CAD/CAM or conventional ceramic materials restorations longevity: a systematic review and meta-analysis

Survival of Partial Coverage Restorations on Posterior Teeth-A Scoping Review

OBJECTIVE

To investigate the nature and availability of evidence on the clinical performance of posterior partial coverage restorations (PCR) fabricated from different ceramic materials, outcome definitions, measurement methods, study drop-outs and follow ups.

OVERVIEW

A systematic literature search (inception-February 2024) was performed through MEDLINE, Scopus, CENTRAL, ClinicalTrials.gov, and the International Clinical Trials Registry Platform to identify clinical studies with a focus on posterior PCRs (onlays, occlusal veneers and partial crowns) with a minimum follow-up of 1 year. Thirteen of 31 included studies were randomized controlled trials (RCT) and 18 non-randomized studies of intervention (NRS). Six RCTs compared two different ceramic materials and might be suitable for meta-analysis. Differences in study design, definition of survival, evaluation methods, and statistical models for survival analysis were identified as reasons for expected heterogeneity among studies. The most common reasons for restoration failures were ceramic fractures and retention loss.

CONCLUSION

The evidence informing the effect of PCRs varied in definitions of survival and failure, complication classifications, and workflow approaches. RCTs addressing clinical performance of PCRs comparing different ceramic materials are available for conducting systematic reviews and meta-analyses.

Survival and Complications of Partial Coverage Restorations on Posterior Teeth-A Systematic Review and Meta-Analysis

OBJECTIVE

To determine the clinical performance of partial coverage restorations (PCR) (onlays, occlusal veneers, and partial crowns) composed of different ceramic and ceramic-based materials to treat extended posterior defects.

MATERIALS AND METHODS

MEDLINE, Scopus, CENTRAL, ClinicalTrials.gov, and the International Clinical Trials Registry Platform were searched (inception-February 2024) for randomized controlled trials (RCT) comparing posterior PCRs composed of different ceramic and ceramic-based materials with a minimum follow-up of 1 year.

RESULTS

Six RCTs were included. Resin matrix ceramic (RMC) and lithium disilicate (LDS) restorations had a 3-year survival rate of 89.3% (95% CI 76.4-95.3) and 93.7% (95% CI 83.7-97.7), respectively, and leucite-reinforced glass ceramic (LRGC) restorations a range between 96.1% (95% CI 90.1-98.9) compared with RMC and 98.3% (95% CI 90.8-100) compared with LDS. After 1-3 years of follow-up, LDS slightly outperformed RMC on restoration failure and loss of retention (1.56 more failures and 1.78 more loss of retentions for RMC per 100 restoration-years [low certainty evidence]). No statistically significant differences between ceramic and ceramic-based materials were detected in short-term follow-up (1-3 years of follow-up). The long-term performance of posterior PCRs is uncertain.

CONCLUSION

The survival of LDS restorations may slightly outperform RMC restorations after 3 years of follow-up across outcomes, except for bulk fracture. RCTs providing medium to long-term data are needed.

CLINICAL SIGNIFICANCE

Ceramic and ceramic-based PCRs are a reliable treatment option to restore extended posterior defects.

How to Conduct and Publish Systematic Reviews and Meta-Analyses in Dentistry

OBJECTIVE

To provide a guide for conducting systematic reviews and meta-analyses in dentistry, with emphasis on translating research findings into clinical practice.

OVERVIEW

Systematic reviews are essential tools for synthesizing research findings and translating evidence into clinical practice. These reviews help to identify the most effective treatment options and to determine areas requiring further research. A structured approach, including defining a concise research question, conducting comprehensive literature searches, and assessing the risk of bias, is critical for ensuring the review's trustworthiness. The GRADE approach facilitates the assessment of the certainty of evidence, which is crucial for formulating conclusions and making informed clinical decisions.

CONCLUSION

Systematic reviews provide invaluable insights into clinical decision-making by compiling, analyzing, and synthesizing multiple primary studies. Following a rigorous methodology ensures that systematic reviews are comprehensive, unbiased, and clinically relevant, ultimately contributing to better patient care and achieving better clinical outcomes.

CLINICAL SIGNIFICANCE

Methodologically sound systematic reviews and meta-analyses provide clinicians with high-quality, synthesized evidence, enabling informed clinical decisions and improved patient outcomes. They save time by consolidating research, informing treatment choices, and facilitating the translation of knowledge into clinical practice.

