Primary Enamel Research Articles

Amelogenesis Imperfecta: Longevity of Clinical Treatment in Pediatric Dentistry

Amelogenesis Imperfecta (AI) is a rare, hereditary disorder that causes a defect in enamel mineralization in the primary and permanent dentitions. Amelogenesis imperfecta is generally categorized as hypoplastic, hypocalcified, or hypomaturation form based on the primary enamel defect. However, distinctive clinical features may be seen in each variant. Moreover, compromised esthetic appearances, tooth sensitivity and loss of occlusal vertical dimension are the common clinical problems observed in these variants. The objective of this review was to discuss the management strategies for patients with amelogenesis imperfecta. Definite diagnosis and adequate treatment planning are ensured for patients clinically presented with different forms of AI. Clinicians should provide preventive care and establish an early permanent therapy plan for these patients. Nevertheless, an interdisciplinary approach is required to improve both esthetic and functions. Moreover, there is a need for long-lasting restorative solutions for AI patients.

The Effect of Er:YAG Laser Irradiation Combined With Fluoride Application on the Resistance of Primary and Permanent Dental Enamel to Erosion.

Introduction: Erosion is an important cause of tooth mineral loss. The combined use of lasers and fluoride has been introduced as a novel modality for the prevention of enamel demineralization. This study aimed to assess the effect of Er:YAG laser combined with fluoride application on primary and permanent enamel resistance to erosion. Methods: Eighty enamel specimens of permanent (n=40) and primary (n=40) molars were prepared and randomly assigned to 4 groups: C-control (no pretreatment), F-acidulated phosphate fluoride (APF) gel, FL-APF gel application followed by Er:YAG laser irradiation, and LF-Er:YAG laser irradiation followed by the application of APF gel . The specimens were then submitted to pH cycling using Coca-Cola (pH=2.4). Enamel micro-hardness was measured using the Vickers microhardness tester before pretreatment and after the erosive process. The collected data were analyzed using the Kolmogorov-Smirnov test, two-way ANOVA and repeated measures ANOVA. Results: The micro-hardness of both permanent and primary enamel specimens significantly decreased after the erosive process (P < 0.05). In the permanent enamel specimens, the greatest reduction in micro-hardness was noted in groups C and F, while the least reduction was noted in group FL. However, these differences were not statistically significant (P > 0.05). In the primary enamel specimens, the greatest reduction in micro-hardness was noted in groups C and LF, while the least reduction was noted in group F. These differences were not statistically significant (P > 0.05). Conclusion: Within the limitations of this study, Er:YAG laser irradiation combined with fluoride application could not prevent erosion in permanent and primary enamel during the erosive process.

Mesenchymal Sufu Regulates Development of Mandibular Molars via Shh Signaling

Sonic hedgehog (Shh) in dental epithelium regulates tooth morphogenesis by epithelial-mesenchymal signaling transduction. However, the action of Shh signaling regulation in this process is not well understood. Here we find that mesenchymal Suppressor of Fused (Sufu), a major negative regulator of Shh signaling, plays an important role in modulating the tooth germ morphogenesis during the bud-to-cap stage transition. Deletion of Sufu in dental mesenchyme by Dermo1-Cre mice leads to delayed development of mandibular molar into cap stage with defect of primary enamel knot (EK) formation. We show the disruption of cell proliferation and programmed cell death in dental epithelium and mesenchyme in Sufu mutants. Epithelial-specific adhesion molecule E-cadherin is evidently reduced in the bilateral basal cells of tooth germ at E14.5. The cells in the presumptive EK, predominantly expressing P-cadherin, appear stratified but fail to condense. Moreover, the transcripts of primary EK marker genes, including Shh, Fgf4, and p21, are significantly decreased compared to controls. In contrast, we find that deficiency of Sufu results in elevation of Shh signaling in mesenchyme, indicated by the significant upregulation of Gli1 and Ptch1. Meanwhile, the expression of Bmp4 and Fgf3, the critical factors of mesenchymal-epithelial induction, is significantly inhibited in dental mesenchyme. Furthermore, the expression of Runx2 experiences a transient decrease at the bud stage. Taken together, these data suggest that mesenchymal Sufu is necessary for tuning the Shh signaling, which may act as an upstream modulator of Bmp4 and Fgf3 to coordinate the interplay between the dental mesenchyme and epithelium of tooth germ.

