Complications of endodontically treated abutment teeth after restoration with non-precious metal double crowns.

OBJECTIVES: This study aimed to evaluate the effects of endodontic treatment on the complication rate in abutment teeth following double crown treatment. MATERIALS AND METHODS: Data of 233 patients supplied with 278 prostheses on 773 teeth were retrospectively analyzed. The 60-month cumulative complication rate for vital, root filled, and post and core reconstructed abutment teeth is calculated using the Kaplan-Meier method. Cox regression is performed to evaluate factors including age, sex, jaw, and tooth number. RESULTS: After 60 months, the cumulative complication rate for all abutment teeth was 24.1% (CI: 19.7-28.5%). A significantly higher cumulative fracture rate (log-rank test, p < 0.001) was found for devital (51.7%; CI: 35.3-68.1%) compared to vital abutment teeth (20.6%; CI: 16.2-25%). Devital teeth restored with post and core reconstructions (46.3%; CI: 26.1-66.5%) showed a lower cumulative fracture rate than abutment teeth with only root fillings (60.9%; CI: 33.5-88.3%). Abutment teeth in severely reduced dentitions (≤ 3 teeth) were found to have significantly lower survival rates than abutment teeth in not severely reduced dentitions (≥ 4 teeth, p = 0.031, HR = 0.609). CONCLUSION: Lower abutment teeth survival rates were associated with non-vitality and a reduced number of abutment teeth. Devital teeth with post and core reconstructions showed higher survival rates than root filled devital teeth. CLINICAL RELEVANCE: After 5 years, devital teeth with double crowns have a fracture rate twice as high as vital teeth. This prognosis should be taken into account during treatment planning, especially in the severely reduced dentition.

Clinical performance of non-precious metal double crowns with friction pins in severely reduced dentitions.

OBJECTIVES: Several in vitro studies have investigated the retention of double crowns with friction pins (DCP); however, clinical data on their long-term success have not been reported. We sought to evaluate the 5-year survival rate of DCPs in patients with severely reduced dentition (SRD) and not severely reduced dentition (NSRD). MATERIALS AND METHODS: A total of 158 patients were treated with 182 dentures on 520 abutment teeth between 2006 and 2016. The SRD group included 144 dentures that had been inserted on 314 abutment teeth. We evaluated the influence of age, sex, jaw, number, tooth vitality, and abutment teeth localization (according to Steffel's classification) on the 60-month survival rates of dentures and abutment teeth using the Kaplan-Meier estimator, logrank test, and Cox regression. RESULTS: The cumulative 60-month survival rate was 84.3% (CI 77.1-91.5%) for all dentures; however, the survival rate in the SRD group (80.3%; CI 71.5-89.1%) was significantly lower than in the NSRD group (100%; p = 0.04). Dentures classified in Steffel's class A had the lowest survival rate (51.5%; CI 30.9-72.1%). Number, location, and vitality of the abutment teeth had a significant impact on survival rate. CONCLUSIONS: DCP dentures showed comparable clinical long-term success to double crown systems that have been previously reported in the literature. The number, localization, and vitality of abutment teeth had the greatest influence on the survival rates of denture and abutment teeth. CLINICAL RELEVANCE: DCP dentures have an acceptable 5-year survival rate. Clinical treatment planning must take into account key factors associated with the prognosis of the abutment teeth.

Retention force of removable partial dentures with different double crowns.

OBJECTIVES: The aim of the study was to compare the retentive behaviors of double crowns with different designs and material compositions before and after artificial aging. MATERIALS AND METHODS: Six pairs of double crowns were fabricated: telescopic crowns 0° made of high-noble metal (group A) or non-precious metal (group B), telescopic zirconia copings with secondary crowns made of electroplated gold 2° (group C), crowns with friction pins 2° made of non-precious metal (group D) or zirconia (group E), and conical crowns 6° made of high-noble metal (group F). Retention forces were assessed before and after artificial aging, and after axial and non-axial loading. RESULTS: Initially, specimens in group D (13.9 N), B (12.5 N), and E (12.2 N) exhibited the highest retention forces. Retention forces in groups A (9.6 N), C (7.4 N), and F (6.0 N) were statistically significantly lower than those of the other groups (p < 0.05). After artificial aging, double crowns with additional retention elements exhibited the highest retention forces. The largest retention force losses were evident in groups A (70%), B (64%), C (39%), and F (47%). CONCLUSIONS: Double crowns with different designs and made of different materials exhibited different retention forces and different long-term retentive behavior. The highest retention force losses were evident in double crowns with more extended surface contact, such as telescopic crowns. CLINICAL SIGNIFICANCE: Telescopic crowns with additional retention elements were more resistant to wearing than double crowns without additional retention elements. An additional clinical benefit might be the quick and easy possibility of enhancing retention.

