Objective assessment of simulated non-carious cervical lesion by tridimensional digital scanning - An in vitro study.

OBJECTIVE: Clinical assessment of progression of non-carious cervical lesions (NCCLs) is currently based on subjective methods. We hypothesize that 3D digital intraoral scanners (IOS) can provide quantitative outcomes for objective measuring and monitoring of NCCLs. This in vitro study verified the reliability of IOS to monitor dental structure loss of simulated NCCLs, in comparison to a reference bench-top 3D optical profilometer (BTS). METHODS: NCCLs of different severity levels (early, moderate, or severe, n = 150) were simulated in a preceding study. Impressions of the lesions were taken and scanned with both BTS (ProScan; Scantron) and IOS (TRIOS4; 3Shape). Generated 3D images were analyzed for volumetric tooth loss (mm3) by superimposition followed by subtraction analysis. ProForm (Scantron) and WearCompare (Leeds Digital Dentistry) software were used in association to BTS and IOS, respectively. Agreement was assessed using intraclass correlation coefficient (ICC, alpha=0.05) and Bland-Altman plots. RESULTS: ICC (confidence interval at 95 %) between IOS and BTS for all data combined was 0.962 (0.942-0.973), showing excellent reliability. Subset analyses showed that NCCLs with lower volume loss (early- and moderate-stage lesions) resulted in moderate ICCs, whereas severe lesions showed excellent ICC. Bland-Altman plots demonstrated general good agreement, with narrower limits for early stage-lesions. CONCLUSION: IOS data demonstrated good agreement to BTS, when measuring tooth structure loss in simulated NCCLs, with particularly higher ICC in more severe lesions. Considering the accessibility and ease-of-use, IOS showed to be a good alternative for the objective assessment of NCCLs in vitro. CLINICAL SIGNIFICANCE: 3D intraoral scanners' accessibility and objectivity make them potentially valuable tools for assessing and monitoring NCCLs.

Quantifying error introduced by iterative closest point image registration.

OBJECTIVES: The aim of this paper was to quantify the analysis error introduced by iterative closest point (ICP) image registration. We also investigated whether a subsequent subtraction process can reduce process error. METHODS: We tested metrology and two 3D inspection software using calibration standards at 0.39 µm, and 2.64 µm and mathematically perfect defects (softgauges) at 2 and 20 µm, on free form surfaces of increasing complexity and area, both with and without registration. Errors were calculated in percentage relative to the size of the defect being measured. Data were analysed in GraphPad Prism 9, normal and two-way ANOVA with post-hoc Tukey's was applied. Significance was inferred at p < 0.05. RESULTS: Using ICP registration introduced errors from 0 % to 15.63 % of the defect size depending on the surface complexity and size of the defect. Significant differences were observed in analysis measurements between metrology and 3D inspection software and within different 3D inspection software, however, one did not show clear superiority over another. Even in the absence of registration, defects at 0.39 µm, and 2.64 µm produced substantial measurement error (13.39-77.50 % of defect size) when using 3D inspection software. Adding an additional data subtraction process reduced registration error to negligible levels (<1 % independent of surface complexity or area). CONCLUSIONS: Commercial 3D inspection software introduces error during direct measurements below 3 µm. When using an ICP registration, errors over 15 % of the defect size can be introduced regardless of the accuracy of adjacent registration surfaces. Analysis output between software are not consistently repeatable or comparable and do not utilise ISO standards. Subtracting the datasets and analysing the residual difference reduced error to negligible levels. CLINICAL SIGNIFICANCE: This paper quantifies the significant errors and inconsistencies introduced during the registration process even when 3D datasets are true and precise. This may impact on research diagnostics and clinical performance. An additional data processing step of scan subtraction can reduce this error but increases computational complexity.

Single-centre, single-blinded, randomised, parallel group, feasibility study protocol investigating if mandibular advancement device treatment for obstructive sleep apnoea can reduce nocturnal gastro-oesophageal reflux (MAD-Reflux trial).

