Tooth wear and wear investigations in dentistry

Evaluating the Influence of Acute and Chronic Orofacial Pains on the Overall Comprehensive Quality of Life

Background Orofacial discomfort refers to various disorders that affect the mouth, jaws, and face. These conditions may substantially influence a person's quality of life (QoL). This kind of pain may be categorised into two primary classifications: acute and chronic. Acute orofacial pain (OFP) usually occurs suddenly and lasts for a short period. It is commonly caused by specific factors such as dental treatments, traumas, or infections. Hence, this study aimed to assess the influence of acute and chronic orofacial discomfort on the overall QoL. Methodology This research used a convenience sample to gather data from the five groups. It was conducted as a cross-sectional study. Four categories of OFP syndromes were utilised: temporomandibular disorders (TMDs), atypical dental pain (ADP), trigeminal neuralgia (TN), and persistent dentoalveolar pain disorder (PDAP). In addition, a control group consisting of individuals who did not experience any discomfort was also included in the study. Participants received a standardised explanation of the questionnaires utilised, and in most instances, they completed them at the clinic under the supervision of one of the investigators. Results The correlations between each version of the Oral Health Impact Profile (OHIP) were statistically significant (p < 0.001), with correlation values ranging from 0.92 to 0.97. When comparing the occurrence of OHIP items across the four pain types, we identified 18 variations that exceeded the 35% prevalence threshold we established for identifying important items that frequently occur out of the 315 comparisons. The question "Have you had a painful aching in your mouth?" showed a low frequency in patients with TN, TMD, and ADP but a significant prevalence in patients with PDAP (90%). This difference in prevalence across pain types was the biggest seen. The question that seemed to distinguish between the pain categories most effectively was "Have you experienced a toothache?" This question had a high occurrence in PDAP (65%) and ADP (60%), perhaps allowing for differentiating these two diseases from TN and TMD. The highest prevalence differences, over 30%, were most often seen when PDAP was included as one of the disorders being compared. ADP had the fewest variances, over 30%, occurring just seven times. Conclusion Both acute and chronic OFPs have a major negative influence on QoL, but they affect it differently and to differing extents. Injury-related acute pain obviously poses rapid and severe restrictions on physical function and causes temporary psychological distress and temporary social exclusion. On the other hand, chronic pain for the patient always implies being locked in a physical world that does not allow him or her to bypass physical limitations, psychological disorders remain constant, and isolation from other people persists for life.

An evaluation of dental paste-like bulk-fill composite wear using intra-oral scanner

This study evaluates the wear resistance of dental paste-like bulk-fill composites compared to conventional paste-like composite resins using an intraoral scanner and 3-D analyzing software. Six different dental composite materials, including five bulk-fill composites and one conventional composite, were tested alongside natural human enamel as a control group. A computer-controlled chewing simulator for wear testing. A one-way ANOVA test was used to identify any significant differences between the means of the tested dental composite materials α=0.05. The results showed variability among bulk-fill composites, with some demonstrating wear resistance similar to conventional composites (p<0.05). Human enamel displayed the lowest wear values, but some bulk-fill composites matched this resistance(p>0.05). Significant variability was observed among bulk-fill composites but the results were comparable to those of conventional composites. The enamel control group demonstrated the lowest wear values, with some bulk-fill composites showing similar wear resistance. This study provides valuable information about the wear resistance of contemporary bulk-fill composite materials, commonly used in current clinical practice, contributing to enhancing clinical procedures.

Tooth Wear Evaluation System 2.0-Evaluation of diagnostic reliability in the assessment of signs and symptoms for tooth wear by non-experts

BACKGROUND

Tooth wear is a multifactorial condition that manifests through various signs and symptoms. These individual signs and symptoms were described in multiple studies, leading to the inclusion in TWES 2.0 (Tooth Wear Evaluation System 2.0) and the forthcoming DC-TW (Diagnostic Criteria for Tooth Wear). However, a study evaluating their reliability has yet to be conducted.

OBJECTIVE

The aim of the study was to examine the reliability in the assessment of 6 signs of pathological tooth wear and 18 clinical signs and symptoms determining aetiology, all of which are included in the TWES 2.0/DC-TW.

METHODS

48 dental students (operators) evaluated patient cases from a patient pool of 14 patients on dental casts and high-resolution intraoral photographs. The agreement between all operators for each sign and symptom was calculated based on ICC (Intraclass Correlation Coefficients). Additionally, the agreement of each operator's evaluation with a predefined sample solution was calculated based on Cohen's kappa.

RESULTS

Inter-user agreement ranged from near perfect (0.91) to poor (0.02) for the various pathology signs or aetiology symptoms of tooth wear (mean 0.32). The agreements of the operator's ratings compared to the sample solution resulted in Cohen's kappa from 0.18 to 1 (mean 0.59) for the pathology signs and ranged from 0.02 to 0.51 for the aetiology signs (mean 0.38).

CONCLUSIONS

The reliability of the signs and symptoms examined and the ability of individual investigators to correctly identify and assign signs and symptoms varied widely. The current assessment tools for the qualification of tooth wear need further refinement, and examiners need intensive training in tooth wear assessment.

Reliability of digital repeated-scan superimposition and single-scan techniques for wear volume loss assessment on flat surfaces

OBJECTIVES

Evidence on the reliability of digital techniques for wear volume assessment using three-dimensional (3D) scan datasets is scarce. This study evaluated the reliability of a repeated-scan superimposition technique and two single-scan techniques in assessing wear volume loss on flat surfaces of 3D-printed resin specimens.

METHODS

Cuboid-shaped (15×10×10 mm) resin specimens were 3D-printed (n = 14) and scanned before and after 200,000 cycles of masticatory simulation. For the repeated-scan superimposition technique, digital 3D models of specimens before and after masticatory simulation were superimposed, and the volume loss was determined. The first single-scan technique utilized a computer-aided design freeware program, while the second one employed a 3D-metrology software program. In the freeware program, the worn area of 3D objects was edited directly to obtain a flat surface. In the 3D-metrology software program, the worn area was deleted first and then filled to the flat surface. The volume differences before and after editing were calculated in each software program. Agreement between the three measurement techniques was determined through intraclass correlation coefficients (ICCs). One-way analysis of variance was performed to compare the wear volume loss assessed by the three techniques (α = 0.05).

RESULTS

High inter-technique reliability was observed between the three assessment techniques (ICC = 0.998, p < .001). On pair-wise comparisons of two of the three techniques, all pairs showed high consistency (ICC ≥ 0.999, p < .001). No significant difference was found in the wear volume loss assessed using the three techniques (p = .996).

