Risk factors for noncarious cervical lesions: A case-control study.

OBJECTIVES: Noncarious cervical lesions (NCCLs) are multifactorial and can be caused by the anatomical structure of the teeth, erosion, abrasion and abnormal occlusion. The aim of this case-control study was to explore the risk factors for NCCLs. METHODS: Cone-beam computed tomography was used to determine whether a wedge-shaped defect existed at the cementoenamel junction. We compared 63 participants with NCCLs with 63 controls without NCCLs, matched for sex, age (±1 year) and toothbrushing-related factors (e.g., type of bristle and brushing patterns, frequency and strength). All participants were asked to complete a questionnaire about self-administered daily diet habits and health condition. Univariate and multivariate logistic regression analyses were conducted to determine the risk factors for NCCLs. RESULTS: Significant variables in the univariate analysis (i.e., p < .2) included frequency of carbonated beverage consumption, sella-nasion-point B angle (SNB) and Frankfort-mandibular plane angle (FMA). Multivariate logistic regression demonstrated that the consumption frequency of carbonated beverages (odds ratio [OR] = 3.147; 95% confidence interval [CI], 1.039-9.532), FMA (OR = 1.100; 95% CI, 1.004-1.204) and SNB (OR = 0.896; 95% CI, 0.813-0.988) was independent influencing factors. The area under the receiver operating characteristic curve (AUC) value of regression Model 1 (established with the frequency of carbonated beverage consumption, FMA, SNB and sleep bruxism) was 0.700 (95% CI, 0.607-0.792; p < .001), and that of regression Model 2 (established using the frequency of carbonated beverage consumption, FMA and SNB) was 0.704 (95% CI, 0.612-0.796; p < .001). CONCLUSIONS: The consumption frequency of carbonated beverages and FMA was risk factors for NCCLs; the higher the frequency of carbonated beverage consumption and FMA, the higher was the probability of NCCLs. SNB was a protective factor for NCCL occurrence; the larger the SNB, the lower was the probability of NCCL occurrence. These findings have further clarified the aetiology of NCCLs and provided clinicians with valuable insights into strategies for preventing the loss of dental tissue.

Prediction and validation of microbial community function from normal pulp to pulpitis caused by deep dentinal caries.

INTRODUCTION: Microbial function changes may be responsible for dental pulp transformation from normal to diseased. However, studies on the prediction and verification of the function of the microbial community in the deep dentine and pulp of caries-induced pulpitis are lacking. METHODS: This study included 171 cases of deep dentinal caries divided into normal pulp (NP), reversible pulpitis (RP), and irreversible pulpitis (IRP). In Experiment I, the microbial community composition was identified in 111 samples using 16S ribosomal DNA. Function prediction was performed through phylogenetic investigation of communities by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States prediction and qPCR. In Experiment II, different microbiome functions were confirmed in 60 samples using liquid chromatography-tandem mass spectrometry. RESULTS: In Experiment I, microbial abundance significantly differed in the IRP group compared to the other two groups. The RP and NP groups had the same microbiome composition, but the predicted functional difference between the RP and NP groups pertained to membrane transport (p < .010). The predicted functional difference between the IRP and NP groups pertained to amino-acid, co-factor, and vitamin metabolism (p < .010). In Experiment II, Kyoto Encyclopedia of Genes and Genomes functional annotation revealed that the differential metabolites between the RP and NP groups did not participate in membrane transport; however, the differential metabolites between the IRP and NP groups participated in amino-acid metabolism. CONCLUSIONS: The near-pulp microbiome in RP and NP with deep dentinal caries had the same differential function. However, amino acid metabolism in near the pulp microbial community differed between IRP and NP with deep dentinal caries.

New technique for detecting cracked teeth and evaluating the crack depth by contrast-enhanced cone beam computed tomography: an in vitro study.