Buonocore Memorial Lecture 2023: Longevity of Dental Restorations or Longevity of Teeth: What Matters?

This paper aims to raise a discussion from the perspective of maintaining long-term oral health, posing a critical question: What holds greater significance for maintaining oral health, the longevity of restorations or teeth? This question explores the aspects that truly matter in ensuring sustained oral health throughout an individual's life. Restoration longevity is well-researched, and evidence shows several risk factors influencing longevity. The dentist's decision-making factor may be of utmost importance, and further studies are needed to investigate its relevance. The critical risk factors for restoration longevity are active pathology (high caries risk), less prominent parafunction, and extensive defects such as endodontic treatment. However, tooth longevity and the main risk factors for tooth loss are not well-researched. The evidence shows dental caries, and its sequelae, are the principal reasons for tooth loss. Patient-related risk factors, especially those associated with lifestyle and health choices, play a major role in the longevity of restorations and, more importantly, tooth longevity. To provide personalized dental care with maximum patient benefit, clinicians should identify and record potential risk factors, promoting a healthy lifestyle to ensure tooth and dentition longevity. Moreover, the evidence suggests that decision-making frameworks based on minimal intervention principles offer the best standard for clinical practice, promoting a longstanding healthy oral environment.

Interdisciplinary Delphi study by PROSEC North America: Recommendations on single indirect restorations made from ceramic and nonmetallic biomaterials for posterior teeth

OBJECTIVE

This article puts forward consensus recommendations from PROSEC North America regarding single indirect restorations made from ceramic and nonmetallic biomaterials in posterior teeth.

OVERVIEW

The consensus process involved a multidisciplinary panel and three consensus workshops. A systematic literature review was conducted across five databases to gather evidence. The recommendations, informed by findings from systematic reviews and formulated based on a two-phase e-Delphi survey, emphasize a comprehensive treatment strategy that includes noninvasive measures alongside restorative interventions for managing dental caries and tooth wear. The recommendations advocate for selecting between direct and indirect restorations on a case-by-case basis, favoring inlays and onlays over crowns to align with minimally invasive dentistry principles. The recommendations highlight the critical role of selecting restorative biomaterials based on clinical performance, esthetic properties, and adherence to manufacturer guidelines. They emphasize the importance of precision in restorative procedures, including tooth preparation, impression taking, contamination control, and luting. Regular follow-up and maintenance tailored to individual patient needs are crucial for the longevity of ceramic and nonmetallic restorations.

CONCLUSIONS

These PROSEC recommendations provide a framework for dental practitioners to deliver high-quality restorative care, advocating for personalized treatment planning and minimally invasive approaches to optimize oral health outcomes.

CLINICAL SIGNIFICANCE

The PROSEC North America recommendations highlight the importance of minimally invasive techniques in posterior tooth restorations using ceramic and non-metallic biomaterials. These principles prioritize tooth structure conservation and personalized treatment planning, essential for enhancing clinical outcomes and long-term oral health.

Shade match comparison of CAD-CAM single crowns to a lithium disilicate crown

PURPOSE

To assess the shade match ability of four varieties of all-ceramic crowns to a neighboring bilayered lithium disilicate crown.

MATERIAL AND METHODS

A dentiform was used to fabricate a bilayered lithium disilicate crown on the maxillary right central incisor, following the anatomy and shade of a selected natural tooth. Two crowns (one full-contour, one cutback) were then designed on a prepared maxillary left central incisor, following the contour of the neighboring crown. The designed crowns were used to manufacture monolithic lithium disilicate, bilayered lithium disilicate, bilayered zirconia, and monolithic zirconia crowns, 10 each. An intraoral scanner and a spectrophotometer were used to assess the frequency of matched shades and to calculate the color difference (ΔE) between the two central incisors at the incisal, middle, and cervical thirds. Kruskal-Wallis and two-way ANOVA were used to compare the frequency of matched shades and ΔE values, respectively (α = 0.05).

RESULTS

There was no significant (p > 0.05) difference in frequencies of matched shades for each group at the three sites; except bilayered lithium disilicate crowns. Bilayered lithium disilicate crowns had significantly (p < 0.05) higher match frequency than monolithic zirconia at the middle third. The ΔE value was not significantly (p > 0.05) different among the groups at the cervical third. However, monolithic zirconia had significantly (p < 0.05) higher ΔE values than bilayered lithium disilicate and zirconia at the incisal and middle thirds.