CONCLUSIONS

Digital repeated-scan superimposition and two single-scan techniques demonstrated high reliability in assessing wear volume loss on flat surfaces.

CLINICAL SIGNIFICANCE

The repeated-scan superimposition technique can be effectively utilized to assess wear volume loss of anatomically shaped specimens and flat surfaces. This study indicates that the single-scan techniques may serve as a suitable alternative to the repeated-scan superimposition technique when evaluating wear volume loss of flat surfaces.

Trueness of 4 sectional-cast digital methods for transferring the interocclusal relationship in complete mouth rehabilitation

STATEMENT OF PROBLEM

An accurate digital workflow for transferring the interocclusal relationship from complete arch diagnostic interim restorations to complete arch tooth preparations is essential in complete mouth rehabilitation. However, research on the accuracy of digital cross-mounting methods is lacking.

PURPOSE

The purpose of this in vitro study was to compare the trueness of 4 sectional-cast digital cross-mounting methods in transferring the interocclusal relationship for complete mouth rehabilitation.

MATERIAL AND METHODS

Maxillary and mandibular anatomic typodonts were used to build complete arch tooth preparations and diagnostic interim restorations for complete mouth rehabilitation in vitro. Four sectional casts were designed: an anterior cast (AR), a posterior cast (PO), a unilateral cast (UL), and a tripod cast (TR). Both extraoral scanning (EOS) and intraoral scanning (IOS) were used to obtain intermediate digital sectional casts, which were cross-registered with diagnostic interim restorations and definitive casts to transfer the interocclusal relationship. Trueness was determined by assessing tooth distance deviation and mandibular 3-dimensional (3D) deviation. Differences among the 4 sectional-cast methods were analyzed with the Kruskal-Wallis test, and differences between the 2 scanning methods were analyzed with the Mann-Whitney U test (α=.05).

RESULTS

Significant differences in the trueness of interocclusal relationship transfer were observed among the 4 sectional-cast methods (P<.05). Regarding tooth overall distance deviation, TR-EOS found no statistically significant difference compared with PO-EOS (P>.05), but TR-EOS had half the overall distance deviation of PO-EOS. Both TR-EOS and PO-EOS had smaller deviations than the AR-EOS and UL-EOS groups (P<.05). TR-IOS had a smaller distance deviation than the AR-IOS, PO-IOS, and UL-IOS groups (P<.05). The overall distance deviation of EOS was significantly smaller than that of IOS in the TR and PO groups (P<.05). Regarding mandibular 3D deviation, TR-EOS found no statistically significant difference but had half the root mean square (RMS) of 3D deviation compared with the PO-EOS groups (P>.05). Both TR-EOS and PO-EOS groups had a smaller RMS than the AR-EOS and groups (P<.05). The TR-IOS group had a smaller RMS than the AR-IOS, PO-IOS, and UL-IOS groups (P<.05). The 3D deviation of EOS was significantly smaller than that of IOS in the PO group (P<.05).

CONCLUSIONS

Both EOS and IOS with the tripod sectional-cast digital method accurately transferred the interocclusal relationship for complete mouth rehabilitation.

Chewing Ability and the Quality of Life: A Cross-Sectional Study to Assess the Relationship Between Tooth Wear and Oral Health

INTRODUCTION

It is important to understand how a very common prevalent condition of tooth wear (TW) impacts a person's day-to-day oral health. An emerging concept of measuring the parameter of oral health-related quality of life (OHRQoL), which evidently impacts the daily living of a person, makes it practical to examine the correlation between TW and OHRQoL. For measuring the OHRQoL, we can apply various methods, and the most effective is the use of the Oral Health Impact Profile (OHIP) questionnaire. Accordingly, the aim of this study was to assess the correlation between TW and the OHRQoL among adult patients attending a dental college and hospital.

METHODS

A cross-sectional research was performed on patients who visited the outpatient department of Teerthanker Mahaveer Dental College and Research Centre, Moradabad, India. Initially, the sociodemographic details of patients, including their oral hygiene and dietary habits, were recorded. This step was followed by the assessment of TW using the Smith and Knight TW index. Then, the translated and validated version of the OHIP questionnaire was filled up, in which the patients were asked to rate each question on a Likert scale, with five points ranging from 0 to 4, where 0 = never, 1 = hardly ever, 2 = occasionally, 3 = fairly often, and 4 = very often.

RESULTS

Based on a clinical examination on 630 subjects and the OHIP questionnaire responses from the participants, a significantly remarkable association (p ≤ 0.05) was found using a chi-square test between TW and the OHRQoL. In particular, TW was linked to other sociodemographic data and various lifestyle, dietary, and drinking habits. Along with the OHRQoL, TW also showed a positive correlation with gender. Using the chi-square test, a statistically significant association between age and TW was observed, with p-value = 0.004. Meanwhile, the place of residence did not show any association with TW. Educational qualifications of patients, visits to dental clinics, and reasons for dental visits showed very significant association with TW. Oral hygiene aids, materials used, frequency of brushing, and brushing technique did not have any association with TW as per the results obtained. A highly significant association was found between consumption of fruit drinks, citric drinks, and beverages and TW in the adult patients. Among all the domains of the OHIP questionnaire, the physical pain domain was the most affected, followed by the physical disability domain.

CONCLUSION

We conclude that TW has a direct association and positive correlation with the OHRQoL. As TW was increasing, so were the OHIP values, which indicated a lesser OHRQoL. The study also presents information on how to maintain a regular and healthy dietary lifestyle and oral hygiene to combat the impacts of TW.

Fatigue and wear of human tooth enamel: A review

Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatigue and wear properties of enamel. The purpose of this review is to provide an overview of our understanding of the fatigue and wear mechanisms of human enamel and how they relate to in vivo observations of tooth damage in the complex oral environment. A key finding of this review is that fatigue and wear processes are closely related. For example, the presence of abrasive wear particles significantly lowers the forces needed to initiate contact fatigue cracking while subsurface fatigue crack propagation drives key delamination wear mechanisms during attrition or attrition-corrosion of enamel. Furthermore, this review seeks to bring a materials science and mechanical engineering perspective to fatigue and wear phenomena. In this regard, we see developing a mechanistic description of fatigue and wear, and understanding the interconnectivity of the processes, as essential for successfully modelling enamel fatigue and wear damage and developing strategies and treatments to improve the longevity of our natural teeth. Furthermore, we anticipate that this review will stimulate ideas for extending the lifetime of the natural tooth structure and will help highlight where our understanding is too limited and where additional research into fatigue and wear of human tooth enamel is warranted.

