Abutment Crown Research Articles

Evaluation of Dental Panoramic Radiographs by Artificial Intelligence Compared to Human Reference: A Diagnostic Accuracy Study.

Background/Objectives: The role of artificial intelligence (AI) in dentistry is becoming increasingly significant, particularly in diagnosis and treatment planning. This study aimed to assess the sensitivity, specificity, accuracy, and precision of AI-driven software in analyzing dental panoramic radiographs (DPRs) in patients with permanent dentition. Methods: Out of 638 DPRs, 600 fulfilled the inclusion criteria. The radiographs were analyzed by AI software and two researchers. The following variables were assessed: (1) missing tooth, (2) root canal filling, (3) endodontic lesion, (4) implant, (5) abutment, (6) pontic, (7) crown, (8) and sound tooth. Results: The study revealed very high performance metrics for the AI algorithm in detecting missing teeth, root canal fillings, and implant abutment crowns, all greater than 90%. However, it demonstrated moderate sensitivity and precision in identifying endodontic lesions and the lowest precision (65.30%) in detecting crowns. Conclusions: AI software can be a valuable tool in clinical practice for diagnosis and treatment planning but may require additional verification by clinicians, especially for identifying endodontic lesions and crowns. Due to some limitations of the study, further research is recommended.

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.

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. 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. 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). 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. 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.

One-Piece Versus Two-Piece Abutments for Single Crowns in the Esthetic Zone: A Clinical Trial.

To evaluate whether a two-piece abutment is equivalent to a one-piece in peri-implant esthetics, patients' satisfaction, and oral health-related quality of life (OHRQOL) for implant-supported anterior single crown placement. Thirty implants were allocated sequentially: 15 in the one-piece abutment group (OP) and 15 in the two-piece abutment group (TP). Peri-implant esthetics were evaluated by the pink esthetic score (PES) at temporary crown insertion (T1), after tissue conditioning (T2), and at 30 days after the final crown insertion (T3). OHRQOL was measured using the OHIP-14 and satisfaction was evaluated using the visual analog scale (VAS) at baseline, T1, and T3. Treatment was considered equivalent if the 95% coefficient interval (CI) for mean difference in PES was between -1.5 and +1.5 points. Statistical analysis was performed using Mann-Whitney, SPANOVA, and Student's t-test, with Sidak's posttest, adopting p < 0.05. No differences were found between the groups for any variable and during follow-up. A significant increase in OHRQOL and satisfaction was observed at T3, when compared to baseline (p < 0.05) for both groups. Significant improvements in peri-implant esthetics were also observed throughout the treatment, particularly after tissue conditioning (p < 0.05). Primary and secondary outcomes were evaluated for equivalence, and both abutment types were considered equivalent following the insertion of the temporary crowns. Two-piece abutment was equivalent to one-piece abutment for peri-implant esthetics, quality of life, or the satisfaction of patients rehabilitated with metal-free single crowns. Tissue conditioning and final crown insertion appear to play a role in improving these outcomes.

INFLUENCE OF ABUTMENT MATERIAL, CEMENT THICKNESS, AND CROWN TYPE ON THE FINAL COLOR OF IMPLANT-SUPPORTED RESTORATIONS.

To evaluate the influence of abutment material, cement thickness, and crown type on the esthetics of implant supported restorations. In total, 60 specimens were prepared to represent six abutment groups: Group PA &#61; pink-anodized Ti; Group GA &#61; gold-anodized Ti; Group T &#61; nonanodized Ti; Group H &#61; hybrid (Ti &#43; zirconia); Group P &#61; PEEK (Ti &#43; PEEK); and Group C &#61; composite resin (control). Crown specimens (n &#61; 120) were obtained from Vita Enamic (VE) and Vita Suprinity (VS). Two cement thicknesses (0.1 and 0.2 mm) were used. The color values of crown configura:ons were measured and ΔE00* values were calculated. Statistical analyses included were Shapiro Wilk, three-way ANOVA, and Tukey HSD tests (P ≤ .05). Abutment (P < .001) and crown materials (P &#61; .001) had a significant effect on ΔE00* values, while cement thickness did not. Groups PA and H resulted in significantly lower mean ΔE00* values than other abutments, whereas Group T revealed the highest. Unlike VS, cement thicknesses created a significant difference on the ΔE00* values for VE (P ≤.05). Pink-anodized Ti or hybrid abutments for VE and pink- or goldanodized Ti for VS seem to be better options, in terms of color change. Cement thickness of 0.1 mm resulted in higher ΔE00* value than 0.2 mm for VE (P ≤ .05).

