An in vitro evaluation of the fatigue behavior of resin composite materials as part of a translational research cycle.

PURPOSE: This study aimed to reproduce and translate clinical presentations in an in vitro set-up and evaluate laboratory outcomes of mechanical properties (flexural strength, fatigue resistance, wear resistance) and link them to the clinical outcomes of the employed materials in the Radboud Tooth Wear Project (RTWP). MATERIALS AND METHODS: Four dental resin composites were selected. 30 discs (Ø12.0 mm, 1.2 mm thick) were fabricated for each of Clearfil TM AP-X (AP), Filtek TM Supreme XTE (FS), Estenia TM C&B (ES), and Lava Ultimate (LU). Cyclic loading (200 N, 2 Hz frequency) was applied concentrically to 15 specimens per group with a spherical steatite indenter (r = 3.18 mm) in water in a contact-load-slide-liftoff motion (105 cycles). The wear scar was analysed using profilometry and the volume loss was digitally computed. Finally, all specimens were loaded (fatigued specimens with their worn surface loaded in tension) until fracture in a biaxial flexure apparatus. The differences in volume loss and flexural strength were determined using regression analysis. RESULTS: Compared to AP and FS, ES and LU showed a significantly lower volume loss (p < 0.05). Non-fatigued ES specimens had a similar flexural strength compared to nonfatigued AP, while non-fatigued FS and LU specimens had a lower flexural strength (p < 0.001; 95 %CI: -80.0 - 51.8). The fatigue test resulted in a significant decrease of the flexural strength of ES specimens, only (p < 0.001; 95 %CI: -96.1 - -54.6). CLINICAL RELEVANCE: These outcomes concur with the outcomes of clinical studies on the longevity of these composites in patients with tooth wear. Therefore, the employed laboratory test seems to have the potential to test materials in a clinically relevant way.

Effect of weight satisfaction on adolescent facial and dental satisfaction.

PURPOSE: To investigate if facial and dental satisfaction is related to body fat percentage and body weight satisfaction. METHODS: A self-administered questionnaire was applied to adolescents from a Private School in Southern Brazil containing sociodemographic (sex and age) and self-perception variables. Adolescents were asked about their perceptions concerning dental problems. Body fat percentage was collected using bioelectrical impedance analysis. RESULTS: A total of 372 adolescents were examined. Most adolescents were satisfied with their dental (81.7%) and facial appearance (87.6%), while 39% of adolescents were satisfied with their body weight. Poisson regression model showed that adolescents who expressed satisfaction with their body weight (PR = 1.12, 95%CI 1.06-1.19) and were satisfied with their dental appearance (PR = 1.24, 95% CI 1.08-1.41) exhibited a positive association with facial satisfaction. Adolescents dissatisfied with dental color (PR = 0.88, 95%CI 0.80-0.97), those reporting dental pain (PR = 0.88, 95%CI 0.80-0.97), and individuals with obesity (PR = 0.91, 95%CI 0.83-0.99) demonstrated a decrease in facial satisfaction. Adolescents aged 16 to 19 years (PR = 1.08, 95% CI 1.01-1.15) and those satisfied with their facial appearance (PR = 1.20, 95%CI 1.01-1.43) exhibited a higher prevalence of dental satisfaction. Conversely, adolescents dissatisfied with dental color (PR = 0.74, 95% CI 0.66-0.82) and those with misaligned teeth (PR = 0.63, 95%CI 0.55-0.73) reported lower levels of dental satisfaction. Parametric g-formula analysis found that the association between body fat and facial satisfaction was mediated by body weight satisfaction (p = 0.001). CONCLUSIONS: While dental satisfaction was not influenced by corporeal characteristics, facial satisfaction was influenced by dental and body weight satisfaction. Obese adolescents had low facial satisfaction.

[Restorative treatment of generalized tooth wear]. / Restauratieve behandeling van gegeneraliseerde gebitsslijtage.