INTRODUCTION: Just under half of patients with obstructive sleep apnoea (OSA) also have gastro-oesophageal reflux disease (GORD). These conditions appear to be inter-related and continual positive airway pressure (CPAP) therapy, the gold standard treatment for OSA to prevent airway collapse, has been shown to reduce GORD. As the impact of mandibular advancement devices, a second-line therapy for OSA, on GORD has yet to be investigated, a feasibility study is needed prior to a definitive trial. METHODS: This will be a single-centre, single-blinded, tertiary-care based, interdisciplinary, parallel randomised controlled study. Potential OSA participants presenting to the sleep department will be pre-screened for GORD using validated questionnaires, consented and invited to receive simultaneous home sleep and oesophageal pH monitoring. Those with confirmed OSA and GORD (n=44) will be randomly allocated to receive either CPAP (n=22) or MAD therapy (n=22). Following successful titration and 3 weeks customisation period, participants will repeat the simultaneous sleep and oesophageal pH monitoring while wearing the device. The number of patients screened for recruitment, drop-out rates, patient feedback of the study protocol, costs of interventions and clinical information to inform a definitive study design will be investigated. ETHICS AND DISSEMINATION: Health Research Authority approval has been obtained from the Nottingham 2 Research Ethics Committee, ref:22/EM/0157 and the trial has been registered on ISRCTN (https://doi.org/10.1186/ISRCTN16013232). Definitive findings about the feasibility of doing 24 hour pH oesophageal monitoring while doing a home sleep study will be disseminated via clinical and research networks facilitating valuable insights into the simultaneous management of both conditions. TRIAL REGISTRATION NUMBER: ISRCTN Reg No: 16013232.

Managing tooth wear with respect to quality of life: an evidence-based decision on when to intervene.

Patients with more severe forms of tooth wear may require restorative rehabilitation. The decision to commence treatment must be taken carefully and there are a multitude of factors to consider. Alongside the clinical signs and symptoms typically associated with tooth wear, there is also the need to assess the impact of the condition on the patient's oral health-related quality of life. As part of the discussions relating to the attainment of informed consent for the restoration of the worn dentition, not only is it relevant to appropriately appraise the risks, benefits, costs, reasonable alternatives and likely prognosis of the proposed treatments, but to also elaborate on the expected impact of the intervention on the patient's oral health-related quality of life. The aim of this article is to review the evidence relating to the impact of the quality of life with the management of tooth wear, with the introduction of the concept of an evidence-based approach to decision-making when planning care.

Monitoring of erosive tooth wear: what to use and when to use it.

Although we are increasingly recognising the need to assess patients for accelerated rates of tooth wear progression, it is often difficult to do so within a feasible diagnostic window. This paper aims to provide evidence-based timelines which a diagnosing clinician can expect to assess tooth wear progression in study models, clinical indices, clinical photographs and visually with intraoral scans. It also discusses new technologies emerging for the quantitative assessment of tooth wear, timelines for diagnosis, and caveats in the 3D scan registration and analysis process.

Associated risk factors with quantitative erosive tooth wear progression.

OBJECTIVES: The aim of this study was to determine predictors of erosive tooth wear (ETW) progression, using novel primary-care quantitative analysis techniques. METHODS: In a single-centre, prospective, observational cohort longitudinal study, adolescents, aged 11-18 years, underwent a baseline BEWE examination, validated risk factors questionnaire and baseline intraoral scan (IOS, TRIOS 3.0, 3Shape, Copenhagen, Denmark). One year later a repeat scan was taken. Quantitative analysis of wear progression (volume loss) on first permanent molars and upper central incisors was performed using previously published protocols. Multilevel linear regression was used to investigate the associations between baseline predictors and volume loss per mm2. RESULTS: A total of 295 dental surfaces (131 incisors and 164 molars) in 70 patients were analysed for this study. The mean age of participants at baseline was 15.0 years (SD: 0.79), and the average time between scans was 11.8 months (1.61 SD; range 10-13). The mean volume loss per mm2 of dental surfaces was -0.013 mm3 (SD: 0.009). Greater volume loss was observed amongst adolescents with higher baseline BEWE scores and those whose parents had lower education as well as on molar than incisor surfaces. No associations were found with dietary acid intake and intrinsic acid exposure when baseline levels of tooth wear, parental education and other factors were controlled for. CONCLUSIONS: The findings help to characterise groups at greater risk of ETW and would indicate that improved screening and upstream preventative measures should form the basis of a preventative program. CLINICAL SIGNIFICANCE: Intra-orals scans and registration software might improve the ability to diagnose, monitor and prevent the early loss of dental hard tissue.

