Restoration Failure Research Articles

Assessment of Prevalence and Causative Factors for Replacement of Composite and Amalgam Restorations: An Observational Study

ABSTRACT Aim: This study intends to evaluate the frequency and causes of replacement for failed amalgam and composite dental restorations. Methodology: A cross-sectional study comprising female patients with failed permanent composite and amalgam restorations aged 15–60 years old was carried out at the dental clinics of Qassim University. Using a self-structured proforma, demographic data and causes for restoration failure were recorded. The effectiveness of the restorations was assessed by using the Ryge criteria after performing clinical and radiographic examinations. The Statistical Package for Social Science was used for the statistical analysis. Results: It is found that 84.6% of the 299 unsuccessful restorations examined were composite, and 15.4% were amalgam. The main reason for dental failure for both amalgam (95.6%) and composite (93.28%) restorations was secondary caries. Failure of amalgam restoration was largely caused by poor marginal adaptation. With varied incidences between amalgam and composite restorations, typical complaints included discomfort, sensitivity, pain, and food impaction with soreness. The main justification for replacement in amalgam restorations was sensitivity. Repair and replacement rates were similar for amalgam, composite, and mandibular/maxillary restorations. Moreover, 21.1% of individuals overall reported no symptoms, with 8.7% in the amalgam group and 23.3% in the composite group with significant differences (χ 2 = 34.28, P = 0.001). Conclusion: According to the current study, secondary caries was found to be the main reason for both amalgam and composite restoration failure. The main problems reported were sensitivity, discomfort, and pain with amalgam showing more sensitivity-related failures.

Effect of low-temperature degradation on the fatigue performance of dental strength-gradient multilayered zirconia restorations

ObjectivesFatigue and low-temperature degradation (LTD) are the main factors contributing to zirconia restoration failure. This study evaluated the effect of LTD on the fatigue performance of the novel “strength & shade-gradient” multilayered zirconia restorations. MethodsDiscs (15 mm × 1.2 mm) of each yttria content layer from a newly developed strength-gradient multilayered zirconia were fabricated and under accelerated aging in an autoclave at 134℃ for 0 h, 32 h, and 64 h. Then, the phase transformation, microstructure, and mechanical properties after LTD were assessed. In addition, the crown samples, including the multi-Zir, 3Y-Zir, and 5Y-Zir were fabricated, and their monotonic and fatigue load before and after LTD, percentage of fatigue degradation (Sd) and the fracture morphology were investigated. Statistical analyses were performed using paired samples t-test (α′ = α/3 = 0.017), one-way ANOVA and Weibull analysis. ResultsAfter LTD, the phase transformation, surface roughness, depth of transformed zone, and residual stress were increased and inversely associated with the yttria content. The indentation elastic modulus and hardness after LTD decreased; however, there was no significant difference between the different yttria content layers. The monotonic and fatigue load of multi-Zir restorations decreased, but their Weibull modulus increased, and Sd decreased, similar to 3Y-Zir. The crack origin was associated with the cervical region. ConclusionThese results show that although LTD reduces the absolute fatigue strength of strength-gradient multilayered zirconia restorations, it also reduces the effect of cyclic fatigue itself on the strength of zirconia (relative to monotonic strength), which might be due to the increase of residual stress. Clinical significanceThe novel “strength & shade-gradient” multilayered zirconia restorations show a promising performance during in vitro LTD and fatigue test and their reliability to some extent is comparable to 3Y-Zir. Yet, further in vivo longitudinal studies are warranted to confirm their precise performance.

Investigating the antibacterial activity of Thyme Oil/TiO2 modified resins against oral pathogenic bacteria