Internal fit and marginal adaptation of all-ceramic implant-supported hybrid abutment crowns with custom-milled screw-channels on Titanium-base: in-vitro study

BackgroundAdvancements in digital dentistry helped in custom-milling screw-channels in implant-supported restorations; however, the fit of these restorations is still unclear especially for contemporary computer aided designing/computer aided manufacturing (CAD/CAM) materials. This study aimed to compare the internal and marginal fit of Ultra translucent multilayered zirconia versus lithium disilicate implant-supported hybrid abutment crowns (HACs) constructed with custom-milled screw-channels on Titanium-base.Materials and methodsA total of 24 HACs with custom-milled screw-channels were constructed from lithium disilicate (Group LDS) and Ultra translucent multilayered zirconia (Group UT) using digital workflow (n = 12). The internal and marginal gaps of HACs on their corresponding Titanium-bases were assessed using replica technique and stereomicroscope, respectively. After testing for normality, quantitative data were expressed as mean and standard deviation and compared using independent t-test at a level of significance (P ≤ 0.05).ResultsThere was no statistically significant difference between Group LDS and Group UT in terms of marginal and internal fit. The internal and marginal gaps in both groups were within the accepted values reported in literature.ConclusionsUT and LDS HACs with custom-milled screw-channels demonstrated comparable and acceptable internal fit and marginal adaptations to Ti-base, which lied within the range reported in literature.

Comparison of misfit and roughness of CAD-CAM ZrO, selective laser sintered CoCr and preformed Ti implant abutment crowns

BackgroundMarginal misfit and surface roughness of customized implant abutments is critical for restorative success. However, little is known about the comparison of misfit and surface roughness of CAD-CAM Zirconium oxide (ZrO), selective laser melting (SLM) Cobalt Chrome (CoCr) and preformed abutments. The aim of the study is to investigate the relation of misfit and micro-roughness of selective laser melting (SLM), preformed and CAD-CAM implant abutments.MethodsThirty internal connection, endosseous dental implants (Ø 4.0 mm x 10 mm, Dentium) were mounted in Polymethyl methacrylate vertically. Ten preformed Titanium alloy (Ti) abutments with 1 mm soft tissue height and Ø 4.5 mm were included as controls. Ten each of Y-TZP and SLM-CoCr, abutment/crowns were fabricated using CAD-CAM milling (CAD-CAM-ZrO) and SLM techniques. Surface micro-roughness (Ra) of the fabricated implant abutment/crown was evaluated with a 3D optical non-contact microscope. All implant restorations were torqued to implants (30 Ncm) using a Tohnichi BTGE digital torque gauge and were analyzed with Bruker micro-CT (Skyscan 1173) to detect micro-gaps at pre-selected points at implant abutment interface. The Ra and misfit data were compared using ANOVA, Tukey-Kramer, Kruskal-Wallis test and Pearson correlation (p < 0.05).ResultsMean Ra among SLM CoCr abutments [0.88 (0.09) µm] were lower than CAD-CAM-ZrO and higher than preformed Ti abutments. Horizontal misfit among SLM-CoCr [45.43 (9.41) µm] and preformed Ti [36.87 (13.23) µm] abutments was not statistically different (p > 0.05). Misfit was significantly higher in Y-TZP samples compared to SLM-CoCr (p = 0.031) and preformed Ti abutments (p = 0.01). Preformed Ti abutments showed significantly lower misfit compared to SLM-CoCr abutments (p = 0.01). A positive linear correlation was observed between the surface roughness (Ra) and vertical misfit (r = 0.61, p < 0.05).ConclusionSLM CoCr abutments showed rough surface compared to preformed Ti abutments, while horizontal misfit was comparable among SLM-CoCr and preformed abutments. Misfit was significantly greater in Y-TZP abutments, compared to SLM and preformed abutments. SLM abutment fabrication technique needs further improvement to provide better fit and surface topography.