BACKGROUND: Cracked teeth may cause various clinical symptoms depending on the extension depth of the crack and the subsequent bacterial infections. However, techniques to reliably determine the extension depths of cracks in teeth before treatment are lacking. The aim of this study was to develop a new technique based on contrast-enhanced cone beam computed tomography (CBCT) to improve the accuracy of crack depth evaluation in vitro. METHODS: We developed an in vitro artificial simulation model of cracked teeth. Pre-experimental CBCT (pre-CBCT), and micro-computed tomography (micro-CT) were first performed for all cracked teeth (n = 31). Contrast-enhanced CBCT was then performed by infiltrating the crack with ioversol under vacuum conditions. The sensitivities of pre-CBCT and contrast-enhanced CBCT for the diagnosis of cracked teeth were calculated. According to the K-means clusters, crack depths measured by micro-CT were changed into categorical variables. Bland-Altman plot and the intraclass correlation coefficient (ICC) were used to analyze the consistency of the crack depths between the pre-CBCT and contrast-enhanced CBCT, as well as the ICC between the contrast-enhanced CBCT and micro-CT. Receiver operating characteristic (ROC) curves were generated to assess the ability for predicting crack depth in the differential diagnosis using pre-CBCT and contrast-enhanced CBCT. Restricted cubic splines were also used to model the non-linear relationship between the crack depths of contrast-enhanced CBCT and micro-CT. RESULTS: The sensitivities of pre-CBCT and contrast-enhanced CBCT were 48.4%, and 67.7%, respectively. The ICC value of crack depth as measured by pre-CBCT and contrast-enhanced CBCT was 0.847 (95% confidence interval [CI] 0.380-0.960; P < 0.001). The areas under ROC curves (AUC) of pre-CBCT and contrast-enhanced CBCT were different: the AUC of pre-CBCT was 0.958 (P = 0.000, 95% CI 0.843-1.074), and the AUC of contrast-enhanced CBCT was 0.979 (P = 0.000, 95% CI 0.921-1.037), and the difference was not statistically significant (Z = - 0.707, P = 0.480). The ICC value of crack depth as measured by contrast-enhanced CBCT and micro-CT was 0.753 (95% CI 0.248-0.911; P < 0.001). CONCLUSION: Contrast-enhanced CBCT under vacuum conditions with a contrast medium can significantly improve the crack detection rate of cracked teeth; however, it cannot measure the crack depths accurately.

Comparing the Traditional Versus Conservative Endodontic Access Cavities Design of the Maxillary First Molar: Using Cone-Beam Computed Tomography.

BACKGROUND This study aimed to compare the size and location of the traditional and conservative endodontic access cavities of the right maxillary first molar teeth, projected on the occlusal surface using cone-beam computed tomography (CBCT), to obtain an ideal access cavity. MATERIAL AND METHODS Five hundred CBCT images of the right maxillary first molars, including 198 males and 302 females, were retrospectively evaluated using KaVo eXam Vision software. First, a rectangular coordinate system was established. The coordinates of 4 pulp horns and 3 root canal orifices, which projected on the occlusal surface, were marked on it. Two different access cavities were then created by connecting these points: (1) traditional endodontic access cavity (TEC) required removal of the entire roof of the pulp chamber to establish a straight-line access to the root canal system; (2) conservative endodontic access cavity (CEC) was formed by connecting the projection of each root canal orifice on the occlusal. Data were analyzed using Kruskal-Wallis and Pearson's correlation tests at a 5% significance level. RESULTS The area of TEC was approximately 9.61 mm2 for males and 8.91 mm² for females. The area of CEC was approximately 3.4 mm² for males and 3.16 mm² for females. The projections of all pulp horns and root canal orifices were in or near the central area of nine-rectangle-grid. CONCLUSIONS Compared with the traditional access cavity, creating a conservative access cavity was less invasive. Meanwhile, the access cavity should be limited to the central or near the central area of nine-rectangle-grid.

Relationship between the difference in electric pulp test values and the diagnostic type of pulpitis.

