Myocentric relation in an additive esthetic rehabilitation within a fully digital workflow.

In recent years, tooth wear has been a growing concern in dentistry as it has become increasingly prevalent among the population. At the same time, the development of adhesive techniques has enabled minimally invasive treatment protocols, with the goal of preserving and protecting teeth for as long as possible. This clinical report presents the case of a full-mouth rehabilitation patient with tooth wear who was treated using minimally invasive techniques. Esthetic and functional outcomes were designed and monitored using digital tools such as digital impressions, 3D facial scans, a digital tooth library, transcutaneous electrical nerve stimulation (TENS), MRI, and kinesiographic (KS) analysis throughout the treatment. To increase the vertical dimension of occlusion, instead of using traditional centric relation (CR) methods, a myocentric relation (MCR) technique was employed. This approach allowed the clinician to maintain the occlusal Class I situation, avoiding more invasive orthodontic treatment or maxillofacial surgery and resulting in reduced morbidity, treatment time, and cost for the patient. At the 1-year follow-up, good patient adaptation was shown, suggesting that the MCR concept is a viable alternative to conventional CR methods in appropriate cases.

An esthetic minimally invasive rehabilitation performed with a fully digital workflow and hybrid restorative approach.

AIM: The aim of the present study was to demonstrate that fully digital workflows can provide predictable esthetic and functional outcomes. MATERIALS AND METHODS: The present clinical case report provides a step-by-step documentation of a full-mouth rehabilitation planned and performed with a fully digital approach utilizing an adhesive and no-prep method. After assessing the patient's needs, a treatment plan was established that considered the patient's functional and esthetic requests. The overlap of 2D images and 3D models and facial scans of the patient allowed the digital previsualization of the esthetic result by implementing the "copy-paste" approach to restore the maxillary anterior sextant. CONCLUSION: The final outcome was satisfactory in terms of esthetics, function, and soft tissue health.

Effects of Different Fiber-Reinforced Solutions on Fracture Strength and Pattern in Endodontically Treated Molars.

PURPOSE: To evaluate the fracture strength of endodontically treated molars filled with different composite resins with vs without fiber reinforcement. MATERIALS AND METHODS: A total of 60 intact mandibular molars were selected and endodontically treated. A standardized mesio-occlusal-distal cavity was prepared with cervical margins 1 mm above the cementoenamel junction and oral and buccal walls with 1.5-mm thickness. Universal adhesive was used in all specimens in etch-and-rinse mode. Specimens were divided into four groups (n = 15 each) according to restoration technique: group CSM = adhesive overlay with hybrid ceramic; group EXP = direct restoration with short fiber-reinforced composite; group ESU = direct restoration with nanohybrid composite; and group EST = direct restoration with nanohybrid composite reinforced with horizontal bidirectional glass fibers placed over the pulpal chamber floor. After 7 days of storage in water, samples were loaded until fracture using a universal testing machine. The maximum breaking loads were recorded in Newtons, and statistical analysis was then conducted with two-way ANOVA and post hoc Tukey test. Fragments were analyzed using scanning electron microscopy. RESULTS: Mean fracture resistance values were: CSM = 1,428.91 ± 316.90 N; EXP = 1,874.57 ± 299.47 N; ESU = 1,557.44 ± 355.65 N; and EST = 1,870.27 ± 145.11 N. The CSM and EXP groups showed the highest strength values when compared to the other groups. The variable fiber insertion did not significantly alter the fracture resistance. The origin of the fracture was always located on the occlusal surface, mainly in the major contact loading area. CONCLUSION: The use of fiber-reinforced composite showed great improvement in fracture resistance, similar to a cuspal coverage restoration. However, only short fiber-reinforced composites showed a favorable fracture pattern. Int J Prosthodont 2023;36:603-611.

Crack propagation and toughening mechanism of bilayered short-fiber reinforced resin composite structure -Evaluation up to six months storage in water.

