Evaluation of a new 3D-printed tooth model allowing preoperative ICDAS assessment and caries removal.

INTRODUCTION: Teaching caries lesion management with operative care requires tooth models with highly realistic anatomical detail and caries lesions that can be assessed using ICDAS. This study aimed to develop and evaluate a new 3D-printed teeth model for ICDAS assessment and caries removal for pre-clinical hands-on education. METHODS: Printable tooth with different layers for enamel, dentin and carious lesions was designed and tested by 31 dental students. They were asked to visually and radiologically assess the ICDAS severity of the simulated carious lesions, establish the therapeutic strategy according to CariesCare 4D, and perform a qualitative assessment of the models based on five-point Likert scale items. RESULTS: Concerning carious lesions, the texture was realistic, and the shade was adequate for 94% and 97% of the participants. Ninety per cent of the participants found the model adequate to perform an ICDAS visual assessment. Seventy-four per cent of the students found the hardness adequate. Concerning the difference in shade and the noticeable hardness difference between enamel and dentin, participants have mixed agreement with a proportion of 61% and 55%, respectively. All the participants agreed these 3D-printed models provide a good caries simulation, are suitable for hands-on operative dentistry courses, and that learning outcomes better than the standard model. CONCLUSION: The present work shows that rapid prototyping paves the way for customized educational models capable of supporting operative but also preoperative skills. 3D printing opens up new opportunities by reducing the gap between pre-clinical training and clinical reality in caries management, which can positively impact the quality of patient care.

Genome-wide association study identifies novel caries-associated loci showing sex-specificity-A study on the Northern Finland Birth Cohort 1966.

A genome-wide association study was performed in sex-stratified groups representing three different caries phenotypes among adults. The study sample consisted of 46-year-old participants of the Northern Finland Birth Cohort 1966 study (n = 1481). The phenotypes for analyses were the dentin caries phenotype (persons having at least one tooth with dentin caries lesion), and the enamel caries phenotype (those having teeth with more than 10 enamel caries lesions), while the control group had <10 enamel caries lesions and no teeth with dentin caries, respectively. A third phenotype dubbed the caries severity phenotype had a below-average number of teeth with initial lesions and at least one extensive dentin caries lesion; their controls had an above-average number of teeth with initial caries lesions and no teeth with extensive dentin caries lesions. All analyses were performed for the whole group and for sex-stratified subgroups. In females, loci in chromosomes 2, 5, and 15 showed a statistically significant association with caries severity. In males, there was a novel association between chromosome 5 and dentin caries. The results of this study may suggest a genetic background of caries among adults. In the future, the detection of genetic predisposing variants may allow the identification of patients at risk for caries, even in the absence of behavioral and environmental risk factors.

Dentine Mineral Changes Induced by Polyalkenoate Cements after Different Selective Caries Removal Techniques: An in vitro Study.

This study aimed at evaluating the mineral variation induced by polyalkenoate cements in residual dentine after different caries removal methods. Ten extracted sound molars were selected, and five cavities were prepared on the occlusal surface of each specimen. Carious lesions were generated using a microbial protocol, while the caries removal was performed using bur, hand excavator, or two papain-based chemo-mechanical agents. One cavity was left unexcavated in each tooth. Cavities were restored using a zinc polycarboxylate cement (ZPC; n = 25), or a glass ionomer cement (GIC) was used (n = 25). Subsequently, the specimens were stored under simulated pulpal pressure for 45 days. Micro-CT scanning was performed after caries formation, removal, and restoration. Cavity volumes (mm3) and mineral density (MD) changes were calculated. Remineralisation ability was investigated by scanning electron microscopy (SEM) and Fourier-transformed infrared spectroscopy (FTIR). Statistical analysis was performed (5% significance level). Baseline caries, cavity volume, and MD increase after caries removal were similar to all excavation groups (p > 0.05). MD was higher in ZPC compared to GIC (p < 0.05). SEM revealed that the chemo-mechanical techniques produced a smoother dentine surface compared to mechanical methods. FTIR showed silicon-based minerals in GIC-treated dentine, while ZPC-treated presented mineral deposits characterised by amorphous calcium phosphate. In both cases, the presence of carbonates was detected on dentine surfaces. All caries removal techniques performed similarly in terms of carious dentine excavation. ZPC can be used as dentine replacement material after caries removal as it may induce higher MD increase in residual dentine via deposition of calcium phosphates, compared to GIC.

