Border Cave and the beginning of the Later Stone Age in South Africa

The transition from the Middle Stone Age (MSA) to the Later Stone Age (LSA) in South Africa was not associated with the appearance of anatomically modern humans and the extinction of Neandertals, as in the Middle to Upper Paleolithic transition in Western Europe. It has therefore attracted less attention, yet it provides insights into patterns of technological evolution not associated with a new hominin. Data from Border Cave (KwaZulu-Natal) show a strong pattern of technological change at approximately 44-42 ka cal BP, marked by adoption of techniques and materials that were present but scarcely used in the previous MSA, and some novelties. The agent of change was neither a revolution nor the advent of a new species of human. Although most evident in personal ornaments and symbolic markings, the change from one way of living to another was not restricted to aesthetics. Our analysis shows that: (i) at Border Cave two assemblages, dated to 45-49 and >49 ka, show a gradual abandonment of the technology and tool types of the post-Howiesons Poort period and can be considered transitional industries; (ii) the 44-42 ka cal BP assemblages are based on an expedient technology dominated by bipolar knapping, with microliths hafted with pitch from Podocarpus bark, worked suid tusks, ostrich eggshell beads, bone arrowheads, engraved bones, bored stones, and digging sticks; (iii) these assemblages mark the beginning of the LSA in South Africa; (iv) the LSA emerged by internal evolution; and (v) the process of change began sometime after 56 ka.     

Dynamics of potassium and nitrate ions release from polycarboxylate cement with 5% KNO3

Release of potassium and nitrate ions from polycarboxylate-cement blocks containing 5% KNO3, with different exposure in extragent aqua redestillata was studied. Using flame photometry we found increased concentration of eliminated potassium ions into the extragent after the 24th hour (0.90 +/- 0.03 mg/cm3) while the maximum quantity of released potassium ions was measured after the 14th day (336 h)--1.50 +/- 0.02 mg/cm3 (t = 60, P < 0.001). The concentration of the released nitrate ions was determined by spectrophotometry at l = 410 nm. The degree of extraction of nitrate ions from the model cement blocks progressively increased with time, but their concentration in the cement decreased after the 14th day too, demonstrating a statistically significant difference: from 4.50 mg on the 20th minute to 2.60 mg on the 14th day (t = 115, P < 0.001).     

Early clinical results from the use of 5% potassium nitrate in polycarboxylate cement for biological treatment of reversible pulpitis

The aim of the present study was to obtain immediate and early clinical results from the use of 5% potassium nitrate (KNO3) in polycarboxylate cement for biological treatment of reversible pulpitis. MATERIAL AND METHODS: The method was applied in 140 teeth, mostly premolars and molars, with a clinical diagnosis of reversible pulpitis and indications for biological treatment of the inflamed dental pulp by means of indirect pulp capping. All teeth had clinically healthy periodontium and no non-carious lesions of the hard dental tissues. The study sample consisted of 127 patients aged between 16 and 40 years. The control group included 92 teeth in 78 patients, which were treated by a calcium hydroxide liner. The follow-up examinations were conducted 24 hours after treatment and on day 3 for the immediate results, and on days 7, 14, 30, and 90 for the early clinical results assessing the functional condition of the teeth, presence of thermal stimulus-induced pain and the measurements from the electric pulp vitality tests. The results were analysed with the analysis of variance and graphic analysis. RESULTS: The immediate and early clinical results of the biological treatment of reversible pulpitis with 5% KNO3 in polycarboxylate cement show that pain as a symptom of the initial inflammatory process in the dental pulp is rapidly and effectively relieved, leaving the treated teeth in good functional condition. The comparison of the measurements from the electric pulp tests of all teeth reveals a statistically significant difference (u = 8.51; P < 0.001) in favour of the group treated with potassium nitrate and polycarboxylate cement. CONCLUSIONS: 1. The immediate and early clinical results of our study suggest that treating reversible pulpitis with 5% KNO3 in polycarboxylate cement has an a very good analgesic action 2. The normal electrical excitability of the treated teeth is restored faster than that in the teeth treated by calcium hydroxide-based materials (P < 0.001).     

Sorption of Hydrophobic Compounds by Modified Poly(ethylene oxide) Networks

Various flocculates were prepared by irradiation and chemical modification of poly(ethylene oxide). It was found that the amphiphilic hydrogels are efficient for purification of waste waters and water‐organic systems contaminated with dyes and pigments, even at low concentrations (0.035–0.1 wt.‐%) of the polymeric PEO network flocculates. The affinity of the modified networks for ionic and nonionic species was studied as a function of the structure and crosslinking density of the networks, their degree of quaternization, and their hydrophilicity coefficients. It was established that hydrophobic organic compounds such as sodium picrate and bromophenol blue are bound predominantly to the lipophilic quaternary ammonium cations. The polyether chains remain inert (in the case of nonionic dyes) or form complexes with the alkali cations (in the case of sodium picrate). It was also found that the microenvironment of the active site (quaternary N⁺ ion or EO segment) affects the sorption ability of the modified networks.     

