The clustering effects of surfaces within the tooth and teeth within individuals

A novel deep learning-based perspective for tooth numbering and caries detection

OBJECTIVES

The aim of this study was automatically detecting and numbering teeth in digital bitewing radiographs obtained from patients, and evaluating the diagnostic efficiency of decayed teeth in real time, using deep learning algorithms.

METHODS

The dataset consisted of 1170 anonymized digital bitewing radiographs randomly obtained from faculty archives. After image evaluation and labeling process, the dataset was split into training and test datasets. This study proposed an end-to-end pipeline architecture consisting of three stages for matching tooth numbers and caries lesions to enhance treatment outcomes and prevent potential issues. Initially, a pre-trained convolutional neural network (CNN) utilized to determine the side of the bitewing images. Then, an improved CNN model YOLOv7 was proposed for tooth numbering and caries detection. In the final stage, our developed algorithm assessed which teeth have caries by comparing the numbered teeth with the detected caries, using the intersection over union value for the matching process.

RESULTS

According to test results, the recall, precision, and F1-score values were 0.994, 0.987 and 0.99 for teeth detection, 0.974, 0.985 and 0.979 for teeth numbering, and 0.833, 0.866 and 0.822 for caries detection, respectively. For teeth numbering and caries detection matching performance; the accuracy, recall, specificity, precision and F1-Score values were 0.934, 0.834, 0.961, 0.851 and 0.842, respectively.

CONCLUSIONS

The proposed model exhibited good achievement, highlighting the potential use of CNNs for tooth detection, numbering, and caries detection, concurrently.

CLINICAL SIGNIFICANCE

CNNs can provide valuable support to clinicians by automating the detection and numbering of teeth, as well as the detection of caries on bitewing radiographs. By enhancing overall performance, these algorithms have the capacity to efficiently save time and play a significant role in the assessment process.

Caries clusters at lesion-severity thresholds: A Sierra Leone case study

OBJECTIVES

Despite being almost entirely preventable, globally, dental caries is extremely prevalent. Moreover, dental caries will continue to present an even larger challenge for lower income countries, particularly those in the African context, as they transition to a more Western diet. Hence, epidemiological data providing insight into disease patterns and trends is critical to inform public health action. The purpose of this study was to examine dental caries clusters by caries detection threshold among 15-year-old adolescents in Sierra Leone, using data from the latest national survey, and to explore associated sociodemographic factors.

METHODS

This paper presents a secondary analysis of oral health data on 490 15-year-olds from the Sierra Leone national oral health survey of schoolchildren. Hierarchical cluster analysis of dental caries experience was conducted across all surfaces at four decay detection thresholds using the International Caries Detection and Assessment System (ICDAS) (clinical: ICDAS 2-6, cavitated: ICDAS 3-6, obvious: ICDAS 4-6 and extensive obvious: ICDAS 5-6 decay) across the four regions of Sierra Leone. Ordered logistic regression was used to estimate the association of sociodemographic factors with generated clusters relating to clinical and obvious decay experience. These are of both clinical and epidemiological relevance.

RESULTS

A 3-cluster decay pattern representing a 'low' to 'high' decay experience distribution was observed under each decay detection threshold across surfaces. For clinical decay (including visual enamel caries), 28.8% had low, 55.1% medium and 15.9% high caries status. In the adjusted model, the only significant risk factor across obvious and clinical decay thresholds was region, with adolescents outside the Western region more likely to experience decay.

CONCLUSION

This study suggests that adolescents in Sierra Leone fall into three distinct caries clusters: low, medium to high decay experience distribution, regardless of decay threshold. It reinforces the importance of recognizing dental caries detection thresholds and the use of contemporary epidemiological methodology. This suggests that adolescents outside the Western region are likely to have higher caries experience. The data also provides insight to the nature of adolescents in each cluster and should help to inform policy and planning of the integration of oral health into primary care and school systems.

Convolutional neural network-based measurement of crown-implant ratio for implant-supported prostheses

STATEMENT OF PROBLEM

Research has revealed that the crown-implant ratio (CIR) is a critical variable influencing the long-term stability of implant-supported prostheses in the oral cavity. Nevertheless, inefficient manual measurement and varied measurement methods have caused significant inconvenience in both clinical and scientific work.

PURPOSE

This study aimed to develop an automated system for detecting the CIR of implant-supported prostheses from radiographs, with the objective of enhancing the efficiency of radiograph interpretation for dentists.

MATERIAL AND METHODS

The method for measuring the CIR of implant-supported prostheses was based on convolutional neural networks (CNNs) and was designed to recognize implant-supported prostheses and identify key points around it. The experiment used the You Only Look Once version 4 (Yolov4) to locate the implant-supported prosthesis using a rectangular frame. Subsequently, two CNNs were used to identify key points. The first CNN determined the general position of the feature points, while the second CNN finetuned the output of the first network to precisely locate the key points. The network underwent testing on a self-built dataset, and the anatomic CIR and clinical CIR were obtained simultaneously through the vertical distance method. Key point accuracy was validated through Normalized Error (NE) values, and a set of data was selected to compare machine and manual measurement results. For statistical analysis, the paired t test was applied (α=.05).

RESULTS

A dataset comprising 1106 images was constructed. The integration of multiple networks demonstrated satisfactory recognition of implant-supported prostheses and their surrounding key points. The average NE value for key points indicated a high level of accuracy. Statistical studies confirmed no significant difference in the crown-implant ratio between machine and manual measurement results (P>.05).

CONCLUSIONS

Machine learning proved effective in identifying implant-supported prostheses and detecting their crown-implant ratios. If applied as a clinical tool for analyzing radiographs, this research can assist dentists in efficiently and accurately obtaining crown-implant ratio results.