Underlying Dentin Shadows (ICDAS 4) in Occlusal Surface of Permanent Teeth Have Low Progression Rate after 1-2 Years.

The aim of this prospective cohort study was to assess the radiographic progression of underlying dentin shadows (UDS) on the occlusal surfaces of permanent posterior teeth of adolescents and young adults over 1-2 years and to identify possible risk factors. A total of 149 UDS lesions (from 101 individuals) were included at baseline. Each participant had to present at least one UDS to be considered eligible for the study. Data collection included the application of a questionnaire, clinical examination, and bilateral bitewing radiographs, performed at baseline and after 1-2 years. The association between possible predictors and UDS progression (defined radiographically as an increase in the radiographic score from baseline to follow-up) was assessed using Weibull regression models. Hazard ratios (HRs) and their 95% confidence intervals (CIs) were estimated. A total of 81 individuals (mean age: 24.0, standard deviation: 8.03) were reexamined after 1-2 years (742 occlusal surfaces, of which 118 were UDS). The overall progression rate was 8.6% after 1-2 years, being 12.6% for UDS without baseline radiolucency and 20% for UDS with baseline radiolucency. The risk analysis showed that UDS without radiolucency at baseline had a similar likelihood of progression (adjusted HR = 1.71, 95% CI = 0.68-4.32, p = 0.26) while UDS with radiolucency at baseline were more likely to progress (adjusted HR = 2.96, 95% CI = 1.06-8.26, p = 0.04) than the reference category (sound occlusal surfaces without radiolucency). These estimates were adjusted for caries prevalence, tooth type, and arch. This study showed low progression rates of UDS after 1-2 years. The presence of radiolucency at baseline was found to predict UDS progression.

Three-Dimensional Assessment of Radiographic Changes after Indirect Pulp Capping Using Silver Diamine Fluoride with or without Potassium Iodide in Young Permanent Teeth (12-Month RCT).

The aim of this study was to conduct a three-dimensional (3D) evaluation of radiographic changes after indirect pulp capping (IPC) with silver diamine fluoride (SDF) with or without potassium iodide (KI) and resin-modified glass ionomer cement (RMGIC) in deep carious young permanent molars using cone-beam computed tomography (CBCT). 108 first permanent molars with deep occlusal cavitated caries lesions, in forty-nine 6- to 9-year-old children, were randomly allocated to one of 3 groups (n = 36) and treated with SDF+KI, SDF, and RMGIC as IPC materials. CBCT scans were taken at 0 and 12 months to assess tertiary dentin formation (volume and grey level intensity), increase in root length, and pathological changes such as secondary caries, periapical radiolucency, internal resorption, and obliteration of the pulp. The 3D image analysis procedures were performed using ITK-SNAP and 3D Slicer CMF. Comparisons were made using analysis of variance with a fixed effect for treatment and random effects for patient and patient-by-treatment to account for within-patient correlations. A two-sided 5% significance level was used. There were no significant differences among the three groups regarding tertiary dentin volume (p = 0.712) and grey level intensity (p = 0.660), increase in root length (p = 0.365), prevention of secondary caries (p = 0.63), and periapical radiolucency (p = 0.80) in the analysed 69 CBCT scans. The study did not find differences among the groups regarding quality and quantity of tertiary dentin formed, increase in root length, absence of secondary caries, and other signs of failure as shown by CBCT. Clinical Significance: The results show no significant differences in radiographic outcomes (quality and quantity of tertiary dentin formed, increase in root length, absence of secondary caries, and other signs of failure) when using SDF+KI, SDF, and RMGIC in IPC. The results of this study can help guide treatment decision-making regarding use of SDF and SDF+KI as IPC materials in deep cavitated lesions.