Accuracy of CAD-CAM-fabricated removable partial dentures.

STATEMENT OF PROBLEM: The conventional fabrication of removable partial dentures (RPDs) is a complex, error-prone, time-consuming, and expensive process. The use of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, especially rapid prototyping, promises a more effective method for fabricating RPD frameworks. PURPOSE: The purpose of this in vitro study was to evaluate the fit of RPD clasps fabricated by means of 4 different CAD-CAM-systems and to compare those fittings with that of the conventional lost-wax casting technique (LWT). MATERIAL AND METHODS: A master model of a partially edentulous maxilla with the canines and second molars as the remaining teeth was fabricated. After the model was optically scanned, we designed a quadrangularly supported RPD with 4 clasps and a palatal strap major connector. A standard tessellation language data set was used to fabricate 12 identical RPDs by using 4 different CAD-CAM techniques: indirect rapid prototyping (wax inject printing combined with LWT), direct rapid prototyping (selective laser melting), indirect milling (wax milling with LWT), and direct milling (resin milling [polyetheretherketone]). Three conventionally cast RPDs (LWT) served as the control group. The fit accuracy of the clasps (n=12 for each group) was determined in both the horizontal and vertical dimensions by using light microscopy. RESULTS: Indirectly milled RPDs (117 ±34 µm horizontal and 45 ±21 µm vertical) and directly milled RPDs (43 ±23 µm horizontal, and 38 ±21 µm vertical) showed significantly better (P<.05) fit than did conventionally fabricated LWT RPDs (133 ±59 µm horizontal; 73 ±25 µm vertical). The worst fit was found for RPDs fabricated using indirect rapid prototyping (323 ±188 µm horizontal and 112 ±60 µm vertical) or direct rapid prototyping (365 ±205 µm horizontal and 363 ±133 µm vertical), which were unstable on the master model, making them unsuitable for clinical use. Most RPDs exhibited smaller vertical measuring distances. CONCLUSIONS: Compared with the LWT, milling techniques enabled fabrication of RPDs with comparable or better fit. However, RPDs fabricated with rapid prototyping techniques showed distinct fitting irregularities.

Colonization of CF patients' upper airways with S. aureus contributes more decisively to upper airway inflammation than P. aeruginosa.

In cystic fibrosis (CF) patients' airways, inflammatory processes decisively contribute to remodeling and pulmonary destruction. The aims of this study were to compare upper airway (UAW) inflammation in the context of Staphylococcus aureus and Pseudomonas aeruginosa colonization in a longitudinal setting, and to examine further factors influencing UAW inflammation. Therefore, we analyzed soluble inflammatory mediators in noninvasively obtained nasal lavage (NL) of CF patients together with microbiology, medication, and relevant clinical parameters. NL, applying 10 mL of isotonic saline per nostril, was serially performed in 74 CF patients (326 samples). Concentrations of the inflammatory mediators' interleukin (IL)-1ß, IL-6, IL-8, matrix metalloproteinase (MMP)-9, and its anti-protease TIMP-1 were quantified by bead-based multiplexed assay, neutrophil elastase (NE) via ELISA. Culture-based microbiology of the upper and lower airways (LAW), as well as serological and clinical findings, were compiled. Our results indicate that UAW colonization with S. aureus significantly impacts the concentration of all measured inflammatory mediators in NL fluid except TIMP-1, whereas these effects were not significant for P. aeruginosa. Patients with S. aureus colonization of both the UAW and LAW showed significantly increased concentrations of IL-1ß, IL-6, IL-8, MMP-9, and slightly elevated concentrations of NE in NL fluid compared to non-colonized patients. This work elaborates a survey on S. aureus' virulence factors that may contribute to this underestimated pathology. Serial assessment of epithelial lining fluid by NL reveals that colonization of the UAW with S. aureus contributes more to CF airway inflammatory processes than hitherto expected.