The threshold of an intra oral scanner to measure lesion depth on natural unpolished teeth.

OBJECTIVES: To investigate the threshold and accuracy of intraoral scanning in measuring freeform human enamel surfaces. METHODS: Software softgauges, ranging between 20 and 160 µm depth, were used to compare four workflow analysis techniques to measure step height on a freeform surface; with or without reference areas and in combination with surface-subtraction to establish which combination produced the most accurate outcome. Having established the optimum combination, 1.5 mm diameter, individual depths ranging from 11 to 81 µm were created separately on 14 unpolished human enamel samples and then scanned with gold standard laboratory optical profilometry (NCLP, TaiCaan Technologies™, XYRIS2000CL, UK) and a clinical intraoral scanner (TrueDefinition™, Midmark Corp., USA). The sequence of surface registration and subtraction determined from the softgauges was used to measure step height on natural human enamel surfaces. Step heights (µm) were compared using two-way ANOVA with post-hoc Bonferroni (p < 0.05) and Bland-Altman analyses. RESULTS: Software differences were significantly reduced from - 29.7 to - 32.5% without, to - 2.4 to - 3.6% with reference areas (p < 0.0001) and the addition of surface-subtraction after registration reduced this further to 0.0 to - 0.3% (p < 0.0001). The intraoral scanner had a depth discrimination threshold of 73 µm on unpolished natural enamel and significant differences (p < 0.05) were observed compared to NCLP below this level. SIGNIFICANCE: The workflow of combining surface-registration and subtraction of surface profiles taken from intraoral scans of freeform unpolished enamel enabled confident measurement of step height above 73 µm. The limits of the scanner is related to data capture and these results provide opportunities for clinical measurement.

Agreement between two common tooth wear indices: Guidance on indications for use.

AIM: To assess the level of agreement between the simplified Tooth Wear Index (S-TWI) and the Basic Erosive Tooth Wear Examination (BEWE). METHODS: Data from 477 adult participants in the Adult Dental Health Survey were analysed. They were examined at home using the S-TWI and the BEWE, in that order. Agreement in the highest score at person, segment and sextant levels was measured with Gwek's agreement coefficient. The impact of the threshold used to define tooth wear (any [mild/moderate/severe] vs no wear, moderate/severe vs no/mild wear and severe vs no/mild/moderate wear) on their agreement was also evaluated. RESULTS: The prevalence of any, moderate/severe and severe tooth wear was 93.1%, 36.1% and 4.6% according to the S-TWI and it was 98.9%, 70.9% and 21.4% according to the BEWE, respectively. The agreement in the highest score between both indices was 0.745 (95% CI: 0.715, 0.775) at person level, 0.771 (95% CI: 0.746, 0.796) at the anterior segment level, 0.795 (95% CI: 0.766-0.824) for the upper anterior sextant and 0.905 (95% CI: 0.895-0.915) for the lower anterior sextant. The agreement between indices was higher for any wear than for severe wear at person, segment and sextant level. However, it was the weakest for moderate/severe wear regardless of the assessment level. CONCLUSION: The agreement between indices was high, especially when focusing on specific parts of the mouth (lower anterior teeth) and when using specific thresholds of tooth wear severity (any wear and severe wear). Agreement was constantly low when using the moderate/severe wear threshold. CLINICAL SIGNIFICANCE: When used as an epidemiological tool, the BEWE may report higher levels of tooth wear than the S-TWI. The BEWE may be a better screening tool whereas the S-TWI may be a better tool to use when determining secondary or tertiary care referral.

