Progression Of Enamel Lesions Research Articles

Correlation between Lesion Progression and Depolarization Assessed by Polarization-Sensitive Optical Coherence Tomography

The detection of early stages of caries is still one of the major challenges in preservative dentistry. Since it is known from polarized light microscopy (PLM) that intrinsic enamel birefringence is affected by demineralization, polarization-sensitive optical coherence tomography (PSOCT) could facilitate the noninvasive detection and assessment of early carious lesions. The present study aims to correlate enamel lesion progression and depolarization measurements based on PSOCT in an artificial demineralization model. A total of 18 enamel slabs were prepared from bovine incisor teeth and demineralized in an acetic buffer solution for up to 49 days. The degree of polarization (DOP)—indicating depolarization and thus, demineralization—was calculated from PSOCT measurements and compared to lesion depth which was measured from PLM images. Artificial lesions showed characteristic zones of natural enamel demineralization in PLM images. DOP representations showed no depolarization for sound, nondemineralized enamel, whereas significant changes were found after 15 days of acid-exposition. The linear regression analysis of the DOP and the measured lesion depth showed a substantial correlation ( R 2 = 0.71 ). The results indicate that PSOCT-based depolarization imaging provides an unambiguous contrast for initial enamel demineralization which is correlated to the lesion progression.

CO2 laser irradiation enhances CaF2 formation and inhibits lesion progression on demineralized dental enamel-in vitro study.

This study evaluated if Carbon dioxide (CO2) (λ 10.6 μm) laser irradiation combined with acidulated phosphate fluoride gel application (APF gel) enhances "CaF2" uptake by demineralized enamel specimens (DES) and inhibits enamel lesion progression. Thus, two studies were conducted and DES were subjected to APF gel combined or not with CO2 laser irradiation (11.3 or 20.0 J/cm(2), 0.4 or 0.7 W) performed before, during, or after APF gel application. In study 1, 165 DES were allocated to 11 groups. Fluoride as "CaF2 like material" formed on enamel was determined in 100 DES (n = 10/group), and the surface morphologies of 50 specimens were evaluated by scanning electron microscopy (SEM) before and after "CaF2" extraction. In study 2, 165 DES (11 groups, n = 15), subjected to the same treatments as in study 1, were further subjected to a pH-cycling model to simulate a high cariogenic challenge. The progression of demineralization in DES was evaluated by cross-sectional microhardness and polarized light microscopy analyses. Laser at 11.3 J/cm(2) applied during APF gel application increased "CaF2" uptake on enamel surface. Laser irradiation and APF gel alone arrested the lesion progression compared with the control (p < 0.05). Areas of melting, fusion, and cracks were observed. CO2 laser irradiation, combined with a single APF application enhanced "CaF2" uptake on enamel surface and a synergistic effect was found. However, regarding the inhibition of caries lesion progression, no synergistic effect could be demonstrated. In conclusion, the results have shown that irradiation with specific laser parameters significantly enhanced CaF2 uptake by demineralized enamel and inhibited lesion progression.

An in vitro comparison of quantitative light-induced fluorescence-digital and spectrophotometer on monitoring artificial white spot lesions

The aim of this study was to evaluate the efficacy of quantitative light-induced fluorescence-digital (QLF-D) compared to a spectrophotometer in monitoring progression of enamel lesions. To generate artificial caries with various severities of lesion depths, twenty bovine specimens were immersed in demineralizing solution for 40 days. During the production of the lesions, repeat measurements of fluorescence loss (ΔF) and color change (ΔE) were performed in six distinct stages after the demineralization of the specimens: after 3, 5, 10, 20, 30, and 40 days of exposure to the demineralizing solution. Changes in the ΔF values in the lesions were analyzed using the QLF-D, and changes in the ΔE values in lesions were analyzed using a spectrophotometer. The repeated measures ANOVA of ΔF and ΔE values were used to determine whether there are significant differences at different exposure times in the demineralizing solution. Spearman's rank correlation coefficient was analyzed between ΔF and ΔE. The ΔF values significantly decreased based on the demineralizing period (p<0.001). Relatively large changes in ΔF values were observed during the first 10 days. There were significant changes in L(*), a(*), b(*), and ΔE values in lesions with increasing demineralizing duration (p<0.001). A strong correlation was observed between ΔF and ΔE with p=-0.853 (p<0.001). The results support the efficacy of QLF-D in monitoring color changes. Our findings demonstrate that QLF-D are a more efficient and stable tool for early caries detection.

