Influence of occlusal thickness on the fracture resistance of chairside milled lithium disilicate posterior full-coverage single-unit prostheses containing virgilite: A comparative in vitro study.

PURPOSE: To evaluate the fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate mandibular posterior crowns with virgilite of different occlusal thicknesses and compare them to traditional lithium disilicate crowns. MATERIALS AND METHODS: Seventy-five chairside CAD-CAM crowns were fabricated for mandibular right first molars, 60 from novel lithium disilicate with virgilite (CEREC Tessera, Dentsply Sirona), and 15 from traditional lithium disilicate (e.max CAD, Ivoclar Vivadent). These crowns were distributed across five groups based on occlusal thickness and material: Group 1 featured CEREC Tessera crowns with 0.8 mm thickness, Group 2 had 1.0 mm thickness, Group 3 had 1.2 mm thickness, Group 4 with 1.5 mm thickness, and Group 5 included e.max CAD crowns with 1.0 mm thickness. These crowns were luted onto 3D-printed resin dies using Multilink Automix resin cement (Ivoclar Vivadent). Subsequently, they underwent cyclic loading (2,000,000 cycles at 1 Hz with a 275 N force) and loading until fracture. Scanning electron microscopy (SEM) assessed the fractured specimens. Statistical analysis involved one-way ANOVA and the Kruskal-Wallis Test (α = 0.05). RESULTS: Fracture resistance varied significantly (<0.001) across mandibular molar crowns fabricated from chairside CAD-CAM lithium disilicate containing virgilite, particularly between crowns with 0.8 mm and those with 1.2 and 1.5 mm occlusal thickness. However, no significant differences were found when comparing crowns with 1, 1.2, and 1.5 mm thicknesses. CEREC Tessera crowns with 1.5 mm thickness exhibited the highest resistance (2119 N/mm2), followed by those with 1.2 mm (1982 N/mm2), 1.0 mm (1763 N/mm2), and 0.8 mm (1144 N/mm2) thickness, whereas e.max CAD crowns with 1.0 mm occlusal thickness displayed the lowest resistance (814 N/mm2). CONCLUSIONS: The relationship between thickness and fracture resistance in the virgilite lithium disilicate full-coverage crowns was directly proportional, indicating that increased thickness corresponded to higher fracture resistance. No significant differences were noted among crowns with thicknesses ranging from 1 to 1.5 mm. This novel ceramic exhibited superior fracture resistance compared to traditional lithium disilicate.

Depth distortion and angular deviation of a fully guided tooth-supported static surgical guide in a partially edentulous patient: A systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis aimed to evaluate the depth distortion and angular deviation of fully-guided tooth-supported static surgical guides (FTSG) in partially edentulous arches compared to partially guided surgical guides or freehand. MATERIAL AND METHODS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in the Open Science Framework (OSF). The formulated population, intervention, comparison, and outcome (PICO) question was: "In partially edentulous arches, what are the depth distortion and angular deviation of FTSG compared to partially guided surgical guides or freehand?" The search strategy involved four main electronic databases, and an additional manual search was completed in November 2023 by following an established search strategy. Initial inclusion was based on titles and abstracts, followed by a detailed review of selected studies, and clinical studies that evaluated the angular deviations or depth distortion in FTSG in partial arches, compared to partially guided surgical guides or freehand, were included. In FTSG, two surgical approaches were compared: open flap and flapless techniques, and two digital methods were assessed for surgical guide design with fiducial markers or dental surfaces. A qualitative analysis for clinical studies was used to assess the risk of bias. The certainty of the evidence was assessed according to the grading of recommendations, assessment, development, and evaluations (GRADE) system. In addition, a single-arm meta-analysis of proportion was performed to evaluate the angular deviation of freehand and FTSG. RESULTS: Ten studies, published between 2018 and 2023, met the eligibility criteria. Among them, 10 studies reported angular deviations ranging from -0.32° to 4.96° for FTSG. Regarding FTSG surgical approaches, seven studies examined the open flap technique for FTSG, reporting mean angular deviations ranging from 2.03° to 4.23°, and four studies evaluated flapless FTSG, reporting angular deviations ranging from -0.32° to 3.38°. Six studies assessed the freehand surgical approach, reporting angular deviations ranging from 1.40° to 7.36°. The mean depth distortion ranged between 0.19 mm to 2.05 mm for open flap FTSG, and between 0.15 mm to 0.45 mm for flapless FTSG. For partially guided surgical guides, two studies reported angular deviations ranging from 0.59° to 3.44°. Seven studies were eligible for meta-analysis, focusing on the FTSG in open flap technique, with high heterogeneity (I2 (95%CI) = 92.3% (88.7%-96.4%)). In contrast, heterogeneity was low in studies comparing freehand versus FTSG in open flap techniques (I2 (95%CI) = 21.3% (0.0%-67.8%)), favoring the FTSG surgical approach. CONCLUSION: In partially edentulous arches, FTSG systems exhibited less angular deviation than freehand and partially guided surgical guides. Flapless surgical approaches were associated with reduced angular deviation and depth distortion, suggesting a potential preference for the FTSG method in these procedures.

