Dentin Exposure Research Articles

Influence of different separating mediums applied on the immediate dentin sealing in the tensile strength of temporary restorations

Objective: To evaluate the ability of different separating mediums to prevent adhesion between provisionalrestorations and hybridized dentin surfaces when used with the Immediate Dentin Sealing technique (IDS).Material and Methods: 120 extracted human teeth — 40 premolars and 80 molars — were selected to integrateacrylics samples separated into 4 different groups (n=10) according to the separating medium used for IDSprotection. Forty samples were made of three teeth mounted in a self-cure acrylic resin block (Jet, Classic, SãoPaulo, Brazil) arranged side by side, simulating the positioning and proximal contacts present in the dental archbetween the second premolar, first molar and second molar. A standard dental preparation for ultra-thin occlusalveneer was performed and complete occlusal dentin exposure was achieved by selective removal of the occlusalenamel with a high-speed conical round burr (Code: 1801.4138 FG, KG Sorensen, Medical Burs Ind. e Com. dePontas e Brocas Cirúrgicas Ltda, São Paulo, Brazil). Dentin hybridization were performed on the control groupand 3 different groups of separating mediums (n=10): PC—commercial provisional separating agent (Pro-VCoat, Bisco, Schaumburg, USA); GG—glycerin gel (K-Y Gel; Johnson & Johnson Industry and Commerce LTDA,São Paulo, Brazil); PJ—petroleum jelly (Rioquímica, São Paulo, Brazil). Provisionalization were manufacturedon the prepared teeth. After 2 weeks, the tensile test was performed, and the analysis of the failure pattern wasperformed by 3D laser confocal microscopy and Scanning Electron Microscopy (SEM). The data were analyzedwith the 1-way ANOVA and the Tukey test (a = 0.05). Results: Significantly lower tensile strength values werefound for the commercial provisional separating agent (30.39 ± 10.01 N) compared to others (p < 0.05).Conclusion: The commercial provisional separating agent showed greater effectiveness on protecting hybridizeddentin against the provisional restorations. KEYWORDSDental bonding agent; Dental restoration temporary; Immediate dentin sealing.

Statistical estimation of wear in permanent teeth: A systematic review

An up to date quantitative assessment of the prevalence of tooth wear (with dentine exposure) in permanent dentition is lacking. The purpose of this systematic review was to synthesize clinical studies and research related to tooth wear in order to derive an overall estimate of the prevalence of tooth wear in permanent dentition. The eligibility criteria used in his work included population-based studies that reported the prevalence of tooth wear in permanent teeth of both adolescents and adults aged 12–80-year-old. Following the eligibility criteria, an electronic search of databases- Medline, Scopus, Embase and Science Citation Index and Biosis (Web of Science)-were performed from 1984 to 2020. Data regarding the sample size, geographical locations, year of publication, age etc. were extracted from each study and the overall estimated prevalence of tooth wear was determined. Meta-regression analysis was used to determine the source of heterogeneity in the studies while Bhattacharyya Distance (BD) was deployed to investigate the relationship within the source of the heterogeneity. The search strategy identified 4205 studies and after removal of duplicates (959), title and abstract screening (3206) and full-text reading (60), 22 studies comprising of total 20,112 subjects were included in the systematic review. The overall estimated prevalence of the tooth wear was 38% (95% CI: 31–46%), the subgroup meta-analysis revealed that continents (region) of publications was responsible for the variability of the prevalence of tooth wear within the included studies with Europe having the least prevalence rate. Bhattacharyya Distance (BD) highlighted that studies from Africa were remarkably different from other studies, whereas studies from Europe, America and Asia share some similarities. We showed that the prevalence of tooth wear with dentin exposure was 38%, with significant heterogeneity between the included studies, and the variability depends mostly on the geographical location of the studies. The results of this study can be used as an information guide by clinicians and policymakers to know the global tooth wear prevalence; can be used as a conductor in formulating policies that will help in reducing the tooth wears.