Oral Health Status and Treatment Needs Based on Artificial Intelligence (AI) Dental Panoramic Radiograph (DPR) Analysis: A Cross-Sectional Study.

Background: The application of artificial intelligence (AI) is gaining popularity in modern dentistry. AI has been successfully used to interpret dental panoramic radiographs (DPRs) and quickly screen large groups of patients. This cross-sectional study aimed to perform a population-based assessment of the oral health status and treatment needs of the residents of Kielce, Poland, and the surrounding area based on DPR analysis performed by a high-accuracy AI algorithm trained with over 250,000 radiographs. Methods: This study included adults who had a panoramic radiograph performed, regardless of indications. The following diagnoses were used for analysis: (1) dental caries, (2) missing tooth, (3) dental filling, (4) root canal filling, (5) endodontic lesion, (6) implant, (7) implant abutment crown, (8) pontic crown, (9) dental abutment crown, and (10) sound tooth. The study sample included 980 subjects. Results: The patients had an average of 15 sound teeth, with the domination of the lower dental arch over the upper one. The most commonly identified pathology was dental caries, which affected 99% of participants. A total of 67% of patients underwent root canal treatment. Every fifth endodontically treated tooth presented a periapical lesion. Of study group members, 82% lost at least one tooth. Pontics were identified more often (9%) than implants (2%) in replacing missing teeth. Conclusions: DPR assessment by AI has proven to be an efficient method for population analysis. Despite recent improvements in the oral health status of Polish residents, its level is still unsatisfactory and suggests the need to improve oral health. However, due to some limitations of this study, the results should be interpreted with caution.

Material and abutment selection for CAD/CAM implant-supported fixed dental prostheses in partially edentulous patients - A narrative review.

Restorative material selection has become increasingly challenging due to the speed of new developments in the field of dental material science. The present narrative review gives an overview of the current indications for implant abutments and restoration materials for provisional and definitive implant-supported fixed dental prostheses in partially edentulous patients. For single implant restorations, titanium base abutments for crowns are suggested as an alternative to the conventional stock- and customized abutments made out of metal or zirconia. They combine the mechanical stability of a metallic connection with the esthetic potential of ceramics. For multiple-unit restorations, conical titanium bases especially designed for bridges are recommended, to compensate for deviating implant insertion axes and angulations. Even though titanium base abutments with different geometries and heights are available, certain clinical scenarios still benefit from customized titanium abutments. Indications for the definitive material in fixed implant restorations depend on the region of tooth replacement. In the posterior (not esthetically critical) zone, ceramics such as zirconia (3-5-Ymol%) and lithium-disilicate are recommended to be used in a monolithic fashion. In the anterior sector, ceramic restorations may be buccally micro-veneered for an optimal esthetic appearance. Lithium-disilicate is only recommended for single-crowns, while zirconia (3-5-Ymol%) is also recommended for multiple-unit and cantilever restorations. Attention must be given to the specific mechanical properties of different types of zirconia, as some feature reduced mechanical strengths and are therefore not indicated for all regions and restoration span lengths. Metal-ceramics remain an option, especially for cantilever restorations.

Brief Analysis of Clinical Evaluation Concerns of Personalized Abutments and Abutment Crown Bridge Products

The applications of personalized abutments and abutment crown bridge products have increased year by year, but there is no clear requirement for clinical evaluation of the same variety of such products. This study mainly introduces the clinical evaluation concerns of personalized abutments and abutment crown bridge products, in order to provide reference for the declaration and registration of such products. The clinical evaluation of personalized abutments and crown bridge products are summarized, and the research content of clinical evaluation is clarified. The clinical evaluation requirements that need to be considered by enterprises are introduced. Personalized abutment and abutment crown bridge products can refer to this study when they are launched in China, mainly using in vitro performance comparison tests for equivalence verification.

