Erik Saxegaard

• Seitz, Elke; Hjortsjö, Carl; Dahl, Jon Einar & Saxegaard, Erik (2020). Dentin to dentin adhesion using combinations of resin cements and adhesives from different manufacturers - a novel approach. Biomaterial Investigations in Dentistry. 7(1), s. 96–104. doi: 10.1080/26415275.2020.1793677. Fulltekst i vitenarkiv
• Khan, Sadia Nazir & Saxegaard, Erik (2015). Obstruktivt søvnapnésyndrom - hvordan kan tannlegen bidra i behandlingen? Den norske tannlegeforenings tidende. ISSN 0029-2303. 125(9), s. 784–792.
• Khan, Sadia Nazir; Skau, Irene; Grytten, Jostein Ivar & Saxegaard, Erik (2015). Obstruktivt søvnapnésyndrom - kunnskap og klinisk erfaring blant et utvalg norske tannleger. Den norske tannlegeforenings tidende. ISSN 0029-2303. 125(9), s. 794–798.
• Hjortsjø, Carl; Jonski, Grazyna; Young, Alix & Saxegaard, Erik (2014). Etching effect of acidic fluorides on human tooth enamel in vitro. Archives of Oral Biology. ISSN 0003-9969. 59(12), s. 1328–1333. doi: 10.1016/j.archoralbio.2014.08.007.
• Rølla, Gunnar; Jonski, Grazyna & Saxegaard, Erik (2013). On inhibition of dental erosion. Acta Odontologica Scandinavica. ISSN 0001-6357. 71(6), s. 1508–1512. doi: 10.3109/00016357.2013.773371. Vis sammendrag

  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.

• Misje, Kjetil; Bjørnland, Tore; Saxegaard, Erik & Jensen, Janicke Liaaen (2013). Treatment Outcome of Dental Implants in the Esthetic Zone: A 12-to 15-Year Retrospective Study. International Journal of Prosthodontics. ISSN 0893-2174. 26(4), s. 365–369. doi: 10.11607/ijp.3097.
• Saxegaard, Erik & Jacobsen, Knut-Erik (2013). Impressions. I Nilner, Krister; Karlsson, Stig & Dahl, Bjørn L. (Red.), A textbook of fixed prosthodontics. The Scandinavian approach. Gothia Förlag AB. ISSN 9789172057968. s. 255–274.
• Wohlfahrt, Johan Caspar; Lyngstadaas, Ståle Petter; Rønold, Hans Jacob; Saxegaard, Erik; Ellingsen, Jan Eirik & Karlsson, Stig [Vis alle 7 forfattere av denne artikkelen] (2012). Porous Titanium Granules in the Surgical Treatment of Peri-Implant Osseous Defects: A Randomized Clinical Trial. International Journal of Oral & Maxillofacial Implants. ISSN 0882-2786. 27(2), s. 401–410.
• Ellingsen, Jan Eirik; Ekfeldt, Anders; Ekstrand, Karl; Saxegaard, Erik & Rønold, Hans Jacob (2010). Suksess og overlevelse av implantatforankret protetikk. Den norske tannlegeforenings tidende. ISSN 0029-2303. 120(2), s. 88–93.
• Hjortsjø, Carl; Jonski, Grazyna; Young, Alix & Saxegaard, Erik (2010). Effect of acidic fluoride treatments on early enamel erosion lesions-A comparison of calcium and profilometric analyses. Archives of Oral Biology. ISSN 0003-9969. 55(3), s. 229–234. doi: 10.1016/j.archoralbio.2010.01.003. Vis sammendrag

  Objective: The protective effect of fluoride solutions against acidic challenge on enamel was tested in vitro using calcium- and profilometer analyses. Methods: HF-, SnF2-, TiF4- and NaF solutions (0.1M F-) and H2O as negative control were tested on a total of 60 enamel specimens divided into ten groups. Prior to and after F-treatment five groups were exposed for 1min to 0.01M citric acid, and the other five groups for 10min 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). ΔCa and Δ 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 F-treatments reduced enamel dissolution for both the 1min and 10min acidic challenge. Profilometry showed no significant differences between the F-solutions for the 1min groups. Significant differences could be seen between the fluorides for the 10min 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 a typical dietary acid. Conclusions: The profilometer was not sensitive enough to measure the effects of the different fluorides against a low acidic challenge as represented by this in vitro experiment. 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.

• Ellingsen, Jan Eirik; Ekstrand, Karl; Saxegaard, Erik; Ekfeldt, Anders & Rønold, Hans Jacob (2010). Forskning kan hjälpa vid val av implantatförankrad protetik. Tandläkartidningen. ISSN 0039-6982. 102(1), s. 84–89.
• Hjortsjø, Carl; Jonski, Grazyna; Thrane, Per Stanley; Saxegaard, Erik & Young, Alix (2009). The Effects of Acidic Fluoride Solutions on Early Enamel Erosion in vivo. Caries Research. ISSN 0008-6568. 43(2), s. 126–131. doi: 10.1159/000209345.
• Hjortsjø, Carl; Saxegaard, Erik; Young, Alix & Dahl, Jon Einar (2009). In vivo and in vitro irritation testing of low concentrations of hydrofluoric acid. Acta Odontologica Scandinavica. ISSN 0001-6357. 67(6), s. 360–365. doi: 10.1080/00016350903117118. Vis sammendrag

  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 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: Sixty male mice were randomly divided into 10 groups of 6 animals (control, 0.05, 0.10, 0.20 and 1.0% HF), shaved on the back, exposed to test solution and sacrificed after 2h or 24h. 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 were strongly irritant. 0.1-1% HF solutions were severely eye irritating. 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 these studies suggest that accidental exposure of soft tissues to solutions containing more than 0.2% HF may be harmful.

