Lena Karlsson

Caries Detection Methods Based on Changes in Optical Properties between Healthy and Carious Tissue

A conservative, noninvasive or minimally invasive approach to clinical management of dental caries requires diagnostic techniques capable of detecting and quantifying lesions at an early stage, when progression can be arrested or reversed. Objective evidence of initiation of the disease can be detected in the form of distinct changes in the optical properties of the affected tooth structure. Caries detection methods based on changes in a specific optical property are collectively referred to as optically based methods. This paper presents a simple overview of the feasibility of three such technologies for quantitative or semiquantitative assessment of caries lesions. Two of the techniques are well-established: quantitative light-induced fluorescence, which is used primarily in caries research, and laser-induced fluorescence, a commercially available method used in clinical dental practice. The third technique, based on near-infrared transillumination of dental enamel is in the developmental stages.

Effect of supplementary amine fluoride gel in caries-active adolescents. A clinical QLF study

Objective. To investigate whether supplementary daily use of amine fluoride toothpaste with weekly brushing with amine fluoride gel enhances the remineralization of white spot lesions on smooth surfaces and also to investigate the possible effect of this treatment on salivary bacterial counts and oral hygiene. Material and Methods. The participants comprised 135 caries-active adolescents living in suburban Stockholm. They were given an amine fluoride dentifrice (1250 ppm F) to be used twice a day, and either a test gel (4000 ppm F) or a placebo gel for brushing for 2 min once a week. During the 12-month study period, the subjects were recalled every 3rd month (baseline, 3, 6, 9, and 12 months). At each visit, ΔF (average change in fluorescence, in%) and lesion area (in mm2) were measured using quantitative light-induced fluorescence (QLF), followed by dietary counseling, oral hygiene instruction, and professional tooth-cleaning. At baseline, 6, and 12 months, saliva was sampled for Streptococcus mutans and lactobacillus counts, and gingival bleeding index was registered. Results. QLF indicated no enhancement of remineralization of white spot lesions by additional weekly brushing with amine fluoride gel. No inter-group differences emerged with regard to salivary bacterial counts. However, the oral hygiene of both groups improved, with a strong significance over time. Conclusion. Adjunctive weekly brushing of amine fluoride gel achieved no significant enhancement of remineralization of white spot lesions monitored with the QLF method.

DIAGNOdent measurements of cultures of selected oral bacteria and demineralized enamel

Abstract Objective. Carious tissue fluoresces with a wavelength different from sound tissue when stimulated by light with a wavelength of 655 nm. This difference is thought to have a bacterial origin rather than indicating demineralization. This study aimed to measure fluorescence emitted by normal cultivable caries-associated bacterial flora and typical porphyrin-producing bacteria with DIAGNOdent, and to verify earlier findings that demineralization of the dental hard tissue does not affect DIAGNOdent readings. Material and methods. Bacterial samples were collected from five occlusal caries lesions in three subjects. From these, mixed anaerobic flora, Lactobacilli and mutans Streptococci were cultured in up to three different kinds of culture medium. Colonies of Lactobacilli and mutans Streptococci were also measured after transferring them to glass slides. Laboratory teaching strains of Prevotella spp., Porphyromonas gingivalis and Actinomyces odontolyticus were cultured anaerobically and fluorescence measured directly after an appropriate incubation period. Sound enamel surfaces of 15 extracted premolars were demineralized and changes in fluorescence measured. Results. DIAGNOdent readings > 20 were only obtained from young colonies of Prevotella and from colonies of mutans Streptococci cultured on mitis–salivarius–bacitracin agar. Higher measurements were obtained as the bacterial colonies aged. Lower measurements were obtained after transferring colonies to glass slides. Demineralization of enamel did not affect the DIAGNOdent measurements. Conclusions. The change in fluorescence measured with DIAGNOdent has a bacterial origin rather than occurring as a result of demineralization. The measurements are presumably dependent on bacterial metabolites rather than bacteria themselves, and probably record synergistic effects during the carious process rather than the quantity or species of bacteria involved.

Comparison among gold standard techniques used for the validation of methods for occlusal caries detection

The aim of this in vitro study was to assess the agreement among four techniques used as gold standard for the validation of methods for occlusal caries detection. Sixty‐five human permanent molars were selected and one site in each occlusal surface was chosen as the test site. The teeth were cut and prepared according to each technique: stereomicroscopy without coloring (1), dye enhancement with rhodamine B (2) and fuchsine/acetic light green (3), and semi‐quantitative microradiography (4). Digital photographs from each prepared tooth were assessed by three examiners for caries extension. Weighted kappa, as well as Friedmans test with multiple comparisons, was performed to compare all techniques and verify statistical significant differences. Results: kappa values varied from 0.62 to 0.78, the latter being found by both dye enhancement methods. Friedmans test showed statistical significant difference (P < 0.001) and multiple comparison identified these differences among all techniques, except between both dye enhancement methods (rhodamine B and fuchsine/acetic light green). Cross‐tabulation showed that the stereomicroscopy overscored the lesions. Both dye enhancement methods showed a good agreement, while stereomicroscopy overscored the lesions. Furthermore, the outcome of caries diagnostic tests may be influenced by the validation method applied. Dye enhancement methods seem to be reliable as gold standard methods. Microsc. Res. Tech., 2012.