Evaluation of Microleakage in Resin Composites Bonded to an Er:YAG Laser and Bur-Prepared Root and Coronal Dentin Using Different Bonding Agents.

Introduction: This study was conducted to assess the microleakage in Er:YAG laser-ablated and bur-prepared root and coronal dentin cavities using self-etch and total-etch adhesive systems. Methods: Sixty extracted caries-free human third molars were sectioned for dentin exposure. Then, two standard class V cavities were prepared in the root and coronal dentin of each tooth and allocated to one of the following conditioning groups randomly (n=12/Group): G1: Diamond bur for cavity preparation and single bond (BESB) etch-and-rinse adhesive for bonding, G2: Er:YAG laser (160 mJ, 20 Hz, 29.88 J/cm2) and SB (LESB), G3: Er:YAG laser and SB without acid etching (LSB), G4: Diamond bur and Clearfil SE Bond (BCSE) self-etch system, and G5: Er:YAG laser and Clearfil SE Bond (LCSE). The cavities were filled with Z100 composite resin. Dye penetration was assessed after thermocycling. Data analysis was done by Kruskal-Wallis and Mann-Whitney U tests. Statistical significance was set at P<0.05. Results: The results showed there were no statistically significant differences in microleakage between the two preparation methods (bur and laser) or the bonding agents applied (P>0.05). Regardless of the cavity preparation method, dye penetration was significantly higher in coronal dentin than in root dentin (P<0.05). Conclusion: The Er:YAG laser had the same efficacy as the conventional method for cavity preparation, and microleakage did not depend on the bonding agent. Microleakage was significantly higher in coronal restorations than in root restorations.

Amelogenesis imperfecta and anterior open bite: how to optimize patient management? A review of the literature

Amelogenesis imperfecta is a genetic disease, characterized by a structural defect of the enamel and has variable clinical expressions. It can be isolated or associated as part of a syndrome. Three clinical forms exist: hypoplastic, hypomature and hypomineralized. Enamel fragility involves dentin exposure and dental hypersensitivity as frequent consequences. Some severe forms are mainly associated with an anterior open bite. The care of these patients constitutes a real challenge for the dentist. Materials et Methods: A literature review was carried out using the PubMed, Web of Science and Scopus interfaces over the past ten years in order to highlight the different treatment options available. From conservative to surgical treatment, it is necessary to develop a collaboration between the orthodontist and the pediatric dentist in order to offer multidisciplinary care adapted to the patient's needs.

English

BACKGROUND Dentinal hypersensitivity is a common clinical disease that occurs as a result of dentin exposure. Though the term dentin hypersensitivity and dentin sensitivity is used interchangeably, dentin hypersensitivity is an exaggerated form of dentinal sensitivity which arises due to localized pulpal inflammation, pulpal nerve sprouting, and development of inflammatory sodium channels. It is characterised by short sharp pain emerging from exposed dentinal tubules in reaction to various stimuli. Such dentin exposure could be due to either enamel loss or cemental loss. This is followed by removal of smear layer by mechanical or chemical means. At present, the hydrodynamic theory, which describes fluid movement in response to stimuli within exposed dentinal tubules, is a commonly recognized explanation for dentin hypersensitivity. It is more common in premolars and canines, and it affects the facial surfaces of the teeth towards the cervical aspect. Studies suggested microscopic changes in the structure of sensitive dentin compared with normal dentin. The diagnosis of dentinal hypersensitivity requires careful clinical examination and eliciting the response using various stimuli. Dentinal hypersensitivity is usually managed by the use of physical or chemical agents. They work either by disturbing the neural response to pain stimulus or block fluid flow by occluding the tubule. The desirable features of a desensitising agent include the ability to give instant and longlasting pain relief, being simple to use, well accepted, not harmful to the pulp. It is recommended that the desensitizing agent is used for at least two weeks. Some of the newer agents used for management includes CPP-ACP, proarginine, nanomaterials, herbal products, propolis etc. In cases where there is tooth structure loss, appropriate restorative material is used to cover the exposed dentin. Root canal therapy is considered the last resort for pain relief after all other options have failed to provide relief. The present article outlines the etiopathogenesis, risk factors, diagnosis, prevention and treatment of dentinal hypersensitivity. KEY WORDS Dentinal Hypersensitivity; Dentin Sensitivity; Desensitizing Agents; Iontophoresis

