A randomized controlled clinical trial on press and block lithium disilicate partial crowns: A 4-year recall.

PURPOSE: To evaluate clinical performances of two lithium disilicate systems (Initial LiSi press vs Initial LiSi Block, GC Co.) using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after 4 years of clinical service. METHODS: Partial adhesive crowns on natural abutment posterior teeth were made on 60 subjects who were randomly divided into two groups: Group 1: Initial LiSi press and Group 2: Initial LiSi Block. Fabrication of partial crowns was made with full analog and digital procedure in Groups 1 and 2 respectively. The restorations were followed-up for 1 and 4 years, and the modified USPHS evaluation was performed at baseline and each recall together with periodontal evaluation. Contingency tables to assess for significant differences of success over time in each group and time-dependent Cox regression to test for differences between the two groups were used and the level of significance was set at P< 0.05. RESULTS: Regarding modified USPHS scores, all evaluated parameters showed Alpha or Bravo and no Charlie was recorded. No statistically significant difference emerged between the two groups in any of the assessed variables (P> 0.05). No statistically significant difference between scores recorded at the baseline and each recall. All modified USPHS scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired, and the survival rate was 100% after 4 years of clinical service. No difference was found between traditional and digital procedure to fabricate the crowns. The two lithium disilicate materials showed similar results after 4 years of clinical service. CLINICAL SIGNIFICANCE: The crowns made with the two tested lithium disilicate materials with analog and digital procedures showed 100% survival after 4 years of clinical service with no statistically significant difference using the modified USPHS scores.

Assessment of distortion of intraoral scans of edentulous mandibular arch made with a 2-step scanning strategy: A clinical study.

STATEMENT OF PROBLEM: Manufacturers of several intraoral scanners have recommended a 2-step strategy for scanning the edentulous mandible. The 2-step technique requires scanning one side first and then moving to the other side. However, whether inconsistency in stitching occurs that results in loss of accuracy or distortion is unclear. PURPOSE: The purpose of this clinical study was to measure the potential distortion of intraoral scans of edentulous mandibular arches made with a 2-step scanning strategy and to assess their differences with conventional impressions. MATERIAL AND METHODS: Twenty mandibular edentulous arches were scanned by 1 investigator with an intraoral scanner using a 2-step scanning strategy, and a corresponding polysulfide conventional impression was obtained. The conventional impression was then immediately scanned with the same intraoral scanner. The obtained standard tessellation language (STL) files were superimposed with a surface-matching software program. After a preliminary alignment, the STL meshes were trimmed and reoriented; then, the final alignment was carried out and meshes moved to a metrology software program where their mean distance was measured. In addition, a surface curve (SIOS) was traced on the intraoral scan from the right to left retromolar pad along the residual ridge and automatically projected onto to the conventional impression scan to obtain a new curve (SC). The mean distance between SIOS and SC was measured and recorded as an indicator of the distortion by considering the X-, Y-, and Z-axes and the overall 3-dimensional (3D) deviation. The analysis was performed for the full curve length and after dividing it into 6 regions of interest. Univariate and multivariate statistical analyses were used to investigate the significance of the extent of the mean 3D distance, as well as the effects of measurement positions (side and region) between and within patients on differences along the X-, Y-, and Z-axes (α=.05). RESULTS: The mean (-0.08 mm; standard error: 0.025) 3D distance between the intraoral scan and conventional impression was significantly different from zero (P=.003). No significant effect of the factor "side" was found by using generalized estimated equation models for the X-, Y-, and Z-axes, and global 3D deviations between SIOS and SC (P>.05), which appeared to exclude distortion. Conversely, a significant effect was found for the factor "region" (P<.05), with no significant differences (P>.05) between corresponding regions on the 2 sides. CONCLUSIONS: Intraoral scans of the edentulous mandibular arch made in a 2-step procedure did not exhibit significant distortion in comparison with conventional impressions.

A randomized controlled clinical trial of two types of lithium disilicate partial crowns.

