Evaluation of marginal and internal adaptation of veneers generated by the guided prosthetic tooth preparation system.

OBJECTIVE: This in vitro study aimed to assess and contrast the marginal and internal adaptation of all-ceramic prefabricated veneers manufactured via the FirstFit guided tooth preparation system against all-ceramic veneers produced using the chairside Computer-Aided Design/Computer Aided Manufacture (CAD/CAM) system following identical guided preparation protocols. MATERIALS AND METHODS: Two main groups were included, with 16 lithium disilicate veneers per group. Four typodonts were used for the test (FirstFit) and control CAD/CAM groups. Intraoral scans created master casts and preparation guides. Guides performed preparations on typodont teeth (two central incisors and two lateral incisors). Prepared teeth were scanned (CEREC Omnicam) to design and mill CAD/CAM veneers. Marginal gap thickness and cement space thickness were measured using light microscopy at four locations: marginal, cervical internal, middle internal, and incisal internal. RESULTS: No significant difference existed between groups for marginal adaptation (p = 0.058) or incisal internal adaptation (p = 0.076). The control group had significantly lower values for middle internal adaptation (p = 0.023) and cervical internal adaptation (p = 0.019). CONCLUSIONS: Guided preparation evaluation showed no significant differences in marginal or incisal internal adaptation. The CAD/CAM group had significantly lower middle and cervical internal adaptation values.

Minimally invasive prosthodontics using the concept of prosthetically guided orthodontics.

OBJECTIVE: This case report aims to present how digital technology can be employed to plan the orthodontic movement of teeth into their final positions for prosthodontic rehabilitation. An interdisciplinary approach to treatment planning and the result of prosthodontic treatment involves the cooperation of an orthodontist and a prosthodontist. When planned to achieve optimal results for a minimally invasive and functional prosthodontic treatment, orthodontic pretreatment provides superior esthetic results and favorable long-term success. CLINICAL CONSIDERATIONS: The orthodontic movements of the teeth were planned so that the prosthodontist could reconstruct an optimally functional and esthetic occlusion while preserving the hard dental tissues. The orthodontic pretreatment minimized the need to prepare the teeth, avoiding any mucogingival surgery to improve the gingival architecture. CONCLUSIONS: In complex clinical cases, it is essential to evaluate the advantages of an orthodontic pretreatment before starting a prosthodontic treatment. This pretreatment can help preserve dental tissues, reduce or eliminate the need for surgical intervention, and achieve long-term stability and esthetic results. CLINICAL SIGNIFICANCE: This case clearly shows the benefits of orthodontic pretreatment for prosthodontic outcomes. With modern digital tools, such an orthodontic pretreatment should become standard clinical practice when planning a complex clinical case.

Multidisciplinary clinical approach of an orthodontic treatment and complete digital rehabilitation of laminate veneers for esthetically compromised worn teeth.

AIM: The present clinical case reports on the workflow of a multidisciplinary treatment including both orthodontic and esthetic procedures for the rehabilitation of a young patient with severe wear in the anterior area of both the maxillary and mandibular arches due to malocclusion. The described workflow comprises a digital step-by-step process that involves 3D printing, intraoral scanners, and CAD/CAM milling systems. RESULTS: Accurate diagnostic and treatment planning were paramount when different specialties needed to combine and work together. For that purpose, different digital procedures helped to improve the predictability and the dynamic of the orthodontic and restorative treatments. CONCLUSION: The present multidisciplinary clinical case was executed with a digital approach that assisted to speed things up and achieve a predictable treatment option.

Ceramic laminate veneers: effect of preparation design and ceramic thickness on fracture resistance and marginal quality in vitro.

