Evaluation of colour change, marginal adaptation, fracture strength, and failure type in maxillary and mandibular premolar zirconia endo-crowns.

OBJECTIVES: The objective of this in vitro study was to evaluate the effects of different preparation designs on the mean colour change (ΔE*), marginal adaptation, fracture resistance, and fracture types of maxillary and mandibular premolar endocrowns (ECs). METHODOLOGY: A total of 40 extracted maxillary and mandibular premolars were treated endodontically, and each type was subdivided according to the remaining axial height (remaining walls on all surfaces; 2-4 mm) and 2 mm inside the pulp chamber. Specimens were immersed in coffee for 14 days, ΔE* was determined, marginal adaptation was observed, fracture forces test was conducted, and the samples were examined visually at 10× magnification to evaluate failure type and identify fracture origin. The data were entered and analyzed using Statistical Package for Social Sciences, and significance between and within groups was evaluated through ANOVA. The p-value ≤ 0.05 was considered statistically significant. RESULTS: The ΔE* values of the maxillary premolar with 2 mm axial height were the highest (6.8 ± 0.89 units), whereas the lowest value was observed in the mandibular premolar with 4 mm axial height (2.9 ± 0.53 units). Significant differences (p < 0.05) in teeth and design were observed. The marginal adaptation of the mandibular premolar with 4 mm axial height was the highest (30.20 ± 1.53 µm), whereas the lowest marginal adaptation was observed in the maxillary premolar with 2 mm axial height (14.38 ± 0.99 µm), and the difference was statistically significant (p < 0.05). The maximum fracture force was observed in maxillary premolars with 2 mm axial height (2248.15 ± 134.74 N), and no statistically significant difference (p = 0.07) was observed between maxillary and mandibular premolars at 4 mm axial height. CONCLUSION: The recorded ΔE* values of the ECs were within clinically acceptable values or slightly higher, and the marginal adaption values were within acceptable and recommended clinical values in µm. EC preparation with 2 mm axial height in both arches recorded the highest fracture forces. Type III (split fracture) failure was recorded as the highest in the maxillary and mandibular premolar ECs with different axial wall heights.

Fracture resistance, marginal and internal adaptation of innovative 3D-printed graded structure crown using a 3D jet printing technology.

PURPOSE: This in vitro study aimed to create a graded structured dental crown using 3D printing technology and investigate the fracture resistance and the adaptation of this new design. MATERIALS AND METHODS: A dental crown with a uniform thickness of 1.5 mm was designed, and the exported stereolithography file (STL) was used to manufacture 30 crowns in three groups (n = 10), solid (SC), bilayer (BL), and multilayer (ML) crowns using  3D jet printing technology. Marginal and internal gaps were measured using the silicone replica technique. Crowns were then luted to a resin die using a temporary luting agent and the fracture resistance was measured using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used to compare the fracture resistance and the adaptation of crowns at a significance level of 0.05. RESULTS: Mean marginal and internal gap of the ML group were 80 and 82 mm, respectively; which were significantly (p < 0.05) smaller than BL (203 and 183 mm) and SC (318 and 221 mm) groups. The SC group showed the highest mean load at fracture (2330 N) which was significantly (p < 0.05) higher than the BL (1716 N) and ML (1516 N) groups. CONCLUSION: 3D jet printing technology provides an opportunity to manufacture crowns in a graded structure with various mechanical properties. This study provided an example of graded structured crowns and presented their fracture resistance. SC group had the highest fracture resistance; however, ML had the best marginal and internal adaptation.

Restoration with a posterior CAD/CAM onlay after failure of a direct resin-based composite restoration: a case report.