Progress and limitations of current surface registration methods when measuring natural enamel wear.

OBJECTIVES: Our ability to detect dental wear on sequential scans is improving. This experiment aimed to determine if widely used surface registration methods were sufficiently accurate to distinguish differences between intervention groups on early wear lesions. METHODS: Baseline measurements were taken on human molar buccal enamel samples (n = 96) with a confocal scanning profilometer (Taicaan, UK). Samples were randomly assigned to subgroups of brushing (30 linear strokes 300 g force) before or after an acid challenge (10 min citric acid 0.3% immersion) for four test dentifrices (medium abrasivity NaF, medium abrasivity SnF2, low abrasivity NaF and a water control). Post-experimental profilometry was repeated. 3D step height was analysed using WearCompare (www.leedsdigitaldentistry.co.uk/wearcompare, UK). Percentage Sa change was calculated using Boddies (Taicaan Technologies, Southampton, UK). Data were analysed in SPSS (IBM, USA). RESULTS: The mean 3D step height (SD) observed when samples were brushed before the erosive challenge was -2.33 µm (3.46) and after was -3.5 µm (5.6). No significant differences were observed between timing of toothbrushing or dentifrice used. The mean % Sa change for the low abrasivity group (water control and low abrasivity NaF) was -10.7% (16.8%) and +28.0% (42.0%) for the medium abrasivity group (medium abrasivity NaF and SnF2). CONCLUSIONS: Detectable wear scars were observed at early stages of wear progression. However standard deviations were high and the experiment was underpowered to detect significant changes. Brushing with a low abrasivity dentifrice or water control produced a smoother surface whereas brushing with a high abrasivity dentifrice produced a rougher surface. CLINICAL SIGNIFICANCE: The methodology currently used to align sequential scans of teeth and measure change is too imprecise to measure early wear on natural enamel surfaces unless a large sample size is used. Further improvements are required before we can fully assess early wear processes on natural teeth using profilometry.

The measurement threshold and limitations of an intra-oral scanner on polished human enamel.

OBJECTIVE: To investigate the measurement threshold of an intra-oral scanner (IOS) on polished human enamel. METHODS: The optical performance of an IOS was compared to a gold-standard non contacting laser profilometer (NCLP), on a painted microscope slide, compared to increasing particle size of silicon-carbide papers (21.8-269.0 µm) and separately on polished human enamel with increasing step-heights. The enamel samples were randomised (n = 80) and scanned using the IOS and NCLP at increasing step-height depths (µm) (1.87-86.46 µm) and quantified according to ISO:5436-1. The measurement threshold of the IOS was determined using a custom designed automated lesion localisation algorithm, corroborated by Gaussian skewness (Ssk) and kurtosis (Sku) analysis, to assess the minimum step-height measured on each enamel sample. RESULTS: The NCLP showed statistically increased Sq surface roughness for all silicon carbide particle sizes compared to the microscope slide, whereas, the IOS Sq roughness discriminated silicon-carbide particles above 68.0 µm compared to the glass slide (p ≤ 0.02). On polished enamel, the automated minimum detectable step-height measurable on each sample was 44 µm. No statistically significantly different step-height enamel lesion measurements were observed between NCLP and IOS above this threshold (p > 0.05). SIGNIFICANCE: This study revealed the fundamental optical metrological parameters for the IOS, was step-heights above 44 µm and this reflects the data acquisition of the system. These results highlight the limitations of IOS used in this study, mandating further research to optimise the performance of other IOS systems, for measuring wear of materials or tooth wear on human unpolished natural enamel surfaces.

Asthma, long-term asthma control medication and tooth wear in American adolescents and young adults.