OBJECTIVES: The aim of the present study was to investigate the influence of five different preparation designs and two different ceramic thicknesses on margin quality and fracture resistance of ceramic laminate veneers after thermomechanical loading in vitro. MATERIALS AND METHODS: Eighty human central incisors were randomly assigned to 10 groups (n = 8) with five different preparation designs: non-prep (NP), minimally invasive (MI) = exclusively enamel-bonded, semi-invasive (SI) = 50% bonded in dentin, invasive (I) = 100% in dentin, and semi-invasive with two additional class III composite resin restorations (SI-C). IPS InLine veneers were fabricated in two thicknesses (L1 = 0.2-0.5 mm; L2 = 0.5-1.2 mm). After adhesive luting (OptiBond FL, Variolink Veneer) with light curing and polishing, specimens were stored in distilled water at 37 °C for 21 days, then thermocycled (2000 cycles between + 5 and + 55 °C), and finally mechanically loaded at the incisal edge at an angle of 45° for 2,000,000 cycles at 50 N und further 1,000,000 cycles at 100 N. Impressions were taken initially, after thermocycling, and after every 250,000 mechanical cycles in order to evaluate cracks and margin quality under a SEM. The veneers were evaluated in a light microscope (× 20) for cracks, chippings, partial, and catastrophic fractures. RESULTS: Margin quality after three million cycles revealed medians for continuous margin of 82-95% without significant differences among groups, neither at the ceramic/composite (p = 0.943) nor at the tooth/composite interface (p = 0.571). Visual inspection of veneers exhibited 22 cracks, 11 chippings, 4 partial and 4 catastrophic fractures in 38 of 80 veneers. The statistical ranking regarding fracture risk (p ≤ 0.05) was: IL1 = SIL1 = MIL1 = IL2 = CL1 = CL2, MIL2 = NPL1 = NPL2 = SIL2, IL2 = CL1 = CL2 = MIL2 = NPL1 = NPL2 = SIL2. CONCLUSIONS: Even after three million cycles with up to 100 N, all groups showed high survival rates. However, the fracture risk increases with thin veneers and preparations with medium to high dentin portions when compared to thicker veneers with preparations in enamel or partially in dentin (p ≤ 0.05). Preexisting resin composite restorations did not show any significant influence on margin quality and facture risk (p > 0.05). CLINICAL RELEVANCE: Ceramic laminate veneers are extremely durable with thin veneers and substantial enamel loss being main risk factors for fracture.

Evaluation of fracture resistance of ceramic veneers with different preparation designs and loading conditions: An in vitro study.

PURPOSE: The purpose of this study was to evaluate the effect of incisal butt joint and incisal overlap design on the fracture resistance of ceramic veneers under two different loading conditions, i.e., 125° and 60° representing protrusive and intercuspal movements, respectively. MATERIALS AND METHODS: Thirty-two maxillary central incisors were divided into two groups of sixteen specimens each and were prepared with incisal butt joint and incisal overlap design. Ceramic veneers were fabricated and cemented. Both the groups were further divided and mechanical testing to evaluate the fracture resistance were done using the universal testing machine. The values were recorded in Newton along with the assessment of the failure mode of both veneer and the tooth. RESULTS: Unpaired t-test showed a significant difference (P < 0.05) with butt joint design having higher fracture resistance than palatal overlap design with the mean value of 409.50N at 60° angle and 473.37N at 125° angle. Paired t-test depicted a significant difference for both the designs at 125° than at 60° angle (P < 0.05). Chi-square analysis showed more number of intact veneers with butt joint design; however, there was no significant difference (P > 0.05). Failure mode of teeth showed more number of coronal fracture followed by cervical fracture and root fracture, but there was no significant difference between the two groups (P > 0.05). CONCLUSION: Butt joint design had higher fracture resistance than palatal overlap design. Under functional loads for both designs, fracture resistance was higher at 125° than at 60° angle.

Combination esthetic treatment of anterior teeth affected by idiopathic enamel hypoplasia: a case report.

The esthetic management of enamel dysplasia presents an opportunity for the practitioner to integrate expertise in diagnosis, biomaterials, and technique. In addition to considerations of appearance, careful attention must be paid to occlusal function and restorative material properties. This case report highlights a combined approach of conservative lithium disilicate indirect restorations and composite resin direct veneers to electively restore the anterior teeth of a patient diagnosed with idiopathic enamel hypoplasia.

