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This study evaluates the fatigue resistance and failure mode of CAD/CAM composite resin and lithium disilicate–bonded screw-retained incisor crowns with long and short titanium bases. Sixty CAD/CAM implant restorations were fabricated using lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) and composite resin (Block HC, Shofu). The central incisor crowns were bonded to a prefabricated titanium base 6 mm tall (groups: Emax6 and Shofu6; n = 15 each) or a modified abutment 4 mm tall (groups: Emax4 and Shofu4; n = 15 each). The intaglio surface of the restorations was conditioned according to the material and bonded to the titanium abutments/ bases using dual-cure cement. All assembled crowns were torqued onto implants and subjected to cyclic isometric loading at the incisal edge along the implant axis. Samples were loaded until fracture. Groups were compared using Kaplan-Meier survival analysis (log rank test at P = .05). The number of mean survived cycles differed significantly, with Emax6 and Emax4 at 48,448 and 43,727 cycles, respectively, and Shofu6 and Shofu4 at 44,124 and 37,620 cycles, respectively. Post hoc tests showed similar fatigue resistance for Emax6, Emax4, and Shofu6. Shofu4 was less resistant than all other groups (P < .03). All restorations survived significantly above physiologic load limits. Lithium disilicate screw-retained incisor crowns can be used with long and short titanium bases, while it is recommended to keep a long titanium base for screw-retained composite resin crowns. The composite resin material required the full height of the abutment for optimal strength but may offer enhanced shock absorption and wear-friendliness when considering function and antagonistic wear. [ABSTRACT FROM AUTHOR]

Although it is generally accepted that a prosthetic restoration must take into account the gingiva, smile, and patient's face, it is often difficult to determine precisely what facial references must be considered. The purpose of this study was to determine the correct vertical and horizontal facial reference planes in esthetic prosthetic treatment. Using photographic analysis of 160 individuals, the different facial reference planes (interpupillary, intermeatic, intercommissural, and incisal edge lines; facial midline; and Camper and Frankfort planes) were compared to the ideal prosthetic reconstruction axis. Additional measurements, including the human eye's ability to perceive parallelism, were recorded. Most participants (64%) exhibited facial asymmetry. Asymmetry was horizontal (difference between widths of the right and left sides; 52.4%), vertical (difference between heights of the right and left sides; 6.9%), or mixed (4.7%). The interpupillary line is the main horizontal reference in 88.4% of situations, with the intercommissural line the second most important. In the profile view, the horizontal plane was on average 6.5 degrees above the Camper plane and 9 degrees below the Frankfort plane. The human eye's ability to perceive parallelism between two lines was found to be limited to differences of approximately 1 degree. During anterior tooth reconstruction, it is necessary to take into account the right horizontal and vertical esthetic references. Knowledge of the biometric facial parameters in natural dentition is necessary to define the right reconstruction axes based on the facial symmetry or asymmetry. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study is to assess the shrinkage‐induced cuspal deformation and strength of large MOD restorations using three different short fiber‐reinforced composite resins (SFRC). Materials and Methods: Twenty‐seven typodont teeth #30 (Columbia) received a standardized slot‐type preparation (5‐mm by 5‐mm depth and bucco‐palatal width). Three types of SFRCs (everX Posterior, everX Flow, and a 50/50 mixture of both materials) were used with the Optibond FL bonding system. The intercuspal distance of each specimen (n = 9) was measured after preparation, immediately after restoration and at 3, 18, and 24 h. Each specimen was then subjected to simulated mastication (30° angulation with cyclic loading of buccal cusp at 5 Hz), starting at 100 N with 100 N increase every 100 cycles until fracture. Failure mode was determined as re‐restorable versus nonrestorable failures. Cusp deformation data were analyzed by two‐way repeated measures ANOVA and the fracture performance by Kaplan–Meier survival analysis. Results: Shrinkage‐induced cuspal deformation ranged from 27–34 microns (immediately) to 33–43 microns (24 h). The largest deformations were observed for everX Flow and the 50/50 mixture (up to 43 microns at 24 h), which also demonstrated the lowest average strength (1456 to 1511 N). everX Posterior demonstrated the least amount of shrinkage‐induced cuspal deformation (27 microns, up 33 microns at 24 h) and the higher average strength (1744 N). everX Flow tended to demonstrate more repairable partial fractures while everX Posterior induced mainly catastrophic failures. Conclusions: Large direct MOD restorations were most favorably restored with everX Posterior (less shrinkage, higher strength) at the expense of failure mode. everX Flow induced more friendly failure modes but more shrinkage‐induced cuspal deformation. Clinical Significance: When a low‐cost restoration must be chosen, EverX Posterior will significantly improve the performance but not the failure mode of directly layered restorations. Because of its increased shrinkage values, everX Flow is best indicated as a limited liner to cover the IDS layer and improve geometry for semi‐(in)direct restorations. [ABSTRACT FROM AUTHOR]

