On inhibition of dental erosion.

OBJECTIVE: To examine the erosion-inhibiting effect of different concentrations of hydrofluoric acid. MATERIALS AND METHODS: Thirty-six human molars were individually treated with 10 ml of 0.1 M citric acid for 30 min (Etch 1), acid was collected and stored until analysis. The teeth were randomly divided into six groups and then individually treated with 10 ml of one of six dilutions (from 0.1-1%) of hydrofluoric acid. The teeth were then again treated with citric acid (Etch 2). The individual acid samples from Etch 1 and 2 were analyzed for calcium by flame atomic absorption spectroscopy and difference in calcium loss was calculated. RESULTS: The highest erosion inhibiting effect was obtained in groups with the highest concentrations of hydrofluoric acid, where the pH was lowest, below pKa of 3.17, thus the hydrofluoric acids being mainly in an undissociated state. DISCUSSION: Diluted hydrofluoric acid is present in aqueous solution of SnF2 and TiF4 (which are known to inhibit dental erosion): SnF2 + 3H2O = Sn(OH)2 + 2HF + H2O and TiF4 + 5H2O = Ti(OH)4 + 4HF + H2O. It is also known that pure, diluted hydrofluoric acid can inhibit dental erosion. Teeth treated with hydrofluoric acid are covered by a layer of CaF2-like mineral. This mineral is acid resistant at pH < 3, because it was formed at this pH. CONCLUSION: The erosion-inhibiting effect is due to formation of an acid resistant mineral, initiated by tooth enamel treatment with hydrofluoric acid. Hydrofluoric acid is different in having fluoride as a conjugated base, which provides this acid with unique properties.

Dentin to dentin adhesion using combinations of resin cements and adhesives from different manufacturers - a novel approach.

AIMS: The aims of this study were to present a novel method to analyse dentin bond strength and to evaluate the bond strength of combining adhesive systems and resin cement from different manufacturers. METHODS: Human wisdom teeth were ground flat to the dentin on parallel surfaces and axially cut into two parts. Dentin cylinders (Ø 3 mm) were drilled from one half of each tooth. The other half from each tooth was embedded in epoxy resin with the dentin surface exposed. The specimens were ground with silicone carbide paper and the dentin cylinders were cemented onto the dentin surface of the other half of the same tooth.Materials: Resin cement and adhesive systems from three different manufacturers were used in various combinations (n = 8 per group). Cement and adhesive from the same manufacturer served as control. Shear bond strength (SBS) was measured and fracture modes were registered.Results and conclusions: The highest median SBS value was found in a bonding combination between cement and a non-corresponding adhesive (33.1 MPa) and one of the lowest values was found in one of the controls (15.3 MPa). Cohesive fractures were most frequent. The results indicated that combining adhesive and cement from different manufacturers did not compromise the dentin bonding. The novel test method is recommended for evaluating dentin bonding.

In vivo and in vitro irritation testing of low concentrations of hydrofluoric acid.

OBJECTIVE: Acidic fluorides are proposed for the treatment of dental erosion. The aim of this study was to examine the irritation properties of dilute hydrofluoric acid (HF) solutions for potential use in the oral cavity. MATERIAL AND METHODS: Hen's egg test-chorioallantoic membrane (HET-CAM): The CAM was accessed by careful dissection through the egg shell (n=36, 6 eggs/test solution) and exposed to 300 µl of the HF solutions (0.05%, 0.10%, 0.20%, and 1.0%) under macroscope examination over the course of 5 min. Mean time-to-coagulation and average irritation score were recorded based on appearance of hemorrhage, coagulation, and lysis of the blood vessels in the membrane. Mouse skin test: 60 male mice were randomly divided into 10 groups of 6 animals each (control, 0.05%, 0.10%, 0.20%, and 1.0% HF), shaved on the back, exposed to test solution, and euthanized after 2 h or 24 h. Skin samples were evaluated by light microscopy, scoring epithelial leukocyte infiltration, vascular congestion, and edema. RESULTS: HET-CAM: 0.05% HF was slightly irritant, 0.1% HF moderately irritant, 0.2% and 1% HF strongly irritant. 0.1-1% HF solutions were severely irritating on the eye. Mouse skin test: HF concentration was significantly correlated with tissue response, and 24-h exposure to 1% HF solution showed focal erosion of the epithelium and marked localized subepithelial leukocyte infiltration. CONCLUSION: The results of the studies suggest that accidental exposure of soft tissues to solutions containing more than 0.2% HF may be harmful.