Dimensional Accuracy of Different Three-Dimensional Printing Models as a Function of Varying the Printing Parameters.

Even in digital workflows, models are required for fitting during the fabrication of dental prostheses. This study examined the influence of different parameters on the dimensional accuracy of three-dimensionally printed models. A stereolithographic data record was generated from a master model (SOLL). With digital light processing (DLP) and stereolithography (SLA) printing systems, 126 models were produced in several printing runs-SolFlex350 (S) (DLP, n = 24), CaraPrint 4.0 (C) (DLP, n = 48) and Form2 (F) (SLA, n = 54)-and their accuracy was compared with plaster and milled polyurethane models. In addition to the positioning on the build platform, a distinction was made between parallel and across arrangement of the models to the printer's front, solid and hollow models, and printing with and without support structures. For accuracy assessment, five measurement sections were defined on the model (A-E) and measured using a calibrated digital calliper and digital scans in combination with the GOM Inspect Professional software 2021. The mean deviation between the measurement methods for all distances was 79 µm. The mean deviation of the models from the digital SOLL model were 207.1 µm for the S series, 25.1 µm for the C series and 141.8 µm for the F series. While positioning did not have an influence, there were clinically relevant differences mainly regarding the choice of printer, but also individually in alignment, model structure and support structures.

Pain After Outpatient Surgical Procedures.

BACKGROUND: Approximately 8.1 million outpatient surgical procedures were performed in Germany in 2021. Little is known about the quality of postoperative pain treatment in the outpatient sector. METHODS: The AQS1 project comprises a combined survey of patients and staff in the framework of quality control for ambulatory surgery. The primary endpoint of this study was the prevalence of relevant incisional pain (≥ 4/10 on the numerical rating scale) up to postoperative day 3. Secondary endpoints included prognostic variables for pain and pain-associated outcomes, based on the AQS1 patient questionnaire. Moreover, mixed regression models were used to analyze potential prognostic variables and associations of pain with other outcomes (study registration number DRKS00028052). RESULTS: Data from 330 008 patients were evaluated (from 1 July 2001 to 31 December 2021). The overall prevalence of relevant incisional pain up to postoperative day 3 was 22.5%, with major differences between different types of procedure (3.2%-51.2%). Pain was most common after hemorrhoid surgery (51.2%) and the laparoscopic lysis of large and small bowel adhesions (45.4%). The main associations of relevant pain were with younger age (odds ratio [OR] 1.87, 95% confidence interval [1.82; 1.91]), early postoperative pain (1.34, [1.30; 1.39]), inadequate provision of analgesics (2.90, [2.71; 3.09]), and surgical wound infections (2.60, [2.43; 2.78]). Patients with pain reported lower overall satisfaction with the procedure and a longer inability to work. CONCLUSION: These data have not been tested for representativeness. They can serve as a point of departure for the optimization of individualized perioperative pain therapy and for the planning of prospective studies.

The Incidence and Risk Factors of Persistent Opioid Use After Surgery­a Retrospective Secondary Data Analysis.

BACKGROUND: The risk of persistent postoperative opioid use (PPOU) and its association with the type of surgery are still unclear in Germany. METHODS: We conducted a nationwide retrospective cohort study on the basis of claims data from BARMER, a statutory health insurance carrier in Germany. Opioid-naive adults who did not have cancer and who underwent inpatient surgery in 2018 were included in the study. The operations were divided into 103 categories. PPOU was defined as the prescribing of opioids between postoperative days 1 and 90 and also between postoperative days 91 and 180 after hospital discharge. Patient-associated risk factors in the 12 months before surgery were investigated. RESULTS: 203 327 patients were included. 1.4% had PPOU (95% confidence interval [1.4; 1.5]). There were major differences between operation groups: major amputations and orthopedic procedures carried the greatest risk for the development of PPOU. The type of surgery had a larger effect on the risk of PPOU than pre-existing risk factors (explained variance 22.3% vs. 14.3%). Among such factors, alcohol abuse and pre-existing treatment with antidepressant drugs were associated with the highest risk for PPOU (odds ratios [OR] 1.515 [1.277; 1.797] and 2.131 [1.943; 2.336]). CONCLUSION: The incidence of PPOU in Germany is low (1.4%). The type of surgery plays an important role in its development.