Effect of incisal preparation design on the fracture strength of monolithic zirconia-reinforced lithium silicate laminate veneers.

PURPOSE: This study aimed to assess the fracture resistance of monolithic zirconia-reinforced lithium silicate laminate veneers (LVs) fabricated on various incisal preparation designs. MATERIALS AND METHODS: Sixty maxillary central incisors with various preparation designs were 3D-printed, 15 each, including preparation for: (1) LV with feathered-edge design; (2) LV with butt-joint design; (3) LV with palatal chamfer; and (4) full-coverage crown. Restorations were then designed and manufactured from zirconia-reinforced lithium silicate (ZLS) following the contour of a pre-operation scan. Restorations were bonded to the assigned preparation using resin cement and following the manufacturer's instructions. Specimens were then subjected to 10,000 thermocycles at 5 to 55°C with a dwell time of 30 s. The fracture strength of specimens was then assessed using a universal testing machine at a crosshead speed of 1.0 mm/min. One-way ANOVA and Bonferroni correction multiple comparisons were used to assess the fracture strength differences between the test groups (α = 0.001). Descriptive fractographic analysis of specimens was carried out with scanning electron microscopy images. RESULTS: Complete coverage crown and LV with palatal chamfer design had the highest fracture resistance values (781.4 ± 151.4 and 618.2 ± 112.6 N, respectively). Single crown and LV with palatal chamfer had no significant difference in fracture strength (p > 05). LV with feathered-edge and butt-joint designs provided significantly (p < 05) lower fracture resistance than complete coverage crown and LV with palatal chamfer design. CONCLUSION: The fracture resistance of chairside milled ZLS veneers was significantly influenced by the incisal preparation designs tested. Within the limitation of this study, when excessive occlusal forces are expected, LV with palatal chamfer display is the most conservative method of fabricating an indirect restoration.

Effect of preparation design and endodontic access on fracture resistance of zirconia overlays in mandibular molars: An in vitro study.

PURPOSE: To evaluate the fracture resistance of zirconia overlays, considering various preparation designs and the presence of endodontic access. MATERIALS AND METHODS: Ninety translucent zirconia (5Y-PSZ) overlay restorations were divided into six groups (n = 15/group) based on different preparation designs, with and without endodontic access: chamfer margin 4 mm above the gingival level without (group 1) and with endodontic access (group 2); margin 2 mm above the gingival level without (group 3) and with endodontic access (group 4); overlay with no chamfer margin without (group 5) and with endodontic access (group 6). Restorations were bonded to mandibular first molar resin dies, and the groups with endodontic access were sealed with flowable resin composite. All restorations underwent 100,000 cycles of thermal cycling between 5°C and 55°C, followed by loading until fracture. Maximum load and fracture resistance were recorded. ANOVA with Tukey post-hoc tests were used for statistical comparison (α < 0.05). RESULTS: Fracture resistance significantly varied among overlay designs with and without endodontic access (p < 0.001), except for the no-margin overlays (groups 5 and 6). Overlays with a 2 mm margin above the gingival margin with endodontic access (group 4) exhibited significantly higher fracture resistance compared to both the 4-mm supragingival (group 2) and no-margin (group 6) designs, even when compared to their respective intact groups (groups 1 and 5). There were no significant differences between the no-margin and 4-mm supragingival overlays. CONCLUSION: The more extensive zirconia overlay for mandibular molars is the first choice since the 2 mm margin above the gingival level design withstood considerable loads even after undergoing endodontic access. A no-margin overlay is preferred over the 4-mm supragingival design as it preserves more tooth structure and there was no outcome difference, irrespective of endodontic access. Caution is warranted in interpreting these findings due to the in vitro nature of the study.

Short-term data suggests cognitive benefits in the elderly with single-implant overdentures.