Axin2-CreERT2 mediated knockout of bone morphogenetic protein receptor type 1A caused abnormal secondary dentine and altered cell fate of Axin2-expressing odontogenic cells.

AIM: Inducing odontogenic differentiation and tubular dentine formation is extremely important in dentine repair and tooth regeneration. Bone morphogenic proteins (BMPs) signalling plays a critical role in dentine development and tertiary dentine formation, whilst how BMPR1A-mediated signalling affects odontoblastic differentiation of Axin2-expressing (Axin2+ ) odontogenic cells and tubular dentine formation remains largely unknown. This study aims to reveal the cellular and molecular mechanisms involved in the formation of secondary dentine. METHODOLOGY: Axin2lacZ/+ mice harvested at post-natal 21 (P21) were used to map Axin2+ mesenchymal cells. Axin2CreERT2/+ ; R26RtdTomato/+ mice and Axin2CreERT2/+ ; R26RDTA/+ ; R26RtdTomato/+ mice were generated to observe the tempo-spatial distribution pattern of Axin2-lineage cells and the effect of ablation of Axin2+ cells on dentinogenesis, respectively. A loss-of-function model was established with Axin2CreERT2/+ ; Bmpr1afl/fl ; R26RtdTomato/+ (cKO) mice to study the role of BMP signalling in regulating Axin2+ cells. Micro-computed tomography, histologic and immunostainings, and other approaches were used to examine biological functions, including dentine formation, mineralization and cell differentiation in cKO mice. RESULTS: The results showed rich expression of Axin2 in odontoblasts at P21. Lineage tracing assay confirmed the wide distribution of Axin2 lineage cells in odontoblast layer and dental pulp during secondary dentine formation (P23 to P56), suggesting that Axin2+ cells are important cell source of primary odontoblasts. Ablation of Axin2+ cells (DTA mice) significantly impaired secondary dentine formation characterized with notably reduced dentine thickness (Mean of control: 54.11 µm, Mean of DTA: 27.79 µm, p = .0101). Furthermore, malformed osteo-dentine replaced the tubular secondary dentine in the absence of Bmpr1a with irregular cell morphology, abnormal cellular process formation and lack of cell-cell tight conjunction. Remarkably increased expression of osteogenic markers like Runx2 and DMP1 was detected, whilst DSP expression was observed in a dispersed manner, indicating an impaired odontogenic cell fate and failure in producing tubular dentine in cKO mice. CONCLUSIONS: Axin2+ cells are a critical population of primary odontoblasts which contribute to tubular secondary dentine formation, and BMP signalling pathway plays a vital role in maintaining the odontogenic fate of Axin2+ cells.

Identification of DSPP novel variants and phenotype analysis in dentinogenesis dysplasia Shields type II patients.

OBJECTIVES: To investigate the genetic causes and teeth characteristics of dentin dysplasia Shields type II(DD-II) in three Chinese families. MATERIALS AND METHODS: Data from three Chinese families affected with DD-II were collected. Whole-exome sequencing (WES) and whole-genome sequencing (WGS) were conducted to screen for variations, and Sanger sequencing was used to verify mutation sites. The physical and chemical characteristics of the affected teeth including tooth structure, hardness, mineral content, and ultrastructure were investigated. RESULTS: A novel frameshift deletion mutation c.1871_1874del(p.Ser624fs) in DSPP was found in families A and B, while no pathogenic mutation was found in family C. The affected teeth's pulp cavities were obliterated, and the root canals were smaller than normal teeth and irregularly distributed comprising a network. The patients' teeth also had reduced dentin hardness and highly irregular dentinal tubules. The Mg content of the teeth was significantly lower than that of the controls, but the Na content was obviously higher than that of the controls. CONCLUSIONS: A novel frameshift deletion mutation, c.1871_1874del (p.Ser624fs), in the DPP region of the DSPP gene causes DD-II. The DD-II teeth demonstrated compromised mechanical properties and changed ultrastructure, suggesting an impaired function of DPP. Our findings expand the mutational spectrum of the DSPP gene and strengthen the understanding of clinical phenotypes related to the frameshift deletion in the DPP region of the DSPP gene. CLINICAL RELEVANCE: A DSPP mutation can alter the characteristics of the affected teeth, including tooth structure, hardness, mineral content, and ultrastructure.