CONCLUSIONS

Bilayered lithium disilicate and zirconia appeared to most closely match the shade of an existing bilayered lithium disilicate crown.

[Compressive stress in three types of finishing lines with lithium disilicate crowns in permanent teeth: finite element analysis]

Introduction

In oral rehabilitation, the use of ceramic restorations is widely accepted due to its aesthetic capacity to mimic the naturalness of the dental tissue, provide longevity of the material, and present a greater marginal fit compared to crowns with a metal structure. Termination lines are biological preparations whose function is to minimize the cervical opening of the marginal seal. Consequently, analyzing the behavior of restorative materials under compressive forces decreases the risk of fracture and increases the success of the treatment.

Objective

To compare the compressive stresses of lithium disilicate crowns with three different finishing lines.

Methodology

In silico study of the simulation of a dental preparation on a lower right first molar with chamfer (0.6 mm), shoulder (0.5 mm) and deep chamfer (0.5 mm) finish lines. Using the SolidWorks®️ version 2017 software, the maximum stresses, minimum stresses, and location of the compressive force were collected on the Megapascal (Mpa) measurement scale.

Results

The chamfer type termination line (0.6mm) obtained a lower compressive stress compared to the other two shoulder type termination lines (0.5mm) and deep chamfer (0.5mm).

Conclusions

It was shown that the chamfer type finishing line (0.6mm) presented a better force distribution, determining greater reliability in the selection of this finishing line with the use of a lithium disilicate crown in a unitary manner.

Effect of 38% silver diamine fluoride on fracture resistance of leucite reinforced feldspathic ceramic CAD/CAM class I inlay restorations

INTRODUCTION

Silver diamine fluoride (SDF) is a topical agent that has recently gained popularity for its ability to stop and prevent dental caries.

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.

SEM Evaluation of the Marginal Accuracy of Zirconia, Lithium Disilicate, and Composite Single Crowns Created by CAD/CAM Method: Comparative Analysis of Different Materials

(1) Background: The objective of this in vitro study is to evaluate the marginal accuracy of crowns created by CAD/CAM. (2) Methods: A customized chrome-cobalt (Cr-Co) implant abutment simulating a maxillary right first molar was fixed in a hemi-maxillary stone model and scanned. In total, 27 crowns were fabricated, including 9 lithium disilicate crowns, 9 composite crowns, and 9 zirconia crowns. The measurements were determined by scanning electron microscopy. Descriptive analysis was performed using the mean and standard deviation, while the Kruskal-Wallis test was performed to determine whether the marginal discrepancies were significantly different between each group (p < 0.05). (3) Results: The lowest marginal gap value was reported for zirconia (21.45 ± 12.58 µm), followed by composite (44.7 ± 24.96 µm) and lithium disilicate (62.28 ± 51.8 µm). The Kruskal-Wallis tests revealed a statistically significant difference (p-value < 0.05) in the mean marginal gaps between different materials. (4) Conclusions: The proposed digital workflow can be a viable alternative for fixed prosthetic rehabilitations. The best performance in terms of marginal gap was achieved by zirconia crowns, but all three materials demonstrate marginal closure below the clinically accepted threshold value (120 µm). Clinical significance: although significant differences were reported, the investigated CAD/CAM materials showed clinically acceptable marginal gaps.

Can we use the translucency parameter to predict the CAD/CAM ceramic restoration aesthetic?

OBJECTIVES

To evaluate the effects of background color, ceramic type and coping thickness on masking ability (ΔE) and translucency parameter (TP) of CAD/CAM lithium disilicate glass-ceramic/monolithic zirconia and, to determine the correlations between coping thickness, TP and ΔE.

METHODS

A total of 120 ceramic specimens (2 mm, 1 mm and 0.5 mm thickness; n = 10) of four CAD/CAM ceramics: IPS e.max, IPS ZirCAD, Upcera Li CAD and Upcera TT CAD, were studied. Specimens were tested over nine fabricated backgrounds: A1, A2, A3.5, ND2 and ND7 shade resin-based composites, cobalt-chromium alloy (CC), medium precious alloy (MPA), black (B) and white (W). CIELab values (L*, a* and b*), color difference (ΔE) and translucency parameter (TP) were measured and calculated using a digital spectrophotometer (color i7, X-Rite, Pantone®). Data were analyzed using the Shapiro-Wilk test, one-way ANOVA, three-way ANOVA, independent t-tests and Tukey post-hoc tests (p < 0.05).

