Ten-year survival of pressed, acid-etched e.max lithium disilicate monolithic and bilayered complete-coverage restorations: Performance and outcomes as a function of tooth position and age

Monolithic Hybrid Abutment Crowns (Screw-Retained) Versus Monolithic Hybrid Abutments With Monolithic Crowns (Adhesively Cemented): Three-Year Data of a Prospective Clinical Split-Mouth Study

OBJECTIVES

This study compares the restoration of single-tooth implants with screw-retained lithium-disilicate hybrid-abutment crowns and single-tooth lithium-disilicate crowns adhesively bonded to hybrid abutments with regard to objective clinical and subjective patient-specific evaluation criteria over a time of observation of 3 years.

MATERIALS AND METHODS

Two bone-level implants were placed in contralateral sides of the same jaw in 10 patients, each with two single-tooth gaps. After osseointegration, implants were uncovered and an impression was taken. In accordance with the split-mouth design, one implant in each patient was restored with a screw-retained hybrid abutment crown and the other implant with a hybrid abutment and an adhesively bonded single-tooth crown. The restorations were randomly allocated to the implants. Prefabricated titanium bases were used. The ceramic abutments and restorations were fabricated monolithically with pressed lithium-disilicate ceramic. An objective evaluation (survival, technical, or biological complications, FIPS) by the practitioner and a subjective evaluation (satisfaction, OHIP) by the patient were carried out after 3, 6, 12, 24, and 36 months after restoration placement.

RESULTS

Both restoration types showed a survival rate of 100% after 3 years of observation. No technical or biological complications occurred. No significant difference was observed between the two types of restoration neither for objective (survival, technical or biological complications, FIPS) nor subjective (satisfaction, OHIP) evaluation criteria (p > 0.05).

CONCLUSION

No statistically significant differences were observed between screw-retained and cemented pressed lithium-disilicate restorations on bone-level implants for both objective and subjective evaluation criteria, respectively.

CLINICAL SIGNIFICANCE

Monolithic hybrid-abutment crowns (screw-retained) and monolithic hybrid abutments with single-tooth crowns (cemented) made of pressed lithium disilicate can be used to successfully restore single implants.

Multicenter Prospective Clinical Study on Chairside-Fabricated Partial Crowns: 5-Year Results for Lithia-Zirconia Glass-Ceramic Restorations

OBJECTIVES

Clinical evaluation of chairside-fabricated lithia-zirconia glass-ceramic (LZGC) partial crowns (CCPCs) in a multicenter practice-based study.

MATERIALS AND METHODS

Seventy-one patients were restored with 92 adhesively luted CCPCs (Cerec SW 4.2/Cerec MC XL/Celtra Duo) in three private dental clinics (C1-C3). Time-dependent (Kaplan-Meier) survival rates (SVR) and success rates (SCR) were calculated. The following possible covariates of SVRs and SCRs were evaluated in a Cox regression model: Restoration position (premolar/molar), luting material (Variolink/Calibra), and operator (C1-C3).

RESULTS

Seventy-three CCPCs were placed in 59 patients and were included in the study (mean observational period: 58.0 ± 15 months). Four complete failures (two tooth fractures, one restoration fracture, and one endodontic failure) were recorded. All failures and interventions occurred in one of the three centers (5-year SCR: C1 + C2: 100%; C3: 71%; 95% confidence interval: [0.55; 0.87]). Additionally, three biological, and two technical complications required clinical intervention to maintain function, and all occurred in C3. Restorations placed in C1 and C2 showed a significantly reduced risk for failure/intervention (hazard ratio = 0.103, p = 0.026) compared with restorations placed in C3.

CONCLUSIONS

LZGC CCPCs showed good five-year clinical performance. However, SVRs and SCRs were significantly influenced by the operator. Additional clinical data are required for a more detailed investigation of this effect.

Minimally invasive prosthodontics using the concept of prosthetically guided orthodontics

OBJECTIVE

This case report aims to present how digital technology can be employed to plan the orthodontic movement of teeth into their final positions for prosthodontic rehabilitation. An interdisciplinary approach to treatment planning and the result of prosthodontic treatment involves the cooperation of an orthodontist and a prosthodontist. When planned to achieve optimal results for a minimally invasive and functional prosthodontic treatment, orthodontic pretreatment provides superior esthetic results and favorable long-term success.

CLINICAL CONSIDERATIONS

The orthodontic movements of the teeth were planned so that the prosthodontist could reconstruct an optimally functional and esthetic occlusion while preserving the hard dental tissues. The orthodontic pretreatment minimized the need to prepare the teeth, avoiding any mucogingival surgery to improve the gingival architecture.

CONCLUSIONS

In complex clinical cases, it is essential to evaluate the advantages of an orthodontic pretreatment before starting a prosthodontic treatment. This pretreatment can help preserve dental tissues, reduce or eliminate the need for surgical intervention, and achieve long-term stability and esthetic results.

CLINICAL SIGNIFICANCE

This case clearly shows the benefits of orthodontic pretreatment for prosthodontic outcomes. With modern digital tools, such an orthodontic pretreatment should become standard clinical practice when planning a complex clinical case.

Over 14-year survival of pressed e.max lithium disilicate glass-ceramic complete and partial coverage restorations in patients with severe wear: A prospective clinical study

STATEMENT OF PROBLEM

Long-term clinical data are lacking on the comparative survival of adhesively luted lithium disilicate glass-ceramic complete and partial coverage restorations in patients with severe wear and the effect that different clinical variables have on their survival.

PURPOSE

The purpose of this study was to examine the 14-year survival of pressed e.max lithium disilicate glass-ceramic complete and partial coverage restorations in patients with severe wear and to evaluate associated clinical parameters.

MATERIAL AND METHODS

Patients demonstrating severe wear and requiring single unit defect-specific partial or complete coverage restorations were recruited in a clinical private practice and received lithium disilicate restorations. The effect of various clinical parameters was evaluated using Kaplan-Meier survival curves to account for attrition bias and other causes of failure. The statistical significance of differences between parameters was determined by using the log rank test (α=.05).

RESULTS

A total of 53 participants (24 men and 29 women) requiring 662 lithium disilicate restorations were evaluated. The mean age of the participants at the time of restoration placement was 60 (range 25 to 85 years). Of 662 units, 551 were anterior and posterior complete and 111 were posterior partial coverage restorations. Six failures (bulk fracture or large chip) requiring replacement occurred with the average time to failure of 4.5 (range 2 to 8) years, yielding a crude estimate of annual failure of 0.1% (cumulative monitoring period of 4650 years, overall survival rate of 98.6%). Of the 551 complete coverage restorations, 4 failed (0 anterior, 4 posterior), yielding a crude estimate of 0.1% annual failure with the survival function time at 14 years. Of the 111 partial coverage restorations, 2 failed, yielding a crude estimate of 0.4% annual failure with the survival function time at 12 years. The only statistically significant difference was seen between anterior crowns and posterior onlays, with no failures in anterior crowns (P<.001). Other clinical variables had no significant effect on survival (P>.05).

CONCLUSIONS

Pressed e.max lithium disilicate partial and complete coverage restorations both showed high survival rates in patients with severe wear over 14 years with an overall yearly failure rate of 0.1%. Risk of failure at any age was minimal for both men and women. All anterior crowns survived. The highest annual failure rate (0.4%) was for posterior onlay partial coverage restorations.

Treatment planning algorithm for patients with a terminal dentition

This article discusses the variables that affect the diagnostic process in patients with a compromised dentition and addresses the clinical decision of whether to extract or maintain teeth. A decision tree algorithm is proposed to guide clinicians in planning complete arch rehabilitations.

Clinical performance of bonded partial lithium disilicate restorations: The influence of preparation characteristics on survival and success

OBJECTIVES

The aim of this study was to investigate the influence of preparation characteristics on the survival, success, and clinical performance of partial indirect lithium disilicate restorations with immediate dentin sealing.

