Cusp Replacement Research Articles

Direct Composite Restorations on Permanent Teeth in the Anterior and Posterior Region - An Evidence-Based Clinical Practice Guideline - Part 1: Indications for Composite Restorations.

This German S3 clinical practice guideline offers evidence-based recommendations for the use of composite materials in direct restorations of permanent teeth. Outcomes considered were the survival rates and restoration quality and process quality of the manufacturing process. Part 1 of this two-part presentation deals with the indication classes. A systematic literature search was conducted by two methodologists using MEDLINE and the Cochrane Library via the OVID platform, including studies up to December 2021. Six PICO questions were developed to guide the search. Recommendations were formulated by a panel of dental professionals from 20 national societies and organizations based on the collected evidence. Composite materials are a viable option for the direct restoration of cavity Classes I-V and may also be used for restorations with cusp replacement, and tooth shape corrections. In the posterior region, direct composite restorations should be preferred over indirect composite inlays. For Class V restorations, composite materials can be used if adequate contamination control and adhesive technique are ensured. The guideline is the first to provide comprehensive evidence on the use of direct composite materials. However, further long-term clinical studies with comparators such as (modified) glass-ionomer cements are necessary. Regular updates will detail the future scope and limitations of direct composite restorations.

Tissue requirements for the application of aortic valve neocuspidization - appropriate pericardium properties and homogeneity?

Aortic valve neocuspidization (AVNeo) using autologous pericardium is a promising technique. Expected advantages are reduced immune response, appropriate biomechanics and lower treatment expenses. Nevertheless, autologous pericardium can be affected by patient's age and comorbidities. Usually, glutaraldehyde (GA) - fixed bovine pericardium is the basic material for aortic valve prostheses, easy available and carefully pre-examined in a standardized fabrication process. Aim of the study is the verification of autologous pericardial tissue homogeneity by analysing tissue thickness, biomechanics and extracellular matrix (ECM) composition. Segments of human GA-fixed pericardium selected by the surgeon based on visual criteria for cusp pre-cut and remaining after surgical AV replacement were investigated in comparison to bovine standard tissue treated equivalently. Pericardium sampling was performed at up to three positions of each sutured cusp for histological or biomechanical analysis, according to tissue availability. Human pericardia exhibited a higher heterogeneity in collagen content, density of vessel structures and elastic moduli. Thickness, vessel density and collagen and elastin content differed significantly between the species. In contrast, significant interindividual differences were detected in most properties investigated for human pericardial samples but only for tissue thickness in bovine tissues. Higher heterogeneity of human pericardium, differing vessel and collagen content compared to bovine state-of-the-art material might be detrimental for long term AV functionality or deterioration and have to be intensely investigated in patients follow up after autologous cusp replacement.

Autologous or bovine pericardium for aortic cusp replacement? Histomorphological and biomechanical properties as decision making tools

Abstract Background/Introduction Aortic valve cusp replacement using autologous pericardium is a promising technique. Expected advantages are reduced immune response, proper biomechanics and lower treatment expenses. During surgery decision for preferred pericardium segment is based on visual criteria. Autologous pericardium can be affected by patient's condition and age. Bovine pericardium, also the basic material for aortic valve prostheses, is easy available and carefully pre-examined. In this study, the homogeneity of tissue thickness, elastic modulus, vessel density and ECM components of GA-treated residual pericardia after surgery is compared with bovine pericardia equivalently treated. Purpose Aim of the study is the comparison of homogeneity of remaining autologous pericardium after surgical aortic valve replacement with bovine pericardia to evaluate and classify the individual applicability. Methods Up to 12 samples of human (n=7) or bovine (n=3) pericardia were analysed. Tissues were treated with 0.6% glutaraldehyde according to surgical protocol. Picrosiriusred- and HE-staining were performed (three edges per separated leaflet). Vessel or collagen content was determined with Zen Blue resp. Fiji software (colour deconvolution plugin, user threshold values). Sample thickness was measured via thickness gauge FD50 before uniaxial tensile testing. Hydroxyproline content was determined and related to dry weight. T-Test or ANOVA were used to test inter-species or intra-individual differences, respectively. Results Human pericardia contain with 64.66±3.85% less collagenous fibres compared to bovine pericardia (86.01±1.713%); their vessel density is with 29.46±3.73 mm–2 significantly higher than in bovine samples (12.34±1.636 mm–2). In addition, human pericardia are with 367.7±59.2 μm significantly thinner than bovine (524.4±96.8 μm). Tensile testing (human: 36.00±15.17 MPa; bovine: 41.30±7.767 MPa) also revealed significant differences. With 77.80±11.76 mg/g merely a trend was observed for a lower hydroxyproline content in human samples (bovine 93.16±5.130 mg/g). ANOVA analyses of human pericardia illustrate significant differences for all properties, thus thickness, elastic modulus and hydroxyproline and collagen content between the individual human pericardium samples. In contrast, bovine pericardia showed an intra-individual difference only for the parameter of tissue thickness. Conclusion Human and bovine pericardia differ in histological and biomechanical parameters. In contrast to bovine pericardia, individual human pericardia were significantly different in most parameters investigated, leading to the conclusion that autologous materials are critically more heterogeneous than xenogeneic tissues. Vessel density in human pericardium was twofold higher than in bovine pericardia and can result in a higher risk for calcification. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): TU Dresden