RESULTS

2 mm CAD/CAM ceramics showed ideal color matching (ΔE<2.6) over different backgrounds, except for CC, B and W backgrounds. Monolithic zirconia had lower ΔE values than lithium disilicate glass-ceramics. ΔE and TP values significantly reduced with the increased coping thickness (p < 0.05). Regardless of ceramic type and thickness, a strong TP-SD of ΔE correlation was observed.

SIGNIFICANCE

CAD/CAM ceramic restoration color was significantly affected by background color, ceramic type and coping thickness. TP is a promising predictor for appropriate ceramic selection to receive an acceptable CAD/CAM ceramic restoration aesthetic.

Bioengineering Applied to Oral Implantology, a New Protocol: “Digital Guided Surgery”

Rehabilitative dentistry has made enormous progress in recent years, not only due to the advent of new implant-prosthetic methods, but also thanks to new information technologies that support the doctor. This study aims to present a new implant protocol that involves the application of bioengineering methods. With the application of the finite element analysis, it is possible to evaluate the distribution of the forces of a fixture and possible implant rehabilitation on each patient, even before performing the surgery. This protocol provides for the combination of radiographic images and three-dimensional files to obtain predictable results on possible rehabilitation, guiding its planning in the best possible way. Surely, the evolution of machines and computers will enable the surgeon to carry out and maintain these protocols in a chair-side manner, and to carry out safe and predictable rehabilitations.

Reasons for Failure of CAD/CAM Restorations in Clinical Studies: A Systematic Review and Meta-analysis

AIM

The systematic review presented herein was performed to descriptively analyze the causes for the failure of computer-aided design/computer-aided manufacture (CAD/CAM) restorations. The meta-analysis reported herein was performed to estimate long-term survival and success rates of CAD-CAM fabrications.

MATERIALS AND METHODS

Using the PICOS paradigm, a systematic search was carried out in the PubMed and Cochrane databases to identify randomized controlled trials (RCTs) and prospective observational studies reporting survival data for CAD/CAM restorations. After selecting studies with a predefined set of selection criteria, data from included prospective clinical studies and RCTs were used for a systematic review aimed at a descriptive analysis of factors associated with failure of CAD-CAM restorations. Data from the included prospective clinical studies were used for meta-analysis, wherein 5-year and 10-year survival and success rates were estimated using Poisson regression models.

RESULTS

The systematic review included data from 9 RCTs and 6 observational studies, which had a median follow-up of 36 months and 60 months, respectively. About 58 failures and 118 technical/ biological complications were noted in the included RCTs and 9 failures along with 58 technical/biological complications were noted in the prospective clinical studies. Poisson regression indicated an estimated 5-year and 10-year survival rates of 85.55-100 and 71-100, respectively. The estimated 5-year and 10-year success rates were 74.2-92.75 and 33.3-85.5, respectively.

CONCLUSION

Several technical and biological complications contribute to failure of CAD/CAM restorations. However, CAD/CAM restorations with routine chairside materials might have clinically meaningful success rates in the long term.

CLINICAL SIGNIFICANCE

The results presented herein indicate that optimal strategies for mitigation of biological and technical complications may augment the success of CAD/CAM fabrications in restorative dentistry. Studies aimed at identification of such strategies are needed to further enhance the long-term success rates of CAD/CAM restorations.

Bonding ability of resin cements to different types of CAD/CAM composite blocks

This study investigated the bonding performance of two different types of resin cements to computer-aided design/computer-aided manufacturing (CAD/CAM) composite blocks based on the shear bond strength (SBS) test. A silane-containing self-adhesive resin cement (Panavia SA Cement Universal) and resin luting cement (Block HC Cem) with a primer, were used. Specimens were fabricated from three different types of CAD/CAM composite blocks, and their surfaces were blasted with alumina. Resin cements were bonded to the specimens, and their SBSs were measured after 15 min, 24 h, and after being subjected to thermal cycling for 10,000 and 30,000 cycles. Three-way ANOVA for bond strength revealed that CAD/CAM composite block, resin cement and storage time significantly influenced the SBS values, and the three-way interactions between the evaluated factors, and all the interactions were significant. It was concluded that the bonding performance of resin cements to CAD/CAM composite blocks were material and storage period dependent.

