AIM: This study deeply investigates the effect of dental implant threading and material selection on the mandibular bone under two different crown materials (Translucent Zirconia and Porcelain fused to metal). METHODS: Two different designs of single piece dental implants were supporting dummy crown above simplified bone geometry in two finite element models. Models components were created by general-purpose CAD/CAM engineering package and then assembled inside ANSYS before meshing and assigning materials. Compressive loading of 100 N and 45º oblique loading of 50 N were tested. RESULTS: Twenty-four case studies were analysed, and their results were compared. Micro thread reduces implant maximum Von Mises stress by about 50 to 70% than regular thread one. Oblique loading of 50 N will produce 4 to 5 times more maximum Von Mises values on implant body than 100 N vertical loading. Zero or negligible effect on the cortical bone was recorded when exchanging the tested crown material. Although titanium implant can also reduce cortical bone, Von Mises stress by 50 to 100% in comparison to reinforced PEKK (poly ether-ketone-ketone) or PEEK (poly-ether-ether-ketone). CONCLUSIONS: Reinforced PEKK and PEEK implants can represent a good alternative to titanium implants. Zirconia crown distributes the applied load better than Porcelain fused to a metal one. Regardless of the implant material, an implant with the micro thread has superior behaviour in comparison to a regular one. Zirconia crown above titanium implant with the micro thread may represent the best option for patient bone.

Background: The aim of the study is to assess the bonding of two repair methods for zirconia. Null hypothesis: Repair of zirconia with Cojet (3M Cojet sand, 68,411) and clearfil (clearfil REPAIR Kuraray Japan) has the same effect on the bond strength of zirconia restorations. Zirconia blocks were sliced before sintering into 28 samples (inCorisZI mono L), surface treated with two repair methods (Cojet and clearfil) then bonded to composite. Storage and thermocycling was done then loaded under shear until failure. Shear bond strength was collected and statistically analyzed. Graph pad Instat (Graph Pad, Inc.) software for windows was used for analyzing results. Results: It was found that COJ surface treatment recorded statistically non-significant higher shear bond strength mean value (8.45 ± 0.70 Mpa) than CLE surface treatment (7.67 ± 2.55 Mpa) as indicated by paired t-test. Conclusion: It was concluded that bond strength between composite resin and inCoris ZI mono L is the same in resistance to shear stresses after Cojet surface treatment and after Clearfil surface treatment.

Objective The aim of this randomized controlled trial was to assess the effect of cantilever design on implant-supported metallic fixed dental prostheses after 3 years of function. Patients and methods Twenty patients were randomly allocated to two groups: the 3 mm (TM) group (n=10), in which patients had one cantilever implant-supported fixed partial denture (CISFPD) with 3 mm distal extension measured from the most distal end of the fixture to the most distal end of the fixed partial denture; and the 5 mm (FM) group (n=10), in which patients had one CISFPD with 5 mm distal extension measured the same way as in the first group. All CISFPDs were supported by one implant (4.5 mm diameter, 10 mm length). The studied outcomes were survival, frequency of complication occurrence, bone loss, and pocket probing depth. All data were collected, tabulated, and statistically analyzed. Descriptive data were summarized as mean and SD, and differences were considered significant when P value up to 0.05. Results The total percentage of success with the CISFPD was 100% in the two groups. In this 3-year study, six noticed effects needing consequent treatment were found. In five patients (four in the FM group and two in the TM group). The amount of bone loss and pocket probing depth of implant abutments were the same in the two groups (P>0.05) and were within permissible limits. Conclusion After 3 years of assessment, the TM-CISFPD and FM-CISFPD showed accepted results. Studies on a larger number of patients will be needed to confirm the results of performance of implant-supported cantilever Fixed Dental Prosthesis.

