Decalcification prevention around orthodontic brackets bonded to bleached enamel using different topical agents.

BACKGROUND: The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. METHODS: Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle gel. Metal brackets were bonded to all the teeth using light-cured adhesive. Each group was divided into six equal subgroups (A, B, C, D, E, and F). In subgroup A, no material was applied (control). In subgroups B, C, D, E, and F, the following materials were applied respectively: Profluorid varnish, Enamel Pro Varnish, Ortho-Choice Ortho-Coat, GC Tooth Mousse, and GC MI Paste Plus. All teeth were cycled in a demineralization solution/artificial saliva for 15 days. Laser fluorescence was used to measure the level of enamel mineralization. The data were statistically analyzed. RESULTS: Regarding the non-bleaching subgroups, all studied material revealed significant demineralization reduction in comparison to the control subgroup (P < 0.05). Ortho-Choice Ortho-Coat revealed the highest significant effect while GC Tooth Mousse showed the least effect. In bleached subgroups, Profluorid varnish, Enamel Pro Varnish, and Ortho-Choice Ortho-Coat significantly reduced demineralization (P < 0.05) while either GC MI Paste Plus or GC Tooth Mousse had no significant effects (P > 0.05). CONCLUSIONS: Ortho-Choice Ortho-Coat, and Profluorid and Enamel Pro varnishes could be utilized successfully to reduce enamel demineralization around brackets bonded to either bleached or non-bleached enamel. GC MI Paste Plus and GC Tooth Mousse were effective only in non-bleached enamel.

Direct inhibition of osteoblastic Wnt pathway by fibroblast growth factor 23 contributes to bone loss in chronic kidney disease.

Bone loss and increased fractures are common complications in chronic kidney disease. Because Wnt pathway activation is essential for normal bone mineralization, we assessed whether Wnt inhibition contributes to high-phosphorus-induced mineralization defects in uremic rats. By week 20 after 7/8 nephrectomy, rats fed a high-phosphorus diet had the expected high serum creatinine, phosphorus, parathyroid hormone, and fibroblast growth factor 23 (FGF23) levels and low serum calcium. There was a 15% reduction in tibial mineral density and a doubling of bone cortical porosity compared to uremic rats fed a normal-phosphorus diet. The decreases in tibial mineral density were preceded by time-dependent increments in gene expression of bone formation (Osteocalcin and Runx2) and resorption (Cathepsin K) markers, which paralleled elevations in gene expression of the Wnt inhibitors Sfrp1 and Dkk1 in bone. Similar elevations of Wnt inhibitors plus an increased phospho-ß-catenin/ß-catenin ratio occurred upon exposure of the osteoblast cell line UMR106-01 either to uremic serum or to the combination of parathyroid hormone, FGF23, and soluble Klotho, at levels present in uremic serum. Strikingly, while osteoblast exposure to parathyroid hormone suppressed the expression of Wnt inhibitors, FGF23 directly inhibited the osteoblastic Wnt pathway through a soluble Klotho/MAPK-mediated process that required Dkk1 induction. Thus, the induction of Dkk1 by FGF23/soluble Klotho in osteoblasts inactivates Wnt/ß-catenin signaling. This provides a novel autocrine/paracrine mechanism for the adverse impact of high FGF23 levels on bone in chronic kidney disease.

Space flight calcium: implications for astronaut health, spacecraft operations, and Earth.

The space flight environment is known to induce bone loss and, subsequently, calcium loss. The longer the mission, generally the more bone and calcium are lost. This review provides a history of bone and calcium studies related to space flight and highlights issues related to calcium excretion that the space program must consider so that urine can be recycled. It also discusses a novel technique using natural stable isotopes of calcium that will be helpful in the future to determine calcium and bone balance during space flight.

The anti-osteoporotic effect of Eurycoma Longifolia in aged orchidectomised rat model.