• Hjortsjø, Carl; Jonski, Grazyna; Thrane, Per Stanley; Saxegaard, Erik & Young, Alix (2009). Effect of Stannous Fluoride and Dilute Hydrofluoric Acid on Early Enamel Erosion over Time in vivo. Caries Research. ISSN 0008-6568. 43(6), s. 449–454. doi: 10.1159/000261415.
• Mutluay, Mustafa Murat; Oguz, S; Fløystrand, Finn; Saxegaard, Erik; Dogan, A & Bek, B [Vis alle 7 forfattere av denne artikkelen] (2008). A prospective study on the clinical performance of polysiloxane soft liners: One-year results. Dental materials journal. ISSN 0287-4547. 27, s. 440–447.
• Gotfredsen, K; Carlsson, GE; Jokstad, A; Fyrberg, KA; Arvidsson, Kristina Fyrberg & Berge, M [Vis alle 32 forfattere av denne artikkelen] (2008). Implants and/or teeth: consensus statements and recommendations. Journal of Oral Rehabilitation. ISSN 0305-182X. 35, s. 2–8. doi: 10.1111/j.1365-2842.2007.01833.x.
• Young, Alix ; Thrane, Per Stanley; Saxegaard, Erik; Jonski, Grazyna & Rølla, Gunnar (2006). Effect of stannous fluoride toothpaste on erosion-like lesions: an in vivo study. European Journal of Oral Sciences. ISSN 0909-8836. 114, s. 180–183.
• Andersen, Eivind; Saxegaard, Erik; Knutsen, Bjørn Mork & Haanæs, Hans R (2001). A Prospective Clinical Study Evaluating the Safety and Effectiveness of Narrow-Diameter Threaded Implants in the Anterior Region of the Maxilla. International Journal of Oral & Maxillofacial Implants. ISSN 0882-2786. 16(Number 2), s. 217–224.
• Lagerlöf, Folke; Saxegaard, Erik; Barkvoll, Pål & Rølla, Gunnar (1988). Effects of inorganic orthophosphate and pyrophosphate on dissolution of calcium fluoride in water. Journal of Dental Research. ISSN 0022-0345. 67, s. 447–449.

Se alle arbeider i Cristin

• Johansson, Anders; Bjorvatn, Bjørn; Saxegaard, Erik; Gjerde, Kjersti; Berge, Morten Eirik & Lehmann, Sverre [Vis alle 7 forfattere av denne artikkelen] (2018). Stor interesse for odontologisk søvnmedisin og søvnapné i Norge. Den norske tannlegeforenings tidende. ISSN 0029-2303. 128(3), s. 202–204.
• Rønold, Hans Jacob; Saxegaard, Erik & Ellingsen, Jan Eirik (2015). Hvordan sikre en god start på en vellykket tannbehandling? Den norske tannlegeforenings tidende. ISSN 0029-2303. 125(2), s. 162–167.
• Hjortsjø, Carl; Jonski, Grazyna; Young, Alix & Saxegaard, Erik (2011). Erosive effect of acidic fluoride solutions on enamel in vitro. Vis sammendrag

  Acidic fluoride solutions have been shown to exhibit erosion-inhibiting properties on dental enamel. The aim of this in vitro study was to investigate the possible erosive effect of dilute hydrofluoric acid (HF) on enamel. A 0.2% HF solution (0.1 mol/l F-, pH 3.02) was compared with two acidic fluorides containing 0.5 mol/l F- (3.9% SnF2-pH 2.65 and 1.6% TiF4-pH 1.42) and 1.8% citric acid (acidic control, pH 2.27). 24 human third molar enamel specimens were randomly divided into 4 groups (6 specimen/solution). Enamel surfaces were ground flat by wet grinding with a grit 2500 abrasive paper and half of each flat surface was isolated using a A-silicon impression material. The enamel surfaces were exposed to 20ml of the test solutions for ten minutes in plastic containers. The isolation material was removed. and changes in the enamel surfaces were analysed by LED blue light profilometry (λ=470 nm, 50x magnification). The specimen area analysed included both treated and untreated ground enamel, a total area of 254.64 x 190.90 µm2 for each sample. The difference in surface height between treated and untreated enamel was calculated for each specimen and etching depth data were analysed using oneway ANOVA and Tukeys test. The mean etching depths (µm±SD) were 0.14(0.86), -2.00(0.52), -3.25(2.91) and 5.42(1.00) for, HF, SnF2, TiF4 and control respectively. HF had significantly less etching effect than the control, but was significantly more erosive than TiF4 (p<0.05). In conclusion, while both SnF2 and TiF4 treatments resulted in an average deposition on the enamel surface, HF showed an average etching effect close to zero. Further studies are needed to examine the mechanism of the previously described anti-erosive effect of HF.

