Prevention and Management of Tooth Wear: The Role of Dental Technology

Evaluating fatigue resistance in occlusal veneers: a comparative study of processing techniques and material thickness of lithium disilicate (IPS e.max Press vs. IPS e.max CAD)

BACKGROUND

Lithium disilicate occlusal veneers are popular for minimally invasive posterior teeth restoration. The aim of this study was to compare the fatigue resistance and crack pattern of lithium disilicate occlusal veneers fabricated using pressing and milling techniques with varying thicknesses.

METHODS

Sixty lithium disilicate discs, representing occlusal veneers, were divided into four groups (n = 15) based on processing technique (IPS e.max Press or IPS e.max CAD) and thickness (0.5 or 0.8 mm). A step-stress fatigue test was applied with axial loading, consisting of 10,000 cycles/step with a step size of 50 N until failure. Fractographic analysis was performed using SEM. Statistical analysis was performed using the Kaplan-Meier test, Mantel-Cox test, and Weibull analysis.

RESULTS

Both processing techniques resulted in similar fatigue resistances at 0.5 mm and 0.8 mm thicknesses. However, the 0.8 mm lithium disilicate restorations showed a significantly higher survival rate than the 0.5 mm lithium disilicate restorations (log-rank tests, χ2 = 58.6; df = 3; P < 0.001). Fractographic analysis revealed radial cracks originating from defects on the ceramic surface at the cementing interface, extending towards the occlusal surface.

CONCLUSIONS

At 0.5 mm or 0.8 mm material thickness, the processing technique did not affect the fatigue resistance or crack patterns of the lithium disilicate occlusal veneers. However, the lithium disilicate with a thickness of 0.8 mm exhibited a superior survival probability compared to that with a thickness of 0.5 mm.

Morphological characteristics of non-carious cervical lesions. A systematic review

OBJECTIVES

This systematic review assessed the morphological characteristics of non-carious cervical lesions (NCCL), among clinical and ex-vivo studies assessed by observational and imaging methods.

DESIGN

The search strategy was conducted on four online databases (MEDLINE, Embase, Scopus and Web of Science) and grey literature (Google Scholar and OpenGrey). The study selection was performed by three reviewers from March to September (2023). The eligibility criteria were established according to the PICO strategy and included NCCL, morphological characteristics and clinical and ex-vivo study designs. The data extraction considered general data that identifies the study, evaluation method, parameter to assess the outcome and the main results for each study. The risk of bias was evaluated using Joanna Briggs Institute critical appraisal tool, and a personalized tool.

RESULTS

The search resulted in 252 studies. A total of 14 studies were included. Prevalence of NCCLs ranged from 3.5 %to 77.78 % with a higher presence in premolars. Common characteristics were wear facets, occluded tubules or cracks, occlusal stress, scratch marks, dimples and craters, structure loss, and dentin sclerosis, which appear more often on buccal surface and were generally classified as wedge-shaped, saucer-shaped. Etiological hypothesis was mainly related to multifactorial factors. In most of the studies, the risk of bias was classified as high.

CONCLUSIONS

The morphological characteristics of NCCL showed a wide range of descriptions regarding appearance, prevalence, lesion-related measures, and macro and microscopic descriptions.

Analysis of Physical and Mechanical Properties of Universal Composites under Different Types of Polishing before and after Acid Challenge