BACKGROUND: According to the diagnosis criteria of the American Association of Endodontists (AAE), sensitive responses to cold and/or heat tests of suspected teeth compared with those of control teeth can be used for the diagnosis of pulpitis, but the role of electric pulp test (EPT) is not mentioned. It is believed that EPT has some limitations in determining the vitality of the pulp. The aim of this study was to explore the association between the difference in EPT values and the differential diagnoses of reversible pulpitis (RP) and symptomatic irreversible pulpitis (SIRP) caused by dental caries. METHODS: A total of 203 cases with pulpitis caused by dental caries were included. A diagnosis of pulpitis was made on the basis of the diagnostic criteria of AAE. Patient demographic and clinical examination data were collected. The EPT values of the suspected teeth and control teeth were measured, and the differences between them were calculated. The correlation between the difference in the EPT values and diagnosis of pulpitis was analyzed using univariate and multivariate logistic regression. RESULTS: In the 203 cases (78 males and 125 females; 115 cases of RP, 88 cases of SIRP; 9 anterior teeth, 59 premolars, and 135 molars), the mean patient age was 34.04 ± 13.02 (standard deviation) years. The unadjusted (crude) model, model 1 (adjusted for age), model 2 (adjusted for age and sex), and model 3 (adjusted for age, sex, and tooth type) were established for the statistical analyses. In model 3 [odds ratio (OR) = 1.025; 95% confidence interval (CI) 1.002-1.050; P = 0.035], the difference in EPT values between RP and SIRP was statistically significant. However, the areas under the curve of predictive probability of the crude model, model 1, model 2, and model 3 were 0.565, 0.570, 0.585, and 0.617, respectively, showing that the model accuracy was low. The P-value for the trend in differences between the EPT values as a categorical variable showed that the differences in the EPT values, comparing RP and SIRP, were not statistically significant. CONCLUSIONS: Based on the present data, the difference in EPT values was not sufficient to differentiate RP from SIRP.

Autotransplantation of mature and immature third molars in 23 Chinese patients: a clinical and radiological follow-up study.

BACKGROUND: We investigated the clinical and radiographic outcomes of autotransplanted teeth over a follow-up period of 2 to 8 years, and summarize the findings of other relevant studies with regard to the primary factors that influence a good prognosis in such patients. METHODS: Twenty-three patients (6 men, 17 women) who attended Tanggu Stomatological Hospital, Tianjin, China, from 2008 through 2013, were included in the study. These patients presented with a variety of dental problems, including tooth loss, residual crowns, missing first or second molars, dental trauma, tooth fracture, and unrestored teeth. A total of 26 third molars, including 2 immature molars, were autotransplanted in these patients. The success rate of autotransplantation was assessed on the basis of clinical and radiographic outcomes after follow-up periods ranging from 2 to 8 years. RESULTS: Clinical examination revealed stability of all 26 transplanted teeth, with satisfactory masticatory function and no patient discomfort. Radiographic examination revealed normal periapical tissues and an intact lamina dura surrounding the tooth root, indicating adequate healing of periodontal tissues. CONCLUSIONS: Autotransplantation achieved good results in the Chinese sample population investigated, and was associated with an excellent prognosis. Rigorous case selection, adequate protection of the periodontal ligament, and proper oral hygiene contribute significantly to the long-term success of the procedure.

Influence of the lateral pterygoid muscle on traumatic temporomandibular joint bony ankylosis.

BACKGROUND: The pathogenesis of traumatic TMJ ankylosis remains unclear. This study aimed to verify the role of the lateral pterygoid muscle in the pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis. METHODS: Eight 6-month-old male sheep were used in this study. Bilateral TMJ osteotomies were performed to induce sagittal fractures of the mandibular condyle. The lateral one-fourth segment of the disc was removed to establish a model of TMJ bony ankylosis. Subsequently, the function of the left and right lateral pterygoid muscles was blocked (experimental group) or maintained (control group), respectively. At 12 weeks postoperatively, animals were sacrificed and TMJ complex samples were evaluated by gross observation, spiral computed tomography (CT), micro-CT, and histological examinations. RESULTS: Gross observation revealed bony ankylosis in the control TMJs and fibrous adhesions in the experimental TMJs. Spiral CT and micro-CT demonstrated that, compared to the experimental group, the control group showed calcified callus formation in the joint space and roughened articular surfaces after new bone formation, which protruded into the joint space. Maximum mediolateral and anteroposterior condylar diameters were significantly larger in the control group than in the experimental group. Micro-CT also showed that the primary growth orientation of new trabeculae was consistent with the direction of lateral pterygoid traction in the control group, but not in the experimental group. Histological examination showed fibro-osseous ankylosis in the control group, but not in the experimental group. CONCLUSIONS: The lateral pterygoid simulates the effects of distraction osteogenesis, which is an important factor in the pathogenesis of TMJ bony ankylosis during the healing of sagittal condylar fractures.