A prospective study on the clinical performance of polysiloxane soft liners: one-year results.

OBJECTIVE: The aim of the present study was to evaluate the clinical performance of four denture soft liners up to 12 months. MATERIALS AND METHODS: Thirty-three edentulous patients who experienced difficulties when using hard denture bases because of changes in denture-supporting tissues were accepted for the study and randomly received Molloplast B, GC Reline Soft, Silagum Comfort, or Mollosil Plus relines. Performance of the materials was evaluated using nine criteria at 3, 6, and 12 months: physical integrity, surface detail, adhesion, color, odor, plaque accumulation, resilience, hygiene, and mucosal condition. A four-point categorized scale (1=poor, 2=fair, 3=good, 4=excellent) was used. Unscheduled maintenance events and the presence of fungal colonization were also recorded. RESULTS: The percentage of patients available at 3, 6, and 12 months were 91%, 91%, and 66%. Main reasons for dropouts and discontinuation were fractured dentures and patient dissatisfaction. At 6 months, 96% of the performance scores were good or excellent and the largest changes were observed for physical integrity, surface detail, color, and fungal colonization. Fungal colonization was the most commonly observed problem and was the only reason of failure at 12 months. CONCLUSIONS: The clinical performance of all soft liners was slightly impaired over the 12-month observation. Except for cases showing extensive fungal colonization, the observed changes in clinical performance did not necessitate remaking of the dentures. Mollosil Plus showed a performance comparable to that of Molloplast B, and the other materials had slightly lower performance especially in terms of fungal colonization.

Etching effect of acidic fluorides on human tooth enamel in vitro.

OBJECTIVE: This in vitro study aimed to examine the etching effect of acidic fluoride solutions on enamel. MATERIALS AND METHODS: 24 human teeth divided into 48 enamel-specimens were partly isolated with impression material. Specimens were exposed for 10 min to 20ml of the following solutions: 1.6% TiF4, 3.9% SnF2, 0.2% HF and 1.8% citric acid (CA). The isolation was removed and 24 specimens analysed by profilometry (Δheight: exposed/isolated enamel surfaces, surface roughness parameters). For the remaining 24 specimens [Ca(2+)] in the test solutions was analysed by atomic absorption spectroscopy. RESULTS: Median Δheights (µm) after exposure were: TiF4 0.07, SnF2 -0.03, HF -0.14 and CA -5.92. TiF4-exposed surfaces showed both deposits and etched areas and exhibited statistically significant different surface roughness parameters compared to the HF- and SnF2-exposed surfaces. Median [Ca(2+)] values (ppm): TiF4 1.88, SnF2 0.11, HF 0.10 and CA 2.17. CONCLUSION: At the [F] tested in this study it can be concluded that SnF2- and HF solutions had negligible erosive effects on enamel. TiF4 solution resulted in an incomplete surface deposition associated with calcium dissolution suggesting that TiF4 applied as solution may not be advisable.

Treatment outcome of dental implants in the esthetic zone: a 12- to 15-year retrospective study.

In the mid-nineties, 27 patients received 31 implant-supported crowns in the anterior maxillary region, and 12 to 15 years later, 18 patients (67%) with 22 implants (67%) participated in a retrospective study evaluating implant survival, bone loss, prosthetic complications, patient satisfaction, and patient and professional evaluation of esthetics. One implant was lost because of implant fracture after 10 years. Mean marginal bone loss was 1.53 mm (standard error ± 0.17 mm). In 6 patients, 6 crowns were replaced and 1 repaired. In 3 patients, 3 crowns had minor unrepaired porcelain fractures. Implant survival was 95.5%, and, despite the high frequency of prosthetic complications, patients were generally very satisfied with the long-term treatment outcome.

Porous titanium granules in the surgical treatment of peri-implant osseous defects: a randomized clinical trial.