A conservative approach to restoration assists in preserving the remaining tooth structure of extensively destroyed vital teeth. This case report describes a single-appointment chairside technique for placement of ceramic restorations in posterior teeth. A patient presented for treatment of her mandibular right first molar, which had a fractured resin-based composite restoration. Due to the presence of vital pulp, extent of the restoration, and presence of caries in the tooth, the following treatment plan was proposed: placement of a lithium disilicate glass-ceramic onlay fabricated with a computer-aided design/computer-aided manufacturing workflow. After the dentist removed the restoration and performed selective caries removal, structural analysis guided the reduction of the buccal cusps. Immediate dentin sealing was performed with a 2-step self-etching adhesive system, and a 1-mm-thick layer of flowable resin-based composite was placed as a resin coating. A digital impression was obtained, the onlay restoration was designed, and a lithium disilicate block was milled and subsequently crystallized. When the onlay was completed, the tooth preparation was sandblasted, selectively etched, and coated with a universal adhesive. The intaglio surface of the onlay was cleaned and primed, the onlay was bonded with dual-cure resin cement, and occlusal adjustments were completed. Follow-up examinations at 1 and 4 months revealed the clinical success of the case. From start to finish, it takes approximately 2.5 hours to produce a single-appointment chairside restoration. The technique used in this case offers a fast-paced workflow that is comfortable and practical for the patient and provides a predictable clinical outcome without the need for a temporary restoration.

The survival and clinical performance of anterior composite resin restorations and posterior indirect and cast restorations used to treat generalised tooth wear.

Objective To evaluate the survival and clinical performance of restorative materials used in the rehabilitation of generalised severe tooth wear within a UK NHS postgraduate teaching hospital.Methods The clinical performance of 527 restorations on 20 patients with generalised severe tooth wear was reviewed after a mean period of five years. Anterior teeth were restored with direct composite resin and posterior teeth with indirect restorations. The study used the modified United States Public Health Service criteria for restoration assessment. Survival of the restorations was analysed using Kaplan-Meier survival curves, the log-rank test and the Cox proportional hazards regression analysis.Results The sample included 20 participants: 13 men and 7 women, with a median age of 51.8 years (range: 33-73 years). The median survival time for all restorations was 11.3 years when major failures were considered and 5.9 years for restorations when all types of failure were considered. A median survival time of 5.9 years for composite resin restorations and over seven years for cast restorations was found when considering all failures. Composite resin restorations commonly failed as a result of fracture, wear and marginal discolouration. Factors significantly influencing restoration survival were the material used, aetiology, incisal relationship and tooth location. The biological complications associated with this treatment regime were rare. Patient satisfaction remained generally high, with greatest dissatisfaction related to treatment time.Conclusions The use of anterior composite resin with posterior indirect restorations to treat generalised severe tooth wear is a viable treatment modality with very few major complications.

Evaluation of vertical marginal discrepancy and load-to-failure of monolithic zirconia and lithium disilicate laminate veneers manufactured in different thicknesses.

OBJECTIVES: This study aimed to evaluate the feasibility of monolithic zirconia laminate veneers (MZLV) compared to lithium disilicate laminate veneers (LDLV). MATERIALS AND METHODS: Sixty resin replicas, each prepared with depths of 0.5 mm, 0.7 mm, and 1 mm, were produced using a 3D printer from acrylic teeth. Laminate veneers of these thicknesses were milled from pre-sintered monolithic zirconia (3rd generation) and lithium disilicate blocks. The intaglio surface of MZLV was treated with air abrasion using 110 µm diameter silica-modified aluminium oxide particles and ceramic primer, while LDLV was etched with etchant gel and treated with the ceramic primer before cementation with resin cement. Vertical marginal discrepancy (VMD) was assessed using a stereomicroscope, and a load-to-failure test was conducted using a universal testing machine. Failure modes were evaluated macroscopically on fractured surfaces. Data were analysed statistically using Two-way ANOVA and Bonferroni correction (α = 0.05). RESULTS: LDLV samples exhibited significantly larger VMD compared to MZLV samples across all thicknesses, especially in cervical, palatal, and mean data. Within the LDLV group, load-to-fracture values for 0.7 mm and 1.0 mm thicknesses were similar, whereas for 0.5 mm thickness, it was significantly lower. In the MZLV group, load-to-fracture values were lower for 0.7 mm and 1.0 mm thicknesses compared to LDLV, but higher for 0.5 mm thickness. CONCLUSIONS: Material choice and restoration thickness significantly influence laminate veneer restorations' success. MZLV generally exhibits superior vertical marginal fit compared to LDLV, with varying load-to-failure values across different thicknesses. Clinical management of debonding in MZLV is simpler compared to restoration fracture in LDLV. CLINICAL RELEVANCE: Considering clinical factors, MZLV may be a preferable option to LDLV for this restoration with the thickness of 0.5 mm.

