Effects of Infantile Hypophosphatasia on Human Dental Tissue.

Hypophosphatasia (HPP) is an inherited, systemic disorder, caused by loss-of-function variants of the ALPL gene encoding the enzyme tissue non-specific alkaline phosphatase (TNSALP). HPP is characterized by low serum TNSALP concentrations associated with defective bone mineralization and increased fracture risk. Dental manifestations have been reported as the exclusive feature (odontohypophosphatasia) and in combination with skeletal complications. Enzyme replacement therapy (asfotase alfa) has been shown to improve respiratory insufficiency and skeletal complications in HPP patients, while its effects on dental status have been understudied to date. In this study, quantitative backscattered electron imaging (qBEI) and histological analysis were performed on teeth from two patients with infantile HPP before and during asfotase alfa treatment and compared to matched healthy control teeth. qBEI and histological methods revealed varying mineralization patterns in cementum and dentin with lower mineralization in HPP. Furthermore, a significantly higher repair cementum thickness was observed in HPP compared to control teeth. Comparison before and during treatment showed minor improvements in mineralization and histological parameters in the patient when normalized to matched control teeth. HPP induces heterogeneous effects on mineralization and morphology of the dental status. Short treatment with asfotase alfa slightly affects mineralization in cementum and dentin. Despite HPP being a rare disease, its mild form occurs at higher prevalence. This study is of high clinical relevance as it expands our knowledge of HPP and dental involvement. Furthermore, it contributes to the understanding of dental tissue treatment, which has hardly been studied so far.

Root caries lesions inhibition and repair using commercial high-fluoride toothpastes with or without tri-calcium phosphate and conventional toothpastes containing or not 1.5% arginine CaCO3: an in situ investigation.

OBJECTIVES: This double-blind, crossover, and in situ study evaluated the effect of commercial high-F toothpastes with or without functionalized ß-tri-calcium phosphate (fTCP) and conventional-F toothpaste containing or not 1.5% arginine-CaCO3 in preventing and repairing root caries-like lesions. METHODS: Twelve volunteers wore palatal appliances containing sound (S) and pre-demineralized (PD) bovine root dentin blocks in 4 phases of 14 days/each. They used F toothpastes, 3×/day: (i) 1,450 µg F/g (conventional-F); (ii) 1,450 µg F/g + 1.5% arginine-CaCO3 (conventional-F + arginine/CaCO3); (iii) 5,000 µg F/g (high-F); and (iv) 5,000 µg F/g (high-F + fTCP). Sucrose solution (20%) was dropped 8×/day on the S blocks. The demineralization in the S blocks and the remineralization in the PD ones were estimated by % of surface hardness difference (%SH-S) and % of SH recovery (%SHR-PD), respectively. Caries lesion area (ΔS) was determined in the blocks. Statistical analyses were performed by one-way ANOVA/Kruskal-Wallis and multiple comparisons tests (p < 0.05). RESULTS: Both high-F toothpastes presented similar effect to prevent early caries lesions and it was higher than conventional-F + arginine/CaCO3. All treatments resulted in significantly lower ΔS values compared with conventional-F toothpaste (p < 0.0001). High-F + fTCP showed non-significantly higher preventive and reversible effect compared to high-F. The effect of conventional-F + arginine/CaCO3 was similar to high-F and lower than high-F + fTCP in preventing and reverting in-deep caries lesions. CONCLUSIONS: Overall, high-F toothpastes seem to be more effective and interesting feasible strategy for both prevention and remineralization actions in root dentin. CLINICAL RELEVANCE: With the trend of increasing dentin root caries, this study brings new evidences about the preventive and repair effect of high-F toothpastes with or without fTCP in root caries and support the use of arginine in toothpastes.

[Characteristics of dental hard tissues in chronic kidney disease: morphology, chemical composition, possibilities of remineralizing therapy]. / Kharakteristika tverdykh tkanei zubov pri khronicheskoi bolezni pochek: morfologiia, khimicheskii sostav, vozmozhnosti remineralizuiushchei terapii.

