Biological and physical properties of calcium hydroxide-based pulp-capping materials and their modifications.

PURPOSE: To evaluate the biological and physical properties of calcium hydroxide-containing pulp-capping materials and their modifications with different solutions and antioxidant Resveratrol (RES) addition. METHODS: Calcium hydroxide+distilled-water:C, calcium hydroxide+saline:S, calcium hydroxide+synthetic tissue fluid:STF, Dycal:D, calcium hydroxide+distilled-water+RES:C+RES, calcium hydroxide+saline+RES:S+RES, calcium hydroxide+synthetic tissue fluid+RES:STF+RES, Dycal+RES:D+RES were tested. Cytotoxicity was determined by WST-1. Antibacterial-activity was evaluated by agar-diffusion. The water-absorption and solubility were examined for ISO-6876 and ISO-3107. The color-change was evaluated by spectrophotometer. Radiopacity was evaluated for ISO-6876 and ISO-9917. The normal distribution and homogeneity were determined and comparisons were made with appropriate analysis and post hoc tests (P < 0.05). RESULTS: The highest cell-viability was determined in the C+RES and the lowest was in D and D+RES after 24 h (P < 0.0001). RES-addition increased cell-viability and the highest rate was detected in C+RES, S+RES and STF+RES after 48 h (P < 0.0001). A limited inhibition-zone against Streptococcus mutans was detected in D and D+RES. RES-addition did not change the water-absorption in S and STF or the solubility in S group. CONCLUSION: RES-addition may be used to increase the biocompatibility of calcium hydroxide without any adverse effect on physical properties. Saline may be the first choice as a mixing solution.

The effects of extended polymerization time for different resin composites on reactive oxygen species production and cell viability.

PURPOSE: The present study was conducted to determine oxidative stress and cell viability after contact with resin composites polymerized for different times. METHODS: Disk-shaped specimens of Admira Fusion, Ceram X One Universal, Solare x and Filtek Z550 (n = 12) were prepared, and two subgroups with polymerization times of 20 and 40 s were employed. The specimens were incubated with mouse fibroblast cells for 48 and 72 h, and changes in reactive oxygen species (ROS) production and cellular viability were determined by an assay with a cell-permeable fluorescent dye, 2',7'-dichlorodihydrofluorescein diacetate (H2DCF-DA), and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, respectively. RESULTS: At 72 h, ROS production in the presence of Admira Fusion polymerized for 40 s was reduced relative to that in the presence of Admira Fusion polymerized for 20 s (P < 0.05). Cell viability was maximal in the Admira Fusion and Solare x groups and there was no difference relative to the control group at 48 h. Cell viability was higher in the Admira Fusion and Solare x groups polymerized for 40 s than for the same materials polymerized for 20 s at 72 h (P < 0.05). CONCLUSION: Extension of the polymerizaton time has a material-specific effect and may be used as a strategy to increase the biocompability of resin composites.

Targeted next-generation sequencing as a diagnostic tool in gastrointestinal system cancer/polyposis patients.

BACKGROUND: Recent advances in next-generation sequencing (NGS) technology have enabled multigene testing and changed the diagnostic approach to hereditary gastrointestinal cancer/polyposis syndromes. The aim of this study was to analyze different cancer predisposition genes in hereditary/sporadic gastrointestinal cancer/polyposis. METHODS: Cancer predisposition genes were analyzed with an Illumina MiSeq NGS system in 80 patients with gastrointestinal cancer/polyposis who were examined between the years 2016 and 2019. Deletion/duplication analysis of MLH1, MSH2, and EPCAM genes was performed by using the multiplex ligation-dependent probe amplification method. RESULTS: Germline testing of hereditary cancer-related genes was performed in 80 patients with gastrointestinal cancer/polyposis. A total of 30 variants in 30 cases (37.5%) were assessed as pathogenic/likely pathogenic. A total of 19 heterozygous variants were assessed as variants of uncertain clinical significance in 17 cases (21.25%) and 18 (22.5%) novel variations (9 pathogenic/likely pathogenic, 9 variants of uncertain significance) were determined. In 4 (5%) cases, multiplex ligation-dependent probe amplification detected deletions in MLH1, MSH2, and EPCAM genes. CONCLUSION: The accumulation of analyses with multigene testing will increase the available data for cancer predisposition genes in hereditary gastrointestinal cancer/polyposis. Educational campaigns for prevention, efficient screening programs, and more personalized care based on the profile of individual patients are necessary.