Importance of local and systemic factors in preventing implant displacement in the mandibular body: a scoping review of existing literature.

BACKGROUND: The aim of this research was to analyse the current literature on displaced dental implants in the mandibular body, including local and systemic variables related to their cause, and to identify the most frequent location. METHODS: The study conducted a search of three databases (Pubmed, Scopus, and Web of Science) using specific index terms such as 'dental implant', 'displacement', 'dislocation', 'displaced', and 'mandible'. The analysis focused on the direction of displacement and the characteristics of the bone tissue (bone quality, density, and quantity) in cases where dental implants were displaced. RESULTS: A total of 371 articles were obtained. Thirteen of these articles were selected and read in full. To define bone quality, the Lekholm and Zarb classification, modified by Rosas et al., was used. The type II-B bone, which is characterized by thick cortical bone surrounding cancellous bone with extremely wide medullary spaces, presented the largest number of complications. Twenty-two cases were found in which the displacement direction was horizontal. Of these, four were displaced vestibularly, fourteen lingually, and four remained in the center. Additionally, 24 cases presented vertical displacement, with 12 displaced towards the inferior border of the mandible, 9 towards the middle or adjacent to the inferior dental nerve canal, and 3 above the inferior dental nerve canal. CONCLUSION: The accidental displacement of implants within the mandibular body is associated with various risk factors, including the characteristics of the bony trabeculum and the size of the medullary spaces. It is reasonable to suggest that only an adequate pre-surgical diagnostic evaluation, with the help of high-resolution tomographic images that allow a previous evaluation of these structures, will help to have better control over the other factors, thus minimizing the risk of displacement.

Bulk-flow composites in paediatric dentistry: long term survival of posterior restorations. A retrospective study.

Dental decay is a prevalent bacterial disease affecting a significant percentage of children globally. In paediatric dentistry, various materials are available for restoring deciduous teeth, addressing both functional and aesthetic concerns. However, paediatric dentists encounter challenges related to patient compliance, limited working time, and material handling. This study aims to observe the survival rate of bulk-fill composite restorations in paediatric patients over a five-year follow-up. A total of 198 patients aged 0 to 12 years underwent 673 class II restorations on deciduous first molars (1M) and second molars (2M). All restorations were conducted performed by 1 Pediatric DDS resident students from the Paediatric Dentistry Department (Padova University), utilizing using different isolation techniques. Bulk-fill composite restorations were evaluated over a five-year follow-up, and data were collected by a single investigator. After five years, 177 patients and 611 restorations were assessed. The retention rate was higher in primary second molars than in first molars, with fewer marginal dyschromies and less formation of secondary caries. The overall failure rate was higher in primary first molars and primary lower second molars. Bulk-fill composites demonstrated significantly positive performance in terms of retention, maintenance, and marginal dyschromies. Bulk-fill composites are promising materials of choice in paediatric dentistry due to their easy handling and favorable properties. Further research is necessary to compare high and low viscosity bulk-fill composites and assess the impact of different variables on restoration success.

Fatigue methods for evaluating translucent dental zirconia.

