Optical coherence tomography in the detection and diagnosis of dental enamel demineralisation areas

A cárie dentária e a erosão dentária são os principais problemas em odontologia. O diagnóstico correto, especialmente em lesões precoces, é vital para o plano de tratamento adequado. O exame visual-tátil e a radiografia dentária são os métodos mais utilizados para esse fim. A tomografia de coerência óptica (OCT) é outro método imagiológico capaz de melhorar o exame visual-tátil no diagnóstico de lesões em esmalte. A sensibilidade do instrumento é muito alta, geralmente mais de 90% e a especificidade normalmente acima de 95%. Utiliza o princípio da interferometria óptica com uma fonte de luz a emitir no infravermelho próximo (comprimento de onda na região de 1300 nm). Um software de processamento de imagens adequado pode melhorar a produção de imagens, incluir zonas colorimétricas e produzir uma imagem-3D, reduzindo a subjetividade na interpretação. Por não utilizar radiação ionizante e obter uma imagem nítida em tempo real, pode ser um bom substituto para a radiografia dentária em caso de avaliação diagnóstica de esmalte e dentina dentários.The dental caries and dental erosion are the major dental problems in dentistry. The correct diagnosis, especially in early lesions, is vital for the proper treatment plan. Visualtactile examination and dental radiography are the most used methods for this purpose. The optical coherence tomography (OCT) is another imaging tool with the capability to improve the visual-tactile examination in enamel diagnostic. The instrument sensitivity is very high, usually more than 90% as the specificity is usually higher than 95%. It uses the principle of optical interferometry with an optical source emitting in the near-infrared (wavelength close to 1300 nm). Proper processing image software can improve the imaging production and present a 3D-image as reduces subjectivity with a colorimetric presentation. As it not use ionising radiation and offers a clear image production in real time, can be a good substitute to dental radiography in case of enamel and outer dentin diagnostic assessment

<i>In situ</i> monitoring and analysis of enamel demineralisation using synchrotron X-ray scattering

Dental caries is one of the most common chronic diseases that affect human teeth. It often initiates in enamel, undermining its mechanical function and structural integrity. Little is known about the enamel demineralisation process caused by dental caries in terms of the microstructural changes and crystallography of the inorganic mineral phase. To improve the understanding of the carious lesion formation process and to help identify efficient treatments, the evolution of the microstructure at the nano-scale in an artificially induced enamel erosion region was probed using advanced synchrotron small-angle and wide-angle X-ray scattering (SAXS and WAXS). This is the first in vitro and time-resolved investigation of enamel demineralisation using synchrotron X-ray techniques which allows in situ quantification of the microstructure evolution over time in a simulated carious lesion. The analysis revealed that alongside the reduction of mineral volume, a heterogeneous evolution of hydroxyapatite (HAp) crystallites (in terms of size, preferred orientation and degree of alignment) could be observed. It was also found that the rate and direction of dissolution depends on the crystallographic orientation. Based on these findings, a novel conceptual view of the process is put forward that describes the key structural parameters in establishing high fidelity ultrastructure-based numerical models for the simulation of the enamel demineralisation process

In silico modelling to differentiate the contribution of sugar frequency versus total amount in driving biofilm dysbiosis in dental caries

Dental caries is the most prevalent infection globally and a substantial economic burden in developed countries. Dietary sugars are the main risk factor, and drive increased proportions of acid-producing and acid-tolerating (aciduric) bacterial species within dental bio lms. Recent longitudinal studies have suggested that caries is most strongly correlated with total sugar intake, contrasting with the prevailing view that intake frequency is the primary determinant. To explore this possibility, we employed a computational model for supragingival plaque to systematically sample combinations of sugar frequency and total amount, allowing their independent contributions on the ratio of aciduric (i.e. cariogenic) to non-aciduric bacteria to be unambiguously determined. Sugar frequency was found to be irrelevant for either very high or very low daily total amounts as the simulated bio lm was predicted to be always or never cariogenic, respectively. Frequency was a determining factor for intermediate total amounts of sugar, including the estimated average human consumption. An increased risk of caries (i.e. high prevalence of aciduric/non-aciduric species) was predicted for high intake frequencies. Thus, both total amount and frequency of sugar intake may combine to in uence plaque cariogenicity. These ndings could be employed to support public guidance for dietary change, leading to improved oral healthcare

Caries associated with orthodontic care part 1: aetiology, prevalence and prevention

The prevalence of demineralization, or enamel caries which is the first clinically recognizable stage of caries, has been reported to be as high as 73% during fixed appliance treatment. It is recognized that wearing an orthodontic appliance increases the caries risk of the individual. The orthodontist can effectively reduce demineralization by applying fluoride varnish at each visit. Selecting patients on their oral hygiene clearly is one factor which can prevent patients suffering from demineralization. Excellent home care with optimal use of fluoride will also help prevent the condition. There is little evidence that fluoride-releasing materials used for bonding orthodontic appliances offer protection from demineralization. The first of these two papers describes the aetiology, prevalence and prevention of demineralization associated with orthodontic care. The second paper will describe the treatments available to manage caries focusing on demineralization post orthodontic treatment. CPD/Clinical Relevance: Demineralization is the most common complication of orthodontic care. The clinician should understand how to prevent this