DESIGN: This study was an extension of a randomized crossover clinical trial approved by the institutional ethics committee (approval number: D2014-148) and adhered to the CONSORT guidelines. The original study juxtaposed patient contentment with single-implant overdentures (1-IODs) against conventional complete dentures (CCDs), with patient satisfaction being the primary focus. In this follow-up study, the cognitive function of edentulous patients receiving 1-IODs was assessed, specifically monitoring for the emergence of mild cognitive impairment (MCI) throughout a three-year period. Patient outcomes were systematically recorded at predetermined intervals: initially, two months post-1-IOD placement, after one year (with groups alternated between denture types at eight-month marks), then after two and three years. A prosthodontist with a decade of expertise performed all denture-related procedures. This follow-up emphasized the cognitive outcomes using the Montreal Cognitive Assessment (MoCA-J), considering it alongside previously documented results on masticatory function, bone resorption, survival rates, and patient-reported outcomes. CASE SELECTION: Between 2015 and 2016, a follow-up study enrolled edentulous patients over 50 years of age who were proficient in Japanese, had sufficient mandibular bone for implants, and were free of systemic health issues and habits that could impact oral health. The participants were randomly divided into two groups after receiving a central mandibular implant. Group 1 initially used 1-IODs, and Group 2 used unloaded CCDs. After two months and subsequent periods, they swapped denture types. Eventually, all patients chose 1-IODs for continued use. Implant success was monitored over three years. The design featured block randomization and accounted for a sample size of 22, determined to be sufficient for evaluating the primary outcome of patient satisfaction. All patients underwent careful allocation and received customized dental interventions, with detailed radiographic planning and surgical precision guiding the implantation process. DATA ANALYSIS: Multivariable linear mixed models were used to assess within-group changes in both overall and specific cognitive function scores across five timepoints. Age, assessment interval, and upper jaw denture status were incorporated as consistent variables, while individual participants were considered variable elements in the analysis. SPSS software version 22.0 was utilized to conduct the statistical tests, and a p value threshold of 0.05 was predetermined to establish statistical significance. RESULTS: Twenty-two patients with edentulous mandibles received 1-IODs. Memory and executive functions saw significant score increases at multiple timepoints over the three-year period, with statistical significance. Though one participant dropped out and another passed away, and two did not complete the 3-year follow-up, the remaining 18 participants provided comprehensive data. Age and type of maxillary denture were significant factors, influencing MoCA-J scores with older participants and those with fixed dentures showing lower scores in certain domains. Overall, the findings illustrated the positive correlation between 1-IODs and cognitive function in older adults. CONCLUSIONS: Older adults with no natural teeth left in their mandible showed improved cognitive function after one and three years of using 1-IODs, as reflected by their total and specific cognitive domain scores. The study suggests that such implant therapy may offer protective benefits against cognitive decline, demonstrating clinical relevance for patient care, regardless of the maxillary arch (antagonist) condition.

Guided bone regeneration improves defect fill and reconstructive outcomes in 3-wall peri-implantitis defects.

DESIGN: This multi-center, randomized clinical trial compared the long-term outcomes of guided bone regeneration (GBR) with open flap debridement (OFD) in treating peri-implantitis-related bony defects with ≥3 osseous walls over 36 months. The study aimed to evaluate the healing potential of GBR using a deproteinized bovine bone mineral (DBBM) graft and native bilayer collagen membrane (NBCM) compared to OFD without the use of graft materials. CASE SELECTION: Sixty-six individuals diagnosed with peri-implantitis were randomly assigned to either GBR (34 patients) or OFD (32 patients). The OFD group served as the control, where inflamed tissue was removed and the implant surface decontaminated using 3% hydrogen peroxide, but no bone graft was placed. The GBR group received DBBM and NBCM for defect reconstruction. Radiographic defect fill (RDF), probing pocket depth (PPD), bleeding on probing (BOP), suppuration (SUP), mucosal recession (MREC), and patient-reported outcomes (PROs) were assessed over the study duration. Post-surgical care included azithromycin, ibuprofen, and chlorhexidine rinses. STUDY TIMELINE: The study involved baseline assessments, surgical interventions, and follow-ups at 6, 12, and 36 months. Supportive peri-implant therapy was provided every 3 months during the additional 24-month follow-up. DATA ANALYSIS: Primary outcome was RDF at 36 months. Secondary outcomes included PPD, BOP, SUP, MREC, and PROs. Descriptive statistics and ANCOVA models were used for analysis. RESULTS: At 36 months, GBR resulted in a mean RDF of 2.13 ± 1.26 mm, compared to 1.64 ± 1.54 mm with OFD (p = .18). No significant differences were found in PPD, BOP, SUP, REC, or PROs between the groups. Treatment success (defined as no additional bone loss, PPD ≤ 5 mm, no BOP, and no SUP) was achieved in 46.2% of GBR cases and 20% of OFD cases (p = 0.053). CONCLUSIONS: GBR provided improved short-term defect fill and higher treatment success compared to OFD, although the differences were not statistically significant. Both procedures maintained clinical parameters over 36 months, with similar patient satisfaction (PROs) observed for GBR and OFD. The adjunct use of DBBM and NBCM may offer clinical benefits for peri-implantitis cases with specific bony defect morphology.