A 24-year-old patient with generalized tooth wear was referred to the Radboud Tooth Wear Project. The tooth wear had a chemical aetiology, caused by gastro-oesophageal reflux and resulting in functional problems of the masticatory system and a reduced quality of life. The treatment of the patient was minimally invasive, with directly applied composite restorations on all teeth, by means of which an increase of vertical dimension of occlusion was introduced. The restorative treatment was not preceded by testing of the new vertical dimension of occlusion. The patient was able to function well again after restorative treatment.

Randomized controlled trial on the performance of direct and indirect composite restorations in patients with severe tooth wear.

OBJECTIVE: The study aimed to evaluate survival and failure behavior of Direct Composite Restorations (DRC) and Indirect Composite Restorations (ICR) on molars and anterior teeth, in a Randomized Controlled Trial (RCT). METHODS: Patients with generalized severe tooth wear were included, and randomly assigned to one of 2 protocols: (1) DCR: All teeth were restored with directly applied micro-hybrid composite restorations (Clearfil AP-X, Kuraray) for load bearing areas and nano-hybrid composite restorations (IPS Empress Direct, Ivoclar Vivadent) for buccal veneers; (2) ICR: First molars were restored with indirect composite 'tabletop' restorations and maxillary anterior teeth were restored with indirect palatal veneer restorations (Clearfil Estenia C&B, cemented with Panavia F, Kuraray). Remaining teeth were restored directly. Restorations were evaluated after 3 years, focusing on clinical acceptability. Statistical analysis was performed using Kaplan Meier curves, Annual Failure Rates (AFRs), and univariate Cox regression analyses (p < 0.05). RESULTS: 41 patients (age: 36.6 ± 6.6y) were evaluated after 3 years (40.0 ± 2.2 m). 408 restorations on first molars and palatal veneers on maxillary anterior teeth were part of this RCT, with 220 DCRs and 188 ICRs. No differences in survival between treatment modality for palatal veneers for any failure criteria were found. Tabletop restorations on first molars showed a considerable higher failure rate for ICR compared to DCR (p = 0.026, HR: 3.37, 95%CI = 1.16-9.81). SIGNIFICANCE: In this RCT, directly applied composite restorations showed superior behavior compared to the indirect composite restorations, when used in the molar region.

[Impact of the coronavirus on Dutch oral health care and practice]. / Impact van het coronavirus op de praktijkvoering van de Nederlandse mondzorg.

Among dental hygienists and dentists in the Netherlands, the impact of the SARS-CoV-2 pandemic on oral healthcare practices from March to July 2020 was investigated. Of the 1,700 healthcare providers approached, 433 completed questionnaires could be used. The results show that the pandemic has had a profound impact on both the accessibility of oral healthcare and on care provided in oral healthcare practices. Extra attention was paid to hygiene and infection prevention: the types of personal protective equipment and the protocols and procedures were adjusted by many oral healthcare providers. The confirmed prevalence of oral healthcare providers with COVID-19 in this study was 1.6%. However, testing was not available to all respondents with complaints during this initial period. Over half of the respondents estimated that even with additional measures there is an increased risk of infection to oral healthcare providers during their work. The efficacy of the various additional measures in oral healthcare practices related to COVID-19 is still unknown.

[Risk factors for class II dental restoration survival:a practice-based study]. / Risicofactoren voor klasse II-restauratieoverleving: een praktijkgebaseerd onderzoek.

The aim of this practice-based cohort study was to determine the performance and influence of possible variables in class II restorations related to practice, patient, tooth, and restoration. To do this, electronic patient files from 11 general practices in the Netherlands were collected, and 31,472 restorations placed between January 2015 and October 2017 were analysed. The observation time of restorations varied from 0 to 2.7 years, resulting in a mean annual failure rate (AFR) of 7.8% at 2 years. However, wide variation in AFRs existed among the operators, varying between 3.6% and 11.4%. An excess of patient-related variables, such as age, general health, periodontal status, caries risk and the presence of parafunctional habits and tooth or restoration-related factors, increases the risk of reintervention. Restorations placed due to fracture were more prone to fail than restorations placed due to caries. This study demonstrated that a wide variety of risk factors on the practice, patient, and tooth levels influences the survival of class II restorations.

