Complications and survival rates of inlays and onlays vs complete coverage restorations: A systematic review and analysis of studies

Is immediate dentin sealing a mandatory or optional clinical step for indirect restorations?

OBJECTIVE

The use of immediate dentin sealing (IDS) following tooth preparation for indirect restorations is well-supported by laboratory studies. The inclusion of IDS as a mandatory clinical step, it must be firmly supported by evidence from randomized clinical trials (RCT). The objective of this study is to assess whether IDS should be added as a mandatory procedure in all indirect restorations, taking into consideration clinically significant outcomes for the patient, such as restoration longevity and hypersensitivity.

MATERIALS AND METHODS

A bibliographic search was carried out in the PubMed. In addition, a manual search was conducted in the references of literature reviews.

RESULTS

Data from four RCT were included. Two studies assessed preparations for full crowns, and two assessed preparations for partial restorations. Data from full crown preparations were subjected to a meta-analysis, revealing a reduction in hypersensitivity incidence in the IDS group 1 week after restoration cementation. With respect to hypersensitivity, IDS seems to offer advantages exclusively during the provisional phase and up to 1 week following the cementation of the final restoration. One study has shown no difference on longevity.

CONCLUSION

The use of IDS should be considered as an elective clinical step during the rehabilitation with indirect restorations.

CLINICAL SIGNIFICANCE

IDS is an elective clinical step that should be considered in patients and preparations with a higher risk of sensitivity between appointments.

Fracture resistance of chairside CAD-CAM lithium disilicate occlusal veneer with various designs after mechanical aging

PURPOSE

This study evaluated the fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate crown, onlay, and non-anatomical occlusal veneer (A-OV) with and without margin fabricated.

MATERIALS AND METHODS

Sixty-four CAD-CAM lithium disilicate restorations were designed as (1) complete coverage crown (CCC); (2) A-OV with margin; (3) non-A-OV with margin (NA-OV-M); and (4) non-A-OV without margin (NA-OV-NM), 16 of each. Restorations were crystallized and adhesively luted to resin dies using resin cement. Specimens were then subjected to 400,000 cycles of chewing in a mastication simulator. A universal testing machine was used to apply a compressive load at a crosshead speed of 1 mm/min to the long axis of the tooth with a stainless-steel sphere until fracture occurred. One-way ANOVA followed by post hoc tests were used to assess the impact of preparation design on the fracture load of CAD-CAM lithium disilicate restorations.

RESULTS

The highest fracture load was recorded for CAD-CAM lithium disilicate indirect restorations for non-A-OVs preparation with margin (2549 ± 428 N) and onlay (2549 ± 293 N) and the lowest fracture load was recorded for CCCs (2389 ± 428 N); however, there was no significant (p = 0.640) between groups.

CONCLUSIONS

CAD-CAM lithium disilicate restorations fabricated for anatomical and non-A-OV preparation display a fracture resistance similar to CCCs. Conservative partial coverage restorations may be considered an acceptable approach for posterior teeth.

Long-term performance of ceramic in/-onlays vs. cast gold partial crowns - a retrospective clinical study

OBJECTIVES

To assess the long-term clinical performance of ceramic in-/onlays (CIOs) and cast gold partial crowns (CGPCs) in posterior teeth in terms of success, survival, complications (biological, technical) and quality.

MATERIAL AND METHODS

In a retrospective study, a total of 325 patients were recorded after up to 24.8 years (mean 13.9 ± 3.8 years) having (pre-)molars restored with CIO (Empress I, Ivoclar Vivadent, n = 161) and CGPC (Degunorm, DeguDent, n = 164) by supervised undergraduate students. A total of 296 restorations were assessed clinically and radiologically in healthy and endodontically treated teeth using modified United States Public Health Service (USPHS) criteria. Cumulative success and survival rates of the restorations were calculated using Kaplan-Meier estimates. Biological and technical complications were recorded. Status of oral health comprising caries risk and localized periodontitis were assessed.

RESULTS

The cumulative success rates of CIOs were 92.1% and of CGPCs 84.2% after mean service times of 14.5 years. The annual failure rates of total service times were 0.5% in teeth restored with CIO (n = 155) and 0.7% in teeth restored with CGPC (n = 163). The cumulative survival rates of CIOs were 93.9% after a mean service time of 15.2 years and decreased to 91.7% after 23.5 years. The cumulative survival rates of CGPCs were 92.6% after a mean service time of 14.9 years and 91.8% after 23.5 years. Complications in CIOs (n = 149) were ceramic fracture (6.7%), secondary caries (4.7%), endodontic complication (2.7%) and tooth fracture (1.3%) compared to CGPCs (n = 147) with endodontic complication (8.8%), secondary caries (4.8%) and decementation (2.0%). Endodontically treated teeth restored with CIO or CGPC revealed significantly less often success compared with corresponding vital teeth (p = .02). CIOs and CGPCs revealed clinically and radiographically good and excellent qualities with 71.8% (107/149) and 68% (100/147) without any significant differences regarding type of restoration.

CONCLUSIONS

Both CIOs and CGPCs achieved high survival rates up to 24.8 years when performed by supervised undergraduate students. The longevity of the restorations may benefit from the intraoral repair of accessible defects and, in case of pulp infection or necrosis, an adequate endodontic management.

CLINICAL RELEVANCE

CIOs and CGPCs made by supervised undergraduate students are proper restoration types in posterior teeth in the long-term. An adequate preparation design, meticulous care in the inserting technique and constant biofilm removal due to proper oral hygiene combined with professional maintenance care are substantial. The clinical long-term performance was mostly limited by ceramic fractures in CIOs and endodontic complications in CGPCs.

Performance of posterior third-generation monolithic zirconia crowns in a complete digital workflow: A three-year prospective clinical study

Background/purpose

Translucent monolithic zirconia restorations have recently introduced. The purpose of this study was to evaluate the clinical behavior and the survival rate of the posterior third-generation monolithic zirconia crowns (MZCs) during three years of clinical service.

Materials and methods

Twenty-four patients who needed thirty crowns were enrolled in this study. Digital impressions were made, and the crowns were milled and cemented with a resin cement. The crowns outcomes were assessed using the California Dental Association's (CDA) criteria. Gingival index (GI), plaque index (PI), and periodontal probing depth (PPD) for MZCs and contralateral natural teeth (control) were assessed. Margin index (MI) for MZCs was also assessed. Data analysis was conducted using the Wilcoxon signed-rank and the Friedman tests.

Results

The 3-year survival rate was 100%. All MZCs were rated as satisfactory throughout the follow-up period, and no biological or mechanical complications were observed. No differences were recorded when GI, PI and PPD at 3-year of follow-up were compared to baseline. No differences were recorded between crowned and control teeth. The MI remained stable throughout the study period.

Conclusion

The third-generation monolithic zirconia appears to be a good treatment option for the rehabilitation of posterior single teeth.

Effect of surface finish and resin cement on the bond strength to CAD-CAM ceramics for interim resin-bonded prostheses

STATEMENT OF PROBLEM

Resin-bonded prostheses, including interim resin-bonded prostheses, are effective in preserving tooth structure compared with other types of fixed dental prostheses for the replacement of missing teeth. However, loss of retention remains a notable concern with these types of prostheses.

PURPOSE

The purpose of this in vitro study was to investigate the influence of glass-ceramic type, resin type, and surface finish on the shear bond strength (SBS) to the CAD-CAM ceramics used to fabricate interim resin-bonded prostheses.