МОРФОЛОГИЧЕСКИЕ АСПЕКТЫ ВЗАИМОСВЯЗИ ТКАНЕЙ ПАРОДОНТА И ПУЛЬПЫ ЗУБОВ

Researchers are currently paying more and more attention to the combined pathology of the tooth pulp and periodontal. At the same time, the peculiarities of the structure of the alveolar bone, the cement of the tooth root and the root canal system that cause their interrelation and mutual influence remain insufficiently studied. The main elements of the connection between the pulp and periodontal tissues are not only apical openings and additional channels, but also other ways of interaction, the study of which is of great interest for understanding the features of pathogenesis, prognosis and treatment of combined diseases of the tooth pulp and periodontal. &#x0D; The aim of the study is to identify the topographical and anatomical features of the structure of the roots of teeth of different functional groups and the surfaces of their holes when studying on human cadaver material.&#x0D; The hypothesis of the study is that the number of openings of the Haversov channels and their localization in the moons are due to the functional affiliation of the teeth and they have their own characteristics.&#x0D; Material and methods. The study was conducted on jawbones with teeth obtained from embalmed corpses of adults of different genders and ages. After appropriate preparation, at the first stage, microscopy of the alveolar surfaces was performed, followed by morphometric analysis of the photos. At the second stage, scanning electron microscopy (SEM) of the surfaces of the roots of teeth previously extracted from the same wells of the jaws was performed.&#x0D; Results and discussion. All the preparations were systematized according to the number and topography of the identified holes of the Haversov channels. Because of the assessment of morphometric indicators, the number of holes, the density of their location and the diameter were determined, depending on the functional affiliation of the teeth. The analysis of microphotographs obtained because of SEM allowed us to determine the structural features of the surfaces of the roots of the teeth. &#x0D; Conclusions. The number, density and diameter of the holes of the Haversov channels are determined by the functional affiliation of the tooth. With the help of SEM, micro cracks and areas of root dentin exposure were found on the surfaces of the roots of the teeth for the first time, which can contribute to the translocation of pathogenic microbiota from the periodontal pocket to the pulp of the tooth and vice versa.

Substantial in-vitro and emerging clinical evidence supporting immediate dentin sealing.

The application of resin adhesive to freshly cut dentin after teeth preparation, the so-called immediate dentin sealing (IDS) has been suggested as an alternative to the delayed dentin sealing (DDS), a technique in which resin adhesive is applied just before final bonding of indirect restorations.The aim of this review is to demonstrate the evidence of the claimed advantages made by the proponents of IDS technique.The results of this review revealed substantial in-vitro evidence supporting the IDS benefits including improved bond strength, reduced dentin permeability, improved restorations’ adaptation, and increased fracture strength of the restorations. Clinical studies have shown that IDS improves survival of ceramic laminate veneers bonded to prepared teeth with increased exposure of dentin. Moreover, it has been shown that IDS reduces post-cementation hypersensitivity in full coverage restorations, which is characterized by exposure of a large number of dentinal tubules. The selection of filled resin adhesive that is capable of producing thick adhesive layer appears to contribute to the success of the technique. Furthermore, careful management of the oxygen inhibition layer before conventional impression making and proper cleaning of the residual temporary cement used with provisional restorations appears to affect the outcome of the restorations.