Selective removal to soft dentine or selective removal to firm dentine for deep caries lesions in permanent posterior teeth: a randomized controlled clinical trial up to 2 years.

OBJECTIVES: The aim of this randomized clinical trial was to compare selective removal to soft dentin (SRSD) and selective removal to firm dentin (SRFD) in permanent teeth. The primary outcome of the study was to compare the success rates of the two caries removal techniques. The secondary outcome of the study was to investigate whether or not calcium silicate-based material (CS) had an effect on the success rate of the treatment. MATERIALS AND METHODS: Between November 2018 and March 2020, patients with deep caries lesions were invited to participate in the study. Posterior teeth (N = 165) with primary caries lesion radiographically extending ¾ of dentin and positive response to cold test were randomly selected. A total of 134 participants meeting the inclusion criteria were randomized to SRSD and SRFD (control) groups. After the caries removal procedure, teeth with exposed pulps were assigned to the pulp exposure (PE) group, and the SRSD group was further divided into test 1 (with CS) and test 2 groups (without CS). Success was defined as a positive response to the cold test, a negative response to percussion, the absence of pain, an abscess, a fistula, and periapical alterations. Fisher-Freeman-Halton exact tests, Kaplan-Meier survival analysis, and the log-rank tests were performed for comparisons between groups. RESULTS: No statistically significant difference was found between the success rates of test 1 (100%) and test 2 (93.5%) groups, whereas the proportion of success in control (82.4%) and PE (84%) groups were significantly lower when compared with test groups (p = 0.024; p < 0.05) at the end of 2-year follow-up. CONCLUSIONS: SRSD had a higher success rate when compared to SRFD to treat deep carious lesions after 2 years of follow-up. The use of CS material after SRSD as a liner had no effect on the treatment outcome. CLINICAL RELEVANCE: SRSD with good coronal sealing might be recommended without CS application for the treatment of deep caries lesions in permanent teeth. TRIAL REGISTRATION: Clinical trial registration number NCT04052685 (08/09/2019).

Iron level participates in the pathological damages of dental caries in infant rats by affecting enamel mineralization.

Iron deficiency anemia (IDA) is a common nutritional disease associated with early childhood caries. This study aimed to explore the role of iron levels in pathological changes of dental caries in childhood. Rats were divided into four groups based on their iron content: IDA, positive control (PC), high iron (HI), and negative control (NC). Except for the rats in the NC group, rats in the other groups were inoculated with Streptococcus mutans and fed cariogenic high-sugar fodder to induce caries. Three months later, the caries status of the molars was evaluated at both the smooth and sulcal surfaces according to Keyes scores. Scanning electron microscopy (SEM) was performed to reveal microstructural changes in caries. Energy-dispersive spectroscopy (EDS) was used to determine the elemental composition of the enamel and dentin. In addition, the histopathology of the salivary gland was detected using hematoxylin and eosin (HE) staining.The results showed that rats in the PC group exhibited obvious carious lesions. The carious score was significantly higher in the IDA group than in the PC group but was lower in the HI group. SEM revealed complete destruction of the enamel and damage to the middle dentin in the IDA group. In contrast, the molars in the HI group exhibited some degree of enamel demineralization, but the underlying dentin was almost intact. In addition, the elemental compositions of the enamel and dentin were similar among the four groups, and iron was detected only in the HI group. No differences were observed in the morphological structures of the salivary glands of rats from the different groups. In conclusion, ID enhanced the pathological damage of caries, whereas HI weakened it. Iron may participate in the pathological damage caused by childhood caries by affecting enamel mineralization.

Effect of brushing force on the abrasive dentin wear using slurries with different abrasivity values.