Clinically relevant parameters, such as stress intensity factor of bilayered resin composite structure with short fiber base and its stability over time, has yet to be investigated. This study investigated the stress intensity factor of pre-cracked bilayered specimens composed of short fiber resin composite base (SFC) and particulate filler resin composite (PFC) as veneering layer, with a crack located in the PFC layer, 0.5 mm away from the PFC-SFC interface. Monolayered specimens served as controls. All specimens were stored in water at 37°C either for 1 week, 1 month or 6 months before testing. Two-way ANOVA (p=0.05) was used to determine the differences among the groups. Results indicated that SFC base improve the brittleness of the PFC. The type of short fibers affected the crack propagation; fiber bridging in millimeter-scale SFC was the main crack arresting mechanism, whereas fiber pulling observed in micrometer-scale SFC mainly deviated the crack path.

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.

Influence of Needle Design and Irrigant Flow Rate on the Removal of Enterococcus faecalis Biofilms In Vitro.

This study aimed to evaluate the influence of needle design and irrigant flow rate on the removal of Enterococcus faecalis mature biofilms during sodium hypochlorite irrigation. Forty-eight single-rooted human teeth were instrumented (ProTaper F3), autoclaved and inoculated with Enterococcus faecalis to establish a two-week-old biofilm. E. faecalis biofilms were treated with Sodium hypochlorite that was injected in the root canals using three types of needles (NaviTip, ProRinse, IrriFlex). For the IrriFlex needle, one, two, or four bars of pressure was applied to the irrigating solution to increase flow rates. Bacteria were labeled with the LIVE/DEAD BacLight Bacterial Viability kit, and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α = 0.05). Bacterial viability was significantly reduced after sodium hypochlorite passive irrigation but the number of viable bacteria retrieved from root canal specimens irrigated with the Pro-Rinse needle was significantly higher compared to NaviTip and IrriFlex needles (p < 0.05). When the irrigant flow rate was increased, the viability of bacterial biofilms was significantly reduced compared to passive irrigation using the IrriFlex needle (p < 0.05). Applying higher flow rates during irrigation using the IrriFlex needle did not further reduce bacterial viability.

Clinical outcome of bonded partial indirect posterior restorations on vital and non-vital teeth: a systematic review and meta-analysis.

OBJECTIVES: The survival rate of indirect partial adhesive restorations on vital versus endodontically treated teeth is still controversial. The hypothesis is that there may be a difference in the survival rate of partial adhesive restorations performed on non-vital teeth compared to vital teeth. MATERIALS AND METHODS: This systematic review was conducted following the PRISMA guidelines. The considered clinical studies investigated the outcomes of adhesive inlays, onlays, and overlays conducted over the past 40 years, focusing on Kaplan-Meier survival curves to calculate the hazard ratio (primary objective) and the survival rate (secondary objective) between vital and non-vital teeth. The risk of bias was assessed using the Newcastle-Ottawa Scale. Studies included in the review were identified through bibliographic research on electronic databases ("PubMed," "Scopus," "Cochrane Central Register of Controlled Trial," and "Embase"). The K agreement between the two screening reviewers was evaluated. RESULTS: A total of 55,793 records were identified on PubMed, Scopus, and other bibliographic sources, and after the application of the eligibility and inclusion criteria, eight articles were included for qualitative analysis and six for quantitative analysis. The meta-analysis of the primary and secondary outcomes demonstrated that hazard ratios (HR = 8.41, 95% CI: [4.50, 15.72]) and survival rates (OR = 3.24, 95% CI: [1.76, 5.82]) seemed more favorable for indirect partial adhesive restorations on vital teeth than for those on endodontically treated teeth. CONCLUSIONS: Within the limits of this study, these findings suggest that the risk of failure of indirect partial adhesive restorations on endodontically treated teeth is higher than on vital teeth. CLINICAL RELEVANCE: The use of partial adhesive restorations on vital and endodontically treated teeth showed different long-term clinical outcomes.

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.

Do Chemical-Based Bonding Techniques Affect the Bond Strength Stability to Cubic Zirconia?