Risk Factors for Severe Pain and Impairment of Daily Life Activities after Cesarean Section-A Prospective Multi-Center Study of 11,932 Patients.

Cesarean section (CS) is the most widely performed and one of the most painful surgeries. This study investigated postoperative pain after CS using patient-related outcomes (PROs) to identify risk factors for severe pain. The secondary outcome was to evaluate the influence of surgery indication (primary CS (PCS) vs. urgent CS (UCS)). This multi-center, prospective cohort study included data submitted to the pain registry "quality improvement in postoperative pain treatment" (QUIPS) between 2010 and 2020. In total, 11,932 patients were evaluated. Median of maximal pain was 7.0 (numeric rating scale (NRS) 0 to 10); 53.9% suffered from severe pain (NRS ≥ 7), this being related to impairment of mood, ambulation, deep breathing and sleep, as well as more vertigo, nausea and tiredness (p < 0.001). Distraction, relaxation, mobilization, having conversations, patient-controlled analgesia (PCA) and pain monitoring were shown to be protective for severe pain (p < 0.001). Maximal pain in PCS and UCS was similar, but UCS obtained more analgesics (p < 0.001), and experienced more impairment of ambulation (p < 0.001) and deep breathing (p < 0.05). Severe pain has a major effect on daily-life activities and recovery after CS, and depends on modifiable factors. More effort is needed to improve the quality of care after CS.

The Cystic Fibrosis Upper and Lower Airway Metagenome.

The microbial metagenome in cystic fibrosis (CF) airways was investigated by whole-genome shotgun sequencing of total DNA isolated from nasal lavage samples, oropharyngeal swabs, and induced sputum samples collected from 65 individuals with CF aged 7 to 50 years. Each patient harbored a personalized microbial metagenome unique in microbial load and composition, the exception being monocultures of the most common CF pathogens Staphylococcus aureus and Pseudomonas aeruginosa from patients with advanced lung disease. The sampling of the upper airways by nasal lavage uncovered the fungus Malassezia restricta and the bacterium Staphylococcus epidermidis as prominent species. Healthy and CF donors harbored qualitatively and quantitatively different spectra of commensal bacteria in their sputa, even in the absence of any typical CF pathogen. If P. aeruginosa, S. aureus, or Stenotrophomonas maltophilia belonged to the trio of the most abundant species in the CF sputum metagenome, common inhabitants of the respiratory tract of healthy subjects, i.e., Eubacterium sulci, Fusobacterium periodonticum, and Neisseria subflava, were present only in low numbers or not detectable. Random forest analysis identified the numerical ecological parameters of the bacterial community, such as Shannon and Simpson diversity, as the key parameters that globally distinguish sputum samples from CF and healthy donors. IMPORTANCE Cystic fibrosis (CF) is the most common life-limiting monogenetic disease in European populations and is caused by mutations in the CFTR gene. Chronic airway infections with opportunistic pathogens are the major morbidity that determines prognosis and quality of life in most people with CF. We examined the composition of the microbial communities of the oral cavity and upper and lower airways in CF patients across all age groups. From early on, the spectrum of commensals is different in health and CF. Later on, when the common CF pathogens take up residence in the lungs, we observed differential modes of depletion of the commensal microbiota in the presence of S. aureus, P. aeruginosa, S. maltophilia, or combinations thereof. It remains to be seen whether the implementation of lifelong CFTR (cystic fibrosis transmembrane conductance regulator) modulation will change the temporal evolution of the CF airway metagenome.

Retention of different temporary cements tested on zirconia crowns and titanium abutments in vitro.