Comparison of apical and coronal extrusions using reciprocating and rotary instrumentation systems.

BACKGROUND: The aim of this study was to compare the apical and coronal extrusions by using two reciprocating and two rotary instrumentation systems. METHODS: Eighty extracted human single-rooted anterior teeth were randomly assigned to four groups. Four different root canal instrumentation systems were used according to the manufacturers instructions, including two reciprocating single-file systems, Reciproc and WaveOne, and two full-sequence rotary BLX and ProTaper instruments. Debris collected from the coronal by the instruments and apical extrusions were quantified respectively. After drying the collections, the mean weight of debris collected from apical and coronal extrusions was assessed using an electronic balance and analyzed using the Kruskal-Wallis H and Mann-Whitney U tests. RESULTS: Statistically significant differences in the apical extrusion were observed among the four groups. Reciproc and WaveOne instruments produced significantly less debris than BLX and ProTaper instruments (P < 0.05). CONCLUSIONS: All of the systems produced apical extrusion of debris. However, reciprocating single-file systems produced less apical extrusion than full-sequence rotary systems. No relationship was observed between apical and coronal extrusions.

Influence of pH on inhibition of Streptococcus mutans by Streptococcus oligofermentans.

Streptococcus oligofermentans is a novel strain of oral streptococcus that can specifically inhibit the growth of Streptococcus mutans. The aims of this study were to assess the growth of S. oligofermentans and the ability of S. oligofermentans to inhibit growth of Streptococcus mutans at different pH values. Growth inhibition was investigated in vitro using an interspecies competition assay. The 4-aminoantipyine method was used to measure the initial production rate and the total yield of hydrogen peroxide in S. oligofermentans. S. oligofermentans grew best at pH 7.0 and showed the most pronounced inhibitory effect when it was inoculated earlier than S. mutans. In terms of the total yield and the initial production rate of hydrogen peroxide by S. oligofermentans, the effects of the different culture pH values were as follows: pH 7.0 > 6.5 > 6.0 > 7.5 > 5.5 = 8.0 (i.e. there was no significant difference between pH 5.5 and pH 8.0). Environmental pH and the sequence of inoculation significantly affected the ability of S. oligofermentans to inhibit the growth of S. mutans. The degree of inhibition may be attributed to the amount of hydrogen peroxide produced.

Efficacy of four different irrigation techniques combined with 60 °C 3% sodium hypochlorite and 17% EDTA in smear layer removal.

BACKGROUND: Efforts to improve the efficacy of smear layer removal by applying irrigant activation at the final irrigation or by elevating the temperature of the irrigant have been reported. However, the combination of such activation protocols with 60 °C 3% sodium hypochlorite (NaOCl) has seldom been mentioned. The aim of this study was to compare the efficacy in smear layer removal of four different irrigation techniques combined with 60 °C 3% NaOCl and 17% EDTA. METHODS: Fifty single-rooted teeth were randomly divided into five groups (n = 10) according to the irrigant agitation protocols used during chemomechanical preparation(Dentsply Maillefer, Ballaigues, Switzerland): a side-vented needle group, a ultrasonic irrigation (UI) group, a NaviTip FX group, an EndoActivator group, and a control group (no agitation). After each instrumentation, the root canals were irrigated with 1 mL of 3% NaOCl at 60 °C for 1 minute, and after the whole instrumentation, the root canals were rinsed with 1 mL of 17% EDTA for 1 minute. Both NaOCl and EDTA were activated with one of the five irrigation protocols. The efficacy of smear layer removal was scored at the apical, middle and coronal thirds. The Data were statistically analyzed using SAS version 9.2 for Windows (rank sum test for a randomised block design and ANOVA). RESULTS: No significant differences among the NaviTip FX group, EndoActivator group and control groups, and each of these groups showed a lower score than that of UI group (P < 0.05). Within each group, all three thirds were ranked in the following order: coronal > middle > apical (P < 0.05). In the coronal third, the NaviTip FX group was better than UI group. In the middle and apical third, the differences were not significant among any of the groups. CONCLUSIONS: Even without any activation, the combination of 60 °C 3% NaOCl and 17% EDTA could remove the smear layer effectively, similar to NaviTip FX or EndoActivator, and these three protocols were more effective than UI. However, regardless of different types of irrigation technique applied, complete removal of the smear layer was not achieved, particularly in the apical third.

