Sias Renier Grobler

A COMPARISON OF FLUORIDE RELEASE FROM VARIOUS DENTAL MATERIALS

OBJECTIVE The aim of this study was to determine, in vitro, the relative short- and long-term fluoride release from four resin-modified glass ionomers (Fuji II LC, Vitremer, Enforce & Advance), a polyacid-modified composite resin (Dyract compomer) and a bonding agent (OptiBond). METHODS All the materials were prepared as outlined by the manufacturers. Circular discs of the materials mentioned were suspended in water for up to 300 days and the non-cumulative 24-h fluoride release was determined potentiometrically at chosen times. RESULTS The amounts of fluoride released during the first day were Vitremer (1.46 micrograms mm-2), Advance (1.18 micrograms mm-2), Fuji (1.08 micrograms mm-2), Optibond (0.33 microgram mm-2), Dyract (0.31 microgram mm-2) and Enforce (0.15 microgram mm-2). After the second day the sequence changed slightly and remained approximately the same for the rest of the 300-day period. There was also an increase in the fluoride release during the 60-200-day period relative to the previous period. CONCLUSION In general the most fluoride was released by Advance and not by Fuji II LC or Vitremer. For most materials, fluoride is still released after 300 days. Furthermore, even a thin layer of bonding agent released a relatively high amount of fluoride (volume-wise the most) at the beginning. It is deduced that even the release of relatively low amounts of fluoride may result in significant concentrations of fluoride in a microleakage gap.

Antimicrobial activity of two South African honeys produced from indigenous Leucospermum cordifolium and Erica species on selected micro-organisms

BackgroundHoney has been shown to have wound healing properties which can be ascribed to its antimicrobial activity. The antimicrobial activity can be effective against a broad spectrum of bacterial species especially those of medical importance. It has also been shown that there is considerable variation in the antimicrobial potency of different types of honey, which is impossible to predict. With this in mind we tested the antimicrobial activity of honeys produced from plants grown in South Africa for their antibacterial properties on selected standard strains of oral micro-organisms.MethodsThe honeys used were produced from the blossoms of Eucalyptus cladocalyx (Bluegum) trees, an indigenous South African plant Leucospermum cordifolium (Pincushion), a mixture of wild heather shrubs, mainly Erica species (Fynbos) and a Leptospermum scoparium (Manuka) honey. Only pure honey which had not been heated was used. The honeys were tested for their antimicrobial properties with a broth dilution method.ResultsAlthough the honeys produced some inhibitory effect on the growth of the micro-organisms, no exceptionally high activity occurred in the South African honeys. The carbohydrate concentration plays a key role in the antimicrobial activity of the honeys above 25%. However, these honeys do contain other antimicrobial properties that are effective against certain bacterial species at concentrations well below the hypertonic sugar concentration. The yeast C. albicans was more resistant to the honeys than the bacteria. The species S. anginosus and S. oralis were more sensitive to the honeys than the other test bacteria.ConclusionThe honeys produced from indigenous wild flowers from South Africa had no exceptionally high activity that could afford medical grade status.

The relation between lead concentrations in human dental tissues and in blood

The purpose of this study was: (1) to measure the lead concentrations in various parts of the teeth (enamel, dentine and circumpulpal dentine) and in blood from individuals of a remote rural South African community; (2) to investigate any correlation between the lead concentrations in these various dental tissues and in blood; and (3) to estimate blood lead from the tooth lead concentrations reported in other studies. Primary teeth and blood were collected from 48 children and analysed by graphite-furnace atomic absorptiometry. The following median concentrations (expressed in mg/kg) of lead were found: blood, 0.025; enamel, 0.25; dentine, 2.04; circumpulpal dentine, 6.71. The tooth lead concentrations were similar to those from other studies from remote rural areas but comparisons of blood lead were not possible in the absence of previous data. Blood lead in other studies could be calculated from the ratios here reported.

The effect of honey on human tooth enamel in vitro observed by electron microscopy and microhardness measurements

Various fruit juices with relatively low pH are known to have erosive effects on human tooth enamel in a reasonably short time. Honey, also with a relatively low pH, could do the same, but scanning electron microscopy showed no erosion of enamel by honey over a period of 30 min, neither did Knoop microhardness tests show any deterioration of enamel structure. The absence of any effect could be only partially attributed to the calcium, phosphorus and fluoride levels in honey.