Dental composites lack inherent antimicrobial activity, leading to secondary caries and restoration failure. This study developed a novel thyme oil/TiO2 nanoparticle filler to impart sustainable antibacterial functions to dental resins. TiO2 nanoparticles were synthesized via a sol-gel method and characterized as 20–30 nm crystalline anatase particles. Functionalization with thyme oil was confirmed by FTIR, with 5.8% thyme oil content measured by TGA. Resin disks containing 0.5–2 wt% thyme-TiO2 exhibited significant inhibition zones against S. mutans, L. acidophilus and C. albicans (8–12 mm) compared to thyme oil-free controls (0 mm) (p < 0.05). Thyme-TiO2 at 1–2 wt% showed sustained release of thyme oil over 15 days with bacterial viability reduction of 68–99% compared to unmodified resin (p < 0.05). Resin-dentin microtensile bond strengths were 45–50 MPa for 0.5–2 wt% thyme-TiO2 and not significantly different from control (p > 0.05). Likewise, flexural strength, elastic modulus and surface microhardness values were unchanged with thyme-TiO2 incorporation ≤ 2 wt% (p > 0.05). DPSC viability was > 90% for all resins, indicating good cytocompatibility. Overall, the thyme-TiO2 nanocomposite successfully endowed the dental resin with potent, long-lasting antibacterial effects without compromising key mechanical properties.

Dental composite biodeterioration in the presence of oral Streptococci and extracellular metabolic products

ObjectiveSecondary caries is a primary cause of early restoration failure. While primary dental caries has been extensively researched, our knowledge about the impact of secondary caries on dental restorations is relatively limited. In this study, we examined how different clinically relevant microbially-influenced environments impact the degradation of nano-filled (FIL) and micro-hybrid (AEL) dental composites. MethodsMaterial strength of two commercial dental composites was measured following incubation in aqueous media containing: i) cariogenic (Streptococcus mutans) and non-cariogenic bacteria (Streptococcus sanguinis) grown on sucrose or glucose, ii) abiotic mixtures of artificial saliva and sucrose and glucose fermentation products (volatile fatty acids and ethanol) in proportions known to be produced by these microorganisms, and iii) abiotic mixtures of artificial saliva and esterase, a common oral extracellular enzyme. ResultsNano-filled FIL composite strength decreased in all three types of incubations, while micro-hybrid AEL composite strength only decreased significantly in biotic incubations. The strength of both composites was statistically significantly decreased in all biotic incubations containing both cariogenic and non-cariogenic bacteria beyond that induced by either abiotic mixtures of fermentation products or esterase alone. Finally, there were no statistically significant differences in composite strength decrease among the tested biotic conditions. ConclusionsThe results show that conditions created during the growth of both cariogenic and non-cariogenic oral Streptococci substantially reduce commercial composite strength, and this effect warrants further study to identify the mechanism(s). Clinical SignificanceDental biofilms of oral Streptococci bacteria significantly affect the mechanical strength of dental restorations.

A low-shrinkage-stress and anti-bacterial adherent dental resin composite: physicochemical properties and biocompatibility.

Polymerisation shrinkage and biofilm accumulation are the two main problems associated with dental resin composites (DRCs) that induce secondary caries, which can cause restoration failure. Polymerisation shrinkage can lead to microleakage gaps between the tooth and the DRCs, causing the aggregation of bacteria and development of secondary caries. Reducing the shrinkage stress (SS) and improving the resistance to bacterial adhesion have always been the focus of this field in modifying DRCs. A thiol-ene resin system can effectively reduce the polymerisation SS via its step-growth mechanism for delaying the gel point. Fluorinated compounds can reduce the surface free energies, thereby reducing bacterial adhesion. Thus, in this study, a range of mass fractions (0, 10, 20, 30, and 40 wt%) of a fluorinated thiol-ene resin system were added to a fluorinated dimethacrylate resin system/tricyclo decanedimethanol diacrylate to create a fluorinated methacrylate-thiol-ene ternary resin matrix. DRCs were prepared using the obtained ternary resin matrix, and their physical and chemical properties, effect on bacterial adhesion, and biocompatibility were investigated. The results demonstrated that the volumetric shrinkage and SS of the DRCs were reduced with no reduction in conversion degree even after the thiol-ene resin system was added. All DRC-based fluorinated resin systems exhibited an excellent anti-bacterial adhesion effect, as evidenced by the colony-forming unit counts, live/dead bacterial staining, and crystal violet staining tests against Streptococcus mutans (S. mutans). The genetic expressions associated with the bacterial adhesion of S. mutans were substantially affected after being cultured with fluorinated DRCs. All fluorinated DRCs demonstrated good biocompatibility through the in vitro cytotoxicity test and live/dead staining images of the L-929 cells. The above results illustrate that the DRCs based on the fluorinated methacrylate-thiol-ene resin matrix can be potentially applied in clinical practice due to their low SS and anti-bacterial adhesion effect.

