On the electrodeposition of titanium in ionic liquids.

The ability to electrodeposit titanium at low temperatures would be an important breakthrough for making corrosion resistant layers on a variety of technically important materials. Ionic liquids have often been considered as suitable solvents for the electrodeposition of titanium. In the present paper we have extensively investigated whether titanium can be electrodeposited from its halides (TiCl(4), TiF(4), TiI(4)) in different ionic liquids, namely1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide ([BMP]Tf(2)N), and trihexyltetradecyl-phosphonium bis(trifluoromethylsulfonyl)amide ([P(14,6,6,6)]Tf(2)N). Cyclic voltammetry and EQCM measurements show that, instead of elemental Ti, only non-stoichiometric halides are formed, for example with average stoichiometries of TiCl(0.2), TiCl(0.5) and TiCl(1.1). In situ STM measurements show that-in the best case-an ultrathin layer of Ti or TiCl(x) with thickness below 1 nm can be obtained. In addition, results from both electrochemical and chemical reduction experiments of TiCl(4) in a number of these ionic liquids support the formation of insoluble titanium cation-chloride complex species often involving the solvent. Solubility studies suggest that TiCl(3) and, particularly, TiCl(2) have very limited solubility in these Tf(2)N based ionic liquids. Therefore it does not appear possible to reduce Ti(4+) completely to the metal in the presence of chloride. Successful deposition processing for titanium in ionic liquids will require different maybe tailor-made titanium precursors that avoid these problems.

Electrodeposition of Al in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids: in situ STM and EQCM studies.

In the present paper, the electrodeposition of Al on flame-annealed Au(111) and polycrystalline Au substrates in two air- and water-stable ionic liquids namely, 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py(1,4)]Tf(2)N, and 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide, [EMIm]Tf(2)N, has been investigated by in situ scanning tunneling microscopy (STM), electrochemical quartz crystal microbalance (EQCM), and cyclic voltammetry. The cyclic voltammogram of aluminum deposition and stripping on Au(111) in the upper phase of the biphasic mixture of AlCl(3)/[EMIm]Tf(2)N at room temperature (25 degrees C) shows that the electrodeposition process is completely reversible as also evidenced by in situ STM and EQCM studies. Additionally, a cathodic peak at an electrode potential of about 0.55 V vs Al/Al(III) is correlated to the aluminum UPD process that was evidenced by in situ STM. A surface alloying of Al with Au at the early stage of deposition occurs. It has been found that the Au(111) surface is subject to a restructuring/reconstruction in the upper phase of the biphasic mixture of AlCl(3)/[Py(1,4)]Tf(2)N at room temperature (25 degrees C) and that the deposition is not fully reversible. Furthermore, the underpotential deposition of Al in [Py(1,4)]Tf(2)N is not as clear as in [EMIm]Tf(2)N. The frequency shift in the EQCM experiments in [Py(1,4)]Tf(2)N shows a surprising result as an increase in frequency and a decrease in damping with bulk aluminum deposition at potentials more negative than -1.8 V was observed at room temperature. However, at 100 degrees C there is a frequency decrease with ongoing Al deposition. At -2.0 V vs Al/Al(III), a bulk aluminum deposition sets in.

The location of the cementodentinal junction in single-rooted mandibular first premolars from Egyptian and Saudi patients: a histological study.

AIM: To determine the location of the cementodentinal junction (CDJ) in mandibular first premolars from Egyptian and Saudi patients. METHODOLOGY: One hundred and twenty-two extracted single-rooted mandibular first premolars (68 Egyptian; 54 Saudi) were examined histologically. Half of the teeth were fixed, decalcified, embedded in paraffin, mesio-distally sectioned and stained with H&E, whilst the other half were ground with a stone prior to microscopic evaluation. Measurements of the location of the CDJ were made parallel to the long axis of the teeth from the external surface of the root apex on the mesial and distal sides of the canal. Measurements were statistically analysed using two-way anova of repeated-measure design. RESULTS: The CDJ in Egyptian sections ranged from 0 to 2.0 mm (mean +/- SD = 0.9 +/- 0.4 mm) on the mesial side of the canal and from 0.2 to 2.5 mm (mean +/- SD = 1.0 +/- 0.5 mm) on the distal aspect. In the Saudi sample, the CDJ ranged from 0.5 to 1.2 mm (mean +/- SD = 0.8 +/- 0.3 mm) on the mesial side and from 0.6 to 0.9 mm (mean +/- SD = 0.7 +/- 0.4 mm) on the distal side. The mesial and distal differences between Egyptian and Saudi premolars on the mesial and distal surface were statistically significant (P < 0.001). CONCLUSIONS: The location of the CDJ varied between the Egyptian and Saudi mandibular first premolars, indicating that this junction is not a fixed point in populations of different countries.