METHODS

This retrospective clinical study evaluated partial indirect lithium disilicate restorations placed in conjunction with Immediate Dentin Sealing (IDS) in (pre)molar teeth between March 2018 and May 2021. The restorations were luted using pre-heated composite. The study focused on survival, success, and clinical performance, which was evaluated using the modified United States Public Health Service (USPHS) criteria. Results were analyzed using the Kaplan-Meier estimates, log-rank tests, and Fisher exact tests.

RESULTS

Partial indirect lithium disilicate restorations (N = 454) were evaluated in 214 patients. The mean evaluation time was 37 months, with a cumulative survival rate of 99.2 % and a cumulative success rate of 97.6 %. Fourteen failures occurred, with endodontic pathology as the predominant failure mode, followed by secondary caries, debonding, and tooth fracture. No statistically significant influence of the preparation variables on survival and success was observed (p > .05). The short-term clinical performance was clinically acceptable in > 90 % of the evaluations.

CONCLUSIONS

This retrospective study on partial indirect lithium disilicate restorations in conjunction with IDS demonstrates survival and success rates of 99.2 and 96.7 % over a mean evaluation period of 37 months. A marked influence of the studied preparation characteristics on the survival, success and clinical performance of lithium disilicate partial restorations could not be demonstrated. Partial lithium disilicate restorations exhibit good clinical performance in >90 % of the cases.

CLINICAL SIGNIFICANCE

The results of this study suggest that preparation characteristics had no significant impact on the survival, success, and clinical performance of partial lithium disilicate restorations in conjunction with IDS. Results show good clinical performance and high survival and success rates, regardless of preparation characteristics.

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.

Ultrathin lithium disilicate and translucent zirconia crowns for posterior teeth: Survival and failure modes

PURPOSE

To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra-translucent zirconia crowns for posterior teeth restorations.

MATERIALS AND METHODS

Fifty-four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y-TZP (Zirconn Translucent, Vipi), and (3) 5Y-PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth-motion step-stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope.

RESULTS

Beta (β) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95-99) regarding 3Y-TZP and 5Y-PSZ groups (84% CB: 65%-93% and 79% CB: 37&-94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%-91%) was higher than 5Y-PSZ (20% CB: 4%-44%) and not significantly different from 3Y-TZP (54% CB: 32%-72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface.

CONCLUSIONS

Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high-load bearing regions must be carefully evaluated.

CLINICAL SIGNIFICANCE

Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre-molars. Their clinical indication in high-load requirement regions must be carefully evaluated.

Effect of different surface treatment protocols on the bond strength between lithium disilicate and resin cements

Because the use of hydrofluoric acid (HF) poses health risks if handled improperly, many clinicians prefer to have the ceramic restorations pre-etched in dental laboratories. However, during the try-in procedure, the pre-etched glass-ceramic restorations may be contaminated with saliva resulting in reduced bond strength. This in-vitro study aimed to investigate the effect of different surface treatments on the bond strength of lithium disilicate (LD) glass-ceramic restorations (IPS e.max Press, Ivoclar Vivadent) to two resin cements. One-hundred eighty blocks (4X4X3mm) of LD glass-ceramic were divided into twelve groups (n = 15), of which six received Variolink Esthetic DC (VE) cement and six received RelyX Ultimate (RU) cement, following the surface treatments: G1) Control: Hydrofluoric Acid + Silane (HF + Sil); G2) Hydrofluoric Acid + Saliva + Silane (HF + S + Sil); G3) Hydrofluoric Acid + Saliva + Ivoclean + Silane (HF + S + IC + Sil); G4) Hydrofluoric Acid + Saliva + Phosphoric Acid + Silane (HF + S + P + Sil); G5) Hydrofluoric Acid + Saliva + Monobond Etch & Prime (HF + S + EP); G6) Monobond Etch & Prime (EP). Following treatment, a resin-cement cylinder (2.3 mm diameter) was built on the glass-ceramic surface, photocured (20 s), stored in distilled water (37 °C, 24 h) and submitted to the shear bond strength test. Bond strength data (MPa) were subjected to two-way ANOVA and Tukey (α = 0.01). Cement type and surface treatment had a significant effect on the bond strength (p < 0.001) (Table 4). Single-step Monobond Etch & Prime (EP) significantly improved the bond strength of resin-cements to glass-ceramic with and without saliva contamination.

Retrospective clinical study on the performance and aesthetic outcome of pressed lithium disilicate restorations in posterior teeth up to 8.3 years

OBJECTIVES

Evaluation of cumulative survival and complication rate of monolithic lithium disilicate inlays and partial crowns performed by supervised undergraduate students up to 8.3 years of clinical service.

MATERIALS AND METHODS

In this retrospective clinical study 143 lithium disilicate posterior restorations (IPS e.max Press) were examined according to the FDI criteria. A standardised questionnaire was used to determine patient satisfaction. The aesthetic outcome was evaluated by dentists and dental technicians using intraoral photographs. Data were descriptively analysed. Cumulative survival and success rates were calculated using Kaplan-Meier estimation.

RESULTS

The cumulative survival rate of lithium disilicate restorations was 97.5% after a mean service time of 5.9 years and 95.0% after 8.3 years. The cumulative success rate decreased from 94.4% after 5.9 years to 30.7% after 8.3 years. Repairs were required for 7 restorations (4.9%), and 5 (3.5%) were classified as failures. The results of the questionnaire indicate a high level of patient satisfaction. The subjective aesthetics were assessed more critically by dental technicians compared to dentists.

CONCLUSION

Lithium disilicate posterior restorations survived successfully up to 8.3 years when carried out by undergraduate students.

CLINICAL RELEVANCE

Pressed lithium disilicate glass ceramic inlays and partial crowns are reliable treatment options in posterior teeth.

Advanced lithium disilicate: A comparative evaluation of translucency and fatigue failure load to other ceramics for monolithic restorations

The aim of this in vitro study was to evaluate the surface roughness, translucency, fatigue failure load (FFL), and number of cycles for fatigue failure (CFF) of a recently released lithia-based material called advanced lithium disilicate and three other ceramics indicated for monolithic restorations. First, ALD (advanced lithium disilicate, CEREC Tessera, Dentsply Sirona), LD (lithium disilicate, IPS e. max CAD, Ivoclar), LS (lithium silicate-disilicate, Suprinity, Vita Zahnfabrik), and 4Y-PSZ (Yttria-stabilized zirconia, IPS e.max ZirCAD MT, Ivoclar) discs (n = 15, Ø = 10 mm and thickness = 1.0 mm) were fabricated from CAD/CAM blocks/discs, A2 shade. The discs were sintered/crystallized and subsequently analyzed by a rugosimeter (Mitutoyo SJ-410) to determine Ra and Rz surface roughness parameters. Next, they were evaluated to determine the translucency parameter (TP) using a bench-top spectrophotometer (SP60, EX-Rite). The discs were subsequently cemented to glass fiber epoxy resin discs, and the specimens were tested under cyclic loading (Step-test), immersed in distilled water at a frequency of 20 Hz, with an initial cyclic load of 200 N for 5,000 cycles and increments of 50 N every 10,000 cycles until failure. Fatigue failure load (FFL) and number of cycles for fatigue failure (CFF) were recorded for subsequent Kaplan Meier analysis, with post-hoc Mantel-Cox and Weibull analysis (α = 0.05). Complementary fractographic, topographic and energy dispersive spectroscopy analyses (EDS) were performed. 4Y-PSZ showed higher survival (p < 0.05), with higher FFL and CFF (1077 N; 180,333 cycles), followed by LD (980 N; 161,000 cycles), LS (937 N; 152,333 cycles) and ALD (910 N; 147,000 cycles). No differences were observed between the tested groups regarding Weibull modulus. ALD presented TP (28.14) equal to DL (28.27) and higher than LS (25.51). All lithia-based materials had higher translucency than 4Y-PSZ (TP = 8.62) (p < 0.05). ALD appears to have a similar elemental composition to LD and LSD for oxygen and silicon. ALD and LSD have a similar zirconium content. Fractures originated on the cemented surface of the ceramic discs. Lithia-based ceramics showed lower surface roughness, with ALD (Ra = 0.04 μm; Rz = 0.66 μm) showing the lowest values (p < 0.05). Despite showing lower FFL when compared to LD and 4Y-PSZ, ALD has compatible translucency and mechanical fatigue performance with its indication for fabricating monolithic, anterior and posterior adhesively cemented single-unit restorations. However, further studies are needed to substantiate its clinical performance.

