Browsing by Subject "Tooth Demineralization"
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Item Ability of Caries Detection Methods to Determine Caries Lesion Activity(2019-12) Aldawood, Fatma; Ando, Masatoshi; Hara, Anderson T.; Diefenderfer, Kim E.Background: Non-cavitated caries lesions form due to acid diffusion and demineralization of enamel subsurface with an intact surface layer (SL). Caries lesions progress when the outcome of demineralization and remineralization processes over time is net mineral loss. Lesions that continue to demineralize are called active, while those that display no evidence of further demineralization are called inactive. Micro-computed-tomography (µCT) analysis provides objective non-destructive measurements of the thickness of the surface layer (SL) and severity of caries lesions. Aims: 1) To investigate if visual/tactile suspected active non-cavitated early white spot lesions present a thinner surface layer than inactive ones; 2) To investigate if there is an association between the thickness of the surface layer (SLT) and caries activity, as determined by QLF during dehydration (△QD); 3) To determine lesion severity by comparing lesion volume and maximum depth correlation with △Q value at 15 s from QLF during dehydration. Materials and Methods: Thirty extracted human premolars exhibiting non-cavitated approximal white spot early lesions stored in 0.1.-percent thymol/4C and treated with 5.0-percent NaOCl/30 min were included in the study. Fifteen active and 15 inactive lesions were determined by visual/tactile examinations by consensus of two experienced examiners. Roughness measurements (Ra) were acquired using non-contact optical profilometry. Two-dimensional minimum (2D-min), maximum (2D-max), average (2D-avg) SL and three-dimensional (3D) analyses, volume and depth of lesions were determined from µCT image analysis. A series of fluorescence images were acquired at baseline (hydrated), at 1 s, at 5 s, at 10 s and at 15 s by QLF. During image acquisition, surfaces were dehydrated with continuous-compressed-air. △Q and △Q/s (△QD) were calculated. Data were analyzed using two-sample t-tests and Pearson correlation coefficients (p < 0.05). Results: Surface roughness of active and inactive lesions was not significantly different (p > 0.08). Overall lesion volume and depth in dentin were significantly larger in active lesions (p = 0.022, p = 0.009). SL thickness of active and inactive lesions was not significantly different (2D = 0.121, 3D = 0.080, 2D-avg = 0.446, 2D-min = 0.197, 2D-max = 0.122). △QD at 1s was significantly larger for active lesions (p = 0.046). ΔQ at 15 s of dehydration had a moderate positive association with lesion volume (r = 0.56). △QD had a weak negative association with SL thickness (2D-avg) and (2D-min). Conclusions: 1) Active and inactive non-cavitated lesions show no difference in SL thickness; 2) QLF during dehydration (△QD) does not correlate well with SL thickness; 3) ΔQ at 15 s of dehydration correlates moderately well with lesion volume and is consistent with caries activity assessed by visual/tactile examination.Item Fluoridated Orthodontic Adhesives' Effect on Enamel Fluoride Content and Demineralization(1995) Lampros, Penny Lynn; Moore, B. Keith; Arbuckle, Gordon R.; Katona, Thomas R.; Shanks, James C.; Swartz, Marjorie L.; Zitterbart, Paul A.Orthodontists are concerned about the high incidence of demineralization and decalcification around appliances. The orthodontic appliances diminish the self-cleansing mechanisms of the oral cavity, and in essence, act as traps for plaque and other debris that often lead to decalcification of the surrounding enamel. Fluoride containing dental restorative cements have been shown to reduce the incidence of secondary caries. The purpose of this study was to compare two fluoride containing orthodontic resin adhesives (a commercial, Phase II F, and an Experimental Adhesive) with a commercial nonfluoridated resin adhesive (Phase II). The resins were compared with respect to fluoride release in water over a 30 day period, hardness, and their effects on enamel fluoride content and enamel demineralization. Resin discs were made from the two fluoridated adhesives and placed in glass distilled water. Fluoride ion concentrations of the water were measured daily, and the accumulated concentrations were calculated for 30 days. Hardness discs were constructed from each adhesive, and Knoop hardness was measured after one hour, one day and one week. Finally, orthodontic brackets were bonded to bovine enamel discs, and two weeks after cementation of the brackets, the specimens were demineralized, and the adjacent enamel was biopsied for fluoride content. Those same specimens were sectioned longitudinally through the bracket and then stained with Rhodamin B. Areas of demineralization extending 500 μm from the bracket edge were measured by a confocal microscope. Depth of demineralization was measured at 250 μm intervals up to 1000 μm. The Experimental Adhesive released fluoride at a significantly higher rate over 30 days than did Phase 11 F. None of the three materials demonstrated any dramatic change in hardness after one week in water. Enamel exposed to the Experimental Adhesive had the highest fluoride content followed by that associated with Phase II F. The lowest fluoride content was found in the nonfluoridated Phase 11 adhesive. The extent of enamel demineralization, in area and depth, was inversely related to the fluoride pattern, although these differences were not statistically significant. A definite trend was noted for increased fluoride