Journal of Prosthodontics-Implant Esthetic and Reconstructive Dentistry最新文献

Purpose: To compare the effect of post-and-core material type and production technique on the fracture resistance of teeth.

Materials and methods: Sixty human maxillary central incisors were used for the study. Root canal treatments were performed, and the post cavities were created. The teeth were divided into six groups (n = 10) according to post material and production method: prefabricated glass-fiber post (PF), zirconia post (PZ), titanium post (PT), and CAD-CAM produced glass-fiber post (CF), zirconia post (CZ), titanium post (CT). All post-and-core restorations were luted with resin cement (RelyX U200). Static loading was applied on the luted metal copings using a universal testing machine to measure fracture resistance. The effect of material and production method on fracture resistance was evaluated with two-way ANOVA test. Tukey HSD test was used in post hoc analyses. Significance was evaluated at p < 0.05 level.

Results: In the CAD-CAM post-and-cores, the fracture resistance of zirconia was significantly higher (809 N) than titanium (569 N) and glass-fiber (342 N). In the prefabricated posts, the fracture resistance of zirconia was significantly higher than glass-fiber (445 N), while there was no significant difference between zirconia (605 N) and titanium (538 N) materials.

Conclusion: Zirconia posts demonstrated the highest and CAD-CAM glass-fiber posts demonstrated the lowest fracture resistance compared to other types of post materials. Additional studies are needed to confirm if CAD-CAM glass-fiber posts may be considered an effective alternative treatment.

A long-term successful implant-supported prosthesis requires the creation of a passively fitting framework, based on an accurate intraoral digital implant scan. According to dental literature, splinted implant scan bodies (ISBs) provide higher intraoral scanning accuracy than non-splinted techniques. This technique presents a structured approach for splinting multi-unit abutment scan bodies (MUASBs) using customized manufactured devices to facilitate the recording of definitive intraoral implant scans.

Purpose: To investigate the feasibility and accuracy (trueness and precision) of facial scanning and virtual patient representation (VPR).

Materials and methods: One participant was recruited and informed consent was obtained. VPR was performed 30 times with a custom fabricated intraoral scan body (ISB). Thirteen adhesive markers were added to the face as an extraoral scan body (ESB). Two facial scans were obtained for each VPR using an infra-red laser accessory sensor (Structure sensor; Occipital Inc) mounted on a computer tablet (iPad Pro; Apple Inc), including one with seated ISB and one without ISB. Two maxillary intraoral scans were obtained using an intraoral scanner (Omnicam; Dentsply Sirona) with and without the ISB. All files were imported to a dental software program (exocad; exocad GmbH) and VPR was obtained by aligning the facial and IOS scans using the ISB and ESB as common elements for alignment. Five fiducial face landmarks, four intraoral dental landmarks, and six perioral landmarks were selected for measurements. A total of 32 linear measurements, including 14 face-face (for facial scan accuracy) and 18 face-dental (for VPR accuracy) representing total face, lower face, and perioral regions, were performed directly using a digital caliper (FINO Digital Caliper; FINO GmbH) and virtually on the VPR. Trueness was evaluated by mean absolute difference (MAD) between the virtual and direct measurements, and the standard deviation represented Precision. Statistical analyses were performed with a statistical software package (IBM SPSS Statistics v25; IBM Corp), with α = 0.05. Data were analyzed for normality with Shapiro-Wilk test, and 1-sample t- (or Wilcoxon signed rank test), technical error of measurement (TEM), and relative error magnitude (REM).

Results: The facial scan had 2.04, 1.66, 0.8 trueness, and 1.05, 0.92, 0.91 precision for total, lower face, and perioral regions. VPR had higher MAD (lower trueness) than facial scan, including 3.32, 2.40, 1.21 trueness and 2.2, 1.47, 1.2 precision for total, lower face, and perioral regions. Both TEM and REM were lowest for the perioral region and increased with increasing measurement distance.

Conclusion: Error in face scanning increased with increased distance and intricate details. VPR accuracy was lower than face scan accuracy because of added errors in the alignment process. The investigated VPR workflow might be feasible for treatment planning and smile design. However, it would be unreliable for more demanding prostheses manufacturing purposes.

Purpose: This randomized clinical trial compared 12-month outcomes of narrow platform implants (NP) or regular platform implants (RP) in beds prepared with conventional versus ultrasonic osteotomy and immediately loaded.

Materials and methods: Patients requiring narrow (3.0 mm) or regular (3.75 mm) implants in the upper esthetic zone were randomly allocated for conventional (10 NP, 15 RP implants) or ultrasonic (10 NP, 15 RP) osteotomy. Primary and secondary implant stability, operation time, patient discomfort, and probing depths were evaluated after different time periods.

Results: Implant bed preparation time was longer (p < 0.001) with ultrasonic osteotomy versus conventional drilling (CD) in both RP and NP groups. Post-operative pain was lesser with ultrasonic preparation on postsurgical days 1 (p = 0.022) and 7 (p < 0.001) in the RP group and days 1, 4, and 7 (p = 0.015, p = 0.019, p = 0.003) in the NP group. Secondary stability at 3 months was higher in the NP group with ultrasonic preparation versus CD (p = 0.002). No significant differences in probing depth were found between 3 and 12 months in either group with either technique. The 12-month success rate was 100% in both groups with both preparations.

Conclusions: Regular diameter implants in beds prepared by ultrasonic osteotomy have comparable primary and secondary stability to those in beds prepared by conventional osteotomy and can be immediately loaded, showing a similar 12-month success rate. Narrow diameter implants placed in beds prepared by ultrasonic osteotomy have comparable primary stability values to those in conventionally prepared beds, but implant stability quotient values were always insufficient for immediate loading.