Radiation dose reduction during endodontic therapy: a new technique combining an apex locator (Root ZX) and a digital imaging system (RadioVisioGraphy).

This study was undertaken on 14 teeth in order to evaluate a new technique for radiation dose reduction during endodontic therapy. After examination of the preoperative film, usually available in the patient file, an apex locator (Root ZX) was used to measure the working length. Complete chemomechanical debridement was then performed, and the master cone was evaluated by a digital imaging system (RadioVisioGraphy (RVG)). Obturation was performed when measurements of the electronic device and RVG were comparable. A postoperative image was made by the RVG system to evaluate the final obturation. A clinical and radiographic follow-up examination (follow-up period: 6 to 8 months) revealed satisfactory apical healing. These results indicated that a successful obturation technique can be performed by a single radiation exposure, using the RVG unit for master cone evaluation. This technique may be useful in medically compromised patients who need not to be exposed to excessive or repeated radiation during endodontic therapy.

Effects of nicotine on tongue development in the CD-1 mouse.

Fetuses of pregnant CD-1 mice, exposed to 0.1% nicotine sulfate at a dose of 1.67 mg/kg body weight from the 6th through the 15th gestational days were compared with control fetuses to assess the effects of nicotine on tongue development. Mothers were sacrificed on the 18th gestational day. The heads of a total of 130 nicotine-treated and 348 control fetuses were embedded in paraffin and sectioned in the frontal plane. 9.6% of the nicotine-treated fetuses had palatal clefts and their tongue development was much retarded compared to the controls. The tongues of the clefted fetuses were misshaped, reduced in size, had no filiform or fungiform papillae, and their myotubes were just in the process of formation. The circumvallate papilla of these fetuses were present but neither taste buds nor glands of von Ebner had as yet developed. Tongue development of nicotine-treated, non-clefted fetuses were closer to those of the controls. The anlagen of their filiform and fungiform papillae were developing, their myotubes were longer and better arranged, their circumvallate papilla was present but without taste buds, and their glands of von Ebner were not developed. It is suggested that nicotine interferes with both palatal and mesenchymal components of tongue development.

Regressive changes of the dental pulp complex in retained primary molars with congenitally missing successor teeth.

This study was undertaken to investigate the regressive changes occurring in the dental pulp complex (pulp, dentin, and cementum) of retained mandibular primary second molars with congenitally missing bicuspid teeth. Seventeen retained, caries free, primary molars were used. The specimens were fixed in 10% neutral buffered formalin. Fixed samples were decalcified, routinely prepared, embedded in paraffin, sectioned, and stained with hematoxylin and eosin. The results demonstrated a reduction in the pulp size, abnormal odontoblastic pattern, declined vascularity, pulp degeneration, pulp stones, accelerated formation of secondary dentin, and hypercementosis. This study suggests that these findings may be from aging and physiological defensive changes. These normal, age-induced changes are of considerable importance in the fields of endodontics, orthodontics, and pediatric dentistry.

Surgical repositioning of unerupted anterior teeth.

The result of surgical repositioning of 12 unerupted anterior teeth was studied. The unerupted teeth were gently exposed, gradually repositioned by shifting them bodily toward the occlusal plane without disturbing the periodontal ligament, and splinted for 3 wk. Root canal therapy was performed at the end of the second week following repositioning. Obturation was done at the end of the third week just before splint removal. Clinical and radiographic examination (follow-up period: 6 months to 3.5 yr) revealed no root resorption with satisfactory apical healing and healthy supporting tissues.

Induction of cleft palate by gamma-irradiation of prenatal CD-1 mice.

Fetuses of pregnant mice exposed to whole body gamma-irradiation (400 rads) on the 12th gestational day were compared with control fetuses to assess the effect of radiation on palatogenesis. Experimental and control groups were sacrificed on day 18 of gestation. The fetuses were removed via laparotomy and counted to determine the litter size. Animals were decapitated and the maximum head height, width, and circumference recorded. For light microscopic examination of palatogenesis, heads were fixed in Bouin's solution and prepared for paraffin sectioning and staining with hematoxylin and eosin. A significant reduction in litter size (p < .0025) and head measurements (p < .005) of irradiated fetuses was observed when compared to those of the control group. Histologic examination of serial coronal sections demonstrated that 100% of the experimental fetuses had palatal clefts. It was concluded that gamma-rays have adverse effects on the litter size, head measurements, and palatal closure of mouse fetuses.