PURPOSE: This randomized controlled clinical trial evaluated the behavior of lithium disilicate partial crowns by means of a novel Functional Index for Teeth (FIT). METHODS: 105 subjects in need of at least a single prosthetic restoration in posterior areas were treated with adhesive partial crowns (for a total of 170 restorations) onto natural vital abutment teeth and followed-up annually for 4 years. Subjects were randomly divided into two experimental groups: Group 1, e.max Press and Group 2, Initial LiSi Press. FIT was used for the objective assessment of outcomes including clinical and radiographic examinations. A dropout rate of 4.25% in Group 1 and 3.4% in Group 2 was recorded. FIT is made up of seven variables (interproximal, occlusion, design, mucosa, bone, biology and margins); each of them to be evaluated using a 0-1-2 score. The Mann-Whitney U test was applied for statistical analysis and the level of significance was set at P< 0.05. RESULTS: In Group 1, five complications were recorded, and four in Group 2, with a failure rate of 6.25% and 6.17%, respectively. No statistically significant difference was found between the experimental groups in any of the assessed variables. The tested lithium disilicate material brands showed comparable clinical performances after 4 years of clinical service. CLINICAL SIGNIFICANCE: Clinicians can use either of the tested lithium disilicate materials to make adhesively luted partial crowns.

Accuracy of a chairside intraoral scanner compared with a laboratory scanner for the completely edentulous maxilla: An in vitro 3-dimensional comparative analysis.

STATEMENT OF PROBLEM: Intraoral scanners are promising options for removable prosthodontics. However, analog aids, including occlusion rims, are still used, as a completely digital workflow is challenging and scientific evidence on the topic is scarce. PURPOSE: The purpose of this in vitro study was to assess and compare the trueness and precision of scans obtained from a reference typodont of a completely edentulous maxilla by using an intraoral scanner (TRIOS 3 Pod; 3Shape A/S) with scans obtained by using a laboratory scanner (DScan 3; EGS S.R.L.) from both Type IV stone casts and polysulfide impressions. MATERIAL AND METHODS: The polyurethane resin reference typodont was replicated from a clinical cast and was scanned with a metrological machine to obtain a reference scan. Ten digital casts were obtained by applying standardized scanning strategies to the reference typodont with the intraoral scanner. A device was created to make 10 consistent polysulfide impressions, and a scan of each impression was made with the laboratory scanner and then digitally reversed to obtain 10 digital reversed casts. Ten Type IV stone casts were poured and then scanned with the laboratory scanner to obtain 10 digital extraoral scanner casts. The scans in standard tessellation language (STL) format were imported into a dedicated software program, and the trueness and precision were calculated in µm. In addition to descriptive statistics (confidence interval 95%), 1-way ANOVA followed by the Bonferroni test or the Kruskal-Wallis and the Dunn tests were used to analyze differences among groups (α=.05). RESULTS: The trueness values (95% confidence interval) were digital intraoral scanner cast=48.7 (37.8-59.5), digital reversed cast=249.9 (121.3-378.5), and digital extraoral scanner cast=308.8 (186.6-430.9); significant differences were detected between digital intraoral scanner cast and digital reversed cast (P<.001) and between digital IOS casts and digital extraoral scanner cast (P<.001). The precision values (95% confidence interval) were digital intraoral scanner cast=46.7 (29.7-63.7), digital reversed cast=271.2 (94.6-447.8), and digital extraoral scanner cast=341.4 (175.5-507.3); significant differences were detected between digital intraoral scanner cast and digital reversed cast (P=.003) and between digital intraoral scanner cast and digital extraoral scanner cast (P=.001). CONCLUSIONS: Directly scanning a solid typodont of a completely edentulous maxilla with the intraoral scanner produced better trueness and precision than scanning the polysulfide impressions or the stone casts with a laboratory scanner.

Comparison of different intraoral scanning techniques on the completely edentulous maxilla: An in vitro 3-dimensional comparative analysis.