OBJECTIVE: The aim of this study was to investigate the resulting abrasive dentin wear using abrasive slurries with different RDA values and applying increasing brushing forces. METHODS: Forty-five bovine incisors were randomly allocated in three groups (A, B, C, n = 15). One hundred and eighty dentin samples were prepared from these incisors and allocated to twelve groups (A1-A4, B1-B4, C1-C4; n = 15). The groups were subjected to a brushing cycle (120 strokes/min, 25 min) as follows: groups A1 to A4 with an abrasive slurry (RDA = 71) applying increasing brushing forces (1, 2, 3 and 4 N). Groups B1 to B4 were brushed using an abrasive slurry (RDA = 85) and C1 to C4 (RDA = 133) applying the same above-mentioned brushing forces. Abrasive dentin wear was recorded using a stylus profilometer and compared amongst the groups using robust models. Pairwise comparisons in each model were tested and corrected after Tukey's method (α = 0.05). RESULTS: Applying 1-N brushing force resulted in the same amount of abrasive dentin wear in all groups regardless of the abrasivity of the used slurry. Increasing the brushing force to 2 N resulted in statistically significantly higher abrasive wear in all groups. This increase in abrasive wear was much higher when the slurry with high abrasivity was used (RDA = 133) compared with the lower abrasive slurry (RDA = 71). CONCLUSION: The abrasivity of the used slurry does not add to the resulting abrasive wear when the brushing force is kept at 1 N. It seems better to advise and help the patients (showing signs of non-carious cervical lesions) calibrating their brushing force to 1 N, than only to advise them to use toothpastes with lower abrasivities.

Monitoring silver diamine fluoride application with optical coherence tomography and thermal imaging: An in vitro proof of concept study.

OBJECTIVES: The purpose of this study was to show that optical coherence tomography (OCT) and thermal imaging can be used to monitor changes in the structure and activity of caries lesions over time after treatment with silver diamine fluoride (SDF). METHODS: Artificial caries lesions were formed on enamel and dentin bovine blocks. Each block was partitioned into five windows with the central three windows exposed to a demineralization solution to create lesions: one sound window served as a sound control (SC), one sound window was exposed to SDF to serve as a test control (SCT), one lesion window served as a lesion control (LC), one lesion window received one application of SDF (L1), while the other lesion window received two applications of SDF (L2). Each window was scanned using OCT before SDF application, and every week subsequently, for 12 weeks after initial SDF treatment. Changes in the mean intensity and the width of the peak of increased reflectivity due to the lesion and SDF along with the intensity at a depth of 180 µm from the surface representing optical penetration through the lesion were monitored. Changes in the heat lost, ΔQ (temperature integrated over time) of each window during drying with air were also monitored using a thermal imaging camera. Transverse microradiography (TMR), and high-resolution microscopy were also used for the analysis of selected samples. RESULTS: The reflectivity and optical penetration of sound and lesion areas of enamel and dentin manifested significant changes in OCT images after SDF application. Thermal imaging showed significant differences in ΔQ indicative of permeability changes in the sound and lesion areas of enamel and dentin after SDF application.

Augmented Vision for Dental Students' Education in Detecting Proximal Carious Lesions on Bitewing Radiographs: A Randomized Controlled Trial.

This two-arm, parallel, randomized controlled trial aimed to assess the effect of augmented vision (AV, using interactive color overlays) on the education of dental students in detecting proximal carious lesions on bitewing radiographs compared to black-and-white textbook-like illustrations. Forty-eight preclinical third-year dental students were randomized using a random number generator into two learning groups: test (AV, allowing interaction with color-highlighted carious lesions, n = 24) and control (showing the native radiograph and a black-and-white illustration displaying the carious lesion, n = 24). First, students had 2 weeks to assess 50 bitewings (lesion prevalence on the tooth level: 54.5%) in the test or control. Due to the nature of the intervention, participants could not be blinded toward the intervention. After that, they were asked to detect lesions on 10 independent bitewings and to assess lesion extent (outer/inner enamel; outer/middle/inner dentin). The reference test was constituted by two experienced dentists. No significant differences in accuracy (test 0.84 [95% CI: 0.79, 0.88]; control 0.83 [0.78, 0.87]), AUC (test 0.82 [0.81, 0.84]; control 0.81 [0.80, 0.83]) and F1 score (test 0.79 [0.75, 0.82]; control 0.77 [0.72, 0.81]) were observed between groups. Students of both groups showed difficulties in differentiating enamel from dentin carious lesions. While AV was reported to be motivating by students, it did not increase their accuracy.