Effect of hydration on assessment of early enamel lesion using swept‐source optical coherence tomography

Establishing reproducible methodologies for assessment of early enamel lesions using optical coherence tomography (OCT) appears to be challenging. This in vitro study longitudinally evaluated the subsurface enamel lesion progression after 3, 9 and 15 days by cross-sectional scanning using 1310 nm centered swept-source OCT (SS-OCT) under hydrated and dry conditions. The positive difference between the depth-integrated OCT signals at dry and hydrated conditions were calculated and adopted as dehydration parameter (DH). A linear regression was found between DH and the square root of demineralization time (R(2) = 0.99). Significant differences were found in DH between sound and demineralized enamel, and between different periods of demineralization (p < 0.001). Hydration state affects the reflectivity of demineralized porous enamel, and the effect can be potentially used for assessment of early enamel lesion using OCT.

Microbial community succession on developing lesions on human enamel

BackgroundDental caries is one of the most common diseases in the world. However, our understanding of how the microbial community composition changes in vivo as caries develops is lacking.ObjectiveAn in vivo model was used in a longitudinal cohort study to investigate shifts in the microbial community composition associated with the development of enamel caries.DesignWhite spot lesions were generated in vivo on human teeth predetermined to be extracted for orthodontic reasons. The bacterial microbiota on sound enamel and on developing carious lesions were identified using the Human Oral Microbe Identification Microarray (HOMIM), which permits the detection of about 300 of the approximate 600 predominant bacterial species in the oral cavity.ResultsAfter only seven weeks, 75% of targeted teeth developed white spot lesions (8 individuals, 16 teeth). The microbial community composition of the plaque over white spot lesions differed significantly as compared to sound enamel. Twenty-five bacterial taxa, including Streptococcusmutans, Atopobiumparvulum, Dialisterinvisus, and species of Prevotella and Scardovia, were significantly associated with initial enamel lesions. In contrast, 14 bacterial taxa, including species of Fusobacterium, Campylobacter, Kingella, and Capnocytophaga, were significantly associated with sound enamel.ConclusionsThe bacterial community composition associated with the progression of enamel lesions is specific and much more complex than previously believed. This investigation represents one of the first longitudinally-derived studies for caries progression and supports microbial data from previous cross-sectional studies on the development of the disease. Thus, the in vivo experiments of generating lesions on teeth destined for extraction in conjunction with HOMIM analyses represent a valid model to study succession of supragingival microbial communities associated with caries development and to study efficacy of prophylactic and restorative treatments.

Progression of Artificial Enamel Caries Lesions after Infiltration with Experimental Light Curing Resins

The arrest of enamel caries lesions by infiltration with low-viscosity light curing resins might be a promising approach of microinvasive dentistry. However, no materials optimized for rapid lesion infiltration (‘infiltrants’) are commercially available today. The penetration coefficient (PC) of experimental resins has been shown to correlate with penetration speed and, therefore, might be an important feature of infiltrants. The aim of the present study was to evaluate the influence of PC and composition of experimental infiltrants on the progression of enamel lesions in a demineralizing environment. Artificial enamel lesions were prepared in a demineralization solution for 50 days and infiltrated with either one of twelve experimental infiltrants or a commercially available adhesive for 10, 22, and 40 s, respectively. Specimens were cut perpendicularly to the surface and one half of each specimen was exposed to a demineralizing solution for another 50 days, whereas the other half was used as baseline control. Lesion progression was analyzed using confocal microscopy (CLSM) and transversal microradiography (TMR). The square root of the product of PC and application time was negatively correlated with progression of lesion depth (CLSM: r = –0.741; TMR: r = –0.450). Therefore, infiltrants should preferably have high PCs to facilitate inhibition of lesion progression efficiently.