STATEMENT OF PROBLEM: Information about the accuracy of intraoral scanners for the edentulous maxilla is lacking. PURPOSE: The purpose of this in vitro study was to compare the accuracy of 3 different intraoral scanner techniques on a completely edentulous maxilla typodont. MATERIAL AND METHODS: Two completely edentulous maxillary typodonts with (wrinkled typodont) and without (smooth typodont) palatal rugae were used as reference and were scanned by using an industrial metrological machine to obtain 2 digital reference scans in standard tessellation language (STL) format (dWT and dST). Three different scanning techniques were investigated: in the buccopalatal technique, the buccal vestibule was scanned with a longitudinal movement ending on the palatal vault with a posteroanterior direction; the S-shaped technique was based on an alternate palatobuccal and buccopalatal scan along the ridge; in the palatobuccal technique, the palate was scanned with a circular movement and then with a longitudinal one along the buccal vestibule. Consecutively, 6 types of scans were obtained (n=10), namely wrinkled typodont/buccopalatal technique, wrinkled typodont/S-shaped technique, wrinkled typodont/palatobuccal technique (wrinkled typodont), smooth typodont/buccopalatal technique, smooth typodont/S-shaped technique, and smooth typodont/palatobuccal technique (smooth typodont). Scans in STL format were imported into a dedicated software program, and trueness and precision were evaluated in µm. In addition to descriptive statistics (95% confidence interval), a 2-factor ANOVA on the data ranks, the Kruskal-Wallis, and the Dunn tests were performed to analyze differences among groups (α=.05). RESULTS: Mean values for trueness (95% confidence interval) were wrinkled typodont/buccopalatal technique=48.7 (37.8-59.5); wrinkled typodont/S-shaped technique=65.9 (54.9-77.4); wrinkled typodont/palatobuccal technique=109.7 (96.1-123.4); smooth typodont/buccopalatal technique=48.1 (42.4-53.7); smooth typodont/S-shaped technique=56.4 (43.9-68.9); smooth typodont/palatobuccal technique=61.1 (53.3-69), with statistically significant differences for wrinkled typodont/buccopalatal technique versus wrinkled typodont/palatobuccal technique (P<.001), buccopalatal technique versus palatobuccal technique (P<.001), and wrinkled typodont versus smooth typodont (P=.002). Mean values for precision (95% confidence interval) were wrinkled typodont/buccopalatal technique=46.7 (29.7-63.7); wrinkled typodont/S-shaped technique=53.6 (37.6-69.7); wrinkled typodont/palatobuccal technique=90 (59.1-120.9); smooth typodont/buccopalatal technique=46 (39.7-52.3); smooth typodont/S-shaped technique=76 (55.5-96.6); smooth typodont/palatobuccal technique=52.9 (41.9-63.8); with statistically significant differences for buccopalatal technique versus palatobuccal technique (P=.032) and wrinkled typodont/buccopalatal technique versus wrinkled typodont/palatobuccal technique (P=.012). CONCLUSIONS: Smooth typodont scans showed better trueness than wrinkled typodont scans. Buccopalatal technique showed better mean values for trueness and precision than palatobuccal technique only in the wrinkled typodont scenario, while the other scanning approaches did not show significant differences in either tested configuration.

Current status on lithium disilicate and zirconia: a narrative review.