This study aimed to evaluate in vitro the degree of surface smoothness provided by two different polishing techniques and the effect of acid challenge on the alteration of surface roughness (Ra), microhardness (Knoop), and color (ΔE00) of three nanoparticulate composites, simulating 1 year of exposure to hydrochloric acid (HCl). Eighty specimens for each composite were divided into four groups (n = 240), being control without polishing, control with wear, WPC (wear + polishing with Cosmedent Kit), and WPB (wear + BisCover LV liquid polish). Repeated measures ANOVA was applied for Ra and Knoop Microhardness. For the color (ΔE) three-way ANOVA was applied. In cases of statistically significant the Tukey posttest was applied (α = 0.05). Both types of polishing tested resulted in a surface smoothness below the critical value established by the studies (Ra ≥ 0.2 μm), even after immersion. The microhardness of all composite resins decreased after the challenges. The specimens immersed in HCl showed a lower microhardness (42.2 Kgf/mm2) when compared to the specimens immersed in artificial saliva (44.7 Kgf/mm2). Regarding the color change, the composites presented values compatible with clinical acceptability, with a statistically significant difference only between the control group and the other types of polishing for the Z350 XT resin (ΔE00 = 3.78). It was concluded that both mechanical and chemical polishing produced a satisfactory surface smoothness, even after immersions in artificial saliva and HCl. The microhardness of the composites was affected by the challenges and the composites tested were within clinical acceptability with regard to color change.

Effects on Sleep Bruxism Activity of Three Different Oral Appliances: One Year Longitudinal Cohort Study

BACKGROUND

Different oral appliances (OAs) have been proposed to control sleep bruxism (SB) detrimental effects on the stomatognathic system.

OBJECTIVE

The aim of the study was to evaluate the effect of different OAs on SB activity and masticatory muscle activity (sMMA) measured by EMG.

METHODS

This longitudinal cohort study was conducted on 51 patients (21 M, 30 F, mean age 26,5 ± 3,5) suffering from SB diagnosed with a validated portable EMG-ECG holter and wearing different OAs: occlusal splints, functional appliance with metallic bites and clear aligners followed after 1 week, 1 month, 3 months, 6 months and 12 months from delivery. A control group of 16 non-treated SB patients (6 M, 10 F mean age 27,1 ± 1,4) was used as a reference. A multiple regression analysis was performed to estimate the differences between groups. The level of significance was set as P value <0,05.

RESULTS

Occlusal splint reduced sleep bruxism index after 1 week, 3, 6 and 12 months from delivery while functional appliance only after 12 months. Occlusal splints reduced general phasic contractions only in the first week and sleep bruxism-related phasic contractions at 1 week, 3 and 6 months after delivery with no significant reductions after 12 months. Patients wearing clear aligners showed a reduction in general tonic contractions after 6 and 12 months.

CONCLUSION

Resin and metal bites can reduce sleep bruxism index, while resin bites can reduce sleep bruxism-related phasic contractions. Clear aligners do not influence sleep bruxism index but can reduce tonic contractions.

Literature Review of an Anterior Deprogrammer to Determine the Centric Relation and Presentation of Cases

The increasing demand for dental aesthetics, articulation corrections, and solutions for pain and frequent bruxism demands quick and effective restorative dental management. The biomedical research aimed to create a beneficial, ecological, and readily available anterior deprogrammer to determine the centric relation (CR) of cases. This medical device is additively manufactured from a biocompatible material. Size is customizable based on the width of the patient's anterior central incisors. This is a pilot study with two subjects. The task was to develop a complete data protocol for the production process, computer-aided design (CAD), and three-dimensional (3D) printing of the anterior deprogrammers. The research focused on creating simple and practically applicable tools for the dentist's prescription (anterior deprogrammer in three sizes), and secondly for the communication between the dentist and the patient (computer application). The tested hypothesis was whether, according to these novel tools, it is possible to produce functional occlusal splints, which could be manufactured using current technologies. This study compared a traditional splint with a digitally designed and 3D-printed one. The tested hypothesis was whether manufactured occlusal splints differ in patients' subjective perception of comfort. Each conservative treatment was monitored for ten weeks. Initial results are promising; no statistically significant difference was found between the productive technologies.

An obturator prosthesis for a 4-year-old child following treatment of a juvenile trabecular ossifying fibroma with a maxillary resection

Juvenile trabecular ossifying fibroma (JTOF) is a benign fibro-osseous lesion that usually occurs in the maxilla or mandible. Individuals with JTOF of the maxilla will most commonly require a resection that can result in a significant palatal defect. Appearance and articulatory, masticatory, and deglutitory functions can be restored with a clasp-retained obturator. Providing a prosthetic obturator with adequate retention in situations where the teeth cannot accommodate clasps because of insufficient eruption can be challenging. This article describes a technique that has been developed for such instances-in this situation, a 4-year-old child who had undergone a maxillary resection because of a JTOF.