Marginal and internal fit and intaglio surface trueness of interim crowns fabricated from tooth preparation of four finish line locations

This study evaluated the marginal and internal fit and intaglio surface trueness of interim crowns fabricated from tooth preparation scanned at four finish line locations. The right maxillary first molar tooth preparation model was fabricated using a ceramic material and placed in four finish line locations (supragingival, equigingival, subgingival, and subgingival with a cord). Intraoral scanning was performed. Crowns were designed based on the scanned area. Interim crowns were fabricated using a stereolithography three-dimensional (3D) printer (N = 16 per location). Marginal and internal fit were evaluated with a silicone replica technique. Intaglio surface trueness was evaluated using a 3D inspection software. One-way analysis of variance and Tukey HSD test were performed for comparisons (α = 0.05). The marginal and internal fit showed significant differences according to locations (P < 0.05); the marginal fit showed the best results in the supragingival finish line (P < 0.05). Intaglio surface trueness was significantly different in the marginal region, with the highest value in the subgingival location (P < 0.05). Crowns fabricated on the subgingival finish line caused inaccurate marginal fit due to poor fabrication reproducibility of the marginal region. The use of an intraoral scanner should be decided on the clinical situation and needs.

Long-term clinical performance and complications of zirconia-based tooth- and implant-supported fixed prosthodontic restorations: A summary of systematic reviews

OBJECTIVES

To present an overview on systematic reviews on prosthodontic zirconia restorations and to discuss long-term complications as well as information on anatomical and functional changes to the masticatory system.

DATA/SOURCES

MEDLINE, EMBASE, Trip medical, and Cochrane Library databases were searched for systematic reviews up to February 2021. Bias was assessed and clinical survival and complications were analyzed.

STUDY SELECTION

38 eligible articles published between 2006 and 2021 were included. The reviews were based on 128 in vivo studies on approximately 10,000 zirconia restorations. 5-year cumulative survival rates varied between 91.2% and 95.9% for tooth-supported (TS) single crowns (SC), 89.4% and 100% for TS multi-unit fixed dental prostheses (FDP), 97.1% and 97.6% for implant-supported (IS) SCs and 93.0% and 100% for IS FDPs. Chipping was the most often technical complication, followed by framework fracture, loss of retention, marginal discrepancies/discoloration, occlusal roughness and abutment/screw loosening. Color mismatch was the only esthetic complication. Biological complications were caries, endodontic complications, tooth fracture, periodontal disease, abrasion/attrition, persisting pain, high sensitivity, peri‑implantitis and soft tissue issues. Patients with bruxism were only examined sporadically.

CONCLUSIONS

5-year results for zirconia restorations were satisfactory. The predominant technical problem of veneering fractures could be overcome with adapted design or fabrication and application of monolithic restorations, but reviews of clinical studies on this subject are rare. The impact of zirconia restorations on the masticatory system remains unclear.

CLINICAL SIGNIFICANCE

Zirconia restorations are experiencing a rapidly increasing use in dental practice. Being highly wear-resistant, hard and durable, it can be assumed that they do not follow natural abrasion and changes in the masticatory system. Possible long-term effects on the stomatognathic system as a whole should therefore be considered.

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 2019 restorative dental literature is offered to inform busy dentists regarding remarkable publications and noteworthy progress made in the profession. Developed by the Scientific Investigation Committee of the American Academy of Restorative Dentistry, each author brings discipline-specific expertise to 1 of 8 sections of the report: (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 likely to influence day-to-day dental treatment decisions. Each review is not intended to stand alone but to update interested readers so that they may visit source material when greater detail is desired. As the profession moves toward evidence-based clinical decision-making, an incredible volume of potentially valuable dental literature continues to increase. It is the intention of this review and its authors to provide assistance in negotiating the extensive dental literature published in 2019. It is our hope that readers find this work useful in the clinical management of dental patients.

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.