Dental implants significantly increase adjacent tooth loss risk due to root fracture.

DESIGN: This retrospective cohort study aimed to investigate the risk and variables of tooth loss for teeth adjacent to dental implants compared to teeth nonadjacent to implants. The study followed the STROBE guidelines and was approved by the Institutional Review Board. COHORT SELECTION: The study included patients treated with dental implants at UCSF School of Dentistry between 2000 and 2020. The inclusion criteria for teeth adjacent to implants required the implant to support a fixed prosthesis and a follow-up period of at least 12 months. Nonadjacent teeth also required a follow-up period of at least 12 months. Teeth were excluded if they had a hopeless prognosis or were planned for extraction before the completion of restorative treatment. DATA ANALYSIS: Data were extracted from electronic health records, including patient demographics, dental histories, and outcomes for teeth adjacent and nonadjacent to implants. Statistical analyses, including Kaplan-Meier survival plots, log-rank tests, and multivariate logistic regression, were used to compare tooth survival and identify aetiologies of tooth loss. RESULTS: The study included 787 patients, with 2048 teeth adjacent and 15,637 teeth nonadjacent to implants. The 10-year cumulative survival rate was 89.2% for teeth adjacent to implants and 99.3% for nonadjacent teeth. Teeth adjacent to implants had a significantly higher risk of tooth loss (Odds Ratio [OR] 13.15). The primary etiology of tooth loss adjacent to implants was root fracture (45.2%), followed by caries (28.9%), periodontitis (24.1%), and endodontic failure (1.8%). For nonadjacent teeth, periodontitis was the leading cause of tooth loss (51.9%). CONCLUSIONS: The study found that teeth adjacent to dental implants had a significantly higher risk of tooth loss, primarily due to root fractures. The findings suggest that dental implants may act as an iatrogenic factor, increasing the risk of complications for adjacent teeth. Conservative management of natural dentition should be prioritized, with emphasis on stringent periodontal surveillance and effective home care. Future research should focus on prospective studies to further explore these associations and improve clinical outcomes.

Maintaining periodontally compromised teeth seems more cost-effective than replacing them with dental implants.

DESIGN: A systematic appraisal without statistical aggregation. DATA SOURCES: The researchers utilized Ovid (Medline), Embase, Web of Science, and CINAHL databases. They performed a comprehensive literature search, which concluded in July 2023. References of selected studies and systematic reviews were examined for additional relevant articles. STUDY SELECTION: The review included studies (randomized controlled trials [RCTs], systematic reviews [SRs], narrative reviews, retrospective studies, cross-sectional studies, case series, case reports) discussing the cost-effectiveness of preserving teeth versus replacing them with implants in patients with severe periodontal disease. Non-English publications, letters, conference abstracts, and brief reports were excluded. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently screened titles and abstracts using a systematic review screening tool, resolving conflicts with a third reviewer. The extracted data included study design, patient demographics, treatment details, economic models, costs, and clinical implications. Quality was assessed using Joanna Briggs Institute (JBI) critical appraisal tools, with scores converted to percentages. RESULTS: A total of 633 studies were identified for periodontal treatment, with 9 included after screening, while 114 studies were identified for dental implants, of which 3 were included after screening. The included studies were published between 2008 and 2018, predominantly from Germany, and mainly comprised retrospective designs, along with some prospective and model-based analyses. Follow-up periods ranged from 36 months to 33 years. Treatment costs were found to increase with disease severity, with surgical treatments being more expensive than nonsurgical ones, and supportive periodontal treatment (SPT) representing the highest cost share in periodontal treatment. Maintaining implants proved more costly than maintaining teeth, especially in cases of peri-implantitis. For chronic periodontitis, total treatment costs per tooth were €222 ± €98 over 18.7 years, and for aggressive periodontitis, €267 ± €148 over 16.9 years. Regular SPT cost €806 per tooth per year over 28.7 years, with significant cost variations across studies. A 2013 study found that maintaining implants was five times costlier than maintaining teeth, particularly if peri-implantitis developed. A 2018 study indicated that implant-supported crowns (ISCs) were the most expensive therapy. Only one study directly compared costs within the same patient, finding periodontal treatment to be more cost-effective than implants. Costs also increased with irregular SPT, aggressive periodontitis, and specialist treatments compared to regular SPT, chronic periodontitis, and treatments by general dental practitioners. The quality of included studies scored between 45% and 84.6%, indicating moderate to high quality, with methodological issues including unclear strategies for handling confounding factors and incomplete follow-up. CONCLUSIONS: Implants are effective for replacing missing teeth but are associated with higher long-term costs and complications. Maintaining periodontally compromised teeth is generally more cost-effective, therefore, maintenance costs and potential complications should be carefully considered in treatment planning. There is a need for studies comparing the long-term cost-effectiveness of saving teeth compared to replacing them with implants, considering several variables for informed clinical decision-making.