Effectiveness of silver diamine fluoride versus sodium fluoride varnish combined with mother's motivational interviewing for arresting early childhood caries: a randomized clinical trial

BACKGROUND

Silver Diamine Fluoride (SDF) has gained attention as one of the minimally invasive modalities to manage ECC although it causes black staining of treated carious lesions. A possible affordable alternative may be Sodium Fluoride (NaF) varnish combined with good oral hygiene promoted by parental Motivational Interviewing (MI). The study compared the effectiveness of 38% SDF solution and 5% NaF varnish supported by parental MI in arresting ECC.

MATERIALS AND METHODS

Children aged ≤ 4 years old with at least one active carious lesion (ICDAS score ≥ 3) were randomly assigned to treatment by a single application of 38% SDF solution or a single application of 5% NaF varnish supported by two MI sessions for mothers at baseline and after three months. Chi-Squared test was used to compare groups and multilevel logistic regression analysis was used to assess the effect of the interventions on ECC arrest adjusting for confounders. The interaction between the type of intervention and baseline lesion severity, moderate (ICDAS 3/4) or advanced (ICDAS 5/6), was also assessed.

RESULTS

The study included 165 children with 949 active lesions. After 6 months, there were no significant differences between SDF and NaF/MI groups in overall caries arrest (63.7% and 58.1%, p = 0.08), and in moderate lesions (72.9% and 69.6%, p = 0.52). However, in advanced lesions, the arrest rate was significantly higher in the SDF than the NaF/ MI group (60.3% and 50.0%, P = 0.01). Multilevel multiple logistic regression showed no significant differences between the interventions (AOR = 1.56, P = 0.27) with significant interaction between the intervention and baseline lesion severity (p < 0.001). Moderate lesions treated with SDF (AOR = 3.69, P = 0.008) or NaF/MI (AOR = 3.32, P < 0.001) had significantly higher odds of arrest than advanced lesions treated with NaF/ MI with no difference between advanced lesions treated with SDF or NaF/ MI (AOR = 1.85, P = 0.155) in arrest rate.

CONCLUSION

NaF/ MI can be an alternative to SDF in arresting advanced and moderate ECC lesions without staining with stronger effect on moderate lesions (ICDAS 3/4).

TRIAL REGISTRATION

The trial was retrospectively registered at clinicaltrial.gov registry (#NCT05761041) on 9/3/2023.

Resin Infiltration of Non-Cavitated Proximal Caries Lesions in Primary and Permanent Teeth: A Systematic Review and Scenario Analysis of Randomized Controlled Trials

The present study aimed to meta-analyze and evaluate the certainty of evidence for resin infiltration of proximal carious lesions in primary and permanent teeth. While resin infiltration has been shown efficacious for caries management, the certainty of evidence remains unclear. The protocol was registered with PROSPERO (CRD42018080895), and PRISMA guidelines have been followed. The databases PubMed, Embase, and Cochrane CENTRAL were systematically screened, complemented by hand searches and cross-referencing. Eleven relevant articles were identified and included, i.e., randomized controlled trials (RCTs) comparing the progression of resin infiltrated proximal caries lesions (combined with non-invasive measures) in primary or permanent teeth with non-invasive measures. Random-effects meta-analyses and trial sequential analyses (TSA) were performed for per-protocol (PP), intention-to-treat (ITT), and best/worst case (BC/WC) scenarios. Six included trials assessed lesions in permanent teeth and five trails assessed lesions in primary teeth. The trials had a high or unclear risk of bias. Risk of caries progression was significantly reduced for infiltrated lesions in the PP, ITT, and BC scenarios in both permanent teeth and primary teeth, but not in the WC scenario. According to the TSA, firm evidence was reached for all of the scenarios except the WC. In conclusion, there is firm evidence for resin infiltration arresting proximal caries lesions in permanent and primary teeth.

Dental plaque and gingival bleeding in adolescents with juvenile idiopathic arthritis and controls: a multilevel analysis

OBJECTIVE

To explore whether plaque and gingival bleeding are more frequently experienced by adolescents with juvenile idiopathic arthritis (JIA) compared to matched controls without JIA; explore whether surface- and site-specific periodontal outcomes vary between the two groups; and for participants with JIA, investigate associations between disease-specific features and periodontal outcomes.

MATERIAL AND METHODS

In this comparative cross-sectional study, selected surfaces, and sites of index teeth in 10-16-year-olds with JIA and matched controls were examined by modified versions of Simplified Oral Hygiene Index (OHI-S) and Gingival Bleeding Index (GBI). Mixed-effects logistic regressions, reporting odds ratios (OR) with 95% confidence interval (CI), were applied. Intra-class correlation coefficients (ICCs) were calculated to quantify the degree of dependency of measures within the same individual.

RESULTS

144 and 159 adolescents with JIA were evaluated according to OHI-S and GBI; corresponding numbers of controls were 154 and 161. Plaque and gingival bleeding were more frequent in individuals with JIA than controls. Adjusted analyses showed association between JIA status and OHI-S > 0 (OR = 2.33, 95% CI: 1.47 - 3.67, ICC = 0.45) and GBI > 0 (OR = 1.54, 95% CI: 1.10 - 2.16, ICC = 0.41 and 0.30). Surface-specific distribution of plaque varied among the two groups.

CONCLUSIONS

Our results highlight the importance of increased awareness of oral health care in patients with JIA and that surface- and site-specific differences in periodontal outcomes exist between individuals with JIA and controls. Few JIA disease-specific variables associated with plaque or gingival bleeding.

