In vitro evaluation of marginal and internal adaptation of class II CAD/CAM ceramic restorations with different resinous bases and interface treatments.

OBJECTIVES: This in vitro study evaluated the influence of different composite bases and surface treatments on marginal and internal adaptation of class II CEREC CAD/CAM ceramic inlays, before and after simulated occlusal loading. METHODS: Thirty-two IPS Empress CAD class II inlays (MO or OD) (n = 8/group) were placed on third molars, with margins 1 mm below the cementum-enamel junction (CEJ), following different cavity treatments. These treatments were non-liner (control group), a flowable composite liner (Premise flow) sandblasted or treated with soft air abrasion and a restorative composite liner (Premise) sandblasted. The restorations were then luted with Premise. All specimens were submitted to 1,000,000 cycles with a 100-N eccentric load. The tooth restoration margins were analysed semi-quantitatively by SEM pre- and post-loading. The internal adaptation was also evaluated after test completion. RESULTS: The percentage of satisfactory marginal adaptation varied from 75 to 87 % pre-loading and 62 to 72 % post-loading in occlusal enamel, from 71 to 83 % pre-loading and 52 to 63 % post-loading in proximal enamel, and from 68 to 88 % pre-loading and 43 to 66 % post-loading in cervical dentin. There were no significant differences among groups. The percentages of satisfactory tooth-composite internal adaptation varied from 81 to 98 % in occlusal dentin, from 63 to 90 % in axial dentin, and from 71 to 84 % in cervical dentin without any statistical difference. CONCLUSIONS: The results of the present study support the use of flowable or restorative composites as a liner underneath ceramic CAD/CAM inlays, producing marginal and internal adaptation which is not different from restorations placed directly on dentin. Soft air abrasion proved not to be different from sandblasting for treating cavities before cementation. CLINICAL RELEVANCE: The results of this in vitro test validate the increasing use of a flowable base/liner underneath CAD/CAM ceramic inlays to optimise tissue conservation and clinical procedures; in this case, soft air abrasion is recommended as a pre-cementation step.

Light polymerization during cavity filling: influence of total energy density on shrinkage and marginal adaptation.

The aim of the study was to evaluate the marginal adaptation and shrinkage stress development of a micro hybrid restorative composite as a function of energy density. Linear displacement and shrinkage forces were measured with custom-made devices for energies of 4,000, 8,000, 16,000 and 32,000 mJ/cm(2) at a constant power density of 800 mW/cm(2). Marginal adaptation of composite restorations cured with the same energy density was evaluated before and after mechanical loading with 300,000 cycles at 70 N. The group "4,000 mJ/cm(2)" showed the lowest shrinkage force [2.9(0.2) kg] and linear displacement [23.5(0.7) µm] but led to the worst marginal adaptation after loading [46.4(23.5) %CM] probably due to under-curing. When the maximum energy of 32,000 mJ/cm(2) was applied, a slight increase in shrinkage forces [3.6(0.2) kg and 29.2(0.8) µm], and a slight decrease in marginal adaptation after loading [75.4(11.5) %CM] were observed, but these changes were not significantly different in comparison to groups cured with energies of 8,000 and 16,000 mJ/cm(2). For the resin composite tested in this study, no differences in marginal adaptation could be detected above the energy threshold of 8,000 mJ/cm(2).

Semidirect composite onlay with cavity sealing: a review of clinical procedures.

UNLABELLED: The evolution in adhesive dentistry has broadened the indication of esthetic restorative procedures especially with the use of resin composite material. Depending on the clinical situation, some restorative techniques are best indicated. As an example, indirect adhesive restorations offer many advantages over direct techniques in extended cavities. In general, the indirect technique requires two appointments and a laboratory involvement, or it can be prepared chairside in a single visit either conventionally or by the use of computer-aided design/computer-aided manufacturing systems. In both cases, there will be an extra cost as well as the need of specific materials. This paper describes the clinical procedures for the chairside semidirect technique for composite onlay fabrication without the use of special equipments. The use of this technique combines the advantages of the direct and the indirect restoration. CLINICAL SIGNIFICANCE: The semidirect technique for composite onlays offers the advantages of an indirect restoration and low cost, and can be the ideal treatment option for extended cavities in case of financial limitations.