Crown width/length ratios have been considered an important aspect in the esthetic zone. Because previous investigations focused on Caucasian populations, limited information is available on other ethnic groups to propose a comprehensive approach to anterior maxillary teeth. The purpose of this study was to analyze the dimensions of anatomical crowns of maxillary anterior tooth groups with respect to width, length, and width/length ratios among an Asian population. The tooth dimensions presented in this investigation may serve as guidelines for treatment planning in restorative dentistry and periodontal surgery for this particular ethnic group. [ABSTRACT FROM AUTHOR]

A thorough understanding of the histoanatomic structures and dynamic light interaction of the natural dentition provides dental practitioners with the ultimate strategic advantage with regard to optical integration of the final restoration. The first part of this article will attempt to provide insight on the threedimensional coronal configuration of natural teeth and on the utilization of this knowledge in the clinical and technical restorative approach. The main goals for this article are to identify and reveal previously unreported histo-anatomic interrelationships and to explain existing ones: the sigmoid curve distribution (convex enamel/ concave dentin), the distinction between dentinoenamel "junction" (DEJ, visual interface) and dentinoenamel "complex" (DEC, functional interphase), and the structural significance of DEC preservation. [ABSTRACT FROM AUTHOR]

The article presents a case of a female patient with existing porcelain-fused-to-metal crowns and darkening of the gingiva that surrounds the restorations. It says that the so-called umbrella effect was produced by the metal substructure and dark fundamental dentin. It state that the umbrella effect was settled by combination of adhesively retained core buildups, walking bleach technique, and porcelain jacket crowns. This approach allowed for maximum conservation of intact tooth substance. Furthermore, it presents the integrated use of the refractory die method in an alveolar cast. A brief overview of metal-free porcelain restorations is also offered.

Objectives: To assess the influence of restorative materials and load cusps on the fatigue resistance of endodontically treated molars. Method and Materials: Thirty extracted molars received root canal treatment followed by a standardized tooth preparation (3-mm cuspal reduction and immediate dentin sealing). Twenty Cerec 3 overlays (Sirona Dental Systems) were milled in the ceramic Vita MKII block (Vident; groups MKIIGL and MKIIGL-Z, oven-glazed), and 10 restorations were duplicated with a composite resin (Miris 2, Coltène/Whaledent; group M2). The fitting surfaces of the restorations were hydrofluoric acid etched (porcelain only) and silanated. Preparations were airborne-particle abraded and etched. All restorations were luted with preheated Filtek Z100 (3M ESPE) and subjected to cyclic isometric chewing (5 Hz) starting at 200 N (5,000 cycles), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 cycles each. A stainless steel load sphere was used for groups MKIIGL and M2, while a composite resin load sphere was used in group MKIIGL-Z. All samples were loaded until fracture or to a maximum of 185,000 cycles. Groups were compared using the Kaplan-Meier survival curves (P = .05). Results: None of the molars restored with porcelain withstood all 185,000 loading cycles (survival = 0%). The mean fracture load for MKIIGL was 1,060 N and for MKIIGL-Z, 1,280 N. In group M2, the survival rate was 50%. The rate of fracture below the CEJ was 40%, 30%, and 20% for MKIIGL, MKIIGL-Z, and M2, respectively. Conclusion: Miris 2 overlays showed higher fatigue resistance than MKII porcelain (P = .01) when loaded with a stainless steel antagonist. [ABSTRACT FROM AUTHOR]