Monolithic hybrid abutment crowns: Influence of crown height, crown morphology and material on the implant-abutment complex.

This in vitro study investigated the influence of material selection, crown morphology, and vertical crown height on the biomechanical behavior of monolithic hybrid abutment crowns (HACs). Ninety implants were embedded in accordance with ISO standard 14801; ninety HACs were mounted (N=90). Monolithic crowns with varying group-specific designs were luted using titanium bases. HACs were fabricated from monolithic lithium disilicate ceramic (LD) or zirconia-reinforced lithium silicate ceramic (ZLS). The crown morphology was either maxillary premolar (LD_PM, ZLS_PM) or molar (LD_MO). The three groups were further divided into three subgroups of ten specimens, each designed with a small (7.5 mm), middle (10.5 mm), and high (13.5 mm) configuration of crown heights (N=10). A load-to-failure test at 30° off-axis was conducted using a universal testing machine until failure. For statistical analysis, Kolmogorov-Smirnov and Mann-Whitney U tests were conducted (P < 0.05). All LD_MO groups presented the highest failure values (808.7 to 947.9 N), followed by the LD_PM (525.8 to 722.8 N) and ZLS_PM groups (312.6 to 478.8N). A comparison between LD and ZLS materials (P < 0.001) as well as the crown morphology (P < 0.001) showed significant differences in failure values. The values in the subgroups of ZLS_PM (low, middle, high) decreased as the crown height increased. The fracture modes showed no consistent patterns across the test groups. Material selection, crown morphology, and vertical crown height appear to be important factors that may influence the clinical failure values and patterns of HACs.

Assessment of Micro-Gap in Hybrid Abutment-Crowns Fabricated with Different Materials

Objective: The aim of this in vitro study is to evaluate the micro-gap changes in three dimensions after thermodynamic loading between hybrid abutment crowns made of different materials and implants with internal conical connection.&#x0D; Methods: A total of 10 morse cone connection implants (Straumann Bone Level Implant, Institut Straumann AG, Basel, Switzerland) were used. In this study, two study groups were formed using lithium disilicate glass-ceramic (LD) and polymethyl methacrylate (PMMA) in hybrid abutment-crown production (n=5). Hybrid abutment-crowns were fabricated by CAD/CAM system. Hybrid abutment crowns were designed and manufactured digitally. A 4-month of clinical cycle was applied to the samples in the chewing simulator. The micro-gap at the implant- abutment interface was visualized with micro-CT before and after thermodynamic loading. Micro-gap change was determined using these obtained images. For comparisons, independent t-test was used.&#x0D; Results: When comparing the micro-gap volumes before and after aging, no significant difference was observed between the LD and PMMA groups. The micro-gap increase after loading was 0.68 ±0.209 in the LD group and 0.45 ±0.373 in the PMMA group. Although the increase was higher in the LD group, there is no statistically significant difference between two groups.&#x0D; Conclusion: he micro-gap in the interface of implants and hybrid abutment crowns increased after aging. Hybrid abutment-crown material affected the micro-gap increase, but it was not statistically significant.

Effect of abutment type and creep behavior on the mechanical properties of implant restorations in the anterior region: A finite element analysis.

