Transdentinal stimulation of reactionary dentinogenesis in ferrets by dentine matrix components.

OBJECTIVES: Trans-dentinal stimulation of reactionary dentinogenesis may be mediated through cellular signalling by bio-active components released from the dentine matrix during injury. Understanding of these processes will be important to guide dentinal repair activity following restorative surgery. The purpose of this study was to investigate the effects of implanting isolated dentine matrix proteins within cavity preparations on dentinal repair activity and odontoblast survival using a controlled experimental animal model. METHODS: Forty-five ferret canine teeth each had a standardised non-exposed cylindrical Class V cavity cut into the buccal dentine. Ten cavities were restored with zinc oxide eugenol, as a control. Two different lyophilised preparations of dentine matrix components were implanted on the axial floor of the remaining 35 cavities prior to filling with zinc oxide eugenol. After post-operative periods of 2, 7, 14, 28, and 90 days, the teeth were extracted and examined histomorphometrically and the data analysed statistically by analysis of variance tests. RESULTS: The odontoblasts beneath the restored cavities responded to the presence of the two dentine matrix preparations by increasing the mean area of reactionary dentine secreted by 433 and 578%, and the numbers of odontoblasts remained stable. CONCLUSION: Dentine matrix components can stimulate reactionary dentinogenesis in non-exposed cavity preparations. It will now be important to identify how this may be harnessed as a part of routine restorative surgery to optimise treatment outcomes with a biological basis.

Patient attitudes to over-the-counter drugs and possible professional responses to self-medication.

BACKGROUND: There is a paucity of research about patients' attitudes towards their doctor's recommending over-the-counter (OTC) remedies or about how patients respond to the doctor's suggestion to try an OTC remedy. OBJECTIVES: The aim of this study was to ascertain the attitudes of patients to OTC drugs. METHODS: 505 consecutive patients from each of six participating practices filled in a questionnaire. RESULTS: A total of 2765 (91.3%) patients responded. The responses from 2624 patients were from adults and are presented here. Based on the number of valid responses to each question, 53.8% of these patients were exempt from prescription charges, 55.1% took regular prescribed medication and 24.6% stated that they used OTC remedies regularly. There were generally positive attitudes to doctors enquiring about prior OTC use as well as to doctors making OTC recommendations in the consultation. However, patients expressed fairly negative attitudes towards pharmacists making generic substitutions and were even more hostile to the idea that pharmacists should make therapeutic substitutions. CONCLUSION: In conclusion, GPs should consider asking their patients regularly about their use of OTC medicines and also consider recommending OTC use if this is cheaper than FP10s. However, the public at present do not appear to be prepared for interventions by the pharmacist.

A review of near patient testing in primary care.

