Marginal and apical bone stability after staged sinus floor augmentation using bone condensing implants with variable-thread design: a two-dimensional analysis.

Studies on the vertical stability of augmented bone after sinus lifting differ substantially. In addition, long healing periods are usually advocated prior to implant installation. The purpose of this case series study was to evaluate the changes in bone height after sinus lifting with a bovine-derived xenograft and to evaluate the clinical outcome of bone condensing implants installed after a short healing period. Patients treated during the years 2010-2013 were re-examined using peri-apical radiographs to evaluate the changes in augmented bone height (BH) and marginal bone loss (BL). Fifty-seven of 70 eligible subjects (28 male and 29 female, mean age 56 years) attended for reassessment. Data were available for 53 sinus lifts and 105 implants installed after a mean healing period of 4.6±1.5 months. Implant survival was 99% after a mean time in function of 19±9 months. Baseline BH, BH at implant placement, and final BH were on average 3.87±1.74mm, 13.75±2.12mm, and 13.11±2.12mm, respectively (P<0.001). Mean BL was 0.51±0.65mm. Only limited resorption is to be expected after sinus lifting in the short term. A bone condensing implant can be used in the early healing phase with successful outcomes in terms of implant survival and bone adaptation.

Microhardness changes in surface enamel after application of bioadhesive fluoride tablets in situ.

The effect of fluoride released by bioadhesive tablets was evaluated in an in situ model in human volunteers. Eight volunteers carried four to six polished human enamel samples in a lower lingual device for a period of 5 days without fluoride supplements (control) and 5 days using one bioadhesive tablet (0.5 mg F) per day, placed in the lower buccal sulcus. Changes in mineral content were measured in terms of surface microhardness indentation length (load 0.98 N, Knoop diamond indenter). Some enamel samples were analyzed for their fluoride content by means of a surface etch biopsy. The indentation length increased significantly in both experiments, but demineralization was less pronounced with fluoride (indentation length increased from 44 +/- 7 to 48 +/- 13 microns) than in the control (44 +/- 7 to 58 +/- 13 microns). The fluoride concentration and the amount of calcium in the acid etch biopsy specimens of the enamel samples did not differ significantly between the two groups. Bioadhesive, fluoride-releasing tablets have therefore demonstrated the potential to reduce demineralization by elevating salivary and plaque fluoride concentration for a period of several hours. This self-administered device can be a supplementary means for prevention of caries.

Rehardening of surface softened and surface etched enamel in vitro and by intraoral exposure.

The rehardening of surface-softened and surface-etched enamel was investigated in vitro and by intraoral exposure. Surface-softened enamel was obtained by treatment with 0.1 M acetic acid buffer solution (pH = 5.5) for 3 h. Surface-etched enamel was obtained by the acid etch procedure used in clinical situations (37% phosphoric acid gel, 30 s). The enamel lesions were treated in vitro, with calcifying solutions for 8 h or were carried for 48 h in an intraoral appliance. Changes at the enamel surfaces were investigated by surface microhardness measurements. Following the treatment with calcifying solutions a significantly greater indentation length was observed in surface-etched than in surface-softened enamel. No significant difference in indentation length between both types of enamel lesions was observed following intraoral exposure. It was concluded that the initial rate of rehardening between both types of enamel lesions is comparable. At his stage remineralization occurs in microspaces created in the slightly destroyed enamel structures. The influence of the etch pits on the indentation length becomes dominating when remineralization continues. An obliteration of etch pits was observed in enamel samples treated with the calcifying solution with the highest degree of saturation. It was suggested that freshly prepared highly supersaturated calcifying solutions can be used to enhance mineral appositions in accidental etch pits.

[The use of human dental enamel as an indicator of the extent of environmental pollution]. / Utilisation de l'émail dentaire humain en tant qu'indicateur du degré de pollution environnementale.

Acid etch surface enamel microbiopsies were taken from permanent teeth of schoolchildren and analyzed for lead and cadmium using electrothermal atomic absorption spectrometry. A comparison concerning these heavy metals was made between children (7 and 12 years) from a school close to a non-ferrous metal plant and children from the same age group from a school situated near the same plant but in a less polluted zone. The lead concentrations in enamel biopsies from the first group were significantly higher than those from the second group. Cadmium shows the same trend but on a much lower level. A significant correlation between lead and cadmium was also found in both groups.