OBJECTIVE: To investigate fatigue methods for the evaluation of translucent zirconia and to associate in vitro failures with clinically reported ones. DATA: Studies published in English that used fatigue tests on dental translucent zirconia. SOURCES: Two databases (MEDLINE/PubMed and Scopus) were electronically searched without any restriction on year of publication. STUDY SELECTION: A total of 4555 studies were identified. After removal of duplicates (78) and irrelevant articles (4316) that did not meet the inclusion criteria, 161 articles were considered eligible based on their titles and abstracts. These articles were fully read, leading to the inclusion of 41 studies in the review. RESULTS: The most widely used fatigue method for evaluation of translucent zirconia was step-stress (18 articles), followed by staircase (seven articles), and step-wise (two articles). Most studies had been conducted in a wet environment with the use of a stainless steel piston to apply load to cemented structures on a dentin-like substrate. Most fracture analyses indicated the fracture originated on the cementation or contact surface where the load was applied. Moreover, studies that utilized anatomical structures (dental crowns) reported fractures starting at the cervical margin of the crowns. CONCLUSION: Most studies used the step-stress method. Only three studies reported failures similar to those found in clinical trials that used translucent zirconia restorations. CLINICAL SIGNIFICANCE: The study findings can assist on correlating clinical failures to the ones observed in vitro.

Longevity of acrylic and cobalt-chromium removable partial dentures-A ten-year retrospective survival analysis of 1246 denture-wearing patients.

OBJECTIVES: to assess the survival rates of removable partial dentures (RPDs) and identify factors impacting their longevity. METHODS: electronic health records were retrieved of patients aged ≥18 who received RPDs between 2010 - 2021 with a follow-up of ≥ three months. Data extracted included demographics, medical history, dental charting, periodontal screening and recording scores, prostheses details and related interventions, including new dentures/denture remakes, and maintenance. Multivariate Mixed-Effect Cox regression was performed to identify potential RPD survival risk factors. Reduced model selection was reached using a backward step-down by comparing the performance of these multivariable models using the ANOVA test. RESULTS: 1893 RPDs from 1246 patients were included, with a median follow-up of 21.8 months (range from 3 to 131.3 months). Three hundred and twelve patients received a maxillary RPD, 460 received a mandibular RPD, and the remaining 474 patients received both maxillary and mandibular RPDs. Metal-based RPDs had a median survival of 73 months (95%CI: 70 - 82) versus 45 months (95% CI: 37-67) for acrylic ones. Multivariable mixed effects Cox model showed that the lifespans of RPDs were longer amongst patients receiving more maintenance care within three months [Hazards Ratio (HR)=0.89 (0.83, 0.96)] and after three months [HR=0.53 (0.46, 0.61)] of denture delivery, patients wearing both maxillary and mandibular RPDs [HR=0.67 (0.52, 0.87)], and patients receiving metal-based RPDs [HR=0.31 (0.23, 0.42)]. CONCLUSIONS: Metal-based dentures, dual arch restoration, and increased maintenance positively impact the survival of RPDs. CLINICAL SIGNIFICANCE: Adapting consent and warranty practices is advised to reflect RPD performance variations.

Fracture Resistance and Failure Mode of Polyethylene Fiber-reinforced Resin-based Restorations in Structurally Compromised Premolars: an in Vitro Study.

OBJECTIVE: To evaluate the effect of polyethylene fiber-reinforcement on the fracture resistance and fracture mode of extensive resin-based composite (RBC) restorations in structurally compromised maxillary premolars. METHODS AND MATERIALS: Maxillary premolars (54) with specific dimensions and extracted for orthodontic reasons were used. Following mesio-occluso-distal (MOD) cavity preparation and endodontic access, teeth were randomly assigned to one of three restorative protocols (n=18): RBC applied incrementally (I) or reinforced with woven polyethylene fibers (Ribbond) placed horizontally (H) or U-shaped (U). Restored teeth were stored for 45 days in distilled water at 37°C and then loaded monotonically until fracture. Half of the specimens in each group received axial loading (A) and the other half was loaded paraxially (PA). Fracture load data was assessed using two-way analysis of variance and Tukey's post hoc test for multiple comparisons (α=0.05). The fracture initiation and propagation path were analyzed using stereomicroscopy and scanning-electron microscopy. RESULTS: No significant differences were observed for the fracture strength among loading configurations, except for groups IA (825 N) and HA (553 N). Fracture initiated and propagated mainly at and through the RBC restoration in the I group, whereas a shift to the interface was observed in both polyethylene fiber-reinforced groups. Blocking and bridging of cracks were identified around the fibers, especially in specimens of group U. CONCLUSIONS: Incorporation of woven polyethylene fibers to reinforce extensive MOD resin-based composite restorations on endodontically treated premolars reduced the occurrence of cohesive fractures in the restorative material but was unable to increase the fracture resistance of the affected teeth.