Comparison of three-dimensional printed resin crowns and preformed stainless steel crowns for primary molar restorations: a randomized controlled trial.

The importance of aesthetics in children has increased over time. Therefore, this multicenter randomized clinical trial aimed to analyze and compare three-dimensional (3D)-printed resin crowns (RCs) as a potential alternative to stainless-steel crowns (SSCs) for restoring primary molars with extensive carious lesions. According to the null hypothesis, no statistically significant difference was observed in restoration failure between RC and SSC groups. A total of 56 primary molars after pulp treatment at two dental hospitals were included. After pulp treatment, the teeth were randomly divided into two groups: SSCs (n = 28) and RCs (n = 28). At 1 week and 3, 6 and 12 months, the Quigley-Hein plaque index (QHI), gingival index (GI), occlusal wear, and survival rate were assessed by examination, radiography and alginate impressions. No significant difference in QHI was observed between the two groups. However, the GI at 12 months and occlusal wear in the RC group were significantly higher than those in the SSC group (p < 0.05). The survival rates were 100% in the SSC group and 82.1% in the RC group (p = 0.047). Cracks and discoloration were also observed in the RCs. Within the limitations of this study, 3D-printed RCs are aesthetically superior to SSCs and clinically easy to repair. However, if clinical effectiveness and safety are improved, RCs could potentially become a viable aesthetic alternative in the future.

Partial glass-ceramic posterior restorations with margins beyond or above the cemento-enamel junction: An observational retrospective clinical study.

This observational retrospective clinical study aimed to investigate the survival and success rates of partial indirect lithium disilicate restorations with margins extending above or beyond the cementoenamel junction (CEJ). The study included patients who underwent partial indirect lithium disilicate restorations with immediate dentin sealing (IDS) between January 2008 and October 2018. All the restorations were placed in a single general dental practice following a standardized protocol. The impact of various predictive variables on the survival rates was assessed. Moreover, modified United States Public Health Service (USPHS) criteria were used to evaluate the survival quality. Totally 1146 partial indirect lithium disilicate restorations in 260 patients were evaluated over an average period of 7.5 years. The cumulative survival and success rates were 97.3% and 95.3%, respectively. Margins extending beyond the cemento-enamel junction did not increase the risk of success or survival failure (P > 0.05). Patients with a high risk of caries, male sex, or non-vital teeth had a significantly higher risk of restoration failure (P < 0.05). Restorations with longer clinical service times exhibited marginally lower clinical quality (P < 0.001). Partial indirect glass-ceramic restorations demonstrated survival and success rates of 97.3% and 95.3%, respectively, over an extended period. However, a higher risk of restoration failure existed in patients with a high caries risk for (pre)molars that had undergone endodontic treatment and in males. In terms of the risk of success or survival failure, comparable results were obtained for the positions of the restoration margin in relation to the cemento-enamel junction.

Clinical Longevity of Ceramic Veneers Bonded to Teeth with Aged Composite Restorations (Literature Review)

In this study the literature was reviewed to investigate the clinical outcome and longevity of anterior ceramic laminate veneers bonded to prior existing composite restorations. Clinical studies had investigated the survival of anterior ceramic laminate veneers adhered to teeth structures for at least 5 years of follow-up. This review has traced the studies which recorded the clinical longivity of porcelain laminate veneers bonded over old composite restorations; also the main reasons associated with restorations failure were searched. Sources in PubMed, Scopus, and Cochrane databases were searched in English language and without restriction on date. three reviewers screened titles and/or abstracts of 195 studies, all screened articles did not met the inclusion criteria of this review; which to have five years and more follow up in clinical retrospective or prospective studies, for that reason we have selected the most In vivo could possibly more related and the related In vitro studies. Within the limitation of this review, the clinical evidence for the practice of ceramic laminate veneers bonded over prior aged composite restorations is not strong. There is information lack about the long duration follow up for such treatment modality. The approach of replacing the prior existing composite restoration with new ones could be a wise option but using extended veneer design might be a wiser alternative. We recommend more clinical trials for long enough duration to evaluate the long success of ceramic laminate veneers that will be adhered to prior existing composite restorations.