Association between obesity and dental caries in Chinese children.

The study sought to analyze the association between dental caries and obesity in Chinese children, and to investigate the protective and risk factors of dental caries. A total of 280 children aged 7-12 years voluntarily answered the caries examination and questionnaire. Caries was measured using the International Caries Detection and Assessment System. According to the Chinese body mass index, the participants were grouped overweight or normal-weight. The logistic regression model showed no correlation between dental caries and obesity. Drinking yogurt and chewing gum are protective factors, whereas oral breathing and genetic predisposition to caries are risk factors.

Prediction of pulp exposure risk of carious pulpitis based on deep learning.

OBJECTIVES: This study aims to predict the risk of deep caries exposure in radiographic images based on the convolutional neural network model, compare the prediction results of the network model with those of senior dentists, evaluate the performance of the model for teaching and training stomatological students and young dentists, and assist dentists to clarify treatment plans and conduct good doctor-patient communication before surgery. METHODS: A total of 206 cases of pulpitis caused by deep caries were selected from the Department of Stomatological Hospital of Tianjin Medical University from 2019 to 2022. According to the inclusion and exclusion criteria, 104 cases of pulpitis were exposed during the decaying preparation period and 102 cases of pulpitis were not exposed. The 206 radiographic images collected were randomly divided into three groups according to the proportion: 126 radiographic images in the training set, 40 radiographic images in the validation set, and 40 radiographic images in the test set. Three convolutional neural networks, visual geometry group network (VGG), residual network (ResNet), and dense convolutional network (DenseNet) were selected to analyze the rules of the radiographic images in the training set. The radiographic images of the validation set were used to adjust the super parameters of the network. Finally, 40 radiographic images of the test set were used to evaluate the performance of the three network models. A senior dentist specializing in dental pulp was selected to predict whether the deep caries of 40 radiographic images in the test set were exposed. The gold standard is whether the pulp is exposed after decaying the prepared hole during the clinical operation. The prediction effect of the three network models (VGG, ResNet, and DenseNet) and the senior dentist on the pulp exposure of 40 radiographic images in the test set were compared using receiver operating characteristic (ROC) curve, area under the ROC curve (AUC), accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and F1 score to select the best network model. RESULTS: The best network model was DenseNet model, with AUC of 0.97. The AUC values of the ResNet model, VGG model, and the senior dentist were 0.89, 0.78, and 0.87, respectively. Accuracy was not statistically different between the senior dentist (0.850) and the DenseNet model (0.850)(P>0.05). Kappa consistency test showed moderate reliability (Kappa=0.6>0.4, P<0.05). CONCLUSIONS: Among the three convolutional neural network models, the DenseNet model has the best predictive effect on whether deep caries are exposed in imaging. The predictive effect of this model is equivalent to the level of senior dentists specializing in dental pulp.

Prediction of accessory canals on the apical third of mandibular second molar based on micro-computed tomography.

OBJECTIVE: The aim of this study was to investigate the anatomical factors influencing the incidence of accessory canals (ACs) in the apical third of the mandibular second molar in Chinese population. METHODS: Micro-CT was performed on 86 root canals. The five possible factors influencing the incidence of ACs in the apical third were named X1 to X5. These factors were the canal length of the apical third, fused roots, location of apical foramen, curvature of the root canals, and complexity of the canals. Statistical analysis was performed by the least absolute shrinkage and selection operator, receiver operating characteristic curve, and the χ2 test (α = 0.05). RESULTS: The selected variables in the least absolute shrinkage and selection operator regression model were fused roots and complex root canals. The area under the curve was 0.737, indicating that the model had a certain predictive ability. ACs were mainly distributed in the buccal wall and mesial wall of root canals in the apical third of molars (p < 0.05). CONCLUSIONS: For Chinese population, fused roots and complex root canals are anatomical factors influencing ACs in the apical one-third of mandibular second molars, and the ACs mainly occur in the buccal wall and mesial wall of the root canal.