Evaluation of the Erosive Effect of Chewing Aspocid versus its Soluble Form on Micro Hardness of Primary Teeth Enamel in Heart Disease Children. (In Vitro -Study)

Evaluation of the Erosive Effect of Chewing Aspocid versus its Soluble Form on Micro Hardness of Primary Teeth Enamel in Heart Disease Children. (In Vitro -Study)

Evaluation of the Erosive Effect of Chewing Aspocid versus its Soluble Form on Micro Hardness of Primary Teeth Enamel in Heart Disease Children. (In Vitro -Study)

Evaluation of the Erosive Effect of Chewing Aspocid versus its Soluble Form on Micro Hardness of Primary Teeth Enamel in Heart Disease Children. (In Vitro -Study)

Comparative Analysis of CPP&amp;ndash;ACP, Tricalcium Phosphate, and Hydroxyapatite on Assessment of Dentinal Tubule Occlusion on Primary Enamel Using SEM: An In Vitro Study

ABSTRACTBackgroundOver the last few decades, fluoride in various forms has been proved to reduce caries and dentinal hypersensitivity in both the primary and permanent dentitions. Recently, newer materials containing calcium and phosphate ions, tricalcium phosphate, and hydroxyapatite has received much attention.AimThe aim of the study was to compare CPP–ACP, tricalcium phosphate, and hydroxyapatite in relation to the assessment of dentine tubule occlusion on primary enamel using scanning electron microscope (SEM).Materials and methodsForty freshly extracted noncarious primary molars were randomly divided into 4 groups (I–IV) with 10 sections in each group—group I: negative control, group II: CPP–ACP, group III: tricalcium phosphate, group IV: hydroxyapatite. To assess tubule occlusion, twenty dentin sections of 2-mm thickness were obtained from the cervical third of sound primary molars. Each section was processed to simulate the hypersensitive dentin and the test agents were brushed over the sections with an electric toothbrush and observed under a SEM for calculation of the percentage of occluded tubules.ResultsGroups II and IV showed a greater percentage of tubule occlusion than group III. An intergroup comparison of tubule occlusion potential of groups II and IV was not significant.ConclusionHydroxyapatite showed significantly higher dentinal tubule occlusion when compared to CPP–ACP and tricalcium phosphate.How to cite this articleShah R, Bajaj M. Comparative Analysis of CPP–ACP, Tricalcium Phosphate, and Hydroxyapatite on Assessment of Dentinal Tubule Occlusion on Primary Enamel Using SEM: An In Vitro Study. Int J Clin Pediatr Dent 2019;12(5):371–374.

Effect of Remineralizing Agents on Bond Strength of Resin-Composites to Primary Enamel.

Aim: The purpose of this in vitro investigation was to assess the effect of three remineralizing agents (Voco Remin Pro®, Uncle Harry's remineralization kit, Sunshine remineralization gel) on the shear bond strengths of two resin-composites (Tetric® N-Ceram and Filtek™ Z250 Universal Restorative) to enamel of primary molars. Study design: Ninety-six enamel specimens were prepared and randomly distributed to eight groups according to the control, remineralizing agents, and resin composite used. Shear bond strength was measured at a crosshead speed of 0.5 mm/min and the type of bond failure was recorded. Results: The highest shear bond strength (Mean+SD) in MPa was for Tetric® N-Ceram/control [21.06+1.68] while the lowest was for Filtek™ Z250/Sunshine remineralization gel [11.98+1.46]. Tukey HSD Post Hoc Tests showed significant difference between Tetric® N-Ceram/control and all other groups (p=0.0001) except Filtek™ Z250/control. In addition, there was significant difference between Filtek™ Z250/control and all other groups (p=0.0001) except Tetric® N-Ceram/control and Tetric® N-Ceram/Uncle Harry's remineralization kit. Mode of failure was cohesive (9.38%), adhesive (55.21%), and mixed (35.42%). Conclusions: The three tested remineralizing agents affect shear bond strength of the tested resin-composites to enamel of primary teeth. In general, shear bond strength values were acceptable. Mode of failure was mostly adhesive.