Marginal Adaptation of In Vitro Class II Restorations Made Out of Bulk or Conventional Composite Using Single- or Multi-Layered Techniques.

Objective: Testing the influence of various restorative materials (conventional or bulkfill composites) and filling techniques (single- or multi-layered techniques) on the in vitro marginal adaptation of large class II direct composites with supra and sub-gingival margins subjected to thermomechanical loading (TML). Methods: A total of 40 prepared teeth were attributed randomly to five experimental groups. In Group 1, restorations were made of multi-layered high-viscosity conventional composite (Tetric EvoCeram); in Groups 2 and 3, restorations were made of a high viscosity bulkfill composite (Tetric EvoCeram Bulk Fill) applied in one (Group 2) or three layers (Group 3); in Groups 4 and 5, restorations were made of a flowable bulkfill composite (SDR flow) applied in one (Group 4) or two layers (Group 5), covered with a layer of high-viscosity conventional composite (Ceram-X Universal). A single adhesive (OptiBond FL) was used in all groups. All specimens were submitted to a staged TML comprising three phases (2 × 500,000 and 1,000,000 cycles) at 50 N with 3350 thermal cycles (5 to 55 °C) every 500,000 cycles. The tooth-restoration interfaces on proximal surfaces were evaluated quantitatively by scanning electron microscopy, before and after each TML phase, hence at three timepoints (T0, T1, T2 and T3). The following segments were considered for evaluation: proximal, vertical enamel margins (assessed individually on both restoration sides), cervical enamel (restoration side above CEJ) and cervical dentin margin (restoration side below the CEJ). Results: TML induced a significant reduction in continuous adaptation at both enamel and dentin margins in all groups, with percentages of continuous margins ranging from 75.2 to 91.8% at T0, and decreasing to values ranging from 21.3 to 73.9% at T3. Both composite systems and layering protocols had a significant influence on marginal adaptation of the restorations, with statistical associations depending on the restoration group and the timepoint considered. Defective margins in enamel were all of a cohesive nature with micro-fractures, while in dentin, interfacial gaps were the main defect observed. Conclusions/Clinical significance: The present results highlighted significant degradation of marginal adaption after long-term in vitro fatigue test using materials even with high-viscosity conventional resin composites, applied with a proper layering approach in medium-large sub-gingival cavities. While no significant differences were observed at the dentin cervical margins, there was a tendency for better adaptation at the enamel margin when using a higher modulus material with a multi-layered technique.

In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases and interface treatments. "Post-fatigue adaptation of indirect composite restorations".

The present study evaluated the influence of different composite bases and surface treatments on marginal and internal adaptation of class II indirect composite restorations, after simulated occlusal loading. Thirty-two class II inlay cavities were prepared on human third molars, with margins located in cementum. A 1-mm composite base extending up to the cervical margins was applied on all dentin surfaces in the experimental groups; impressions were made and composite inlays fabricated. The following experimental conditions were tested: no liner (control group), flowable composite treated with soft air abrasion (experiment 1), flowable composite sandblasted (experiment 2) and restorative composite sandblasted (experiment 3). All specimens were submitted to 1,000,000 cycles with a 100-N eccentric load. Tooth-restoration margins were analysed semi-quantitatively by scanning electron microscopy before and after loading; internal adaptation was also evaluated after test completion. The percentage of perfect adaptation in enamel was 79.5% to 92.7% before loading and 73.3% to 81.9% after loading. Perfect adaptation to dentin was reduced before loading (54.8% to 77.6%) and after loading (41.9% to 63%), but no difference was found among groups for pre- and post-loading conditions. No debonding occurred between the base and composite luting. A significant, negative influence of cyclic loading was observed. The results of the present study support the use of flowable or restorative composites as base/liner underneath large class II restorations. Soft air abrasion represents a potential alternative to airborne particle abrasion for treating cavities before cementation. The application of a composite base underneath indirect composite restorations represents a feasible non-invasive alternative to surgical crown lengthening to relocate cavity margins from an intra-crevicular to supra-gingival position.