Translucent Zirconia in Fixed Prosthodontics-An Integrative Overview

Over the past two decades, dental ceramics have experienced rapid advances in science and technology, becoming the fastest-growing field of dental materials. This review emphasizes the significant impact of translucent zirconia in fixed prosthodontics, merging aesthetics with strength, and highlights its versatility from single crowns to complex bridgework facilitated by digital manufacturing advancements. The unique light-conducting properties of translucent zirconia offer a natural dental appearance, though with considerations regarding strength trade-offs compared to its traditional, opaque counterpart. The analysis extends to the mechanical attributes of the material, noting its commendable fracture resistance and durability, even under simulated physiological conditions. Various zirconia types (3Y-TZP, 4Y-TZP, 5Y-TZP) display a range of strengths influenced by factors like yttria content and manufacturing processes. The study also explores adhesive strategies, underlining the importance of surface treatments and modern adhesives in achieving long-lasting bonds. In the realm of implant-supported restorations, translucent zirconia stands out for its precision, reliability, and aesthetic adaptability, proving suitable for comprehensive dental restorations. Despite its established benefits, the review calls for ongoing research to further refine the material's properties and adhesive protocols and to solidify its applicability through long-term clinical evaluations, ensuring its sustainable future in dental restorative applications.

Printed Digital Wax-up Model as a Blueprint for Layered Pressed-ceramic Laminate Veneers: Technique Description and Case Report

This article presents a clinical technique for transferring Digital Smile Design (DSD) information and a digital wax-up to fabricate highly personalized ceramic laminate veneers. The hybrid workflow of digitally designed wax-up and conventional hand-crafted veneers is showcased in a female adult who sought to improve her smile due to maxillary anterior incisal wear. The ceramic veneers, layered by feldspathic porcelain, followed the contours and shade blueprint planned with the digital wax-up. The DSD improved the harmony of the facial-and-smile relationship, and the ceramic restorations fulfilled the patient's esthetic and functional demands. Guides based on the printed model with the digitally designed wax-up can provide a reference for pressed lithium disilicate veneers layered with feldspathic porcelain.

Clinical survival and performance of premolars restored with direct or indirect cusp-replacing resin composite restorations with a mean follow-up of 14 years

OBJECTIVES

The objective is to evaluate the long-term clinical survival and performance of direct and indirect resin composite restorations replacing cusps in vital upper premolars.

METHODS

Between 2001 and 2007, 176 upper premolars in 157 patients were restored with 92 direct and 84 indirect resin composite restorations as part of an RCT. Inclusion criteria were fracture of the buccal or palatal cusp of vital upper premolars along with a class II cavity or restoration in the same tooth.

RESULTS

Forty patients having 23 direct and 22 indirect composite restorations respectively, were lost to follow-up (25.6%). The cumulative Kaplan-Meier survival rates were 63.6% (mean observation time: 15.3 years, SE 5.6%) with an AFR of 2.4% for direct restorations and 54.5% (mean observation time: 13.9 years, SE: 6.4%) with an AFR of 3.3% for indirect restorations. The Cox regression analysis revealed a statistically significant influence of the patient's age at placement on the survival of the restoration (HR 1.036, p = 0.024), the variables gender, type of upper premolar, type of restoration, and which cusp involved in the restoration had no statistically significant influence. Direct composite restorations failed predominantly due to tooth fracture, indirect restorations primarily by adhesive failure (p < 0.05).

SIGNIFICANCE

There was no statistically significant difference in survival rates between direct and indirect composite cusp-replacing restorations. Both direct and indirect resin composite cusp-replacing restorations are suitable options to restore compromised premolars. The longer treatment time and higher costs for the indirect restoration argue in favor of the direct technique.

The use of the monolithic ceramic and direct monolithic composite in the aesthetic rehabilitation of tooth wear

Traditional cold layering composite techniques can have limitations in the aesthetic rehabilitation of advanced tooth wear, with potentially high maintenance/failure rates and compromised aesthetics. This article explores advances in materials and clinical techniques involving monolithic ceramics and direct monolithic composites. These restorations satisfy the most aesthetically demanding patient, providing good to excellent aesthetics and long-term predictability.

Polishing the bonding surface, before or after crystallization, does not alter the fatigue behavior of bonded CAD-CAM lithium disilicate

The aim of this study was to assess if the finishing/polishing of the bonding surface of lithium disilicate ceramic, prior to or after crystallization, would affect the fatigue behavior of a bonded restorations. For this, lithium disilicate ceramic (IPS e.max CAD) discs (n = 15) were milled and randomly divided into 3 groups: CAD-CAM group which remained untouched; PRE group which received a finishing/polishing protocol (OptraFine system) prior to its crystallization; and POST group, which received the treatment after its crystallization. After surface treatments, ceramic and glass-fiber reinforced epoxy resin discs were paired and bonded using a resin cement (Multilink N). A cyclical fatigue test was conducted (frequency 20 Hz, initial load 200 N for 5000 cycles, step-size of 100 N for 10,000 cycles/step) until failure occurrence. Surface roughness and topography were analyzed. An initial descriptive analysis of surface roughness, FFL and CFF was performed to obtain the mean, standard deviation and confidence interval values (SPSS v. 21, SPSS Inc.) for statistical analysis. Roughness data was using one-way ANOVA with Tukey's post hoc test (α = 0.05), while the fatigue data was submitted to survival analysis with Kaplan-Meier test (α = 0.05) and Weibull modulus (Weibull++, Reliasoft). Neither the finishing/polishing procedure of the bonding surface, nor the moment (prior to or after crystallization), affected the fatigue behavior of bonded milled lithium disilicate. There were also no differences for mechanical reliability among conditions. Despite this, finishing/polishing reduced surface roughness and led to smoother topography. Finishing/polishing the bonding surface of milled lithium disilicate, before or after crystallization, does not alter the fatigue behavior of the bonded restorative set, although there is some influence on roughness and topography.

An engineering perspective of ceramics applied in dental reconstructions

The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.

Effect of the region of the CAD/CAM block on the flexural strength and structural reliability of restorative materials

The aim of the study was to evaluate whether the region (internal or external) of the CAD/CAM block influences the mechanical performance of restorative materials. Blocks of different CAD/CAM materials (Composites: KAV - Katana Avencia; LULT - LULT Ultimate; Ceramics: ENAM - Vita Enamic; NICE - N!CE; EMP - IPS Empress CAD; VMII - Vita Mark II; EMAX - IPS e.max CAD) were selected, and direct resin composite blocks (APX - Clearfil AP-X; FSUP - Filtek Supreme) were built using the incremental technique on a mold from one of the CAD/CAM blocks. All blocks were sectioned into bar-shaped specimens (1 × 1 × 14 mm), which were separated into two groups according to the region of the block (inside or outside). 3-point bending tests were performed following ISO 6872:2015 and flexural strength data were analyzed using one-way ANOVA and Bonferroni post-hoc tests (p < 0.05). Weibull module and characteristic strength were also calculated. In general, the mean flexural strength values were not statistically different (p > 0.05) between the inside and outside regions of each material, except for LULT (inside > outside) and EMAX (outside > inside). Comparing the materials, a similar strength (only discrete variations) was observed for inside, outside or merged (inside and outside data assembled together) regions: EMAX > KAV = LULT > NICE = APX > EMP = ENAM = VMII ≥ FSUP (merged condition). Characteristic strength at 63.2% failure probability and at 5% failure probability generally corroborates such observations. There were no statistical differences for Weibull module data (inside, outside, or merged), except for KAV and NICE (outside > inside). Thus, the region from where the restoration is milled within the CAD/CAM block generally does not influence the mechanical performance hereof (flexural strength, failure probability, risk of premature failures, and mechanical reliability) of the material, except for LULT and EMAX.