BACKGROUND: The introduction of the new generation of particle-filled and high strength ceramics, hybrid composites and technopolymers in the last decade has offered an extensive palette of dental materials broadening the clinical indications in fixed prosthodontics, in the light of minimally invasive dentistry dictates. Moreover, last years have seen a dramatic increase in the patients' demand for non-metallic materials, sometimes induced by metal-phobia or alleged allergies. Therefore, the attention of scientific research has been progressively focusing on such materials, particularly on lithium disilicate and zirconia, in order to shed light on properties, indications and limitations of the new protagonists of the prosthetic scene. METHODS: This article is aimed at providing a narrative review regarding the state-of-the-art in the field of these popular ceramic materials, as to their physical-chemical, mechanical and optical properties, as well as to the proper dental applications, by means of scientific literature analysis and with reference to the authors' clinical experience. RESULTS: A huge amount of data, sometimes conflicting, is available today. Both in vitro and in vivo studies pointed out the outstanding peculiarities of lithium disilicate and zirconia: unparalleled optical and esthetic properties, together with high biocompatibility, high mechanical resistance, reduced thickness and favorable wear behavior have been increasingly orientating the clinicians' choice toward such ceramics. CONCLUSIONS: The noticeable properties and versatility make lithium disilicate and zirconia materials of choice for modern prosthetic dentistry, requiring high esthetic and mechanical performances combined with a minimal invasive approach, so that the utilization of such metal-free ceramics has become more and more widespread over time.

Stress distribution of bulk-fill resin composite in class II restorations.

PURPOSE: To study the influence of the resin bonding layer thickness and the bulk filling material stiffness in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). METHODS: Four 3D-FE models of teeth restored with different filling material stiffness and resin bonding layer thickness were built-up and analyzed. The 3D model of a sound lower molar was also analyzed and compared with restored ones. The tooth tissues (enamel, dentin), dental restoration and bolus on the occlusal surface, was divided into 3D solid CTETRA elements with four grid points. The adhesive bonding around the dental restoration was modeled with shell elements. Polymerization shrinkage was simulated with a thermal expansion approach. Mechanical behavior of restored models in terms of stress and displacement distributions, under the combination effects of polymerization shrinkage and occlusal load (600 N), was analyzed. All the materials were assumed to behave as elastic materials throughout the entire deformation. RESULTS: Numerical results show that the mechanical response of the restored models was very different compared to the sound tooth ones, where the stress was uniformly distributed from enamel to dentin with no critical stress concentration. In the restored models, the highest stress values were detected in the enamel, near the enamel-dentin interface and in the bulk restorative material. Tooth preparations A and B showed lower gradient stresses than corresponding C and D. The value of the vertical displacement components in models A and B were higher than corresponding C and D. The maximum displacement values were mainly located around the groove and were higher by an order of magnitude than the sound models. The results showed better mechanical response with models A and B compared to C and D. It is also evident that resin bonding thickness slightly affected the stress level of the restored teeth. CLINICAL SIGNIFICANCE: Class II MOD direct bulk resin composite restorations showed a high susceptibility to damage at the marginal and internal tissue interfaces depending on their own stiffness. The use of resin-based bulk filling materials is not recommended for large class II MOD adhesive restorations due to mechanical behavior failure risk.

Complications of endodontically treated teeth restored with fiber posts and single crowns or fixed dental prostheses-a systematic review.

OBJECTIVE: The present systematic review aimed at assessing data from the literature on endodontic and prosthetic complications in endodontically treated teeth restored with fiber posts and single crowns (SCs) or fixed dental prostheses (FDPs). MATERIALS AND METHODS: Available randomized controlled clinical trials evaluating endodontic and prosthetic complications in the teeth treated with fiber posts and restored with different prosthetic restorations were reviewed. PubMed, Evidence-Based Dentistry, BMJ Clinical Evidence, Embase, DynaMed, and gray literature restricted to scientific literature were analyzed; also, manual researches were performed. English language and time filters (from 1990 to 2015) were used. RESULTS: The database search produced 4230 records, many of which were duplicates. The manual research did not produce any other relevant article. After duplications were removed, all the selected databases produced 3670 records. Reading titles and abstracts, two independent reviewers excluded 3664 reports. The full-texts of the remaining six reports were read. Only four studies met the inclusion criteria and were included in this systematic review. CONCLUSIONS: The most frequently reported failures in the available studies were as follows: fiber post debonding, loss of retention of single crowns, and marginal gaps. Less frequently, chippings and fractures were recorded in SCs. No studies about complications related to FDPs were found. CLINICAL RELEVANCE: A correlation between the failure rates of fiber posts and the type of prosthetic restorations just like SCs and FDPs cannot be found to date. Further randomized controlled clinical studies are required to achieve evidence-based conclusions, particularly about the use of fiber posts with FDPs.