Oral conditions of the pre-Hispanic mummies of Gran Canaria (Canary Islands, Spain)

ObjectiveTo analyse the oral conditions of pre-Hispanic mummies from Gran Canaria (5th-11th centuries AD), comparing the results with published data from the non-mummified population. Materials440 teeth and 764 alveoli of 30 adult mummies. MethodsMacroscopic examination of pathological and non-pathological features of the oral cavity, using standardized criteria. ResultsThe mummies reveal frequent dental caries (11.8%), especially affecting molars (27.6%), a high prevalence of calculus (66.3%) and periodontal disease (34.9%). The average wear is characterized by extensive dentine exposure. Periapical lesions (10.6%) and antemortem tooth loss (AMTL) (15.9%) are common. A high percentage of individuals exhibit linear enamel hypoplasia (LEH) (84%). Except for periodontitis, the data indicate the absence of significant statistical differences between the mummies and the skeletonized sample. ConclusionsThe profile of the dental pathologies of the mummies indicates a carbohydrate-rich diet that contained abrasive grit from the stone querns used to grind cereals. Comparison of the oral conditions of mummified and skeletonized remains shows no differences in access to food resources, reinforcing the recent rejection of the traditional interpretation of the mummies as the pre-eminent status group of Canarian society. SignificanceThis is the first study to delve into the oral conditions of pre-Hispanic mummified remains from Gran Canaria. The results have implications for the framing of research questions based on the social status of these mummies. LimitationThe preserved sample of mummified remains of ancient Canarians is small. Suggestion for further researchComparative analysis from a diachronic perspective would improve understanding of the historical development of ancient Canarians.

Influence of Preoperative Pulp Inflammation in the Outcome of Full Pulpotomy Using a Dog Model

IntroductionThis study aimed to evaluate the impact of preoperative pulp inflammation on the histologic outcome of full pulpotomy performed in mature permanent posterior teeth using 4 different biomaterials. MethodsFive beagle dogs (providing a total of 120 roots) were selected. Dentin exposure was performed in teeth from the second and third quadrants. One week later, full pulpotomy procedures were performed using 4 different bioactive materials (ProRoot MTA [MTA], TotalFill BC Putty [BC], Biodentine [BIO], and an experimental cement [ie, pulp capping material]). The hemostasis time was registered. After 14 weeks, the animals were killed. Pulp-dentin tissues were histologically and radiographically assessed. The significance level was set at .05. ResultsTeeth with previously exposed dentin revealed a statistically significant increase in the time required to achieve hemostasis (P < .001), therefore confirming the pulp inflammation status induced by 1-week exposure of occlusal dentin before performing full pulpotomy. There was no radiographic evidence of root resorption, periapical radiolucency, or lamina dura alterations. No statistically significant differences were observed between normal and inflamed pulp regardless of the evaluated histologic parameters. Moreover, histologic data concerning calcified barrier formation and the pulp tissue response show better results for BIO without statistical differences compared with MTA or BC (P > .05). The pulp capping material presented a lower performance, with statistically significant differences being detected in regard to the remaining 3 tested materials (P < .001). ConclusionsRadiographic and histologic outcomes of full pulpotomy are not jeopardized by short-term preoperative pulp inflammation. Moreover, BIO, MTA, and BC cements present suitable alternatives to be used as pulp capping agents.

Fluoride and Functionalized β-tricalcium Phosphate (fTCP) Fluoride Toothpaste Affect the Primary Dentin Caries Surface: A Comparison by Estimation Statistics

This study aims to compare the effect of fTCP-contained toothpaste in combination with 950 ppm fluoride on primary dentin caries surface to ordinary 1100 ppm fluoride toothpaste by using estimation statistics. Dental caries with deep lesion and dentin exposure from nine primary teeth were cut into two equal parts and randomly divided into two groups in a before-after study. Each group was brushed with one type of toothpaste two times per day for 28 days and rested in artificial saliva. SEM images of cavity bottom surfaces and energy-dispersive X-ray spectrometry (EDX) were used to determine the percentage of calcium (Ca), phosphorus (P), fluoride (F) and oxygen (O) at six continuous measured areas from the surface of the cavity bottom into 45 µm depth before and after brushing. About 95% confidence interval of the mean difference was calculated by performing bootstrap resampling with 5000 resamples followed by comparison analysis. The percentage of Ca, P, F, O was shifted after treatment. There was no difference between the two groups. The SEM images reflected a similar illustration of EDX data. The combination of fTCP and 950 ppm fluoride in toothpaste showed equivalent effectiveness to the 1100 ppm fluoride toothpaste in primary dentin caries.