Effect of topical fluoride on microshear bond strength of primary enamel to composite, microhardness of enamel and its surface morphology: An in vitro study.

Background. This in vitro study aimed to evaluate the microshear bond strength (μSBS), microhardness and morphological characteristics of primary enamel after treating with sodium fluoride (NaF) and acidulated phosphate fluoride (APF). Methods. Forty-eight primary canines were cut into mesial and distal sections and assigned to five groups randomly: group 1 (immersed in saliva as a control), group 2 (treated with NAF and immersed in saliva for 30 minutes), group 3 (treated with APF and immersed in saliva for 30 minutes), group 4 (treated with NAF and immersed in saliva for 10 days), and group 5 (treated with APF and immersed in saliva for 10 days). Composite resin (Filtek Z250) was bonded on the specimens (n=15) for measuring the μSBS. After storage in 37°C artificial saliva for 24 hours, µSBS and Vickers hardness tests (10 readings) were performed. The data were analyzed using one-way ANOVA and Kolmogorov-Smirnov, Levene’s and Tukey HSD tests (P<0.05). Morphological analysis of enamel and modes of failure were carried out under a scanning electron microscope (SEM) on two remaining specimens. Results. Significant differences in μSBS were only noted between groups 2 and 4 (P=0.024). Group 3 showed a significant decrease in hardness after storage in artificial saliva (P<0.001), with a significantly lower hardness than the other groups (P<0.001). The SEM observations showed irregular particles in groups 3 and 5; uniform, smooth and thin coats were seen in groups 2 and 4. Conclusion. Fluoride therapy with NaF and APF gels prior to restorative treatments had no adverse effects on the microshear bond strength.

Comparative Evaluation of Shear Bond Strength of Composite Resin Bonded to Acid Etched and Lased Primary Enamel (Er, Cr: YSGG)

Comparative Evaluation of Shear Bond Strength of Composite Resin Bonded to Acid Etched and Lased Primary Enamel (Er, Cr: YSGG)

Effect of Er:YAG and Fluoride Varnishes for Preventing Primary Enamel Demineralisation.

To measure the demineralisation changes on human deciduous enamel produced by pH cycling after preventive treatment with Er:YAG laser irradiation, fluoride varnish application and a combination of the two. Sixty extracted human anterior primary teeth were assigned to six groups (n = 10). Group C: untreated; group L: Er:YAG laser; group TCP-NaF: Clinpro White (5% sodium fluoride and modified tricalcium phosphate); group CPP-ACP-NaF: MI varnish (5% sodium fluoride with casein phosphopeptide-amorphous and calcium phosphate); group L+TCP-NaF: Er:YAG + 5% sodium fluoride + modified tricalcium phosphate; group L+ CPP-ACP-NaF: Er:YAG + 5% sodium fluoride with casein phosphopeptide-amorphous and calcium phosphate. The samples were subjected to a 10-day pH-cycling regimen to create caries-like lesions, with 8 h in demineralising solution and 16 h in remineralising solution at 37°C. Enamel demineralisation was evaluated by laser fluorescence (DIAGNOdent) before and after pH cycling. The Mann-Whitney U-test and Wilcoxon tests were performed with statistical significance set at p ≤ 0.05. The Wilcoxon test revealed statistically significant differences at baseline and after pH cycling in groups C (p = 0.02), L (p = 0.034) and L+TCP-NaF (p = 0.025) and the lowest percentage of healthy tooth substance compared to the other groups. The results suggest that the treatment protocols employed in groups TCP-NaF, CPP-ACP-NaF, and L+ CPP-ACP-NaF had similar effects in terms of preventing demineralisation, as reflected in a higher percentage of healthy dental structure maintained. Hence, these treatments are recommended for clinical use as an effective preventive measure.