In vivo Spectrophotometric Assessment of the Tooth Whitening Effectiveness of Nite White 10% with Amorphous Calcium Phosphate, Potassium Nitrate and Fluoride, Over a 6-month Period

To clinically evaluate the effectiveness of Nite White 10% carbamide peroxide with amorphous calcium phosphate, potassium nitrate and fluoride over a 6-month follow-up period. Nite White was applied nightly for 14 days, according to the manufacturer’s instructions. The color of teeth 11 and 21 of twenty one subjects was measured with a spectrophotometer (L*; a*; b*). Subjects were instructed to take note of any tooth sensitivity and gingival irritation. For all three components (L*, a* and b*) statistical significant differences (p<0.05) in the values between base-line (pre-bleaching) and; after treatment, after 1-month, after 3-months as well as after 6-months were found (Wilcoxon Signed Rank Sum Test). Significant differences were also found amongst the ΔE*ab (0-14days) values and; ΔE*ab (0-1 month), ΔE*ab (0-3 months) and ΔE*ab (0-6 months). However, no significant differences were found between pairs of ΔE*ab (0-1 month), ΔE*ab (0-3 months) and ΔE*ab (0-6months). The decrease in ΔE*ab was the highest after 1 month (~30%). The highest decrease in L* was about 58% after 1 month. Over the 14-day treatment period tooth sensitivity was 24.5%. Conclusions: Nite White ACP demonstrated significant tooth-whitening (unit increase = 5.29) with a low tooth sensitivity (25%) probably due to the presence of amorphous calcium phosphate, potassium nitrate, and fluoride. The whitening effect decreased the most after one month and then maintained well even after a 6 month period (units 3.89). Clinical implications The product is a good tooth whitener with a color increase of about 5 units accompanied with a low sensitivity.

A modified dilatometer for determining volumetric polymerization shrinkage of dental materials

A modified mercury dilatometer is described where any change in the volume of the sample is registered every 0.5 s as a change of the mercury height in the capillary, which is measured electronically instead of by the naked eye. The device is relatively low in cost and enables measurements to be made on samples regardless of their shape or size. Four different light-curing dental materials - Amelogen (Ultradent Dental Products, South Jordan, UT, USA), Z250 (3M/ESPE, Minneapolis, MN, USA), Permaflo (Ultradent) and Filtec flow (3M/ESPE) - were initially tested. From the results it was concluded that with this modified dilatometer reproducible measurements, with a measurement error (residual standard deviation) of less than 0.027% and an average coefficient of variation of less than 1.22%, could be obtained. Thus, the instrument is particularly suitable for the study of light-curing dental resins.

Spectrophotometric assessment of the effectiveness of Opalescence PF 10%: A 14-month clinical study

OBJECTIVES To evaluate the effectiveness of Opalescence PF 10% just after treatment, at 6-month follow-up and at a 14-month follow-up period. METHODS Opalescence PF 10% was applied nightly for 14 days. The color of teeth 11 and 21 of 17 subjects were measured with a spectrophotometer (L*; a*; b*) before treatment, just after treatment (14 days), after 6 months and after 14 months. Subjects were instructed to take note of any tooth sensitivity. RESULTS For all three components (L*, a* and b*) statistical significant differences (p<0.05) in the values between base-line, after treatment (14 days later), after 6 months and after 14 months were found (Wilcoxon Signed Rank Sum Test). The decrease in L* was about 20% after 6 months and about 50% after 14 months. The a* value decreased approximately 14% after 6 months but was worse after 14 months than at the beginning. The b* value decreased the least with about 9% after 6 months and about 8% after 14 months. The decrease in DeltaE(ab)(*) was approximately 20% after 14 months. Less than 20% of the subjects experienced mild tooth sensitivity just after treatment. CONCLUSION Significantly whiter teeth were found after treatment as well as after a 6-month follow-up period. The whiteness/brightness (L*) decreased with approximately 50% after 14 months and the a* value with approximately 50% after 7 months, while the yellowness (b* value) remained even after 14 months. CLINICAL IMPLICATIONS The product is an effective tooth whitener resulting in only low tooth sensitivity. Re-bleaching could be done at about 14 months.

Blood lead levels of South African long-distance road-runners

Road runners are exposed to vehicular exhaust aerosols which are a major source of atmospheric lead pollution in those countries where lead additives are incorporated in petrol. The purpose of this study was twofold: the authors wished to determine the blood lead levels of South African road runners, and they wished to investigate the influence of various environments on such levels. Blood samples were obtained by the finger-prick technique and analyzed for lead by graphite furnace atomic absorption spectrophotometry. The results were analyzed statistically and compared with control samples from a selected urban nonrunning population and a remote rural population, respectively. The mean blood lead levels obtained were 20.1 micrograms/dl, 51.9 micrograms/dl, 45.8 micrograms/dl, and 53.00 micrograms/dl for the rural trainers, urban trainers, Two Oceans pre-race, and Two Oceans post-race samples, respectively. The mean level for the selected urban control was 9.7 micrograms/dl. The results suggest that road runners are exposed to increased lead inhalation and that atmospheric lead levels differ in urban and rural areas of South Africa.