MATERIAL AND METHODS

Eighty 10×2-mm glass-ceramic disks were fabricated by using a diamond saw (IsoMet 1000), 40 from feldspathic porcelain blocks (Vita Mark II) and 40 from lithium disilicate blocks (IPS e.max CAD). Half of the specimens in each group were left with a dull or matte surface finish after cutting, while the other half were glazed with an add-on glaze (VitaAkzento Plus Glaze Spray and IPS e.max CAD Glaze Spray, respectively). The disks were mounted in acrylic resin, and each group was subdivided into 2, with 1 receiving a photopolymerized resin cement (RelyX Veneer) and the other receiving a flowable composite resin (Filtek Supreme Ultimate Flow) to form 2.38×2-mm cylinders. SBS was determined using a universal testing machine (Instron 4411) in accordance with the International Organization for Standardization (ISO) 29022:2013 standard, and failure modes were analyzed by using a stereomicroscope with ×40 magnification. The data were analyzed with a 3-way analysis of variance and Tukey post hoc analysis. The chi-squared test was used to analyze the failure mode (α=.05 for all tests).

RESULTS

Ceramic type, resin type, and surface finish significantly impacted SBS (P<.001, P=.003, P<.001, respectively). Lithium disilicate showed higher SBS than feldspathic porcelain, and flowable composite resin exhibited higher SBS than resin cement. Glazed surfaces displayed lower SBS compared with the dull or matte surfaces. The combinations among the 3 materials also impacted SBS (P=.03). In addition, the combinations between ceramic type and surface finish affected SBS (P<.001), regardless of resin cement type. No other combinations affected the SBS (P>.05). The mode of failure was different among the groups (P<.001). In comparison with all other groups, cohesive failures were most prevalent in feldspathic porcelain with a dull or matte surface finish, regardless of the resin type used.

CONCLUSIONS

The SBS to glass-ceramics was influenced by ceramic material, resin cement type, and surface finish. Flowable composite resin showed higher SBS than resin cement. A dull or matte surface finish exhibited greater bond strength than a glazed surface. Lithium disilicate had higher SBS than feldspathic porcelain.

Do onlays and crowns offer similar outcomes to posterior teeth with mesial-occlusal-distal preparations? A systematic review

OBJECTIVE

Teeth prepared for mesial-occlusal-distal (MOD) restorations have a significant risk of cusp fracture. Crowns and onlays can provide cusp coverage to reinforce posterior teeth at risk. Onlays are often more conservative of tooth structure which may be an advantage for teeth with large MOD preparations. It remains uncertain how onlays and crowns compare for posterior teeth with MOD tooth structure loss. The purpose of this systematic review was to compare the resistance to fracture, success rate, survival rate, and failure rate of teeth with MOD preparations restored with onlays or crowns.

MATERIALS AND METHODS

An electronic search queried Medline (PubMed), Embase (Ovid), Scopus, the Cochrane Library, and grey literature (OpenGrey) from database inception through April 29, 2023.

RESULTS

After eliminating duplicates and irrelevant records, 32 manuscripts were assessed. Only three publications met the criteria for inclusion. Most exclusions were due to poor reporting of restorative design and the amount of tooth structure remaining, or due to combining various restorative designs. Due to the limited sample size and high heterogeneity, no meta-analysis was conducted. One study observed a better outcome for onlays and two observed no difference. All three studies reported the mode of failure for crowns as more catastrophic whereas teeth with onlays could be salvaged.

CONCLUSIONS

Onlays may be an advantageous alternative to crowns for teeth with MOD preparations, but the level of evidence is insufficient to draw meaningful conclusions.

CLINICAL SIGNIFICANCE

Current evidence is insufficient to determine whether onlays or crowns are providing a different outcome when used to restore posterior teeth with MOD tooth structure loss. However, the fracture of teeth with MOD tooth structure loss restored with onlays appears to be less catastrophic than when restored with crowns.

Minimally invasive CAD/CAM lithium disilicate partial-coverage restorations show superior in-vitro fatigue performance than single crowns

OBJECTIVE

To analyze the influence of restoration design (partial-coverage restoration vs. crown) and ceramic layer thickness on the performance and failure loads of CAD/CAM-fabricated lithium disilicate (LDS) reconstructions on molars after fatigue.

MATERIALS AND METHODS

Seventy-two posterior monolithic CAD/CAM-fabricated LDS restorations (IPS e.max CAD, Ivoclar Vivadent) with different occlusal/buccal ceramic layer thicknesses (1.5/0.8, 1.0/0.6, and 0.5/0.4 mm) and restoration designs (PCR: non-retentive full-veneer/partial-coverage restoration, C: crown,) were investigated and divided into six groups (n = 12, test: PCR-1.5, PCR-1.0, PCR-0.5; control: C-1.5, C-1.0, C-0.5). LDS restorations were adhesively bonded (Variolink Esthetic DC, Ivoclar Vivadent) to dentin-analogue composite dies (Z100, 3M ESPE). All specimens were subjected to thermomechanical loading (1.2 million cycles, 49 N, 1.6 Hz, 5-55°C) and exposed to single load to failure testing. Failure analysis was performed with light and scanning electron microscopies. Data were statistically analyzed using ANOVA, Tukey-Test, and t-test (p < 0.05).

RESULTS

Eight crown samples (C-0.5) and one PCR specimen (PCR-0.5) revealed cracks after fatigue, resulting in an overall success rate of 87.5% (crowns: 75%, PCRs: 96.88%). Direct comparisons of PCRs versus crowns for thicknesses of 0.5 mm (p < 0.001) and 1.0 mm (p = 0.004) were significant and in favor of PCRs. Minimally invasive PCRs (0.5 and 1.0 mm) outperformed crowns with the identical ceramic thickness. No difference was detected (p = 0.276) between thickness 1.5 mm PCRs and crowns.

CONCLUSIONS

Minimally invasive monolithic CAD/CAM-fabricated posterior LDS PCRs (0.5 and 1.0 mm) resulted in superior failure load values compared to minimally invasive crowns. Minimally invasive crowns (0.5 mm) are prone to cracks after fatigue.

CLINICAL SIGNIFICANCE

Minimally invasive CAD/CAM-fabricated LDS PCR restorations with a non-retentive preparation design should be considered over single crowns for molar rehabilitation.

The loss of resin cement adhesion to ceramic influences the fatigue behavior of bonded lithium disilicate restorations

When partial and/or non-retentive preparation, such as those for occlusal veneers, is indicated, a proper and stable adhesion is essential. Therefore, the aim of this in vitro study was to evaluate the effect of loss of adhesion in different regions of the bonding interface on the fatigue behavior of simplified lithium disilicate restorations. For this, lithium disilicate (IPS e.max CAD) discs (1 mm thick and Ø = 10 mm) were fabricated, polished with #400-, #600-, #1200-grit silicon carbide (SiC) papers, and crystallized. As substrate, fiber-reinforced resin epoxy discs (2.5 mm thick and Ø = 10 mm) were fabricated and polished with #600-grit SiC paper. The ceramic bonding surface was treated with 5% hydrofluoric acid and a silane-containing primer (Monobond N), while the substrate was etched with 10% hydrofluoric acid followed by the application of the bonding system primers (Primer A + B). A lacquer (nail polish) was used to simulate the loss of adhesion in specific areas according to the study design to compose the testing groups: bonded (control; did not received nail polish application); - non-bonded (loss of adhesion in the whole specimen area); - margin (loss of adhesion in the ceramic margin); - center (loss of adhesion in the ceramic central area). The adhesive area of partially bonded groups was 50% of the adhesive surface. Then, the discs (n = 12) were bonded to the respective substrate using a resin cement (Multilink N), light-cured, water-stored for 90 days, and subjected to thermocycling (25,000 cycles, 5° to 55 °C) before testing. A cyclic fatigue test was run (20 Hz, initial load of 200 N for 5000 cycles, 50 N step size for 10,000 cycles each until specimen failure), and the fatigue failure load and number of cycles for failure were recorded. As complementary analysis, finite element analysis (FEA) and scanning electron microscopy analysis were performed. Kaplan-Meier log-rank (Mantel-Cox) was conducted for survival analysis. The results showed that as the loss of adhesion reaches the central area, the worse is the fatigue behavior and the higher is the stress peak concentration in the ceramic bonding surface. The bonded specimens presented better fatigue behavior and stress distribution compared to the others. In conclusion in a non-retentive preparation situation, proper adhesion is a must for the restoration fatigue behavior even after aging; while the loss of adhesion reaches central areas the mechanical functioning is compromised.

