Browsing by Author "Hara, Anderson T."
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Item 3D-Image Analysis of the Impact of Toothpaste Abrasivity on the Progression of Simulated Non-Carious Cervical Lesions(Elsevier, 2018) Sabrah, Alaa H.; Turssi, Cecilia P.; Lippert, Frank; Eckert, George J.; Kelly, Adam B.; Hara, Anderson T.; Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjectives To investigate the effect of toothpaste abrasive level on the progression of non-carious cervical lesions (NCCLs) using 3D-image subtraction. Methods Upper first premolars were allocated into seven groups (n = 16) of toothpaste/abrasive slurries: A-Zeodent113/5%, B-Zeodent124/10%, C-Zeodent103/15%, D-Sensodyne Pronamel, E-Crest Cavity-Protection, F-Crest Pro-Health-Whitening, and G-Deionized water (DIW). Teeth were mounted on acrylic blocks, and their root surfaces covered with acrylic resin, except for 2-mm near the cemento-enamel junction that was exposed to toothbrushing. Specimens were brushed with the slurries for 5000-, 15,000-, 35,000- and 65,000-strokes. Impressions were taken at baseline and after each brushing time, and then scanned by a 3D optical profilometer. Dentine volume loss was calculated by image subtraction software and subjected to mixed-model ANOVA and multiple comparison tests (α = 0.05). Results No significant differences among slurries were observed at 5000 and 15,000. At 35,000, F showed higher loss than all other groups except C, which did not differ from the others. At 65,000, F (4.19 ± 3.29 mm3) showed the highest loss, followed by C (2.33 ± 1.47 mm3), which differed from all the other groups except B (1.85 ± 0.91 mm3). Groups B, A (1.35 ± 0.65 mm3), D (1.17 ± 0.48 mm3), E (1.40 ± 0.68 mm3) and G (1.12 ± 0.73 mm3) did not differ from each other. Groups F and C showed significant increase of volume loss starting at 35,000, while B, A, D and E only at 65,000; no increase loss was observed for G. Conclusions 3D-image subtraction was able to quantify and differentiate tooth loss, but only at advanced stages. The progression of NCCLs was more evident and faster for highly abrasive slurries. Clinical significance Upon root dentin exposure, brushing with lower abrasive dentifrices is advisable to reduce the risk for NCCLs development.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 The ability of dual whitening anti-caries mouthrinses to remove extrinsic staining and enhance caries lesion remineralization – An in vitro study(Elsevier, 2020) Al-Shahrani, Ahid A.; Levon, John A.; Hara, Anderson T.; Tang, Qing; Lippert, Frank; Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjectives This laboratory study investigated the ability of dual whitening anti-caries mouthrinses to remove extrinsic staining from artificially stained caries lesions and to enhance their remineralization and fluoridation. Materials and Methods Early caries lesions were created in bovine enamel specimens. The lesions were artificially stained and pH cycled for 10 days with the daily cycling regimen consisting of twice daily 60s-treatments with one of 11 mouthrinses, a 4-h demineralization period and artificial saliva treatments in between. Mouthrinses were eight commercially available products, all containing 100 ppm fluoride but utilizing hydrogen peroxide, pyro-, tri- or hexametaphosphate salts and/or sodium bicarbonate. The three control mouthrinses were 100 ppm fluoride, 30 % hydrogen peroxide and deionized water. Enamel color changes (ΔE) were determined spectrophotometrically. Vickers surface microhardness (VHN) was used to determine lesion remineralization. Enamel fluoride content (EFC) was determined using the microbiopsy technique. Data were analyzed using ANOVA. Results ΔE was significantly different among groups (p = 0.0045). Thirty percent hydrogen peroxide was superior to all other mouthrinses, while there were no differences between commercial mouthrinses and deionized water. There were small, directional but non-significant differences between commercial mouthrinses with those containing hydrogen peroxide providing better whitening. There were no significant differences between mouthrinses in their ability to remineralize caries lesions (p = 0.2898). EFC differed among groups (p < 0.0001), with the two mouthrinses containing pyrophosphate salts having lower EFC than all but the deionized water group. Conclusions Artificially stained caries lesions show reduced susceptibility to fluoride remineralization and whitening effects of commercial whitening and anti-caries mouthrinses. Clinical Relevance Artificially stained caries lesions appear to require stronger than over-the-counter interventions to successfully whiten and remineralizing them.Item Age effect on presence, susceptibility and treatment of erosive tooth wear(2018) Algarni, Amnah Abdullah; Hara, Anderson T.; Lippert, Frank; Platt, Jeffrey A.; González-Cabezas, Carlos; Ungar, PeterErosive tooth wear (ETW) is