The objective of this investigation was to present a novel method to facilitate and accelerate geometry acquisition/modification during the fabrication of finite element models of tooth restorations. Microcomputed tomographic data, stereolithography, and surface-driven automatic meshing were used to generate premolar finite element models with different occlusoproximal cavity preparations and corresponding composite resin restorations. Occlusal loading was simulated by nonlinear contact analysis. Cuspal widening was measured and correlated with existing experimental data for model validation. Cuspal widening during application of a 150-N load ranged from 2.7 μm for the unrestored tooth to 5 to 179 μm for the different preparations and 3.5 to 6.9 μm for the different restorations. The described method was efficient and generated detailed and valid three-dimensional finite element models. These models were used to study the effect of restorative procedures on cuspal deflection and revealed high cuspal strains associated with mesio-occlusodistal preparations and restorations compared to individual two-surface preparations. This study confirmed that, whenever possible during removal of interdental decay, an intact marginal ridge should be maintained to avoid three-surface preparations such as the mesio-occlusodistal and the high cuspal strain associated with this design. [ABSTRACT FROM AUTHOR]

The article offers information on the alveolar model, a nature-inspired, innovative technique that can be used during the laboratory fabrication of all traditional and contemporary fixed dental restorations. It presents a step-by-step procedure to create the alveolar model including the examination of voids or irregularities in the polyvinyl siloxane dental impression, duplicating the alpha die in a small cylinder through the use of addition-reaction silicone, and fabricating the dentogingival alveolar cast by pouring type IV gypsum into the impression. Furthermore, the alveolar model maintains an unaltered dentogingival perspective during the fabrication of the dental restoration and ensures psychologic, functional, and esthetic integration of the final dental restorations.

Objective: To evaluate the optical integration of 4 contemporary composite resin materials used for incisoproximal restorations and the natural layering concept. Method and Materials: Miris 2 (M2; Coltene Whaledent), Gradia Direct (GD; GC), Enamel Plus HFO (HFO; Micerium), and Filtek Supreme Plus (FSP; 3M ESPE) composite resins were used to consecutively restore 6 extracted incisors with incisoproximal restorations using the natural layering concept, mimicking the natural anatomy of the tooth with only 2 composite resin masses (dentin and enamel). Following each restoration, the specimen was allowed to rehydrate for 2 weeks and was then photographed under standardized conditions (direct, indirect, and fluorescent lights). Six independent evaluators scored each light condition using an optical integration score on a scale from 1 to 4 (1 = worst optical integration, restoration can be easily distinguished from remaining tissues; 4 = optimal optical integration, restoration "invisible"). Mean optical integration scores (from the 6 evaluators) were analyzed with a 2-way analysis of variance (ANOVA) (composite resin brand and light condition). Pooled data of M2 and HFO (single-hue systems) and GD and FSP (multiplehue systems) were also analyzed with a 2-way ANOVA (shade system and light condition). Results: M2 obtained the highest optical integration scores (P < .03), followed by GD and HFO (not significantly different, P = .99). FSP showed the least favorable optical behavior (P < .0001), which is explained in part by the lack of fluorescence and possible inappropriateness for use with the natural layering technique. Single-hue systems (M2 and HFO) achieved better optical integration (P < .02) compared to multihue systems (GD and FSP). Conclusions: For M2, the simplified natural layering concept produced incisoproximal restorations with excellent optical integration. GD and HFO are also suitable for this technique. FSP failed to produce acceptable optical integration in the present study. [ABSTRACT FROM AUTHOR]