This study evaluated the effectiveness of chemical-based adhesive techniques on promoting immediate and aged bond strength between zirconia and luting cement. A total of 128 discs of zirconia were divided into 4 groups (n = 32) according to the adhesive treatment: tribochemical silica-coating followed by silane (Silane Primer, Kerr) and bonding (Optibond FL, Kerr), Signum Zirconia Bond (Hereaus), Z-Prime Plus (Bisco), and All-Bond Universal (Bisco). Composite cylinders were cemented on the zirconia sample with Duo-Link Universal (Bisco). Eight specimens per group were subjected to 10,000 thermocycles and subsequently bond strength was tested with shear-bond strength test. ANOVA test showed that artificial aging significantly affected the bond strength to zirconia. Bonferroni test highlighted a significant influence of adhesive treatment (Signum) on bond strength after thermocycling. It was concluded that 10-MDP-based bonding systems showed no improvement in initial bond strength compared with tribochemical treatment. All chemical bonding techniques tested in this study were influenced by thermocycling.

The influence of FRC base and bonded CAD/CAM resin composite endocrowns on fatigue behavior of cracked endodontically-treated molars.

Cracked endodontically treated molars (ETMs) are commonly treated with full crowns. Less invasive techniques could include fiber-reinforced composite (FRC) base and adhesively bonded endocrowns. The purpose of this study was to assess the fatigue resistance of ETMs restored with CAD/CAM resin composite endocrowns and reinforced with different FRC bases. Cracks were simulated in fifty mandibular molars by cutting the teeth longitudinally and reassembling the two parts. After performing endodontic treatments and preparing cavities, teeth were restored in one of the following methods (n = 10). In Group 1, cavity floors were lined with 0.5 mm of flowable composite (Universal Injectable; GUI, shade A2). In Groups 2 and 3, the cavity floors were covered with one and three layers of FRC-net (ES Net) respectively, whereas in Groups 4 and 5 with 1 mm and 2 mm of flowable FRC-resin (EverX Flow Dentin; EXFD) respectively. Endocrowns (Cerasmart 270; CE, A2 HT) with 5 mm thickness were adhesively luted with preheated composite and all specimens were subjected to cyclic loading in water at 5 Hz, starting with a load of 600 N (5000 cycles), followed by stages of 1000, 1300, 1600, 1900, 2200 and 2500 at a maximum of 20 000 cycles each. Results were analyzed using Kaplan-Meier survival analysis and the Log-Rank test (p = 0.05). The fatigue failure load of ES Net applied in three layers (1617 N ± 371) or in one layer (1499 N ± 306), as well as EXFD applied in 2 mm (1496 N ± 264) or in 1 mm (1434 N ± 372) did not differ significantly (p > 0.05). Control teeth fractured at 1255 N ± 350 (p > 0.05). In the fiber-reinforced groups, restorable fractures were observed in 50%-80%, with only 30% deemed restorable in the control group. The fractures originated mainly at the occlusal contact points and the main crack propagated in the corono-apical direction. No crack origin (primary or secondary) starting from the artificial pre-existing crack was observed in fractured specimens. FRC bases did not improve the fatigue resistance of cracked ETMs, but favorably influenced the failure mode.

Could different direct restoration techniques affect interfacial gap and fracture resistance of endodontically treated anterior teeth?

OBJECTIVES: To evaluate different direct restoration techniques on various cavity designs in anterior endodontically treated teeth (ETT). MATERIALS AND METHODS: Ninety upper central incisors (n = 90) were selected, endodontically treated, and divided into three groups (n = 30) accordingly to the cavity design: minimal endodontic cavity access (group A), endodontic access + mesial class III cavity (group B), and endodontic access + two class III cavities (group C). Three subgroups (n = 10) were then created accordingly to the restoration technique: nano hybrid composite restoration (subgroup a), glass fiber post + dual-cure luting cement (subgroup b), and bundled glass fiber + dual-cure luting cement (subgroup c). Samples underwent micro-CT scan, chewing simulation, and a second micro-CT scan. 3D quantification (mm3) of interfacial gap progression was performed; then, samples underwent fracture resistance test. Data were statistically analyzed setting significance at p < 0.05. RESULTS: Groups A and B showed significantly lower interfacial gap progression compared with group C. Subgroup b performed significantly better compared with subgroups a and c. Improved fracture strength was reported for group C compared with group A, while both subgroups b and c performed better than subgroup a. CONCLUSIONS: Cavity design significantly influenced interfacial gap progression and fracture resistance. Fiber posts significantly lowered gap progression and improved fracture resistance while bundled fibers only increased fracture resistance. A significant reduction of non-repairable fractures was recorded when fibers were applied. CLINICAL RELEVANCE: A minimally invasive approach, conserving marginal crests, should be applied whenever possible. Inserting a fiber post is indicated when restoring anterior ETT, in order to reduce gap progression, improve fracture resistance, and avoid catastrophic failures.

