PubMed Health⌕ Search

Biomedical subjects

P Lagouvardos

Publications and source records attributed to P Lagouvardos.

8 recordsLinked to original sources
PubMed1990

[Crack path in dental amalgams].

The need of amalgam to resist fracture becomes a more evident necessity when restoration margins are taken into consideration. Marginal microcracks permit bacteria to pass beneath the restoration resulting in cement base dessalution, secondary caries and pulp inflammation. Fracture toughness of amalgam is usually studied indirectly from the maximum force required to fracture the amalgam, during compressive, tensile or bend stresses, through its ability to deform plastically or its surface hardness. Important information on fracture toughness of amalgams can be also taken from metallographic studies of their microstructures, during or after the formation of a crack. This study was planned to evaluate the microcracks produced on the surface of different amalgams, with a Vickers pyramid head of a hardness tester and their relation to the different phases of the amalgam structure. Seven amalgams were studied: Amalcap-F, Tytin, Cupralloy, Ana-2000 and three experimental combinations of them, in order to have in the same amalgam different alloy particles, for evaluation purposes. The result showed that the structure elements, that mainly assist crack formation and propagation, are voids and gamma 2-phase, while elements that resist fracture are alloy particles (gamma-phase) in conventional amalgams, eutectic spheres in admixed high copper amalgams and eta'-phase crystals in single melt high copper amalgams.

Dental Amalgam↗
PubMed1989

Coronal fractures in posterior teeth.

Coronal fractures of posterior teeth are not rare in clinical practice. Most of the time they constitute a restorational problem for the clinician, since they usually end below the free gingival crest. Two hundred coronal fractures of posterior teeth were examined in this study, with respect to several factors. Some of the factors were the sex and age of the patient, type and location of the tooth, and vitality of the pulp. The results showed that frequency of fractures is not influenced by the sex or age of the patient, the type or location of the tooth, or the vitality of the pulp. Factors that significantly affect the appearance of a fracture include caries, restored surfaces, and tooth morphology. Lingual cusps fracture more often than buccal cusps, fractures ended more frequently above or at the gingival crest in teeth with vital pulps, and in nonvital teeth fractures ended more frequently below the crest. Conservative cavity designs for tooth restorations and conservative access to the root canals for endodontic treatment will decrease the frequency of tooth or restoration fracture.

Adult↗
PubMedDate not supplied

[Greek dental journals: statistics on their scientific reports of the years 1982-1986].

Since the number of dental journals grows bigger every year it becomes important for the practitioner researcher teacher and editorial stuff to be informed for the content of the journals. The scientific reports in four Greek dental journals were recorded and evaluated according to several parameters. All the reports published in the years 1982-1986 were recorded and these were covering more than 90% of the total number of Greek scientific articles of this period. The results revealed an association between field and journal as well as between type of the report and journal, type and number of reports, type and number of authors, type and volume of the report, type and presence of tables, figures or photographs, type and number of references and type and cost of the report. It was also shown that in their largest percent the reports were dealing with Oral Medicine (16%), were of the review type (56.1%), were written by only one author (37.1%), contained no tables (58.8%) or diagrams (53.7%), contained photographs (63.8%), had references on foreign articles (87.7%) and cost not more than 8.000 drs (75.5%).

Factor Analysis, Statistical↗
PubMedDate not supplied

[Clinicostatistical study of the reasons for placing and replacing restorations].

This article presents the results of a clinical study conducted in the department of Operative Dentistry of the University of Athens. The reasons for placing and replacing restorations, the restorative material used, patient's age and sex, teeth and surfaces involved and age of replaced restorations were the variables studied in 1520 restorations. The results revealed that 53.2% of the restorations were placed for the first time. 92.6% of the new restorations were placed due to primary caries. Secondary caries were the reasons for the 35% of the replaced with amalgam restorations. Secondary caries and color mismatch were the reasons for the 25% and 23.2% respectively of the replaced with composite restorations.

Adolescent↗
PubMedDate not supplied

[Compressive and bend strength of experimental admixed high copper alloys].

Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutectic spheres are blend with conventional flakes. In the present study the compressive strength, bend strength and microstructure of two high-copper alloys (Tytin, Ana-2000) is compared with three experimental alloys prepared of the two high copper by mixing them in proportions of 3:1, 1:1 and 1:3 by weight. The results revealed that experimental alloys inherited high early and final strength values without any significant change in their microstructure.

Copper↗