This study used 2-D finite element modeling to simulate cuspal flexure and stresses at the surface and tooth-restoration interface of a restored maxillary molar using three restorative materials; the influence of four inlay/onlay preparation configurations on stress distribution within the complex was also investigated. A buccolingual cross-section of an intact molar was digitized and used to create 2-D models restored with different restorative materials (feldspathic porcelain, high- and low-elastic modulus composites) and tooth preparations (small and large inlays, small and large onlays). Two simulated 25-N oblique loads were applied to the cusps. The tangential stress for each finite element node located at the tooth surface, interfacial stress, and relative cuspal flexure were analyzed. All materials and tooth preparations exhibited similar surface tangential stress patterns, with a definite compressive area at the external cusp ridges, a tensile zone at the occlusal surface, and compression stress peaks at the CEJ. The low-elastic modulus composite showed reduced tensile stresses at its surface but increased tension at the dentin-adhesive interface when compared to ceramics. All types of onlays demonstrated a majority of compressive interfacial stresses, while inlays showed a majority of tensile stresses. The interfacial tension at the dentin level increased with the flexibility of the restorative material. Only the large ceramic onlay displayed almost pure compression at the interface. Composite-restored teeth exhibited increased crown flexure, while porcelain-restored teeth showed increased crown stiffness. Porcelain inlays/onlays featured more detrimental stresses at the occlusal surface but better potential protection against debonding at the dentin-restoration interface compared to composite inlays/onlays. Ceramic onlays/overlays seem to represent an effective answer to restore severely damaged posterior teeth. [ABSTRACT FROM AUTHOR]

Purpose: This study was conducted to optimize the interdental design (wraparound) of porcelain laminates bonded to teeth in the presence of preexisting composite fillings. Materials and Methods: A finite element model (2-dimensional mesh generated from a horizontal cross section of a maxillary incisor) was used to evaluate the effects of luting composite shrinkage and thermal changes on the stress distribution within the ceramic. The mesh included 3 restorative designs (3 degrees of interdental wrapping) and a Class III composite filling. Curing contraction of the luting composite was simulated at baseline temperature (37°C). Thermal loads from 37 to 60°C and from 37 to 5°C were assessed with and without preexisting composite shrinkage. Surface tangential stresses were calculated at the ceramic surface and interface. Results: Curing contraction alone generated mostly compressive stresses (peaks at 15 MPa) at both the ceramic surface and interface. Stresses remained compressive (peaks at 20 MPa) when thermal changes were added, except for the conservative veneer with minimum wraparound, the margins of which showed potentially harmful tensile stress peaks (≈ 7 MPa). Deformation of the tooth-restoration complex tended to be more uniform for veneers with maximum wraparound. In the presence of thermal loads alone, opposite effects were observed on the restoration surface and the interface, with compressive stresses on one side (up to 13 MPa) and tensile stresses on the other (up to 9 MPa). This effect of proximal bending (explained by the nearby expansion/contraction of the composite filling) was attenuated by the significant reduction of the bulk of the preexisting interdental composite by the overlapping veneer. Conclusion: In the finite element environment, the negative effect of the nearby expanding/contracting composite fillings can be minimized by extending the veneer over the preexisting interdental restoration. Because of the precompressed state resulting from composite shrinkage, ceramics showed lower temperature-induced tensile stresses. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate in vitro the vertical seating of computer-assisted design/computer-assisted manufacturing (CAD/CAM) composite resin inlays, on-lays, and overlays luted with two different composite resins. Materials and methods: Sixty plastic typodont molars were prepared for medium-sized MOD inlays, anatomic onlays, and flat overlays (n = 20); 3-mm thick at the central groove with similar morphology (Cerec biogeneric copy). Restorations were milled using Lava Ultimate blocks, and included standardized hemispherical occlusal concavity for seating measurements with an electromechanic system (force = 30 N). Restorations were luted either with preheated composite resin (Filtek Z100) or dual-cure resin cement (RelyX Ultimate). Seating of restorations was first evaluated at try-in (baseline). Seating was reevaluated after airborne-particle abrasion (Step 1), after seating with luting agent (Step 2), and after light polymerization (Step 3). The Friedman test followed by the Wilcoxon post hoc test were used to compare the seating among steps, and the Kruskal-Wallis test followed by the Mann-Whitney post hoc test were used to compare the seating between luting agents at P < 0.05. Results: Seating differences varied significantly from baseline (P < 0.0125). All restorations seated 3.85 pm (inlays) to 5.45 pm (onlays) deeper after airborne-particle abrasion (Step 1) (P < 0.007). Except for cement-luted inlays, the try-in position (=i-_1 pm) was recovered following unpolymerized luting (Step 2). After polymerization (Step 3), onlays and overlays seated 2.9 to 3.9 pm deeper than during try-in (baseline) using Z100 (P < 0.005), and 7.0 to 7.3 pm deeper using RelyX (P = 0.005). Inlays luted with RelyX seated higher than during try-in (baseline), exactly 7.9 pm after Step 2 (P = 0.005), and 7.7 pm after Step 3 (P = 0.008). Luting with Z100 sustained the seating of inlays with no statistical difference when compared to baseline (P = 0.157). Conclusion: Airborne-particle abrasion significantly deepens the seating of CAD/CAM composite resin restorations, but the presence of unpolymerized restorative composite resin luting agent perfectly compensates for this discrepancy. Following polymerization, onlays and overlays seat deeper compared to inlays, especially when using RelyX. The latter, however, resulted in a slightly higher seating of inlays. Clinical significance: With the least varia tion compared to baseline seating (try-in), restorative composite resin used as luting agent resulted in the seating of CAD/CAM inlays, onlays, and overlays closer to baseline when compared to dual-cure resin cement. [ABSTRACT FROM AUTHOR]