Fabrication of Definitive Cast for Complete Mouth Rehabilitation by Using Resin-Transfer Coping

One of the most challenging steps in dentistry is taking final impressions for full mouth rehabilitation of a dentate patient. Final impressions should include the necessary details needed to fabricate a definitive cast. This cast will be used to construct indirect restorations in the laboratory. Besides all the improvement of impression materials and systems used for taking final impressions, the intraoral cavity is a challenging environment and there are some cases that prevent clinicians from recording the needed details in a single final impression. The objective of this case report is to describe a technique for fabrication of a definitive cast for a full mouth rehabilitation case by using resin-transfer coping impression technique. This technique is used as an alternative option for cases that prevent the clinician from capturing all the needed details in a single full-arch final impression.

Tooth Wear and Tribological Investigations in Dentistry

Dental or tooth wear is a physiological process in the life cycle of teeth. Loss of the occlusal surface may cause excessive tooth wear. Several factors may contribute to tooth wear with different intensities and duration in the oral cavity. The oral cavity is generally compared to a tribological system to determine the various types of wear between teeth and restorative materials and assess the amount of dental wear. However, it is challenging to investigate in vitro and in vivo wear owing to the complexity of tooth wear; thus, a clear correlation between in vitro and in vivo data could not be established. This review is aimed at providing an insight into the etiology of tooth wear and tribological investigations in dentistry.

Medical Device Regulations and custom-made device documentation: Ten frequently asked questions and their answers

Dental professionals who practice in the UK must follow the General Dental Council (GDC) Standards, one of which is to "find out about laws and regulations that affect your work and follow them". Dental professionals manufacture custom-made devices (CMDs) and the legislation that governs these devices has changed. Medical devices manufactured within the European Union (EU) were previously subject to Council Directive 93/42/EEC (Medical Devices Directive [MDD]), which was given effect in UK law by The Medical Devices Regulations 2002 (Statutory Instrument 2002/618 [UK MDR 2002]). Regulation (EU) 2017/745 (Medical Device Regulation [EU MDR]) was scheduled to replace the MDD on 26 May 2020, but this was postponed for one year due to the coronavirus (COVID-19) pandemic. In preparation for the UK's departure from the EU, the EU MDR was largely transposed into The Medical Devices (Amendment etc.) (EU Exit) Regulations 2019 (Statutory Instrument 2019/791 [UK MDR 2019]), which amended the UK MDR 2002, and was expected to come into effect on 1 January 2021 but a further amendment, The Medical Devices (Amendment etc.) (EU Exit) Regulations 2020 (Statutory Instrument 2020/1478 [UK MDR 2020]), removed these provisions. As of 1 January 2021, medical devices in Great Britain are subject to either the UK MDR 2002 (as amended) or the EU MDR (until 30 June 2023) while those in Northern Ireland must be manufactured in accordance with the EU MDR. This paper provides the answers to some key questions regarding the documentation that must be supplied with CMDs following these changes.

Enamel wear against monolithic zirconia restorations: A meta-analysis and systematic review of in vitro studies

OBJECTIVE

An assessment was performed to identify and evaluate dental enamel wear caused by monolithic zirconia restoration. Literature searches were conducted in PubMed, Science Direct, Cochrane Evidence, and the Cochrane Library up to May 2020.

MATERIAL AND METHODS

Studies were selected for systematic review according to the inclusion (articles conducted on the wear of enamel samples opposing monolithic zirconia) and exclusion (case reports, non-English articles, and monolithic zirconia samples facing other materials rather than human enamel) criteria. Of those, articles on polished and glazed monolithic zirconia subjected to a 50 N vertical load with a range of 240,000-250,000 cycles, equivalent to 1 year of in vivo mastication, were included in the meta-analysis.