a growing dental condition often associated with aging. This in-vitro project comprised three studies aiming to investigate the impact of tooth age on ETW susceptibility and prevention. In the first study, un-identified extracted premolars were collected and had their ages estimated using validated dental forensic methods. The premolars were examined to investigate the relationship between age and presence and severity of ETW, as well as other main dental-hard tissues conditions. ETW, dental caries, fluorosis, extrinsic staining and tooth color were evaluated using established clinical indices. In the second study, the tooth age impact on ETW susceptibility and response to preventive treatments (Sn+F, NaF, and de-ionized water control) were evaluated using representative samples from the initial study. Enamel and dentin specimens were prepared and subjected to daily erosion-treatmentremineralization cycling procedure. Surface loss (SL) was determined during and after the cycling, by optical profilometry. Similar protocol was adopted in the third study with the addition of toothbrushing abrasion to the model, in order to explore the interplay between age and toothpaste abrasivity on erosion-abrasion development. SL was measured during and after the erosion-toothbrushing-remineralization cycling. The relationships between age and the investigated variables were assessed using linear regression models. In conclusion: 1. The presence and severity of ETW, dental caries, and extrinsic staining increased with age, while of enamel fluorosis decreased. Tooth also showed to be darker with age. 2. Susceptibility of enamel and dentin to demineralization increased with age. Sn+F showed the highest anti-erosive efficacy, and was not affected by age. NaF showed lower efficacy on dentin, which increased with age. 3. Enamel and dentin SL increased with toothpaste abrasivity level. Dentin SL also increased with age. Age effect on enamel SL was observed only with low abrasive toothpaste. Age-related changes on enamel and dentin affected ETW development.Item Anticaries Potential of a Sodium Monofluorophosphate Dentifrice Containing Calcium Sodium Phosphosilicate: Exploratory in situ Randomized Trial(Karger, 2017-03) Parkinson, C. R.; Siddiqi, M.; Mason, S.; Lippert, Frank; Hara, Anderson T.; Zero, Domenick T.; Cariology, Operative Dentistry and Dental Public Health, School of DentistryCalcium sodium phosphosilicate (CSPS) is a bioactive glass material that alleviates dentin hypersensitivity and is postulated to confer remineralization of caries lesions. This single-centre, randomized, single (investigator)-blind, placebo-controlled, crossover, in situ study explored whether the addition of 5% CSPS to a nonaqueous fluoride (F) such as sodium monofluorophosphate (SMFP)-containing dentifrice affects its cariostatic ability. Seventy-seven subjects wore 4 gauze-covered enamel specimens with preformed lesions (2 surface-softened and 2 subsurface) placed buccally on their mandibular bilateral dentures for up to 4 weeks. Subjects brushed twice daily with 1 of the 5 study dentifrices: 927 ppm F/5% CSPS, 927 ppm F/0% CSPS, 250 ppm F/0% CSPS, 0 ppm F/5% CSPS, or 0 ppm F/0% CSPS. Specimens were retrieved after either 21 (surface-softened lesions; analyzed by Knoop surface microhardness [SMH]) or 28 days (subsurface lesions; analyzed by transverse microradiography). The enamel fluoride uptake was determined for all specimens using a microbiopsy technique. The concentrations of fluoride and calcium in gauze-retrieved plaque were also evaluated. Higher dentifrice fluoride concentrations led to greater remineralization and fluoridation of both lesion types and increased plaque fluoride concentrations. CSPS did not improve the cariostatic properties of SMFP; there were no statistically significant differences between 927 ppm F/5% CSPS and 927 ppm F/0% CSPS in percent SMH recovery (p = 0.6788), change in integrated mineral loss (p = 0.5908), or lesion depth (p = 0.6622). Likewise, 0 ppm F/5% CSPS did not provide any benefits in comparison to 0 ppm F/0% CSPS. In conclusion, CSPS does not negatively impact nor does it improve the ability of an SMFP dentifrice to affect remineralization of caries lesions.Item Are dental patients able to perceive erosive tooth wear on anterior teeth? An internet-based survey assessing awareness and related action(Elsevier, 2020) Goldfarb, Micah B.; Hara, Anderson T.; Hirsh, Adam T.; Carvalho, Joana C.; Maupomé, GerardoBackground. Erosive tooth wear (ETW) is irreversible loss of dental hard tissue. The authors examined patients’ ability to recognize ETW relative to sound teeth and teeth with dental caries. Methods. Using Amazon’s crowdsourcing service, the authors recruited participants (N=623) to view standardized images of buccal surfaces of teeth (sound, ETW, or caries). Participants reported whether a dental condition existed (yes/no), likelihood to seek care, and esthetic