OBJECTIVE: This study explored the associations of asthma and long-term asthma control medication with tooth wear among American adolescents and young adults. METHODS: Data from 2186 participants of the National Health and Nutrition Examination Survey (NHANES) were used. Asthma and prescribed long-term medication were collected through questionnaires. The number of surfaces with tooth wear was determined during clinical examinations. Associations were tested in Hurdle regression models adjusting for confounders. RESULTS: The prevalence of tooth wear was 58%, with an average of 6.1 (SD: 4.0) surfaces affected among those with the condition. The prevalence of asthma was 10.3%, with 2.9% of participants using long-term medication for asthma control. In the adjusted regression model, asthma was not associated with tooth wear. However, long-term control medication was associated with greater odds of having tooth wear (odds ratio: 3.33; 95%CI: 1.24-8.97), but it was not associated with the number of surfaces with tooth wear among those with the condition (rate ratio: 1.01; 95% CI: 0.58-1.75). CONCLUSION: This cross-sectional analysis of national data shows that taking long-term asthma medication was positively associated with having tooth wear.

The interrelationship between xerogenic medication use, subjective oral dryness and tooth wear.

OBJECTIVE: To investigate the association between xerogenic medication use and tooth wear among American adults and whether this association can be explained by subjective oral dryness. METHODS: We used data from 3578 adults who participated in the National Health and Nutritional Examination Survey (NHANES). Tooth wear was clinically determined using the modified Tooth Wear Index. Information on xerogenic medication use, subjective oral dryness (amount of saliva in mouth and feeling the mouth dry when eating) and potential confounders (sociodemographic factors, dental insurance coverage, gastroesophageal reflux disease medication use and soft drinks intake) were self-reported. The associations among xerogenic medication use, subjective oral dryness and tooth wear were assessed in regression models adjusting for confounders. RESULTS: Adults taking xerogenic medication had greater odds of reporting too little amount of saliva and feeling the mouth dry when eating. In addition, participants taking one and multiple (two or more) xerogenic medications had, respectively, 1.53 (95 % CI: 1.01-2.32) and 1.44 (95 % CI: 0.62-3.33) greater odds of having tooth wear than those taking no xerogenic medications. In a regression model including all explanatory variables, the association of xerogenic medication use with tooth wear was fully attenuated whereas subjective oral dryness (amount of saliva in mouth but not feeling the mouth dry when eating) remained positively associated with prevalence of tooth wear. Similar findings were obtained with long-term use of xerogenic medication (in the past month and for three or more years). CONCLUSION: Current (last month) use of xerogenic medication was associated with the presence of tooth wear. This association was accounted for by subjective indicators of oral dryness. CLINICAL SIGNIFICANCE: Dentists should be familiar with the possible connection between patient's medical prescription and tooth wear. Changing prescriptions to non-xerogenic alternatives, whenever possible, could improve patients' oral condition. The findings also suggest that patients may recognise, through the perception of dry mouth, when medication is placing them at risk.

Tooth Wear: Best Evidence Consensus Statement.

PURPOSE: The purpose of this Best Evidence Consensus Statement was to evaluate the impact of wear on teeth. MATERIALS AND METHODS: A search updated last on the 07th October 2020 using the terms tooth wear, dental erosion, dental abrasion or dental attrition yielded 11,694 results. Limiting the search to clinical trials, cross-sectional investigations, randomized controlled trials, reviews, systematic reviews and meta-analysis yielded 1,769 results. Mechanistic in vitro studies were also added to the list of abstracts supplying additional information of the impact of wear on teeth. All abstracts were reviewed by two authors. Those relating to the focus question formed the evidence base which was used to formulate the response. RESULTS: From the search results, 212 articles were related to the research question and 60 were included in this paper. Although tooth wear prevalence is over 30% of the population in early adulthood and increases as individual's age, the impact on the dentition is poorly investigated in longitudinal clinical studies. Wear on teeth can result in alterations in shape and potentially dentine hypersensitivity depending on the etiology. However, the process is slow and pulpal death is rare. The impact that tooth wear has on the patient depends on patient characteristics to a greater extent than the severity of wear. CONCLUSIONS: Tooth wear is a common condition and part of the ageing process. Erosive tooth wear is a term which acknowledges that acids are normally linked to progression, but mechanical actions of attrition and abrasion will cause visible damage. The changes to the shape of teeth on the macro and micro levels are used to investigate the progression, prevention, etiology, and management. The biological impact of wear on teeth is relatively innocuous and management is often a patient driven process. This article is protected by copyright. All rights reserved.