3D Surface Deviation Wear Analysis of Veneered PEEK Crowns and Its Correlation with Optical Digital Profilometry

PURPOSE

To verify whether 3D surface deviation analysis software can detect the surface changes of composite veneered polyetheretherketone posterior crowns following wear simulation compared to optical digital profilometry.

MATERIALS AND METHODS

Twenty dental crowns, fabricated from CAD-CAM polyetheretherketone (PEEK) and veneered with high impact polymer composite (HIPC), were subjected to wear test (50N, 5/55°C; 120,000 chewing cycles). Optical digital profilometry and 3D surface deviation using Geomagic design X software was used before and after the wear test to measure volumetric wear loss (mm³ ). The data were statistically analyzed with Wilcoxon signed-rank test to compare the two methodologies. The significance level was set at p ≤ 0.05.

RESULTS

There was no statistically significant difference between the two assessment methods (p-value = 0.075, Effect size = 0.854). Regarding the optical digital profilometry analysis, HIPC veneered PEEK crowns showed 0.01686 (0.018-0.02155) mm³ as a median volumetric wear loss value. While the crowns analyzed by 3D surface deviation showed -0.0398 (-0.0913 to -0.0042) mm³ as a median volumetric loss value (p-value = 0.075, Effect size = 0.854). In addition, there was no statistically significant correlation between wear measurements by optical digital profilometry and 3D surface deviation analyses (ρ = -0.177, p-value = 0.685).

CONCLUSIONS

There was no significant difference or correlation between optical digital profilometry and 3D surface deviation analyses for volumetric wear loss of veneered PEEK crowns.

Digital Volumetric Analysis of CAD/CAM Polymeric Materials after Tooth Brushing

The objective of the study was to evaluate the volumetric wear of four composite materials for CAD/CAM (computer-aided design/computer-aided manufacturing) systems. The materials evaluated were: Cerasmart (CER), Shofu Block HC (SBH), Tetric CAD (TEC) and Brava (BRA). All the samples (n = 40) were subjected to simulated brushing (100,000 cycles). Wear was evaluated by superimposing pre-and post-brushing scans obtained with an intraoral optical scanner (CEREC Primescan; Dentsply Sirona, Germany), which were subsequently imported into the OraCheck software 5.0 (Dentsply Sirona, Germany). The data were analyzed by ANOVA test and Tukey’s HSD test was used for multiple comparisons. Cerasmart showed the least wear after brushing. All the tested materials exhibited mass loss.

Wear Behavior between Aesthetic Restorative Materials and Bovine Tooth Enamel

Tooth enamel wear occurs because of daily mastication and occlusion. This study investigated the wear behavior of bovine teeth against aesthetic restorative materials in vitro. Abrader specimens were fabricated using four tooth-colored restorative materials (zirconia, lithium disilicate glass ceramic, dental porcelain, and resin composite), with bovine tooth enamel as a control. Flattened bovine tooth enamel was used as the substrate specimen. These materials were characterized by Vickers hardness tests and surface roughness measurements. Two-body wear tests between the abrader and substrate specimens were performed, and the worn topographies were evaluated using a contour-measuring instrument and 3D laser microscope. The restorative materials and bovine tooth enamel had similar surface roughness but different hardness and wear behaviors. Bovine teeth showed the largest wear in tooth–tooth contact as the abrader and substrate specimens. Compared to bovine teeth, zirconia, lithium disilicate glass ceramic, and dental porcelain showed greater hardness and less wear on their surfaces, and less substrate wear of the opposite tooth enamel. The lowest hardness resin composite showed intermediate wear on its surface, resulting in the lowest substrate wear. Accordingly, dentists should pay attention to the selection of restorative materials to reconstruct their morphologies owing to different wear behaviors.

Wear Resistance, Color Stability and Displacement Resistance of Milled PEEK Crowns Compared to Zirconia Crowns under Stimulated Chewing and High-Performance Aging

Recently, polyetheretherketone (PEEK) has been introduced to the dental market as a high-performance and chemically inert biomaterial. This study aimed to compare the wear resistance, abrasiveness, color stability, and displacement resistance of zirconia and PEEK milled crowns. An ideal tooth preparation of a first maxillary molar was done and scanned by an intraoral scanner to make a digital model. Then, the prosthetic crown was digitally designed on the CAD software, and the STL file was milled in zirconia (CaroZiir S, Carol Zircolite Pvt. Ltd., Gujarat, India) and PEEK (BioHpp, Bredent GmbH, Senden, Germany) crowns using five-axis CNC milling machines. The wear resistance, color stability, and displacement resistance of the milled monolithic zirconia with unfilled PEEK crowns using a chewing simulator with thermocyclic aging (120,000 cycles) were compared. The antagonist wear, material wear, color stability, and displacement were evaluated and compared among the groups using the Wilcoxon-Mann-Whitney U-test. Zirconia was shown to be three times more abrasive than PEEK (p value < 0.05). Zirconia had twice the wear resistance of PEEK (p value < 0.05). Zirconia was more color stable than PEEK (p value < 0.05). PEEK had more displacement resistance than zirconia (p value < 0.05). PEEK offers minimal abrasion, better stress modulation through plastic deformation, and good color stability, which make it a promising alternative to zirconia crown.

3D Occlusal Tooth Wear Assessment in Presence of Limited Changes in Non-Occlusal Surfaces

The study aimed to develop an accurate and convenient 3D occlusal tooth wear assessment technique, applicable when surfaces other than the occlusal undergo changes during the observation period. Various degrees of occlusal tooth wear were simulated in vitro on 18 molar and 18 premolar plaster teeth. Additionally, their buccal and lingual surfaces were gently grinded to induce superficial changes and digital dental models were generated. The grinded and the original tooth crowns were superimposed using six different 3D techniques (two reference areas with varying settings; gold standard: GS). Superimposition on intact structures provided the GS measurements. Tooth wear volume comprised the primary outcome measure. All techniques differed significantly to each other in their accuracy (p < 0.001). The technique of choice (CCD: complete crown with 30% estimated overlap of meshes) showed excellent agreement with the GS technique (median difference: 0.045, max: 0.219 mm³), no systematic error and sufficient reproducibility (max difference < 0.040 mm³). Tooth type, tooth alignment in the dental arches, and amount of tooth wear did not significantly affect the results of the CCD technique (p > 0.01). The suggested occlusal tooth wear assessment technique is straightforward and offers accurate outcomes when limited morphological changes occur on surfaces other than the occlusal.