The improvement of biocompatibility of adhesives : The effects of resveratrol on biocompatibility and dentin micro-tensile bond strengths of self-etch adhesives.

OBJECTIVE: The aim of this in vitro study is to evaluate the effects of resveratrol (RES) addition on the cytotoxicity and microtensile bond strength (µTBS) of different adhesives. MATERIALS AND METHODS: Five self-etching adhesives (G-aenial Bond-GC, Optibond All in One-Kerr, Gluma Self Etch-Kulzer, Clearfil S3 Bond-Kuraray, and Nova Compo-B Plus-Imicryl) were tested. They were applied to L-929 cell culture by the extract method. In the test groups, 0.5 µM RES (Sigma-Aldrich) was added into the medium. Cell viability was assessed by MTT assay after 24 h. Human extracted third molars were used for µTBS test (n = 7). The adhesives with or without 0.5 µM RES addition were applied on dentin surfaces. A composite build-up was constructed. Then, the specimens were sectioned into multiple beams with the non-trimming version of the microtensile test and subjected to microtensile forces. Statistical analysis was performed using ANOVA and post hoc Tukey test (p Ë‚ 0.05). RESULTS: The extracts of all adhesives decreased the cell viability. However, RES addition increased the cell viability in all groups (p Ë‚ 0.05). RES addition did not cause any decrease in µTBS values of the adhesives compared to baseline. Optibond All in One showed the highest µTBS after RES addition. It was followed by Clerafil S3 Bond and Nova Compo-B Plus. No difference was determined between the Optibond All in One and Clearfil S3 Bond. There was difference between Optibond All in One and Nova Compo-B Plus (p Ë‚ 0.05). CONCLUSION: RES addition may improve the biocompatibility without causing negative influence on µTBS of the adhesives. CLINICAL RELEVANCE: RES addition has clinical applicable potential to overcome the adverse biocompatibility of adhesives.

Procrastination and predictor variables among a group of dental students in Turkey.

The aim of this study was to assess the prevalence of procrastination among a group of Turkish dental students and to determine the predictors and consequences of procrastination. A total number of 273 females and 179 males (aged between 18 and 28) were included in the study. Tuckman procrastination scale, Academic Life Satisfaction Scale, Concern over Mistake Scale, Poor Time Management Scale, Self-Doubt Scale, Irrational Beliefs about Studying Scale, Positive and Negative Affect Schedule and Life Satisfaction Scale were used to gather data. Results indicated that 50% of participants were more likely to procrastinate their academic assignments or tasks. Procrastination score did not differ according to gender. The findings suggested that procrastinating students had a higher level of poor time management, self-doubt and irrational beliefs about studying, and poor academic performance and well-being than their non-procrastinating counterparts. Preventive strategies are necessary to overcome procrastination which affects the academic achievement, satisfaction, and well-being of dental students.

In vivo performance of different scaffolds for dental pulp stem cells induced for odontogenic differentiation.

This study was designed to determine the in vivo performance of three different materials as scaffolds for dental pulp stem cells (DPSC) undergoing induced odontogenic differentiation. An odontogenic medium modified by the addition of recombinant human bone morphogenetic protein 2 was used in the experimental groups to induce differentiation. Mesenchymal stem cell medium was used in the control groups. DPSC were transplanted onto the backs of mice via three scaffolds: copolymer of L-lactide and DL-lactide (PLDL), copolymer of DL-lactide (PDL) and hydroxyapatite tricalcium phosphate (HA/TCP). The expression levels of dentin sialo-phosphoprotein (DSPP), dentin matrix protein-1 (DMP1), enamelysin/matrix metalloproteinase 20 (MMP20) and phosphate-regulating gene with homologies to endopeptidases on X chromosome (PHEX) were analysed using RT-PCR. The expressions in the experimental groups were compared to those in the control groups. The transcript expressions at 6 and 12 weeks were significantly different for all scaffolds (p < 0.05), except for the expression of DSPP in the PLDL group with regard to the time variable. Although there was a decrease in the expression of enamelysin/MMP20 in PLDL and HA/TCP at 12 weeks, all other expressions increased and reached their highest level at 12 weeks. The highest DSPP expression was in the PDL group (p < 0.05). The highest expression of DMP1 was detected in the HA/TCP group (p < 0.05). The highest expression of PHEX was in the PLDL group (p < 0.05). Consequently, PLDL and PDL seemed to be promising scaffold candidates for odontogenic regeneration at least as HA-TCP, when they were applied with the DPSC induced for odontogenic differentiation.