Clinical evaluation of lithium disilicate versus indirect resin composite partial posterior restorations - A 7.8-year retrospective study

OBJECTIVE

To evaluate retrospectively the longevity of lithium disilicate ceramic (LidiSi) vs. laboratory-processed resin-based composite (RBC) inlay/onlay/overlay restorations and risk factors associated with restoration deficiencies and failures.

METHODS

Patients (n = 91) receiving LidiSi (73.1%) and RBC (36.9%) inlays/onlays/overlays between 2007 and 2017 were selected. The restorations were evaluated using the modified U.S. Public Health Service criteria. The survival of the restorations was analyzed using the Kaplan-Meier method and log rank test. Factors affecting the occurrence of deficiencies were examined by logistic regression analysis. This was performed with the use of the Generalized Estimating Equation model including Repeated measurements (GEER), with the consideration that the same patient had several teeth in the sample. Risk estimation was conducted for each evaluated criterion (p < 0.05).

RESULTS

The survival of LidiSi and RBC restorations were 96.8% and 84.9%, respectively after a mean observation period of 7.8 ± 3.3 years. The annual failure rate was 0.2% for LidiSi and 1.0% for RBC. The probability of survival was above 98% for both restorations in the first 6 years, however, it dropped to 60% for RBC by the end of the 15th year. For both materials the reasons for failure included secondary caries, restoration fracture, and endodontic complication. In addition, LidiSi also failed due to tooth fracture, while RBC due to marginal gap formation and loss of retention. Among the evaluated risk factors, material of restoration (OR=6.8, CI95%:3.1-14.9), oral hygiene (OR=8.0, CI95%: 2.9-22.1], and bruxism (OR=1.9, CI95%: 1.1-3.3) showed a significant impact on the evaluated criteria.

SIGNIFICANCE

LidiSi and RBC restorations showed similarly excellent 6-year survival, however, in the long term significantly more failures should be expected for RBCs.

Loss of pulp vitality correlated with the duration of the interim restoration and the experience of the dentist: A retrospective study

STATEMENT OF PROBLEM

The second most common biological complication in fixed prosthodontics is loss of pulp vitality, which may lead to restoration loss. While reasons for loss of pulp vitality are unclear, 2 potential contributing factors, duration of the interim restoration and operator experience, have not been fully investigated.

PURPOSE

The purpose of this retrospective study was to investigate whether the duration of the interim restoration or the experience of the dentist was correlated with loss of pulp vitality.

MATERIAL AND METHODS

Fixed prosthetic restorations placed between 2005 and 2012 were retrospectively analyzed. Abutment teeth supporting single-unti or multiunit restorations were evaluated regarding loss of pulp vitality. The Mann-Whitney U test and simple logistic regression were used, with α=.05 for the subsequent multiple logistic regression. The experience of dental professionals was defined by the number of treatments performed and coupled with failure rate by using an analysis of variance.

RESULTS

One hundred seventy-four dentists made 15 879 restorations, of which 1136 failed during the observation period, a failure rate of 7.2%. Two hundred fifty restorations were randomly selected from the failed restorations, and a corresponding 250 restorations were randomly selected from nonfailed restorations for the control group. Increased duration with interim replacement was linked to a higher risk of loss of pulp vitality (P<.001). Failure rate in the dentist group varied from 0% to 100%. No significant differences in failure rate were found among dentists who did few restorations and those who performed larger numbers of restorations.

CONCLUSIONS

The results of the present study suggest that operator experience does not affect failure rate. However, extended time with an interim restoration was a contributing factor to the loss of pulp vitality.

The influence of core-build up materials on biaxial flexural strength of monolithic strength-gradient zirconia; an in-vitro study

BACKGROUND

Since their introduction, there has been limited research regarding the mechanical properties of novel strength-gradient monolithic zirconia. In addition to that, studies evaluating the effect of different core-build materials on the strength of indirect restorations are scarce. Therefore, the aim of this study was to investigate the effect of using different core build-up materials on biaxial flexural strength of a new monolithic multilayered zirconia material.

METHODS

Forty zirconia discs were fabricated from IPS e.max ZirCAD Prime (Ivoclar Vivadent AG, Schaan, Liechtenstein) and divided into 2 groups (n = 20). Forty composite discs were prepared from Tetric N-Ceram (Ivoclar Vivadent AG, Schaan, Liechtenstein) and MultiCore Flow (Ivoclar Vivadent AG, Schaan, Liechtenstein). The zirconia discs were adhesively cemented to the 2 types of composite forming 2 groups (Zirconia-Tetric N-Ceram and Zirconia-MultiCore Flow). Biaxial flexural strength was determined using a piston-on-3-ball test. The data were statistically analyzed with an independent t-test for significant differences (p = 0.05).

RESULTS

Tetric N-Ceram had significantly higher strength than MultiCore Flow (p < 0.001) but no statistically significant differences were found in strength values between Zirconia-Tetric N-Ceram and Zirconia-MultiCore Flow bilayered samples (p = 0.27).

CONCLUSIONS

It was concluded that although the tested composite core materials significantly differ in their biaxial flexural strength values, they had no influence on the biaxial flexural strength of the overlying zirconia.

Assessment Methods for Marginal and Internal Fit of Partial Crown Restorations: A Systematic Review

BACKGROUND

Different methods are used for the analysis of marginal and internal fit of partial crowns, but not all of them are applicable for in vivo studies. The aim of this review is to search the available methods, described in the current literature, to assess marginal and internal fit in partial crowns.

METHODS

an electronic search was performed on Pubmed and Web of Science databases to find studies published from 1 January 2017 up to 2 March 2023, following PRISMA guidelines and Cochrane handbook for systematic reviews. The search strategy applied was: "(marginal) AND (fit OR gap OR adaptation OR discrepancy) AND (inlay OR onlay OR partial crown)". In vitro studies which evaluated marginal and internal fit on CAD CAM or 3D printed partial crowns were included in this review. Quality of the studies was assessed by using Quality Assessment Tool For In Vitro Studies (QUIN tool).

RESULTS

22 studies were included. Among conventional methods, direct view with microscope, indirect view on resin replicas, and silicone replica technique (SRT) were used. Considering new digital methods, micro-CT, SRT 3D and triple scan technique (TST) were applied.

CONCLUSIONS

Among 2D methods, direct view technique is the most used marginal fit analysis. For a more comprehensive evaluation, a 3D digital analysis is suggested. SRT and indirect view are the only 2D methods available for in vivo analysis. A protocol for the application of TST for assessment in vivo is now available, but no studies are reported in literature yet.