Detection of Cavitated Proximal Carious Lesions in Permanent Teeth: A Visual and Radiographic Assessment.

Detection of proximal carious lesions involves the combination of clinical and radiographic methods, both with inherent difficulties. The present cross-sectional study is aimed at estimating the prevalence of cavitation in proximal carious lesions, based on a direct clinical assessment of previously detected radiographic lesions, in permanent molars and premolars. Proximal dental surfaces were radiographically evaluated using the ADA coding system and cavitation was determined through clinical visual examination of the surfaces after separation with elastomeric bands. One-hundred and twenty-six patients attending the dental clinics at the University of Talca were examined, comprising 508 proximal surfaces with radiographic codes ranging from E1 to D3. Two examiners were trained and calibrated for radiographic and clinical detection of proximal lesions. Most participants were females (61.9%). The age mean of participants was 28.7 (0.8) years old. A total of 22.2% of the examined surfaces were cavitated. Only few lesions coded as E1 (n = 4; 2.1%) and E2 (n = 9; 9.8%) were cavitated. Fifty D1 (35.5%) and 22 D2 (41.5%) lesions were cavitated after separation. Most lesions coded as D3 (n = 28; 84.8%) were cavitated. The multilevel binary regression model (p = 0.003) demonstrated that sex, age, jaw, tooth type, surface, and side were not associated with the likelihood of having proximal cavitation. Challenging conventional wisdom, most D1 and D2 lesions were not cavitated. Combining detection methods seems desirable to increase the accuracy in assessing approximal posterior lesions. The low proportion of cavitated lesions reinforces the idea of cautiously indicating invasive approaches for managing proximal carious lesions.

In vitro Effect of Occlusal Loading on Cervical Wall Lesion Development in a Class II Composite Restoration.

The aim of this study was to determine the effect of simulated occlusal loading on wall lesion development in cervical gaps of class II composite restorations in vitro. Sixty-four extracted human molars received standardized (4.0 × 4.2 × 3.0 mm) box preparations. The teeth were randomly assigned to one of two restoration groups: restoration with a normal or a low E-modulus composite material (CLEARFIL AP-X: E-modulus 16.8 GPa or CLEARFIL MAJESTY ES Flow: E-modulus 6.6 GPa). A metal matrix was placed at the bottom of the box for each restoration, creating a cervical gap of about 100 µm wide. Samples were exposed to simulated caries lesion development in a lactic acid solution (pH 4.8) for 8 weeks in a Rub&Roll device. Half of the samples were subjected to 90 N cyclic loading. After demineralization, the teeth were sectioned. Wall lesion development was measured using microradiography (transversal wavelength-independent microradiography) in two different locations (location 1: 1,000 µm and location 2: 1,600 µm from the gap entrance) and recorded in lesion depth (LD) (µm) and mineral loss (µm × vol%). Linear regression modeling was used to estimate the effect of loading and material on wall lesion development. Mean wall LD in location 1 across all groups was 150.83 µm with a standard deviation (SD) of 61.83 µm. In location 2, mean overall wall LD was 102.98 µm with an SD of 64.92 µm. Linear regression showed no significant effect of either loading or material on wall lesion development. Occlusal loading had no significant effect on secondary caries lesion development in composite class II restoration in this in vitro study.

Deep carious lesions and their management among Finnish adolescents: a retrospective radiographic study.