Twenty-five years' experience with root remodeling and bicuspid aortic valve repair.

BackgroundBicuspid aortic valves may be associated with ascending aortic aneurysm, or develop severe aortic regurgitation with variable aortic dilatation. If aortic dilatation involves the root, valve-preserving root replacement is a treatment option, and we prefer root remodeling for this purpose. The objective of this study is to review our experience encompassing 25 years.MethodsBetween November 1995 and August 2021, 472 patients (429 male; age 9–80 years; mean 48±13 years) were treated by bicuspid aortic valve repair and root remodeling. Aortic regurgitation was present in 322 cases. The primary indication for surgery was aortic regurgitation (n=317), aortic aneurysm (n=143) or acute type A aortic dissection (n=12). In 271 instances, a suture annuloplasty was added. Cusp calcification was present beyond the raphe in 80 cases, and a pericardial patch was used for partial cusp replacement in 44 cases. Follow-up was 92.8% complete with a mean of 71±68 months (median 61 months).ResultsHospital mortality was 0.4% and survival at 20 years was 76.9%. Reoperation was necessary for recurrent aortic regurgitation in 26 patients; nine patients underwent reoperation for stenosis. The overall freedom of reoperation was 90.5% after ten years and 76.6% after 20 years. Annuloplasty was associated with a higher proportion of competent aortic valves at discharge (P=0.001), and had no effect on ten-year freedom from reoperation. The use of a pericardial patch for cusp repair was a predictor for reoperation (P=0.003). The presence of cusp calcification was a predictor for the development of aortic stenosis and reoperation (P=0.032).ConclusionsBicuspid aortic valve repair combined with root remodeling leads to excellent ten- and 20-year results. Cusp calcification and partial cusp replacement are associated with an increased probability of valve failure requiring reoperation.

Post-Fatigue Fracture and Marginal Behavior of Endodontically Treated Teeth: Partial Crown vs. Full Crown vs. Endocrown vs. Fiber-Reinforced Resin Composite.