POSTOPERATIVE SENSITIVITY IN POSTERIOR COMPOSITE RESIN RESTORATIONS

Composite resin restorations are part of everyday clinical practice, delivering aesthetic and long-lasting results, provided there is mastery of the technique and knowledge of dental materials. Among the main failures in composite resin restorations is postoperative sensitivity, which causes discomfort for both the patient and the dentist due to the need to redo the procedure. The aim of this study is to demonstrate, through the literature, the possible origins of postoperative sensitivity and to describe more effective methods to minimize it. A literature review was conducted, with a temporal focus on the last 10 years (2013–2023), where articles published on the topic were searched in the PubMed, Scielo, Google Scholar, Scribd, and Lilacs databases. Postoperative sensitivity occurs due to the movement of existing dentinal fluids in the dentin, caused by inadequate sealing of dentinal tubules. Procedure failure is associated with factors such as restorative technique, adhesive system, monomer conversion rate, and polymerization time, which can lead to postoperative sensitivity. Thus, postoperative sensitivity can be triggered by various factors during the clinical procedure, requiring attention at every stage of the restorative technique by the dentist

Structural, electrochemical, biological, and mechanical assessment of functionally graded Cr-based multilayers for enhanced metal-ceramic bond strength in dental restorations

The failures of metal-ceramic dental restorations happen due to the initiation of a corrosive process that leads to the deterioration of restorations from a mechanical and aesthetic point of view, by releasing ions and corrosion products, causing patient hypersensitivity, as well as by detaching the ceramic from the metal support. The purpose of this study was to improve the metal-ceramic adhesion of dental prosthetic frameworks by covering their metallic components with biocompatible inorganic coatings, resistant to corrosion in the oral cavity environment. Different coating architectures based on chromium oxynitrides were obtained by cathodic arc method on CoCr alloy substrate. GDOES results confirmed the proposed configuration of the multilayers, and (O + N)/(Cr + Si) ratio calculated for each component layer (ranging from 0.7 to 2.7) emphasized the gradual transition from a metallic character towards a ceramic character of the CrSiON outer layer. XRD analysis proved the stability of the coating structure when a ceramic sintering treatment was applied, the Cr2O3 trigonal phases formed as a result of heat treatment, having a beneficial effect on the metal-ceramic bond strength. After 12h immersion in artificial saliva (pH = 5), an increased protection efficiency was observed for all the proposed multilayers. Among them, the best behaviour was exhibited by CrSiN/CrSiON coating, as pointed out by electrochemical impedance spectroscopy. Even after 72h of immersion, the mentioned design proved the highest pore resistance, result ascribed to a more defect free structure, which acted as a corrosion barrier to the electrolyte ingress. However, biological assessment revealed that the best proliferating and metabolic support for human gingival fibroblasts was showed by Cr/CrSi/CrSiN/CrSiON coating. Similar results were obtained by mechanical characterization of the new CoCr-multilayers-ceramic systems (tests performed based on the requirements specified in ISO 9693:2012 standard), indicating that the coating with the highest number of interfaces had also the highest surface roughness and lower contact angles, and therefore, the best bond strength value.

Technological Aspects and Performance of High Entropy Alloys with Potential Application in Dental Restorations and Reducing Implant Failure

Amidst the prevalence of aggressive bacterial infections that can impact both oral and systemic health following various dental and implant procedures, the search for alternative, high-performing and biocompatible materials has become a challenging pursuit. The need for such investigations is increasing owing to the fact that toxicological risks of cobalt–chromium (CoCr) alloys used in dentistry have become a part of the EU’s new Medical Devices Regulations establishing that cobalt metal has been classified as carcinogenic, genotoxic and detrimental to reproduction. Within this context, this review proposes high entropy alloys (HEA) as potential alternatives and presents their characteristics and in vitro biological performance when used as a substrate or coating. Anatomical details of the oral cavity in relationship with prosthodontics and implant dentistry support the paper’s motivation and presentation. The review highlights the innovative manufacturing procedures, microstructure and properties of both the bulk and coatings of BioHEA. It evaluates the performance of BioHEAs based on their complete characterization and assesses their suitability for novel applications in dentistry, serving as the primary objective of this manuscript.