Biofabrication of engineered dento-alveolar tissue

Oral health is essential for a good overall health. Dento-alveolar conditions have a high prevalence, ranging from tooth decay periodontitis to alveolar bone resorption. However, oral tissues exhibit a limited regenerative capacity, and full recovery is challenging. Therefore, regenerative therapies for dento-alveolar tissue (e.g., alveolar bone, periodontal membrane, dentin-pulp complex) have gained much attention, and novel approaches have been proposed in recent decades. This review focuses on the cells, biomaterials and the biofabrication methods used to develop therapies for tooth root bioengineering. Examples of the techniques covered are the multitude of additive manufacturing techniques and bioprinting approaches used to create scaffolds or tissue constructs. Furthermore, biomaterials and stem cells utilized during biofabrication will also be described for different target tissues. As these new therapies gradually become a reality in the lab, the translation to the clinic is still minute, with a further need to overcome multiple challenges and broaden the clinical application of these alternatives.

Biomechanical properties of different endocrown designs on endodontically treated teeth

OBJECTIVE

To compare the biomechanical properties of different endocrown designs on endodontically treated teeth with an extensive defect in the mesial wall using a three-dimensional finite element method (3D FEM).

METHODS

Four finite element analysis models were designed and built up based on different endocrown configurations in a mandibular molar. One model was designed as a butt joint preparation with 2 mm occlusal thickness(control), the other three models were butt joint designs with different distances between the bottom of the mesial wall preparation and the cemento-enamel junction (CEJ): 2 mm, 1 mm and 0 mm respectively. A vertical load parallel with the longitudinal axis of the tooth and an oblique load with a 45°angle to the longitudinal axis were applied to the occlusal surfaces. The maximum Von Misses (VM) stresses and stress distribution patterns were calculated and compared. Weibull risk-of-rupture analysis was used to analyze the survival probability of the restorations and tooth in the different models.

RESULTS

For the restoration, the model with a mesial wall destruction at the level of CEJ showed much higher risk of failure than other models. Overall, none of the four models showed failure. Under oblique loading, VM stress in the cement layer of the models with a mesial wall defect was higher than in the control model. In the dentin, the highest VM stresses were found in the peri-cervical dentin. Under the oblique loading, the model with the mesial wall destruction at the level of CEJ restored by endocrown showed the highest risk of failure.

CONCLUSION

Under the oblique loading, with the increase of the simulated defect in the mesial wall, the peak VM stress values in the cement layer increased accordingly. In the model with a mesial wall defect up to the level of CEJ risk of failure was highest in the cervical dentin.

Clinical Outcomes of CAD/CAM (Lithium disilicate and Zirconia) Based and Conventional Full Crowns and Fixed Partial Dentures: A Systematic Review and Meta-Analysis

Although CAD/CAM (computer-aided design/computer-aided manufacturing) restorations act as a favorable alternative to conventional metal-ceramic restorations for fixed dental prostheses, little is known about their intermediate and persistent clinical performance. This systematic review and meta-analysis aimed to assess the clinical performance in terms of biological, technical, and esthetic aspects and the survival and success ratios for single full crowns (SFCs) and fixed partial dentures (FPDs) fabricated by CAD/CAM and conventional techniques and according to the materials used (zirconia {ZC} and lithium disilicate {LD}). The population, intervention, control, outcome, and study design (PICOS) strategy was used to electronically search key terms in the PubMed, Cochrane Library, Embase, and Wiley Online databases for randomized control trials (RCTs) and cohort studies. The bias risks for RCTs and cohort studies were assessed using the Cochrane collaboration tool and the Newcastle-Ottawa Scale (NOS). Meta-analysis was performed using Rev5 from Cochrane. A total of 13 studies reporting on 1598 restorations in 1161 patients with a mean observation period of 3.6 years (minimum-maximum: 1-9.3 years) met the inclusion criteria. Meta-analysis of the included studies indicated that CAD/CAM manufacturing resulted in 1.17, 1.14, and 16.88 (95% CI: 0.64-2.17, 0.86-1.52, 7.59-37.56) higher biological, technical, and esthetic complications than conventional manufacturing of restorations. However, the difference was significant for esthetic complications only (p<0.00001). A significant difference was observed for all biological, technical, and aesthetic aspects between SFCs and FPDs (odds ratio {OR} = 2.61 vs. 1.78, 95% CI: 1.92-3.56 vs. 1.33-2.38; p<0.00001). The survival ratio of SFCs was 2.69 (95% CI: 1.98-3.65), significantly higher compared to the 1.76 (95% CI: 1.31-2.36) of FPDs (p<0.00001). The success ratio of FPDs at 1.18 (95% CI: 0.83-1.69) was significantly lower compared to SFCs at 2.36 (95% CI: 1.68-3.33). The clinical performance of LD with 2.42 (CI: 1.16-5.03) was significantly higher compared to ZC with 2.22 (CI: 1.78-2.77) (p<0.00001). The biological, technical, and aesthetic behaviors showed similar clinical outcomes between the CAD/CAM and conventional groups. LD could be a good alternative to zirconia, but its intermediate or persistent clinical performance needs to be evaluated. Overall, zirconia and CAD/CAM techniques must evolve further to outclass the conventional techniques used in the fabrication of SFCs and FPDs.

Indirect restorative systems-A narrative review

OBJECTIVE

The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence-based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all-ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes.

OVERVIEW

Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin-matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth.

CONCLUSIONS

Based on several clinical research, materials, and patient-related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process.

CLINICAL SIGNIFICANCE

The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long-term clinical trials in order to incorporate or not new materials and technological advancements.

Gold versus ceramic - which will last longer for posterior indirect restorations?

Data sources Electronic search through PubMed (Medline), CENTRAL (Cochrane) and Embase databases in November 2021. Grey literature searches (OpenGrey, Pro-Quest, National research register and the register of clinical studies hosted by the US National Institute of Health).Study selection Randomised in vivo clinical trials (RCTs) with at least two-year follow-ups, that compared the longevity of adhesively luted indirect ceramic restorations against conventionally cemented indirect metal restorations. The teeth studies had to be about single tooth restorations, on premolars or molars, with sufficient information available for extraction; eg outcome assessment, reason for failure. No language or time restrictions were applied.Data extraction and synthesis Two authors performed study selection, data extraction and quality assessment independently and in duplicate. The following clinical data was extracted: number of participants and dental health status, location of the cavosurface margin, cavity type, reason for intervention, methods and materials for treatment, follow-up, lesion activity at moment of restoration placed, lesion extension (surfaces of restoration), lesion margin (enamel or dentine). It was decided if the restoration was renewed, repaired or re-cemented, then this was classed as outcome failure. Grading of evidence was performed according to the GRADE network.Results After duplicates were removed, 2,667 underwent title screening, 389 abstract screening, and 186 went on to have full text screening with 72 being excluded. In total, 110 eligible articles were then excluded from the 114 that were assessed leaving four RCTs meeting the eligibility criteria and being included in the synthesis, published between 2000 and 2013. Two studies were parallel-arm, the other two, split-mouth design. Overall, 443 restorations had been placed, 212 were adhesively luted ceramic, and 213 conventionally cemented metal restorations; these were all gold. The follow-up periods ranged from 5-7 years. Two studies compared inlays only, one looked at partial crowns only, and the fourth full crowns. The lowest failure rates were found for metal restorations, ranging from 0-11%. The failure rates for ceramic inlays and partial crowns were 5-9% over the same observation period. The failure rates for ceramic full crowns were 36% after five years. The most common failure for ceramic was found to be fracture of the restoration, whereas caries was the most frequent cause of failure for the gold restorations.Conclusions The risk of bias was high for all four studies and the grading of evidence showed a low level of evidence. Only one meta-analysis could be performed comparing conventionally cemented metal vs adhesively luted ceramic restorations, showing the relative risk to fail for conventionally cemented metal indirect restorations is significantly lower than adhesively luted ceramic indirect restorations.

