Group 1 consisted of 12 individuals, 3 women and 9 men, with a mean age of 34.5 years. Group 2 consisted of 13 individuals, 4 women and 9 men, with a mean age of 45.1 years. The wear was evaluated by three examiners, two dentists and one dental hygienist. The examiners worked independently, having available at all times the written criteria and a photographic guide illustrating the lowest limit of each category. Each tooth was given a rating in accordance with the index, and the interexaminer agreement of 612 such evaluations was approximately 85%. Each person was given an individual wear rating corresponding to the most severe category comprising 90% of the tooth ratings. The difference in the distribution of individual ratings between the two groups was tested for significance by the ridit method. Significantly greater wear was observed in group 2 than in group 1, indicating a good sensitivity of the index.

Adult↗
PubMed1986

Adhesion of polycarboxylate-based dental cements to enamel: an in vivo study.

The bond strength of two polycarboxylate and two glass ionomer cements to enamel in vivo has been measured by a tensile test method. The four cements were used to cement small stainless steel cylinders onto the facial surfaces of 11 and 21. The cylinders were removed by a tensile force applied by a handpiece containing a semi-conductor sensory unit. The results showed that all cements gave two sets of bond strength values, either a good bond corresponding to a cohesive failure, or a weak bond corresponding to an adhesive failure. The mean bond strength values were lower than those recorded in vitro, and differences among the cements were limited.

Adhesiveness↗