Incidence and progression of approximal carious lesions among school children in Western Australia

An understanding of carious lesion behaviour is important in timing and frequency of radiographic examinations. The aim of this study was to examine the occurrence and behaviour of approximal enamel lesions in permanent teeth among children in Western Australia and test the effect of easily measured factors on the rate of lesion progression. Bitewing radiographs of children enrolled with the School Dental Service in Western Australia were scored for the occurrence and progression of enamel caries using established criteria. Time to lesion occurrence was estimated by the use of the Kaplan-Meier analysis, bivariate tests of survival functions were undertaken using the log rank test and the influence of the measured factors were tested using the multivariate Cox proportional hazard model. The median time to occurrence of enamel caries was 6.1 months; median time to dentine caries was 77.7 months. Multivariate analysis shows gender (hazard ratio, male 0.65), baseline permanent tooth caries experience (hazard ratio 1.15) and time at risk since eruption (hazard ratio 0.88) were important factors in the initiation of enamel caries while time since eruption (hazard ratio 0.87), clinician's rating of risk (hazard ratio, moderate risk 2.78, high risk 5.00) and residence in fluoridated area (hazard ratio, fluoridate 0.44) were all statistically significant for enamel caries progression. Time to occurrence of enamel lesions in approximal surfaces is relatively rapid while progression into dentine is relatively slow. Clinicians were able to assign the risk of lesion progression in a child. Residence in a fluoridated area has a marked retarding effect on enamel lesion progression but not on initiation of enamel lesions. These factors may be useful in developing a schedule for timing and frequency of radiographic examinations among children in Western Australia.

Effects of different amounts of a low fluoride toothpaste on primary enamel lesion progression: a preliminary study using in vitro pH-cycling system

To evaluate and compare the efficacy of pea and half-pea portions of child formula fluoride (500 ppm) toothpaste on artificially created enamel lesions in primary teeth. Sound primary incisors were painted with nail varnish, leaving a 1 mm wide window and then placed in a demineralising solution for 96 h to produce artificial carious lesions 60-100 microm deep. The teeth were longitudinally sectioned (100 microm thick) and divided into 3 groups. Group A: treated with a pea-sized portion of a non-fluoride containing toothpaste (1:3, toothpaste: deionized water), while Groups B and C were treated with half-pea-sized and pea-sized portions of a 500 ppm fluoride containing toothpaste, respectively. The pH-cycling model was utilized for 7 days. Groups A and B lesions increased in depth by 60% while those in Group C increased by 19%. The mineral content of the surface zone decreased significantly in Groups A and B but not in Group C. Reduction of the amount of fluoride toothpaste to less than a pea-size in order to minimize the risk of fluorosis should be undertaken with caution because it may compromise the cariostatic effects of the toothpaste.

Effect of School-Based Fluoride Varnish Programmes on Approximal Caries in Adolescents from Different Caries Risk Areas

