Biomedical subjects

G Douvitsas

Publications and source records attributed to G Douvitsas.

10 recordsLinked to original sources

PubMed1991

Effect of cavity design on gap formation in Class II composite resin restorations.

Qhis study examined the width of the gap at the cervical wall in traditional cavity preparations or adhesive designs that were restored with various composite resins by different procedures. Fifty-four intact human molars were restored with several composite resins and their respective bonding agents. A rectangular cavity was prepared in one proximal surface and a spherical cavity was prepared in the other proximal surface. The composite resin Occlusin with the bonding agent recorded the least gap width compared with similar materials. The spherical cavity restorations recorded less gap width than the rectangular cavity restorations.

Acid Etching, Dental↗

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

[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↗

PubMedDate not supplied

[New aspects for the caries of deep cavities].

This article refers to the contemporary aspects about the carious lesions in the deepest parts of a cavity near the pulp. In these situations the problem that arises is to how deeply this carious dentine should be excavated without the risk of destroying the pulp. On this question there have been expressed two divergent opinions based also on two divergent theories. The one theory supports that during the carious process the microorganisms proceed the decalcification of the dentin, whereas the other theory supports the opposite view. According to the new aspects, in acute carious lesions the decalcification proceeds the bacteria, while in chronic caries the microorganisms, the discoloration and the bacterial invasion are closer to each other. This article also refers to the microflora of deep carious lesions and to the fate of bacteria that remain under the fillings. From this paper we come to the following conclusions: 1) In certain clearly defined conditions some carious dentine should be left at the base of a cavity in order to avoid the pulp exposure. But the periphery of the cavity must be unquestionably caries-free. 2) Few microbes always remain after the excavation of the carious cavities. 3) These microbes under well-fitting restorations do not proliferate and gradually die. 4) The defensive properties of the pulp play also a significant role, because pulp immunoglobulins are able to react upon invasive bacteria. 5) Finally, it must be emphasized that the clinical dentist must not underestimate the microbial role and action.

Dental Caries↗

PubMedDate not supplied