RESULTS

In total, 3968 articles were pooled. Twenty-five articles met the inclusion criteria for the systematic review. Three studies were included in the meta-analysis. The results showed that the enamel wear against monolithic zirconia was within the statistically accepted level. Moreover, the polished monolithic zirconia surface caused less enamel wear than the glazed surface.

CONCLUSION

This review indicates that monolithic zirconia restorations cause acceptable antagonist enamel wear. Moreover, the meta-analysis results agreed that the final restoration's surface texture plays an essential role in the wear process.

CLINICAL SIGNIFICANCE

Monolithic zirconia restorations have been widely used in dental practice because they eliminate the chipping problems resulting from using veneered restorations. With recent technology development, monolithic zirconia has obtained more esthetic features and a more natural look. However, due to the high strength and surface roughness of monolithic zirconia, wear on the antagonist's teeth was detected. The results showed that this wear amount was statistically acceptable and lower than other ceramics such as feldspathic porcelain and enamel. Furthermore, surface treatment methods must be applied to minimize tooth wear, as polished or glazed surfaces interfere with enamel loss.

Pathophysiology of Demineralization, Part I: Attrition, Erosion, Abfraction, and Noncarious Cervical Lesions

PURPOSE OF THE REVIEW

Compare pathophysiology for infectious and noninfectious demineralization disease relative to mineral maintenance, physiologic fluoride levels, and mechanical degradation.

RECENT FINDINGS

Environmental acidity, biomechanics, and intercrystalline percolation of endemic fluoride regulate resistance to demineralization relative to osteopenia, noncarious cervical lesions, and dental caries. Demineralization is the most prevalent chronic disease in the world: osteoporosis (OP) >10%, dental caries ~100%. OP is severely debilitating while caries is potentially fatal. Mineralized tissues have a common physiology: cell-mediated apposition, protein matrix, fluid logistics (blood, saliva), intercrystalline ion percolation, cyclic demineralization/remineralization, and acid-based degradation (microbes, clastic cells). Etiology of demineralization involves fluid percolation, metabolism, homeostasis, biomechanics, mechanical wear (attrition or abrasion), and biofilm-related infections. Bone mineral density measurement assesses skeletal mass. Attrition, abrasion, erosion, and abfraction are diagnosed visually, but invisible subsurface caries <400μm cannot be detected. Controlling demineralization at all levels is an important horizon for cost-effective wellness worldwide.

Efficacy of Two Toothpaste in Preventing Tooth Erosive Lesions Associated with Gastroesophageal Reflux Disease

Patients suffering from acid reflux due to endogenous causes are often affected by gastroesophageal reflux disease which, in the oral environment, causes lingual and palatal enamel erosion. As enamel does not have the intrinsic ability to repair itself, the application of alloplastic materials, such as toothpastes is suggestable. The aim of this “in vitro” study was to compare the effectiveness of two different toothpastes in preventing erosion due to gastroesophageal reflux disease. Six tooth elements from bovine jaws were prepared using a high-speed diamond bur and water irrigation. Acid attack simulation was carried out using a 15% HCl hydrochloric acid solution. After that, two different toothpastes with or without fluoride, were brushed at the sample surface using an electric toothbrush at standard position and force. SEM and profilometer analysis were performed. Statistically significant difference was found in average tooth surface roughness after using toothpaste with or without fluoride after the acid attack, as the former offered a greater remineralization. No difference was found in long-term prevention. Fluoridated toothpastes offer a greater degree of remineralization at a first acid attack, however, there is no difference in long-term prevention independently from the toothpaste type.