Alar webbing is a functional and aesthetic defect of the nasal structure noted in cleft lip and palate patients (CLP), which is thought to be due to a deficiency in nasal lining tissue. Surgical procedures have previously focused on the removal of lining or alar cartilage leading to worse post-operative defects. This case demonstrates a novel technique of releasing the tissue, followed by using a CAD-CAM splint to help mold the tissue during the healing process to better control esthetics, symmetry, and prevent relapse. The release of scarred tissue using a custom CAD-CAM stent is a promising technique that allows for symmetric healing and an overall aesthetic surgical result for patients.

Purpose: This study aimed to investigate the effect of crystallization and finish line curvature on the integrity of lithium disilicate crowns fabricated by using partially crystallized (P) and fully crystallized (F) blocks.

Materials and methods: Forty-eight lithium disilicate crowns were fabricated based on the designated lithium disilicate blocks and finish line curvatures. The specimens were divided into four groups (n = 12 each): P block with a curved finish line (PC), P block with a straight finish line (PS), F block with a curved finish line (FC), and F block with a straight finish line (FS). Using the silicone replica technique and triple scan method, the absolute marginal discrepancy was measured at four surfaces. Using the triple scan method, five sections were segmented for each surface. Global deviation was measured by using a best fit alignment. Three-way mixed analysis of variance followed by Fisher least significant difference test and the Kruskal-Wallis test were used for statistical analyses (α = 0.05).

Results: The block crystallization had a significant impact on the marginal integrity in the triple scan method, showing a greater marginal discrepancy in the F block crowns (p < 0.001). The finish line curvature significantly influenced the marginal integrity in both measurement methods, with curved finish line crowns exhibiting a greater marginal discrepancy (p < 0.05). However, the areas with the greatest marginal discrepancies differed depending on the analytical method used.

Conclusions: The marginal discrepancies of the crowns differed according to the fabricated blocks and finish line curvature.

Purpose: To investigate how varying ferrule heights and the number of glass fiber posts affect fracture resistance and behavior of endodontically treated maxillary first premolars with substantial loss of tooth structure.

Materials and methods: Twenty-four extracted endodontically treated human maxillary first premolars were divided into three groups (n = 8) based on ferrule height and post number. The groups were as follows: premolars of 2 mm ferrule height that were restored with single posts (control group), premolars of 0.5 mm ferrule height that were restored with single posts in palatal canals (single-post group), and premolars of 0.5 mm ferrule height that were restored with double posts in palatal and buccal canals (double-post group). All groups were then restored with composite core and metal-ceramic crowns cemented with zinc phosphate cement. All specimens were subjected to 10,000 thermal cycles at temperatures of 5°C and 55°C, as well as 1.2 million cyclic loadings of 49 N load at 1.2 Hz using a chewing simulator. The specimens were loaded to fracture in a universal testing machine and fracture behavior was examined under stereomicroscope and divided into restorable and unrestorable fracture modes. Fracture loads and modes were analyzed by one-way ANOVA, Tukey's post hoc test, and Fisher's exact probability test (p ≤ 0.05).

Results: The control group showed the highest mean fracture load (1127 ± 172) of all groups (p < 0.001). The specimens in the single-post group showed numerically higher mean fracture load (522 ± 171) but with no significant difference compared to the ones in the double-post group (518 ± 157; p > 0.967). In the control group, 75% of specimens showed unrestorable fractures compared to 50% and 12.5% in single-post and double-post groups. The specimens in the control group had similar unrestorable fractures, starting from the coronal part and extending obliquely to the cervical third of the root below resin level. Two specimens in the control group showed unrestorable fractures in the middle third of the root. No middle-third root fractures were observed in single-post and double-post groups, and unrestorable fractures in both groups were similar to those of the control group. The single-post group had two specimens with core-post crown complex restorable fractures, while the control and double-post groups had one specimen each. The remaining specimens showed cervical-third root restorable fractures above resin level.

Conclusion: The ferrule height significantly influences the fracture resistance of endodontically treated premolars compared to the number of placed posts. Nonetheless, more restorable fractures are seen in endodontically treated premolars restored with double posts than single posts regardless of ferrule height.

Purpose: To assess the impact of staining and multiple firings on the mechanical, optical, and surface characteristics of zirconia-containing lithium silicate ceramics (ZLS).

Materials and methods: Ninety ZLS discs (Suprinity, VITA Zahnfabrick) were divided according to the "Number of firings" protocol: Ctr-control, no characterization; SC-single firing cycle (for characterization, crystallization and staining simultaneously); and DC-double firing cycle (crystallization firing cycle was performed separately from the staining firing). Extrinsic pigmentation was performed to replicate the characterization of a monolithic restoration. A layer of stain and glaze was applied with a fine brush to the ceramic surface. Specimens were fired two or four cycles, designed to simulate additional staining firings for potential characterization adjustments, but without applying new stain, resulting in six groups (n = 15): Ctr_II, Ctr_IV, SC_II, SC_IV, DC_II, and DC_IV. X-ray diffraction, color, translucency, and surface roughness analysis were also performed, and the samples were subjected to the biaxial flexural strength test. Data were subjected to one-way ANOVA, Tukey's test (α = 0.05), and Weibull analysis.

Results: No changes in the diffractogram pattern were found, irrespective of the number of firings. The translucency (p = 0.02) and roughness (p < 0.01) of DC_IV were significantly reduced compared to DC_II. DC_IV also showed the highest flexural strength (325.52^AMPa), followed by SCII (271.64^BMPa).

Conclusions: Repeated firings increased the flexural strength of ZLS, where the double-step characterization technique demonstrated better statistical results than the other groups. Moreover, despite the ceramic showing good color stability, repeated firings significantly compromised its translucency.