Incidence of endodontic therapy after complete or partial coverage glass-ceramic restorations with a follow-up time of over 30 years: A prospective clinical study

STATEMENT OF PROBLEM

Long-term clinical data are lacking on the comparison of the incidence of endodontic therapy in adhesively luted complete and partial coverage glass-ceramic restorations, as well as on the effect of technique and clinical variables.

PURPOSE

The purpose of this prospective clinical study was to assess the long-term incidence of teeth requiring endodontic therapy after receiving either complete or partial coverage glass-ceramic restorations.

MATERIAL AND METHODS

Participants requiring single anterior complete, posterior complete, or posterior partial (inlay or onlay) coverage restoration, or a combination of these on a vital tooth were recruited from a clinical private practice. Only the participants who chose glass-ceramic partial and complete coverage restorations without the need of endodontic therapy were included in the study. The overall clinical performance of these glass-ceramic restorations was assessed by 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 by using the log rank test (α=.05).

RESULTS

A total of 1800 participants requiring 4511 glass-ceramic anterior and posterior restorations were evaluated. The mean age of the participants at the time of restoration placement was 62 (range 20 to 99 years, 710 men and 1090 women). Of 4511 restorations, 1476 were anterior complete coverage, 2119 posterior complete coverage, and 916 posterior partial coverage. Endodontic therapy after restoration placement was needed for 76 restorations (10 anterior complete, 50 posterior complete, and 16 posterior partial). The total time at risk was 50 436 years providing an estimated need for endodontic therapy risk of 0.15% per year. The estimated 35-year cumulative survival was 97.36%. The majority of endodontic treatments (67%, 52/76) occurred in the first 5 years. The estimated cumulative survival of anterior complete coverage, posterior complete coverage, posterior partial inlay, and posterior partial onlay restorations was 98.89% (n=1476, 10 endodontic treatments), 96.38% (n=2119, 50 endodontic treatments), 96.78% (n=553, 11 endodontic treatments), and 98.53% (n=363, 5 endodontic treatments), respectively. Statistically significant differences occurred between anterior complete coverage, posterior complete coverage, and posterior partial coverage inlay restorations, with a higher incidence in posterior complete coverage and posterior partial inlay restorations (P<.05). First molars had the highest rate of endodontic therapy after restoration in both arches. Age and restoration thickness were significant factors, recording statistically higher number of endodontic treatments in participants >52 years and restorations with all surfaces ≥1 mm (P<.05). Other clinical variables, dental arch and sex of the participants, were not significantly related to endodontic treatments (P>.05).

CONCLUSIONS

The clinical performance of 4511 units over 30 years in service was excellent, with the estimated cumulative survival of 97.36%. Posterior complete coverage and posterior partial inlay restorations had a significantly higher need for endodontic therapy than anterior complete coverage restorations. Their overall clinical performance relative to endodontic treatment was excellent with a cumulative survival of 96.38% and 96.78% over 30 years. There was no difference in the endodontic treatment rate between posterior complete and partial coverage restorations. Thickness of the restoration affected the endodontic treatment rate, with ≥1 mm resulting in higher incidence. The age of the participants influenced the endodontic treatment rate, with higher incidence in the >52-year age group. Other confounding clinical variables did not have a significant effect on the endodontic treatment rate.

Survival of Complete Coverage Tooth-Retained Fixed Lithium Disilicate Prostheses: A Systematic Review

Background and objectives: Porcelain-fused-to-metal (PFM) prostheses are considered the gold standard for the replacement of missing teeth, however, these have several drawbacks. Therefore, lithium disilicate (LDS) prostheses have been introduced for the construction of fixed crowns and bridges. The aim of this systematic review was to ascertain the long-term survival of LDS fixed prostheses in comparison to other materials. Materials and methods: The focused question was 'In patients who have undergone prosthodontic treatment (participants), what are the overall survival rate of lithium disilicate (LDS) crowns and fixed bridges; and how do they relate to survival rates of non-LDS similar restoration are the survival and com-plication rates (outcomes) of LDS-based fixed prostheses with complete coverage (intervention) higher or lower when compared to non-LDS materials (controls)?'. An electronic search was conducted in PubMED/Medline, EMBASE, Google Scholar, and ClinicalTrials.gov for articles published between January 2006 and August 2022 using appropriate MeSH terms and keywords. The following types of studies were included: (1) All types of prospective clinical studies; (2) Clinical studies focusing on the survival of fixed LDS bridges and crowns; (3) Studies using natural teeth with complete coverage as abutment for fixed LDS bridges and crowns; and (4) Studies in English. The following studies were excluded: (1) Laboratory/in vitro studies and studies on LDS prostheses with no description of outcomes or survival rates; (2) Commentaries; (3) Letters to the editor; (4) Reviews; and (5) Internal data from manufacturers. The data from included studies were extracted and the risk of bias was assessed within the studies using ROBINS-I. Results: A total of 25 studies were included in this systematic review. The overall 5-year and 10-year survival rates were of 95-100% and 71.4-100%, respectively. Generally, three-unit bridges had a significantly lower survival rate over 5 and 10 years compared to single-unit crowns. Overall, the risk of bias in the included studies was moderate. Conclusions: The LDS-based complete coverage prostheses have a survival rate ranging between 48.6% and 100%. Furthermore, due to the lack of comparative studies, the long-term function and survival of LDS prostheses compared to other material prosthesis (PFM and ZrO) is debatable.

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.

Comparative Assessment of the Functional Parameters for Metal-Ceramic and All-Ceramic Teeth Restorations in Prosthetic Dentistry-A Literature Review

Simple Summary

In the last decades, the science and technology of all-ceramic teeth restorations witnessed the fastest-growing field of restorative materials in research and development for fixed prosthodontics. Due to their properties, characterized by a high level of biocompatibility, excellent optical properties, and high fracture resistance, all-ceramic material can also be used in the posterior areas of the dental arches. However, metal-ceramic fixed partial dentures are still perceived as the golden standard for those restorations, thanks to the positive clinical outcomes. Irrespective of the materials of which fixed partial dentures are performed, their success rates depend on the expected outcome and on how they perform in the oral environment. Such conditions of failure restorations may include biological factors (i.e., secondary decay, loss of vitality, periodontal disease, or abutment fracture) or technical factors (i.e., chipping, ceramic fracture, framework fracture, or loss of retention). Our aim is to provide the current evidence for the efficacy of metal-ceramics and all-ceramics in the treatment of multiple posterior edentulous spaces. Moreover, we aim to compare the survival rates of metal-ceramic and all-ceramic fixed partial dentures in terms of functionality and biocompatibility in all the aforementioned clinical situations. Our results have shown that all all-ceramic systems, especially densely sintered zirconia and reinforced glass ceramics, have a promising future to satisfy both practitioners and patients. However, technical and biological complications need to be taken into account when planning multi-unit fixed partial dentures for the posterior areas.