Influence of ceramic thickness and type on micromechanical properties of light-cured adhesive bonding agents.

OBJECTIVE: The aim of this study was to evaluate the micromechanical properties of different adhesive bonding agents when polymerized through ceramics. MATERIALS AND METHODS: Sixty sound extracted human third molars were selected and the crowns were sectioned perpendicular to the long axis in order to obtain dentin slices to be bonded with one of the following adhesives: Syntac/Heliobond (Ivoclar-Vivadent) or Adper-Scotchbond-1XT (3M-ESPE). The adhesives were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10 s, 20 s and 30 s) under two ceramics (IPS-e.max-Press, Ivoclar-Vivadent; IPS-Empress®CAD, Ivoclar-Vivadent) of different thicknesses (0 mm, 0.75 mm, 2 mm). Thirty groups were included, each containing 60 measurements. Micromechanical properties (Hardness, HV; indentation modulus, E; and creep, Cr) of the adhesives were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). Data were statistically analyzed by using one-way ANOVA and Tukey's post-hoc test, as well as a multivariate analysis to test the influence of the study parameters (SPSS 18.0). RESULTS: Significant differences were observed between the micromechanical properties of the adhesives (p < 0.05). The ceramic type showed the highest effect on HV (Partial-eta squared (η(2)) = 0.109) of the tested adhesives, while E (η(2) = 0.275) and Cr (η(2) = 0.194) were stronger influenced by the adhesive type. Ceramic thickness showed no effect on the E and Cr of the adhesives. CONCLUSIONS: The adhesive bonding agents used in this study performed well by curing through different thicknesses of ceramics. The micromechanical properties of the adhesives were determined by the adhesive type and were less influenced by ceramic type and curing time.

Clinical Success Evaluation of Ultrathin Ceramic Veneers Bonded to Nonprepared Teeth: An Observational Prospective Cohort Study.

BACKGROUND: Patients' increasing interest in achieving optimal cosmetic outcomes and the widespread use of ultrathin ceramic veneers offer advantages such as high esthetic results and long-term durability. Several issues related to tooth preparation have been raised, including dental sensitivity, periodontal diseases, and increased treatment phases, in addition to complications associated with previous procedures, the treatment of which remains controversial to date. With the advancement of dental ceramic and its manufacturing techniques, it was widely used to manufacture ultrathin ceramic veneers with minimal preparation. Issues such as fracture and abfraction are the most common in ceramic veneers made of feldspathic ceramic due to their weak mechanical properties against various forces, which led to the emergence of lithium disilicate glass-ceramic manufactured using the heat-press technique. This has resulted in ultrathin ceramic veneers with a thickness of up to 0.1-0.2 mm easily bonded and finished as they have high mechanical properties and esthetic qualities that mimic natural tooth color and shape. The current cohort study aimed to evaluate the success rates of this kind of treatment for patients treated at our department. MATERIALS AND METHODS: This observational cohort study's sample comprised 60 ultrathin ceramic veneers manufactured from lithium disilicate glass-ceramic bonded to nonprepared upper teeth. The clinical performance of the studied sample was evaluated and monitored at monthly intervals (one month, three months, six months, and one year) using the clinical success evaluation based on Walton's principles adopted for evaluating the success and failure of fixed restorations. RESULTS: Ultrathin ceramic veneers made from lithium disilicate glass-ceramic, bonded to nonprepared teeth, proved to be a successful clinical and esthetic treatment option, with a clinical success rate of 100% during the entire follow-up period. CONCLUSIONS: This study's findings indicate that ultrathin ceramic veneers made from lithium disilicate glass-ceramic, bonded to nonprepared teeth, are a successful clinical and esthetic treatment option, with a clinical success rate of 100% during the entire follow-up period.

A Conservative Approach to Ceramic Laminates in the Anterior Region: A Clinical Report.