3D Method for Occlusal Tooth Wear Assessment in Presence of Substantial Changes on Other Tooth Surfaces

Early diagnosis and timely management of tooth or dental material wear is imperative to avoid extensive restorations. Previous studies suggested different methods for tooth wear assessment, but no study has developed a three-dimensional (3D) superimposition technique applicable in cases where tooth surfaces, other than the occlusal, undergo extensive morphological changes. Here, we manually grinded plaster incisors and canines to simulate occlusal tooth wear of varying severity in teeth that received a wire retainer bonded on their lingual surfaces, during the assessment period. The corresponding dental casts were scanned using a surface scanner. The modified tooth crowns were best-fit approximated to the original crowns using seven 3D superimposition techniques (two reference areas with varying settings) and the gold standard technique (GS: intact adjacent teeth and alveolar processes as superimposition reference), which provided the true value. Only a specific technique (complete crown with 20% estimated overlap of meshes), which is applicable in actual clinical data, showed perfect agreement with the GS technique in all cases (median difference: −0.002, max absolute difference: 0.178 mm³). The outcomes of the suggested and the GS technique were highly reproducible (max difference < 0.040 mm³). The presented technique offers low cost, convenient, accurate, and risk-free tooth wear assessment.

Awareness and Treatment Decisions on Tooth Wear among Jordanian Dentists and Prosthodontists: A Cross-Sectional Survey Study

Objectives

To assess the awareness, knowledge, and treatment decisions by dentists in Jordan regarding tooth wear.

Materials and Methods

A questionnaire was disseminated to a random sample of 200 general dentists and 100 prosthodontists working in the Ministry of Health, academia, private practices, and military services. Chi square and independent t-tests were performed for statistical analysis.

Results

Hundred and seventy-nine dentists and prosthodontists responded (59.7% response rate), of which 71.5% was females. 83.8% of the dentists reported they see patients with tooth wear. 61.5% registered wear lesions in the patient file, and 68.2% reported they find a probable cause of tooth wear. 87.2% of the dentists reported that bruxism is the most common cause in Jordan. 63.3% dentists treated their patients. 46.4% reported they “always” record a dietary history. 77.7% did not think that tooth wear is linked to caries. Low confidence levels were demonstrated among general practitioners in diagnosing and treating tooth wear. Regarding treatment decisions, most dentists decided to restore worn teeth with composite and to construct a night guard. Minimally affected anterior teeth were mostly treated with fluoride. Restoration of posterior worn teeth with overlay was suggested by one-third of the dentists.

Conclusion

The dentists and prosthodontists in Jordan are aware of tooth wear. However, examination and documentation were given a little priority by general dentists. On the other hand, there was an agreement among the dentists and prosthodontists on applying the minimally invasive approach. Clinical Significance. It is challenging for dentists to make the best treatment decision for tooth wear especially as no standard treatment is available. Therefore, this study investigated the awareness and treatment decisions of a sample of dentists and prosthodontists in Jordan.

Detection of dentin-exposed occlusal/incisal tooth wear using quantitative light-induced fluorescence technology

OBJECTIVES

To prolong tooth life expectancy, tooth wear resulting in dentin exposure should be detected early. However, the most objective methods are clinically limited. We validated fluorescence parameters for distinguishing enamel from dentin-exposed wear in clinical images.

METHODS

Quantitative light-induced fluorescence (QLF) images of 73 adults (age range: 22-48 years, mean: 33.81 ± 7.71 years), including 1949 teeth with varying tooth wear degrees, without restorations, caries, or cusp area fractures, were used to calculate the ΔF_wear values. Areas-of-interest (AOIs) were selected from QLF images; the ΔF_wear values and the tooth wear index (TWI) were calculated for each tooth. The ΔF_wear values were compared according to the TWI scores. The optimum ΔF_wear values for distinguishing enamel and dentin-exposed wear were determined using the receiver operating characteristic (ROC) curve analysis.

RESULTS

Overall, 1949 AOIs were evaluated. The median ΔF_wear values for teeth with TWI scores 0, 1, and 2 (5.7 %, 10.3 %, and 17.0 %) differed significantly (P < 0.001). The optimum cutoff ΔF_wear values were 12.1 and 14.7 in the anterior and posterior teeth, respectively; the corresponding areas under the ROC values (AUROCs) were 0.86 and 0.93 (sensitivity: 0.79 and 0.85; specificity: 0.79 and 0.85, respectively). The ΔF_wear cutoff values for different age groups were within a range (12.7-13.7) and showed high validity (sensitivity, specificity, and AUROC: 0.78, 0.77-0.78, and 0.87-0.88, respectively).

CONCLUSIONS

At the optimum threshold, the ΔF_wear values showed high validity for distinguishing dentin exposure in worn teeth (AUROC: 0.87‒0.93) and could determine pathological tooth wear, particularly in posterior teeth.

CLINICAL SIGNIFICANCE

We demonstrated the feasibility of using QLF to detect dentin-exposed tooth wear and present optimal thresholds according to age. In addition, we confirmed the possibility using such image data for objective and cost-effective epidemiological investigation and application in tele-dentistry.

Clinical Behavior of Ceramic, Hybrid and Composite Onlays. A Systematic Review and Meta-Analysis

A systematic review and meta-analysis was performed to analyze the survival of onlay restorations in the posterior region, their clinical behavior according to the material used (ceramic reinforced with lithium disilicate, conventional feldspathic ceramic or reinforced with leucite; hybrid materials and composite), possible complications, and the factors influencing restoration success. The systematic review was based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement, without publication date or language restrictions. An electronic search was made in the PubMed, Scopus, Embase, and Cochrane databases. After discarding duplicate publications and studies that failed to meet the inclusion criteria, the articles were selected based on the population, intervention, comparison, outcome (PICO) question. The following variables were considered in the qualitative and quantitative analyses: restoration survival rate (determined by several clinical parameters), the influence of the material used upon the clinical behavior of the restorations, and the complications recorded over follow-up. A total of 29 articles were selected for the qualitative analysis and 27 for the quantitative analysis. The estimated restoration survival rate was 94.2%. The predictors of survival were the duration of follow-up (beta = −0.001; p = 0.001) and the onlay material used (beta = −0.064; p = 0.028). Composite onlays were associated with a lower survival rate over time. Onlays are a good, conservative, and predictable option for restoring dental defects in the posterior region, with a survival rate of over 90%. The survival rate decreases over time and with the use of composite as onlay material.