PURPOSE: Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to treat peri-implant osseous defects. The aim of this study was to analyze clinical and radiographic outcomes of peri-implant osseous defects after treatment with PTG. MATERIALS AND METHODS: This prospective, randomized, case-control, clinical 12-month study compared open-flap debridement and surface decontamination with titanium curettes and 24% ethylenediaminetetraacetic acid gel (n = 16) to the same protocol but with the addition of PTG (n = 16). One-, two-, and three-wall infrabony defects were included. Patients were given amoxicillin and metronidazole 3 days before surgery and for 7 days afterwards. Implants were submerged and allowed to heal for 6 months. Probing pocket depths, bleeding on probing, implant stability using resonance frequency analysis, and radiographic evaluation were performed at baseline and at 12 months. The threshold for significance was set at .05. RESULTS: Change in radiographic defect height and percent fill of the peri-implant osseous defect significantly favored patients treated with PTG. Both treatment modalities demonstrated significant improvements in probing pocket depth, but significant differences between groups were not observed. The PTG-treated implants showed an increase in implant stability quotient (ISQ) of 1.6 units, compared with a decrease of 0.7 ISQ for the control group. No adverse effects were associated with PTG treatment. CONCLUSIONS: Reconstruction with PTG resulted in significantly better radiographic peri-implant defect fill compared with controls; however, the results do not necessarily imply reosseointegration or osseointegration of PTG particles. Improvements in clinical parameters were seen in both groups, but no differences between groups were demonstrated.

Effect of acidic fluoride treatments on early enamel erosion lesions--a comparison of calcium and profilometric analyses.

OBJECTIVE: The protective effect of fluoride solutions against acidic challenge on enamel was tested in vitro using calcium- and profilometer analyses. METHODS: HF-, SnF(2)-, TiF(4)- and NaF solutions (0.1M F(-), with a pH of 2.0, 2.9, 1.5, 7.3, respectively) and H(2)O were tested on a total of 60 enamel specimens divided into 10 groups. Prior to and after F-treatment five groups were exposed for 1 min to 0.01 M citric acid, and the other five groups for 10 min to 0.1M citric acid. Enamel specimens were measured by profilometry at baseline and before and after each acidic challenge. [Ca] in the collected citric acid samples was measured by atom absorption spectroscopy (AAS). DeltaCa and Delta surface height were calculated for each specimen and the data were analysed using one-way ANOVA, Tukeys test and Pearson r correlation. RESULTS: AAS showed that the acidic F-treatments significantly reduced enamel dissolution for both the 1 min and 10 min acidic challenge. Profilometry showed no significant differences between the F-solutions for the 1 min groups. Significant differences could be seen between the fluorides for the 10 min groups and there was a large correlation between the profilometric and AAS results. In conclusion, all fluoride solutions reduced enamel dissolution when specimens were exposed to citric acid. CONCLUSIONS: The profilometer was not sensitive enough to measure the effects of the different fluorides against a low acidic challenge. AAS was able to show these differences and for the 10 min acidic challenge there was a good correlation between the results from the two methods.

Effect of stannous fluoride toothpaste on erosion-like lesions: an in vivo study.

It has recently been shown that stannous fluoride (SnF(2)), in the form of aqueous solutions and as toothpaste, can reduce the dissolution of enamel in erosive acids in vitro and in situ. The aim of this study was to compare the effect of toothpastes containing SnF(2) or NaF on enamel dissolution using an in vivo model. Four healthy anterior teeth in each subject (n = 20) were exposed to diluted citric acid (100 mmol l(-1) or 10 mmol l(-1)) applied using a peristaltic pump (5 ml @7 ml min(-1)) and the acid was collected in a test tube before and after application of the respective toothpastes (etch I and etch II). Toothpaste was applied to the labial surfaces with a soft brush (four applications, each of 1-min duration), with gentle water rinsing between applications. Each subject had one pair of teeth treated with each of the test toothpastes. Enamel dissolution was examined by assessment of calcium content in the citric acid applied before and after the treatment with toothpaste. The results indicate that the SnF(2) toothpaste markedly reduced the dissolution of teeth in vivo (etch II < etch I), whereas the NaF toothpaste provided no protection (etch II > etch I). Toothpaste appears to be an acceptable vehicle for SnF(2) and maintains the dissolution-reducing effect exhibited by aqueous solutions of this fluoride salt.