Adhesive procedures have changed the way to restore endodontically treated teeth (ETT). It started with the shift from cast post-and-core to fiber post. The original focus on strength also shifted towards failure modes, revealing that catastrophic failures are still a concern when restoring endodontically-treated teeth even with fiber posts. As an alternative, postless approaches have been proposed in order to improve the chances of repair. The goal of this critical review is to present a survey of the current knowledge on adhesive approaches to restore endodontically treated teeth with and without extensive coronal tissue loss. The preservation of tooth structure of endodontically treated teeth is paramount. Partial versus full coverage of ETT, the role of the ferrule, the post type effect on catastrophic failures and postless alternatives as endocrowns and postless build-ups are reviewed. There is a consensus that the remaining tooth structure plays an important role in ETT survival, although the current literature still is contradictory on the influence of post type on root fractures as well as the benefits of avoiding a post or partially restoring a tooth. More clinical studies should be carried out with the modern postless adhesive alternatives to conventional approaches. [ABSTRACT FROM AUTHOR]

Objectives: Evaluate the fatigue resistance and failure mode of novel-design implant restorations made of histoana-tomic computer-assisted design/computer-assisted manufacturing (CAD/ CAM) bilaminar bonded assemblies. Material and methods: 60 screw-retained implant restorations were fabricated. Monolithic restorations were used as a control group (15 lithium disilicate: group CE; and 15 nanofilled composite resin: group CL), and compared with bilaminar restorations (15 dentin-shaped lithium disilicate mesostructures with a bonded nanofilled composite resin veneer: group CEL; and 15 dentin-shaped nanofilled composite resin mesostructures with a bonded lithium disilicate veneer: group CLE). All monolithic and bilaminar restorations were assembled and bonded to a customized metal implant abutment. Cyclic isometric chewing (5 Hz) at a 30-degree angle was simulated, starting with 5,000 cycles at a load of 150 N, followed by 20,000 cycles with increments of 50 N. Samples were loaded until fracture or to a maximum of 160,000 cycles. The groups were compared using the Life Table survival analysis (logrank test at P = 0.05; post hoc tests at P = 0.008). Results: In the CL group, restorations failed at an average load of 347.39 N (98.361 cycles), and in the CLE group at an average load of 313.20 N (83.105 cycles), and none of the specimens withstood all 160,000 load cycles. In the CE group, restorations failed at an average load of 381.47 N (119.115 cycles), and in the CEL group at an average load of 415.20 N (132.873 cycles), with survival rates of 26% and 33%, respectively. Post hoc tests from the load step data showed higher fatigue resistance of CEL compared with CLE (P= 0.003). Conclusion: Lithium disilicate monolithic restorations and mesostructures with nanofilled composite resin veneer presented higher survival rates when compared with nanofilled composite resin restorations. (Int J Esthet Dent 2017; 12:336-351) [ABSTRACT FROM AUTHOR]