Objectives: To investigate in vitro post-fatigue fracture behavior of endodontically treated molars having been differently restored. Methods: A total of 120 extracted human molars were used. A total of 120 specimens in 14 test groups and one control group (n = 8) were root canal treated. After postendodontic sealing and build-up (AdheSE Universal, SDR), additional MOD preparations were cut. Postendodontic restorations were: Direct restorations (Tetric EvoCeram BulkFill bonded with AdheSE Universal and EverX Posterior/Essentia bonded with G-Premio Bond; as filling (F) or direct partial crown (DPC) after reducing the cusps 2 mm; indirect adhesive restorations (partial crown/PC vs. full crown/FC): e.max CAD, Celtra Duo, both luted with Variolink Esthetic; indirect zirconia restorations (partial crown/PC vs. full crown/FC), luted with RelyX Unicem 2; indirect non-bonded cast gold restorations (partial crown/PC vs. full crown/FC; Degunorm), luted with Ketac Cem. Before and after 300,000 thermocycles (5/55 °C) and 1.2 Mio. A total of 100 N load cycles, replicas were analyzed under a SEM for marginal quality in enamel and dentin (where applicable) and finally, specimens were loaded until fracture. Results: In direct groups, there was no difference between RC and FRC in fracture strength (p > 0.05); however, direct partial crowns showed higher post-fatigue fracture resistance. Regarding marginal quality, intracoronal FRC restorations exhibited more gap-free margins in enamel than RC. In the indirect groups, there was no significant difference between partial and full crowns in any of the adhesively luted ceramic groups regarding post-fatigue fracture resistance. Zirconia partial crowns exhibited significantly lower marginal quality in enamel. Indirect groups performed significantly better than direct groups in fracture resistance. Within the indirect restorations, both cast gold groups and zirconia full crowns exhibited the highest fracture resistance being superior to control teeth. Significances: Within the limits of this in vitro investigation, it can be concluded that any kind of indirect restoration with cusp replacement is suitable for ETT restoration when a certain cavity extension is exceeded. All indirect restorations, i.e., endocrowns, partial crowns, and full crowns showed a promising performance after in vitro fatigue-loading.

Asporin Reduces Adult Aortic Valve Interstitial Cell Mineralization Induced by Osteogenic Media and Wnt Signaling Manipulation In Vitro.

Worldwide, calcific aortic valve disease is one of the leading causes of morbidity and mortality among patients with cardiac abnormalities. Aortic valve mineralization and calcification are the key events of adult calcific aortic valve disease manifestation and functional insufficiency. Due to heavy mineralization and calcification, adult aortic valvular cusps show disorganized and dispersed stratification concomitant with deposition of calcific nodules with severely compromised adult valve function. Interestingly, shared gene regulatory pathways are identified between bone-forming cells and heart valve cells during development. Asporin, a small leucine-rich proteoglycan (43 kDa), acts to inhibit mineralization in periodontal ligament cells and is also detected in normal murine adult aortic valve leaflets with unknown function. Therefore, to understand the Asporin function in aortic cusp mineralization and calcification, adult avian aortic valvular interstitial cell culture system is established and osteogenesis has been induced in these cells successfully. Upon induction of osteogenesis, reduced expression of Asporin mRNA and increased expression of bone and osteogenesis markers are detected compared to cells maintained without osteogenic induction. Importantly, treatment with human recombinant Asporin protein reduces the mineralization level in osteogenic media-induced aortic valvular interstitial cells with the concomitant decreased level of Wnt/β-catenin signaling. Overall, all these data are highly indicative that Asporin might be a novel biomolecular target to treat patients of calcific aortic valve disease over current cusp replacement surgery.

Congenital aortic and truncal valve reconstruction using the Ozaki technique: Short-term clinical results

ObjectivesAortic valve reconstruction (AVRec) with neocuspidization or the Ozaki procedure with complete cusp replacement for aortic valve disease has excellent mid-term results in adults. Limited results of AVRec in pediatric patients have been reported. We report our early outcomes of the Ozaki procedure for congenital aortic and truncal valve disease. MethodsA retrospective analysis was performed on all 57 patients with congenital aortic and truncal valve disease who had a 3-leaflet Ozaki procedure at a single institution from August 2015 to February 2019. Outcome measures included mortality, surgical or catheter-based reinterventions, and echocardiographic measurements. ResultsTwenty-four patients had aortic regurgitation (AR), 6 had aortic stenosis (AS), and 27 patients had AS/AR. Two patients had quadricuspid valves, 26 had tricuspid, 20 had bicuspid, and 9 had unicusp aortic valves. Four patients had truncus arteriosus. Thirty-four patients had previous aortic valve repairs and 5 had replacements. Preoperative echocardiography mean annular diameter was 20.90 ± 4.98 cm and peak gradient for patients with AS/AR was 53.62 ± 22.20 mm Hg. Autologous, Photofix, and CardioCel bovine pericardia were used in 20, 35, and 2 patients. Eight patients required aortic root enlargement and 20 had sinus enlargement. Fifty-one patients had concomitant procedures. Median intensive care unit and hospital length of stay were 1.87 and 6.38 days. There were no hospital mortalities or early conversions to valve replacement. At discharge, 98% of patients had mild or less regurgitation and peak aortic gradient was 16.9 ± 9.5 mm Hg. Two patients underwent aortic valve replacement. At median follow-up of 8.1 months, 96% and 91% of patients had less than moderate regurgitation and stenosis, respectively. ConclusionsThe AVRec procedure has acceptable short-term results and should be considered for valve reconstruction in pediatric patients with congenital aortic and truncal valve disease. Longer-term follow-up is necessary to determine the optimal patch material and late valve function and continued annular growth.