A 3-year randomized clinical trial evaluating two different bonded posterior restorations: Amalgam versus resin composite.

OBJECTIVE: To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. MATERIALS AND METHODS: This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months. RESULTS: Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3(rd) year, overall "Bravo" rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3(rd) year evaluation (P < 0.05). CONCLUSIONS: Within the limitation of this study, both resin composite and bonded amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities.

Medium modification with bone morphogenetic protein 2 addition for odontogenic differentiation.

The aim of this study was to evaluate whether medium modification improves the odontogenic differentiation of human dental pulp stem cells (DPSC) in vitro and in vivo. DPSC isolated from human impacted third molar teeth were analysed for clusters of differentiation with flow cytometry. Odontogenic differentiation was stimulated by medium modification with the addition of bone morphogenetic protein 2 (BMP2). The expression of dentin sialophosphoprotein, dentin matrix protein 1, enamelysin/matrix metalloproteinase 20 and the phosphate-regulating gene with homologies to endopeptidases on the X chromosome of the cells were analysed with RT-PCR at 7, 14 and 21 days. Then, DPSC were transplanted on the back of immunocompromised mice via a hydroxyapatite tricalcium phosphate scaffold, and the structure of the formed tissue was investigated. The cells were identified as mesenchymal stem cells with a 98.3% CD73 and CD90 double-positive cell rate. The increase in mineralization capacity and expression of human enamel-dentin specific transcripts proportional to the culture period were determined after differentiation. Six weeks after transplantation, an osteo-dentin matrix was formed in the group in which odontogenic differentiation was stimulated, and the odontogenic characteristics of the matrix were confirmed by histological examination and RT-PCR analysis. Odontogenic differentiation of the isolated and characterized human DPSC was improved with medium modification by the addition of BMP2 in vitro and in vivo. The defined medium and applied technique have a potential use for forming reparative dentin in the future, but the effects of the method should be investigated in long-term studies.

Medium modification with bone morphogenetic protein 2 addition for odontogenic differentiation

Abstract The aim of this study was to evaluate whether medium modification improves the odontogenic differentiation of human dental pulp stem cells (DPSC) in vitro and in vivo. DPSC isolated from human impacted third molar teeth were analysed for clusters of differentiation with flow cytometry. Odontogenic differentiation was stimulated by medium modification with the addition of bone morphogenetic protein 2 (BMP2). The expression of dentin sialophosphoprotein, dentin matrix protein 1, enamelysin/matrix metalloproteinase 20 and the phosphate-regulating gene with homologies to endopeptidases on the X chromosome of the cells were analysed with RT-PCR at 7, 14 and 21 days. Then, DPSC were transplanted on the back of immunocompromised mice via a hydroxyapatite tricalcium phosphate scaffold, and the structure of the formed tissue was investigated. The cells were identified as mesenchymal stem cells with a 98.3% CD73 and CD90 double-positive cell rate. The increase in mineralization capacity and expression of human enamel-dentin specific transcripts proportional to the culture period were determined after differentiation. Six weeks after transplantation, an osteo-dentin matrix was formed in the group in which odontogenic differentiation was stimulated, and the odontogenic characteristics of the matrix were confirmed by histological examination and RT-PCR analysis. Odontogenic differentiation of the isolated and characterized human DPSC was improved with medium modification by the addition of BMP2 in vitro and in vivo. The defined medium and applied technique have a potential use for forming reparative dentin in the future, but the effects of the method should be investigated in long-term studies.