Post-Fatigue Fracture Resistance of Lithium Disilicate and Polymer-Infiltrated Ceramic Network Indirect Restorations over Endodontically-Treated Molars with Different Preparation Designs: An In-Vitro Study

The aim of the present study was to evaluate the fatigue to cyclic and static resistance of indirect restorations with different preparation designs made either of lithium disilicate (LS) or polymer-infiltrated ceramic network (PICN). Eighty-four (n = 84) molars were chosen, endodontically treated, and prepared with standardized MOD cavities. The molars were randomly divided into 6 study groups (n = 14) taking into account the "preparation design'' (occlusal veneer with 1.2 mm occlusal thickness; overlay with 1.6 mm occlusal thickness; adhesive crown with 2 mm occlusal thickness) and the "CAD/CAM material'' (E-max CAD, Ivoclar vivadent; Vita Enamic, Vita). A fatigue test was conducted with a chewing simulator set at 50 N for 1,500,000 cycles. Fracture resistance was assessed using a universal testing machine with a 6 mm diameter steel sphere applied to the specimens at a constant speed of 1 mm/min. A SEM analysis before the fracture test was performed to visually analyze the tooth-restoration margins. A statistical analysis was performed with a two-way ANOVA and a post-hoc pairwise comparison was performed using the Tukey test. The two-way ANOVA test showed that both the preparation design factor (p = 0.0429) and the CAD/CAM material factor (p = 0.0002) had a significant influence on the fracture resistance of the adhesive indirect restorations. The interaction between the two variables did not show any significance (p = 0.8218). The occlusal veneer had a lower fracture resistance than the adhesive crown (p = 0.042) but not lower than the overlay preparation (p = 0.095). LS was more resistant than PICN (p = 0.002). In conclusion, in the case of endodontically treated teeth, overlay preparation seems to be a valid alternative to the traditional full crown preparation, while occlusal veneers should be avoided in restoring non-vital molars with a high loss of residual tooth structure. LS material is more resistant compared to PICN.

Onlays/partial crowns versus full crowns in restoring posterior teeth: a systematic review and meta-analysis

BACKGROUND

Tooth-colored onlays and partial crowns for posterior teeth have been used increasingly in clinics. However, whether onlays/partial crowns could perform as well as full crowns in the posterior region was still not evaluated thoroughly.

METHODS

A literature search was conducted without language restrictions in Pubmed, Embase, Cochrane Central Register of Controlled Trial and Web of science until September 2021. RCTs, prospective and retrospective observational studies with a mean follow-up of 1 year were selected. Cochrane Collaboration's tool was adopted for quality assessment of the RCT. The quality of observational studies was evaluated following Newcastle-Ottawa scale. The random-effects and fixed-effects model were employed for meta-analysis.

RESULTS

Four thousand two hundred fifty-seven articles were initially searched. Finally, one RCT was identified for quality assessment and five observational studies for qualitative synthesis and meta-analysis. The RCT was of unclear risk of bias while five observational studies were evaluated as low risk. The meta-analysis indicated no statistically significant difference in the survival between onlays/partial crowns and full crowns after 1 year (OR = 0.55, 95% CI: 0.02-18.08; I² = 57.0%; P = 0.127) and 3 years (OR = 0.65, 95% CI: 0.20-2.17; I² = 0.0%; P = 0.747). For the success, onlays/partial crowns performed as well as crowns (OR = 0.58, 95% CI: 0.20-1.72; I² = 0.0%; P = 0.881) at 3 years. No significant difference of crown fracture existed between the two methods (RD = 0.00, 95% CI: - 0.03-0.03; I² = 0.0%; P = 0.972).

CONCLUSIONS

Tooth-colored onlays/partial crowns performed as excellently as full crowns in posterior region in a short-term period. The conclusions should be further consolidated by RCTs with long-term follow-up.

Effect of preparation design on marginal adaptation and fracture strength of ceramic occlusal veneers: A systematic review

OBJECTIVES

This systematic review aims to investigate the effect of different preparation designs on the marginal fit and fracture strength of ceramic occlusal veneers.

MATERIALS AND METHODS

Based on the PICO question and the search terms, an electronic search was performed in Google Scholar, PubMed (MEDLINE), Scopus, Cochrane Library, Web of Science, Science Direct, Wiley, Ovid, and SAGE for articles published up to July 2022. After including English in vitro studies that evaluated posterior ceramic occlusal overlays at the posterior with ceramic restorations by following the PRISMA statement, the extracted data was tabulated. The methodological quality of the included studies was evaluated. Risk of bias assessment was done independently by two authors using the modified MINORS scale.

RESULTS

About 3138 search results were screened, of which 22 were selected due to their titles. Twenty-one full-text articles were assessed for eligibility. Seventeen in-vitro studies were finalized for the extraction of quantitative data. All 17 articles had a low risk of bias and were retained. The influencing items for evaluating the research were different in most studies; therefore, qualitative synthesis of the results was feasible. They generally included preparation design, material thickness, depth of preparation in the tooth, internal divergence angle, and finish line. Meta-analysis was not done due to heterogeneity of preparation types and evaluation methods. Results revealed that fracture resistance of occlusal veneers is higher than normal mastication force, and it is sufficient to prepare the occlusal surface, use a self-etching primer for bonding, and an acceptable minimum ceramic thickness. The marginal discrepancy of occlusal veneers is clinically acceptable. However, this systematic review faces some limitations due to the lack of in vivo studies, different preparation designs in included studies, different follow-ups, and lack of comprehensive explanations in articles.

CONCLUSIONS

The preparation design of occlusal veneers influences both marginal adaptation and fracture resistance. Various preparation designs are proven to have clinically acceptable fracture strength and marginal adaptation.

Effect of Different Indirect Composite Onlay and Core Materials on Fracture Resistance of Endodontically Treated Maxillary Premolars

PURPOSE

To compare and evaluate the effects of different indirect composite onlay and/or core buildup materials on the fracture resistance and fracture mode of restored endodontically treated premolars.

METHODS

Two conventional handmade indirect composite resins (SR Nexco (NC) and Ceramage (CM)) and two core buildup materials, dual-cure composite resin (MultiCore Flow (MC)), and short fiber-reinforced composite resin (EverX Posterior (EXP)), were selected. Sixty maxillary premolars were randomly divided into six groups (n=10). Group 1 included intact teeth (INT; negative control). Mesio-occluso-distal cavity preparation and endodontic treatment was performed on the remaining premolars. Group 2 was restored with polymer-reinforced zinc oxide eugenol intermediate restorative material (IRM; positive control), whereas the experimental groups (groups 3-6) were restored with core buildup material and indirect composite onlay (MC_NC, MC_CM, EXP_NC, and EXP_CM). The specimens received compressive loading using a universal testing machine, at 45° to the long axis with a crosshead speed of 0.5 mm/min until fracture. Fracture modes were visually analyzed. Fracture resistance was measured and statistically analyzed using two-way and one-way ANOVA (α=0.05).

RESULTS

Only the type of indirect composite onlay affected the fracture resistance of the experimental groups (P=0.009). The MC_CM group showed the highest fracture resistance, which was significantly higher than that of the MC_NC group (P=0.031). No statistically significant differences were found between the INT group and other experimental groups(P>0.05). All groups had a greater incidence of restorable than unrestorable failures.