An Audit of Indication, Distribution, and Failure of Direct Composite Restoration in a Tertiary Hospital

Abstract Background: Currently, the move to phase down/phase out Amalgam as a direct restorative material has made composite restoration presently the most used direct tooth-coloured restoration in all teeth. Aim: The aim is to assess the indication, distribution, and failure of direct composite restorations placed in a tertiary teaching hospital over a period. Methodology: A three-year retrospective audit of composite restorations placed in a Nigeria tertiary facility. Data concerning composite cases were extracted from the case files using a pro forma. Sociodemographics, type of procedure, type of teeth, shade of composite, and failure of restoration were among the data collected. Descriptive analysis was performed using frequency and percentage, and Chi-square test was used to test associations between categorical variables (P &lt; 0.05). Results: A total of 898 cases were retrieved and analysed. A higher number: 333 (37.1%) of the participants were in the age group 21–40 years and the majority were (507, 56.5%). Cervical abrasion (289; 32.2%), followed by class 1 carious cavity (105; 11.7%), were the major procedures specified. Upper centrals had the highest restoration (135; 15%). Only 24.5% of the restorations reported the use of glass ionomer cement (GIC) lining. Shade A3 was the most used (73; 57%). The failure rate recorded was 13.8% and the use of GIC reduced it to 5.1% (P &lt; 0.001). Conclusion: A 13.8% failure of composite restoration within the three-year study period was observed, which fell within the reported range from other studies. Furthermore, it was observed that the use of GIC lining, where necessary, contributed to the survival of composite restoration.

Effects of repeated sediment bypassing on stream ecosystems in a Japanese mountainous river

Sediment bypassing connects the upstream and downstream regions of dam impoundments through tunnels and is expected to partly restore natural processes (flood pulse and sediment regime) in dam‐altered river ecosystems. However, few reports examined the effects of restoration on stream biota. We examined the effectiveness of repeated sediment bypassing (12 times) over a period of 5 years in a Japanese dammed river using a before‐after‐reference‐impact design. We compared the abiotic parameters (water quality and substrate environment), biotic assemblages (algae, macroinvertebrates, and fish), and similarities between the dam downstream and undammed reference reaches. The reference sites exhibited high temporal variability in abiotic environments and species composition over the 5‐year period. Most abiotic and biotic parameters downstream of the dam improved and approached those of the changing reference states. However, these indices returned to pretrial conditions after the last trial. Biotic similarities between the downstream and reference reaches gradually increased throughout successive sediment‐bypassing trials for macroinvertebrates and algae; however, these similarities diminished after the last trial. Conversely, the abundance‐based composition of fish assemblages in the restored reach consistently diverged from that of the reference conditions throughout the study period. Our results show that the success and failure of restoration by sediment bypassing may be affected by the amount of bedload in the flushing flows and other regional processes such as migratory connectivity. Sediment bypassing can partially re‐establish natural processes and is a useful tool for improving sediment‐associated environments and biota.

Does the Modality of Dental Treatment Affect the Treatment Prognosis and the Necessity of Re-Treatments?

The utilization of evidence-based approaches is crucial to achieving long-term positive outcomes for treatment performed chairside or under general anesthesia. The study aimed to evaluate if treatment modality (at the chairside or under general anesthesia) affects prognosis and the need for re-treatment. Oral-hygiene, gingival, and plaque indexes were recorded during the control appointment. The success of all treatments was evaluated according to the scoring of particular evaluation criteria. A total of 1066 dental procedures were performed on 92 children. Plaque index scores were higher for patients treated under general anesthesia. The success rate of restorative procedures was 82.5% under general anesthesia and 80.6% at the chairside. There was no statistically significant difference between the mean number of restorative treatments and the need for re-treatment between general anesthesia or chairside (p = 0.649, p = 0.311). The mean number of unsuccessful endodontic treatments performed under general anesthesia was higher than performed chairside. Only two out of thirty stainless-steel crowns were decemented, all performed under general anesthesia. The high volume of restoration failure due to secondary caries has highlighted the need for alternative approaches to caries management, especially given the risks associated with repeat general anesthetic.