Review of Cracked Tooth Syndrome: Etiology, Diagnosis, Management, and Prevention

Cracked tooth syndrome refers to a series of symptoms caused by cracked teeth. This article reviews the current literature on cracked tooth syndrome from four aspects, etiology, diagnosis, management, and prevention, to provide readers integrated information about this. The article begins with an introduction to the odontiatrogenic factors and then covers the noniatrogenic factors that induce cracked tooth syndrome. While the former discusses inappropriate root canal therapy and improper restorative procedures, the latter covers the topics such as the developmental and functional status of cracked tooth syndrome. This is then followed by the description of common clinical diagnosis methods, the prospects of new technologies, and summaries of current clinical management methods, including immediate management and direct and indirect restoration. In the final section, preventive methods and their importance are proposed, with the aim of educating the common population.

Evaluation of Masticatory Muscle Function Using Digital versus Traditional Techniques for Mockup Fabrication: A Controlled Prospective Study

Background: the aim of this longitudinal prospective study was to analyze the effect of digital and traditional mockup on masticatory muscle activity in patients with teeth wear, rehabilitated with an increase of occlusal vertical dimension. Subjects and Methods: a sample of 22 adult patients who were about to receive a prosthetic rehabilitation was divided into a study group (3M; 9F; mean age 42 ± 0.8 years), treated using the digital mockup; and a control group (2M; 8F; mean age 37 ± 0.5 years), treated using the conventional technique (traditional) mockup. Electromyographic activity of anterior temporalis and masseter muscles were evaluated before the beginning of the treatment (T0), at mockup insertion (T1), after treatment (T2) and each lapse of time lasted 2–5 months. Results: the comparison between the two groups at different time gaps revealed that at ∆1 (T1–T0) only the impact index (IMP) showed significant difference and no other significant variation was observed between the two groups at ∆2 (T2–T1) and ∆3 (T2–T0). It concludes that traditional and digital methods generally have nonsignificant differences. Conclusions: both methods seem to be effective in prosthetic rehabilitation and give comparable effects on masticatory muscles.

Use of new scratch test and tensile test for evaluation of bond strength of selfadhesive flowable resin composite for repair of artificial tooth erosion

The purpose of this study was to use a new scratch test and tensile test to evaluate the bond strength between artificial erosive enamel or dentin and self-adhesive resin composites as a coating material. Coronal enamel or dentin surface was exposed to an erosive cycle (artificial saliva [AS], pH:7.0 for 6.5 h and acidic carbonated beverages for 5 min, alternated 3 times per day) for the eroded-surface or stored in AS for the remineralized-surface. Two self-adhesive flowable resin composites, Fusio and LLB-CR6 (prototype), and a conventional flowable resin composite, BEAUTIFIL FLOW with self-etching primer system, Clearfil Mega Bond, were applied to enamel or dentin surfaces; and then the bond strengths were measured. For the eroded-surface, there were no significant differences in bonding strength among all materials, as assessed by the new scratch test. Thus, these self-adhesive flowable resin composites might be useful for coating materials on acid-eroded tooth surfaces.

Tooth wear as an indicator of acculturation process in remote Amazonian populations

Riverine populations are typical of the Amazon region that depend on nature for subsistence. These people are considered an intermediate population between the urban and indigenous, the original Amazon habitants. The aim of this cross-sectional study was to evaluate the relationship between tooth wear and age in a remote riverine population from the Amazon, located by the Tucumanduba River (n = 94), and to compare them to previous findings obtained from semi-isolated indigenous (n = 223) and urban populations (n = 40) from the Amazon region, which were examined using the same methodology. Using linear regression, tooth wear explained 54.5% of the variation in the ages of the riverine subjects (p<0.001). This coefficient is mid-way between those obtained in semi-isolated indigenous populations (65–86%) and urban subjects (12%) living in the Amazon. Our findings suggest that tooth wear, a direct evidence of what an individual ate in the past, may be an indicator of the acculturation process in remote populations.

Can canines alone be used for age estimation in Chinese individuals when applying the Kvaal method?