In vivo performance of different scaffolds for dental pulp stem cells induced for odontogenic differentiation

Abstract This study was designed to determine the in vivo performance of three different materials as scaffolds for dental pulp stem cells (DPSC) undergoing induced odontogenic differentiation. An odontogenic medium modified by the addition of recombinant human bone morphogenetic protein 2 was used in the experimental groups to induce differentiation. Mesenchymal stem cell medium was used in the control groups. DPSC were transplanted onto the backs of mice via three scaffolds: copolymer of L-lactide and DL-lactide (PLDL), copolymer of DL-lactide (PDL) and hydroxyapatite tricalcium phosphate (HA/TCP). The expression levels of dentin sialo-phosphoprotein (DSPP), dentin matrix protein-1 (DMP1), enamelysin/matrix metalloproteinase 20 (MMP20) and phosphate-regulating gene with homologies to endopeptidases on X chromosome (PHEX) were analysed using RT-PCR. The expressions in the experimental groups were compared to those in the control groups. The transcript expressions at 6 and 12 weeks were significantly different for all scaffolds (p < 0.05), except for the expression of DSPP in the PLDL group with regard to the time variable. Although there was a decrease in the expression of enamelysin/MMP20 in PLDL and HA/TCP at 12 weeks, all other expressions increased and reached their highest level at 12 weeks. The highest DSPP expression was in the PDL group (p < 0.05). The highest expression of DMP1 was detected in the HA/TCP group (p < 0.05). The highest expression of PHEX was in the PLDL group (p < 0.05). Consequently, PLDL and PDL seemed to be promising scaffold candidates for odontogenic regeneration at least as HA-TCP, when they were applied with the DPSC induced for odontogenic differentiation.

The protective effect of resveratrol against dentin bonding agents-induced cytotoxicity.

This study was designed to evaluate the cytotoxicity of four dentin bonding agents and the effects of an antioxidant addition. Group A: G-aenial Bond, Group B: Optibond All in One, Group C: Gluma Self Etch and Group D: Clearfil S(3) Bond were added to the medium using extract method. The cells were cultured with or without resveratrol (RES) addition. MTT, reactive oxygen species (ROS), DCF, Comet and 8-OHdG measurements were performed. The agents had a dose-dependent (1:1>1:10>1:20) cytotoxic effect. Considering 1:10 concentration; Group D at 1 h (p<0.01) and Group B and D at 24 h had the weakest cytotoxic effect (p<0.05). After RES addition, the highest cell viability was determined in Groups B+RES and D+RES at 1 h and in Groups A+RES and B+RES at 24 h (p<0.01). The dentin bonding agents induced ROS production and DNA damage regarding to their composition. However, RES addition decreased the indicated parameters.

The prevalence and consequences of burnout on a group of preclinical dental students.

OBJECTIVE: The aim of this study is to investigate the prevalence of burnout among a group of Turkish preclinical dental students, to compare the level of burnout and to determine the consequences in structural equation model. MATERIALS AND METHODS: Preclinical dental students (n = 329, 50.5% of females and 49.5% of males) aged between 18 and 24 took part in the study. Maslach burnout inventory student version, academic satisfaction scale, and personal information sheet were used to gather data. Pearson correlation analyses, t-test, and one-way ANOVA were used for statistical analysis. The proposed theoretical model was tested via observed variable path analysis using maximum likelihood parameter estimation with AMOS 7.0. RESULTS: About 22.3% of students had high level of emotional exhaustion, 16.7% of students had high level of cynicism, and 17.9% of students suffered from high level of reduced academic efficacy. While the students attending the first grade reported higher level of reduced academic efficacy, the students in the third grade reported higher level of emotional exhaustion. Academic workload played an important role in the development of burnout. As consequences of burnout, students with high levels of burnout intended to change their current major and did not to plan to continue to postgraduate education. Students with high level of burnout reported less level of academic satisfaction and academic achievement. CONCLUSIONS: Creating awareness on the burnout of dental students from the preclinical period may be useful for prevention and more compatible dental education environment.

Does post-bleaching fluoridation affect the further demineralization of bleached enamel? An in vitro study.