Interspecies competition and inhibition within the oral microbial flora: environmental factors influence the inhibition of Streptococcus mutans by Streptococcus oligofermentans.

Dental caries is a bacterial infectious disease. Streptococcus mutans is the primary pathogen that causes dental caries. Streptococcus oligofermentans is a new oral streptococcal species that can inhibit the growth of S. mutans specifically. The study aimed to assess the inhibition of S. mutans by S. oligofermentans under different oral environmental conditions. The inhibition under different carbohydrate and oxygen conditions was investigated in vitro using an interspecies interaction assay. The 4-aminoantipyine (4-ATTP) method was used to measure the yield and the initial production rate of H(2) O(2) in S. oligofermentans. The inhibitory effect was enhanced when the bacteria were cultured with carbohydrates and under aerobic conditions, or when S. oligofermentans was inoculated earlier than S. mutans. The initial synthesis rates of H(2) O(2) by S. oligofermentans were higher in the presence of carbohydrates and in aerobic culture conditions. In terms of the total H(2) O(2) yield, the effect of the environmental conditions was as follows: no carbohydrates > sucrose> glucose, and aerobic conditions > anaerobic conditions. We conclude that the presence of carbohydrate and oxygen significantly affect the ability of S. oligofermentans to inhibit the growth of S. mutans. The difference in inhibitory effect may be attributed to changes in the capacity of S. oligofermentans to produce H(2) O(2) .

Relationship between Clinical Symptoms and the Microbiota in Advanced Caries.

INTRODUCTION: The composition and relative abundance of bacterial species change throughout the development of dental caries; however, how these changes relate to clinical symptoms remains elusive. In this study, we explored the relationship between clinical symptoms and specific microorganisms in advanced dentinal caries. METHODS: A total of 111 permanent premolars and molars were used to simulate the progression from caries to pulpitis indirectly. Clinical symptoms were evaluated, and teeth were diagnosed according to the diagnostic criteria of the American Association of Endodontics. Samples were collected for 16S ribosomal DNA sequencing. Associations between the microbiota and clinical symptoms/diagnosis and the relationship between alpha diversity and clinical symptoms/diagnosis were evaluated independently by the linear discriminant analysis effect size and Spearman rank correlation analyses. RESULTS: The 16S ribosomal DNA sequences were assigned to 13,852 operational taxonomic units. The linear discriminant analysis effect size and Spearman correlations unveiled negative associations between the relative abundance of Bacteroidia and Gammaproteobacteria and referred pain, Gammaproteobacteria and the electric pulp test response, and Actinomyces and Propionibacterium and diagnosis (r < 0.0, P < .05). Conversely, the relative abundance of Lactobacillus was positively correlated to referred pain, the cold test, the percussion response, and diagnosis (r > 0, P < .05). Lactobillus reuteri, a probiotic bacterium, was more abundant in teeth with referred pain and teeth diagnosed with symptomatic irreversible pulpitis. The Spearman correlation between alpha diversity and clinical symptoms/diagnosis was not significant (P > .05). CONCLUSIONS: Clinical symptoms and diagnosis were significantly associated with specific microorganisms in the most advanced layers of dentinal caries.

Microbiome of Deep Dentinal Caries from Reversible Pulpitis to Irreversible Pulpitis.