Abstract

The metal-ceramic fixed partial prosthesis is the golden standard for posterior tooth restorations. Following the demands of patients and clinicians for metal-free restorations, all-ceramic materials were developed as they offer an adequate alternative with better optical qualities and good mechanical properties. This study aims to carry out a bibliographic review to assess the survival rate and the biological and technical complications of all-ceramic and metal-ceramic fixed partial dentures. An electronic search for articles in the English language literature was performed using PubMed (MEDLINE). This literature review focused on research studies between 2010 and 2020 that performed clinical studies on tooth-supported fixed partial dentures with a mean follow-up of at least 3 years. All the studies, which analyzed the survival and complications of tooth-supported fixed partial dentures, were included. Thus, 14 studies reporting on 756 all-ceramic and 160 metal-ceramic fixed partial dentures met the inclusion criteria. A comparative analysis was carried out based on all the data existing in the studies included in this review. The metal-ceramic fixed partial dentures showed survival rates of 95% to 100% at 3-, 5-, and 10-year follow-up periods. Zirconia fixed partial dentures were reported to have survival rates of 81% to 100% at 3-, 5-, 9-, 10-year follow-up evaluations. The reinforced glass-ceramic fixed partial dentures showed survival rates of 70% to 93.35% at 5 years, while the alumina FPDs showed a survival rate of 68% at 3 years follow-up. The incidence of caries and loss of vitality were reported as higher for all-ceramic prostheses as compared to the metal-ceramic ones. A significant framework fracture was reported for glass-infiltrated alumina fixed partial dentures in comparison to metal-ceramic fixed partial dentures. All-ceramic and metal-ceramic restorations showed similar survival rates after 3 years, although all-ceramic restorations have problems with technical complications such as chipping, which can lead to framework fractures over time.

The perception of smile attractiveness to altered vertical position of maxillary anteriors by various groups

There is a gap in research about the differences in smile attractiveness. The problem the study addresses is how the vertical canine and incisor position affect smile attractiveness. The aim of this study was to assess the perception of the smile attractiveness between Saudi laypersons, orthodontists, non-orthodontist, and various dental students levels, and to determine how the canine and incisor vertical positions affect the attractiveness of smile. The study is a cross-sectional survey and was conducted at King Abdulaziz University, Jeddah, Saudi Arabia. Six groups of subjects participated in the study: Orthodontic residents (n = 31), prosthodontic, restorative, periodontics specialties residents specialties residents (n = 30), interns (n = 31), fifth year students (n = 41), 6th year students (n = 39), and laypeople (n = 39). Participants were asked to rate the attractiveness of a smile of a female subject photographed using a Minolta DiMage 7i digital camera. The image had been manipulated to produce 2 sets of images; 1 to modify the incisors and 1 to change the canines. The subjects were asked to choose the most and least attractive picture. For the best incisor positions, only the laypeople and prosthodontics liked the original picture, the rest liked +0.5 mm which accentuate the smile curve and make it follow the lower lip line. For the worst incisor position, all groups did not prefer the minus 1.5 reversed smile. For the best canine vertical position, all groups preferred the original position where canine was at the level of the incisal plane. For the worst canine position, they all disliked the minus 1.5 reversed smile. Results confirmed past findings that orthodontists are in general more critical about smile attractiveness than laypersons, but just like other dental specialists. The findings can be used in the esthetic dentistry field, but further research on the study population based on other dental design parameters remain necessary.

Metal-ceramic and porcelain-veneered lithium disilicate crowns: a stress profile comparison using a viscoelastic finite element model

Metal-ceramics (MC) are one of the oldest dental restorative systems, which are considered to be the gold standard for full crown restoration. Porcelain-veneered lithium disilicate (PVLD), on the other hand, are newer material systems that have shown high survival rate in clinical follow-ups but needs to be studied more. This study compares the stresses developed in the single crowns made from newer PVLD system against those with MC configuration. For this comparison, influence of the layer thickness and cooling rates is also taken into consideration. An experimentally validated viscoelastic finite element model (VFEM) has been developed to predict the stress profile in these systems. Three-dimensional rotationally symmetric crowns were analyzed using this validated model for both material systems, three veneer to core thickness ratios (2:1, 1:1, 1:2), and two cooling rates: slow cooling at 1.74E-5 W/mm2K (∼30 K/min) and fast cooling at 1.74E-4 W/mm2K (∼300 K/min). PVLD showed lower values of transient and residual stresses than MC. The maximum tensile residual stresses in MC systems were observed in the cusp area, whereas those in PVLD were located in the central fossa. With the reduction in veneer layer, there was reduction in residual stress in MC; however, the veneer thickness had little to no effect in PVLD. The effect of cooling rate was also evident as slow cooling resulted in lower residual and tensile stresses for both material systems.

In Vitro Fatigue and Fracture Load of Monolithic Ceramic Crowns Supported by Hybrid Abutment

Objective:

This study evaluated the performance of zirconia and lithium disilicate crowns supported by implants or cemented to epoxy resin dies.

Methods:

Eigthy zirconia and lithium disilicate crowns each were prepared and assigned in four groups according to the crown material and supporting structure combinations (implant-supported zirconia, die-supported zirconia, implant-supported lithium disilicate, and die-supported lithium disilicate). Ten crowns in each group acted as control while the rest (n=10) underwent thermocycling and fatigue with 100 N loading force for 1.5 million cycles. Specimens were then loaded to fracture in a universal testing machine. Data were analysed using one-way ANOVA and Tukey multiple comparison test with a 95% level of significance.

Results:

No implants or crown failure occurred during fatigue. The mean fracture load values (control, fatigued) in newton were as follows: (4054, 3344) for implant-supported zirconia, (3783, 3477) for die-supported zirconia, (2506, 2207) for implant-supported lithium disilicate, and (2159, 1806) for die-supported lithium disilicate. Comparing the control with the corresponding fatigued subgroup showed a significantly higher fracture load mean of the control group in all cases. Zirconia showed a significantly higher fracture load mean than lithium disilicate (P=0.001, P<0.001). However, comparing crowns made from the same material according to the supporting structure showed no significant difference (P=0.923, P=0.337).

Conclusion:

Zirconia and lithium disilicate posterior crowns have adequate fatigue and fracture resistance required for posterior crowns. However, when heavy fatigue forces are expected, zirconia material is preferable over lithium disilicate. Zirconia and lithium disilicate implant-supported crowns cemented to hybrid abutments should have satisfactory clinical performance.

Clinical Evaluation of Reduced-Thickness Monolithic Lithium-Disilicate Crowns: One-Year Follow-Up Results

Purpose: The purpose of this in vivo study was to investigate whether the less invasive approach (reduced thickness of the restoration) will result in a comparable risk of failure and similar aesthetic results, compared to conventional layered full porcelain crowns, and can, therefore, be used as a good alternative. Material and Methods: The tested ceramic was lithium-disilicate ceramic (IPS e.max). Forty-four patients with endodontically treated premolars or molars were randomized into two groups and provided with single crowns. One group received conventional all-ceramic crowns made from a lithium-disilicate core and hand-veneered aesthetic ceramic, while another group received full-contoured lithium-disilicate ceramic crowns with reduced wall thickness than manufactures recommendations. The teeth for conventional crowns were prepared with 1 mm rounded shoulder and 2 mm occlusal reduction, while teeth for monolithic crowns were prepared with 0.6 mm wide rounded shoulder and 1 mm occlusal reduction. All crowns were prepared by the same clinician and manufactured in the same laboratory by the same technician. The survival and aesthetics of the crowns were assessed by the independent clinician. Apart from this, patients’ aesthetic satisfaction was evaluated. The assessment was double blind as both the examiner and the patients did not know which type of crown was provided. The observation period was 36 months. Survival of the crowns was assessed using the modified United States Public Health Service (USPHS) criteria and aesthetics and participants’ aesthetic satisfaction with the crowns was evaluated using a visual analogue scale. Results: The one-year survival rate for layered crowns was 100% and for monolithic crowns 95.5%. The median patients’ aesthetic satisfaction with both crowns was 100%. Conclusions: The results indicate similar one-year survival rate of reduced-thickness monolithic lithium-disilicate crowns and conventional veneered crowns. Differences with patients’ satisfaction with the aesthetics of both crowns were not statistically significant and it can be said that the patients’ aesthetic satisfaction was the same for both crowns.

The PGO concept: Prosthetically guided orthodontics concept

OBJECTIVE

The aim of this case report is to present a novel digital approach of guiding orthodontics and periodontal surgery by creating interim restorations that represent the final shape of the teeth before starting the treatment.