Direct composite resin restorations have been recognized for their valuable clinical service and respect of intact hard tissue. The cost-effectiveness and inherent minimally invasive approach of resin-based materials means that they are also gaining popularity for use in computer-aided design/computer-aided manufacture (CAD/CAM) procedures. Several cases from the student clinics at the Herman Ostrow School of Dentistry of USC are presented that could have been resolved either with direct composite resin restorations or with indirect porcelain veneers. A novel semi-indirect CAD/CAM approach, characterized by its absolute noninvasiveness and simplicity, was chosen instead. The bilaminar restoration consists of a customized histoanatomical CAD/CAM dentin base (incisoproximal cutback), and a generic enamel skin. The patients can be treated either in one clinical session (semi-directly) or in two clinical sessions (semi-indirectly). The purpose of this article is to present another tool from the anterior restorative armamentarium to bridge the gap between direct and indirect techniques. [ABSTRACT FROM AUTHOR]

Objectives: To assess the influence of conventional glass ionomer cement (GIC) vs resin-modified GIC (RMGIC) as a base material for novel, super-closed sandwich restorations (SCSR) and its effect on shrinkage-induced crack propensity and in vitro accelerated fatigue resistance. Methods: A standardized MOD slottype tooth preparation was applied to 30 extracted maxillary molars (5 mm depth/5 mm buccolingual width). A modified sandwich restoration was used, in which the enamel/dentin bonding agent was applied first (Optibond FL, Kerr), followed by a Ketac Molar (3M ESPE)(group KM, n = 15) or Fuji II LC (GC) (group FJ, n = 15) base, leaving 2 mm for composite resin material (Miris 2, Coltène-Whaledent). Shrinkageinduced enamel cracks were tracked with photography and transillumination. Samples were loaded until fracture or to a maximum of 185,000 cycles under isometric chewing (5 Hz), starting with a load of 200 N (5,000 X), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 X each. Groups were compared using the life table survival analysis (↑ = .008, Bonferroni method). Results: Group FJ showed the highest survival rate (40% intact specimens) but did not differ from group KM (20%) or traditional direct restorations (13%, previous data). SCSR generated less shrinkage-induced cracks. Most failures were re-restorable (above the cementoenamel junction [CEJ]). Conclusions: Inclusion of GIC/RMGIC bases under large direct SCSRs does not affect their fatigue strength but tends to decrease the shrinkage-induced crack propensity. Clinical significance: The use of GIC/ RMGIC bases and the SCSR is an easy way to minimize polymerization shrinkage stress in large MOD defects without weakening the restoration. [ABSTRACT FROM AUTHOR]

The restoration of anterior teeth is frequently a demanding mission. Patients generally have high expectations for the anterior region, which makes the emotional side of treatment especially important. When this involves discolored endodontically treated teeth, consensus can hardly ever be found as to the chosen approach. Bleaching with direct composites is undoubtedly the most conservative choice for these cases. However, this may require more maintenance (touch-up bleaching and repairs) in the long term, which is an important issue for adult patients. On the other hand, bonded porcelain veneers represent a more 'high-end' option, as they recover the original biomechanics of the intact tooth, allow an optimal masking of the substrate, remain stable, and have a reasonable biological cost when compared to full-coverage crowns. This strategy is explained in this article and documented with a clinical case. We describe treatment planning based on the biomimetic concept, taking into consideration what is possible with current materials and techniques when combined with the patient's particular needs, including the introduction of an innovative step during dentin sealing - the microsuction. The laboratory work was totally accomplished by 'teledentistry', with no direct contact between the dental technologist and the patient. [ABSTRACT FROM AUTHOR]