The effect of Er,Cr:YSGG laser, fluoride, and CPP-ACP on caries resistance of primary enamel.

The aim of this in vitro study was to determine the effect of different remineralization agents and laser on caries resistance of primary enamel. In the study, 150 sound primary molars were used. The initial microhardness values were measured and the teeth were randomly assigned to ten treatment groups (n = 15): no treatment/negative control (C), NaF, APF, fluoride varnish (FV), CPP-ACP, laser (L), L + NaF, L + APF, L + FV, L + CPP-ACP. The microhardness values were measured after the treatments and the pH cycle. The obtained data were analyzed statistically. One sample from each group was examined before treatment, after treatment, and after the pH cycle with a scanning electron microscope. While microhardness values after treatment compared to baseline increased, microhardness after the pH cycle decreased compared to after treatment values in all experimental groups (p < 0.05). In regard to the difference in microhardness after the pH cycle and baseline, there were no statistically significant differences between groups C and NaF and between C and CPP-ACP (p > 0.05). There was a significant difference between groups L and L + FV (p < 0.05), while no significant difference was noted between groups L and L + NaF, L + APF, L + CPP-ACP (p > 0.05). As a conclusion, FV is more effective when used in combination with laser than laser alone. NaF, CPP-ACP, and laser may be insufficient in protecting the primary teeth against acid attacks compared to FV used with laser.

Activation of Pro-apoptotic Caspases in Non-apoptotic Cells During Odontogenesis and Related Osteogenesis.

Caspases are well known proteases in the context of inflammation and apoptosis. Recently, novel roles of pro-apoptotic caspases have been reported, including findings related to the development of hard tissues. To further investigate these emerging functions of pro-apoptotic caspases, the in vivo localisation of key pro-apoptotic caspases (-3,-6,-7,-8, and -9) was assessed, concentrating on the development of two neighbouring hard tissues, cells participating in odontogenesis (represented by the first mouse molar) and intramembranous osteogenesis (mandibular/alveolar bone). The expression of the different caspases within the developing tissues was correlated with the apoptotic status of the cells, to produce a picture of whether different caspases have potentially distinct, or overlapping non-apoptotic functions. The in vivo investigation was additionally supported by examination of caspases in an osteoblast-like cell line in vitro. Caspases-3,-7, and -9 were activated in apoptotic cells of the primary enamel knot of the first molar; however, caspase-7 and -8 activation was also associated with the non-apoptotic enamel epithelium at the same stage and later with differentiating/differentiated odontoblasts and ameloblasts. In the adjacent bone, active caspases-7 and -8 were present abundantly in the prenatal period, while the appearance of caspases-3,-6, and -9 was marginal. Perinatally, caspases-3 and -7 were evident in some osteoclasts and osteoblastic cells, and caspase-8 was abundant mostly in osteoclasts. In addition, postnatal activation of caspases-7 and -8 was retained in osteocytes. The results provide a comprehensive temporo-spatial pattern of pro-apoptotic caspase activation, and demonstrate both unique and overlapping activation in non-apoptotic cells during development of the molar tooth and mandibular/alveolar bone. The importance of caspases in osteogenic pathways is highlighted by caspase inhibition in osteoblast-like cells, which led to a significant decrease in osteocalcin expression, supporting a role in hard tissue cell differentiation.

Evaluation of permanent and primary enamel and dentin mineral density using micro-computed tomography.