Is Silver Diamine Fluoride Effective in Arresting Enamel Caries? A Randomized Clinical Trial

Background: There is limited information on the effectiveness of 38% silver diamine fluoride (SDF) in managing enamel caries. Objective: This study aimed to compare effectiveness of 38% SDF and 5% Sodium fluoride (NaF) varnish in arresting enamel caries in young children when applied semiannually over 18 months. Methods: A randomized controlled trial was conducted on children aged 1−3 years who had at least one active carious surface. They were allocated into two groups: Group 1 (38% SDF) and Group 2 (5% NaF varnish). Visual-tactile examination was used to assess extent of carious lesions. Enamel caries that did not progress to dentin were classified as having caries arrest. Intention-to-treat analysis was performed. Results: At baseline, 290 children with 1974 tooth surfaces with enamel caries were recruited. Caries arrest rates at the tooth surface level in Group 1 and Group 2 were 59.1% and 58.8%, respectively (p = 0.873), at 18 months. The multilevel logistic regression analysis revealed that tooth position, tooth surface, extent of enamel caries at baseline, caries experience, and brushing with fluoride toothpaste influenced caries arrest (p < 0.05). Conclusion: The semiannual application of 38% SDF and 5% NaF varnish had comparable effectiveness in arresting enamel caries in primary teeth.

Caries experience by socio-behavioural characteristics in HIV-1-infected and uninfected Ugandan mothers - a multilevel analysis

OBJECTIVES

To assess caries experience in Ugandan mothers according to HIV status, socio-behavioural-characteristics, gingival bleeding status and to examine whether HIV status impacts the association of socio-behavioural characteristics with caries experience. Third, using multilevel analysis, this study assessed to what extent surface-specific caries experience varied between and within individuals.

MATERIALS AND METHODS

Caries experience was recorded using the World Health Organization's Decayed, Missed and Filled Teeth/Surfaces indices from a cohort of 164 HIV-1-infected Ugandan mothers and a cross sectional comparison group of 181 negative controls. Mixed-effects logistic regression was conducted with surface-specific caries experience as the outcome variable.

RESULTS

The prevalence of caries in HIV-1-infected and uninfected mothers was 81% and 71%, respectively. Significant associations occurred between caries experience at surface level and women's increasing age (odds ratio [OR] = 1.8, 95% confidence interval [CI]: 1.1-2.8) and presence of gingival bleeding (OR = 2.0, 95% CI: 1.2-3.2). Intra-class correlation (ICC) coefficient amounted to 0.54 (95% CI 0.48‒0.59).

CONCLUSIONS

Caries prevalence was higher in HIV-1 infected than in uninfected mothers and increased with age and gingival bleeding. ICC indicated that 54% of the variance was attributable to variation between individuals. Socio-demographic differences in dental caries did not vary by HIV-1 status.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-omputed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

Analysis of the mandibular canal course using unsupervised machine learning algorithm

Objectives

Anatomical structure classification is necessary task in medical field, but the inevitable variability of interpretation among experts makes reliable classification difficult. This study aims to introduce cluster analysis, unsupervised machine learning method, for classification of three-dimensional (3D) mandibular canal (MC) courses, and to visualize standard MC courses derived from cluster analysis in the Korean population.

Materials and methods

A total of 429 cone-beam computed tomography images were used. Four sites in the mandible were selected for the measurement of the MC course and four parameters, two vertical and two horizontal parameters were measured per site. Cluster analysis was carried out as follows: parameter measurement, parameter normalization, cluster tendency evaluation, optimal number of clusters determination, and k-means cluster analysis. The 3D MC courses were classified into three types with statistically significant mean differences by cluster analysis.

Results

Cluster 1 showed a smooth line running towards the lingual side in the axial view and a steep slope in the sagittal view. Cluster 2 ran in an almost straight line closest to the lingual and inferior border of mandible. Cluster 3 showed the pathway with a bent buccally in the axial view and an increasing slope in the sagittal view in the posterior area. Cluster 2 showed the highest distribution (42.1%), and males were more widely distributed (57.1%) than the females (42.9%). Cluster 3 comprised similar ratio of male and female cases and accounted for 31.9% of the total distribution. Cluster 1 had the least distribution (26.0%) Distributions of the right and left sides did not show a statistically significant difference.

Conclusion

The MC courses were automatically classified as three types through cluster analysis. Cluster analysis enables the unbiased classification of the anatomical structures by reducing observer variability and can present representative standard information for each classified group.

Dental caries in children and adolescents with juvenile idiopathic arthritis and controls: a multilevel analysis

Background

Optimal utilization of dental caries data is crucial in epidemiological research of individuals with juvenile idiopathic arthritis (JIA). The aims were to: explore whether caries is more prevalent among children and adolescents with JIA compared to controls; examine presence of caries according to JIA group, socio-behavioral and intraoral characteristics, and the extent to which surface-specific caries varies between and within individuals; assess whether surface-specific caries varies according to JIA group and dentition; and investigate whether disease-specific clinical features of JIA are associated with presence of caries.

Methods

In this comparative cross-sectional study, calibrated dentists examined index teeth (primary 2. molars, 1. permanent molars) of 4–16-year-olds with JIA (n = 219) and matched controls (n = 224), using a detailed caries diagnosis system (including enamel caries). JIA-specific characteristics were assessed by pediatric rheumatologists and socio-behavioral information collected by questionnaires. Multilevel mixed-effect logistic regressions reporting odds ratios (OR) with 95% confidence interval (CI) were applied (caries at surface level as outcome variable). Potential confounders were adjusted for, and the effect of dependency of surface-specific caries data was estimated by calculating intra-class correlation coefficients (ICC).