Effect of gamma-irradiation on prenatal development of the tongue in CD-1 mice.

Development of the tongue in murine fetuses, in which the dams were exposed to whole body gamma-irradiation (400 rads) on the 12th day postcoitum, was studied and compared with unirradiated controls. Experimental and control groups were killed on day 18 of gestation and the fetuses were removed via laparotomy. The fetal heads were excised, fixed in Bouin's solution, prepared for paraffin sectioning, and stained with hematoxylin and eosin for light microscopic examination. Histologic examination of serial coronal sections demonstrated that all of the experimental fetuses possessed malformed, poorly developed tongues, when compared to those of the control group. It was concluded that gamma-irradiation has an adverse effect on tongue development in mouse fetuses.

Effect of gamma-irradiation on prenatal development of the nasal septal cartilage in CD-1 mice.

The effects of gamma-rays on nasal septum development in CD-1 mouse fetuses subsequent to irradiation of their mothers were studied. Pregnant CD-1 mice exposed to 400 rads of whole body gamma-irradiation 12 days after gestation were sacrificed on day 18, post coitum. The fetuses were removed via laparotomy and analyzed. Data on head dimensions, including head height, width, and circumference were recorded. Fetal heads were then routinely prepared for histologic examination of the developing nasal septal cartilage. Analysis of data revealed significant reduction in litter size (p < .0025) and head measurements (p < .0005) of irradiated animals. Histologically, the nasal septa of irradiated fetuses had retarded growth, were less differentiated, and smaller than those of control mice. Results suggest that gamma-irradiation has detrimental effects on litter and head sizes and may interfere with the cellular maturation process of nasal septal cartilage as well as other structures.

Endodontic therapy of traumatized incisors with crown and transverse intra-alveolar root fractures.

A case involving traumatic injury to the maxillary anterior teeth with crown and transverse intra-alveolar root fractures is reported. The patient did not seek immediate treatment after trauma. Treatment included pulpectomy, fixation of a fractured root, root canal obturation, endodontic therapy of the coronal segment, and postoperative observation. Follow-up showed good results. Thus effective nonsurgical endodontic therapy of traumatized anterior teeth can result in a good prognosis in cases involving crown and intra-alveolar root fractures.

Effects of gamma radiation on incisor development of the prenatal albino mouse.

Fetuses of pregnant albino mouse exposed to 400 rad of gamma-irradiation, on the 12th gestational day, were compared with unirradiated fetuses to asses the radiation effect on developing incisors. Pregnant animals were sacrificed on day 18 post coitum, and their fetuses were decapitated. Heads were routinely prepared, frontally sectioned, and stained with hematoxylin and eosin. Histologic examination demonstrated that the development of the maxillary and mandibular incisors was retarded in all the experimental fetuses and were in early bell stage, whereas those of the control animals were elaborated their matrices. It was concluded that gamma-irradiation interferes with cytodifferentiation of the enamel organ and dental papilla and subsequently inhibits normal odontogenesis.

Healing assessment of osseous defects of periapical lesions associated with failed endodontically treated teeth with use of freeze-dried bone allograft.

Freeze-dried bone allograft (FDBA) has been used extensively in periodontal surgery and in the treatment of pocket osseous defects resulting from inflammatory periodontal disease. No other endodontic investigation has used this type of graft material in the treatment of bony resorptive defects of the periapical lesions associated with failed endodontic therapy. Therefore this study was conducted with the use of FDBA, to assess healing ability of osseous defects after removal of periapical lesions associated with failed endodontically treated teeth. In all patients periapical lesions were surgically removed with retrograde amalgam seal and the graft material was then carefully packed without pressure into the bony defect. The lesions were fixed in 10% neutral buffered formalin and prepared for histologic examination. Long-term recall demonstrated bone regeneration and good tolerance of allograft material by the periapical tissues. The periapical lesions were either periapical granulomas or apical periodontal cysts. We conclude that FDBA is a biocompatible material of osteogenic potential and can be used effectively in treating osseous defects of periapical lesions associated with failed endodontically treated teeth.

Postnatal effects of nicotine on first molar development in the CD-1 mouse.

Young CD-1 mice, 4 days old, exposed to 0.1% nicotine sulfate on gestational days 6-20 were compared with untreated pups of the same age to determine its effect on the development of mandibular first molars. Pregnant mice were given intraperitoneal injections of nicotine at a dose of 1.67 mg/kg/day. Pups were then decapitated, their entire mandibles were excised, routinely prepared and embedded in paraffin, sectioned in the frontal plane and stained with hematoxylin and eosin for histological examination of developing lower first molars. The results demonstrated that the process of odontogenesis appears retarded in nicotine-treated animals while the molars of the control group revealed dentin and enamel formation. It was concluded that nicotine has a detrimental effect on molar development. Nicotine may interfere with cellular maturation of the tooth germ indicating that this effect is prenatal and extends postnatally.