Quantification of dental macrowear using 3D occlusal surface topographic measurements in deciduous and permanent molars of children.

ObjectivesChildhood paleodietary reconstruction via dental macrowear analysis is limited in part by available methods to measure dental macrowear. We describe a method to quantify dental macrowear progression (in both deciduous and permanent molars) using a handheld intraoral scanner and two 3D occlusal topographic measurements. We assess the agreement of our macrowear proxies with an established qualitative wear scoring system and their relationship to age.Material and methodsWe scanned 92 well‐preserved dentitions of immature individuals from the medieval cemetery of St. Pölten in Lower Austria using an intraoral scanner. Two measurements were made on the resulting mesh files—the relative flat surface area in % of the occlusal surface (RFSA%) and the mesial interior slope angle. We estimated the technical error of measurement (TEM). Comparisons were made with the macrowear scoring system—tooth wear index.ResultsWe found that TEM for both measurements was between 1 and 3%, except the interobserver TEM of RFSA% which was above 5%. Both quantitative measurements generally agree with the established qualitative scores and correlate with age; however, RFSA% does not reliably indicate the progression of macrowear for teeth after dentine exposure occurs.DiscussionThe proposed 3D topographic measurements can be made reliably, and within a certain range of wear provide good quantitative proxies of the progression of dental macrowear. Such measurements constitute a promising approach for improving dental macrowear analysis in contexts such as childhood paleodietary reconstruction, which benefit from additional precision in wear rate estimation and present less dentine exposure.

The Stability of Dentin Surface Biobarrier Consisting of Mesoporous Delivery System on Dentinal Tubule Occlusion and Streptococcus Mutans Biofilm Inhibition.

BackgroundThe dentin exposure always leads to dentin hypersensitivity and/or caries. Given the dentin’s tubular structure and low mineralization degree, reestablishing an effective biobarrier to stably protect dentin remains significantly challenging. This study reports a versatile dentin surface biobarrier consisting of a mesoporous silica-based epigallocatechin-3-gallate (EGCG)/nanohydroxyapatite delivery system and evaluates its stability on the dentinal tubule occlusion and the Streptococcus mutans (S. mutans) biofilm inhibition.Materials and MethodsThe mesoporous delivery system was fabricated and characterized. Sensitive dentin discs were prepared and randomly allocated to three groups: 1, control group; 2, casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) group; and 3, the mesoporous delivery system group. The dentin permeability, dentinal tubule occlusion, acid and abrasion resistance, and S. mutans biofilm inhibition were determined for 1 week and 1 month. The in vitro release profiles of EGCG, Ca, and P were also monitored.ResultsThe mesoporous delivery system held the ability to sustainably release EGCG, Ca, and P and could persistently occlude dentinal tubules with acid and abrasion resistance, reduce the dentin permeability, and inhibit the S. mutans biofilm formation for up to 1 month compared with the two other groups. The system provided prolonged stability to combat oral adverse challenges and served as an effective surface biobarrier to protect the exposed dentin.ConclusionThe establishment of the dentin surface biobarrier consisting of a mesoporous delivery system indicates a promising strategy for the prevention and the management of dentin hypersensitivity and caries after enamel loss.

Dentinogenesis imperfecta type II: a case report

Objective: Dentinogenesis imperfecta (DI) type II is a rare dentin development disorder with an autosomal dominant inheritance that affects both functional and aesthetic aspects of deciduous and permanent dentitions. This study reports the clinical case of a patient diagnosed late with this anomaly. Material and methods: Male patient, 33 years old, sought dental care complaining of dental aesthetic dissatisfaction. During clinical examination, it was observed that the teeth had a brownish color, with wear and tear of the dental enamel and dentin exposure. Radiographically, the teeth presented the pulp chambers and root canals obliterated, in addition to bulbous crowns. The patient reported that several members of his family had the same condition. The established clinical diagnosis was DI type II. Conclusion: In this case, type II dentinogenesis imperfecta was diagnosed late and without adequate therapeutic intervention, causing aesthetic and functional damage to the patient.