Robotic Hartmann's reversal-feasibility and technical aspects.

Hartmann's reversal as a staged procedure after emergency surgery is a major abdominal operation with undeniable skill-demanding steps. The robotic approach and its advantages seem to be a safe and feasible technique and could overcome necessary technical compromises of laparoscopy, ensuring a significant reduction in restoration failures or conversion.

Cultivating Resilience in Dryland Soils: An Assisted Migration Approach to Biological Soil Crust Restoration.

Land use practices and climate change have driven substantial soil degradation across global drylands, impacting ecosystem functions and human livelihoods. Biological soil crusts, a common feature of dryland ecosystems, are under extensive exploration for their potential to restore the stability and fertility of degraded soils through the development of inoculants. However, stressful abiotic conditions often result in the failure of inoculation-based restoration in the field and may hinder the long-term success of biocrust restoration efforts. Taking an assisted migration approach, we cultivated biocrust inocula sourced from multiple hot-adapted sites (Mojave and Sonoran Deserts) in an outdoor facility at a cool desert site (Colorado Plateau). In addition to cultivating inoculum from each site, we created an inoculum mixture of biocrust from the Mojave Desert, Sonoran Desert, and Colorado Plateau. We then applied two habitat amelioration treatments to the cultivation site (growth substrate and shading) to enhance soil stability and water availability and reduce UV stress. Using marker gene sequencing, we found that the cultivated mixed inoculum comprised both local- and hot-adapted cyanobacteria at the end of cultivation but had similar cyanobacterial richness as each unmixed inoculum. All cultivated inocula had more cyanobacterial 16S rRNA gene copies and higher cyanobacterial richness when cultivated with a growth substrate and shade. Our work shows that it is possible to field cultivate biocrust inocula sourced from different deserts, but that community composition shifts toward that of the cultivation site unless habitat amelioration is employed. Future assessments of the function of a mixed inoculum in restoration and its resilience in the face of abiotic stressors are needed to determine the relative benefit of assisted migration compared to the challenges and risks of this approach.

Clinical evaluation of lithium disilicate versus indirect resin composite partial posterior restorations – A 7.8-year retrospective study

ObjectiveTo evaluate retrospectively the longevity of lithium disilicate ceramic (LidiSi) vs. laboratory-processed resin-based composite (RBC) inlay/onlay/overlay restorations and risk factors associated with restoration deficiencies and failures. MethodsPatients (n = 91) receiving LidiSi (73.1%) and RBC (36.9%) inlays/onlays/overlays between 2007 and 2017 were selected. The restorations were evaluated using the modified U.S. Public Health Service criteria. The survival of the restorations was analyzed using the Kaplan-Meier method and log rank test. Factors affecting the occurrence of deficiencies were examined by logistic regression analysis. This was performed with the use of the Generalized Estimating Equation model including Repeated measurements (GEER), with the consideration that the same patient had several teeth in the sample. Risk estimation was conducted for each evaluated criterion (p < 0.05). ResultsThe survival of LidiSi and RBC restorations were 96.8% and 84.9%, respectively after a mean observation period of 7.8 ± 3.3 years. The annual failure rate was 0.2% for LidiSi and 1.0% for RBC. The probability of survival was above 98% for both restorations in the first 6 years, however, it dropped to 60% for RBC by the end of the 15th year. For both materials the reasons for failure included secondary caries, restoration fracture, and endodontic complication. In addition, LidiSi also failed due to tooth fracture, while RBC due to marginal gap formation and loss of retention. Among the evaluated risk factors, material of restoration (OR=6.8, CI95%:3.1–14.9), oral hygiene (OR=8.0, CI95%: 2.9–22.1], and bruxism (OR=1.9, CI95%: 1.1–3.3) showed a significant impact on the evaluated criteria. SignificanceLidiSi and RBC restorations showed similarly excellent 6-year survival, however, in the long term significantly more failures should be expected for RBCs.