Due to the secondary dentin formation, the dental pulp undergoes changes in shape throughout life. Based on this phenomenon, the Kvaal method has been applied to various populations for age estimation, and its usefulness has been verified. When applying the Kvaal method to Chinese subjects, we observed a relatively strong correlation between mandibular canines and age. This study notes the correlation between canines and chronological age and is the first to identify which canine is most closely related to chronological age. In addition, a new, simpler formula is determined based on canines according to Kvaal's methodology. The radiographs of 360 individuals from northern China were selected, from which the widths and lengths of the pulp from four canines were measured according to the Kvaal method. Next, inter- and intra-observer reliabilities were analyzed in order to assess the repeatability of these measurements. The correlation between measurements and age was examined, and Chinese-specific age estimation formulae were derived. The results revealed that the ratios from the left maxillary canine exhibited the strongest correlation with age compared to the other canines, whereas the left mandibular canine showed the weakest correlation, which may contribute to the overall poor correlation of mandibular canines with age. What's more, the formula derived from the left maxillary canine in this study displayed the highest coefficients of determination, and the formula derived from all canines showed the lowest residuals. Both of these formulae performed better than the Chinese-specific formula derived from six different types of teeth in our previous study, which had formerly possessed the highest coefficients of determination and the lowest residuals. Thus, we concluded that canines do play an important role in age estimation in the Chinese population, and the correlation between maxillary canines and chronological age is stronger than that of mandibular canines, although no distinct trend as to which side is better correlated with age was established. Going forward, we recommend the analysis of additional samples from different geographical regions and populations to further verify the importance of canines in age estimation.

The Wear Performance of Glazed and Polished Full Contour Zirconia

Abstract This study evaluated the influence of zirconia surface finishes on the wear of an enamel analogue. 40 zirconia discs were divided into four groups: control (without finish); glazed; polished; polished and glazed. All samples were subjected to wear against steatite antagonists. The specimens underwent roughness, topographic, scanning electron microscopy (SEM) and wettability analyses. Quantitative wear measurements were performed on both steatites and discs. To measure wear of steatites the weight before and after the test and the diameter after the test were used. Profilometer measurements were performed to determine the wear on discs. Roughness, volumetric wear and mass loss were analyzed using the Kruskal-Wallis and Dunn tests (5%), while contact angle values were analyzed with One-way ANOVA and Tukey tests (5%). The polished group had the lowest roughness means, being statistically different from the other groups (p-value=0.0001). The glazed group presented the lowest steatite volumetric wear (p-value=0.0001), but not statistically different from the polished and glazed group, whereas these groups presented the highest zirconia volumetric wear, with statistically different (p-value=0.0002) compared to the others. SEM showed irregularities on the control groups surface, grooves on the polished group, and a homogeneous surface for the glazed group with a few pores. All groups presented contact angles lower than 90 degrees, characterizing hydrophilic surfaces. It can be concluded that just glazed zirconia caused less wear on the antagonist when compared to no finish and polished zirconia.

The Role of Mouthguards in Preventing and Reducing Sports-related Trauma

a mouthguard, also known as a gumshield, mouth protector or sports guard is an appliance that covers the teeth and surrounding mucosa with the aim of preventing or reducing trauma to the teeth, gingival tissue, lips and jaws. The device is usually worn on the maxillary arch and works by separating the maxillary and mandibular dentition, protecting the teeth from the surrounding soft tissue, absorbing or redistributing shock and/or stabilising the mandible during traumatic jaw closure. They may also play a role in preventing and reducing concussion by absorbing impact forces that would otherwise be transmitted through the base of the skull to the brain, although the evidence for this is less conclusive. A mouthguard will usually fall into one of three categories: stock mouthguards (which are made ready to use and are believed to give the least protection), the mouth-formed or 'boil and bite' type (which are heated in hot water, placed in the mouth and moulded to the teeth) and custom-made mouthguards (which are usually made on a stone model of the maxillary teeth and surrounding tissue and are thought to give the most protection). These devices can be made from various materials but ethylene-vinyl acetate is by far the most popular material, probably because of the ease with which it can be used for the production of custom-made mouthguards. This paper gives a review of the role of mouthguards in preventing and reducing sports-related trauma and examines the materials that are used to fabricate them.