PURPOSE: The aim of the present study was to examine the retention force of monolithic zirconia copings cemented with various temporary cements on implant abutments in vitro. METHODS: Sixty exercise implants with pre-screwed implant abutments were embedded in resin. Subsequently, 60 CAD/CAM manufactured zirconia copings were divided into three main groups [Harvard Implant Semi-permanent (HAV), implantlink semi Forte (IMP), Temp Bond NE (TBNE)]. The zirconia copings were cemented on the implant abutments and loaded with 35 N. Specimens were stored in distilled water (37 °C) for 24 h. Half of the test specimens of each group were subjected to a thermocycling (TC) process. Retention force was measured in a universal testing machine. Using magnifying glasses, the fracture mode was determined. Statistical analysis was performed applying the Kruskal-Wallis test, the post hoc test according to Dunn-Bonferroni and a chi-square test of independence. RESULTS: Without TC, IMP showed the highest retention of the three temporary luting agents (100.5 ± 39.14 N). The measured retention forces of IMP were higher than those of HAV (45.78 ± 15.66 N) and TBNE (61.16 ± 20.19 N). After TC, retention was reduced. IMP showed the greatest retentive strength (21.69 ± 13.61 N, three fail outs). HAV and TBNE showed pull-off forces of similar magnitude (17.38 ± 12.77 N and 16.97 ± 12.36 N, two fail outs). The fracture mode analysis showed different results regarding the tested cements before and after TC (facture type before/after TC): IMP (III+II/III), HAV (I/II) and TBNE (III/III). There were clear differences of the fracture modes regarding the examination before and after TC. CONCLUSIONS: Within the limits of this study, IMP showed the highest pull-off forces under the chosen test conditions. All three temporary luting agents showed lower retention forces after TC. Retention values in the individual cement classes were very heterogeneous. Easy cement removal in the crown lumen favours the dominance of adhesive cement fractures on the abutment and adhesive/cohesive cement fractures on the abutment with HAV appears advantageous in case of recementation of the superstructure.

Ivacaftor Reduces Inflammatory Mediators in Upper Airway Lining Fluid From Cystic Fibrosis Patients With a G551D Mutation: Serial Non-Invasive Home-Based Collection of Upper Airway Lining Fluid.

In cystic fibrosis (CF) therapy, the recent approval of CF-transmembrane conductance regulator (CFTR) channel modulators is considered to be the major breakthrough. However, the current first-line approach based mainly on pulmonary function to measure effects of the novel therapy, tested by forced expiratory volumes in one second (FEV1), provides restricted sensitivity to detect early structural damages. Accordingly, there is a need for new sensitive surrogate parameters. Most interestingly, these should quantify inflammation that precedes a decline of pulmonary function. We present a novel method assessing inflammatory markers in the upper airways' epithelial lining fluid (ELF) obtained by nasal lavage (NL). In contrast to broncho-alveolar lavage, ELF sampling by NL is an attractive method due to its limited invasiveness which allows repeated analyses, even performed in a home-based setting. In a longitudinal cohort study (ClinicalTrials.gov, Identifier: NCT02311140), we assessed changes of inflammatory mediators in 259 serially obtained nasal lavages taken up to every second day before and during therapy with ivacaftor from ten CF patients carrying a G551D mutation. Patients were trained to sample NL-fluid at home, to immediately freeze and transfer chilled secretions to centers. Neutrophil Elastase, Interleukins IL-1ß, IL-6 and IL-8 in NL were quantified. During 8-12 weeks of ivacaftor-treatment, median values of IL-1ß and IL-6 significantly declined 2.29-fold (2.97→1.30 pg/mL), and 1.13-fold (6.48→5.72 pg/mL), respectively. In parallel, sweat tests and pulmonary function improved considerably. This is the first study assessing changes of airway inflammation on a day-to-day basis in CF patients receiving a newly administered CFTR-modulator therapy. It proves a decline of airway inflammation during ivacaftor-therapy.

Desire to Receive More Pain Treatment - A Relevant Patient-Reported Outcome Measure to Assess Quality of Post-Operative Pain Management? Results From 79,996 Patients Enrolled in the Pain Registry QUIPS from 2016 to 2019.