Results

At individual level, no significant difference in caries prevalence was found between individuals with JIA and controls, regardless of inclusion of enamel caries. Proportion of enamel lesions exceeded dentine lesions. JIA was not associated with presence of caries, but in both groups, low maternal educational level was associated with presence of caries (OR: 2.07, 95% CI: 1.24–3.46). Occlusal and mesial surfaces, compared to buccal surfaces, had generally higher OR according to presence of caries than distal and lingual surfaces (ICC = 0.56). Surface-specific caries in the permanent dentition differed significantly according to group affiliation. Some JIA disease-specific variables were suggested to associate with presence of caries.

Conclusions

No overall difference in caries prevalence between individuals with JIA and controls was observed, but for both groups, low maternal educational level and tooth surface associated with presence of caries. Associations between JIA disease-specific variables and presence of caries cannot be excluded. Due to predominance of enamel lesions, the potential of preventative dental strategies is considerable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01758-y.

Chlorhexidine to improve the survival of ART restorations: A systematic review and meta-analysis

OBJECTIVES

Our aim was to systematically assess the efficacy of chlorhexidine (CHX) as a cavity pre-treatment or restoration mix-in on the survival of ART restorations.

DATA

We included randomized controlled trials that assessed the effect of cavity pretreatment with CHX or the restoration mix-in of CHX on the survival of ART restorations (test group) versus a similar restorative approach without CHX. Risk of bias was assessed using Cochrane's randomized trial quality assessment Tool (RoB 2.0). Random-effects meta-analysis was conducted, with mean Odds Ratios and 95 % confidence intervals (OR, 95 % CI) as effect estimates. The certainty of the evidence was assessed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system.

SOURCES

Medline, Web of Science, Cochrane Central were searched. Eligible studies were in- or excluded and data extracted for included studies by two reviewers independently.

STUDY SELECTION

Four studies with 261 patients (mean age 3.8-14.6 years) and 467 ART restorations were included. All studies showed some concerns about the risk of bias. Three studies involving a total of 167 restorations in the CHX group and 188 restorations in the control group, followed up for one year, were submitted to meta-analysis. There were no significant differences between CHX vs. control (OR = 0.79, 95 % CI [0.26, 2.40], P = 0.68, I² = 3%, P = 0.35). The strength of the evidence was estimated as low.

CONCLUSIONS

Based on very limited data, CHX pre-treatment or restoration mix-in did not have any significant benefit for survival of ART restorations.

CLINICAL SIGNIFICANCE

There is a lack of evidence regarding the influence of chlorhexidine on the survival of ART restorations. Our results revealed that there was no significant difference in the survival of ART restorations when CHX was used as a cavity pre-treatment or mix-in.

A randomized clinical trial to arrest dentin caries in young children using silver diamine fluoride

OBJECTIVES

The study aimed to compare the effectiveness of 38% silver diamine fluoride (SDF) solution, and 5% sodium fluoride (NaF) varnish applied semiannually in arresting dentin caries in young children with high caries risk.

METHODS

Children aged 1-3 years who had at least one active dentin carious lesion were randomly allocated into 2 groups as follows: Group 1 = 38% SDF (Topamine), and Group 2 = 5% NaF varnish (Duraphat). Both agents were applied every 6 months onto the carious surface. Lesion activity was assessed by the visual-tactile examination. Baseline and follow-up examinations were conducted by the same examiner. The children's demographic background, oral health-related habits, and oral hygiene practices, as well as parental satisfaction with children's dental appearance were collected at baseline and the 12-month follow-up.

RESULTS

At baseline, 153 and 149 children were recruited in Group 1 and Group 2, respectively. The mean dmfs scores in Groups 1 and 2 were 8.89 and 9.79, respectively. After 12 months, 87.1% remained in the study. The caries arrest rate of Group 1 (35.7%) was significantly higher than that of Group 2 (20.9%) (p < 0.001). The results of the multilevel logistic regression analysis confirmed that the treatment in Group 1 was more effective in arresting dentin carious lesions than that of Group 2 (OR = 2.04; 95% CI, 1.41-2.96). The presence of plaque on caries lesions, tooth type, tooth surface type, frequency of milk feeding, snack taking, and family income influenced on caries activity. Regardless of the intervention groups, there were no differences in parental satisfaction with on the child's dental appearance before and after receiving the intervention.

CONCLUSION

Based on the 12-month results, 38% SDF is more effective than 5% NaF varnish in arresting dentin carious lesions in young children. SDF has no negative impact on parental satisfaction with the child's dental appearance.

CLINICAL SIGNIFICANCE

To control dentin carious lesions in young children with high caries risk, 38% SDF is more effective than 5% NaF varnish.

Use of Data Analysis Methods in Dental Publications: Is There Evidence of a Methodological Change?

Objectives: To evaluate how data analysis methods in dental studies have changed in recent years. Methods: A total of 400 articles published in 2010 and 2017 in five dental journals, Journal of Dental Research, Caries Research, Community Dentistry and Oral Epidemiology, Journal of Dentistry, and Acta Odontologica Scandinavica, were analyzed. The study characteristics and the reporting of data analysis techniques were systematically identified. Results: The statistical intensity of the dental journals did not change from 2010 to 2017. Dental researchers did not adopt the data mining, machine learning, or Bayesian approaches advocated in the computer-oriented methodological literature. The determination of statistical significance was the most generally used method for conducting research in both 2010 and 2017. Observational study designs were more common in 2017. Insufficient and incomplete descriptions of statistical methods were still a serious problem. Conclusion: The stabilization of statistical intensity in the literature suggests that papers applying highly computationally complex data analysis methods have not meaningfully contributed to dental research or clinical care. Greater rigor is required in reporting the methods in dental research articles, given the current pervasiveness of failure to describe the basic techniques used.