Influence of Scanner Precision and Analysis Software in Quantifying Three-Dimensional Intraoral Changes: Two-Factor Factorial Experimental Design.

BACKGROUND: Three-dimensional scans are increasingly used to quantify biological topographical changes and clinical health outcomes. Traditionally, the use of 3D scans has been limited to specialized centers owing to the high cost of the scanning equipment and the necessity for complex analysis software. Technological advances have made cheaper, more accessible methods of data capture and analysis available in the field of dentistry, potentially facilitating a primary care system to quantify disease progression. However, this system has yet to be compared with previous high-precision methods in university hospital settings. OBJECTIVE: The aim of this study was to compare a dental primary care method of data capture (intraoral scanner) with a precision hospital-based method (laser profilometer) in addition to comparing open source and commercial software available for data analysis. METHODS: Longitudinal dental wear data from 30 patients were analyzed using a two-factor factorial experimental design. Bimaxillary intraoral digital scans (TrueDefinition, 3M, UK) and conventional silicone impressions, poured in type-4 dental stone, were made at both baseline and follow-up appointments (mean 36 months, SD 10.9). Stone models were scanned using precision laser profilometry (Taicaan, Southampton, UK). Three-dimensional changes in both forms of digital scans of the first molars (n=76) were quantitatively analyzed using the engineering software Geomagic Control (3D Systems, Germany) and freeware WearCompare (Leeds Digital Dentistry, UK). Volume change (mm3) was the primary measurement outcome. The maximum point loss (µm) and the average profile loss (µm) were also recorded. Data were paired and skewed, and were therefore compared using Wilcoxon signed-rank tests with Bonferroni correction. RESULTS: The median (IQR) volume change for Geomagic using profilometry and using the intraoral scan was -0.37 mm3 (-3.75-2.30) and +0.51 mm3 (-2.17-4.26), respectively (P<.001). Using WearCompare, the median (IQR) volume change for profilometry and intraoral scanning was -1.21 mm3 (-3.48-0.56) and -0.39 mm3 (-3.96-2.76), respectively (P=.04). WearCompare detected significantly greater volume loss than Geomagic regardless of scanner type. No differences were observed between groups with respect to the maximum point loss or average profile loss. CONCLUSIONS: As expected, the method of data capture, software used, and measurement metric all significantly influenced the measurement outcome. However, when appropriate analysis was used, the primary care system was able to quantify the degree of change and can be recommended depending on the accuracy needed to diagnose a condition. Lower-resolution scanners may underestimate complex changes when measuring at the micron level.

Quantitative tooth wear analysis of index teeth compared to complete dentition.