Risk Factors for Dental Restoration Survival: A Practice-Based Study.

To improve patient dental care, it is necessary to identify possible risk factors for the failing of restorations. This practice-based cohort study investigated the performance and influence of possible risk factors at the level of the practice, patient, tooth, and restoration on survival of direct class II restorations. Electronic patient files from 11 Dutch general practices were collected, and 31,472 restorations placed between January 2015 and October 2017 were analyzed. Kaplan-Meier statistics were performed; annual failure rates (AFRs) were calculated; and variables were assessed by multivariable Cox regression analysis. The observation time of restorations varied from 0 to 2.7 y, resulting in a mean AFR of 7.8% at 2 y. However, wide variation in AFRs existed among the operators, varying between 3.6% and 11.4%. A wide range of patient-related variables is related to a high risk for reintervention: patient age (elderly: hazard ratio [HR], 1.372), general health (medically compromised: HR, 1.478), periodontal status (periodontal problems: HR, 1.207), caries risk and risk for parafunctional habits (high: HR, 1.687), restorations in molar teeth (HR, 1.383), restorations placed in endodontically treated teeth (HR, 1.890), and multisurface restorations (≥4 surfaces: HR, 1.345). Restorations placed due to fracture were more prone to fail than restorations placed due to caries. When patient-related risk factors were excluded, remaining risk factors considerably changed in their effect and significance: the effect of operator, age of the patient, and endodontic treatment increased; the effect of the diagnosis decreased; and the socioeconomic status became significant (high: HR, 0.873). This study demonstrated that a wide variation of risk factors on the practice, patient, and tooth levels influences the survival of class II restorations. To provide personalized dental care, it is important to identify and record potential risk factors. Therefore, we recommend further clinical studies to include these patient risk factors in data collection and analysis.

[European statement of consensus regarding the treatment of severe tooth wear]. / Europese consensusverklaring over de behandeling van ernstige gebitsslijtage.

In 2016, a European consensus meeting was held regarding the treatment of severe tooth wear. This meeting resulted in the publication of the European statement of consensus on the treatment of severe tooth wear in 2017. In the statement, new definitions of physiological and pathological tooth wear are described, recommendations for diagnosis and taking preventive measure are presented, and advice for counseling and monitoring is offered to better elucidate the underlying aetiological factors causing tooth wear in the patient. The decision whether restorative treatment is appropriate is multifactorial and partially dependent on the severity and the consequences of the wear and on the aesthetic and functional wishes of the patient. Restorative intervention should be delayed as long as possible, but when such intervention is indicated, the preference is for minimally invasive techniques using direct, indirect or hybrid treatment methods.

A guide to managing tooth wear: the Radboud philosophy.

This paper explains a conservative, pragmatic and minimally invasive intervention concept for the treatment of severe tooth wear patients based on the Radboud Tooth Wear Project in the Netherlands. Guidelines and flowcharts for management of severe tooth wear patients and rehabilitation in increased vertical dimension of occlusion are presented. We concluded that: (a) Restorative treatment is not always indicated, even for patients with severe tooth wear. (b) If the patient has no complaints, counselling and monitoring is probably the best option. (c) Minimally invasive and adhesive restorative strategies are preferred when severe tooth wear patients are to be treated in increased vertical dimension, especially when young patients are involved. (d) Clinical evidence for a suitable restorative treatment protocol is limited to five-year follow up for direct composites. This material seems to be suitable for rehabilitation in increased vertical dimension on the middle long term. Clinical results for indirect techniques are not available yet. (e) Restorations, including those that are considered 'definitive' may prove to have a limited lifetime in patients with severe tooth wear due to bruxism and erosion. Explanation of the possible treatment options and expected complications should be included in the informed consent.