Clustering effects of oral conditions based on clinical and radiographic examinations

OBJECTIVES

The intra-class correlation coefficient (ICC) is a measure of intra-subject clustering effects. A priori estimates of the ICC and the associated design effect (DE) are required for sample size estimation in clustered studies, and should be considered during their analysis, too. We aimed to determine the clustering effects of carious lesions, apical lesions, periodontal bone loss, and periodontal pocketing, assessed in clinical or radiographic examinations.

METHODS

A subsample of patients (n = 175) enrolled in the fifth German Oral Health Study provided data on clinically determined carious teeth (i.e., with untreated carious lesions, WHO method) as well as teeth with periodontal pocketing (i.e., with maximum probing-pocket-depths ≥ 4 mm). A sample of panoramic radiographs (n = 85) from randomly chosen patients, examined from 2010 to 2017 at the Charité dental hospital, provided data on radiographically determined carious teeth (i.e., with lesions extending into dentine or enamel), teeth with apical lesions (determined by dentists via majority vote), and teeth with periodontal bone loss (≥ 20% of root-length). The ICC and its 95% confidence interval (95% CI) were determined.

RESULTS

There were 3839 and 1961 teeth assessed in clinical and radiographic evaluations, respectively. For clinically or radiographically determined carious lesions, the ICC (95% CI) was 0.20 (0.16-0.24) or 0.19 (0.14-0.25), respectively. For clinical pocketing or radiographic bone loss, the ICC was 0.40 (0.35-0.46) or 0.30 (0.24-0.38), respectively. The lowest ICC was found for apical lesions at 0.08 (0.06-0.13).

CONCLUSIONS

The ICC varied between assessment methods and conditions. Clustered trials should account for this during study planning and data analysis.

CLINICAL RELEVANCE

Within the limitations of this study, and considering the risk of selection bias and the limited sample sizes of both datasets, clustering effects were substantial but varied between dental conditions. Studies not accounting for this during planning and analysis may yield misleading estimates if clustering is present.

Accuracy of the lower third molar radiographic imaging to estimate age among Ugandan young people

OBJECTIVE

Dental development is a useful method for age estimation. Although third molar eruption is commonly used to estimate age in Uganda, it is reported to be unreliable because of external influences. The more reliable radiographic techniques have inter-ethnic differences but data from sub-Saharan Africa are limited regarding estimating age in young adults. This study, therefore, aimed at determining the accuracy of Demirjian's classification of the lower third molar, a common dental age estimation method, in estimating key ages in a Ugandan population using Ugandan references. Dental records of 1021 Ugandans aged 10-22 years were assigned to two groups; reference and test. The reference data was retrieved from a database of a previous bigger research project.

RESULTS

The overall sample population comprised of 514/1021 (50.3%) males. The mean age was 15.8 (3.6) years. No significant sex differences in dental age were established in the reference sample (520 records). Accuracy values (area under the curve) at the 12-, 14-, 16- and 18-year cut-offs were between 0.83 and 0.90 using the test sample (501 records). The results suggest that Demirjian's classification of the lower third molars is a useful method for age estimation in the young urban Ugandan population in the 10-22-year age-group.

Deep Learning for the Radiographic Detection of Periodontal Bone Loss

We applied deep convolutional neural networks (CNNs) to detect periodontal bone loss (PBL) on panoramic dental radiographs. We synthesized a set of 2001 image segments from panoramic radiographs. Our reference test was the measured % of PBL. A deep feed-forward CNN was trained and validated via 10-times repeated group shuffling. Model architectures and hyperparameters were tuned using grid search. The final model was a seven-layer deep neural network, parameterized by a total number of 4,299,651 weights. For comparison, six dentists assessed the image segments for PBL. Averaged over 10 validation folds the mean (SD) classification accuracy of the CNN was 0.81 (0.02). Mean (SD) sensitivity and specificity were 0.81 (0.04), 0.81 (0.05), respectively. The mean (SD) accuracy of the dentists was 0.76 (0.06), but the CNN was not statistically significant superior compared to the examiners (p = 0.067/t-test). Mean sensitivity and specificity of the dentists was 0.92 (0.02) and 0.63 (0.14), respectively. A CNN trained on a limited amount of radiographic image segments showed at least similar discrimination ability as dentists for assessing PBL on panoramic radiographs. Dentists’ diagnostic efforts when using radiographs may be reduced by applying machine-learning based technologies.

Deep Learning for the Radiographic Detection of Apical Lesions

INTRODUCTION

We applied deep convolutional neural networks (CNNs) to detect apical lesions (ALs) on panoramic dental radiographs.

METHODS

Based on a synthesized data set of 2001 tooth segments from panoramic radiographs, a custom-made 7-layer deep neural network, parameterized by a total number of 4,299,651 weights, was trained and validated via 10 times repeated group shuffling. Hyperparameters were tuned using a grid search. Our reference test was the majority vote of 6 independent examiners who detected ALs on an ordinal scale (0, no AL; 1, widened periodontal ligament, uncertain AL; 2, clearly detectable lesion, certain AL). Metrics were the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and positive/negative predictive values. Subgroup analysis for tooth types was performed, and different margins of agreement of the reference test were applied (base case: 2; sensitivity analysis: 6).