• Wohlfahrt, Johan Caspar; Aass, Anne Merete; Rønold, Hans Jacob; Karlsson, Stig; Ellingsen, Jan Eirik & Saxegaard, Erik (2010). Porous titanium granules in the surgical treatment of peri-implant osseous defects - a randomized clinical trial.
• Wohlfahrt, Johan Caspar; Aass, Anne Merete; Rønold, Hans Jacob; Karlsson, Stig; Ellingsen, Jan Eirik & Saxegaard, Erik [Vis alle 7 forfattere av denne artikkelen] (2009). Porous Titanium Granules in the Surgical Treatment of Peri-Implant Osseous Defects – A Randomized Clinical Study.
• Hjortsjø, Carl; Jonski, Grazyna; Saxegaard, Erik & Young, Alix (2009). Profilometric study of the effects of acidic fluoride solutions on early dental erosion. Vis sammendrag

  An in-vivo experimental model for dental erosion has been utilised to assess the effects of treating dental enamel with fluorides. This in-vitro study aimed to examine the effects of the same acidic fluoride solutions using profilometry. Crowns of intact, surgically extracted human third molar teeth were cut into 2-4 pieces, washed (deionised water, 50% ethanol then 96% ethanol), embedded in acrylic resin and polished (grit 4000). Nail varnish was applied in a line across the block separating the enamel surface from the acrylic resin surface. Specimens were exposed to 5 ml of 100 mmol/L citric acid for 10 min before (etch I) and after (etch II) fluoride treatments. Aqueous solutions of TiF4, SnF2, HF or NaF, (all 0.1 M F-) and deionised water (negative control) were tested (n=6 specimens/test solution). All solutions were applied in a cell culture well (Nunclon, Nunc, Roskilde, Denmark) and enamel specimens were exposed to all the fluids in these wells. Specimens were analysed at all stages in a high power LED blue light profilometer (PLµ2300 Optical Imaging Profiler, Sensofar Tech, Spain) at 150x magnification and λ=470 nm. Areas including one half of exposed enamel and the other half varnish-covered enamel (220.98 x 165.68µm) were analysed to a depth of 40µm. Data analysis compared the step-height differences between the exposed and the varnished reference areas. Paired t-test and Kruskal-Wallis ANOVA on Ranks were used in the statistical analysis. There was a significant reduction in step height difference following HF-, SnF2-, and TiF4-treatments (p ≤0.005), but not for the NaF and water. The acidic fluoride solutions were capable of reducing the erosive effect of the citric acid challenge as previously shown in the in vivo experimental model.

• Young, Alix ; Hjortsjø, Carl; Saxegaard, Erik & Jonski, Grazyna (2009). A study on the effect of age on enamel dissolution using a dental erosion model. Vis sammendrag

  The prevailing expert opinion suggests that there is little evidence to support the concept that pathological levels of dental erosion are age-dependant. However, some evidence seems to indicate that normal levels of erosion may be age-dependant. Many factors may contribute to this type of wear and presumably the enamel solubility is one of these factors. An in-vivo experimental model for dental erosion using volunteers of various ages has been utilised to assess the effects of treating dental enamel with fluorides to reduce damage due to erosion. The aim of the present study was to examine the possible relationship between the age of the test individuals and the degree of enamel dissolution upon acidic challenge. The in-vivo model has been described previously. In 176 test subjects (age range 18 - 69 years), labial surfaces of 342 healthy anterior teeth were exposed to 5 ml 0.18% citric acid, at 6 ml/min using a peristaltic pump. The acid was collected in coded test tubes for blind analysis of calcium content using atom absorption spectrometry. Mean calcium concentration was calculated separately for central incisors (0.924 mg/L, range 0.033-4.434) and lateral incisors (0.654 mg/L, range 0.051-3.048). The age of the subjects was not normally distributed with a mean age of 27.8 years. Statistical analysis using Spearman’s rho showed no correlation between the age of the test subjects and the calcium concentration in the acid etch (central incisors rs = 0.048, lateral incisors rs = 0.161, p<0.05). Despite the skewed age distribution these results do not support a correlation between age and degree of enamel dissolution following a brief acidic challenge.

• Hjortsjø, Carl; Jonski, Grazyna; Saxegaard, Erik & Young, Alix (2009). Validation of a dental erosion model I–chemical analysis in-vitro. Vis sammendrag