Teratogenic effects of nicotine on first molar odontogenesis in the mouse.

Fetuses of pregnant CD-1 Swiss albino mice, exposed to 0.1% nicotine sulphate at a dose of 1.67 mg/kg body weight from the 6th to the 15th gestational day, were compared with control fetuses to assess the effects of nicotine on first molar odontogenesis. Mothers were sacrificed on the 18th day of gestation. The 130 nicotine treated fetuses, as well as the 348 control fetuses were embedded in paraffin and sectioned in the frontal plane. The developing molars of the experimental fetuses were retarded, less differentiated, and reduced in breadth in comparison with controls. The developing molars of the control fetuses were in the bell stage of odontogenesis, whereas those of the experimental population were either in the late cap or early cap stage, depending on the absence or presence of palatal cleft, which occurred in 9.6% of the fetuses. It is suggested that nicotine, or its metabolic byproducts, interfere with normal interaction between the epithelial and mesenchymal components of the developing tooth.

Postnatal effects of nicotine on incisor development of albino mouse.

Young albino mice, 4-days-old, exposed to 0.1% nicotine sulfate on gestational days 6-20 were compared with untreated pups to determine nicotine's effects on the animals. Pregnant mice were given intraperitoneal injections of nicotine at a dose of 1.67 mg/kg/day. Data of pups weight, CRL, distance between the anterior and posterior limbs, maximum head height and width as well as head circumference were collected. The neonates were then decapitated, their entire mandibles were excised, routinely prepared, sectioned and stained with H and E for histologic examination of the developing incisors. All the parameters were significantly reduced in the treated group. Histologically, the processes of odontogenesis appeared retarded in nicotine treated animals, whereas the control group demonstrated normal dentin and enamel formation. Thus nicotine has a detrimental effect on the development of newborn offspring in general and incisor development in particular. This effect begins prenatally and extends postnatally.

Effects of nicotine on murine incisor development.

The effects of daily injections of nicotine sulfate on incisor development in CD-I mice were studied. Pregnant animals, injected with 0.1% nicotine sulfate at a dose of 1.67 mg/kg body weight from the 6th to the 15th day of gestation, were sacrificed on the 18th postcoital day. The 130 nicotine treated fetuses, as well as the 348 control fetuses were embedded in paraffin and sectioned in the frontal plane. The developing incisors of the experimental fetuses were retarded, less differentiated, and reduced in breadth and length. The developing incisors of the control fetuses were in the early appositional stage of odontogenesis, whereas those of the experimental population were either in the late cap or early bell stage, depending on the presence or absence of palatal cleft, which occurred in 9.6% of the fetuses.

The use of radiographs in periapical surgery.

The purpose of this case report is to demonstrate the importance of radiographic examination before suturing in periapical surgery. Corrective surgery was performed to eliminate excess amalgam left in the periapical region 6 years before. The result was favorable and demonstrates the importance of radiographic examination before flap repositioning and suturing. A roentgenogram should always be made before suturing and dismissal to verify the removal of amalgam particles and to confirm that no alteration is needed.

Teratogenic effects of nicotine on palate formation in mice.

Fetuses of pregnant CD-1 mice, exposed to intraperitoneal injection of 0.1% nicotine sulfate at a dose of 1.67 mg/kg body weight/day on gestational days 6-15, were compared with control (saline injected and non-injected) fetuses to assess the effects of nicotine on fetal growth in general and palatogenesis in particular. A total of 59 pregnant females (18 experimental and 41 control) were sacrificed on the 18 th gestational day and their fetuses were examined gross morphologically and histologically (using serial sections through the head in the frontal plane). Data analysis revealed that maternal weight gain, crown-rump length, fetal weight and head dimensions were significantly reduced in nicoted treated animals when compared to those of the controls. Histological examination revealed that 9.6% of fetuses of nicotine injected mothers presented clefts of the palate, whereas none of the control fetuses had that anomaly. It was concluded that nicotine has a detrimental effect on general growth and development as well as on palatogenesis of mice.

Calcium hydroxide in the treatment of external root resorption.

A case is presented in which calcium hydroxide was used in endodontic treatment of external root resorption in a tooth with a necrotic pulp, during active orthodontic movement. A calcified deposit formed, filling a defect, and the tooth was subsequently obturated with gutta-percha. Thus, both types of therapy--endodontic and orthodontic--were performed simultaneously.