Acute postoperative pain is frequently evaluated by pain intensity scores. However, interpretation of the results is difficult and thresholds requiring treatment are not well defined. Additional patient-reported outcome measures (PROMs) might be helpful to better understand individual pain experience and quality of pain management after surgery. We used data from the QUIPS pain registry for a cross-sectional study in order to investigate associations between the desire to receive more pain treatment (D2RMPT) with pain intensity ratings and other PROMs. Responses from 79,996 patients were analyzed, of whom 10.7% reported D2RMPT. A generalized estimating equation Poisson model showed that women had a lower risk ratio (RR) to answer this question with "yes" (RR: .92, P < .001). Factors that increased the risk most were "maximal pain intensity ≥ 6/10 on a numerical rating scale" (RR: 2.48, P < .001) and "any pain interference" (RR: 2.48, P < .001). The largest reduction in risk was observed if patients were "allowed to participate in pain treatment decisions" (RR: .41, P < .001) and if they felt that they "received sufficient treatment information" (RR: .58, P < .001). Our results indicate that the (easily assessed) question D2RMPT gives additional information to other PROMs like pain intensity. The small proportion of patients with D2RMPT (even for high pain scores) opens the discussion about clinicians' understanding of over- und under-treatment and questions the exclusive use of pain intensity as quality indicator. Future studies need to investigate whether asking about D2RMPT in clinical routine can improve postoperative pain outcome. PERSPECTIVE: This article presents characteristics of the patient-reported outcome measure "Desire to receive more pain treatment." This measure could be used to apply pain treatment in a more individualized way and lead to improved treatment strategies and quality.

Biaxial flexural strength of zirconia: A round robin test with 12 laboratories.

OBJECTIVE: The aim of this interlaboratory round robin test was to prove the robustness of the DIN EN ISO 6872:2019 and to identify the influence of processing and testing variations. METHODS: Each of the 12 laboratories participated (A-L) received 60 (n = 720) assigned zirconia specimens. All participants seperated the specimens from the blanks, sintered them, polished half of all specimens and performed the biaxial flexural test (DIN EN ISO 6872:2019). The surface roughness was determined by using tactile measuring device. Fractographic examination was performed under scanning-electron-microscopy (SEM). Data was analysed using Kolmogorov-Smirnov-, Kruskal-Wallis-, Mann-Whitney-U-test and two-parametric Weibull statistic (p < 0.05). RESULTS: The results for both preparation methods (as-fired and polished) showed significant differences for some participants. The values for as-fired groups ranged between 513 (I) and 659 (E) MPa. H showed higher Weibull modulus than C, E and I. Within polished groups flexural strengths values from 465 (L) to 1212 (E) MPa were observed, with a tendency to clustered groups A, I, J, L (465-689 MPa) and remaining groups (877-1212 MPa). E presented the highest and H the lowest Weibull modulus. Within A and J, no impact of the preparation method on flexural strength values was observed. Within L, as-fired specimens showed higher flexural strength than polished ones. The flexural strength increase did only associate to a certain extent with measured surface roughness. Fractography showed defect populations depending on polishing techniques, associated to the strength level, especially for polished groups. Reduced strength is related to machining defects, regardless of the surface state. SIGNIFICANCE: DIN EN ISO 6872:2019 can be seen as guidance to biaxial flexural strength testing but additional effort is necessary to ensure interlaboratory comparability. Calibrated furnaces and reliable sintering conditions are mandatory requirements together with detailed specifications on finishing or polishing procedures. Biaxial flexural testing is really a matter of understanding specimen preparation, alignment and mechanical testing by itself. DIN EN ISO 6872:2019 should further recommend reporting of mean surface roughness along with any biaxial flexural strength data. Fractography is a mandatory tool in interpretation and understanding of strength data.

Retention Force of Removable Partial Dentures with CAD-CAM-Fabricated Telescopic Crowns.