Performance of Bonded Lithium Disilicate Partial-coverage Crowns in the Restoration of Endodontically Treated Posterior Teeth: An Up to Seven-Year Retrospective Study.

OBJECTIVES: To evaluate the clinical performance of adhesively bonded lithium disilicate glass-ceramic (LDG) partial-coverage crowns in restoring posterior endodontically treated teeth (ETT). METHODS AND MATERIALS: A total of 121 morphologically compromised posterior ETT were restored with LDG partial-coverage crowns between October 2015 and January 2018. The restorations were fabricated in the laboratory or at the chairside. Two adhesive systems and resin cements were used to cement the restorations. Tooth and restoration survival rates were calculated. The restorations were evaluated clinically using the modified United States Public Health Service (USPHS) criteria for an observation period of 5-7 years. The Cox proportional hazards model was used to estimate relative failure risks such as tooth type, resin cements, gender, and sleep bruxism. The standard chi-squared test was used to compare the survival of different tooth types for significant differences (α=0.05). In addition, survival probability was calculated using the Kaplan-Meier algorithm. RESULTS: Among seven failed cases, one was a tooth fracture, and six were restoration fractures. According to the Kaplan-Meier analysis, the estimated survival rate of the teeth was 99% for seven years, while the estimated survival rate of the restorations was 94.8% for 5 years and 92.8% for 7 years. Tooth type and resin cements did not influence restoration survival rates (p>0.05), while sleep bruxism and male patients might increase the risk of failure (p<0.05). CONCLUSIONS: The indirect adhesively bonded LDG partial-coverage crowns of posterior ETT exhibited favorable clinical outcomes. Ceramic fracture was the most common failure pattern.

Evaluation of fracture resistance and marginal fit of implant-supported interim crowns fabricated by conventional, additive and subtractive methods.

BACKGROUND: Interim crowns are utilized for restoring implants during and after the process of osseointegration. However, studies on adaptation and fracture strength of implant-supported interim crowns are rare. AIM OF THE STUDY: The aim of this in vitro study is evaluating marginal fit and fracture resistance of conventional, subtractive, and additive methods of fabricating implant-supported interim crowns. MATERIALS AND METHODS: An implant was placed in an epoxy resin model with a missing first molar. A scan body was attached, and scanned with an intraoral scanner (IOS), the STL file was used to fabricate eighteen master models with standardized implant digital analogue spaces. The digital analogues and their corresponding abutments were attached to the master models and scanned with the IOS, the STL files were used to fabricate eighteen crowns using three different techniques (n = 6): conventional (CR); from Autopolymerizing composite resin, subtractive (SM); milled from PMMA resin blanks, and additive (AM); from 3D printed resin material. The crowns were fitted and cemented on their corresponding abutments and subjected to cyclic loading and thermocycling. The marginal fit was evaluated using a stereomicroscope. The crowns were then loaded until fractured in a universal testing machine. The Shapiro-Wilk and the Kolmogorov-Smirnov tests revealed that data of Marginal gap was non-parametric. Kruskal-Wallis test followed by the Dunn test was used (α = 0.05). While data of Fracture resistance test was parametric. ANOVA (F-test) was used followed by the Tukey test (α = 0.05). RESULTS: For marginal gap, a significant difference was shown between the study groups (P = .001) according to Kruskal-Wallis test. Groups SM and AM had significantly lower marginal gap values compared to group CR (P = .003). No significant difference was found between groups SM and AM (P = .994). For fracture resistance, One-way ANOVA revealed a significant difference in fracture resistance between study groups (P < .001). Group SM had significantly higher fracture strength followed by group AM and group CR (P = .001). CONCLUSIONS: Group SM and AM showed better marginal adaptation than group CR. Group SM showed superior fracture resistance compared to other groups. All study groups showed acceptable marginal gap and fracture resistance.