  An in vivo experimental model for dental erosion has been utilised to assess the effects of treating dental enamel with fluorides as a preventive and/or treatment measure. Objective: To validate the in-vivo experimental model results in-vitro using chemical analysis. Methods: Crowns of intact, surgically extracted human third molar teeth were cut into 2-4 pieces, washed (deionised water, 50% ethanol, 96% ethanol), embedded in acrylic resin and polished (grit 4000). Specimens were exposed to 5 ml of 10 mmol/L citric acid for 1 min before (etch I) and after (etch II) fluoride treatment. Aqueous solutions of TiF4, SnF2, HF and NaF (all 0.1 M F-) and deionised water (negative control) were tested (n = 6 tooth specimens/test solution). The citric acid and test solutions were applied using a peristaltic pump (flow: 6 ml/min, Gilson model Minipuls 3). Etch and fluoride solutions were collected in coded tubes and analysed blind for calcium content using atomic absorption spectrometry (Model 3300, Perkin Elmer Analytical Instruments, USA) using air-acetylene flame and λ = 422.7 nm. ∆ ppm calcium (etch I minus etch II) was calculated for each tooth and mean percentage reduction in calcium loss was determined for each test solution. Results were analysed using one way ANOVA and the Bonferroni t-test for multiple comparisons. Results: The HF- and SnF2-treatments were significantly more effective in reducing calcium dissolution than the TiF4 and NaF-treatments (p≤0.004). There was no statistical difference between TiF4 and NaF- treatments (p=0.138). The water control resulted in an increase in calcium dissolution. Conclusion: These results correlate well with results from the in vivo model and help validate the use of calcium analysis in the in-vivo dental erosion model.

• Hjortsjø, Carl; Dahl, Jon Einar; Saxegaard, Erik & Young, Alix (2008). HET-CAM testing of diluted hydrofluoric acid solutions. Vis sammendrag

  It has been suggested that diluted hydrofluoric acid (HF) solutions (≤ 0.2%) can reduce enamel dissolution in a clinical dental erosion model. The toxic effect of concentrated solutions of HF is well known. The possible effects of low concentrations of HF are less well known. This study aimed to examine the irritative effects of four HF solutions (1%, 0.2%, 0.1% and 0.05%) using the Hen’s Egg Test - chorioallantoic membrane (HET-CAM) (Kalweit et al., Toxicol in Vitro 1990;4:702-706). The hypothesis to be tested was that low concentrations of HF do not provoke any response on the blood vessels of the CAM of fertilized hens’ eggs. The CAM was accessed by careful dissection through the egg shell. 300 μl of the test solutions was dripped on the CAM under constant examination using a macroscope. The time for appearance of haemorrhage, vessel lysis and coagulation in the membrane was recorded. An average irritation score (IS) for each test solution (n=24 eggs in total) was calculated and a score was assigned: 0-0.9 = non irritant, 1-4.9 = slight irritant, 5-8.9 = moderate irritant and 9-21 = strong irritant. Mean time to coagulation (mtc100) was also calculated, values below 100 were classified as R41 - severely eye irritating. Results showed that 0.05% HF scored as slightly irritant (IS=3.26), 0.1% HF as moderately irritant (IS=7.49) while both 0.2% and 1% HF were recorded as strongly irritant (IS=9.92 and 12.22 respectively). 0.1%, 0.2% and 1% HF were classified as severe eye irritants (mtc100= 75, 80 and 50). In conclusion all four HF solutions provoked reactions on the chorioallantoic membrane of fertilized hen’s eggs. Care must therefore be taken when using diluted HF solutions under experimental clinical conditions.

• Hjortsjø, Carl; Jonski, Grazyna; Rølla, Gunnar; Thrane, Per Stanley; Saxegaard, Erik & Young, Alix (2008). Short term effect of NaF-, SnF2- and dilute HF-treatments on enamel erosion-like lesions in vivo. Vis sammendrag

  Dental erosion is a clinical problem in many countries today partly due to increased exposure to dietary acids. Citric acid for example is commonly found in fruit juices, mineral water, flavoured teas and bottled still water. Recent studies have shown that several acidic fluoride preparations hold promise in the prevention and treatment of dental erosion. This study aimed at comparing the effect of sodium fluoride (NaF, pH 7.3), stannous fluoride (SnF2, pH 2.9) and dilute hydrofluoric acid (HF, pH 2.0) solutions, on enamel dissolution in an experimental in vivo model as described previously (Young et al., Eur J Oral Sci 2006;114;180-183). Four healthy anterior teeth in each subject (n=29) were isolated using plastic strips and a light bodied impression material for complete palatal coverage. The labial surfaces of the test teeth were exposed to 5 ml citric acid (0.18%) using a peristaltic pump (6 ml/min), before (etch I) and 5 min after (etch II) application of test fluoride preparations. The acid was collected in a test tube for later analysis. NaF, SnF2 or HF solutions (all 0.1 M F-) were applied to the labial surfaces of the teeth for 1 min using a peristaltic pump (6 ml/min). Enamel dissolution was examined by measuring calcium content in the citric acid using atom absorption spectrometry. Mean values for etch I minus etch II were calculated and statistical analysis with the Bonferroni t-test for between group comparisons. HF and SnF2 gave mean calcium reductions of 0.37 ppm (76%) and 0.67 ppm (68%) respectively (NS). NaF gave no calcium reduction (-0.34 ppm (-52%). In conclusion, while neutral NaF had no protective effect 5 min after treatment, SnF2 and dilute HF markedly reduced calcium loss.