attractiveness for teeth with no, initial, moderate, or severe signs of ETW/caries. Results. Dental patients demonstrated poor recognition of cases of ETW, especially compared to sound and caries-affected teeth at each level of severity. Patients were less likely to schedule a dental appointment for care/treatment of teeth with ETW than caries at each level of severity. Patients also found ETW more esthetically attractive than caries at each level of severity and found initial ETW more attractive than sound teeth. Conclusions. Dental patients struggle recognizing ETW, in general and compared to caries, at each level of severity and particularly for early stages of ETW. These recognition difficulties likely arise, in part, from tooth esthetic attractiveness standards (smooth and shiny teeth look more esthetic), possibly leading to lack of appropriate care-seeking behavior. Practical Implications. This internet-based tool may be used to assess dental patients’ awareness and ability to recognize cases of ETW. Improved patient awareness might lead to seeking professional care to prevent and/or delay ETW progression.Item Artificial biofilm thickness and salivary flow effects on fluoride efficacy – A model development study(2017-10-26) Lippert, Frank; Hara, Anderson T.; Churchley, David; Lynch, Richard J. M.This laboratory model development study investigated the interaction between artificial biofilm thickness and salivary flow rate on fluoride-mediated prevention of enamel caries lesion formation. This 5-day pH cycling study on sound bovine enamel specimens utilized a continuous flow model and followed a 4 (agarose biofilm thickness-‘no biofilm’/1/2/3mm)×2 (remineralizing solution flow rate-0.05/0.5ml/min)×2 (fluoride-0/383ppm as sodium fluoride) factorial design. Vickers surface microhardness change was the outcome measure. Data were analyzed with three-way ANOVA. The three-way interaction gel thickness×flow rate×fluoride concentration was significant (p=0.0006). 383ppm fluoride caused less softening than 0ppm regardless of gel thickness or flow rate. 0.5ml/min flow rate caused less softening than 0.05ml/min for ‘no biofilm’ and 1mm biofilm thickness regardless of fluoride concentration, for 2 and 3mm with 0ppm F but not for 383ppm F. For 0.05ml/min, softening was reduced as gel thickness increased from ‘no biofilm’-1-2mm, but not from 2-3mm. For 0.5ml/min, ‘no biofilm’ caused more softening than 1, 2, and 3mm, but 1, 2, and 3mm were not different from each other for both 0 and 383ppm F. The present findings suggest that the efficacy of fluoride in preventing enamel demineralization is affected by both biofilm thickness and salivary flow rate, with both thicker biofilms and higher flow rate resulting in less demineralization.Item Beam profile characterization of light-emitting-diode curing units and its effect on polymerization of a resin-matrix composite(2017) AlZain, Afnan Omar; Platt, Jeffrey A.; Chu, Tien-Min G.; Bottino, Marco C.; Hara, Anderson T.; Goodpaster, John V.; Roulet, Jean-FrancoisThe general aim of this study was to investigate the influence of the localized irradiance beam profiles from multiple light-emitting-diode (LED) light-curing units (LCUs) on the polymerization pattern within a resin-matrix composite (RMC). Irradiance beam profiles were generated from one quartz-tungsten-halogen and various single and multiple emission peak LED LCUs using a camera-based beam profiler system combined with LCU power measurements obtained using an integrating sphere/spectrometer assembly. The influence of distance on irradiance, radiant exposure (RE) and degree of conversion (DC) on the top and bottom surfaces of a RMC increment, using various LCUs, at two clinically relevant distances was investigated. Molar absorptivity of the photoinitiators present in the nano-hybrid RMC (Tetric EvoCeram bleaching shade-XL) assessed was using UV-spectrophotometry. The correlation among irradiance, RE and DC was explored. A mapping approach was used to investigate DC, microhardness and cross-link density (CLD) within 5×5×2 mm specimens at various depths; top, 0.5, 0.7, 0.9, 1.1, 1.3,1.5 mm and bottom. The localized irradiance correlation with its corresponding DC, microhardness and CLD was explored, and localized DC correlation with microhardness was assessed. The DC was measured using micro-Raman spectroscopy, and CLD was assessed by an ethanol-softening method (%KHN reduction) using an automated microhardness tester. Molar absorptivity of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide was 20-fold higher than camphorquinone. Non-uniform LCU beam profiles caused localized polymerization discrepancies that were significant at specific depths and points within the specimens with respect to DC, microhardness and CLD, which did not follow a specific pattern regardless of the LCU or curing distance assessed. A moderate correlation was displayed among irradiance, RE and DC. The