Rehabilitation of Worn Dentition with Direct Resin Composite Restorations: A Case Report.

The incidence of tooth wear has steadily increased in all Western populations during the past decades. A through-care strategy, extendable for a lifetime, has become crucial to prevent the extensive loss of sound dental structure and to make an eventual retreatment affordable in the long term. An interceptive treatment using resin composite materials and no-preparation approaches meets these requirements. Moreover, continual developments in digital dentistry makes possible to predict the treatment plan for the restorative rehabilitation of the mouth. The availability of digital resources allows clinicians to increase predictability for excellent esthetics and good functional results. This article provides a step-by-step description of a full-mouth additive rehabilitation achieved by employing digital workflows and direct resin composite restorations. A comprehensive functional and esthetic evaluation of the treatment is proposed and discussed.

Marginal adaptation of large adhesive class IV composite restorations before and after artificial aging.

PURPOSE: To test the marginal adaptation of Class IV restorations made of different composite materials designed for anterior use. MATERIALS AND METHODS: Forty-two extracted caries-free human maxillary central incisors were randomly divided into 7 experimental groups - one per composite tested - for which Class IV cavities were prepared. The microfilled composite materials tested (SolidBond/Durafill [D/SB], Syntac classic/Heliomolar [H/SC], Scotchbond1/ Experiment127 [EXI/SB1], Optibond FL/Point 4 [P4/OBFL], Prime&Bond NT/Esthet-X [EX/PBNT], ART Bond/ Miris [MIR/ART], SE Bond/Clearfil ST [CLE/SE-B]) were inserted in two increments after polymerization of their respective adhesive systems. While under simulated dentinal fluid pressure, specimens were submitted to cyclic incisal stress (1,200,000 cycles, maximum load 49 N) and thermal loading (3000 cycles). Both after polishing and after thermomechanical loading, impressions were made of the surface of each restoration, and epoxy replicas were prepared for the marginal adaptation evaluation using SEM. RESULTS: Perfect margins before loading in enamel ranged from 49.9% (EXI/SB1) to 98.2% (MIR/ART) and after loading from 25.3% (EXI/SB1) to 91.9% (MIR/ART). For margins located in dentin, perfect margins ranged from 16.8% (EXI/SB1) to 100% (CLE/SE-B) before loading and from 4.6% (EXI/SB1) to 67.1% (CLE/SE-B) after loading. CONCLUSION: The poor results obtained in this in-vitro test with the microfilled composites suggest avoiding their use in large Class IV restorations with margins in dentin.

In vitro evaluation of marginal adaptation in medium- and large size direct class II restorations using a bulk-fill or layering technique.

OBJECTIVES: to test if cavity dimensions and restorative protocol have potential to influence in-vitro adaptation of class II restoration after simulated thermo-occlusal stressing. METHODS: A total of 32 prepared teeth were randomly assigned to one of the 4 experimental groups depending on cavity size, composite system and filling technique; group 1: small cavity and multi-layered conventional restorative composite (Tetric Evo-ceram: TEC), group 2: small cavity and flowable bulk-filled composite (SDRFlow: SDR) + one single occlusal layer of conventional restorative composite (TEC), group 3: large cavity and multilayered conventional restorative composite (TEC) and group 4: large cavity and bulk-filled flowable composite (SDR) + one single occlusal layer conventional restorative composite (TEC). All specimens were submitted to 500'000 cycles of thermomechanical loading (50 N, 5 to 55 °C). The proximal tooth-restoration interface was analyzed quantitatively by SEM, prior and after thermomechanical loading. RESULTS: Before loading, continuous enamel adaptation varied from 61.49% (Gr 1) to 68.39% (Gr 4) proximally and from 50.93% (Gr2) to 68.65% (Gr1) cervically, with no statistical difference among groups for both segments. After thermomechanical loading, continuous enamel adaptation varied from 36.6% (Gr2) to 46.6% (Gr1) proximally, without significant difference, and from 20.2% (Gr4) to 51.3% (Gr1) cervically; statistical differences in cervical enamel adaptation were found in-between groups 1 and 2 (p = 0.0479), 1 and 4 (P = 0.0116), 2 and 3 (p = 0.0028) and 3 and 4 (p = 0.001). Before loading, dentin continuous adaptation varied from 55.32% (Gr3) to 81.82% (Gr4) with statistical difference in-between those groups (p = 0.045); after loading, dentin continuous adaptation varied from 31.56% (gr2) to 51% (Gr4) with a statistical difference between those 2 groups (p = 0.019). The drop in adaptations values after loading was significant in all groups and segments. CONCLUSIONS: The impact of the restorative technique and cavity size on marginal adaptation appeared essentially after simulated fatigue for enamel adaptation. Cervical enamel and dentin continuous adaption of small and large bulk-filled restorations dropped significantly while the change was lower in layered restorations made of conventional restorative composite. CLINICAL SIGNIFICANCE: Restorations made with bulk-filled flowable composite behaved differently from layered ones using conventional resin composite, according to cavity size and loading.