This clinical report presents a conservative approach to restoring aesthetic function in anterior maxillary teeth using digital dental technologies. A 40-year-old female patient sought treatment to enhance the aesthetics of her anterior maxillary teeth. The clinical examination revealed wear on the incisal surfaces and gingival asymmetry. Utilizing a digital workflow, intraoral and extraoral data were acquired through clinical photographs and an intraoral scanner. The patient's restorative needs were assessed using the 3Shape Smile Design system (3Shape, Copenhagen, Denmark). Minimal-thickness ceramic restorations were designed and fabricated using Computer-Aided Design-Computer-Aided Manufacturing (CAD-CAM) technologies. Lithium disilicate was selected for its strong mechanical properties and adhesive capabilities. The restorations were then placed using an adhesive cementation protocol under magnification. Digital technologies facilitated precise diagnosis, planning, and execution of the treatment. The ceramic restorations provided excellent aesthetic outcomes, aligning with the patient's expectations. The minimal thickness of the restorations ensured the preservation of natural tooth structure while maintaining structural integrity and adhesion performance. This case underscores the advantages of a digital workflow in achieving optimal restorative outcomes. The digital dental workflow demonstrated in this case report provides a reliable, efficient, and patient-centric approach to minimal thickness restorations, highlighting the potential for future advancements in restorative dentistry.

Three Dimensional-Printed Gingivectomy and Tooth Reduction Guides Prior Ceramic Restorations: A Case Report.

Computer-aided design and computer-aided manufacturing (CAD/CAM) dentistry have significantly changed workflows in recent years. Restorations and devices can now be digitally designed and 3D-printed for dental care purposes. This clinical case report provides straightforward protocols for the digital design and 3D manufacture of gingivectomy and tooth preparation guides. These types of guides improved the gingival architecture of the anterior teeth and provided controllable tooth preparations prior to labial ceramic veneers. Thoughtful clinical evaluation started with listening to the patient's chief complaint and extra- and intra-oral evaluations. Then a digital wax-up was performed, followed by an intra-oral mock-up, to evaluate the shape of the proposed restorations. After patient acceptance, the clinical procedure started with the gingivectomy and tooth preparation. Hand-crafted porcelain veneers were bonded under rubber dam isolation to avoid any contamination and maximize the bonding protocol. The esthetic and functional demands were fully satisfied. Predictable outcomes can be obtained whenever a meticulous evaluation and execution of all the steps are performed. Three dimensional printing technology allows the fabrication of devices such as gingivectomy and tooth reduction guides that help accomplish the desired results.

Application of Minimally Invasive Prosthodontics With an Esthetic 16-Unit Rehabilitation of the Dental Arches for a Patient With Anterior Dental Crowding and a Relatively Deep Bite: A Case Report.

Minimally invasive dentistry indicates an operative intervention to correct or manipulate a dental anomaly or lesion while focusing on preserving the original tissues as much as possible. Losing teeth or teeth loss is one of the most common problems patients have always suffered from due to different reasons, such as caries, trauma, or periodontal problems. In cases of multiple teeth loss, oral rehabilitation is usually indicated. Aesthetic reconstruction of a patient's mouth with crowded teeth and a deep bite is challenging for prosthodontists. This case report shows an applicable conservative approach of minimally invasive dentistry in this situation while maintaining vertical dimension and centric occlusion.

Freehand vs. depth-gauge rotary instruments for veneer preparation: A controlled randomized simulator study.