This study aimed to assess the effect of abutment variation and creep on dental implant restorations. Three finite element analysis (FEA) models of implant restorations were created, which were restored by conventional one-piece abutment (CA), hybrid abutment crown (HAC), and multi-unit abutment (MUA). The contacts were considered intimate (no friction), except for implant/abutment, abutment/screw, and abutment/screw/crown (HAC) attachments. The related mechanical parameters were used to improve the authenticity of the study. Instantaneous loads and constant loads (100 s) of 130 N were applied at a 30° angle to the palatal portion of the crown. Results were qualitatively and quantitatively evaluated using the equivalent von Mises stress, micro-gap distance of the implant-abutment interface (IAI), preload changes, and safety index. The stress state of each component differed depending on the restoration type, from CA and HAC to MUA. Implants and screws were the structures that suffered the most stress under instantaneous loads. Each metal structure exhibited a substantial decrease in stress during a constant loading period. The screws of the MUA abutment showed more preload loss (62.1 N) after constant loads for 100 s. MUA base produced less micro-gap (0.72 μm) at the IAI when it was compared with the CA group (0.93 μm) and HAC group (3.29 μm). The abutment type influences the mechanical properties and performance of implant restorations. The creep effect decreases the maximum stress level and increases the safety factors of each structure, indicating that stress-related mechanical complications may not occur more easily.

Bonding Strength of Various Luting Agents between Zirconium Dioxide Crowns and Titanium Bonding Bases after Long-Term Artificial Chewing

The use of hybrid abutment crowns bonded extraorally to a titanium bonding base has aesthetic and biological benefits for the prosthetic rehabilitation of oral implants. The objective of this study was to evaluate the effects of luting agents between a zirconium dioxide crown and the titanium bonding base on crown/abutment retention and the subsequent durability of the prosthetic superstructure. Fifty-six implant abutment samples, all restored with a lower first premolar zirconium dioxide crown, were used and divided into seven groups (n = 8/group) according to the type of luting agent used: group 1, SpeedCEM Plus; group 2, Panavia SA Cement Universal; group 3, Panavia V5; group 4, RelyX Unicem 2 Automix; group 5, VITA ADIVA IA-Cem; group 6, Ketac CEM; and group 7, Hoffmann’s Phosphate Cement. All specimens were subjected to thermomechanical loading (load of 49 N, 5 million chewing cycles and 54.825 thermocycles in water with temperatures of 5 °C and 55 °C). The surviving samples were exposed to a pull-off force until crown debonding from the bonding base. Overall, 55 samples survived the thermomechanical load. Group 2 showed the highest mean pull-off force value (762 N), whereas group 6 showed the lowest mean value (55 N). The differences between the seven groups were statistically significant (ANOVA, p &lt; 0.001). The debonding failure pattern was mainly adhesive and was noticed predominantly at the zirconium dioxide–luting agent interface. Within the scope of the present investigation, it was shown that most of the luting agents are suitable for “cementation” of a zirconium dioxide crown onto a titanium base since the debonding forces are above a recommended value (159 N).

Comparison of Screw Loosening and Fracture Resistance in Different Hybrid Abutment Crown Restorations After Thermomechanical Aging.

To investigate the screw loosening and fracture resistance of different hybrid abutment crown restorations after thermomechanical aging. Restorations were produced from zirconia, lithium disilicate, and hybrid ceramics with a CAD/CAM system (n &#61; 10). Restorations and titanium bases (Ti-bases) were cemented, and the abutment screws were torqued to 30 Ncm. They were retorqued after 10 minutes, and then the removal torque values (RTVs) were measured. After 250,000 and 500,000 cycles of thermomechanical aging were completed, the RTVs were measured again, and removal torque loss (RTL) ratios were calculated. The specimens were subjected to a fracture resistance test after 750,000 cycles of thermomechanical aging, and the load at failure was recorded as the fracture resistance (N). The results were statistically analyzed (α &#61; .05). Aging was effective on the RTVs and RTL ratios (P < .001). The highest RTV was observed before aging; however, the RTVs significantly decreased and RTL ratios significantly increased after aging (P < .05). The fracture resistance values significantly differed among the ceramic materials. All lithium disilicate and hybrid ceramic specimens showed restoration fracture and most of the zirconia specimens showed Ti-base-related failure. Hybrid abutment crowns made of zirconia, lithium disilicate, and hybrid ceramics can withstand the average occlusal forces in the molar region; however, the ceramic type may affect the failure type. Retightening of the abutment screws after 10 minutes following the first tightening and annually may be beneficial to prevent the adverse effects of screw loosening on the integrity of the implant-abutment connection.