The aim was to evaluate, in a 3-year RCT study, school-based fluoride varnish programme on approximal caries incidence and approximal caries progression in 13- to 16-year-olds in high, medium and low caries risk areas on the Swedish west coast. Seven hundred and fifty-eight (89%) fulfilled the trial. Using a simple mobile unit, 2 dental nurses treated the adolescents with F varnish: (1) twice a year at 6-month intervals, (2) 3 times a year within 1 week, (3) 8 times per year during the semesters with 1-month intervals, and (4) no treatment (control). Radiographic caries recording was performed blindly by one of the authors. Concerning total approximal caries incidence, control groups in all areas developed more caries than F varnish groups, with the largest difference in the high risk area: 3.05 ± 3.37 new approximal caries lesions (mean ± SD) compared to 0.54 ± 1.26 for group 3, 0.95 ± 1.67 for group 1 and 1.40 ± 1.89 for group 2 (p < 0.001). More than 90% of the new approximal lesions in all the groups and in all areas consisted of new enamel lesions. Regarding progression of enamel lesions, there were only significant differences between groups 1–3 and group 4 in the high caries risk area. Prevented fraction for fluoride varnish treatment twice a year at 6-month intervals was 69% in high, 66% in medium and 20% in low risk areas. To conclude, school-based F varnish treatment every 6 months in 13- to 16-year-olds is excellent to prevent approximal caries in medium and high caries risk areas.

The effect of different commercial dentifrices on enamel lesion progression: an in vitro pH-cycling study

To evaluate and compare the de/remineralization effects of dentifrices manufactured locally in some developing countries. Utilisation of the in vitro single-section and the pH-cycling model. Laboratory. TEST MATERIALS: Dentifrices: Maxam DFP, Maxam Tartar Control, First, Tianqi Medicated from China; Vicco Vajradenti from India; Colgate MFP2, Crest Tartar Control from USA; and one non-fluoride dentifrice as control. Sound molars were painted, leaving a 1 mm wide 'window' on the buccal and/or lingual surface and placed in a demineralisation solution for 96 h to produce artificial caries lesion approximately 80-100 mm deep. The teeth were then longitudinally sectioned (approximately 100 mm thick), and randomly divided into 8 groups (22 sections/group). The pH cycling model was utilised for 10 days. Polarised light microscopy and microradiography were used to evaluate the lesion progression before and after treatment. The control group showed an increase in lesion depth of 70 per cent and was statistically different from some test groups which ranged from -2 per cent to 68 per cent (P < 0.01, t-test). Statistically significant differences were also observed among some of the fluoride containing groups. This study suggests that, when compared to 'multinational dentifrices', Chinese and Indian dentifrices manufactured locally failed to show 'healing' efficacy even though they claimed to contain varying levels of fluoride.

Scanning and Contact Microradiographic Study of the Effect of Degree of Saturation on the Rate of Enamel Demineralization

The effect of degree of saturation with respect to hydroxyapatite (DSHA) on enamel section demineralization was studied by contact and scanning microradiography (CMR and SMR). Two aspects were studied: (1) the effect of different values of DSHA at constant pH, and (2) the effect of constant DSHA with variable pH. In the pH range (2.5-4.5) and time scale (0-120 h) studied, the DSHA was more important in determining the rate of enamel lesion progression than was the pH.

Longitudinal study of dental caries development in Dutch children aged 8-12 years.

In many Western societies caries experience in children has decreased substantially in areas both with and without organized preventive programs or water fluoridation. In the majority of studies reporting declining caries activity, cross-sectional data of the same age groups are compared. The purpose of the present study is to provide longitudinal data on the progress of dental caries in permanent first molars. 252 caries-active children, initially 8-yr old, were followed up from 1979 to 1983. At all three examinations lower socioeconomic (SES) children had a significantly higher caries experience than children the same age in middle and high SES classes. The D2MF-S counts did not change between age 8 and 10, but increased steeply between 10 and 12 yr of age. The D3MF-S counts, on the other hand, rose steadily in all SES classes. The phenomenon was caused by the progression of enamel lesions to dentinal lesions or fillings, leading to a concomitant decrease in the curves of incipient caries lesions (D2). The rise from age 10 to 12 is attributable to new developing enamel lesions. With regard to predilection sites, at all ages and in every SES class, the highest proportion of both indices was due to lesions in occlusal surfaces, followed by buccal and lingual pits and fissures. The approximal sites were the least affected.