content and decreased demineralization of enamel due to increased fluoride released by the Experimental Adhesive.Item The influence of baseline hardness and chemical composition on enamel demineralization and subsequent remineralization(2017-05-09) Alkattan, Rana; Ando, Masatoshi; Lippert, Frank; Cook, Norman BlaineBACKGROUND Several studies have reported that harder enamel with higher contents of calcium (Ca), phosphorus (P) and fluorine (F) coupled with lower contents of carbonate (C), magnesium (Mg) and nitrate (N) was found to be more resistant to demineralization. Additionally, the hardness of dental enamel was found to have a strong correlation with its chemical content. However, yet to be established is the relation between the physical and chemical structure of enamel and its response to de- and remineralizing conditions. OBJECTIVES The aims of this laboratory study were: 1) To investigate the hardness and chemical content of sound enamel and their influence on demineralization; 2) To investigate these properties in demineralized enamel and their influence on remineralization; and 3) To investigate these properties in sound enamel and their influence on remineralization. MATERIALS AND METHODS Incipient subsurface caries lesions were created in 94 bovine enamel specimens using Carbopol C907 using three demineralization times. The specimens were then pH-cycled and treated using either 367 ppm F sodium fluoride or a placebo. Knoop surface microhardness (SMH), Energy dispersive X-ray spectroscopy (EDS) and Transverse microradiography (TMR) were performed on the specimens at all stages and compared between them. TMR variables included integrated mineral loss (ΔZ), Lesion depth (L) and maximum mineral density of the surface zone (SZmax). Data were analyzed using three- and four-way ANOVA and Pearson correlation coefficients were calculated. RESULTS SMH, ΔZ, L and SZmax were significantly different among stages, demineralization times and treatment. The weight% of F at the surface was significantly affected by treatment, irrespective of demineralization time. A statistically significant moderate correlation was found between SZmax and ΔZ and SZmax and L after pH cycling. SMH also correlated weakly to moderately with TMR data. CONCLUSIONS SMH and SZmax decreased while ΔZ and L increased with increased demineralization time. Both fluoride and non-fluoride specimens were able to remineralize, which emphasizes the role of saliva in mineralization. The Ca:P ratio remained stable at various stages, indicating the stoichiometric dissolution and redeposition of minerals. The greatest deposition of F was at the surface and its increase led to an increase in SMH and SZmax. SMH values showed that harder specimens at baseline and after demineralization remained hard after demineralization and pH-cycling, respectively, although this correlation was weak. Additionally, harder lesions showed less L and ΔZ and greater SZmax. RELEVANCE This in-vitro study will help better understand the caries process and the impact of physical and chemical characteristics of enamel on de- and remineralization challenges.Item Longitudinal In Vitro Effects of Silver Diamine Fluoride on Early Enamel Caries Lesions(2020) Thompson Alcorn, Alice-Anne; Lippert, Frank; Al Dehailan, Laila; Cook, N. BlaineObjective: This study aimed to evaluate surface microhardness changes in early, incipient, non-cavitated white-spot, enamel caries lesions treated with silver diamine fluoride (SDF) longitudinally. The utilization of silver nitrate and potassium fluoride test groups served as additional controls to assist in evaluating if the remineralization effects were due to the silver or fluoride component in SDF. Hypotheses: 1. SDF treatment will result in increased surface microhardness of early, incipient, non-cavitated white-spot, enamel caries lesions compared to all other tested interventions. 2. Specimen storage for 2-weeks in artificial saliva will result in greater surface rehardening in lesions treated with SDF compared to other tested interventions. Design: This laboratory study had 5 intervention groups (SDF, silver nitrate (AgNO3), potassium fluoride (KF), 5.0-percent sodium fluoride varnish (FV), deionized water (DI)) × 2-time intervals after intervention (immediate & delayed pH-cycling), resulting in 10 groups (n = 18). Early, incipient, non-cavitated white-spot, enamel caries lesions were created in bovine enamel and extent of demineralization was determined using Vickers surface microhardness (VHNlesion). Intervention treatments were applied. Half the specimens from each group underwent immediate 5-day pH-cycling and half were stored in an incubator with artificial saliva for two weeks before undergoing 5-day pH-cycling. After pH-cycling, lesion hardness was evaluated using VHNpost. Specimens were then exposed to a second demineralization challenge and lesion softening was evaluated using VHNsecdem. Surface rehardening was calculated: ΔVHN =VHNpost - VHNlesion. Surface softening was calculated: ΔVHNsecdem =VHNsecdem – VHNpost. Data was analyzed using two-way ANOVA. Results: Immediately cycled, SDF had significantly (p < .0001) greater remineralization than DI, AgNO3, and FV. All delayed cycling groups had significantly (p < .0001) greater remineralization than FV. Significantly greater remineralization was noted in delayed AgNO3 (p < .0001), DI (p = .0003), and FV (p = .0006) compared to immediately cycled. After the second demineralization challenge, FV had significantly less surface softening than AgNO3 (p = 0.0002), DI (p = 0.0003), KF (p = 0.0225), and SDF (p = 