Functional assessment of the stomatognathic system. Part 2: The role of dynamic elements of analysis.

OBJECTIVES: To review the dynamic analytical elements used in the functional assessment of the stomatognathic system, summarize the available scientific evidence, and consider interrelations with body posture and cognition. METHOD AND MATERIALS: A thorough literature search was conducted using PubMed, the Cochrane Library database, and Google Scholar. Peer-reviewed articles and literature reviews provided up-to-date information addressing three topics: (a) the available knowledge and recent evidence on the relationship between the morphologic aspects of dental/craniofacial anatomy and oral function/dysfunction, (b) mandibular dynamics, considering mobility, functional activity, and existing methodologies of analysis, and (c) a possible correlation between the stomatognathic system, body posture, and cognition. RESULTS: Modern dentistry may be regarded as a human adaptation strategy, helping to conserve healthy teeth for much longer without risking overall health. It is futile to treat patients using a mechanistic, sectorial approach that misrepresents patient behavior and requests, just as it is to affirm the absence of any structure-function relationships. However, it is also evident that there is a lack of general consensus on the precise functional assessment of the stomatognathic system, mostly due to the methodologic heterogeneity employed and the high risk of bias. Despite the abundant evidence produced with the aim of providing solid arguments to define dynamic models of functional assessment of the stomatognathic system, it is yet to become highly empirical, based as it is on operator experience in daily clinical practice. CONCLUSIONS: Further efforts from the scientific and clinical community, with the help of progress in technology, remain should this gap be filled and should substantial data on differences between pathologic and physiologic dynamic models of function be provided. Dentistry needs to employ - on a larger scale - objective, dynamic methods of analysis for the functional evaluation of the stomatognathic system, embracing concepts of "personalized medicine" and "interprofessional collaborations."

Functional assessment of the stomatognathic system. Part 1: The role of static elements of analysis.

OBJECTIVES: To review the elements of static analysis in the functional assessment of the stomatognathic system, as promoted for more than a century by gnathologists, and summarize the available scientific evidence, including anthropologic observations. METHOD AND MATERIALS: A thorough search was conducted using PubMed, the Cochrane Library database, and Google Scholar. From peer-reviewed articles and other scientific literature, up-to-date information addressing three topics was identified: (a) the anthropologic perspective with particular consideration for the role of progressive dental wear over time, (b) descriptions of gnathologic principles and evidence on their scientific validity, and (c) the methodologic inaccuracies introduced by seeking to correlate variables directly rather than allowing for causal inference. RESULTS: For decades gnathology attempted to describe a structure-function correlation within the stomatognathic system by means of a model whose principles were static and mechanistic references. No scientific validation was ever achieved, placing clinical and research consensus out of reach. CONCLUSIONS: A historical perspective helps to place the fundamentals of gnathology into context: They were conceived to solve technical difficulties but were then assumed to be physiologic stereotypes. This misconception led to a decades-long promotion of mechanistic theories to describe oral function, but the evidence available today supports a more flexible and adaptable approach. Gnathologic arguments have been relegated to become exclusively of technical relevance in oral rehabilitation.