• Mutluay, Mustafa Murat; Oguz, Serra; Fløystrand, Finn; Saxegaard, Erik; Dogan, Arife & Bek, Bulent [Vis alle 7 forfattere av denne artikkelen] (2008). A prospective study on the clinical performance of polysiloxane soft kiners. Dental Materials. ISSN 0109-5641. 27, s. 440–447.
• Mutluay, Mustafa Murat; Oguz, Serra; Fløystrand, Finn; Saxegaard, Erik; Dogan, Arife & Bek, Bulent [Vis alle 7 forfattere av denne artikkelen] (2007). A prospective study on the clinical performance of polysiloxane soft liners: one-year results.
• Hjortsjø, Carl; Jonski, Grazyna; Saxegaard, Erik; Thrane, Per Stanley & Young, Alix (2007). Effect of time on dilute hydrofluoric acid-treatments of enamel in vivo. Vis sammendrag

  Dental erosion is currently considered to be one of the main reasons for tooth wear. It has been suggested in an in vivo study that hydrofluoric acid (HF) successfully reduces enamel dissolution and protects enamel against acidic challenges. The aim of this study was to evaluate the protective effect of 0.2% HF solution over time, using a newly established indirect experimental in vivo model. Test subjects (n=28) took part in this study. Healthy anterior teeth (n=107) with intact pellicle were kept dry during the experiment using cotton rolls and saliva suction, and isolated using plastic strips and a light-bodied impression material for complete coverage of palatinal surfaces. The labial surfaces were exposed to diluted citric acid (10mmol/l) using a peristaltic pump (5ml, 6ml/min). The acid was collected in a test tube before (etch I) and after 24 h (n=54 teeth) or 7 days (n=53 teeth) (etch II), following application of aqueous 0.2% HF solution (6ml, 6ml/min). The teeth were rinsed for 5s with water after both etch I and II. Enamel dissolution was examined by assessment of calcium content in the citric acid of etch I and II using atom absorption spectroscopy. The reductions in calcium content in the citric acid between etch I and etch II were calculated for each tooth (p< 0.05). A significant reduction in post HF-treatment calcium loss was observed for both time periods, though the protective effect decreased with time. Mean percent calcium loss reduction was 49 (S.E. 3.6) for the 24-h group and 29 (S.E. 5.4) for the 7-d group. The results suggest that 0.2% HF has a protective effect on sound enamel that lasts for at least one week.

• Rølla, Gunnar; Jonski, Grazyna; Saxegaard, Erik & Young, Alix (2006). Effect of acidified fluoride solutions on dissolution rate of enamel in erosive acid. Vis sammendrag

  It is well known that aqueous solutions of SnF2 and TiF4 reduce the dissolution rate of enamel in erosive acid, and it has recently been shown that highly diluted solutions of hydrofluoric (HF) acid shares this property. All these solutions have “natural” acidity, and induce formation of calcium fluoride on enamel. Objective: To compare the dissolution-reducing capacity of HF with NaF acidified with HCl or H3PO4. The latter are also known to cause calcium fluoride formation. Material and methods: The diluted HF and acidified NaF-solutions all had a pH of 3 and contained 0.09% fluorine. Enamel samples (n=18) were individually pre-treated with 10ml of 0.01M citric acid for 10 min (Etch 1) and the amount of calcium released measured by atomic absorption. These enamel samples were subsequently treated with one of the fluoride containing solutions for 10 min, and again etched and analyzed as before (Etch 2). The difference between Etch 1 and Etch 2 was assumed to be due to the respective fluoride treatments. Data were analysed using one way ANOVA. Results: It was found that the HF-treatment was more effective than treatment with acidified NaF-solutions. Mean reductions were HF - 50%, NaF with H3PO4 - 30% (p=0.26) and NaF with HCl - 20% (p=0.03). Conclusion: As HF contains mainly un-dissociated molecules at pH 3, it is suggested that these very small, uncharged molecules of covalently bound H and F, can diffuse rapidly together into enamel, opposed to ionic F-Na+ in acidified solutions. The HF molecules can form calcium fluoride as follows: CaHPO4 + 2HF > CaF2 + H2PO4 + H+. The acids used with NaF are fully dissociated and these protons are free to individually penetrate into enamel and cause mineral loss. The movement of fluoride is however restricted due to its high affinity for Na.

• Young, Alix ; Thrane, Per Stanley; Saxegaard, Erik; Hjortsjø, Carl; Jonski, Grazyna & Rølla, Gunnar (2006). Preventive effect of acidic fluoride treatments on erosion-like lesions. Vis sammendrag

  Dental erosion is an increasingly important clinical problem and treatment of serious cases often both difficult and expensive. Prevention and treatment involving fluoride application in various forms has been studied both in vitro and in situ. Objectives: To compare the effect of acidic fluoride against neutral fluoride on erosion-like lesions using an in vivo model. Methods: Four healthy anterior teeth in each subject (n=40) with intact pellicle were individually exposed to citric acid (100mmol/l or 10mmol/l) applied using a peristaltic pump (5ml, 7ml/min) and the acid collected in test tubes before (etch I) and after (etch II) applications of the respective fluoride preparations. Fluoride toothpastes (0.15% NaF and 0.4% SnF2) were applied to the labial surfaces with a soft brush (4 x 1min) with gentle water rinsing between applications. Fluoride solutions (0.15% HF, pH 2.5 and 0.35% NaF, pH 8.8) were dripped continuously on the labial surfaces of each tooth (1 min, 4 ml/min), followed by 5 s water rinse/tooth. Subjects rested 1 min prior to etch II. Enamel solubility was examined by assessment of calcium content (Ca) in etch I and II using atom absorption spectroscopy. Results: Toothpastes – SnF2 provided far better protection of the enamel than NaF reducing Ca-loss by 20% when the weakest acid was used. NaF resulted in large Ca-loss with both acid concentrations. Solutions – HF reduced Ca-loss by 60 % whereas the NaF resulted in large Ca-loss with both acid concentrations. Conclusions: The experiments showed that SnF2 and highly dilute HF are promising preventive treatment measures for dental erosion.