A thorough understanding of the spatial distribution pertaining to the histo-anatomic coronal structures and dynamic light interaction of the natural dentition provides the dental team with the ultimate strategic advantage with regards to optical integration of the final restoration. The second part of this two-part article will attempt to provide insight on the illumination interactivity and the spatial arrangement of the coronal elements of natural teeth through the utilization of this knowledge in the clinical and technical restorative approach. The main goals for this article are to cognize histo-anatomic visualization by introducing: (1) Dynamic light interaction, (2) the 9 elements of visual synthesis, (3) dynamic infinite optical thickness, and (4) amplified visual perception effect of the hard dental tissues. Furthermore, a diversification of photographic illumination techniques will be illustrated in order to juxtapose optical associations between the enamel/dentinoenamel complex/dentin nexus. [ABSTRACT FROM AUTHOR]

Objectives The aim of the present study was to assess the shock absorbing capacity of implant-supported restorations ( CAD/ CAM composite resin or zirconia abutment with composite resin or porcelain crown/onlay) and a simulated natural tooth complex using the Periometer®. Material and methods One hundred and twenty Morse taper implants (Titamax CM 11 mm) were mounted on bone-simulating acrylic resin base and restored with CAD/ CAM zirconia (60) and metal composite resin Paradigm MZ100 (60) abutments. Using CEREC3, standardized onlays (60) and crowns (60) were designed and milled in ceramic (Paradigm C) or composite resin (Paradigm MZ100) to simulate a maxillary premolar. All restorations were luted with a preheated light curing composite resin (Filtek Z100). Fifteen extracted human upper premolars were mounted with a simulated PDL and used as control group. The Periometer®, a new handheld percussion probe that measures the energy loss coefficient ( LC) for both natural teeth and implant-supported structures, was positioned perpendicularly to the buccal surface of each restoration. Three measurements of the LC were collected for each specimen. The effect of each variable (abutment material, restoration material, and restoration design) on the LC was explored using multiple regression analysis. Results Differences in LC between the abutment material (zirconia/Paradigm MZ100), the restoration material (Paradigm C/Paradigm MZ100) and the restoration design (onlay/crown) were recorded. The average LC of zirconia and metal composite resin abutments ranged from 0.040 to 0.053 and 0.059 to 0.068, respectively. Zirconia abutments restored with composite resin restorations ( LC 0.051-0.053) had the closest LC value when compared with teeth with simulated PDL (0.049). Conclusion Composite resin onlays/crowns bonded to zirconia implant abutments presented similar dynamic response to load (damping behavior) when compared to teeth with a simulated PDL. [ABSTRACT FROM AUTHOR]

Localized subgingival margins can complicate the use of indirect adhesive restorations (isolation, impression taking, and delivery) and subsequently hinder their durability and relationship with the periodontal tissues. This article proposes a technique involving placement of a modified Tofflemire matrix followed by immediate dentin sealing and coronal elevation of the deep margin to a supragingival position using a direct bonded composite resin base. The deep margin elevation technique may be a useful noninvasive alternative to surgical crown lengthening. This technique may also facilitate the placement of large direct composite resin restorations. The fundamental principles of deep margin elevation are presented. [ABSTRACT FROM AUTHOR]