Results of Pericardial Patches in Tricuspid and Bicuspid Aortic Cusp Repair

Aortic valve repair for aortic regurgitation has become an increasingly accepted alternative to replacement. Some cusp pathologies require partial cusp replacement or augmentation using pericardium. There are limited data on pericardial patch durability. We analyzed our long-term results with pericardial patches in aortic cusp repair to clarify whether durability is influenced by aortic valve morphology or underlying cusp pathology. From 2000 to 2017, 275 patients (mean age, 53 ± 14 years) underwent aortic valve repair involving pericardial patches with tricuspid aortic valve (n= 139, 50.5%) or bicuspid aortic valve (n= 136, 49.5%) morphology. Pericardial patches were used for either central cusp replacement (n= 64, 23%), closure of defects (n= 55, 20%), fenestrations (n= 104, 38%), cusp augmentation (n= 27, 10%), or commissural reconstruction (n= 25, 9%). Follow-up was complete in 96%. Ten-year survival was 85%, and 10-year freedom from reoperation was 53%. Durability was inferior after bicuspid aortic valve repair (37%) compared with tricuspid aortic valve repair (69%; P < .0001). Best 10-year freedom from reoperation was found after closure of fenestrations (73%) and defects (67%). Suboptimal durability was observed after cusp augmentation (44%), central cusp replacement (39%), and commissural reconstruction (16%, P < .001). The results of aortic cusp repair using pericardium depend on valve morphology and cusp pathology. Mid- and long-term durability is reasonable in tricuspid aortic valve repair. In bicuspid aortic valve repair valve stability is poor regardless of cusp pathology and repair technique. For any analysis of patch durability, details of pathology and technique have to be considered.

Two decades of experience with root remodeling and valve repair for bicuspid aortic valves

ObjectiveBicuspid aortic valve anatomy is associated with ascending aortic aneurysm in approximately 50% of individuals and may lead to severe aortic regurgitation with aortic dilatation. Both entities may be treated by valve repair and root remodeling. The objective was to review the cumulative experience of 20 years. MethodsBetween November 1995 and December 2015, 357 patients (324 male; age 10-80 years; mean, 49 ± 13 years) underwent combined bicuspid aortic valve repair and root remodeling. Aortic regurgitation was relevant in 265 cases; the main indications for surgery were aortic regurgitation (n = 241), aortic aneurysm (n = 102), and acute dissection (n = 9). In 225 instances, a suture annuloplasty was added. Cusp calcification was present beyond the raphe in 52 cases, and an autologous pericardial patch was implanted for partial cusp replacement in 39 cases. All patients were followed. Follow-up was 97.8% complete with a mean of 57 ± 51 months (median, 39 months). ResultsTwo patients died (hospital mortality 0.6%), and survival at 15 years was 81%. Reoperation became necessary for recurrent aortic regurgitation in 24 patients; 6 patients underwent reoperation for stenosis. Cumulative incidence of reoperation at 15 years was 21.7%. Cusp calcification and the use of a pericardial patch for cusp reconstruction were associated with time to reoperation (P = .002). ConclusionsRepair of the bicuspid aortic valve combined with root remodeling leads to excellent 10- and 15-year results. Cusp calcification and the need for partial cusp replacement are associated with valve failure.

Planar biaxial testing of heart valve cusp replacement biomaterials: Experiments, theory and material constants.