Case-specific finite element analysis of dental CAD/CAM prostheses to identify design flaws prior to manufacture.

PURPOSE: To apply a design optimization strategy to dental prostheses machining to verify whether this approach can detect flaws occurring in the CAD process and to estimate the influence of the type of material on the occurrence of fractures in restorations. METHODS: The stereo lithography interface format of a 4-unit (from canine to first molar) fixed dental prosthesis designed by a conventional dental CAD process was converted into a Finite Element Analysis (FEA) model. This basic model was coupled to the mechanical properties of feldspathic ceramic, lithium disilicate ceramic (LS2) and zirconia (ZrO2) to create three FEA models with different mechanical properties. The models were constrained along the abutment housing surfaces of the canine and the first molar, respectively. Finally, a simulated load of 50 N was applied vertically to the occlusal surface of the first premolar. RESULTS: The FEA showed a stress peak concentration between the second connectors and the second premolar. The stress peak overcame the ultimate tensile stresses of feldspathic and lithium disilicate ceramics; conversely, the ultimate tensile stress of zirconia was not overcome. A geometrical flaw was identified in the 4-unit fixed dental prosthesis. The flaw was sensitive to tensional stress and could lead to failure of the component. CLINICAL SIGNIFICANCE: The results of the present investigation showed the importance and future impact of the application of FEA in the daily practice of prosthodontics. A FEA-implemented CAD process would allow proper prosthetic volumes with correct dimensions of the framework, in order to withstand occlusal loads and consequently reduce mechanical failures. FEA is a useful tool to simplify the design of prosthetic frameworks and select esthetic ceramic materials with strength enough to withstand occlusal stress.

Short-term clinical performance of zirconia single crowns with different framework designs: 3-year clinical trial.

PURPOSE: The present prospective clinical study evaluated the influence of coping design on the fracture resistance of CAD/CAM zirconia single crowns layered with dedicated ceramics. METHODS: 56 subjects were provided with 90 zirconia single crowns in posterior regions. Tooth preparations were standardized and the abutment teeth were randomly distributed into three groups, according to three different coping designs (flat design, FD; porcelain-fused-to-metal-like crowns, PFM; anatomically-guided, AG). The zirconia cores were produced using a CAD/CAM software and then were hand-layered with dedicated ceramics. All crowns were cemented with a self-adhesive resin luting agent and the patients were recalled for follow-up visits after 1 month, 6 months, 1, 2 and 3 years of clinical service. The function, esthetics and marginal adaptation of the restorations were evaluated. Statistical analyses were performed to evaluate survival and success of the restorations. RESULTS: Success rates of 100% were reported in Group 2 and Group 3 while the percentage was 80% in Group 1. Three chippings were noticed in Group 1 (FD) and two crowns needed to be replaced after 3 years, resulting in a survival rate of 93.3%. Group 2 and Group 3 had significantly higher 3-year success rates than Group 1 (P < 0.05). Based on the present clinical results, the following conclusions were drawn: the porcelain-fused-to-metal-like and the anatomically-guided frameworks for zirconia single crowns performed better clinically than the flat designed cores in posterior regions after 3 years; standardized tooth preparations achieved even thicknesses of the bilayered restorations; the proper support given to the veneering ceramic by the correct design of the zirconia framework could significantly reduce the risk of chipping during function.

Fracture Strength of Zirconia and Alumina Ceramic Crowns Supported by Implants.

Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns.

Effect of 2 impression techniques on the dimensional accuracy of working implant prosthesis models: an in vitro study.