Comparative in vitro study of pulp capping materials

AIM: In a comparative in vitro study we examined the bactericidal effect, adhesion and shrinkage of 5% potassium nitrate in Carboxy-Adhaesor, 5% potassium chloride in Carboxy-Adhaesor, Carboxy-Adhaesor, Adhaesor and Dycal. MATERIAL AND METHODS: The bactericidal effect of the investigated pulp capping materials on the isolated microorganisms Staphylococcus aureus, Staph. epidermidis, Streptococcus viridans alpha-haemolyticus, Streptococcus pneumoniae and Streptococcus beta-haemolyticus was assessed by the diffusion method around each disk in mm. The adhesion and shrinkage were assessed after hardening of the material. RESULTS: The results obtained showed higher bactericidal activity of polycarboxylate cements in comparison to Adhaesor and Dycal. The largest zone of inhibition was found around the disks with polyacrilic acid, followed by 5% KNO3 in polyacrilic acid, 5% KCl in polyacrilic acid; significantly smaller is the zone around Dycal. The difference was statistically significant (p<0.01). The adhesion and shrinkage of polycarboxylate cements were estimated as very good, better than those of Adhaesor and Dycal. CONCLUSION: The bactericidal effect of 5% KNO3 in polycarboxylate cement is very good for the microorganisms isolated from deep caries. The adhesion to hard tissues is very good, which suggests good marginal adaptation to the cavity.     

Prevalence, awareness, treatment and control of hypertension in a working Bulgarian population

Arterial hypertension is a major risk factor for coronary heart disease and stroke mortality. Few data exist on prevalence, awareness, and management of hypertension in Bulgaria, precluding development of potentially beneficial risk reduction initiatives. Between September 1996 and July 1997, an age-sex stratified sample of 847 male and 771 female employees (age 18–64 y) of the national transport industry resident in Sofia was recruited during their annual physical examination. A structured interview was conducted and resting blood pressure (BP) measured. Prevalence: Elevated BP (mean of two consecutive readings SBP 140 mmHg and/or DBP 90 mmHg) was observed among 24% of women and 58% of men (p < 0.001). Prevalence increased with age in both men and women. Awareness: Among 722 employees with elevated BP, 49% of women and 33% of men (p < 0.001) reported history of hypertension. Awareness increased with age. Management: Among 345 employees with history of hypertension, 37% of women and 36% of men (p > 0.05) reported taking antihypertensive treatment. The proportion under management increased with age. Control: Normal BP was measured in only 6% of men and 7% of women taking antihypertensive medication (p > 0.05; no consistent trends by age). Elevated BP is widespread and hypertension is underdiagnosed and poorly controlled in this urban working-age Bulgarian population, especially among those under 40 y. This may contribute to the high rates of coronary heart disease and stroke incidence and mortality in Bulgaria.     

Situational analysis of the type and degree of resorption of the interdental septum of teeth with approximal amalgam restorations

AIM: The aim of the study was to determine radiographically the type and degree of resorption of the interdental septum of teeth with approximal amalgam restorations in various iatrogenic clinical situations. METHODS: Situational analysis of the type and degree of resorption of the interdental septum was performed in 757 approximal amalgam restorations of Class II cavities (according to Black). Intraoral periapical retroalveolar radiographs were used for that purpose. The condition of the septum was investigated in restorations with correct shape, in restorations with a poorly restored anatomical form, unsatisfactory marginal adaptation, as well in restorations with no proximal contact with the adjacent tooth. RESULTS: The horizontal type of interdental septum resorption was the predominant type in all study groups. Restorations with poor anatomical form showed considerably higher incidence of vertical type of resorption in comparison with correctly shaped fillings. Similarly, restorations with unsatisfactory marginal adaptation demonstrated higher incidence of the disproportionate type of resorption than in the accurately formed group. A greater degree of resorption of the interdental septum was observed in restorations with incorrect anatomical form, with unsatisfactory marginal adaptation and with no contact with the adjacent tooth. CONCLUSION: The observed changes can be explained by the presence of significant, long-standing retention of bacterial plaque, as well as by the additional trauma caused while eating and maintaining personal oral hygiene.     

Clinical results of potassium nitrate use in polycarboxylate cement for biological treatment of reversible pulpitis

To determine effectiveness of indirect pulp capping with 5% potassium nitrate in polycarboxylate cement for biological treatment of reversible pulpitis, a clinical study of 232 teeth with active caries lesions from 205 healthy patients aged from 16 to 40 years was performed. They were divided into 2 groups: the study group--140 teeth of 127 persons with 5% potassium nitrate in polycarboxylate cement (Carboxy Adhesor); control group--92 teeth of 78 persons with calcium-hydroxide cement (Dycal). Short-term clinical results showed better desensitizing effect and faster recovery to normal values of electric vitality in teeth treated by potassium nitrate in comparison with Dycal lining (p<0.001). Long-term follow-up (up to 2 years) showed good functional conditions, preserved vitality and x-ray status of the treated teeth.