localized irradiance from the LCUs was weakly correlated with the corresponding DC, microhardness and CLD on the top surface of a RMC at both curing distances. The localized microhardness was moderately correlated with DC. In conclusion, polymerization within the RMC investigated was non-uniform and did not reflect the LCU irradiance pattern at the area assessed. Also, a mapping approach within the specimens provided a detailed polymerization pattern assessment occurring within a RMC increment. Therefore, the LCUs explored may potentially increase the risk of RMC fracture.Item Biodegradability of resilon, a resin based root canal obturating material, by typical endodontic pathogens(2012) Rexford, Ashleigh M.; Spolnik, Kenneth Jacob, 1950-; Vail, Mychel Macapagal, 1969-; Hara, Anderson T.; Ehrlich, Ygal; Zunt, Susan L., 1951-; Gregory, Richard L.; Legan, Joseph J.Root canal therapy is a recommended treatment for apical periodontitis. Root canal failure can occur as a result of microbial leakage. Resilon, a resin based root canal obturating cone material introduced in 2004 attempts to minimize leakage by a unique bonding method of the resin sealer to both the core material and to the dentin of the canal walls. Resilon has no bactericidal or antimicrobial effect15. Furthermore, it has been shown that Resilon is susceptible to alkaline and enzymatic hydrolysis as well as bacterial degradation.73, 184-186 It has been suggested that Resilon may be susceptible to degradation by microorganisms found in the infected root canal space. This work focuses on the susceptibility of root canal obturating materials to be degraded by endodontic pathogens seen in root canal treated teeth with apical periodontitis. The aim of this study was to determine if Resilon could be degraded by selected pathogenic bacteria found in the infected root canal system, and if this degradation is more severe than with gutta-percha, a conventional obturating material. P. intermedia, E. faecalis and P. aeruginosa, known endodontic pathogens were inoculated on discs of obturating material (Resilon or gutta-percha) mounted on a platform and placed in wells containing TSB incubated at 37°C under aerobic conditions. The discs were polished, examined by SEM, profilometry, and elemental analysis prior to inoculation to establish a baseline, and were then re-examined by these methods one month after inoculation. The overall results were inconclusive; and using these methods it cannot be determined that the selected bacteria can degrade Resilon. An ideal future study would utilize SEM with gold coated samples as well as atomic force microscopy to evaluate for changes in topographical features of these obturating materials. A notable finding was that Resilon turns black when exposed to bacteria, and the significance of this finding should be addressed in future studies.Item Comparison Between Radiotracer and Surface Profile Methods for the Determination of Dentifrice(Office of the Vice Chancellor for Research, 2013-04-05) Sabrah, Alaa; Lippert, Frank; Kelly, Adam B.; Hara, Anderson T.Introduction: ISO11609 states that a surface profile (Sp) method can be used to determine dentifrice abrasivity in relation to dentin (RDA) as an alternative to the traditional radiotracer method (Rt). A comparison between both methods was performed in this study. Methods: Specimens from human root dentin were prepared for each method and randomly assigned to 8 dentifrice/abrasive groups (n=8), which represented a wide abrasivity range. Aqueous dentifrice slurries or abrasive suspensions in a solution containing 0.5% carboxymethylcellulose and 10% glycerin were used to brush specimens in a custom-made V-8 cross-brushing machine. Two independent studies (Sp, Rt) were carried out. For Rt, the specimen preparation, study design, analysis and calculation of the abrasive level (RDA) followed the ISO11609/Annex A guidelines. Similarly for Sp, the ISO11609/Annex B recommendations were followed, except by the number of brushing strokes, which was pre-determined to be 2000 strokes (instead of 10000) in a preliminary test. Data were analyzed using ANOVA and Tukey tests, with significance level set at 5%. The correlation between methods was also investigated. Results: Overall, higher variation and RDA values were observed for the Sp method compared to Rt. While good correlation was found between methods (R2=0.841), group ranking was dissimilar and better statistical differentiation among groups was observed in Rt. Conclusions: The Rt method showed to be a more standardized and robust method compared to Sp for the determination of RDA values of dentifrices/abrasives. Sp needs to be further developed before being considered as an equivalent test method for RDA. The determination of the abrasive levels of toothpastes using standard testing methods is important to guide oral care professionals and patients on the prevention of toothbrushing abrasive wear.