The present study was performed to investigate the mineral density distribution in enamel and dentin for both permanent and primary teeth and to establish the standard density per tooth type using micro-computed tomography (CT). Fifty-seven extracted human teeth (37 permanent, 20 primary) were evaluated in the present study. The enamel and dentin mineral densities in the extracted teeth were measured using micro-CT. Cubic regression curves were used to determine the mineral density distribution in the enamel and dentin for each tooth type. The mean values, distributions, and regression equations of the mineral densities were obtained. The mean mineral density values for permanent enamel and dentin were significantly higher than those for their primary counterparts for each tooth type. In the present study, we demonstrated the distribution of mineral density in sound enamel and dentin and attempted to determine the standard mineral density for each tooth type using micro-CT. The mineral density distributions found in this study contribute to our understanding of the mechanical properties of enamel and dentin. A positive correlation suggests that the systemic bone mineral density could be predicted based on the analysis of exfoliated teeth, such as in patients with hypophosphatasia. The present results may be useful in establishing a numerical standard for the mechanism involved in root fracture and for early detection of root fracture risk.

Evaluation of Remineralization Potential of Beverages modified with Casein Phosphopeptide-Amorphous Calcium Phosphate on Primary and Permanent Enamel: A Laser Profiler Study.

PurposeTo assess the erosive potential of carbonated beverages and the remineralization potential of beverages with added casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste on primary and permanent enamel.Materials and methodsA total of 32 primary and 32 permanent enamel specimens were immersed for 5, 10, and 30 minutes, respectively, in beverages, i.e., Coke, Sprite, Mirinda, and Mountain Dew, with and without added 0.2% CPP-ACP. Samples were profiled before immersion and after immersion under laser profiler.ResultsCoke was found to be highly erosive at it caused significant enamel erosion at both 10 and 30 minutes of immersion (p < 0.05) for both primary and permanent enamel. The 30-minute immersion caused significant amount of reminerali-zation over primary enamel in all groups, whereas permanent enamel remineralization was significant in Sprite and Mountain Dew at 30 minutes in all the groups (p < 0.05).ConclusionThis study demonstrated that enamel erosion occurred after immersion in carbonated beverages. Remineralization of enamel was observed after immersion in beverages modified with CPP-ACP paste. Primary enamel was susceptible to remineralization compared with permanent enamel. Within the limitations of this in vitro study, the application of CPP-ACP paste may enhance the remineralization after an erosive challenge and thus offer some protection for patients who are at risk for erosion.How to cite this article: Rai N, Sandhu M, Sachdev V, Sharma R. Evaluation of Remineralization Potential of Beverages modified with Casein Phosphopeptide-Amorphous Calcium Phosphate on Primary and Permanent Enamel: A Laser Profiler Study. Int J Clin Pediatr Dent 2018;11(1):7-12.

Does Acid Challenge Affect the Properties and Bond Stability of Restorative Materials on Primary Teeth?

To evaluate the effect of acidic challenge (AC) on the properties and bond stability of restorative materials to primary enamel and dentin. One hundred twenty primary molars were assigned to 12 groups according to substrate (enamel or dentin), restorative material (composite, high-viscosity glass ionomer cement [HV-GIC] or resin-modified glass-ionomer cement [RM-GIC]), and immersion after restoration (control [saline solution/7 days] or AC [cola-based drink/5 min/3x per day/7 days]). Twenty-four hours after the restorative procedure, specimens were submitted to one of the proposed challenges. Half of the specimens were immediately subjected to the microshear bond strength test, and the other half after 12 months. To determine flexural strength flexural strength and superficial roughness (SR), 30 specimens were built up. After 24 h, the first measurement of SR from 10 specimens was performed. Specimens were then immersed in one of proposed challenges and SR was measured again. Subsequently, flexural strength testing was performed. Bond strength, surface roughness, and flexural strength data were subjected to ANOVA and Tukey's test. Composite showed the highest bond strengths compared to the others materials on both substrates. The storage period negatively influenced the bond strength only for composite groups in dentin. AC after restoration negatively influenced bond strength when the materials were evaluated in eroded dentin. AC affected the second SR measurement, showing increased SR for all restorative materials. AC did not affect flexural strength. The acidic challenge jeopardizes the surface roughness and bond strength of restorations to eroded dentin.