Aortic valve (AV) repair has become an attractive option to correct aortic insufficiency. Yet, cusp reconstruction with various cusp replacement materials has been associated with greater long-term repair failures, and it is still unknown how such materials mechanically compare with native leaflets. We used planar biaxial testing to characterize six clinically relevant cusp replacement materials, along with native porcine AV leaflets, to ascertain which materials would be best suited for valve repair. We tested at least six samples of: 1) fresh autologous porcine pericardium (APP), 2) glutaraldehyde fixed porcine pericardium (GPP), 3) St Jude Medical pericardial patch (SJM), 4) CardioCel patch (CC), 5) PeriGuard (PG), 6) Supple PeriGuard (SPG) and 7) fresh porcine AV leaflets (PC). We introduced efficient displacement-controlled testing protocols and processing, as well as advanced convexity requirements on the strain energy functions used to describe the mechanical response of the materials under loading. The proposed experimental and data processing pipeline allowed for a robust in-plane characterization of all the materials tested, with constants determined for two Fung-like hyperelastic, anisotropic strain energy models. Overall, CC and SPG (respectively PG) patches ranked as the closest mechanical equivalents to young (respectively aged) AV leaflets. Because the native leaflets as well as CC, PG and SPG patches exhibit significant anisotropic behaviors, it is suggested that the fiber and cross-fiber directions of these replacement biomaterials be matched with those of the host AV leaflets. The long-term performance of cusp replacement materials would ideally be evaluated in large animal models for AV disease and cusp repair, and over several months or more. Given the unavailability and impracticality of such models, detailed information on stress-strain behavior, as studied herein, and investigations of durability and valve dynamics will be the best surrogates, as they have been for prosthetic valves. Overall, comparison with Fig. 3 suggests that CC and SPG (respectively PG) patches may be the closest mechanical equivalents to young (respectively aged) AV leaflets. Interestingly, the thicknesses of these materials are close to those reported for porcine and younger human AV leaflets, which may facilitate surgical implantation, by contrast to the thinner APP which has poor handling qualities. Because the native leaflets as well as CC, PG and SPG patches exhibit anisotropic behaviors, from a mechanistic perspective alone, it stands to reason that cardiac surgeons should seek to intraoperatively match the fiber and cross-fiber directions of these replacement biomaterials with those of the repaired AV leaflets.

Oxidation of sitosterol and transport of its 7-oxygenated products from different tissues in humans and ApoE knockout mice

The most common phytosterols in the human diet are sitosterol and campesterol, which originate exclusively from plant derived food. These phytosterols are taken up by NPC1L1 transport from the intestine into the enterocytes together with cholesterol and other xenosterols. Phytosterols are selectively pumped back from the enterocytes into the intestinal lumen and on the liver site from hepatocytes into bile by heterodimeric ABCG5/G8 transporters. Like cholesterol, both phytosterols are prone to ring and side chain oxidation. It could be shown that oxyphytosterols, found in atherosclerotic tissue, are most likely of in situ oxidation (Schött et al.; Biochem. Biophys. Res. Commun. 2014 Apr 11;446(3):805-10). However, up to now, the entire mechanism of phytosterol oxidation is not clearly understood. Here, we provide further information about the oxidation of sitosterol and the transport of its oxidation products out of tissue. Our survey includes data of 104 severe aortic stenosis patients that underwent an elective aortic valve cusp replacement. We studied their phytosterol concentrations, as well as absolute and substrate corrected oxyphytosterol levels in plasma and valve cusp tissue. In addition, we also examined phytosterol and oxyphytosterol concentrations in plasma and tissues (from brain and liver) of 10 male ApoE knockout mice. The ratio of 7-oxygenated-sitosterol-to-sitosterol exceeds the ratio for 7-oxygenated-campesterol-to-campesterol in plasma and tissue of both humans and mice. This finding indicates that sitosterol is oxidized to a higher amount than campesterol and that a selective oxidative mechanism might exist which can differentiate between certain phytosterols. Secondly, the concentrations of oxyphytosterols found in plasma and tissue support the idea that oxysitosterols are preferably transported out of individual tissues. Selective oxidation of sitosterol and preferred transport of sitosterol oxidation products out of tissue seem to be a metabolic pathway of forced sitosterol clearance from tissue compartments.