BACKGROUND: Topical fluoride agents have been shown to be the most effective method in treating demineralized enamel after in-office bleaching treatments. Thus, this study aimed to examine the effects of two different post-bleaching fluoridation agents: 1.5% titanium tetrafluoride (TiF(4)) (9200 ppm) and 2.1% sodium fluoride (NaF) (9500 ppm), on the calcium loss of enamel after an acidic challenge. METHODS: Ten maxillary premolars were sectioned into four pieces and then divided into the following four groups: Group 1: Control, kept in artificial saliva, no treatment; Group 2: 38% hydrogen peroxide (HP); Group 3: 38% HP followed by 1.5% TiF(4); Group 4: 38% HP followed by 2.1% NaF solution. The specimens were subjected to demineralization for 16 days, refreshing the solution every 4 days; that is, on the 4th, 8th, 12th, and 16th days. Calcium ion (Ca(2+)) concentration was determined by an atomic absorption spectrophotometer. Data were analyzed using Friedman and Wilcoxon tests (p = 0.05). RESULTS: The loss of Ca(2+) in each of the test groups was compared with that of the control group, depicting that there was a statistically significant difference among the groups after 4, 8, 12, and 16 days and in total (p < 0.05). The calcium released from the fluoride-applied groups was lower when compared with the 38% HP and control group. At the end of the 16th day, the total amount of calcium released from the TiF(4-)treated samples (9.12 mg/mL) was less than from the NaF-treated samples (13.67 mg/mL) (p < 0.05). CONCLUSIONS: Regarding the results of our in vitro study, the risk of further demineralization was significantly reduced with the use of TiF(4) and NaF after bleaching with 38% HP. TiF(4) was found to be more effective in preventing Ca2+ release owing to acid attack when compared with NaF. In the case of an intra-oral acidic exposure, the use of topical 1.5% TiF(4) and 2.1% NaF agents might be beneficial after bleaching with 38% HP.

Replantation after traumatic avulsion.

The aim of this report is to present the case of an accidentally avulsed maxillary central incisor kept in saline solution from the moment of trauma until its replantation 3 h later in a 13-year-old girl. The avulsed tooth was replanted back into the alveolar socket and splinted with composite resin. Calcium hydroxide intracanal dressing was used to prevent inflammatory root resorption. Radiographic and clinical examinations were performed during 27 months follow-up. During the 15 months follow-up period, the tooth remained in a stable functional position and did not reveal replacement resorption. But mild infraocclusion and root resorption were developed 21 months after replantation. The amount of damage to tooth and supporting structures, emergency treatment and follow-up period play a role in the prognosis of the avulsed tooth. It can be recommended to keep the avulsed tooth in saline solution at least when more appropriate storage media are not on handle immediately.

Susceptibility of enamel treated with bleaching agents to mineral loss after cariogenic challenge.

Objectives. Controversial reports exist whether bleaching agents cause a susceptibility to demineralization. The aim of this study was to compare the calcium loss of enamel treated with different bleaching agents and activation methods. Method and Materials. The specimens obtained from human premolars were treated in accordance with manufacturer protocols; 10% carbamide peroxide, 38% hydrogen peroxide light-activated, 38% hydrogen peroxide laser-activated, and no treatment (control). After cariogenic challenge calcium concentrations were determined by Inductively Coupled Plasma Mass Spectrometry. Results. No differences were found between the calcium loss of the laser-activated group and 10% carbamide peroxide group (p > 0.05). However, the differences between laser-activated and control groups were statistically significant (p < 0.05). The differences between 10% carbamide peroxide and the control group were not significant (p > 0.05). On the other hand, the light-activated group showed a significantly higher calcium loss compared with the other groups (p < 0.05). Conclusions. The results show that bleaching agents may cause calcium loss but it seems to be a negligible quantity for clinical aspects.

Effect of bleaching agents on calcium loss from the enamel surface.

OBJECTIVES: To compare the Ca2+ loss of enamel treated with 38% hydrogen peroxide (HP), 35% HP with light, and 10% carbamide peroxide (CP). METHOD AND MATERIALS: Ten extracted premolars were sectioned buccolingually and longitudinally so that 4 specimens were obtained from each tooth. The specimens were randomly assigned to 1 of 4 groups to receive the following bleaching agents: 38% HP, 35% HP with light, 10% CP, and no agent (control). The specimens were treated with an artificial caries solution (pH 4) for 16 days; the solution was replaced on days 4, 8, 12, and 16. Calcium concentration was determined by an atomic absorption spectrophotometer. Repeated measures ANOVA was performed on concentrations on days 4, 8, 12, and 16. RESULTS: At the end of day 16, calcium ions released per square millimeter were calculated cumulatively as follows: 38% HP group: 27.52 +/- 5.22 microg/mL; 35% HP with light group: 25.15 +/- 4.99 microg/mL; 10% CP group: 19.53 +/- 4.03 microg/mL; control group: 18.35 +/- 4.00 microg/mL. The differences between the control group and the 35% HP with light group and between the control group and 38% HP group were statistically significant. Although demineralization differences were observed between the control group and the 10% CP group, this difference was not significant. CONCLUSIONS: It can be concluded that 35% HP with light and 38% HP may cause significantly more loss of Ca2+ from the enamel surfaces than 10% CP. Also, 10% CP does not vary significantly from the control.