Evaluation of the assessment of tooth wear by general dental practitioners

Aim To evaluate currently available methods for assessing and monitoring tooth wear in a general dental practice environment.Method A questionnaire was developed and used to obtain data. Models were used to test the dentists' assessment of tooth wear. Ethical permission was obtained.Results Twenty general dental practitioners were interviewed and 100% were aware of the use of study models, 50% about the use of photographs and 45% of the BEWE. Methods used to assess and monitor tooth wear were study models (75%), photographs (65%), BEWE (10%), Smith & Knight index (0%) and no method (15%). Sixty-five percent of dentists were unaware of any guidelines on monitoring tooth wear. In comparing serial photographs, no participant correctly identified all the wear changes and 25% thought a change had occurred when one hadn't. Statistical analysis showed a sensitivity of only 73% with a specificity of 75%. In comparing serial study models (same cases as used in the photographs), 55% of participants identified a change when no change occurred and 50-60% of participants were able to correctly identify if wear had or had not occurred. Participants graded the models according to BEWE. Statistical analysis of these results shows a sensitivity of just 69% with a specificity of only 55%. The inter-operator agreement (Fliess' Kappa) showed an even lower degree of agreement was found with only 0.12, which suggests only a slight level of agreement, less than that with photographs.Conclusion Dentists do not seem to be aware of the current guidelines but do make reasonable attempts to monitor tooth wear. None of the currently available methods are ideal and even the use of serial study models is open to much inter-operator variability.

An accurate and efficient method for occlusal tooth wear assessment using 3D digital dental models

Tooth or material wear in a dentition is a common finding that requires timely diagnosis for management and prevention of further loss or associated esthetic or functional impairment. Various qualitative and quantitative methods have been suggested to measure tooth or material wear, but they present with limitations, such as imprecision, subjectivity, or high complexity. Here we developed and assessed an efficient 3D superimposition method to accurately measure occlusal tooth wear on 3D digital dental models. For this purpose, teeth on plaster casts were manually grinded on their occlusal surfaces to simulate various degrees of tooth wear. The casts were scanned using a surface scanner. Grinded tooth crowns (T1) were segmented and compared to the original crowns (T0) using five 3D surface superimposition techniques and a gold standard technique (GS). GS measurements were obtained by using intact adjacent structures as superimposition references. The technique of choice (complete crown with 30% estimated overlap of meshes) showed the best reproducibility (maximum difference < 0.050 mm³) and excellent agreement with the GS technique (median difference: 0.032 mm³). The suggested 3D superimposition method offers a highly efficient and accurate tool for tooth wear assessment, which could be applicable to clinical conditions.

Inverse correlations between wear and mechanical properties in biphasic dental materials with ceramic constituents

The objective of this study is to elucidate the interdependence of competing mechanical degradation processes in biphasic dental materials with ceramic constituents in the region of high-pressure occlusal loading. It is hypothesized that wear resistance in this region correlates inversely with basic material parameters (modulus, hardness, toughness, strength) evaluated from 'standardized' test specimens. Ball-on-flat wear tests in simulation of oral function are used to quantify susceptibility to protracted sliding contact damage. Wear rates for this class of dental material tend to increase with quasistatic parameter values, so the latter do not provide a reliable guide to longevity. The generation of severe-wear facets involves cumulative quasiplastic deformation and microcrack coalescence at the grain level. It is implied that interplay between wear and fracture mechanisms should be an important consideration in future microstructural design of dental ceramics, especially in the quest to balance durability against esthetics.

Tooth wear in Swedish adults-A cross-sectional study

BACKGROUND

Tooth wear has been recognised as a growing oral health problem in children and adolescents, with erosion often cited as the main cause of the tooth wear. Most studies on tooth wear have been conducted on children and adolescents, and only few studies focus on adults. Our aim was to study the prevalence of different types of tooth wear in an adult population and investigate related factors to tooth wear.

METHODS

A total of 831 adults in Sweden participated in the study by completing a questionnaire about oral health, a clinical examination, saliva sample and intraoral photographs. Tooth wear was estimated according to the Basic Erosive Wear Examination index, and the aetiology was determined based on the clinical appearance.

RESULTS

Almost 80% of the individuals had signs of erosion, and over 90% had signs of attrition. A high level of tooth wear was found in 4.6% of the individuals, few of who reported having received information about both attrition and erosion. Significantly, more men had tooth wear. Daily consumption of fruit had a stronger correlation to tooth wear than acidic drinks.

DISCUSSION & CONCLUSION

A high level of tooth wear was found in 4.6% of the individuals, and it was more common in men than women. Aside from attrition, tooth wear due to erosion was a frequent finding in adults. Only a few of the individuals with a high level of tooth wear reported to have received information about tooth wear from their dentist or dental hygienist.

Contemporary management of minimal invasive aesthetic treatment of dentition affected by erosion: case report

Background

The paradigm shift obtained with new dental materials permits minimally invasive dentistry, by following a biomimetic approach. Erosion increasingly affects the adult population through dental substance loss by acid attack. Oral rehabilitation is often extensive and requires careful mouth examination and treatments codified in the literature.

Case presentation

This clinical report proposes a reasoned approach to erosion treatment for a 39-year-old male patient presenting several old fixed prostheses. These old restorations are all of correct quality and are retained. The temporomandibular joint was free from disorder. Only defective reconstructions are remade together with eroded teeth, according to a three-step technical protocol. In the first step, mock-up manufacturing is performed which occlusal vertical dimension increased to 1 mm provoking passive dental overeruption to the second and third molars. In all, one ceramic crown was remade, and two ceramic onlays and a resin composite were integrated on the posterior teeth. The last step consisted of palatal veneers on the maxillary incisor and canine, and an aesthetic resin composite on the incisor edge. After these treatments, regular assessments were carried out at 4 months then at 6 months with visual, photographic and radiographic examinations.

Conclusion

The present dental care philosophy is to preserve dental tissue as much as possible, even in large erosion cases, and to respond to the aesthetic and functional expectations of the patient. This methodology requires a thorough evaluation phase, compliance with the protocol and regular patient follow-up.

