Biomedical subjects

J Orstavik

Publications and source records attributed to J Orstavik.

14 recordsLinked to original sources

PubMed1991

A method for testing denture adhesives.

An in vitro test method is described simulating the in vivo fate of a denture adhesive, i.e., destruction of the adhesive, dilution, and dissolution, by measuring the bond strength for the adhesive placed between acrylic resin plates. Between each measurement, the adhesive was exposed to isotonic saline. The bond strength for two ointment denture adhesives, Super Corega and Fixodent, was measured and the results were compared with those obtained for one of them in a previous in vivo test. The test method described for denture adhesives seems useful to depict the fate of a denture adhesive in clinical use.

Adhesives↗

PubMed1991

In vivo and in vitro studies on soft denture materials: microbial adhesion and tests for antibacterial activity.

The microbiological properties of four tissue conditioners, one soft liner, and one acrylic resin were studied. The tissue conditioners showed no or negligible antimicrobial effects toward salivary microorganisms by two different in vitro tests. In in vitro adhesion experiments, more Streptococcus mutans and Candida albicans adhered to the tissue conditioners and the soft liner in comparison with conventional acrylic resin used for denture-base fabrication. No difference in bacterial adhesion was found among the tissue conditioners. The microbial colonization of two tissue conditioners lined on maxillary dentures in three volunteers was followed for 14 days. No difference among the materials was found, but a tendency for subject-dependence in plaque formation on the materials was noted.

Acrylic Resins↗

PubMed1991

Parotid salivary flow rates in two patients during immediate denture treatment.

Parotid salivary flow rates in response to chewing or citric acid stimulation were studied in two patients who had their last maxillary teeth extracted and immediately replaced with complete dentures. The patients were monitored 6 months from the last week before extraction. Parotid salivary flow rate in response to chewing was increased after insertion of the denture. For one of the patients a particularly high output from the parotid gland was found 2 weeks after treatment. Throughout the experiment, parotid salivary flow was higher on the chewing side than on the contralateral side. At the end of the experimental period the dentures were relined. Salivary flow measured immediately after relining was lower than prior to this procedure. An increased salivary response was also observed during citric acid stimulation after transition from the dentate to the denture wearing state. This increase was more marked if the patients had their dentures in situ when the gustatory provocations were performed. It is concluded that parotid salivation increases during masticatory and gustatory stimulation in patients subjected to total extraction and immediate complete denture treatment, and that the presence of a complete denture per se appears to act as an additional mechanical stimulus in the salivary reflexes.

Citrates↗

PubMed1991

The masseteric reflex evoked by tooth and denture tapping.

The characteristics of the masseter reflex evoked by tapping a maxillary incisor were compared with the reflex pattern evoked by tapping a corresponding denture tooth after insertion of an immediate denture. Up to three inhibitory phases (I-1, I-2 and I-3), followed by excitation, were found on an averaged EMG. The tapping force threshold for the early inhibitory phase was lower than for the late phases. The pattern of the reflex was generally the same before and after insertion of the denture, but the threshold values increased. After insertion of the denture, the threshold for I-1 increased from 1 +/- 0.3N to 2.2 +/- 0.4N, the threshold for I-2 increased from 2.4 +/- 0.8N to 3.8 +/- 0.9N, and the threshold for I-3 increased from 5.1 +/- 0.6N to 8.3 +/- 0.9N. The latency period for I-1 also increased from 12.3 +/- 0.5 ms to 13.1 +/- 0.3 ms after insertion of the denture. After relining, the threshold for evoking I-1 decreased from 2.7 +/- 1.2N to 1.2 +/- 0.6N. It was assumed that the mechanoreceptors situated in the mucosa under the denture base could take over the functional role of the periodontal mechanoreceptors for evoking the masseter reflex during tapping, and that these afferents probably had connections to the same interneurones.

Denture, Complete↗

PubMed1991

[What happens to patients referred for implant evaluation? Treatment choice and patient response].

Case histories of patients referred to a university clinic for evaluation/treatment with implants were studied, regarding recommended and actually performed treatment. Patient reactions after treatment with conventional methods were also recorded. Three main groups attended: 1) Elderly, unsatisfied complete denture wearers. 2) Patients with few remaining teeth and an aversion against removable dentures. 3) Young patients with single teeth missing in an otherwise healthy dentition. Fifty-seven per cent of edentulous patients were recommended correction/replacement of their conventional full denture. Three out of four followed the recommendation. For jaws with a severely reduced dentition conventional prosthetic alternatives were advocated in 80 per cent of the cases. Corresponding treatment was carried out in 57 per cent of the cases, prosthetic appliances differing substantially from the suggested alternative in 26 per cent, and 17 per cent received no prosthetic treatment. Only few jaws required single tooth replacements. Every second patient who had this complete denture corrected or remade, considered implant therapy then superfluous. All complicated cases with extensive tooth loss were treated to the patients satisfaction, without using implant support, provided the treatment was referred to a colleague with specialist training. Forty per cent of similar cases remitted to their general practitioner did not receive any prosthetic treatment at all.

Adolescent↗

PubMed1990

[New experimental procedures in adult orthodontics].

This presentation discusses a new approach to preprosthetic orthodontic treatment of adult patients with missing anterior teeth. The basic idea is: Prosthodontic appliances with high and lasting esthetic qualities are difficult to obtain in the anterior region. Our alternative is to close anterior gaps by orthodontic treatment, if necessary combined with recontouring of individual crowns by means of grinding and/or light-cure resin buildup. Spaces needing prosthetic closure are transferred to more posterior regions of the dental arch, usually in the premolar region. Different aspects of this new approach has been presented and discussed. The material is derived from a clinical study currently in progress at the departments of orthodontics and prosthetics at The Dental Faculty in Oslo.

Adult↗

PubMed1976

In vitro attachment of Streptococcus sanguis to dental crown and bridge cements.

The ability of a common dental plaque bacterium, Streptococcus sanguis, to adhere to dental crown and bridge cements in vitro was investigated. Cylindrical blocks of five different commercial brands of cement, with and without acquired pellicles, were indubated with buffer suspensions of S. sanguis for 1 h. Attached bacteria were counted under the microscope. S. sanguis had particularly high affinity for uncoated resin cement. In contrast, the carboxylate cement tested was a poor substrate for the adherence of this bacterium. The other cement types (zinc phosphate, zinc oxide and silico-phosphate) had intermediary qualities as adhering surfaces. The presence of an acquired pellicle, obtained by pretreatment with saliva, influenced the initial adherence of bacteria to cement in vitro. On the resin cement a salivary pellicle strongly suppressed the bacterial adhesion. For the zinc phosphate, zinc oxide and silico-phosphate cements a pellicle slightly enhanced the attachment of S. sanguis. On the carboxylate cement only few organisms attached also after pretreatment with saliva.

Cell Count↗

PubMed1976

Cytotoxicity of temporary crown and bridge materials.

In vitro cytotoxicity of freshly prepared temporary crown and bridge materials was studied using mouse fibroblasts prelabelled with 3H-thymidine grown in shake flask cultures. Cytotoxicity was measured as (1) lack of cell multiplication, (2) stainability with Trypan blue and (3) release of 3H-labelled material to the culture medium. All the materials tested (zinc oxide-eugenol cement (ZOE), Scutan and Sevriton) were cytotoxic in this system, ZOE most strongly. This finding favours the view that the in vitro cytotoxicity of dental materials should not be used alone as a screening test for their biological compatibility under clinical conditions since clinical experience and previous in vivo findings have established that ZOE is biologically well tolerated by the dental tissues.

Animals↗

PubMed1974