Clinical performance of full rehabilitations with direct composite in severe tooth wear patients: 3.5 Years results.

OBJECTIVES: To evaluate the mid-term clinical performance of direct composite restorations placed in patients with pathological tooth wear needing full rehabilitation with an increase of vertical dimension of occlusion. METHODS: In a prospective trial 34 patients (34.0 ±â€¯8.4 years; 25 males, 9 females) were treated with a minimal invasive additive technique using composite restorations. The restorative treatment protocol was to provide all teeth with composite build-up restorations in an increased vertical dimension of occlusion (VDO) using the DSO-technique. Recall appointments were planned after 1 month, 1 and 3 years after treatment. Restorations were scored for clinically acceptability (FDI-criteria) and scores 4 and 5 were recorded as clinically unacceptable. Frequencies of failures and Kaplan Meier survival curves are presented and effect of relevant variables was calculated with a multifactorial Cox regression (p < 0.05). RESULTS: 1256 Restorations were placed, 687 anterior, 324 premolar, and 245 molar restorations. After a mean observation time of 39.7 months a total of 69 failures were observed, of which 61 restorations were repaired (score 4) and 8 were replaced (score 5). Most common reasons for failure were (chip) fractures (n = 43) and caries (n = 11). Placement of anterior restorations in two sessions led to significant 4.6 times more failures then placed in one session. CONCLUSIONS: In patients with severe tooth wear a full rehabilitation, in an increased vertical dimension of occlusion, direct composite resin restorations show a 94.8% success and 99.3% survival rate after a period of 3.5 years.

Clinical studies in restorative dentistry: New directions and new demands.

Clinical research of restorative materials is confounded by problems of study designs, length of trials, type of information collected, and costs for trials, despite increasing numbers and considerable development of trials during the past 50 years. This opinion paper aims to discuss advantages and disadvantages of different study designs and outcomes for evaluating survival of dental restorations and to make recommendations for future study designs. Advantages and disadvantages of randomized trials, prospective and retrospective longitudinal studies, practice-based, pragmatic and cohort studies are addressed and discussed. The recommendations of the paper are that clinical trials should have rational control groups, include confounders such as patient risk factors in the data and analysis and should use outcome parameters relevant for profession and patients.

Longevity of Anterior Composite Restorations in a General Dental Practice-Based Network.

This practice-based study investigated the performance of a large set of anterior composite restorations placed by a group of 24 general practices. Based on data from electronic patient files, the longevity of 72,196 composite restorations was analyzed, as placed in 29,855 patients by 47 general dental practitioners between 1996 and 2011. Annual failure rates (AFRs) were calculated, and variables associated with failure were assessed by multivariate Cox regression analysis with shared frailty for 2 age groups (5 to 24 y and ≥25 y). The observation time of restorations varied from 2 wk to 13 y, with a mean of 4.8 y, resulting in a mean AFR of 4.6% (95% confidence interval [95% CI], 4.5% to 4.6%) at 5 y. Among dentists, a relevant variation in clinical performance of restorations was observed, with an AFR between 2% and 11%. The risk for restoration failure increased in individuals up to 12 y old, having a 17% higher risk for failure when compared with the age group of 18 to 25 y (hazard ratio, 1.17; 95% CI, 1.03 to 1.34), and for the age group >65 y, having a 81% higher risk for failure when compared with 25 to 35 y (hazard ratio, 1.81; 95% CI, 1.66 to 1.98). In both multivariate models, there was a difference in longevity of restorations for different teeth in the arch, with fillings in central incisors being the most prone to failure and replacement. It was concluded that anterior composite restorations placed by general dental practitioners showed an adequate clinical performance, with a relevant difference in outcome among operators.