Mechanical strength of stock and custom abutments as original and aftermarket components after thermomechanical aging.

OBJECTIVES: The study aimed to assess the impact on the mechanical strength and failure patterns of implant-abutment complexes of choosing different abutment types, designs and manufacturers, aiding in selecting the optimal restorative solution. Stock and custom abutments from original and aftermarket suppliers were subjected to thermomechanical aging. MATERIAL AND METHODS: Stock and custom abutments from the implant manufacturer (original) and a aftermarket supplier (nonoriginal) were connected to identical implants with internal connection. Custom abutments were designed in a typical molar and premolar design, manufactured using the workflow from the respective suppliers. A total of 90 implants (4 mm diameter, 3.4 mm platform, 13 mm length) equally divided across 6 groups (three designs, two manufacturers) underwent thermo-mechanical aging according to three different regimes, simulating five (n = 30) or 10 years (n = 30) of clinical function, or unaged control (n = 30). Subsequently, all samples were tested to failure. RESULTS: During aging, no failures occurred. The mean strength at failure was 1009N ± 171, showing significant differences between original and nonoriginal abutments overall (-230N ± 27.1, p < .001), and within each abutment type (p = .000), favoring original abutments. Aging did not significantly affect the failure load, while the type of abutment and manufacturer did, favoring original and custom-designed abutments. The most common failure was implant bending or deformation, significantly differing between original and nonoriginal abutments and screws. All failure tests resulted in clinically unsalvageable implants and abutments. CONCLUSIONS: Within the limitations of this study, original abutments exhibited a higher mechanical strength compared to the nonoriginal alternative, regardless of the amount of simulated clinical use. Similarly, custom abutments showed higher mechanical strength compared to stock abutments. However, mechanical strength in all abutments tested was higher than average chewing forces reported in literature, thus components tested in this study can be expected to perform equally well in clinical situations without excessive force.

Is routine antibiotic prophylaxis warranted in dental implant surgery to prevent early implant failure? - a systematic review.

BACKGROUND: The question of whether antibiotic prophylaxis should be administered routinely for dental implant surgery is unresolved. Despite the lack of conclusive supportive evidence, antibiotics are often administered to reduce the risk of infection, which could lead to early implant failure. Increasing antibiotic resistance is a major concern and it is therefore important to reduce the overall use of antibiotics, including in dentistry. The aim of the present systematic review and meta-analysis was to evaluate the efficacy of preoperative antibiotics in preventing early implant failure, in overall healthy patients undergoing dental implant surgery. METHODS: An electronic search was undertaken of PubMed (Medline), Web of Science and the Cochrane Library up to October 1st, 2023, to identify randomized clinical trials (RCTs). All RCTs comparing antibiotic prophylaxis with no antibiotics/placebo in overall healthy patients receiving dental implants were included. The primary outcome was patients with early implant failure. Risk of bias was assessed, data were extracted, a meta-analysis was done, and GRADE certainty-of-evidence ratings were determined. The risk ratio (RR), the risk difference (RD) and 95% confidence intervals (CI) were estimated. RESULTS: After removal of duplicates, 1086 abstracts were screened, and 17 articles were reviewed in full text. Seven RCTs with moderate or low risk of bias and with a total of 1859 patients and 3014 implants were included in the meta-analysis. With reference to early implant failure at patient level, the meta-analysis failed to disclose any statistically significant difference (RR: 0.66, 95% CI: 0.30-1.47) between antibiotic prophylaxis and a placebo. The risk difference was -0.007 (95% CI: -0.035-0.020) leading to a number needed to treat (NNT) of 143. CONCLUSION: Antibiotic prophylaxis for dental implant surgery does not seem to have any substantial effect on early implant failure ( ). The results do not support routine antibiotic prophylaxis for dental implant surgery.