The impact of occlusal forces on the longevity of restorations

The longevity of dental restorations like fillings, crowns, and bridges is critically influenced by occlusal forces exerted during biting and chewing. These forces vary among individuals based on diet, masticatory habits, and the structural soundness of the dental arch and can range from 11 to over 450 Newtons, depending on circumstances. The choice of restorative material is important for withstanding these forces. While amalgam is durable, modern dentistry has shifted towards aesthetic restoratives such as composite resins and ceramics. However, these materials respond differently to occlusal forces. Ceramics might fracture under excess load, whereas composite resins resist wear but can degrade over time due to other factors. Precision in restoration is crucial to preventing undue occlusal forces that might lead to restoration failure. Tools like T-scan assist in this precision. The manner and distribution of occlusal forces, along with the health of the periodontal ligament, are critical for restoration durability. Bruxism, a parafunctional habit, can significantly impact restorations, necessitating protective measures like occlusal splints and patient education. The interplay of occlusal forces and the chosen restorative material greatly affects the success and lifespan of dental restorations.

Psychological Stress as a Determinant of Increased Maximum Voluntary Bite Force - A Clinical Observational Study.

Background Psychological stress is a known risk factor and modulator for several oral diseases. It is among the critical etiological factors of bruxism and several other disorders. The quantum of bite force is one of the prime determinants of wear resistance and the clinical performance of restorations. Thus, the present study aims to investigate the relationship between the maximum voluntary bite force (MVBF) and the amount of perceived stress experienced by an individual. Materials and methods Patients (n=111) fulfilling the exclusion and inclusion criteria were divided into high, medium, and low-stress groups based on their stress scores deduced from the Perceived Stress Scale questionnaire (PSS). Bite force measurement was recorded in Newtons (N) for each subject using a portable customized bite recording FlexiForce sensor (B 201). The data were analyzed using Kruskal-Wallis and independent samples t-test. Results Among the females, the bite force in the medium and high-stress groups was greater compared to the low-stress level group. On the other hand, there was no difference in bite force between any of the stress level groups among male participants. Conclusion The results show that higher MVBF is associated with higher perceived stress scores in adult females. Practical Implications Psychological counseling can be included in the dental treatment plan of individuals with a high-stress score to counteract their stress-related higher occlusal forces, parafunctional jaw movements, and risky oral health behaviors, thereby potentially reducing the incidence of adverse outcomes such as temporomandibular joint dysfunction and restoration failure by careful choice of restorative materials.

Formulating an altered dentin substrate to improve dentin bonding

Statement of problemSecondary caries is a major factor in the failure of dental restorations. However, studies on the fabrication of acid-resistant and antibacterial dentin to improve dentin bonding are sparse. PurposeThe purpose of this in vitro study was to compare the effects of 2 types of fluoride-containing etchants on dentin bonding and explore the feasibility of formulating an altered dentin substrate to improve dentin bonding. Material and methodsNaF-containing and SnF2-containing etchants were developed by adding sodium fluoride and stannous fluoride to a 35% phosphoric acid aqueous solution. Two groups (N1 and N2) containing NaF, 10 and 30 mg/mL respectively, and 2 groups (S1 and S2) containing SnF2, 18.6 and 55.8 mg/mL respectively, were formulated. The etchant of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), microhardness, antierosion, and antibacterial tests were performed on the treated dentin. Moreover, the microtensile bond strength (µTBS) of each group was tested, and the fracture mode was determined after testing. Statistical analysis was performed with the 2-way ANOVA test (α=.05). ResultsThe exposed collagen fiber was observed in group C, and minerals were formed on the dentin in the experimental groups. SEM, FTIR, and the microhardness test indicated more remineralization in the SnF2-containing etchant groups. The µTBS of S1 (77.5 ±10.36 MPa) was the highest in all groups, and group C (38.5 ±9.01 MPa) was the lowest. Moreover, the antierosion and antibacterial properties of the S2 group were the best among all groups (P<.05). ConclusionsCompared with NaF-containing etchant, SnF2-containing etchant could improve the dentin substrate, increase remineralization, improve bonding strength, and enhance antibacterial ability, especially by increasing resistance to acid erosion.