Osteoporosis in elderly men is becoming an important health issue with the aging society. Elderly men with androgen deficiency are exposed to osteoporosis and can be treated with testosterone replacement. In this study, Eurycoma longifolia (EL), a plant with androgenic effects, was supplemented to an androgen-deficient osteoporotic aged rat as alternative to testosterone. Aged 12 months old Sprague-Dawley rats were divided into groups of normal control (NC), sham-operated (SO), orchidectomised-control (OrxC), orchidectomised and supplemented with EL (Orx + El) and orchidectomised and given testosterone (Orx + T). After 6 weeks of treatment, serum osteocalcin, serum terminal C-telopeptide Type 1 collagen (CTX) and the fourth lumbar bone calcium were measured. There were no significant differences in the osteocalcin levels before and after treatment in all the groups. The CTX levels were also similar for all the groups before treatment. However, after treatment, orchidectomy had caused significant elevation of CTX compared to normal control rats. Testosterone replacements in orchidectomised rats were able to prevent the rise of CTX. Orchidectomy had also reduced the bone calcium level compared to normal control rats. Both testosterone replacement and EL supplementation to orchidectomised rats were able to maintain the bone calcium level, with the former showing better effects. As a conclusion, EL prevented bone calcium loss in orchidectomised rats and therefore has the potential to be used as an alternative treatment for androgen deficient osteoporosis.

Efficacy of a sealant : study on the efficacy of a sealant (Light Bond) in preventing decalcification during multibracket therapy.

AIM: Decalcification remains a serious problem when treating patients with a multibracket appliance. The objective of this study was to classify patients with decalcification in terms of where it occurs, and to compare its potential reduction using a smooth surface sealant with a control group with no sealant. We also aimed to discover whether this enamel sealant would affect the incidence of bracket loss. MATERIAL AND METHODS: A total of 78 patients aged 11.6 to 39.5 years (median: 15.9 years) treated at a private orthodontic practice were examined for signs of decalcification within a maximum of 3 months after debonding. The indexing system used for evaluation subdivided the tooth's labial surface into four zones for quantifying the area affected (0-3) and severity of the decalcification (0-3). Preexisting areas of demineralization were excluded based on photographic evidence. We used cumulative logistical regression to investigate the sealant effect. Bracket loss was evaluated according to patient records. RESULTS: In patients with sealed labial surfaces, we observed a significantly reduced level of severity in the areas affected by decalcification (p = 0.013) and the depth of demineralization (p = 0.080). Sealant application reduced the median incidence of bracket loss by half. CONCLUSIONS: Our results demonstrate that Light Bond Reliance, the viscous sealant used in this study, may assist in preventing or reducing the incidence of enamel demineralization. We also noted a correlation between the sealant's use and the incidence of bracket loss in the treatment group.

[Developmental osteopenia: decrease of bone mineral density or systemic impairment?]. / Osteopenia w wieku rozwojowym--obnizenie mineralizacji koscca czy zaburzenie ogólnoustrojowe?

In the quantitative evaluation of bone osteopenia is defined as a decrease of mineral density by more than 1 SD from the established normal values (age, sex, peak bone mass...). The border of osteopenia and osteoporosis is demarcated by -2.5 SD (T-score) in adults, while in children the most proper is considered to be -2.0 SD (Z-Score). The aim of the study was to determine whether developmental osteopenia is accompanied by biochemical abnormalities and what are clinical symptoms concomitant with this condition. The studies include 28 children aged 5-17 years, in whom no chronic disease, especially of locomotor system, was found. The basis for diagnosis was densitometric examination of bone, with DEXA method (densitometer by Lunar), vertebral column (Spine) in the pediatric program or for adults. The most frequent causes for referring to the examination were pain in the spine, limbs or history of multiple bone fractures. In the performed biochemical examinations hypomagnesemia, decreased concentration of 25OHD and PTH in blood serum, increased activity of bone isoenzyme of alkaline phosphatase as well as increased excretion of hydroxyproline in urine, were found in several children. In about 1/3 of the children low body mass, and in some cases also retardation of the bone age was revealed. The results of our studies allow a conclusion, that in children with certain clinical abnormalities from locomotor system osteopenia may take place. This disturbance is concomitant with various deviations in calcium-phosphate metabolism and requires adequate therapy. It may be supposed, that in the majority of children, osteopenia was caused by low dietary calcium intake, together with reduced physical activity and vitamin D deficiency. The observations and conclusions from the study are of important practical significance, because children with osteopenia are the risk group for the appearance of osteoporosis in their future life.