Influence of remaining coronal tooth morphology with resin abutment and fiber post on static and dynamic fracture resistances.

This study aimed to clarify the fracture resistance of resin abutments built on endodontically treated roots with the remaining coronal teeth via static and cyclic loading tests. Endodontically treated bovine roots, which had a remaining coronal tooth covered with an occupied area for a quarter and half of the circumference at the tensile side or covered the circumference at both the tensile and compressive sides, were fabricated to build up to the resin abutment. Fracture resistance was evaluated via static and cyclic loading tests by applying a load of 30° to the tooth axis. Half of the circumference of the remaining coronal tooth showed a significantly higher static fracture load and survival rate. The remaining coronal tooth on the compressive side improved the dynamic fracture resistance associated with severe fractures. The occupied area and location of the remaining coronal tooth affected the static and dynamic fracture resistances.

[Constructive complications in dental implantology (clinical case series)]. / Konstruktivnye oslozhneniya v dental'noi implantologii (na primere klinicheskikh sluchaev).

The aim the study. Analyze errors in planning orthopedic treatment using dental implants using the example of clinical cases. MATERIALS AND METHODS: Two patients are presented who applied for a consultation at the orthopedic and surgical department of the Federal State Budgetary Institution National Medical Research Center Central Research Institute of Chronic and Peripheral Surgery of the Russian Ministry of Health regarding a fracture of a previously installed orthopedic structure on an implant. For diagnostic purposes, computed tomography was performed to determine the condition of the implants and teeth of the upper and lower jaws. RESULTS: The patients were found to have: a fracture of an implant 4.0*10 with a single orthopedic structure in the area of tooth 4.6 (the patient did not undergo restoration of the missing tooth 4.7 in the presence of an antagonist), a fracture of small diameter implants (3.5*9) in the area of 3.6, 3.7, prosthetic combined orthopedic crowns. CONCLUSIONS: During surgical and orthopedic treatment of patients, it is necessary to strictly follow the instructions developed by the manufacturer of dental implants and the STaR recommendations.

Performance of a novel self-adhesive bulk-fill composite hybrid in endodontically treated maxillary premolars: analysis of fracture resistance and failure mode.

This study evaluated the fracture resistance of endodontically treated maxillary premolars restored with a new self-adhesive composite hybrid material (Surefil one [SO]) using different protocols. A total of 72 maxillary premolars were divided into 6 groups (n = 12). The control group included intact teeth, and the other 5 groups included teeth in which disto-occlusal cavities were prepared and endodontic treatment was performed. The prepared cavities were assigned to groups that were based on the restorative procedures: bulk-fill group, universal adhesive plus conventional bulk-fill composite resin plus a layer of conventional composite resin; SO-SC group, self-cured SO; SO-LC group, light-cured SO; SO-UA group, universal adhesive plus SO; or SO-core group, a 4.0-mm layer of SO covered by a layer of conventional composite resin. Specimens in each group underwent thermocycling and load cycling to test the fracture strength and fracture mode. The results were analyzed using analysis of variance and the Tukey test (α = 0.05). The SO-core group showed the highest mean (SD) fracture resistance, 959.9 (171.8) N, among the restored groups. The SO-core group did not differ significantly from the control group (P > 0.05) but did show significantly higher strength than all other test groups (P < 0.05) except SO-SC (P = 0.364). No significant differences were found between the bulk-fill, SO-SC, SO-LC, and SO-UA groups (P > 0.05). The SO-core group showed the highest number of unrestorable fractures, while the main fracture mode for the other groups was restorable fracture. Although the use of SO as a core material restored the fracture strength of endodontically treated premolars to the level of intact teeth, it also resulted in a higher incidence of unrestorable fractures. The SO-SC group demonstrated a high fracture resistance comparable to that of the SO-core group and had a greater tendency to experience restorable fractures.

Effect of different design and surface treatment on the load-to-failure of ceramic repaired with composite.