OBJECTIVE: The objective of this retrospective study was to find out (i) the prevalence of deep carious lesions, both untreated and previously treated, among 14- and 15-year olds and (ii) how deep carious lesions were managed in a Finnish public health care setting. MATERIALS AND METHODS: A random sample of 278 patients was taken from 3990 patients at the oral health care of the City of Helsinki. Radiographic subsample consisted of patients with bitewing and periapical radiographs (n = 128, 46% of the total sample). Deep carious lesions (extending to at least the inner half of dentine), deep restorations, direct pulp cappings, root canal treatments, and extractions in permanent premolars and molars were recorded from the radiographs. Patients with untreated deep carious lesions were followed up for 24 months. RESULTS: In the total sample 12% had at least one untreated deep carious lesion, 10% at least one deep restoration, and 19% at least one untreated or previously treated deep carious lesion. The follow-up cohort included 48 deep carious lesions in 26 patients. Complete excavation was the most frequently chosen method (81% for lesions reaching the inner half of dentine and 56% the inner third or deeper), followed by stepwise excavation (19% and 37%, respectively). CONCLUSIONS: One-fifth of 14-15-year-olds had at least one untreated or previously treated deep carious lesion. The choice for the carious tissue removal did not follow the current recommendations for less invasive methods. CLINICAL RELEVANCE: Continuing education is needed to improve the diagnostics and management of deep carious lesions.

Clinical Management of Interproximal and Occlusal Caries in Children and Adolescents by Canadian Dentists: A Survey.

PURPOSE: Early restorative interventions may have important implications in young patients, and the International Caries Classification and Management System strongly recommends non-surgical strategies in the management of dental caries. We aimed to assess management of interproximal and occlusal caries in children and adolescents (≤18 years of age) by Canadian dentists. METHODS: An electronic survey was created and sent to members of Canadian provincial regulatory dental bodies. The survey included 11 questions on demographic factors and 3 clinical situations on dental caries management. RESULTS: The response rate was 4.6% (n = 702). To treat interproximal carious lesions limited to enamel, 442 dentists (63.0%) reported using surgical caries removal on a permanent molar and 502 dentists (71.5%) did the same for a primary tooth. For occlusal carious lesions, the corresponding numbers were 300 dentists (42.7%) for a permanent molar and 269 (38.3%) for a primary molar. Age, year of graduation and province of practice appear to have a significant impact on the restorative threshold. CONCLUSIONS: According to the latest evidence-based recommendations for caries management, the presence of cavitated enamel should be the main indication to restore, and non-surgical interventions for non-cavitated lesions confined to enamel should be prioritized. Results show that a good proportion of respondents have a lower restorative threshold, particularly for interproximal lesions.

An image analysis protocol for the quantification of interglobular dentine in anthropological tooth sections.

The histological identification of interglobular dentine (IGD) in archeological human remains with macroscopic evidence of rickets has opened a promising new avenue for the investigation of metabolic disease in the past. Recent paleopathological studies have shown that histological analysis of archeological human teeth may allow the identification of periods of vitamin D deficiency occurring within very narrow developmental windows, yielding new information on the seasonality or even maternal-fetal transmission of this disease. However, currently available techniques for recording IGD rely on subjective scoring systems or visual estimations, potentially leaving them open to inter and intra-observer error and rendering comparisons of datasets difficult. Here we describe a new imaging protocol that utilizes open access software and may yield more objective and quantitative data on the amount of IGD present within a dentinal region of interest. We demonstrate that grayscale histograms in FIJI®/ImageJ® might be used to provide less subjective estimates of the percentage of a region of interest affected by IGD. Application of this technique may enable more accurate comparison of datasets between researchers.

Assessment of physiological disturbances during pre- and early postnatal development based on microscopic analysis of human deciduous teeth from the Late Epipaleolithic site of Shubayqa 1 (Jordan).