0.0388) intervention groups. No significant difference was found between the pH-cycle timings. Conclusion: Based on our findings, FV maybe better suitable than SDF to treat early, incipient, non-cavitated white-spot, enamel caries lesions. Longitudinally, SDF exhibited greater remineralization than both FV and DI groups, though not statistically significant. However, upon a second demineralization challenge, FV significantly outperformed SDF in preventing surface softening.Item Relative fluoride response of caries lesions created in fluorotic and sound teeth studied underremineralizing conditions(2013) Alhawij, Hala M.; Martilnez-Mier, Esperanza de los A. (Esperanza de los Angeles), 1967-; Lippert, Frank; Cochran, Michael A. (Michael Alan), 1944-; Soto-Rojas, Armando E.; Zandoná, Andréa G. Ferreira (Andréa Gonçalves Ferreira),1969-Fluoride prevents caries by decreasing demineralization and promoting remineralization of enamel crystals during lesion formation and progression. The chemical, morphological, and histologic characteristics of teeth with fluorosis may alter the response of enamel to fluoride during the caries process. However, the effectiveness of fluoride in fluorosed teeth has not been thoroughly studied. Therefore, the current study utilized an in-vitro net remineralization model to study differences between fluorosed and sound enamel with regards to caries lesion remineralization and progression. Hypotheses: There is no significant difference in the effectiveness of fluoride to enhance caries lesion remineralization between fluorosed and non-fluorosed (sound) teeth after changes in enamel fluorescence relative to the lesion baseline. Objectives: The primary objective is to investigate the relative fluoride response of caries lesions created in sound and fluorosed teeth of varying severities under remineralizing conditions in vitro. Secondary objectives: a) To investigate the impact of the presence and severity of enamel fluorosis on caries lesion formation, and b) To investigate the acquired acid resistance of pH-cycled lesions relative to their fluorosis severity. Materials and Methods: Three hundred sixty (360) extracted human molars (sound and fluorosed) were collected and divided into four main groups based on their TF score (0; 1; 2; 3), with sample size of n = 45 per group. Each group was divided into two subgroups: no fluoride/placebo and fluoride/treatment. Artificial caries lesions were created on the teeth and pH-cycled for 20 days using a net remineralization model. The lesions were assessed to determine differences in acquired acid resistance. Quantitative light-induced fluorescence (QLF) was used throughout the study to determine changes in enamel fluorescence relative to a sound enamel window, thereby providing information about enamel de- or remineralization. The results of this study demonstrated that enamel fluorosis levels had a significant effect on lesion remineralization after pH cycling (p > 0.05). The teeth with moderate dental fluorosis had a significantly better response to remineralization and more resistance to a subsequent acid challenge than sound teeth in the presence of fluoride.Item Treatment of Enamel Demineralization Following Orthodontic Therapy(1997) Stoll, Lana R.; Garetto, Lawrence P.; Analoui, Mostafa; Dunipace, Ann J.; Hohlt, William F.; Schemehorn, Bruce R.; Shanks, JamesThe early-stage, carious, white-spot lesion is a common finding on teeth in patients who have received orthodontic treatment. Recently, a calciumphosphate (Ca-P) treatment was developed to enhance remineralization of white spot lesions. We hypothesized that a rinse containing the Ca-P would promote greater remineralization of demineralized enamel in vivo than a fluoride (F)-containing rinse or a placebo rinse. Thirty post-treatment orthodontic patients with demineralized white spot lesions on one or more of the six maxillary anterior teeth were selected and randomly assigned to three equal groups for a double-blind study. One group was given the placebo rinse. Another group was given a rinse with the same ingredients as the placebo rinse plus 0.055% F. The third group was given a rinse with the same ingredients as the F rinse plus calcium, phosphate, and magnesium salts. In addition, all subjects used a 0.011% F dentifrice before rinsing. Two different methods were used to determine the initial extent and subsequent de- or remineralization of the white spot lesions at the debonding appointment (baseline), and at one, three, and six months after the baseline reading: 1) visual inspection, in which two examiners estimated the severity and location of the lesions, and 2) quantitative laser fluorescence (QLF), in which the depth and area of the lesions were determined more objectively. Lnterexaminer agreement was almost perfect for the clinical exams. All three groups were significantly different with regards to reduction of number of white spots according to the clinical scoring. The placebo rinse group had the greatest reduction followed by the Ca-P group and the fluoride group. The QLF data showed no significant overall group differences for any of the measurements except total lesion depth. The placebo group had a significantly greater reduction of total lesion depth at the last examination than the Ca-P group (p < 0.05). The data suggested that different mechanisms may exist for remineralization of large and small lesions and that remineralization of a lesion with a lower concentration of fluoride, such as that used with the placebo rinse and the fluoride dentifrice, may result in greater remineralization of white-spot lesions.