[X-ray densitometry and biochemical parameters of bone tissue metabolism in patients with vibration disease]. / Rentgenodensitometricheskie i biokhimicheskie pokazateli metabolizma kostnoi tkani u bol'nykh vibratsionnoi bolezn'iu.

To reveal systemic and local osteoporosis, the authors studied biochemical markers of bone metabolism in vibration disease patients. The vibration disease patients appeared to have the most frequent and marked osteoporosis in peripheral bones--hands (in 90% of cases) and forearms (in 66.7%). Prevalence of systemic osteoporosis and osteopenia reached 11.7 and 48.3% in the select respectively. According to biochemical markers, bone reconstruction state was characterized by moderately intensified bone resorption and diminished bone formation.

[Bone demineralization and elevation of serum osteocalcin concentrations in young children with hyperthyroidism]. / Déminéralisation osseuse et elévation des concentrations sériques d'ostéocalcine chez les jeunes enfants atteints d'hyperthyroïdie.

Bone mineralization and serum osteocalcin level were evaluated in 15 children with Grave's disease. Two groups were constituted according to the presence (group I: n = 9) or absence (group II: n = 6) of a severe bone demineralization. A spontaneous fracture and a collapsed vertebra were found in one group I patient. Patients in group I were younger than in group II (8.3 +/- 4.9 vs 11.5 +/- 4.3 yrs). One patient in group II and six in group I were prepubertal with advanced bone age and increased growth velocity. Osteocalcin measurement (Oc) was performed in 10 patients (group I: n = 6; group II: n = 4) at the time of biological hyperthyroidism. The six patients with bone demineralization had elevated Oc levels. In group II, two patients had normal Oc levels and two had elevated Oc levels. In treated patients with good control of hyperthyroidism, all group II patients except one, had normal serum Oc levels and bone mineralization remain normal (n = 5) after 0.6 to 4.6 yrs of follow-up. In group I patients, although height velocity was normal, elevated (n = 4) or slightly elevated (n = 1) serum Oc levels and severe bone demineralization (n = 7 cases) persisted after 0.5 to 3 yrs of good control of the hyperthyroidism. Although the method used for measuring bone mineralization is potentially less precise than bone densitometry and not all the patients had serum osteocalcin measurements at the same time of the illness, our results emphasize that skeletal demineralization may be particularly marked in young children with Grave's disease and should be carefully evaluated.

[Prevalence of bone decalcification in the treatment of Crohn's disease]. / Prevalence odvápnení kostí pri lécbe Crohnovy nemoci.

In clinically active Crohn's disease the bone mineralization is impaired due to calcium malabsorption by the inflamed intestinal wall which is potentiated by diarrhoea and the thus accelerated transit time. To this we must add the shortening of the gut after operations, the inadequate dietary calcium supply or possibly calcium elimination in case of concurrent lactose intolerance. Corticoid treatment leads also to deterioration of bone mineralization. This is the reason why the authors assessed in 98 patients with Crohn's disease the bone mineralization, using the method of clavicular bone index (NIBA). Then treatment was started: a high protein diet, calcium forte, Ossin (sodium fluoride), vitamin D forte, anabolics and regular physical exercise. Check-up examinations after one year revealed that the index was restored in the majority of patients (60.84%) to normal. The above treatment is thus effective. It must be, however, regular and of a long-term character, in some patients it must extend over many years. We had, however, also patients who although subjected to an extensive resection of the gut and treated for prolonged periods with corticoids, had permanently an index between 100 and 120% without treatment.