OBJECTIVES: Recent software advancements have facilitated quantification of erosive tooth wear progression using intraoral scans. This paper investigated if wear on commonly affected surfaces (central incisors and first molars) was representative of wear on the full arch. METHODS: Bimaxillary digital intraoral scans (True Definition, 3 M, USA) of patients (n = 30) from the monitoring arm of the Radboud Tooth Wear Project, were taken at baseline and at 3 years (+/-10months). The occlusal/incisal surface of each tooth (excluding 3rd molars) was analysed for volume change and volume change per mm of analysed surface area in WearCompare (www.leedsdigitaldentistry.com/Wearcompare) following previously published protocols. Data were normal, descriptives and multi-level linear regression analysis was performed in Stata v15.1 taking patient level and surface type data into account. RESULTS: Data from 556 surfaces in 29 patients were included in analysis. Per patient, mean volume loss (95 % CI) was -0.91mm3(-1.28,-0.53) on all surfaces, -1.85mm3(-2.83,-0.86) on index surfaces, -2.53mm3(-3.91,-1.15) on molar surfaces and -0.83 mm3(-1.34,-0.31) on upper central incisal surfaces. Statistical differences were observed between analysing all surfaces and index teeth(p = 0.002) in addition to molar surfaces(p < 0.0001). Mean volume loss per mm2 of surface analysed was -0.024 mm3 (-0.031,-0.017), -0.028mm3 (-0.041,-0.014), -0.030mm3 (-0.046,-0.013) and -0.025mm3 (-0.041,-0.010) for all surfaces, index surfaces, first molar surfaces and central incisor surfaces respectively with no statistical differences between groups. CONCLUSIONS: Wear on upper central incisors was not statistically different to full arch wear analysis. If the surface area is standardised, wear on both index surfaces are statistically similar to wear on the full arch. CLINICAL SIGNIFICANCE: These results suggest that analysing rates of wear on index teeth can be a resource-saving substitute for analysing rates of wear on the entire dentition, provided the surface area is standardised. If whole surfaces are analysed, the molar surfaces will show greater rates of wear.

Recommendations and guidelines for dentists using the basic erosive wear examination index (BEWE).

This paper explains how to screen tooth wear in general practice using the Basic Erosive Wear Examination (BEWE) index. It explains how stakeholders in the UK acknowledged the convenience of the BEWE and that it could be recorded at the same time as the Basic Periodontal Examination (BPE). The article contains examples of anterior and posterior tooth wear for each BEWE score to help dentists in their evaluation.

Quantifying increased rates of erosive tooth wear progression in the early permanent dentition.

OBJECTIVES: To investigate if quantitative analysis of intraoral scans of study models can identify erosive tooth wear progression. METHODS: Data were collected from a retrospective longitudinal study, using pre-and post-orthodontic treatment casts of 11-13 year olds, recorded at two consecutive appointments 29 months apart. Casts were digitised with intra-oral scanner TRIOS™ (3Shape, Copenhagen, Denmark) and first molar scan pairs used for analysis. Occlusal surfaces of each molar pair were visually assessed using the BEWE index as having no BEWE progression (n = 42) or BEWE progression (n = 54). Scan pairs were aligned and analysed for volume loss, maximum profile loss and mean profile loss in WearCompare (Leedsdigitaldentistry.com/wearcompare) using previously published protocols. Data were analysed in SPSS and not normal. Mann-Whitney U test with a Bonferroni correction assessed differences between progression groups. Receiver-operating-characteristic (ROC) curves were used to identify the sensitivity and specificity of quantified wear progression rates at determining visual wear progression. RESULTS: Surfaces with visible progression demonstrated a median volume loss of -2.19 mm3 (IQR-3.65, -0.91) compared to a median volume loss of -0.37 mm3 (IQR -1.02, 0.16) in the no visible progression group (p < 0.001). Mean profile loss was -75.2 µm (IQR-93.9, -61.0) and 63.2 µm (IQR -82.5, -49.7) for the progression and no-progression groups respectively (p = 0.018). Volume loss of -1.22mm3 represented a 79 % sensitivity and 61 % specificity. The estimated area under the curve for volume loss was 0.80 (95 %CI 0.71-0.89, p < 0.001). CONCLUSIONS: This is the first study to propose rates of high wear progression in adolescents. Limited sensitivity and specificity confirms that quantitative analysis is an adjunct tool to be used alongside history taking and clinical judgement. CLINICAL SIGNIFICANCE: The rapid advancement of digital technologies may result in improved diagnosis in erosive tooth wear (ETW). Intra-oral scans and registration software are a promising adjunct for monitoring ETW progression in clinical practice.

Differences in the Natural Enamel Surface and Acquired Enamel Pellicle following Exposure to Citric or Hydrochloric Acid.