INTRODUCTION: This study examined the identity of the microbiome of deep dentinal caries and its correlation with the inflammation status of caries-induced pulpitis. METHODS: Seventy-five cases were diagnosed based on the American Association of Endodontics's diagnostic criteria and divided into 4 groups: normal pulp with deep caries (NP; n = 13), reversible pulpitis with only cold-evoked pain (CRP; n = 17), reversible pulpitis with both cold/heat-evoked pain (CHRP; n = 24), and symptomatic irreversible pulpitis (SIP; n = 21). Samples were sequenced by 16S rDNA. Alpha and beta diversity were determined. Linear discriminant analysis effect size (LEfSe) analysis was used to detect intergroup differences, and receiver operating characteristic (ROC) curves were generated to assess the role of the caries microbiome in caries-induced pulpitis. RESULTS: The 16S rDNA sequencing yielded 9100 operational taxonomic units. Lactobacillus had the highest relative abundance at the genus level among the 4 groups. There were significant differences in the distribution of the microbiome among the groups. In an alpha diversity analysis, species richness differed between the CRP group and the other groups. In a beta diversity analysis, the distribution of microorganisms in the SIP group was significantly different from those in the other 3 groups. LEfSe analysis indicated substantial differences in the microbiome among the groups, and the areas under the ROC curves (AUC) were all high (AUC: 0.734-0.952). CONCLUSIONS: Characterization of the caries microbiome has the potential to become an auxiliary method for the diagnosis of pulpitis. This finding may prompt new research on diagnostic strategies for caries-induced pulpitis.

A preliminary study on potential association between psychopathological status and rhythmic masticatory muscle activity of young patients with sleep bruxism in Tianjin China.

OBJECTIVES: The aim of this cross-sectional study was to assess the psychological status of patients with bruxism and to explore the potential relationship between psychological status and rhythmic masticatory muscle activity (RMMA), since the basic manifestation of sleep bruxism is RMMA. METHODS: Twenty-five patients (nine males, 16 females, and mean age 27.84 ± 5.60) who self-reported having SB and 25 normal subjects were randomly recruited. Fifty subjects filled out the Symptom Checklist-90 (SCL-90) to assess their psychopathological status. SB was diagnosed by polysomnography (PSG), and RMMA was recorded based on the results of PSG. RESULTS: In this study we detected 15.89 ± 4.23 RMMA episodes per hour in normal subjects, whereas 41.23 ± 16.78 RMMA episodes per hour were recorded in patients with SB, which was nearly three times of the former group with statistical significance (P = 0.001). Paired t-test revealed significant differences between SB patients and normal subjects in any of the SCL-90 subscales (P = 0.001). Regarding total psychopathological scores, 10 of the 25 SB patients endorsed scores higher than 160, and the positive rate was 40%. In addition, obsessive-compulsive behavior, interpersonal sensitivity, depression, anxiety, paranoid ideation and psychoticism were all statistically associated with RMMA (P < 0.05). CONCLUSION: Within the limitations of the study, we found that patients with sleep bruxism tend to have poor psychological status, and obsessive-compulsive behavior, interpersonal sensitivity, depression, anxiety, paranoid ideation and psychoticism are related to onset of SB.

Expression of Cannabinoid Type 1 Receptors in Human Odontoblast Cells.

INTRODUCTION: The aim of this study was to investigate the functional expression of cannabinoid type 1 (CB1) receptors in human odontoblasts (HODs) and the possible internal mechanism. METHODS: In the present study, we examined the molecular and functional expression of the CB1 receptors in cultured HOD-like cells and native HODs obtained from healthy wisdom teeth. RESULTS: Immunohistochemistry and immunofluorescence revealed that CB1 receptors localize to native HODs and HOD-like cells, respectively. Both reverse-transcription polymerase chain reaction and Western blot analysis confirmed gene and protein expression of CB1 receptors. The ultrastructural distribution by immunoelectron microscopy also found that CB1 receptors labeled by colloidal gold particles distribute sparsely in the cytoplasm and odontoblastic processes. In functional assays, 2-arachidonyl glycerol, as an agonist of CB receptors, elicited the increase of intracellular fluorescence intensity that could be inhibited by a CB1-specific receptor antagonist rather than a selective CB2 receptor antagonist with fluo-3AM Ca2+ fluorescence. The source of the increase of intracellular fluorescence intensity elicited by CB1 receptors was from extracellular Ca2+ but not intracellular Ca2+ stores. The process of 2-arachidonyl glycerol activating CB1 receptors modulated transient receptor potential vanilloid 1-mediated Ca2+ entry via the cyclic adenosine monophosphate signaling pathway. CONCLUSIONS: We conclude that HODs can express functional CB1 receptors that may play an important role in mediating the physiological function in tooth pulp.