Interceptive treatment of tooth wear: a revised protocol for the full molding technique.

A modern approach to treating tooth wear aims to stop its progression at an early stage and, ideally, to install effective preventive measures or, in cases when it is already late, to intervene using an interceptive treatment approach. It is important to avoid the need for a full prosthetic treatment that implies additional tooth substance removal, with potential biologic complications. As signs of tooth wear often appear in young individuals, an interceptive treatment has the great potential of stabilizing tooth wear progression early using a no-prep approach and composite resins. The additional benefit of this treatment approach is its affordability and maintainability in the light of tooth wear being, usually, a lifelong pathology. Among the various options for restoring tooth wear lesions with composite resins, interest has lately been increasing for molding techniques (single or full) due to their efficiency and simplicity. This article describes modifications of the basic full molding technique to alleviate most of the known shortcomings of this method; namely, the index deformation, the time-consuming removal of excesses in the proximal and contact areas, and the possible insufficient precision in the molding of the occlusal anatomy. The 1- and 3-year follow-ups of both cases presented here confirmed the functional and esthetic quality of the results obtained with this technique. A kinesiographic and 3D superimposition of the posttreatment and 1-year results of one case provided additional perspectives on this treatment method.

Evidence-based concepts and procedures for bonded inlays and onlays. Part III. A case series with long-term clinical results and follow-up.

This third article in this series (Part III) aims to present new clinical results and long-term follow-up of resin composite inlays and onlays using the modern clinical concepts presented in the Part I and Part II articles. These revised protocols have contributed to eliminating the most frequent difficulties related to the preparation, isolation, impression taking, and cementation of tooth-colored inlays and onlays. This clinical report presents a series of 25 cases of indirect or semidirect inlays and onlays (intra- and extraoral techniques) made of microhybrid and nanohybrid composites with 6- to 21-year follow-ups. The restoration performance was assessed through clinical examination, intraoral radiographs, and clinical photographs. The overall clinical assessment aimed to confirm the absence (success) or presence (failure) of decay or restoration fracture, while the restoration quality was judged on intraoral photographs. The restoration status with regard to margins, anatomy, and color was assessed using three quality scores (A = ideal, B = satisfactory, C = insufficient). Descriptive statistics were used to evaluate the possible impact of composite structure (microhybrid or nanohybrid) or observation time on restoration quality. Over this medium- to long-term observation period, no clinical failure was reported. Only a few restorations (mainly those made of conventional inhomogeneous nanohybrid) presented discrete marginal discoloration (n = 4) or occlusal anatomy change due to wear (n = 7). This first clinical survey with long-term follow-up supports the application of the aforementioned clinical concepts, which thus far have only been validated by in vitro studies.

Clinical performance of direct anterior composite restorations: a systematic literature review and critical appraisal.

OBJECTIVES: The aim of this study was to systematically review the literature on the clinical behavior of direct anterior composite restorations and to identify the factors potentially influencing restoration success and longevity. MATERIALS AND METHODS: The search included all existing references until September 2016 cited in the PubMed database, the Cochrane central register of controlled trials and Cochrane Library, EMBASE, an internet search using Google internet search engine (possibly including unpublished data), a hand search (University of Geneva library), and the perusal of the references of relevant articles. Studies with appropriate research protocols and that clearly reported data about the performance of anterior composite restorations were included. Yearly failure rates (YFRs) were computed for each study based on survival rates or, when not reported, using United States Public Health Service (USPHS) scores leading to reintervention. The potential impact of the following factors was evaluated: composite filler technology (microfilled, macrofilled, nanofilled or hybrid), polymerization mode (chemical or light cured), treatment environment (academic, private or social) and operator (single or multiple). The studies were analyzed according to the observation time (< 2 years, 2 to 5 years, and > 5 years). RESULTS: 39 potential studies were identified, from which 24 met the review inclusion criteria: nine randomized controlled trials (CTs), two prospective CTs, one retrospective CT, six prospective case series (CSs), and four retrospective CSs. CONCLUSION: This review followed a standard approach and explored an alternative review process that limited the significant data loss that occurs when the meta-analysis method is used. Overall, anterior composite restorations have shown a large heterogeneity in performance, as is typically observed in reviews of clinical studies, but the present appraisal identified influential factors such as treatment environment and the number of operators.