Fluoride release from esthetic restorative materials with and without adhesive.

OBJECTIVE: The purpose of this in vitro study was to compare the effect of surface coating containing fluoride on patterns and amounts of fluoride release from 5 esthetic restorative materials. METHOD AND MATERIALS: Twelve cylinders of each material were prepared in a plexiglass mold. The experimental groups (n = 6) were coated with 1 layer of fluoridated adhesive resin, Prompt L-Pop, while the control groups (n = 6) remained uncoated. Fluoride release into deionized water was measured on days 1, 2, 3, 7, 14, 21, and 28 using an ion analyzer. Results were evaluated statistically using repeated measure analysis of variance and Duncan test. RESULTS: In the uncoated materials, the highest fluoride-releasing material was a resin composite Ariston pHc (140.468 +/- 9.80) followed by Photac-fil (101.200 +/- 5.56), Ketac-fil (91.098 + 4.69), Hytac Aplitip (5.122 +/- 1.00), and Ecusit (0.310 +/- 0.18). Material-coating interaction was found to be significant, but the effect of surface coating was different for each material. Among the coated materials, conventional glass-ionomer cement Ketac-fil released the highest amount of fluoride (93.326 +/- 10.86), followed by Photac-fil (83.666 +/- 4.72), Ariston pHc (53.862 +/- 7.90), Hytac Aplitip (14.634 +/- 2.35), and Ecusit (1.355 +/- 0.29). CONCLUSION: Application of fluoridated adhesive affected fluoride release from each material in varying magnitudes.

Clinical evaluation of indirect resin composite and ceramic onlays over a 24-month period.

The purpose of this study was to compare the clinical performance of ceramic and indirect resin composite onlays over a 24-month period. A total of 94 onlay restorations in 47 patients were included in this study. Cavities were prepared, full-arch impressions were taken, and onlays were fabricated in the laboratory. All restorations were placed with a dual-cured luting resin composite system. Restorations were evaluated at baseline and at 6, 12, 18, and 24 months. Differences between Alpha scores were analyzed statistically. The recall rate of this study was 93.6%. At the six-month evaluation, one onlay failed due to pulpitis. Other than the color match, there was no significant difference between indirect resin composite and ceramic onlays (p > 0.05). For indirect resin composites, Alpha score differences pertaining to color match, marginal adaptation, and surface texture were found to be statistically significant (p < 0.05) between the baseline and the 24-month recall. For ceramic restorations, marginal adaptation criteria was the only significant difference over the 24-month period (p < 0.05). At the end of 24 months, both indirect resin composite and ceramic onlays were considered to be successful clinically.

Effects of topical fluoride agents on artificial enamel lesion formation in vitro.

OBJECTIVE: The purpose of this study was to assess the effects of topical fluoride agents on enamel erosion in vitro. METHOD AND MATERIALS: Ten premolars extracted for orthodontic purposes were sectioned buccolingually and then longitudinally into two parts, so that four specimens were obtained from each tooth. The specimens were randomly assigned to one of four groups. The following topical fluoride agents were applied to the specimens: 1% titanium tetrafluoride (0.32 MF) for 1 minute; Duraphat (2.26% F) and Elmex (1.25% F) for 4 minutes. In the control group, no solution was applied. The specimens were treated with an artificial caries solution for 4, 8, 12, and 16 days. Calcium (Ca++) concentration was determined by an atomic absorbtion spectrophotometer, while fluoride (F-) concentration was determined with an ion-selective electrode. One-way analysis of variance tests were performed on cumulative concentrations of calcium and fluoride at days 4, 8, 12, and 16. RESULTS: Specimens treated with titanium tetrafluoride lost significantly less calcium than did specimens in the other two test groups at all time periods. Titanium tetrafluoride-treated specimens released significantly less fluoride than did Duraphat- or Elmex-treated specimens at day 16. CONCLUSION: Titanium tetrafluoride was found to be more effective than the other fluoride agents in preventing artificial enamel lesion formation.