Utilization of Er:YAG Laser in Retrieving and Reusing of Lithium Disilicate and Zirconia Monolithic Crowns in Natural Teeth: An In Vitro Study

The study examined the effect of noninvasive crown retrieval/reuse process using an erbium-doped yttrium aluminum garnet laser (Er:YAG). Twenty-six extracted human teeth were prepared for a crown. The crown was milled using lithium disilicate (LD) and zirconia (Z) materials, n = 13 per group, with three for scanning electron microscopy (SEM). The crown was luted using composite resin cement and subjected to a laser retrieval process. After the retrieval process, the crown was cleaned, re-cemented and laser-retrieved two more times, without and with additional tooth reduction mimicking clinical refreshment of dentin. Retrieval time and temperature were analyzed using analysis of variance (ANOVA). Surface changes were observed through SEM. The retrieval times were 267.1 ± 130.43, 220 ± 79.09, 277.1 ± 126.44, 368.4 ± 136.14, 355 ± 159.39, and 419.2 ± 121.36 s for first, second, third LD and Z groups, respectively (p = 0.009). The maximal temperatures were 23.95.1 ± 1.89 °C, 24.86 ± 2.01 °C, 24.17 ± 1.53 °C, 22.88 ± 1.51 °C, 24.03 ± 1.74 °C, and 21.99 ± 1.32 °C for first, second, third LD and Z groups, respectively (p = 0.006). Er:YAG laser crown removal is an effective retrieval tool for all-ceramic crowns. Minimal changes to teeth and crowns were observed following laser irradiation.

3D Digital Impression Systems Compared with Traditional Techniques in Dentistry: A Recent Data Systematic Review

The advent of new technologies in the field of medicine and dentistry is giving improvements that lead the clinicians to have materials and procedures able to improve patients' quality of life. In dentistry, the last digital techniques offer a fully digital computerized workflow that does not include the standard multiple traditional phases. The purpose of this study is to evaluate all clinical trials and clinical randomized trials related to the digital or dental impression technique in prosthetic dentistry trying to give the readers global information about advantages and disadvantages of each procedure. Data collection was conducted in the main scientific search engines, including articles from the last 10 years, in order to obtain results that do not concern obsolete impression techniques. Elsevier, Pubmed and Embase have been screened as sources for performing the research. The results data demonstrated how the working time appears to be improved with digital workflow, but without a significant result (P = 0.72596). The papers have been selected following the Population Intervention Comparison Outcome (PICO) question, which is related to the progress on dental impression materials and technique. The comparison between dentists or practitioners with respect to classic impression procedures, and students open to new device and digital techniques seem to be the key factor on the final impression technique choice. Surely, digital techniques will end up supplanting the analogical ones altogether, improving the quality of oral rehabilitations, the economics of dental practice and also the perception by our patients.

Are Metal-Free Monolithic Crowns the Present of Prosthesis? Study of Mechanical Behaviour

Purpose: To analyze in vitro the mechanical behavior of five types of complete coverage crowns fabricated from different materials. Materials and methods: Seventy-five full coverage crowns were divided into five groups according to material: Group I, metal core with feldspathic ceramic covering (MC- control group); Group II, zirconia core with feldspathic ceramic covering (CZ); Group III, tetragonal monolithic zirconia (TMZ); Group IV, cubic monolithic zirconia (CMZ); Group V, high molecular weight polymethyl methacrylate (PMMAG) doped with graphene nanoparticles. All crowns underwent in vitro fatiguing by dynamic loading in wet conditions to simulate the masticatory forces to which prosthodontic materials are subject in the oral medium. Lastly, fracture resistance was evaluated by static compression testing. Results: The fracture resistance values obtained were as follows: Group MC, 2443.6 ± 238.6 N; Group CZ, 2095.4 ± 329.2 N; Group TMZ, 2494.6 ± 236.6 N; Group CMZ, 1523.6 ± 325.2 N; and Group PMMAG, 1708.9 ± 386.6 N. Group MC presented higher strength with statistically significant differences in comparison with Groups CZ (P = 0.002), CMZ (P < 0.001), and PMMAG (P < 0.001). Weibull distribution showed less probability of cumulative biomechanical failure in Groups MC and TMZ. Conclusions: Metal-ceramic and tetragonal zirconia showed high fracture resistance, while cubic zirconia and PMMA doped with graphene nanoparticles obtained lower values.