The aim of the work was an assessment of the morphological structure and chemical composition of dental hard tissues in persons suffering from chronic kidney disease and the effectiveness of remineralizing therapy in them. The study of the morphological structure and chemical composition of dental hard tissues in individuals suffering from chronic kidney disease and the effectiveness of 6 weeks of remineralizing therapy in the course of individual oral hygiene in combination with the intake of vitamin-mineral complex was conducted by means of ABT-55 electron microscope (Japan) combined with a LinkAN-10 000/S85 microprobe (United Kingdom) in comparison with persons without somatic pathology. It has been established that in people suffering from chronic kidney disease dental hard tissues morphological features were determined by their pathological changes due to carious process or non-carious lesions. In chronic kidney disease a significant decrease in the level of mineralization in both enamel and dentin was found, which was most pronounced in patients with chronic renal failure and did not depend on whether they received hemodialysis. The use of remineralizing therapy in people with chronic kidney disease within the framework of individual oral hygiene combined with a vitamin-mineral complex intake for 6 weeks significantly contributed to an increase in the Ca/P ratio in tooth enamel and may be seen as a useful tool for prevention of dental hard tissues pathology in the patient's group.

Efficacy of desensitizing products containing 8% arginine and calcium carbonate for hypersensitivity relief in MIH-affected molars: an 8-week clinical study.

OBJECTIVES: The objective of this study was to compare the efficacy in reducing hypersensitivity in molar incisor hypomineralization (MIH)-affected molars immediately and over 8 weeks combining a single in-office application and a homed-based program with desensitizing products containing 8% arginine and calcium carbonate. MATERIALS AND METHODS: Nineteen children with at least one MIH-affected molar with hypersensitivity were included. Hypersensitivity was assessed with an evaporative (air) stimulus and a tactile stimulus. Each child received a single in-office treatment with a desensitizing paste containing 8% arginine and calcium carbonate (elmex Sensitive Professional desensitizing paste), followed by 8 weeks of brushing twice daily with a desensitizing toothpaste containing 8% arginine, calcium carbonate with 1450 ppm fluoride (elmex Sensitive Professional toothpaste), using the elmex Sensitive Professional toothbrush. Additionally, the corresponding mouthwash (elmex Sensitive Professional mouthwash) was used. Clinical assessments were made at baseline, immediately after the in-office treatment and after 1, 2, 4 and 8 weeks of brushing twice daily. RESULTS: Fifty-six molars with an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) were included. Application of the desensitizing paste decreased hypersensitivity significantly immediately and throughout the 8 weeks recalls (p < 0.001). CONCLUSIONS: In conclusion, 8% arginine and calcium carbonate were able to reduce hypersensitivity successfully during this 8-week trial. CLINICAL RELEVANCE: Hypersensitivity is a major complaint in patients with MIH. This is the first study evaluating the desensitizing effect of a desensitizing paste containing 8% arginine and calcium carbonate in patients with MIH.

Masking white spots of enamel in caries lesions with a non-invasive infiltration technique in vitro.

We investigated the treatment effect of non-invasive infiltration on early caries caused by different degrees of enamel demineralization. Forty specimens of early enamel caries were prepared and divided into low and high demineralization groups. After treatment with non-invasive infiltration, the specimens were placed under cariogenic conditions. Color measurements were determined using a spectrophotometer 4 times to obtain chromatism values (ΔE1-ΔE4), including before and after production of artificial caries, and after infiltration treatment and re-demineralization. The effects of color change on early caries using non-invasive infiltration were compared between the 2 demineralization groups. Color differences before the production of artificial caries and after infiltration treatment and re-demineralization could not be distinguished by direct observation. Color differences after the production of artificial caries and after infiltration treatment and re-demineralization could be distinguished by direct observation. There were no significant differences in the 4 chromatism values (ΔE1-ΔE4) between the 2 groups. Non-invasive infiltration showed an excellent ability to mask white spot lesions and maintained high color stability. Treatment of high and low demineralization of enamel had the same masking effect.

Infantile loss of teeth: odontohypophosphatasia or childhood hypophosphatasia.

Hypophosphatasia is a hereditary disorder characterized by a deficiency of serum and bone alkaline phosphatase (ALP) activity and defective skeletal mineralization. It is caused by a loss of function mutations in the tissue nonspecific ALP gene (TNSALP) encoding the tissue nonspecific alkaline phosphatase. A 4-year-and-8-month-old girl presented with premature exfoliation of the anterior incisors and canines. Very low ALP level (27 IU/ml) suggested the diagnosis of hypophosphatasia, which was supported by an elevated urine phosphoethanolamine/Cr of 84 µmol/mmol (reference range, <25 µmol/mmol) and serum pyridoxal-5'-phosphate of 393 µg/L (reference range, 3.6-18 µg/L). The phenotype of the patient was subsequently classified as mild childhood hypophosphatasia. TNSALP gene sequencing revealed the homozygous c.382 G > A (p.V128M) mutation. This mutation was previously observed in a series of patients with severe hypophosphatasia, pointing out the possible role of other genetic or environmental factors in the modulation of the hypophosphatasia phenotype.