PURPOSE: Implant impressions and working models form integrated precision systems for registration and transmission of clinical data. The components of implant systems have a dimensional tolerance capable of introducing inaccuracies in the impression, thus in the prosthetic framework. This article aimed at comparing 2 repositioning impression techniques: one using impression copings (conventional technique) and the other using the final abutments as impression copings (interceptive technique). MATERIALS AND METHODS: Two experimental models, one with 4 parallel implants and the other with 4 nonparallel implants, were used to make silicone impressions. Twenty impressions were made with the conventional technique, and a further 20 were made with the interceptive technique. Three-dimensional images acquired with a three-dimensional scanner were measured using a three-dimensional image analysis software, comparing models obtained from the impressions with the experimental models. Data were statistically analyzed by means of confidence intervals calculated with the mean (α = 0.05), descriptive (box plot), and bivariate analyses. RESULTS: Statistic analysis highlighted significant differences among models obtained using both techniques: the interceptive technique generated working models with less distortion and variability. CONCLUSIONS: For internal-connection implants, the interceptive technique provided significantly more precise working models than did the conventional technique.

A 13- to 17-year Retrospective Evaluation of the Clinical Performances of Anterior and Posterior Lithium Disilicate Restorations onto Teeth and Implants.

This retrospective study aimed at evaluating the clinical outcomes of lithium disilicate prostheses onto teeth and implants. A total of 860 restorations were delivered to 312 patients, including crowns, veneers and onlays. Patients with uncontrolled gingival inflammation and/or periodontitis were excluded, whilst subjects with occlusal parafunctions were included. The retrospective observational period ranged between 13 to 17 years. The mechanical and esthetic performances of the restorations were rated according to the modified CDA criteria. The recorded data were analyzed statistically. In total, 26 mechanical complications were noticed: 17 ceramic chippings, 5 core fractures and 4 losses of retention. Mechanical complications occurred predominantly in posterior areas; monolithic prostheses showed the lowest percentage of structural problems. The clinical scores of layered and monolithic restorations were fully satisfactory according to the modified CDA rating. The cumulative survival and success rates ranged between 95.46-100% and 93.75-100% respectively up to 17 years of follow-up. Although patient selection and the rigorous application of validated clinical protocols were considered paramount, the use of lithium disilicate prostheses onto teeth and implants was reported to be a viable and reliable treatment option in the long-term.

Trueness and precision of an intraoral scanner on abutments with subgingival vertical margins: An in vitro study.

OBJECTIVES: This study aimed to evaluate the accuracy of an intraoral scanner (IOS - Medit i700) on tooth abutments with vertical preparations at 2 depths below the free gingival margin, and to determine if the IOS can reproduce the area beyond the finish surface of the tested preparation geometry. METHODS: Two abutments for a maxillary first molar were designed by means of CAD software, with vertical preparations set at 1 and 2 mm below the gingiva. These abutments were subsequently printed in resin and placed on a reference model. The reference files consisted of scans made using a metrological machine on these abutments. Ten scans were made with the tested IOS on each sample, resulting in two study groups. The scans from the experimental groups were labeled "V-1″ for vertical preparation at 1 mm below the gingival margin and "V-2″ for 2 mm below. The analysis of these scans was performed using Geomagic Control X (3D SYSTEMS) to assess their trueness and precision in µm. Descriptive statistics with a 95 % confidence interval were employed, alongside independent sample tests, to ascertain any differences between the groups (α=0.05). RESULTS: Statistically significant differences were not found both for trueness (p=.104) and precision (p=.409), between the tested geometries. The mean values for trueness were V-1 = 37.5[31.4-43.6]; V-2 = 32.6[30.6-34.6]. About the precision, the mean values were V-1 = 20.5[8.4-32.5]; V-2 = 18.4[8.2-28.5]. In both the study groups, it was possible to detect the surface beyond the finish area. CONCLUSIONS: Within the limitations of this study, vertical preparation design allows for registration of the tooth anatomy beyond the finish area with IOS. Moreover, the mean accuracy values were clinically acceptable at both 1 and 2 mm below the gingival margin.

Clinical longevity of direct and indirect posterior resin composite restorations: An updated systematic review and meta-analysis.