Complete Aortic Valve Cusp Replacement in the Pediatric Population Using Tissue-Engineered Bovine Pericardium

Three clinical cases of severe pediatric aortic valve defects undergoing complete aortic valve cusp replacement using tissue-engineered bovine pericardium are reported. All patients achieved excellent early results, and are being followed without complications.

MODELING AORTIC VALVE INSUFFICIENCY AND AORTIC VALVE REPAIR: APPLICATIONS FROM BENCH TO THE OPERATING ROOM

Aortic valve repair(AVr) has become an attractive alternative for the correction of aortic insufficiency(AI) as compared to aortic valve replacement; however, little information exists regarding the effects of acute AI and subsequent AV repair(AVr) on ventricular and valvular dynamics. The objective of this study was to measure and compare hemodynamic and echocardiographic properties in a novel, ex-vivo model of severe acute AI due to cusp pathology followed by valve repair. Porcine aortic roots with intact aortic valves were placed in a left heart simulator mounted with a high-speed camera for baseline hemodynamic assessment. 3-D echocardiography was used to evaluate valve function, AI, and leaflet coaptation (coaptation surface area [CoSA]). In the first model, an 8mm diameter circular perforation was created in the body of the non-coronary cusp (NCC) leaving an intact free margin(AI “lesion” assessment) followed by patch repair (AVr “treatment” assessment). In the second model, 75% of the NCC was excised followed by cusp replacement with a pericardial patch. Hemodynamic and echocardiographic data are expressed as medians with interquartile ranges. Finite element modeling (FEM) was performed in both models to understand stress characteristics. Wilcoxon-signed rank tests were used to determine significance between paired sample experiments. The cusp perforation model demonstrated a significant increase in the regurgitant fraction (RF) after AI was created (control= 5.2 [5,5.6] % versus AI= 50.1 [49,53] %; p=0.04) and returned to baseline “control” levels after AVr (AVr= 11.7 [7.1,11.8] %; p=0.14). The cusp excision and repair model demonstrated a significant increase in RF after AI was created (control= 4.8 [3.2,9.1]% versus AI = 69.6 [69.2,75.3]%; p=0.04) but returned to baseline with valve repair “treatment” (AVr= 10.4[9.7,11] %; p=0.5). Furthermore, CoSA was significantly reduced after creation of AI (1.54cm2 versus 1.14[0.75,1.18] cm2; p=0.04) which then returned to baseline levels after AVr (1.54cm2 versus 1.59cm2; p=0.68). Finally, after comparing all hemodynamic parameters after valve repair in both models, there was no significant difference. Figure 1 summarizes the findings with FEM. We successfully simulated acute AI and effective repair due to clinically relevant cusp pathology in an ex-vivo left heart simulator along with 3-D echocardiography. After valve repair, both models demonstrated similar leaflet stress changes (+24% increase) suggesting that no matter the intervention, the repaired cusp retains major stress; making it more vulnerable to failure. Further investigation using this reproducible ex-vivo protocol with FEM will help reveal optimal therapeutic options in more complex models of AI.

Single cusp replacement in patients with ventricular septal defect and aortic insufficiency.

The aim of this study was to analyze the mid- and long-term outcome of single cusp replacement in patients with ventricular septal defect and aortic insufficiency. From September 2005 through March 2014, 172 patients underwent single cusp replacement and ventricular septal defect (VSD) closure. The median age was 19.5 years (range, 9 months to 67 years). Additional techniques were used to repair associated anomalies including sinus of Valsalva aneurysm, patent ductus arteriosus, patent foramen ovale, subaortic membrane, and intramural coronary artery. One patient with large left ventricle (preoperative end-diastolic diameter: 9.8 cm) died after the procedure from incurable heart failure. Four patients required a second pump run for residual aortic insufficiency (AI) (two patients, 1.16%) and residual VSD (two patients, 1.16%). Four patients required re-exploration for postoperative bleeding or cardiac tamponade. Mean follow-up was 53.27 ± 25.37 months (median, 56.5 months; range, 3 to 104 months). Redo aortic valve surgery was performed in three patients. Three patients had moderate-severe AI during the following period without reoperation. There was no post-operative endocarditis. Single cusp replacement can be safely used in patients with VSD-AI.

Examination of ceramic restoration adhesive coverage in cusp-replacement premolar using acoustic emission under fatigue testing.