In vitro colorimetric evaluation of the efficacy of various bleaching methods and products.

OBJECTIVE: Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficacy is unknown. The aim of this in vitro study was to evaluate the ability of different bleaching products and protocols to lighten enamel and dentin. METHOD AND MATERIALS: Bovine tooth samples of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thicknesses) were prepared and stained with whole blood and hemolysate before being submitted to 11 different bleaching regimens: home bleaching using 10%, 15%, 16%, or 20% carbamide peroxide, power bleaching using 15% hydrogen peroxide, 30% hydrogen peroxide, or 25% carbamide peroxide with or without light activation, and over-the-counter bleaching strips containing 5.3% hydrogen peroxide. Colorimetric measurements were performed on each sample side, according to the CIE L*a*b* system, before and after staining as well as after each series of 5 bleaching sessions (number of applications varied from 5 to 20 times, according to the bleaching protocol). RESULTS: All products and protocols produced a similar bleaching effect on enamel, while the home bleaching regimen proved largely superior to lighten dentin. CONCLUSION: In-office bleaching techniques proved less efficient than home bleaching for removing stains deposited in dentin.

A new shading concept based on natural tooth color applied to direct composite restorations.

OBJECTIVE: Patient demands have prompted manufacturers to improve intrinsic optical properties of resin composites and clinicians to refine application procedures. The aim of this study is to present a shading concept based on colorimetric L*a*b* and contrast ratio data of human dentin and enamel. METHOD AND MATERIALS: Extracted teeth of the A and B Vita shade groups (n = 8 per group) were sectioned according to 2 different planes to measure specific color (using the CIE L*a*b* system) and opacity (contrast ratio). Standardized samples of enamel and dentin shades of a new composite system (Miris, Coltène Whaledent) were submitted to the same colorimetric evaluation for comparison with natural tissues. RESULTS: Comparison of teeth from the Vita groups A and B having the same chroma showed limited variations regarding a* (green to red) and b* (blue to yellow) values; the only significant variation was the increasing b* values (yellow) with increasing chroma (A1 to A4 and B1 to B3). As for dentin contrast ratio, limited differences were reported, while enamel proved to increase in translucency with age (reduced contrast ratio). CONCLUSION: These data served as the foundation of the so-called natural layering concept, which makes use of 2 basic composite masses (dentin and enamel) that optically mimic natural tissues. This concept allows for simplified clinical application and layering of composite, as it uses only 1 universal dentin hue with several chroma levels and 3 enamel types for young, adult, and old patients, each exhibiting specific tints and translucency levels.

Clinical performance and marginal adaptation of class II direct and semidirect composite restorations over 3.5 years in vivo.

OBJECTIVE: The study evaluated the clinical performance and marginal adaptation of direct and semi-direct class II composite restorations in a split-mouth design over 3.5 years. DESIGN: 44 upper posterior teeth in 11 adults with primary carious lesions were treated with 22 direct and 22 semi-direct restorations. Conventional cavities were prepared for both types of restorations. A fine fine hybrid composite (APH) and a multifunctional adhesive system (Prisma universal bond 3) were used for all restorations. The incremental "3-sited light curing" technique was applied to direct restorations. Semi-direct inlays were prefabricated on silicone casts and post-cured using light and heat. Clinical performance was evaluated using modified USPHS parameters, while marginal adaptation was judged on replicas, using SEM and a standardized evaluation technique. RESULTS: Clinical results after 3.5 years revealed a 100% retention rate with no fractures, sensitivity or recurrent caries for both types of restorations. SEM-evaluation of the occlusal margins showed at the tooth-restoration interface relatively low rates of marginal openings over the observation period (4-8%). Marginal restoration fractures ranged between 1 and 2%, marginal tooth fractures between 3 and 9%. Differences between the restorative techniques and after the different time observation periods were not statistically significant. Proportions of marginal fractures and openings at the restoration-luting composite interface were less than 10% after 3.5 years. CONCLUSION: The results indicated no significant differences for direct and semi-direct fine hybrid composite restorations in medium size cavities in posterior teeth with respect to clinical performance and marginal adaptation over 3.5 years.