OBJECTIVES: The aim of this study was to investigate variations in the interaction between enamel, that is, the acquired enamel pellicle (AEP) and citric or hydrochloric acid. MATERIALS AND METHODS: A 24-h AEP was formed on natural enamel specimens (n = 40) from pooled whole mouth human saliva. Samples were randomly allocated to citric (0.3%, pH 3.2) or hydrochloric (HCl) acid (0.01 M, pH 2.38) exposure for 30 or 300 s. The total protein concentration (TPC), and phosphorous and calcium concentrations of the pellicle were determined before and after acid exposure, and again after re-immersion in saliva. Surface roughness and tandem scanning confocal microscopy imaging were used to assess enamel changes. RESULTS: After 300 s of citric acid exposure, the mean ± SD TPC reduced from 5.1 ± 1.1 to 3.5 ± 1.1 mg/mL (p < 0.05). In contrast, after 300 s of HCl exposure, the mean TPC did not reduce significantly from baseline (6.6 ± 1.1 to 5.7 ± 0.7 mg/mL) but was significantly reduced in the reformed pellicle to 4.9 ± 1.2 mg/mL (p < 0.001). This reduction occurred after significant release of calcium and phosphorous from the enamel surface (p < 0.001). Thirty seconds of exposure to either acid had no obvious effect on the AEP. The surface roughness of the enamel decreased after acid exposure but no differences between groups was observed. CONCLUSIONS: These findings indicate that citric acid interacted with proteins in the AEP upon contact, offering enamel protection. In contrast, HCl appeared to bypass the pellicle, and reduced protein was observed only after changes in the enamel chemical composition.

Obesity and tooth wear among American adults: the role of sugar-sweetened acidic drinks.

BACKGROUND: To explore the association between obesity and tooth wear among American adults and the role of sugar-sweetened acidic drinks consumption in explaining that association. METHODS: We analyzed data from 3541 adult participants in the National Health and Nutrition Examination Survey. Obesity was determined using the body mass index and tooth wear was assessed using the modified tooth wear index. Daily intake of four categories of drinks was estimated as the average (drinks/day) of two consecutive 24-h dietary recalls. The association between obesity and number of surfaces with moderate-to-severe tooth wear was assessed in hurdle models adjusting for sociodemographic factors, acid reflux medication, and dental insurance. RESULTS: Overweight and obese adults had more surfaces with moderate-to-severe tooth wear than those with normal body size, after adjusting for confounders. The consumption of sugar-sweetened acidic drinks explained part, but not all the above association. More specifically, the estimate for obesity was fully attenuated, whereas the estimate for overweight was slightly attenuated but remained significant. CONCLUSION: Obesity was positively associated with tooth wear in American adults. This association was only partially accounted for by the consumption of sugar-sweetened acidic drinks, a common risk factor for both conditions. PRACTICAL IMPLICATIONS: Dentists must be aware of the health consequences of sugar-sweetened acidic drinks and advocate for reduction in consumption and/or substitution with healthier alternatives.

Non-carious cervical lesions - can terminology influence our clinical assessment?

Introduction Abfraction is a theoretical term used that has been classified as a type of non-carious cervical lesion (NCCL) and characterised by the microstructural loss of hard dental tissue in areas of high stress concentration. There is a lack of consensus among researchers and clinicians as to whether occlusal loading, particularly interferences or eccentric loading, generates sufficient tensile stress to be an aetiological factor in the loss of hard dental tissue at the cemento-enamel junction (CEJ).Aim This narrative review article assesses the evidence behind the theory of abfraction.Results It is difficult to control all influencing factors in a clinical trial making it challenging to generate sufficient evidence to conclusively support the theory of abfraction. There is limited evidence occlusal forces are an aetiological agent in non-carious cervical lesion development. However, if occlusal forces do play a role, the term non-carious cervical lesion is more reflective of the limited role it may play and a multifactorial aetiology.Conclusion The term 'abfraction lesion' remains misleading and could be removed from our diagnostic vocabulary.