OBJECTIVES: To answer the PICO(S) question: Is there a difference in clinical longevity between direct and indirect resin composite restorations placed on permanent posterior teeth? DATA: Randomized controlled clinical trials (RCTs) investigating direct and indirect resin composite restorations in posterior permanent teeth were considered. SOURCES: Several electronic databases were searched, with no language or date restrictions. The revised Cochrane Collaboration's tool for assessing risk of bias (RoB-2) was used to analyze the studies; meta-analyses were run and the certainty of evidence was assessed by the GRADE tool. A subgroup meta-analysis was performed for resin composite restorations placed on posterior worn dentition. STUDY SELECTION: Twenty-three articles were included in qualitative synthesis, while 8 studies were used for meta-analyses. According to the RoB-2 tool, 5 studies were ranked as "low risk", 7 had "some concerns", while 11 papers were rated as "high risk" of bias. There were no statistically significant differences in short-term (p = 0.27; RR=1.54, 95% CI [0.72, 3.33]), medium-term (p = 0.27; RR=1.87, 95% CI [0.61, 5.72]) and long-term longevity (p = 0.86; RR=0.95, 95% CI [0.57, 1.59]). The choice of restorative technique had no influence on short-term survival of resin composite restorations placed on worn dentition (p = 0.13; RR=0.46, 95% CI [0.17, 1.25]). The certainty of evidence was rated as "very low". CONCLUSIONS: Direct and indirect resin composite restorations may show similar clinical longevity in posterior region, regardless of the observation period or substrate (wear-affected and non-affected dentition). The very low quality of evidence suggests that more long-term RCTs are needed to confirm our results.

Five-year prospective clinical study of posterior three-unit zirconia-based fixed dental prostheses.

This prospective clinical trial aimed at evaluating the clinical performance of three-unit posterior zirconia fixed dental prostheses (FDPs) after 5 years of clinical function. Thirty-seven patients received 48 three-unit zirconia-based FDPs. The restorations replaced either a premolar or a molar. Specific inclusion criteria were needed. Tooth preparation was standardized. Computer-aided design/computer-assisted manufacturing frameworks with a 9-mm(2) cross section of the connector and a 0.6-mm minimum thickness of the retainer were made. The restorations were luted with resin cement. The patients were recalled after 1, 6, 12, 24, 36, 48, and 60 months. The survival and success of the ceramics and zirconia were evaluated. The technical and aesthetic outcomes were examined using the United States Public Health Service criteria. The biologic outcomes were analyzed at abutment and contralateral teeth. Descriptive statistics were performed. All FDPs completed the study, resulting in 100% cumulative survival rate and 91.9% and 95.4% cumulative success rates for patients wearing one and two FDPs, respectively. No losses of retention were recorded. Forty-two restorations were rated alpha in all measured parameters. A minor chipping of the ceramics was detected in three restorations. No significant differences between the periodontal parameters of the test and control teeth were observed. Five-year clinical results proved that three-unit posterior zirconia-based FDPs were successful in the medium term for both function and aesthetic. Zirconia can be considered a promising substitute of metal frameworks for the fabrication of short-span posterior prostheses.

Effect of the length of glass fiber posts on the fracture resistance of restored maxillary central incisors.

PURPOSE: To evaluate the influence of post length insertion on the fracture resistance of directly restored endodontically treated teeth. METHODS: 30 maxillary central incisors were restored with glass fiber posts and composite cores to produce groups with post lengths of (1) 5 mm, (2) 7 mm, and (3) 9 m. Specimens were loaded at 130 degrees (Instron). Fracture strengths were analyzed with the Kolmogorov-Smirnov Test to verify the normality of the data distribution and with ANOVA and Tukey's post hoc test at P < 0.05. Fracture patterns (restorable or unrestorable) were analyzed (Pearson's Chi-square test). RESULTS: The average fracture resistance was: Group 1 = 366.4 N, Group 2 = 507.4 N and Group 3 = 509.9 N. No significant difference was found among the three groups for fracture resistance or for failure mode. The insertion length did not influence the fracture pattern; more restorable fractures were detected.