Purpose: The aim of this study is to investigate the effect of the curing modes of two adhesive resin cements (Light cure mode of the Variolink Veneer, the self-cure mode and dual cure mode of the Multilink Automix) on the marginal leakage of lithium disilicate ceramic laminate veneers. Methods: A total number of forty eight extracted natural central incisors were prepared to receive ceramic laminate veneers, constructed using E-max ceramic divided into three groups cemented using three curing modes of two adhesive resin cements {light-cure mode of Variolink Veneer, self-cure mode of Multilink Automix and dual-cure mode of Multilink Automix adhesive resin cements} . Die penetration test was done using the methylene blue stain {qualitative assessment} for testing the die penetration along the tooth/ceramic interface. Results: Descriptive statistical analysis revealed that the self-curing mode recorded the significantly least degree of leakage compared to the light and dual cure modes. The self-cure mode recorded (0.1±0.3) which was significantly lower than light cure (1.2 ±0.9) and dual cure mode (1.2 ±0.4), there was no statistical significant difference between the later two curing modes. The self-cure mode of the resin cement is considered a more effective method for having the least marginal leakage at the tooth/ceramic interface. There was no difference between the light cure mode and the dual cure mode.

Statement of Problem. The performance of central incisor endocrowns with varying crown heights and different computer‐aided designs and computer‐aided manufacturing materials is not clear. Purpose. The aim of this study was to compare and assess the stress distribution and failure possibility of endodontically treated central incisor protected with endocrowns with different heights, with various CAD–CAM blocks such as IPS e.max CAD, Katana Zirconia, and Zolid Fx Zirconia. Materials and Methods. A root canal‐treated central incisor (plastic model) restored with an endocrown was scanned with a laser scanner to prepare a control model with a CAD software and then transferred to an FEA software. Proposed crown heights were 2, 4, and 6 mm. The model that was duplicated and restored with CAD–CAM blocks, IPS e.max CAD, Katana Zirconia, and Zolid Fx Zirconia were tested as endocrown materials. Bone geometry was simplified to be two coaxial cylinders in all models. Stress distributions under 50 N axial and oblique (with 135° angle from the vertical plane) loading were analyzed. Each model was then subjected to two occlusal loading conditions—the lingual slope of the incisal edge and the junction between incisal and middle thirds. Eighteen runs and calculations were performed to determine the endocrown height and material effect. Results. The results showed a minor or negligible effect of changing the endocrown material. Increasing endocrown height was shown to reduce stresses and deformations on most of the model components (bone, gutta‐percha, periodontal ligament, and endocrown), except root and cement. Differences in deformations and stresses between the two models of 4 and 6 mm were relatively smaller (ranged between 1% and 30%) compared to those between the 2 and 4 mm models (ranged between 10% and 400%). Conclusions. The material used to fabricate endocrowns did not show considerable effect on the underlying structures. However, the endocrown design (2, 4, and 6 mm height) was shown to affect all components of the studied systems. Increasing endocrown height is recommended for bone, periodontal ligaments, and endocrown body, as it reduces stresses and deformations. On the other hand, it dramatically increases stresses on the root and cement layer. Smaller endocrown sizes represent an acceptable treatment option when there is a healthy periodontal state, while using larger sizes will be more suitable when there is a periodontal compromise with bone loss.

OBJECTIVE: The aim of this in vitro study was to assess the effect of obturation technique and cementation timings on the bonding of fibre-reinforced posts to the root canal walls. METHODS: Twenty extracted teeth were randomly allocated to two groups according to the obturation technique and cementation timing. Central incisors with single canals were used after being decoronated. Every extracted tooth of the {vertical compaction group} (VC) group (n = 10) had been obturated using the {E & Q plus obturation system} with posts cemented in the same day; The other (CO) conventional group (n = 10) teeth were obturated using the conventional lateral compaction technique and posts cemented after one week. “SF“ Fiber posts were used after bonding and cementation using Rely X ARC resin cement with all the endodontically treated teeth. The push-out test was performed in a universal testing machine. Data were analysed by 2 way analysis of variance with Statistical significance was set to 0.05. RESULTS: Heat softened gutta percha group showed more push out the bond strength of the bonded posts than the conventional obturation group (p < 0.05). In the middle region, there was no statistical significance between the two groups while there was significance in the coronal and apical thirds. CONCLUSION: The vertical compaction technique and early cementation improved the bond strength of the resin posts in comparison to the conventional obturation technique with late cementation.