Combination of high-fluoride toothpaste and no post-brushing water rinsing on enamel demineralization using an in-situ caries model with orthodontic bands

Abstract Objective. To compare the effects on enamel demineralization and fluoride (F) retention of two different brushing–rinsing regimens. Material and methods. An in-situ caries model with orthodontic bands was used for 8–9 weeks. A total of 20 orthodontic patients participated. They were randomized into two groups: (1) a test group using 5000 ppm F (n = 10) with no post-brushing water rinsing; and (2) a control group using 1450 ppm F (n = 10) with three sessions of post-brushing water rinsing. Orthodontic stainless-steel bands were applied to the two upper first premolars, leaving 2–3 mm of space away from the exposed buccal surface in order to accumulate plaque and provoke initial caries development. The teeth were extracted after 8 and 9 weeks, then analysed using quantitative light-induced fluorescence (QLF). Additionally, oral F retention was compared for the two groups. Results. In comparison to the control group, the test regimen resulted in a non-significant smaller QLF lesion area and a significantly lower average QLF loss of fluorescence (P < 0.05). The highest F retention concentration under the band was found in the test group (P < 0.001). Conclusions. The combination of using a 5000 ppm F toothpaste and no post-brushing water rinsing had a greater anti-caries potential and resulted in elevated oral F retention compared to a 1450 ppm F toothpaste with three sessions of post-brushing water rinsing.

Effect of fluoridated milk on enamel demineralization adjacent to fixed orthodontic appliances

Abstract Objective. To investigate the effect of daily intake of fluoridated milk on enamel demineralization adjacent to fixed orthodontic brackets assessed with quantitative light-induced fluorescence (QLF). Materials and methods. Sixty-four healthy adolescents (13–18 years) undergoing orthodontic treatment with fixed appliances were enrolled and randomly allocated to a randomized controlled trial with two parallel groups. The intervention group was instructed to drink one glass of milk (∼ 200 ml) supplemented with fluoride (5 ppm) once daily and the subjects of the control group to drink the same amount of milk without fluoride. The intervention period was 12 weeks and the end-point was mineral gain or loss in enamel, assessed by QLF on two selected sites from each individual. The attrition rate was 12.5% and 112 sites were included in the final evaluation. Results. There was no statistically significant difference between the groups concerning fluorescence (ΔF) values and lesion area (A mm2) at baseline. After 12 weeks, a significant decrease (p < 0.05) in ΔF was registered in the fluoridated milk group and a significant increase in the non-fluoride control group (p < 0.05). The mean reduction in the test group was somewhat lower (14%) than the increase in the control group (18%), but individual variations were evident. Only minor alterations of lesion area were recorded over the 12-week period and no statistically significant differences compared with baseline were found in any of the groups. Conclusion. Daily intake of fluoridated milk may aid remineralization of white spot lesions adjacent to fixed orthodontic appliances.

Evaluation of dental enamel caries assessment using Quantitative Light Induced Fluorescence and Optical Coherence Tomography.

An in vitro study of morphological alterations between sound dental structure and artificially induced white spot lesions in human teeth, was performed through the loss of fluorescence by Quantitative Light-Induced Fluorescence (QLF) and the alterations of the light attenuation coefficient by Optical Coherence Tomography (OCT). To analyze the OCT images using a commercially available system, a special algorithm was applied, whereas the QLF images were analyzed using the software available in the commercial system employed. When analyzing the sound region against white spot lesions region by QLF, a reduction in the fluorescence intensity was observed, whilst an increase of light attenuation by the OCT system occurred. Comparison of the percentage of alteration between optical properties of sound and artificial enamel caries regions showed that OCT processed images through the attenuation of light enhanced the tooth optical alterations more than fluorescence detected by QLF System. QLF versus OCT imaging of enamel caries: a photonics assessment.

Near-infrared transillumination of teeth: measurement of a system performance

Transillumination (TI) of dental enamel with near-infrared light is a promising nonionizing imaging method for detection of early caries lesion. Increased mineral loss (caries lesion) leads to increased scattering and absorption. Caries thus appear as dark regions because less light reaches the detector. The aim of this work was to characterize the performance of a TI system from the resolution of acquired images using the modulation transfer function at two wavelengths, 1.28 and 1.4 mum. Test charts with various values of spatial periods, mimicking a perfect caries lesion, were attached to tooth sections, followed by capture of the transmitted image, using both wavelengths. The sections were then consecutively reduced in thickness, and a sequence of all sizes of the test charts were used for repeatedly imaging procedures. The results show that the TI system can detect feature size of 250 mum with 30% modulation. From the information about how the image degrades as it propagates through enamel, we also examined the possibility of estimating the position of a simulated approximal caries lesion by comparing images obtained from the two sides of a tooth section.

Approximal caries increment in adolescents after a visual aid in combination with a comprehensive open discussion

Abstract Objective. To achieve greater motivation for behavioural changes; educating, motivating and supporting the patients ability to change lifestyle factors related to the caries disease are important tasks in the prevention of the disease. The aim of this study was to evaluate whether a visual aid (Visual Caries Dialogue, VCD) in combination with a comprehensive open discussion has a beneficial effect on approximal caries development among a population of young adolescents. Materials and methods. The study subjects were randomized to either an intervention group (n = 118), where VCD was conducted, or a control group (n = 112) receiving traditional oral healthcare information, at the annual dental health examination. The number of caries lesions reaching through the entire enamel (D2) and dentin caries reaching through the enamel into the dentin (D3) were recorded from bitewing radiographs each year, from 2001–2004. Differences between the study groups regarding at least two new approximal surfaces with caries (D2–D3) were tested using logistic regression. Results. The caries increment was lower in the intervention group compared to the control group. During the 3-year follow-up, 18 (15.3%) patients in the intervention group and 40 (35.7%) patients in the control group demonstrated a DS-approximal increment of at least two surfaces with a risk ratio of 2.34 (95% CI = 1.43–3.83). Conclusion. Visual Caries Dialogue in combination with a comprehensive open discussion reduced approximal caries increment among young individuals. The method provides an innovative simple and low-cost way of delivering information to patients and guides busy dental healthcare personnel in the approach.