RESULTS

The mean (standard deviation) tooth level prevalence of both uncertain and certain ALs was 0.16 (0.03) in the base case. The AUC of the CNN was 0.85 (0.04). Sensitivity and specificity were 0.65 (0.12) and 0.87 (0.04,) respectively. The resulting positive predictive value was 0.49 (0.10), and the negative predictive value was 0.93 (0.03). In molars, sensitivity was significantly higher than in other tooth types, whereas specificity was lower. When only certain ALs were assessed, the AUC was 0.89 (0.04). Increasing the margin of agreement to 6 significantly increased the AUC to 0.95 (0.02), mainly because the sensitivity increased to 0.74 (0.19).

CONCLUSIONS

A moderately deep CNN trained on a limited amount of image data showed satisfying discriminatory ability to detect ALs on panoramic radiographs.

Feasibility of assessing training of primary care dental practitioners in endodontics of moderate complexity: mapping process and learning

Objectives

To explore the feasibility of measuring quality of endodontic care provided by general dental practitioners (GDPs), using clinical, radiographic and patient-related outcomes, as well as understanding practitioner views and estimating financial costs.

Methods

Multi-faceted mixed-methods two-part study involving retrospective analysis of the educational component (course assessments, endodontic training blocks and analysis of a sample of teeth treated at the beginning and end of training), and prospective analysis of patients treated by these dentists after completion of training.

Participant

Dentists working in and patients treated in primary dental care in London.

Intervention

Twenty-four-month training in endodontics.

Comparison

Dentists enrolled in the training at different time points.

Outcome

Measuring outcome of endodontic treatment.

Results

Eight dentists (mean 36 years, SD = 8.2 years) participated in training. Subsequently, five of these dentists (mean 34.2 years, SD = 7.08 years) contributed to the prospective study and recruited 135 patients. Thirty-five patients completed all patient-related outcome questionnaires, and of these there were 16 cases with complete clinical and radiographic data (12%) at follow-up (10.1–36.4 months). Preliminary analysis revealed that a minimum of 45 cases of complete data would be required for multivariate analysis, requiring the recruitment of in excess of 375 patients to future studies to account for this level of loss to follow-up.

Conclusions

Findings suggest it is possible to carry out mixed-methods and treatment-related outcome-based research in primary care. Measurement/data capture tools developed were tested and used successfully in measuring the adherence to treatment processes and outcome of endodontic treatment.

Effect of a hyperbaric environment (diving conditions) on adhesive restorations: an in vitro study

Objectives No recent study has addressed the effect of diving conditions (pressure increase) on adhesive restorations. We evaluated the impact of a simulated hyperbaric environment on microleakage of the dentine-composite resin interface. The ultimate aim was to propose recommendations for restorative dentistry for patients who are divers to limit barodontalgia (dental pain caused by pressure variations of the environment) and may lead to dangerous sequelae.Methods We bonded 20 dentine disks by using an adhesive system (Scothbond Universal) to ten intact composite cylinders and ten composite cylinders with porosity (Ceram X mono). For each group, the samples were divided into two subgroups, one submitted to a simulated hyperbaric environment and the other to an ambient environment. All samples were immersed in a silver nitrate solution to evaluate microleakage at the interface after analysis with a camera.Results Dye percolation for groups in the hyperbaric environment was greater than groups in ambient environment. For each subgroup, dye percolation was greater for samples with than without porosity.Conclusions High percolation percentages demonstrate that our simulated hyperbaric condition led to loss of sealing at the dentine-composite resin interface, especially with porous composites.Clinical significance Respect of the protocol and the quality of condensation for adhesive restorations are important in all clinical situations, especially for patients who are divers. A more interventionist approach must be adopted with these patients.

Sealing or infiltrating proximal carious lesions

OBJECTIVES

Micro-invasive treatment (sealing, infiltration) seems more efficacious to arrest early (non-cavitated) proximal carious lesions than non-invasive treatment (NI). Uncertainty remains as to the efficacy of sealing versus infiltration and the robustness of the evidence. We aimed to review and synthesize this evidence using pairwise and network meta-analysis (NMA) and to perform trial sequential analysis (TSA).

SOURCES

Searching three electronic databases (Medline, Embase, Cochrane Central) was complemented by hand searches and cross-referencing.

STUDY SELECTION

Randomized controlled trials comparing micro-invasive strategies against each other, NI or placebo for managing proximal carious lesions were included. The primary outcome was radiographically assessed lesion progression. Pairwise and Bayesian network meta-analyses as well as TSA were used for synthesis.

DATA

Thirteen split-mouth studies (486 participants, mean age 15 years) were included. Mean follow-up was 25 months (min/max 12/36 months). Firm evidence on the superior efficacy of sealing/infiltration over NI (OR; 95% CI: 0.25; 0.18-0.32) was reached. Firm evidence was also reached on the superior efficacy of sealing (OR; 95% CI: 0.29; 0.18-0.46, 7 studies) and infiltration (OR; 95% CI: 0.22; 0.15-0.33, 7 studies) over NI. One study compared infiltration versus sealing and found no significant difference (0.70; 0.34-1.47). Based on Bayesian NMA, infiltration was ranked first in 80% of the simulations (sealing 20%, NI 0%). The surface-under-the-cumulative-ranking (SUCRA) values were 0.90 for infiltration, 0.60 for sealing and 0.00 for NI. We did not detect significant inconsistency (p = 0.89, node-split).

CONCLUSIONS

Sealing or infiltration are likely to be more efficacious for arresting early (non-cavitated) proximal lesions than NI.

CLINICAL SIGNIFICANCE

Practitioners should strive to perform micro-invasive treatment instead of NI for early proximal lesions. The decision between sealing or infiltration should be guided by practical concerns beyond efficacy.