OBJECTIVES: To study pre- and early postnatal tooth formation and to analyze the effects of physiological disturbances on enamel and dentin formation in deciduous teeth of infants from the Late Epipaleolithic (Natufian) site Shubayqa 1. MATERIALS AND METHODS: Ten deciduous teeth from six infants (ages at death between 21 and 239 days) were analyzed by light and scanning electron microscopy. RESULTS: Marked prism cross-striations and an abnormal wavy course of the prisms were recorded in pre- and postnatal enamel of all analyzed teeth. Single or multiple accentuated incremental lines were observed in prenatal enamel of nine teeth and in postnatal enamel of eight teeth. Accentuated Andresen lines and broader zones exhibiting an enhanced calcospheritic pattern were recorded in the pre- and postnatally formed dentin of nine teeth. DISCUSSION: The structural abnormalities in the pre- and postnatally formed enamel of the infants are considered indicative of chronic stress that negatively affected the activity of secretory ameloblasts. The structural aberrations in pre- and postnatal dentin denote that odontoblasts were also affected by this stress. The presence of single or multiple accentuated incremental lines in pre- and postnatal enamel is interpreted as reflecting (short-term) impacts of higher intensity superimposed on the chronic stress. Our findings suggest compromised maternal health affecting the late fetus and compromised health in newborns. Although limited by the small number of analyzed individuals, the present study contributes to the knowledge of maternal and early infant health conditions in Late Epipaleolithic populations.

A novel hypothesis based on clinical, radiological, and histological data to explain the dentinogenesis imperfecta type II phenotype.

Purpose/Aim: The aim of this study was to explore whether dentinogenesis imperfecta (DGI)-related aberrations are detectable in odontogenic tissues. Materials and Methods: Morphological and histological analyses were carried out on 3 teeth (two maxillary 1st molars, one maxillary central incisor) extracted from a patient with DGI Type II. A maxillary 2nd molar teeth extracted from a healthy patient was used as control. A micro-computed tomographic (µCT) data-acquisition system was used to scan and reconstruct samples. Pentachrome and picrosirius red histologic stains were used to analyze odontogenic tissues and their collagenous matrices. Results: Our findings corroborate DGI effects on molar and incisor root elongation, and the hypo-mineralized state of DGI dentin. In addition to these findings, we discovered changes to the DGI pulp cavity: Reactionary dentin formation, which we theorize is exacerbated by the early loss of enamel, nearly obliterated an acellular but still-vascularized DGI pulp cavity. We also discovered an accumulation of lamellated cellular cementum at the root apices, which we hypothesize compensates for the severe and rapid attrition of the DGI tooth. Conclusions: Based on imaging and histological data, we propose a novel hypothesis to explain the complex dental phenotypes observed in patients with DGI Type II.

The efficacy of ultrasonic and PIPS (photon-induced acoustic streaming) irrigation to remove artificially placed dentine debris plugs out of an artificial and natural root model.

The aim was to validate an artificial resin 'root canal wall groove model' (RCWGM) mimicking the situation of natural roots with a groove of identical dimensions on debris removal out of these grooves, and to evaluate Erbium 'laser-activated irrigation' (LAI) with two conical tips at PIPS (photon-induced photoacoustic streaming) settings, with different activation times and different root canal positions on debris removal out of the grooves. A split RCWGM was used (resin blocks and roots of maxillary canines) with a canal size 40/0.06. The grooves in the apical third were filled with stained dentinal debris. Seventeen irrigation protocols (n = 20) were used: syringe-needle irrigation (3× 20 s), manual dynamic activation (1× 60 s), ultrasonically activated irrigation (UAI) with 25/25 Irrisafe (3× 20 s) and LAI (2940 nm Er:YAG) with X-Pulse or PIPS tips at PIPS settings (20 mJ, 50 µs, 20 Hz) and with the fibre (IN) or (OUT) the canal: IN during 1× 20 s, and OUT during 1× 20 s, 2× 20 s, 3× 20 s, 30 s, 2× 30 s and 1× 60 s. The quantity of remaining dentine debris in the groove was evaluated on a numerical scale. Statistical analysis was performed by means of proportional odds logistic regression, equivalence testing and Wald tests. The level of significance was set at 0.05. Resin models and the RCWGM with natural teeth can be called equivalent (log odds ratio 0.185). There were mostly no statistically significant differences for debris removal between UAI and LAI (p > 0.05) and between LAI with PIPS and X-Pulse (p > 0.05). Although not statistically different, the numbers of completely cleaned grooves were higher with LAI than with UAI for a 1-min activation, confirming findings from other studies. There is no difference in cleaning efficacy between X-Pulse and PIPS tips at PIPS settings.