ABSTRACT Statement of Problem: Cracked teeth may traditionally require the use of complete coverage crowns. Alternative conservative treatments involve the use of adhesive inlays/onlays with the possibility of including a fiber patch to reinforce the cracked cusp. Purpose: The purpose of this study was to evaluate the fatigue strength of compromised molars restored with computer-aided-design/computer-assisted-manufactured (CAD/CAM) composite resin inlays/onlays with and without fiber-reinforced immediate dentin sealing (IDS). Methods and Materials: Large mesio-occluso-distal preparations with cracked/undermined palatal cusps were simulated on 40 extracted maxillary molars. All teeth received IDS (Optibond FL, Kerr, Orange, CA, USA), and composite resin (Paradigm MZ100, 3M-ESPE, St. Paul, MN, USA) inlays ( N = 20) and onlays ( N = 20). A fiber patch (Ribbond, Ribbond Inc., Seattle, WA, USA) was applied in half of the preparations. Restorations were adhesively luted with pre-heated composite resin (Z100, 3-M ESPE) and submitted to cyclic isometric loading at 5 Hz, starting with a load of 50 N (5,000 cycles), followed by stages of 150, 300, 450, 600, 750, 900, and 1,050 N at a maximum of 25,000 cycles each. Specimens were loaded until fracture or to a maximum of 180,000 cycles. Groups were compared using the life table survival analysis. Results: Differences in survival probability were found ( p = 0.04). The inlay group with fiber patch failed at an average load of 870 N, and none of the specimens withstood all 180,000 load cycles; survival rates of inlays and onlays without fibers, and onlays with fibers were 10, 30, and 50%, respectively. Conclusions: Onlays (with or without fibers) increased the fatigue resistance of compromised molars in this in vitro study. CLINICAL SIGNIFICANCE The results of this in vitro study suggest that molars with a compromised cusp may be best reinforced by a cusp-protecting composite resin onlay. There was no benefit of using fiber reinforcement under those indirect restorations. (J Esthet Restor Dent 24:135-147, 2012) [ABSTRACT FROM AUTHOR]

The growing demand of patients for esthetic or metal-free restorations, together with the ongoing interest of the dental profession for tissue-preserving materials have led to the actual development of posterior adhesive restorations. It is now clearly established that a new biomimetic approach to restorative dentistry is possible through the structured use of "tooth-like" restorative materials (composite resins and porcelain) and the generation of a hard tissue bond (enamel and dentin bonding). Scientific studies and clinical experience have validated use of bonded tooth-colored restorations, and we may have entered the so-called "postamalgam era." These significant changes have already impacted daily general practice, including pediatric dentists in California, but it is now critical to assure that the corresponding evidencebased process is integrated to the predoctoral programs statewide and nationwide. This paper reviews the foundations of this evolution, based on maximum tissue preservation and sound biomechanics, the so-called "biomimetic principle." Using scientific evidence and clinical experience, a model for the adequate use of current restorative systems is presented. This work, illustrated with cases with up to 10 and 14 years' follow-up, sets the ground rules for the clinical performance of the posterior esthetic restoration. Important considerations about tooth preparation, matrix techniques, layering methods, immediate dentin sealing and base lining are presented. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To assess the influence of material/technique selection (direct vs. CAD/CAM inlays) for large MOD composite adhesive restorations and its effect on the crack propensity and in vitro accelerated fatigue resistance. Methods: A standardized MOD slot-type tooth preparation was applied to 32 extracted maxillary molars (5mm depth and 5mm bucco-palatal width) including immediately sealed dentin for the inlay group. Fifteen teeth were restored with direct composite resin restoration (Miris2) and 17 teeth received milled inlays using Paradigm MZ100 block in the CEREC machine. All inlays were adhesively luted with a light curing composite resin (Filtek Z100). Enamel shrinkage-induced cracks were tracked with photography and transillumination. Cyclic isometric chewing (5Hz) was simulated, starting with a load of 200N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200 and 1400N at a maximum of 30,000 cycles each. Samples were loaded until fracture or to a maximum of 185,000 cycles. Results: Teeth restored with the direct technique fractured at an average load of 1213N and two of them withstood all loading cycles (survival=13%); with inlays, the survival rate was 100%. Most failures with Miris2 occurred above the CEJ and were re-restorable (67%), but generated more shrinkage-induced cracks (47% of the specimen vs. 7% for inlays). Significance: CAD/CAM MZ100 inlays increased the accelerated fatigue resistance and decreased the crack propensity of large MOD restorations when compared to direct restorations. While both restorative techniques yielded excellent fatigue results at physiological masticatory loads, CAD/CAM inlays seem more indicated for high-load patients. [Copyright &y& Elsevier]