• Young, Alix ; Thrane, Per Stanley; Saxegaard, Erik; Hjortsjø, Carl; Jonski, Grazyna & Rølla, Gunnar (2006). Preventive effects of acidic fluoride treatments on erosion-like lesions.
• Saxegaard, Erik; Young, Alix ; Hjortsjø, Carl; Jonski, Grazyna & Rølla, Gunnar (2006). Dentin pre-treatment with diluted hydrofluoric acid reduces solubility. Vis sammendrag

  We have previously reported that enamel and cementum are protected against dissolution in citric acid by brief pre-treatments with highly diluted hydrofluoric acid (HF, pH=3). (Saxegaard et al IADR 2005). Deposition of calcium fluoride-like material (hereafter CaF2) was shown to account for the effect which was also concentration dependent. However, advanced cases of dental erosion may penetrate the enamel and reach the dentin. Objective: To examine the effect of similar pre-treatments on the solubility of dental dentin. Methods: In 42 intact human third molars the dentin was exposed by cutting off the tooth-enamel using a diamond bur. The roots were cut off and the exposed cervical surface covered with acid-resistant nail varnish. In 6 groups each specimen was treated with 0.1M citric acid (10ml, 30min) before (etch-I) and after (etch-II) treatment with the different HF-solutions ((0.1%-1.0%, 10ml, 10min). Samples were briefly rinsed in deionised water between treatments. Dissolution of dentin was assessed by comparing the calcium content in etch I and II using atomic absorption spectroscopy. Remaining dentin samples similarly underwent etch I and various HF-treatments before examination in EDXA and SEM (Phillips type XL30 ESEM). Results: Treatment with 0.1%HF reduced the solubility of dentin by ~80%, whereas 0.2-1.0%HF gave reductions of 93-98%. This reduction was somewhat lower than for cementum but higher than for enamel. SEM images showed that dentin was covered with a CaF2, whereas results of EDXA analyses were inconsistent. Conclusion: As with enamel and cementum the CaF2 produced on dentin in the presence of HF appears to exert a protective effect against clinical erosion. It can be speculated that the effect may be due to the low pH at which the CaF2 was formed. It seems likely that the nature of the phosphate contamination of the CaF2 determines its rate of dissolution in erosive acids.

• Rølla, Gunnar; Young, Alix ; Saxegaard, Erik & Jonski, Grazyna (2006). On calcium fluoride formation on enamel. Vis sammendrag

  A controversy exists concerning the role of calcium fluoride deposited on enamel during fluoride treatments. Some authors maintain that such calcium fluoride can protect enamel surfaces from erosive acids, whereas others claim that calcium fluoride is soluble in such acids. We have shown that calcium fluoride formed on enamel at neutral pH after exposure to 0.5 mol/l of an aqueous solution of NaF for 24 h, was unable to protect the enamel against 0.1 mol/l of citric acid for 30 min, whereas a similarly treated enamel (0.5 mol/l of an aqueous solution of hydrofluoric acid for 10 min with a pH of 3), did protect the enamel almost completely. The aim of this abstract was to discuss these results. It is suggested that the difference in dissolution rates may depend on the nature of the phosphate contaminations found in calcium fluorides formed on enamel. These phosphate contaminations originate from the enamel and are probably in the form of calcium phosphates. More acid-soluble phosphates are available on the enamel surface at pH 7, than at pH 3. These are dibasic/monobasic phosphates, and monobasic phosphate/phosphoric acid, respectively. It is also suggested that undissociated HF which is the major component of hydrofluoric acid at pH 3, may have an important role in calcium fluoride formation as previously shown [Larsen and Jensen: Caries Res 1986; 20:56-64]. It is thought that HF can probably get closer to the intercrystalline regions on the enamel due to its uncharged state, than the charged species of fluoride. The use of NaF in acidic fluoride solutions may be unfortunate in this respect, as Na inhibits the formation of HF due to its extremely high affinity for fluorine.

• Young, Alix ; Thrane, Per Stanley; Saxegaard, Erik; Jonski, Grazyna & Rølla, Gunnar (2006). A clinical model for evaluating fluoride treatment of erosion-like lesions. Vis sammendrag

  Dental erosion is an increasingly important clinical problem and treatment of serious cases often both difficult and expensive. Prevention and treatment involving fluoride application in various forms has been studied both in vitro and in situ. The present in vivo model was developed to examine the effect of fluoride on erosion-like lesions. Results are presented for two fluoride toothpastes. Material and methods: Four healthy anterior teeth in each subject (n=20) with intact pellicle were exposed to diluted citric acid (100mmol/l or 10mmol/l) applied using a peristaltic pump (5 ml, 7 ml/min) and the acid collected in a test tube before and after application of the respective toothpastes (etch I and etch II). Toothpastes (neutral 0.15 % NaF and acidic 0.4 % SnF2) were applied to the labial surfaces with a soft brush (4 x 1min) with gentle water rinsing between applications. Each subject had one pair of teeth treated with each of the test toothpastes. Enamel solubility was examined by assessment of calcium content in the citric acid applied before and after the treatment with toothpaste. Results: SnF2-toothpaste reduced the solubility of teeth in vivo by 20 % (etch II < etch I). NaF-toothpaste provided no protection (etch II > etch I). Conclusion: This model promises the possibility for studying the effect of preventive treatment measures for dental erosion. SnF2 toothpaste is more effective than NaF in preventing loss of enamel due to acid attack.