CLINICAL CONSIDERATIONS

The patient presented with worn dentition, super-erupted maxillary and mandibular anterior teeth, and altered passive eruption, all this creating a gummy smile. Following a digital wax-up design, a digital orthodontic set-up, and the digital bracket bonding, temporary restorations, and bracket indirect bonding trays were fabricated. Restorations' cementation, bracket bonding, and periodontal surgery were performed the same day. After 14 months of orthodontic treatment, teeth were restored with final ceramic restorations. One year and 6 months was the total treatment duration.

CONCLUSION

Prosthetically guided orthodontic concept allows the use of digital technology to simulate the final outcome of the patient treatment before starting dental therapy. This technique not only improves the communication between specialists, it also reduces treatment time and increases precision and predictability.

CLINICAL SIGNIFICANCE

The prosthetically guided orthodontics (PGO) concept has the goal to start interdisciplinary therapy with a simulation of the final outcome. Giving the worn teeth their proper size through interim restorations prior to orthodontic therapy will guide the orthodontist from the beginning of the treatment and will improve communications between all the specialists. Through a digital approach, a digital wax-up and an orthodontic digital set-up the objectives of treatment can be established early on.

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

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2020 professional literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to this work to cover this broad topic. Specific subject areas addressed include prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders (TMDs); sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence day-to-day dental treatment decisions with a keen eye on future trends in the profession. With the tremendous volume of dentistry and related literature being published today, this review cannot possibly be comprehensive. The purpose is to update interested readers and provide important resource material for those interested in pursuing greater detail. It remains our intent to assist colleagues in navigating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the dental patients they encounter.

Residual stresses explaining clinical fractures of bilayer zirconia and lithium disilicate crowns: A VFEM study

OBJECTIVE

To understand the stress development in porcelain-veneered zirconia (PVZ) and porcelain-veneered lithium disilicate (PVLD) crowns with different veneer/core thickness ratios and cooling rates. To provide design guidelines for better performing bilayer restorations with the aid of Viscoelastic Finite Element Method (VFEM).

METHODS

The VFEM was validated by comparing the predicted residual stresses with experimental measurements. Then, the model was used to predict transient and residual stresses in the two bilayer systems. Models with two different veneer/core thickness ratios were prepared (2:1 and 1:1) and two cooling protocols were simulated (Fast: ∼300 °C/min, Slow: ∼30 °C/min) using the heat transfer module, followed by stress analysis in ABAQUS. The physical properties of zirconia, lithium disilicate, and the porcelains used for the simulations were determined as a function of temperature.

RESULTS

PVLD showed lower residual stresses than PVZ. The maximum tensile stresses in PVZ were observed in the cusp area, whereas those in PVLD were located in the central fossa. The 1:1 thickness ratio decreased stresses in both layers of PVZ. Slow cooling slightly decreased residual stresses in both systems. However, the cooling rate effect was more evident in transient stresses.

SIGNIFICANCE

Slow cooling is preferable for both systems. A thinner porcelain layer over zirconia lowers stresses throughout the restoration. The different stress distributions between PVZ and PVLD may affect their failure modes. Smaller mismatches in modulus, CTE, and specific heat between the constituents, and the use of low T_g porcelains can effectively reduce the deleterious transient and residual tensile stresses in bilayer restorations.

Comprehensive Management of Severe Dental Fluorosis with Adhesively Bonded All-Ceramic Restorations

Dental fluorosis is a common disorder caused by excessive fluoride intake during tooth development. The esthetic consequences of dental fluorosis can negatively affect oral health-related quality of life and have lasting psychosocial effects. In severe cases, where the fluorosed enamel is prone to chipping, flaking, and developing caries, minimally invasive procedures are ineffectual and a more substantial restorative approach is required to restore optimal function and esthetics. However, no definitive guidelines exist for the management and treatment of severe dental fluorosis due to the limited evidence available in the literature. This case report describes the full-mouth rehabilitation of a patient with severe dental fluorosis utilizing adhesively bonded all-ceramic crowns, veneers, and overlays. The successful follow-up on this case indicates that adhesively bonded restorations may provide a viable option in the functional and esthetic management of severely fluorosed dentition.

Clinical Evaluation of Resin Composite CAD/CAM Restorations Placed by Undergraduate Students

To evaluate the clinical outcomes of resin composite CAD/CAM restorations in a prospective cohort study, and to assess patient and operator satisfaction after restoration placement, 59 indirect resin composite were placed by supervised undergraduate students, of which 43 restorations were followed over a mean period of 28 months (14–44 months) and evaluated using USPHS criteria. Patient and operator satisfaction levels were assessed using a visual analogue scale (VAS) after restoration placement. A total of 37 patients and 47 restorations were included for further study. Four teeth were extracted—three due to extensive drug-induced secondary caries in the same patient, and one tooth due to large periapical periodontitis after 44 months of service. The overall survival rate was 91.4%, and success rate was 87.2%. Differences between baseline and endpoint scores were significant for marginal discoloration (p < 0.05) and adaptation (p < 0.001). Color match (p < 0.05) and surface texture (p < 0.001) differed significantly, affecting all restoration types. VAS scores for patient and operator satisfaction showed a significant rank correlation (p < 0.01), and pairwise comparison showed significant differences for mean overall patient and operator VAS scores (p < 0.001). Lava Ultimate CAD/CAM may be considered a suitable material for overlays and endocrown restorations when combined with IDS, air abrasion, and MDP-containing adhesive systems. Marginal disintegration may present in inlays and onlays over time.

Comparison of Fracture Resistance for Chairside CAD/CAM Lithium Disilicate Crowns and Overlays with Different Designs

PURPOSE

To determine the fracture resistance of chairside computer-aided design and computer-assisted manufacturing (CAD/CAM) lithium disilicate full coverage crowns and two different designs of overlay restorations for premolars.

MATERIALS AND METHODS

CAD/CAM lithium disilicate (IPS e.max CAD for CEREC/HT A1 C14, Ivoclar Vivadent) restorations (15 specimens/group) with 1.5 mm occlusal thickness and 1.0 mm chamfer were designed and fabricated with a chairside CAD/CAM system (CEREC, Dentsply Sirona). The restorations were prepared in three different designs: (1) full coverage crowns, (2) overlays with the margin located 2 mm above the gingiva, and (3) overlays with the margin located 4 mm above the gingiva. Restorations were cemented using conventional resin luting cement (Multilink, Ivoclar Vivadent) with primer system (Monobond Plus, Ivoclar Vivadent) to resin printed dies, load cycled (2,000,000 load cycles at 1 Hz with 275 N force), and then finally loaded with a steel indenter until failure. Scanning electron microscopy observations of fractured surfaces were also conducted. Group results were analyzed with one-way analysis of variance, and the medians were evaluated independently with Kruskal-Wallis.

RESULTS

The fracture force of CAD/CAM lithium disilicate restorations was significantly different (p < 0.001) depending on the design of the restoration. Full coverage crowns showed significantly higher force to fracture (1018.8 N) than both types of overlays (p = 0.002 for overlay 2.0 mm and p < 0.001 for overlay 4.0 mm above gingiva). Among the two overlays, the restoration with the margin located 2 mm above the gingiva showed significantly higher fracture force (813.8 N) than the overlay with margin at 4 mm above the gingiva (436.1 N; p < 0.001). The fracture appearance of the crowns was much more complex than that of the overlay restorations.

CONCLUSIONS

Full coverage chairside CAD/CAM lithium disilicate premolar crown showed higher fracture resistance than overlay restorations. Overlays with the margin located 2 mm above the margin demonstrated higher resistance than those with the margin located 4 mm above the gingiva.