Wear of ceramic-based dental materials

An investigation is made of wear mechanisms in a suite of dental materials with a ceramic component and tooth enamel using a laboratory test that simulates clinically observable wear facets. A ball-on-3-specimen wear tester in a tetrahedral configuration with a rotating hard antagonist zirconia sphere is used to produce circular wear scars on polished surfaces of dental materials in artificial saliva. Images of the wear scars enable interpretation of wear mechanisms, and measurements of scar dimensions quantify wear rates. Rates are lowest for zirconia ceramics, highest for lithium disilicate, with feldspathic ceramic and ceramic-polymer composite intermediate. Examination of wear scars reveals surface debris, indicative of a mechanism of material removal at the microstructural level. Microplasticity and microcracking models account for mild and severe wear regions. Wear models are used to evaluate potential longevity for each dental material. It is demonstrated that controlled laboratory testing can identify and quantify wear susceptibility under conditions that reflect the essence of basic occlusal contact. In addition to causing severe material loss, wear damage can lead to premature tooth or prosthetic failure.

Wear of dental materials: Clinical significance and laboratory wear simulation methods -A review

This review focusses on tribological aspects of teeth during function, the clinical significance of wear, wear of natural teeth and restorative materials and laboratory methods to simulate wear of restorative materials. Ceramic, metal alloy and amalgam show low material wear, whereas resin-based materials demonstrate substantial wear in the long term. The clinical wear shows a high variability with the patient factor accounts for about 50% of the variability. Wear as such seldomly compromises the function of the stomatognath system or individual teeth and is in most cases an esthetic problem. Particles that are ingested due to attrition and abrasion wear may pose a health risk to the patient, especially those from composite resin materials. However, systematic clinical studies on that issue are not available. For laboratory research many wear simulation devices and methods have been developed but only few are validated and have a moderate correlation with clinical wear.

In vitro wear behavior between enamel cusp and three aesthetic restorative materials: Zirconia, porcelain, and composite resin

PURPOSE

The aim of this study was to identify the effects of three aesthetic restorative materials on the wear between tooth and restoration by a pin-on-disk manner.

MATERIALS AND METHODS

Six aesthetic restorative materials were used to prepare disk specimens for wear test, which were Lava Zirconia as zirconia group, Vintage MP and Cerabien ZR as veneering porcelain group, Gradia Direct microhybrid composite containing prepolymerized fillers, Filtek Z250 microhybrid composite containing zirconia glass and colloidal silica particles, and Filtek Z350 nanocomposite as composite resin group. Vertical loss of the worn cusp, change of the surface roughness of the restoration materials, and the surface topography were investigated after wear test under 9.8-N contact load.

RESULTS

The porcelain groups (Vintage MP and Cerabien ZR) caused the largest vertical loss of teeth when compared with those of the composite resin and zirconia groups, and Filtek Z250 microhybrid composite results in the second-largest vertical loss of teeth. The surface of Filtek Z350 nanocomposite was deeply worn out, but visible wear on the surface of the zirconia and Gradia Direct microhybrid composite was not observed. When the zirconia surface was roughened by sand-blasting, vertical loss of teeth considerably increased when compared with that in the case of fine polished zirconia.

CONCLUSION

It was identified that microhybrid composite resin containing a prepolymerized filler and zirconia with reduced surface roughness by polishing were the most desirable restorative materials among the tested materials to prevent the two-body wear between aesthetic restorative material and tooth.

The Prevalence and Severity of Tooth Wear in Type 2 Diabetic Patients

Objective

To assess the prevalence and severity of tooth wear in type 2 diabetic patients.

Methods

Attendees at a diabetic clinic at Wiang Pa Pao Hospital in Chiang Rai province, Thailand, were invited to take part in this cross-sectional study. All participants were aged 35–74 and had type 2 diabetes. Participants were required to have been diagnosed with diabetes for at least three months. 179 subjects accepted a clinical oral examination and completed the questionnaire. Tooth wear was assessed clinically using the Smith and Knight Tooth Wear Index.

Results

The mean age of diabetic patients was 56.5 ± 7.8 years. The majority (44.1%) had diabetes more than 5 years. The average years of having had diabetes was 6.5 ± 6.3 years. The most prevalent type of tooth wear was attrition (99.4%). The prevalence of erosion, abrasion, and abfraction were 64.8%, 31.3%, and 7.3%, respectively. The majority of the tooth wear was moderate to high severity (62.1%). Erosion and abfraction showed significant association with age group (p < 0.05). Age group was significantly associated with the severity level (p=0.017). Mild tooth wear severity was the highest in age groups 35–44 and 45–54 (53.8% and 41.2%, respectively). Moderate tooth wear was the highest proportion in age groups 55–65 and 65–74 (52.2% and 44.0%, respectively). There were no significant differences between specific diabetic symptoms and types of tooth wear.

Conclusion

There was a high prevalence of tooth wear among diabetic patients. The role of prevention is vital in maintaining the integrity of the teeth and to avoid treating these worn teeth in diabetic patients.

Prevalence, severity and explanatory factors of tooth wear in Arab populations

OBJECTIVES

The aim of this study was to assess the prevalence and severity of tooth wear and related risk indicators in six Arab countries.

METHODS

This multicenter, multinational cross-sectional study was conducted among 2924 participants between the ages of 18-35 years old from six Arab countries. Calibrated dentists assessed tooth wear using the Basic Erosive Wear Examination Index (BEWE). Participants were also asked to complete a questionnaire that assessed their dietary and oral health habits. Each participant was identified by the sextant with the highest BEWE score in the upper and lower jaws.

RESULTS

Odds ratios were estimated for correlates of tooth wear anterior and posterior regions. Oman had the highest prevalence of BEWE score 3 (N = 255 (60.2%)). Overall, the highest BEWE score 3 was observed on the incisal edge of the upper anterior teeth (N = 602 (20.6%)) and in the lower left posterior region (sextant 6) on the occlusal surface (N = 466 (15.9%)). Correlates of severe tooth wear in both regions were eating or drinking more than six times per day, age and education. Drinking soft drinks "once a day" was significantly associated with severe tooth wear in the posterior region (OR: 1.3, 95% CI:1.05, 1.6). Brushing teeth more than twice a day was inversely associated with tooth wear in the anterior region (OR:0.75, 95% CI: 0.57,0.97).

CONCLUSION

The prevalence of tooth wear in Arab populations is relatively high, specific preventive and therapeutic measures should be developed to target people at higher risk of this condition.

CLINICAL SIGNIFICANCE

Tooth wear is now regarded as a significant oral health problems, dentists should advise their patients about dietary and oral health habits that can lead to severe tooth wear.

To Evaluate the Severity, Distribution of Occlusal Tooth Wear and its Correlation with Bite Force in Young North Indian Adults

AIM

To determine the severity and distribution of occlusal tooth wear among young North Indian adults and to evaluate the correlation of occlusal tooth wear with bite force.