• Rølla, Gunnar; Lamolle, Sebastien Francis; Young, Alix ; Jonski, Grazyna & Saxegaard, Erik (2005). Comparison of the properties of CaF2-like particles formed under different conditions. Vis sammendrag

  Treatment with dilute hydrofluoric acid (HF) induces the immediate formation of a continuous layer of CaF2-like particles on dental enamel. This is associated with a marked cariostatic effect. More recently it was observed that this treatment reduced the solubility of enamel in erosive acid and that this effect was concentration dependent. It has been suggested that deposition of CaF2-like material may provide protection of the underlying enamel and that the amount of such material formed could be essential. OBJECTIVE: To examine the CaF2-like particles formed by treatment of enamel with either neutral or acidic fluoride. METHOD: Tooth enamel specimens (n=6) were treated with either1% NaF (0.5M F-) at neutral pH for 24h, or 1% HF (0.5M F-) for 10 min. The solubility of the CaF2-like particles formed on the specimens was examined by exposing them to 0.1M citric acid for 30 min. Acid was analysed for Ca2+ by atomic absorption spectroscopy. The enamel samples were also examined by atomic force microscopy (AFM) and by SEM. RESULTS: It was found that enamel solubility was reduced 96% by HF and 6.2% by NaF. Effect of NaF was not significantly different from the control (p<0.000). AFM showed that the amount of particles formed during the two different treatments was of the same order of magnitude, that they covered the whole surface of the enamel and that they had a similar particle size of ~20 nm diameter. SEM showed that a complete layer of CaF2-like material covered the enamel. HF-treatment gave particles which were resistant to 0.1M citric acid for 30 min and to KOH for 24h (here some of the material was lost). CONCLUSION: HF treatment thus seems to give a very resistant enamel surface, presumably due to low solubility of the CaF2-like material formed under these conditions.

• Rølla, Gunnar; Saxegaard, Erik; Jonski, Grazyna & Young, Alix (2005). The solubility-reducing effect on teeth by SnF2. Vis sammendrag

  It is well established that stannous fluoride (SnF2) reduces the solubility of teeth, whereas stannous chloride or sodium fluoride salts have no such effect. Objective: To examine whether fluoride at the concentration and pH at which it is present in 0.4% SnF2, can reduce solubility of teeth without the presence of Sn2+. As the pH of an aqueous solution of 0.4 % SnF2 is 3, due to an immediate hydrolysis reaction (Sn2+ +2H2O > Sn(OH)2 +2H+), it appears that the fluoride part of the SnF2-molecule is always exposed to acidic conditions. This fluoride is thus present as partly non-dissociated hydrofluoric acid (HF). Methods: Whole intact human premolars were pre-treated with 0.4% SnF2 or 0.1% HF (10 min) and then exposed to 0.1M citric acid or 0.01M HCl (30 min). Tooth solubility after acid exposure was estimated by measuring the [Ca2+] in the acids, by atomic absorption spectroscopy. Teeth were also examined by EDXA and SEM (Phillips type XL30 ESEM). Results: Solubility reduction by both 0.4% SnF2 and 0.1% HF were similar in both acids, and not statistically different. This indicated that the fluoride part of SnF2 alone accounts for its solubility reduction and that Sn2+ appears only to provide a suitable pH for the fluoride. The teeth treated with HF were covered with dense layers of CaF2, which probably caused the solubility reduction in acids. Conclusion: It is thus possible to separate the solubility reduction by stannous fluoride from stannous ions. As stannous ions may cause discoloration of teeth, and tend to be both oxidized and hydrolyzed during storage, the aqueous solution of HF may have advantages and be of potential interest in the prevention of dental erosions.

• Saxegaard, Erik; Jonski, Grazyna; Young, Alix & Rølla, Gunnar (2005). Effect of pre-treatment with dilute hydrofluoric acid on enamel solubility. Vis sammendrag