CONCLUSION

The type of indirect composite onlay affected the fracture resistance of restored endodontically treated maxillary premolars.

The influence of indirect bonded restorations on clinical prognosis of endodontically treated teeth: A systematic review and meta-analysis

OBJECTIVE

The loss of the dental coronal portion following carious lesions or fractures leads to endodontic treatment with subsequent restoration to ensure correct anatomy and function. Recently, partial adhesive restorations have been widely proposed to increase the survival rate of endodontically treated teeth. The primary purpose of this review is to assess the failure rate of indirect partial adhesive restorations on endodontically treated teeth (ETT), considering the follow-up period.

METHODS

The indications reported in the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) were used to draft the present review. The study was constructed on PICO questions: population (patients who need indirect adhesive restorative treatment on endodontically treated teeth with onlay and overlay), intervention (onlay and overlay), control (patients with onlay and overlay on endodontically treated teeth) and outcome (failure rate and types of failure for onlay and overlay). The asked scientific question was: what are the failure rate and types of failure for adhesive indirect partial restorations on ETT?

RESULTS

The overall failure rate that emerges is 0.087 with a ratio of 121/1254, I² 80 % p-value< 0.001. Moreover, by meta-regression with covariates the follow-up period reports a coefficient of 0.013 with a P-value< 0.001. In conclusion, the indirect partial restorations on endodontically treated teeth displayed overall acceptable outcomes in terms of success from 2 to 4 years after their placement with only 4.32 % of failure. Failures increase after 7 years up to 12-30 years with failure rates of approximatively 10.65 % and 20.94 %. The analysis of the included articles reporting the causes of restorations failures showed that 15.51 % of cases were related to the loss of dental element.

SIGNIFICANCE

Besides the survival rates of indirect adhesive restorations on endodontically treated posterior teeth, it was highlighted that the majority of failures appeared restorable. Thus, partial restorations seemed able to prevent the ETT tooth loss.

Does immediate dentin sealing influence postoperative sensitivity in teeth restored with indirect restorations? A systematic review and meta-analysis

Objective

This study comprehensively reviewed clinical trials that investigated the effect of immediate dentin sealing (IDS) technique on postoperative sensitivity (POS) and clinical performance of indirect restorations.

Materials and methods

The systematic review was conducted according to the preferred reporting items for systematic reviews and meta‐analyses statement, and was guided by the PICOS strategy. Clinical trials in which adult patients received at least one indirect restoration cemented with IDS approach and one restoration cemented following the delayed dentin sealing (DDS) were considered.

Results

Following title screening and full‐text reading, four studies met the inclusion criteria and were included for qualitative synthesis, while two studies were selected for quantitative synthesis. According to Risk of bias‐2 tool, two studies were classified as “some concerns” for the outcome POS. No statistically significant differences were found between teeth restored with indirect restorations using the IDS and DDS approach for POS (p > 0.05), neither at the baseline (very low certainty of evidence according to GRADE) nor after 2 years of follow‐up (low certainty of evidence according to GRADE).

Conclusion

There is low‐certainty evidence that IDS does not reduce POS in teeth restored with indirect restorations.

Clinical significance

There is no clinical evidence to favor IDS over DDS when restoring teeth with indirect restorations.

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.

Effect of Root Canal Therapy Combined with Full Crown Restoration on the Level of Inflammatory Factors and Chewing Function in Patients with Cracked Teeth and Chronic Pulpitis

Objective

To explore the clinical effect of root canal therapy combined with full crown restoration in patients with cracked teeth and chronic pulpitis.

Methods

From May 2018 to June 2020, 87 patients with cracked teeth and chronic pulpitis in our hospital were selected; the patients were randomly divided into the control group and the research group by random number method. The control group only used root canal therapy; the research group used root canal therapy combined with full crown restoration. The therapeutic effect, levels of inflammatory factors, chewing function, periodontal index, complications, and quality of life were compared between the two groups.

Results

The total effective rate of the research group (97.78%) was better than the total effective rate of the control group (85.71%) (P < 0.05). Compared with before treatment, the serum levels of interleukin-1β (IL-1β), IL-6, and C-reactive protein (CRP) of the two groups of patients decreased after treatment. After treatment, compared with the control group, the serum levels of IL-1β, IL-6, and CRP in the research group decreased (P < 0.05). Compared with before treatment, the bite force of teeth and chewing efficiency of the two groups of patients increased after treatment. After treatment, compared with the control group, the bite force of teeth and chewing efficiency of the research group increased (P < 0.05). Compared with before treatment, the plaque index (PLI), probing depth (PD), gingival sulcus bleeding index (BI), and gingival index (GI) of the two groups of patients decreased after treatment. After treatment, compared with the control group, the PLI, PD, BI, and GI of the research group decreased (P < 0.05). The total incidence of complications in the research group was (11.11%), and the total incidence of complications in the control group was (16.67%); there was no significant difference between the two groups (P > 0.05). After treatment, compared with the control group, the quality of life scores of the patients in the research group were reduced (P < 0.05).

Conclusion

Root canal therapy and full crown restoration have a definite curative effect in patients with cracked teeth and chronic pulpitis, which can improve the inflammatory response, restore chewing function, maintain periodontal health, improve the quality of life, and do not increase the incidence of complications, so it has good application value.

Longevity of Polymer-Infiltrated Ceramic Network and Zirconia-Reinforced Lithium Silicate Restorations: A Systematic Review and Meta-Analysis

The purpose of this study was to systematically review the existing literature to assess the clinical survival and success of PICN and ZLS indirect restorations as the clinical evidence for them remains lacking. PubMed, SCOPUS, Embase, Cochrane Library, Web of Science, LILACs, and SciElo databases were searched from 1 January 2000 to 1 February 2021. Clinical trials and cohort studies published in English were included while case studies, case series, and in vitro studies were excluded. Results were analyzed qualitatively and a meta-analysis using a random effects model was performed. A strength of recommendation taxonomy (SORT) analysis was conducted and risk of bias (RoB) was assessed using the Newcastle-Ottawa scale and Cochrane RoB tools. An electronic search through the databases yielded 2454 articles, of which 825 remained after duplicate removal. Five studies investigating PICN and four investigating ZLS indirect restorations remained after assessing for eligibility. The overall survival rate of PICN over 1 year was 99.6% and 99.2% over 2 years. The overall survival rate of ZLS over 1 year was 99%. The main mode of failure for both materials was catastrophic fracture. One study had a high RoB, four had a moderate RoB, and four had a low RoB. Both materials demonstrated moderate strength of recommendation at a level 2 evidence for all studies based on SORT analysis. PICN and ZLS show promising short-term clinical performance as full and partial coverage indirect restorations, but longer follow-up studies are required to confirm their long-term performance.

Survival Rate of CAD-CAM Endocrowns Performed by Undergraduate Students

OBJECTIVES

This study aimed to evaluate the success of computer-aided design-computer-aided manufacturing (CAD-CAM) endocrown restorations of endodontically treated teeth (ETT) performed by supervised undergraduate students. The study also intended to identify possible factors that may lead to failures.

METHODS AND MATERIALS

This observational open cohort study was based on clinical data from endocrown restorations performed by residents and undergraduate students in their 4th, 5th, and 6th year from July 2011 to May 2018. The presence of a tooth with an endocrown on the arch was the main criteria used to calculate the survival rate of restored teeth. The quality of the remaining endocrowns was evaluated referring to the FDI criteria. The cases of failure were categorized into either favorable or unfavorable.

