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Biomedical subjects

P Zervas

Publications and source records attributed to P Zervas.

9 recordsLinked to original sources
PubMed1992

Sealing ability of sectional injection thermoplasticized gutta-percha technique with varying distance between needle tip and apical foramen.

The purpose of this investigation was to evaluate the influence of the distance of the needle tip from the apical foramen on the apical seal and the length control of the root filling material when thermoplasticized gutta-percha is injected using a sectional injection technique. Ninety-nine human single-rooted mandibular incisors and permanent premolars with straight canals were divided into three equal Groups A, B and C. In Group A the teeth had relatively the wider root canal, in Group C the narrowest, while in Group B root canal size was intermediate. The root canals of all teeth were prepared with a step-back technique. Roots of Group A were instrumented to a Size 70 4 mm short of the working length, while roots of Groups B and C to a Size 70 6 mm and 8 mm short of the working length, respectively. The teeth of all groups were covered with aluminium foil and embedded in acrylic blocks. After the placement of sealer (Roth 811) the root canals of all teeth were obturated with injection-molded thermoplasticized gutta-percha using a three-stage sectional technique. The roots remained in India ink for three days and then cleared by successive immersion in nitric acid, ascending grades of alcohol and finally in xylene. The linear dye penetration and the linear apical underextentionion of the root canal filling were measured by two independent examiners under a stereo microscope. There was no significant difference in the linear dye leakage between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicuspid↗
PubMed1991

The effect of citric acid treatment on periodontal healing after replantation of permanent teeth.

The aim of this study was to evaluate the effect of surface demineralization on the healing of 120 replanted teeth in fifteen 8- to 16-month-old dogs. Replanted teeth were divided into two groups (A and B). In group A, teeth were replanted following planing of the entire root surface. In group B, teeth were replanted following planing and surface demineralization with citric acid. Replanted teeth were splinted for 7 days, and observation periods were 3, 14 and 56 days. A total of 95 teeth and their surrounding tissues were examined histologically under a light microscope. Histological examination of specimens 3 days after replantation revealed that initial reunion between the root and the alveolar periodontal ligament fibres was via a fibrin-like network in both groups. Fourteen days after replantation histological observations showed superior healing in group B with regard to epithelial condition, periodontal ligament fibre reattachment to the root surface, resorption and functional arrangement of the periodontal ligament fibres. By 56 days after replantation, healing was superior in group A; group B was characterized by severe inflammatory and replacement resorption. These results indicated that surface demineralization had an initial positive effect, but later led to impaired healing.

Animals↗
PubMed1990

Apical placement of needle tip with an injection-thermoplasticized gutta-percha technique for root canal obturation.

It is recommended that when injection-thermoplasticized gutta-percha is used as the obturation technique, the root canal space should be prepared in such a way that the 23-gauge injection needle tip can be placed at a distance 3 to 5 mm short of the working length. In this study the apical seal and extent of gutta-percha were evaluated when the 23-gauge tip was placed at a distance 4 mm, 6 mm, and 8 mm short of the working length. Ninety-nine human single-rooted mandibular incisors and premolars divided into 3 equal groups were used. Their crowns were separated at the cementoenamel junction and their roots were stored in sodium hypochlorite for 1 week. The roots were then instrumented from size 20 at the working length to size 70:4 mm short of the working length in group A, 6 mm in group B, and 8 mm in group C. Following instrumentation, 3 randomly selected roots of each group were used as control. The remaining 30 roots of each group were covered with aluminium foil and embedded in acrylic blocks. The root canals were then dried, coated with sealer (Roth 811) and obturated by injection of thermoplasticized gutta-percha using the single-phase technique. Vertical condensation followed. The roots were immersed in dye for 3 days and then demineralized, dehydrated and cleared in xylene. Measurements of linear dye penetration for the apical seal and for underextension were done by 2 independent examiners under a stereomicroscope. The results of this study showed no statistically significant difference in leakage between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Coloring Agents↗
PubMed1989

Periodontal tissue reactions following root canal obturation with an injection-thermoplasticized gutta-percha technique.

The thermoplasticized gutta-percha obturation technique is a relatively recent development in endodontics. In this study we evaluated the possible effects of heat transmitted to the periodontal tissues when the Obtura root canal filling device was used in dog teeth. Two 8-month-old beagle dogs were used; 56 root canals of 36 teeth (maxillary incisors and first, second and third premolars of both jaws) were divided into two groups. In Group A 26 root canals were obturated with the lateral condensation technique, while in Group B 30 root canals were obturated using the Obtura device, without sealer. Observation periods were 1, 3, 7, 28 and 56 days. After routine laboratory procedures, hematoxylin-eosin stained sections were examined under a light microscope. In this experimental model the thermoplasticized gutta-percha obturation technique caused a periapical inflammatory reaction at all observation periods. Inflammatory reaction and destruction of collagen fibers were localized in the area around the apical delta, while the alveolar founding bone, the roots of the teeth and the periodontal ligament at the side of the root surfaces remained normal.

Animals↗
PubMed1988

[Separation of endodontic instruments into the root canal].

One of the most common accidents during extirpation of the pulp and chemicomechanical preparation is breakage of the endodontic instrument in the root canal. In this paper the causes of the instrument breakage are reported. The methods of handling the accident are discussed, as well as the basic rules of prevention.

Dental Pulp Cavity↗
PubMedDate not supplied

[Histological investigation of neural plexus on developing permanent teeth. Study on puppies].

On permanent premolars of 9 puppies (three groups of 45 days, 3 and 4 months old) the neural plexus was studied, using the Alcian blue/PAS and Bielschowsky staining techniques. Nerve fibres were observed on the 45 days group, directed to the odontoblastic layer, as well as fine nerve bundles, parallel to the vessels. On the 3-months group nerve fibres were seen in the dental papilla and the dental sac. Furthermore a significant increase in number size of the nerve fibres was noticed on the 4-months group, comparing with those of the 3-months group.

Animals↗