Clinical Performance of CAD/CAM All-Ceramic Tooth-Supported Fixed Dental Prostheses: A Systematic Review and Meta-Analysis

Although CAD/CAM ceramics present a promising alternative to metal-ceramic fixed dental prostheses, little is known about their mid- and long-term clinical performance. This systematic review aims to estimate the survival and success rates and describes the underlying complication characteristics for CAD/CAM tooth-supported zirconia- and lithium disilicate-based fixed dental prostheses (FDPs). We systematically searched MEDLINE and Web of Science to find relevant prospective studies with a follow-up of at least one year. We estimated pooled 1-, 5-, and 10-year survival and success rates by combining the collected data in a Poisson regression model. Descriptive statistics were conducted to evaluate the distribution of failures and complications in the included studies. Risk of bias for the included studies was assessed with an adapted checklist for single-arm trials. Pooled estimated 1-, 5-, and 10-year survival rates ranged from 93.80% to 94.66%, 89.67% to 91.1%, and 79.33% to 82.20%, respectively. The corresponding success rates excluding failures, but including any other types of intervention were 94.53% to 96.77%, 90.89% to 94.62%, and 81.78% to 89.25%. Secondary caries was the most frequent cause of failure, followed by chipping of the veneering. The most common cause of complication excluding failures but requiring intervention was chipping of the veneering. Risk of bias was generally acceptable for the included studies, with seven studies associated with low risk of bias, eight studies with a moderate risk of bias, and three studies with serious risk of bias. The current meta-analysis on CAD/CAM-supported FDPs revealed satisfying survival and success rates for up to 10 years of exposure. More prospective studies focusing on long-term performance are needed to strengthen the evidence currently available in the literature.

Survey of clinically used adhesive ceramic bonding methods - follow up after 12 years

OBJECTIVES

This survey evaluated dentists' use of adhesive bonding methods of all-ceramic restorations over a period of twelve years. This is a follow-up survey which had been undertaken in 2007, 2011, and in 2015 [1].

METHODS

A multiple choice questionnaire regarding adhesive bonding methods for all-ceramic restoration was developed and handed out in 2007 and 2019 to dentist participating in a local annual dental meeting in Northern Germany. The questionnaires were evaluated on the basis of evidence-based techniques from the scientific literature.

RESULTS

Data from 93 questionnaires (2019) were compared with 90 evaluated questionnaires from 2007. Bonding of oxide ceramic had improved over the years of observation (7% to 62%) whereas evidence-based bonding of silicate ceramic restorations decreased from 66% to 38%; common mistakes were using air abrasion on silicate surface. Females showed better values for correct adhesive cementation than males (f: 39-50%, m: 22%-41%). A correlation between correct cementation and years of professional experience could not be revealed.

CONCLUSION

Incorrect bonding of oxide ceramic restorations decreased within the 12 years investigated whereas there was no improvement of evidence-based bonding procedures of silicate ceramics. Still a high number of survey participants need additional training in bonding techniques.

10.9-year survival of pressed acid etched monolithic e.max lithium disilicate glass-ceramic partial coverage restorations: Performance and outcomes as a function of tooth position, age, sex, and the type of partial coverage restoration (inlay or onlay)

STATEMENT OF PROBLEM

Long-term clinical data on the survival of pressed lithium disilicate glass-ceramic when used with partial coverage restorations and the effect that different technical and clinical variables have on survival are sparse.

PURPOSE

The purpose of this clinical study was to determine the 10.9-year survival of pressed lithium disilicate glass-ceramic partial coverage restorations and associated clinical parameters on outcomes.

MATERIAL AND METHODS

Individuals requiring single unit defect-specific partial coverage restorations in any area of the mouth were recruited in a clinical private practice. Participants were offered the options of partial coverage cast gold or glass-ceramic (lithium disilicate) restorations. Only participants that chose glass-ceramic partial coverage restorations were included in the study. The overall survival of the glass-ceramic restorations was assessed by the clinical factors (participant's age, sex, dental arch, tooth position in dental arch, type of partial coverage restoration, and ceramic thickness) determined at recall. The effect of this clinical parameters was evaluated by using Kaplan-Meier survival curves accounting for attrition bias and other reasons for failure. The statistical significance of differences between parameters was determined by using the log rank test (α=.05).

RESULTS

A total of 304 participants requiring 556 lithium disilicate restorations were evaluated. The mean age for the participant at the time of restoration placement was 62 with a range of 20 to 99 years, 120 were men and 184 were women. A total of 6 failures (bulk fracture or large chip) requiring replacement were recorded with the average time to failure of 2.4 (0.8-9.2) years. The total time at risk computed for these units was 1978.9 years providing an estimated failure risk of 0.3% per year. The 10-year estimated cumulative survival was 95.6%. The estimated cumulative survival of inlays (n=246) and onlays (n=305) were 93.9% and 98.3%, at 9.9 and 9.8 years, respectively (P<.05). Of the 6, there were 3 failures recorded for the partial coverage inlay restorations. The total time at risk for these inlays was 786.79 years providing an estimated risk of 0.38% per year. The other 3 failures recorded occurred for the partial coverage onlay restorations. The total time at risk for the onlays was 1032.17 years providing an estimated risk of 0.29% per year. The failures occurred in the molar region only. There were no failures recorded for the anterior partial coverage inlays (n=5). The total time at risk computed for the anterior units was 21.55 years providing an estimated risk of 0% per year. There was no statistically significant difference in the survival of partial coverage restorations among men and women, different age groups, or position in the dental arch. The thickness of the restoration had no influence on the survival of glass-ceramic partial coverage restorations.

CONCLUSIONS

Pressed lithium disilicate defect-specific partial coverage restorations reported high survival rate over the 10.9-year period with an overall failure rate of 0.3% per year and limited to the molar teeth. Risk of failure at any age was minimal for both men and women.

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.

Current status and research trends of lithium disilicate in dentistry: A bibliometric analysis

STATEMENT OF PROBLEM

Lithium disilicate (LD) is a popular dental ceramic and has been a focus of dental research. Nevertheless, a quantified literature analysis focusing on the research of lithium disilicate is lacking.

PURPOSE

The purpose of this bibliometric analysis was to review the progress of research into lithium disilicate in dentistry, including the identification of contributing researchers, organizations, countries or regions, journals, and the analysis of high-impact keywords and research trending.

MATERIAL AND METHODS

The search was carried out within the topic field of the Web of Science (WoS) database, collecting publications related to LD from between 1996 and 2019. Metadata including the titles, abstracts, keywords, authors, affiliations, countries or regions, and references were extracted. Bibliometric indicators in terms of documents, authors, journals, and keywords were analyzed.

RESULTS

Between 1996 and 2019, the dental research on LD trended upward. Scholars in the United States, Germany, Switzerland, and Brazil actively participated in the research on LD, and publications from the United States had the most citations. The Journal of Prosthetic Dentistry and Dental Materials were the major contributing journals. High-impact terms could be categorized into types of restorative material, types of prostheses, and properties or techniques of materials. Co-occurrence and relative normalized citation analysis of keywords highlighted several research interests, such as comparison studies between LD and zirconia, computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, and the performance of complete coverage LD restorations.

CONCLUSIONS

With the global upsurge in research on lithium disilicate, extensive collaborations and citations have been noted among authors, institutions, and countries or regions. Research hotspots include types of restorative material, types of prostheses, and properties or techniques of materials.

Survival of Cast Gold and Ceramic Onlays Placed in a School of Dentistry: A Retrospective Study

PURPOSE

This study was done to compare the survival rates of cast gold and ceramic onlays placed in a dental school setting.

MATERIAL AND METHODS

An electronic search was conducted in the patient records at Adams School of Dentistry, University of North Carolina at Chapel Hill for onlay codes that were in the database (From 1998 until 2018). Progress notes and radiographs were scrutinized to establish the survival time of the restorations. Any complications that occurred during the life time of the restorations were noted. The survival was summarized by categorization based on ranges of survival time in years; group 1: 1 to 5 years, group 2: 6 to 22 years. The mean survival time and standard deviation were calculated. One-way ANOVA was used to determine whether there was a statistically significant difference in the survival times between gold and ceramic onlays.