[In vivo evaluation of the level of lead in human superficial enamel using a double biopsy]. / Evaluation in vivo du profil du plomb dans l'émail superficiel humain par double biopsie.

Two successive acid etch biopsies were performed on the permanent maxillary right central incisors of two age groups of children resident in an urban area in Belgium. Lead was determined in the biopsy solutions and the concentrations were related to etch depths, which were calculated from the calcium and phosphorus concentrations in the biopsy solutions. The mean lead concentration in the first enamel biopsy layer was five times higher than in the second biopsy. A strong correlation was observed between the two biopsies. It was shown that calibration of the lead values with respect to etch depths and Ca/P ratio was desirable and that a robust regression analysis approach was needed instead of classical more reliable calibration. In this study no age related increase in the surface enamel lead concentration could be demonstrated. Therefore, it was concluded that for these children the presence of lead in surface enamel had to be attributed primarily to pre-eruptive uptake.

[The use of fluoride from the viewpoint of toxicology and ecology]. / L'utilisation du fluor du point de vue toxicologique et écologique.

Although the effectiveness of fluoride against dental caries seems to be established, criticism about its safety has never ceased. Its dual role as a (potentially beneficial) drug as well as a (potentially malignant) environmental pollutant have contributed to this controversy. Although Belgium does not allow the fluoridation of drinking water, many sources of air and water contamination exist due to industrial activities. The role of the dentist is to know about these regional fluoride sources when prescribing fluoride for caries control in order to obtain an optimal effect together with maximum safety.

Load dependency and reliability of microhardness measurements on acid-etched enamel surfaces.

The load dependency of hardness measurements was investigated on sound and demineralized enamel samples. For all samples investigated, the Knoop hardness number (KHN) varied as a function of the applied load. Higher loads enhanced indenter penetration into the test surface. The variation in KHN values observed in demineralized enamel, both surface-softened and surface-etched, was explained by a decrease in porosity as a function of depth. The reading error for indentations made on surface enamel etched with 37% phosphoric acid gel for 30 s was found to be slightly elevated compared to indentations made on a polished sound enamel surface. It was concluded that the surface microhardness technique can be used for the longitudinal investigation of etched surface enamel.

Comparison of salivary fluoride concentrations after administration of a bioadhesive slow-release tablet and a conventional fluoride tablet.

The in-vitro and in-vivo fluoride release of bioadhesive, slow-release tablets prepared from a mixture of polyethylene glycol polymers, containing 0.1 mg of fluoride as NaF was studied, and their ability to sustain fluoride levels in saliva were compared with conventional fluoride tablets with the same fluoride content. In-vitro release experiments showed that the bioadhesive tablets needed 8 h to release all their fluoride compared with less than 1 h for the conventional fluoride tablets. In-vivo, the bioadhesive tablets had a retention period of 6 h and could sustain a salivary fluoride level of more than 10 microM above the baseline for 7 h. The conventional fluoride tablets achieved a peak concentration of 0.5 mM directly after dissolution in the mouth, but the fluoride level could not be sustained for longer than 1 h. A good agreement was found between the in-vitro swelling behaviour of the bioadhesive tablets and their in-vitro and in-vivo release characteristics and their in-vivo retention time.

[Prevention of alveolar bone loss]. / Prévention de la perte osseuse alvéolaire.

This article describes the bone resorption and remodeling of the edentulous jaw, starting right after extraction of teeth. This resorption is a physiological process, but can be influenced by wearing dentures. Load on the mucosa and disturbed blood circulation of the mucosa caused by the denture gives an additional bone resorption. The prevention of bone resorption can be executed in saving teeth or roots as long as possible. But when the jaw is already edentulous it is necessary to create an optimal function and load-dividing of the denture and regular controls are indicated. From time to time the denture has to be rebased or relined due to the changes in contour of the jaw. Also a daily massage of the mucosa after cleaning the denture is advisable to restore a normal blood circulation.

[Fluoride concentration in drinking water in small villages in the Cape province]. / Die fluoriedkonsentrasie in die drinkwater van kleiner dorpe in die Kaapprovinsie.