MATERIALS AND METHODS

A total of 164 subjects were enrolled in the present study. Inclusion criteria included subjects with age range of 25-40 years having a full complement of natural dentition (excluding third molars), with no history of orthodontic treatment, FPD and trauma. Maxillary and mandibular casts of each subject were taken. Tooth wear score of anterior and posterior teeth of both the arches was calculated using a five-point (0 to 4) ordinal scoring system. The calculated tooth wear scores were then compared with data concerning age, sex, number of daily meals, vegetarian/non-vegetarian diet, Group function/Canine guided occlusion and bite force. Nonparametric (Mann-Whitney) test was used to determine the relationship between various factors and occlusal tooth wear. Spearman's correlation coefficient was used to determine the correlation between tooth wear and bite force.

RESULTS

After applying statistical analysis to the data collected, total tooth wear score of the whole sample was 30.07 ± 6.39. Anterior teeth had significantly higher wear score than posteriors (P < 0.01). Males showed significantly higher (P < 0.001) tooth wear in both arches factors such as bite force and age showed significant correlation with tooth wear (P=0.000), however, the number of meals taken per day did not show any significant correlation. Higher tooth wear loss was seen in non vegetarian dietary pattern but it was statistically insignificant. It was also found that Group function occlusion showed significantly higher mean tooth wear loss 45.76 ± 9.19 as compared to Canine guided occlusion 26.37 ± 10.68 (P=0.000).

Recent advances in understanding the fatigue and wear behavior of dental composites and ceramics

Dental composite and ceramic restorative materials are designed to closely mimic the aesthetics and function of natural tooth tissue, and their longevity in the oral environment depends to a large degree on their fatigue and wear properties. The purpose of this review is to highlight some recent advances in our understanding of fatigue and wear mechanisms, and how they contribute to restoration failures in the complex oral environment. Overall, fatigue and wear processes are found to be closely related, with wear of dental ceramic occlusal surfaces providing initiation sites for fatigue failures, and subsurface fatigue crack propagation driving key wear mechanisms for composites, ceramics, and enamel. Furthermore, both fatigue and wear of composite restorations may be important in enabling secondary caries formation, which is the leading cause of composite restoration failures. Overall, developing a mechanistic description of fatigue, wear, and secondary caries formation, along with understanding the interconnectivity of all three processes, are together seen as essential keys to successfully using in vitro studies to predict in vivo outcomes and develop improved dental restorative materials.

Methods for quantitative measurement of tooth wear using the area and volume of virtual model cusps

Purpose

Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methods of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models.

Methods

The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed.

Results

The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ρ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference (P<0.01) from the other cusps in the paired t-test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp.

Conclusions

Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear.

Wear measurement of dental tissues and materials in clinical studies: A systematic review

OBJECTIVES

This study aims to systematically review the different methods used for wear measurement of dental tissues and materials in clinical studies, their relevance and reliability in terms of accuracy and precision, and the performance of the different steps of the workflow taken independently.

METHODS

An exhaustive search of clinical studies related to wear of dental tissues and materials reporting a quantitative measurement method was conducted. MedLine, Embase, Scopus, Cochrane Library and Web of Science databases were used. Prospective studies, pilot studies and case series (>10 patients), as long as they contained a description of wear measurement methodology. Only studies published after 1995 were considered.

RESULTS

After duplicates' removal, 495 studies were identified, and 41 remained for quantitative analysis. Thirty-four described wear-measurement protocols, using digital profilometry and superimposition, whereas 7 used alternative protocols. A specific form was designed to analyze the risk of bias. The methods were described in terms of material analyzed; study design; device used for surface acquisition; matching software details and settings; type of analysis (vertical height-loss measurement vs volume loss measurement); type of area investigated (entire occlusal area or selective areas); and results.

SINIFICANCE

There is a need of standardization of clinical wear measurement. Current methods exhibit accuracy, which is not sufficient to monitor wear of restorative materials and tooth tissues. Their performance could be improved, notably limiting the use of replicas, using standardized calibration procedures and positive controls, optimizing the settings of scanners and matching softwares, and taking into account unusable data.

Mimicking and Measuring Occlusal Erosive Tooth Wear with the "Rub&Roll" and Non-contact Profilometry

Chewing, drinking, and occasional tooth grinding will result in physiological tooth wear during a lifetime. Extreme challenges, such as bruxism or habitual chewing on foreign objects, may lead to excessive wear. Recently, the role of erosion in accelerating mechanical tooth wear has been recognized, but the interplay between chemical and mechanical wear processes has not been extensively studied. Our laboratory recently introduced a novel oral wear simulation device, the Rub&Roll, that enables the user to perform wear and loading studies separately or simultaneously in an erosive and/or abrasive environment. This manuscript describes an application of the device: the combined mechanical and erosive loading of extracted human (pre)molars in a simulated chewing movement, with a controlled application of force, velocity, fluid, and time, and the application of non-contact profilometry in visualizing and measuring the resulting wear pattern. The occlusal morphology that was created in the experiment with the highest loading level is very similar to the clinical presentation of erosive wear.

In Vitro Investigation of Wear of CAD/CAM Polymeric Materials Against Primary Teeth

The aim of the study was to evaluate the effects of polymeric computer-aided design/computer-aided manufacturing CAD/CAM materials on antagonistic primary tooth wear. Five CAD/CAM polymeric materials were examined: Vipi Block Monocolor (VBM), Yamahachi polymethylmethacrylate (PMMA) (YAP), Mazic Duro (MZD), Vita Enamic (ENA), and Pekkton (PEK). All of the specimens were tested in a thermomechanical loading machine with the primary canine as the antagonist (50 N, 1.2 × 10⁵ cycles, 1.7 Hz, 5/55 °C). The wear losses of the antagonist tooth and the restorative materials were calculated using reverse modelling software and an electronic scale. VBM and ENA showed significantly higher antagonist tooth wear than PEK (p < 0.05), but there was no significant difference observed among VBM, YAP, MZD, and ENA (p > 0.05). PEK showed the largest value in both material volumetric and weight losses. In terms of material volumetric losses, there was no significant difference between all of the groups (p > 0.05). In terms of material weight losses, PEK was significantly larger than ENA (p < 0.05), but there was no significant difference between VBM, YAP, MZD, and ENA (p > 0.05). Volumetric and weight losses of materials showed similar wear behaviour. However, the wear patterns of antagonists and materials were different, especially in PEK.