Management of Non-Carious Lesions: A Case Report

Introduction: Non-carious lesions are caused as a result of tooth surface loss. Several categories of tooth surface loss exist, including erosion, attrition, abrasion and abfraction. Numerous factors, such as bruxism, clenching, disease, dietary considerations, lifestyle choices, improper tooth brushing, abrasive dentrifices, craniofacial complex, iatrogenic dentistry and ageing might contribute to this problem. It can be challenging to identify the cause, but it is feasible by observing the pattern of tooth surface loss on the teeth, and it is essential for treatment planning to avoid failure. Prevention, tooth remineralization and active treatment by repairing the affected teeth are all methods of managing this process. Treatment options include minimally invasive and adhesive dentistry to full mouth rehabilitation, and restoring the lost vertical height. Case Report: A 45-year-old female patient reported to the Department of Conservative Dentistry and Endodontics with a chief complaint of sensitivity in the upper front teeth for the past 2 months. The clinical examination showed abrasion on the buccal surface of teeth 13 and 23 with dentin exposure. And also, abfraction with respect to 14. No signs of mobility or pain on percussion. Conclusion: The steps of problem identification, diagnosis, etiological factor removal or treatment, and, if necessary, restoration, are components of treating non-caries lesions. The restorative treatment must be considered for dentin hypersensitivity and for the re-establishing of dental esthetics.

The effect of Fit-checking material and various subsequent cleaning methods on the wettability of the dentin surface: an in vitrostudy

Background: GC Fit-checker is a modified polyvinyl siloxane impression material exclusively used to check the internal fit and improve the marginal fit of indirect restorations. An unpolymerized organic film is known to be leftover on the bonding surfaces after the silicone disclosing procedure. Residual silicone film being hydrophobic may alter the wettability of the cement to the tooth/metal surface, thus having a detrimental effect on the bond strength and retention of the restoration. Aim: This study aimed to evaluate the wetting of luting liquid (GIC) to tooth dentin surface after application of Fit-checker and evaluate the efficiency of various surface treatments in removing the residual silicone film. Materials and Methods: Extracted human molars were mounted on the acrylic block, and the tooth occlusal surface was ground flat till the dentin exposure. All the specimens were assigned into five groups: Group 1: without application of Fit-checker (control group); Group 2: without any surface treatment after peeling off Fit-checker; Group 3: surface treatment with wet pumice; Group 4: 37% phosphoric acid treatment; Group 5: 10% polyacrylic acid treatment. Later, Type 1 Glass Ionomer Cement (GIC) liquid drop was placed on the dentin and photographs were made horizontally using a standardized procedure. Contact angles were measured using AUTOCAD software. Obtained values were statistically analyzed using the One-way ANOVA test and Tukey’s Post hoc test. Samples of each group were examined using the scanning electron microscope. Results: Statistically significant difference was observed among all the groups except between Group 4 and Group 2 (p > 0.05). SEM images of various groups showed a significant difference in roughness patterns. Conclusion: Surface treatment with pumice and the rotary brush was an effective method among the three in cleaning the residual silicone film.

Role of enamel and dentin on color changes after internal bleaching associated or not with external bleaching.