Similar short-term outcomes for bone-level implants with or without intermediate abutments.

DESIGN: A single-center (university-setting), prospective, longitudinal, split-mouth, single-blind, randomized controlled clinical trial investigated peri-implant parameters of bone-level implants restored with either screw-retained prostheses connected directly to the implants or with intermediate abutments over a 3-year period. The study adhered to the ethical principles of the Helsinki Declaration and the CONSORT guidelines. Ethical approval was granted, and the trial was registered at Clinicaltrials.gov . CASE SELECTION: Participants included were over 18 years of age, had a plaque index below 25%, and were missing at least two adjacent teeth, allowing for rehabilitation with screw-retained fixed partial prostheses over two implants and 2-4 prosthetic units. Exclusion criteria included long-term use of medications affecting bone metabolism, smoking more than 10 cigarettes per day, history of local radiotherapy, untreated periodontitis, and the need for rehabilitation in the anterior sextant of the maxilla. The primary clinical outcome was marginal bone loss (MBL), while secondary outcomes included probing pocket depth (PPD), plaque index (PI), bleeding on probing (BOP), and patient-reported outcomes (PROs). STUDY TIMELINE: The study schedule included a screening (visit 1), implant surgery (visit 2), stage-two 8 weeks post-surgery (visit 3), impressions taken 4 weeks post stage-two (visit 4), baseline standardized radiograph (visit 5), followed by 6-month (visit 6), 12-month (visit 7), and 36-month (visit 8) follow-up visits. DATA ANALYSIS: Descriptive statistics and quantitative measures included means, standard deviations (SDs), minimum and maximum values, and 95% confidence intervals (CIs). Clinical parameters (six sites per implant) measured were MBL, PPD, PI, and BOP. Paired t tests were utilized for intragroup comparisons across different time points and intergroup comparisons at each time point. PROs at 36 months were compared using Student's t test. The alpha significance level was set at 0.05. RESULTS: The study included 36 patients (72 implants), with two not completing the follow-up due to death and relocation. No implants showed signs of inflammation or mobility. Mean interproximal bone level (IBL) at baseline was 0.13 mm ± 0.15 mm for the control group and 0.10 ± 0.13 mm for the test group. At the 36-month follow-up, mean IBL was 0.13 ± 0.18 mm for the control group and 0.20 ± 0.24 mm for the test group, with no significant differences (F(1, 32) = 1.06; p > 0.05). Clinical parameters (PPD, BOP, PI) at 36 months showed no significant differences between groups. Minor complications occurred in 6.7% of the control group and 5.3% of the test group. PROs indicated no significant differences in general satisfaction, esthetics, comfort, phonetics, and masticatory function between the groups. CONCLUSIONS: After a 36-month follow-up, bone-level implants restored with CAD/CAM prostheses directly connected to the implants displayed similar clinical outcomes, PROs, and marginal bone level changes as those restored with intermediate standardized abutments.

LONG-TERM OUTCOMES OF IMPLANT PLACEMENT VERSUS TOOTH PRESERVATION IN PERIODONTALLY COMPROMISED TEETH MAY BE COMPARABLE.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Sarafidou K, Lazaridi I, Gotsis S, Kirmanidou Y, Vasilaki D, Hirayama H, Michalakis K. Tooth preservation vs. extraction and implant placement in periodontally compromised patients: A systematic review and analysis of studies. J Prosthodont. 2022 Oct;31(8):e87-e99. doi:10.1111/jopr.13560. Epub 2022 Aug 2. PMID: 35794083 SOURCE OF FUNDING: No external funding was received for this research. TYPE OF STUDY/DESIGN: Systematic review (without meta-analysis).