The purpose of the study was to update existing tables on the fluoride content of drinking water and thereby help curb its fluoride overdose from the use of fluoride containing tablets. The fluoride concentration in the drinking water of 57 villages in the Cape Province was determined by a combination fluoride ion selective electrode. This investigation showed that the number of available water sources decreased as follows: boreholes greater than dams greater than fountains = canals. Furthermore, boreholes contained more fluoride in the drinking water than fountains, dams or canals (p less than 0.10). Five out of 41 boreholes have less than or equal to 0.10 parts per million (ppm) fluoride in the drinking water, while 17 out of 26 dams, 4 out of 13 rivers and 3 out of 5 fountains and canals contained less than or equal to 0.10 ppm fluoride.

Relation between lead in surface tooth enamel, blood, and saliva from children residing in the vicinity of a non-ferrous metal plant in Belgium.

Two groups of schoolchildren between seven and 12 years old residing in the vicinity of a non-ferrous industrial plant and exposed to lead (Pb) at a concentration that could cause health problems, were monitored. Concentrations of Pb in blood (blood-Pb), which were determined at regular six monthly intervals, were related to the Pb concentrations in surface tooth enamel (enamel-Pb). Acid etch biopsy samples of surface enamel were taken at the end of the five year study period in the first group (A) and after two years in the second group (B). Salivary Pb (saliva-Pb) concentrations were determined for the first study group on the same day that the enamel biopsies were performed. Calibration of the data was necessary--that is, blood-Pb concentration with respect to age and sex and enamel-Pb concentration with respect to etch depth and age. The blood-Pb concentrations declined with time. Surface enamel Pb concentrations correlated with blood-Pb concentration for the period starting with the pre-eruptive development of the incisors, related to blood-Pb concentration for a long time, and corresponded partly to the exposure at the time of pre-eruptive development and/or eruption. Through the correlation with enamel-Pb concentration, the seasonal behaviour of blood-Pb concentration became apparent. Saliva-Pb concentrations related to blood-Pb concentrations only in the short term.

Acid-etched enamel surfaces after 24 h exposure to calcifying media in vitro and in vivo.

The remineralization of acid-etched enamel lesions is investigated in this study both in vitro and in vivo over periods of 24 h. In an initial study, samples of etched bovine enamel were subjected in vitro to treatment with synthetic calcifying solutions, or were exposed to saliva by means of an intraoral appliance. Alterations in hardness of the enamel surface were measured by indentation techniques. In a second study the suitability of an impression technique for investigating the surface relief induced by an acid-etch procedure was investigated. Extracted human incisors were used to make SEM observations of eteched areas and corresponding sections of impressions. Subsequently, six subjects were selected for a clinical evaluation of the impression technique. Although a significant decrease in indentation length (increase in hardness) was observed for etched enamel lesions treated with calcifying solutions in vitro, no evidence for any such change was observed in samples exposed to the influence of saliva when investigated by the indentation and impression techniques.

Development and testing of bioadhesive, fluoride-containing slow-release tablets for oral use.

The bioadhesive characteristics of tablets for oral use made from modified starch, polyacrylic acid (PAA), polyethylene glycol (PEG) and sodium carboxymethylcellulose (CMC) were investigated. Adhesion force and energy were determined in-vitro and maximal adhesion time was evaluated in-vivo in human subjects. In-vitro, PAA showed the best bioadhesive properties, followed by modified maize starch and PEG with a mol. wt of 300,000-400,000 daltons. The presence of 0.1 mg of fluoride as NaF did not lead to significant differences in adhesion force and energy for the same formulation. The in-vivo bioadhesion was not strongly correlated to the in-vitro data. PAA, despite its excellent adhesion, proved to be irritating to the mucosa. PEG with a mol, wt of 200,000 daltons was subject to erosion. CMC showed good bioadhesive properties but the mechanical strength of the tablets was low. Modified maize starch tablets containing 5% (w/w) PAA and PEG with a mol. wt of 300,000 daltons proved to be the most suitable formulations for a fluoride-slow-release tablet with bioadhesive properties. In-vitro, the tablets released all of the fluoride within the 8 h period, with a high initial release. The release rate was related to the water absorption rate of the tablets. The PAA-containing formulations and the CMC formulations had the fastest release. In-vivo, fluoride levels with a minimum of 150 and a maximum of 1000 micrograms mL-1 were maintained for 8 h in the oral cavity. These fluoride levels were sustained significantly longer than those obtained with the administration of fourfold the amount of fluoride in the form of a fluoride-containing toothpaste. The release characteristics in-vivo exhibited a high variation. The use of bioadhesive polymers in oral pharmacotherapy seems promising.