Strain gauge analysis and fracture resistance of implant-supported PEKK hybrid abutments restored with two crown materials: An in vitro study.

Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium and ceramic implant abutments due to its apparent ability to dissipate excessive strain around dental implants. However, the biomechanical behaviors of implant abutment crown systems may change depending on the crown and abutment material combinations used. This study aimed to assess how the crown material affects strain generation and fracture resistance of PEKK hybrid abutment crowns. Sixteen dummy implants (Ø 3.7 x 11 mm), simulating maxillary first premolars, were restored with 16 milled PEKK hybrid abutments and randomly categorized into two groups according to the crown material (n = 8): Group C, milled composite crowns cemented on PEKK hybrid abutments; and Group Z, ultra-translucent zirconia crowns cemented on PEKK hybrid abutments. Before thermocycling, a cyanoacrylate-base adhesive was used to position two strain gauges on buccal and lingual crestal bone surfaces, and a vertical load (100 N) was applied to the central fossa to record the strain generated. Then, all samples were thermocycled between 5°C and 55°C before being loaded to fracture on a universal testing machine. Modes of failure were observed under an optical microscope, and representative samples were examined using a scanning electron microscope. Independent t-tests were used for intergroup comparisons. The significance level was set at (p < 0.05) for all tests.. The results showed a significant difference between both groups. The zirconia group recorded significantly higher strain and fracture resistance values than the composite group (p < 0.001). There was a positive correlation between the strain developed in peri-implant crestal bone and fracture resistance of the abutment crown complex. Strains developed in both groups were within the acceptable clinical range. The crown material substantially impacted the strain and fracture of the PEKK hybrid abutment crown system.

IN VITRO SURVIVAL AND FRACTURE FORCE OF LITHIUM DISILICATE HYBRID ABUTMENT CROWNS.

To evaluate the behavior of hybrid abutment crowns fabricated from monolithic lithium disilicate ceramic (LDC) and to compare the influence of different in vitro artificial aging protocols. A total of 32 monolithic hybrid abutment crowns of monolithic LDC were fabricated. Of these, 24 were artificially aged using three different protocols up to a 20 year simulation (1.2 × 106, 2.4 × 106, 4.8 × 106 chewing cycles, thermocycling), a control group underwent no artificial aging (n &#61; 8, N &#61; 32). Load-to-failure tests were conducted for all specimens, and failure values were compared (P < .05). All specimens passed in vitro aging. Mean failure load values between 532.6 and 562.8 N were found but did neither differ significantly among the test groups nor from the control group. Within the limitations of this in vitro pilot study, hybrid abutment crowns manufactured from monolithic LDC seem to offer appropriate long-lasting mechanical stability over a simulation period up to 20 years. The failure values and complication pattern seem to be independent of several aging protocols in this test set-up.

Implant-Supported Single Crowns With Hybrid Abutments Show Favorable Short-Term Clinical Outcomes

Clinical performance of implant-supported single hybrid abutment crown restoration: A systematic review and meta-analysis. Journal of Prosthodontic Research. Zhang, M., Ho, D. K. L., Pelekos, G., & Fok, M. R. JPR_D_22_00279. SOURCE OF FUNDING: No funding was received. Systematic review and meta-analysis.

Fabrication trueness and internal fit of hybrid abutment crowns fabricated by using additively and subtractively manufactured resins