Polymerization shrinkage of flowable resin-based restorative materials.

This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultraseal XT and Wave). Measurements for linear polymerization displacement and polymerization forces were performed using custom made measuring devices. Polymerization of the test materials was carried out for 60 seconds by means of a light curing unit, and each property was measured for 180 seconds from the start of curing in eight specimens for each material. Statistical evaluation of the data was performed with one-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) test (p=0.05) and simple linear regression. A wide range of values was recorded for linear polymerization displacement (26.61 to 80.74 microns) and polymerization forces (3.23 to 7.48 kilograms). Statistically significant differences among materials were found for both properties studied. Very few materials (Freedom, Glacier, and Photo SC) presented low values of linear polymerization displacement and polymerization forces (similar to hybrid resin composites), while the majority of materials presented very high values in both properties studied. Study of the shrinkage kinetics revealed the exponential growth process of both properties. The polymerization forces development exhibited a few seconds delay over linear polymerization displacement. Simple linear regression showed that the two polymerization shrinkage properties that were studied were not highly correlated (r2=0.59).

Evidence-based concepts and procedures for bonded inlays and onlays. Part I. Historical perspectives and clinical rationale for a biosubstitutive approach.

This first article in the series (Part I) aims to present an updated rationale and treatment approach for indirect adhesive posterior restorations based on the best scientific and long-term clinical evidence available. The proposed treatment concept relies on the basic ideas of (1) the placement of an adhesive base/liner (Dual Bonding [DB] and Cavity Design Optimization [CDO]) and, when needed, (2) a simultaneous relocation of deep cervical margins (Cervical Margin Relocation [CMR]), prior to (3) impression taking to ensure a more conservative preparation and easier-to-follow clinical steps, and the use of (4) a highly filled, light-curing restorative material for the cementation (Controlled Adhesive Cementation [CAC]), together with restoration insertion facilitation, the application of sonic/ultrasonic energy, and/or material heating. The suggested clinical protocol will help the practitioner to eliminate the most frequently experienced difficulties relating to the preparation, isolation, impression taking and cementation of tooth-colored inlays and onlays. This protocol can be applied to both ceramics and composites as no material has been proven to be the most feasible or reliable in all clinical indications regarding its physicochemical and handling characteristics. For the time being, however, we have to regard such indirect restorations as a biosubstitution due to the monolithic nature of the restoration, with still very imperfect replication of the specific natural dentin-enamel assemblage.

Evidence-based concepts and procedures for bonded inlays and onlays. Part II. Guidelines for cavity preparation and restoration fabrication.

The second part of this article series presents an evidence-based update of clinical protocols and procedures for cavity preparation and restoration selection for bonded inlays and onlays. More than ever, tissue conservation dictates preparation concepts, even though some minimal dimensions still have to be considered for all restorative materials. In cases of severe bruxism or tooth fragilization, CAD/CAM composite resins or pressed CAD/CAM lithium disilicate glass ceramics are often recommended, although this choice relies mainly on scarce in vitro research as there is still a lack of medium- to long-term clinical evidence. The decision about whether or not to cover a cusp can only be made after a multifactorial analysis, which includes cavity dimensions and the resulting tooth biomechanical status, as well as occlusal and esthetic factors. The clinical impact of the modern treatment concepts that were outlined in the previous article - Dual Bonding (DB)/Immediate Dentin Sealing (IDS), Cavity Design Optimization (CDO), and Cervical Margins Relocation (CMR) - are described in detail in this article and discussed in light of existing clinical and scientific evidence for simpler, more predictable, and more durable results. Despite the wide choice of restorative materials (composite resin or ceramic) and techniques (classical or CAD/CAM), the cavity for an indirect restoration should meet five objective criteria before the impression.