The aim of this study was to compare the retention forces after artificial aging of telescopic crowns fabricated either by a conventional lost-wax technique or by computer-aided design/computer-aided manufacturing (CAD-CAM) technology. Two types of telescopic crowns (0°) were fabricated conventionally using high-noble (group A) and non-precious metal (group B). CAD-CAM fabricated telescopic crowns (0°) were made of non-precious metal (group C). Retention forces were assessed before and after artificial aging and after axial and non-axial loading. Initially [I.] and after artificial aging [IV.], specimens of group C (I. 16.2 N; IV. 13.6 N) exhibited the highest retention forces. The retention forces in groups B (I. 12.5 N; IV. 4.6 N) and A (I. 9.6 N; IV. 2.9 N) were found to be lower than those of group C. The retention force differences between the groups were statistically significant (p < 0.001) at all measurement times [I. vs. IV.]. Different fabricated telescopic crowns with approximately identical designs and materials exhibited different retention forces and different long-term retentive behavior. An optimized CAD-CAM process with individually defined design parameters ensured telescopic crowns with a better fit. These findings might influence prospective clinical decision-making.

Retentive Force of Glass-Ceramic Soldered Customized Zirconia Abutment Copings with Prefabricated Titanium Bases.

Two-piece abutments consisting of customized zirconia abutment copings and prefabricated titanium bases are popular due to their biological and esthetic advantages. Glass-ceramic solder (GS) is an alternative biocompatible connective agent. This in vitro study evaluated the retentive force of GS in comparison to classical resin composite cements (RC) after artificial aging and autoclaving. Ninety specimens consisting of prefabricated titanium bases and zirconia abutment copings were fabricated. The two parts of each specimen were fixed either by RC (n = 30) or GS with a luting space of either 30 µm (n = 30) or 100 µm (n = 30). Ten specimens of each group underwent autoclaving before artificial aging (water storage, thermocycling). Twenty specimens (including the 10 autoclaved specimens) of each group were exposed to a mechanical load. The retentive force between the zirconia and titanium in all specimens was determined. A fractographic analysis was performed to analyze the fracture surfaces of the GS specimens. The RC- and GS-connected two-piece abutments showed no relevant differences, independent of the luting space. RC appears to be more vulnerable to the thermal and mechanical loads than GS. Thus, GS may be an appropriate alternative to RC for two-piece abutments, especially for patients with enhanced biocompatibility requirements.

Retentive Characteristics of a New Attachment System for Hybrid Dentures.

Removable implant-anchored dentures have become an established treatment concept especially for older, multimorbid patients. This study investigates the retention force (RF) of two different attachment systems. A total of 96 specimens (n = 8 for each condition) were fabricated and RF was measured under different conditions: fatigue (10,000 cycles dislodging), thermal undulation (5/55 °C, 5000 cycles) and implant-angulation (0°, 5°, 10°, 15°, 20°). The Novaloc system ((N), 0° and 15° abutments, yellow matrix (Y)) was compared to the Locator system ((L), pink (P) and orange (O)). Initial RFs (8.57 ± 0.99 N (NY), 19.39 ± 8.10 N (LP), 8.8 ± 5.28 N (LO)) were reduced by ageing simulation (26% (NY), 66% (LP), 89% (LO); p < 0.001). After thermocycling, Novaloc's RFs decreased by 33% (p < 0.001) while the Locators' RFs increased by 34% (LP: p = 0.002, LO: p = 0.148). In contrast to LP, the RFs of Novaloc abutments and LOs predominantly showed no clinically relevant dependence on implant angulation. Ageing processes tended to result in lower RFs at higher implant angulation. Thus, the Novaloc attachment system offers an alternative to Locator attachments. It is characterized by a comparatively continuous RF-curve over the entire wearing period. Future clinical studies have to be conducted to verify the in vitro demonstrated advantages of the Novaloc system.

A cross-sectional survey of attitudes towards education in implant dentistry in the undergraduate dental curriculum.

BACKGROUND: An ongoing debate in dental education is whether implant dentistry, as a multidisciplinary domain, should be integrated into the undergraduate curriculum. The aim of the present study was to evaluate the perspectives of novices, clinical educators, and experienced dentists with regard to the importance of theoretical and practical implant dentistry teaching content in undergraduate dental education. The specific objective was to determine whether a consensus could be found concerning aspects of theoretical knowledge, implant position planning, implantation, prosthetic treatment procedures, postoperative care, and prerequisite experiences that should be provided in undergraduate dental education. RESULTS: A positive consensus existed in terms of theoretical education, assistance in surgical and prosthodontic procedures, implant planning and restoration in straightforward cases (i.e., posterior single crowns and bridges, overdentures on nonconnected implants), and postoperative care. A negative consensus existed for bone augmentation. Implantation was supported by novices (i.e., students and graduates). In addition, more experienced dentists were more likely to oppose implantation performed by undergraduates. The most preferred implantation method was implant insertion using a digitally fabricated drilling template, after surgical flap elevation. CONCLUSIONS: Students and graduates preferred a comprehensive undergraduate education that included implant dentistry. Dentists working in private practice, and especially dentists working as university educators, were critical towards the integration of implant-related learning content into undergraduate education. The intention of medical education is to impart knowledge to students and to prepare them for life-long learning and continual professional development after graduation. Thus, an undergraduate dental curriculum that provides students a solid introduction and knowledge foundation in implant dentistry is recommended.