Staining of dentin from amalgam corrosion is induced by demineralization.

PURPOSE: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. METHODS: Sound human molars (n = 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n = 24). Non-demineralized teeth served as controls (n = the 10). A dispersive high-Cu amalgam or conventional low-Cu amalgam was condensed onto dentin surfaces of all groups. After 10 weeks storage in saline, amalgam was removed and teeth were cut into three slices. Surfaces were inspected under optical microscopy and photographed. RESULTS: Penetration of black pigments was observed in dentin underneath both high-Cu and low-Cu amalgams in demineralized specimens. Black deposits were unevenly distributed and observed predominantly in dentin near to pulp horns. Discoloration was not limited to outer demineralized dentin but extended beyond this zone. Evenly distributed bluish-green discoloration was observed underneath all high-Cu amalgam specimens independent of demineralization.

An in vivo investigation of salivary properties, enamel hypomineralisation, and carious lesion severity in a group of Iraqi schoolchildren.

BACKGROUND: Hypomineralised enamel is a prevalent, congenital defect vulnerable to deteriorate post-eruptively particularly in the presence of an unfavourable oral environment. AIMS: To assess the influence of salivary characteristics on the clinical presentation of hypomineralisation lesions diagnosed in first permanent and second primary molars and to evaluate caries severity in relation to the defect's clinical presentation. DESIGN: Recruitment consisted of 445 seven- to nine-year-old participants, of whom 152 were diagnosed as having molar hypomineralisation (MH); the remaining unaffected subjects (N = 293) were considered their controls for saliva analysis. Dental caries status was assessed in 300 subjects of saliva sub-sample, equally divided as MH-affected and non-affected children. The International Caries Detection and Assessment System was used for caries detection. Salivary flow rates, viscosity, pH, and buffering capacity were determined. RESULTS: Molar hypomineralisation-affected children have significantly higher mean caries scores compared to the non-affected group. Dentinal carious lesions were ten times more frequent in teeth with post-eruptive breakdown (PEB) than with teeth with opacities only. Low salivary flow rates (LSFR), moderately viscous saliva, and low pH were significantly more common in the affected group. LSFR and moderate and highly acidic saliva were more likely associated with PEB. CONCLUSION: Demarcated hypomineralised enamel is a dynamic defect highly influenced by individual characteristics of the oral environment.

Dental developmental disturbances in 50 individuals with the 22q11.2 deletion syndrome; relation to medical conditions?

OBJECTIVE: The aims of the study were to examine tooth and enamel disturbances in individuals with 22q11.2 deletion syndrome and to analyze associations with medical conditions, birth characteristics and blood values of calcium and PTH. MATERIALS AND METHODS: Fifty individuals participated in the study (27 females, median age 10 years, range 1.5-44). Congenital absence of teeth was studied on orthopantomograms; 1148 teeth were examined, both clinically and radiologically, and enamel hypomineralizations and hypoplasias were recorded. Medical history and findings were recorded as part of a larger study on the manifestations of 22q11.2-deletion syndrome in Norway. RESULTS: Tooth agenesis was observed in 15% of study participants. Sixty-six percent of the participants and 26.0% of teeth presented with enamel disturbances. Of these, 12 individuals (24.0%) and 215 teeth (18.7%) had hypomineralizations and four individuals (8.0%) and 86 teeth (7.5%) had hypoplasias. Seventeen participants (34.0%) presented with both types of disturbance, but rarely in the same tooth. Only two teeth (0.17%) had both types of disturbance. Hypomineralizations were twice as frequent in permanent as in primary teeth. No correlations were found to medical conditions, except that participants with congenital cardiac anomalies presented with fewer total enamel disturbances and hypomineralizations in permanent teeth than those without. CONCLUSIONS: Enamel disturbances were frequently seen. There were more hypomineralizations than hypoplasias. Hypoparathyroidism and/or hypocalcemia are not clear etiological factors for enamel disturbances and there were no major correlations between medical conditions and enamel disturbances.

Increased susceptibility for white spot lesions by surplus orthodontic etching exceeding bracket base area.