Effect of a coating material containing surface reaction-type pre-reacted glass-ionomer filler on prevention of primary enamel demineralization detected by optical coherence tomography.

We used optical coherence tomography to examine the effect of a coating material containing surface reaction-type pre-reacted glass-ionomer (S-PRG) filler on primary enamel demineralization in 18 extracted human primary teeth. The pulp was removed, and each tooth was ultrasonically cleaned with distilled water. Six teeth were treated with 0.1-M lactic acid buffer solution (De group). In the second group (n = 6), a thin film of coating material was applied before demineralization (PRG group). A third group (Control group; n = 6) was maintained in artificial saliva. Using optical coherence tomography, we measured peak signal intensity (dB) and width at 1/e2 (µm) at predetermined locations on the enamel surface and calculated integrated values. All data were analyzed with ANOVA and the Tukey-Kramer test (α = 0.05). Although changes in integrated values differed between groups, there was a small but significant increase in the Control group and a small but significant decrease in the De group. In the PRG group, integrated values were significantly higher at 7 days after the start of the experiment and significantly increased thereafter. Our findings indicate that a coating material containing S-PRG fillers may prevent primary enamel demineralization.

Evaluation of the erosive capacity of children's beverages on primary teeth enamel: An in vitro study.

BackgroundThe consumption of acidified beverages, associated with lower mineralization of primary enamel, is the ideal combination for the development and progression of dental erosion. The objective of this study is to analyze the erosive capacity and the surface roughness of primary teeth enamel after exposure to three different brands of grape juices.Material and MethodsForty enamel blocks of primary teeth were obtained, attened and polished. They were submitted to initial surface roughness analysis (baseline), and randomly assigned into four groups (n = 10): NAT: natural grape juice (Campo Largo); IND: industrialized grape juice (Dell Vale Kapo); SOY: soy-based grape juice (Ades); and CONT (control): artificial saliva. Blocks were immersed for 2 min, 3 times per day, for 9 days. During the whole time of the experiment, the enamel blocks were stored in artificial saliva. After the 9 days, the roughness parameters were determined again. The beverages were analyzed for pH and titratable acidity. Data were statistically analyzed (α = 0.05).ResultsThe surface roughness did not differ significantly among groups (p > 0.05). However, after the immersion in the different grape juices, the surface roughness values increased significantly (p< 0.05). The pH values were weakly correlated to acidity values; NAT showed the highest titratable acidity values than the other juices (p<0.05).ConclusionsAlthough the surface roughness values of the experimental groups did not differ from the control group, there was a difference in initial and final roughness in all groups. Grape juices, especially natural, may have an erosive capacity, changing the surface roughness of primary dental enamel. Key words:Dental erosion, beverages, enamel, roughness.

Effect of Erbium Laser on Microtensile Bond Strength of Fissure Sealant in Primary Teeth: An in vitro Study.

Background:Laser etching has several advantages as compared with conventional acid etching. However, results of earlier studies on conditioning surfaces with erbium, chromium:yttrium–scandium–gallium–garnet (Er, Cr:YSGG) before application of the fissure sealant have been inconclusive.Aim:The study aimed to evaluate the microtensile strength of resin-based fissure sealant bonded to primary enamel conditioned by Er, Cr:YSGG laser with varying power outputs.Materials and Methods:Fifty sound primary first molars were randomized into the following five groups based on pretreatment choice: Group 1: 3.5 W laser etching + acid etching; Group 2: 2.5 W laser etching + acid etching; Group 3: 3.5 W laser etching with no acid; Group 4: 2.5 W laser etching with no acid and Group 5: acid etching with no laser. Acid etch was performed with 35% orthophosphoric acid for 30 s. Laser etching was performed with Er, Cr:YSGG (2780 nm) laser using G6 tips and 600 μm diameter, 2.5 W or 3.5 W power outputs, pulse duration of 140 μs and a repetition rate of 20 Hz. Sealant was applied on the buccal surface followed by an incremental buildup with composite resin. Microtensile bond strength was assessed and compared among the five groups using one- and two-way ANOVA.Results:There was no statistical difference in the mean bond strength between groups except in Group 4 (9.66 MPa) (Group 1: 15.57 MPa; Group 2: 14.18 MPa; Group 3: 14.78 MPa; Group 5: 14.63 MPa).Conclusion:Pretreatment with 3.5 W Er, Cr:YSGG laser alone results in microtensile bond strengths similar to that produced by acid etching, indicating that enamel etching using 3.5 W Er, Cr:YSGG laser would result in the long-term success of pit and fissure sealants in primary teeth.