Objective To evaluate the effect of the association between external and internal tooth bleaching on color changes in dentin and enamel, individually or recombined, previously stained with triple antibiotic paste (TAP).Methodology Forty enamel-dentin specimens from bovine incisors were separated into ten blocks according to similarity in their whiteness index (WID). Three specimens within each block were stained by dentin exposure to TAP, and the remaining specimen was used as control to estimate color changes. Specimens were sectioned to separate tissues, and dentin and enamel colors were measured individually and after being recombined. Alterations in color (CIEDE2000 - ΔE00) and translucency parameter (TP) resulting from staining were estimated by color difference between stained and control specimens. The contribution of each tissue to the color change (CTCC) was also calculated. Non-sectioned stained specimens were bleached by applying sodium perborate on dentin, associated or not with 35% hydrogen peroxide on enamel. Color changes caused by bleaching procedures were estimated and data were analyzed using the paired t-test or Two-way repeated measures ANOVA.Results TAP caused more pronounced changes in dentin, but enamel color was also affected. Both protocols presented a similar ΔE00, and dentin showed the greater color change. After exposure to TAP, we observed a reduction in WID; WID values were the same for bleached and control specimens regardless of protocol. We found no significant effect of substrate and bleaching technique on TP. Enamel played a more critical role in color changes caused by either staining or bleaching procedures.Conclusion Enamel color played a greater role on tooth color changes than dentin. External and internal bleaching association did not improve bleaching effect on specimens stained with TAP.

OCT evaluation of the internal adaptation of ceramic veneers depending on preparation design and ceramic thickness

ObjectivesIn-vitro evaluation of the influence of preparation design and thickness of ceramic veneers on the interfacial bond using optical coherence tomography (OCT). MethodsSixty-four central incisors were randomly assigned to four preparation designs differing from no to complete dentine exposure (n = 16 each): non-prep (NP), minimal-invasive (MI, no dentine exposure), semi-invasive (SI, 50% dentine) and invasive (I, 100% dentine). Ceramic veneers (IPS InLine Veneer) of two thicknesses (0.2−0.5 mm (T1) and > 0.5–1.2 mm (T2)) were etched, silanized, and adhesively luted (Optibond FL, Variolink Veneer). After water storage (37 °C, 21d), thermocycling (2000 cycles, 5°-55 °C), and mechanical loading (2 + 1 million cycles, 50 + 100 N) specimens were imaged by spectral-domain OCT (Telesto II, Thorlabs). Adhesive defects at the ceramic-composite and tooth-composite interfaces were quantified on 35 equidistantly distributed OCT B-scans (length, %). Statistical differences were verified with Wilcoxon-/Mann-Whitney-U-test (α = 0.05). ResultsAdhesive defects appeared in all groups at both interfaces, albeit to differing extents (0.1 – 31.7%). NP and MI veneers showed no significant differences at the interfaces (pi > 0.05). In groups, SI and I, significantly more adhesive defects appeared at the tooth-composite compared to the veneer-composite interface (pi ≤ 0.039). The following preparation designs and veneer thicknesses showed differences (pi ≤ 0.021): Veneer-composite: NP-T1 < I-T1, MI-T1 < I-T1, I-T1 > I-T2; Tooth-composite: NP-T1 < SI-T1, NP-T1 < I-T1, NP-T2 > MI-T2, MI-T1 < SI-T1, MI-T1 < I-T1, SI-T1 < I-T1, MI-T2 < SI-T2, MI-T2 < I-T2. SignificanceThe interface adhesion of ceramic veneers was influenced by the preparation design and the veneer thickness. A ceramic thickness of at least 0.5 mm and a preparation without exposing dentine is advantageous for the interfacial bond.

Assessing molar wear in narrow-headed voles as a proxy for diet and habitat in a changing Arctic

This paper investigates the potential of mesoscale tooth wear (mesowear, chipping, facets, and other wear attributes) in rodents as a proxy for Arctic habitat. It presents a pilot study of narrow-headed voles, Microtus gregalis, at three sites along a latitudinal gradient of ecological subzones in the Yamal Peninsula of the Russian Arctic. These sites include Kharp in the forest–tundra ecotone, Erkuta in the low Arctic, and Sabetta at the border between the low and the high Arctic. A total of 117 specimens were included and eight variables were used to characterize mesoscale tooth wear. Results show significant differences between the sites, suggesting that these variables can distinguish populations from different subzones. Kharp has the flattest tooth wear, whereas Sabetta has the most M1 occlusal relief and dentin exposure. These results are consistent with and interpreted in the light of published experimental work on captive voles. In addition, the Kharp sample has the tallest M1 crowns, whereas Sabetta has the most vertically implanted M1s. The general directional trends toward separation of values by latitude of samples suggests that mesoscale wear in hypselodont rodents (those with open-rooted, ever-growing molar teeth) reflects variation in food abrasivity and, by extension, may be valuable for tracking habitat and ecological changes in the Arctic.