A Japanese adult case of cystic fibrosis causing bone demineralization.

Cystic fibrosis is an inherited, multisystem disorder characterized by an abnormality in exocrine gland function. It leads to chronic pulmonary disease in most cases and pancreatic insufficiency in 85 percent of patients. Although this disease is not uncommon in Caucasians, it has been considered very rare among Japanese. The majority of patients are diagnosed in infancy or childhood. The patient in this case report was a 45-year-old Japanese man who had not been diagnosed as having cystic fibrosis. This patient had recurrent episodes of pulmonary infection that started in childhood, and plain films of the chest showed increased interstitial markings, hyperaeration, and bronchiectasis. CT of the upper abdomen showed a generally enlarged pancreas with complete fatty replacement. Serum and urine pancreatic enzyme levels were low, suggesting pancreatic insufficiency. Repeated sweat tests were positive. A roentgenologic skeletal survey showed general demineralization, which may be multifactorial. In this case, it was concluded that vitamin D deficiency caused by vitamin D malabsorption and/or insufficient sunlight exposure was mainly responsible for the demineralization and that chronic respiratory acidosis might also be partially responsible.

Prevention in orthodontics--a review.

Increasing numbers of patients are being orthodontically treated by specialist and general dental practitioners, after postgraduate courses and clinical assistantships. The potential for iatrogenic damage to the teeth and supporting structures has, therefore, also increased. This paper examines these problems and outlines measures for their prevention.

[Focal demineralization of the cortical plate of the jaw and its experimental reversibility based on microphotometry data]. / Ochagovaia demineralizatsiia kortikal'noi plastinki cheliusti i ee obratimost' v usloviiakh éksperimenta po dannym mikrofotometrii.

Focal demineralization of bone tissue with local dosed vacuum (exposure of up to 20 sec) and 2% lithium chloride electrophoresis (8 sessions daily, 10 min exposure) was tried in 40 white rats (21 reference ones and 19 experimental). The maximal reduction of mineral content was achieved on days 3-7 after the end of the course and made up 76.2 +/- 15.0% (p less than 0.01) and 80.6 +/- 12.5% (p less than 0.001), respectively, as against the reference animals. Mineral content at the site of demineralization gradually normalized by day 21. This transient reduction of mineral content of bone tissue may be used in orthodontic treatment of dentition abnormalities.

A light and scanning electron microscopic study of enamel decalcification in children living in a water-fluoridated area.

Eleven children, each having one or two pairs of premolars to be extracted for orthodontic purposes, participated in the study. The model involved placement of a special orthodontic band that allowed the accumulation of plaque in a defined area between the band and the buccal enamel. Examination of enamel changes was carried out in experimental teeth that had been exposed to local plaque accumulation for one, two, four, eight or 14 days. The specimens were examined under the light (LM) and the scanning electron microscope (SEM). All teeth had signs of very mild dental fluorosis. No indications of demineralization were noted after one day. SEM examination showed signs of crystal dissolution in some of the two-day specimens. Six of eight four-day specimens exhibited surface dissolution. All eight- and 14-day specimens showed signs of surface demineralization in the LM as well as in the SEM. These observations documented that undisturbed bacterial deposits are capable of initiating enamel demineralization within short time periods, even in children living in a water-fluoridated area.

X ray anomalies occurring in workers exposed to vibration caused by light tools.

A high frequency of radiological anomalies (vacuoles, cysts, enostoses) was found in workers exposed to vibration caused by light tools (screw drivers, nutrunners) compared with a non-exposed group. The lesions were mostly localised in the spongy carpal bones (os capitatum, os lunatum, os scaphoideum). There was no significant difference between the sexes, nor between the "active" or "passive" hand, both hands being simultaneously exposed. These findings support the need to implement preventive measures.