Caries associated with orthodontic care part 2: management

It is recognized that wearing an orthodontic appliance increases the caries risk of the individual. The prevalence of demineralization has been reported to be as high as 73%. When demineralization occurs a number of treatments exist: fluoride application, acid microabrasion, casein phosphopeptide-amorphous calcium phosphate (CCP-ACP), resin infiltration and self-assembling peptides. Of these, topical fluoride has the most evidence to support its use. CPD/Clinical Relevance: Demineralization is the most common complication of orthodontic care. The clinician should understand how to manage this when it occurs

3D analysis of enamel demineralisation in human dental caries using high- resolution, large field of view synchrotron X-ray micro-computed tomography

We report major advances in the analysis of synchrotron 3D datasets acquired from human healthy and carious dental enamel. Synchrotron tomographic data for three human carious samples and a non-carious reference tooth sample were collected with the voxel size of 325 nm for a total volume of 815.4 × 815.4 × 685.4 μm3. The results were compared with conventional X-ray tomography, optical microscopy, and focused ion beam-scanning electron microscopy. Clear contrast was seen within demineralised enamel due to reduced mineral content using synchrotron tomography in comparison with conventional tomography. The features were found to correspond with the rod and inter-rod structures within prismatic enamel. 2D and 3D image segmentation allowed statistical quantification of important structural characteristics (such as the aspect ratio and the cross-sectional area of voids, as well as the demineralised volume fraction as a function of lesion depth). Whilst overall carious enamel predominantly displayed a Type 1 etching pattern (preferential demineralisation of enamel rods), a transition between Type 2 (preferential inter-rod demineralisation) and Type 1 was identified within the same lesion for the first time. This study does not provide extensive results on the different lesions studied, but illustrate a new method and its potential application

Efficacy of enamel sealants in preventing demineralisation

Magister Chirurgiae Dentium - MChDTo compare the efficacy of two fluoride containing materials, namely, FluorSure and Duraphat, in protecting the enamel around and underneath the orthodontic brackets against decalcification.South Afric

EFFECTS OF ZINC AND FLUORIDE ON in vitro ENAMEL DEMINERALISATION CONDITIONS RELEVANT TO DENTAL CARIES

PhdZinc has been investigated extensively as an anti-plaque and calculus agent. However, its interaction with enamel and its putative role in demineralisation and remineralisation are considerably less understood. In comparison to zinc, the interactions between fluoride and enamel have been extensively reported in the literature. The overall aim was to understand the effects of zinc ions [Zn2+] on enamel demineralisation (relevant to dental caries), whilst the effect of fluoride ions [F–] were similarly studied and used as a benchmark for the zinc investigations. The independent effects of varying concentrations of [Zn2+] and [F–] on enamel demineralisation kinetics were investigated during in vitro caries-simulating conditions. Human enamel blocks were exposed to series of in vitro demineralising solutions consisting of 0.1 M acetic acid adjusted to pH 4.0, with increasing concentrations of [Zn2+] or [F–]. Scanning Microradiography (SMR) obtained accurate, real-time quantitative measurements of changes in enamel mineral mass, as they were exposed to [Zn2+] or [F–]-containing acid solutions. Further, amongst other characterisation techniques, ultralow Energy Secondary Ion Mass Spectrometry (uleSIMS) and 19F MAS-NMR were used for determination of possible surface physical-chemical mechanisms of [Zn2+] and [F–] on the enamel dissolution processes respectively. This study confirmed that zinc reduces enamel demineralisation during in vitro caries-simulating conditions. An overall log-linear relationship was observed between the reduction in demineralisation and increasing [Zn2+] up to 3565 ppm. Fluoride showed this log-linear relationship up to 135 ppm, however, further reductions in demineralisation were minimal above this concentration. 19F MAS-NMR established that fluorite (CaF2) predominantly formed above 135 ppm [F–], whereas fluorohydroxyapatite (FHAp) largely formed below 135 ppm. uleSIMS indicated that zinc was largely concentrated at the near-surface region of enamel, which suggested that zinc acts predominantly at the enamel crystal surface in its mechanism of reducing demineralisation. Thus, at low concentrations, zinc appeared to act at PO43– sites on enamel surfaces, possibly via an adsorption-type process and was confirmed to form an α-hopeite-like phase, once surface adsorption was complete at higher concentrations. These results have significant implications on the understanding of the fundamental chemical aspects of zinc in toothpastes and demonstrate its therapeutic potential in preventing tooth mineral loss