Glass ceramics are widely used to manufacture esthetic veneers, inlays, onlays, and crowns. Although the clinical survival rates ofglass-ceramic restorations arefavorable,fractures or chips are common. Certain cases can be repaired with direct composite. AIM: The aim of this study was to investigate the interaction effect of different designs and surface treatments on the load-to-failure of lithium disilicate glass-ceramic repaired with nanofilled composite. MATERIALS AND METHOD: Lithium-disilicate glass-ceramic slabs (IPS e.max Press, Ivoclar Vivadent) with three different designs of the top surface (flat, single plateau, or doubleplateau) (n=U) received 'no treatment', '5% HF etching', or "AI2O3 sandblasting". HF-etched and sandblasted slabs also received silane and universal one-step adhesive application. All slabs were incrementally repaired with nanofilled composite (Filtek Z350, 3M ESPE) up to6 mm above the highest ceramic top plateau. Specimens were stored in artificial saliva at 37 °C for 21 days and then subjected to 1,000 thermocycles between 5 and 55 °C. The interface composite-ceramic of each specimen was tensile tested until failure in a universal testing machine and the mode of failure was determined under a stereomicroscope. The ceramic surface morphology of one representative tested specimen from each subgroup (design/surface treatment) was observed through scanning electron microscopy (SEM). RESULTS: Regardless of ceramic design, the absence of surface treatment resulted in significantly lower load-to-failure values. No significant differences in load-to-failure values were observed between HF-etched and sandblasted specimens for the flat design; however, HF etching resulted in significantly higher load-to-failure values than sandblasting for both single plateau and double plateau designs. The majority (60%) of HF-etched specimens with single plateau or double plateau presented mixed failures. SEM photomicrographs showed that HF-etched specimens had smoother surfaces than sandblasted specimens. CONCLUSION: The surface treatment of a defective lithium disilicate glass-ceramic restoration has more influence than its macroscopic design on the retention of the composite repair. HF etching seems to provide higher bond strength to the composite repair.

Embora fraturas e lascamento de restauragoes vitrocerámicas sejam comuns, alguns casos podem ser reparados com compósito direto. OBJETIVO: investigar o efeito da interagao de diferentes formas e tratamentos de superficie na carga de ruptura de uma vitrocerámica reforgada com dissilicato de litio reparada com compósito nanoparticulado. MATERIAIS E MÉTODOS: A superficie superior de espécimes de vitroceramica (IPS e.max Press, Ivoclar Vivadent) foi preparada com tres formas (plana, plato único, ou duplo) e recebeu (n=11): 'nenhum tratamento', 'condicionamento com ácido hidrofluoridrico 5%', ou 'jateamento com AfOf. Ambos espécimes condicionados e jateados receberam silano e adesivo universal. Todos os espécimes foram reparados incrementalmente com compósito (Filtek Z350, 3M ESPE) até6 mm acima do plato cerámico mais alto, armazenados em saliva artificial á 37 °C por 21 dias, e submetidos á 1.000 termociclos (5 e 55 °C). A interface compósito-cerámica de cada amostra foi testada á tragao até sua falha em máquina universal e o modo de falha foi determinado com estereomicroscópio. A morfologia da superficie de uma amostra representativa de forma/tratamento de superficie foi observada através de microscopia eletronica de varredura (MEV). RESULTADOS: Independentemente da forma ceramica, a ausencia de tratamento superficial resultou em valores de carga de ruptura significativamente menores. Nao foi observada differenga significativa entre os espécimes planos condicionados ou jateados; no entanto, o condicionamento resultou em valores significativamente maiores que o jateamento para espécimes com plato único e duplo. A maioria (60%) dos espécimes condicionados e com plato único ou duplo apresentou falhas mistas. Imagens SEM demonstraram rugosidade superficial mais regular dos espécimes condicionados que os jateados. CONCLUSÕES: O tratamento superficial de uma restauragao defeituosa de vitrocerámica reforgada por dissilicato de litio tem maior influencia na retengao do reparo de compósito do que sua forma macroscópica; ainda, o condicionamento com ácido hidrofluoridrico parece proporcionar maior resistencia de uniao ao reparo com compósito.