Bioactive-Functionalized Interpenetrating Network Hydrogel (BIOF-IPN): A Novel Biomaterial Transforming the Mechanism of Bio-Repair, Bio-Adhesion and Therapeutic Capability – An In Vitro Study

The purpose of this investigation was to evaluate and report the in vitro performance of a few selected Bioactive- Functionalized Interpenetrating Network Hydrogels (BIOF-IPN); a novel biomaterial with a build-in mechanism of biorepair capacity, bio-adhesion and therapeutic capability. The study also evaluates the cytotoxicity of the newly developed material, and its ability to be used in the dental field. In this study, four bioactive-functionalized interpenetrating network hydrogels (BIOF-IPN) were prepared by dispersion of different therapeutic agents. The dentin bond strength is tested, the bio-adhesivity, modulus of elasticity and cytotoxicity of the materials were investigated, and the performance of the therapeutic-agents release profile, evaluated. The gels used in this study demonstrated excellent capacity in leading to high internal surface areas with low diffusional resistance. An increase in bond strength of the dentin treated with the BIOF-IPNs compared to the bond strength of the conventionally bonded teeth was indicated, and a significant increase in the modulus of elasticity observed. BIOF-INPs showed high adhesive force promotes binding to the negative surface of skin or dentin structure. It was found that chitosan alone increased the cell survival rate remarkably (113%) and its presence with naproxen and ibuprofen increased the cell survival rate [naproxen (93%), chitosan/naproxen (96.6%), ibuprofen (76.6%), and chitosan/ibuprofen (89.1%). The use of BIOF-IPNs has increased the time of the release of therapeutic agents, and protected the active ingredient from any type of free radical damage produced in and around the active site. Present results demonstrate the capability of the BIOF-IPNs to play an important role in the defense mechanism, and in the functional multidimensional restorative repair materials. The findings suggest that the new material would definitely find applications in functional dental composites and regenerative dentistry.

Insights into Functional Erythromycin/Antioxidant Containing Chitosan Hydrogels as Potential Bio-active Restorative Materials: Structure, Function and Antimicrobial Activity

Substantial data are available in the literature on the role of Reactive Oxygen Opecies (ROS) and antioxidants in disorders such as the inflammatory and in chronic immune mediated conditions such as rheumatoid arthritis. However, remarkably little information is available on the periodontal diseases, which show many of the pathological features of other chronic inflammatory diseases. The periodontal tissues also provide an ideal medium within which to study mechanisms of ROS mediated tissue damage and of antioxidant defense in response to bacterial colonization, through the non-invasive collection of GCF. Bio-adhesive polymers appear to be particularly attractive for the development of alternative etches free dentin bonding system with an added advantage of additional therapeutic delivery systems to improve intradental administration of therapeutic and prophylactic agents if necessary. Chitosan, which is a biologically safe biopolymer, has been proposed as a bio-adhesive polymer and are of continuous interest to us due to their unique properties and flexibility in broad range of oral applications reported by others and us recently. The objectives of this study is to evaluate the novel chitosan based functional drug delivery systems which can be successfully incorporated into “dual action bioactive restorative materials” containing common antibiotic such as erythromycin, krill oil, aloe and aspirin as commonly used antioxidant species. Methods: The novel hydrogels will be investigated with respect to the antioxidant capacity and drug release capacity of the tetracycline as well as erythromycin from the designer drug delivery system, the use of SEM imaging for the characterization of the surfaces and reactive features of novel materials with antimicrobial potential as well asuse of the newly designed materials as an effective adhesive restorative materials. Results: A continuous release of erythromycin, while maintaining antibiotic effects against the tested bacteria,for at least 24 hours was shown from designer chitosan-antioxidant hydrogels. The increase antioxidant capacityof the designer material, significant antimicrobial capacity as well as adhesive dentine bond strength make thechitosan-containing restorative materials suitable and potentially advantageous materials for restorative andperiodontal applications in-vitro. The addition of antioxidants to the functionalized restorative material acts as aalternative free radical defense mechanism and therefor increases the shear bond strength teeth by managing theexcess of free radicals produced during common restorative procedure. Future investigations are necessary tovalidate this hypothesis.