INTRODUCTION: There is a paucity of information with regard to the susceptibility of iatrogenic white spot lesion formation after inattentive, surplus orthodontic etching with 30% phosphoric acid and the subsequent provision or absence of adequate oral hygiene. METHODS: Ninety sound enamel specimens were randomly allocated to 6 trial groups (n = 15 each) for etching with 30% phosphoric acid for either 15 seconds and standardized daily enamel brushing or no brushing, etching for 30 seconds with daily brushing or no brushing, or nonetched controls with brushing or no brushing. Nutritive acidic assaults were simulated by demineralization cycles 3 times per day for 1 hour with interim storage in artificial saliva. Lesion depths in terms of percentage of fluorescence loss (delta F, delta Q) and lesion extension compared with the baseline were assessed by using quantitative light-induced fluorescence after 2, 7, 14, 21, and 42 days. Etching duration, trial time elapse, and oral hygiene, as well as the significance of factor interactions, were analyzed with 3-way analysis of variance (α = 5%). RESULTS: The impact of the factors of enamel brushing, trial time elapse, and etching each had a comparably significant effect on lesion progression. The effect of surplus etching on white spot lesion formation was significantly enhanced by the simultaneous absence of enamel brushing and also the progression of trial time. The combination of 30 seconds of surplus etching with inadequate oral hygiene was especially detrimental. CONCLUSIONS: Excessive surplus orthodontic etching of the complete labial enamel surface, instead of the bracket bases only, must be avoided to prevent iatrogenic white spot lesions. Etching times not exceeding 15 seconds are favorable.

Dentin protection by a primer-less adhesive technique.

PURPOSE: To identify the remaining demineralized dentin (the permeable layer that allows leakage) when using primer-less wet bonding with a total etching period of 10 to 60 seconds compared with contemporary resin adhesives. METHODS: Extracted human molars were selected and Class V cavities were prepared on the axial surfaces at the CEJ, providing margins in enamel and dentin for leakage testing using a basic dye (n = 10). Seven groups of conditioned teeth [1-1 etched for 10, 30, and 60 seconds (primer-less wet), All-Bond 2 and Single-Bond 2 (wet), AQ-Bond (self-etched), Super-Bond C&B (dry)] were used as bonding systems for resin composite restoration. All specimens were stored in water at 37 degrees C for 24 hours before soaking in a 0.5% basic fuchsin solution for 24 hours. The distance of dye penetration was measured using stereomicroscopy. RESULTS: No leakage at the enamel- and dentin-resin interfaces was found for all etching periods of 1-1 primer-less, Super-Bond C&B, and AQ-Bond specimens. However, leakage was observed at dentin margins in two wet with primer systems, All-Bond 2 (1.31 +/- 1.39 mm) and Single-Bond 2 (0.37 +/- 0.28 mm), which required phosphoric etching to remove a weak smear layer on prepared dentin.

Influence of customized therapy for molar incisor hypomineralization on children's oral hygiene and quality of life.

OBJECTIVE: The aim of this clinical follow-up study was to demonstrate the effects of different therapeutic strategies for hypomineralized teeth on patients' oral health. The treatment results were characterized by changes in the extent of hypersensitivity and plaque accumulation, as well as reductions in nutritional restrictions. MATERIAL AND METHODS: The impacts of therapy, including the use of fluoride varnish, fissure sealants, fillings, and stainless steel crowns, were evaluated in 78 children (mean age 8.5 years). We followed recommendations according to the Molar Incisor Hypomineralisation Treatment Need Index for customized treatment. The Quigley Hein Index, the Schiff Cold Air Sensitivity Scale, Wong-Baker Faces Scale, and dietary-limiting parameters were assessed before and after therapy for comparison. RESULTS: Plaque accumulation and hypersensitivity decreased after completion of therapy. The improvements were greater for individual teeth (Quigley Hein Index for teeth treated with stainless steel crowns from 4.19 to 2.54) than for those of the whole dentition (high-severity category from 2.67 to 2.20). Problems with food intake were minimized via therapy, with the greatest influence observed for patients who were also in the high-severity category. CONCLUSIONS: Therapy for affected teeth in children has positive effects on oral health and quality of life.

Aspects on dental hard tissues in primary teeth from patients with Ehlers-Danlos syndrome.