A comparative study of the lead and cadmium content of surface enamel of Belgian and Kenyan children.

Acid etch surface enamel microbiopsies were performed on teeth from 378 children aged 6-12 years; 318 of the children lived in Belgium, an industrialized country, and 60 lived in a rural part of Kenya. In addition to lead and cadmium, calcium and phosphorus were also quantitatively determined in the etch solutions. Calcium was chosen as an internal reference for the expression of the lead and cadmium concentrations and for the assessment of the etch depth. The mean lead level in surface enamel of the Belgian children was approximately eight times higher than that of the Kenyan children. The cadmium levels were not significantly higher. An appropriate regression model taking into account differences in etch depth showed that a significant decrease of lead and cadmium with etch depth occurred and that a significant correlation between lead and cadmium in surface enamel existed for the Belgian cohort. Moreover, the same mean calcium/phosphorus ratios were obtained for the Belgian and Kenyan surface enamel samples, and were found not to play a significant role in the calibration of the lead and cadmium levels.

Study of lead and cadmium content of surface enamel of schoolchildren from an industrial area in Belgium.

The amount of lead and cadmium was determined in surface enamel from permanent teeth of schoolchildren by means of an acid etch surface enamel microbiopsy method. Lead and cadmium levels were calculated on the amount of etched enamel. A comparison of the concentrations of these heavy metals was made between children (7 and 11 yr) from a school close to a non-ferrous metal plant and children from the same age group from a school situated nearby the same plant but in a zone polluted to a lesser degree. The lead concentrations in enamel biopsies from the first group were significantly higher than those from the second group. Cadmium shows the same trend but on a much lower level. A significant correlation between lead and cadmium was also found in both groups.

Model for assessment of lead content in human surface enamel.

Acid etch surface enamel microbiopsies were taken in vitro and in vivo and analyzed for lead using electrothermal atomic absorption spectrometry. The in vitro samples were obtained from subjects resident in an urbanized region in Belgium or from a region close to a nonferrometal industrial plant. The smaller set of in vivo samples were all from subjects resident in an urbanized region. Using a regression tree approach it was possible to identify in a stepwise manner factors that contributed to the variation of lead in the samples. For the in vitro as well as in vivo samples, the etch depth, tooth type, and age of the subjects were identified as significant factors but sex and dental arch quadrant were not. The residual lead levels obtained after regression with the significant factors were better distributed with much lesser variance. Moreover, a significant higher lead concentration could be demonstrated in the in vitro samples from the region close to the nonferrometal industrial plant.

In vivo use of a dual acid etch biopsy for the evaluation of lead profiles in human surface enamel.

Two successive acid etch biopsies were performed on the permanent maxillary right central incisors of two age-groups of children resident in an urban area in Belgium. Lead was determined in the biopsy solutions and the concentrations were related to etch depths which were calculated from the calcium and phosphorus concentrations in the biopsy solutions. The mean lead concentration of the first enamel biopsy layer was five times higher than in the second biopsy layer. A strong relation was observed between the two biopsies. It was shown that calibration of the lead values with respect to etch depths and Ca/P ratios was desirable and that a robust regression analysis approach was needed instead of classic least-squares regression analysis. However, the second biopsy provided more reliable lead estimates. In this study no increase in lead concentration in surface enamel could be demonstrated with age. Therefore, it was concluded that for these children the presence of lead in surface enamel had to be attributed primarily to preeruptive uptake.

Localization of lead and fluoride in cultured tooth germs by laser microprobe mass analysis.

Trace elements can influence dental health, possibly by altering tooth resistance during preeruptive development. Therefore, it was investigated whether lead and fluoride would be incorporated into the calcifying matrices or the cellular parts of tooth germs in vitro. Using laser microprobe mass analysis, the localization of lead and fluoride was studied in the different layers or tooth germs that had been cultured in a medium to which PbCl2 of NaF had been added in different concentrations. Both elements could only be detected in the dentine layer. Hence, the enamel organ in the secretory stage of tooth development excludes lead and fluoride from the enamel, even when enamel formation by the ameloblasts is visibly disturbed. Furthermore, there seemed to be a process of saturation in the accumulation of lead and fluoride in the dentine.