Restoration's thickness and bonding tooth substrate are determining factors in minimally invasive adhesive dentistry.

Purpose To explore fracture strength and failure behaviour of minimally invasive CAD-CAM composite resin overlay restorations.Methods Eighty bi- and tri-layer cylindrical overlay model including the restoration bonded over bovine tooth dentin (Groups D) and enamel-dentin (Groups E) were assembled (diameter 9 mm). Restorations were milled from CAD-CAM composite resin blocks (Brilliant Crios, Coltène/Whaledent AG) in different thicknesses (0.5mm, 1mm, 1.5mm, 2mm) and equally distributed in four Groups D and four Groups E (n=10). All specimens were submitted to an Hertzian load-to-failure contact test with spherical indenter. Critical loads were recorded in Newton and data were analysed using Kruskal-Wallis test for multiple and Mann-Whitney test for 2-samples comparisons (p < 0.05). Fragments were examined using SEM. The stress distribution for specimens with restorations of 0.5 mm and 2 mm was also investigated with FEA.Results For all specimens, the mean static loads in Newton increased with an increase in restoration thickness. On contrary, restorations with the same thickness displayed higher resistance values when bonded over enamel than dentin, except for the 2-mm thick restorations. A damage competition was detected between cone/median cracks originating at the loading contact area of the restorations and radial cracks beginning at their inner surface, with the former prevailing in restorations bonded on enamel and the latter being dominant for restorations bonded on dentin.Conclusions For bonded ultra-thin resin composite restorations (0.5 mm to 1.5 mm) enamel as bonding substrate assures higher critical loads to fracture than dentin. This influence gradually decreases as restoration thickened.

Full-mouth rehabilitation of a severe tooth wear case: a digital, esthetic and functional approach.

The proliferation of digital technology is progressively changing dentistry. Thanks to continual improvements in CAD/CAM devices and dental materials, it is possible nowadays to carry out a treatment plan for oral rehabilitations with fully digital approaches and noninvasive concepts. The availability of digital resources allows clinicians to increase the predictability of enhanced esthetics and good functional results. There is an increasing number of patients today who are affected by excessive tooth wear and may benefit from these kinds of treatments. This article provides a step-by-step documentation of a full-mouth rehabilitation performed with a digital approach and additive CAD/CAM composite resin restorations. An innovative functional evaluation is also documented and discussed. The initial situation was assessed and compared with the rehabilitation project through a snap-on device. After the intraoral adjustment and validation, the final rehabilitation was performed according to the information obtained in the provisional phase and digitally transmitted to the laboratory.

The potential of three-dimensional printing technologies to unlock the development of new 'bio-inspired' dental materials: an overview and research roadmap.

