Composition and particle size of mineral trioxide aggregate, portland cement and synthetic geopolymers

Objective: To describe the composition and particle size of Portland cement (PC) and geopolymers in comparison to mineral trioxide aggregate (MTA).Design: A quantitative, laboratory-based exploratory study.Setting: Schools of Dental Sciences and Physical Sciences, University of Nairobi; World Agroforestry Centre (ICRAF); Ministry of Mining, all in Nairobi, Kenya.Study population: Grey PC clinker, Kaolin, Fly ash (FA) and blast furnace (BF) slag, together with alkaline-activated aluminosilicates (AS) or geopolymers derived from them, were evaluated in comparison to two brands of MTA (MTA Cem and ProRoot MTA).Methods: The materials were characterized by x-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), graphite furnace atomic absorption spectroscopy (GFAAS) and fluoride ion selective electrode (FISE) for compositional analysis, and laser diffraction for particle size distribution analysis. Continuous data was subjected to analysis of variance (ANOVA) and Tukey’s post hoc test for hypothesis testing at α level of 0.05.Results: While MTA and PC comprised mainly of dicalcium and tricalcium silicate phases, geopolymers contained aluminosilicate phases such as quartz and mullite. Only FA contained fluoride (43.33μg/g, sd 5.77). There was no statistically significant difference in the composition of MTA and PC as determined by EDXRF except in the Bi (F-statistic=44.29, df=2, adjusted p<0.0001, difference=2.47, 95% CI 16.30, 33.14%wt) and Pb content (F-statistic=164.40, df=2, adjusted p=0.000, difference=1.74, 95% CI 1.43, 2.05%wt). There was no statistically significant difference in the mean particle size distribution of MTA, PC and geopolymers (D50 for PC = 12.46μm, sd 3.18, MTA = 7.23μm, sd 3.43, aluminosilicates = 12.74μm, sd 3.79, p>0.05).Conclusion: Composition of PC was similar to MTA while particle size of PC and geopolymers was similar to MTA

Selection of impression materials and techniques employed by dentists in Kenya

Objectives: The aim of the study was to determine the preferred impression material and impression recording technique employed by the dentists in Kenya for specific clinical procedures.Design: A descriptive cross sectional study.Setting: Dental clinics/institutions within Kenya.Participants: Dentists registered by the Medical Practitioners and Dentists Board as at 2015.Methods: A sample n=322 was randomly selected among the 1000 dentists registered in 2015. Data was collected using a pre-tested self-administered questionnaire that was distributed via online web-based survey monkey softwareand off-line by data collection assistants. Data was analysed using SPSS version 20 and Microsoft Excel 2013. Results were presented in tables, pie and bar charts.Results: Ninety seven dentists (30.1%) returned the questionnaires, 57 (58.8%) completed the hard copy version while 40 (41.2%) responded via the on-line tool. Majority of the respondents were males 52 (53.6%), 44 (45.4%) females while one dentist (1%) did not respond. Nearly half of the dentists 44 (46.4%) had 0-5 years clinical experience and a sizeable number 72 (74.2%) were general practitioners. Majority 56 (57.7%) considered availability, cost, ease of use and degree of accuracy in selecting impression materials (IM’s). The most commonly used (IM) was alginate whereas the least applied were polysulphide and vinyl siloxanether. Alginate was used in primary and final impressions of all procedures except border moulding, mostly in study model 88 (90.7%) and least in complete denture final impression 4 (4.1%). Addition and condensation cured silicones were preferred for fixed restoration impressions with majority 40 (41.1%) using single mix impression technique. One dentist used digital impression recording technique.Conclusion: Selection of (IM’s) is influenced by availability, cost, ease of use and degree of accuracy. Alginate and silicone impression materials were most utilised. The single mix impression technique was more popular while digital impression technique is yet to be widely embraced by dentists in Kenya

Selection of direct restorative and rooting filling materials by Kenyan dentists in 2014

Objectives: To establish the categories of direct restorative and root filling materials used by dentists in Kenya as well as the factors considered in their selection.Design: A descriptive cross-sectional study.Setting: Public and private dental practices in major towns in Kenya.Participants: Registered, practicing dentists in Kenya in 2014.Methods: Out of approximately 1000 dentists, a sample size of 384 was determined. Using stratified random sampling, respondents were selected from the former eight provincial administrative regions. Data was collected using a pre-tested selfadministered semi-structured questionnaire. Microsoft Excel 2013 was used for data analysis and presentation of results.Results: Eighty three filled questionnaires were returned. The preferred direct restorative materials were resin composites (RC)(33.2%), glass ionomer cements (GIC) (30.3%) and dental amalgam (DA) (29.9%);compomers had limited use (6.6%). In permanent dentition, the use of RC was 52.6%, mostly for anterior restorations (30.3%)while DA was 49%, mostly for posterior restorations (89.5%). In deciduous dentition, the use of GIC was 47.1% while that of compomerswas 21%. The most commonly used root filing material was Guttapercha(GP) (96.4%). Overall, site and type of cavity (22.5%) and material properties (19%) were considered during selection.Conclusion: Kenyan dentists have access to modem direct restorative and root filling materials. Although RC is used more frequently in permanent dentition, DA is still preferred for posterior restorations while GIC is used more frequently in deciduous dentition; further, majority use GP for root fillings