IMPLANT-SUPPORTED DENTAL PROSTHESES MAY PRESERVE OROFACIAL HARD AND SOFT TISSUES.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: De Souza AB, Papaspyridakos P, Weber HP, Vazouras K, Matarazzo F. Effect of dental implant therapy on the preservation of orofacial tissues: A systematic review and meta-analysis. Clin Oral Implants Res. 2023;34 Suppl 26:240-256. doi:10.1111/clr.14106. PMID: 37750525. SOURCE OF FUNDING: No private or public funding was received for this research. CONFLICT OF INTEREST: The authors declare that they have no competing interests. TYPE OF STUDY/DESIGN: Systematic review (with meta-analysis).

LIMITED DATA SHOWS POTENTIAL OF FLAPLESS SURGERY FOR ENHANCED BUCCAL BONE PRESERVATION IN IMMEDIATE IMPLANT PLACEMENT.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Pitman J, Christiaens V, Callens J, Glibert M, Seyssens L, Blanco J, Cosyn J. Immediate implant placement with flap or flapless surgery: A systematic review and meta-analysis. J Clin Periodontol. 2023 Jun;50(6):755-764. doi: 10.1111/jcpe.13795. Epub 2023 Mar 5. PMID: 36843361. SOURCE OF FUNDING: The study was funded by the authors and their affiliated institutions. TYPE OF STUDY/DESIGN: Systematic review with meta-analysis.

Effect of resin cement selection on fracture resistance of chairside CAD-CAM lithium disilicate crowns containing virgilite: A comparative in vitro study.

STATEMENT OF PROBLEM: Studies on the fracture performance of a recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate ceramic containing virgilite with different cements are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the fracture resistance of crowns made of a recently introduced chairside CAD-CAM lithium disilicate containing virgilite cemented with different types of adhesive luting cement. MATERIAL AND METHODS: Sixty complete coverage crowns for a maxillary right central incisor were milled out of a lithium disilicate with virgilite (CEREC Tessera) (n=48) and a traditional lithium disilicate (e.max CAD) (n=12) using a chairside CAD-CAM system (Primescan). The central incisor tooth preparation included a 1.5-mm incisal reduction, a 1.0-mm axial reduction, and a 1.0-mm chamfer finish line. The restorations were bonded with different types of resin cement to 3D printed dies of the tooth preparation and were divided into 5 groups (n=12 per group): e.max CAD with Multilink Automix (E.Mu); Tessera with Multilink Automix (T.Mu); Tessera with Calibra (T.Ca); Tessera with Unicem (T.Un); and Tessera with Speedcem (T.Sp). The cemented restorations were stored in water for 30 days and then loaded until they were fractured in compression. The load at fracture was analyzed with a 1-way analysis of variance (ANOVA) and the honestly significant difference (HSD) Tukey test (α=.05). RESULTS: The mean fracture resistance of traditional lithium disilicate and virgilite lithium disilicate anterior crowns significantly differed depending on the type of resin cement used (P<.05). Group E.Mu displayed the highest values (946.35 ±155 N), followed by group T.Un (819.59 ±232 N), group T.Sp (675.52 ±153 N), and group T.Mu (656.95 ±193 N). The lowest values were displayed by group T.Ca (567.94 ±184 N). CONCLUSIONS: The fracture resistance of lithium disilicate containing virgilite and traditional lithium disilicate crowns cemented with the same cement displayed statistically similar values. However, significant differences were observed when the virgilite lithium disilicate crowns were cemented with different types of adhesive luting cement. The crowns in the T.Ca group displayed the lowest fracture resistance.

Enhanced Lip-Contour During Facial Scan for 3D DSD and Implant Planning: A Blue Screen Approach.

When obtaining 3-dimensional (3D) facial images for digital smile design (DSD) and dental implant planning, inaccuracies may frequently be introduced by distortion in the region between the lips' vermilion border and the teeth. The present clinical technique aimed to reduce such deformation during face scanning, thereby facilitating 3D DSD. This is also essential to plan bone reduction with precision for implant reconstructions. A custom-made silicone matrix acting as a blue screen provided reliable support for 3D visualization of facial images in a patient requiring a new maxillary screw-retained implant-supported fixed complete denture. Imperceptible volumetric changes were registered in the facial tissues when the silicone matrix was added. The usual deformation of the lip vermilion border originating in face scans was overcome by applying blue-screen technology with a silicone matrix. Reproducing the vermilion border of the lip contour accurately may offer improved communication and visualization for 3D DSD. The silicone matrix was a practical approach that acted as a blue screen to display the transition from lips to teeth with satisfactory precision. Implementing blue-screen technology in reconstructive dentistry might increase predictability by reducing errors when scanning objects with challenging-to-capture surfaces.