RESULTS

A total of 343 ETT were restored with endocrowns in 315 patients. Among them, 199 patients encompassing 225 endocrowns were followed during a 56 ± 26 month period. The survival rate of restored teeth was found to be 81.8%, the estimated Kaplan-Meier survival rate being 71.8% at 9 years. Among the 41 failed cases, 32 were favorable (debonding and/or ceramic fractures) and 9 were unfavorable.

CONCLUSION

Endocrown restorations of posterior ETT using CAD-CAM technologies could be carried out by undergraduates with a low risk of failure. Teacher supervision could be reinforced, covering all steps of each endocrown procedure in order to avoid failures due to insufficient thickness or loss of retention.

Fatigue behavior of endodontically treated maxillary premolars with MOD defects under different minimally invasive restorations

OBJECTIVES

To analyze the stress distribution and subsequent fracture resistance of human maxillary premolars with mesial-occlusal-distal (MOD) defects restored with different minimally invasive restorations.

MATERIALS AND METHODS

Seventy non-carious human maxillary premolars were selected and divided into seven groups (n = 10). Ten teeth without further preparation served as control. The remaining teeth were endodontically treated and received three restorative patterns: inlays without cusp coverage (I), onlays with palatal coverage (O), overlays with both buccal and palatal coverage (Ov). Lithium disilicate glass ceramics (EM) and machinable composite resin (LU) were used for restoration. Specimens were tested under cycling loading with tongue direction of 45° for 1.2 × 10⁶ cycles at a 50-N load and 2.0-Hz frequency. The survival time and two fracture mode classifications were assessed. Three-dimensional models of each group were designed. The magnitude and pattern of stresses were analyzed under the same condition of the in vitro test using finite element stress analysis.

RESULTS

Although the overlay model pattern produced more favorable stress distribution, three restorative patterns restored with the same material had no difference in survival curves (P > 0.05). Only the survival curve of the EM-Ov group had no statistical difference with that of the control group (P > 0.05). EM groups presented mainly interface adhesive failure, while LU groups were mainly material cohesive failure.

CONCLUSION

For the endodontically treated maxillary premolars with MOD defect, the lithium disilicate glass ceramic overlay pattern can reach the best restorative effect.

CLINICAL RELEVANCE

Comparing with restorative pattern, restorative material had a greater influence on the minimally invasive restoration of posterior teeth.

Influence of Cavity Geometry on the Fracture Strength of Dental Restorations: Finite Element Study

The main purpose of this work was to analyze the stress distribution in premolars restored with indirect IPS Empress® CAD onlays or inlays. The three-dimensional geometry of a human first premolar was created using modeling software. The tooth fixation system was simulated through box geometry, comprising a cortical bone layer with 2 mm of thickness over a layer of trabecular bone with 15 mm of thickness. The tooth had the following approximated crown dimensions: 10.35 mm buccolingual length; 7.1 mm mesiodistal width; and 7.0 mm cervico-occlusal height. The mesio-occluso-distal (MOD) cavity preparations followed the suggestions available in the literature. The cement geometry was modified to include cohesive zone models (CZM) to perform the adhesive joint’s strength prediction. The loading body was created assuming contact between the food bolus and the tooth surface. Numerical solutions were obtained by performing static analysis and damage analysis using the finite element method. Von Mises stress values generated in the ceramic inlay restoration ranged from 1.39–181.47 MPa, which were on average 4.4% higher than those of the onlay ceramic restoration. The fracture strength of the onlay restoration was about 18% higher than that of the inlay restoration. The onlay design seems to contribute to higher homogenization of the adhesive resin cement strain and higher tooth structure protection.

Long-term Clinical Performance of Composite Resin or Ceramic Inlays, Onlays, and Overlays: A Systematic Review and Meta-analysis

CLINICAL RELEVANCE

Composite resin or ceramic inlays, onlays, and overlays can achieve high long-term survival and success rates.

SUMMARY

Core build-up resin composites: an in-vitro comparative study

Aim

Resin composite (RC) are commonly used under full crowns. However, independent information is lacking to guide practitioners regarding core RC material selection. This study aimed at comparing the flexural properties of a large selection of commercially-available core build-up RCs (CBU-RC), either light-, self- or dual-cure, to conventional light-cure RCs.

Methods

RCs were injected into a 25 × 2×2mm Teflon mold, and either light-cured during 20 s (materials with claimed light-cure characteristics) or covered by aluminum during 10 min (dual- and self-cure CBU-RCs). They were subjected after a one-week water storage at 37.5 °C to three-point bending, and Flexural modulus (E _flex) and Flexural Strength (σ _f) were calculated (n = 20). Thermogravimetric analysis (n = 3) was performed to determine inorganic filler content (%).

Results

For dual-cure CBU-RCs, both RC (p < .0001) and light-curing (p = .0007) had a significant influence on E _flex, while only RC was significant for σ _f (p < .0001). Between all conventional RCs and CBU-RCs, significant differences were observed (p < .0001), both regarding E _flex and σ _f, with values ranging from 3.9 to 15.5 GPa and from 76 to 130.3 MPa, respectively. Higher E _flex values were observed for light-cure RCs than for self- and dual-cure ones, while no clear trend was noticed regarding σ _f. Good linear correlation was found between inorganic filler content and E _flex (R ²=0.85, p < .0001), but not with σ _f (R ²=0.08, p = .1609).

Conclusion

This work demonstrated a positive influence of light-curing on dual-cure CBU-RC's E _flex. It also highlighted large differences in flexural properties (especially E _flex) among the investigated materials, questioning the use of some CBU-RCs as dentin replacement in case of large tissue loss.

Clinical Behavior of Ceramic, Hybrid and Composite Onlays. A Systematic Review and Meta-Analysis

A systematic review and meta-analysis was performed to analyze the survival of onlay restorations in the posterior region, their clinical behavior according to the material used (ceramic reinforced with lithium disilicate, conventional feldspathic ceramic or reinforced with leucite; hybrid materials and composite), possible complications, and the factors influencing restoration success. The systematic review was based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement, without publication date or language restrictions. An electronic search was made in the PubMed, Scopus, Embase, and Cochrane databases. After discarding duplicate publications and studies that failed to meet the inclusion criteria, the articles were selected based on the population, intervention, comparison, outcome (PICO) question. The following variables were considered in the qualitative and quantitative analyses: restoration survival rate (determined by several clinical parameters), the influence of the material used upon the clinical behavior of the restorations, and the complications recorded over follow-up. A total of 29 articles were selected for the qualitative analysis and 27 for the quantitative analysis. The estimated restoration survival rate was 94.2%. The predictors of survival were the duration of follow-up (beta = −0.001; p = 0.001) and the onlay material used (beta = −0.064; p = 0.028). Composite onlays were associated with a lower survival rate over time. Onlays are a good, conservative, and predictable option for restoring dental defects in the posterior region, with a survival rate of over 90%. The survival rate decreases over time and with the use of composite as onlay material.

Comparison of 16.9-year survival of pressed acid etched e.max lithium disilicate glass-ceramic complete and partial coverage restorations in posterior teeth: Performance and outcomes as a function of tooth position, age, sex, and thickness of ceramic material

STATEMENT OF PROBLEM

Long-term clinical data are lacking on the comparison of the survival of adhesively luted pressed e.max lithium disilicate glass-ceramic complete and partial coverage restorations in posterior dentitions and the effect that different technical and clinical variables have on their survival.