BACKGROUND: Ehlers-Danlos syndrome (EDS) is a rare hereditary condition affecting connective tissues and dental hard tissues. HYPOTHESES: Primary enamel and dentine from EDS patients were expected to differ from those of healthy subjects regarding morphology and chemical composition. DESIGN: Forty-seven exfoliated primary teeth from 25 patients with EDS were investigated. Morphology was studied using a polarized light microscope, scanning electron microscope, and X-ray microanalysis. Comparisons were made with 36 primary teeth from 36 healthy patients. RESULTS: Morphological analysis of enamel in EDS teeth showed a high frequency of postnatally hypomineralized enamel and postnatally located incremental lines, whereas dentine was normal in all patients. Chemical analysis could not reveal any differences between EDS and control patients except for lower content of C and a higher Ca/P ratio in the enamel in the EDS teeth, indicating porous enamel. Regarding dentine, EDS teeth had a lower content of C, and a higher content of Ca, P, and O. Ratios for Ca/C and Ca/O were also higher compared with controls. CONCLUSIONS: There are several aberrations of booth enamel and dentine in primary teeth from patients with EDS. These could explain the occurrence of both more dental caries and tooth fractures in patients with EDS.

Bacterial invasion of dentinal tubules beneath apparently intact but hypomineralized enamel in molar teeth with molar incisor hypomineralization.

BACKGROUND: The most common problems for a patient with molar incisor hypomineralization (MIH) are the collapse of enamel and cavitations, loss of fillings, and secondary caries, but most of all, severe hypersensitivity. OBJECTIVE: The aim of this paper was therefore to histologically study possible bacterial invasion of dentinal tubules beneath apparently intact, but hypomineralized enamel in permanent molars with MIH. MATERIAL AND METHODS: Five extracted permanent first molars diagnosed with MIH were fixated, demineralized, and sagittally serially sectioned in a bucco-lingual direction in a microtome with a thickness of 4-5 microm. Sections were stained with a modified Brown and Benn staining for bacteria, unstained sections were analysed in field emission SEM. RESULTS: Stained sections from the cuspal areas, below the hypomineralized enamel, the staining indicated the presence of bacteria in the dentinal tubules. The HTX staining showed that the pulp in sections without any findings was normal and free from bacteria or infiltrates from inflammatory cells. In sections where bacteria were found in the cuspal areas or deeper in the dentin, a zone of reparative dentin was found, and in sections from one tooth, the coronal pulp showed an inflammatory reaction with inflammatory cells. In sections adjacent to those without any bacterial staining, the SEM analyses revealed empty dentinal tubules without any odontoblast processes or signs of bacteria. When odontoblast processes were found, the dentinal tubules were filled with bacteria located on the surface of the odontoblast processes. In some areas, a large number of tubules were found with bacteria. No bacteria were found close to the pulp. The odontoblast processes appeared larger in areas where bacteria were found. CONCLUSIONS: The presence of bacteria in the dentinal tubules and inflammatory reactions in the pulp indicate that oral bacteria may penetrate through the hypomineralized enamel into the dentin, thus possibly contribute to hypersensitivity of teeth with MIH.

Early enamel lesion part II. Histo-morphology and prevention.

There has been a paradigm shift from Black's 'extension for prevention' to a minimal intervention approach in the recent time. The most important aspect in diagnosis of earliest stages of enamel demineralization involves accurate and reliable detection of such lesions. The newer diagnostic aids would enable the dentist to detect and diagnose early enamel lesions and direct appropriate preventive measures to promote remineralization and conservation of the tooth substance. A high level of caries experience necessitates preventive strategies which are more cost effective than surgical intervention and restorative procedures.

Are hypomineralised lesions on second primary molars (HSPM) a predictive sign of molar incisor hypomineralisation (MIH)? A systematic review and a meta-analysis.

OBJECTIVES: Molar Incisor Hypomineralisation (MIH) and Hypomineralised Second Primary Molars (HSPM) involve qualitative structural developmental anomalies of tooth enamel affecting the first permanent molars (and often incisors) and the second primary molars, respectively. A putative relationship between HSPM and MIH has been reported in the scientific literature. The aim was to determine whether children with HSPM are more likely to develop MIH. SOURCE: A systematic search using PubMed/Medline, Embase and Cochrane Library electronic databases for publications from 2001 to August 2017 investigating the link between MIH and HSPM was undertaken. STUDY SELECTION: Four reviewers selected the studies independently, extracted the data according to PRISMA statement, and assessed the bias risk with the Newcastle-Ottawa Scale (NOS) criteria. RESULTS: From 645 potentially eligible studies, 14 were selected for full text analysis and 5 were included in the meta-analysis. Cross-sectional and cohort studies were reported and 4662 participants were included. The meta-analyses were performed with a random model calculated an OR total of 4.66 (95% CI 2.11-10.26; P < 0.001). The weighted mean of the co-occurrence of HSPM and MIH prevalence was 19.94%. DISCUSSION: The high heterogeneity (I2 = 88%) can be explained by the great variation present in number of participants and variable caries risk. Despite the limitations of the study, the presence of HSPM is predictive for MIH, with greater MIH prevalence in the presence of mild HSPM. CLINICAL SIGNIFICANCE: Early detection and preventive intervention could reduce MIH complications.