AIMS AND OBJECTIVES: The aim was to identify publications relating to near patient testing (NPT), the use of alternative delivery systems between laboratory and general practice, including electronic data interchange (EDI), and computerised diagnostic decision support (CDDS), in the primary care setting to answer the following questions. What is the availability of NPT for primary care? What evidence is available to support the clinical effectiveness of NPT? What evidence is available on the accuracy and reliability of NPT within primary care? What evidence is available on the cost-effectiveness of different NPTs? How may CDDS improve the effectiveness of NPT? What evidence is available that compares NPT and existing laboratory services? What evidence is available on the cost-effectiveness of EDI or alternative delivery systems? HOW THE RESEARCH WAS CONDUCTED: Eight databases were searched, and the bibliographies from relevant publications checked for completeness. Unpublished work and publications not included in the databases were obtained by personal contact with collaborators, and from a postal survey sent to heads of academic departments of general practice and clinical chemistry and to researchers active or interested in the field worldwide. Questionnaires were also sent to 150 commercial organisations. Publications that met agreed definitions and reported original data were included in the systematic review. Of the 1057 publications identified, 102 (92 related to NPT, eight to CDDS, and two to EDI) were passed to the reviewers for appraisal of validity. The limited amount of published research relating to any particular NPT prohibited meta-analysis. Scoring systems to assess the validity of evaluations were also difficult to apply. RESEARCH FINDINGS: A wide variety of NPT systems have been developed. In general, the quality of the methods reported in the literature was poor. The issue of patient convenience and acceptability has not been adequately addressed. No evaluations of alternative delivery systems met the review criteria. No studies have evaluated the telephone or fax machine as a means of reporting results. For EDI, the majority of papers were descriptive. EDI and alternative delivery systems are not a replacement for NPT when the provision of an immediate result might have an impact on the quality of care. EDI may have clinical and cost advantages over traditional means of communication, but this has not been evaluated. The advisory role of the laboratory can be supported by CDDS. The use of CDDS and NPT has not, however, been fully evaluated. Few economic analyses have been conducted, and most were simple cost analyses. There are insufficient data for conclusions to be drawn on the cost-effectiveness of NPT in primary care. RECOMMENDATIONS: FURTHER SYSTEMATIC REVIEWS: Subject-specific systematic reviews are required that include laboratory and secondary care studies, and consider the potential for altering current management and patient acceptability. Priority topics include: biochemistry profiles on desktop analysers; cholesterol testing; urinalysis for the diagnosis of urinary tract infection; anticoagulation control; NPTs for the identification of acute infection. (ABSTRACT TRUNCATED)

Influence of substrate nature and immobilization of implanted dentin matrix components during induction of reparative dentinogenesis.

The biological effects of isolated soluble dentin extracellular matrix components on the induction of reparative dentinogenesis in exposed cavities in ferret canine teeth have been shown to be blocked by immobilizing the extracellular matrix components on nitrocellulose or Millipore membranes during implantation. This contrasts with the picture of induction of odontoblast-like cell differentiation and reparative dentin deposition on existing insoluble dentin matrix of the exposure walls when the extracellular matrix components are implanted in lyophilized form. These data indicate the importance of an existing insoluble dentin matrix in providing a substrate to potentiate the growth factor-like activity of soluble isolated dentin extracellular matrix components in the induction of reparative dentinogenesis.

Odontoblast stimulation in ferrets by dentine matrix components.

The possible effects of isolated dentine matrix components on odontoblast secretory activity were investigated in vivo by implantation of lyophilized fractions of these components into cavities prepared in ferret canine teeth. After implantations as short as 14 days there was significant deposition of reactionary dentine by the odontoblasts beneath the cavity and this response increased in a non-linear manner with time of implantation. In contrast, control cavities lacking the dentine matrix components showed no evidence of reactionary dentine deposition. Examination of teeth at early periods of implantation (2 and 5 days) indicated that odontoblast death had not occurred as a result of the operative procedures and that the response was one of stimulation of existing odontoblasts rather than that of induction of a new generation of odontoblast-like cells. The mechanisms of odontoblast stimulation by the dentine matrix components remain to be elucidated, but could be mediated by growth factors within the dentine matrix preparations.

A study of the relationship among pulpal response, microbial microleakage, and particle heterogeneity in a glass-ionomer-base material.

This investigation was designed to study the pulpal responses to glass-ionomer base materials that differ in particle size distribution. The study was carried out according to the BSI (1980) recommendations for testing restorative materials in vivo. The base materials caused more pulpal inflammation than the control material, Kalzinol, although by an indirect mechanism. A significant association was demonstrated in the statistical model between bacterial presence within the experimental cavity and pulpal inflammation. The type of restorative material has no direct association with the degree of inflammation, although the model suggests that it exerts an indirect influence via its antibacterial properties, and hence its influence on microbial microleakage. The base material, with a heterogeneous particle distribution, was associated with greater bacterial microleakage. Particle size distribution, therefore, has some effect upon bacterial microleakage, but, because of its complex effect upon several physical properties of materials, further studies are indicated.

Pulpal response to two semihydrous glass ionomer luting cements.