Surface Quality of 3D-Printed Models as a Function of Various Printing Parameters.

Although 3D-printing is common in dentistry, the technique does not produce the required quality for all target applications. Resin type, printing resolution, positioning, alignment, target structure, and the type and number of support structures may influence the surface roughness of printed objects, and this study investigates the effects of these variables. A stereolithographic data record was generated from a master model. Twelve printing processes were executed with a stereolithography Desktop 3D Printer, including models aligned across and parallel to the printer front as well as solid and hollow models. Three layer thicknesses were used, and in half of all processes, the models were inclined at 15°. For comparison, eight gypsum models and milled polyurethane models were manufactured. The mean roughness index of each model was determined with a perthometer. Surface roughness values were approximately 0.65 µm (master), 0.87-4.44 µm (printed), 2.32-2.57 µm (milled), 1.72-1.86 µm (cast plaster/alginate casting), and 0.98-1.03 µm (cast plaster/polyether casting). The layer height and type and number of support structures influenced the surface roughness of printed models (p ≤ 0.05), but positioning, structure, and alignment did not.

Effect of Disinfectants on Mechanical Properties of Orthodontic Acrylics.

OBJECTIVE: Infection control protocols in dentistry dictate that orthodontic acrylics have to be disinfected. No specific products for orthodontic acrylics are available. The objective of this study was to investigate the influence of chemical disinfectants on mechanical properties of orthodontic acrylics. MATERIALS AND METHODS: 260 test specimens of two cold-curing orthodontic acrylics were manufactured. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, and Stammopur DR. Test specimens were stored in distilled water and divided into test groups. E-Modulus, flexural strength, macro hardness, micro hardness, average roughness, and colour change were measured. RESULTS: Disinfection agents showed no significant influence on E-modulus. Values ranged from 1783.80 ± 163.80 MPa (Forestacryl colourless) to 2474.00 ± 135.00 MPa (Orthocryl green) after storage in distilled water. Disinfection agents performed no significant influence on flexural strength. Values ranged from 18.64±1.59 N/mm2 (Forestacryl colourless) to 25.64 ± 1.43 N/mm2 (Orthocryl green) after storage in distilled water. Orthocryl colourless showed a reduction of the macro hardness after disinfection (Stammopur DR (p≤0.001), D050 Instru-Gen (p≤0.037)). Disinfection of Orthocryl green with D050 Instru-Gen (p<0.001) and Forestacryl colourless with Impresept (p≤0.001) led to a reduction of macro hardness. Micro hardness of Orthocryl colourless altered significantly after disinfection with D050 Instru-Gen (p≤0.001). Micro hardness of Forestacryl colourless increased (Impresept (p≤0.039)) and decreased (Stammopur DR (p≤0.006) Instru-Gen (p≤0.001)) after disinfection. Average roughness did not change significantly (Orthocryl colourless). Forestacryl colourless performed a significant change after disinfection with Stammopur DR (p≤0.05). This is also true for the disinfection of Orthocryl green and Forestacryl pink with Instru-Gen (p≤0.05). Disinfection performed no significant influence on colour change. ΔE-values were in a range of 1 to 2. CONCLUSIONS: Some orthodontic acrylics disinfection caused significant changes of determined parameters. Changes were specific for the applied disinfectant and tested orthodontic acrylic. Further studies should verify the impact of long-term disinfection intervals. Thus, from manufacturers of orthodontic acrylics recommendations for appropriate disinfectants would be desirable.