Pulpal status of hypomineralized permanent molars.

PURPOSE: Young patients with hypomineralized teeth frequently complain of symptoms suggestive of dentin hypersensitivity. It has been proposed that these symptoms may be exacerbated by an underlying pulpal inflammation. The purpose of the study was to determine the pulpal status of hypomineralized teeth. METHODS: The experimental material comprised 25 sound and 19 hypomineralized permanent first molars obtained from children requiring dental extractions under general anesthesia. Pulp sections were processed for indirect immunofluorescence using combinations of: (1) protein gene product 9.5; (2) leukocyte common antigen; and (3) Ulex europaeus I lectin. Image analysis was then used to determine the percentage area of staining of each label. RESULTS: Innervation density was significantly greater in the pulp horn and subodontoblastic region of hypomineralized teeth than in sound teeth. Immune cells were most abundant within pulps of hypomineralized teeth exhibiting enamel loss. Vascularity was found to be similar for both hypomineralized and sound teeth, but was significantly greater in hypersensitive hypomineralized samples. CONCLUSION: This study provides biological evidence that inflammatory changes may be present within the pulpal tissue of these teeth.

Defining, classifying, and placing incipient caries lesions in perspective.

A caries lesion begins with the introduction of a disease state, likely due to bacterial strains, in the oral cavity. If accompanied or followed by alterations to salivary flow, frequent periods of reduced salivary pH, or frequent intake of refined carbohydrates, the demineralization of tooth structure is likely to begin. The subsequent lesions first will be visible as white spot lesions, which if ignored, eventually will cavitate. Modern dentistry is capable of testing for the presence of caries lesions before cavitation, and it is suggested that routine testing should be mandatory for all patients who are at risk. If the disease is to be identified and treated before cavitation, it is desirable to adopt a new classification for the recognition and recording of caries lesions.

An overview of tooth discoloration: extrinsic, intrinsic and internalized stains.

The causes of tooth discoloration are varied and complex but are usually classified as being either intrinsic, extrinsic or internalized in nature. Dietary chromogens and other external elements deposit on the tooth surface or within the pellicle layer either directly or indirectly to form extrinsic discoloration. Stains within the dentine or intrinsic discoloration often results from systemic or pulpal origin, while internalized stains are the result of extrinsic stains entering the dentine via tooth defects such as cracks on the tooth surface.

Clinical assessment of non carious cervical lesion using swept-source optical coherence tomography.

Non-carious cervical lesions (NCCLs) involve various forms of tooth loss with different etiologies. This study aimed to utilize swept-source optical coherence tomography (SS-OCT) at 1300 nm wavelength range in vitro and in vivo to evaluate and clarify the mechanism of NCCLs. In the in vitro phase, a dentin attenuation coefficient (µt ) derived from the SS-OCT signal at NCCL was compared with mineral loss obtained from transverse microradiography (TMR) to determine a µt threshold to discriminate demineralization of cervical dentin in vivo. In the clinical study, 242 buccal surfaces were investigated in 35 subjects. Presence and dimensions of NCCLs, cervical cracking and the degree of demineralization at the exposed cervical dentin were determined using SS-OCT. Dentin demineralization was observed in 69% of NCCLs. SS-OCT results confirm that dentin mineral loss and occlusal attrition were associated with larger NCCLs, and can be considered as an etiological factor in formation and progress of these lesions. (A) We determined the attenuation coeffcient (µt ) threshold of SS-OCT signal for the detection of demineralization (1.21) from in vitro study. DEM: demineralized dentin, sound: sound dentin. (B) Using the µt threshold, we observed NCCLs in vivo to detect the demineralization in cervical dentin. SS-OCT scanning was performed along the red line. (C) SS-OCT image obtained along the red line in B. In SS-OCT, brightness of dentin beneath the NCCL was increased (arrow) compared with intact zone. The cervical dentin was slightly demineralized (µt : 1.25). e: enamel, d: dentin, g: gingiva.