The Extent of the Crack on Artificial Simulation Models with CBCT and Periapical Radiography.

BACKGROUND: The aim of this study was to investigate the extent of the crack of a cracked tooth on an artificial simulation model with Periapical Radiography (PR) and cone beam computed tomography (CBCT) in vitro, providing the basis for early diagnosis and an appropriate treatment plan. METHODS: Forty-four teeth with different extents of artificial cracks, created by exposure to liquid nitrogen after hot water at 100°C, were collected. They were subjected to PR and CBCT. Micro-computed tomography (micro-CT) examination, regarded as a relatively more accurate measurement than others, was used to measure and record the crack depth. Three observers, an endodontic graduate student, an experienced endodontist, and an experienced radiologist, examined the PR and CBCT results independently, and the presence or absence of cracks with PR and CBCT were respectively recorded. The external consistency ICC with 95% confidence interval (95% CI) was used to analyze the consistency among the graduate student, endodontist, and radiologist; ROC curves were used for the analysis of diagnostic performance of both radiographic modalities for tooth cracks with crack depth. RESULTS: For the interpretation of the PR results, there were statistically significant differences among the three different observers (P < 0.001), and the interpretation of the CBCT results (P < 0.001). In the group of results read by the graduate student, the sensitivity of diagnosis with CBCT and PR was 77.27% and 22.73%, respectively (P < 0.001). In the group of results read by the endodontist, the sensitivity of diagnosis with CBCT and PR was 81.81% and 8.19%, respectively (P < 0.001). In the group of results read by the radiologist, the sensitivity of diagnosis with CBCT and PR was 88.64% and 11.36%, respectively (P < 0.001). As for CBCT diagnosis, the critical value for the graduate, endodontist, and radiologist was 3.20 mm, 2.06 mm, and 1.24 mm, respectively. For the PR diagnosis, the critical value for the graduate, endodontist, and radiologist was 6.12 mm, 6.94 mm, and 6.94 mm, respectively. CONCLUSIONS: Within the limitations of this study, on an artificial simulation model of cracked teeth for early diagnosis, we recommend that it would be better for a cracked tooth to be diagnosed by a radiologist with CBCT than PR, CBCT with a minimum depth of 1.24 mm.

Predicting extension of cracks to the root from the dimensions in the crown: A preliminary in vitro study.

BACKGROUND: In this study, the authors investigated whether extension of a tooth crack into the root can be predicted by the appearance of the crack in the crown in vitro. METHODS: The authors obtained 22 cracked teeth from 22 patients who underwent extraction, and they scanned the teeth using microcomputed tomography. The length and width of the crack on the occlusal surface (LOS and WOS, respectively) and the length of the crack on the proximal surface (LCPS) were measured on 3-dimensional reconstruction images. The pulp chamber roof was penetrated and removed. A crack line visible under the microscope only on the access cavity wall rather than extending to the bottom of the pulp chamber was termed a "nonroot crack." A crack seen at the bottom of the pulp chamber or root wall was termed a "root crack." The authors analyzed the data using Pearson correlation coefficients and receiver operating characteristic curves. RESULTS: There was a significant correlation between the LOS and LCPS (correlation coefficient, 0.782; P < .001) and between the WOS and LCPS (correlation coefficient, 0.651; P < .05). The LCPS increased by 1.195 millimeters for every 1-mm increase in the LOS. The area under the receiver operating characteristic curve was 0.839 (95% confidence interval, 0.659 to 1.000) for LOS and 0.760 (95% confidence interval, 0.557 to 0.964) for WOS. CONCLUSIONS: The extent of a crown crack may indicate how far the crack extends to the root. Both the LOS and WOS may be valuable for assessing whether a crack involves the root, although the LOS seems to be more useful. PRACTICAL IMPLICATIONS: The dimensions of a crack in a crown provide a helpful approach for predicting the depth of the crack and its likely prognosis.