Associations between sleep bruxism and (peri-) implant complications: a prospective cohort study

Objectives/Aims:

To describe the protocol of a prospective cohort study designed to answer the question: ‘Is sleep bruxism a risk factor for (peri-)implant complications?’.

Materials and Methods:

Our study is a single-centre, double-blind, prospective cohort study with a follow-up time of 2 years. Ninety-eight participants fulfilling inclusion criteria (planned treatment with implant-supported fixed suprastructure(s) and age 18 years or older) will be included. Sleep bruxism will be monitored at several time points as masticatory muscle activity during sleep by means of a portable single-channel electromyographic device. Our main outcomes are biological complications (i.e., related to peri-implant bleeding, probing depth, marginal bone height, quality of submucosal biofilm and loss of osseointegration) and technical complications (i.e., suprastructure, abutment, implant body or other).

Results:

The study is currently ongoing, and data are being gathered.

Discussion:

The results of this prospective cohort study will provide important information for clinicians treating bruxing patients with dental implants. Furthermore, it will contribute to the body of evidence related to the behaviour of dental implants and their complications under conditions of high mechanical loadings that result from sleep bruxism activity.

Conclusion:

The protocol of a prospective cohort study designed to investigate possible associations between sleep bruxism and (peri-) implant complications was presented.

Prevalence of dental problems in recreational SCUBA divers: a pilot survey

Objective To determine the prevalence of dental symptoms in recreational scuba divers and describe the distribution of these symptoms on the basis of diver demographics, diving qualifications and dive conditions during the episode of dental pain.Design A survey was designed and distributed through online social media platforms dedicated to scuba diving. A convenience sample of 100 recreational divers was obtained by this method.Main outcome measures The outcome measures of interest were: diver demographics, diving characteristics (level of certification, number of dives completed), occurrence of dental problems during a dive, and details of the episode.Results Forty-one percent of the respondents experienced dental symptoms during a dive. Barodontalgia was the most frequently experienced dental symptom during a dive.Conclusion Within the limits of the small sample size and online method of recruitment, the findings of this study suggest that a high proportion of recreational divers may experience dental symptoms during a dive. It would be meaningful to ensure that dental decay and damaged restorations are addressed before a dive and that the mouthpiece design be evaluated in case of complaints of temporomandibular discomfort during a dive.

Randomized Clinical Trial of 12% and 38% Silver Diamine Fluoride Treatment

This 30-mo randomized clinical trial compared the effectiveness of 2 concentrations (12% or 38%) of silver diamine fluoride (SDF) and 2 periodicity of application (once or twice a year) in arresting cavitated dentin caries in primary teeth. Children aged 3 to 4 y who had at least 1 active cavitated caries lesion were enrolled and randomly allocated into 4 groups for intervention. Group 1 had 12% SDF applied annually (every 12 mo), group 2 had 12% SDF applied semiannually (every 6 mo), group 3 had 38% SDF applied annually, and group 4 had 38% SDF applied semiannually. Clinical examinations were performed semiannually in kindergarten by a single examiner to investigate whether the SDF-treated caries became arrested. A total of 888 children with 4,220 decayed tooth surfaces received SDF application at baseline, and 799 (90.0%) children with 3,790 surfaces (89.8%) were evaluated at the 30-mo examination. The caries arrest rates were 55.2%, 58.6%, 66.9%, and 75.7% for groups 1, 2, 3, and 4, respectively ( P < 0.001). Caries treated with 38% SDF had a higher chance of becoming arrested than those treated with 12% SDF (odds ratio [OR], 1.98; 95% confidence interval [CI], 1.51-2.60, P < 0.001). The interaction between frequency of SDF application and visible plaque index (VPI) score was significant ( P = 0.017). Among those children who received annual SDF application, children with a higher VPI score had a lower chance to have their caries become arrested (OR, 0.59, 95% CI, 0.49-0.72). In conclusion, SDF at a concentration of 38% is more effective than that of 12% in arresting active caries in primary teeth. For children with poor oral hygiene, caries arrest rate of SDF treatment can be increased by increasing the frequency of application from annually to semiannually ( ClinicalTrials.gov NCT02385474).

Clinical studies in restorative dentistry: Design, conduct, analysis

OBJECTIVE

Clinical studies should be one main aspect underlying dentists' decision-making towards dental materials. Study design, conduct, analysis and reporting impact on the usefulness of studies. We discuss problems with current studies and highlight areas where improvement might be possible.

METHODS

Based on systematically and non-systematically collected data, we demonstrate where and why current studies in clinical dentistry deliver less-than-optimal results. Lending from general medicine, we suggest ways forward for clinical dental material science.

RESULTS

Randomized controlled (efficacy) trials remain a major pillar in dental material science, as they reduce selection bias and, if well-designed and conducted, have high internal validity. Given their costs and limited external validity, alternatives like practice-based or pragmatic controlled trials or observational studies can complement the evidence-base. Prior to conduct, researchers should focus on study comparators and setting (answering questions with relevance to clinical dentistry), and pay attention to statistical power, considering the study aim (superiority or non-inferiority trial), the expected event rate, and attrition. Study outcomes should be chosen on the basis of a core outcome set or, if not available, involving patients and other stakeholders. Studies should be registered a priori, and reporting should adhere to standards. Possible clustering should be accounted for during statistical analysis.

SIGNIFICANCE

Many clinical studies in dental material science are underpowered, and of limited validity and usefulness for daily decision-making. Dental researchers should mirror existing efforts in other medical fields in making clinical studies more valid and applicable, thus contributing to better dental care.