ObjectivesTo evaluate the fabrication trueness and internal fit of hybrid abutment crowns fabricated by using additively and subtractively manufactured restorative materials. MethodsA maxillary first premolar crown with a screw access channel was designed onto a digitized master titanium base abutment. This file was used to fabricate 40 crowns additively (Crowntec (CT) and VarseoSmile Crown Plus (VS)) or subtractively (Brilliant Crios (BC) and Vita Enamic (EN)) (n = 10). Crowns were digitized with an intraoral scanner and root mean square method was used to evaluate fabrication trueness. Master abutment and the crowns when seated on the abutment were also digitized with the same intraoral scanner and triple scan method was used to evaluate internal fit. Data were analyzed either with 1-way ANOVA (surface deviations) or Kruskal-Wallis (internal fit) tests (α= 0.05). ResultsCT had the highest overall, external, and marginal surface deviations (P≤.030), whereas BC had the lowest external (P≤.001) and VS and EN had the lowest marginal surface deviations (P≤.007). BC had the highest intaglio surface deviations (P<.001). BC and EN had higher average gap values CT and VS (P≤.006); however, the differences within additively and subtractively manufactured materials were nonsignificant (P≥.858). ConclusionsOne of the tested additively manufactured resins (CT) resulted in mostly lower trueness than that of other materials. However, deviations at the intaglio and marginal surfaces were generally small and the maximum mean difference among test groups when average gap was considered was 17.4 µm. Therefore, clinical fit of hybrid abutment crowns fabricated with tested materials may be similar.

Influence of Restorative Material on the Distribution of Loads to the Bone in Hybrid Abutment Crowns-In Vitro Study.

Background: The objective of this study was to evaluate the load transmitted to the peri-implant bone by seven different restorative materials in single-unit rehabilitations with morse taper implants using a strain gauge. Materials: In a polyurethane block that simulated type III bone, a morse taper platform implant was installed (3.5 × 11 mm) in the center and 1 mm below the test base surface, and four strain gauges were installed around the implant, simulating the mesial, distal, buccal and lingual positions. Seven similar hybrid abutment crowns were crafted to simulate a lower premolar using different materials: 1-PMMA; 2-glass ceramic over resin matrix; 3-PEEK + lithium disilicate; 4-metal-ceramic; 5-lithium disilicate; 6-zirconia + feldspathic; 7-monolithic zirconia. All groups underwent axial and oblique loads (45 degrees) of 150 N from a universal testing machine. Five measurements (n = 5) were performed with each material and for each load type; the microdeformation data underwent statistical analysis. The data were obtained in microdeformation (με), and the significance level was set at p ≤ 0.05. Results: There was no statistically significant difference in the evaluation among the materials under either the axial load or the oblique load at 45 degrees. In turn, in the comparison between axial load and oblique load, there was a difference in load for all materials. Conclusion: The restorative material did not influence the load transmitted to the bone. Furthermore, the load transmitted to the bone was greater when it occurred obliquely at 45° regardless of the material used. In conclusion, it appeared that the different elastic modulus of each material did not influence the load transmission to the peri-implant bone.

Cumulative 10-year performance of endodontically treated teeth with prosthetic restorations of base metal alloy double crowns with friction pins—a retrospective study

ObjectivesThis 120-month follow-up study aimed to investigate the complication rate of abutment teeth after endodontic pretreatment with base metal alloy double crowns with friction pins.Materials and methodsA total of 158 participants (n = 71, 44.9% women) aged 62.5 ± 12.7 years with 182 prostheses on 520 abutment teeth (n = 459, 88.3% vital) were retrospectively analyzed between 2006 and 2022. Of the endodontically treated abutment teeth, 6.9% (n = 36) were additionally treated with post and core reconstructions. Cumulative complication rates were calculated using the Kaplan–Meier estimator and log-rank test. In addition, Cox regression analysis was performed.ResultsThe cumulative complication rate at 120 months for the entire set of abutment teeth was 39.6% (confidence interval [CI]: 33.0–46.2). Endodontically treated abutment teeth (33.8%; CI: 19.6–48.0) were found to have a significantly higher cumulative fracture rate than vital teeth (19.9%; CI: 13.9–25.9, p < 0.001). Endodontically treated teeth restored with post and core reconstructions (30.4%; CI: 13.2–47.6) showed a nonsignificant lower cumulative fracture rate than that of teeth with root fillings only (41.6%; CI: 16.4–66.8, p = 0.463).ConclusionsHigher 120-month cumulative fracture rates were observed in endodontically treated teeth. Comparable performance was observed in teeth with post and core reconstructions compared to teeth with root fillings only.Clinical relevanceIf endodontically treated teeth are used as abutments for double crowns, the risk of complications from these teeth should be considered when planning treatment and communicating with the patient.