PURPOSE

The purpose of this clinical study was to examine and compare the 16.9-year survival of posterior pressed e.max lithium disilicate glass-ceramic complete and partial coverage restorations and associated clinical parameters on the outcome.

MATERIAL AND METHODS

Patients requiring either single-unit posterior defect-specific partial coverage or complete coverage restorations were recruited in a clinical private practice. The participants were offered the options of direct restorations, partial coverage cast gold, or glass-ceramic (lithium disilicate) restorations. Those requiring complete coverage restorations were given the options of complete cast gold, metal-ceramic, or glass-ceramic restorations. Only participants who chose glass-ceramic partial and complete coverage restorations were included in the study. The overall survival of the glass-ceramic restorations was assessed by the clinical factors determined at recall. The effect of various clinical parameters (type of restoration, dental arch, tooth position in the dental arch, age and sex of participant, and ceramic thickness) was evaluated by using Kaplan-Meier survival curves to account for attrition bias and other reasons for failure. The statistical significance of differences between parameters was determined using the log rank test (α=.05).

RESULTS

A total of 738 participants requiring 2392 lithium disilicate restorations in posterior teeth were evaluated. The mean age of the participants at the time of restoration placement was 62 (range: 20-99 years, 302 men and 436 women). Of 2392 units, 1782 were complete and 610 were partial coverage restorations. A total of 22 failures (bulk fracture or large chip) requiring replacement were recorded with the average time to failure 3.5 (0.02-7.9) years. The total time at risk computed for these units was 13227.9 years, providing an estimated failure risk of 0.17% per year. The 16.9-year estimated cumulative survival was 96.49%. The estimated cumulative survival of posterior complete (n=1782) and posterior partial coverage restorations (n=610) was 96.75% at 10.5 years and 95.27% at 16.9 years (P<.05). Of the 22, 16 failures were recorded for the complete coverage restorations. The total time at risk for these restorations was 10144.5 years, providing an estimated risk of 0.16 per year. The other 6 failures recorded occurred for the partial coverage restorations. The total time at risk for these restorations was 3083.5 years, providing an estimated risk of 0.19% per year. No statistically significant difference was found in the survival of posterior complete and partial coverage restorations among men and women, different age groups, or posterior tooth position in the dental arch (P>.05). The thickness of the restoration also had no influence on the survival of glass-ceramic posterior restorations (P>.05).

CONCLUSIONS

Pressed e.max lithium disilicate complete and partial coverage restorations showed high survival rates in posterior teeth over a 16.9-year period, with an overall failure rate of 0.17% per year. Risk of failure at any age was low for both men and women. No statistically significant difference was found in the survival of complete and partial coverage restorations, and none of the confounding variables, including the thickness of the restoration, appeared to have a significant effect on survival.

Clinical Performance of Partial and Full-Coverage Fixed Dental Restorations Fabricated from Hybrid Polymer and Ceramic CAD/CAM Materials: A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the clinical performance of tooth-borne partial and full-coverage fixed dental prosthesis fabricated using hybrid polymer and ceramic CAD/CAM materials regarding their biologic, technical and esthetical outcomes. PICOS search strategy was applied using MEDLINE and were searched for RCTs and case control studies by two reviewers using MeSH Terms. Bias risk was evaluated using the Cochrane collaboration tool and Newcastle–Ottawa assessment scale. A meta-analysis was conducted to calculate the mean long-term survival difference of both materials at two different periods (≤24, ≥36 months(m)). Mean differences in biologic, technical and esthetical complications of partial vs. full crown reconstructions were analyzed using software package R (p < 0.05). 28 studies included in the systematic review and 25 studies in the meta-analysis. The overall survival rate was 99% (0.95–1.00, ≤24 m) and dropped to 95% (0.87–0.98, ≥36 m), while the overall success ratio was 88% (0.54–0.98; ≤24 m) vs. 77% (0.62–0.88; ≥36 m). No significance, neither for the follow-up time points, nor for biologic, technical and esthetical (88% vs. 77%; 90% vs. 74%; 96% vs. 95%) outcomes was overserved. A significance was found for the technical/clinical performance between full 93% (0.88–0.96) and partial 64% (0.34–0.86) crowns. The biologic success rate of partial crowns with 69% (0.42–0.87) was lower, but not significant compared to 91% (0.79–0.97) of full crowns. The esthetical success rate of partial crowns with 90% (0.65–0.98) was lower, but not significant compared to 99% (0.92–1.00) of full crowns.

A comparison of mvM stress of inlays, onlays and endocrowns made from various materials and their bonding with molars in a computer simulation of mastication - FEA

OBJECTIVES

The purpose of the study was to compare the mvM stresses occurring in inlays, onlays and endocrowns made from different materials and their bonding with molars in a computer simulation of mastication.

METHODS

The study was conducted using the finite elements method with contact elements. Sixteen 3D first molar models were created of a intact tooth - T; a tooth with a ceramic inlay - IN; a tooth with an onlay - ON; and a tooth with an endocrown - EN. The restorations were made of: Comp - resin nanoceramic; Hc - hybrid ceramic; Le - leucite ceramic; Dlit - lithium disilicate; and Zr - zirconia. Computer simulations of mastication were performed. The equivalent stresses according to the modified von Mises criterion (mvM) were calculated in model materials and contact stresses at the interface cement-dental tissue around the examined restorations.

RESULTS

The highest equivalent mvM stresses were concentrated in buccal margins of inlays. The mvM stresses recorded in onlays were 1.6-5 times lower than those found in inlays, while in endocrowns they were 2.3-6.5 times lower. Around the onlays and endocrowns, in tooth structures and luting cement, mvM stresses were significantly lower compared to teeth restored with inlays. The tensile and shear contact stresses between inlays and teeth were several times lower than under another restorations. The highest stresses (58.5MPa) occurred in the zirconia inlay. The stresses observed in the enamel of a tooth restored with an INZr inlay were half those noted in INComp, and a third of those observed in cement. Tensile contact stresses at the interface between the INZr inlay and dental tissue were 4.5 times lower than in the INComp, and the shear stresses were more than 7 times lower.

SIGNIFICANCE

The highest values and unfavorable of stress levels occurred in teeth restored with inlays. Cavities MOD in molars should be reconstructed with cusp-covering restorations. The endocrown in molars should withstand physiological loading. The higher the modulus of elasticity of the restoration material, the higher the stresses in the restorations, while the lower stresses were observed in the tooth structures, luting cement and at the interface between the restoration and the dental tissue. Ceramic restorations should provide better protection and marginal seal of the reconstructed tooth than composite ones.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

This comprehensive review of the 2018 dental literature is provided to inform busy dentists about progress in the profession. Developed by the Committee on Scientific Investigation of the American Academy of Restorative Dentistry, each author brings discipline-specific expertise to one of the 8 sections of the report including (1) prosthodontics; (2) periodontics, alveolar bone, and peri-implant tissues; (3) implant dentistry; (4) dental materials and therapeutics; (5) occlusion and temporomandibular disorders; (6) sleep-related breathing disorders; (7) oral medicine and oral and maxillofacial surgery; and (8) dental caries and cariology. The report targets important information that will likely influence day-to-day treatment decisions. Each review is not intended to stand alone but to update interested readers so that they may visit source materials if greater detail is desired. As the profession continues its march toward evidence-based clinical decision-making, an already voluminous library of potentially valuable dental literature continues to grow. It is the intention of this review and its authors to provide assistance in navigating the extensive dental literature published in 2018. It is our hope that readers find this work useful in the clinical management of patients moving forward.