RESULTS

The mean survival rate of cast gold onlays (86.6%) was comparable to that of ceramic onlays (81.1%). The gold onlays in Group 1 had a higher mean survival time (2.43 years) than the ceramic onlays (2.03 years). This difference was statistically significant (p = 0.002). The ceramic onlays in Group 2 had a mean survival time of 19.75 years while gold onlays had a mean survival time of 17.63 years. This difference was not statistically significant (p = 0.91).

CONCLUSION

It was concluded that while the survival rate of ceramic onlays (81.1%) was inferior to that of cast gold onlays (86.6%), it was comparable.

Prospective clinical evaluation of 765 partial glass-ceramic posterior restorations luted using photo-polymerized resin composite in conjunction with immediate dentin sealing

Objectives

To evaluate the clinical performance of partial glass-ceramic (IPS e.max Press) posterior restorations.

Materials and methods

A total of 765 restorations in 158 patients were placed between 2008 and 2018 and evaluated in a prospective study during regular dental care visits between 2015 and 2018. The restorations were luted with a conventional photo-polymerized resin composite (HFO) in conjunction with an Immediate Dentin Sealing procedure (IDS). Intra-oral photographs and radiographs were made and evaluated using USPHS criteria.

Results

The mean observation time was 53.3 months (range 3–113 months). Three absolute failures occurred (tooth fractures, n = 2; apical re-infection, n = 1) all leading to the loss of the restored tooth. Repairable and salvageable failures occurred in 9 teeth (endodontic complications, n = 7; secondary caries, n = 1; debonding, n = 1). The survival and success rates according to Kaplan-Meier after 5 years cumulated to 99.6% and 98.6%, respectively. Location (premolar/molar and mandibula/maxilla), pre-restorative endodontic status (vital/devitalised) and extension of the indirect ceramic restoration (number of sides and cusps involved) did not significantly affect the cumulative success rate (log rank test, p > 0.05). The condition of the vast majority of the restorations remained unaffected for 5 years.

Conclusions

Partial glass-ceramic posterior restorations (pressed lithium disilicate (IPS e.max press, Ivoclar Vivadent) luted by means of a conventional photo-polymerized resin composite in conjunction with the use of an IDS procedure have an excellent medium-term prognosis.

Clinical relevance

Partial glass-ceramic posterior restorations can be considered as a highly reliable treatment option. Location and extension of the restoration and pre-restorative endodontic status do not affect success rate.

Fatigue performance of adhesively luted glass or polycrystalline CAD-CAM monolithic crowns

STATEMENT OF PROBLEM

Data comparing the fatigue performance of adhesively luted glass or polycrystalline ceramic systems for computer-aided design and computer-aided manufacturing (CAD-CAM) are scarce.

PURPOSE

The purpose of this in vitro study was to evaluate and compare the fatigue performance of monolithic crowns manufactured from glass or polycrystalline CAD-CAM ceramic systems adhesively luted to a dentin analog.

MATERIALS AND METHODS

Fifty-four pairs of standardized preparations of dentin analog (NEMA Grade G10) and simplified ceramic crowns of 1.5-mm thickness were obtained with 3 ceramic materials: lithium disilicate (LD) glass-ceramic (IPS e.max CAD); zirconia-reinforced lithium silicate (ZLS) glass-ceramic (Vita Suprinity); and translucent yttrium fully stabilized polycrystalline zirconia (Trans YZ) (Prettau Anterior). The simplified crowns (n=15) were adhesively cemented onto the preparations and subjected to step-stress fatigue test (initial load of 400 N, 20 Hz, 10 000 cycles, followed by 100-N increment steps until failure). Collected data (fatigue failure load [FFL] and cycles for failure [CFF]) were submitted to survival analysis with the Kaplan-Meier and Mantel-Cox post hoc tests (α=.05) and to Weibull analysis (Weibull modulus and its respective 95% confidence interval). Failed crowns were submitted to fractography analysis. The surface characteristics of the internal surface (roughness, fractal dimension) of additional crowns were accessed, and the occlusal cement thickness obtained in each luted system was measured.

RESULTS

Trans YZ crowns presented the highest values of FFL, CFF, and survival rates, followed by ZLS and LD (mean FFL: 1740 N>1187 N>987 N; mean CFF: 149 000>92 613>73 667). Weibull modulus and cement thickness were similar for all tested materials. LD presented the roughest internal surface, followed by ZLS (mean Ra: 226 nm>169 nm>93 nm). The LD and ZLS internal surfaces also showed higher fractal dimension, pointing to a more complex surface topography (mean fractal dimension: 2.242=2.238>2.147).

CONCLUSIONS

CAD-CAM monolithic crowns of Trans YZ show the best fatigue performance. In addition, ZLS crowns also showed better performance than LD crowns.

Future of dental biomaterials: Gazing into Bob's crystal ball

In February 2019, the American Prosthodontics Society asked me to "ponder" the future of dental biomaterials. This talk was titled, "Gazing Into Bob's Crystal Ball". My basic approach was guided by the words of Confucius, "Study the past if you would define the future." As I have often studied and lectured on how many of our important materials got into dentistry, it was a natural assignment. In this article, I review how key materials came to be used in dental practice and organize these "sources" into an extended classification, assuming future materials will likely derive from one of these. Then, I identify important examples in each category and then expound on likely future developments, some already in progress. These include increasing the use of and benefiting from automated systems; better engineering with existing materials by means of failure analysis (from clinically retrieved specimens); iterative improvements in materials and practices, again based on observations from clinical behavior; the use of scaffolds for both hard- and soft-tissue repair; and the development of "smart" materials. I hope this contribution survives the test of time. Please note that, importantly, this list includes not just materials but often-overlooked steps in processing that will affect their properties and clinical durability.

A pilot trial on lithium disilicate partial crowns using a novel prosthodontic functional index for teeth (FIT)

Background

Lithium disilicate is now a well accepted material for indirect restorations. The aim of this trial was to evaluate two lithium disilicate systems using a novel prosthodontic Functional Index for Teeth (FIT).

Methods

Partial adhesive crowns on natural abutment posterior teeth were made on sixty patients. Patients were divided into two groups: Group 1 IPS e.max press (Ivoclar-Vivadent, Schaan, Liecthestein), and Group 2 Initial LiSi press (GC Co., Tokyo, Japan). The restorations were followed-up for 3 years, and the FIT evaluation was performed at last recall. The FIT is composed of seven variables (Interproximal, Occlusion, Design, Mucosa, Bone, Biology and Margins), each of them are evaluated using a 0–1-2 scoring scheme, and is investigated by an oral radiograph and occlusal and buccal pictures. More in details, three variables have the three scores made on the presence or not of major, minor or no discrepancy (for ‘Interproximal’, ‘Occlusion’ and ‘Design’), presence or not of keratinized and attached gingiva (‘Mucosa’), presence of bone loss > 1.5 mm, < 1.5 mm or not detectable (‘Bone’), presence or not of Bleeding on Probing and or Plaque Index (‘Biology’), presence of detectable gap and marginal stain or not (‘Margins’). The Mann-Whitney ‘U’ test was used and the level of significance was set at p < 0.05. Also, “success” of the crowns (restoration in place without any biological or technical complication) and “survival” (restoration still in place with biological or technical complication) were evaluated.

Results

Regarding FIT scores, all partial crowns showed a stable level of the alveolar crest without detectable signs of bone loss in the radiographic analysis. All other evaluated parameters showed a high score, between 1.73 and 2. No statistically significant difference emerged between the two groups in any of the assessed variables (p > 0.05). All FIT scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired and the success rate was 100%.

Conclusions

The results showed that it is possible to evaluate the clinical performance of partial crowns using FIT. The FIT proved to be an effective tool to monitor the performance of the restorations and their compatibility with periodontal tissues at the recall. The FIT can be really helpful for a standardized evaluation of the quality of the therapy in prosthodontic dentistry. The two lithium disilicate materials showed similar results after 3 years of clinical service.

Trial registration

The study protocol was approved by the Ethical Committee of University of Siena (clinicaltrial.gov # NCT 01835821), ‘retrospectively registered’.