PURPOSE: To investigate whether depth-gauge burs in veneer preparations influence preparation depth in a randomized, controlled, single-blinded trial and whether inexperienced operators can perform adequate veneer preparations. METHODS: Participants were 20 undergraduate dental students with no prior veneer preparation experience. The instruments used were the "Laminate Veneer System" (LVS), "Keramik-Veneers. de" (KVD), and a "Freehand" group (FH) for reference. All participants prepared three educational acrylic resin maxillae and three mandibular central incisors mounted in typodonts in patient simulators. The objectives were to achieve a preparation depth of 0.6 mm (tooth 11) and 0.4 mm (tooth 31). The sequences of the instruments used and prepared teeth were randomized. The measurements were performed using a laser triangulation coordinate-measuring machine. The data were stratified according to tooth location. RESULTS: The preparation depths of both depth-gauge-instrument-groups LVS and KVD achieved the objectives significantly better than did the instruments from the "Freehand" group (P < 0.001). The differences between the depth gauge groups were insignificant, although the maximum preparation depths were smaller in the KVD group. Regarding the prepared teeth, the preparation depths in the mandibular incisors were lower, and the differences were smaller. CONCLUSIONS: The use of special depth-gauge burs for initial veneer preparation leads to significantly lower preparation depths than "Freehand" preparations. The tapered instruments resulted in a lower incidence of extreme preparation depths. The inexperienced operators performed veneer preparation remarkably well.

Total Rehabilitation Using Adhesive Dental Restorations in Patients with Severe Tooth Wear: A 5-Year Retrospective Case Series Study.

INTRODUCTION: Currently, there is little clinical evidence to support the medium- and long-term survival and clinical performance of ultraconservative approaches using adhesive restorations in full-mouth restorations. The aim of this case series study was to evaluate the medium-term clinical performance of anterior and posterior adhesive restorations applied with direct and indirect techniques using resin composites and glass-ceramic-based materials. MATERIALS AND METHODS: The inclusion criteria were an esthetic problem as the main reason for consultation and severe generalized wear of grade 2 to 4 according to the Tooth Wear Evaluation System (TWES 2.0). In addition, at each follow-up appointment, patients were required to submit a clinical-parameter-monitoring record according to the modified United States Public Health Service (USPHS) criteria. RESULTS: Eight patients with severe tooth wear were treated through full rehabilitation in a private dental clinic in Spain by a single operator (AFC). A total of 212 restorations were performed, which were distributed as follows: 66 occlusal veneers, 26 palatal veneers and 120 vestibular veneers. No signs of marginal microleakage or postoperative sensitivity were observed in any occlusal, vestibular and/or palatal restoration after the follow-up period. The estimated survival rate of the 212 restorations was 90.1% over 60 months of observation, with a survival time of 57.6 months. Only 21 restorations had complications, which were mostly resolved with a direct composite resin. The dichotomous variables of the restoration type (posterior veneer, anterior veneer) and the type of restored tooth (anterior, posterior) were the risk predictors with statistically significant influences (p < 0.005) on the survival of the restorations. CONCLUSION: According to the results of this study, there is a significantly higher risk of restorative complications in posterior teeth compared to anterior teeth. Also, it can be concluded that the indication of adhesive anterior and posterior restorations is justified in the total oral rehabilitation of patients with severe multifactorial tooth wear, as they are associated with a low risk of failure.

The Influence of a Novel, Crenelated Design of CAD-CAM Ceramic Veneers on the Debonding Strength.

(1) Background: Aesthetic dentistry has become one of the most dynamic fields in modern dental medicine. Ceramic veneers represent the most appropriate prosthetic restorations for smile enhancement, due to their minimal invasiveness and highly natural appearance. For long-term clinical success, accurate design of both tooth preparation and ceramic veneers is of paramount importance. The aims of this in vitro study were to assess the stress in anterior teeth restored with Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) ceramic veneers and compare the resistance to detachment and the fracture of ceramic veneers prepared using two different designs. (2) Methods: Sixteen lithium disilicate ceramic veneers were designed and milled using the CAD-CAM technology and divided into two groups according to the preparations (n = 8): Group 1, conventional (CO), with linear marginal contour and Group 2, crenelated (CR), the latter with our novel (patented) sinusoidal marginal design. All samples were bonded to anterior natural teeth. The mechanical resistance to detachment and fracture was investigated by applying bending forces on the incisal margin of the veneers in order to determine which type of preparation leads to better adhesion. An analytic method was employed, as well, and the results of the two approaches were compared. (3) Results: The mean values of the maximum force recorded at the veneer detachment were 78.82 ± 16.55 N for the CO group and 90.20 ± 29.81 N for the CR group. The relative increase, equal to 14.43%, demonstrated that the novel CR tooth preparation provided higher adhesive joints. In order to determine the stress distribution within the adhesive layer, a finite element analysis (FEA) was performed. The statistical t-test showed that the mean value of the maximum normal stresses is higher for the CR-type preparations. (4) Conclusions: The patented CR veneers represent a practical solution to augment the adhesion and mechanical properties of ceramic veneers. The obtained results demonstrated that CR adhesive joints triggered higher mechanical and adhesive forces, which subsequently led to a higher resistance to detachment and fracture.