Microhardness and Surface Texture of Primary Teeth Enamel After Immersion in a Fruit Drink

Purpose:The purpose of this in vitro study was to determine the surface microhardness of human enamel of primary teeth immersed in an orange fruit drink at two time intervals. In addition, surface texture was recorded using scanning electron microscope (SEM).Methods:Fifteencaries free primary molars were used to prepare enamel specimens. Specimens were immersed in orange fruit drink for 1 and 2 hours at room temperature. Prior to immersion and following each immersion period, measurement of the surface microhardness at a load of 200 grams for 5 seconds and impression was taken for each specimen using polyvinyl/siloxane to form an epoxy resin replica to be prepared for SEM examination.Results:Mean +standard deviation of the surface microhardness prior to immersion as well as 1 hour and 2 hours after immersion were 343.50 + 6.78, 273.13 + 6.70, and 212.13 + 6.63 respectively. There was significant difference between the three groups (p<0.0001).Percent difference of microhardness before versus after immersion showed that the greatest softening after the second immersion compare to first immersion and before immersion. A distinct difference was observed under SEM in the specimens after 1 and 2 hours immersion in the fruit drink compared to the control.Conclusion:Immersion of the specimens of enamel of primary teeth in the tested orange fruit drink for 1 and 2 hours reduced the surface microhardness significantly compared to the baseline/control. SEM confirmed that the surface texture of the enamel surface of primary teeth was affected. Changes and effects on the surface texture increased over time and result in severe irregular and etching-like pattern of destruction after exposure for 2 hours.

Mechanism of Action of TiF4 on Dental Enamel Surface: SEM/EDX, KOH-Soluble F, and X-Ray Diffraction Analysis

This in vitro study aimed to evaluate the action of TiF₄ on sound and carious bovine and human enamel. Sound (S) and pre-demineralised (DE) bovine and human (primary and permanent) enamel samples were treated with TiF₄ (pH 1.0) or NaF varnishes (pH 5.0), containing 0.95, 1.95, or 2.45% F for 12 h. The enamel surfaces were analysed using SEM-EDX (scanning electron microscopy/energy-dispersive X-ray spectroscopy) (n = 10, 5 S and 5 DE) and KOH-soluble fluoride was quantified (n = 20, 10 S and 10 DE). Hydroxyapatite powder produced by precipitation method was treated with the corresponding fluoride solutions for 1 min (n = 2). The formed compounds were detected using X-ray diffraction (XRD). All TiF₄ varnishes produced a coating layer rich in Ti and F on all types of enamel surface, with micro-cracks in its extension. TiF₄ (1.95 and 2.45% F) provided higher fluoride deposition than NaF, especially for bovine enamel (p < 0.0001). It also induced a higher fluoride deposition on DE samples compared to S samples (p < 0.0001), except for primary enamel. The Ti content was higher for bovine and human primary enamel than human permanent enamel, with some differences between S and DE. The XRD analysis showed that TiF₄ induced the formation of new compounds such as CaF₂, TiO₂, and Ti(HPO₄)₂·H₂O. In conclusion, TiF₄ (>0.95% F) interacts better, when compared to NaF, with bovine and human primary enamel than with human permanent enamel. TiF₄ provoked higher F deposition compared to NaF. Carious enamel showed higher F uptake than sound enamel by TiF₄ application, while Ti uptake was dependent on the enamel condition and origin.