This study compared the pulpal responses to two innovative semihydrous glass ionomer luting cements (STA and ZIN) with those previously obtained for a conventional anhydrous glass ionomer luting cement, Aquacem. ZIN contained zinc oxide in the formulation. The study was conducted according to the BSI (1989) recommendations for testing restorative materials in vivo. ZIN was associated with minimal pulpal changes and microbial microleakage, and differed little from the control material, Kalzinol. The pulpal response to STA was similar to that observed for Aquacem, but was associated with less microbial microleakage. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The closer that bacteria were to the pulp, the more severe was the ensuing inflammation.

Preliminary studies on the in vivo morphogenetic properties of dentine matrix proteins.

Two fractions of isolated noncollagenous extracellular matrix proteins from dentine have been implanted into the base of exposed cavities in ferret canine teeth. After sealing the cavities, reparative dentinogenesis was assessed histologically after 14 and 28 days as compared to control cavities. Reparative dentinogenesis was enhanced in the presence of these matrix proteins with evidence of tubular dentine along the walls of the exposure and on the cavity floor demonstrating the in vivo morphogenetic properties of the dentine matrix proteins.

In vivo morphogenetic activity of dentine matrix proteins.

Matrix proteins (EDTA-soluble and collagenase-released) from rabbit dentine have been demonstrated to show in vivo morphogenetic activity in exposed pulps of ferret canine teeth. In young adult ferrets, the reparative dentine resembled normal primary tubular dentine with odontoblast-like cells lining its formative surface. The reparative response in older animals was seen as osteo-dentine deposition. In both cases, the reparative response was characterized by its intensity within a comparatively short time period and also by the low grade or complete absence of any localized inflammatory response. Dentine matrix proteins implanted in exposed pulps of teeth provide a good experimental model for analysing the cell-matrix interactions and events taking place during odontoblast differentiation and dentinogenesis.

An in vitro study of the antibacterial and antifungal properties of an irreversible hydrocolloid impression material impregnated with disinfectant.

The difficulties associated with the disinfection of alginate (irreversible hydrocolloid) materials have resulted in the development of an irreversible hydrocolloid impression material impregnated with an antimicrobial compound, didecyldimethyl ammonium chloride. This investigation assessed the antibacterial and antifungal properties in vitro of this innovative irreversible hydrocolloid material by using the agar well technique. The microorganisms used were Pseudomonas aeruginosa, Streptococcus mutans, Streptococcus sanguis, Lactobacillus odontolyticus rodriguez, Actinomyces odontolyticus, mixed salivary organisms, and Candida albicans. The results showed an absence of activity against Pseudomonas aeruginosa. Varying degrees of antibacterial activity were exhibited against the other microorganisms. It is concluded that it is not know whether the limited antibacterial and antifungal effect demonstrated in this study is sufficient to prevent bacterial and fungal colonization of the impression surface in the mouth during clinical practice.

Pulpal response to an anhydrous glass ionomer luting cement.

This investigation was designed to study the pulpal responses to Aquacem, an anhydrous glass ionomer luting cement, and to compare the results with those previously obtained for a conventional glass ionomer luting cement, Chembond. The study was carried out according to the BSI (1980) recommendations for testing restorative materials in vivo. Aquacem caused more pulpal inflammation than the control material, Kalzinol, though by an indirect mechanism. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The type of restorative material has no direct association with the degree of inflammation, but the model suggests that it exerts an indirect influence via its antibacterial properties and hence its influence on microbial microleakage.

An in vitro study of the antiviral properties of an alginate impression material impregnated with disinfectant.

The antiviral properties of a new alginate impression material impregnated with a disinfectant (didecyldimethyl ammonium chloride) were evaluated in vitro against herpes simplex virus type I and poliovirus type I. The material was exposed to the virus suspension for periods of up to 60 min. The impregnated alginate material showed no clinically acceptable effect against either virus, although log reductions of 1.0 and 1.7 plaque-forming units of herpes virus were obtained after exposure to the material containing the disinfectant for 5 and 60 min, respectively.