Effect of sintering on the translucency of CAD-CAM lithium disilicate restorations: A comparative in vitro study.

PURPOSE: The available independent data on the translucency of novel pre and fully sintered chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate are limited. This comparative in vitro study evaluated the translucency degree of pre and fully sintered chairside CAD-CAM lithium disilicate crowns after optional, required, and additional firing processes. MATERIALS AND METHODS: One hundred and five maxillary left central incisor crowns manufactured by three different CAD-CAM lithium disilicate brands shade A1 were assigned into seven groups as follows (n = 15): (1) Straumann n!ce without sintering; (2) Straumann n!ce with one additional sintering process; (3) Straumann n!ce with two additional sintering processes; (4) Amber Mill with one sintering process; (5) Amber Mill with two sintering processes; (6) IPS e.max CAD with one sintering process; and (7) IPS e.max CAD with two sintering processes. The translucency of all crowns was evaluated with a color imaging spectrophotometer. All statistical analyses were performed using statistical software. A standard level of significance was set at α < 0.05. RESULTS: All the milled crowns presented different degrees of translucency, and additional sintering processes altered it. IPS e.max CAD with two (4.33 ± 0.26) and one (4.01 ± 0.15) sintering processes displayed the highest translucency, whereas Straumann n!ce with no sintering process provided the lowest value (2.82 ± 0.16). CONCLUSIONS: The translucency of chairside lithium disilicate single-unit full-coverage restorations manufactured with subtractive technology was significantly influenced by the brand and the number of sintering processes. The traditional presintered IPS e.max CAD and the fully crystallized glass-ceramic Straumann n!ce considerably increased the translucency after one additional firing process, whereas Amber Mill decreased its translucency.

Double-Crown Prosthesis Retention Using Polyetherketoneketone (PEKK): An In Vitro Study.

PURPOSE: To assess the retentive force of telescopic crowns using polyetherketoneketone (PEKK) high-performance polymer in relation to conventional materials over a long period of time in an in vitro setting. MATERIALS AND METHODS: Thirty-six sets of primary and secondary crowns were fabricated as per the double crown-retained prostheses approach. Six samples were included in each of the five test groups (1: zirconia/PEKK [Zr/PEKK]; 2: titanium/PEKK [Ti/PEKK]; 3: cobalt-chrome/PEKK [CoCr/PEKK]; 4: PEKK/PEKK; and 5: gold/PEKK [Au/PEKK]) and the single control group (gold/galvano-gold [Au/GA]). The insertion-removal test was performed for 20,000 cycles, and the surface condition was observed. Retentive forces were analyzed using two-way ANOVA (α<0.05). RESULTS: The retention forces in groups Zr/PEKK and Ti/PEKK significantly decreased over time (group 1: p = 0.035 and group 2: p = 0.001), whereas retentive force increased significantly in groups PEKK/PEKK, Au/PEKK, and control (group 4: p = 0.001, group 5: p = 0.008, and control: p = 0.042). Similar wear was observed on the primary crown in groups PEKK/PEKK, gold/PEKK, and control. CONCLUSIONS: Groups PEKK/PEKK and Au/PEKK showed a transition of retentive force similar to the control group. Groups PEKK/PEKK and Au/PEKK had similar wear on the surface compared to control. Therefore, PEKK has a promising clinical potential.

Traditional versus conservative endodontic access impact on fracture resistance of chairside CAD-CAM lithium disilicate anterior crowns: An in vitro study.