Therapies for bruxism: a systematic review and network meta-analysis (protocol)

BACKGROUND

Bruxism is a sleep disorder characterized by grinding and clenching of the teeth that may be related to irreversible tooth injuries. It is a prevalent condition occurring in up to 31% of adults. However, there is no definitive answer as to which of the many currently available treatments (including drug therapy, intramuscular injections, physiotherapy, biofeedback, kinesiotherapy, use of intraoral devices, or psychological therapy) is the best for the clinical management of the different manifestations of bruxism. The aim of this systematic review and network meta-analysis is to answer the following question: what is the best treatment for adult bruxists?

METHODS/DESIGN

Comprehensive searches of the Cochrane Library, MEDLINE (via PubMed), Scopus, and LILACS will be completed using the following keywords: bruxism and therapies and related entry terms. Studies will be included, according to the eligibility criteria (Controlled Clinical Trials and Randomized Clinical Trials, considering specific outcome measures for bruxism). The reference lists of included studies will be hand searched. Relevant data will be extracted from included studies using a specially designed data extraction sheet. Risk of bias of the included studies will be assessed, and the overall strength of the evidence will be summarized (i.e., GRADE). A random effects model will be used for all pairwise meta-analyses (with a 95% confidence interval). A Bayesian network meta-analysis will explore the relative benefits between the various treatments. The review will be reported using the Preferred Reporting Items for Systematic Reviews incorporating Network Meta-Analyses (PRISMA-NMA) statement.

DISCUSSION

This systematic review aims at identifying and evaluating therapies to treat bruxism. This systematic review may lead to several recommendations, for both patients and researchers, as which is the best therapy for a specific patient case and how future studies need to be designed, considering what is available now and what is the reality of the patient.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015023308.

Hardness and modulus of elasticity of primary and permanent teeth after wear against different dental materials

Objectives:

The purpose of this study was to determine the Young's modulus and the hardness of deciduous and permanent teeth following wear challenges using different dental materials.

Materials and Methods:

Wear challenges were performed against four dental materials: A resin-based fissure sealant (Fluoroshield^®), a glass ionomer based fissure sealant (Vitremer^®), and two microhybrid composite resins (Filtek Z250 and P90^®). Using the pin-on-plate design, a deciduous or a permanent tooth was made into a pin (4 mm × 4 mm × 2 mm) working at a 3 N vertical load, 1 Hz frequency, and 900 cycles (15 min) with Fusayama artificial saliva as a lubricant. Before and after the tribological tests, the hardness and elasticity modulus of the tooth samples were measured by creating a nanoindentation at load forces up to 50 mN and 150 mN. All of the results were statistically analyzed using ANOVA and post-hoc Duncan's tests (P < 0.05).

Results:

No difference in hardness was encountered between deciduous and permanent teeth (P < 0.05) or modulus of elasticity (P < 0.05) before or after the wear challenges for all of the dental materials tested.

Conclusions:

Wear challenges against the studied dental materials did not alter the properties of permanent or deciduous teeth after the application of a 3 N load.

Nutritional status, tooth wear and quality of life in Brazilian schoolchildren

OBJECTIVE

To evaluate the correlation among nutritional status, tooth wear and quality of life in Brazilian schoolchildren.

DESIGN

The study followed a cross-sectional design. Nutritional status was measured via anthropometry using BMI and tooth wear was measured using the Dental Wear Index; both these assessments were carried out by a trained recorder according to standard criteria. A modified version of the Child Oral Impacts on Daily Performances was used to assess quality of life.

SETTING

City of Bauru, in Brazil.

SUBJECTS

A cluster sample of 396 schoolchildren (194 boys and 202 girls) aged 7-10 years.

RESULTS

The anthropometric assessment showed similar situations for both sexes regarding underweight (31·40 % in boys and 30·20 % in girls) and overweight/obesity (33·96 % in boys and 33·17 % in girls). The underweight children showed a greater severity of tooth wear in the primary teeth (OR=0·72; CI 0·36, 1·42), although in the permanent dentition the obese children had a greater severity of tooth wear (OR=1·42; 95 % CI 0·31, 6·55). The tooth wear was correlated with age for both dentitions.

CONCLUSIONS

Tooth wear in the primary and permanent dentition may be related to nutritional status. Tooth wear and obesity did not have a significant impact on the schoolchildren's perception of quality of life.

Dental wear estimation using a digital intra-oral optical scanner and an automated 3D computer vision method

The objective of this work was to propose an automated and direct process to grade tooth wear intra-orally. Eight extracted teeth were etched with acid for different times to produce wear and scanned with an intra-oral optical scanner. Computer vision algorithms were used for alignment and comparison among models. Wear volume was estimated and visual scoring was achieved to determine reliability. Results demonstrated that it is possible to directly detect submillimeter differences in teeth surfaces with an automated method with results similar to those obtained by direct visual inspection. The investigated method proved to be reliable for comparison of measurements over time.

Wear behavior of pressable lithium disilicate glass ceramic

This article reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressable lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using three-dimensional laser scanning microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation, and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behavior of LDGC and will provide guidelines for better utilization and preparation of the material for long-term success in dental restorations. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 968-978, 2016.

Estimation of the rate of tooth wear in permanent incisors: a cross-sectional digital radiographic study

This study used conventional digital radiography to estimate the rate of tooth wear (TW) of maxillary and mandibular central incisors based on a cross-sectional study design. The crown length of 1239 permanent maxillary and mandibular central incisors from 346 persons (age groups: 10, 25, 40, 55 and 70 years ± 3) were measured by three calibrated dentists. Study teeth were intact incisally, had clearly visible incisal edges and cementoenamel junctions and had natural tooth antagonists. Measures were based on digital radiographic images (N = 666) archived in MiPACS within the electronic health record (axiUm(®)) from the College of Dentistry patient database. Incisor crown length decreased at a linear rate in both arches over the 60 years represented by the age groups. The average crown length for maxillary incisors in the youngest age group was 11.94 mm, which decreased by an average of 1.01 mm by median age 70. For mandibular incisors, the average crown length in the youngest age group was 9.58 mm, which decreased by an average of 1.46 mm in the oldest age group. Males and females showed similar rates of TW. Regardless of age, females demonstrated smaller mean crown height for maxillary incisors than males (P < 0.0001). Measures by the examiners demonstrated good agreement, with an interclass correlation coefficient of 0.869 and an average intra-examiner correlation of 99.5%, based on repeated measurements (n = 100). TW was estimated to average 1.01 mm for maxillary central incisors and 1.46 mm for mandibular central incisors by age 70 years.