[Preventive dentistry 5. Secondary caries]. / Preventieve tandheelkunde 5. Secundaire cariës.

Secondary caries is reported as one of the most important reasons for replacing restorations. The patient's general caries risk plays an important role in the development of secondary caries. The connection, at the patient level, between various factors, the risk of caries and restoration factors, such as the presence of a gap and the kind of restoration material, deserves additional investigation. The minimum gap width in which secondary caries can develop is most likely less than 100 µm and could depend on the patient's caries risk. Composite restorations seem more susceptible to secondary caries than amalgam restorations in patients with high caries risk. So far, there is no unambiguous explanation for this difference. The prevention of secondary caries is comparable to that of primary caries and stresses the importance of fluoride, diet and oral hygiene.

Criteria for the Replacement of Restorations: Academy of Operative Dentistry European Section.

The replacement of a restoration is one of the most common procedures in dentistry. However, the criteria for such intervention, excluding catastrophic failure and persistent discomfort and pain, continue to be the subject of considerable debate. The decision-making process remains subjective on the part of the treating clinician, while the evidence base for refurbishment and repair rather than replacement for the management of defective and failing restorations continues to grow and strengthen. This article, prepared as an Academy of Operative Dentistry European Section consensus publication, reviews existing criteria for the replacement of restorations and encourages practitioners to shift, if not already doing so, to considering the replacement of a restoration as a last resort rather than as a prudent action to be taken if in any doubt about clinical acceptability. Further research in the area, spanning the risk assessment of defective and failing restorations and new diagnostic tools and processes, together with work to enhance the evidence base of restoration repair vs replacement, would be of immense value.

Ten-Year Survival of Class II Restorations Placed by General Practitioners.

The aim of this retrospective practice-based study was to investigate the survival of direct class II restorations placed by a group of general dental practitioners (GDPs) and to analyze the effect of practice-, patient-, and tooth/restoration-related factors. Electronic patient files of 24 general dental practices were used for collecting the data for this study. From the patient files, survival rates of 222,836 composites, amalgams, glass ionomers, and compomers placed in 61,121 patients by 67 GDPs between 1999 and 2011 were analyzed by Kaplan-Meier statistics and a multiple Cox regression. The investigated group of GDPs placed restorations with a satisfactory survival (mean AFR10, 4.9%; 95% confidence interval, 2.1 to 7.7), although a wide variation in annual failure rate (AFR) existed between the different operators, varying between 2.6% and 7.0%. Restorations placed in young adults (21-30 y old) survived longest, whereas they showed a shorter survival in children (hazard ratio [HR], 1.553) and the elderly (HR, 1.593). Restorations in molar teeth, restorations placed in endodontically treated teeth, and multisurface restorations are more at risk for reintervention. However, restoration size (included surfaces) has a greater impact on restoration survival in premolar teeth. For the future, improved data collection at the practice/operator, patient, and tooth/restoration level (e.g., risk assessment and diagnoses) will provide the opportunity to evaluate even more extensively the risk factors involved. Knowledge Transfer Statement: The results of this study give insight into the long-term survival of direct dental restorations and the influencing practice-, patient-, and tooth/restoration-related variables.

Randomized controlled clinical trial of the 24-months survival of composite resin restorations after one-step incomplete and complete excavation on primary teeth.