Dentin Exposure after Tooth Preparation for Laminate Veneers: A Microscopical Analysis to Evaluate the Influence of Operators' Expertise.

Background: To assess the quantity of dentin exposure detected by 3 operators with different clinical expertise for 2 designs of tooth preparation for laminate veneers: window (WI) and butt joint (BJ). Methods: 20 intact maxillary central incisors were collected and then prepared for laminate veneers to a depth of 0.6 mm, with a cervical mini-chamfer finish line of 0.3 mm. Each prepared tooth was analyzed by 3 operators with different expertise: undergraduate student (ST), general practitioner (GP), and prosthodontist (PR), at sight under magnification. Besides descriptive statistics (CI 95%), 2-way ANOVA and Games−Howell tests were used to analyze differences among groups (α = 0.05). Results: The means of percentage and area of detected dentin exposure were WI = 30.48%, 21.57 mm2; BJ = 30.99%, 21.97 mm2; ST/WI = 22.82%, 16.44 mm2; GP/WI = 58.05%, 40.64 mm2; PR/WI = 10.55%, 7.63 mm2; ST/BJ = 28.99%, 20.83 mm2; GP/BJ = 40.56%, 28.32 mm2; PR/BJ = 23.42%, 16.75 mm2. Significant differences were found between ST/WI vs. GP/WI (p = 0.005) and GP/WI vs. PR/WI (p < 0.001). Conclusions: There was no difference in detection of exposed dentin among operators with different expertise for BJ preparation, whereas differences were found between the general practitioner and the other 2 operators in WI. Moreover, the quantity of exposed dentin was not related to different tooth preparation designs.

Human Papilloma Virus Vaccination and Oropharyngeal Cancer: Knowledge, Perception and Attitude among Italian Pediatric Dentists.

BACKGROUND: Pediatric dentists could play a key role in the prevention of human papilloma virus (HPV)-related oropharyngeal cancer (OP-cancer). The aim of this study was to assess knowledge, perception, and attitude on HPV-related OP-cancer, HPV infection, and HPV vaccination among Italian pediatric dentists. METHODS: A cross-sectional study was conducted. Pediatric dentists received, by email, a link to participate in the questionnaire online. The questionnaire comprised four parts: (i) demographic information, (ii) knowledge on HPV-related OP-cancer, HPV infection, and HPV vaccine, (iii-iiii) perceptions and attitude on HPV-related OP-cancer, HPV infection, and HPV vaccine. Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney test and Pearson's chi-square test. RESULTS: A total of 271 pediatric dentists completed the questionnaire. Results showed a good overall knowledge; a positive perception of their role in HPV disease prevention; a good attitude in discussing sensitive topics; a need for acquiring more information about HPV's connection to cancer, HPV infection, and HPV vaccine. CONCLUSIONS: Improving educational training programs, as well as informing about prevention of HPV-related OP-cancer, will place pediatric dentists in the front line of HPV diseases primary prevention.

A Biologically Driven Concept to Design the Emergence Profile Around Dental Implants: Surgical and Prosthetic Considerations to Optimize Hard and Soft Tissue Integration.

The emergence profile is a crucial factor in facilitating favorable esthetic outcomes and maintaining peri-implant health and stability. It should be evaluated not simply in terms of morphology but as a clinical variable closely related to material properties and clinical approaches; in this way, this critical factor-which can significantly influence the integration, stability, and preservation of bone and soft tissues-can be comprehensively planned. Soft tissue integration and adherence to prosthetic components are paramount elements in the preservation and protection of bone from contamination and infection. The present narrative paper presents a prosthetic concept suggested as an operative strategy to preserve peri-implant hard and soft tissues and achieve predictable prosthetic outcomes, optimizing soft tissue integration. Achieving an ideal soft tissue seal around implants is paramount in achieving stable restorations and protecting the bone interface from possible contamination and infection.