  It is reported in another paper at this meeting (Rölla et al.) that an aqueous solution of 0.1% hydrofluoric acid (HF) reduced the solubility of human teeth in 0.1M citric acid and in 0.01M HCl to the same extent as 0.4% SnF2. It was suggested that 0.1% HF was the part of the SnF2-molecule which reduces the solubility of teeth in aqueous SnF2, and that Sn2+ only provided a suitable pH for the reaction (pH 3). Objective: To examine the solubility reducing effect of a series of aqueous solutions of HF, on human dental enamel. Methods: [HF] ranged from 0.1% to 1.0%. Intact human third molars (n=36) were cut at the collum and the exposed dentin was covered with acid-resistant nail varnish. All teeth were initially treated with 10ml of 0.1M citric acid for 30 min, rinsed in deionised water and dried. The acid solutions were kept until Ca analysis (control). Six teeth were pre-treated with 10 ml of the 6 different concentrations of HF for 10 min. The teeth were then rinsed briefly in de-ionized water and dried. The pre-treated specimens were subsequently exposed to 10ml of 0.1M citric acid for 30 min. The solubility of the teeth was determined by measuring [Ca2+] in the acids before and after HF pre-treatment, using atomic absorption spectroscopy. The enamel was examined by EDXA and SEM (Phillips type XL30 ESEM). Results: Pre-treatment with 0.1% HF reduced the solubility of dental enamel by 50-60%, whereas 0.2-1.0% HF gave reductions of 90-100%. Conclusion: The pre-treated teeth were covered by a dense layer of a calcium fluoride-like material. Treatment with non-dissociated dilute aqueous solutions of HF may result in the formation of a protective layer on the enamel which potentially reduces the effects of erosive attack.

• Saxegaard, Erik; Jonski, Grazyna; Young, Alix & Rølla, Gunnar (2005). Dilute hydrofluoric acid reduces solubility of cementum in citric acid. Vis sammendrag

  It has been reported that pre-treatment with diluted aqueous solutions of hydrofluoric acid (HF) reduced the solubility of human dental enamel in 0.1M citric acid between 50-100% (Saxegaard et al #3272 IADR 2005). The effect was concentration dependent. OBJECTIVE: To examine the corresponding solubility reducing effect on dental cementum by a similar series of aqueous solutions of HF. METHODS: [HF] ranging from 0.1% to 1.0% was examined. Intact human third molars (n=36) were cut at the collum and the exposed cervical dentin and pulp was covered with acid-resistant nail varnish while the root cementum was carefully cleaned and lightly polished with pumice, using a rubber cup in a slow speed handpiece. In six groups (n=6) each specimen was initially treated in 0.1M citric acid (10ml, 30 min), rinsed briefly with water and dried. Samples were then pre-treated with different concentrations of HF (10ml, 10min), rinsed and dried as before, and then re-exposed to 0.1M citric acid (10ml, 30min). Solubility of the cementum was determined by measuring [Ca2+] using atomic absorption spectroscopy. Reduction in dissolution between the first and second exposure was assumed to be due to the HF-treatment. Additional cementum samples treated with HF dilutions were examined by EDXA and SEM (Phillips type XL30 ESEM). RESULTS: HF in the range 0.1-1.0% reduced the solubility of cementum by 97-100%. The pre-treated cementum was covered with a dense layer of a calcium fluoride-like material. Since cementum contains more protein than enamel, and the mineral crystals are smaller than in enamel, the mechanism of dissolution of cementum is most likely different from that of enamel. CONCLUSION: It appears that the calcium fluoride produced in the presence of HF is acid resistant and may exert a protective effect against clinical erosion of the cementum.

• Jonski, Grazyna; Saxegaard, Erik; Young, Alix & Rølla, Gunnar (2005). A comparison of biological activities of three SnF2-containing toothpastes. Vis sammendrag

  Freshly made aqueous solutions of SnF2 exhibit a solubility-reducing effect on enamel in erosive acids, and can inhibit oral malodour by interaction with volatile sulphur compounds (VSC) which may form in the mouth. It is unclear to what extent these biological activities are present in SnF2-containing toothpastes, it is known that both the [F-] and [Sn2+] may be reduced. OBJECTIVE: The aim of the present study was to assess the biological activities outlined above in three commercial toothpastes containing SnF2 in slightly different concentrations. METHOD: Three toothpastes containing 0.14%, 0.15% and 0.10% F respectively were tested. Aqueous extracts of the toothpastes (toothpaste/water 1:3) were incubated 1 h and centrifuged at 10000 x g for 30 min. Solubility reduction: hydroxyapatite granules (HA) were treated with the respective toothpaste extracts for 10 min, washed, dried and exposed to 10 ml 0.1M citric acid for 30 min. Solubility was compared with that of untreated HA by calcium analyses of the acid using atomic absorption spectroscopy. Inhibition of VSC formation: Human saliva (n=6) was incubated overnight at 37oC, resulting in production of copious amounts of VSC. 10-ul aliquots of the toothpaste extracts were added to 1-ml saliva samples, and the VSC in the tubes compared with the untreated control using gas chromatography. RESULTS: Solubility reduction was about 40 % for the toothpastes. Toothpaste B was numerically best, followed by A and C, but there were no statistically significant differences. This reflects probably the different fluoride concentrations. Anti-VSC effects were of the same order of magnitude with A, B and C inhibiting VSC 97-99%, indicating available Sn2+. CONCLUSION: The experiments showed SnF2 toothpaste can be a vehicle for solubility-reducing activity, and that Sn2+ is also available.

• Fløystrand, Finn; Karlsen, Kjell; Saxegaard, Erik & Ørstavik, Jon Sigurd (1986). Effects on retention of reducing the palatal coverage of complete maxillary dentures. Acta Odontologica Scandinavica. ISSN 0001-6357. 44(83).

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