OBJECTIVE: This randomized clinical trial aimed to compare the 24-months survival of composite restorations in primary molars after partial caries removal (PCR) and total caries removal (TCR). METHODS: Forty-eight children aged 3-8 years with at least one molar with a deep carious lesion were included (PCR; n=66; TCR; n=54). For PCR, excavation was stopped when dentine with a leathery consistency was achieved; in the TCR group, total absence of carious tissue was confirmed using a blunt-tipped probe. Pulpotomy was performed in cases of pulp exposure. Success was assessed by modified USPHS criteria with Alpha and Bravo scores recorded as success. RESULTS: Pulp exposure occurred in 1 and 15 of the teeth treated with PCR and TCR respectively (p<0.01). The restorations survival rate after 24 months was 66% (PCR) and 86% (TCR) (p=0.03). When teeth that received pulpotomy were analyzed separately, the survival rate was 92% (p=0.09). PCR performed in occlusoproximal restorations demonstrated the lowest success rate (p=0.002). PCR increases 2.90 times the probability of having a restorative failure compared to TCR (p=0.03), after adjusting for cavity type. When pulp exposure and restoration failure were considered as the outcome, there was no significant difference between the two groups (p=0.10) with success rates of 64% (PCR) and 61% (TCR). CONCLUSION: Collectively, deciduous teeth submitted to PCR prevented pulp exposure and, consequently, more invasive treatments; otherwise, PCR yielded lower longevity for composite restoration compared to TCR, suggesting that PCR restorations need to be followed over time, especially when multi-surface restorations are involved. CLINICAL SIGNIFICANCE: Composite restorations on carious remaining tissue require monitoring over time, especially those performed in more than one surface. Even if the restorations present shortcomings over the time, the majority of them are subject to repair, allowing more conservative approaches for teeth with deep caries lesions.

Restoration materials and secondary caries using an in vitro biofilm model.

This in vitro study investigated whether restoration materials and adhesives influence secondary caries formation in gaps using a short-term in vitro biofilm model. Sixty enamel-dentin blocks were restored with 6 different restoration materials with or without adhesives (n = 10 per group) with a gap: 1) Clearfil AP-X composite, 2) Clearfil AP-X composite + SE Bond, 3) Clearfil AP-X composite + ProtectBond, 4) Filtek Silorane composite, 5) Filtek Silorane composite + Silorane System adhesive, or 6) Tytin amalgam. Specimens were subjected to an intermittent 1% sucrose biofilm model for 20 days to create artificial caries lesions. Lesion progression in the enamel-dentin next to the different materials was measured in lesion depth (LD) and mineral loss (ML) using transversal wavelength independent microradiography (T-WIM). A regression analysis was used to compare the LD and ML of the different restoration materials at 4 measurement locations: 1 location at the surface of the enamel, 1 location at the wall of the enamel, and 2 locations at the wall of the dentin. A statistically significant effect of AP-X composite with Protect Bond was found for LD and ML at the WallDentin1 location, leading to less advanced wall lesions. An additional finding was that gap size was also statistically significant at the 2 wall locations in dentin, leading to increasing lesion progression with wider gaps. In conclusion, adhesives can influence wall lesion development in gaps. Protect Bond showed significantly less caries progression compared to bare restoration materials or other adhesives in this short-term in vitro biofilm model.

Longevity of posterior composite restorations: a systematic review and meta-analysis.

The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years' follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces.

Gap size and wall lesion development next to composite.

This in situ study investigated whether there is a relationship between gap size and wall lesion development in dentin next to 2 composite materials, and whether a clinically relevant threshold for the gap size could be established. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with 5 different interfaces: 4 gaps of 50 µm, 100 µm, 200 µm, or 400 µm and 1 non-bonded interface without a gap. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 minutes. Before and after caries development, specimens were imaged with transversal wavelength-independent microradiography (T-WIM), and lesion depth (LD) and mineral loss (ML) were calculated at the 5 different interfaces. After correction for the confounder location (more mesial or distal), a paired t test clustered within volunteers was performed for comparison of gap widths. Results showed no trend for a relationship between the corrected lesion depth and the gap size. None of the differences in lesion depth for the different gap sizes was statistically significant. Also, the composite material (AP-X or Filtek Supreme) gave no statistically significant differences in lesion depth and mineral loss. A minimum gap size could not be established, although, in a non-bonded interface without a measurable gap, wall lesion development was never observed.