Single-visit or multiple-visit root canal treatment: systematic review, meta-analysis and trial sequential analysis

OBJECTIVES

Single-visit root canal treatment has some advantages over conventional multivisit treatment, but might increase the risk of complications. We systematically evaluated the risk of complications after single-visit or multiple-visit root canal treatment using meta-analysis and trial-sequential analysis.

DATA

Controlled trials comparing single-visit versus multiple-visit root canal treatment of permanent teeth were included. Trials needed to assess the risk of long-term complications (pain, infection, new/persisting/increasing periapical lesions ≥1 year after treatment), short-term pain or flare-up (acute exacerbation of initiation or continuation of root canal treatment).

SOURCES

Electronic databases (PubMed, EMBASE, Cochrane Central) were screened, random-effects meta-analyses performed and trial-sequential analysis used to control for risk of random errors. Evidence was graded according to GRADE.

STUDY SELECTION

29 trials (4341 patients) were included, all but 6 showing high risk of bias. Based on 10 trials (1257 teeth), risk of complications was not significantly different in single-visit versus multiple-visit treatment (risk ratio (RR) 1.00 (95% CI 0.75 to 1.35); weak evidence). Based on 20 studies (3008 teeth), risk of pain did not significantly differ between treatments (RR 0.99 (95% CI 0.76 to 1.30); moderate evidence). Risk of flare-up was recorded by 8 studies (1110 teeth) and was significantly higher after single-visit versus multiple-visit treatment (RR 2.13 (95% CI 1.16 to 3.89); very weak evidence). Trial-sequential analysis revealed that firm evidence for benefit, harm or futility was not reached for any of the outcomes.

CONCLUSIONS

There is insufficient evidence to rule out whether important differences between both strategies exist.

CLINICAL SIGNIFICANCE

Dentists can provide root canal treatment in 1 or multiple visits. Given the possibly increased risk of flare-ups, multiple-visit treatment might be preferred for certain teeth (eg, those with periapical lesions).

Arresting Dentine Caries with Different Concentration and Periodicity of Silver Diamine Fluoride

Different regimens of silver diamine fluoride (SDF) have been used to manage early childhood caries. So far, there is limited information regarding the concentrations and frequency of applications for effective caries control in primary teeth. This study aimed to compare the efficacy of 2 commercially available SDF solutions at preprepared concentrations of 38% and 12% when applied annually or biannually over 18 mo in arresting dentine caries in primary teeth. This randomized double-blinded clinical trial recruited kindergarten children aged 3 to 4 y who had at least 1 tooth with dentine caries. The children were randomly allocated to receive 4 treatment protocols: group 1, annual application of 12% SDF; group 2, biannual application of 12% SDF; group 3, annual application of 38% SDF; and group 4, biannual application of 38% SDF. Clinical examinations at 6-mo intervals were conducted to assess whether active carious lesions became arrested. Information on the children's background and oral hygiene habits was collected through a parental questionnaire at baseline and follow-up examinations. A total of 888 children with 4,220 dentine carious tooth surfaces received treatment at baseline. After 18 mo, 831 children (94%) were examined. The caries arrest rates were 50%, 55%, 64%, and 74% for groups 1, 2, 3, and 4, respectively (P < 0.001). Lesions treated with SDF biannual application had a higher chance of becoming arrested compared with those receiving SDF annual application (odds ratio, 1.33; 95% confidence interval, 1.04-1.71; P = 0.025). The interaction between concentration and lesion site was statistically significant (P < 0.001). Compared with 12% SDF, the use of 38% SDF increased a chance of becoming arrested (P < 0.05), except lesions on occlusal surfaces. Based on the 18-mo results, SDF is more effective in arresting dentin caries in the primary teeth of preschool children at 38% concentration than 12% concentration and when applied biannually rather than annually. Knowledge Transfer Statement: The results of this study can be used by clinicians and dental public health professionals when deciding which concentrations and frequency of application of silver diamine fluoride solution should be adopted for arresting dentine caries. With consideration of caries arrest treatment with silver diamine fluoride, which is painless, simple, and low cost, this information could lead to more appropriate therapeutic decisions for caries control in young children or those who lack access to affordable conventional dental care.

Accounting for measurement reliability to improve the quality of inference in dental microhardness research: a worked example

OBJECTIVES

Dental microhardness experiments are influenced by unobserved factors related to the varying tooth characteristics that affect measurement reproducibility. This paper explores the appropriate analytical tools for modeling different sources of unobserved variability to reduce the biases encountered and increase the validity of microhardness studies.

MATERIALS AND METHODS

The enamel microhardness of human third molars was measured by Vickers diamond. The effects of five bleaching agents-10, 16, and 30 % carbamide peroxide, and 25 and 38 % hydrogen peroxide-were examined, as well as the effect of artificial saliva and amorphous calcium phosphate. To account for both between- and within-tooth heterogeneity in evaluating treatment effects, the statistical analysis was performed in the mixed-effects framework, which also included the appropriate weighting procedure to adjust for confounding. The results were compared to those of the standard ANOVA model usually applied.

RESULTS

The weighted mixed-effects model produced the parameter estimates of different magnitude and significance than the standard ANOVA model. The results of the former model were more intuitive, with more precise estimates and better fit.

CONCLUSIONS

Confounding could seriously bias the study outcomes, highlighting the need for more robust statistical procedures in dental research that account for the measurement reliability. The presented framework is more flexible and informative than existing analytical techniques and may improve the quality of inference in dental research.

CLINICAL RELEVANCE

Reported results could be misleading if underlying heterogeneity of microhardness measurements is not taken into account. The confidence in treatment outcomes could be increased by applying the framework presented.