An in vitro comparison of incisal preparation design on load-to-failure of ceramic veneers.

Introduction: This in vitro study aimed to compare the load-to-failure values of two different ceramic veneers (IPS e.max Press [Ivoclar Vivadent] and Vintage lithium disilicate [LD] press [Shofu]) with incisal preparation designs under standardized conditions. Materials and Methods: Twenty-two intact extracted maxillary incisors were selected and divided randomly into two groups (n = 11). The veneer tooth preparation was standardized in both groups where a butt joint incisal preparation was done along with chamfer margin. Group 1 included veneers made from IPS e.max Press (Ivoclar Vivadent) and Group 2 included veneers fabricated from Vintage LD Press (Shofu). Veneers were luted to their respective abutment teeth using standardized bonding protocols and resin cement for both groups. Later, every specimen was loaded to failure utilizing a universal testing machine, and the outcomes were noted in Newtons (N). Results: The mean load-to-failure value obtained for Group 1 (IPS e.max Press) was 1386.46 N while that obtained for Group 2 was 1777.07 N. Statistically significant difference was found in this intergroup comparison (P = 0.006). Conclusion: The load-to-failure value of Vintage LD Press veneers (Shofu) was greater than that of IPS e.max Press veneers (Ivoclar Vivadent).

Effect of ultrasound on preheated resin composites used as ceramic luting agents.

This study investigated the effect of ultrasound application when luting ceramic using two preheated composites that show distinct responses to preheating at 69°C: Filtek Z100 and Z350XT. RelyX Veneer was the control. Feldspar disks were luted using the resin-based luting agents (RBLAs), and ultrasound was tested. Biaxial flexure strength (σbf) was calculated at z-axial positions of the luted disks (z=0; z=-t2). Microtensile bond strength (µTBS) to ceramic was tested (n=30). Data were analyzed at α=0.05. At z=0, the σbf was higher for Z350 when ultrasound was not used. When ultrasound was applied, the σbf was similar between Z350 and Z100. At z=-t2, differences across the RBLAs were observed: Z350 was superior than Z100 and control without ultrasound. Ultrasound increased σbf for Z100 at both axial positions. The preheated composites yielded higher µTBS than the control. Ultrasonication increased the mechanical performance of ceramic luted with Z100 without influencing the film thickness.

Rubber Dam Isolation for Bonding Ceramic Veneers: A Five-Year Post-Insertion Clinical Report.

It has been well-documented that uncontaminated ground enamel provides the most predictable substrate for the bonding of ceramic veneers, and thus conservative tooth preparation with complete isolation using a rubber dam is key to the long-term success of the restorations presented with five years of follow-up. Rubber dam isolation provides several advantages to the clinician, such as preventing contamination of the working field by saliva, blood, and sulcular fluids, and improving direct visibility. However, it may be a challenge to the younger clinician to properly isolate teeth prior to bonding ceramic veneer. The present case report demonstrated the sequence and some clinical tips for a case in which the rubber dam is placed from a second premolar to the opposite second premolar and held with clamps, the rubber dam is gently invaginated into the sulcus, and clamps are selected and placed on each tooth to create an ideal situation for the adhesion of the ceramic veneer. This step-by-step sequence may help the younger clinician in understanding how to gently manage soft tissue in order to properly provide complete isolation with rubber dam for future bonding of ceramic veneers. Following these methods, the clinician can achieve complete isolation, invaginate the rubber dam in the sulcus without causing tissues to bleed, and reduce the time needed for bonding procedures.

