Nanostructured Ti-Zr-Pd-Si-(Nb) bulk metallic composites: Novel biocompatible materials with superior mechanical strength and elastic recovery

The microstructure, mechanical behaviour, and biocompatibility (cell culture, morphology, and cell adhesion) of nanostructured Ti45 Zr15 Pd35- x Si5 Nbx with x = 0, 5 (at. %) alloys, synthesized by arc melting and subsequent Cu mould suction casting, in the form of rods with 3 mm in diameter, are investigated. Both Ti-Zr-Pd-Si-(Nb) materials show a multi-phase (composite-like) microstructure. The main phase is cubic β-Ti phase (Im3m) but hexagonal α-Ti (P63/mmc), cubic TiPd (Pm3m), cubic PdZr (Fm3m), and hexagonal (Ti, Zr)5 Si3 (P63/mmc) phases are also present. Nanoindentation experiments show that the Ti45 Zr15 Pd30 Si5 Nb5 sample exhibits lower Young's modulus than Ti45 Zr15 Pd35 Si5 . Conversely, Ti45 Zr15 Pd35 Si5 is mechanically harder. Actually, both alloys exhibit larger values of hardness when compared with commercial Ti-40Nb, (HTi-Zr-Pd-Si ≈ 14 GPa, HTi-Zr-Pd-Si-Nb ≈ 10 GPa and HTi-40Nb ≈ 2.7 GPa). Concerning the biological behaviour, preliminary results of cell viability performed on several Ti-Zr-Pd-Si-(Nb) discs indicate that the number of live cells is superior to 94% in both cases. The studied Ti-Zr-Pd-Si-(Nb) bulk metallic system is thus interesting for biomedical applications because of the outstanding mechanical properties (relatively low Young's modulus combined with large hardness), together with the excellent biocompatibility.

Treatment of class II furcation involvements in humans with bioresorbable and nonresorbable guided tissue regeneration barriers. A randomized multi-center study

In this multi-center study 38 patients with contralateral molar Class II furcation defects were treated with GTR therapy using a bioresorbable matrix barrier (test) and a nonresorbable expanded polytetrafluoroethylene (ePTFE) barrier (control). Following flap elevation, scaling, root planing, and removal of granulation tissue, each device was adjusted to cover the furcation defect. The flaps were repositioned and sutured to complete coverage of the barriers. A second surgical procedure was performed at control sites after 4 to 6 weeks to remove the nonresorbable barrier. Before treatment and 12 months postsurgery all patients were examined and probing depths, clinical attachment levels, and position of the gingival margin were recorded. The primary response variable was the change in clinical attachment level in a horizontal direction (CAL-H change). Both treatment procedures reduced the probing depths (P < or = 0.001). Statistically significant gain of clinical attachment level in both horizontal and vertical direction was found at the test sites. At control sites gain of attachment in horizontal direction was statistically significant. The gain of CAL-H was 2.2 mm at test sites compared to 1.4 mm at control sites (P < or = 0.05). At test sites, the gingival margin was maintained close to the pre-surgical level (0.3 mm), whereas at control sites gingival recession was evident (0.9 mm), the difference being statistically significant (P < or = 0.01). Postsurgical complications, such as swelling and pain were more frequent following the control treatment (P < or = 0.05).

Clinical use of a bioresorbable matrix barrier in guided tissue regeneration therapy. Case series

In this case series study 19 Class II furcations and 47 intrabony defects in 59 patients were treated according to the principles of guided tissue regeneration using a bioresorbable matrix barrier. Gingival condition and device exposure were assessed at 2 weeks, and 1, 3, 6, and 12 months after surgery. The effect of therapy was evaluated by assessing probing depths (PD), probing attachment level (PAL), and the position of the gingival margin prior to surgery and 12 months after surgery. Mild clinical signs of inflammation in the soft tissue covering the device was found adjacent to 3 defects only and limited to the first month of healing. Device exposure occurred at 10 out of the 66 defects. At the furcation defects, the mean PD reduction amounted to 3.7 mm (P < or = 0.001). Mean gain PAL vertical was 3.4 mm and PAL horizontal 3.3 mm (P < or = 0.001), resulting in complete closure of 9 out of the 19 defects. Mean gingival recession was 0.2 mm. At the intrabony defects mean PD reduction was 5.4 mm and mean gain of PAL 4.9 mm (P < or = 0.001). Gingival recession averaged 0.5 mm (P < or = 0.05). It was concluded that the use of the matrix barrier in GTR therapy resulted in 1) reduced probing depths; 2) pronounced gain of clinical attachment; and 3) a very low incidence of gingival pathology, gingival recession, and device exposure.

Effect of a field program based on systematic plaque control on caries and gingivitis in schoolchildren after 3 years

The effect of a field program, based on systematic plaque control, on caries and gingivitis was tested during a 3-year period on 1,100 schoolchildren. Once every 3rd week the children were given oral hygiene instructions, professional toothcleaning and fluorides topically delivered by specially trained dental nurses. The children of a control group of approximately the same number of pupils, participated in a preventive program consisting of mouthrinsings once every 2nd week with a 0.2% sodium fluoride solution. The children of the third and fourth grades were, at the start of the experiment, selected as reference groups and then continuously examined once every year. At the end of the trial the mean reduction of surfaces haboring plaque and units with gingival inflammation was 59% and 73%, respectively. The reduction in caries increment was 51%.

Effect of toothbrushing with chlorhexidine gel on salivary microflora, oral hygiene, and caries

The effect of daily toothbrushing with 0.5% chlorhexidine-containing gel for 12 months was evaluated in a double-blind study in 37 dental students. The active gel did not markedly influence plaque formation, gingival conditions, or caries as compared with placebo gel treatment. Salivary bacterial counts were performed on subgroups of six subjects using chlorhexidine gel and on six using placebo gel. No differences in the effect of treatment on the microorganisms studied in the two subgroups could be detected except for S. sanguis. The percentage of this species decrease in the placebo group and increased in the chlorhexidine group. The difference became significant after 2 weeks. A tendency to a greater reduction of S. mutans noted in the chlorhexidine group was most marked in individuals who had high initial counts of this species. The proportion of S. sanguis, which could grow on chlorhexidinei-containing mitis salivarius medium, increased and after 12 months of chlorhexidine treatment averaged 34% of cultivable S. sanguis compared with 0.002% prior to treatment. The number of less sensitive S. sanguis decreased in the 12 months following termination of treatment. There was no observed tendency for the selection or proliferation of other streptococci, gram-negative rods, yeasts, or staphylococci.

Effect of listerine on dental plaque and gingivitis

The present study was performed in 10 adults in order to evaluate the effect of an antiseptic mouthrinse (Listerine) on the rate of dental plaque formation and gingivitis development during a 2-week period when all efforts towards active mechanical oral hygiene were withdrawn. The study was performed as a crossover study and was carried out during four consecutive 2-week periods. During the first and third periods (preparatory periods) the participants were subjected to repeated professional tooth cleanings in order to establish plaque- and gingivitis-free dentitions. During the second and fourth periods (test and control periods) the participants were not allowed to brush their teeth but rinsed their mouths three times a day with Listerine or a placebo mouthwash. Plaque Index, Gingival Index, gingival fluid flow, and crevicular leukocytes were assessed on d 0, 2, 4, 7, and 14. On d 7 and 14, dental plaque was removed from the right and left jaws respectively and the wet weights determined. The chemotactic activity elaborated by the plaques was studied in Boyden chambers. During the Listerine test period, significantly lower Plaque and Gingival Index values were scored and lower amounts of plaque could be sampled in comparison to the control period.