BackgroundThis study investigates CAD/CAM ceramic cusp-replacing restoration resistance with and without buccal cusp replacement under static and dynamic cyclic loads, monitored using the acoustic emission (AE) technique.MethodThe cavity was designed in a typical MODP (mesial-occlusal-distal-palatal) restoration failure shape when the palatal cusp has been lost. Two ceramic restorations [without coverage (WOC) and with (WC) buccal cuspal coverage with 2.0 mm reduction in cuspal height] were prepared to perform the fracture and fatigue tests with normal (200 N) and high (600 N) occlusal forces. The load versus AE signals in the fracture and fatigue tests were recorded to evaluate the restored tooth failure resistance.ResultsThe results showed that non-significant differences in load value in the fracture test and the accumulated number of AE signals under normal occlusal force (200 N) in the fatigue test were found between with and without buccal cuspal coverage restorations. The first AE activity occurring for the WOC restoration was lower than that for the WC restoration in the fracture test. The number of AE signals increased with the cyclic load number. The accumulated number of AE signals for the WOC restoration was 187, higher than that (85) for the WC restoration under 600 N in the fatigue test.ConclusionThe AE technique and fatigue tests employed in this study were used as an assessment tool to evaluate the resistances in large CAD/CAM ceramic restorations. Non-significant differences in the tested fracture loads and accumulated number of AE signals under normal occlusal force (200 N) between different restorations indicated that aggressive treatment (with coverage preparation) in palatal cusp-replacing ceramic premolars require more attention for preserving and protecting the remaining tooth.

Finding the ideal biomaterial for aortic valve repair with ex vivo porcine left heart simulator and finite element modeling

Aortic valve (AV) repair (AVr) has become an attractive alternative to AV replacement for the correction of aortic insufficiency; however, little clinical evidence exists in determining which biomaterial at AVr would be optimal. Cusp replacement in AVr has been associated with increased long-term AVr failure. We measured the hemodynamic and biomaterial properties using an ex vivo porcine AVr model with clinically relevant biomaterials and generated a finite element model to ascertain which materials would be best suited for valve repair. Porcine aortic roots with intact AVs were placed in a left heart simulator mounted with a high-speed camera for baseline valve assessment. The noncoronary cusp was excised and replaced with autologous porcine pericardium, glutaraldehyde-fixed bovine pericardial patch (Synovis), extracelluar matrix scaffold (CorMatrix), or collagen-impregnated Dacron (Hemashield). The hemodynamic parameters were measured for a range of cardiac outputs (2.5-6.5 L/min) after repair. The biomaterial properties and St Jude Medical pericardial patch were determined using pressurization experiments. Finite element models of the AV and root complex were constructed to determine the hemodynamic characteristics and leaflet stresses. The geometric orifice areas after repair were significantly reduced in the Hemashield (P<.05) and CorMatrix (P=.0001) groups. Left ventricular work increased with increasing cardiac output (P=.001) in unrepaired valves, as expected, and was similar among all biomaterial groups. Finite element modeling of the biomaterials displayed differences in the percentage of changes in total Von Mises stress for both replaced (noncoronary cusp) and nonreplaced left and right cusps with the St Jude Medical pericardial patch (+4%, +24%) and autologous porcine pericardium (+5, +26%), with a lower percentage of changes than for the bovine pericardial patch (+12%, +27%), Hemashield (+30%, +9%), and CorMatrix (+13%, +32%). The present study has shown that postrepair left ventricular work did not increase despite a decrease in geometric orifice areas in the Hemashield and CorMatrix groups. The autologous porcine pericardium and St Jude Medical pericardial patch had the closest profile to normal AVs; therefore, either biomaterial might be best suited. Finally, the increased stresses found in the bovine pericardial patch, Hemashield, and CorMatrix groups might, after prolonged tensile exposure, be associated with late repair failure.