Substantial in-vitro and emerging clinical evidence supporting immediate dentin sealing.

The application of resin adhesive to freshly cut dentin after teeth preparation, the so-called immediate dentin sealing (IDS) has been suggested as an alternative to the delayed dentin sealing (DDS), a technique in which resin adhesive is applied just before final bonding of indirect restorations. The aim of this review is to demonstrate the evidence of the claimed advantages made by the proponents of IDS technique. The results of this review revealed substantial in-vitro evidence supporting the IDS benefits including improved bond strength, reduced dentin permeability, improved restorations' adaptation, and increased fracture strength of the restorations. Clinical studies have shown that IDS improves survival of ceramic laminate veneers bonded to prepared teeth with increased exposure of dentin. Moreover, it has been shown that IDS reduces post-cementation hypersensitivity in full coverage restorations, which is characterized by exposure of a large number of dentinal tubules. The selection of filled resin adhesive that is capable of producing thick adhesive layer appears to contribute to the success of the technique. Furthermore, careful management of the oxygen inhibition layer before conventional impression making and proper cleaning of the residual temporary cement used with provisional restorations appears to affect the outcome of the restorations.

Essay III: Adhesive restorative options for restorative space management in the anterior zone with or without orthodontic pretreatment: some clinical considerations and case presentations.

An unfavorable relationship between the form and dimension of the dental arch and the number, dimension, and shape of the existing teeth can pose several esthetic, biologic, and functional problems. In this article, the various restorative options are discussed based on clinical and scientific evidence: Gap closure and substitution of missing teeth: restorative transformation of substituted teeth into homologous teeth with odontoplasty, direct composite, etched pieces or porcelain veneers. Gap opening and tooth replacement with all-ceramic adhesive bridges, including pontic site development. Gap distribution and restorative compensation with direct composite restorations, etched pieces or porcelain veneers. Gap shifting and restorative compensation with all-ceramic adhesive bridges, composite, etched pieces or veneers. Gap compensation by reconstructive compensation without orthodontics. The reconstructive tools including composite restorations, ceramic veneers, and adhesive bridges are discussed, and numerous cases are presented to illustrate the concepts.

Response of composite resins to preheating and the resulting strengthening of luted feldspar ceramic.

OBJECTIVE: This study evaluated the influence of preheating different composite resins on their viscosity and strengthening yielded to ceramic. METHODS: Modulus of elasticity, Poisson's ratio, and degree of CC conversion were measured for three restorative composite resins (Z100-microhybrid; Empress Direct-nanohybrid; Estelite Omega-supranano) and one photoactivated resin cement (RelyX Veneer). Viscosity was measured during a heating-cooling curve (25°C-69°C-25°C) and also using isothermal analyses at 25°C and 69°C. Feldspar ceramic disks simulating veneers were bonded with the luting materials. Biaxial flexural strength, characteristic strength, and Weibull modulus were calculated at axial positions (z=0 and z=-t2) of the bilayers. Film thickness was measured and morphology at the bonded interfaces was observed. Data were statistically analyzed (α=0.05). RESULTS: A gradual decrease in viscosity was noticed as the rheometer temperature gradually increased. Viscosity differences between the composite resins were large at the beginning of the analysis, but minor at 69°C. At 25°C, the composites were up to 38 times more viscous than the resin cement; at 69°C the difference was 5-fold. CC conversion was similar between all resin-based agents. The resin cement yielded lower film thickness than the composites. All resin-based agents were able to infiltrate the ceramic porosities at the interface and strengthen the ceramic. However, the magnitude of the strengthening effect was higher for the preheated composite resins, particularly at z=-t2. SIGNIFICANCE: Selection of composite resin impacts its response to preheating and the resulting viscosity, film thickness, and magnitude of ceramic strengthening.