PURPOSE: Bio-inspiration is an approach in engineering aimed at optimizing artificial systems by borrowing biological concepts from nature. This review sets out to summarize the fundamental aspects employed by nature to avoid premature dental failures. On the basis of these findings, it then defines and evaluates rules for 'post-modern' manufacturing processes to imitate or regenerate complex biological systems. STUDY SELECTION: A thorough literature search was conducted using PubMed, the Cochrane Library database and Google Scholar. Peer-reviewed articles and other scientific literature provided up-to-date information addressing two topics: (a) how natural dental tissues combine to create a structure as tough, strong and highly resistant to fatigue failure as tooth, and (b) how 'bio-inspiration' can be applied to the manufacture of dental restorations, taking into consideration the limitations of techniques currently used in dentistry. RESULTS: Bio-inspired concepts have already been successfully applied in a range of engineering fields to enhance the toughness and strength of artificial materials. The area of technology with greatest potential to unlock the development of these new approaches is additive manufacturing. Consequently, these technologies and concepts could be applied to dentistry to improve the mechanical properties of dental restorations. Three-dimensional (3D) printing technologies also offer a new and promising prospect of regenerating dental tissues. CONCLUSIONS: Considering the limitations to both conventional and subtractive computer-aided design/computer-aided manufacturing (CAD/CAM) methods, further research should focus on new, additive 3D-printing techniques. This may open new research paths in dentistry that will enhance the clinical performance of artificial dental materials.

Restoration of discolored endodontically treated anterior teeth: a minimally invasive chemomechanical approach.

In the case of discolored devitalized anterior teeth, several treatments are available to enhance the esthetic outcome, from noninvasive external/internal bleaching to freehand resin composites and more complex prosthetic solutions such as veneers or full crowns. Innovative computer-aided design/computer-aided manufacturing (CAD/CAM) chairside technologies and the introduction of new industrially polymerized composite resin blocks coupled with modern adhesive strategies have reduced both biological and financial costs compared to the classic post-core-crown approach. The aim of this article is to show how these new materials can be used in association with noninvasive internal and external tooth bleaching to restore a discolored, fractured, non-vital central incisor.

Vertical dimension augmentation with a full digital approach: a multiple chairside sessions case report.

The last few decades have seen an upward trend of the pathologies of abrasion, erosion, and abfraction. These pathologies, especially in combination, can provoke a significant loss of tooth substance. Nowadays, modern digital chairside technologies and new restorative materials allow clinicians to restore the lost tooth structure with a minimally invasive and fully digital approach. This article describes a step-by-step procedure of a full-mouth rehabilitation performed with a total digital chairside approach in several appointments.

Multiple diastema closure in periodontally compromised teeth: How to achieve an enamel-like emergence profile.

This article describes a direct composite resin technique for the closure of multiple diastemas. The described procedure allows an anatomic and esthetic emergence profile of the apical third of the tooth to be obtained in periodontally compromised teeth without the use of interproximal wedges.

The influence of FRCs reinforcement on marginal adaptation of CAD/CAM composite resin endocrowns after simulated fatigue loading.

To evaluate the marginal adaptation of endodontically treated molars restored with CAD/CAM composite resin endocrowns either with or without reinforcement by fibre reinforced composites (FRCs), used in different configurations. 32 human endodontically treated molars were cut 2 mm over the CEJ. Two interproximal boxes were created with the margins located 1 mm below the CEJ (distal box) and 1 mm over the CEJ (mesial box). All specimens were divided in four groups (n = 8). The pulp chamber was filled with: group 1 (control), hybrid resin composite (G-aenial Posterior, GC); group 2, as group 1 but covered by 3 meshes of E-glass fibres (EverStick NET, Stick Tech); group 3, FRC resin (EverX Posterior, GC); group 4, as group 3 but covered by 3 meshes of E-glass fibres. The crowns of all teeth were restored with CAD/CAM composite resin endocrowns (LAVA Ultimate, 3M). All specimens were thermo-mechanically loaded in a computer-controlled chewing machine (600,000 cycles, 1.6 Hz, 49 N and simultaneously 1500 thermo-cycles, 60 s, 5-55 °C). Marginal analysis before and after the loading was carried out on epoxy replicas by SEM at 200× magnification. For all the groups, the percentage values of perfect marginal adaptation after loading were always significantly lower than before loading (p < 0.05). The marginal adaptation before and after loading was not significantly different between the experimental groups (p > 0.05). Within the limitations of this in vitro study, the use of FRCs to reinforce the pulp chamber of devitalized molars restored with CAD/CAM composite resin restorations did not significantly influenced their marginal quality.

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.