Abstract 18226: Finding the Ideal Biomaterial for Aortic Valve Repair

Objectives: Cusp replacement in aortic valve repair (AVr) is associated with increased long-term repair failure. We measured hemodynamic and biomaterial properties after porcine AVr with 4 types of clinically relevant biomaterials to ascertain which material(s) would be best suited for repair. Methods: Porcine aortic roots with intact aortic valves were placed in a left heart simulator mounted with a high-speed camera for baseline valve assessment. The non-coronary cusp (NCC) was excised and replaced with autologous porcine pericardium (APP), glutaraldehyde-fixed bovine pericardial patch (BPP; Synovis™), extracelluar matrix scaffold (CorMatrix™), or collagen-impregnated Dacron (HEMASHIELD™). Biomaterial properties, along with St. Jude Medical™ Pericardial Patch with EnCapTM Technology (SJM), were determined and finite element modeling of the aortic valve and root complex were constructed to determine hemodynamic characteristics and leaflet stresses. Results: Post-repair geometric orifice areas were significantly reduced in the HEMASHIELD™ (5.06 cm2 [4.24-5.73];P&lt;0.05), and CorMatrix™ ( 5.27 cm2 [4.57-5.56]; P=0.0001) groups when compared to unrepaired valves (6.08 cm2 [5.82-6.83]). Finite element modeling of biomaterials displayed differences in percent changes in total Von Mises stress for both repaired (NCC) and non-repaired left and right cusps with SJM (+4%,+24%) and APP (+5,+26%) having lower percent changes than BPP (+12%,+27%), HEMASHIELD™ (+30%,+9%), and CorMatrix™ (+13%,+32%) when compared to unrepaired valve stresses (Table 1). Conclusions: Due to increased stresses found in bovine pericardial patch, HEMASHIELD™, and CorMatrix™ groups, these biomaterials may be associated with late repair failure in AVr. Finally, autologous porcine pericardium and St. Jude Medical™ Pericadial Patch have the closest profile to normal aortic valves; therefore, use of either biomaterial may be best suited.

Finding the Ideal Biomaterial for Aortic Valve Cusp Repair

Cusp replacement in aortic valve repair (AVr) is associated with increased long-term repair failure. We measured hemodynamic and biomaterial properties after porcine AVr with 4 types of clinically relevant biomaterials to ascertain which material(s) would be ideal.

Aortic Valve Repair—Current Status, Indications, and Outcomes

Aortic valve repair is a new development with old roots. In the past 20 years, marked progress has been made in understanding the normal anatomy of the aortic valve and the interrelation between cusps and root. Aortic dilatation is the single most frequent pathogenetic factor in aortic regurgitation, accompanied by cusp pathology, that is, prolapse or congenital anomaly in most industrialized countries. Frequently, aortic and cusp pathology coexist. Different operative techniques have been established for correction of aortic and cusp pathology. Experience has shown that the combined application of repair procedures will lead to good results if normal valve and cusp configuration is achieved. Some congenital anomalies may require design alteration of the aortic valve. Low-operative mortality rates have been reported consistently. When adequate repair durability is achieved, the incidence of valve-related complications is lower than what has been reported for valve replacement. Aortic valve repair is currently in transition from surgical improvisation to a reproducible operation and an option for many patients with aortic regurgitation. Current research focuses on some special aspects, such as stabilization of the basal ring, ideal material and technique for cusp replacement, and more objective information on ideal valve configuration.

3f Prosthesis Aortic Cusp Replacement: Implantation Technique and Early Results

Stentless aortic bioprostheses have been successfully used for over a decade. The 3f bioprosthesis is a new equine pericardial stentless valve, unique in its tubular design, preserving the native aortic sinuses post-implant. Forty-six consecutive aortic valve replacements with the 3f bioprosthesis were performed between June 2003 and January 2005. The patients were prospectively assessed and echocardiography was performed at 6 months, 12 months, and annually thereafter. The median follow-up was 2.1 + or - 0.9 years. There was one early and 4 late deaths; none were valve-related. The 2-year mean transvalvular gradient was 8.8 + or - 3.8 mm Hg, the mean echocardiographic aortic regurgitation grade was 0.4 + or - 0.7 (grade 1 being trivial). Echocardiographic sizing of the aortic annulus before surgery accurately predicted prosthesis size. The 3f bioprosthesis is easy to implant. Early clinical results are favorable, with hemodynamic profiles consistent with those of other stentless prostheses. Longer follow-up is required to confirm its durability.