PURPOSE: To evaluate the effect of traditional and conservative endodontic access hole preparation on fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate maxillary right central incisor crowns. MATERIALS AND METHODS: Fifty-seven milled lithium disilicate maxillary right central incisor crowns were designed and fabricated with a chairside CAD-CAM system (Planmeca Romexis, Planmeca). The abutment preparation had a 1.0 mm incisal reduction and 1.0 mm chamfer finish. The restorations were bonded with resin cement to printed resin dies (n = 19 per group) and were treated and divided into three groups, (1) no endodontic access, (2) traditional triangular endodontic access, and (3) conservative ovoidal endodontic access. The endodontic access of the crowns was sealed with flowable resin composite. Restorations were subjected to 10,000 cycles of thermal cycling between 5° and 55°C. Then, restorations were loaded and exposed to compressive loading force, and the crack initiation (CI) and complete fracture (CF) were recorded. SEM micrographs of broken specimens on the printed dies were captured. ANOVA test and Bonferroni's correction were used for statistical comparison. RESULTS: The fracture resistance among the three groups varied. Crowns with no endodontic access displayed significantly (p < 0.001) higher resistance [CI: 1025 (121) N; CF 1134 (127) N], followed by crowns with conservative ovoidal endodontic access [CI: 924 (60) N; CF: 1000 (72) N. Crowns with traditional triangular endodontic access showed the significantly (p < 0.001) lowest fracture resistance [CI: 635 (82) N; CF: 709 (75) N]. CONCLUSION: The fracture resistance of chairside CAD-CAM lithium disilicate maxillary anterior crowns is influenced by the type of endodontic access provided. Conservative ovoidal endodontic access provides crowns with higher fracture resistance than traditional triangular endodontic access. Crowns with no endodontic access provided the highest resistance than other types of endodontic access.

Minimally Invasive Laminate Veneer Therapy for Maxillary Central Incisors.

Minimally invasive dentistry is a considered process that requires the clinician to be prepared with the ideal sequence and the tools needed. This report describes a well-planned ultraconservative approach using only two ceramic laminate veneers for the maxillary central incisors to significantly improve the patient's overall smile. A 30-year-old female presented with the chief complaints of having diastemas between the central and lateral incisors as well as incisal wear. Diagnostic wax-up and mock-up were performed, and the patient approved the minimally invasive treatment with veneers only for central incisors. A reduction guide aided the conservative tooth preparations, and hand-crafted feldspathic veneers were bonded under total isolation with a rubber dam. The two final conservative veneers significantly improved the smile and fulfilled the patient's expectations. Following proper planning and sequencing, predictable outcomes were obtained and fulfilled the patient's esthetic demands. Minimally invasive restorative dentistry with only two single veneers can impact the entire smile frame. Overtreatment in the esthetic zone is unnecessary to meet a patient's esthetic expectations.

Soft Tissue Grafting Procedures before Restorations in the Esthetic Zone: A Minimally Invasive Interdisciplinary Case Report.

An esthetically pleasing smile is a valuable aspect of physical appearance and plays a significant role in social interaction. Achieving the perfect balance between extraoral and intraoral tissues is essential for a harmonious and attractive smile. However, certain intraoral deficiencies, such as non-carious cervical lesions and gingival recession, can severely compromise the overall aesthetics, particularly in the anterior zone. Addressing such conditions requires careful planning and meticulous execution of both surgical and restorative procedures. This interdisciplinary clinical report presents a complex case of a patient with esthetic complaints related to asymmetric anterior gingival architecture and severely discolored and eroded maxillary anterior teeth. The patient was treated using a combination of minimally invasive ceramic veneers and plastic mucogingival surgery, resulting in a successful outcome. The report emphasizes the potential of this approach in achieving optimal esthetic results in challenging cases, highlighting the importance of an interdisciplinary team approach in achieving a harmonious balance between dental and soft tissue aesthetics.

Ceramic versus Composite Resin Polishing Systems on the Surface Roughness of Milled Leucite-Reinforced Ceramics.

Background and Objective: This study aimed to compare the surface finish of milled leucite-reinforced ceramics polished with ceramic and composite polishing systems based on the manufacturers' recommendations. Materials and Methods: Sixty subtractive computer-aided manufactured (s-CAM) leucite-reinforced glass-ceramic specimens (IPS-Empress-CAD) were assigned into six groups: no polishing, a ceramic polishing kit, and four composite kit groups. The roughness average (Ra) was evaluated in microns using a profilometer, and scanning electron micrographs were obtained for qualitative analysis. A Tukey HSD posthoc test (α = 0.05) was used to determine significant intergroup differences. Results: After surface evaluation of the ceramics, the Ra values of the polishing systems ranked OptraFine (0.41 ± 0.26) < Enhance (1.60 ± 0.54) < Shofu (2.14 ± 0.44) < Astropol (4.05 ± 0.72) < DiaComp (5.66 ± 0.62) < No Polishing (5.66 ± 0.74). Discussion: Composite polishing systems did not provide as smooth surfaces as the ceramic polishing kit for CAD-CAM leucite-reinforced ceramics. Thus, using ceramic polishing systems, polishing leucite ceramics is recommended, whereas composite polishing systems should not be considered as an alternative for use in minimally invasive dentistry.