The Prevalence of Tooth Wear in an Adult Population from the Eastern Province of Saudi Arabia.

AimTo assess the prevalence of tooth wear in the Eastern Province of Saudi Arabia in an adult population and to identify potential contributing factors, such as sociodemographic factors.MethodsThis cross-sectional study included adults between 18 and 40 years, seeking routine dental care. A clinical examination using the tooth wear index (TWI) was performed. Each tooth was given a TWI score, followed by classifying participants according to different risk levels. This was followed by a self-administered questionnaire on demographic information and oral hygiene habits. Statistical analyses included univariate, bivariate, as well as multivariate to assess the risk of tooth wear in relation to possible risk factors. The tests used were odds ratios (ORs) with 95% confidence intervals (CIs) and p-values < 0.05 to be statistically significant.ResultsThe prevalence of tooth wear and dentin exposure was 83.5% and 58.8%, respectively, with the mean affected teeth of 1.3 ± 0.6 and 0.2 ± 0.2. Both gender and education level were significantly associated with tooth wear at bivariate and multivariate levels (p < 0.05).ConclusionThe prevalence of tooth wear among sampled adults in this study was high. There was a clear difference in rates of tooth wear for gender and education level. Early identification and prevention of tooth wear will help reduce signs and symptoms in later stages of life.

Influence of graphene oxide filler content on the dentin bond integrity, degree of conversion and bond strength of experimental adhesive. A SEM, micro-Raman, FTIR and microtensile study

The study aimed to evaluate the effect of graphene oxide (GO) nano-filler content in experimental dental adhesive on its degree of conversion (DC), microtensile bond strength (μTBS) and structural reliability, using Fourier transform infrared spectroscopy (FTIR), Micro-Raman spectroscopy and Scanning electron microscopy (SEM). A resin adhesive was fabricated (control adhesive - CA) and fabricated GO nano-particles were added at 0.5% and 2.0% (m/m) to produce adhesives GOA1 and GOA2 respectively. One hundred and two teeth (specimens) were prepared for dentin exposure and conditioned with 36% phosphoric acid. Specimens in each group (n = 34) were treated with formulated adhesives (CA, GOA1 & GOA2) and photo-polymerized for 20 s followed by composite build up. Sixty specimens were used for μTBS testing in the adhesive groups (CA, GOA1 & GOA2), with half exposed to thermocycling (TC) whereas the remaining half (n = 10) stored in distilled water. Seven specimens each were assessed using SEM and Micro-Raman spectroscopy, in each adhesive group (n = 7). DC for the adhesives was assessed using FTIR. The means of μTBS and DC were analyzed using ANOVA and post hoc Tukey multiple comparisons test. GO nano-filler content showed significant influence on the adhesive μTBS in comparison to controls (p < 0.01). Ageing (TC) revealed significant reduction in the μTBS, except in GOA2 specimens, which showed comparable outcomes among TC and non-TC specimens (p > 0.05). DC was significantly higher in control adhesive [46.8 (3.6)%] compared to GOA2 [37.7 (4.2)%] specimens, however DC was comparable among GOA1 [42.3 (2.9)%] and GOA2 [37.7 (4.2)%] specimens (p > 0.05) respectively. GO exhibited interaction within adhesive and tooth dentin comparable to control adhesive. Increasing GO content showed increase in μTBS of adhesive to dentin, but a decrease in degree of conversion. Under ideal conditions, experimental adhesive with 2% GO content showed acceptable bond strength and DC; and should be further assessed under dynamic conditions to recommend clinical use.